摘要:
A moderate pressure nitrogen and argon producing cryogenic air separation unit is provided that includes a three distillation column system and turbine air stream bypass arrangement or circuit. The turbine air stream bypass arrangement or circuit is configured to improve argon and nitrogen recoveries in select operating modes by optionally diverting a portion of the turbine air stream to a nitrogen waste stream circuit drawn from the lower pressure column of the cryogenic air separation unit such that the diverted portion of the turbine air stream bypasses the distillation column system.
摘要:
A method and device to produce oxygen by the low-temperature separation of air at variable energy consumption. A distillation column system comprises a high-pressure column, a low-pressure column and a main condenser, a secondary condenser and a supplementary condenser. Gaseous nitrogen from the high-pressure column is liquefied in the main condenser in indirect heat exchange with an intermediate liquid from the low-pressure column. A first liquid oxygen stream from the bottom of the low-pressure column is evaporated in the secondary condenser in indirect heat exchange with feed air to obtain a gaseous oxygen product. The supplementary condenser serves as a bottom heating device for the low-pressure column and is heated by means of a first nitrogen stream from the distillation column system, which nitrogen stream was compressed previously in a cold compressor.
摘要:
A method for separating air is provided, in which a flow of oxygen-rich liquid is sent to a top of a pure oxygen column, having a pure oxygen reboiler, in which said flow is purified in order to form a vessel liquid containing at least 98 mol % of oxygen and the vessel liquid is drawn off as a product. A supercharged airflow at a second pressure is sent to the pure oxygen reboiler and to a liquid oxygen vaporizer; a nitrogen-rich gas is drawn from the top of the medium-pressure column and sent to an intermediate reboiler of the low-pressure column and the condensed gas is sent to the top of the medium-pressure column; and a nitrogen-rich gas or air is sent to a vessel reboiler of the low-pressure column and the liquid that condenses therein is sent to the medium-pressure column.
摘要:
A process and apparatus for highly efficient production of industrial gases by the cryogenic distillation of air, wherein a feed stream of compressed air, is supercharged to high pressure, cooled, and mixed with various recycle streams of supercharged air, to regulate the expander turbine operating temperature. The need for pre-cooling equipment downstream of the supercharger, which is widely employed in industry to manage the temperature of the incoming compressed air stream, is eliminated.
摘要:
A system is set forth to increase the capacity of an LNG-based liquefier in a cryogenic air separation unit wherein, in a low production mode, the nitrogen that is fed to the LNG-based liquefier consists only of at least a portion of the high pressure nitrogen from the distillation column system while in a high production mode, a supplemental compressor is used to boost the pressure of at least a portion of the low pressure nitrogen from the distillation column system to create additional (or replacement) feed to the LNG-based liquefier. A key to the present invention is the supplemental compressor and the associated heat exchange equipment is separate and distinct from the LNG-based liquefier. This allows its purchase to be delayed until a capacity increase is actually needed and thus avoid building an oversized liquefier based on a speculative increase in liquid product demand.
摘要:
A process and apparatus for highly efficient production of industrial gases by the cryogenic distillation of air, wherein a feed stream of compressed air, is supercharged to high pressure, cooled, and mixed with various recycle streams of supercharged air, to regulate the expander turbine operating temperature. The need for pre-cooling equipment downstream of the supercharger, which is widely employed in industry to manage the temperature of the incoming compressed air stream, is eliminated.
摘要:
An air separation plant producing pressurized gaseous oxygen includes at least one column having a bottom reboiler. The column is fed with a stream of air. The bottom reboiler is warmed by a nitrogen-enriched gas compressed in a cold compressor and pumped liquid oxygen is withdrawn from the bottom of the column, pumped and vaporized. The refrigeration for the process is produced by air expansion in a turbine.
摘要:
A method and apparatus of separating air to produce an oxygen product. In accordance with the method and apparatus the air is rectified within a double column arrangement. The lower pressure column has lower and intermediate reboilers. Nitrogen from the higher pressure column is compressed and sent to the lower reboiler and oxygen tower overhead from the higher pressure column is fed to the intermediate reboiler. The resultant liquid is used to reflux both columns. The advantages in the arrangement set forth above is that the higher pressure column may be made to operate at a lower pressure to conserve energy.
摘要:
In a process for the cryogenic distillation of air in a distillation column system that contains at least one distillation column wherein the boil-up at the bottom of the distillation column producing the oxygen product is provided by condensing a stream whose nitrogen concentration is equal to or greater than that in the feed air stream, which comprises the steps of: (a) generating work energy which is in excess of the overall refrigeration demand of the distillation column system by at least one of the following three methods: (1) work expanding a first process stream with nitrogen content equal to or greater than that in the feed air and then condensing at least a portion of the expanded stream by latent heat exchange with at least one of the two liquids: (i) a liquid at an intermediate height in the distillation column producing oxygen product and (ii) one of the liquid feeds to this distillation column having an oxygen concentration equal to or preferably greater than the concentration of oxygen in the feed air; (2) condensing at least a second process stream with nitrogen content equal to or greater than that in the feed air by latent heat exchange with at least a portion of an oxygen-enriched liquid stream which has oxygen concentration equal to or preferably greater than the concentration of oxygen in the feed air and which is also at a pressure greater than the pressure of the distillation column producing oxygen product, and after vaporization of at least a portion of oxygen-enriched liquid into a vapor fraction due to latent heat exchange, work expanding at least a portion of the resulting vapor stream; and (3) work expanding a fraction of the feed air; (b) using the work which is generated in excess of the refrigeration need of the distillation column system to cold compress a process stream at a temperature lower than the ambient temperature.
摘要:
The present invention relates an improvement to a cryogenic process for the separation of air which produces at least a nitrogen product and is carried out in a distillation column system having at least one distillation column from which the nitrogen product is produced. The distillation column of the distillation column system must comprise a rectifying section. In the process of the present invention, air is compressed, freed of impurities which will freeze out at cryogenic temperatures, cooled to near its dew point and fractionated in the distillation column system to produce the nitrogen product.The improvement is the operation of the distillation column such that the ratio of downward liquid to upward vapor flow rate (L/V) is no less than 0.65, preferably greater than 0.75, but less than 1.0 in the rectifying section of a distillation column from which the nitrogen product is produced. The flowrates are in moles per unit time.