摘要:
The present invention relates to a process producing large quantities of liquid product via the cryogenic distillation of air wherein at least a portion of the refrigeration needs of the process is provided by expansion of the feed air. In particular, the present invention is an improved method to meet the liquid nitrogen requirements of the process and comprises elevating the discharge pressure of the nitrogen recycle compressor.
摘要:
A fluid mixture is separated by distillation in a two column system in which a portion of the feed is prefractionated in a first column having at least one separation stage above the feed and the prefractionator bottoms provides feed to a second column operating at a lower pressure. Cooling for condensing the overhead vapor of the first column is provided by heat exchange with flashed prefractionator bottoms or with an intermediate fluid in the second column. Another portion of the feed is flashed and introduced into the second column. The two-column system is readily combined with a high pressure column in a three-column distillation system for separating air which is particularly useful for integration with a gasification combined cycle combustion turbine system. Optionally, three nitrogen products can be produced at three different pressures.
摘要:
The present invention is an improvement to a process for the cryogenic distillation of air to produce both nitrogen and oxygen products carried out in a single distillation column system wherein a feed air stream is distilled thereby producing a nitrogen overhead and a liquid oxygen bottoms. The improvement is characterized in that: (a) operating the single distillation column at a pressure between 70 and 300 psia [480 and 2,070 kPa.sub.(absolute) ]; (b) withdrawing a portion of the liquid oxygen bottoms having an oxygen concentration greater than 80% oxygen and preferably between 85% and 97% oxygen from the bottom of the single distillation column and reducing the pressure of and vaporizing the withdrawn liquid oxygen by heat exchange against a condensing nitrogen stream removed from a top section of the single distillation column; (c) feeding the condensed, nitrogen stream to a top section of the single distillation column as reflux; and (d) recovering the vaporized oxygen as at least a substantial portion of the oxygen product. The improvement can be further characterized by providing boilup by boiling at least another portion of the liquid oxygen bottoms by heat exchange against a condensing vapor stream, wherein the vapor stream to be condensed in an air stream at a higher pressure than the feed air stream or a recycle nitrogen stream at a pressure greater than the operating pressure of the single distillation column, or by recycling a portion of the oxygen product at a pressure of at least the operating pressure of the single distillation column to the bottom of the distillation column and/or by providing intermediate boilup to the stripping section of the single distillation column system by vaporizing a portion of descending column liquid by heat exchange against another condensing vapor stream, wherein the other vapor stream to be condensed is either an air stream at a higher pressure than the feed air stream or a recycle nitrogen stream at a pressure greater than the operating pressure of the single distillation column.
摘要:
An efficient multieffect distillation process separates multicomponent mixtures containing three or more components into product streams each enriched in one of the components. The distillation process consists of at least two distillation columns that are thermally linked. A mixture stream that can be the given feed or a stream recovered from another distillation column and containing three or more components is fed to one of the thermally linked distillation columns and at least two submixture streams are produced from this distillation column and transferred to other distillation columns for further distillation. At least one of the submixture streams is transferred to the other thermally linked distillation column. One submixture stream is lean in the least volatile component of the mixture feed and the other submixture stream is lean in the most volatile component of the mixture feed.
摘要:
A fluid mixture is separated by distillation in a two column system in which the feed is prefractionated in a first column having at least one separation stage above the feed and the prefractionator bottoms provides feed to a second column operating at a lower pressure. Cooling for condensing the overhead vapor of the first column is provided by heat exchange with flashed prefractionator bottoms or with an intermediate fluid in the second column. The two-column system is readily combined with a high pressure column in a three-column distillation system for separating air which is particularly useful for integration with a gasification combined cycle combustion turbine system. Optionally, three nitrogen products can be produced at three different pressures.
摘要:
The present invention relates to an improvement to a cryogenic process for the separation of air into its constituent components. In the process, a distillation column system having at least two distillation columns, a high pressure distillation column and a low pressure column is used; these two distillation columns are in thermal communication with each other. The low pressure column of the distillation column system operates at a pressure between 9 to 75 psig and a nitrogen product is produced from the top section thereof. At least 50% of the air to the distillation column system is removed as this nitrogen product, which has a nitrogen concentration of at least 95% and is at a pressure of at least 9 psig.The improvement to the process is a series of steps which allows for the production of liquid products from the cryogenic process in an efficient manner. These steps are primarily the partial warming of the nitrogen product, its subsequent isentropic expansion and use of the inherent refrigeration of the expanded nitrogen. These steps can be carried out in three ways.
摘要:
The present invention relates to an improved cryogenic process for the separation of air to produce an oxygen product and a nitrogen product. The present invention employs a distillation column system with three distillation columns, a low pressure column, a medium pressure column and a high pressure column. The improved three column distillation system process comprises: (a) producing an oxygen product with a product purity of less than 98% purity oxygen and producing no argon product; (b) producing a gaseous nitrogen product which represents greater than 35% of the feed air and which is removed from the medium and/or high pressure columns; (c) recovering a major portion of the oxygen product from the low pressure column; and (d) condensing at least a portion of the high pressure nitrogen overhead from the high pressure column by heat exchange against a liquid stream in the medium pressure column and utilizing at least a portion of the condensed portion to provide reflux to the high pressure column.
摘要:
The present invention is a liquid nitrogen reflux means improvement capable of allowing the operation of conventional dual and triple reboiler air separation cycles at elevated pressures. The improvement comprises: (a) further compressing and cooling another portion of the compressed, essentially impurities free, feed air, thereby producing a further compressed second portion; (b) removing and increasing the pressure of a portion of the liquid oxygen bottoms of the second column and heat exchanging the increased pressure liquid oxygen bottoms against at least a fraction of the further compressed second portion of step (a) so that upon heat exchange the fraction of the further compressed second portion of step (a) is at least partially condensed and the increased pressure liquid oxygen bottoms portion is at least partially vaporized; (c) feeding the at least partially condensed fraction of step (b) to at least one of the two distillation columns; (d) warming the at least partially vaporized oxygen of step (b) to recover refrigeration; (e) compressing a portion of the gaseous nitrogen product and cooling it to a temperature near its condensation temperature by heat exchange against warming process streams; and (f) condensing the cooled, compressed gaseous nitrogen product portion of step (e) and feeding the condensed nitrogen portion as reflux to at least one of the distillation columns.
摘要:
A method to reduce the cycle time in a pressure swing adsorption process by reducing the required pressure equalization time in a cycle, thereby reducing the overall cycle time and increasing product recovery per unit of adsorbent used. This reduces the amount of adsorbent required in the beds for a given feed rate while continuing to provide product at an acceptable product purity, and has the desirable effect of reducing the capital cost of the process equipment required for a given volumetric production rate.
摘要:
The present invention relates to a cryogenic process and apparatus for production of an oxygen product from air, characterized in that a multiple passage plate-fin heat exchanger having at least two sets of passages is used to effectuate the rectifying and stripping functions, wherein one set of passages comprises a continuous-contact rectification dephlegmator which rectifies the separator vapor and produces the enriched-nitrogen rectifier overhead and the crude liquid oxygen bottoms; wherein a second set of passages comprises a continuous-contact stripping dephlegmator which strips the oxygen-enriched liquid to produce the nitrogen-enriched stripper overhead and the oxygen product; wherein reflux of the rectification device and boilup for the stripping device is provided, at least in part, by indirect heat exchange between and along said two sets of passages, thereby producing a thermal link between the rectification dephlegmator and the stripping dephlegmator.