Summary of the invention:
The utility model proposes a kind of air-separating plant that utilizes cold energy of liquefied natural gas, on the one hand the power consumption of production process is significantly reduced, heater and running cost in the time of can saving gasification LNG on the other hand again kill two birds with one stone.
Technical solution of the present utility model is as follows:
A kind of air-separating plant that utilizes cold energy of liquefied natural gas, comprise: suck the filter 1 of air, air compressor 2, aerial cooler 3, molecular sieve adsorption system 4, main heat exchanger 5, high pressure fractionating column 6, low pressure fractionating column 7, subcooler 8, argon gas fractionating system 10, liquid argon storage tank 9, liquid nitrogen storage tank 11, liquid oxygen storage tank 12, liquia air choke valve J1, liquid nitrogen choke valve J2, the system argon is with the little choke valve J5 of liquid nitrogen, liquid nitrogen switch valve F1, liquid oxygen switch valve F2, liquid argon switch valve F3 and connecting line, the useless nitrogen heater 16 of accessory system etc.; Be provided with in the described main heat exchanger 5: the enterprising pressure-air heat exchanger channels A5 → A6 that goes out down, the useless channel of nitrogen n4 → n5 of low-purity that goes out on advancing down is characterized in that: also comprise in the device: the nitrogen cycle refrigeration system and the air cooling system that carry out heat exchange with cold energy of liquefied natural gas; Described main heat exchanger 5 has additional circulating nitrogen gas backheat passage S9 → S10; Wherein:
Described nitrogen cycle refrigeration system of carrying out heat exchange with cold energy of liquefied natural gas, be the joint refrigeration system with circulation and nitrogen outer circulation in the nitrogen, it comprises: circulating nitrogen gas backheat passage S9 → S10, interior cyclic nitrogen choke valve J4, outer circulation nitrogen choke valve J7 and J8 and connecting line thereof etc. in pressure nitrogen compressor 28 in low-pressure nitrogen compressor 13, high pressure nitrogen compressor 14, the outer circulation, LNG heat exchanger 25, low-cycle of higher pressure nitrogen heat exchanger 26, the main heat exchanger 5;
Be provided with in the described LNG heat exchanger 25: circulating nitrogen gas heat release pipe SN4 → SN5, the interior circulating nitrogen gas heat release pipe SN6 → SN7 of the enterprising high pressure that goes out down, the enterprising middle pressure outer circulation nitrogen heat release passage S11 → S12 that goes out down and the enterprising high pressure outer circulation nitrogen heat release pipe S15 → S16 that goes out down in the liquefied natural gas endothermic tube LNG1 → NG2 that goes out on advancing down, the enterprising sub-high pressure that goes out down;
Described low-be provided with in the cycle of higher pressure nitrogen heat exchanger 26: circulating nitrogen gas backheat passage SN1 → SN2 in circulating nitrogen gas heat release pipe SN7 → SN8 in the enterprising high pressure that goes out down, the low pressure that goes out on advancing down, enterprising go out high pressure outer circulation nitrogen heat release pipe S16 → S17 down and advance down on middle pressure outer circulation nitrogen product heat cal rod S13 → S12 of going out;
The connected mode that described and cold energy of liquefied natural gas carries out the interior cycle refrigeration system of nitrogen of heat exchange is in proper order: from low pressure fractionating column 7 top pure nitrogen gas outlet n1, take over cooler 8, meet the interior circulating nitrogen gas backheat passage SN1 → SN2 of low pressure of low-cycle of higher pressure nitrogen heat exchanger 26, through control valve F6, connect low-pressure nitrogen compressor 13, meet the interior circulating nitrogen gas heat release pipe SN4 → SN5 of sub-high pressure of LNG heat exchanger 25, connect high pressure nitrogen compressor 14, meet the interior circulating nitrogen gas heat release pipe SN6 → SN7 of high pressure of LNG heat exchanger 25, meet the interior circulating nitrogen gas heat release pipe SN7 → SN8 of high pressure of low-cycle of higher pressure nitrogen heat exchanger 26, meet interior cyclic nitrogen choke valve J4, be connected to the liquid nitrogen inlet e of high pressure fractionating column 6 through mouthful SN14 that crosses;
The connected mode that described and cold energy of liquefied natural gas carry out the nitrogen outer circulation refrigeration system of heat exchange is in proper order: the outlet of the check valve DF1 that joins from the nitrogen outlet d with high pressure fractionating column 6 middle and upper parts and the outlet joint S9 of choke valve J7, meet the circulating nitrogen gas backheat passage S9 → S10 of main heat exchanger 5, meet control valve F4, meet the middle pressure outer circulation nitrogen heat release passage S11 → S12 of LNG heat exchanger 25, connect and press nitrogen compressor 28 in the outer circulation, meet the high pressure outer circulation nitrogen heat release pipe S15 → S16 of LNG heat exchanger 25, meet the high pressure outer circulation nitrogen heat release pipe S16 → S17 of low-cycle of higher pressure nitrogen heat exchanger 26, after interface S17, divide two the tunnel to meet outer circulation nitrogen choke valve J7 and J8 respectively; Meet the inlet S9 of the circulating nitrogen gas backheat passage S9 → S10 of main heat exchanger 5 after the choke valve J7, and draw a bypass from inlet S9 and meet control valve F8, meet the middle pressure outer circulation nitrogen backheat passage S13 → S12 of low-cycle of higher pressure nitrogen heat exchanger 26 again; After the outlet of the outlet of choke valve J8 and choke valve J4 is intersected in SN14, be connected to the liquid nitrogen inlet e of high pressure fractionating column 6 again;
The air cooling system that described and cold energy of liquefied natural gas carry out heat exchange comprises: the natural gas refrigerating medium in heat exchanger 15, coolant circulation pump 17, aerial cooler 3 and connecting line and the cooling circuit of rising again; Described refrigerating medium is freon class refrigeration working medium or anti-icing fluid; The refrigerating medium closed circuit connected mode of described air cooling system is: the rise again outlet R1 of refrigerating medium path of heat exchanger 15 of natural gas connects coolant circulation pump 17, then meet the refrigerating medium passage R2 → R3 of aerial cooler 3, then be connected to the rise again inlet of refrigerating medium passage of heat exchanger 15 of natural gas; The rise again inlet of natural gas path of heat exchanger 15 of natural gas is connected with the outlet NG2 of liquefied natural gas endothermic tube in the main heat exchanger 5, the outlet NG3 of its natural gas path with regulate steam supply valve F5 and be connected;
On the basis of such scheme, a nitrogen precooled device 29 of preposition outer circulation is set up at the top of described LNG heat exchanger 25; Only be provided with liquefied natural gas and two heat exchange runners in the nitrogen precooled device 29 of described outer circulation from the circulating nitrogen gas of main heat exchanger 5, the inlet of its liquefied natural gas heat exchange runner connects the outlet from the liquefied natural gas endothermic tube LNG1 → NG2 of LNG heat exchanger 25, the outlet of its liquefied natural gas heat exchange runner connects the rise again inlet of natural gas path of heat exchanger 15 of natural gas, the inlet of its circulating nitrogen gas heat exchange runner is connected with the outlet S10 of the circulating nitrogen gas backheat passage of main heat exchanger 5, after its outlet meets control valve F4, be connected to the inlet S11 of the middle pressure outer circulation nitrogen heat release passage S11 → S12 of LNG heat exchanger 25;
Described low-middle and upper part of cycle of higher pressure nitrogen heat exchanger 26 also can set up the heat exchange runner of liquefied natural gas, its inlet docks with the low-temperature liquefaction natural gas supply mouth of pipe at liquefied natural gas station 18, and its outlet connects the inlet of the liquefied natural gas endothermic tube LNG1 → NG2 of LNG heat exchanger 25;
On the basis of above-mentioned each scheme, the air cooling system that described and cold energy of liquefied natural gas carry out heat exchange also can be one and integrate the rise again condensation evaporation heat exchanger of heat exchanger 15 and aerial cooler 3 of natural gas; Described condensation evaporation heat exchanger is casing, is made up of case shell 30, the natural gas fluorine Lyons working medium 31 of rising again in heat exchanger 15, aerial cooler 3 and the case; The natural gas heat exchanger 15 of rising again places top in the casing as the condenser of fluorine Lyons working medium, leave the import NG2 and the outlet NG3 that are connected with natural gas, aerial cooler 3 places the evaporimeter of the interior bottom of casing as fluorine Lyons working medium, leaves the import A3 and the outlet A4 that are connected with compressed air.
Because the utility model is provided with nitrogen cycle refrigeration system and the air cooling system that carries out heat exchange with cold energy of liquefied natural gas in air-separating plant, the liquefied natural gas of quoting-162 ℃ (111K) at liquefied natural gas station comes cooled compressed air by multistage cycle refrigeration system and air cooling system in the nitrogen, outside the nitrogen, made full use of the valuable cold energy of LNG, to produce liquid oxygen, liquid nitrogen and liquid argon be that the power consumption of the air-separating plant of major product reduces greatly thereby make.Calculating shows that the unit kilogram liquid oxygen of the air-separating plant that the utility model proposes or the power consumption of liquid nitrogen can reduce to 0.3~0.5 kilowatt hour from 0.9~1.2 traditional kilowatt hour, is 10000NM for oxygen output
3The air-separating plant day of/h is produced 330 tons of liquid oxygen, 300 tons of liquid nitrogen, 17 tons of liquid argons, and a year amount of electricity saving reaches 9,000 ten thousand~100,000,000 kilowatt hours, is worth more than 5000~6,000 ten thousand yuan, and the cold energy of 700 tons of liquefied natural gas of daily consumption amounts to 2.0 * 10 approximately
11The kJ energy also need not to establish in addition firing equipment and consumes the sea water pump merit.In addition,, adopt circulating nitrogen gas and fluorine Lyons or anti-icing fluid cooled compressed air, guaranteed device security because liquefied natural gas heat exchanger tube LNG1 → NG2 is placed in the LNG heat exchanger 25, keeps apart with the compressed air loop; Also saved parts such as cryogenic expansion machine in the device, compact conformation, cost is low.Simultaneously, the utility model also has and transforms less and investment advantage such as province to traditional air separation plant.
The specific embodiment:
Further specify concrete technology contents of the present utility model below in conjunction with accompanying drawing.
Equipment that air-separating plant adopted and the adapter path thereof of embodiment 1 is (seeing shown in the accompanying drawing 1):
Air cleaner 1 leaves air suction inlet A1, and its outlet meets the inlet A2 of air compressor 2; The outlet of air compressor 2 meets the air intake A of aerial cooler 3
3The air outlet slit of aerial cooler 3 connects the air intake of molecular sieve adsorption system 4, tie point A4; The air outlet slit of molecular sieve adsorption system 4 meets the inlet of the pressure-air heat exchanger tube at top, main heat exchanger 5 hot junction, tie point A5; The outlet A6 of the pressure-air heat exchanger tube of main heat exchanger 5 is located at the bottom, and it is connected with the pressure-air inlet a of high pressure fractionating column 6; The liquia air outlet b of high pressure fractionating column 6 takes over cooler 8, and the outlet of liquia air coil pipe is connected contact gb with liquia air choke valve J1; The liquia air of the crude argon column 19 in liquia air choke valve J1 outlet and the argon gas fractionating system 10 enters the mouth and is connected; Crude argon column 19 has the pipeline of two liquia airs that are connected with low pressure fractionating column 7, and tie point is respectively L1, L2; Crude argon column 19 also has the pipeline of two gas air that are connected with low pressure fractionating column 7, and tie point is respectively g1, g2; The liquid nitrogen outlet c of high pressure fractionating column 6 is connected with the liquid nitrogen coil pipe of subcooler 8, the liquid nitrogen coil pipe of subcooler 8 outlet gc divides with liquid nitrogen choke valve J2 be connected laggard low pressure fractionating column 7 at two the tunnel: the one tunnel, interface Ln, another road joins with liquid nitrogen storage tank 11 behind control valve F1; The tubule that the low-purity liquid nitrogen of high pressure fractionating column 6 outlet f draws in regular turn with argon gas fractionating system 10 in the following heat exchanger 21, system argon of smart argon purifying column 20 with the little choke valve J5 of liquid dirt nitrogen with after last heat exchanger 22 is connected, converge mutually behind n3 with the lower purified nitrogen tracheae that comes out from low pressure fractionating column 7 outlet n2, enter the lower purified nitrogen gas coil pipe of subcooler 8; The outlet of the lower purified nitrogen gas coil pipe of subcooler 8 is connected tie point n4 with the low-temperature end of the low-purity nitrogen gas of main heat exchanger 5 inlet; The useless channel of nitrogen of low-purity nitrogen gas in main heat exchanger 5 passes through, and its temperature end outlet n5 is connected with useless nitrogen heater 16, also joins with vent valve F7 simultaneously; The outlet of useless nitrogen heater 16 is connected tie point n6 with the nitrogen inlet of molecular sieve adsorption system 4; The nitrogen outlet n7 of molecular sieve adsorption system 4 leads to atmosphere; After meeting control valve F2, the liquid oxygen outlet Lo of low pressure fractionating column 7 bottoms is connected with liquid oxygen storage tank 12; Crude argon outlet Y1 is arranged at the nearly top of crude argon column 19 in the argon gas fractionating system 10, connect argon gas heat exchanger 24, through interface Y2 connect hydrogen palladium catalytic deoxidation device 23, through interface Y3 tieback argon gas heat exchanger 24, connect smart argon purifying column 20, be connected with liquid argon storage tank 9 again after meeting control valve F3 by the bottom liquid argon outlet of smart argon purifying column 20 through interface Y4; Liquid nitrogen storage tank 11, liquid argon storage tank 9 and liquid oxygen storage tank 12 all leave the outlet of liquid nitrogen, liquid argon, liquid oxygen.
Connection with top is identical with common air separation unit, and the nitrogen cycle refrigeration system and the air cooling system that carry out heat exchange with cold energy of liquefied natural gas that difference of the present utility model is in air separation unit to be increased; Wherein:
Described nitrogen cycle refrigeration system of carrying out heat exchange with cold energy of liquefied natural gas, be the joint refrigeration system with circulation and nitrogen outer circulation in the nitrogen, it comprises: circulating nitrogen gas backheat passage S9 → S10, interior cyclic nitrogen choke valve J4, outer circulation nitrogen choke valve J7 and J8 and connecting line thereof etc. in pressure nitrogen compressor 28 in low-pressure nitrogen compressor 13, high pressure nitrogen compressor 14, the outer circulation, LNG heat exchanger 25, low-cycle of higher pressure nitrogen heat exchanger 26, the main heat exchanger 5;
Be provided with in the described LNG heat exchanger 25: circulating nitrogen gas heat release pipe SN4 → SN5, the interior circulating nitrogen gas heat release pipe SN6 → SN7 of the enterprising high pressure that goes out down, the enterprising middle pressure outer circulation nitrogen heat release passage S11 → S12 that goes out down and the enterprising high pressure outer circulation nitrogen heat release pipe S15 → S16 that goes out down in the liquefied natural gas endothermic tube LNG1 → NG2 that goes out on advancing down, the enterprising sub-high pressure that goes out down;
Described low-be provided with in the cycle of higher pressure nitrogen heat exchanger 26: circulating nitrogen gas backheat passage SN1 → SN2 in circulating nitrogen gas heat release pipe SN7 → SN8 in the enterprising high pressure that goes out down, the low pressure that goes out on advancing down, enterprising go out high pressure outer circulation nitrogen heat release pipe S16 → S17 down and advance down on middle pressure outer circulation nitrogen product heat cal rod S13 → S12 of going out;
The connected mode that described and cold energy of liquefied natural gas carries out the interior cycle refrigeration system of nitrogen of heat exchange is in proper order: from low pressure fractionating column 7 top pure nitrogen gas outlet n1, take over cooler 8, meet the interior circulating nitrogen gas backheat passage SN1 → SN2 of low pressure of low-cycle of higher pressure nitrogen heat exchanger 26, through control valve F6, connect low-pressure nitrogen compressor 13, meet the interior circulating nitrogen gas heat release pipe SN4 → SN5 of sub-high pressure of LNG heat exchanger 25, connect high pressure nitrogen compressor 14, meet the interior circulating nitrogen gas heat release pipe SN6 → SN7 of high pressure of LNG heat exchanger 25, meet the interior circulating nitrogen gas heat release pipe SN7 → SN8 of high pressure of low-cycle of higher pressure nitrogen heat exchanger 26, meet interior cyclic nitrogen choke valve J4, be connected to the liquid nitrogen inlet e of high pressure fractionating column 6 through mouthful SN14 that crosses;
The connected mode that described and cold energy of liquefied natural gas carry out the nitrogen outer circulation refrigeration system of heat exchange is in proper order: the outlet of the check valve DF1 that joins from the nitrogen outlet d with high pressure fractionating column 6 middle and upper parts and the outlet joint S9 of choke valve J7, meet the circulating nitrogen gas backheat passage S9 → S10 of main heat exchanger 5, meet control valve F4, meet the middle pressure outer circulation nitrogen heat release passage S11 → S12 of LNG heat exchanger 25, connect and press nitrogen compressor 28 in the outer circulation, meet the high pressure outer circulation nitrogen heat release pipe S15 → S16 of LNG heat exchanger 25, meet the high pressure outer circulation nitrogen heat release pipe S16 → S17 of low-cycle of higher pressure nitrogen heat exchanger 26, after interface S17, divide two the tunnel to meet outer circulation nitrogen choke valve J7 and J8 respectively; Meet the inlet S9 (being the outlet of check valve DF1 and the outlet joint S9 of choke valve J7) of the circulating nitrogen gas backheat passage S9 → S10 of main heat exchanger 5 after the choke valve J7, and draw a bypass and meet control valve F8 from inlet S9, meet the middle pressure outer circulation nitrogen backheat passage S13 → S12 of low-cycle of higher pressure nitrogen heat exchanger 26 again; After the outlet of the outlet of choke valve J8 and choke valve J4 is intersected in SN14, be connected to the liquid nitrogen inlet e of high pressure fractionating column 6 again:
Pressing nitrogen compressor 28 in low-pressure nitrogen compressor 13, high pressure nitrogen compressor 14 and the outer circulation is turbine type, and the three can a shared motor 27; LNG heat exchanger 25 is a coiled, and what flow between pipe is outer circulation nitrogen from main heat exchanger 5; Low-cycle of higher pressure nitrogen heat exchanger 26 is a coiled, and what flow between pipe is low pressure recycle nitrogen; Main heat exchanger 5 is a heat-exchangers of the plate type.
The air cooling system that described and cold energy of liquefied natural gas carry out heat exchange comprises: the natural gas refrigerating medium in heat exchanger 15, coolant circulation pump 17, aerial cooler 3 and connecting line and the cooling circuit of rising again; Described refrigerating medium is freon class refrigeration working medium or anti-icing fluid; The refrigerating medium closed circuit connected mode of described air cooling system is: the rise again outlet R1 of refrigerating medium path of heat exchanger 15 of natural gas connects coolant circulation pump 17, then meet the refrigerating medium passage R2 → R3 of aerial cooler 3, then be connected to the rise again inlet of refrigerating medium passage of heat exchanger 15 of natural gas; The rise again inlet of natural gas path of heat exchanger 15 of natural gas is connected with the outlet NG2 of liquefied natural gas endothermic tube in the main heat exchanger 5, the outlet NG3 of its natural gas path with regulate steam supply valve F5 and be connected.
Refrigerating medium can be selected freon R22 or R134a for use, also can select anti-icing fluid for use, as glycol solution; The natural gas heat exchanger 15 of rising again can adopt coiled, and what flow between pipe is refrigerating medium; Coolant circulation pump 17 can adopt rotary.
The air-separating plant of embodiment 1 is operation like this:
Air enters air compressor 2 and is compressed to more than the 0.5MPa after air cleaner 1 filters removal dust impurity, compressed air is cooled to 1~5 ℃ (274~278K) by refrigerating medium in aerial cooler 3, enter molecular sieve adsorption system 4, fall the laggard pressure-air heat exchanger channels A5 → A6 that goes into main heat exchanger 5 of airborne moisture content and carbon dioxide by molecular sieve adsorption; Middle pressure circulating nitrogen gas backheat passage SN9 → SN10 that goes out on also being provided with down in the main heat exchanger 5 and the low-purity channel of nitrogen n4 → n5 that gives up, middle pressure circulating nitrogen gas and the useless nitrogen of low-purity that compressed air is backflowed about-180 ℃ (93K) cool off, become the saturated mode humid air, then enter the inlet a of high pressure fractionating column 6;
In high pressure fractionating column 6, air and liquid nitrogen condensation and evaporation repeatedly on the column plate of multilayer under the overhead streams, the oxygen-enriched liquid air that contains more liquid oxygen composition combines in the bottom of high pressure fractionating column 6, nitrogen combines in the top of high pressure fractionating column 6, and with low pressure fractionating column 7 bottom liquid oxygen heat-shifts, nitrogen is condensed into liquid then;
The liquid nitrogen that high pressure fractionating column 6 top liquid nitrogen gatherers are collected is drawn by outlet c, further lower the temperature through subcooler 8, be depressurized to about 0.14MPa through liquid nitrogen choke valve J2 again, enter the interface Ln at low pressure fractionating column 7 tops, as the phegma at low pressure fractionating column 7 tops, another part is banished liquid nitrogen storage tank 11 and is stored behind control valve F1;
The oxygen-enriched liquid air of high pressure fractionating column 6 bottoms flows out after subcooler 8 coolings from outlet b, again after liquia air choke valve J1 step-down, enter the crude argon column 19 of argon gas fractionating system 10, oxygen-enriched liquid air is flow in the low pressure fractionating column 7 through the pipeline of the liquia air that is connected with low pressure fractionating column 7 interface L1, the L2 from low pressure fractionating column 7 middle parts again after tentatively extracting argon gas in argon gas fractionating system 10, rich argon air in the low pressure fractionating column 7 enters crude argon column 19 by connecting line g1, and the air in the crude argon column 19 returns low pressure fractionating column 7 through connecting line g2; The high-purity liquid oxygen combines in low pressure fractionating column 7 bottoms after 7 fractionation of low pressure fractionating column, and puts to liquid oxygen storage tank 12 storages through control valve F2 from interface Lo;
The high pure nitrogen that low pressure fractionating column 7 top exit n1 flow out, behind subcooler 8 recovery section colds, enter the interior circulating nitrogen gas backheat passage SN1 → SN2 of low pressure of low-cycle of higher pressure nitrogen heat exchanger 26, cold is passed to the cycle of higher pressure nitrogen of circulating nitrogen gas heat release pipe SN7 → SN8 in the enterprising high pressure that goes out down, be warming up to about 110~150K (163~-123 ℃), then entering low-pressure nitrogen compressor 13 compresses, be compressed to more than the 1.0MPa, outlet temperature surpasses after the 220K (53 ℃), enter the interior circulating nitrogen gas heat release pipe SN4 → SN5 of sub-high pressure of LNG heat exchanger 25, emit heat and give LNG, temperature rolls back about 120~150K (153~-123 ℃), enter high pressure nitrogen compressor 14 again and be compressed to 5.0~5.5MPa, the interior circulating nitrogen gas heat release pipe SN6 → SN7 of high pressure that enters LNG heat exchanger 25 again emits heat and gives LNG, after temperature is reduced to about 115~150K (158~-123 ℃), enter the interior circulating nitrogen gas heat release pipe SN7 → SN8 of high pressure of low-cycle of higher pressure nitrogen heat exchanger 26 again, further be cooled to about 100K (173 ℃), and after interior cyclic nitrogen choke valve J4 throttling is depressured to about 0.5MPa, produce a large amount of liquid nitrogen and fractional saturation nitrogen, and after mouthful SN14 that crosses enters the liquid nitrogen inlet e of high pressure fractionating column 6;
The middle pressure circulating nitrogen gas that nitrogen outlet d from high pressure fractionating column 6 middle and upper parts draws just just starts the initial stage at device, through check valve DF1, advances the middle pressure circulating nitrogen gas backheat passage S9 → S10 of main heat exchanger 5; The nitrogen of outer circulation is no longer drawn from the nitrogen outlet d of high pressure fractionating column 6 middle and upper parts when the normal operation of device, and draws the low temperature nitrogen after nitrogen choke valve J7 throttling; The low temperature outer circulation nitrogen of about 90~100K (183~-173 ℃) is passed to compressed air to cold in the middle pressure circulating nitrogen gas backheat passage S9 → S10 of main heat exchanger 5, while self, backheat was to the temperature that enters the main heat exchanger inlet near compressed air, be adjusted to suitable flow through control valve F4, then enter the middle pressure outer circulation nitrogen heat release passage S11 → S12 of LNG heat exchanger 25, again the natural gas that is liquefied is cooled to about 120~150K (153~123 ℃), enter again and press nitrogen compressor 28 in the outer circulation, nitrogen pressure is reduced to 3~5MPa, the circulating nitrogen gas temperature of outlet is approximately higher than 190K (83 ℃), then enter the high pressure outer circulation nitrogen heat release pipe S15 → S16 of LNG heat exchanger 25, absorbing the LNG cold is cooled to about 115~140K (158~133 ℃), enter the high pressure outer circulation nitrogen heat release pipe S16 → S17 of low-cycle of higher pressure nitrogen heat exchanger 26 again, further be cooled to about 100K (173 ℃) again; At the beginning of the device starting, close choke valve J7, throttle opening J8, allow circulating nitrogen gas enter knockout tower, participate in fractionation; After being full of high pure nitrogen in the circulation pipe, close choke valve J8, open outer circulation nitrogen choke valve J7 and control valve F8, pressure is also at about 0.5MPa after the throttling, and above-mentioned loop outer circulation nitrogen refrigeration system is normally moved; The nitrogen of this system's outer circulation plays refrigeration and transmission LNG cold energy is given compressed air, interior circulation compressed nitrogen and outer circulation compressed nitrogen, and do not enter fractionating column, thereby can avoid entering fractionating column and the danger that causes is closed in oxidation because of natural gas leaking;
The low-purity nitrogen gas that low pressure fractionating column 7 tops outlet n2 flows out, with draw from high pressure fractionating column 6 centre exit f, in the argon gas fractionating system 10 of flowing through the following heat exchanger 21 of smart argon purifying column 20 and system argon with the liquid little choke valve J5 of dirty nitrogen and on the nitrogen of heat exchanger 22 converge at interface n3, then temperature enters the useless channel of nitrogen n4 → n5 of main heat exchanger 5 about 90K (183 ℃) after subcooler 8 heat exchange, in main heat exchanger, absorb compressed-air actuated heat and by backheat, finally at outlet n5 place by backheat to the compressed air temperature that approaches the A5 porch; With this backheat to the lower purified nitrogen gas of room temperature after useless nitrogen heater 16 is by the electric heater heating, deliver to molecular sieve adsorption system 4, remove moisture content and carbon dioxide in the saturated molecular sieve of desorption, make it regeneration, or by valve F7 emptying;
Rich argon liquid air in argon gas fractionating system 10 behind crude argon column 19 prefractionations, through heat exchanger 24 heat exchange, in degasifier 23 through hydrogenation palladium catalytic deoxidation, after heat exchanger 24 backheats, deliver to smart argon purifying column 20 and purify again, liquid argon is stored in the liquid argon storage tank 9 through switch valve F3;
Temperature is still lower the liquid natural gas that flows through liquefied natural gas heat exchanger tube LNG1 → NG2 absorbs the heat of circulating nitrogen gas in LNG heat exchanger 25 after, so be introduced to the natural gas heat exchanger 15 of rising again, make the refrigerating medium condensation, the secondary refrigerant liquid circulating pump 17 that is cooled is delivered to the refrigerating medium passage of aerial cooler 3, be compressed the air heat evaporation, compressed air is cooled simultaneously, can be chilled to 1~5 ℃ (274~278K).
This device and without the LNG cold energy, same day output is 330 tons of liquid oxygen, 300 tons of liquid nitrogen, the conventional air-separating plant that liquid argon is 17 tons is compared, about 30~330,000 kilowatt hour/days of using electricity wisely, use initial temperature-162 ℃ (111K), pressure is the cold energy of liquefied natural gas 700 ton per days of 1~8MPa, saved cyclic nitrogen tolerance about 3/4, make the compressor cost of investment of cyclic nitrogen reduce more than 50%, and can save common handpiece Water Chilling Units one cover of 300~500 standard tons, comprehensive gross investment funds can save 10~20%, save 1000~2,000 ten thousand yuan approximately, year economize on electricity 9,000 ten thousand~100,000,000 kilowatt hours, about 6,000 ten thousand yuan, great economic benefit is arranged.
Distinct device and the adapter path thereof of the air-separating plant of embodiment 2 and embodiment 1 is (seeing shown in the accompanying drawing 2):
Set up a nitrogen precooled device 29 of preposition outer circulation at the top of described LNG heat exchanger 25, wherein only be provided with liquefied natural gas and two heat exchange runners from the circulating nitrogen gas of main heat exchanger 5, the inlet of its liquefied natural gas heat exchange runner connects the outlet from the liquefied natural gas endothermic tube LNG1 → NG2 of LNG heat exchanger 25, the outlet of its liquefied natural gas heat exchange runner connects the rise again inlet of natural gas path of heat exchanger 15 of natural gas, the inlet of its circulating nitrogen gas heat exchange runner is connected with the outlet S10 of the circulating nitrogen gas backheat passage of main heat exchanger 5, after its outlet meets control valve F4, be connected to the inlet S11 of the middle pressure outer circulation nitrogen heat release passage S11 → S12 of LNG heat exchanger 25.This is effective for high pressure LNG system.The nitrogen precooled device 29 of preposition outer circulation can adopt coil exchanger, and what flow between pipe is middle pressure outer circulation nitrogen from main heat exchanger 5;
In addition, liquefied natural gas endothermic tube in the LNG heat exchanger 25 also can move down one section to described low-middle and upper part of cycle of higher pressure nitrogen heat exchanger 26, be that its inlet docks with the low-temperature liquefaction natural gas supply mouth of pipe at liquefied natural gas station 18, its outlet connects the inlet of the liquefied natural gas endothermic tube LNG1 → NG2 of LNG heat exchanger 25; The low-temperature liquefaction natural gas supply pipe at liquefied natural gas station 18 is introduced into the middle and upper part of low-cycle of higher pressure nitrogen heat exchanger 26, the low temperature cold of LNG is concentrated top-down cycle of higher pressure nitrogen in the low-cycle of higher pressure nitrogen heat exchanger 26 of supply earlier, then enter the liquefied natural gas endothermic tube LNG1 → NG2 of LNG heat exchanger 25; It is favourable must keeping the system of the operating mode of 6~8Mpa air pressure after this is utilized for the LNG cold energy;
If also want to utilize device of the present utility model to produce oxygen or pure nitrogen gas, can in device, increase corresponding pipeline according to prior art.As oxygen pipeline set among the embodiment 2: establish the outlet Go of a gas oxygen from the bottom of low pressure fractionating column 7, the top of liquid oxygen outlet, enter the oxygen backheat passage of establishing in addition in the main heat exchanger 5 through tube connector, in main heat exchanger 5 backheat to room temperature after control valve F8 send;
Moreover, argon gas fractionating system 10 in the device also can be simplified: economize dehydrogenation palladium catalytic deoxidation device 23 and heat exchanger 24, and in crude argon column 19 and pure argon column 20, place regular honeycomb padding fractionator, liquid air enters low pressure fractionating column 7 through choke valve J1, liquid air is established branch road in addition and is entered crude argon column 19 evaporator overhead condensers through choke valve J3, rich argon air enters crude argon column 19 bottoms by the outlet g1 of low pressure fractionating column 7, the liquid air that has been extracted argon gas returns low pressure fractionating column 7 through interface L1, crude argon column 19 tops have the saturated air that has been extracted argon gas to return low pressure fractionating column 7 through interface g2, crude argon column 19 nearly tops have crude argon directly to enter the middle part of pure argon column 20, and the following heat exchanger 21 and the last heat exchanger 22 of pure argon column 20 place in the tower, required liquid nitrogen heating and cooling loop is identical with embodiment 1.
In the device of embodiment 1 and embodiment 2, also can connect the liquid nitrogen pipeline of a low-purity in the f at described high pressure fractionating column 6 middle parts outlet in addition, through the dirty nitrogen primary throttle valve of subcooler 8, liquid, be connected to the dirty helium interface on low pressure fractionating column 7 tops, one liquid nitrogen reflux liquid is just arranged again at low pressure fractionating column 7 tops like this, and is beneficial for obtaining high pure nitrogen.
Air cooling system shown in the accompanying drawing 3 is a kind of air cooling integrated equipment of condensation evaporation heat exchanger form.This equipment is to integrate the rise again condensation evaporation heat exchanger of heat exchanger 15 and aerial cooler 3 of natural gas; Described condensation evaporation heat exchanger is casing, is made up of case shell 30, the natural gas fluorine Lyons working medium 31 of rising again in heat exchanger 15, aerial cooler 3 and the case; The natural gas heat exchanger 15 of rising again places the condenser of casing internal upper part as fluorine Lyons working medium, leave the import NG2 and the outlet NG3 that are connected with natural gas, aerial cooler 3 places the evaporimeter of the interior bottom of casing as fluorine Lyons working medium, leave the import A3 and the outlet A4 that are connected with compressed air, like this, just saved coolant circulation pump 17.Fluorine Lyons working medium is selected R22 or R134a for use, and filled pressure is 0.1~0.5MPa, saturation temperature 235~270K (38~-3 ℃); During work, liquid freon gathers in case bottom and is compressed the air heat evaporation, is cooled off by cryogenic natural gas in steam fluorine Lyons of box top and is condensed into liquid, drips at the bottom of case by own wt.This condensation evaporation heat exchanger is large-scale heat pipe heat exchanging interchanger, and very high heat transfer efficiency is arranged.