CN110877919A - Coal gasification black water heat recovery method and device - Google Patents
Coal gasification black water heat recovery method and device Download PDFInfo
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- CN110877919A CN110877919A CN201911324711.3A CN201911324711A CN110877919A CN 110877919 A CN110877919 A CN 110877919A CN 201911324711 A CN201911324711 A CN 201911324711A CN 110877919 A CN110877919 A CN 110877919A
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- 239000010866 blackwater Substances 0.000 title claims abstract description 86
- 238000002309 gasification Methods 0.000 title claims abstract description 53
- 239000003245 coal Substances 0.000 title claims abstract description 50
- 238000011084 recovery Methods 0.000 title claims abstract description 37
- 238000000034 method Methods 0.000 title claims abstract description 29
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 113
- 238000001704 evaporation Methods 0.000 claims abstract description 29
- 230000008020 evaporation Effects 0.000 claims abstract description 29
- 239000007788 liquid Substances 0.000 claims description 91
- 238000000926 separation method Methods 0.000 claims description 90
- 239000000498 cooling water Substances 0.000 claims description 14
- 230000005484 gravity Effects 0.000 claims description 4
- 239000000284 extract Substances 0.000 claims description 3
- 238000012546 transfer Methods 0.000 abstract description 10
- 230000006837 decompression Effects 0.000 abstract description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 239000003034 coal gas Substances 0.000 description 5
- 239000007787 solid Substances 0.000 description 4
- 238000012423 maintenance Methods 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 2
- 238000007701 flash-distillation Methods 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 238000005352 clarification Methods 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000010797 grey water Substances 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
- C02F1/06—Flash evaporation
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/10—Energy recovery
Abstract
The invention discloses a coal gasification black water heat recovery method and a coal gasification black water heat recovery device, wherein the recovery method comprises the following steps: the coal gasification black water is decompressed by a decompression pipe; carrying out secondary pressure reduction on the coal gasification black water subjected to pressure reduction by using a pressure reduction angle valve, and conveying the coal gasification black water to a first flash tank for flash evaporation to obtain first non-condensable gas and steam; conveying the first uncondensed gas and the steam to a humidifying tower, and carrying out countercurrent contact on the first uncondensed gas and the steam and low-temperature low-pressure circulating water from a second flash evaporator to realize heat exchange between the first uncondensed gas and the steam and the low-temperature low-pressure circulating water; the first uncondensed gas and steam reduced in the humidified tower are delivered to a first flash cooler. In the embodiment of the application, the first uncondensed gas and the steam obtained by the first flash tank directly enter the humidifying tower, and are subjected to countercurrent heat exchange with the once-heated low-temperature low-pressure circulating water in the humidifying tower, and the steam/water is in countercurrent direct contact, so that the heat transfer efficiency is improved; the mode of combining direct heat exchange and indirect heat exchange is adopted, and both the heat exchange efficiency and the equipment quantity are considered.
Description
The present application claims priority from the chinese patent office filed on 27/12/2018, chinese patent application No. 201811607283.0, the entire contents of which are incorporated herein by reference.
Technical Field
The invention relates to the field of heat recovery, in particular to a coal gasification black water heat recovery method and a coal gasification black water heat recovery device.
Background
The patent CN102336496A discloses a technical route for recovering flash heat by a method for treating and recycling grey water of a dry coal powder gasification device, wherein the technical route is designed in such a way that gasified black water directly enters a flash tank for primary flash after passing through a pressure reducing valve and a flow limiting element, meanwhile, process water enters the flash tank to wash flash steam, and the washed flash steam passes through a venturi tube, then enters a dehumidifier for heat exchange and cooling, then is further cooled by a cooler, and then is discharged to a torch; and after the liquid subjected to the primary flash evaporation passes through the secondary flash evaporation, the gas is cooled and discharged to a torch, and the liquid is further subjected to flash evaporation and then sent to a clarification tank.
The process technology effectively utilizes the heat coming out of the primary flash evaporation, and improves the recovery efficiency of the flash evaporation heat, but the technical route adopts a mode of reducing the pressure by a direct pressure reducing valve, so that the pressure reducing valve is seriously abraded due to high-pressure-difference operation, and the long-period operation of equipment is restricted; the venturi tube is adopted for gas-liquid mixing, so that scaling in the tube is easily caused; the secondary flash steam is cooled and separated by cooling water and then discharged to a torch, so that the heat of the secondary flash steam is not further utilized, and the consumption of the cooling water is increased.
The patent CN 1214091C-hydrocarbon is the hot recovery method of waste water containing slag in the raw materials gas apparatus for producing, disclose a hot water tower that adopts flash distillation-heat transfer integration, because dry pulverized coal gasification black water handling capacity is big, when leading to using this equipment to gasify black water and carry out the flash distillation and handle, will cause the equipment size huge, processing, the operation difficulty, simultaneously because all concentrate on hot water tower with key parts such as evaporation and heat transfer system in, equipment structure is complicated, in case the trouble, it is very big to overhaul the degree of difficulty.
Disclosure of Invention
The invention aims to provide a coal gasification black water heat recovery method and a coal gasification black water heat recovery device, and aims to solve the problems of low heat transfer efficiency and high overhauling difficulty in the prior art.
In a first aspect, the invention provides a coal gasification black water heat recovery method, which comprises the following steps:
reducing the pressure of the coal gasification black water to 2.0-3.5Mpa by using a pressure reducing pipe;
carrying out secondary pressure reduction on the coal gasification black water subjected to pressure reduction by using a pressure reduction angle valve, and conveying the coal gasification black water to a first flash tank for flash evaporation to obtain first non-condensable gas and steam, and first black water;
conveying the first non-condensable gas and the water vapor to a humidifying tower, and carrying out countercurrent contact with low-temperature low-pressure circulating water from a second flash evaporator to realize heat exchange between the first non-condensable gas and the water vapor and the low-temperature low-pressure circulating water, wherein the temperature of the low-temperature low-pressure circulating water is increased, and the temperature of the first non-condensable gas and the water vapor is reduced;
pressurizing the heated low-temperature low-pressure circulating water by a high-temperature circulating water pump to form high-temperature high-pressure circulating water;
conveying the first noncondensable water and the steam cooled in the humidifying tower to a first flash cooler, and after the first flash cooler exchanges heat with circulating cooling water and is cooled, allowing the first non-condensable water and the steam to enter a first gas-liquid separation tank for gas-liquid separation to obtain second noncondensable water and the steam and first condensate;
conveying the second uncondensed gas and steam separated from the first gas-liquid separation tank to a flare;
and conveying the condensate separated by the first gas-liquid separation tank to a settling tank.
Further, the recovery method further comprises:
the first black water is decompressed by a first flash angle valve, then is conveyed to a second flash tank, and is subjected to flash evaporation in the second flash tank to obtain third non-condensable gas and steam, and second black water;
conveying the third uncondensed gas and the steam to a second flash evaporator cooler for heat exchange with low-temperature low-pressure circulating water;
the second flash evaporation cooler heats the low-temperature low-pressure circulating water and then conveys the heated low-temperature low-pressure circulating water to a humidifying tower;
in the second flash evaporation cooler, the second uncondensed gas and the steam are cooled and then are conveyed to a third flash evaporation cooler, the second uncondensed gas and the steam exchange heat with circulating cooling water, and then the second uncondensed gas and the steam are conveyed to a third gas-liquid separation tank for gas-liquid separation, and fourth uncondensed gas and the steam and a second condensate are obtained through separation;
and conveying the fourth non-condensable gas and water vapor to a torch, and conveying the second condensate to a settling tank.
Further, the recovery method further comprises:
the second black water is decompressed by a second flash angle valve, then is conveyed to a third flash tank, and is flashed in the third flash tank to obtain flash steam and third black water;
the third flash tank extracts flash steam through a vacuum pump to control the vacuum degree, and the pressure is ensured to be between-50 and-25 KpaG;
conveying the flash steam to a fourth flash evaporator cooler, and exchanging heat with circulating cooling water to obtain cooled flash steam;
conveying the cooled flash steam to a third gas-liquid separation tank for gas-liquid separation to obtain noncondensable gas and third condensate;
conveying the non-condensable gas to a torch or a high-point discharge by using a flash vacuum pump arranged on a gas phase outlet pipeline at the top of the third gas-liquid separation tank; conveying the third condensate to a third settling tank;
and the third black water enters the settling tank by using a flash pump or in a gravity-fed manner.
Further, the pressure of the first flash tank is controlled by a control valve arranged on an outlet pipeline of the first gas-liquid separation tank, and the pressure is controlled to be 0.5-0.7 MpaG.
Further, the pressure of the second flash tank is controlled by a control valve arranged on an outlet pipeline of the second gas-liquid separation tank, and the pressure is controlled to be 0.15-0.35 MpaG.
In a second aspect, the invention provides a coal gasification black water heat recovery device, comprising: the system comprises a pressure reducing pipe, a pressure reducing angle valve, a first flash tank, a humidifying tower, a second flash cooler, a high-temperature circulating water pump, a first flash cooler, a first gas-liquid separation tank, a torch and a settling tank;
the pressure reducing pipe, the pressure reducing angle valve and the first inlet of the first flash tank are sequentially connected;
the first outlet of the first flash tank is connected with the first inlet of the humidifying tower;
the first outlet of the humidifying tower is connected with the first inlet of the first flash cooler;
a first outlet of the first flash cooler is connected with an inlet of the first gas-liquid separation tank;
the first outlet of the first gas-liquid separation tank is connected with the torch;
the second outlet of the first gas-liquid separation tank is connected with the settling tank;
the first outlet of the second flash cooler is connected with the second inlet of the humidifying tower;
and a second outlet of the humidifying tower is connected with the high-temperature circulating water pump.
Further, the apparatus further comprises: the system comprises a first flash angle valve, a second flash tank, a third flash cooler and a second gas-liquid separation tank;
a second outlet of the first flash tank is sequentially connected with a first flash angle valve and an inlet of the second flash tank;
the first outlet of the second flash tank is connected with the second inlet of the second flash cooler;
the second outlet of the second flash cooler is connected to the first inlet of the third flash cooler;
a first outlet of the third flash cooler is connected with an inlet of the second gas-liquid separation tank;
the first outlet of the second gas-liquid separation tank is connected with the torch;
and a second outlet of the second gas-liquid separation tank is connected with the settling tank.
Further, the apparatus further comprises: a second flash angle valve, a third flash tank, a fourth flash cooler, a vacuum pump, a third gas-liquid separation tank and a flash pump;
a second outlet of the second flash tank is connected with an inlet of the third flash tank through a second flash angle valve;
a first outlet of the third flash tank is connected to a first inlet of the fourth flash cooler;
a first outlet of the fourth flash cooler is connected with an inlet of the third gas-liquid separation tank;
the first outlet of the third gas-liquid separation tank is connected with the vacuum pump;
a second outlet of the third gas-liquid separation tank is connected with the settling tank;
and a second outlet of the third flash tank is connected with the settling tank through a flash pump.
Further, a control valve is arranged on the first outlet pipeline of the first gas-liquid separation tank.
Further, a control valve is arranged on the first outlet pipeline of the second gas-liquid separation tank.
According to the technical scheme, the coal gasification black water heat recovery method and the coal gasification black water heat recovery device provided by the invention comprise the following steps: reducing the pressure of the coal gasification black water to 2.0-3.5Mpa by using a pressure reducing pipe; carrying out secondary pressure reduction on the coal gasification black water subjected to pressure reduction by using a pressure reduction angle valve, and conveying the coal gasification black water to a first flash tank for flash evaporation to obtain first non-condensable gas and steam, and first black water; conveying the first non-condensable gas and the water vapor to a humidifying tower, and carrying out countercurrent contact with low-temperature low-pressure circulating water from a second flash evaporator to realize heat exchange between the first non-condensable gas and the water vapor and the low-temperature low-pressure circulating water, wherein the temperature of the low-temperature low-pressure circulating water is increased, and the temperature of the first non-condensable gas and the water vapor is reduced; pressurizing the heated low-temperature low-pressure circulating water by a high-temperature circulating water pump to form high-temperature high-pressure circulating water; conveying the first noncondensable water and the steam cooled in the humidifying tower to a first flash cooler, and after the first flash cooler exchanges heat with circulating cooling water and is cooled, allowing the first non-condensable water and the steam to enter a first gas-liquid separation tank for gas-liquid separation to obtain second noncondensable water and the steam and first condensate; conveying the second uncondensed gas and steam separated from the first gas-liquid separation tank to a flare; and conveying the condensate separated by the first gas-liquid separation tank to a settling tank. This application embodiment, the first noncondensable water and the steam that first flash tank obtained directly enter into humidifying tower, with the low temperature low pressure circulating water that has heated once in humidifying tower, carry out countercurrent flow heat transfer, steam/water countercurrent direct contact, improve heat transfer efficiency. The process target is realized by adopting the combination of direct heat exchange and indirect heat exchange, and the number of complex hot water towers is reduced. And the mode of independently performing flash evaporation and heat exchange is adopted, so that the difficulty in maintenance is reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a flow chart of a coal gasification black water heat recovery method provided by the invention;
fig. 2 is a schematic structural diagram of a coal gasification black water heat recovery device provided by the invention.
Illustration of the drawings: 1-a pressure reducing pipe, 2-a pressure reducing angle valve, 3-a first flash tank, 4-a humidifying tower, 5-a second flash cooler, 6-a high-temperature circulating water pump, 7-a first flash cooler, 8-a first gas-liquid separation tank, 9-a torch, 10-a settling tank, 11-a first flash angle valve, 12-a second flash tank, 13-a third flash cooler, 14-a second gas-liquid separation tank, 15-a second flash angle valve, 16-a third flash tank, 17-a fourth flash cooler, 18-a vacuum pump, 19-a third gas-liquid separation tank and 20-a flash pump.
Detailed Description
Referring to fig. 1, a coal gasification black water heat recovery method provided by an embodiment of the present invention is shown, and the recovery method includes:
s101, reducing the pressure of the coal gasification black water to 2.0-3.5Mpa by using a pressure reducing pipe;
specifically, the coal gas black water is high-temperature and high-pressure solid-containing black water from the bottom of the gasification furnace, the temperature of the coal gas black water is 220 ℃, and the pressure of the coal gas black water is 4.5 MPa. And the pressure of the coal gas black water is reduced by a pressure reducing valve, and the pressure is reduced to 2.0-3.5 Mpa.
Step S102, after the coal gasification black water subjected to pressure reduction is subjected to secondary pressure reduction by using a pressure reduction angle valve, conveying the coal gasification black water to a first flash tank for flash evaporation to obtain first non-condensable gas and steam, and the first black water;
specifically, the coal gasification black water decompressed in the decompression pipe is decompressed to 0.7Mpa again through a decompression angle valve, and enters a first flash tank for flash evaporation to obtain first non-condensable gas at 170 ℃ and steam.
This application embodiment, before getting into first flash tank, will coal gas black water step-down can reduce the preceding back pressure differential of flash valve like this, reduce wear.
Step S103, conveying the first non-condensable gas and the water vapor into a humidifying tower, and making the first non-condensable gas and the water vapor in countercurrent contact with low-temperature low-pressure circulating water from a second flash evaporation cooler to realize heat exchange between the first non-condensable gas and the low-temperature low-pressure circulating water, wherein the temperature of the low-temperature low-pressure circulating water is increased, and the temperature of the first non-condensable gas and the water vapor is reduced;
specifically, the first non-condensable gas and the steam are conveyed to a humidifying tower, and the first non-condensable gas and the steam are in direct countercurrent contact with low-temperature low-pressure circulating water from a second flash evaporator in the humidifying tower. The first non-condensable gas and the steam exchange heat with the low-temperature low-pressure circulating water. The temperature of the first non-condensable gas and the steam is reduced to below 170 ℃, and the low-temperature and low-pressure circulating water is heated to 140-160 ℃.
This application embodiment, the first noncondensable water and the steam that first flash tank obtained directly enter into humidifying tower, with the low temperature low pressure circulating water that has heated once in humidifying tower, carry out countercurrent flow heat transfer, steam/water countercurrent direct contact, improve heat transfer efficiency.
According to the embodiment of the application, the process target is jointly realized by adopting a form of combining direct heat exchange and indirect heat exchange, and the number of complex hot water towers is reduced. And the mode of independently performing flash evaporation and heat exchange is adopted, so that the difficulty in maintenance is reduced.
Step S104, pressurizing the heated low-temperature low-pressure circulating water by a high-temperature circulating water pump to form high-temperature high-pressure circulating water;
the low-temperature and low-pressure circulating water obtained in the humidifying tower after being heated is pressurized by a high-temperature circulating water pump to become high-temperature and high-pressure circulating water, and the high-temperature and high-pressure circulating water is sent to a gasification boundary zone to be used as process circulating water of the gasification boundary zone. The embodiments of the present application also provide a return line to control or maintain the system water balance.
Step S105, conveying the first noncondensable gas and the water vapor which are cooled in the humidifying tower to a first flash cooler, and after the first flash cooler exchanges heat with circulating cooling water and is cooled, allowing the first noncondensable gas and the water vapor to enter a first gas-liquid separation tank for gas-liquid separation to obtain second noncondensable gas and the water vapor and first condensate;
s106, conveying the second uncondensed gas and the steam separated from the first gas-liquid separation tank to a torch;
noncondensable water and steam that flash distillation goes out all carry out once circulating cooling water cooling before discharging to the torch in this application embodiment to will not congeal water and steam and further separate through the gas-liquid separation jar, increase and retrieve the condensate liquid measure.
And S107, conveying the condensate separated by the first gas-liquid separation tank to a settling tank.
And the first condensate separated by the first gas-liquid separation tank is sent to a settling tank for recycling.
Further, the recovery method further comprises:
the first black water is decompressed by a first flash angle valve, then is conveyed to a second flash tank, and is subjected to flash evaporation in the second flash tank to obtain third non-condensable gas and steam, and second black water;
specifically, the first black water contains more solids than the coal gasification black water. And after the pressure of the first black water is reduced, the first black water enters a second flash tank and is flashed in the second flash tank to obtain a third non-condensable gas and steam at 134 ℃, and the second black water. The second black water contains more solids than the first black water.
Conveying the third uncondensed gas and the steam to a second flash evaporator cooler for heat exchange with low-temperature low-pressure circulating water; and the third uncondensed gas and the steam exchange heat with low-temperature low-pressure circulating water outside the battery limits in a second flash evaporator, and the low-temperature low-pressure circulating water is heated to 106 ℃.
The second flash evaporation cooler heats the low-temperature low-pressure circulating water and then conveys the heated low-temperature low-pressure circulating water to a humidifying tower;
specifically, the heated low-temperature low-pressure circulating water is sent to a humidifying tower to exchange heat with the first uncondensed water and the steam.
In the second flash evaporation cooler, the second uncondensed gas and the steam are cooled and then are conveyed to a third flash evaporation cooler, the second uncondensed gas and the steam exchange heat with circulating cooling water, and then the second uncondensed gas and the steam are conveyed to a third gas-liquid separation tank for gas-liquid separation, and fourth uncondensed gas and the steam and a second condensate are obtained through separation;
and conveying the fourth non-condensable gas and water vapor to a torch, and conveying the second condensate to a settling tank.
Specifically, the separated second condensate is sent to a settling tank for recycling.
Further, the recovery method further comprises:
the second black water is decompressed by a second flash angle valve, then is conveyed to a third flash tank, and is flashed in the third flash tank to obtain flash steam and third black water;
the third flash tank extracts flash steam through a vacuum pump to control the vacuum degree, and the pressure is ensured to be between-50 and-25 KpaG;
conveying the flash steam to a fourth flash evaporator cooler, and exchanging heat with circulating cooling water to obtain cooled flash steam;
conveying the cooled flash steam to a third gas-liquid separation tank for gas-liquid separation to obtain noncondensable gas and third condensate;
conveying the non-condensable gas to a torch or a high-point discharge by using a flash vacuum pump arranged on a gas phase outlet pipeline at the top of the third gas-liquid separation tank; conveying the third condensate to a third settling tank;
and the third black water enters the settling tank by using a flash pump or in a gravity-fed manner.
Specifically, the third black water separated by the third flash tank contains more solids than the second black water, and the third black water enters the settling tank through a flash pump or in a gravity-fed manner and is clarified in the settling tank.
Further, the pressure of the first flash tank is controlled by a control valve arranged on an outlet pipeline of the first gas-liquid separation tank, and the pressure is controlled to be 0.5-0.7 MpaG.
Further, the pressure of the second flash tank is controlled by a control valve arranged on an outlet pipeline of the second gas-liquid separation tank, and the pressure is controlled to be 0.15-0.35 MpaG.
Referring to fig. 2, a coal gasification black water heat recovery device provided by an embodiment of the present invention is shown, and the device includes: the system comprises a pressure reducing pipe 1, a pressure reducing angle valve 2, a first flash tank 3, a humidifying tower 4, a second flash cooler 5, a high-temperature circulating water pump 6, a first flash cooler 7, a first gas-liquid separation tank 8, a torch 9 and a settling tank 10;
the pressure reducing pipe 1, the pressure reducing angle valve 2 and a first inlet of the first flash tank 3 are sequentially connected;
a first outlet of the first flash tank 3 is connected with a first inlet of the humidifying tower 4;
a first outlet of the humidifying tower 4 is connected with a first inlet of the first flash cooler 5;
a first outlet of the first flash cooler 5 is connected with an inlet of the first gas-liquid separation tank 8;
the first outlet of the first gas-liquid separation tank 8 is connected with the torch 9;
a second outlet of the first gas-liquid separation tank 8 is connected with the settling tank 10;
a first outlet of the second flash cooler 5 is connected with a second inlet of the humidifying tower 4;
and a second outlet of the humidifying tower 4 is connected with the high-temperature circulating water pump 6.
Further, referring again to fig. 2, the apparatus further includes: a first flash angle valve 11, a second flash tank 12, a third flash cooler 13 and a second gas-liquid separation tank 14;
a second outlet of the first flash tank 3 is sequentially connected with a first flash angle valve 11 and an inlet of a second flash tank 12;
a first outlet of the second flash tank 12 is connected to a second inlet of the second flash cooler 5;
the second outlet of the second flash cooler 5 is connected to the first inlet of the third flash cooler 13;
a first outlet of the third flash cooler 13 is connected with an inlet of the second gas-liquid separation tank 14;
a first outlet of the second gas-liquid separation tank 14 is connected with the flare 9;
a second outlet of the second knockout drum 14 is connected to the settling tank 10.
Further, referring again to fig. 2, the apparatus further includes: a second flash angle valve 15, a third flash tank 16, a fourth flash cooler 17, a vacuum pump 18, a third gas-liquid separation tank 19 and a flash pump 20;
a second outlet of the second flash tank 12 is connected to an inlet of the third flash tank 16 through a second flash angle valve 15;
a first outlet of the third flash tank 16 is connected to a first inlet of the fourth flash cooler 17;
a first outlet of the fourth flash cooler 17 is connected with an inlet of the third gas-liquid separation tank 19;
a first outlet of the third gas-liquid separation tank 19 is connected to the vacuum pump 18;
a second outlet of the third gas-liquid separation tank 19 is connected with the settling tank 10;
a second outlet of the third flash tank 16 is connected to the settling tank 10 by a flash pump 20.
Further, a control valve is arranged on the first outlet pipeline of the first gas-liquid separation tank 8.
Further, a control valve is provided on the first outlet line of the second gas-liquid separation tank 14.
According to the technical scheme, the coal gasification black water heat recovery method and the coal gasification black water heat recovery device provided by the invention comprise the following steps: reducing the pressure of the coal gasification black water to 2.0-3.5Mpa by using a pressure reducing pipe; carrying out secondary pressure reduction on the coal gasification black water subjected to pressure reduction by using a pressure reduction angle valve, and conveying the coal gasification black water to a first flash tank for flash evaporation to obtain first non-condensable gas and steam, and first black water; conveying the first non-condensable gas and the water vapor to a humidifying tower, and carrying out countercurrent contact with low-temperature low-pressure circulating water from a second flash evaporator to realize heat exchange between the first non-condensable gas and the water vapor and the low-temperature low-pressure circulating water, wherein the temperature of the low-temperature low-pressure circulating water is increased, and the temperature of the first non-condensable gas and the water vapor is reduced; pressurizing the heated low-temperature low-pressure circulating water by a high-temperature circulating water pump to form high-temperature high-pressure circulating water; conveying the first noncondensable water and the steam cooled in the humidifying tower to a first flash cooler, and after the first flash cooler exchanges heat with circulating cooling water and is cooled, allowing the first non-condensable water and the steam to enter a first gas-liquid separation tank for gas-liquid separation to obtain second noncondensable water and the steam and first condensate; conveying the second uncondensed gas and steam separated from the first gas-liquid separation tank to a flare; and conveying the condensate separated by the first gas-liquid separation tank to a settling tank. This application embodiment, the first noncondensable water and the steam that first flash tank obtained directly enter into humidifying tower, with the low temperature low pressure circulating water that has heated once in humidifying tower, carry out countercurrent flow heat transfer, steam/water countercurrent direct contact, improve heat transfer efficiency. The process target is realized by adopting the combination of direct heat exchange and indirect heat exchange, and the number of complex hot water towers is reduced. And the mode of independently performing flash evaporation and heat exchange is adopted, so that the difficulty in maintenance is reduced.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
It will be understood that the invention is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.
Claims (10)
1. A coal gasification black water heat recovery method is characterized by comprising the following steps:
reducing the pressure of the coal gasification black water to 2.0-3.5Mpa by using a pressure reducing pipe;
carrying out secondary pressure reduction on the coal gasification black water subjected to pressure reduction by using a pressure reduction angle valve, and conveying the coal gasification black water to a first flash tank for flash evaporation to obtain first non-condensable gas and steam, and first black water;
conveying the first non-condensable gas and the water vapor to a humidifying tower, and carrying out countercurrent contact with low-temperature low-pressure circulating water from a second flash evaporator to realize heat exchange between the first non-condensable gas and the water vapor and the low-temperature low-pressure circulating water, wherein the temperature of the low-temperature low-pressure circulating water is increased, and the temperature of the first non-condensable gas and the water vapor is reduced;
pressurizing the heated low-temperature low-pressure circulating water by a high-temperature circulating water pump to form high-temperature high-pressure circulating water;
conveying the first noncondensable water and the steam cooled in the humidifying tower to a first flash cooler, and after the first flash cooler exchanges heat with circulating cooling water and is cooled, allowing the first non-condensable water and the steam to enter a first gas-liquid separation tank for gas-liquid separation to obtain second noncondensable water and the steam and first condensate;
conveying the second uncondensed gas and steam separated from the first gas-liquid separation tank to a flare;
and conveying the condensate separated by the first gas-liquid separation tank to a settling tank.
2. The coal gasification black water heat recovery method according to claim 1, further comprising:
the first black water is decompressed by a first flash angle valve, then is conveyed to a second flash tank, and is subjected to flash evaporation in the second flash tank to obtain third non-condensable gas and steam, and second black water;
conveying the third uncondensed gas and the steam to a second flash evaporator cooler for heat exchange with low-temperature low-pressure circulating water;
the second flash evaporation cooler heats the low-temperature low-pressure circulating water and then conveys the heated low-temperature low-pressure circulating water to a humidifying tower;
in the second flash evaporation cooler, the second uncondensed gas and the steam are cooled and then are conveyed to a third flash evaporation cooler, the second uncondensed gas and the steam exchange heat with circulating cooling water, and then the second uncondensed gas and the steam are conveyed to a third gas-liquid separation tank for gas-liquid separation, and fourth uncondensed gas and the steam and a second condensate are obtained through separation;
and conveying the fourth non-condensable gas and water vapor to a torch, and conveying the second condensate to a settling tank.
3. The coal gasification black water heat recovery method according to claim 1, further comprising:
the second black water is decompressed by a second flash angle valve, then is conveyed to a third flash tank, and is flashed in the third flash tank to obtain flash steam and third black water;
the third flash tank extracts flash steam through a vacuum pump to control the vacuum degree, and the pressure is ensured to be between-50 and-25 KpaG;
conveying the flash steam to a fourth flash evaporator cooler, and exchanging heat with circulating cooling water to obtain cooled flash steam;
conveying the cooled flash steam to a third gas-liquid separation tank for gas-liquid separation to obtain noncondensable gas and third condensate;
conveying the non-condensable gas to a torch or a high-point discharge by using a flash vacuum pump arranged on a gas phase outlet pipeline at the top of the third gas-liquid separation tank; conveying the third condensate to a third settling tank;
and the third black water enters the settling tank by using a flash pump or in a gravity-fed manner.
4. The coal gasification black water heat recovery method according to claim 1, wherein the pressure of the first flash tank is controlled by a control valve arranged on an outlet pipeline of the first gas-liquid separation tank, and the pressure is controlled to be 0.5-0.7 MpaG.
5. The coal gasification black water heat recovery method according to claim 2, wherein the pressure of the second flash tank is controlled by a control valve arranged on an outlet pipeline of the second gas-liquid separation tank, and the pressure is controlled to be 0.15-0.35 MpaG.
6. A coal gasification black water heat recovery device, characterized in that the device comprises: the system comprises a pressure reducing pipe, a pressure reducing angle valve, a first flash tank, a humidifying tower, a second flash cooler, a high-temperature circulating water pump, a first flash cooler, a first gas-liquid separation tank, a torch and a settling tank;
the pressure reducing pipe, the pressure reducing angle valve and the first inlet of the first flash tank are sequentially connected;
the first outlet of the first flash tank is connected with the first inlet of the humidifying tower;
the first outlet of the humidifying tower is connected with the first inlet of the first flash cooler;
a first outlet of the first flash cooler is connected with an inlet of the first gas-liquid separation tank;
the first outlet of the first gas-liquid separation tank is connected with the torch;
the second outlet of the first gas-liquid separation tank is connected with the settling tank;
the first outlet of the second flash cooler is connected with the second inlet of the humidifying tower;
and a second outlet of the humidifying tower is connected with the high-temperature circulating water pump.
7. The coal gasification black water heat recovery apparatus of claim 6, further comprising: the system comprises a first flash angle valve, a second flash tank, a third flash cooler and a second gas-liquid separation tank;
a second outlet of the first flash tank is sequentially connected with a first flash angle valve and an inlet of the second flash tank;
the first outlet of the second flash tank is connected with the second inlet of the second flash cooler;
the second outlet of the second flash cooler is connected to the first inlet of the third flash cooler;
a first outlet of the third flash cooler is connected with an inlet of the second gas-liquid separation tank;
the first outlet of the second gas-liquid separation tank is connected with the torch;
and a second outlet of the second gas-liquid separation tank is connected with the settling tank.
8. The coal gasification black water heat recovery apparatus of claim 6, further comprising: a second flash angle valve, a third flash tank, a fourth flash cooler, a vacuum pump, a third gas-liquid separation tank and a flash pump;
a second outlet of the second flash tank is connected with an inlet of the third flash tank through a second flash angle valve;
a first outlet of the third flash tank is connected to a first inlet of the fourth flash cooler;
a first outlet of the fourth flash cooler is connected with an inlet of the third gas-liquid separation tank;
the first outlet of the third gas-liquid separation tank is connected with the vacuum pump;
a second outlet of the third gas-liquid separation tank is connected with the settling tank;
and a second outlet of the third flash tank is connected with the settling tank through a flash pump.
9. The coal gasification black water heat recovery device according to claim 6, wherein a control valve is arranged on the first outlet pipeline of the first gas-liquid separation tank.
10. The coal gasification black water heat recovery device according to claim 7, wherein a control valve is provided on the first outlet line of the second gas-liquid separation tank.
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| CN113060785A (en) * | 2021-03-17 | 2021-07-02 | 宁夏神耀科技有限责任公司 | Coal gasification flash distillation device and coal gasification flash distillation process |
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