Air separation apparatus to produce oxygen and nitrogen through isobaric separation

Abstract

This invention is about an air separation apparatus to produce oxygen and nitrogen through isobaric separation, which is based on the Rankine cycle system of similar thermal energy power circulation apparatus at cryogenic side, a liquid pump is used to input work and the cold is made up to the air separation apparatus with refrigerating media, so as to realize the isobaric separation of air to produce nitrogen and oxygen. The air separation apparatus of this invention can save energy by over 30% as compared with the traditional advanced apparatus with the identical refrigerating capacity, and it can also realize centralize gas supply via the air separation apparatus, therefore it constitutes a breakthrough to the traditional air separation technology and refrigeration theory, with substantial economic, social and environmental protection benefits.

Claims

1. An air separation apparatus to produce oxygen and nitrogen through isobaric separation, comprising: an air purifying system for air purification, which comprises an air compressor for moving an air stream through an air purifier to obtain a pre-cleaned air stream; a precooling system for cooling the pre-cleaned air stream from the air purifying system, the precooling system comprises a main cold exchanger and an auxiliary cold exchanger for cooling the pre-cleaned air stream; a rectification system for separating nitrogen and oxygen from the pre-cooled air from the precooling system, the rectification system comprises a nitrogen liquefier, a subcooler, and a rectification apparatus having an upper column, a lower column, and a condensing evaporator disposed between the upper column and the lower column, and the condensing evaporator is fluidly connected with the lower column, wherein the lower column receives the pre-cooled air from the auxiliary cold exchanger and separates the pre-cooled air into an oxygen-rich liquid air stream and a first gaseous nitrogen stream, the upper column receives a first liquid nitrogen stream from the subcooler, the subcooler receives the first gaseous nitrogen stream from the lower column and cools the first gaseous nitrogen stream to form the first liquid nitrogen stream, and the nitrogen liquefier condenses a second gaseous nitrogen stream from the upper column to obtain a second liquid nitrogen stream; and a cold makeup system for supplying cold energy to the rectification system, the cold makeup system comprises: a refrigerant tank containing a liquid refrigerant, a hydraulic pump for transferring the liquid refrigerant through the nitrogen liquefier and the subcooler in the rectification system, and the auxiliary cold exchanger in the pre-cooling system to obtain a superheated refrigerant stream, an expander for expanding the superheated refrigerant, and a cold regenerator that cools the superheated refrigerant from the expander.

2. The apparatus as described in claim 1, wherein, in the cold makeup system, the refrigerant from the hydraulic pump cools the expanded superheated refrigerant from the expander in the cold regenerator.

3. The apparatus as described in claim 2, wherein the rectification system further comprises a liquid air absorber fluidly connected with the lower column and the subcooler, wherein the oxygen-rich air from the lower column passes the liquid air absorber before entering the subcooler.

4. The apparatus as described in claim 1, wherein the expander comprises a braking equipment that is a fan, a motor, a hydraulic pump, or a gas compressor.

5. The apparatus as described in claim 4, wherein the expander expands and cools the superheated refrigerant.

6. The apparatus as described in claim 5, wherein the rectification system further comprises a liquid oxygen booster pump and a liquid oxygen absorber, wherein the liquid oxygen booster pump pumps a liquid oxygen stream from the upper column through the liquid oxygen absorber and the main cold exchanger to produce a pressurized product oxygen stream.

7. The apparatus as described in claim 6, wherein the lower column, the condensing evaporator, and the upper column are integrated in one housing.

8. The apparatus as described in claim 7, wherein the air purifier is a molecular sieve purifier, a reversible cold exchanger, or a stone cooler.

9. The apparatus as described in claim 6, wherein the lower column, the condensing evaporator, and the upper column are in separated structures.

Description

DESCRIPTION OF FIGURES

(1) FIG. 1 is a process schematic diagram of a 3200 m.sup.3/h tube type oxygenerator:

(2) In FIG. 1: 101cold accumulator, 102automatic valve box, 103turbine expander, 104expansion filter, 105liquefier, 106lower column, 107condensing evaporator, 108upper column, 109liquid oxygen absorber, 110liquid air adsorber, 111liquid air subcooler, 113liquid oxygen pump, 114carbon dioxide absorber.

(3) FIG. 2 is a process schematic diagram of a reversible heat exchanger self-cleaning 10000 m.sup.3/h oxygenerator:

(4) In FIG. 2: 201reversible heat exchanger, 202automatic valve box, 203liquefier (waste nitrogen), 204liquefier (pure nitrogen), 205liquefier (oxygen), 206turbine expander, 207lower column, 208condensing evaporator, 209upper column, 210liquid air subcooler, 211liquid oxygen subcooler, 212liquid nitrogen subcooler, 213liquid oxygen absorber, 214liquid air absorber, 215liquid oxygen pump.

(5) FIG. 3 is a process schematic diagram of a 30000 m.sup.3/h external compression oxygenerator:

(6) In FIG. 3: ACair cooling tower, AFair filter, APliquid argon pump, TCair centrifugal compressor, BT1supercharger (expander), C1lower column, C2upper column, C701crude argon column I, C702crude argon column II, C703pure argon column, E1main heat exchanger, E2liquid air liquid nitrogen subcooler, EHelectric heater, ET1turbine expander, K1main condensing evaporator, K701crude argon condenser, K702crude argon liquefier, K704pure argon evaporator, MS1 and MS2molecular sieve purifiers; PV701liquid nitrogen balance, WCwater cooling tower, WP1 and WP2water pump.

(7) FIG. 4 is a process schematic diagram of a 52000 m.sup.3/h oxygenerator for chemical application:

(8) In FIG. 4: ACair cooling tower, AFair filter, ATC1air centrifugal compressor, ATC2air cycle supercharger, APliquid argon pump, C1lower column, C2upper column, C801crude argon column I, C802crude argon column II, C803pure argon column, E1main heat exchanger, E3subcooler, ETexpander, BCsupercharger (expander), ECwater cooling tower, SHsteam heater, K1main condensing evaporator, K801crude argon condenser, K802crude argon liquefier, K803pure argon condenser, K804pure argon evaporator, MS1 and MS2molecular sieve purifier; NPliquid nitrogen pump, OPliquid oxygen pump.

(9) FIG. 5 is a process schematic diagram of an air separation apparatus to produce oxygen and nitrogen through isobaric separation of this invention:

(10) In FIG. 5: 1air, 2air filter, 3gas compressor, 4cleaner, 5pre-cleaned air, 6main cold exchanger, 7air coming into lower column, 8lower column, 9condensing evaporator, 10upper column, 11oxygen-enriched liquid air, 12liquid air absorber, 13lower column nitrogen, 14liquid oxygen, 15liquid oxygen pump, 16liquid oxygen absorber, 17liquid oxygen, 18refrigerant tank, 19liquid refrigerant, 20hydraulic pump, 21cold regenerator, 22liquid nitrogen, 23cryogenic nitrogen, 24refrigerating media superheated vapor, 25expander, 26expander outlet exhaust, 27throttle valve, 28braking equipment, 29nitrogen liquefier, 30liquid nitrogen, 31liquid nitrogen booster pump, 32HP nitrogen, 33liquid oxygen booster pump, 34HP oxygen, 35cryogenic oxygen, 36product oxygen, 37waste nitrogen pipeline, 38waste nitrogen, 39product nitrogen, 40air, 41auxiliary cold exchanger, 42subcooler.

EMBODIMENTS

(11) In the following, this invention is further described in detail in conjunction with figures and embodiments.

Embodiment 1

(12) As shown in FIG. 5, an air separation apparatus to produce oxygen and nitrogen through isobaric separation, with liquid nitrogen gas as refrigerating media, with the specific embodiment as follows:

(13) (1) Raw air 1 flows through air filter 2 to remove dust and mechanical foreign substance, and enters the air compressor 3 to be compressed to the desired pressure;

(14) (2) The precooled compressed air enters purifier 4 to remove moisture, carbon dioxide and small amount of acetylene and hydrocarbon compounds, and then cooled via main cold exchanger 6 to the liquefaction temperature, before entering lower column 8 of the rectification apparatus;

(15) (3) In lower column 8 rough distillation is performed to obtain oxygen-enriched liquid air 11, after removing acetylene in liquid air absorber 12 and supercooling in subcooler 42, it is directly sent to the middle of the upper column without throttling, and it flows via condensing evaporator 9 to evaporate to produce nitrogen, and obtain liquid oxygen and oxygen;

(16) (4) The liquid nitrogen produced in condensing evaporator 9 flows back to lower column 8 as reflux liquid;

(17) (5) The liquid oxygen 14 obtained from rectification in upper column 10 flows via liquid oxygen pump 15 and liquid oxygen absorber 16 to remove acetylene and hydrocarbon compounds, and returns to the bottom of upper column, to form the liquid oxygen circulation circuit; or the liquid oxygen 14 after removing acetylene via liquid oxygen pump 15 and liquid oxygen absorber 16 is sent out directly as product 17; or it is boosted by liquid oxygen booster pump 33, and after recovering cold energy by main cold exchanger 6, is sent out as product HP oxygen 34;

(18) (6) The waste nitrogen is diverted out from the bottom of the auxiliary column of the upper column, and flows via waste nitrogen pipeline 37 and main cold exchanger 6 to recover cold energy, then it is sent to the nitrogen and water precooler or is vented directly;

(19) (7) In main cold exchanger 6, cold is supplied by the gaseous nitrogen 23 diverted from the top of upper column and gaseous oxygen 35 diverted from the bottom of upper column and waste nitrogen as the cold sources, to cool the pre-cleaned air 5, and then it enters the lower column and the rectification apparatus to separate out nitrogen and oxygen;

(20) (7) Auxiliary cold exchanger 41 provides cold with a cold makeup system, or provides cold with the gaseous nitrogen 23 diverted from the top of upper column and gaseous oxygen 35 diverted from the bottom of upper column and waste nitrogen as the cold sources, to cool the air 40 to the liquefaction temperature;

(21) (8) The circulation process of the refrigerating media in the cold makeup system is:

(22) The cold makeup system of the said apparatus refers to the process that liquid refrigerant 19 from refrigerant tank 18, flows via hydraulic pump 20, cold regenerator 21, nitrogen liquefier 29, subcooler 42, and auxiliary cold exchanger 41, to form the refrigerating media superheated vapor 24, after expansion and temperature reduction via expander 25, it flows via cold regenerator 21 again and throttle valve 27 and returns to the refrigerant tank 18, to make up the required cold energy via the subcooler 42 and auxiliary cold exchanger 41 to the air separation system, so as to form the cold dynamic cycle circuit of the refrigerant; the braking equipment 28 of the said expander 25 refers to an air compressor, design to increase pressure of the gas product oxygen or nitrogen.

(23) Nitrogen 23 is condensed via nitrogen liquefier 29 into product liquid nitrogen 22, or after increasing pressure via liquid nitrogen booster pump 31 and recovering cold energy via main cold exchanger 6, is output as HP nitrogen 32.

(24) The said refrigerant tank 18 is provided with necessary thermal and cold insulation, such as thermal isolated vacuum container, and insulation materials such as pearlite.

(25) The equipment and their backup systems, pipes, instruments, valves, cold insulation and bypass facilities with regulation functions not described in this invention shall be configured with mature technologies of generally known traditional refrigerating cycles.

(26) Safety and regulation and control facilities associated with the air separation cycle apparatus of this invention are provided, so that the apparatus can operate economically and safely with high thermal efficiency, to achieve the goal of energy conservation, consumption reduction and environmental protection.

(27) This invention has been made public with an optimum embodiment as above, however, it is not used to restrict this invention, all variations or decorations made by those familiar with this technology without deviating from the spirit and scope of this invention also falls into the scope of protection of this invention. Therefore, the scope of protection of this invention shall be that defined by the claims in this application.