Utilize the full-liquid air separation device and the method for cold energy of liquefied natural gas
Technical field
The present invention relates to air-separating plant, be specifically related to a kind of full-liquid air separation device and method of utilizing cold energy of liquefied natural gas.
Background technology
Air separation equipment is exactly with air liquefaction, rectifying, finally is separated into the gas separation equipment of oxygen, nitrogen and other valuable gases, is called for short air separation plant.Air once was called as " permanent gas " to 19 end of the centurys, it is found that air also can liquefy under profound hypothermia, and because of oxygen, nitrogen boiling point difference, can isolate oxygen and nitrogen from liquefied air.First commercial oxygenerator made in 1903, and it just is used for the gas welding and the cutting of metal at first.At the end of the thirties, nitrogen fertilizer industry needs nitrogen, and oxygenerator develops into can produce oxygen and nitrogen simultaneously, renames as air separation equipment.
Natural gas is a kind of high-grade energy, has the calorific value height, clean, characteristics such as Air is little, its Main Ingredients and Appearance is a methane, for the ease of transporting its liquefaction condensing temperature) generally at-150 ℃~-161 ℃, become liquefied natural gas LNG), be transported to behind the destination in order to utilize and to need its vaporization, can produce a large amount of colds during vaporization, 0.1Mpa under the cold energy that discharged during from-161 ℃ of re-heats to 27 ℃ of LNG be about 950KJ/kg, 8.0Mpa under the cold energy that discharged during from-161 ℃ of re-heats to 27 ℃ of NG be about 830KJ/kg, LNG contains huge high-quality cold energy, will be great waste if do not recycle.The mode of LNG cold energy use at present has cold energy generation, low-temperature grinding old tire, produces the full liquid air separation unit of liquid oxygen, liquid nitrogen, liquid argon.According to the low temperature cold principle utilized of low temperature as far as possible, full liquid air separation unit is LNG cold energy use the most rational the most effective a kind of mode of utilizing.
Liquid oxygen, liquid nitrogen, the liquid argon product of full liquid air separation unit production are widely used in fields such as metallurgy, petrochemical industry, machinery, chemical fertilizer, glass, military project, food, medical treatment, but traditional conventional empty energy consumption of dividing is big, produces 1Nm
3Fluid product needs the energy consumption of 1.05-1.25kwh, utilizes the air separation unit of LNG cold energy to produce 1Nm
3The fluid product energy consumption reduces more than 50%.
Summary of the invention
At the deficiencies in the prior art, the invention provides a kind of cryogenic energy utilization rate height, energy-conserving and environment-protective, high efficiency, full-liquid air separation device that utilizes cold energy of liquefied natural gas and method that safety coefficient is high.
Technical scheme of the present invention is achieved in that a kind of full-liquid air separation device that utilizes the liquified natural gas cold energy, comprise: self-cleaning air filter AF, the air compressor TC1 that is connected with self-cleaning air filter AF, the aerial cooler E5 that is connected with air compressor TC1, the purification system that is connected with aerial cooler E5, the main heat exchanger E2 that is connected with purification system by the first raw air pipeline, the second raw air pipeline that is connected with the first raw air pipeline, the following tower C1 that is connected with the second raw air pipeline, also pass through the last tower C2 that is connected behind the subcooler E3 with following tower C1 by pipeline, be positioned at the first condenser/evaporator K1 of tower C2 bottom, the nitrogen circulating system that is connected with following tower C1, and the argon gas fractionating system that is connected with last tower C2, described tower C1 down is provided with liquid nitrogen fraction, the lean solution sky is taken out mouth, subcooler E3 is provided with liquid nitrogen fraction passage and the empty passage of lean solution, last tower C2 is provided with liquid nitrogen fraction, the empty import of lean solution, the liquid nitrogen fraction passage is connected with last tower C2 and following tower C1 respectively by subcooler E3, and the empty passage of lean solution is connected with last tower C2 and following tower C1 respectively by subcooler E3.
Described nitrogen circulating system comprises high pressure heat exchanger E1, the delivering liquid natural gas is used to reclaim the liquid natural feed channel of liquified natural gas cold to high pressure heat exchanger E1, the low pressure recycle nitrogen compressor TC2 that is connected by first pipeline with following tower C1, the middle pressure cyclic nitrogen press TC3 that is connected with low pressure recycle nitrogen compressor TC2, the first gas-liquid separator SV1 that is connected by the 5th pipeline with low pressure recycle nitrogen compressor TC2 and middle pressure cyclic nitrogen press TC3, the second gas-liquid separator SV2 that is connected with the first gas-liquid separator SV1 by the 6th pipeline, the liquefier E7 that is connected with the first gas-liquid separator SV1 by second pipeline, wherein the first gas-liquid separator SV1 is connected with low pressure recycle nitrogen compressor TC2 by the 7th pipeline, the 5th pipeline is provided with the 8th pipeline that is connected with middle pressure cyclic nitrogen press TC3, and liquefier E7 is connected with low pressure recycle nitrogen compressor TC2 by the 3rd pipeline and the 4th pipeline respectively again.
Described purification system is connected with main heat exchanger E2 by the first raw air pipeline, and the first raw air pipeline is connected with liquefier E7 after passing main heat exchanger E2, and liquefier E7 is connected with following tower C1 by the liquid air pipeline.
The pressure of the natural gas in the described liquid natural feed channel 26 is 0.2Mpa-10.0Mpa.
A kind of full liquia air separation method that utilizes cold energy of liquefied natural gas, its method is as follows:
1) after raw air filters dust impurity through self-cleaning air filter AF, enter air compressor TC1 and be compressed to 0.52Mpa, cooled to 2 ℃-10 ℃ by refrigerant glycol water or fluorine Lyons, enter purification system then and remove impurity such as airborne moisture content, carbon dioxide, raw air after the purification goes main heat exchanger E2 heat exchange, be cooled to-167 ℃ to-170 ℃, a part of raw air enters down tower C1 through the second raw air pipeline; Another part raw air enters down tower C1 through liquefier E7 liquefaction for liquid air and through the liquid air pipeline, carries out caloic exchange, condensation evaporation at following tower C1, obtains nitrogen, liquid nitrogen, liquid nitrogen fraction, lean solution sky, oxygen-enriched liquid air successively;
2) oxygen-enriched liquid air described 1) is crossed the further rectifying of tower C2 in the cold deutomerite diffluence through subcooler E3, described 1) nitrogen that tower C1 top obtains under in removes condenser/evaporator K1, be condensed into liquid nitrogen, the conduct of part liquid nitrogen is the phegma of tower down, another part liquid nitrogen is crossed through subcooler E3 and is gone the further rectifying of tower C2, described 1 after cold) in the liquid nitrogen fraction that obtains of tower C1, lean solution sky are crossed through subcooler E3 by liquid nitrogen fraction passage, the empty passage of lean solution respectively and are gone tower C2 to participate in further rectifying after cold down;
When gas nitrogen is condensed into liquid nitrogen in condenser/evaporator K1,1) liquid oxygen among the last tower C2 is evaporated the rising gas as last tower C2, and phegma liquid nitrogen, oxygen-enriched liquid air conduct heat between filler, mass transfer, oxygen, nitrogen separate, last tower C2 bottom obtains highly purified liquid oxygen output ice chest I, it is that 8%-12% argon fraction is sent into argon producing system that last tower C2 middle part obtains volume ratio, produces smart argon and exports ice chest I, and the nitrogen at last tower C2 top is cooling box I after subcooler E3, main heat exchanger E2 re-heat;
3) with 1), 2) in remove main heat exchanger E2 after down the nitrogen that obtains of tower C1 top the 3rd pipeline of extracting a part of nitrogen that a part vaporizes out in first pipeline and output liquefier E7 merges, with first raw air pipeline heat exchange intensification back cooling box I, remove ice chest II then, extract out after in high pressure heat exchanger E1, being cooled to-120 ℃ to-126 ℃, send into low pressure recycle nitrogen compressor TC2 by liquified natural gas; Another part nitrogen of vaporizing among the liquefier E7 by the 4th pipeline after high pressure heat exchanger E1 is warmed up to-120 ℃ to-126 ℃, send into low pressure recycle nitrogen compressor TC2, the first gas-liquid separator SV1 separated nitrogen is also extracted out after high pressure heat exchanger E1 is warmed up to-120 ℃-126 ℃, send into low pressure recycle nitrogen compressor TC2, extract out after after low pressure recycle nitrogen compressor TC2 supercharging, returning high pressure heat exchanger E1 and being cooled to-120 ℃ to-126 ℃ once more go in pressure cyclic nitrogen press TC3, return heat exchanger E1 after the supercharging, reclaim the cold of liquefied natural gas, liquefaction is liquid nitrogen, the part throttling of the liquid nitrogen that is liquefied after heat exchanger E1 extract out after being warmed up to-120 ℃ to-126 ℃ go in pressure cyclic nitrogen press TC3, the residue liquid nitrogen advances the first gas-liquid separator SV1, a liquid nitrogen part of separating is removed liquefier E7 liquefied air through second pipeline, self is evaporated to nitrogen, another part liquid nitrogen removes the second gas-liquid separator SV2, liquid after the separation is sent as product, and gas is through heat exchanger E1 re-heat cooling box II;
4) the ducted liquified natural gas of liquified natural gas described 3) in high pressure heat exchanger E1 by re-heat, from the liquid natural feed channel at high pressure heat exchanger E1 middle part, extract a part of natural gas out and remove heat exchanger E4 cooling glycol water or freon, remainder is extracted out with after the merging of the natural gas after the heat exchanger E4 re-heat from high pressure heat exchanger E1 is terminal, finally obtain the sky hot gas more than 2 ℃, the refrigerant that is cooled goes the compressed air of air compressor machine intercooler E6 and aftercooler E5 cooling air compressor TC1 to arrive to 2 ℃-10 ℃, improve the efficient of air compressor TC1, reduce air compressor TC1 energy consumption.
Described 3) tower C1 top is extracted a part of nitrogen out and remove main heat exchanger E2 after first pipeline and the 3rd pipeline of exporting a part of nitrogen of vaporizing among the liquefier E7 is merged under in, with first raw air pipeline heat exchange intensification back cooling box I, remove ice chest II then, in high pressure heat exchanger E1, after-120 ℃-126 ℃, extracted out, send into low pressure nitrogen press TC2 by the liquified natural gas tube-cooled; Another part nitrogen of vaporizing among the liquefier E7 by the 4th pipeline after high pressure heat exchanger E1 is warmed up to-120 ℃-126 ℃, send into low pressure nitrogen press TC2, the first gas-liquid separator SV1 separated nitrogen is also extracted out after high pressure heat exchanger E1 is warmed up to-120 ℃-126 ℃ by the 7th pipeline, send into low pressure nitrogen press TC2, after low-temp low-pressure cyclic nitrogen press TC2 supercharging, return high pressure heat exchanger E1 cooling, extract out after being cooled to-120 ℃-126 ℃ once more and remove the middle cyclic nitrogen press TC3 that presses, return heat exchanger E1 after the supercharging, reclaim the cold of liquified natural gas, liquefaction is liquid nitrogen, a liquid nitrogen part that is liquefied through the 8th pipeline throttling after heat exchanger E1 extract out after being warmed up to-120 ℃-126 ℃ go in pressure cyclic nitrogen press TC3, the residue liquid nitrogen advances the first gas-liquid separator SV1 by the 5th pipeline, a liquid nitrogen part of separating is removed liquefier E7 liquefied air through second pipeline, self is evaporated to nitrogen, another part liquid nitrogen removes the second gas-liquid separator SV2 through the 6th pipeline, liquid is sent as product through the liquid nitrogen output channel, and gas passes through the 9th pipeline through heat exchanger E1 re-heat cooling box II.
The present invention has following good effect: the present invention takes out liquid nitrogen fraction, lean solution sky by following tower, makes air separation unit not reduce recovery rate because of the liquefaction of part material air; Liquefy in high pressure heat exchanger the low temperature cold recovery of LNG by circulating nitrogen gas, glycol water (or freon) is with the high temperature cold recovery, and the LNG cold energy utilizes stage by stage, compares with traditional full liquid air separation unit and can reduce power consumption and water consumption significantly; Liquid nitrogen passes to fractionating column system with air liquefaction with cold by liquefier, has stopped the leakage of methane to fractionating system, makes separator safe; LNG progressively heats up in high pressure heat exchanger and gasifies, the low temperature cold is transferred to nitrogen, but re-heat can not be used for its high temperature cold recovery the middle cooling and the final stage cooling of air compressor by suitable refrigerant to normal temperature, improve the efficient of air compressor machine machine, energy-saving and cost-reducing.
Description of drawings
Fig. 1 is a structural representation of the present invention.
The specific embodiment
As shown in Figure 1, a kind of full-liquid air separation device that utilizes the liquified natural gas cold energy, comprise: self-cleaning air filter AF, the air compressor TC1 that is connected with self-cleaning air filter AF, the aerial cooler E5 that is connected with air compressor TC1, the purification system that is connected with aerial cooler E5, the main heat exchanger E2 that is connected with purification system by the first raw air pipeline 1, the second raw air pipeline 2 that is connected with the first raw air pipeline 1, the following tower C1 that is connected with the second raw air pipeline 2, also pass through the last tower C2 that is connected behind the subcooler E3 with following tower C1 by pipeline, be positioned at the first condenser/evaporator K1 of tower C2 bottom, the nitrogen circulating system that is connected with following tower C1, and the argon gas fractionating system that is connected with last tower C2, described tower C1 down is provided with liquid nitrogen fraction, the lean solution sky is taken out mouth, subcooler E3 is provided with liquid nitrogen fraction passage 6 and the empty passage 7 of lean solution, last tower C2 is provided with liquid nitrogen fraction, the empty import of lean solution, liquid nitrogen fraction passage 6 is connected with last tower C2 and following tower C1 respectively by pipeline, and the empty passage 7 of lean solution is connected with last tower C2 and following tower C1 respectively by pipeline.
Described nitrogen circulating system comprises high pressure heat exchanger E1, the delivering liquid natural gas is used to reclaim the liquid natural feed channel 26 of liquified natural gas cold to high pressure heat exchanger E1, the low pressure recycle nitrogen compressor TC2 that is connected by first pipeline 13 with following tower C1, the middle pressure cyclic nitrogen press TC3 that is connected with low pressure recycle nitrogen compressor TC2, the first gas-liquid separator SV1 that is connected by the 5th pipeline 17 with low pressure recycle nitrogen compressor TC2 and middle pressure cyclic nitrogen press TC3, the second gas-liquid separator SV2 that is connected with the first gas-liquid separator SV1 by the 6th pipeline 20, the liquefier E7 that is connected with the first gas-liquid separator SV1 by second pipeline 19, wherein the first gas-liquid separator SV1 is connected with low pressure recycle nitrogen compressor TC2 by the 7th pipeline 18, the 5th pipeline 17 is provided with the 8th pipeline 16 that is connected with middle pressure cyclic nitrogen press TC3, and liquefier E7 is connected with low pressure recycle nitrogen compressor TC2 by the 3rd pipeline 14 and the 4th pipeline 15 respectively again.
Described purification system is connected with main heat exchanger E2 by the first raw air pipeline 1, and the first raw air pipeline 1 is connected with liquefier E7 after passing main heat exchanger E2, and liquefier E7 is connected with following tower C1 by liquid air pipeline 3.
The pressure of the natural gas in the described liquid natural feed channel 26 is 0.2Mpa-10.0Mpa.
A kind of full liquia air separation method that utilizes cold energy of liquefied natural gas, its method is as follows:
1) after raw air filters dust impurity through self-cleaning air filter AF, enter air compressor TC1 and be compressed to 0.52Mpa, cooled to 2 ℃-10 ℃ by refrigerant glycol water (or fluorine Lyons), enter purification system then and remove impurity such as airborne moisture content, carbon dioxide, raw air after the purification goes main heat exchanger E2 heat exchange, be cooled to-167 ℃ to-170 ℃, a part of raw air enters down tower C1 through the second raw air pipeline 2; Another part raw air enters down tower C1 through liquefier E7 liquefaction for liquid air and through liquid air pipeline 3, carries out caloic exchange, condensation evaporation at following tower C1, obtains nitrogen, liquid nitrogen, liquid nitrogen fraction, lean solution sky, oxygen-enriched liquid air successively;
2) oxygen-enriched liquid air described 1) is crossed the further rectifying of tower C2 in the cold deutomerite diffluence through subcooler E3, described 1) nitrogen that tower C1 top obtains under in removes condenser/evaporator K1, be condensed into liquid nitrogen, the conduct of part liquid nitrogen is the phegma of tower down, another part liquid nitrogen is crossed through subcooler E3 and is gone the further rectifying of tower C2, described 1 after cold) in the liquid nitrogen fraction that obtains of tower C1, lean solution sky are crossed through subcooler E3 by liquid nitrogen fraction passage 6, the empty passage 7 of lean solution respectively and are gone tower C2 to participate in further rectifying after cold down;
When gas nitrogen is condensed into liquid nitrogen in condenser/evaporator K1,1) liquid oxygen among the last tower C2 is evaporated the rising gas as last tower C2, and phegma liquid nitrogen, oxygen-enriched liquid air conduct heat between filler, mass transfer, oxygen, nitrogen separate, last tower C2 bottom obtains highly purified liquid oxygen output ice chest I, it is that 8%-12% argon fraction is sent into argon producing system that last tower C2 middle part obtains volume ratio, produces smart argon and exports ice chest I, and the nitrogen at last tower C2 top is cooling box I after subcooler E3, main heat exchanger E2 re-heat;
3) with 1), 2) in remove main heat exchanger E2 after down the nitrogen that obtains of tower C1 top the 3rd pipeline 14 of extracting a part of nitrogen that a part vaporizes out in first pipeline 13 and output liquefier E7 merges, with the first raw air pipeline 1) heat exchange intensification back cooling box I, remove ice chest II then, extract out after in high pressure heat exchanger E1, being cooled to-120 ℃-126 ℃, send into low pressure nitrogen press TC2 by liquid natural feed channel 26; Another part nitrogen of vaporizing among the liquefier E7 by the 4th pipeline 15 after high pressure heat exchanger E1 is warmed up to-120 ℃-126 ℃, send into low pressure nitrogen press TC2, the first gas-liquid separator SV1 separated nitrogen is also extracted out after high pressure heat exchanger E1 is warmed up to-120 ℃-126 ℃ by the 7th pipeline 18, send into low pressure nitrogen press TC2, after low-temp low-pressure cyclic nitrogen press TC2 supercharging, return high pressure heat exchanger E1 cooling, extract out after being cooled to-120 ℃-126 ℃ once more and remove the middle cyclic nitrogen press TC3 that presses, return heat exchanger E1 after the supercharging, reclaim the cold of liquified natural gas, liquefaction is liquid nitrogen, a liquid nitrogen part that is liquefied through 16 throttlings of the 8th pipeline after heat exchanger E1 extract out after being warmed up to-120 ℃-126 ℃ go in pressure cyclic nitrogen press TC3, the residue liquid nitrogen advances the first gas-liquid separator SV1 by the 5th pipeline 17, a liquid nitrogen part of separating is removed liquefier E7 liquefied air through second pipeline 19, self is evaporated to nitrogen, another part liquid nitrogen removes the second gas-liquid separator SV2 through the 6th pipeline 20, liquid is sent as product through liquid nitrogen output channel 21, gas by the 9th pipeline 22 through heat exchanger E1 re-heat cooling box II.
4) liquified natural gas in the liquid natural feed channel 26 described 3) in high pressure heat exchanger E1 by re-heat, from the liquid natural feed channel 26 at high pressure heat exchanger E1 middle part, extract a part of natural gas via natural gas lateral 23 out and remove heat exchanger E4 cooling glycol water (or freon), remainder is extracted out with after the merging of the natural gas via after the heat exchanger E4 re-heat from high pressure heat exchanger E1 is terminal, after promptly merging with natural gas lateral 23, finally obtain the sky hot gas more than 2 ℃, the refrigerant that is cooled goes the compressed air of air press intercooler E6 and aftercooler E5 cooling air compressor TC1 to arrive to 2 ℃-10 ℃ by refrigerant conveyance conduit 25, improve the efficient of air compressor TC1, reduce air compressor TC1 energy consumption.
The present invention utilizes circulating nitrogen gas to recycle the LNG cold by heat exchanger, again air liquefaction is passed to space division system with cold, by suitable refrigerant cold is passed to air compression system.Utilize the cold energy of LNG to produce liquid oxygen, liquid nitrogen, liquid argon, and reduce power consumption more than 50% significantly, water consumes more than 90%.Transmit cold by raw air, avoid the leakage of methane toward piece-rate system, safe.Extract liquid nitrogen fraction, lean solution sky by following tower, tower reflux ratio in the increase makes air separation unit not reduce recovery rate because of the liquefaction of raw air.
The present invention is not limited to the above-mentioned specific embodiment; the above-mentioned specific embodiment only is schematic; be not restrictive; those of ordinary skill in the art is under enlightenment of the present invention; do not breaking away under the scope situation that aim of the present invention and claim protect; can also make a lot of forms, these all belong within protection scope of the present invention.