CN112107875B

CN112107875B - Flash evaporation steam stripping cooling system and black water treatment process using same

Info

Publication number: CN112107875B
Application number: CN202011181565.6A
Authority: CN
Inventors: 张泽武; 胡余龙; 邹中华; 范登森; 郭智竑
Original assignee: SHANGHAI HUAYI ENGINEERING CO LTD
Current assignee: SHANGHAI HUAYI ENGINEERING CO LTD
Priority date: 2020-10-29
Filing date: 2020-10-29
Publication date: 2023-08-15
Anticipated expiration: 2040-10-29
Also published as: CN112107875A

Abstract

The invention provides a flash evaporation stripping cooling tower, which is sequentially provided with a flash evaporation chamber, a liquid phase residence chamber, a stripping chamber, a heat exchange chamber and a separation chamber from bottom to top; the stripping chamber is sequentially provided with a tray section, a liquid phase distributor and a gas phase distributor along the steam flowing direction, the tray section comprises a plurality of trays, the heat exchange chamber is internally provided with a heat exchanger section, and the heat exchanger section comprises a plurality of heat exchangers. The invention further provides a flash stripping cooling system. The invention also provides a black water treatment process. The flash evaporation stripping cooling system and the black water treatment process thereof provided by the invention have the advantages of equipment integration, simplified flow, reduced energy consumption, improved heat transfer effect, low-temperature grey water cooling, realization of graded utilization of the low-temperature grey water, saving of a large amount of circulating water and complete recycling of slag water.

Description

Flash evaporation steam stripping cooling system and black water treatment process using same

Technical Field

The invention belongs to the technical field of chemical industry, and relates to a flash evaporation stripping cooling system and a black water treatment process thereof.

Background

Raw coal gasification is an important measure for realizing comprehensive utilization of coal resources based on the basic national conditions of more coal and less oil in China. Coal gasification and coal chemical industry are important development and development directions for the development of chemical industry in China. Usually, raw coal is gasified in a gasification furnace after being prepared into pulverized coal or coal water slurry, and a large amount of black water is generated after the generated high-temperature gas (main components such as CO, CH4, CO2, H2 and the like) is chilled and washed. These black waters generally contain 0.01 to 2% of solid particles (mainly coal ash, cinder and incompletely reflected coal) at a temperature of about 150 to 250 ℃ and a pressure of 1.8 to 10 mpa. At this time, the black water is almost saturated. On the one hand, CO2, CH4, H2S, NH3 and other gases are also dissolved and entrained in the black water. These gases are flammable and explosive, toxic and harmful, and if not removed, not only corrode equipment, but also cause harm to the whole device; on the other hand, the black water pressure generated by the washing tower and the gasification furnace is not low, but the black water pressure contains solid particles and cannot be used for doing work by external expansion; thirdly, the black water temperature is not low, part of heat energy can be recovered, but engineering problems of abrasion, blockage, scaling and the like of solid particles are overcome, and the cost is quite high generally, and the benefit is limited.

Existing engineering solutions, such as CN110228830A, CN207498194U, CN207627955U, CN207828040U, CN209161731U, adopt a method of performing step-by-step flash evaporation by adopting a simple flash tank, so that heat is not recycled, and a large amount of precious water resources (mainly used as circulating cooling water) are consumed for cooling.

Texaco is one of foreign companies which enter the market of China earlier and popularize coal water slurry gasification. CN94117093.4 discloses a multistage flash evaporation technology, and energy recovery and process water recycling are realized through subsystems such as a three-stage flash evaporation system, a sedimentation and clarification system, an oxygen removal system and the like. Black water from a gasification and synthesis gas washing system is sent to a high-pressure flash tank after passing through a pressure reducing valve, part of the black water is changed into steam through flash evaporation and enters a stripping tower, process water from an deoxidization system is heated, tail gas is sent to a sulfur recovery unit after being cooled by a heat exchanger and separated by the high-flash separation tank, and condensed water separated by the high-flash separation tank is sent to the deoxidization system. And the black water flowing out from the bottom of the high-pressure flash tank is further flashed by the low-pressure flash tank and the vacuum flash tank, and the discharged water is sent to a black water sedimentation and clarification system. The black water is settled and clarified to become grey water, most of the grey water is deoxidized by an deoxidizing system and heated by a stripping tower and then is sent back to a gasification and synthesis gas washing system, and the other part of the grey water is cooled by a wastewater cooler and sent to a sewage treatment plant for balancing the salt dissolved in the system. And the steam at the outlet of the low-pressure flash tank is sent into an deoxidization system to perform deoxidization, and the steam at the outlet of the vacuum flash tank is cooled by a heat exchanger, separated by a vacuum pump and pumped by a vacuum pump and is discharged to the atmosphere. The technology has the advantages of more equipment, complex operation, more occupied land and larger equipment cost and construction investment cost. Is difficult for a general enterprise to bear.

In CN109485190a, a treatment method of black water produced by coal gasification and a gasification method of coal and a system thereof are disclosed, the technology is that on the basis of CN94117093.4, black water after flocculation treatment is settled, supernatant obtained by settlement is sequentially subjected to filtration treatment and electrodialysis treatment, the number of equipment is greatly increased, and the process is more complex.

The black water flash evaporation device disclosed in CN105056560A is mainly used for relieving steam, scouring and abrasion to equipment in the solid-containing black water flash evaporation process. The technology of the patent basically does not substantially improve the treatment effect, the energy-saving effect and the water-saving effect of the whole slag water treatment system.

CN205948388U discloses a tray type flash evaporation-heat exchange integrated device, which comprises a tower body, wherein a tower body partition plate is divided into a lower evaporation chamber and an upper hot water chamber, a tray is arranged in the tower body, and the tray is positioned in a heat exchange section of the hot water chamber. The method has good effects on the aspects of flash evaporation of black water, solid separation and the like. But it also has significant drawbacks: (1) The equipment only carries out single heat recovery, the temperature after preliminary flash evaporation is about 150-200 ℃, and the effect of recovering heat energy is limited; (2) The gas phase at the top of the tower of the equipment is required to be condensed by arranging a heat exchanger, and the heat exchanger is usually an ABS type floating head heat exchanger with a hook ring, so that the structure is complex and the manufacturing cost is high. (3) the vapor phase condensation of the apparatus requires a large amount of circulating water; coal gasification projects are generally uneconomical and environment-friendly in places with shortage of water resources such as northwest. (4) After condensation, the equipment is required to be provided with a gas-liquid separation tank for separation, and is complex in equipment and high in cost. (5) The tray of the device adopts a single overflow tray, the application effect is not ideal when the liquid phase flow is large, and the conditions such as flooding and the like are easy to occur. (6) The gas phase heat exchange part of the equipment has the phenomenon of low gas phase flow rate, and is suitable for a small-sized gasification device.

Meanwhile, the treatment process based on the equipment has a plurality of defects, such as CN110228830A, CN207498194U, CN207627955U, CN207828040U, CN209161731U and the like, is a simple flash evaporation-separation-cooling-separation process, and the main equipment of the treatment process is a high-pressure flash evaporation tank, a high-pressure flash evaporation primary heat exchanger, a high-pressure flash evaporation secondary heat exchanger and a high-pressure flash evaporation gas-liquid separation tank respectively; then a low-pressure flash evaporation process is carried out, and the equipment mainly comprises a low-pressure flash evaporation tank, a low-pressure flash evaporation condenser, a deaerator and the like; low pressure flash process: because the first 2 times of flash evaporation separation are not thorough, a 2-stage vacuum flash evaporation device is required to be arranged. The whole slag water treatment process is complex and complicated, equipment is huge, heat exchange equipment is more, the effective efficiency loss is large, the equipment efficiency is low, the occupied area is more, the manufacturing cost is high, and the like.

In addition, low temperature (opposite) grey water mostly adopts a series-dividing wall heat exchange process. The ash water is subjected to first heat exchange with the steam at the top of the low-pressure flash tank through an ash water pump, then subjected to second heat exchange with the steam at the top of the high-pressure flash tank in a heat exchanger, and finally pumped into a high-temperature high-pressure washing tower through a pump; the second heat exchange in the two heat exchanges is limited by the driving force, so the heat exchange is not thorough, and a heat exchanger is connected in series at the back. The heat exchange efficiency of the flow is relatively low.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a flash stripping cooling system and a treatment process for black water, which can treat black water generated in a coal gasification process by using the system, reduce the number of equipment used in the treatment process, reduce the occupied area of a device, save a considerable amount of cooling water, and realize complete recycling of slag water.

To achieve the above and other related objects, a first aspect of the present invention provides a flash stripping cooling tower, which is provided with a flash chamber, a liquid-phase residence chamber, a stripping chamber, a heat exchange chamber and a separation chamber from bottom to top in sequence; the stripping chamber is sequentially provided with a tray section, a liquid phase distributor and a gas phase distributor along the steam flowing direction, the tray section comprises a plurality of trays, the heat exchange chamber is internally provided with a heat exchanger section, and the heat exchanger section comprises a plurality of heat exchangers.

Preferably, the flash evaporation chamber is internally and sequentially provided with a cone section and an evaporation section from bottom to top, the cone section gradually increases from bottom to top, the bottom of the cone section is provided with a slag discharging pipe, the side wall of the cone section is provided with a black water outlet pipe, and the side wall of the evaporation section is provided with a black water inlet.

More preferably, the black water drain pipe penetrates through the side wall of the cone section, one end of the black water drain pipe is provided with a black water drain hole, the black water drain hole penetrates into the position of a vertical axis line in the cone section, and the other end of the black water drain pipe extends out of the cone section and is downward in opening.

Further preferably, the vertical distance between the black water outlet and the top of the cone section is 1/3-2/3 of the inner diameter of the top of the cone section.

More preferably, a black water outlet standby port is arranged on the side wall of the evaporation section.

Preferably, the liquid phase residence chamber is sequentially provided with a liquid phase residence section and a gas phase diameter section from bottom to top, and the gas phase diameter section gradually becomes smaller from bottom to top.

More preferably, the bottom of the liquid phase residence section is provided with a separator.

Further preferably, the isolation plate is a seal head.

Further preferably, a drain pipe is arranged on the isolation plate, and the drain pipe extends into the flash chamber and penetrates through the side wall of the flash chamber to form a drain port.

Most preferably, the liquid discharge pipe is provided with a plurality of straight pipe sections in the flash chamber, and the bending angle between every two adjacent straight pipe sections is 120-145 degrees.

More preferably, a plurality of liquid inlet pipes are arranged in the liquid phase residence section, and the liquid inlet pipes penetrate through the side wall of the liquid phase residence section to form a liquid inlet.

Further preferably, the lower end of the liquid inlet pipe extends to the bottom of the liquid phase residence section.

More preferably, a liquid outlet is arranged on the side wall of the liquid phase residence section.

More preferably, a gas phase pipe is arranged in the liquid phase stay section, the gas phase pipe is vertically arranged, the lower end of the gas phase pipe penetrates through the isolation plate, and a gas cap is arranged outside the upper end of the gas phase pipe.

More preferably, the ratio of the top surface diameter to the bottom surface diameter of the gas phase diameter section is 0.1 to 1:1, preferably 0.4 to 0.8:1.

preferably, the trays are arranged at a position perpendicular to the flow direction of the steam.

Preferably, the tray is a plate tray comprising at least 2 downcomers.

Preferably, a first silk screen demister is arranged in the gas-phase distributor.

Preferably, one end of the liquid phase distributor horizontally penetrates through the stripping chamber to form a grey water inlet.

Preferably, the heat exchanger is arranged in a position parallel to the steam flow direction.

Preferably, a cooling grey water inlet and a cooling grey water outlet are arranged on the side wall of the heat exchanger section.

More preferably, the cooling grey water outlet is located above or below the cooling grey water inlet.

More preferably, the cooling grey water inlet is provided in the middle of the side wall of the heat exchanger section.

More preferably, the cooling grey water inlet is provided with an erosion shield.

Preferably, the heat exchanger is a spiral plate type or a tube type heat exchanger.

More preferably, when the heat exchanger is a spiral plate type heat exchanger, a round header pipe is arranged in the center of the heat exchanger section, and one end of the round header pipe is communicated with the cooling ash water outlet through a pipeline.

Further preferably, the flow passage of the cold fluid in the heat exchanger is spiral from outside to inside, and the flow passage of the steam fluid in the heat exchanger is in the clearance of the spiral plate from bottom to top.

Further preferably, the gap between adjacent spiral plates in the heat exchanger is 2-28 mm.

More preferably, when the heat exchanger is a tube type heat exchanger, the tube diameter of a heat exchange tube in the tube type heat exchanger is 19-57 mm, the wall thickness of the heat exchange tube is 0.8-3.5 mm, the tube spacing is 25-65 mm, and the length of the heat exchange tube is 0.5-6 m.

Further preferably, the tube side flow rate of the heat exchange tube is 3-25 m/s.

More preferably, when the heat exchanger is a shell-and-tube heat exchanger, the number of passes of the heat exchange tube shell passes in the shell-and-tube heat exchanger is 1-4.

More preferably, when the heat exchanger is a shell-and-tube heat exchanger, a baffle plate is arranged on the side of the shell-and-tube heat exchanger, and the baffle plate is one selected from a single-bow type, a double-bow type, a three-bow type, a circular ring type, a circular defect type, a hole type baffle plate and a spiral type.

Further preferably, the rate of the circular defect of the baffle plate is 10-55%; the space between the baffle plates is 1/5-3/5 of the outer diameter of the heat exchanger section.

Further preferably, the shell side flow rate of the baffles is 1 to 3.5m.

Preferably, the upper end and the lower end of the heat exchanger in the heat exchanger section are detachably connected with the inner wall of the heat exchange chamber respectively.

Preferably, a second silk screen demister is arranged above the heat exchange chamber heat exchanger section.

Preferably, the top of the separation chamber is provided with an air outlet.

The second aspect of the invention provides a flash stripping cooling system, which comprises a first flash stripping cooling tower, a second flash stripping cooling tower, a vacuum flash tank, an ash water tank, a settling tank, a condenser and a vacuum flash separation tank;

the first flash steam stripping cooling tower, the second flash steam stripping cooling tower, the vacuum flash tank and the gray water tank are sequentially communicated along the black water input direction to form a black water passage; in the black water passage, the tank bottom of the vacuum flash tank is communicated with the ash water tank through a settling tank, and the tank top of the vacuum flash tank is communicated with the ash water tank through a condenser and a vacuum flash separation tank;

the ash water tank is respectively communicated with the first flash steam stripping cooling tower and the second flash steam stripping cooling tower along the ash water reflux direction to form an ash water reflux passage;

The first flash stripping cooling tower and the second flash stripping cooling tower form a condensed water loop along the flowing direction of condensed water.

Preferably, the first flash stripping cooling tower is a high pressure flash stripping cooling tower having a pressure of > 0.5MPaG and less than or equal to 2.0MPaG.

Preferably, the second flash stripping cooling tower is a low pressure flash stripping cooling tower, and the pressure of the low pressure flash stripping cooling tower is 0.01-0.5MPaG.

Preferably, the first flash stripping cooling tower is communicated with the gasification furnace and is used for inputting black water from the gasification furnace.

More preferably, the gasifier is in communication with the evaporator section of the flash chamber.

Preferably, the vacuum flash tank is communicated with the slag skimming pool through a pipeline.

Preferably, a mixer is arranged on a pipeline between the vacuum flash tank and the settling tank along the black water output direction.

Preferably, the condenser is arranged on the tank top of the vacuum flash tank.

Preferably, the vacuum flash separation tank is externally connected with a flash vacuum pump.

Preferably, an ash water pump unit and an air cooler are sequentially arranged on a pipeline between the ash water tank and the first flash steam stripping cooling tower along the ash water output direction, and the ash water pump unit is also communicated with the second flash steam stripping cooling tower through the pipeline.

More preferably, the grey water pump unit is selected from one of a single grey water pump or a double grey water pump.

Further preferably, when the ash water pump unit is a single ash water pump, a flow regulating valve is arranged on the single ash water pump.

Further preferably, when the ash water pump unit is a double ash water pump, the double ash water pumps are a high-pressure ash water pump and a low-pressure ash water pump respectively, the high-pressure ash water pump is arranged on a pipeline between the ash water tank and the first flash steam stripping cooling tower, and the low-pressure ash water pump is arranged on a pipeline between the ash water tank and the second flash steam stripping cooling tower.

More preferably, the ash water tank is respectively communicated with heat exchanger sections in heat exchange chambers of the first flash stripping cooling tower and the second flash stripping cooling tower.

Preferably, the first flash stripping cooling tower is respectively communicated with the conversion section and the synthesis gas washing tower and is used for inputting condensed water from the conversion section and outputting the circulated condensed water to the synthesis gas washing tower.

More preferably, the stripping chamber of the first flash stripping cooling tower is communicated with the conversion section, the liquid phase residence chamber of the first flash stripping cooling tower is communicated with the synthesis gas washing tower, a washing tower feed pump is arranged on a pipeline between the liquid phase residence chamber and the synthesis gas washing tower, an outlet of the washing tower feed pump is communicated with the synthesis gas washing tower, and an inlet of the washing tower feed pump is communicated with a liquid outlet of the liquid phase residence chamber of the first flash stripping cooling tower.

Preferably, the first flash stripping cooling tower is communicated with the ash water inlet of the stripping chamber in the second flash stripping cooling tower through the cooling ash water outlet of the heat exchange chamber, and is used for inputting the condensed water flowing through the heat exchange section in the heat exchange chamber into the second flash stripping cooling tower, and the second flash stripping cooling tower is communicated with the heat exchange chamber in the first flash stripping cooling tower through the liquid outlet of the liquid phase residence chamber and is used for refluxing the condensed water input into the second flash stripping cooling tower into the heat exchange section of the heat exchange chamber of the first flash stripping cooling tower.

More preferably, a flash stripping cooling tower feed pump is arranged on a pipeline between a liquid outlet of the liquid phase residence chamber of the second flash stripping cooling tower and a heat exchange chamber in the first flash stripping cooling tower.

More preferably, the cooling ash water inlet and the cooling ash water outlet of the second flash stripping cooling tower are externally connected with circulating cooling water to form a cooling loop.

Preferably, the first flash stripping cooling tower and the second flash stripping cooling tower are respectively communicated with the sulfur recovery device along the tail gas output direction.

A third aspect of the present invention provides the use of the flash stripping cooling tower described above and/or the flash stripping cooling system described above in the treatment of black water.

The fourth aspect of the invention provides a black water treatment process, which adopts the flash evaporation stripping cooling system and comprises the following steps:

1) Black water is input into a flash evaporation chamber of a first flash steam stripping cooling tower, ash water is input into a stripping chamber of the first flash steam stripping cooling tower, the black water forms first steam after being flashed in the flash evaporation chamber, the first steam flows upwards to enter the stripping chamber through a liquid-phase residence chamber to be mixed with the ash water, and is cooled after heat exchange in a heat exchange chamber, so that first tail gas is obtained and is sent to a sulfur recovery device for sulfur recovery;

2) The method comprises the steps of inputting black water slag water after flash evaporation into a flash evaporation chamber of a second flash evaporation stripping cooling tower from a flash evaporation chamber of a first flash evaporation stripping cooling tower, inputting ash water into a gas stripping chamber of the second flash evaporation stripping cooling tower, forming second steam after flash evaporation in the flash evaporation chamber, enabling the second steam to flow upwards, enter the gas stripping chamber through a liquid phase residence chamber, are mixed with the ash water, exchanging heat in a heat exchange chamber, cooling, and obtaining second tail gas to be sent to a sulfur recovery device for sulfur recovery;

3) And (3) inputting the black water slag water after flash evaporation into a vacuum flash evaporation tank from a flash evaporation chamber of a second flash evaporation steam stripping cooling tower to flash evaporation, condensing the formed flash evaporation gas and first flash evaporation residues by a condenser, inputting the condensed flash evaporation gas into a vacuum flash evaporation separation tank to separate to obtain non-condensable gas and second flash evaporation residues, evacuating the non-condensable gas, and enabling the first flash evaporation residues and the second flash evaporation residues to flow into an ash water tank to form ash water after passing through a settling tank, wherein the ash water respectively flows back into the first flash evaporation steam stripping cooling tower and the second flash evaporation steam stripping cooling tower.

Preferably, in step 1), 2) or 3), the flow rate of the greywater is 1.2-3.5 m/s.

Preferably, in step 1), the black water is fed from a gasifier quench chamber.

Preferably, in step 1), the grey water is fed from a synthesis gas scrubber and a grey water tank.

Preferably, in step 1), the black water and grey water are depressurized before being fed into the first flash stripping cooling tower.

Preferably, in step 1), the flash conditions of the first flash stripping cooling tower are: the flash evaporation temperature is 126-168 ℃; the flash pressure is 0.50-2.0MPaG.

Preferably, in the step 1), the heat exchange temperature of the heat exchange chamber is 80-125 ℃.

Preferably, in step 1), the cooling temperature is equal to or less than 60 ℃.

Preferably, in step 2), the greywater is fed from a greywater tank.

Preferably, in step 2), the black water is depressurized before being fed to the second flash stripping cooling tower.

Preferably, in step 2), the flash conditions of the second flash stripping cooling tower are: the flash evaporation temperature is 80-125 ℃; the flash pressure is 0-0.6MPaG.

Preferably, in the step 2), the heat exchange temperature of the heat exchange chamber is 80-125 ℃.

Preferably, in step 2), the cooling temperature is equal to or less than 60 ℃.

Preferably, in step 3), the black water is depressurized before being fed into a vacuum flash tank.

Preferably, in step 3), the flash conditions of the vacuum flash tank are: the flash evaporation temperature is 80-85 ℃; the flash pressure is-0.10 to-0.01 MPaG.

Preferably, in step 3), the condensing temperature of the condenser is 55-85 ℃.

Preferably, in the step 3), a polymeric flocculant is put into the settling tank, and the polymeric flocculant is a polyacrylamide flocculant.

Preferably, in the step 3), the greywater tank is charged with a dispersant, and the dispersant is one selected from sulfonate, naphthalene, humic acid, lignin, polyolefin, acrylic acid and their combinations.

More preferably, the dispersant is a sulfonic acid-carboxylic acid based dispersant.

Preferably, in step 3), the temperature of the grey water in the grey water tank is 55-85 ℃.

Preferably, in the step 3), the grey water is cooled by an air cooler and then flows back to the first flash steam extraction cooling tower, and the cooling temperature of the air cooler is 45-50 ℃.

Preferably, in step 3), the air cooler is used under one or more conditions selected from the following conditions, preferably 3 to 5 conditions:

a) The difference between the hot fluid outlet temperature and the air outlet temperature is more than 15 ℃;

b) The outlet temperature of the hot fluid is more than 50-60 ℃, and the allowable fluctuation range is more than 3-5 ℃;

C) The design inlet temperature of the air is less than 38 ℃;

d) The effective logarithmic average temperature difference is more than or equal to 40 ℃;

e) The coefficient of a heat transfer film of the hot fluid in the tube is less than 2300W/(m < 2 >. T);

f) The solidifying point of the hot fluid is less than 0 ℃;

g) The allowable pressure drop of the hot fluid at the pipe side is more than 100kPa, and the design pressure is more than or equal to l00kPa.

As described above, the flash evaporation stripping cooling system and the treatment process for black water thereof provided by the invention form structural types of a high-pressure flash evaporation stripping cooling tower and a low-pressure flash evaporation stripping cooling tower, and have the following beneficial effects:

(1) The flash stripping cooling system and the black water treatment process using the same provided by the invention have the advantages that after the novel flash stripping cooling tower is used, the operation range is enlarged, the novel flash stripping cooling system is suitable for a larger-scale gasification device, the whole black water treatment process is simplified, the occupied area of 2 heat exchangers and 2 flash separation tanks is reduced compared with the traditional process, the equipment use amount in the treatment process is reduced, the occupied area of the device is reduced, and the operation cost of the slag water treatment process is reduced.

(2) The flash evaporation stripping cooling system and the treatment process for black water thereof form 2-level cold fluid internal circulation and sleeve-level utilization, simplify the equipment, simplify the process, reduce the energy consumption, save a large amount of circulating water and realize the complete recycling of slag water.

(3) The invention provides a flash evaporation stripping cooling system and a black water treatment process thereof, which furthest utilize grey water after cooling. The high-temperature flash steam is subjected to heat exchange with the high-temperature flash steam of the high-pressure flash stripping tower cooling tower, and then enters the low-pressure flash stripping tower cooling tower to perform secondary heat exchange; the energy is greatly saved.

(4) According to the flash evaporation stripping cooling system and the black water treatment process thereof, the high-pressure flash evaporation stripping tower cooling tower does not need circulating water for cooling, but uses low-temperature grey water for cooling, so that the consumption of the circulating water is saved; the method has a particularly important significance in northwest areas where northwest water resources are scarce. The cleaner grey water is further cooled by the air cooler, so that energy sources are saved; when the temperature is lower in winter in the north, the air cooler can be cut out through a bypass of the air cooler, so that the operation cost is further saved.

(5) The flash evaporation steam stripping cooling system and the treatment process for black water provided by the invention have the advantage that the heat transfer effect of the novel flash evaporation steam stripping cooling tower is improved by at least 25% compared with that of a heat transfer and exchange device.

(6) The flash stripping cooling system and the black water treatment process thereof integrate the traditional external heat exchanger with complex external structure and high manufacturing cost into the flash stripping cooling tower, and apply the spiral plate heat exchanger with simple structure and high heat transfer efficiency, which is suitable for solid-liquid containing. The built-in heat exchanger can be segmented according to the process requirement; for example, low temperature liquids in the plant, which need to be warmed, can be sent again to the stripping cooling tower. The low-temperature grey water is used for cooling and heat exchanging in a high-pressure flash evaporation section; instead of the circulating water in the traditional process, and realizes the graded utilization of low-temperature grey water.

Drawings

Fig. 1 shows a schematic structure of a flash stripping cooling tower in the present invention.

Fig. 2 shows a schematic diagram of the flash stripping cooling system in the present invention.

Reference numerals

1. Flash chamber

11. Cone segment

111. Slag discharging pipe

112. Black water drain pipe

113. Black water outlet

12. Evaporation section

121. Black water inlet

122. Black water liquid outlet spare port

2. Liquid phase residence chamber

21. Liquid phase stay section

211. Partition board

212. Liquid discharge pipe

213. Liquid outlet

214. Straight pipe section

215. Liquid inlet pipe

216. Liquid inlet

217. Liquid outlet

218. Gas phase pipe

219. Air cap

22. Gas phase reducing section

3. Stripping chamber

31. Tray section

311. Tray

312. Downcomer pipe

32. Liquid phase distributor

321. Ash water inlet

33. Gas phase distributor

331. First silk screen foam remover

4. Heat exchange chamber

41. Heat exchanger section

411. Heat exchanger

412. Cooling ash water inlet

413. Cooling grey water outlet

414. Second silk screen foam remover

5. Separation chamber

51. Air outlet

S1 first flash steam stripping cooling tower

S2 second flash steam stripping cooling tower

S3 vacuum flash tank

S4 ash water tank

S5 settling tank

S6 condenser

S7 vacuum flash evaporation separation tank

S8 gasifier

S9 black water slag fishing pool

S10 mixer

S11 flash evaporation vacuum pump

S12 high-pressure grey water pump

S13 air cooler

S14 low-pressure grey water pump

S15 conversion section

S16 synthetic gas washing tower

S17 washing tower feed pump

S18 flash evaporation stripping cooling tower feed pump

S19 sulfur recovery device

Detailed Description

The invention is further illustrated below in connection with specific examples, which are to be understood as being illustrative of the invention and not limiting the scope of the invention.

Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.

It should be understood that the process equipment or devices not specifically identified in the examples below are all conventional in the art; all pressure values and ranges refer to relative pressures.

Furthermore, it is to be understood that the reference to one or more method steps in this disclosure does not exclude the presence of other method steps before or after the combination step or the insertion of other method steps between these explicitly mentioned steps, unless otherwise indicated; it should also be understood that the combined connection between one or more devices/means mentioned in the present invention does not exclude that other devices/means may also be present before and after the combined device/means or that other devices/means may also be interposed between these two explicitly mentioned devices/means, unless otherwise indicated. Moreover, unless otherwise indicated, the numbering of the method steps is merely a convenient tool for identifying the method steps and is not intended to limit the order of arrangement of the method steps or to limit the scope of the invention in which the invention may be practiced, as such changes or modifications in their relative relationships may be regarded as within the scope of the invention without substantial modification to the technical matter.

The first aspect of the invention provides a flash evaporation stripping cooling tower, as shown in fig. 1, a flash evaporation chamber 1, a liquid phase residence chamber 2, a stripping chamber 3, a heat exchange chamber 4 and a separation chamber 5 are sequentially arranged from bottom to top; the stripping chamber 3 is sequentially provided with a tray section 31, a liquid phase distributor 32 and a gas phase distributor 33 along the steam flow direction, the tray section 31 comprises a plurality of trays 311, the heat exchange chamber 4 is internally provided with a heat exchanger section 41, and the heat exchanger section 41 comprises a plurality of heat exchangers 411.

In the flash stripping cooling tower provided by the invention, as shown in fig. 1, a cone section 11 and an evaporation section 12 are sequentially arranged in the flash chamber 1 from bottom to top, the cone section 11 gradually increases in width from bottom to top, a slag discharging pipe 111 is arranged at the bottom of the cone section 11, a black water outlet pipe 112 is arranged on the side wall of the cone section 11, and a black water inlet 121 is arranged on the side wall of the evaporation section 12.

In a preferred embodiment, as shown in fig. 1, the black water outlet pipe 112 penetrates through the side wall of the cone section 11, one end of the black water outlet pipe 112 is provided with a black water outlet 113, the black water outlet 113 extends deep into the cone section 11 at the position of the vertical axis line, and the other end of the black water outlet pipe 112 extends out of the cone section 11 and is opened downwards.

In a further preferred embodiment, as shown in FIG. 1, the vertical distance between the black water outlet 113 and the top of the cone segment 11 is 1/3-2/3 of the inner diameter of the top of the cone segment 11.

In a preferred embodiment, as shown in fig. 1, a black water outlet 122 is provided on the side wall of the evaporation section 12.

In the flash stripping cooling tower provided by the invention, as shown in fig. 1, a liquid-phase residence section 21 and a gas-phase diameter-reducing section 22 are sequentially arranged in the liquid-phase residence chamber 2 from bottom to top, and the width of the gas-phase diameter-reducing section 22 is gradually reduced from bottom to top.

In a preferred embodiment, as shown in fig. 1, the bottom of the liquid phase residence section 21 is provided with a separator 211. The separation plate 211 is used for separating the flash chamber 1 from the liquid-phase residence chamber 2.

In a further preferred embodiment, as shown in fig. 1, the spacer 211 is a closure head. Specifically, the seal head is a seal head protruding downwards, and the shape of the seal head is hemispherical or elliptic. The seal head can be cancelled according to the operation condition.

In a further preferred embodiment, as shown in fig. 1, a drain pipe 212 is provided on the partition 211, and the drain pipe 212 extends into the flash chamber 1 and forms a drain 213 through a side wall of the flash chamber 1. The drain 212 is used to drain the contaminated liquid in the liquid-phase retention chamber 2.

Further, as shown in fig. 1, the liquid discharge pipe 212 is formed as a plurality of straight pipe sections 214 in the flash chamber 1, and the bending angle between the adjacent straight pipe sections 214 is 120 ° to 145 °. The angle of the bend of the straight tube section 214 may prevent blockage of the drain 212. The straight pipe sections 214 are circular arc-shaped, and cannot have any corner angle, so that the drain pipe 212 is blocked.

In a preferred embodiment, as shown in fig. 1, a plurality of liquid inlet pipes 215 are disposed in the liquid phase residence section 21, and the liquid inlet pipes 215 penetrate through the side wall of the liquid phase residence section 21 to form a liquid inlet 216.

In a further preferred embodiment, as shown in fig. 1, the lower end of the liquid inlet pipe 215 extends to the bottom of the liquid phase residence section 21. Specifically, the lower end of the liquid inlet pipe 215 extends to a tangent line of the partition plate 211. Is used for forming a liquid seal and preventing air leakage.

In a preferred embodiment, as shown in fig. 1, the liquid phase residence section 21 has a liquid outlet 217 on the side wall. The outlet 217 is used to deliver black water to the syngas scrubber S16 via the scrubber feed pump S17.

In a preferred embodiment, as shown in fig. 1, a gas-phase tube 218 is disposed in the liquid-phase residence section 21, the gas-phase tube 218 is disposed vertically, the lower end of the gas-phase tube 218 penetrates through the partition plate 211, and a gas cap 219 is disposed outside the upper end of the gas-phase tube 218.

In a further preferred embodiment, as shown in fig. 1, the air cap 219 is a standard semi-sealing head, and the shape of the air cap 219 is selected from one of a cone shape, a square shape, and a circular shape.

In a preferred embodiment, as shown in FIG. 1, the ratio of the top surface diameter to the bottom surface diameter of the gas phase diameter section 22 is 0.1 to 1:1, preferably 0.4 to 0.8:1. the gas phase diameter section 22 improves the gas phase flow rate and improves the effects of gas-liquid phase heat exchange and mass transfer.

In the flash stripping cooling tower provided by the invention, as shown in fig. 1, the tray 311 is arranged at a position perpendicular to the flow direction of steam.

In a flash stripping cooling tower provided by the present invention, as shown in fig. 1, the tray 311 is a plate tray, and the tray 311 includes at least 2 downcomers 312.

In a preferred embodiment, the plate trays are double flooded plate trays. The double overflow plate type tray has better heat exchange performance and operation elastic range, and meanwhile, the occurrence of flooding is reduced.

In a further preferred embodiment, the dual tray deck tray is a dual tray overflow solid valve tray. The tray 311 is made of 316L, has a diameter phi of 2800mm, a plate thickness of 4mm, a plate interval of 600mm, an aperture ratio of 13% and a bubbling area of 47.7%.

In a preferred embodiment, the downcomer 312 has a top width of 600mm, a bottom width of 475mm, a bottom gap of 70mm, an outlet weir height of 70mm, and a weir length of 2750mm.

In one flash stripping cooling tower provided by the present invention, as shown in fig. 1, the liquid phase distributor 32 is a conventionally used liquid phase distributor, i.e., a spray thrower.

In a preferred embodiment, the pattern of the liquid phase distributor 32 includes, but is not limited to, a bent tube, a notched, a porous calandria, a multiple empty tray, a distribution tray, a trough distributor.

In one flash stripping cooling tower provided by the present invention, as shown in fig. 1, the gas phase distributor 33 is a conventionally used gas phase distributor. In a preferred embodiment, the gas phase distributor 33 is a wire mesh distributor or a vane distributor.

In the flash stripping cooling tower provided by the invention, as shown in fig. 1, a first wire mesh demister 331 is arranged in the gas phase distributor 33.

In one flash stripping cooling tower provided by the invention, as shown in fig. 1, one end of the liquid phase distributor 32 horizontally penetrates through the stripping chamber 3 to form a grey water inlet 321.

In the flash stripping cooling tower provided by the invention, as shown in fig. 1, the heat exchanger 411 is arranged in a position parallel to the flow direction of steam.

In a flash stripping cooling tower provided by the invention, as shown in fig. 1, a cooling ash water inlet 412 and a cooling ash water outlet 413 are arranged on the side wall of the heat exchanger section 41.

In a preferred embodiment, the cooling grey water outlet 413 is located above or below the cooling grey water inlet 412.

In a preferred embodiment, the cooling grey water inlet 412 is provided in the middle of the side wall of the heat exchanger section 41.

In a preferred embodiment, the cooling grey water inlet 412 is provided with an erosion shield. Specifically, the anti-erosion plate is a conventionally used anti-erosion plate, preferably an anti-erosion veneer or an anti-erosion ring plate.

In one flash stripping cooling tower provided by the present invention, as shown in fig. 1, the heat exchanger 411 is a spiral plate type or tube type heat exchanger, preferably a spiral plate type heat exchanger.

The spiral plate type or tube type heat exchanger has simple structure and low manufacturing cost, and can replace the existing floating head type heat exchanger with the hook ring, which has high manufacturing cost and complex structure.

The heat exchange area of the heat exchanger 411 is large enough, the wall thickness is thin enough, the cooling medium flow rate is larger than that of the original ABS type heat exchanger, and the heat transfer coefficient can be improved by 1.25-2.5 times.

The spiral plate on the spiral plate type heat exchanger and the tube nest on the tube nest type heat exchanger depend on the heat exchange amount and the requirement.

In a preferred embodiment, when the heat exchanger 411 is a spiral plate heat exchanger, the center of the heat exchanger section 41 is provided with a round header, and one end of the round header is communicated with the cooling ash water outlet 413 through a pipeline. The heat exchanger sections 41 may optionally be in series of multiple sections.

Further, the flow passage of the cold fluid in the heat exchanger 411 is spiral from outside to inside, and the flow passage of the steam fluid in the heat exchanger 411 is in the spiral plate gap from bottom to top. The flow directions of the cold fluid and the steam fluid are mutually perpendicular.

Further, the gap between adjacent spiral plates in the heat exchanger 411 is 2 to 28mm, preferably 6 to 18mm.

Further, the spiral plate in the heat exchanger 411 is made of stainless steel.

In a preferred embodiment, when the heat exchanger 411 is a tube type heat exchanger, the tube diameter of the heat exchange tube in the tube type heat exchanger is 19-57 mm, the wall thickness of the heat exchange tube is 0.8-3.5 mm, the tube spacing is 25-65 mm, and the length of the heat exchange tube is 0.5-6 m.

Further, the heat exchange tubes are arranged in a mode selected from one of regular triangles, corner triangles, squares and corner squares.

Further, the heat exchange tube is made of carbon steel or stainless steel, preferably stainless steel.

Further, the tube side flow rate of the heat exchange tube is 3-25 m/s.

In a preferred embodiment, when the heat exchanger 411 is a tube type heat exchanger, the number of passes of the heat exchange tube shell in the tube type heat exchanger is 1 to 4, preferably 1.

In a preferred embodiment, when the heat exchanger 411 is a tube type heat exchanger, a baffle plate is disposed on the tube side of the tube type heat exchanger, and the baffle plate is selected from one of a single-bow type, a double-bow type, a triple-bow type, a circular ring type, a circular-defect type, a hole type baffle plate and a spiral type, and is preferably a single-bow type. The baffle plate is used for enhancing heat exchange.

Further, the rate of the circular defect of the baffle plate is 10-55%, preferably 25-45%; the pitch of the baffles is 1/5 to 3/5, preferably 1/3, of the outer diameter of the heat exchanger section 41.

Further, the shell side flow rate of the baffle is 1 to 3.5m, preferably 1.5 to 2.5m.

In the flash stripping cooling tower provided by the invention, as shown in fig. 1, the upper end and the lower end of the heat exchanger 411 in the heat exchanger section 41 are detachably connected with the inner wall of the heat exchange chamber 4 respectively. The detachable connection is through flange connection. The maintenance, the disassembly, the cleaning and the replacement can be conveniently carried out.

In the flash stripping cooling tower provided by the invention, as shown in fig. 1, a second wire mesh demister 414 is arranged above the heat exchanger section 41 in the heat exchange chamber 4. The second wire mesh demister 414 can more thoroughly remove entrained droplets in the gas phase.

In the flash stripping cooling tower provided by the invention, as shown in fig. 1, the top of the separation chamber 5 is provided with an air outlet 51.

The second aspect of the invention provides a flash stripping cooling system, as shown in fig. 2, comprising a first flash stripping cooling tower S1, a second flash stripping cooling tower S2, a vacuum flash tank S3, a grey water tank S4, a settling tank S5, a condenser S6 and a vacuum flash separation tank S7;

the first flash steam stripping cooling tower S1, the second flash steam stripping cooling tower S2, the vacuum flash tank S3 and the gray water tank S4 are sequentially communicated along the black water input direction to form a black water passage; in the black water passage, the bottom of the vacuum flash tank S3 is communicated with the grey water tank S4 through a settling tank S5, and the top of the vacuum flash tank S3 is communicated with the grey water tank S4 through a condenser S6 and a vacuum flash separation tank S7;

the ash water tank S4 is respectively communicated with the first flash steam stripping cooling tower S1 and the second flash steam stripping cooling tower S2 along the ash water reflux direction to form an ash water reflux passage;

The first flash stripping cooling tower S1 and the second flash stripping cooling tower S2 form a condensed water loop along the flowing direction of condensed water.

In the flash stripping cooling system provided by the invention, as shown in fig. 2, the first flash stripping cooling tower S1 is a high-pressure flash stripping cooling tower, and the pressure of the high-pressure flash stripping cooling tower is more than 0.5MPaG and less than or equal to 2.0MPaG.

In the flash stripping cooling system provided by the invention, as shown in fig. 2, the second flash stripping cooling tower S2 is a low-pressure flash stripping cooling tower, and the pressure of the low-pressure flash stripping cooling tower is 0.01-0.5MPaG.

In the flash stripping cooling system provided by the invention, as shown in fig. 2, the first flash stripping cooling tower S1 is communicated with the gasification furnace S8, and is used for inputting black water from the gasification furnace S8. The gasification furnace S8 is a pulverized coal type or coal water slurry type gasification furnace.

In a preferred embodiment, as shown in FIG. 2, the gasifier S8 is in communication with the evaporator section 12 of the flash chamber 1.

In the flash stripping cooling system provided by the invention, as shown in fig. 2, the vacuum flash tank S3 is communicated with the slag skimming tank S9 through a pipeline. The black water slag dragging pool S9 is a conventionally used black water slag dragging pool and is used for carrying out liquid-solid separation on coal slag and coal ash.

In the flash stripping cooling system provided by the invention, as shown in fig. 2, a mixer S10 is arranged on a pipeline between the vacuum flash tank S3 and the settling tank S5 along the black water output direction. The mixer S10 is a conventionally used mixer, specifically, the mixer S10 is an axial flow mixer.

In the flash stripping cooling system provided by the invention, as shown in fig. 2, the condenser S6 is arranged at the top of the vacuum flash tank S3.

In the flash stripping cooling system provided by the invention, as shown in fig. 2, the cooling medium of the condenser S6 is circulating cooling water.

In the flash stripping cooling system provided by the invention, as shown in fig. 2, the vacuum flash separation tank S7 is externally connected with a flash vacuum pump S11. The flash evaporation vacuum pump S11 is a water ring type vacuum pump.

In the flash evaporation stripping cooling system provided by the invention, an ash water pump unit and an air cooler S13 are sequentially arranged on a pipeline between the ash water tank S4 and the first flash evaporation stripping cooling tower S1 along the ash water output direction, and the ash water pump unit is also communicated with the second flash evaporation stripping cooling tower S2 through the pipeline.

In a preferred embodiment, the greywater pump unit is selected from one of a single greywater pump or a double greywater pump.

In a further preferred embodiment, when the grey water pump unit is a single grey water pump, a flow regulating valve is arranged on the single grey water pump. The single ash water pump carries out flow distribution adjustment through a flow adjusting valve, and controls the ash water flow ratio of the heat exchange section 41 entering the first flash steam stripping cooling tower S1 and the stripping chamber 3 of the second flash steam stripping cooling tower S2.

In a further preferred embodiment, as shown in fig. 2, when the grey water pump unit is a double grey water pump, the double grey water pumps are respectively a high-pressure grey water pump S12 and a low-pressure grey water pump S14, the high-pressure grey water pump S12 is arranged on a pipeline between the grey water tank S4 and the first flash stripping cooling tower S1, and the low-pressure grey water pump S14 is arranged on a pipeline between the grey water tank S4 and the second flash stripping cooling tower S2.

The single ash water pump, the high-pressure ash water pump S12 and the low-pressure ash water pump S14 are all centrifugal pumps. The outlet pressure of the high-pressure greywater pump S12 is greater than that of the low-pressure greywater pump S14. The air cooler S13 is a heat exchanger using air as a cooling medium.

In a preferred embodiment, as shown in fig. 2, the grey water tank S4 is in communication with heat exchanger sections 41 in the heat exchange chambers 4 of the first flash stripping cooling tower S1, the second flash stripping cooling tower S2, respectively.

In the flash stripping cooling system provided by the invention, as shown in fig. 2, the first flash stripping cooling tower S1 is respectively communicated with the conversion section S15 and the synthesis gas washing tower S16, and is used for inputting condensed water from the conversion section S15 and outputting the circulated condensed water to the synthesis gas washing tower S16. The conversion section S15 is a carbon monoxide conversion section, and is to convert CO into H ₂ For adjusting the hydrocarbon ratio. Specifically, the shift section S15 from the coal gasification project shifts condensed water, and the condensed water of the shift section S15 is derived from entrained water in the synthesis gas and water generated by shift side reaction The condensate contains H ₂ S is acidic, has large corrosiveness to equipment pipelines and is not easy to recycle, and the equipment has good gas-liquid separation performance, so that the waste liquid inconvenient to recycle can be treated. So the high-concentration H2S acid gas contained in the tower top is sent to the sulfur recovery device S19.

In a preferred embodiment, as shown in fig. 2, the stripping chamber 3 of the first flash stripping cooling tower S1 is communicated with the conversion section S15, the liquid phase residence chamber 2 of the first flash stripping cooling tower S1 is communicated with the synthesis gas scrubber S16, a scrubber feed pump S17 is arranged on a pipeline between the liquid phase residence chamber 2 and the synthesis gas scrubber S16, an outlet of the scrubber feed pump S17 is communicated with the synthesis gas scrubber S16, and an inlet of the scrubber feed pump S17 is communicated with a liquid outlet 217 of the liquid phase residence chamber 2 of the first flash stripping cooling tower S1.

The washing tower feeding pump S17 is a centrifugal pump, and the washing tower feeding pump S17 can be driven by an electric driving machine or a steam driving machine, preferably an electric driving machine.

In the flash stripping cooling system provided by the invention, as shown in fig. 2, the first flash stripping cooling tower S1 is communicated with the ash water inlet 321 of the stripping chamber 3 in the second flash stripping cooling tower S2 through the cooling ash water outlet 413 of the heat exchange chamber 4, and is used for inputting condensed water flowing in the heat exchange chamber 4 into the second flash stripping cooling tower S2, and the second flash stripping cooling tower S2 is communicated with the heat exchange chamber 4 in the first flash stripping cooling tower S1 through the liquid outlet 217 of the liquid phase residence chamber 2, and is used for refluxing the condensed water input into the second flash stripping cooling tower S2 into the heat exchange chamber 41 of the heat exchange chamber 4 of the first flash stripping cooling tower S1.

In a preferred embodiment, as shown in fig. 2, a flash stripping cooling tower feed pump S18 is provided on the line between the liquid outlet 217 of the liquid phase residence chamber 2 of the second flash stripping cooling tower S2 and the heat exchange chamber 4 of the first flash stripping cooling tower S1.

In a preferred embodiment, as shown in fig. 2, the cooling ash water inlet 412 and the cooling ash water outlet 413 of the second flash stripping cooling tower S2 are externally connected with circulating cooling water to form a cooling loop.

In the flash stripping cooling system provided by the invention, as shown in fig. 2, the first flash stripping cooling tower S1 and the second flash stripping cooling tower S2 are respectively communicated with the sulfur recovery device S19 along the tail gas output direction. The sulfur recovery device S19 is used for recovering sulfur or treating H-containing gas at the downstream of the tower top gas ₂ S gas device.

In the black water treatment process provided by the invention, in the steps 1), 2) or 3), the flow rate of the gray water is 1.2-3.5 m/s. Because the structure of the tower top heat exchanger is changed, the grey water is used as a cooling medium, and a high flow rate is adopted. The high flow rate of the ash water and a small amount of solid particles contained in the ash water are utilized to achieve the effect of scouring, so that the ash water side is not easy to scale, and the purpose of long-term stable use is achieved.

In the black water treatment process provided by the invention, in the step 1), the black water is input from a chilling chamber of a gasifier.

In the black water treatment process provided by the invention, in the step 1), the grey water is input from a synthesis gas washing tower and a grey water tank.

In the black water treatment process provided by the invention, in the step 1), the pressure of the black water and the gray water is reduced before the black water and the gray water are input into the first flash steam stripping cooling tower.

In the black water treatment process provided by the invention, in the step 1), the flash evaporation conditions of the first flash vapor stripping cooling tower are as follows: the flash evaporation temperature is 126-168 ℃; the flash pressure is 0.50-2.0MPaG, preferably 0.62MPaG.

In the black water treatment process provided by the invention, in the step 1), the first steam comprises and is not limited to CO, CO2, H2 and H2S, NH4.

In the black water treatment process provided by the invention, in the step 1), the heat exchange temperature of the heat exchange chamber is 80-125 ℃.

In the black water treatment process provided by the invention, in the step 1), the cooling temperature is less than or equal to 60 ℃.

In the black water treatment process provided by the invention, in the step 1), the first tail gas is gas and water vapor without condensation.

In the black water treatment process provided by the invention, in the step 2), the grey water is input from a grey water tank.

In the black water treatment process provided by the invention, in the step 2), the pressure of the black water is reduced before the black water is input into the second flash stripping cooling tower.

In the black water treatment process provided by the invention, in the step 2), the flash evaporation conditions of the second flash evaporation stripping cooling tower are as follows: the flash evaporation temperature is 80-125 ℃; the flash pressure is 0-0.6MPaG, preferably 0.12MPaG. Further flashing of the gas dissolved in the black water.

In the black water treatment process provided by the invention, in the step 2), the heat exchange temperature of the heat exchange chamber is 80-125 ℃.

In the black water treatment process provided by the invention, in the step 2), the cooling temperature is less than or equal to 60 ℃.

In the black water treatment process provided by the invention, in the step 2), the second tail gas is gas and water vapor without condensation.

In the black water treatment process provided by the invention, in the step 3), the pressure of the black water is reduced before the black water is input into the vacuum flash tank.

In the black water treatment process provided by the invention, in the step 3), the flash evaporation conditions of the vacuum flash tank are as follows: the flash evaporation temperature is 80-85 ℃, preferably 82 ℃; the flash pressure is-0.10 to-0.01 MPaG, preferably-0.05 MPaG.

In the black water treatment process provided by the invention, in the step 3), the condensation temperature of the condenser is 55-85 ℃, preferably 67 ℃.

In the black water treatment process provided by the invention, in the step 3), the second flash residue is water.

In the black water treatment process provided by the invention, in the step 3), the polymeric flocculant is put into the settling tank, and the polymeric flocculant is a polyacrylamide flocculant.

In the black water treatment process provided by the invention, in the step 3), the ash water tank is provided with a dispersing agent, and the dispersing agent is selected from one of sulfonate, naphthalene, humic acid, lignin, polyolefin, acrylic acid and the compounding thereof.

In a preferred embodiment, the dispersant is a sulfonic acid-carboxylic acid based dispersant.

In the black water treatment process provided by the invention, in the step 3), the temperature of the grey water in the grey water tank is 55-85 ℃, preferably 77 ℃.

In the black water treatment process provided by the invention, in the step 3), the grey water is cooled by an air cooler and then flows back to the first flash steam extraction cooling tower, and the cooling temperature of the air cooler is 45-50 ℃. And part of the ash water is sent to the first flash steam stripping cooling tower for heat exchange, and is sent to the second flash steam stripping cooling tower again after heat exchange. Part of the grey water is sent to a second flash stripping cooling tower as scrubbing liquid.

In a preferred embodiment, the air cooler is used under one or more of the following conditions, preferably 3 to 5 conditions:

C) The design inlet temperature of the air is less than 38 ℃;

f) The solidifying point of the hot fluid is less than 0 ℃;

For different coal types, alkali liquor such as sodium hydroxide aqueous solution can be added into the black water circulation system to neutralize acidity when needed.

Example 1

Black water was fed from the gasifier quench chamber to the flash chamber of the first flash stripping cooling tower at a flow rate of 314400kg/h, a solids content of 0.02, a pressure of 4.2mpa g and a temperature of 193 ℃. The grey water was fed from the syngas scrubber to the stripping chamber of the first flash stripping cooling tower at a flow rate of 100852.19kg/h, a solids content of 0.00845, and a temperature of 182 ℃. The black water and grey water were each depressurized to 0.7MpaG and fed into a first flash stripping cooling tower. The black water is flashed in the flash chamber to form first steam, and the first steam flows upwards through the gas phase pipe, passes through the liquid phase residence chamber, enters the stripping chamber and is mixed with ash water, and full countercurrent mass transfer and heat transfer are carried out. The grey water may also be the stripping chamber of the first flash stripping cooling tower refluxed from the grey water tank, this stream having a flow rate of 375467.56kg/h and a temperature of 125.2 ℃. The first steam leaving the uppermost tray in the stripping chamber of the first flash stripping cooling tower enters the heat exchanger section of the heat exchange chamber at the temperature of 125 ℃, and the heat exchange area of the heat exchanger in the heat exchanger section is 104.73m ² The heat exchanger power was 229.72kw. Cooling to 60 ℃ after heat exchange, and sending the obtained first tail gas to a sulfur recovery device for sulfur recovery.

The pressure of the flash-evaporated black water slag in the flash chamber of the first flash stripping cooling tower is 0.8MpaG, and the temperature is 180 ℃. And after the pressure difference is reduced to 0.13MpaG through a reducing angle valve, the flash steam is input into the flash chamber of the second flash steam stripping cooling tower from the flash chamber of the first flash steam stripping cooling tower, and the flash steam amount of the black water slag water in the flash chamber of the second flash steam stripping cooling tower is 34492.65kg/h. The black water is flashed in the flash chamber to form second steam, and the second steam flows upwards through the gas phase pipe, flows through the liquid phase residence chamber, enters the stripping chamber and is mixed with ash water, and full countercurrent mass transfer and heat transfer are carried out. The second flash stripping cooling tower, with the grey water being refluxed from the grey water tank, had a flow of 316983.83kg/h and a temperature of 77 ℃. Leave the second flash stripping coolingThe second steam of the uppermost tray in the stripping chamber of the tower enters a heat exchanger section of a heat exchange chamber, and the heat exchange area of the heat exchanger in the heat exchanger section is 122.6m ² . Cooling to 60 ℃ after heat exchange, and sending the obtained second tail gas to a sulfur recovery device for sulfur recovery.

The flow rate of the flash-evaporated black water slag in the flash chamber of the second flash stripping cooling tower was 365900.6kg/h, the pressure was 0.13MpaG, and the temperature was 125 ℃. And (3) reducing the pressure to-0.03 Mpa G through a pressure difference and a pressure reducing angle valve, and then enabling the mixture to enter a vacuum flash tank for flash evaporation, wherein the flash steam quantity of the black water slag water in the vacuum flash tank is 26417.1kg/h. After the black water slag water is flashed in the vacuum flash tank, ash water with the flow rate of 449904.75kg/h (the pressure is-0.08 MpaG and the temperature is 82 ℃) is discharged from the bottom of the vacuum flash tank, the slag water flows into a settling tank through a level difference, and slag is discharged from the bottom of the settling tank, and upper clean ash water flows into an ash water tank (the pressure is normal pressure and the temperature is 77 ℃). Part of the ash water in the ash water tank is pumped to a second flash evaporation stripping cooling tower through a low-pressure ash water pump, and the other part of the ash water is boosted through a high-pressure ash water pump at a flow rate of 39587.25kg/h, cooled to 45-50 ℃ through an air cooler (1470.182 KW) and then sent to a heat exchanger section of the first flash evaporation stripping cooling tower for heat exchange (the outlet is about 50-55 ℃).

In the process, slag water at the bottom of the stripping chamber of the first flash stripping cooling tower is sent into a synthetic gas washing tower for washing and utilization through a washing tower feed pump (the flow is 407249.89kg/h and the pressure is 4.68Mpa G). The heat exchange chamber of the second flash stripping cooling tower is cooled by circulating water (inlet 32 ℃ and outlet 40 ℃) and the cooling water quantity is 225790.63kg/h.

In the process, the size of the first flash stripping cooling tower is 4000 x 12900 of flash chamber phi, 4000 x 10000 of gas phase diameter section phi in the liquid phase residence chamber, 2800 x 5400 of tray section phi in the stripping chamber; heat exchanger sections phi 2800 x 2000 of the heat exchange chamber, central holes 500, heat exchange areas 234.8m2, plate spacing 0.012m.

The second flash evaporation stripping cooling tower has the dimensions of a flash evaporation chamber phi 3200, 10500, a gas reducing section phi 3200, 4000, a tray section phi 3200, 4800, a heat exchanger section phi 3200, 1800, a central hole 800 and a heat exchange area 283.6m ² The plate spacing was 0.010m.

The treatment process for black water and the apparatus thereof in example 1 were compared with the existing slag water treatment process and the apparatus thereof, and specific data are shown in table 1. As can be seen from table 1, the present technical solution saves the circulating water: 152.94t/h, the required proportion of the circulating water is reduced by 8.18 percent, and the water-saving effect is very obvious; the water quantity sent to the washing tower is 7.07% larger than that of the traditional technology. The energy-saving and water-saving effects are very obvious.

TABLE 1

In summary, the flash evaporation stripping cooling system and the treatment process for the black water provided by the invention have the advantages of integrated equipment, simplified flow, reduced energy consumption, improved heat transfer effect, low-temperature grey water cooling, realization of graded utilization of the low-temperature grey water, saving of a large amount of circulating water and complete recycling of slag water. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.

Claims

1. The flash steam stripping cooling system is characterized by comprising a first flash steam stripping cooling tower (S1), a second flash steam stripping cooling tower (S2), a vacuum flash tank (S3), a grey water tank (S4), a settling tank (S5), a condenser (S6) and a vacuum flash separation tank (S7);

The first flash steam stripping cooling tower (S1), the second flash steam stripping cooling tower (S2), the vacuum flash tank (S3) and the gray water tank (S4) are sequentially communicated along the black water input direction to form a black water passage; in the black water passage, the tank bottom of the vacuum flash tank (S3) is communicated with the gray water tank (S4) through a settling tank (S5), and the tank top of the vacuum flash tank (S3) is communicated with the gray water tank (S4) through a condenser (S6) and a vacuum flash separation tank (S7);

the ash water tank (S4) is respectively communicated with the first flash steam stripping cooling tower (S1) and the second flash steam stripping cooling tower (S2) along the ash water reflux direction to form an ash water reflux passage;

the first flash steam stripping cooling tower (S1) and the second flash steam stripping cooling tower (S2) form a condensed water loop along the flowing direction of condensed water;

an ash water pump unit and an air cooler (S13) are sequentially arranged on a pipeline between the ash water tank (S4) and the first flash steam stripping cooling tower (S1) along the ash water output direction, and the ash water pump unit is also communicated with the second flash steam stripping cooling tower (S2) through the pipeline;

the grey water pump unit is selected from one of a single grey water pump or a double grey water pump.

2. The flash stripping cooling system according to claim 1, wherein the first flash stripping cooling tower (S1) and the second flash stripping cooling tower (S2) are flash stripping cooling towers, and the flash stripping cooling towers are sequentially provided with a flash chamber (1), a liquid-phase residence chamber (2), a stripping chamber (3), a heat exchange chamber (4) and a separation chamber (5) from bottom to top; the steam stripping chamber (3) is sequentially provided with a tray section (31), a liquid phase distributor (32) and a gas phase distributor (33) along the steam flowing direction, the tray section (31) is internally provided with a plurality of trays (311), the heat exchange chamber (4) is internally provided with a heat exchanger section (41), and the heat exchanger section (41) is internally provided with a plurality of heat exchangers (411).

3. The flash stripping cooling system according to claim 2, wherein a cone section (11) and an evaporation section (12) are sequentially arranged in the flash chamber (1) from bottom to top, the cone section (11) is gradually enlarged from bottom to top, a slag discharging pipe (111) is arranged at the bottom of the cone section (11), a black water outlet pipe (112) is arranged on the side wall of the cone section (11), and a black water inlet (121) is arranged on the side wall of the evaporation section (12).

4. The flash stripping cooling system according to claim 2, wherein the liquid phase residence chamber (2) is internally provided with a liquid phase residence section (21) and a gas phase diameter reduction section (22) in sequence from bottom to top, and the width of the gas phase diameter reduction section (22) is gradually reduced from bottom to top.

5. The flash stripping cooling system of claim 2, wherein the flash stripping cooling tower further comprises any one or more of the following conditions:

a) The tray (311) is a plate tray, the tray (311) comprising at least 2 downcomers (312);

b) A first silk screen foam remover (331) is arranged in the gas-phase distributor (33);

c) One end of the liquid phase distributor (32) horizontally penetrates through the stripping chamber (3) to form a grey water inlet (321);

d) A cooling ash water inlet (412) and a cooling ash water outlet (413) are arranged on the side wall of the heat exchanger section (41);

E) The heat exchanger (411) is a spiral plate type or tube type heat exchanger;

f) A second silk screen foam remover (414) is arranged above the heat exchanger section (41) in the heat exchange chamber (4);

g) An air outlet (51) is arranged at the top of the separation chamber (5).

6. A flash stripping cooling system as claimed in claim 1, wherein the first flash stripping cooling tower (S1) is a high pressure flash stripping cooling tower having a pressure > 0.5MPaG and < 2.0MPaG.

7. A flash stripping cooling system as claimed in claim 1, characterized in that the second flash stripping cooling tower (S2) is a low pressure flash stripping cooling tower with a pressure of 0.01-0.5MPaG.

8. The flash stripping cooling system as recited in claim 1, further comprising any one or more of the following conditions:

a) The first flash steam stripping cooling tower (S1) is communicated with the gasification furnace (S8);

b) The vacuum flash tank (S3) is communicated with the black water slag scooping tank (S9) through a pipeline;

c) A mixer (S10) is arranged on a pipeline between the vacuum flash tank (S3) and the sedimentation tank (S5) along the black water output direction;

d) The condenser (S6) is arranged on the tank top of the vacuum flash tank (S3);

e) The vacuum flash separation tank (S7) is externally connected with a flash vacuum pump (S11);

f) The first flash steam stripping cooling tower (S1) is respectively communicated with the conversion section (S15) and the synthetic gas washing tower (S16);

g) The first flash steam stripping cooling tower (S1) is communicated with a grey water inlet (321) of a stripping chamber (3) in a second flash steam stripping cooling tower (S2) through a cooling grey water outlet (413) of a heat exchange chamber (4), and the second flash steam stripping cooling tower (S2) is communicated with the heat exchange chamber (4) in the first flash steam stripping cooling tower (S1) through a liquid outlet (217) of a liquid phase residence chamber (2);

h) The first flash steam stripping cooling tower (S1) and the second flash steam stripping cooling tower (S2) are respectively communicated with the sulfur recovery device (S19) along the tail gas output direction.

9. Use of a flash stripping cooling system according to any of claims 1-8 in black water treatment.

10. A black water treatment process employing a flash stripping cooling system according to any one of claims 1-8, comprising the steps of: