Abstract: The invention provides a means of producing at least one of high purity nitrogen and low to medium purity oxygen (up to about 97% purity) at high recovery (above 96% for oxygen). The LP column efficiency is improved to reduce the energy requirement, without offsetting reduction in LN.sub.2 reflux availability. Referring to FIG. 1, this is done by providing intermediate height reboil to LP column 3 by a latent heat exchanger 10 in which HP rectifier 5 overhead N.sub.2 vapor which has been partially expanded in expander 9 is condensed and kettle liquid is evaporated. The condensed N.sub.2 is then used to reflux column 3 after depressurization by valve 13.

Abstract: An absorbent solution for absorbing and desorbing useful quantities of ammonia vapor is disclosed. The absorbent has much lower vapor pressure than water, and has a wider solubility field and higher crystallization limit than any previously known non-volatile absorbent for ammonia. It is useful in absorption cycle processes and apparatus requiring high lifts from temperatures well below freezing, e.g., in thermally actuated industrial refrigeration systems or cold-climate absorption heat pumps for space heating. The new absorbent is also useful with other ammonia-type vapor, e.g., monomethylamine.

Abstract: Method and apparatus are disclosed for obtaining more refrigeration from a cold pressurized stream of nitrogen being expanded to discharge pressure, particularly in an air separation plant. Referring to FIG. 1, cold expansion in 1 is followed or preceded by warm compression in 2 of at least part of the same stream being expanded. The net result of reduced N.sub.2 to expansion is more LN.sub.2 reflux available to increase O.sub.2 recovery, without import of additional power or substantial increase in capital cost.

Abstract: The low energy triple distillation pressure process for producing high purity industrial oxygen is improved in several ways, including higher O.sub.2 pressure, higher recovery of both oxygen and crude argon, and lower N.sub.2 content in the argon. This is done with the traditional triple pressure column arrangement (columns 22, 24, and 27 of FIG. 1) preferably by totally condensing liquid air in reboiler 21 and then splitting it with valves 42 and 43; by providing all LN.sub.2 reflux duty from reboiler 26; by evaporating product oxygen in 23 with partially condensing air; and by intermediate refluxing column 27 with condenser 28 which provides a separate vapor stream to column 22.

Abstract: The invention provides an improved means of producing the refrigeration required for any fractional distillation air separation process. The improved refrigeration technique causes the distillation columns to operate more efficiently, and thereby permits increased recovery and/or purity of product at lower energy input. Referring to FIG. 3, refrigeration air is partially expanded in expander 313, then condensed by exchanging latent heat with depressurized kettle liquid in condenser 314, and the resulting liquid air is split and used to reflux both columns 307 and 305 via pump 316 and valve 315 respectively.

Abstract: Method and apparatus for achieving high yields of high purity N.sub.2 and optional coproduct O.sub.2 at lower energy and capital cost than heretofore possible are disclosed. Referring to FIG. 1, in a dual pressure configuration comprised of a rectifier (105) and a column (102), warm companded air from a compressor (118) provides bottom reboil at the reboiler (103), and the liquid air is split to reflux both columns. The refrigeration expander (112), driven by expansion of waste O.sub.2, provides the power for the compressor (112). Also kettle liquid is distilled into two vapor streams by a contact zone (107) before feeding to the column (102).

Abstract: In a cryogenic air distillation process for producing medium-to-high purity oxygen plus optional coproduct argon, a new process sequence results in more efficient distillations at reduced supply pressure and full O.sub.2 recovery. Reforming to FIG. 2, a minor stream of supply air is additionally compressed by compander 204, cooled, and then reboils column 201 by total condensation in reboiler 205. The liquid air is split into two intermediate reflux streams, one for each column 201 and 202, valves 206 and 207, thereby improving the efficiency of both columns. The air condensing in 205 is somewhat hotter than that supplied to 202, due to its higher pressure, which permits a reduction in the main supply pressure.

Abstract: In a triple pressure cryogenic air distillation apparatus for producing of high purity oxygen and crude argon at low energy requirement, a novel method of avoiding proximity to argon freezeup conditions is disclosed. Referring to FIG. 3, the temperature at the overhead of the argon recovery column 309 is kept above about -305.degree. F. by increasing the pressure of N.sub.2 rejection column 304 to about 3 psi above normal discharge pressure. The exhaust N.sub.2 is subsequently depressurized in one or more work-expanders 324 and 330 thereby producing process refrigeration.

Abstract: A temperature swing absorption separation of oxygen from air is performed with an oxygen acceptor of alkali metal nitrate and nitrite.

Abstract: Refrigeration is produced by an intermittent absorption cycle. The cycle is driven by solar radiation, and utilizes NH.sub.3 as refrigerant and a liquid, preferably H.sub.2 O, as absorbent. Referring to FIG. 1, solar radiation is collected during the daytime or in generation mode by a Compound Parabolic Collector 2, which reflects the light onto a cylindrical target vessel 1 containing the absorption working pair. Ammonia is boiled out of the target, the vapor travels to condenser 5 where it is cooled to liquid, and the liquid is stored in receiver vessel 6. During the nighttime, or absorption mode, liquid is released from the receiver vessel into an evaporator coil 8 located in a cold box 9 wherein it vaporizes, thus removing heat from the contents of the cold box. The vaporized ammonia then is absorbed back into the absorbent, in the target vessel.

Abstract: The inefficiency of the nitrogen stripping section of a high purity oxygen-producing air distillation plant is reduced. This allows increased recovery of byproduct argon and in some cases increased recovery of refrigeration work also. The improvement is obtained by evaporating kettle liquid with condensing argon rectifier vapor in two sequential stages, to yield vapor streams respectively having more and less O.sub.2 content than the kettle liquid, and separately feeding them to the N.sub.2 removal column. The improvement is applicable to both dual and triple pressure processes. Referring to FIG. 1, kettle liquid is supplied via valve 11 to the top of contactor 18, and overhead reflux condenser 13 of argon rectifier 14 reboils the bottom of contactor 18. Vapor streams of differing O.sub.2 composition are withdrawn from above and below 18.

Abstract: The argon recovery of an air distillation plant is increased by increasing the argon rectifier reboil and simultaneously decreasing the nitrogen stripping reboil. No additional power and minimal added equipment is required. Referring to FIG. 1, two separate argon rectifier reflux condensers (7 and 9) are provided, either for a single argon rectifier or optionally as shown for two separate argon rectifiers (12 and 13). Kettle liquid is partially evaporated in reflux condenser 7 and the liquid residue is further evaporated in reflux condenser 9 to a vapor of differing (higher) O.sub.2 content. The two vapor stream are separately fed to different heights of column 2, separated by countercurrent contact zone 11.

Abstract: Process and apparatus are disclosed for increasing argon recovery in conjunction with cryogenic distillation of air to high purity oxygen. The increased argon recovery is obtained by incorporating one or more latent heat exchangers in the flowsheet at strategic disclosed locations and between specific fluids. The invention is particularly advantageous in conjunction with LOXBOIL flowsheets, which otherwise lose O.sub.2 recovery when argon recovery is increased.

Abstract: A liquid mixture of alkali metal nitrates and excluding nitrite anions is disclosed which is useful for reveribly absorbing and desorbing useful quantities of water vapor. The mixture in noncorrosive to mild steel and thermally stable up to temperatures at least as high as 260.degree. C., and finds application in absorption cycles and in air drying cycles.

Abstract: A process for the integration of a chemical absorption separation of oxygen and nitrogen from air with a combustion process is set forth wherein excess temperature availability from the combustion process is more effectively utilized to desorb oxygen product from the absorbent and then the sensible heat and absorption reaction heat is further utilized to produce a high temperature process stream. The oxygen may be utilized to enrich the combustion process wherein the high temperature heat for desorption is conducted in a heat exchange preferably performed with a pressure differential of less than 10 atmospheres which provides considerable flexibility in the heat exchange.

Abstract: A water vapor absorbing composition containing CsOH is disclosed which is useful in absorption cycle heat pumping processes and apparatus. When combined with at least one of KOH and NaOH, the absorbent makes possible exceptionally high lifts of the temperature of heat which is initially at low ambient temperatures. Acceptably low corrosion rates are achieved with standard materials of construction using ordinary corrosion inhibitors.

Abstract: This invention makes possible a substantial improvement in the distillation column efficiencies of a cryogenic air separation process while still retaining high reboil rates through the argon stripping section of the low pressure column. Those advantages result in a lower energy requirement for separating air while still yielding medium to high oxygen purity. In a triple pressure column arrangement, the medium pressure column efficiency is increased by reboiling it at two or more locations by latent heat exchange with both the high pressure and low pressure columns. The LP column vapor which reboils the MP column is taken from above at least part of the argon stripper, to maintain a high reboil rate through the stripper.

Abstract: A process and apparatus are disclosed for producing pressurized oxygen at up to about 10 ATA directly in a cryogenic distillation process without need of an oxygen compressor. The process involves a split supply pressure air supply wherein the elevated pressure fraction gasifies pumped liquid oxygen. An essential aspect of the invention is that this gasification takes place in an elevated pressure rectifier; thus the elevated pressure fraction of air is converted into partially separated liquids as opposed to the more wasteful conversion to liquid air which occurs in the conventional process. The improvement may be adapted to any cryogenic distillation configuration and be used to produce any purity of product oxygen. A particularly high purity (99.5%) and low energy example is presented.

Abstract: The invention provides a means of producing high purity nitrogen at high recovery with lower energy requirement than has been possible heretofore. This is done with an elevated pressure dual pressure distillation column arrangement wherein the low pressure column (at about 4 ATA pressure) (component 102 in FIG. 1) is reboiled by partially condensing supply air in 103 and is refluxed both by direct injection of LN.sub.2 from the HP rectifier 105 plus latent heat exchange with depressurized LP column bottom liquid in 114, and the HP rectifier is refluxed by latent heat exchange with either LP column intermediate liquid in 106 and/or depressurized kettle liquid.

Abstract: The invention provides a means of producing high purity oxygen at high recovery plus also byproduct argon while using a low air supply pressure. This is done with a triple pressure distillation arrangement (columns 101, 102, and 103 of FIG. 1) having argon stripping sections at the bottom of both the MP (102) and LP (103) columns, a liquid sidestream withdrawal (117) from the MP column, forming feed for the LP column, an intermediate reflux (118) for the LP column which reboils the MP column, and an argon removal capability.