An apparatus usable with a flash memory as storage and a method of operating the same are provided, which can provide an optimized architecture to a flash memory through combination of a flash transition layer (FTL) with a database. The apparatus includes a flash memory, a device driver to manage a mapping table between logical addresses and physical addresses in accordance with a data operation in the flash memory, and a control unit to perform data recovery of the flash memory by requesting the mapping table through an interface provided by the device driver.

1. Field of the Invention
The present general inventive concept relates to an apparatus using a flash memory as storage and a method of operating the same, and more particularly, to an apparatus using a flash memory as storage and a method of operating the same, which can provide an optimized architecture to a flash memory through combination of an FTL (Flash Translation Layer) with a database.
2. Description of the Related Art
Generally, in an embedded system, such as a home appliance, a communication appliance, a set top box, and the like, a nonvolatile memory has been widely used as a storage medium for storing and processing data.
A flash memory, which is a type of nonvolatile memory, is a nonvolatile storage device that can electrically delete or rewrite data. Since the flash memory has a low power consumption in comparison to a storage medium based on a magnetic disk memory, a rapid access time in comparison to a hard disk, and a small size, the flash memory is suitable to be used in a portable device.
Such a flash memory has a different characteristic from a magnetic storage medium, such as a hard disk. Specifically, in the flash memory, data read/write operation can be performed in a unit of a page, but data update work cannot be performed in the unit of the page. In order to perform the data update work in the flash memory, a delete operation in the unit of a block that is composed of a plurality of pages is required, and generally, the delete unit is larger than the write unit. This feature of the flash memory is difficult using a file system designed based on a hard disk.
Accordingly, in order to complement the characteristic that the delete unit is larger than the write unit in the flash memory and the characteristic that the number of deletions is limited in the flash memory, and to use a file system designed based on a hard disk, a flash translation layer (FTL) has been developed. The FTL is a type of software layer allowing flash memory to be used in the same manner as a hard disk.
Recently, with an increase of the capacity of a flash memory, a large amount of data can be stored in flash memory. Accordingly, the use of a database is essential in an apparatus using the flash memory as storage. For example, in an apparatus using the flash memory as storage, log-based recovery and shadow paging techniques have been used as mechanisms for data recovery.
The log-based recovery technique generates log records for changes in the database, stores the log records in the disk, and uses the log records for the database recovery. The log records for the changes include previous data and new data for the changed data, and are written in the disk via log buffers as needed. According to this log-based recovery technique, the log records, which usually are very small, are frequently written in the disk whenever the changes are generated. Accordingly, pages are frequently used due to the frequent writing of the log records, and thus a deletion operation, which is relatively slow in comparison to the read/write operation, is frequently performed in order to withdraw the pages that have become ineffective.
If a specified page is updated, the shadow paging technique updates data of the corresponding page by making a copy of the page in another page, without using the log records. If a transaction is terminated, the technique reflects the transaction in a new disk, while if the transaction is aborted, the technique discards the copy. According to the shadow paging technique, the frequent writing of the log records as in the log-based recovery technique is not performed, but is required to separately manage a page table for managing pages in which copies of the updated pages are written. That is, the database manages the mapping operation between logical addresses and physical addresses. However, since the physical addresses managed in the database are once again translated into physical addresses through the mapping table managed by the FTL and the mapping information is managed by the database and the FTL, unnecessary duplication work is performed.
Accordingly, there is a need for a database architecture that considers the characteristic of a flash memory in an apparatus using the flash memory as storage.
Korean Patent Unexamined Publication No. 2004-0082921 relates to a flash file system which has an FTL (Flash Translation Layer) and performs mapping of logical addresses received from a host system on physical addresses of a flash memory. This flash file system, however, still fails to propose a database architecture that considers the characteristic of a flash memory in an apparatus using the flash memory as storage.

Apparatus using flash memory as storage and method of operating the same


For improved offset compensation, a Hall sensor is provided with a device for orthogonally switching the Hall detector supply current and the Hall-voltage taps. A summing device determines an offset-compensated Hall-voltage value from first and second predetermined Hall-voltage values. The Hall-voltage values are formed by means of a Hall detector containing at least first and second Hall cells for offset-voltage precompensation. The first and second Hall cells are identical and are orthogonally switchable. The geometrical orientation of the first and second Hall cells includes an angle other than 0.degree. and 180.degree..

1. Field of the Invention
The present invention relates to a Hall sensor for measuring magnetic fields, particularly to a Hall sensor in the form of a monolithic integrated component containing a Hall detector, a power supply, and electronic circuits for evaluating the Hall voltage.
2. Description of the Related Art
To fabricate a Hall sensor comprising a combined detector, power supply and electronics circuit, use is commonly made of one of the conventional silicon semiconductor technologies which correspond to the conventional bipolar or MOS fabrication processes. Known disadvantages of silicon as the Hall detector material are its low Hall sensitivity and the great influence of the piezoelectric effect, which leads to offset-voltage errors caused by stresses in the crystal structure and caused by direction-dependent Hall sensitivity.
The sensitivity of Hall detectors is essentially a function of the carrier mobility and the current flow through the Hall plate. The resolution limit and the spread of measured values are dependent mainly on the variation of the different offset voltages, which depend on the Hall detector itself and the subsequent electronics.
A Hall plate can, to a first approximation, be thought of as a resistance bridge which is adjusted for zero output, i.e., balanced, if no magnetic field is present. Methods for fabricating Hall sensors in which the desired accuracy can only be achieved by a selection from the wide fabrication spectrum are quite unsatisfactory, of course. Therefore, tolerances are kept to a minimum during fabrication by compensation methods. The most widely used method is the compensation of the Hall plate offset voltage by parallel connection of a second Hall plate rotated by 90.degree. which is as equivalent to the first Hall plate as possible. This makes it possible to compensate, to a first approximation, for the imbalance of the resistance bridge due to the piezoelectric effect. Nevertheless, process tolerances or high stress gradients in the crystal prevent a higher precision of the magnetic-field measurement.
A method of compensating the offset voltages is described in "Proceedings of Eurosensors IV", 1991, Vol. 2, pages 747 to 751, which relates to a meeting held in Karlsruhe October 1-3, 1990. The method described therein uses a circular Hall plate with 16 contacts uniformly distributed around the periphery, which are switched circularly by means of electronic switches. The 16 associated Hall voltages are integrated causing the offset error to be reduced to values less than 50 microvolts. In the pertinent description it is stated that it is possible to completely eliminate geometrical errors of the Hall plate by orthogonal switching, but not to eliminate offset errors due to the above-described piezoelectric effects.
Since offset errors in silicon are frequently considerably greater--for instance, up to a factor of 1000--than the Hall voltage to be determined, there is also a specific error of the evaluating circuit.
Assuming an ideal equivalent bridge circuit, during orthogonal switching, the offset error occurs with different signs. If the two orthogonal Hall voltages were summed, the offset error would thus have to be fully compensated. This would apply only if strict proportionality, linearity, equal gain and sensitivity can be assumed for the amplified and processed Hall voltages. The linearity and sensitivity requirements are generally insufficient.

Offset-compensated hall sensor having plural hall detectors having different geometrical orientations and having switchable directions


A kiln system for drying green lumber to a predetermined moisture content according to the present invention includes a kiln chamber for enclosing a charge of lumber consisting of a number of laterally spaced rectangular solid stacks of lumber, a fan above the lumber for circulating air through the kiln chamber and through the lumber and a first elongate center bridging panel above the stacks of lumber and overlying each vertically extending air space defined between adjacent, laterally spaced stacks of lumber. The elongate center bridging panel includes a center portion having opposed side edges which extends laterally substantially across the air space. The center bridging panel also includes first and second side portions hingedly connected to the opposed edges of the center portion. The center bridging panel substantially prevents circulating air from rising above the stacks of lumber in the vertically extending air space. Accordingly, the circulating air is forced to flow through each successive stack of lumber to more evenly and efficiently dry the lumber.

Lumber which has recently been cut and machined contains a relatively large percentage of water and is referred to as green lumber. Prior to being used in construction or other applications which demand good grades of lumber, the green lumber must be dried to remove a relatively large percentage of water from the lumber. Acceptable water content will vary with the application as well as the type of wood, however, in many circumstances, a moisture content of 19% or less is an acceptable water content.
Although lumber may be air dried, kiln drying accelerates and provides increased control over the drying process. In kiln drying, charges of lumber are placed in a kiln chamber. A typical kiln chamber is a generally rectangular building which can be sealed to control the introduction and exhaust of air. Further, such kiln chambers typically have reversible fans for circulating the air through the chamber.
The charge of lumber placed in the kiln generally consists of a number of rectangular solid stacks of lumber. Each stack of lumber, in turn, typically consists of a number of vertically stacked, horizontal rows of lumber that form a rectangular solid. The horizontal rows are spaced apart for air to pass between the rows using wooden boards referred to as "stickers" that have a relatively small lateral cross-sectional area in relation to the lateral cross-sectional area of the lumber forming the charge. The stickers are generally spaced apart between each horizontal row to allow air to flow between the rows.
Typically, the stacks of lumber are placed on separate wheeled, flat bed cars which are mounted for movement on railroad-type tracks. Kilns may have any desired number of tracks. Multi-track kilns may therefore accept several stacks of lumber during each drying cycle.
In operation, a charge of green lumber is initially placed in a kiln chamber. After sealing the kiln chamber, the air within the kiln is heated to facilitate drying. The air may be heated in a number of ways such as by heat transfer from pipes extending through the kiln chamber in which steam flows. Alternatively, heated air may be introduced such as from a furnace. Kilns which utilize the introduction of heated air are typically referred to as direct fired kilns.
Fans generally positioned in upper portions of the kiln and above the stacked lumber circulate the heated air through the kiln chamber, including the stacks of lumber. Because the stickers provide spacing between the horizontal rows of lumber, the heated air passes between the rows of lumber and is in direct contact with both the upper and lower surfaces of the individual pieces of lumber. The fans continually recirculate the air through the kiln and the lumber to further dry the lumber. Periodically, a portion of the circulating air is exhausted from the kiln and additional air is introduced into the kiln. The additional air is typically heated in the kiln chamber, such as by heat transfer from the steam pipes. This periodic exhaust and replacement process allows circulating air which has absorbed a large amount of moisture from the green lumber to be removed, while drier air is introduced to accelerate the lumber's drying.
Within such kilns, the circulating air flows in a generally circular pattern. More particularly, fans above the stacks of lumber direct air laterally over the top of the lumber in a first direction. When the air contacts a first sidewall of the kiln chamber, the bulk of the air is forced downward by the fans and the ceiling of the kiln chamber. The circulating air subsequently flows through the spaces between the horizontal rows of lumber established by the stickers in a second, lateral direction opposite the first lateral direction. Upon contact with a second sidewall of the kiln chamber, the air rises and is recirculated by the fans through the lumber. Periodically, the fans are reversed such that the air flows in the opposite direction to provide generally consistent drying of the lumber.
In standard multi-track kilns, adjacent stacks of lumber typically define a narrow, vertically extending air space between the stacks. The circulating heated air will rise in this air space between adjacent first and second stacks of lumber. Depending upon the width of the air space, the air's circulation speed, and the distance between the circulating air and the top of the stacks when the air enters the air space from the first stack of lumber, the air may rise above the stacks of lumber. Consequently, such air would be recirculated without ever passing through the second stack of lumber.
As a result, the second stack of lumber would not be dried as thoroughly as the first stack of lumber. This uneven drying of the stacks of lumber may result in the production of inferior grades of lumber, including lumber with increased warping and cracking. If the drying is continued until the second stack of lumber is sufficiently dry in an attempt to avoid the production of inferior grades of lumber, the time and expense required to dry the lumber will significantly increase and the first stack of lumber may actually be dried too much. Further, as the same amount of air does not circulate through each stack of lumber, the consistency and predictability with which the lumber may be dried, i.e., the determination of appropriate drying times for which the lumber must remain in the kiln to ensure adequate moisture removal, is hindered.

Center bridging panel for drying green lumber in a kiln chamber


A full color digital scanning system includes a lamp carriage having a light source and a mirror. A mirror carriage is also included with a rotatable corner mirror assembly. The rotatable corner mirror assembly has a first color corner mirror subassembly, a second color corner mirror subassembly, and a third color corner mirror subassembly. The scanning system positions a first color corner mirror on a mirror carriage to provide a 180.degree. cornering function and scans the image to produce image data representing a first color component. The scanning system then positions a second color corner mirror on the mirror carriage to provide a 180.degree. cornering function and scans the image to produce image data representing a second color component. The scanning system further positions a third color corner mirror on the mirror carriage to provide a 180.degree. cornering function and scans the image to produce image data representing a third color component.

Conventionally, low volume and mid-volume copiers and image input terminals utilize moving scanning carriages to scan an image. These moving scanning carriages usually include an illumination device like a fluorescent lamp. These scanning carriages are moved across an image by a cable system during the scanning process. Such a prior art scanning carriage system is illustrated in FIG. 1. This scanning system is commonly called a half rate/full rate scanning system.
In FIG. 1, a motor 1 in conjunction with a belt 3 is used to drive a capstan 5. Capstan 5 has a plurality of cable windings around it such that when the capstan 5 is rotated, certain cable strands are pulled onto the capstan and other cable strands are released from the capstan. As illustrated in FIG. 1, two sets of cables 11 and 13 are used to move a lamp carriage 17 and a mirror carriage 19 having corner mirrors 21 positioned thereon.
Cable 11 is connected to the frame 9 by anchor 10. The cable 11 is then wrapped around pulley (roller) 57 and connected to the lamp carriage 17 through clamp 28. From clamp 28, cable 11 is wrapped around pulleys (rollers) 51 and 50 before being wrapped around, capstan 5. The remaining portion of cable 11 wraps around pulleys (rollers) 55, 60, 58, and 59 before being connected to spring 8. Spring 8 is connected to the frame 9 by anchor 6. Cable 11 is connected to the mirror carriage 19 at pulleys (rollers) 57 and 58.
Cable 13 is connected to the frame 9 by anchor 2. The cable 13 is then wrapped around pulley (roller) 52 and connected to the lamp carriage 17 through clamp 27. From clamp 27, cable 13 is wrapped around pulley (roller) 50 before being wrapped around capstan 5. The remaining portion of cable 13 wraps around pulleys (rollers) 54, 53, and 56 before being connected to spring 4. Spring 4 is connected to the frame 9 by anchor 6. Cable 13 is connected to the mirror carriage 19 at pulleys (rollers) 52 and 53.
The cables 11 and 13 are wrapped around the pulleys (rollers) in such a configuration that when the cables 11 and 13 are released or pulled onto the capstan 5, the carriages 17 and 19 are properly moved to scan the image. More specifically, a lamp 15 which is located on the lamp carriage 17 provides a light source to scan the image wherein the light reflected from the image is incident upon mirrors located on the lamp carriage 19 and thus are directed toward corner mirrors 21 located on the mirror carriage 19. The corner mirrors 21 direct the reflected light from the mirror on the lamp carriage 19 to a lens. The lens focuses the scanned image onto a CCD or full width array sensor. The sensor converts the reflected light into electrical signals representing the scanned image.
This scanning operation can be more clearly seen in FIG. 2 of the present application. FIG. 2 illustrates the path of light as it is reflected from the image 101. The reflected light, as noted above, is incident upon a mirror 117 which is located on the lamp carriage 17. This mirror 117 then directs the light towards the corner mirrors 21 on the mirror carriage which causes the light to make a 180.degree. turn. The light leaving the corner mirrors 21 is directed to an optical lens assembly 107 which focuses the reflected light upon a CCD or full width sensor array 109.
The utilization of pulleys on the mirror carriage 19 allows the mirror carriage to move into proper proportion to the movement of the lamp carriage 17. In other words, a focused image is maintained by maintaining a certain fixed optical distance between the image 101 and the lens 107 while the lamp carriage 17 is moving. The fixed optical length is ensured by the mirror carriage 19 moving at exactly one half the speed of the lamp carriage 17 and in the same direction as the lamp carriage 17.
It is desirable to produce full color images with digital scanners. To produce a full color image, the light reflected from the image must be filtered by at least three color filters so as to produce three sets of color image data. Although digital scanners have been able to achieve this result, the result has only been achieved by redesigning the entire scanning system which increases the cost of producing a color scanner. The mirror system described above does not aid in the color separation process. Thus, it is desirable to provide a retrofit to a monochrome digital scanner's scanning system which easily converts the monochrome scanner to a full color digital scanner.

Method and system for converting a half rate/full rate monochrome scanner to a half rate/full rate color scanner


A security device for preventing unauthorized separation of a door from a cooperating buck assembly, in which first and second plate members are respectively carried by the door and the buck assembly and cooperate with each other to prevent movement of the door in a lateral direction when the door is closed. The first plate member is of unique configuration and is arranged to interlock with adjoining structure on the second plate member to keep the door from moving in its plane. In certain embodiments a Z-shaped support element separate from the plate members is mounted on the buck assembly in juxtaposition with the second plate member, and in some cases either the first plate member or the second plate member includes a pivotally supported cam element which moves into cooperating relationship with the other member as the door reaches its fully closed position.

This invention relates to security apparatus and more particularly to apparatus for preventing unauthorized separation of a door from a cooperating buck assembly.
As is well known, many types of access doors in present usage are hinged or pivoted along one vertical edge to a cooperating rectangular frame commonly referred to as a door buck. The opposite vertical edge carries a spring biased latch within the door which protrudes into a mating opening in a strike plate on the buck assembly when the door is closed. The latch may be locked to secure the door in its closed position.
One of the ways of gaining unauthorized entry through a door which has been locked in this manner is to wedge a crowbar or similar burglar's tool between the door and the buck assembly and then pry the two apart. The door moves in its plane and becomes bowed sufficiently to carry the latch away from the strike plate by a distance equal to the latch's penetration in the strike plate opening. The door may then be readily moved to its open position.
Although attempts have been made heretofore to prevent such authorized entry through the use of interlocking plates and similar devices, these attempts have proved deficient in many respects. As an illustration, and this was of special moment in the mounting of the plates on a pre-existing door and buck installation, difficulties were encountered in positioning the plates in their proper locations. In addition, in several previous arrangements of this type the apparatus was deficient in providing the desired locking action with the necessary structural rigidity to do a really effective job. Further difficulties were encountered in arranging the interlocking plates such that they remained in position even after successive attempts to force the door.


The present invention is directed to a method of desulfurization of a sulfur laden hydrocarbon liquids that comprises contacting the liquid with a sponge nickel metal alloy, removing the sulfur free liquid, regeneration of the alloy by contact with an aqueous solution of an oxidant and reusing the alloy for further desulfurization of additional sulfur laden liquid.

The present invention is directed to an improved process capable of providing product streams of light and heavy gasoline fractions, which are substantially free of sulfur containing compounds.
Catalytic cracking is a petroleum refining process, which is applied commercially on a very large scale. A majority of the refinery gasoline blending pool in the United States is produced using a fluidized catalytic cracking (FCC) process. In the process, heavy hydrocarbon feedstocks are converted into lighter products by reactions taking place at elevated temperatures in the presence of a catalyst, with the majority taking place in the vapor phase. The feedstock is thereby converted into gasoline, distillates and other liquid fraction product streams as well as lighter gaseous cracking products having four or less carbon atoms per molecule. The three characteristic steps of a catalytic cracking process comprises: a cracking step in which the heavy hydrocarbon feed stream is converted into lighter products, a stripping step to remove adsorbed hydrocarbons from the catalyst material, and a regeneration step to burn off coke formations from the catalyst material which is then recirculated and reused in the cracking step.
Petroleum feedstocks normally contain organic sulfur compounds, such as mercaptans, sulfides and thiophenes. The products of the cracking process correspondingly tend to contain sulfur impurities even though about half of the sulfur compounds are converted to hydrogen sulfide during the cracking process, mainly by catalytic decomposition of non-thiophenic sulfur compounds. The thiophenic and other organic sulfur containing compounds have been found most difficult to remove. The specific distribution of sulfur in the cracking products is dependent on a number of factors including feed, catalyst type, additives present, conversion and other operating conditions, but, in any event in a certain proportion of the sulfur tends to enter the light or heavy gasoline fractions and passes over into the product pool. Although petroleum feedstock normally contains a variety of sulfur born contaminants, one of the chief concerns is the presence of unsubstituted and hydrocarbyl substituted thiophenes and its derivatives, such as thiophene, methylthiophene, ethylthiophene, propylthiophene, benzothiophene, and tetrahydrothiophene, as well as thiophenols, in the heavy and light gasoline fraction product streams of the refining process (e.g. fluid cracking catalyst process). These compounds generally have boiling points within the range of the light and heavy gasoline fractions and, thus, become concentrated in these product streams.
In response to concerns about emission of sulfur oxides and other sulfur compounds into the atmosphere following combustion, various governmental agencies have promulgated regulations on the amount of sulfur contained in these petroleum-refining products. For example, the U.S. Government has issued Reformulated Gasoline (RFG) regulations, as well as Amendments to the Clean Air Act. In addition, the California Air Resources Board has set a limit on the concentration of sulfur in gasoline to about 40 parts per million (ppm). Since the current sulfur levels in gasoline are about 385 ppm, these new lower goals require significant resources by most petroleum refiners to meet the new level.
Several approaches have been developed to remove sulfur from gasoline. One approach has been the removal of sulfur containing compounds from feedstock by hydrotreating the stock prior to cracking. While highly effective, this approach tends to be expensive in terms of capital costs of the equipment required as well as operationally, since large amounts of hydrogen are consumed.
From the economic point of view, it would be desirable to achieve thiophenic sulfur removal in the cracking process itself since this would effectively desulfurize the major components of the gasoline blending pool without additional treatment. Various catalytic materials have been developed for the removal of sulfur during the FCC process cycle. For example, a FCC catalyst impregnated with vanadium and nickel metal has been shown to reduce the level of product sulfur. See Myrstad et al., Effect of Nickel and Vanadium on Sulfur Reduction of FCC Naptha, Applied Catalyst A: General 192 (2000) pages 299-305. This reference also showed that a sulfur reduction additive based on a zinc-impregnated alumina is effective to reduce product sulfur in FCC products. However, when these materials are mixed with metal impregnated FCC catalyst, the effect of sulfur reduction was lessened and became economically inefficient.
Other developments for reducing product sulfur have centered on the removal of sulfur from the regenerator stack gases. An early approach developed by Chevron used alumina compounds as additives to the inventory of cracking catalyst to adsorb sulfur oxides in the FCC regenerator; the adsorbed sulfur compounds which entered the process in the feed were released as hydrogen sulfide during the cracking portion of the cycle and passed to the product recovery section of the unit where they were removed. See Krishna et al., Additives Improved FCC Process, Hydrocarbon Processing, November 1991, pages 59-66. Although sulfur is removed from the stack gases of the regenerator, product sulfur levels are not greatly effected, if at all.
An alternative technology for the removal of sulfur oxides from regenerator stack gases is based on the use of magnesium-aluminum spinels as additives to the circulating catalyst inventory in the FCC unit. Exemplary patents disclosing this type of sulfur removal additives include U.S. Pat. Nos. 4,963,520; 4,957,892; 4,957,718; 4,790,982 and others. Again, however, product sulfur levels are not greatly reduced.
A catalyst composition to reduce sulfur levels in liquid cracking products has been described in Wormsbecher and Kim in U.S. Pat. Nos. 5,376,608 and 5,525,210. The composition proposes the addition of a cracking catalyst additive, composed of an alumina-supported Lewis acid, with conventional zeolite molecular sieves. Although this system has the advantages of causing sulfur reduction in the cracking process, the composition has not achieved significant commercial success. It has been found that the compositions proposed by Wormsbecher et al. do not provide significant reduction of the levels of thiophenes and its derivatives, even when high levels of the alumina-supported Lewis acid additives are included in the composition. The use of greater than about 10 weight percent of additives in their composition does not provide a benefit equal to the cost of the additive.
The possibility of adsorbing thiophenes directly from gasoline has been explored briefly in the scientific literature. A. B. Salem in Ind. Eng. Chem. Res., 33, page 336 (1964) and Garcia et al. in J. Phys. Chem. 96 page 2669 (1991) have shown that certain zeolite materials can be used to adsorb thiophenes from olefin-free gasoline. Exchanged zeolites, such as Ag-exchanged Zeolite Y and Cu-exchanged Zeolite Y have been shown to adsorb sulfur from standard gasoline (See U.S. Pat. No. 4,188,285 and EP 0,275,855). However, in each case, the absorption capacity of the adsorbent material is insufficient for commercial application.
It is also recognized that raw fuels, such as gasoline, diesel fuels and the like may not be useful as a fuel source for a fuel cell power plant due to the presents of organo-sulfur compounds in the fuel source. Hydrogen generation in the presence of sulfur and sulfur compounds results in a poisoning effect on all of the catalysts used in a hydrogenation generating system, including fuel cell anode catalysts. Conventional fuel processing systems used with fuel cell power plants include a thermal steam reformer, such as that described in U.S. Pat. No. 5,5 16,334. In such a system, the sulfur is removed from the fuel by conventional hydrodesulfurization techniques. The resultant hydrogen sulfide is then removed using a zinc oxide bed. While this system is satisfactory when used in combination with large stationary applications, it does not lend itself to mobile transportation applications because of the systems size cost and complexity. It would be highly desired to have a cost-effective means of removing sulfur from hydrocarbon fuels so that they can be used in fuel cell applications.
It would be desirable to have an economical and effective process, which is capable of removing sulfur-containing materials, such as thiophenes, directly from gasoline product streams obtained from cracking processes.
It would also be desirable to have an economical and effective process which selectively adsorbs sulfur containing materials contained in a gasoline product stream and in which the absorbent can be readily desorbed of the sulfur material and recycled to further remove sulfur material from additional gasoline product.
The present invention is directed to the desulfurization of hydrocarbon compositions by contacting sulfur laden hydrocarbon liquid such as product stream liquid of petroleum refining processes with Raney(copyright) nickel catalyst compositions useful in packed bed reactors, and separating the desulfurized hydrocarbon liquid from the Raney nickel material. The process further provides for removal of the sulfur species from the Raney nickel and reusing the regenerated catalyst to treat additional sulfur-laden hydrocarbon liquid.
The present process provides an effective and economic method of removing sulfur species from hydrocarbon liquids, especially light and heavy gasoline fractions obtained from cracking of petroleum heavy hydrocarbon feed. The present process comprises contacting sulfur-ladened hydrocarbon liquid product with porous nickel-alumina or nickel-aluminum fixed bed catalyst material that is contained in a fixed bed reactor and recovering the resultant desulfurized hydrocarbon liquid. The sulfur species of sulfur-laden fixed bed catalyst can be readily removed by the present invention to provide a regenerated porous catalyst. This catalyst can again be utilized for removal of sulfur species from additional hydrocarbon liquid. Thus, the present invention provides a process that can effectively and economically produce a sulfur free hydrocarbon product.
The terms xe2x80x9cfixed bed reactorxe2x80x9d or xe2x80x9cpacked bed reactorxe2x80x9d as used herein and in the claims appended hereto interchangeably refer to any reactor in which the catalyst is in a densely loaded or substantially stationary form. For example, the reactor may have a packed column or an ebullating bed form. The terms xe2x80x9cfixed bed catalystxe2x80x9d or xe2x80x9cpacked bed catalystxe2x80x9d interchangeably refer to catalyst compositions useful in these reactors.
The process and system of the present invention is particularly adapted for the treatment of hydrocarbon product streams from catalytic cracking processes. It should be understood, however, that the scope of the present invention is not limited to hydrocarbon liquids obtained from such processes.
The process and system of the present invention is also useful in the treatment of hydrocarbon product streams contemplated for use in fuel cell applications.
Catalytic cracking is a petroleum refining process whereby heavy hydrocarbon feed is converted into lighter products by reactions, which take place at elevated temperatures in the presence of a catalyst. The majority of the conversions occur in the vapor phase. The feedstock is converted into gasoline, distillate and other liquid products as well as lighter gaseous products having one to four carbon atoms per molecule. This petroleum refining process is normally perceived as being composed of three steps comprising the cracking step in which the petroleum hydrocarbons are converted into lighter, commercially desirable distillate products, a stripping step to remove hydrocarbon adsorbed on the catalyst and a regeneration step to burn off coke which has accumulated on the catalyst during cracking.
Distillate products suitable for processing according to the present invention are typically are light products composed of hydrocarbon components in which about 10 percent by volume having boiling points in the range of from about 80xc2x0 to 180xc2x0 F. (27xc2x0-83xc2x0 C.) and the remaining having boiling points within the range of from about 180xc2x0 to 500xc2x0 F. (83xc2x0 to 260xc2x0 C. Suitable distillate products may also be light cycle oil and/or gasoline products having about 10 percent by volume having boiling points of from about 300xc2x0 F. (149xc2x0 C.) to 500xc2x0 F. (260xc2x0 C.) with the remaining 90 percent by volume having boiling points in the range of from about 500xc2x0 F. (260xc2x0 C.) to not more than about 750xc2x0 F. (399xc2x0 C.).
Typical distillates, which can be subjected to the desulfurization process of the present invention described below, may have the following characteristics:
The distillate hydrocarbon mixture normally contains sulfur species that need to be removed to provide a resultant product having a reduced sulfur content which causes the product to be environmentally acceptable. The product stream may be a product of a hydrotreating processes (hydrogenalysis and treated product) or from absorption processes (treating).
The terms xe2x80x9csulfurxe2x80x9d and xe2x80x9csulfur speciesxe2x80x9d as used herein and in the appended claims refer to elemental sulfur and to organic sulfur compounds including sulfides, such as a di C3-C6 sulfide, as for example propyl sulfide, butyl sulfide pentyl sulfide, hexyl sulfide and the like; disulfides, such as di C2-C4 disulfides, as for example ethyl disulfide, propyl disulficle, butyl disulfide and the like; mercaptans, such as C1-C4 alkanethiols as, for example, mathanethiol, ethanethiol, propanethiol and the like; thiophenes, such as methylthiophene, ethylthiophene, propylthiophene, dihydrothiophene and the like; benzothiophenes, such as a C1-C4 alkyl benzothiophene as, for example, methyl benzothiophene, dimethylbenzothiophene and the like; dibenzothiophenes; mixtures of said organic sulfur compounds, and the like which are contained in a liquid hydrocarbon.
The present invention is directed to contacting sulfur laden hydrocarbon distillate with a sponge nickel metal alloy catalyst (also referred to herein as a xe2x80x9cRaney nickel catalystxe2x80x9d). The distillate and Raney nickel may be contacted by passing the distillate through a packed bed (e.g. fixed bed or ebullated bed) of the present catalyst. The materials are contacted under ambient pressure, which normally is from atmospheric pressure to a slightly elevated pressure (e.g., up to about 5 atmospheres). The materials are contacted at temperatures ranging from 15 to 150xc2x0 C., such as 15xc2x0 C. to 70xc2x0 C.,
xe2x80x9cRaney Nixe2x80x9d, as used herein and in the appended claims, refers to a porous catalytic alloy based material of nickel and aluminum that may further contain small amounts of other metals. The porous catalyst is formed by first forming a precursor alloy of nickel and aluminum (optionally having small amounts of up to about 10 weight percent of other metals, such as Cr, Mo, Fe, Cu, Co, Zn and the like therein) in which the nickel is present in from about 35 to 60 weight percent, with the remainder being primarily aluminum; subjecting the formed alloy to an aqueous alkali (e.g., sodium hydroxide) solution to extract the aluminum metal from the alloy. When the resultant porous material is of the coarse granular, fixed bed type (cross sectional diameter of about 2 to 6 mm), the aluminum is only partially extracted to retain about 60 to 40, preferably 55 to 45 weight percent Ni and from about 40 to 60 weight percent Al. The fine granular fixed bed type (cross sectional diameter of about 0.1 to 2 mm) normally has about 60 to 95 weight percent Ni and from about 5 to 40 weight percent Al. As stated above, small amounts of the resultant porous catalyst may be composed of copper, iron, cobalt, zinc, chromium, molybdenum and the like or mixtures thereof, as well as chemically-bound oxygen in the resultant species.
The Raney Ni material can be formed according to the process described in U.S. Pat. Nos. 1,628,190; 1,915,473; 2,139,602; 2,461,396; and 2,977,327. The teachings of these patents are incorporated herein in their entirety by reference. Commercial products of this material are sold by W. R. Grace and Co. under the trademark RANEY(copyright).
The catalyst material may be (a) granular; (b) a polymer bonded material that is not subjected to calcining; or (c) a calcined product. In cases where the catalyst is a formed material (b) or (c), the catalyst is formed from Raney Ni particles having a particle size in the range of minus 50 mesh (U.S. Standard screens) or less, such as minus 100 mesh or more preferably minus 200 mesh. The term xe2x80x9cminusxe2x80x9d, when used in conjunction with mesh size, refers to material which passes through the designated mesh screen (U.S. Standard screens). The catalysts of Raney Ni may be formed by conventional methods, such as those described in U.S. Pat. Nos. 4,826,799 and 4,895,994, the teachings of which are incorporated herein in their entirety by reference. For example, the catalyst involved in contacting a fixed bed or moving bed of the packed bed catalyst with the sulfur-laden hydrocarbon liquid may be formed by:
First, mixing particles of minus 50 mesh or less of an alloy of nickel and aluminum with a high molecular weight polymer alone or further with a plasticizer for the polymer, such as mineral oil. In addition, small amounts (up to about 10 weight %) of other ingredients such as inert fillers, stabilizer, etc. can be added to the mix.
The mixture is formed into shaped material, typically by extrusion and cutting or by pellet molding.
The shaped material is then subjected to an extraction or other process step to remove all or at least a majority of the plasticizer from the shaped material.
The shaped material may be then treated in ways to form the active fixed bed catalyst. For example, the shaped material may be treated with alkali (e.g., sodium hydroxide) to remove aluminum metal by conventional Raney technique. Thus, the resultant material is a Raney Ni having a shape bound by a polymer.
Alternately, the shaped fixed bed catalyst material can be calcined and then subjected to alkali solution to remove a majority of the aluminum from the initial alloy. The resultant porous shaped Raney Ni will be substantially free of polymer and plasticizer.
The above fixed bed catalyst can, as stated above, be formed with the use of a polymer alone or additionally with a plasticizer for the polymer.
In the case where the material is subjected to calcining, the alkali leaching of aluminum from the calcined fixed bed catalyst precursor may provide a Raney Ni fixed bed catalyst, such as that illustrated by the table herein below. Oxygen may be present as bound to aluminum (as alumina) and, in addition, small amounts of oxygen may be chemically bound to certain other metals that are present. This explains the differences of the content of the compositions when done on a metal only basis versus that done on a total composition basis. The retention of high aluminum content as metal or alumina provides a fixed bed catalyst of high strength suitable for the cyclic processing as required by the present invention and described herein below.
Generalized compositions formed by various extrusion or pelleting processes are shown in Table below:
Polymers suitable for forming fixed bed catalyst used in the present invention include materials which are fluid at some stage in their processing. Suitable thermoplastics for carrying out this invention include: unplasticized polyvinyl chloride, polyvinyl chloride-propylene copolymer, polyvinyl chloride-ethylene copolymers, polyvinylidene chloride copolymers, polystyrene, impact styrene, ABS resin, styrene butadiene block copolymers, polyethylene of low (0.91 sp. gr.) to high density (0.97 sp. gr.), polyethylene copolymers with propylene, butene, 1-pentane, 1-octane, hexene, styrene, etc., polyethylene copolymers with vinyl acetate, alkyl, acrylate, sodium acrylate, acrylic acid, etc., chlorinated polyethylene, chlorosulfonated polyethylene, polypropylene and propylene-olefin copolymers, polybutene and butylene-olefin copolymers, poly-4-methyl-1-pentene, thermoplastic polyurethane, polyamides, e.g., Nylon-5, Nylon-12, Nylon-6/6, Nylon-6/10, Nylon-11, fluorocarbon resins such as FEP, polyvinylidene fluoride, polychlorotrifluoroethylene; acrylonitrile-methyl acrylate copolymers, acrylonitrile-vinyl chloride copolymers, methacrylonitrile-styrene copolymers, polymethyl inethacrylate, cellulose acetate, cellulose acetate butyrate, acetal, polycarbonate, polysulfone, polyethylene oxide, polypropylene oxide, polyphenylene oxide, polyethylene and butylene terephthalates.
Many thermosetting resins and crosslinkable resins are also suitable for purposes of this invention and include the following: radiation cured polyethylene, peroxide-cured polyethylene, diazo crosslinked polypropylene, epoxy resins; hydrocarbon, chloroprene, and nitrile rubbers, furane, melamine-formaldehyde, urea-formaldehyde, phenol-formaldehye, diallyl phthalate, polyesters and silicones.
From economic considerations, one wishes to use relatively inexpensive binder polymer since in one of the processes of forming the fixed bed catalyst, it will be burned away in the final product. A preferred group of polymers are polyolefins, polyvinyl chlorides, polyvinyl acetates, polystyrenes and mixture of these polymers. The polyolefins are most preferred, and these are discussed separately below.
The preferred polyolefin component is the same as those used in mixes of the prior art, e.g., as described in U.S. Pat. Nos. 3,351,495 and 3,904,551. Thus, the polyolefin (which may be a mixture) has a high molecular weight (at least 100,000). Suitably it is a linear polyethylene of at least 0.93 to 0.97 g/cm3 density, high molecular weight polypropylene, or high molecular weight particle form ethylene-butylene copolymer. Others are polybutene, ethylene-propylene copolymers, ethylene-butene copolymers, propylene-butene copolymers, and ethylene-propylene-butene copolymers. A useful polyolefin is a commercial particle form high molecular weight polyethylene having a standard load (2,160 g) melt index of 0.0; a high load (21,600 g) melt index of 1.8, a density of 9.96, and a solution viscosity of 4.0 measured as 0.02 g of polymer in 100 g decalin at 130xc2x0 C.
Blends of high and low molecular weight polyolefins can be used, bearing in mind that as the average molecular weight is reduced, the possibility of slumping is increased during the bake-out and early part of the firing process.
The plasticizer component, when used, can be that used in prior art mixes, e.g., as described in U.S. Pat. Nos. 3,904,551 and 3,351,495, bearing in mind that some plasticizers will react violently with finely divided Al, e.g., the lower alcohols, and that these should, of course be avoided. A particularly useful plasticizer is mineral oil. Hydrocarbons, (e.g., paraffin oil and low molecular weight polymers such as polyisobutylene and polybutadiene) are suitable. The more volatile types of mineral oil are preferred if removal is to be done by baking.
The plasticizer enhances processing of the composition, i.e., it lowers the melt viscosity and reduces the amount of power input, which is required to compound and fabricate the composition. Very importantly, the plasticizer, by its removal, imparts porosity to the composition and increases its viscosity such that slumping during the initial part of the firing is eliminated, thereby providing greenware suitable for firing, in that it retains its shape and combustion products from the polyolefin or other polymer and residual amounts of plasticizer can escape through the pores.
When plasticizer is used, it comprises about 10-40 wt. %, preferably 15-30 wt. %, of the total mixture. This is equivalent to about 0.1-0.35 cc/g, or about 30-70 volume %, preferably about 35-55 volume %.
Removable, finely divided fillers can be added to enhance porosity or for other purposes. For example, Al powder may be added which is substantially removed during the leaching step with NaOH. Other powdered fillers that can be removed in the NaOH or other aqueous solution include sugar, various salts, such as sodium carbonate, powdered urea, and the like. Some fillers can be added with a view of increasing bulk and/or strength in the final catalyst shape; i.e., they remain in the shape as used. Such fillers include TiO2, alpha-alumina, mullite, cordierite, etc. All are, of course, finely divided. The TiO2 may be expected to react with alumina to form aluminum titanate during the sintering process.
It is conventional to add stabilizers (antioxidants) and lubricants when fabricating polyolefin-containing materials. Such additives and the amounts and manner of their use are well known in the art. Representatives of stabilizers are 4,4 thiobis (6-tert-butyl-m-cresol) (xe2x80x9cSantonoxxe2x80x9d) and 2,6-di-tert-butyl-4-methylphenol (xe2x80x9cIonolxe2x80x9d). Stabilizers are burnt off during firing. Zinc stearate is a preferred lubricant, and may be used in up to a 0.5% concentration as an aid to give good dispersion of the solids in the polymer-plasticizer solution during compounding. Other commonly known extrusion aids, stabilizers, and coupling agents can advantageously be incorporated in said formulations.
In its simplest aspect, the formation of fixed bed catalyst involves mixing together only polymer and fine particles of nickel-aluminum alloy, omitting plasticizer, filler, etc. The mixture is shaped and at least a portion of the Al leached from the shape with NaOH solution to provide a shaped polymer-bound Raney fixed bed catalyst. In another embodiment using only polymer and alloy, following shaping, the shaped mixture is calcined to remove polymer and to sinter the alloy particles, then Al is leached out to form the final calcined catalyst.
Mixing of the initial components used to form the fixed bed catalyst utilized herein can be done by any conventional means. For example, they can be mixed using a Haake Rheometer, or a Banbury or Brabender mixer. When continuous compounding is desirable, the use of intermeshing twin screw compounders is desirable. An example is the MP compounder manufactured by Baker Perkins Co. and the ZSK compounder manufactured by Werner and Pfleiderer. Acceptable compounds may also be made by multiple passes through conventional single screw thermoplastic extruders.
In the specific case of where polyethylene/oil plasticizer is used, on cooling the mix, the oil separates as a finely dispersed liquid phase, readily removed as herein described.
The mixture thus comprises:
(a) particles of Nixe2x80x94Al alloy of a particle size of minus 50-mesh or finer, preferably about minus 100 mesh and more preferably minus 200 mesh: about 60-90 parts by weight, preferably about 70-85 parts;
(b) high molecular weight polymer, about 1-30 parts by weight, preferably about 2-20 parts; and
(c) plasticizer, 0-40 parts by weight, preferably about 10-30 parts by weight, equivalent to about 0-70 volume % of the total mixture, preferably about 35-55 volume %.
The resulting mixture is then formed into shapes, having regard to the geometrical form desired in the finished fixed bed catalyst. Extrusion is one of the simplest methods of shaping. For example, the mixture can be extruded in conventional extruders as solid rods, tubes (hollow or vaned), and filaments, all chopped into segments of the desired length in the known way. Some of the simplest and most effective shapes are pellets made by cutting {fraction (1/32)}, {fraction (1/16)}, xe2x85x9 or xc2xc inch diameter rods into one half to six times the rod diameter. Hollow cylinders and radial-vaned catalyst pellets may be made by various extrusion processes. See, e.g., U.S. Pat. No. 3,907,710 (Lundsager) and U.S. Pat. No. 4,510,263 (Pereira et al.) which discloses extrudes with a cylindrical, hollow annular configuration with internal reinforcing vanes. Other thermoplastics forming processes such as compression and injection molding may also be used. The general idea is that the mixture is shaped into final form prior to use (in the case of our polymer-bound catalyst) or prior to firing (in the case of our calcined catalyst). It is preferred to have the mixture heated during shaping since it is easier to shape the polymer containing mass when it is heated.
At this point the material of the shape is still identical in composition to the mixture of (1). It is ready for the next step:xe2x80x94removal of some or all of the plasticizer (e.g., mineral oil).
Plasticizer can be removed from the shape made in Step (2) by various methods. The two best are extraction with a solvent (e.g., hexane), or, if the plasticizer is sufficiently volatile (as are certain mineral oils), by heating the shape in an air circulating oven at about 100xc2x0 C. for a few hours, whereby the oil is vaporized and removed; in essence the shape is dried. Removal of plasticizer leaves a shaped composition consisting essentially of particles of Raney process alloy in a polymer matrix. That is to say, at this point the composition consists essentially of an intimate mixture of:
(a) particles of alloy, passing 50 mesh, preferably passing 100 mesh and more preferably passing 200 mesh U.S. Standard Sieve Size, about 60-99 parts by weight, preferably about 80-98 parts;
(b) high molecular weight polymer, about 1-30 parts by weight, preferably about 2-20 parts; and
(c) Homogeneous voids, left by removal of plasticizer, if any, of about 0.1-70 volume % of the mixture, preferably about 35-55 volume %.
As noted, in some formulations the plasticizer may be omitted, in which case there will of course be no plasticizer-generated voids. When a plasticizer is used, the voids occupy the same volume (or a little less) that the plasticizer occupied.
Here, as above noted, the invention branches. The next step can be either leaching Al with caustic soda solution as described in 4 below, or it can be calcination followed by leaching as described in 5 below.
(a) Leaching Al
We describe partial leaching out Al with strong caustic soda solution (typically about 6N). Leaching is done hot, for example at about 90xc2x0 C., but preferably not over 100xc2x0 C. Leaching with NaOH is exothermic, and cold water may be added periodically to maintain the temperature at 90xc2x0 C. Leaching may require several hours, and is preferably concluded with a fresh sodium hydroxide solution for an additional hour. The leached shape is then washed with water continuously until the pH of the water drops to less than about 9. The result is a shape consisting of a polymer-bound aggregation of Raney Ni fixed bed catalyst particles made by the Raney process. These particles are still connected by the original polymer matrix. At this point the shaped catalyst differs from the composition of (3) in that most or nearly all of the Al has been removed, leaving the Raney process metal. Thus the catalyst consists essentially of an intimate mixture of:
(a) particles of Raney Ni metal with residual Al, about 15-50 parts by weight, preferably about 20-47 parts by weight;
(b) high molecular weight polymer, about 1-30 parts by weight, preferably about 2-20 parts by weight; and
(c) homogeneous voids within the mixture, about 0.1-90 volume % of the total mixture, preferably about 40-80 volume %.
The composition has a surface area of about 20-80 m2/g and a macroporosity of about 0.1-70% of the total porosity.
Several methods of leaching are described by Freel et al. Journ. of Catalysis, vol. 14, No. 3, p. 247 (1969). We prefer leaching with NaOH solution.
5. We proceed now to the second alternate where the composition of (3) is calcined followed by sodium hydroxide leaching.
Calcination
The shapes of (3) are heated so as to remove polymer, followed by calcining to fuse the alloy particles to a porous metal structure. Simultaneously some of the Al metal is converted to alpha-alumina. Thus, the composition is calcined first in a furnace at about 200xc2x0-700xc2x0 C., preferably in the presence of air or oxygen. The temperature is increased and calcination is completed at temperature between 850xc2x0 and 1,200xc2x0 C. Calcination at 900xc2x0 C. for about 1 to 2 hours is optimum. It is pointless to continue heating beyond 1,200xc2x0 C.
The composition may gain weight during calcining because of the conversion of some Al metal to alpha-alumina. The weight gain may be typically 5-20% and is a consequence of an essential step in the formation of calcined fixed bed catalyst. The alpha-alumina xe2x80x9cspot-weldsxe2x80x9d or cements (sinters) the particles of nickelxe2x80x94aluminum alloy together.
The resultant shaped fixed bed catalyst precursor that has been calcined in the manner described above is then subjected to alkali to remove the aluminum and provide an activated fixed bed catalyst. The leaching can be accomplished in manners such as that described in 4 above.
The resultant Raney Nixe2x80x94Al fixed bed catalyst consists essentially of particles of Raney Ni and aluminum cemented together with alumina. The resultant material is highly porous having a gross composition of from about 20-50 weight percent Al2O3 and Raney Ni forming substantially the balance. The BET surface area is normally within the range of 20 to 80 m2/g and has a pellet density (weight divided by total pellet volume) of from about 0.5 to 2, such as 1.1 to 1.8 g/cc and a packed bed density of from about 0.4 to 0.7 g/cc.
The calcined extruded or pelleted fixed bed catalyst has a structure that contains macropores as well as micropores. The macropores extend throughout the fixed bed catalyst and provide porosity of at least 600 Angstroms. This porosity is attributable to the removal of plasticizer or the combined polymer/plasticizer component from the fixed bed catalyst. The microporosity is predominantly associated with the voids caused by the removal of aluminum from the precursor nickel-aluminum allow particulate used to form the fixed bed catalyst. The total void volume is normally about 30 to 70 volume percent of the fixed bed catalyst pellets. The total pore volume of the Raney Nixe2x80x94Al particles is normally about 0.3 to 0.5 cc/g.
It has been found that sulfur species can be removed from sulfur-laden hydrocarbon liquids by contacting the liquid with a Raney Ni fixed bed catalyst. The desulfurization of liquid fractions of a fluid catalytic cracking catalyst process is particularly suitable to the present process. The product streams of FCC processes are known to contain undesirable amounts of sulfur species, which, unless removed, may render the product unsuitable for use as a fuel in view of present environmental concerns. Thus, the present invention provides a means to economically, effectively and efficiently remove sulfur species from the hydrocarbon liquids without causing a detrimental impact on the remaining components of the treated liquid.
The Raney Ni fixed bed catalyst may be contained in a vessel, which is in line with the product stream of the sulfur-laden liquid of the petroleum refining process, such as a FCC unit. The fixed bed catalyst may be contained in a conventional fixed bed or moving bed reactor vessel into which the sulfur-laden hydrocarbon liquid is introduced. For example, the fixed bed reactor may have the form of a vertical cylinder in which the interior is divided by horizontal partitions. These partitions are perforated or foraminous plates or the like which aid in supporting and retaining the Raney Ni fixed bed catalyst while allowing the liquid being treated to pass through. Because the vessel is packed with the fixed bed catalyst, the liquid is required to incur a tortuous path through the fixed bed catalyst and be in intimate contact with the Raney Ni fixed bed catalyst. The sulfur-laden liquid is normally allowed to pass down through the fixed bed catalyst bed. Several fixed bed reactors are normally utilized in parallel to allow for continuous desulfurization while permitting regeneration of spent fixed bed catalyst, as described herein below. The resultant liquid product has been found to have very low levels of sulfur species remaining and, thereby, provide an environmentally desirable product.
Similarly, the Raney Ni catalyst may be contacted with the sulfur-laden hydrocarbon liquid used in a moving-bed reaction vessel. In this instance, the fixed bed catalyst and the sulfur-laden liquid are introduced into the moving bed vessel. This may be done in a concurrent or countercurrent (preferred) manner with the spent fixed bed catalyst and desulfurized liquid being captured.
The sulfur-laden hydrocarbon liquid and Raney Nixe2x80x94Al fixed bed catalyst are contacted at low temperatures and pressures. The materials are contacted at temperatures ranging from about 15xc2x0 C. to 150xc2x0 C., preferably from 20 to 125xc2x0 C. The pressure under which contact is accomplished is about one atmosphere although elevated pressure of from ambient to about 0.5 to 1 mPa (5-10 atmospheres)(with the use of inert gas, such as N2) may be used.
It has been found that the present process provides desulfurization of the liquid hydrocarbon feed without reducing the octane rating of the liquid. Thus, the olefinic components are not reduced to saturated compounds to cause a reduction in the octane rating of the liquid.
The Raney Ni fixed bed catalyst will be effective for a period of time, after which the rate of adsorption of sulfur species will decrease. The exact point when this change of rate occurs will depend on the liquid hydrocarbon being treated, the amount and type of sulfur species being adsorbed, and the type of contact being used. The rate can be readily monitored to determine when the fixed bed catalyst should be subjected to regeneration, as required by the present process.
The regeneration of the subject Raney Ni fixed bed catalyst can be achieved by:
i) treating the spent fixed bed catalyst with an aqueous solution of a mild chemical oxidant such as, for example hydrogen peroxide, an alkali metal hypochlorite (e.g. NaOCl), an alkali metal nitrate (e.g., NaNO3) or an alkali metal nitrite (e.g., NaNO2), an alkali metal perborate (e.g., NaBO3), peroxy acids (e.g., peroxy acetic acid) and the like. This is accomplished at ambient pressure and at temperatures extending from ambient to the boiling point of the aqueous solution, preferably from ambient to about 10xc2x0 C. below the boiling point. This may be followed by washing with water or a mild alkaline solution to remove unreacted oxidant and/or any remaining oxidized sulfur species;
ii) Treating the spent fixed bed catalyst with hydrogen gas at elevated temperatures of from 100xc2x0 C. to 500xc2x0 C., preferably from 200 to 400xc2x0 C.;
iii) Treating the spent catalyst with a mild chemical oxidant, as described herein above, followed by subjecting the material to hydrogen at elevated temperatures, as also described herein above. This method of treating the spent catalyst is most preferred as using mild oxidants alone may leave a portion of the catalyst in an oxidized state and thereby in a less active form and mere treatment with hydrogen may produce bulk sulfides which are difficult to fully remove. Combining the treatments in the stated sequence has been found to alleviate both of the concerns to produce an active catalyst substantially free of sulfur compounds; or
iv) Treating the spent fixed bed catalyst by contacting it with a metal salt of an organic acid provided a) the organic acid does not have high reactivity with the Raney Ni and b) the metal ion forms a sulfide (MSx where x is 1-5) which is insoluble in acidic and soluble in alkaline solution and c) the organic acid salt is at least partially soluble in water.
Organic acids which can be used to regenerate the Raney Nickel fixed bed catalyst include: saturated monocarboxylic aliphatic acids, e.g., formic acid, acetic acid, propionic acid, isovaleric acid, etc.; saturated dicarboxylic aliphatic acids, e.g., oxalic acid, maloric acid, succinic acid, glutaric acid, adipic acid, pimelic acid, etc.; saturated tricarboxylic aliphatic acids, e.g; hydroxy-substituted aliphatic acids, e.g., glycolic acid, lactic acid, gamma-hydroxybutyric acid, gluconic acid, malic acid, tartaric acid, saccharic acid, citric acid, etc.; and alicyclic acids, e.g., cyclopentane-carboxylic acid, hexahydrobenzoic acid, hexahydrophthialic acid, etc.
After the spent Raney Ni fixed bed catalyst and organic acid salt are admixed, the mixture is heated to at least about 40xc2x0 C. and held at that temperature for about 5 minutes residence time. The pH of the suspension is then increased to about 6.5 to 7.1 by the addition of base. The base is preferably in an aqueous solution. The temperature can be retained at the elevated level during this addition. At this point the insoluble metal sulfide produced in the organic acid treating step to a soluble condition so that it can be removed from the catalyst-base solution admixture by decantation, filtration or some other known technique of separating a solid from a liquid. Following such a liquid removal step, the rejuvenated Raney nickel catalyst is washed, preferably with a dried alcohol, to remove traces of the treating solutions.
The preferred modes of regeneration are those of ii) and iii) described above and the most preferred mode is that of iii) above.
The regenerated Raney Ni fixed bed catalyst can then be used to remove sulfur species from additional sulfur-laden hydrocarbon liquid. For example, when the fixed bed catalyst is used to pack a series of fixed bed reactors which run in parallel, the liquid can be treated sequentially through a single or multiple reactor(s) while the remaining reactor(s) of the series are subject to regeneration of its fixed bed catalyst in the manner described above. By alternating the reactors of the series, one can have a continuous process of forming substantially free hydrocarbon product conducted in an efficient and economical manner.
When an ebullating or moving bed reactor is used, the spent catalyst can be regenerated external to the reactor space in one of the manners described above and the regenerated catalyst can then be fed into the reactor.
It has been unexpectedly found that sulfur-laden hydrocarbon liquid, such as produced by conventional FCC processing of petroleum feed, can be readily desulfurized under low temperature and pressure condition. The presently required fixed bed Raney Ni catalyst, as described above, effectively removes the sulfur species from the hydrocarbon liquid under these mild conditions. Finally, the fixed bed catalyst, once spent of its ability to adsorb sulfur species, can be readily regenerated and reused to further remove sulfur species from additional sulfur laden hydrocarbon liquid. Thus, the present invention is directed to an effective and efficient process of desulfurization of liquids.

Process for sulfur removal from hydrocarbon liquids


An endoscope optical system unit includes an endoscope illuminating optical system and an endoscope objective optical system. The endoscope illuminating optical system includes a light-emitting section and a first optical-path deflecting prism group, which includes a first prism, a second prism, and a third prism. The endoscope objective optical system includes a lens group and a second optical-path deflecting prism group, which includes a fourth prism, a fifth prism, and a sixth prism. A direction of irradiation of illumination light by the endoscope illuminating optical system, and a visual field direction of the endoscope objective optical system, are variable by rotation of the prisms.

Field of the Invention
The present invention relates to an endoscope optical system unit.
Description of the Related Art
An endoscope is an apparatus that has been used widely in a medical field and an industrial field. Particularly, in the medical field, images of various parts inside a body cavity are captured by an endoscope inserted into the body cavity. A diagnosis of a part observed, is carried out by these images. In such manner, endoscopes have been used for observation and diagnosis of various body parts inside the body cavity.
A non-bending variable visual-field endoscope in which it is possible to change a direction of observation by driving an optical element at an interior of an objective optical system without bending an inserting section at the time of observing various parts inside the body cavity, has been known.
In the observation by such variable visual-field endoscope, it is desirable that a subject image in any direction of observation that can be achieved in the objective optical system can be observed with adequate brightness.
Illuminating in advance, regions in all directions of a range of variable visual-field for fulfilling the requirement may be taken into consideration. However, a range to be illuminated being wide, it is difficult to illuminate with uniform intensity in all directions. As a result, problems such as change in the brightness of subject according to the visual-field direction and uneven brightness in the subject image arise.
As another arrangement for fulfilling the requirement, an illuminating optical system proposed in Japanese Patent No. 4458211 Publication for example, has been known. In the illuminating optical system of Patent Literature 1, by making it possible to drive one optical element at an interior of the illuminating optical system, irradiation of illumination light followed by the movement of the objective optical system in the visual-field direction is made possible. With this arrangement, it is possible to illuminate uniformly in any visual-field direction, and furthermore, since it is possible to narrow a range to be illuminated at a time, the unevenness in brightness of a subject image is not susceptible to occur.


A cutting apparatus for cutting a sheet material includes a platform; a rail structure secured onto the platform; a sliding member sliding along the rail structure; a pressing plate disposed under the rail structure and engaging with the sliding member for pressing the sheet material against the platform in response to an external force, wherein a gap exists between the pressing plate and the platform for receiving the sheet material before the external force is exerted; an elastic member connected with and disposed between the rail structure and the pressing plate to keep the gap between the pressing plate and the platform by a recovery force thereof when the external force is released; and a cutting member carried by the sliding member for cutting the sheet material sustained on the platform.

Please refer to FIG. 1 which is a schematic diagram showing the structure of the cutting apparatus in common use recently. The cutting apparatus 10 includes a rail 11 and a slider 12. The slider 12 has thereunder a cutting member such as a blade (not shown) and slides along the rail 11. The user puts one or more pieces of paper to be cut in the space under the pressing structure 110 while using the cutting apparatus. Then, the slider 12 is pressed down to make the pressing structure 110 sustain against the paper to be cut. The pressed slider 12 is movable to slide to and fro along the rail 11, thereby driving the cutting member to pass through and cut the paper.
Please refer to FIG. 2 which is a schematic diagram showing the structure of a conventional cutting apparatus, e.g. as that shown in U.S. Pat. No. 5,671,647. In FIG. 1, the base portion of the cutting apparatus is illustrated, and the elements similar to the above-mentioned ones will not be redundantly described herein. The recovery force of the spring 20 overcomes the weight of the pressing structure 110, the rail 11, and the slider 12 to sustain against the pressing structure 110 and maintain the pressing structure 110 at an initial position. Meanwhile, a gap 111 exists between the pressing structure 110 and the bed 21. After the paper to be cut is put into the gap 111, and a downward force is exerted onto the slider 12 by the user, the downward force dominates the recovery force of the spring 20. Therefore, the pressing structure 110 will move down to contact the paper and fix it. The user then moves the slider 12 to cut the paper. The pressing structure 110 will automatically move back to its initial position by the recovery force of the spring 20 while the external downward force is released.
In the prior art structure, however, too many elements are involved for fixing, cutting and releasing paper. It is troublesome to assemble these elements due to the complexity. Furthermore, since the recovery force of the spring 20 has to overcome the weight of the pressing structure 110, the rail 11, and the slider 12 to lift them, it is necessary for the spring 20 to have great durability and strength. Accordingly, it is laborious to use this cutting apparatus. In addition, an undesirable cavity is required to be provided in the structure in order to secure the spring 20. It is an object of the present invention to solve the above problems.


A membrane or plate spring clutch on which there is an automatic wear adjustment mechanism, which wear adjustment mechanism takes into consideration only a portion of the wear which has occurred, and guarantees the required application force on the friction linings of the clutch disc, so that the torque transmission capability of the friction clutch remains constant over its entire useful life.

1. Field of the Invention
The present invention generally relates to a membrane or plate spring clutch, in particular, for a motor vehicle. The membrane or plate spring clutch includes a flywheel fastened to the crankshaft of an internal combustion engine, which flywheel defines an axis of rotation. The membrane or plate spring clutch also includes an application plate, which application plate is non-rotational in relation to the flywheel, yet the application plate can be displaced axially. There is a clutch disc with friction linings located between the application plate and the flywheel. The membrane or plate spring clutch also includes a membrane or plate spring to apply pressure to the application plate toward the flywheel. In addition, there is a retracting device for the application plate, as well as a mechanism for the automatic adjustment of the membrane or plate spring as a function of the wear of the friction linings.
2. Background Information
There are numerous conventional friction clutches which have an automatic wear compensation mechanism. For example, Unexamined German Patent Applications 43 06 688 and 44 12 107 disclose that, in the area of the contact between the membrane or plate spring and the application plate, adjustment elements with diagonal surfaces can be inserted which, when wear occurs, re-establish the original position of the membrane or plate spring in relation to the housing to keep both the position and the application force constant.

Friction clutch with automatic wear compensation


Seismic cable shielding method and apparatus. Shielding is obtained by switching unused wire pairs to ground via a roll-along switch which is connected to system ground. Grounding of the unused conductors in the cable is accomplished by ground connections at the roll-along switch. By grounding the unused conductor pairs (all pairs except those required for the sensor signals) within the cable, partial shielding is provided between the active wire pairs and cross-talk is reduced to a negligible level. Additional wire pairs are hardwired to system ground and distributed uniformly throughout the cable cross section to form an interstitial shield.

The present invention relates generally to the field of seismic exploration. More particularly, the present invention relates to a method of internal seismic cable shielding.
Seismic exploration data in the frequency band of 5 Hz to 150 Hz are presently gathered in the field using multiple twisted-wire-pair seismic cables in which the number of circuits is typically in the range from 100 to 250. Further, when acquiring seismic data, more wire pairs are typically deployed on the ground than are actually used at any one time. However, the quality of the multi-channel data is typically reduced because of crosstalk (cross-feed) between wire pairs in the cable as well as by pickup of 60 Hz and its harmonics from power lines. If 60 Hz becomes too great a problem, most seismic recording systems are equipped with notch filters that will cut this narrow band signal by 80 dB or more. However, notch filters have the undesirable property of distorting the phase of the desired seimic signals within the frequency range of about 50 to 75 Hz for a 60 Hz notch filter. This problem is not so severe when the bandwidth of interest in seismic recording ranged from 5 Hz to 50 Hz, but, as bandwidth capabilities have been expanded to higher frequencies in the range of 5 Hz to 250 Hz and above, this notch filter phase distortion effect falls in the frequency band of interest. The higher harmonics of the 60 Hz signals now also cause interference pickup problems. Because cross-talk between wire pairs within the cable is due to inductive and capacitive coupling, it also increases significantly for higher frequencies and as the length of the cable is increased.
One technique that can be used for decreasing cross-talk and power line pickup is to use shielded wire pairs (i.e., wire pairs with grounded mesh shields around each wire pair) and external cable shielding and grounding. However, shielded wire pair cable which utilizes such a technique is not normally used since it is more expensive, heavier, stiffer and more difficult to work with in the field than unshielded cable. As such, the art has heretofore lacked an appropriate method of seismic cable shielding which overcomes the foregoing limitations and effectively reduces internal cross-talk and 60 Hz pick up from external sources.


A method and apparatus for computing correlating images for image recognition is provided. In particular, the method is used to compare images of a biometric object to authorize an individual or verify whether an individual is the person he claims to be. The biometric objects may include fingerprints, hand or palm prints, and retina scans. The method uses a deviation of symmetry of correlation functions to determine whether the images are of a same object.

Image correlation is useful in several areas of practical application. For example, image recognition systems often use correlation of an acquired actual image and a reference image for comparison. In particular, images of biometric objects such as faces, retinas scans, fingerprints, and hand or palm prints, are compared using the image recognition systems to identify an individual or verify whether an individual is the person he claims to be for security. Image correlation is typically performed using Fast Fourier Transforms (FFTs), image shifting, or optical transformation techniques.

Method of correlation of images in biometric applications


An application specific integrated circuit (ASIC) includes ASIC logic and test logic that includes a fail-safe circuit and test logic circuitry. The test logic in conjunction with input and output test cells provides manufacturing test capability for the ASIC logic with a plurality of input pins and a plurality of output pins. The test logic generates several control signals that can affect operation of the ASIC logic. If any one of these signals is driven active by either a failure or a defect, the ASIC logic would be rendered inoperative. Consequently, each of these control signals is routed to the fail-safe circuit. These control signals include, for example, tri-state and reset signals and other control signals generated by test logic circuitry for the built-in testing of the ASIC. The fail-safe circuit generates a fail-safe control output signal for a corresponding control input signal from the test logic circuitry only during manufacturing testing when a fail-safe enable signal is applied to the fail-safe circuit. Preferably, the fail-safe enable signal is provided on one of the plurality of pins connected to the test logic so that the fail-safe enable signal cannot be generated by a failure or defect in the test logic circuitry.

1. Field of the Invention
This invention relates generally to application specific integrated circuits (ASICs) and in particular to a fail-safe structure that is included within the ASIC manufacturing test circuitry to assure that the test circuitry does not degrade the performance of the ASIC.
2. Description of the Related Art
In an application specific integrated circuit (ASIC), there are two general problems encountered in the manufacturing testing process. The first problem is that the ASIC logic itself is defective and the second is that the circuitry used to get signals into the ASIC logic and out of the ASIC logic is defective. Consequently, test logic is built into an ASIC that is used only in the manufacturing process to verify the operability of the ASIC. After the manufacturing process is complete, the ASIC test circuitry is passive and is no longer required or used.
Typically, the ASIC built-in test logic includes a built-in self-test (BIST) capability as well as a boundary scan capability. ASIC 100 (FIG. 1) includes both the built-in self-test capability and the boundary scan capability. ASIC 100 includes test logic 120, which controls the built-in self-test and the boundary scan capability, and ASIC logic 110.
The boundary scan capability is provided by input boundary scan register cells (BSRCs) 103-1 to 103-4, output boundary scan register cells 104-1 to 104-4, and test logic 120. The built-in self-test capability is provided by pseudo-random number generator cells 105-1 to 105-4, pseudo-random number signature analyzer cells 106-1 to 106-4, and test logic 120. ASIC 100 has four input pins 101-1 to 101-4 and four output pins 102-1 to 102-4.
As illustrated in FIG. 1, the configuration of the input and output boundary scan register cells 103-1 to 103-4 and 104-1 to 104-4 and pseudo-random number generator and signature analyzer cells 105-1 to 105-4 and 106-1 to 106-4 for each input pin and output pin is the same. Thus, the following description for input pin 101-2 and output pin 102-2 is applicable for any of the other input pins and output pins, respectively, of ASIC 100.
Input pin 101-2 drives an input boundary scan register cell 103-2, which in turn provides an input signal to pseudo-random generator cell 105-2 that in turn drives an input line of ASIC logic 110. Similarly, a signal on an output line of ASIC logic 110 drives pseudo-random number signature analyzer cell 106-2. The output signal of cell 106-2 drives output boundary scan cell 104-2, which in turn drives output pin 102-2.
Test logic 120 drives control lines for the input and output boundary scan cells and the pseudo-random number generator and signature analyzer cells. Typically, the built-in self-test and the boundary scan capability form an on-chip monitor architecture that conforms to IEEE 1149.1 standard. This standard requires that ASIC 100 have four additional pins, which are test data in signal pin TDI, test data out signal pin TDO, test mode select signal pin TMS, and test clock pin TCK. Test reset pin TRST* is an optional pin, but when test reset pin TRST* is used, the standard defines its use. In addition, most ASICs include, as illustrated for ASIC 100, an asynchronous ASIC reset pin RST and an asynchronous three-state output pin TRIST for use in normal operation of ASIC logic. However, for manufacturing tests, test logic 120 also typically includes a means for generating signals on lines TRISTATE and RESET to ASIC logic 110.
The built-in self-test typically includes an internal scan capability in addition to the boundary scan capability. The internal scan capability receives input signals from pin TDI, passes the signals through test logic 120 to ASIC logic 110 and the resulting signals from ASIC logic 110 are passed through test logic 120 to pin TDO. Test logic 120 generates a signal on line SS to configure flip-flops in ASIC logic 110 for the internal scan and in addition provides a clock signal CLK for the scan.
A common problem in manufacturing testing of ASIC 100 is that ASIC 100 fails to operate. The ASIC failure could be due to a multiplicity of reasons. For example, ASIC logic 110 could be defective. Alternatively, either test logic 120 or one or more of the cells used in the built-in self-test and boundary scan capability could be defective, and therefore prevent operation of the ASIC 100.
Unfortunately, at the time of manufacturing testing, there is no ability to determine the basis for the failure and typically the solution is to start over in the fabrication of ASIC 100 within a redesign of ASIC 100.
Also, either the boundary scan capability or the built-in self-test capability may introduce problems in the operation of ASIC 100, after ASIC 100 is provided to the customer. Ideally, the manufacturing test circuitry in ASIC 100 is only used during the manufacturing check out period and after that time is passive and its presence is unknown to the user. However, if, for example, the signal on line SS goes active after the customer receives ASIC 100, ASIC 100 goes into the internal scan mode, and therefore is no longer functional. Similarly, failures in test logic 120 may generate active signals on line TRISTATE or RESET that render ASIC logic 110 inoperable.
Failures in test logic 120 may create erroneous conditions in the input boundary scan register cells, the output boundary scan register cells, the pseudo-random number generator cells or the pseudo-random number signature analyzer cells. Any one of these faults in test logic 120 renders ASIC 100 inoperable.
The faults that may render ASIC 100 inoperable are further demonstrated by examining typical cells in ASIC 100 that are used that are used only for manufacturing testing.
A typical structure for an input boundary scan register cell 203 and a typical structure for an output boundary scan register cell 304 are illustrated in FIGS. 2 and 3, respectively. Input boundary scan register cells 103-1 to 103-4 are identical and are represented by cell 203 (FIG. 2). Output boundary scan register cells 104-1 to 104-4 are also identical and are represented by cell 304 (FIG. 3). Moreover, the basic structure of cell 203 and cell 304 are the same. The only difference in cells 203 and 304 is the source of the input signal for the cell and the use of the output signal from the cell.
Each cell 203, 304 includes two two-to-one multiplexers 211, 214 and 311, 314 and two D-type flip-flops 212, 213 and 312, 313. Test logic 120 drives five control lines which are used by cells 203, 304. If the signal on control line MODE is active, the input signal to cell 203, 304 is not simply passed through the cell. Rather, multiplexer 214, 314 passes the signal generated by D-type flip-flops 212, 213 and 312, 313 to the cell output line. Therefore, if test logic 120 drives the signal on line MODE permanently active, ASIC 100 is rendered useless.
A typical structure for a pseudo-random number generator cell 405 and a typical structure for a pseudo-random number signature analyzer cell 506 are illustrated in FIGS. 4 and 5 respectively. Pseudo-random number generator cell 405 (FIG. 4) represents pseudo-random number generator cells 105-1 to 105-4 and pseudo-random number signature analyzer cell 506 (FIG. 5) represents pseudo-random number signature analyzer cells 106-1 to 106-4. Each cell 405, 506 includes an exclusive OR gate, 416, 516, a D-type flip-flop, 417, 517, and a two-to-one multiplexer 418, 518. Each cell 405, 506 receives three control signals from test logic 120. If signal TEST.sub.-- MODE is active, the pseudo-random number built-in self-test feature is enabled. Accordingly, if signal TEST.sub.-- MODE goes active due to a fault in test logic 120, ASIC 100 is defective.
One difference in cells 405 and 506 is the source of the input signal and the use of output signal of the cell. The other difference is the number of input lines to the exclusive OR gate.
FIG. 6 illustrates a typical cell 600 within ASIC logic 110 that is used for internal scan testing. If the signal on line SS goes active for whatever reason, the ASIC logic that utilizes the flip-flops in the internal scan cell 600 becomes useless.
Thus, while the boundary scan capability and the built-in self-test capability included in ASIC 100 improved the testability of ASIC 100, these features also provide additional failure modes for ASIC 100. If these failure modes require re-design of ASIC 100 during manufacture, significant costs and delays in time to market are incurred. If these failure modes occur while ASIC 100 is being used by a customer, the customer is severely inconvenienced by the costs associated with the down time of the piece of equipment as well as the costs of replacing the failed ASIC. These losses result from passive equipment, which is used only in manufacturing testing, subsequently failing in a way that destroys the functionality of ASIC 100.

Fail safe, fault tolerant circuit for manufacturing test logic on application specific integrated circuits


Used oil is treated in a reactor to remove contaminants. The reactor comprises a rotating vessel forming an internal reaction chamber. The vessel is housed within a heating chamber. The inside of the vessel is indirectly heated by conduction through the vessel walls. The reaction chamber contains a permanently resident charge of non-ablating, granular coarse solids. Within the reaction chamber, the oil is vaporized and pyrolyzed, producing a hydrocarbon vapour. Coke is formed as a byproduct. Contaminants, such as metals and halides, become associated with the coke. The coarse solids scour and comminute the coke to form fine solids. The fine solids are separated within the reaction chamber from the coarse solids and are removed from the vessel through a pipe located at the axis of the vessel. The hydrocarbon vapours are also removed from the vessel through the axial pipe, as a separate stream. Residual fine solids are separated in a cyclone from the vapour stream. The cleaned vapour stream is then condensed to produce a substantially contaminant-free product oil. The contaminant-rich solids are collected for disposal.

Processes are known for reclaiming oil from contaminated used oil (sometimes referred to as waste oil).
One such process is disclosed in U.S. Pat. No. 5,271,808, issued Dec. 21, 1993 to Shurtleff. Shurtleff discloses a process wherein an inclined boiler heats the waste oil, vaporizing and driving off lighter hydrocarbons at temperatures of about 650.degree. F. Heavier hydrocarbons and contaminants, amounting to about 10% of the original oil, collect as a sludge in the bottom of the boiler. The sludge drains for disposal. The lighter hydrocarbons are condensed as a reclaimed oil product.
However, Shurtleff's process produces an oily waste which itself requires specialized disposal.
Other methods which can produce a reclaimed oil and an oil-dry contaminant typically involve subjecting the waste oil to thermal pyrolysis.
For example, in U.S. Pat. No. 5,423,891, issued to Taylor, a process is disclosed for the gasification of solids waste. Heat carrier solids (HCS) are first heated and then fed co-currently with hydrocarbon-bearing solids waste through a rotary kiln retort. The solids waste and HCS co-mingle, transferring heat. The resulting temperatures of 1200 to 1500.degree. F. are suitable to thermally pyrolyze the hydrocarbons in the waste. The resultant vapours are extracted for condensation. The retort solids and HCS are discharged from the kiln for recovery of the retort solids and re-heating of the HCS.
In Taylor's system the HCS are continuously circulated in a material handling loop. The HCS is a coarse granular solid which is heated outside the kiln and gives up its heat inside the kiln. Transport of the HCS around the loop involves considerable materials-handling equipment.
In U.S. Pat. No. 4,473,464, issued to Boyer et al., a process is disclosed for treating heavy crude oil. Carbonaceous solids are finely ground for concurrent feed with crude oil to an indirectly heated kiln. Pyrolyzed hydrocarbon vapours are condensed. Coke and carbonaceous solids are screened, ground and recycled outside the kiln. Heat loss to the solids is minimized and the crude oil is preheated to a temperature high enough to balance any temperature loss by the solids.
U.S. Pat. No. 4,303,477, issued to Schmidt et al., discloses co-currently adding a consumable fine-grained reactive solid to a waste material for binding metal and sulfur contaminants during treatment. The reactive solids, such as lime having a grain size typically less than 1 mm, and waste are thermally cracked as they progress through a rotating, indirectly fired kiln. The solids make a single pass through the kiln, the reactive solid being consumed in the process.
Some of the above described prior art processes involve significant material handling challenges in the recycling and conveyancing of large masses of hot, coarse solids. Other processes, which do not recycle hot solids, involve rejection of a portion of the oily waste or irreversibly consume a catalyst.
There is therefore a need for a simplified process for separating contaminants from used oils. It is the objective of the present invention to provide such a process.

Thermal apparatus and process for removing contaminants from oil

Alberta Oil Sands Technology & Research Authority