摘要:
The present invention is a cryogenic process for the production of nitrogen by distilling air in a double column distillation system comprising a high pressure column and a low pressure column. The critical step of the invention is the condensation of two nitrogen streams at different pressures in two reboiler/condensers located in the stripping section of the low pressure column to provide column reboil. The lower pressure of the two nitrogen streams is condensed in the upper of the two reboiler/condensers; the higher pressure nitrogen stream in the lower of the two reboiler/condensers.
摘要:
A process is set forth for the cryogenic distillation of an air feed to produce an ultra-high purity oxygen product. A first oxygen-containing but heavy contaminants-lean (free) stream is removed from the main distillation column system and subsequently stripped in an auxiliary distillation column. A second oxygen-containing but light contaminants-lean (free) gaseous stream is also removed from the main distillation column system and subsequently fed to the bottom section of the auxiliary distillation column in order to provide heat duty/reboil to the bottom of the auxiliary distillation column. The ultra-high purity oxygen product (ie total contaminant concentration less than 10.0 vppm, preferably less than 1.0 vppm) is withdrawn from an intermediate section of the auxiliary distillation column.
摘要:
This invention relates to a cryogenic process for the separation of air utilizing an integrated multi-column distillation system wherein a nitrogen rich, oxygen rich and argon rich product are generated. In the cryogenic distillation separation of air, air is initially compressed, pretreated and cooled for separation into its components. Moderate pressure, e.g., 25-80 psia nitrogen is generated with enhanced nitrogen product purity and greater recovery of both nitrogen and argon by effecting a high boil-up rate in the bottom of the lower pressure column, thereby creating a reduced liquid flow/vapor flow ratio (L/V) and utilizing a higher than customary nitrogen reflux to the top of the lower pressure column, where the concentration of oxygen in nitrogen is less than about 10 ppm by volume or the nitrogen purity is at least about 99.5% by volume. Refrigeration to drive the system is obtained by recovering the energy from the waste nitrogen stream and oxygen vapor from the lower pressure column. A second method for obtaining refrigeration is to withdraw oxygen as a bottoms liquid from the lower pressure column, expanding that liquid to a lower pressure and using it to condense the nitrogen vapor generated in a higher pressure column which has been expanded in a turbo-expander to provide the refrigeration.
摘要:
The present invention is an improvement to a method of producing crude argon directly from the cold box of a cryogenic air separation unit. The improvement is the production of crude argon containing greatly decreased concentrations of oxygen, i.e.
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:
This invention relates to an improvement in a process for the separation of a multi-component stream comprising component A, B and C with A being the most volatile and C the least volatile. A multi-component feed is introduced to a multicolumn distillation system comprising a first or main distillation column and a side column wherein at least a light component A is separated from a heavier component C in the main distillation column, the lighter component A being removed as an overhead fraction and the heavier component C being removed as a bottoms fraction. The improvement for enhanced recovery of component B in the side column comprises withdrawing a liquid fraction from the main distillation column at a point intermediate the overhead and feed and introducing that liquid fraction to an upper portion of the side column. Lighter components are withdrawn as an overhead from the side column and returned to an optimal location in the distillation system, typically the main distillation column. A vapor fraction is also withdrawn from the main distillation column at a point intermediate the bottoms and feed and vapor fraction is introduced to a lower portion of the side column. A liquid fraction is withdrawn as bottoms and returned to the main distillation column. Thermal integration in the side column is effected by removing a portion of the liquid typically from the stripping section of the side column and vaporizing this fraction against a vapor fraction obtained from the main distillation column.
摘要:
A process and system for controlling a cryogenic air separation unit during rapid changes in production. During operation of an air separation unit, demands for oxygen will vary and the pressure of the feed air will fluctuate. The changes in oxygen demand and feed air pressure translate into a ramping, either up or down, of the distillation system pressure in the air separation unit. Because the product streams have tight purity requirements, the ramping system pressure (which could adversely affect product purity) is compensated for. This compensation is by way of a net transfer of refrigeration, in the form of liquid nitrogen, into and out of the distillation system. This transfer of refrigeration is implemented using a storage vessel of liquid nitrogen connected to the reflux path of the distillation system. Liquid nitrogen via the reflux path is removed and stored or added to the distillation system to decrease or increase the refrigeration, respectively.
摘要:
The present invention relates to an improvement for the production of ultra-high purity oxygen from cryogenic air separation processes which produce nitrogen and/or commercial purity oxygen products. In particular, the improvement comprises removing or producing an oxygen-containing but heavy contaminant-lean (free, stream from one of the distillation columns of a single or multiple column cryogenic air separation facility and further stripping the removed or produced oxygen-containing stream in a fractionator to produce ultra-high purity oxygen (i.e., contaminant concentration
摘要:
A process is set forth for introducing a multicomponent liquid feed stream at pressure P.sub.2 into a distillation column operating at lower pressure P.sub.1. The process comprises removing a split stream from the feed stream, reducing its pressure and using the resulting stream to subcool the feed stream. After being subcooled, the feed stream is also reduced in pressure and both streams are fed to different stages of the distillation column. An important embodiment of the present invention is within the standard double column air separation cycle where the multicomponent liquid stream is the crude liquid oxygen stream from the bottom of the high pressure column which must be reduced in pressure prior to its introduction into the low pressure column.
摘要:
A process is set forth for the cryogenic distillation of an air feed to produce a low to medium purity oxygen product using a single distillation column system. The air feed is partially condensed into a crude liquid oxygen stream and a remaining nitrogen-enriched vapor stream by boiling the liquid phase at the bottom of the distillation column. The pressure of the crude liquid oxygen stream is reduced and the nitrogen-enriched vapor stream is subsequently condensed against it to provide reflux to the top of the distillation column. The low to medium purity oxygen product (oxygen concentration between 65% and 99%) is withdrawn from the bottom of the distillation column as liquid, vapor or a combination of both.