A selectable bandwidth filter has an analysis filter bank and a synthesis filter bank having M paths. A masking vector is disposed between the analysis filter bank and the synthesis filter bank. The masking vector enables select ones and disables unselected ones of the M paths, so as to define an output signal bandwidth.

A multichannel digital receiver simultaneously down-converts a set of frequency division multiplexed (FDM) channels residing in a single sampled data signal stream. In a similar way, a multichannel digital transmitter simultaneously up-converts a number of baseband signals to assemble a set of FDM channels in a single sampled data signal stream. The polyphase filter bank has become the architecture of choice to efficiently accomplish these tasks. This architecture uses three interacting processes to assemble or to disassemble the channelized signal set. In a receiver these processes are an input commutator to effect spectral folding or aliasing due to a reduction in sample rate, a polyphase M-path filter to time align the partitioned and resampled time series in each path, and a discrete Fourier transform to phase align and separate the multiple base-band aliases. In a transmitter, these same processes operate in a related manner to alias baseband signals to high order Nyquist zones while increasing the sample rate with the output commutator. As such, multichannel wireless digital receivers and transmitters are defined by the relationships between channel bandwidth, channel separation and channel sample rate.


Power supply efficiency may be provided. First, a total power supply capacity may be determined comprising a sum of a plurality of supply capacities respectively corresponding to a plurality of power supplies serving a plurality of components. Next, a load value corresponding to the plurality of components may be determined. A number of the plurality of power supplies may then be powered down. The number of power supplies powered down may comprise a value that may cause a remaining number of the plurality of power supplies serving the plurality of components to operate within an efficiency range.

A power supply is an electronic device that supplies electric energy to an electrical load. The primary function of a power supply is to convert one form of electrical energy to another and, as a result, power supplies are sometimes referred to as electric power converters. Some power supplies are discrete, stand-alone devices, whereas others are built into larger devices along with their loads. Examples of the latter include power supplies found in desktop computers and consumer electronics devices as well as commercial and industrial data and control systems.
Power supplies have a power input that receives energy from the energy source, and a power output that delivers energy to the load. In most power supplies, the power input and output consist of electrical connectors or hardwired circuit connections, though some power supplies employ wireless energy transfer in lieu of galvanic connections for the power input or output. Some power supplies have other types of inputs and outputs as well, for functions such as external monitoring and control.


An internally oriented perforating apparatus and associated method of perforating provide increased reliability in orienting perforating charges to shoot in desired directions in a well. In a described example, a perforating gun includes a tubular gun carrier, multiple perforating charges, multiple charge mounting structures and multiple rotating supports. The rotating supports are attached between the charge mounting structures, or at least between the perforating charges.

The present invention relates generally to operations performed and equipment utilized in conjunction with a subterranean well and, in an example described below, more specifically provides an internally oriented perforating apparatus.
It is sometimes desirable to perforate a well in a particular direction or range of directions relative to the wellbore. For example, in a deviated, inclined or horizontal well it is frequently beneficial to shoot perforating charges in a downward direction. However, certain circumstances may instead make it more beneficial to perforate in an upward direction, in a particular inclination from the upward or downward direction, or in another combination or range of directions.
To achieve this goal of perforating wells in particular directions, several attempts have been made to achieve reliable orientation of perforating charges downhole. Unfortunately, each of these has its drawbacks.
One method of orienting perforating charges downhole requires the charges to be rigidly mounted in a gun carrier so that they are pointed in the desired direction(s) relative to the carrier. The gun carrier is then conveyed into a wellbore and either laterally biased physically to one side of the wellbore so that the gun carrier seeks the lower portion of the wellbore due to gravity, or the gun carrier is rotatably supported with its center of gravity laterally offset relative to the wellbore. This method relies on the gun carrier rotating in the wellbore, so that the gun carrier may be oriented relative to the force of gravity. Frequently, such orienting rotation is unreliable due to friction between the gun carrier and the wellbore, debris in the wellbore, etc.
Another method of orienting perforating charges rotatably mounts the perforating charges in the gun carrier. The charges are mounted to a structure which extends substantially the length of the gun carrier. Rotating supports are attached at each end of the structure to permit the charges and the structure to rotate within the gun carrier due to gravity. Unfortunately, the structure is typically many feet in length and, with the charges mounted thereon, it tends to sag. This sagging of the structure permits it, or the charges mounted thereon, to contact the interior of the gun carrier. The contact prevents the charges from rotating in the gun carrier.
Therefore, an improved oriented perforating apparatus is needed. It is a purpose of the present invention to provide such an improved oriented perforating apparatus, as well as associated methods of perforating a well.
The principles of the invention are demonstrated below in an example of an internally oriented perforating gun which solves the above problems in the art by rotatably supporting the perforating charges periodically between ends of a gun carrier. This distributed rotational support prevents the charges, or their mounting structures, from contacting the interior of the gun carrier and preventing charge rotation. Well perforating methods are also provided.
In one aspect, a method of perforating a subterranean well is provided by the invention. The method includes the step of rotatably supporting multiple perforating charges within a single gun carrier by attaching at least one rotating support between selected ones of the charges. Each of the charges is directed in a respective direction. The gun carrier is conveyed into the well, with the gun carrier rotating as it is conveyed into the well. The perforating charges rotate within the gun carrier as the gun carrier rotates in the well, so that each charge remains directed in its respective direction.
In another aspect, a perforating gun for use in a well is provided by the invention. The perforating gun includes a generally tubular gun carrier, multiple perforating charges, at least one charge mounting structure for positioning the charges within the gun carrier, and multiple rotating supports permitting the charges to rotate within the gun carrier. At least one of the supports is connected between adjacent charges.
In yet another aspect, a perforating gun is provided which includes a generally tubular gun carrier, multiple charge mounting structures within the gun carrier, and at least a one rotating support connected between adjacent ones of the charge mounting structures.
The perforating apparatus provided by the invention may include a special thrust bearing for use between a charge mounting structure and a tandem, bull plug or other device attached to an end of the gun carrier. A specially configured weight may be used to laterally offset a center of gravity of a rotating assembly including the charges and mounting structure. The gun carrier may be provided with reduced wall thickness portions circumscribing the perforating charges, so that as the charges rotate within the carrier, each charge remains directed to shoot through one of the reduced wall thickness portions.
These and other features, advantages, benefits and objects of the invention will be clear to a person of ordinary skill in the art after careful consideration of the description of representative examples of the invention below and the accompanying drawings.

Internally oriented perforating apparatus


The invention is directed to a process for the production of sodium carbonate-anhydrate having a bulk density of at least 800 kg/m3, said process comprising:

The invention is directed to a process for the production of anhydrous soda, sodium carbonate anhydrate, with a bulk density of at least 800, preferably at least 1000, more in particular at least 1300 kg/m3, by crystallisation.
Soda is an important chemical, which is produced in large amounts. It is used, among others, in production of glass. There are generally two processes for this production, the so-called Solvay process and the trona process.
The former is based on the production of solid sodium bicarbonate, which is calcined into light soda anhydrate (crystal water free soda). This calcination is the chemical conversion of bicarbonate to carbonate, carbon dioxide and water.
The latter process is based on the mining of trona, mainly consisting of the double salt of sodium carbonate and sodium bicarbonate, with two water molecules, and varying amounts of contaminants. Trona is converted to soda, dissolved and purified. Subsequently soda is crystallised from the clear solution as the monohydrate, followed by drying to give light soda anhydrate. A review of the various aspects of the refining of trona is given in the paper by Aitala et al, Process for Selection Criteria for refining Trona to Commercial Products, presented at the First International Soda Ash Conference (ISAC), Jun. 11, 1997.
Light soda ash produced by either the trona-route or the Solvay process has a low bulk density. This results in high transport costs and gives rise to dusting during transportation and handling. Depending on the process used, this light soda ash has a bulk density of 550 (Solvay) or 800 (Trona) kg/m3.
A heat densification process can be used to increase the density of the product to about 1000 kg/m3. During this process hot water is added to the light product to produce monohydrate, which is immediately evaporated in a calciner to form anhydrate again. This requires a large amount of energy.
Sodium carbonate can be crystallised as various hydrates. In aqueous solutions, the anhydrous form (Na2CO3) is only stable at temperatures above 109xc2x0 C., which is higher than the boiling point at atmospheric pressure of a saturated soda ash solution (105xc2x0 C.). This means that evaporative crystallisation can only produce anhydrous soda at elevated pressures i.e. when the boiling temperature is higher than the transition temperature (the transition temperature is hardly influenced by pressure).
Because evaporative crystallisation in pressurised vessels is expensive, in the trona process the soda is often crystallised by evaporation of water at lower temperatures: Na2CO3. 1H2O or monohydrate is produced. After a drying step at 150 to 200xc2x0 C., whereby the crystal water is removed, the end-product is porous and usually has a bulk density of 800 kg/m3.
The conventional evaporative crystallisation, drying and heat densification steps require a high energy input. The resulting product, after heat densification is a dense soda, having a density of about 1000 kg/m3.
From earlier work it is known to produce crystal water free soda, i.e. sodium carbonate anhydrate, by direct evaporative crystallisation at atmospheric pressure from an aqueous solution. The driving force for the crystallisation in this process is the evaporation of water. In this process the boiling point of the saturated sodium carbonate solution is increased to a temperature above the transition temperature above which sodium carbonate monohydrate is unstable, by adding an amount of an organic solvent. Upon evaporative crystallisation sodium carbonate anhydrate can be recovered directly from the crystallising mixture, in a dense form. This sodium carbonate anhydrate has a bulk density of far above 1000 kg/m3, generally in the range of 1300 to 1600 kg/m3.
This system is limited to crystallisation by evaporation of the solvent, i.e. the water, which means that the economical application of the process is limited to those systems wherein all sodium carbonate is fully dissolved.
In view of the high energy requirements of the is conventional process (evaporating water in the monohydrate evaporative crystallization; removing the crystal water to produce anhydrate; heat densification treatment), it would be an important improvement if one or more of these steps could be deleted, without decrease of the bulk density of anhydrous soda.
Another, very profitable improvement would be if there could be provided a process for converting light soda ash to soda ash having a higher bulk density, without evaporation of water being necessary, i.e. a process to replace the heat densification process. Finally, it would also be very important to provide a process wherein soda ash of high bulk density is produced more or less directly from bicarbonate containing feedstocks, such as trona, or pure bicarbonate.
The present invention is based on the principle that when recrystallising soda from a dispersion thereof in an aqueous medium, it is possible to produce soda, free of crystal water, of high to very high bulk density, provided that the xe2x80x98water-activityxe2x80x99 of the systems is modified in such a way that the temperature of the crystallising system is below the boiling point of the system and above the transition temperature of the monohydrate-anhydrate transition. The crystallisation of soda anhydrate occurs here via a solution mediated conversion of one solid phase into another solid phase.
The invention in its broadest form is accordingly directed to a process for the production of sodium carbonate-anhydrate having a bulk density of at least 800 kg/m3, said process comprising:
providing a suspension of solid sodium carbonate and/or solid sodium bicarbonate and/or solid double salts at least comprising one of sodium carbonate and sodium bicarbonate, in a mixture containing water and an organic, water miscible or partly water miscible solvent, which solvent influences the transition temperature below which sodium carbonate monohydrate is stable, whereby the type and the amount of solvent is selected in such way that the said transition temperature is below the boiling point of the said mixture of water and an organic, water miscible or partly water miscible solvent,
in case sodium bicarbonate is present, converting the bicarbonate into carbonate,
crystallising sodium carbonate anhydrate from said mixture at a temperature above the said transition temperature and below the said boiling point, and
recovering the sodium carbonate anhydrate.
The term xe2x80x98solventxe2x80x99 as used herein indicates an organic water miscible or partly water miscible organic liquid, which influences the water activity, which will generally result in a decrease of the transition temperature of the anhydrate-monohydrate transition. This transition temperature is defined as the temperature in the phase diagram of sodium carbonate, above which the anhydrate crystal form of sodium carbonate is stable. The term xe2x80x98solventxe2x80x99 includes, unless otherwise indicated also combinations of two or more solvents.
The starting materials for the process of the present invention are the various forms in which sodium carbonate and bicarbonate occur or are produced. More in particular, as will become evident from the further discussion, the various crystal forms of sodium carbonate are important starting materials. Also the various double salts of sodium carbonate and sodium bicarbonate, optionally containing crystal water, such as trona may be used.
The various embodiments of the invention are all based on solution mediated recrystallisation or conversion, contrary to the evaporative crystallisation that is conventionally used for commercial soda production, and where the evaporation of water from the process is essential to cause crystallisation. The process of the invention accordingly has the distinct advantage of avoiding the evaporation step and thus of much lower energy requirements, thereby reducing the production costs. Further the invention allows it to produce soda of much higher bulk density, up to 50% higher, thereby reducing storage and transport costs.
The invention is based on influencing the water activity of the system, by adding organic solvents, as defined herein, whereby the transition temperature above which the anhydrate is stable and below which the monohydrate is stable, is decreased. In this system it is not relevant if the addition of the solvent increases or decreases the solubility of the soda.
A further aspect of influencing the water activity of the system resides in an improvement of the possibilities of steering the process performance. With a decreased transition temperature it is possible to determine the optimal operating temperature range. An important aspect is of course that the transition temperature is below the boiling temperature of the system at the pressure applied. At the transition temperature there will be no driving force for recrystallisation or conversion, as is clear from a schematic solubility diagram that can be plotted in the following manner.
The solubilities of sodium carbonate monohydrate (MH) and anhydrous soda (AH) can be plotted versus the temperature, at a constant solvent/water ratio and pressure.
At a certain temperature, the so-called transition temperature, the solubilities are equal.
At temperatures above the transition temperature the more stable AH has the lower solubility, while the less stable MH has a higher solubility. A solution which is saturated with MH, is supersaturated with respect to AH. Therefore, if these two solid phases are simultaneously present, AH crystals will grow. This leads to an undersaturation with respect to MH, which will dissolve. The rates of MH dissolution and of AH growth will become balanced at a certain soda concentration which lies between the two solubilities at that temperature. Since the maximum supersaturation of AH growth is limited by the solubility difference of AH and MH, and since this difference can be controlled via the temperature (at a given solvent concentration), the crystallization is well controlled. This is important for obtaining the desired high purity and bulk density (via the crystal size distribution).
At temperatures below the transition temperature the recrystallization takes place in the opposite direction: AHxe2x86x92MH.
By changing the temperature the difference in solubility can be regulated; the further the temperature is above the transition temperature, the higher the recrystallisation rate. By careful selection of the operating temperature, it is thus possible to regulate the rate of recrystallisation, whereby lower rates yield improved product purity, crystal quality and bulk density. On the other hand higher temperatures result in increased recrystallisation rates, thereby decreasing processing time and equipment costs, but at the cost of product properties.
An important aspect in the process of the invention is that the degree of supersaturation will never be high throughout the system, contrary to the evaporative crystallisation processes, where locally the supersaturation may become high. As a consequence there is much less chance of impurities being included in the crystals and of uncontrolled seed formation rate.
In the evaporative crystallisation processes it is only possible to regulate the amount of water being removed. In the process of the invention it is possible to control the maximum degree of supersaturation in a much better way by careful selection of the process conditions, resulting in purer product, better crystals and crystal size distribution.
In this respect it is to be noted, that this process, when used instead of the heat densification process, results in additional purification.
Even when the process conditions are selected in such a way, that the rate of crystallisation is low, it is possible by careful selection of process equipment, like number of crystallisers, classifiers (hydrocyclones), recirculation systems, to increase the total production rate again, thereby compensating for the loss in production rate in the actual crystallisation.
It is also within the scope of the present invention to repeat the solution mediated conversion of monohydrate into anhydrate to improve the purity and bulk density of the soda. This would imply intermediate anhydrate monohydrate solution mediated conversions.
In summary this means, that the use of the process of the invention results in a decrease of energy requirements, while maintaining the same product quality, or even improving it.
Starting from the general embodiment of the process according to the invention there are various options for carrying out this process.
One important embodiment of this process is based thereon that so-called light soda ash can be recrystallised or converted in a suspension, to give dense soda, having a much higher bulk density. In accordance with this embodiment light soda is slurried in a mixture of water and solvent, at a temperature below the transition temperature. Thereby the sodium carbonate anhydrate crystals are converted to monhydrate crystals by a solution mediated process. Subsequently the temperature of the resulting slurry of sodium carbonate monohydrate is increased to above the said transition temperature. The monohydrate crystals are converted to anhydrate crystals, as that has become the stable form, again by a solution mediated recrystallisation. During this conversion the anhydrate has a higher bulk density than before.
This embodiment can be used as treatment after the conventional soda process, instead of the heat densification step. An important advantage of this embodiment of the invention, compared to the heat densification step, is that no water need to be evaporated. In the heat densification step water is required, which has to be removed subsequently. In the process of the invention this is not the case.
Another area where the process of the present invention is important concerns the mining and refining of Trona. Trona is a raw material, mainly mined in the United States and in Africa, and consists of deposits of double salts of sodium carbonate and sodium bicarbonate in a molar ratio of roughly 1:1 and containing varying amounts of impurities, generally insolubles, varying from deposit location to deposit location.
For the purpose of the present invention the use of trona for producing soda is the only relevant one, although trona is also used for producing other materials. In the present case there exist already a number of ways to convert trona into sodium carbonate monohydrate. All methods are based on the principle that the sodium bicarbonate, through heating, is converted into sodium carbonate, thereby producing carbon dioxide and water. This conversion is generally carried out at increased temperature, the so-called wet-calcining temperature.
The present invention now provides an improved method for producing soda from trona (or another sodium bicarbonate source, such as the Solvay process).
According to one embodiment trona is calcined to yield a sodium carbonate, using known techniques. This carbonate is hydrated at a temperature below the transition temperature and subsequently converted to the anhydrate, as disclosed earlier, by recrystallisation.
In general it is to be remarked that the process of the invention has advantages in that it produces soda of increased bulk density, while requiring less energy. Accordingly the process may be applicable and advantageous, as soon as there is a need for producing anhydrous soda of bulk density comparable to or higher than that produced in accordance with the conventional processes. The advantages are generally the most pronounced when the soda produced has a bulk density of more than 1000 kg/m3, more in particular more than 1300 kg/m3.
The process of the invention is preferably carried out at ambient pressure, i.e. at atmospheric pressure, as this requires the least investments. However, a small over- or under-pressure may also be applied, as this does not require large investments and may result in operational advantages. Accordingly it is generally possible to use a pressure from 0.5 bar (abs) or higher. Under certain circumstances it may even be advantageous to use pressures up to 5 bar for the crystallization step itself.
The temperature of the recrystallisation step is a critical parameter, which is determined in relation to the required purity and the composition of the liquid system, i.e. water and one or more solvents. Of course the temperature should be below the boiling temperature of the system. This boiling point is determined by the amount and the nature of the solvent(s). Generally, the recrystallisation is done at a temperature sufficiently far below the boiling point that no substantial evaporation of the water and/or solvent occurs. Suitable temperatures for the recrystallisation are between 15 and 105xc2x0 C., more in particular between 45 and 95xc2x0 C. In case at least part of the recrystallisation step is combined with a calcination or decomposition of bicarbonate to carbonate, it should be taken into account, that the temperature is sufficiently high for the decomposition reaction to proceed at a sufficiently high rate. In that situation temperatures of at least 80xc2x0 C. are preferred, possibly combined with a slightly decreased pressure. The calcination step is included in the process in order to produce soda from the bicarbonate. Of course it is not necessary to include this step in case traces of sodium bicarbonate (resulting from incomplete calcination) are present in the product.
Another important parameter in the invention is the choice of type and amount of solvent. Contrary to the situation in the evaporative crystallisation, the solvent does not play a relevant role in influencing the boiling point (i.e. the solvent is not selected for its influence on the boiling point), but should decrease the transition temperature of the monohydrate-anhydrate transition, as defined herein. In order to get a sufficiently large decrease it is generally preferred to have an amount of solvent which is at least 5 wt % of the liquid phase, i.e. 5% of the combined weight of water and solvent.
The amount of solvent is also dependent on the nature thereof. A solvent having a large influence on the water activity may be used in smaller amounts than a solvent that has a smaller influence. In general it is, however, preferred to have an amount of solvent of at least 20 wt. %, whereby the upper limit is generally determined by its influence on the solubility of the soda (which is generally negative). It is of course important that the soda has a sufficiently high solubility product to be able to carry out the solution mediated recrystallisation. For this purpose the solubility may, however, be much lower than is necessary for the evaporative crystallisation. Generally, the upper limit of the amount of solvent will be 90 wt. %.
As indicated already, the nature of the solvent plays an important role in the process of the invention. In the first place it should be stable under the process conditions and it should not interfere with the stability and quality of the soda. Preferably it should also be of such nature that minute amounts left in the soda are not detrimental to the future use of the soda. Finally, it would be advantageous if the adhering solvent could be removed from the soda, after separation of the soda from the mother liquor, in an easy manner, for example by washing or evaporation.
Taking all the aspects into account, some of which are more important than others depending on the use of the soda, one can define a number of groups of organic solvents.
As a most general definition the solvents can be defined as those water miscible or partly water miscible organic compounds that influence the water activity of the system. This tends to exclude the pure hydrocarbons, as their influence is limited and further they are not really sufficiently water miscible. However, all substituted hydrocarbons and all hydrocarbons containing one or more hetero atoms may be tested for their suitability.
Preferred compounds are the various hydroxy group containing compounds, ether group containing compounds, amine group containing compounds, aldehyde group containing compounds, keto group containing compounds, carboxy group containing compounds and the like.
More preferred are the mono- and polyhydroxy compounds such as the monoalcohols, including the lower alcohols having 1 to 6 carbons atoms (methanol, ethanol, propanol, butanol, pentanol and hexanol, which may have straight or branched alkyl chains), polyols, such as glycols, glycerol and the like are deemed suitable. Most preferred are the low molecular weight polyols, such ethylene glycol, diethylene glycol, glycerol, 1,2-propane diol, 1,3-propane diol, the butane diols, polyethylene glycol, polypropylene glycol, polyethylene-propylene glycol (those glycols having a molecular weight between about 150 and 600) and the like.
Amines may be used, provided that they do not react with the carbonate group. An other group of potentially suitable compounds are the amides and nitrites. Ethers, ketones and aldehydes may also be used, whereby especially suitable compounds are acetone and methyl-ethyl ketone.
The various reactions can be carried out in equipment that is conventional for this process. No specific design is necessary, beyond the standard and routine amendments generally necessary, taking into account the process conditions. As soda production is generally carried out continuously, it is preferred to use two or more reactors for each recrystallisation or conversion step.
In the prior art, the monohydrate process is the most widely applied method to produce soda ash from trona (Na2CO3. NaHCO3. 2H2O). This process is now described. A number of unit operations is deployed to convert the feed into the light soda ash. First the trona is calcined. When water and carbon dioxide are removed, a porous raw soda produce is left with, typically, 10 w % of impurities (silicates mainly). To remove this non-soluble impurities, water is added to selectively dissolve the soda. The impurities are then removed by means of filtration and a clear brine stream is then fed to the evaporative crystalliser. Usually a cascade of three evaporative crystallisers is used to produce the monohydrous soda form which is stable at the operating conditions. After the monohydrate is removed from the slurry, it is calcined into light soda ash with a density of about 800 kg/m3. A final step in the product process usually is the bulk densification of the soda ash. A heat densification treatment in a third calciner increases the bulk density up to 1000 kg/m3.
Light soda produced according to the solvay process also has a low bulk density (of about 550 kg/m3) due to the fact that in the final step of the process sodium bicarbonate is calcined. Upon the evaporation of water and carbon dioxide a very porous product results that is also subjected to the thermal treatment to increase the bulk density.
Light soda from both the monohydrate and the Solvay process can be used in an embodiment of the invention. The anhydrous light soda is added to a series of crystallisers 1 that are operated at such conditions that monohydrous soda is stable. The anhydrate will therefor transform into monohydrate. The transition from monohydrate into anhydrate (and vice versa) is a solution mediated transition in which the unstable hydrate will dissolve, resulting in a supersaturation for the stable phase which then crystallises. Since the rate of recrystallisation in a certain mixture is depending on the temperature only, the supersaturation may be kept at a desired, low value which results in a pure product of large crystals.
The soda monohydrate is transferred to a second series of crystallisers that are operated at a temperature above the transition point of the applied mixture. Under these circumstances monohydrate will transform into anhydrate again. After filtration (or another wet classification), the mother liquor is used to heat the monohydrate slurry and then recycled into the first series is of crystallisers.
Instead of using light soda ash, it is also possible to apply calcined trona as a feed stream. One major disadvantage is, however, the presence of impurities in the calcined trona. Therefor, one adjustment is made to the flow scheme. After the first series of crystallisers, a cyclone (or another wet classifier) is added to separate the fine impurities from the large monohydrage cyrstals.
Another option is the solution mediated recrystallisation of the monohydrate that leaves the crystallisers in the monohydrate process. Instead of calcining, the monohydrate is added to a mixture of water and (anti) solvent. Due to the temperature and mother liquor composition, the transition temperature is lower than the actual crystalliser temperature and anhydrate will be formed. Notice that when monohydrate is added and anhydrate is the product, water has to be removed somewhere in the process. It is possible to treat a small part of the clear liquor mother by means of distillation. In case a high boiling solvent is applied, water will be the top product, while sod and (maybe) some of the impurities will be precipitated in the bottom product flow. In case a solvent is used having a lower boiling point than water, the solvent will be the topproduct.
Another option is the solution mediated conversion of trona: raw trona (with impurities) is added to the crystalliser together with concentrated solvent. The conversion is carried out at a temperature below the conversion is carried out at a temperature below the mixture""s boiling point. Due to the high temperature, the trona will decompose. Anhydrous soda, carbon dioxide and water are formed. The carbon dioxide leaves the crystalliser due to the solvent""s water-binding behaviour. The calcination step is carried out below the mixture""s boiling point. Then, the soda is separated from the impurities in a series of settling tanks or other wet classifiers. By cooling down the mixture in the second series of crystallisers, monohydrate is formed when the temperature is below the transition temperature (if necessary water can to be added). Subsequent heating in the third series of crystallisers will produce anhydrate again. When the supersaturation is kept low (i.e. a temperature just above transition point of the mixture) the size of the anhydrous particles will be large. Finally, the product is separated from the slurry and the clear mother liquor is treated in e.g. a distilling column: water is purged or recycled within the flow sheet, the high-boiling solvent is returned to the first crystalliser.
A comparable flowsheet is proposed for the wet calcination of sodium bicarbonate. The only difference is that due to the high purity of the feed, no settling tanks and filters are needed to remove insoluble impurities.
The invention is now elucidated on the basis of an example, which is not intended as limiting the invention.

Process for the production of sodium carbonate anhydrate


An improved inflatable habitation volume in space comprising reduced cost, improved debris impact protection, enhanced penetration resistance, self sealing qualities, innovative flat end caps, industry accepted commercial design/manufacturing techniques, enhanced inflatable assembly techniques and expanded interior volume. Costs are reduced by compressing the launch package, removing the three gravity launch load requirements from the transportation process and inflating in microgravity. The inflatable habitation volume unit can be connected to either existing orbital facilities or connected to similar units to create expanded volumes and space tourist torus structures rotated for partial gravity.

No government finding, no government support or government contract or clause is related to this concept.
A portion of the disclosure of this patent document contains material that is subject to copyright protection. The owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyrights whatsoever.
1. Field of the Invention (Technical Field)
The present invention relates generally to a pressurized volume in space, transported in the deflated condition and inflated in the vacuum and microgravity of orbit for use as habitation or other volumes like space stations.
2. Background Art
Space tourism is expected to be a future industry in space, but many believe two orders of magnitude in cost reduction must be achieved before this new industry emerges. A traditional habitation module in the range of $425m is transported in the space shuttle for approximately $500m. The typical metal module weighs approximately 38,000 pounds and provides approximately 4,600 cubic feet of pressurized interior volume. This means the current state of the art habitation module costs approximately $24,000 per pound or approximately $201,000 per cubic foot of internal volume. Habitation in space is important to this emerging space tourism industry. The current reusable launch vehicle transportation is in the range of approximately $4,000 per pound, so additional innovation is required in both transportation and module design to reach the space tourist cost goal. Getting the cost reduced is important to the emergence of this new industry. Two orders of magnitude in cost reductions are difficult to achieve.
If an innovative, inflatable habitation volume in the range of $50m is transported in a reusable vehicle for approximately $20m, then a near term space tourist market may emerge. The module weighs approximately 5,000 pounds and provides approximately 21,000 cubic feet of useful pressurized interior volume. Assume a second trip of a reusable vehicle for approximately $20m is required to infill the volume with additional ECLS equipment worth $30m for a total $80m in orbital habitation hardware costing $40m to transport. This means the inflatable state of the art goal for a habitation module could be in the range of costs like $15,000 per pound or $7,142 per cubic foot of internal volume. This assumption is still too expensive to satisfy the two orders of magnitude in cost reduction.
Assume the space tourism industry matures and the space transportation, in hardware and operations, brings costs to a point closer to the airline tourist industry, then what assumptions are anticipated in cost? If maturity in reusable transportation and inflatable technology is achieved in cost, then a second-generation inflatable habitation volume in the range of $25m is transported in the reusable launch vehicle for approximately $10m. The module weighs approximately 8,000 pounds and provides approximately 21,000 cubic feet of pressurized interior volume. This means the inflatable state of the art goal for a habitation module is in the range of $4,375 per pound or $1,667 per cubic foot of internal volume. This is still above two orders of magnitude of the goal of $240 per pound, but just below the $2,010 per cubic foot goal for space tourist industry stimulation and emergence.
The advantage of the present invention is an operational habitation module that works together in an integrated cost effective manner to contain the interior pressurized volume, provide Environmental Controlled Life Support Systems (ECLSS) required for humans, protect the integrity of the pressure envelope, transfer cargo, maintain the pressure and other gases at proper pressure including timely repair, and expansion as required. The inflated pressurized volume provides near earth pressure, protection from temperature extremes, particle impact and other hazards in microgravity.
The present invention relates to inflatable structures in space, specifically to a new design for an inflatable habitation volume, to an improvement or modification of the fabrication/design of an early NASA inflatable design and to the future utilization of both the new concept and the enhanced NASA inflatable TransHab Module design. The transportation costs are reduced, because the inflatable is transported to orbit before it is inflated and can be further enhanced by future launches.
Metal habitation modules are currently used for space stations, because these high strength alloys are needed to withstand the three gravity launch loads, the pressure loads from the 14.7 psia interior habitation pressure in orbit, the high speed particle impact and puncture loads in orbit and other loads resulting from the temperature extremes and misc loads. These loads vary greatly with location, transportation and duration and result in significant metal weight. The design loads from transportation are relatively short in duration, but generally drive the design, because they are in the range of three times gravity. The interior pressure load is significantly different from the launch loads and drive the metal design toward becoming a sphere in shape, while the typical transportation volume is a cylinder. The particle impact loads force the design into a series of mass barriers used to break up the particle before it strikes the pressure shell. The key to an impact barrier is the proper spacing of each impact barrier from the pressure bladder or other barriers and requires a specific distance to become effective, which reduces the interior volume of a metal module solution. This design weight required to resist these separate loads must be transported to orbit on expensive transportation systems in the range of $10,000 per pound.
The background art explores various ways of obtaining more interior volume with less transportation cost by composite forms, clever packing methods, folding struts, furlable metal segments, air supported earth based structures, inflatable nose missile cones, flat end caps, telescoping walls and salvaging existing hardware in orbit.
U.S. Pat. No. 4,730,797, to Minovitch, et. al., entitled xe2x80x9cINFLATABLE CORE ORBITAL CONSTRUCTION METHOD AND SPACE STATIONxe2x80x9d is a construction form inflated in orbit and used to hold wraps of other materials to form large space volumes. Although suggested as automatic, outside (extra vehicular activity, EVA) labor in orbit for the portions of this device that can not be automatic must be performed in a microgravity vacuum, which is very expensive. Without gravity, typical construction techniques in one gravity do not work in microgravity and vacuum. There is no mention of solutions for launch loads and pressure used for habitation in orbit, plus the high-speed particle impact protection that works in orbit. There is no phased build up to soften the initial financial impact of the project.
U.S. Pat. No. 4,744,533, to Mullen, et. al., entitled xe2x80x9cMODULAR SPACE STATION,xe2x80x9d is altering the building materials into hollow module xe2x80x9cUxe2x80x9d shaped segments designed to fit within the space shuttle""s payload bay and assembled in orbit. The resulting square hut shaped space station with a square structural shape is not consistent with a minimum material/weight structure similar to a sphere, which drives pressure volume designs in a vacuum. The structure requires many joints to be made in space and appears to require many outside labor intensive joints. The details of the joints are not given, but the joints are in tension and worse result in a ripping load configuration. The outside labor in orbit for the joint portions must be performed in a microgravity vacuum and is very expensive, because no joints can be made from the inside, until the entire structure is pressurized, which requires all joints to be completed. Without gravity, typical labor intensive construction techniques in one gravity do not transfer well in to microgravity and vacuum. This design is overly focused on accommodating the transportation envelope and lacks much construction consideration of the problems and remote conditions in orbit. While the ""533 Patent solutions for launch loads and volume are used, little else is considered in the design life of the structure. The classic approach of altering the building materials to fit the transportation device is the wrong direction to proceed for cost reduction.
U.S. Pat. No. 5,184,789, to Aldrin, entitled xe2x80x9cSPACE STATION FACILITY,xe2x80x9d is a standard space station with metal pressurized modules and lots of struts. The modules are standard and the struts fold in the center to fit within the 60xe2x80x2 long space shuttle. This means the struts are xcx9c120xe2x80x2 long and the modules larger than any known launch vehicle could carry. It is not clear what value the struts provide; do they make the modules lighter and how do they address the primary commercial issues of transportation weight and cost?
U.S. Pat. No. 5,451,975, to Miller and Nyden, entitled xe2x80x9cFURLABLE SOLID SURFACE REFLECTOR,xe2x80x9d is a metal expanding structure with interlocking metal panels expanded to create a reflector. It is not meant to be a pressure volume, but the metal interlocking with metal might provide a pressure seal, but would be difficult to repair, if a high speed particle impact were to occur. While this solution may address launch loads in the compressed configuration and provide a reduced volume, however little else applies to the design life of a habitation volume structure in orbit. It does not appear the expandable metal to metal joint could be pressurized.
U.S. Pat. No. 03,836,417, to Yaeger, et. al., entitled xe2x80x9cLAMINATE FOR HUMAN HABITATIONxe2x80x9d is earth based air supportable structures with rigidized beams on the surface of the earth, but in a microgravity/vacuum environment the pressure alone provides the structural strength. These composite materials do not appear appropriate for microgravity, vacuum and impact uses. The composite layers suggested contain metal flakes, which may result in significant weight.
U.S. Pat. No. 4,024,679, assigned to Irvin Industries, Inc., to Rain, et. al., and Mclorg, et. al., entitled xe2x80x9cAIR SUPPORTED STRUCTURE MEMBRANE CONFIGURATIONxe2x80x9d is surface based air supported volumes with multiple layers and structural beams rigidized by air on the surface of the earth. In orbit in a microgravity environment of space, the inflation pressure alone is sufficient for strength. These composite materials do not appear appropriate for microgravity, vacuum and impact uses, however the material does have limited radiation protection.
U.S. Pat. No. 5,464,172, to Jensen, et. al., and Allen, et. al., entitled xe2x80x9cDEPLOYABLE MASS AND SENSOR FOR IMPROVED MISSILE CONTROLxe2x80x9d is an inflatable missile nose cone folded to decrease its transportation volume, but fails to address the habitation, transport packing, human aspects or the orbital particle impact hazard environment.
U.S. Pat. No. 4,562,979, to Taylor, et. al., entitled xe2x80x9cEXPANDABLE SPACECRAFTxe2x80x9d is a telescoping metal module innovation in an attempt to double the interior volume using a shorter module in transport and less metal. The ""979 Patent to Taylor in Jan. 7, 1986 also used difficult to use seals in the extended configuration. The extra metal required to react to the launch loads encountered and provide a maximum of pressurized manned volume in orbit added significant weight. The ""979 Patent is an attempt to expand the habitation volume in orbit, but uses metal and it is heavy. The metal module based on the Spacelab design in Europe is limited to fifty days on orbit and has limited impact protection. The removal of the module from the space shuttle is complicated in orbit and the Spacelab Module requires the Environmental Control Life Support Systems (ECLSS) from the orbiter.
U.S. Pat. No. 4.867,395, to Taylor, et. al., and Citron, entitled xe2x80x9cFLAT END CAP MODULE FOR SPACE TRANSPORTATION SYSTEMSxe2x80x9d is a flat end cap on each end of a truncated cylinder module. SPACEHAB is a pressurized module in the space shuttle payload bay based on this patent that has reduced the cost of manned tended research in the space by a factor of ten. The device reduces the transportation costs by being shorter, by using disc end caps and the truncation permits safety waivers in the space shuttle. The manned module is not manned during ascent, but does take advantage of approximately 5 feet of module less length, which reduces the space shuttle price by about {fraction (5/60)}th times the launch cost. The module is truncated to allow a suited EVA astronaut access to the payload bay door latches in orbit. The system replaced a nearly identical European supplied module system ($920 million) called xe2x80x9cSpacelabxe2x80x9d with a commercial start-up venture with $105 million in private funds, an innovative hardware solution and the same structure subcontractor. Spacelab was built by a consortium of countries in Europe based on design from an American aerospace contractor. Using less labor and the same contractors that learned on the European Spacelab system reduced costs. The innovation of flat end cap module severely complicated the design and increased the metal structure into the range of 10,000 pounds, but the length of the module was the launch cost criteria and not the weight. Most of the reduction in cost was from the differences in the work force required in government versus commercial operation. The metal module design is limited to fifty days on orbit and has limited impact protection. The removal of the module from the space shuttle is complicated in orbit, because the SPACEHAB requires the Environmental Control Life Support Systems (ECLSS) from the orbiter.
U.S. Pat. No. 5,813,632, to Taylor, et. al., entitled xe2x80x9cSALVAGE HARDWARE APPARATUS AND METHOD FOR ORBITING OBJECTS,xe2x80x9d is salvaging hardware transported to orbit for other reasons and potentially available. The ""632 Patent could create a metal pre-tested pressure volume capable of habitation. For example, the volume of the salvaged liquid hydrogen tank is 55,000 cubic feet worth approximately $11 billion by today""s habitation module costs of $201,000/CF. If two orders of magnitude of cost reduction were desired, then the developers would have $110 million to develop the interior of the salvaged hydrogen tank in orbit to achieve the goal of two orders of magnitude reduction in cost ($2,010/CFxc3x9755,000CF=$110m).
The ""632 Patent uses a systems package to accomplish the salvage of the discarded tank hardware in orbit and proceed to use the pressurized tank volume for new uses including a habitation configuration. No extra metal is required and no transportation costs are incurred, except for the salvage systems package, the material and labor used to develop the interior of the ET in orbit. The transportation loads encountered by the tank are not changed on ascent and later the tank is reused to provide a maximum of pressurized manned volume in orbit (pre-tested to +40 psia) with added interior and Environmental Control Life Support Systems (ECLSS) placed inside the tank in orbit. The ""632 Patent is an attempt to develop, the habitation volume in orbit from existing materials, but the ET is metal and its heavy.
The device requires significant cooperation from the governments launching large vehicles. The original tank design is limited to eight minutes of ascent use and lacks the impact particle barrier beyond the existing aluminum pressure envelope, which provides some limited impact protection. The removal of the inserts and the ECLS Systems from the space shuttle and placement into the interior of the tank is outside labor intensive and complicated in orbit plus the operation uses the orbiter and on-orbit EVA labor, all of which are expensive. This patent does salvage an ET in orbit with a mass that would cost $611 million to transport to orbit any other way.
There are few inflatable habitation modules in the prior art. U.S. Pat. No. 5,350,138 to Cubbertson, Rogers, and Ware, entitled xe2x80x9cLOW COST SHUTTLE-DERIVED SPACE STATION,xe2x80x9d discloses a combination of an external tank and the space shuttle using pre-positioned inflatable inserts instead of inserts placed in orbit as suggested in the present invention. Altering the external tank before launch in any way requires a re-certification, which is very expensive.
U.S. Pat. No. 5,305,970, to Porter, Johns and Caudle entitled xe2x80x9cCENTRIFUGAL SPACE PROPELLANT STORAGE AND TRANSFER DEPOTxe2x80x9d uses a torus shape to transfer propellants, but is not manned. The massive structure suggested borders on the upper end of the expense envelope.
Inflatable structures for unmanned applications such as re-entry decoys and light solar array structures have been used in space to achieve lighter weight payloads, but inflatable manned modules have not been tested in orbit.
A TransHab Concept is a NASA initiative in 1998-99 and is a relatively simple design for an manned pressurized volume capable of being transported in the space shuttle and inflated in orbit. The concept used a weaved strap design restraining a spherical pressure envelope into a cylinder and a series of composite layers used to break down high speed particles in space. The design can be seen at website: http://technology.jsc.nasa.gov/habconference/ and is shown as a dotted structure in the drawings in the present invention.
The present invention is directed to a new inflatable habitation volume in space using an apparatus that does not use the NASA design or design direction. The present invention creates an inflatable volume in space with flat end caps, fabricates with large composite winding machines, uses commercial techniques and provisions for commercial advertising, transports in a smaller reusable launch vehicle (RLV), but could be scaled up to fit in the space shuttle. The GLOBAL OUTPOST, Inc. TransHab Concept was drafted by the inventor and was submitted to the NASA Johnson Space Center. The six month discussion and proposal period started in mid August 1999 and progressed through November 1999 with 2 concept papers of under five pages each and two entrepreneurial business proposals over 150 pages each by the company to NASA for 20 years of ISS habitation volume work to satisfy NASA requirements for costs between $150 to $204 million with $204 million as the NASA stated budget. The concept evolved and focused on a desired NASA Module. GLOBAL OUTPOST enhanced the NASA TransHab module into a business proposal with the addition of other commercial modifications to the NASA TransHab Module including, but not limited to different fabrication techniques, a focus on NASA requirements for manned habitation facilities, but also an unmanned business proposal design offering commercial services at ISS in an entrepreneurial manner. The NASA Proposal process for the $204 million TransHab entrepreneurial exploration of the inflatable alternative was terminated with NASA awarding Boeing approximately $400 million to complete the aluminum habitation module in progress.
A second part of the present invention includes the inventor""s enhancements to the NASA TransHab Concept. The NASA device was fabricated in a prototype design and tested in a large vacuum chamber but used a simple design not generally used in the composite industry.
In contrast to the above described references, the present invention launches in the deflated condition, inflates in orbit, provides a pressurized volume for humans, protects the habitation environment and expands into other uses in a cost effective manner.
This present invention is a new inflatable module design using the flat end cap and an inflatable device. The present invention also modifies, expands and improves on an original NASA TransHab inflatable module design. The NASA TransHab Module is shown dotted in the drawings.
The present invention eliminates the requirement for the finished structure to withstand the launch loads, generally three times normal loads, and significantly higher and different than the module loads the structure will experience in orbit. The present invention also is a lighter weight solution for the same amount of enclosed volume when compared to a traditional metal habitation module. Lighter weight impacts the cost by reducing the mass transported to orbit. With maturity this inflatable solution combined with the reusable launch vehicle can provide the two orders of magnitude in cost reduction required for space tourist activities to emerge.
The inflatable volume apparatus comprises an inflatable volume transportable to space in the compressed form, a connector providing connection between the inflatable volume and other devices, and an expandable interior structure comprising tension cables.
The apparatus of inflatable volume comprises at least one layer and the layers including an architectural surface layer with one or more functions. These surface functions include color, wearable and washable surface, acoustical treatment, minor attachment points for light, pictures and other removable items leaving the surface capable of quick access by inhabitants for repair. The repair uses a gel layer with part A of a multi-part chemical compound, which produces structural foam when mixed with part B. The combined mixture is transported to a puncture location in the pressure envelope by the escaping interior gases. An instrumented mesh containing the ability to detect and pinpoint a break in closely spaced wire, fiber or conducting ceramic mesh and part B of a multi-part chemical compound, which produces a structural foam when mixed with part A and transported to a puncture by escaping interior gases.
The apparatus also contains a pressure bladder layer containing the internal pressure boundary layer in a non rip flexible envelope material capable of compressed transport, inflation in space and repair in a vacuum microgravity environment. This containment barrier of foldable composite materials is used to contain the spherical pressure bladder in a more useful semi-spherical shape. A series of bullet proof like material barriers are used to break up high-speed particles traveling with high energy. These separate high speed particle break-up barriers are separated by compressed foam powder activated in the inflation process and maintained at a proper space or distance between barriers with restraint loops after inflation. The spacing of the barriers is critical to breaking up the high-speed particles and dissipating their energy over a wider area of the structure, so a puncture does not occur. An exterior layer capable of foldable transport is on the outside and consistent with the temperature, solar radiation and other conditions of the space environment.
The apparatus has a material, which requires only being transported in a contained manner rather than a rigid and heavier design to resist 3 gravity launch loads. The deflated, non rigid material is like a membrane material capable of an inflated volume greater than the compressed volume, which forms a minimum material shape and is a spherical shape or a semi-spherical shape. The sphere is the maximum volume shape confined by minimum material.
The pressure envelope comprises a restraint band around a middle section with a compressed form of folds in the non-inflated structural foam. In the transported volume the structural foam is activated upon inflation.
The apparatus has a connector on each end called a flat end cap, which is disc shape structural device at each end connectable to the inflatable structure between the flat end caps. The volume contains a pressurized volume for humans or other functions. The flat end caps at each end are connectable to at least one device selected from the group consisting of another inflatable structure, a space station, an unpressurized structure, a salvaged device or hardware item, a fluid providing device, an energy-providing device, a celestial body other than earth, and space vehicle.
This connector end cap includes utility connectors and interfaces, a human hatch, a set of bolts/seals each of which joins a respective bolts/seals on a similar end cap unit and a means for attaching the inflatable volumes with bolts/seals from the inside. The inflated volume has tension cables connecting the two ends of the inflatable volume. The inside of inflatable volume has interior foldable architectural partitions attached to the tension cables to utilize the interior for human habitation, storage, scientific laboratory or other purposes.
The apparatus has an outer layer, which comprises a circular series of solar array plug into attach points and a series of solar array panels sized for the transport and capable of plugging a second solar array into a hole of the failed array leaving the old array in place. A portion of the remaining surface area used for revenue producing advertising enhancing the commercial utilization of the combination, and the combination is used in a space vacuum and microgravity.
The volume has end cap at each end of the inflatable volume having a bladder layer pressure tight bonding method and only the pressure boundary needs to be attached securely to the flat end cap. A hatch in the flat end cap capable of withstanding 14.7 psia on one side and vacuum on the other. A track around the exterior of the flat end cap for a traveling or repositionable robotic arm, and a set of robot data control tracks capable of transmitting control signals back and forth to manipulate the arm from the inside using a window and cameras for visual. The flat end cap also contains a set of utility connections through the non-hatch area from one volume to another, and an adapter capable of interfacing with ISS and Russian hatch hardware.
The inflatable volume is combined with similar units and used in a torus ring combination that has a series of modified volumes rotated to provide some portion of normal gravity for the inhabitants. The combination of similar units and salvaged space hardware forms a torus unit rotating and an axis formed with salvaged hardware such as external tanks of the space shuttle. The end of the axis is fitted with one or more exterior robotic arms capable of transferring the logistics cargo to and from the storage racks on the exterior to improve utilization of the combination, where the combination will be used in a space vacuum and microgravity.
The inflatable volume is sized for transport and insert into another in space and, used to salvage the external tank of the space shuttle, to salvage another suitable item, and to make a cave or other natural volume on another celestial suitable for habitation in a space vacuum.
A modified NASA TransHab habitation module volume is improved by adding a larger inflatable volume version transported to space in the compressed form in the aft cargo carrier (ACC), and an inflatable volume version pre-attached to the aft end of the external tank of the space shuttle. One or more compressed interior development packages are inserted into the salvaged external tank and inflated inside the existing salvaged external tank and enhance the utilization of the interior volume combination, where the combination will be used to develop volumes in a space vacuum and microgravity.
The volume of the NASA TransHab habitation module or other volume is also improved by adding a large space structures exterior frame in an erectable form for the attachment of robotically plugged in payloads.
The volume of the NASA TransHab habitation module or other volume is also improved by adding an unpressurized tunnel at both ends for connection between the inflatable volume and other items, and one or more exterior robotic arms capable of transferring the logistics cargo to and from the storage racks on the exterior to improve utilization of the combination, where the combination will be used in a space vacuum and microgravity.
The volumes are combined with other similar units and improved into torus units comprising a connector module in the compressed form in the aft cargo carrier (ACC), and a series of external tanks of the space shuttle are used as a mass heavy central axis, and a series of torus units are rotated to provide some percent of normal earth gravity, and specific space facility combinations are rotated in opposite directions to improve the stability of the rotating facility, and one or more compressed interior development packages for insertion into the salvaged external tank and inflated inside to enhance the utilization of the interior volume combination, and observation modules are used to provide space tourist activities on orbit, and where the combination will be used in a space vacuum and microgravity to develop an external tank in orbit.
Accordingly, several objects and advantages are the cost effective, reliable and safe space habitation using an inflatable integrated volume containing a series of inflatable layers protected by debris breakup barriers with spacing and exterior covering the volume for a successful habitation volume in space.
A primary object of the present invention is cost effective habitation volumes in space.
A primary advantage of the present invention is the elimination of most of the launch loads as a design consideration for an orbital pressure volume. This is accomplished using the transport of the compressed volume, inflation of the module volume in orbit, creation of a safe pressurized volume for humans and animals, protection of the habitation volume and expansion of the capability into other uses in a cost-effective manner.
Another object is to reduce the cost of habitation.
Another advantage of the present invention is the series layers used to create an interior, repair, pressure, containment and exterior layers with a semi-spherical shape contained by the disc shaped flat end cap that transfers the inflatable spherical structural loads into the flat end cap and provides a standard hatch in each flat end cap.
Another advantage of the present invention is the disc end cap with bolts capable of being installed and removed from the inside and from either end without damaging the interior environment flexibility of a washable wearable, architectural inside surface for human interaction permitting interior ISS rack mounted experiments and habitation.
Another advantage of the present invention is the pressure layer plus a repair layer with component A of a two part gel and a mesh layer with the part B of a two part foam generation reaction to move toward a puncture using the interior pressure to form a foam plug in the pressure bladder.
Another advantage of the present invention is open human access to repair the inside wall in the event of puncture.
Another advantage is the exterior solar cells used to generate electrical power.
Another advantage is the robotic arms capable of transfer of other mass including logistics items to and from the volume.
Another advantage of the present invention is the large-scale composite wound belt with electric solar cells on the exterior of the habitation volume.
Another advantage of the present invention is an integrated module wall system of separate layers for radiation, temperature, pressure, utilities and architectural systems providing an acceptable human environment within the pressure envelope.
Another advantage of the present invention is the exterior strut system compatible with the existing large space structures, providing utility systems support, and commercial opportunities for robotically receiving, transferring, attaching, detaching modules using a framework and rotational device on the end of the module.
Another advantage of the present invention is the attachment of inflatable structures to salvaged hardware and providing an acceptable method of developing pressurized volumes using inflatable volumes to create the interior pressure human environment within the salvaged hardware pressure envelope.
Another advantage of the present invention is the combination of stand alone inflatable structures with less strong interior inflatable structures that create habitation volumes inside existing salvaged hardware in orbit providing an acceptable method of developing pressurized volumes using several different types of inflatable structures.
Another advantage of the present invention is the creation of a large diameter cargo pod called the Aft Cargo Compartment (ACC) for attachment to a transportation vehicle tank. Part of the ACC remains with the tank aft section and part of the ACC is discarded after the ascent heating portion of the launch is over.
Another advantage of the present invention is the use of a large diameter cargo pod called the Aft Cargo Compartment (ACC) to transport a large diameter inflatable single module to orbit for use in space using a payload volume equal to the space shuttle.
Another advantage of the present invention is the use of a large diameter cargo pod called the Aft Cargo Compartment (ACC) to transport a large diameter inflatable single module already attached to the aft dome of an external tank of the space shuttle for use in space.
Another advantage of the present invention is the use of a large diameter cargo pod called the Aft Cargo Compartment (ACC) to transport smaller diameter inflatable, multiple modules to orbit.
Another advantage of the present invention is the compressed objects travel to orbit in a compressed state and are inserted into other volumes in orbit including the external tank of the space shuttle and other salvaged items for use in space.
Another advantage of the present invention is the objects are inflated and used to enhance the existing salvaged interior volumes already in orbit for many functions other than the original design function.
Another advantage of the present invention is the attachment of two or more inflatable volumes together at the flat end cap ends using bolts and connecting utility lines together.
Another advantage of the present invention is the use of two or more inflatable modules either in a straight line or a curved fashion with a flat end cap cable for support.
Another advantage of the present invention is the use of two or more connector modules to support a salvaged liquid hydrogen tank developed with interior inflatable units.
Another advantage of the present invention is the use of two or more connector modules to support one or more inflatable volumes developed in a curved manner and assembled into a section of a torus.
Another advantage of the present invention is the use of two or more assembled sections of a torus to complete the torus into a ring with bracing and human access spokes.
Another advantage of the present invention is two or more assembled sections of a torus rotated to produce some portion of one gravity to provide an enhanced human environment in space and lessen the effects of microgravity.
Another advantage of the present invention is two or more assembled torus units rotated in one direction to produce some portion of one gravity, while other portions of the complex are rotated in a different direction or allowed to remain at rest in order to fully utilize the gravity gradient aspects of the long axis structure and to counteract any other forces like coriolis effects and other forces that tend to unbalance the facility.
Another advantage of the present invention is two or more large diameter module and earth observation units are de-spun so as to permit space tourists to view earth and other objects from space.
Further objects and advantages of the invention will become apparent from the consideration of the drawings and ensuing description.
Other objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.


A method and article are provided for batch processing of a plurality of MEMS dice. The MEMS dice are secured in a holder having multiple stations adapted to secure a MEMS die. A process step is then performed on the plurality of MEMS dice while they are secured in the holder and may be performed simultaneously on all of the MEMS dice secured in the holder.

This application relates generally to processing microelectromechanical systems (MEMS), and more particularly to postprocessing of MEMS dice.
In recent years, increasing emphasis has been made on the development of techniques for producing microscopic systems that may be tailored to have specifically desired electrical and/or mechanical properties. Such systems are generically described as microelectromechanical systems (MEMS) and are desirable because they may be constructed with considerable versatility despite their very small size. Much of the development of MEMS processes has taken advantage of developments in the semiconductor processing industry, although there are significant differences.
One difference is that semiconductor processing is typically performed on the scale of wafers. In particular, semiconductor devices are typically formed by a series of deposition and etching steps on a silicon wafer having a diameter of 100 mm, 200 mm, or 300 mm. Many devices are thus formed simultaneously with a single wafer so that economies can be realized from the batch processing. By contrast, in MEMS processing, only a portion of the process is performed at the wafer scale. A MEMS device is formed through initially depositing structural and sacrificial layers on a wafer, both of which may be etched in specific ways as part of the process. Subsequently, the structures are diced using a 75- to 250-xcexcm-wide diamond or carbide saw blade and the MEMS devices are xe2x80x9creleasedxe2x80x9d through immersion in a substance corrosive to the sacrificial layers. Typically the sacrificial layers are formed of silicon oxide, which is dissolved through immersion of individual dice in hydrofluoric acid (HF). Each die, after immersion in hydrofluoric acid, is then rinsed, for example in a bath of deionized water. Because these processes are performed individually, MEMS processing does not realize the same economies of scale available in semiconductor processing. Additionally, since the release and rinses are typically performed by holding an individual die with tweezers, there is a significant risk of accidental damage to the delicate device.
This risk of accidental damage is further increased because MEMS devices are generally not passivated prior to the release and rinse steps in the formation process. This is in contrast to semiconductor devices, which are generally passivated to promote the formation of a resistant layer that provides some level of protection during handling. Since the MEMS devices are unpassivated, they are especially sensitive to surface contact that may damage the silicon layers used to form the device. In addition, for the same reasons, they are more susceptible to harmful effects from debris and contamination than are semiconductor devices.
After the release and rinsing steps, the MEMS dice are packaged. Because these post-dicing processing steps cannot take advantage of the large-scale integration used in the semiconductor-processing industry, their cost may be considerable. It is not unusual for the post-dicing processing of MEMS devices to account for as much as 80% of the overall cost of a component or system. There is accordingly a need in the art for a method and apparatus that provides for batch processing of MEMS dice and that limits contact with a human handler.
Thus, embodiments of the invention provide a method for processing a plurality of MEMS dice, such as may be prepared by dicing a processed wafer. The plurality of MEMS dice are secured in a holder. A process step is then performed on the plurality of MEMS dice while they are secured in the holder. Such a process step may be performed simultaneously on all of the MEMS dice secured in the holder. In one embodiment, the plurality of MEMS dice include unreleased MEMS dice.
A variety of processing steps may be performed. For example, the holder may be immersed in one or more liquids, thereby immersing all of the MEMS dice secured by the holder in the liquid. One liquid may be hydrofluoric acid, which is corrosive to silicon oxide layers commonly used as sacrificial material in fabricating MEMS devices, so that the immersion in hydrofluoric acid acts to release the MEMS devices. The holder may thus be made of a material resistant to corrosion by hydrofluoric acid, such as the fluoropolymer resin teflon(copyright). Another liquid may be used to rinse hydrofluoric acid after release, such as deionized water. Another processing step that may be performed while the MEMS dice are secured in the holder is critical point drying to prevent damage to the delicate structures after rinsing. Other process steps that may be performed include testing the plurality of MEMS dice, as well as some steps involved in packaging the MEMS dice.
In one embodiment, the holder comprises a structural body having a plurality of stations. Each station is adapted to secure a MEMS die. In one embodiment, this is achieved with a recess in the structural body shaped to secure an edge of the MEMS die together with a flexible retaining arm adapted to retain the MEMS die within the recess. The flexible retaining arm may include a notch shaped for engagement with a tool for flexing the flexible retaining arm. Each station may also include an access to an underside of the MEMS die, as may be provided with a hole or slot in the structural body. In one embodiment, the structural body is circularly symmetric and the plurality of stations are configured symmetrically about a central axis of the structural body. The structural body may be formed as a single continuous structure.


In at least one embodiment of the invention, an OLED device is disclosed in which the surface of one or more layers of the OLED are conditioned with metal nano-particles such that they are disposed along the interface between adjacent layers.

An organic light emitting diode ("OLED") display or device is typically comprised of: a transparent anode on a substrate; a hole injection/transporting layer; a light emitting layer ("emissive layer"); and a cathode, where one or more of these layers are organic in nature. When a forward bias is applied, holes are injected from the anode into the hole injection/transporting, and the electrons are injected from the cathode into the emissive layer. Both carriers are then transported towards the opposite electrode and allowed to recombine with each other. The location of this recombination is called the recombination zone and due to the recombination, the emissive layer produces visible light.
There is some suggestion in a published patent application that incorporation of metal nano-particles within a polymer-based light emitting layer suppresses photo-oxidation and enhances luminous stability [Publication number US 2004/0217696 A1]. Yet another patent application suggests that acceleration of the radiative processes is achieved by incorporation of metal nano-particles within the hole transporting layer or within the light emitting layer of phosphorescence based OLEDs [Publication number US 2005/0035346]. The acceleration of the radiative processes is achieved by the interaction of the light emitting species with surface plasmon resonances in the vicinity of metal nano-particles. Non-radiative Förster-type processes are efficiently suppressed by encasing each nano-particle in organic capping molecules. In all of the above approaches, metal nano-particles were blended in one or more layers of the OLEDs.
However direct incorporation of metal nano-particles into the active region or other layers within the OLED can cause additional negative effects. For example, it has been demonstrated that incorporation of a gold nano-particle even at low volume fraction of 3×10−5 within a light emitting polymer layer introduces strong hole blocking effects and a large increase in operating voltage [Publication number US 2004/0217696 A1 and Jong Hyeok Park et al., Chem. Mater. 2004, 16, 688]. Furthermore, incorporation of metal nano-particles in both fluorescence-based and phosphorescence-based OLEDs will likely quench emission and strongly deteriorate device performance. Encasing nano-particles in organic capping molecules is suggested to achieve an optimum balance between quenching and acceleration of the radiative processes of the triplets states [Publication number US 2005/0035346]. However achieving such a condition is not straightforward and capping of the metal nano-particles is not a well known procedure.

Interface conditioning to improve efficiency and lifetime of organic electroluminescence devices