Patent ID: 8100671

Claim:
A process for the repressurization of an off gas at a suction pressure from 68.94 kPa-g (10 psig) to 344.7 kPa-g (50 psig) to a discharge pressure of repressurized gas at the exit of a diffuser of at least one downstream supersonic ejector from 2068.2 kPa-g (300 psig) to 3447 kPa-g (500 psig) comprising: providing a first supersonic gas ejector and at least one downstream supersonic gas ejector connected in tandem, every ejector having a nozzle and a diffuser; providing said first supersonic ejector having a ratio of the cross section of the area of the nozzle exit to the nozzle throat from 2.9 to 3.2 and a ratio of the cross section area of the throat of the diffuser to the throat of the nozzle from 4.60 to 4.90 with a flow of said off gas at said suction pressure and a flow of motive gas at a pressure from 4600 kPa-g to 5500 kPa-g; providing each of said downstream ejectors having a ratio of the cross section of the area of the nozzle exit to the nozzle throat from 1.30 to 1.45 and a ratio of the cross section area of the throat of the diffuser to the throat of the nozzle from 1.70 to 1.90 with a flow of motive gas at a pressure up to 6000 kPa-g and a discharge flow from the immediately upstream supersonic ejector; operating every ejector's nozzle exit discharge flow to be at a Mach number greater than 1; and operating every upstream ejector's nozzle exit discharge flow to be at a Mach number greater than that at the nozzle exit of the subsequent downstream ejector.