A method for reducing the cost of emission control by utilizing a combination of low cost, combustion and post-combustion processes to eliminate emissions of sulfur and nitrogen oxides, and trace metals, including mercury, and trace dioxins and furans. These processes are applied sequentially to the combustion flow train of an air-cooled, slagging combustor-boiler, and include two groups of process steps. One group is implemented in the combustor and the other in post combustion zones.

1. Field of the Invention
The invention relates to reduction of sulfur and nitrogen oxides and volatile trace metals from coal and solid fuel combustion in furnaces and boilers and a method of use.
2. Description of Related Art
Due to increasingly stringent and very costly emission regulations in recent decades, coal utilization has remained essentially constant in the U.S., despite its abundance and stable pricing. Historically, the primary concern has been emissions to the atmosphere of sulfur dioxide (SO2), nitrogen oxides (NOx), and ash particulates. In the past several years, the allowable emissions from these three pollutants have been further reduced. In addition, new requirements have been proposed, especially the emission of mercury, which is found in coal in minute quantities in the range of 20 to 100 parts per billion (ppb).
Many technologies have been developed and are available for commercial use to control each of these pollutants to the most stringent levels now being proposed by the U.S. Environmental Protection Agency (EPA). However, the common feature of these technologies is high, to extremely high, capital and/or operating costs. Historically, the favored approach has been to integrate the control processes for SO2, NOx, and particulates in the exhaust ducting of the boilers. This approach was also extended to adding controls for mercury and dioxin/furans to this same exhaust duct region. However, this has proven to be very costly because certain reactions are slow at these low temperatures, thereby necessitating large components. Also, it is known that some processes interfere with others, thereby necessitating further complexity in the process design. For example, mercury and dioxin/furan reduction improves as the temperature of the gases decreases below the acid dew point of SO2 and HCl. However, these acids corrode metal walls.
The overall result of applying current control methods to meet new regulations for coal fired power plants, which will require NOx reductions to 0.15 lb/MMBtu, 90% mercury removal, while maintaining existing SO2 reductions, has been estimated by EPA and the U.S. Department of Energy (DOE) to cost about $10 per megawatt-hour (MWH). This equals to 40% of the historical average, wholesale price of electricity of $25/MWH. To this cost must be added the probable future cost for reducing greenhouse gas emission, primarily carbon dioxide, CO2, which is produced in greater quantity from coal combustion than oil or natural gas.
In consequence of these high costs for pollution control, there has been in recent decades an almost total shift toward the use of natural gas for new electric power plants. However, natural gas is far less abundant than coal, and it also serves large existing markets, such as domestic and commercial heating. The problem with relying on natural gas as a power plant fuel was demonstrated in the economic recession of 2001 when the wholesale price of electricity decreased to its low historical level in the $25/MWH range, while the price of natural gas, with its multiple uses, remained relatively high. As a result, operators of natural gas fired-power plants were faced with declining revenues and high fuel prices. The economics of municipal waste incineration for waste disposal and energy recovery were also adversely affected by costly environmental regulations with the result that waste is now preferably disposed in landfills, with the result of future pollution from methane gas emissions from said sites.
As mentioned, known art has focused on treating the pollutants primarily in the exhaust ducting of boilers and furnaces. While the goal was to achieve an integrated approach, the reality has been that major pollutants have been treated with separate processes. While this approach will generally meet the most stringent current and proposed regulations, their implementation does not lead to any economic benefit from integration. For example, Selective Catalytic Reduction (SCR) will, in one step, reduce NOx to meet the most stringent regulations. However, it is extremely costly, and it offers no benefit to the control of SO2, or mercury. The result has been, as noted above, that EPA and DOE estimate meeting current and proposed emission regulations for NOx, SO2, and mercury will cost $10/MWH, which equals to 40% of the historical wholesale price of electricity of about $25/MWH.
Some of the volatile metals released during combustion, such as mercury and arsenic, can pass through fabric filters or ESP's (ElectroStatic Precipitators) into the atmosphere. The EPA has proposed using Best Available Control Technology (BACT) to remove the mercury emitted from U.S. coal burning plants. According to EPA's Reports to Congress ("Mercury Study Report to Congress, Vol. VIII (EPA-452/R-97-01010), December 1997 and "Air Pollutants from Electric Utilities-Report to Congress", (453/R-98-004a), February 1998 (hereinafter referred to as "EPA")), coal burning plants emit to the atmosphere about 33% of the mercury (Hg) emitted in the U.S. The DOE's current estimate is that removing 90%, or 37 tons of Hg, would cost about $5 billion, or $70,000/lb of Hg removed, or add $5/ton to the cost of U.S.'s coal production. Municipal solid waste (MSW) combustion systems account for 19%, or 27 tons of Hg emissions in the U.S. However, due to their higher concentration and different combustion process the cost of Hg removal is only, according to EPA, $11 to $47 million, or $211 to $870/lb of Hg.
It is critical to sharply reduce the cost of Hg removal from coal-fired power plants in the U.S. because the EPA reports (loc. cit.) state that Hg emission is a global atmospheric problem. Of the 5,000 to 5,500 tons emitted per year, 1000 tons are from natural sources, 2000 tons are re-emitted from prior years, and 2,000 tons are new emissions. Of this total, the U.S. emits only 3% (120 ton) and the U.S. coal fired power plants emit 1% (about 41 ton). By coincidence, 35 tons, which almost equals the total U.S. coal plant emissions, deposit in the U.S. from worldwide Hg emissions. Therefore, the U.S. would benefit directly by reducing global Hg emissions in Asia, whose power plants and other furnaces use the very high (up to 40%) ash coals.
The currently favored mercury emission process for coal fired power plants and MSW plants is injection of activated carbon with various spray injectors into the combustion gases flowing through the ducts upstream of the ash particle removal equipment (EPA, loc. cit.). One problem with this method is that injection must take place at gas temperature above the dew point for acid condensation from sulfur and nitrogen compounds and HCl in the gas, typically above 350° F. At these higher temperatures the mercury reduction effectiveness and also of dioxin/furans by activated carbon is greatly reduced. As the gas temperature is lowered the capture of Hg by activated carbon improves dramatically, with almost total removal measured at gas temperatures of about 220° F. It is, therefore, necessary to remove all the acid producing species, primarily sulfur and nitrogen oxides and chlorine, prior to cool down of the combustion gases to the temperatures below the acid dew points. In fact, as will be discussed below, it appears that the primary benefit in the prior art of injecting lime in large and complex spray dryers systems to reduce dioxin/furan emissions and improve mercury removal is to eliminate the corrosion from acid condensation at the low temperatures at which dioxin/furan emission reduction is effective.
In addition, the presence of other trace species that are in much higher concentrations in the gas stream, including SO2 and volatile trace metals, can attach to the porous activated carbon particle surface and prevent the gettering of the Hg. This is a critical deficiency in the use of activated carbon injection because the infinitesimal mercury concentration competes with far more numerous other species that can attach to the carbon. Sharply reducing these other species in the activated carbon injection zone is thus required.
A consequence of the above noted deficiencies for high Hg reductions are the need for extremely high carbon to Hg ratios. This results in replacing one environmental air emission problem with a future water and solid emission problem because mercury contaminated carbon must either be recycled or properly landfilled. To address this issue, EPA is turning to "life cycle assessment" or "cradle to grave" emission control to assure that removal of a pollutant from air, for example, does not create a water or solid waste problem.
To quantify this problem, one solution to mercury removal is coal washing at the mine that can remove up to 60% of the Hg with advanced deep cleaning processes [EPA, loc. cit.]. However, the Hg is deposited in large slurry ponds near the coalmines, and it may leach out to the water supply in the future. Similarly, the Hg removed in stack equipment of coal-fired power plants with the currently favored activated carbon injection processes require anywhere from 100's to 34,000 more carbon than Hg, (according to EPA), or 100,000 times more carbon, according to the DOE (EPA loc. cit.). This would replace 37 tons of Hg removed from the stack gases with 1 to 3+ million tons of mercury containing, solid waste. EPA (loc. cit.) estimates that this could increase electricity costs by around $2/MWh, while DOE estimates around $5/MWh, which equals 8% to 20% of the current wholesale electricity price of $25/MWh. EPA's (EPA, loc. cit) review of the many processes that remove mercury from stack gases all rely on some form of capture by specially prepared carbon, ranging in cost from activated carbon costing about $1,000/ton to proprietary compounds that cost 20 times as much.
Even if these mercury control technologies are adopted in the U.S., other volatile trace metals, such as lead or arsenic, or even minute traces of radioactive trace elements in coal ash, must also be removed from atmospheric emission. Furthermore, the deposition of these materials on U.S. soil from coal combustion overseas must be addressed because mercury from overseas deposits on U.S. soil and in the Pacific Ocean fisheries, whose fresh fish are eaten in Pacific Coast States. There is a greater than anticipated health risk from mercury as just reported in a study of 116 persons (Jane M. Hightower, "Study of Mercury in People's Blood", Journal of Environmental Health Perspectives, Nov. 1, 2002) that ate more that 2 servings per week of fish, 89% had mercury levels above the 5 ppm recommended by the National Academy of Sciences.
Trace Metal Removal in the Air-Cooled, Cyclone Coal Combustor
Vitrification converts the fly ash that contains leachable toxic metals, such as arsenic and lead, into a chemically inert glassy material that can be used beneficially, (B. Zauderer & E. Fleming, "Air Cooled Cyclone Coal Combustor to Convert Ash to Inert Slag", DOE SBIR-DE-AC01-88ER80568, Phase 1 Final Report, Mar. 13, 1989; Phase 2 Final Report: Jul. 13, 1992) and (2. B. Zauderer & E. Fleming, "A Cyclone Coal Combustor to Convert Municipal Incinerator Ash to Inert Slag", Final Report EPA-SBIR Contract 68D90117, Apr. 30, 1991.). A key element of fly ash vitrification process was to prevent the re-evolution of volatile trace metals in the fly ash into the combustion gases in the air-cooled combustor. These trace metals were in two forms: one was trace metals that had remained trapped and dispersed throughout the ash particles during the original coal particle combustion in the power plant, and the other consisted of volatile metals that had condensed onto surfaces and internal pores structure of the fly ash particles in the stack gas stream and on the ash captured on the surfaces of the baghouse or ESP.
A "kinetic vitrification" process is based on the concept that the simplest and lowest cost method of limiting volatile metal emission to the atmosphere is to prevent them from evolving from the ash particles during combustion. As ash particles melt during combustion the volatile metals diffuse to the ash surface and vaporize. Therefore, to retain most of the volatile metals inside the ash particle or droplet it is essential to limit its residence time in the hot combustion gas. This is accomplished by the centrifugal force from the swirling combustion air that forces ash droplets to the liquid slag covered combustor wall. Since the volatile metals can still diffuse back to the liquid slag surface on the wall and re-evolve into the combustion gases, the slag must be rapidly drained into a water-cooled quench tank. Theoretical analysis (Zauderer & Fleming, loc. cit.) of the diffusion process in ash droplets and the slag layer show that this is feasible in a cyclone combustor whose refractory liner is air-cooled with the liners' solid surface in contact with the slag at the slag melting temperature.
As described in Zauderer & Fleming (loc. cit.), the time dependent diffusion equation for the time of evolution of a volatile metal from a spherical liquid slag droplet in the known range of particle size distribution is solved to determine the radial concentration of a trace metal. It is assumed that the concentration of the species, such as Hg, is uniformly dispersed in the sphere. The total loss of metal, e.g. Hg, is computed for the time of flight between fly ash particle injection to impact of the ash particle or droplet on the liquid slag covered combustor wall. The next step in the analysis is to solve the same diffusion equation for the liquid slag layer on the combustor wall. The solution provides the trace metal evolution from the slag layer. Here the total time is the slag layer drainage time, which is computed from the integrated, time dependent solution for viscous Stokes flow on the combustor wall. Air-cooling allows variation of the liner surface temperature as the slag melting temperature varies with different coal ashes. Additional variability in slag layer residence time is obtained by injection of calcium oxide based particles with the coal, which changes the slag viscosity.
The testing of this kinetic vitrification process was implemented in DOE and EPA projects (Zauderer and Fleming, loc. cit.) in which fly ash from a coal power plant and from a municipal incinerator were vitrified in Coal Tech's 20 MMBtu/hr, air-cooled combustor (Zauderer, U.S. Pat. No. 4,624,191, Nov. 25, 1986). As shown schematically in FIG. 1, the injected air from a pressure blower provides a swirling flow whose centrifugal force drives particles and droplets into the liquid slag layer that lines the inner combustor wall. Firing coal that is pulverized to 80% (by weight) passing a 200 mesh, results in about 75% of the ash that remains solid or is liquefied in the combustion gas being driven into the slag layer in the wall. The slag is drained through a slag tap at the downstream end of the combustor's floor, (FIG. 1). Ash particles as small as 10 microns impacted the slag layer within the 4-foot axial length of the combustor wall, with said particle or droplet transit time equal to or somewhat less than the combustion gas transit time of 80-millisecond in that combustor. Larger particles impact the wall sooner. For example, a 20-micron particle impacts the slag layer within 20 milliseconds, while a 50-micron particles impacts within 10 milliseconds.
Particles smaller than 10 microns will escape even from an air-cooled combustor twice as long, namely 8 feet, as was verified with such a combustor that has been in operation at Coal Tech Corp's facility in Philadelphia, Pa. since 1995. Therefore, retention of volatile trace metals in the fly ash tests cited above, whose mean particle size was somewhat under about 10 microns, was more difficult to achieve than with larger ash particles, except at very high swirl. Nevertheless, significant concentrations of volatile arsenic and lead were retained in the slag in the 20 MMBtu/hr-combustor (See FIG. 2). This was accomplished by operating the inlet swirl air pressure at 40 inches water gage (w. g.) where 90% of the ash was retained in the slag layer in the 4-foot long, combustor wall.
The theoretical analysis requires knowledge of diffusion data for these elements in the slag. For this purpose experimental data on the diffusion of sulfur and oxygen atoms in liquid metal oxide slag was used. It was determined that almost all the volatile metals could be retained in liquid ash droplets as small as 20 microns during the 20 millisecond interval between injection and slag layer impact. Even 10 micron-particles, which equaled the mean size of the fly ash used in the tests, retained (according to the analysis) 44% of volatile atoms in the 80 milliseconds interval from coal particle injection to slag layer impact.
The second critical step in kinetic vitrification is to prevent the re-evolution of the volatile metals captured in the slag layer during the time a liquid ash droplet or ash particle impacts the slag layer to its removal through the slag tap into the water filled quench tank. A slag element's residence time in the 20 MMBtu/hour air-cooled combustor's slag layer ranges from a few minutes to almost 30 minutes, depending on the slag layer thickness, slag layer temperatures, viscosity and slag mass flow rates. Again, using the O2 or S diffusion coefficients in liquid metal oxides as representative of volatile metals, e.g., As or Pb, but this time in a planar slab layer with a slag layer thickness of 2 millimeters and a surface temperature of 2300° F., it was computed that almost all volatile metals would remain in the slag if the slag residence time on the combustor wall was about 3 minutes, or less.
The above discussion of controlling the emissions of volatile trace metals, including mercury, focused on preventing their evolution from the ash particles and liquid ash droplets during their time of flight from injection inside the coal particles to their release during combustion and impact and dispersal in the slag layer on the combustor wall.
Sulfur Capture With Limestone or Lime Injection into a Slagging Cyclone Combustor
Several groups conducting research on different designs of slagging combustors in the late 1970's to early 1980's discovered independently that the injection of limestone into a slagging coal combustor would reduce the SO2 emissions. One group conducted tests in a 1 MMBtu/hr air cooled combustor (C. S. Cook, et. al, "Evaluation of Closed Cycle MHD Power", Final Report, U.S. DOE Contract Mo: DE-AC01-78ET10818, November 1981) and (B. Zauderer, "Sulfur Capture with Limestone Injection in Cyclone Combustion Flows", National Science Foundation Final Report, Grant No: CPE-8260265, Apr. 15, 1983, Hereafter "Zauderer-NSF") in which 25% to 30% SO2 reduction was measured at the stack with limestone injection at a high Ca/S mol ratio of 9 to 1. The combustion gas residence time was about 50 m.sec. Another group (J. Stamsel, et. al., "TRW's Slagging Combustor System Tests" in 6th International Coal Utilization Conference, Houston, Tex. November 1983) also reported 10 to 45% capture with Ca/S mol ratios of 1 to 6.
These results were puzzling because the gas temperatures in slagging combustors is about 3000° F., while the reaction of calcined limestone, CaO, with SO2 to form CaSO4, reverses above about 2200° F. Furthermore, above this temperature melting of the particle's surface blocks access of SO2 gas molecule to the internal pore structure of the calcined particles, where almost the entire CaO—SO2 reaction occurs. Also, the published data for this "pore structure" reaction of CaO with SO2 in the temperature below 2200° F. showed that the reaction times needed for SO2 capture by CaO were in the range of 1 second, while the typical gas transit times in slagging combustors was generally under 100 m.sec. (Zauderer NSF, loc. cit.).
Zauderer suggested one possible explanation (Zauderer, NSF and Zauderer, "Analytical Investigation of Sulfur Capture and Slag rejection in Cyclone Coal Combustors", Final Report, U.S. DOE Contract No. DE-AC22-82PC50050, Jan. 17, 1983) for the rapid sulfur capture, namely, that it occurred primarily near the injection zone of the coal, limestone, and air into the combustor. Rapid volatilization of the coal particles releases the organic matter in the coal, including the sulfur, resulting in ignition and heatup under locally high excess air conditions. Consequently, the local gas temperature is lower than the final gas temperature of about 3000° F. However, the temperatures are high enough to rapidly heatup and calcine the limestone or lime, resulting in an internal porosity that is substantially greater than the values reported in the literature with slow calcinations. Furthermore, the heatup rates of the CaO particles lag that of the combustion gases, and it is the surface temperature of the CaO particles that control the reaction with SO2. Therefore, the combination of a cooler initial combustion zone, a slower CaO heatup rate compared to the gas, and the greater particle porosity, all result in substantially greater sulfur capture than would be predicted by slower reactions under equilibrium gas and particle temperatures, as would exist in large boilers.
Since the smaller CaSO4 particles remain entrained for greater axial distances in the combustor they enter the final gas temperature region where the sulfur capture reaction should begin to reverse. This effect is reduced by the swirl of the gases that drives the particles into the slag layer where they melt and trap the sulfur. However, this latter effect is counterbalanced by the low solubility of sulfur in slag. It is, therefore, essential to remove the slag within several minutes.
The analysis of the time intervals for these gas phase and liquid slag phenomena were discussed above in connection with the vitrification of the volatile trace metals in coal ash. In fact, the capture of volatile trace metals by injected particles into the combustor would be governed by the same phenomena. The particles in the 10 to 100 microns size range remain entrained in the combustion gas from several milliseconds to 100 milliseconds, and that particles under 10 microns will be carried out of the combustor through the exit nozzle, and that the slag layer residence time in the combustor must be within a few minutes to prevent volatile gas re-evolution. This entire process for sulfur capture is described in Zauderer, ("Method of Optimizing Combustion and the Capture of Pollutants During Coal Combustion in a Cyclone Combustor", U.S. Pat. No. 4,765,258.)
J. A. Woodroffe and J. S. Abichandani ("Sulfur Equilibrium Desulfurization of Sulfur Containing Products of Combustion", U.S. Pat. No. 4,922,840, May 8, 1990) describe a sulfur capture process similar to Zauderer (U.S. Pat. No. 4,765,258), which they define as a "super equilibrium" process. Their application is to a toroidal, slagging combustor in which the coal, limestone, and air are all injected tangentially along the outer diameter of a "pancake" shaped combustor. The gases and slag are removed through an opening at the central bottom of the combustor. They teach the use of small particles of a mean size of 325 mesh and greater than 10 microns, and a 25 to 35 millisecond residence time in the combustion chamber. The two major deficiencies in their approach is that the toroidal combustor results in immediate injection into the nominal 3000° F. gases which greatly reduces the available time during which the CaO particles are in the colder temperature range where SO2 capture is favored. Furthermore, they fail to note the need for rapid slag removal to prevent sulfur re-evolution from the slag.
It has been difficult to achieve repetitive results and to optimize the sulfur capture process in the slagging combustor due to the competing reactions all of which occur within the combustor. For example, Zauderer reported (B. Zauderer, et. al., "Status of Coal Tech's Air Cooled Slagging Combustor", in 2nd Annual Clean Coal Technology Conference, Atlanta, Ga., Sep. 8, 1993, Vol. 1, pp. 467-482) 70% SO2 reduction measured at the stack in tests in the 20 MMBtu/hour, air-cooled combustor with limestone injection at a Ca/S mol ratio of 4. However, a sampling probe at the combustor exit revealed that only 19% of this reduction occurred inside the combustor, with the balance occurring in the cooler, 2000° F. and lower, post-combustion zone downstream of the exit. This result suggested that despite transit through the 3000° F. gas temperature, the calcined CaO particles retained their pore structure, which is necessary for substantial SO2 capture, without "dead burning", i.e. melting of the CaO particle surface. However, 80% SO2 reduction was measured during the same test series by injecting more reactive lime into the immediate post-combustion zone (nominal 2000° F. gas temperature) in the boiler, (See FIG. 1). The mean particle size of lime is about 10 microns, compared to about 74 microns for the limestone injected into the combustor. This lower temperature and smaller particle sizes account for the about 33% greater effectiveness of lime than limestone in sulfur capture in the combustor.
These tests were repeated (B. Zauderer, et. al, "Small, Modular, Low Cost Coal Fired Power Plants for the International Market", in 7th Clean Coal Technology Conference, Tampa, Fla., January 1997) in a second-generation design of the 20 MMBtu/hour air-cooled combustor whose internal diameter was also 2.5 ft., but whose axial length was doubled to 8 feet, which resulted in a longer gas residence time. This resulted in major improvements in slag retention in the combustor in that all the slag was drained through the slag tap, as opposed to substantial slag flow out of the exit nozzle into the boiler. Slag flow out of the exit nozzle into the boiler has a much longer residence time at high temperature, which allows all the sulfur in the slag to re-evolve into the gas phase. In this longer combustor, with essentially no slag flow out of the combustor into the boiler, sulfur capture was higher, averaging 60% to 75% at Ca/S mol ratios of less than 3. Also, sulfur retention in the slag improved with values in the 10% to 20% range, which was measured in a high, 37% Indian ash coal. There the slag flow rates were in the 300 to 400 lb/hr range. However, this sulfur concentration in the slag did not represent a major fraction of the sulfur removed in the combustor by lime or limestone injection because the analysis of sulfur re-evolution from hot slag required slag mass flow rates above 500 lb/hr in order to limit the slag residence times in the combustor to 3 minutes.
In summary, a general observation from the prior art on sulfur capture in slagging combustors is that the published results do not teach how the process should be applied to large commercial scale (20 MMBtu/hour or greater) slagging combustors. The data shows a wide range of SO2 reduction with no clear correlation on how the process would scaleup or how to optimize it. High SO2 reductions have been reported; however, the relationship of these reductions to the removal of the reacted sorbent has been overlooked except in the prior work of Zauderer, who reported results of captured sulfur reporting to the slag. Also, Zauderer reported that in some cases, a significant part of the sulfur capture occurred in the immediate post-combustion zone with no evidence that transit of larger calcined limestone particles through the 3000° F. gas temperature in the combustor caused substantial "dead burning" of the particles, which would limit their sulfur capture effectiveness. Zauderer also attempted to isolate the capture and retention parts of the process by injecting gypsum as a sulfur gas generator in order to study the relationship of high slag mass flow rates on sulfur capture. Zauderer also used fly ash and more recently, high (70%) ash rice husk gasifier waste for this purpose. However, while a trend was established between increased slag flow and increased sulfur retention in slag, the total capture of 20% of the injected sulfur in the slag was still low.
Separately, in connection with using the air-cooled slagging combustor for mercury removal, EPA reported (EPA, loc. cit.) that the high ash residue in advanced coal-washing plants remove up to 60% of the mercury in the raw coal. It is almost certain that this mercury is in the inorganic ash, where retention of volatile trace metals within the ash particles released during coal particle combustion phase was found by Zauderer to be effective.
Injection of Activated Carbon for Mercury Reduction in the Combustion Gas Stream of the Boiler or Furnace Exhaust Ducting
As shown by analysis and tests (B. Zauderer & E. Fleming, DOE Contract: DE-AC01-88ER80568, loc. cit.) even at very high swirl in the air-cooled cyclone combustor, 10% of the ash mass, consisting of particles less than 10 microns, will exit the combustor. Also some fraction of the mercury in the organic part of coal will escape the combustor. It is therefore, necessary to add an additional process, such as the injection of various types of getters, either activated carbon or calcined lime, upstream of the particulate capture devices. Prior art (EPA, loc. cit) has shown that depending on factors, such as coal and ash type, reagent type, etc., most of the mercury can be removed from the gas stream. However, current injector schemes even with activated carbon that is enhanced with sulfur or iodine will in most cases require extremely high (up to 100,000 to 1) carbon to initial mercury mol ratios (EPA, loc. cit.).
Removal of SO2 and NOx from the Post Combustion Gas Stream
As noted above, Zauderer has developed and tested (B. Zauderer, "Method of Reducing NOx in Combustion Effluents" U.S. Pat. No. 6,048,510) a variable droplet size injection method that disperses droplets of a reagent of ammonia or urea dissolved in water throughout gas volumes ranging from the 20 MMBtu/hr boiler to 100 MWe power plant boilers. Since vaporization proceeds from the droplet surface inward, larger droplets penetrate deeper into the gas. Specialists in the field call this process Selective Non-Catalytic Reduction (SNCR). In 1997, coal-fired tests in the post-combustion zone of the 20 MMBtu/hour-boiler with these injectors resulted in NOx reductions from 1 lb/MMBtu by as much as 80% to 0.2 lb/MMBtu when the combustor operated under fuel lean conditions. Operating the combustor under fuel rich conditions reduced NOx from 1 lb/MMBtu to 0.4 lb/MMBtu. This was followed by the injection of SNCR in the post combustion zone that further reduced NOx to as low as 0.07 lb/MMBtu.
The identical injector design was also used by Zauderer (B. Zauderer, "A Method for Combined Reduction of Nitrogen Oxide and Sulfur Dioxide Concentrations in the Furnace Region of Boilers", U.S. patent application Ser. No. 09/964,853, Sep. 29, 2001) to spray droplets containing a mixture of lime and urea into the 20 MMBtu/hr-combustor and immediately downstream of the combustor at gas temperature of about 2000° F. SO2 emissions were reduced by 80% while simultaneously reducing NOx. When added to the SO2 removed in the combustor with lime injection (B. Zauderer. U.S. Pat. No. 4,765,258) essentially all the SO2 is removed.
Another post combustion process for reducing NOx is called "reburn" in which additional fuel is introduced into fuel lean post-combustion gases in order to convert them to fuel rich conditions. This greatly reduces NOx as reported by Zauderer (B. Zauderer, "Reduction of Nitrogen Oxides by Staged Combustion in Combustors, Furnaces, and Boilers", U.S. Pat. No. 6,453,830 B1). The latter invention disclosed the use of oil, biomass, and coal-water slurry as the "reburn" fuel. In tests conducted with the first two fuels, 50% NOx reductions were measured in tests in the 20 MMBtu/hour air-cooled cyclone combustor. The "reburn" NOx reduction is additive to staged combustion inside the combustor and to the SNCR reduction in the post-combustion zone.
Removal of Chlorinated Hydrocarbons-Primarily Dioxins and Furans from the Combustion and Post-Combustion Gas Streams
The chlorine in coal and in municipal solid waste results in the formation of dioxins and furan. However, the chlorine in coal is generally between 10 to 100 times lower in concentration than in municipal waste incinerators because the latter contains plastics that have substantially higher chlorine concentrations. The dioxins/furans are formed in the combustion zone at gas temperatures in the 2000° F. to 3000° F. range and separately in a narrow range in the post-combustion zone during regular gas cool down in the exhaust ducting below about 600° F. to 700° F. Zauderer performed a series of tests in the 20 MMBtu/hour combustor-boiler in which coal was co-fired with various amounts (up to 50% of the total mass flow rate) of a shredded municipal refuse derived fuel (RDF) (B. Zauderer, et. al, "Tests on Co-Firing of Coal and Refuse Derived Fuel (RDF) in A Slagging Cyclone Combustor Attached to a Package Boiler", Coal Tech Corp., Merion, Pa. Report, Apr. 8, 1991, unpublished). The dioxins/furans were measured both inside the boiler and in the stack exhaust, and subsequently analyzed by Rossi, et. al. using EPA Method 23 (L. Bonfanti, et. al., "PCDD/Formation and Destruction from Co-Firing and RDF in a Slagging Combustor", ENEL-Nuclear Research Center, Pisa, Italy, July 1992, Also in a paper presented at an International Environmental Conference, Lisbon, Portugal, 1992). The chlorine in the RDF was 10 times (0.5%) greater than that in the coal (<0.1%). With 40% RDF-60% Coal (mass flow) the dioxin and furans were about 60 times greater at the stack (almost 1,500 ng/NM3) than with coal only.
They were also measured with a water-cooled, suction gas probe inserted from the rear of the boiler, parallel and within several inches from the side wall. Here, dioxin/furan readings were 4 times higher than in the stack. However, gas sampling of SO2 and NOx in coal fired combustion tests 6 years later by Zauderer (unpublished) with the same probe and in the same boiler clearly showed that sampling at that location was not representative of the much hotter core combustion gas stream in the boiler. This non-uniformity was also confirmed in 3-dimensional modeling of the gas conditions in this boiler (S. Brewster, in a Report on DOE Contract DE-AC22-91PC91162). Consequently, the dioxin/furan samples taken in the boiler cannot be correlated to a specific gas state.
A major problem with these coal-RDF co-firing tests was the non-uniformity of the RDF feeding, which resulted in sharp periodic (order of 1 second) fluctuations in the visible flame inside the slagging combustor. It was believed that the high dioxin/furan emissions measured were due to these non-uniformities, a point also noted by others. This threw into question the stack gas results from the coal-RDF co-firing tests. To address this issue of uniform feeding, a series of tests were performed several years later (B. Zauderer, "Control of Dioxin Emissions from Waste Fuel Combustion by Co-firing with Coal", DOE-SBIR Phase 1 Project Final Report, Contract: No: DE-FG05-93ER81554, Mar. 24, 1994). To assure uniform feed, calcium chloride pellets were used as a chlorine source, instead of RDF, and it was co-fired with the same 0.1% chlorine coal as previously. The chlorine level was increased in several steps to as high as 2.6% of the total injected mass flow, equal to 5 times greater than the Cl in the RDF. Nevertheless, even with 2.6% chlorine injection, the dioxin level measured at the stack was only 30 ng/Nm3, the same as with the 0.1% chlorine, coal test. This strongly suggested that non-uniform combustion is a major factor in dioxin formation.
In another test in which the calcium chloride injection produced a 1.2% chlorine mass flow rate, lime (calcium hydrate) was co-injected. The total calcium from both chemicals resulted in a total Ca/Cl mol ratio of 6.9, while that due to Ca(OH)2 alone was 3.4. The addition of calcium hydrate lowered the dioxin level by 45% and the furan by 12% compared to the baseline test without the lime. It also reduced the SO2 emissions by 72%.
In a report on the correlation of stack gas temperature with dioxin/furan emissions for several large municipal waste incinerators in Denmark (V. Boscak & G. Kotynek, "Techniques for Dioxin Emission Controls" in Proceedings of Municipal Waste Combustion Conference, Tampa, Fla., Apr. 15, 1991, Sponsored by EPA & Air & Waste Management Association, pp. 383-397) the measured reduction of the sum of the dioxin and furan emissions were lowered by a factor of 1000 to a little over 1 ng/NM3 as the stack gas temperature was reduced from 230° C. to 120° C. However, the results reported by Boscak are not directly comparable to Zauderer's results because a spray dryer absorber, with a presumably relatively long, single pass, gas residence time, into which a lime slurry was injected with a special injector, was installed upstream of the fabric filter leading to the stack.
Boscak also reported that injection of activated carbon or activated hydrated lime had no effect on these emissions. The lack of effect by these two species suggests that the lime's main function was mostly limited to neutralizing the acids formed from sulfuric acid and hydrochloric acid as SO2 and HCL are cooled below the acid dew point, and that the quenching of the gas stream by the water spray was the primary factor in lowering the dioxin/furan concentrations. This is a reasonable conclusion because the dioxin/furan reduction increased as the temperature was lowered, which indicates increased spray water flow and more rapid gas cooling. If this assessment is correct, it means that the use of such large spray dryers is a costly method for neutralizing these acids whose presence would corrode the ductwork. In any case, the results clearly indicate that stack gas temperature was the primary driver to the dioxin/furan reduction.
A spray dryer operates at low temperatures where the reaction between SO2 and HCl with lime is very slow and as a result a long residence time is needed for the reaction to proceed, which requires a large vessel. Prior art by Zauderer was cited above for removing the sulfur at high temperature. This type of spray dryer has been installed in a number of large (as much as 2000 tons/day of MSW) European and American MSW incinerator facilities. Brown and Felsvang (B. Brown and K. S. Felsvang, "Control of Mercury and Dioxin Emissions from U.S. and European MSW Incinerators by Spray Dryer Absorption", Municipal Waste Combustion Conference, Apr. 15, 1991, pp. 675-705) presented results on dioxin/furan and mercury reduction in five MSW and RDF incinerators that used one type of spray dryer. Clarke also presented a technical paper on the same results of dioxin/furan and mercury reduction obtained in a Swiss MSW incinerator that was also reported by Brown, (M. J. Clarke, "A Review of Activated Carbon Technologies for Reducing MSW Incinerator Emissions" in Municipal Waste Combustion Conference, Tampa, Fla. [loc. cit.] April 1991, pp. 975-994).
Both review papers isolate the effect on adding activated carbon injection upstream of the lime slurry-spray dryer for both pollutants. A general comment on the three technical papers is that the presentation format provides test results, but little if any correlation to incinerator operating conditions. For example, the composition of the MSW and its heating value, which can vary widely even within one day are not given. In fact, the very wide variation in input conditions to the spray dryer reported in the last two papers validates the assessment that the MSW composition and probably combustion operating conditions varied widely. The absence of this information, which was certainly collected during the test, provides no guidance on the possible impact of combustion conditions on the magnitude of the emissions.
For present purposes, as noted above, all three papers report that the low temperature was the key factor in reducing dioxin and furan emissions. However, in contrast to Boscak, the other two papers report that the addition of activated carbon immediately upstream of the spray dryer in a 400 ton/day Swiss MSW incinerator reduced dioxin/furans by 98.9% to 5 ng/NM3 at the ESP outlet from 455 ng/NM3 at the lime-slurry drier inlet at 120° C. (248° F.). In the prior test without the carbon injection, the reduction was 75% to 69 ng/NM3 at the ESP outlet from 277 ng/NM3 at the dryer inlet. Note that the carbon injection was 59 milligram/NM3, which yields a ratio by weight of carbon to the incremental (over the spray drier) dioxin/furan reduction of 922,000 to 1. The ratio based on the dioxin/furan concentration at the inlet to the spray dryer was 130,000 to 1. However, since a large fraction of the dioxin reduction was due to rapid cooling of the stack gases, the contribution of the carbon to the total reduction is not known, only the incremental reduction can be totally quantified. This incremental removal of 34 grams per year of dioxin/furans, results in about 31,000 kg/yr of dioxin/furan impregnated carbon, which is dispersed in the fly ash, and requires proper landfill disposal. Since the U.S.-EPA regulation for MSW incinerators is 30 ng/NM3, as opposed to an apparent limit of under 5 ng/NM3 in Europe, it would appear that improvements in combustion performance combined with stack gas cooling should be sufficient to lower the emissions from 69 ng/NM3 to the U.S. limit without the need for activated carbon injection and its solid waste disposal requirement.
A qualitative measure of the ratio of activated carbon to pollutant can be obtained from the mercury reduction tests that were also conducted in this Swiss incinerator. The mercury emissions also decreased with decreasing outlet duct gas temperature from 140° C. to 110° C. The injection of lime in the spray dryer also contributed to gettering mercury. At 140° C., the Hg reduction across the spray dryer is 28%, while at 110° C. it was 43%. Injecting 30 mg/NM3 at 110° C., doubled the Hg reduction to 87%. In this case the carbon caused an incremental reduction of Hg of 105 μg/NM3 from which a carbon to Hg weight ratio of only 285 is deduced.
It thus appears that cooling of the stack gases is a far less costly process, than activated carbon injection for dioxin/furan removal. Also, use of a large spray drier vessel is a costly method of accomplishing said cooling. Furthermore, Boscak's reported lack of improvement in dioxin/furan reduction by use of activated carbon injection, while achieving an even lower emission of 1.4 ng/NM3 with only the lime slurry spray drier, suggests that activated carbon may not be necessary for dioxin/furan control. However, Boscak emphasized the importance of uniform combustion in removing excess ash from furnace walls that contain dioxin/furans, and removing fly ash at gas temperatures above 300° C., which reduces the catalytic effect of copper in said fly ash on dioxin/furan formation.
The alternative of applying to coal fired power plants the prior art from MSW incinerators of large spray driers with lime injection for acid neutralization would be quite costly because MSW plants have generally much lower thermal inputs than coal fired power plants. For example, the Swiss MSW plant had a capacity of 400 tons of MSW per day, which translates at best to less than 250 MMBtu/hr. This would equal to a very small 25 MW coal fired power plant. This may be one reason why DOE estimates (EPA, loc. cit.) that mercury removal for coal fired power plants would cost $70,000 per lb of Hg removed, while EPA states that said removal is 5 to 10 times less costly for MSW incinerators (EPA, loc. cit.). The MSW cost estimate is in general agreement with the prior MSW plant estimates cited above in which a costly spray dryer was used. Due to the low chlorine level in coal, dioxin/furan emissions, which are caused by chlorine in the coal, are much lower, and as yet not subject to regulation in coal fired power plants.
In 1994, Zauderer proposed (Zauderer, "DOE-SBIR Phase 2 Proposal to DOE Contract: No: DE-FG05-93ER81554", unpublished) follow-on tests to validate this stack gas temperature effect and its relation to uniform combustion by replacing the calcium chloride source of chlorine with polyvinyl chloride pellets that would better simulate municipal solid waste. While the tests were not implemented, in September 2001 a pair of tests were implemented by Zauderer on a 90 MMBtu/hour, mass burn, municipal incinerator in Pennsylvania, which partially validated both the key role of uniform combustion in the primary flame zone on dioxin/furan emission levels and the importance of reducing stack gas temperatures on the magnitude of said emissions.
The prior art has shown that the major pollutants emitted during coal and MSW combustion, namely SO2, NOx, particulates, mercury, dioxins and furans, can be individually sharply reduced to below the current and proposed EPA regulatory levels. However, prior art reduction processes have little synergism between the individual pollutants, and each is quite costly. For example, SO2 reduction with a wet scrubber has little in common with NOx reduction with Selective Catalytic Reduction (SCR), or with mercury reduction with activated carbon.
While some prior art approaches may generally meet the most stringent current and proposed regulations, their implementation does not lead to any economic benefit from integration. For example, Selective Catalytic Reduction (SCR) will, in one step, reduce NOx to meet the most stringent regulations. However, it is extremely costly, and it offers no benefit to the control of SO2, or mercury. The result has been, as noted above, that EPA and DOE estimate meeting current and proposed emission regulations for NOx, SO2, and mercury will cost $10/MWH, which equals to 40% of the historical wholesale price of electricity of about $25/MWH.
Finally, the review of the prior commercial technology strongly suggests that the use of activated carbon for the control of dioxin/furans and mercury consisted of adding components to equipment that was apparently originally installed for SO2 and HCl emission control. However, this equipment, such as the spray dryer are large components, which are obviously costly. It is interesting that the three references cited in connection with their use contain no information on cost. Cost is the final determinant in use of any technology.

Reduction of sulfur, nitrogen oxides and volatile trace metals from combustion in furnaces and boilers


A domestic appliance includes a pump that establishes and directs a flow of washing fluid into a tub during a washing operation. The pump includes a pump housing having a rigid main body portion that defines an inlet section and an outlet section, as well as a plurality of resilient members that are over-molded onto the inlet and outlet sections. The rigid main body portion includes a mounting element for supporting the pump. An insulation grommet is positioned in the mounting element to minimize any transfer of vibration from the pump to the appliance. The inlet nipple, outlet nipple and insulation grommet are joined through a plurality of web members. The rigid main body also includes a secondary outlet section that is adapted to directly receive a hose or is connected to a hose through a secondary outlet nipple.

1. Field of the Invention
The present invention pertains to the art of domestic appliances and, more particularly, to a domestic appliance including a pump having a pump housing that is over-molded with a plurality of resilient members.
2. Discussion of the Prior Art
Incorporating pumps into domestic appliances, such as dishwashers, washing machines and the like is widely known. In general, the pumps are employed to generate a flow of liquid, typically washing fluid, to clean laundry, dishes and the like. The pumps are either unidirectional, i.e., the liquid is simply pumped from a tub as in the case of a conventional washing machine, or bi-directional, i.e., the liquid is recirculated in the tub as in the case of a dishwasher. Regardless of the particular type, pumps are generally connected to the tub using a resilient hose connection. That is, in order to minimize vibrations transmitted between the pump and the tub, as well as to provide a simple method of connection, the pump is coupled to the tub through a resilient hose.
Often times, the hose will include sharp bends in order to accommodate various connection points. More specifically, as appliances become more and more sophisticated, room within the appliance to accommodate various components is reduced. Thus, often times, the hose is required to include a sharp bend in order to reach between the pump and the tub. In any case, hose clamps are used to secure the hose to both the pump and the tub. That is, a clamp is provided at each attachment point, i.e., at both the pump and the tub, in securing the hose so as to prevent any leaks.
While manufacturers have employed resilient hoses for some time, certain drawbacks in their use exist. More specifically, hoses, having multiple connections, create the potential for multiple leak points. In addition, mounting and installing multiple connections increases the overall cost and complexity of manufacture. Moreover, the sharp bends created in the hoses create inefficiencies in fluid flow that require the pump to work harder.
Based on the above, despite the existence of pumps in the prior art, there still exists a need for an improved pump arrangement for use in a domestic appliance. More specifically, there exists a need for a pump assembly having minimal connection points that is easy to manufacture, install and service.


A lens holder which supports a projection lens is screwed and fixed to a bracket which supports a spatial light modulator. A positioning pin configured to position the lens holder in a left-right direction with respect to the bracket is inserted into a long hole which is formed in the bracket and extends in a lamp front-rear direction. The screwing and fixing is performed in a state where the positioning pin is inserted into the long hole and is appropriately moved in the lamp front-rear direction, so that the lens holder is restricted from being displaced in a left-right direction with respect to the bracket, and it is possible to finely adjust a positional relationship between the projection lens and the spatial light modulator in the lamp front-rear direction.

As described in Patent Literature 1, there is known a vehicle lamp configured to emit light from a light source toward a front side of a lamp via a spatial light modulator and a projection lens.
There is also known an illumination device in which a spatial light modulator and a support board which supports a peripheral edge portion of the spatial light modulator from a rear side are electrically connected, and an illumination device in which a reflective spatial light modulator and a control board are electrically connected in a state where the control board is abutted against a peripheral edge portion of the spatial light modulator from a rear side.
There is also known an in-vehicle spatial light modulation unit which includes a spatial light modulator. Patent Literature 1 describes a spatial light modulation unit of a vehicle lamp which includes a spatial light modulator configured to reflect light from a light source toward a projection lens.
There is also known a spatial light modulation unit in which a spatial light modulator and a support board which supports a peripheral edge portion of the spatial light modulator from a rear side are electrically connected.
There is also known an in-vehicle lamp unit configured to emit light from a light source reflected by a spatial light modulator toward a front side of the unit via an optical member, such as a projection lens.

Vehicle lamp with particular attachment of spatial light modulator to heat sink


A method for etalon suppression in a gas detection device by determining an etalon fringe period during a calibration step without gas in dependency of the DC drive current. A measuring signal which is a function of the gas absorption and substantially independent of an intensity modulation of an initial light signal at an initial frequency (f) is generated by determining a first pre-measuring signal when the laser source is operated at the center of the gas absorption peak, a second pre-measuring signal when the laser source is operated with a DC drive current below the gas absorption peak of the gas to be detected, and a third pre-measuring signal when the laser source is operated with a DC drive current above said gas absorption peak, with a difference between said DC drive currents which corresponds to the etalon fringe period determined in a calibration step before. The final measuring signal is determined as the difference between the first pre-measuring signal and the arithmetic mean of the second pre-measuring signal and the third pre-measuring signal.

The present invention concerns in particular low-cost infrared (IR) gas detection as disclosed in WO 2005/026705 A1.
The gas detection method and gas detector device as described in this prior art publication is based on a source formed by a wavelength modulated Vertical Cavity Surface Emitting Laser (VCSEL) or Distributed FeedBack (DFB) laser and uses the fact that the modulation of the wavelength is directly connected to a modulation of the laser source output intensity. The intensity of the light having passed the gas volume and being incident to the detector therefore shows a first modulation related to the laser source intensity and a second modulation related to the gas absorption as the wavelength is scanned across the gas absorption line. Accordingly, the known detection method and device provides an initial light signal by a wavelength modulated laser source.
The source provides an initial light signal, which is wavelength modulated with an AC modulation signal at a given initial frequency (f) at the absorption line around the gas to be determined. A light sensor respectively is arranged at the periphery of a detection region intended for receiving at least a gas the concentration of which is to be determined. The light sensor receives a resulting light signal formed by the initial light signal having passed through the detection region. In the following a detection signal is formed which is substantially proportional to the time derivate of the resulting light signal. Further disclosed are first means for generating a first modulation reference signal at the given frequency (f) and second means for generating a second modulation reference signal at twice this frequency (2f). The detection signal is multiplied by the first modulation reference signal and then integrated over time in order to provide a first measuring signal which is a function of the intensity of said initial light signal and substantially independent of the concentration of said gas. The detection signal is further multiplied by said second modulation reference signal and then integrated over time in order to provide a second measuring signal which is a function of the gas absorption and substantially independent of an intensity modulation of the initial light signal at the given initial frequency. The final measuring signal is then received by dividing the second measuring signal by the first measuring signal, thereby providing a signal relative to the concentration or the presence of a given gas. This gas detector method and device have the advantage that only a single sensor unit is needed for one laser source. All necessary information for determining a precise gas concentration value is given by the processing of the generated detection signal which is proportional to the derivate of the light signal received by the sensor unit after having passed through a sample of the defined gas.
The first and second reference modulation signal both are in phase with the intensity variations of the initial light signal. With this known measurement technique the detector signal is time derivated, and the derivated signal is fed into a two-channel lock-in amplifier. The first channel operates on the modulation frequency f, and the output signal is proportional to the slope of the optical power as function of the laser current. The second channel operates of twice the modulation frequency and its output gives a signal, which is proportional to the gas concentration encountered by the laser beam. The ratio of the measuring signal at the frequency 2f to the measuring signal at the frequency f gives the absolute concentration of the gas independent of the laser output as the measuring signal at the frequency f contains information about the laser intensity under the assumption that variations of the laser intensity stem from optical degradations in the light path, such as dust, condensation, speckles. This assumption only holds for two conditions:
1. The laser does not show mode hopping, i.e. sudden changes of wavelength. If such a mode hopping occurs, the wavelength has to be re-adjusted by a change of the DC laser current, which in turn changes the laser output power. With a VCSEL the slope, which is measured by the signal at the frequency f does not necessarily change accordingly. In the case of a DFB laser, the output power is strictly proportional to the DC current which gives the same signal at the frequency f for different output powers.
2. The temperature of the laser is exactly stabilized. For a change of the laser temperature, the wavelength changes, which in turn leads to a re-adjustment of the DC laser current to stay centered on the wavelength of the gas absorption line. Such a change of the current means an intensity change as described in item 1.
With the method described in the prior art patent application, the signal based on a modulation reference signal at the frequency f shows a slope around the center of the gas absorption line, which is proportional to the gas concentration. At high gas concentrations, the accuracy of the measurement is limited by the accuracy of the DC laser current of which the error influences the modulation reference signal at the frequency f. Variations of the current will cause variation of the laser signal, and this effect increases with concentration. This shows, that for some applications this prior art method and device is quite demanding in terms of temperature control of the laser, and depends very much on the thermal mounting of the latter. DFB lasers and VCSEL's differ very much in their thermal budget so that the tracking of the gas absorption line, which is always necessary in term of DC current, has to include a temperature tracking as well.
The co-pending U.S. patent application Ser. No. 11/227,477 describes a first modulation reference signal at twice of said initial frequency is generated by respective means, whereby said first modulation reference signal has a 45° phase angle to said initial light signal. This first modulation reference signal oscillates at an amplitude level between amplitude levels 1 and 0 and is different from the amplitude level of the second modulation reference signal. Finally the detection signal directly received from the resulting light signal is multiplied with the first modulation reference signal. Thus, the first modulation reference signal is not measured on the frequency f, but on the frequency 2f with a slight modification of the 2f modulation reference signal in the amplitude levels and a phase shifting of 45° between the first modulation reference signal and the initial frequency, which is necessary to provide the same phase which is obtained by a derivate over time. Further, the detector signal is no longer derivated but directly fed to the lock-in amplifier for generating a first measuring signal, which is a function of the intensity of the initial light signal. The resulting signal is directly proportional to the light intensity of the laser as seen by the detector without gas absorption (i.e. including any degradations of the light beam between laser and detector). Further it is proposed to combine this first 2f modulation reference signal and its signal treatment with other treatments in order to obtain stable final measuring signals dependent on the special application of gas detection. In a further embodiment, the second modulation reference signal is generated at twice of said initial frequency f, whereby the first and second modulation reference signals have the same phase correlation to the initial light signal; therefore both signals have 45° phase angle to the AC modulation signal for the laser source. Further, the second modulation reference signal oscillates between amplitude levels 1 and −1. For generating the second measuring signal the detection signal directly received from the resulting light signal is multiplied via lock-in amplifier with said second modulation reference signal. The final measuring signal is obtained by the above-mentioned ratio. In this embodiment the final measuring signal is obtained by a first and a second measuring signal based on a 2f modulation reference signal, both obtained with a detection signal directly received from the resulting light signal. In an other embodiment the second modulation reference signal is generated at twice of said initial frequency f, whereby said second modulation reference signal is exactly in phase with the intensity variations of said initial light signal. The detection signal generated by said detection means is substantially proportional to the time derivate of said resulting light signal and the second measuring signal is generated by multiplying said detection signal with said second modulation reference signal. This signal treatment shows the best result, which is independent from the laser temperature and sudden wavelength changes. In this embodiment also the final measuring signal is obtained by a first and a second measuring signal based on a 2f modulation reference signal, but the second measuring signal, which is a function of the absorption is obtained with a derivated detection signal. In a further embodiment, which needs more electronic parts, two reference modulation signals at a frequency f and 2f are used for generating two measuring signals, which are a function of intensity of the initial light signal. This is realised by generating, additionally to the first measuring signal based on the first 2f modulation reference signal, a third measuring signal, which is also a function of intensity of said initial light signal. This third measuring signal is generated from a detection signal by multiplying the detection signal with a third modulation reference signal at the initial frequency f and then integrated over time. Further the second measuring signal is generated from said detection signal, by multiplying said detection signal with a second 2f modulation reference signal at twice of said initial frequency f and then integrated over time. The third and second modulation reference signals are exactly defined in phase with the intensity variations of said initial light signal and the detection signal for both measuring signals are substantially proportional to the time derivate of the resulting light signal. The final measuring signal is obtained by correlating the first and third measuring signal and generating the ratio between the second measuring signal and the correlated signal of the first and second measuring signal.
Generally speaking, in wavelength modulation laser spectrometry, the laser wavelength is modulated at a modulation frequency f. After transmission of the light through the gas sample to be measured, the laser light is incident onto a photo detector. In general, the signal of the photo detector is fed into a phase-sensitive lock-in amplifier and the gas concentration is related to the photo detector signal on twice the modulation frequency (2f detection).
The 2f detection is limited by various noise sources: laser intensity noise (which partly can be compensated for by measuring the laser intensity);
electronic noise stemming from the photo detector and/or the amplifying circuitry;
optical interference-based noise.
The optical noise based on interference can take the form of speckles or of etalon fringes. Speckles are interference patterns created by the diffraction of the coherent laser light at irregularities like dust, dirt etc. Speckles are not the object of this invention.
Etalon fringes are caused by portions of the light, which are back-reflected from optical interfaces within the designed light path (i.e. windows, lenses, mirrors etc.). As the back-reflected parts of the laser light are in coherence with the laser beam, the interaction of back-reflection and propagating laser light can create a standing wave within the cavity of the gas absorption device (i.e. the free-space absorption path containing the gas to be measured).
If the length of the cavity is changed, the amplitude of the standing wave at the location of the photo detector will vary between periodical minima and maxima as a function of the cavity length. The same effect can be obtained if the cavity length is held constant and the wavelength of the laser light is changed. The periodical variation of the light amplitude with cavity length or with laser wavelength is called "etalon fringes". FIG. 1 shows in diagram (a) etalon fringes of a methane gas detector with zero gas concentration (note that the electronic noise floor is not resolved in this graph) and in diagram (b) the same device as in (a) with methane present. The etalon fringes are about the same size as the gas absorption signal at the center of the absorption peak.
In a real-world gas detection device, the variation of the length of the cavity stems from thermal expansion of its mechanical members. As an example, with a thermal expansion coefficient of steel (10 ppm/° C.), a mechanical length of 10 cm and a temperature of operation from 0° C. to 50° C., the cavity changes its length by 5 micrometers. This variation of length corresponds to 3 to 4 times the laser wavelength and can therefore create massive etalon fringes. The etalon fringes are not directly correlated to the intensity of the laser and can therefore not be compensated by measuring the laser intensity.
The period of the etalon fringes on the ambient temperature or the laser wavelength (drive current) is a function of the length of the geometrical cavity, which creates the etalon fringes: The longer the cavity, the shorter the etalon fringe period. For a gas detection device based on a Vertical Cavity Surface Emitting Laser (VCSEL), the etalon fringe period is on the same order than the gas absorption peak (in wavelength) if the etalon fringe generating cavity has a length of several centimeters, which is the typical length of an absorption path. Very small cavities, i.e. the window of the laser cap, generate etalon fringes, which have periods longer than the entire tuning range of the VCSEL. In such a case, the signal variations with ambient temperature resemble a change of the signal offset.
A gas detection device will always contain optical interfaces (at least the laser chip will be sealed hermetically underneath an optical window), and operational conditions will always create a thermal expansion. Therefore, most gas detection devices based on wavelength modulation spectrometry are limited in their lower detection limits by etalon fringes rather than by electronic noise. Etalon fringe suppression is thus a key element in the increase of the performance (accuracy, precision, detection limit) of a gas detection device.
The state of the art knows several techniques for the suppression of etalon fringes.
The first technique consists in the periodical variation of the position of one of the optical components within the gas detection device, preferentially of a mirror. Such a variation can be implemented for example by placing the mirror onto a piezoelectric positioning device and driving said device by an AC voltage (the frequency of the AC voltage being different from the frequency of wavelength modulation). The overall effect of such an implementation is that the etalon fringes undergo a variation by their full amplitude with time. As long as the time constant of the photo detector's amplifier is significantly higher than the period of the piezoelectric AC drive voltage, the amplifier's output signal will average across all possible etalon fringe amplitudes so that changes in the etalon fringes due to thermal expansion do not have any effect. For any given optical setup, the piezoelectric AC drive voltage can be optimized in frequency and in amplitude in order to maximize the etalon fringe suppression.
A second means to suppress etalon fringes consists in modulating the laser wavelength at a second frequency, which has no relation with the original modulation frequency. In a similar way as in the technique described above, the change of the wavelength due to the second modulation causes a temporal variation of the etalon fringe amplitude, which will be averaged by the photodiode's amplifier, provided that amplifier's time constant is significantly higher than the period of the second wavelength modulation. Similarly, the amplitude and frequency of the second wavelength modulation needs to be optimized for maximum etalon fringe suppression for a given optical arrangement.
Other etalon fringe suppression techniques make use of the slow scan in wavelength of the gas absorption peak (while applying the fast wavelength modulation). Here, etalon fringe amplitude and period are numerically calculated from the obtained scan of the 2f signal, which allows them to be cancelled out. The main drawback of this technique is the necessity to acquire a wavelength scan of the 2f amplifier signal across the gas absorption peak, which implies a very slow measurement cycle.
A common point of all etalon fringe suppression techniques is that there is no absolute suppression technique, and that the main performance limitations of most gas detection devices stem from residual etalon fringes. FIG. 2 shows in diagram (a) residual etalon fringes of an oxygen detector (with zero oxygen concentration) which employs a second, independent wavelength modulation (the residual etalon is about 3 times larger than the electronic noise floor) and in diagram (b) the same device as in (a) with three oxygen absorption peaks.
In view of this, it is the object of the present invention to provide an etalon fringe suppression technique for gas detection, which is less dependent from the temperature and sudden wavelength changes.
Based on this etalon suppression technique it is a further object of the invention to provide a method and device with an easier generation of said first measuring signal which is a function of the intensity of said initial light signal and substantially independent of the concentration of said gas.

Gas detection method and gas detection device


An integrated circuit includes a substrate layer and a resistor bank in a polysilicon layer disposed on the substrate layer. The resistor bank includes a plurality of resistor elements having a body portion extending in a longitudinal direction. A metal line is disposed in a metal layer above the polysilicon layer to extend transverse to the longitudinal direction and across the body portion of a group of the plurality of resistor elements, thereby forming a first region of the resistor bank and a second region of the resistor bank. The first region is separated from the second region by the metal line. A resistor device having a predetermined resistance includes a subset of the resistor elements in the group electrically coupled together in the second region. The resistor device also includes first and second terminals located in the same first or second region of the resistor bank.

Integrated circuits, including electronic circuits on semiconductor material, are commonly used in a variety of applications such as in computers, televisions, and mobile telephones. Depending on the application, the integrated circuit may be designed according to specific requirements. The design of an integrated circuit includes several steps, including a physical design or layout step in which a circuit pattern is drawn and converted to lithography before being transferred onto silicon. A metal layer is commonly included in the physical design to facilitate electrical connections between components of the circuit. A physical design may include several metal layers connected with vias, depending on the complexity of the design and the number of components included in the design, in order to facilitate the electrical connections when a single metal layer may not be able to provide sufficient surface area to facilitate all of the necessary electrical connections. Including several metal layers in an integrated circuit design, however, may be costly.

Integrated circuit with single level routing


A mouthpiece of a brass instrument is provided. The mouthpiece of the brass instrument can cause lips to vibrate efficiently while having a throat of the size allowing to produce a loud sound so that the brass instrument is made easier to blow, durability is improved, and excellent sound quality can be generated with improved sound production in high tone and low tone areas.

1. Field of the Invention
The present invention relates to a mouthpiece of a brass instrument held to one's mouth when a trumpet, trombone, or the like is used.
2. Description of the Related Art
There are various types of brass instruments and, for example, a trumpet is one typical instrument thereof. In a general trumpet, lips vibrate due to a breath blown by a player to generate a sound wave. The sound wave repeatedly travels back and forth in the instrument at the speed of sound and a portion thereof is discharged from the bell.
Incidentally, the mouthpiece is an important part through which air is blown while the mouthpiece being held to one's mouth and includes, as described in Japanese Patent Application Laid-Open Nos. 5-127665, 10-214080, and 2004-61573, each part of a rim, cup, shoulder, throat, back-bore, and shank.
According to Japanese Patent Application Laid-Open No. 5-127665, for example, a mouthpiece is formed from a material of titanium or a titanium alloy, or zirconium or a zirconium alloy as a mouthpiece that is lightweight and will not rust and also provides a tone that is different from conventional one.
According to Japanese Patent Application Laid-Open No. 10-214080, an upper half of a rim is formed to be positioned at a location apart from a player by a predetermined distance with respect to a lower half of the rim so that even a player having occlusion in such a way that lower front teeth are positioned toward the player from upper front teeth when viewed from the player can play in a horizontal form.
According to Japanese Patent Application Laid-Open No. 2004-61573, a satin surface constituted by fine innumerable irregularities is formed on an outer circumferential surface of rim where lips come into contact, the front, and an inner surface of a cup so that a mouthpiece becomes soft on lips, a slip can be prevented to prevent an error caused by a slip during performance, and also fatigue caused by performance can be mitigated.
Various techniques of the mouthpiece of a brass instrument held to one's mouth have been proposed, as described above, but the cup, shoulder, throat, and backbore directly relate to a sense of resistance and a problem of a conventional mouthpiece to be solved is that when lips are fatigued, lips may not vibrate so that no sound is produced.
Particularly, it is generally known that the best place to obtain a moderate sense of resistance is only the throat, places where sound pressure is maximal for all sounds are only the cup and throat, and blowing resistance decreases with an increasing throat diameter and conversely increases with a decreasing throat diameter so that a moderate sense of resistance helps the player, but no technique concerning the throat has been disclosed.
The Bernoulli's theorem of "If the flow rate goes up, pressure drops" is known and applying this theorem to a phenomenon that occurs in a throat part of a mouthpiece yields "If the flow rate goes up by making the throat smaller, sound pressure drops". From the standpoint of a player, this means that if the throat is made smaller, lips vibrate more easily with increasing blowing resistance, but a loud sound cannot be produced.
The throat has been completely round with a smooth surface and only the throat diameter is changed, for example, in accordance with the brass instrument.
The present invention has been made in view of the above circumstances and an object thereof is to provide a mouthpiece capable of causing lips to vibrate efficiently while having a throat of the size allowing to produce a loud sound so that a brass instrument is made easier to blow, durability is improved, and excellent sound quality can be generated with improved sound production in high tone and low tone areas.

Abstract: A user of the mouthpiece may feel blowing resistance because a breath more than necessary has been blown to obtain moderate blowing resistance for the user. However, by using helpful blowing resistance (reflected pressure) causing lips to vibrate easily by a resistance part formed at least in a portion of an inner wall area of the throat, lips are allowed to vibrate efficiently, the user can perform easily, and the user is made less fatigued. Also, high tones can now be played, stable low tones are obtained, and the sound itself becomes deep and impressive.


A combined fluid pressure and temperature sensor device 10 has a variable capacitor (14) formed of a rigid substrate (14a) and flexible diaphragm (14b) attached thereto in sealed, spaced apart relation by an annular glass seal (34). The capacitor is received in a fluid passage chamber (12e) of a housing (12) having a fluid port (12b) for coupling to a fluid pressure source to be monitored. A connector (20) mounting transducer terminal pins is received in an open end of the housing with an electric circuit chamber (20d) formed between the connector and the variable capacitor which receives signal conditioning circuitry (26). A temperature responsive thermistor (32) is disposed, in one embodiment, on the exposed face of the diaphragm and is provided with electrical traces (32a, 32b) which go through apertures 14k, 14j) in the diaphragm into electrical contact with connection pads on the substrate within a glass enclosed window (34k, 34j). Traces (32e, 32f) extend from the connection pads through the glass seal to additional glass enclosed windows (34g, 34h) for connection with respective pins (30d, 30e) extending through the substrate to form a hermetic seal between the thermistor (32) and the signal conditioning circuit chamber through the annular glass seal. Additional embodiments include a leaded thermistor (42) positioned in the fluid pressure port (40), a leaded thermistor in a protective sleeve adapted to project into a fluid body (50), a leaded thermistor in which the leads are bent to place the thermistor adjacent to the diaphragm (60), a thermistor mounted on a heat conductive probe with a thermistor proximate to the diaphragm and with the probe extending therebeyond (70) a thermistor received on the substrate through an aperture in the diaphragm in a closed glass window (80) and a thermistor combined with a monolithic variable capacitor (90).

This application relates generally to condition responsive sensors and more particularly to combined fluid pressure and temperature sensor apparatus.
Fluid pressure responsive capacitive transducers comprising a variable capacitor mounted in a fluid chamber having a thin ceramic diaphragm exposed to the fluid so that changes in fluid pressure cause concomitant changes in the position of the diaphragm to thereby cause a change in the capacitance of the capacitor are well known in the art. Transducers of this type are shown and described, for example, in U.S. Pat. No. 4,716,492, the subject matter of which is incorporated herein by this reference. In that patent, a thin ceramic diaphragm is shown mounted in closely spaced, sealed, overlying relation to a ceramic substrate. Metal coatings are deposited on opposing surfaces of the diaphragm and base to serve as capacitive plates arranged in predetermined closely spaced relation to each other to form a capacitor. Capacitor terminal pins having one end connected to the capacitor plates are mounted in bores extending through the substrate with an opposite end connected to signal conditioning circuitry disposed in an electric circuit chamber at an opposite surface of the substrate. A connector body of electrical insulating material, received over the signal conditioning circuitry, mounts transducer terminals extending into the electric circuit chamber for connection to the signal conditioning circuitry. Capacitance is converted by the circuitry to an output voltage related to the fluid pressure. The capacitor is received in a suitable housing having a fluid receiving port and is provided with a fluid seal enabling the transducer to be used with fluid pressures up to 10,000 psi or higher.
In certain applications it is desirable to measure the temperature of fluid as well as pressure. Although it is known to provide temperature sensors in a separate or stand alone housing, it would be desirable to combine both functions in the same housing so that both measurements can be obtained at essentially the same location as well as to provide savings of cost and space. One of the problems in providing a device combining both functions is that of providing a seal between the electrical leads of the temperature sensing element and the interconnection with the electrical circuit means of the device in order to prevent leakage of the fluid being sensed, particularly at relatively high pressures, while still being able to accurately sense the temperature of the fluid within a satisfactory response time and without impairing the pressure sensing function. Sealing the temperature sensor by overmolding techniques addresses the leakage problem; however, it results in a relatively slow response time and an inherent temperature gradient between the medium being sensed and the sensing element. Sensors which are directly exposed to the fluid medium generally have an epoxy seal for the sensor leads; however, due to leakage problems, these are limited to use with relatively low pressure fluid systems.

Combined pressure responsive transducer and temperature sensor apparatus


A bangle or handle for supporting a mobile station that includes a continuous loop of resiliently compressible material. A portion of the length of the handle is configured to fit within a channel defined in a housing of the mobile station. A second length portion extends from the housing to form a loop of the handle that can be gripped by the user, or otherwise used to suspend the mobile station. The handle may also include a conducting element that extends through the loop and is in communication with a conducting contact of the loop. The conducting contact of the continuous loop can be positioned in overlying contact with a conducting contact of the housing of the mobile station. Such contact supplies power or signals to, and receives power or signals from, a device such as a light, fan, noise generator or camera, connected to the second length portion.

1. Field of the Invention
The present invention is related to the field of mobile stations, and more particularly to the field of tethers, handles and other accessories that facilitate transport of mobile stations.
2. Description of Related Art
Participants in the mobile telephone industry are in a constant search to differentiate their telephones by making them easier to use and more aesthetically appealing. For example, accessories have been developed for mobile telephones that facilitate their handling by providing tethers, lanyards or handles. In one instance, a tether includes a length of cord defining a loop and having a fastener on one end extending between and attaching the loop and a housing of the mobile telephone. In this manner, a user of the mobile telephone can extend their fingers, or even entire hand, through the loop so that the mobile telephone dangles from their fingers or wrist.
Tethers, handles and lanyards can have additional functions beyond facilitating handling of the mobile telephone. For instance, PCT publication WO 01/22526 to Ritter ("Ritter") discloses a mobile telephone with a yoke antenna. In particular, as shown in FIG. 1 of Ritter, the telephone includes a housing 10 and a yoke 25 consisting of two metal wires 21, 22 and a non-conductive connecting portion 23. The yoke has ends that attach to corners 17, 18 of the housing so as to form a loop. In addition to being able to support the rest of the mobile station, the metal wires serve as separate transmitting or receiving antennas.
Despite the advantages of the above-listed devices, further improvements in the aesthetic appearance, ease of use and transportability of mobile stations are always desirable. Therefore, it would be advantageous to have a handle for a mobile station that facilitates handling of the mobile station while at the same time providing additional useful functions.

Handle for a mobile station and method of using the same


The variable valve gear for an internal combustion engine includes a cam lobe that is rotatably supported by a cam drive shaft, and a variable valve mechanism that includes a drive arm fixed adjacent to one end of the cam lobe in the cam drive shaft, an eccentric shaft member that is swivelably supported at a position opposite to the cam lobe with respect to the drive arm in the cam drive shaft, has an outer circumferential surface eccentric to an axis of the cam drive shaft, and is adjustable in eccentricity, and an intermediate rotary member that is rotatably supported through a bearing member around the eccentric shaft member, and is connected to the drive arm, wherein the drive arm includes an end face that overlaps with an end face of the bearing member, when projecting along the axis of the cam drive shaft, and the end face of the drive arm is protruding further than the end face of the cam lobe toward the bearing member.

1. Field of the Invention
The present invention relates to a variable valve gear for an internal combustion engine, which varies the open period of a valve.
2. Description of the Related Art
Regarding a reciprocating engine (internal combustion engine) installed in an automobile, a variable valve gear has been developed, which varies a valve-open-period according to the operational state of the engine in order to properly control the valve characteristics of intake and exhaust valves.
Many variable valve gears of this type have a configuration in which a cam lobe that is rotatably fitted onto the outer circumferential surface of a camshaft (cam drive shaft) supported by a cylinder head is combined with a valve-open-period variable mechanism that varies the rotational velocity of the camshaft at predetermined cycles to transmit the rotation to the cam lobe, as disclosed in Japanese Patent Gazette (Laid pen No. 10-280925). A lot of valve-open-period variable mechanisms have an Oldham coupling structure in which a drive arm is fixed onto the outer circumferential surface of the camshaft at a position adjacent to the cam lobe; an eccentric shaft is fitted to the outer circumferential surface of the camshaft at a position adjacent to the drive arm to be eccentrically rotatable; and a harmonic ring (intermediate rotary member) is rotatably fitted to the outer circumferential surface of the eccentric shaft. More specifically, the valve-open-period variable mechanism employs a structure that drives the valve by transmitting the constant velocity rotation of the camshaft, which is outputted from the drive arm, to the harmonic ring by using an input-side transmission member, changing the constant velocity rotation into non-constant velocity rotation that is changed in velocity at a predetermined cycle, and transmitting the rotation from a boss, which is protruding from the outer circumference of the end of the cam lobe, to the cam lobe by using an output-side transmission member. To phase-shift the axial position of the eccentric shaft from that of the camshaft adjusts a delay or advance of a rotational phase of the cam love relative to a rotational angle of the camshaft, and varies the valve-open period.
In order to place the valve-open-period variable mechanism in a limited area between each adjacent cylinders of the cylinder head, the mechanism has a structure in which the boss protruding from the outer circumferential surface of the end of the cam lobe is disposed close to a lateral portion of the drive arm in parallel with the lateral portion to carry out the transmission of the rotation from the harmonic ring, and the harmonic ring is supported by the eccentric shaft having a little larger external diameter than the camshaft located in the inside of an input gear portion of the variable mechanism.
As disclosed in the Japanese Patent Gazette, the valve-open-period variable mechanism is provided with a bearing portion such as a needle bearing in between the outer circumferential surface of the eccentric shaft and the inner circumferential surface of the harmonic ring for the purpose of smooth rotation of the harmonic ring.
The bearing portion can be displaced in an escaping direction, or more concretely, toward the cam lobe due to a change of the harmonic ring's movement (in result of a change in an eccentricity direction).
The displacement of the bearing portion disables the reliable support of the harmonic ring. Furthermore, the displacement causes abnormal abrasion. The bearing portion is disposed in a position eccentric to the camshaft to support the harmonic ring, and the boss of the cam lobe is located adjacent to the drive arm coaxially with the camshaft. Because of this displacement, the end face of the bearing portion repeatedly faces the end face of the drive arm and faces the end face of the boss of the cam lobe during the rotation of the harmonic ring. Especially the boss of the cam lobe is located outside the drive arm, so that the entire end face of the boss repeats a movement of deviating totally from the bearing portion to the outside and returning to the inside of the bearing portion. For this reason, if the end of the bearing portion, albeit slightly, projects from between the eccentric shaft and the harmonic ring, there generates such abnormal abrasion that the end of the bearing portion and the corner of the end face of the boss interfere with each other when the boss passes the end of the bearing portion.
The bearing portion can be prevented from escaping by employing a structure in which the bearing portion is fixed in between the harmonic ring and the eccentric shaft by press fitting or a structure in which a stopper is independently set in between the harmonic ring and the eccentric shaft.
In the case of the press fitting, however, it is difficult to reliably inhibit the axial movement of the bearing portion due to a high elastic deformability of the harmonic ring.
If the stopper is utilized, the bearing portion has to be made short in bearing length (strength decrease of the bearing portion) in order to secure a space for installing the stopper. In result, the sufficient support strength of the harmonic ring cannot be retained, which causes another problem.
A possible way of preventing the abnormal abrasion is to arrange the end face of the drive arm and that of the cam lobe to be flush with each other so that the boss smoothly passes between the end face of the bearing portion and that of the drive arm. Since the drive arm and the cam lobe are separate components and move differently, it is impossible to completely fit the end faces of these components together without a step or a gap. It is thus difficult to avoid the abnormal abrasion.

Variable valve gear for an internal combustion engine

Mitsubishi Jidosha Kogyo Kabushiki Kaisha

Mitsubishi Jidosha Engineering Kabushiki Kaisha


At least one embodiment of this disclosure provides a display apparatus for solving the problem of a low identification precision due to a relatively large distance between the finger and the fingerprint identification device. The display apparatus comprises a display panel and at least one fingerprint identification device. Each fingerprint identification device comprises a plurality of identification units arranged in an array, each identification unit being provided with a photosensitive element. The photosensitive element is used for performing photoelectric conversion of incident light. The fingerprint identification device further comprises a collimating filter layer arranged on a light entrance surface of the photosensitive element. The collimating filter layer comprises a plurality of strip-shaped light guide portions arranged to be spaced and parallel, a longitudinal direction of the plurality of strip-shaped light guide portions being substantially perpendicular to the light entrance surface of the photosensitive element.

The fingerprint of the human body has uniqueness and invariance. Hence, the fingerprint identification technology has the characteristics of good security, high reliability, simple and convenient use, so that the fingerprint identification technology has been widely applied in various fields of protecting personal information security, particularly in a field of display apparatus, such as a mobile phone, a notebook computer, a tablet computer, a digital camera, etc.

Display apparatus including a fingerprint identification device


A manufacturing method of a semiconductor device is carried out as follows. A first mask layer having a first linear opening pattern is formed above the first interlayer insulating layer. A second mask layer having a plurality of second linear opening patterns and first dummy opening patterns is formed above the first mask layer. The plurality of second linear opening patterns are aligned above the first linear opening pattern at given intervals to cross the first linear opening pattern. The first dummy opening patterns are arranged in close proximity to a first pattern remaining region that is present between the second linear opening patterns adjacent to each other. The first interlayer insulating layer that is present below opening patterns obtained by overlap portions of the first linear opening pattern and the second linear opening patterns is etched to form holes.

1. Field of the Invention
The present invention relates to a manufacturing method of a semiconductor memory device and a semiconductor device, for example, a forming method of fine contact holes continuously aligned in a semiconductor memory device.
2. Description of the Related Art
In recent years, with a demand for a reduction in size and realization of high functions of a semiconductor device, miniaturization of, e.g., a interconnection contact in a semiconductor device has been developed. In a lithography step in manufacture of a semiconductor device, it is known that a linear opening pattern rather than a hole pattern enables forming an elaborate finer pattern because of lithography characteristics. Therefore, by utilizing such characteristics, when forming a fine contact hole a so-called double transfer exposure technology or cross-point exposure technology is used (see, e.g., Jpn. Pat. Appln. KOKAI Publication No. 2000-357736 (FIG. 3)). According to this technology, mask layers having linear opening patterns formed therein are superimposed on, e.g., an interlayer insulating layer in such a manner that the linear opening patterns become perpendicular to each other, and an interlayer insulating layer or the like below opening crossing parts of the patterns perpendicular to each other is etched to form each contact hole.
However, in case of exploiting this technology to form each fine contact hole in a semiconductor device, a problem that a fine contact hole is distorted occurs when a resist of, e.g., an organic film is used as a mask to perform etching.

Manufacturing method of semiconductor device and semiconductor storage device including fine contact holes