A process for the production of liquid nitrogen and oxygen from an air separation unit comprising:
- feeding separate oxygen and high and low pressure nitrogen gas streams to a liquifier device as a pure gas;
- passing the oxygen gas sequentially through an oxygen cooler, boiler, condenser, and an oxygen flash pot to provide a liquid oxygen stream,
- feeding the liquid oxygen stream to an oxygen filter house, measuring the liquid oxygen purity, and then moving purified the liquid oxygen to storage, whereby the oxygen is drawn to the oxygen filter house by a change of state from liquid to gas,
- feeding a low pressure nitrogen gas stream from the flash pots sequentially through the condenser, boiler and oxygen cooler, and joining the low pressure stream from the flash pots with the low pressure nitrogen stream from the air separation plant,
- feeding the joined low pressure nitrogen stream to a plurality of turbine boosters and aftercoolers arranged in series to increase the pressure and cool the nitrogen stream, and providing a major nitrogen flow,
- feeding the major flow in branch lines to the oxygen cooler, preheater, and a bypass, and then rejoining the major flow,
- feeding the rejoined major flow to the boiler to give pressure to the turbines, then from the boiler to the condenser as a gas, then from the condenser to an added cooler as a two-phase liquid to lower the temperature, and then to a pump flash pot cooled by a nitrogen bath at low pressure, and exiting the pump flash pot as a single phase usable liquid nitrogen,
- feeding a portion of usable liquid nitrogen off of the pump flash pot to a liquid nitrogen pump system,
- upon exit from the pump system, feeding a first regulated flow of usable liquid nitrogen to the boiler and boiling to a vapor point, whereby the pressure vapor point of the vapor is held back by guide vanes in a plurality of turbine expanders, then upon exit from the boiler feeding the vaporized nitrogen flow to a second preheater, and then to run the plurality of turbine expanders arranged in parallel to yield a lower pressure nitrogen gas flow, which exiting gas is a close to liquid temperature low pressure gas and almost at its boiling point, and will remove the latent heat of vaporization from the higher pressure nitrogen stream and lower pressure nitrogen stream,
- feeding the lower pressure nitrogen gas flow from the turbine expanders into a turbine exhaust phase separator regulated to produce no more than three percent liquid off of the phase separator, to hold a liquid level controlled by the exit temperature of the turbines and draining auto control valves, which temperature depends on boiler pressure and preheater feed temperature, and then to the condenser to add refrigeration to the condenser,
- feeding the gas stream off of the phase separator to the condenser, then to the boiler, then to the oxygen cooler, making more liquid, and upon exiting the oxygen cooler to a line containing a pressure control valve joining the higher pressure nitrogen stream inlet, which is used to heat the preheater and bypass the preheater and connects to the last turbine booster, joining to make the major flow,
- feeding the liquid off of the phase separator to the oxygen flash pot, the nitrogen production flash pot, and pump flash pot as regulated by separate auto level control valves, and any remaining liquid off of the phase separator to a control valve to flash the liquid and then is fed to a low pressure line to the nitrogen production flash pot exhaust gas,
- feeding a low pressure flow to the air separation plant to add refrigeration to the low pressure column and argon system, and
- feeding a nitrogen flow from the pump flash pot, to the production flash pot, and then to storage.