CN109126364B - Treatment process for deep heat collection and purification of flue gas - Google Patents
Treatment process for deep heat collection and purification of flue gas Download PDFInfo
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- CN109126364B CN109126364B CN201811283013.9A CN201811283013A CN109126364B CN 109126364 B CN109126364 B CN 109126364B CN 201811283013 A CN201811283013 A CN 201811283013A CN 109126364 B CN109126364 B CN 109126364B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D21/00—Heat-exchange apparatus not covered by any of the groups F28D1/00 - F28D20/00
- F28D21/0001—Recuperative heat exchangers
- F28D21/0014—Recuperative heat exchangers the heat being recuperated from waste air or from vapors
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D47/00—Separating dispersed particles from gases, air or vapours by liquid as separating agent
- B01D47/06—Spray cleaning
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/343—Heat recovery
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/30—Sulfur compounds
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/02—Other waste gases
- B01D2258/0283—Flue gases
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/48—Sulfur compounds
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working
Abstract
A treatment process for deeply receiving and purifying flue gas relates to the technical field of heating technology and waste gas purification. The device consists of three units of waste heat recovery, desulfurization and white smoke purification, wherein the smoke enters a plurality of stages of heat exchange areas of the waste heat recovery unit, deionized cooling water is adopted for heat exchange, and the vaporization and heat absorption at a boiling point lower than normal pressure under the condition of negative pressure can be realized, so that the waste heat of the smoke is recovered in a steam form and is discharged through a preheating section; when the cooled flue gas after heat collection enters the desulfurization unit, the water evaporation capacity can be reduced; and the flue gas discharged from the desulfurization unit is subjected to spray cooling, membrane demisting and flue gas reheating treatment of the purification white smoke elimination unit and then is discharged. The invention can recover more flue gas waste heat in a steam form with higher enthalpy on one hand, and can also purify flue gas deeply on the other hand, thereby realizing ultralow emission without 'white smoke' at a flue gas outlet.
Description
Technical Field
The invention relates to the technical field of heating technology and waste gas purification, in particular to a treatment process for deep heat collection and purification of flue gas.
Background
China is one of the countries with the largest smoke emission in the world at present, and the smoke emission is mainly concentrated in the fields of electric power, refining, heating power, coking, metallurgy and the like. According to the requirements of relevant specifications, the temperature of the flue gas before desulfurization is basically controlled to be 130-180 ℃, and the temperature of the flue gas before desulfurization is partially even over 200 ℃. How to fully recycle the flue gas waste heat and reduce the waste heat emission as much as possible is one of the main subjects faced by technical workers in the field.
Meanwhile, the method is also imperative for treating haze pollution and eliminating 'white smoke' during smoke emission. Most of the white smoke discharged from the chimney comes from the vaporization of water in the wet treatment process of the smoke, such as the white smoke formed by the wet tail gas discharged after wet desulphurization. Therefore, the effective recovery of heat energy becomes an important precondition for removing white smoke from the smoke.
Many techniques select cooling water to cool the smoke, but the problem of white smoke emission cannot be effectively solved. Not only is the equipment corrosion and the efficiency which are inevitably accompanied by the flue gas heat exchange not high, but also most of the waste heat can only heat the cooling water when the temperature of the flue gas is below 130 ℃, and steam can not be obtained basically. In order to be recycled, the cooling water must be cooled by a water cooling tower, so that the 'white smoke' and the heat energy are essentially transferred from a chimney to the water cooling tower for discharge.
At present, the treatment technologies for recovering the waste heat of the smoke and eliminating the white smoke are mainly as follows: 1) the MGGH technology utilizes the closed circulation flow of heat medium water, uses the heat obtained from the raw flue gas to heat the purified flue gas after desulfurization and dust removal, so as to enhance the flue gas diffusion capacity, thereby reducing the problem of white smoke plume of a chimney from the sense, and still releasing a large amount of flue gas waste heat to the environment. 2) The phase-change heat exchange and heat pipe heat exchange technology absorbs the waste heat of the flue gas by using the vaporization of water, but in order to avoid or reduce acid condensation corrosion and ash blockage, the final flue gas temperature is basically controlled to be about 130 ℃ or even higher due to the limit of heat exchange conditions. The problem of white smoke pollution at the outlet of the flue cannot be solved. 3) It has also been reported that the cooling water is directly contacted with the flue gas, the tail heat of the flue gas after desulfurization is recovered to obtain warm hot water, then the warm hot water is heat-exchanged with the flue gas with higher temperature by a heat exchanger to obtain high-temperature hot water, and finally the process steam is obtained by negative pressure evaporation of a heat pump. This approach has significant drawbacks: firstly, the low temperature flue gas still contains suspended solid and trace acid after the desulfurization, though the adoption gas, liquid contact formula can be traded the waste heat, nevertheless the aquatic water has dissolved impurity such as considerable ash content, and the steam is then produced in the reuse is used for the heat transfer of high temperature flue gas, leads to the inside corrosion and the scaling that forms of heat exchange tube of follow-up equipment certainly to will accumulate rapidly, can seriously influence the heat exchange efficiency and the safe handling of heat exchanger and evaporimeter. Secondly, the steam generated by the technical route contains a small amount of acid gas, carbon dioxide and the like, and can cause corrosion and damage to the heat pump compressor.
Along with the requirements of environmental protection policies and the continuous improvement of public environmental protection consciousness, the emission standard of the flue gas is increasingly strict, and society needs a new technology which can deeply purify the flue gas and can utilize the waste heat in the flue gas as much as possible.
Disclosure of Invention
The invention aims to provide a treatment process for deeply receiving and purifying flue gas, which can fully recover the waste heat of the flue gas and be used for generating steam, effectively eliminate the phenomenon of 'white smoke' during the emission of the flue gas and deeply remove pollutants such as smoke dust, aerogel and the like.
A treatment process for deeply receiving and purifying flue gas comprises a waste heat recovery unit, a desulfurization unit and a white smoke purification unit. The flue gas passes through the waste heat recovery unit to obtain cooled flue gas, the cooled flue gas passes through the desulfurization unit to obtain desulfurized flue gas, and the desulfurized flue gas passes through the white smoke purification and elimination unit and then enters the chimney to be discharged. Through the waste heat recovery unit, the heat energy in the flue gas can be recovered in a steam form, and meanwhile, the temperature of the flue gas is reduced to 75 ℃ or even lower and passes through the acid dew point of the sulfur-containing flue gas; the enthalpy of the cooling flue gas is reduced, so that the evaporation capacity of water in the operation of the desulfurization unit is also obviously reduced; after the treatment of the purifying and white smoke eliminating unit, the ultra-clean emission without white smoke at the discharge port of the chimney can be realized.
The main equipment of the waste heat recovery unit of the invention comprises: a heat transfer zone, a circulation pump, and a preheating zone; the heat exchange area is composed of a negative pressure self-infiltration heat exchange tube bundle with a tube pass in the flue as cooling water, a negative pressure vapor-liquid isolating bag outside the flue, a negative pressure vapor compressor, a cooling water supplementing pipe orifice and a collecting pipe orifice.
In the waste heat recovery unit, cooling water enters a tube pass of a collecting pipe at the bottom of a preheating section, flows out from the top of the water preheating section after heat exchange, enters a cooling water replenishing pipe orifice of a heat exchange area, absorbs heat to be vaporized to form steam, enters a negative pressure steam-liquid isolating bag from a negative pressure self-infiltration heat exchange tube bundle to separate liquid water, enters a negative pressure steam compressor, is pressurized by the negative pressure steam compressor, and enters a steam main pipe to form a cooling water heat exchange loop.
In the waste heat recovery unit, flue gas flows through the shell pass of the negative pressure self-infiltration tube bundle in the heat exchange area after entering the flue, is cooled after exchanging heat with cooling water, and finally flows through the water preheating section to be further cooled and then flows to the desulfurization unit, so that a flue gas heat exchange loop is formed.
The negative pressure self-infiltration heat exchange tube bundle in the heat exchange area is communicated with the negative pressure vapor-liquid isolating bag; a steam pipe at the top of the negative-pressure steam-liquid isolating bag is communicated with an inlet of a negative-pressure steam compressor, and an outlet of the negative-pressure steam compressor is communicated with a steam main pipe; the cooling water supplement pipe orifice is arranged at one or more parts of the following cooling water in a liquid state or a vapor-liquid mixed state, and comprises: the negative pressure steam-liquid isolating bag, the connecting pipeline of the negative pressure self-infiltration heat exchange tube bundle and the negative pressure steam-liquid isolating bag and the manifold of the negative pressure self-infiltration heat exchange tube bundle.
The compressor of the invention selects one or more of a Roots type compressor, a centrifugal type compressor and a screw type compressor; the steam pressures at the three positions of the negative pressure self-infiltration heat exchange tube bundle, the negative pressure steam-liquid isolating bag and the inlet of the negative pressure steam compressor are consistent, so that the three parts form a heat exchange area under independent working conditions.
The invention can gradually add heat exchange areas with different working conditions according to the increase of the temperature and the flow of the flue gas, and the steam pressure of the added heat exchange areas is different, thus forming a multistage series heat exchange process.
The cooling water is boiler feed water with the temperature lower than 33 ℃.
The multistage series heat exchange process of the heat exchange zone comprises the following steps: the heat exchange area comprises a negative pressure heat exchange area, and the corresponding steam gauge pressure is-0.06-0 MPa.
Further, when the inlet air temperature is higher than 110 ℃, a micro-positive pressure heat exchange area can be additionally arranged before the negative pressure heat exchange area, and the corresponding steam gauge pressure is between 0 and 0.25 MPa;
further, when the inlet air temperature is higher than 130 ℃, a positive pressure heat exchange area can be arranged before the micro-positive pressure heat exchange area, and the corresponding steam gauge pressure is higher than 0.25 MPa;
further, the sequence of contact between the flue gas and the heat exchange area is from the positive pressure heat exchange area to the micro-positive pressure heat exchange area and then to the negative pressure heat exchange area, and finally the flue gas is cooled by the preheating section to form cooled flue gas and enters the rear section desulfurization unit.
The cooling water heat exchange loop is internally provided with a cooling water circulating pump, liquid cooling water enters the inlet of the circulating pump from the bottom of the negative pressure vapor-liquid isolating bag, is pressurized by the circulating pump and then is merged with the preheated cooling water, and is sent to a cooling water supplementing pipe orifice of a heat exchange area.
In the cooling water heat exchange loop of the multistage series heat exchange process, liquid water at the bottom of the vapor-liquid isolating bag is subjected to pressure reduction flash evaporation step by step from the highest pressure to a next-stage heat exchange area through a pressure reducing valve in a circulating mode, so that the heat exchange area and flue gas form concurrent evaporation; liquid water in the negative pressure heat exchange area is pressurized by a circulating pump and is converged with the preheated cooling water, and the liquid water is conveyed to a cooling water supplementing pipe orifice of the positive pressure heat exchange area. The other circulation mode is that the pressure is increased step by a circulating pump to a previous heat exchange area, so that the heat exchange area and the flue gas form countercurrent evaporation; the liquid water in the highest pressure positive pressure heat exchange area is flashed to at least one cooling water replenishing pipe orifice with lower pressure through a pressure reducing valve.
Furthermore, in the cooling water heat exchange loop of the multistage series heat exchange process, steam at the top of the gas-liquid isolating bag is conveyed to the steam header pipe in a process flow direction after being directly pressurized by the compressor through the steam compressor, so that parallel pressurization of the steam is formed. Another process flow direction is from the outlet of the lower pressure compressor to the inlet of the higher stage compressor, constituting a series boost of vapor pressure from low to high, which is then fed to the vapor header.
The invention can convey cooling water from the low-pressure heat exchange area to the high-pressure heat exchange area through the pressurization of the circulating pump, the online circulation amount of the cooling water can be larger than the evaporation amount, the ratio of the online flow rate of the cooling water to the evaporation amount can be selected to be (1.01-3): 1, and the particularly suitable ratio range is (1.2-2): 1.
The cooling water of the present invention is continuously replenished from the preheating section, and since the concentration of the electrolyte in the water is increased by evaporation, a part of the water can be extracted at the end of the cycle. Because the evaporation and the extracted part lead to the reduction of cooling water, the same amount of cooling water can be added for supplement, the supplement amount is larger than the evaporation amount, and the residual liquid water after evaporation is discharged from a cooling water extraction pipe orifice.
The purifying and white smoke eliminating unit of the invention comprises: a spray tower membrane demister and a flue gas reheater; wherein, the upper part in the spray tower is provided with a cooling spray device, and the lower part is provided with a tower tray; wherein, a hydrophilic microporous membrane is arranged in the membrane demister; the hydrophilic microporous membrane divides the membrane demister into a gas side and a liquid side, wherein the gas side is in contact with one side of a membrane surface of flue gas, the liquid side is not in contact with one side of the back surface of the flue gas, the gas side passes through the sprayed flue gas containing fog drops, and the liquid side is provided with a pipeline opening which is used for introducing water for infiltrating the membrane and extracting water formed by collecting the fog drops, and the pressure of the liquid side is kept lower than the pressure of the flue gas; the space in the tower outside the cooling and spraying device is communicated with the gas side of the membrane demister, the gas side of the membrane demister is communicated with a chimney, and a flue gas reheater is arranged between the membrane demister and the inlet of the chimney.
In the purifying and white smoke eliminating unit, cooling water enters a cooling spraying device at the upper part of a spraying tower, part of the cooling water is collected on a tower tray at the lower part of the spraying tower and then discharged, and the rest of the cooling water is collected at the liquid side of a membrane demister and then discharged through a set pipeline port to form a spraying and mist collecting loop of the cooling water.
In the white smoke purification and elimination unit, desulfurized smoke sequentially passes through the spray tower, the membrane demister and the reheater, the smoke is cooled and washed in the spray tower, fog drops, micro-foam and the like are removed through the demister to obtain low-temperature saturated gas, the low-temperature saturated gas is heated by the smoke reheater to be unsaturated smoke, and finally the unsaturated smoke enters a chimney to be discharged, so that a white smoke purification and elimination loop of the smoke is formed.
The cooling and spraying device at the upper part of the spraying tower provided by the invention adopts industrial cooling water spraying, the particle size of generated droplets is 20-400 mu m, and the tray at the bottom is preferably at least one of a float valve tray and a bubble cap tray. The flue gas enters the spray tower and first passes through the bottom tray and then is in countercurrent contact with the spray. The hydrophilic membrane in the membrane demister has the pore diameter of 5-4000 nm, the structural shape of one or more of tubular, plate-shaped, honeycomb-shaped and hollow fibers, and the material is an organic or inorganic material with a contact angle with water of less than 75 degrees. Further, before the desulfurized flue gas enters the membrane demister, water is filled in the liquid side of the microporous membrane in advance to enable the microporous membrane to be soaked, and the pressure of the liquid side is controlled to enable the pressure of the liquid side to be lower than the pressure of the flue gas.
Further, the heat source of the flue gas reheater of the present invention comprises steam generated by front end waste heat recovery.
Furthermore, the flue gas purification and white smoke elimination loop comprises a membrane demister arranged inside the spray tower, the membrane demister and the spray tower are combined into a single unit, and the membrane demister (arranged above the cooling spray device and a buffering baffling baffle is arranged between the membrane demister and the spray tower to isolate water drops carried by flue gas.
The invention has the beneficial effects that:
the invention controls the pressure of the inlet of the vapor compressor to negative pressure, so that cooling water is vaporized by controlled corresponding low temperature heat absorption to form larger heat exchange temperature difference, and the heat energy of the flue gas is converted into latent heat of vapor by smaller scale of heat exchange equipment and higher efficiency, so that the heat energy of the flue gas can be deeply recycled and utilized.
The invention can forcibly reduce the temperature of the flue gas to be lower, reduce the water evaporation capacity of the desulfurization unit and reduce the load of white smoke treatment.
The invention can lead each heat exchange area to be in the working condition with higher heat exchange efficiency by arranging the multistage heat exchange flow in series, and lead the ineffective power consumption of the vapor compressor to be lower.
The invention can strengthen the heat exchange effect of the self-soaking heat exchange tube bundle by arranging the circulating pump in the cooling water heat exchange loop.
The invention can recover most of the heat energy before the high-temperature flue gas enters the desulfurizing tower, deeply remove impurities such as other dispersed particles carried in the flue gas, eliminate the pollution of white smoke at a flue gas outlet and realize ultralow emission.
Drawings
FIG. 1 is a schematic structural diagram of the present invention.
Fig. 2 is a schematic structural diagram of embodiment 1 of the present invention.
Fig. 3 is a schematic structural diagram of embodiment 2 of the present invention.
Fig. 4 is a schematic structural diagram of embodiment 3 of the present invention.
Fig. 5 is a schematic structural diagram of embodiment 4 of the present invention.
In the figure, 11, a negative pressure self-infiltration heat exchange tube bundle, 12, a negative pressure vapor-liquid isolation bag, 13, a negative pressure vapor compressor, 14, a circulating pump, 21, a micro-positive pressure self-infiltration heat exchange tube bundle, 22, a micro-positive pressure vapor-liquid isolation bag, 23, a micro-positive pressure vapor compressor, 24, a circulating pump II, 31, a positive pressure self-infiltration heat exchange tube bundle, 32 a positive pressure vapor-liquid isolation bag, 33, a positive pressure vapor compressor, 41, a positive pressure self-infiltration heat exchange tube bundle II, 42 a positive pressure vapor-liquid isolation bag II, 43, a positive pressure vapor compressor II, 5, a water preheating section, 6-flues, 7-spray towers, 8-demisters and 9-flue gas reheaters.
Detailed Description
As shown in fig. 1 to 5, a treatment process for deep heat collection and purification of flue gas includes three units, namely a waste heat recovery unit, a desulfurization unit and a purification and white smoke elimination unit:
the flue gas passes through a waste heat recovery unit to obtain cooled flue gas, the cooled flue gas passes through a desulfurization unit to obtain desulfurized flue gas, and the desulfurized flue gas passes through a white smoke purification and elimination unit and then enters a chimney to be discharged;
wherein the waste heat recovery unit includes: a heat exchange zone, a circulation pump 14, and a water preheating zone 5; the heat exchange area comprises a negative pressure self-infiltration heat exchange tube bundle which is arranged in the flue 6 and has a tube pass of cooling water, a negative pressure vapor-liquid isolating bag outside the flue 6, a negative pressure vapor compressor, a cooling water supplementing pipe orifice and a extracting pipe orifice;
cooling water in the waste heat recovery unit enters a tube pass from a collecting pipe at the bottom of the water preheating section 5, flows out from the top of the water preheating section 5 after heat exchange, enters a cooling water replenishing pipe orifice of a heat exchange area, absorbs heat to be vaporized to form steam, enters a negative pressure steam-liquid isolating bag 12 from the tube pass of the negative pressure self-infiltration heat exchange tube bundle 11 to separate liquid water, enters a negative pressure steam compressor 13, is pressurized by the negative pressure steam compressor 13 and enters a steam collecting pipe, and a cooling water heat exchange loop is formed by the above steps;
after entering the flue, the flue gas in the waste heat recovery unit flows through the negative pressure self-soaking shell pass of the heat exchange area 11, is cooled after exchanging heat with cooling water, and finally flows through the water preheating section 5 to be further cooled and then flows to the desulfurization unit, so that a flue gas heat exchange loop is formed.
As shown in fig. 1 to 5, the self-wetting heat exchange tube bundle in the heat exchange zone of the present invention is communicated with the vapor-liquid separation bag; a steam pipe at the top of the vapor-liquid separation bag is communicated with an inlet of a vapor compressor, and an outlet of the vapor compressor is communicated with a steam main pipe; the cooling water supplementing pipe orifices are arranged at one or more parts of the steam-liquid isolating bag, the connecting pipeline of the self-soaking heat exchange pipe bundle and the steam-liquid isolating bag and the manifold of the self-soaking heat exchange pipe bundle;
the steam pressures at the self-infiltration heat exchange tube bundle, the steam-liquid isolating bag and the inlet of the steam compressor are consistent, so that the self-infiltration heat exchange tube bundle, the steam-liquid isolating bag and the inlet of the steam compressor form a heat exchange area under independent working conditions; when the heat exchange area exceeds one stage, the steam pressure of each stage is different, and a multi-stage series heat exchange process is formed.
The cooling water is boiler feed water with the temperature lower than 33 ℃, the heat exchange area comprises a negative pressure heat exchange area, and the corresponding steam gauge pressure is-0.06-0 MPa. The device comprises a negative pressure self-infiltration heat exchange tube bundle 11 arranged in a flue 6, a negative pressure vapor-liquid isolation bag 12 and a negative pressure vapor compressor 13, wherein the negative pressure self-infiltration heat exchange tube bundle 11 is arranged outside the flue 6, the negative pressure vapor-liquid isolation bag 12 is communicated with the negative pressure vapor-liquid isolation bag 11, a vapor tube at the top of the negative pressure vapor-liquid isolation bag 12 is communicated with an inlet of the negative pressure vapor compressor 13, and an outlet of the negative pressure vapor compressor 13 is communicated with a vapor main pipe; the bottom pipeline of the negative pressure vapor-liquid isolating bag 12 is communicated with the negative pressure self-infiltration heat exchange tube bundle 11. The inside of the flue 6 is provided with a water preheating section 5, the upper part of the water preheating section 5 is communicated with a bottom pipeline of the negative pressure vapor-liquid isolating bag 12, the bottom of the water preheating section 5 is provided with a water supply pipeline, the top is provided with a water outlet pipeline which is connected with a circulating pump 14, and an outlet pipeline of the circulating pump 14 is communicated with the vapor-liquid isolating bag.
A micro-positive pressure heat exchange area is additionally arranged in front of the negative pressure heat exchange area, and the corresponding steam gauge pressure is between 0 and 0.25 MPa. A micro-positive pressure self-infiltration heat exchange tube bundle 21 is arranged on one side, far away from the water preheating section 5, of the negative pressure self-infiltration heat exchange tube bundle 11 in the flue 6, an outlet of the micro-positive pressure self-infiltration heat exchange tube bundle 21 is communicated with a micro-positive pressure vapor-liquid isolating bag 22, a vapor tube at the top of the micro-positive pressure vapor-liquid isolating bag 22 is communicated with an inlet of a micro-positive pressure vapor compressor 23, and an outlet of the micro-positive pressure vapor compressor 23 is communicated with a vapor main pipe; the lower part of the micro-positive pressure vapor-liquid isolating bag 22 is connected with the negative pressure vapor-liquid isolating bag 12 through a pressure reducing valve; the outlet of the negative pressure vapor compressor 13 is connected to the inlet of the micro positive pressure vapor compressor 23 by a pipeline. The inside of the flue 6 is provided with a water preheating section 5, the upper part of the water preheating section 5 is communicated with a bottom pipeline of the negative pressure vapor-liquid isolating bag 12, the bottom of the water preheating section 5 is provided with a water supply pipeline, the top is provided with a water outlet pipeline which is connected with a circulating pump 14, and an outlet pipeline of the circulating pump 14 is communicated with the vapor-liquid isolating bag.
The positive pressure heat exchange area is arranged before the micro-positive pressure heat exchange area, namely the area contains a negative pressure area, a micro-positive pressure area and a positive pressure area, and the corresponding steam pressure is higher than 0.25 MPa. A positive pressure self-infiltration heat exchange tube bundle 31 is arranged on one side, far away from the negative pressure self-infiltration heat exchange tube bundle 11, of the micro-positive pressure self-infiltration heat exchange tube bundle 21 in the flue 6, the upper end of the positive pressure self-infiltration heat exchange tube bundle 31 is communicated with a positive pressure vapor-liquid separation bag 32, and a top air pipe of the positive pressure vapor-liquid separation bag 32 is communicated with a steam main pipe; the lower part of the positive pressure vapor-liquid isolating bag 32 is connected with the micro positive pressure vapor-liquid isolating bag 21 through a pressure reducing valve. The inside of the flue 6 is provided with a water preheating section 5, the upper part of the water preheating section 5 is communicated with a bottom pipeline of the negative pressure vapor-liquid isolating bag 12, the bottom of the water preheating section 5 is provided with a water supply pipeline, the top is provided with a water outlet pipeline which is connected with a circulating pump 14, and an outlet pipeline of the circulating pump 14 is communicated with the vapor-liquid isolating bag.
As shown in fig. 1 to 5, the purifying and white smoke eliminating unit of the present invention comprises a spray tower 7, a membrane demister 8 and a smoke reheater 9 which are connected in sequence; a cooling spraying device is arranged at the upper part in the spraying tower 7, and a tower tray is arranged at the lower part; a hydrophilic microporous membrane is arranged in the membrane demister 8; the membrane demister 8 is divided into a gas side which is in contact with the membrane surface of the flue gas and a liquid side which is not in contact with the back surface of the flue gas by the hydrophilic microporous membrane, the gas side passes through the sprayed flue gas containing fog drops, and the liquid side is provided with a pipeline opening which is used for introducing water for infiltrating the membrane and extracting water formed by collecting the fog drops and maintaining the pressure of the liquid side lower than the pressure of the flue gas; the space in the spray tower 7 except the cooling and spraying device is communicated with the air side of a membrane demister 8, the air side of the membrane demister 8 is communicated with a chimney, and a flue gas reheater 9 is arranged between the membrane demister 8 and the inlet of the chimney; cooling water enters a cooling spraying device on the upper part of a spraying tower 7, a part of the cooling water is collected on a tower tray on the lower part of the spraying tower 7 and then discharged, and the rest of the cooling water is collected on the liquid side of a membrane demister 8 and then discharged through a set pipeline port to form a spraying and mist collecting loop of the cooling water; the flue gas is cooled and washed in the spray tower 7, fog drops, micro-foam and the like are removed from the flue gas by the gas side of the membrane demister 8 to obtain low-temperature saturated gas, the low-temperature saturated gas is heated by the flue gas reheater 9 to form unsaturated flue gas, and finally the unsaturated flue gas enters a chimney to be discharged, so that a white smoke purification and elimination loop of the flue gas is formed.
As shown in FIG. 3, the smoke purifying and white smoke eliminating loop of the present invention comprises a membrane demister 8 arranged inside a spray tower 7, the two devices are combined into a single unit, the membrane demister 8 is arranged above a cooling spray device, and a buffering baffle plate is arranged between the membrane demister 8 and the cooling spray device to isolate water drops carried by smoke.
Example 1
As shown in fig. 2, a treatment process for deep heat collection and purification of flue gas is used for treating flue gas of a natural gas boiler, flue gas parameters of the natural gas boiler are shown in table 1, and the process only comprises a waste heat recovery unit.
The waste heat recovery unit device includes: the system comprises a heat exchange area, a circulating pump and a water preheating section 5, wherein the heat exchange area consists of a self-infiltration heat exchange tube bundle taking a tube pass in a flue 6 as cooling water, a vapor-liquid isolating bag and a vapor compressor outside the flue 6, and a cooling water supplementing pipe orifice and a cooling water extracting pipe orifice; the self-infiltration heat exchange tube bundle in the heat exchange area is communicated with the vapor-liquid isolating bag; a steam pipe at the top of the vapor-liquid separation bag is communicated with an inlet of a vapor compressor, and an outlet of the vapor compressor is communicated with a steam main pipe; and the cooling water supplementing pipe orifice is arranged on a connecting pipeline of the self-soaking heat exchange pipe bundle and the vapor-liquid isolating bag.
The specific implementation method comprises the following steps:
the inlet air temperature is 290 ℃, and the heat exchange area is provided with a four-stage series flow: two stages of positive pressure heat exchange areas, micro positive pressure heat exchange areas and negative pressure heat exchange areas with different pressures, wherein the cooling water 0 is boiler feed water with the temperature of 30 ℃.
Wherein the steam gauge pressure of the positive pressure heat exchange zone is between 0.3MPa and 1.0 MPa; the steam gauge pressure of the micro-positive pressure heat exchange area is 0-0.25 MPa; the gauge pressure of steam generated in the negative pressure heat exchange area is-0.05-0 MPa;
after entering the flue 6, the flue gas sequentially flows through a positive pressure self-infiltration heat exchange tube bundle II 41, a positive pressure self-infiltration heat exchange tube bundle 31, a micro-positive pressure self-infiltration heat exchange tube 21 and a negative pressure self-infiltration heat exchange tube bundle 11, exchanges heat with boiler feed water in a tube pass of the self-infiltration heat exchange tube bundle, is cooled and enters a water preheating section 5;
boiler feed water enters a tube pass of the water preheating section 5 from a collecting pipe at the bottom of the water preheating section 5, flows out of the top of the water preheating section 5 after heat exchange, and is sent to a connecting pipeline between the self-infiltration heat exchange tube bundle and the vapor-liquid isolating bag through a second circulating pump 24, so that the boiler feed water is filled in the self-infiltration heat exchange tube bundle and is subjected to heat absorption and vaporization in the tube pass of the self-infiltration heat exchange tube bundle to form steam, and the steam enters the vapor-liquid isolating bag from the self-infiltration heat exchange tube bundle to separate liquid water and then enters a vapor;
wherein, the steam at the top of the positive pressure steam-liquid isolating bag 32 is merged from the outlet of the positive pressure steam compressor 33 to the inlet of the second steam compressor 43 for pressurization and then merged into a steam header pipe; the steam at the top of the negative pressure steam-liquid isolating bag 12 is merged from the outlet of the negative pressure steam compressor 13 to the inlet of the micro-positive pressure steam compressor 23 for pressurization and then merged into a steam header pipe; the vapor compressor is a centrifugal compressor.
Liquid water at the bottom of the positive-pressure vapor-liquid isolating bag II 42 is flashed to a connecting pipeline of the positive-pressure self-wetting heat exchange tube bundle 31 and the positive-pressure vapor-liquid isolating bag 32 along the direction A4-A3 through a pressure reducing valve, the liquid water at the bottom of the positive-pressure vapor-liquid isolating bag 32 is flashed to a micro-positive-pressure heat exchange region along the direction A3-a2 through the pressure reducing valve, the liquid water at the bottom of the micro-positive-pressure vapor-liquid isolating bag 22 is flashed to a negative-pressure heat exchange region along the direction A2-a1 through the pressure reducing valve, the liquid water at the bottom of the negative-pressure vapor-liquid isolating bag 11 is discharged along the direction A1, and is pressurized by the circulating pump 14 and is delivered to the connecting pipeline between the positive-pressure self-wetting heat exchange tube bundle II 41 and the positive-pressure vapor-; the ratio of the on-line flow rate of the boiler feed water to the evaporation capacity is 2: 1;
the boiler feed water is continuously supplemented from the water preheating section 5, the supplementing quantity is larger than the liquid evaporation quantity, and the liquid water left after evaporation is discharged from a cooling water extraction pipe orifice at the outlet of the primary circulating pump 14.
The natural gas boiler flue gas finally flows through a water preheating section 5 to be further cooled to 75 ℃, and the total amount of recoverable steam is not less than 4500 kg/h.
TABLE 1 Natural gas boiler fume intake parameter table
Example 2
As shown in FIG. 3, the treatment process for deep heat collection and purification of flue gas is used for treatment of refined flue gas and comprises a waste heat recovery unit, a desulfurization unit and a white smoke purification and elimination unit, wherein the refined flue gas parameters are shown in Table 2.
The waste heat recovery unit device includes: the system comprises a heat exchange area, a circulating pump and a water preheating section 5, wherein the heat exchange area consists of a self-infiltration heat exchange tube bundle taking a tube pass in a flue 6 as cooling water, a vapor-liquid isolating bag and a vapor compressor outside the flue 6, and a cooling water supplementing pipe orifice and a water extracting pipe orifice; the self-infiltration heat exchange tube bundle in the heat exchange area is communicated with the vapor-liquid isolating bag; a steam pipe at the top of the vapor-liquid separation bag is communicated with an inlet of a vapor compressor, and an outlet of the vapor compressor is communicated with a steam main pipe; the bottom of the vapor-liquid separation bag is communicated with the inlet of a circulating pump, the outlet of the circulating pump is communicated with the bottom of the self-soaking heat exchange tube bundle, and the cooling water supplementing pipe orifice is arranged at the inlet of the preheating section 5.
The specific implementation method comprises the following steps:
the inlet air temperature is more than 130 ℃, so the heat exchange area is provided with a three-stage series flow: the positive pressure heat exchange area, the micro-positive pressure heat exchange area and the negative pressure heat exchange area are cooled by 30 ℃ boiler feed water.
Wherein, the gauge pressure of steam generated in the positive pressure heat exchange zone is controlled to be 0.3 MPa; the gauge pressure of steam generated in the micro-positive pressure heat exchange area is controlled to be 0.1 MPa; the gauge pressure of steam generated in the negative pressure heat exchange area is controlled to be-0.045 MPa;
after entering the flue 6, the flue gas sequentially flows through the positive pressure self-infiltration heat exchange tube bundle 31, the micro-positive pressure self-infiltration heat exchange tube 21 and the negative pressure self-infiltration heat exchange tube bundle 11, exchanges heat with boiler feed water in the tube pass of the self-infiltration heat exchange tube bundle, is cooled and enters the water preheating section 5;
boiler feed water enters a tube pass of the water preheating section 5 from a collecting pipe at the bottom of the water preheating section 5, flows out of the top of the water preheating section 5 after heat exchange, flows into the self-soaking heat exchange tube bundle along the b1 and is filled with the self-soaking heat exchange tube bundle, is subjected to heat absorption and vaporization in the tube pass of the self-soaking heat exchange tube bundle to form steam, and the steam enters a steam-liquid isolating bag from the self-soaking heat exchange tube bundle to separate liquid water and then enters a steam compressor;
wherein, the steam at the top of the positive pressure steam-liquid isolating bag 32 is pressurized by the positive pressure steam compressor 33 and then is directly sent to the steam main pipe; the steam at the top of the negative pressure steam-liquid isolating bag 12 is merged from the outlet of the negative pressure steam compressor 13 to the inlet of the micro-positive pressure steam compressor 23 for pressurization and then merged into a steam header pipe;
liquid water at the bottom of the negative-pressure vapor-liquid isolating bag 12 is conveyed to the micro-positive-pressure self-infiltration heat exchange tube bundle 21 along the direction B1-B2 through the circulating pump 14, liquid water at the bottom of the micro-positive-pressure vapor-liquid isolating bag 22 is conveyed to the positive-pressure self-infiltration heat exchange tube bundle 31 along the direction B2-B3 through the circulating pump II 24, the liquid water at the bottom of the positive-pressure vapor-liquid isolating bag 32 is flashed to a micro-positive-pressure heat exchange area through a pressure reducing valve, and the ratio of the online flow rate to the evaporation capacity of boiler feed water is 1.3: 1;
the boiler feed water is continuously supplemented from the water preheating section 5, the supplementing quantity is larger than the evaporation quantity, and the liquid water left by evaporation is discharged from a cooling water extraction pipe orifice at the bottom of the positive pressure steam-liquid isolating bag 32 along the direction B3.
TABLE 2 refined smoke gas intake parameter table
The refined flue gas finally flows through a water preheating section 5 to be further cooled to 80 ℃, and the total amount of recoverable steam is not less than 8500 kg/h.
The cooling flue gas gets into desulphurization unit and carries out wet flue gas desulfurization, and the flue gas gets into and purifies white cigarette unit that disappears after the desulfurization, and the white cigarette unit main equipment that purifies that disappears includes: a spray tower 7, a membrane demister 8 and a flue gas reheater 9; wherein, the upper part in the spray tower 7 is provided with a cooling spray device, and the lower part is provided with a tower tray; the space in the tower outside the cooling and spraying device is communicated with the gas side of a membrane demister 8, the membrane demister 8 is communicated with a chimney, and a flue gas reheater 9 is arranged between the membrane demister 8 and the inlet of the chimney;
wherein membrane defroster 8 sets up inside spray tower 7, and both merge into a monomer equipment, and membrane defroster 8 is located cooling atomizer's top, sets up buffering baffling baffle between membrane defroster 8 and the spray tower 7 in order to keep apart the water droplet that the flue gas wrapped up in the area.
The temperature of the cooled flue gas is reduced to 52 ℃ after wet desulphurization, the desulfurized flue gas enters a spray tower 7, the temperature is reduced to 45 ℃ by spraying, and the spraying water quantity of the spray tower 7 is 233m3The particle size of fog drops is 20-400 mu m, the partial pressure of steam in the flue gas is reduced to 9.6kPa, and the temperature of spray water is increased from 33 ℃ to 51 ℃; the sprayed flue gas enters a membrane demister 8 to remove entrained water mist, the membrane demister 8 is a box-type component of a 50nm tubular ceramic membrane, and the transmembrane pressure difference is 0.02 MPa; the low-temperature saturated gas obtained by the membrane demister 8 is heated to 65 ℃ by a flue gas reheater 9, the relative humidity is reduced to 39%, and the gas is discharged through a chimney.
Example 3
As shown in FIG. 4, the treatment process for deep heat collection and purification of flue gas is used for treating the flue gas of a coking plant and comprises a waste heat recovery unit, a desulfurization unit and a white smoke purification and elimination unit, wherein the coking flue gas parameters are shown in Table 3.
The waste heat recovery unit device includes: the system comprises a heat exchange area, a circulating pump and a water preheating section 5, wherein the heat exchange area consists of a self-infiltration heat exchange tube bundle taking a tube pass in a flue 6 as cooling water, a vapor-liquid isolating bag and a vapor compressor outside the flue 6, and a cooling water supplementing pipe orifice and a water extracting pipe orifice; the self-infiltration heat exchange tube bundle in the heat exchange area is communicated with the vapor-liquid isolating bag; a steam pipe at the top of the vapor-liquid separation bag is communicated with an inlet of a vapor compressor, and an outlet of the vapor compressor is communicated with a steam main pipe; the bottom of the vapor-liquid isolating bag is communicated with the inlet of a circulating pump, the outlet of the circulating pump is communicated with a connecting pipeline between the self-soaking heat exchange tube bundle and the vapor-liquid isolating bag, and the cooling water supplementing pipe orifice is arranged at the inlet of the water preheating section 5;
the specific implementation method comprises the following steps:
the inlet air temperature is more than 130 ℃, so the heat exchange area is provided with a three-stage series flow: the positive pressure heat exchange area, the micro-positive pressure heat exchange area and the negative pressure heat exchange area are cooled by 30 ℃ boiler feed water.
Wherein, the gauge pressure of steam generated in the positive pressure heat exchange zone is controlled to be 0.3 MPa; the gauge pressure of steam generated in the micro-positive pressure heat exchange area is controlled to be 0.05 MPa; the gauge pressure of steam generated in the negative pressure heat exchange area is controlled to be-0.055 MPa;
after entering the flue 6, the flue gas sequentially flows through the positive pressure self-infiltration heat exchange tube bundle 31, the micro-positive pressure self-infiltration heat exchange tube 21 and the negative pressure self-infiltration heat exchange tube bundle 11, exchanges heat with boiler feed water in the tube pass of the self-infiltration heat exchange tube bundle, is cooled and enters the water preheating section 5;
boiler feed water enters a tube pass of the water preheating section 5 from a collecting pipe at the bottom of the water preheating section 5, flows out of the top of the water preheating section 5 after heat exchange, flows into the self-soaking heat exchange tube bundle along the b1 and is filled with the self-soaking heat exchange tube bundle, is subjected to heat absorption and vaporization in the tube pass of the self-soaking heat exchange tube bundle to form steam, and the steam enters a steam-liquid isolating bag from the self-soaking heat exchange tube bundle to separate liquid water and then enters a steam compressor;
wherein, the steam at the top of the positive pressure steam-liquid separation bag 32 is directly sent to the steam main pipe; the steam at the top of the negative pressure steam-liquid isolating bag 12 is merged from the outlet of the negative pressure steam compressor 13 to the inlet of the micro-positive pressure steam compressor 23 for pressurization and then merged into a steam header pipe;
liquid water at the bottom of the negative-pressure steam-liquid isolating bag 12 is conveyed to a connecting pipeline between the micro-positive-pressure self-infiltration heat exchange tube bundle 21 and the micro-positive-pressure steam-liquid isolating bag 22 along the B1-B2 direction through a circulating pump 14, the liquid water at the bottom of the micro-positive-pressure steam-liquid isolating bag 22 is conveyed to the connecting pipeline between the positive-pressure self-infiltration heat exchange tube bundle 31 and the positive-pressure steam-liquid isolating bag 32 along the B2-B3 direction through a circulating pump II 24, the liquid water at the bottom of the positive-pressure steam-liquid isolating bag 32 is flashed to the connecting pipeline between the micro-positive-pressure self-infiltration heat exchange tube bundle 21 and the micro-positive-pressure steam-liquid isolating bag 22 through a pressure reducing valve, and the ratio of the on;
the boiler feed water is continuously supplemented from the water preheating section 5, the supplementing quantity is larger than the evaporation quantity, and the liquid water left by evaporation is discharged from a cooling water extraction pipe orifice at the bottom of the positive pressure steam-liquid isolating bag 32 along the direction B3.
TABLE 3 coking fume gas intake parameter table
The coking flue gas finally flows through a water preheating section 5 to be further cooled to 75 ℃, and the total amount of recoverable steam is not less than 3600 kg/h.
The cooling flue gas gets into desulphurization unit and carries out wet flue gas desulfurization, and the flue gas gets into and purifies white cigarette unit that disappears after the desulfurization, and the white cigarette unit main equipment that purifies that disappears includes: a spray tower 7, a membrane demister 8 and a flue gas reheater 9; wherein, the upper part in the spray tower 7 is provided with a cooling spray device, and the lower part is provided with a tower tray; the space in the tower outside the cooling and spraying device is communicated with the gas side of the membrane demister 8, the membrane demister 8 is communicated with the chimney, and a flue gas reheater 9 is arranged between the membrane demister 8 and the inlet of the chimney.
The temperature of the cooled flue gas is reduced to 60 ℃ after wet desulphurization, the desulfurized flue gas enters a spray tower 7, the temperature is reduced to 50 ℃ by spraying, and the spraying water quantity of the spray tower 7 is 188m3The particle size of the fog drops is 30-500 mu m, and the temperature of spray water is raised from 33 ℃ to 58 ℃; the sprayed flue gas enters a membrane demister 8 to remove entrained water mist, the membrane demister 8 is connected in series in two stages, a 200nm organic membrane bundle integrated module is adopted, and transmembrane pressure difference is 0.02 MPa; the low-temperature saturated gas obtained by the membrane demister 8 is heated to 75 ℃ by a flue gas reheater 9, the relative humidity is reduced to 39%, and the low-temperature saturated gas is discharged through a chimney.
Example 4
As shown in FIG. 5, a process for deep heat recovery and purification of flue gas, which is used for treating flue gas of a coal-fired boiler, comprises a waste heat recovery unit, a desulfurization unit and a white smoke purification unit, wherein the parameters of the flue gas of the coal-fired boiler are shown in Table 4.
The waste heat recovery unit device includes: the system comprises a heat exchange area, a circulating pump and a preheating section 5, wherein the heat exchange area consists of a self-infiltration heat exchange tube bundle with a tube pass of cooling water in a flue 6, a vapor-liquid isolating bag and a vapor compressor outside the flue 6, and a cooling water supplementing pipe orifice and a cooling water extracting pipe orifice; the self-infiltration heat exchange tube bundle in the heat exchange area is communicated with the vapor-liquid isolating bag; a steam pipe at the top of the vapor-liquid separation bag is communicated with an inlet of a vapor compressor, and an outlet of the vapor compressor is communicated with a steam main pipe; the bottom of the vapor-liquid isolating bag is communicated through a pipeline, the outlet of the circulating pump is communicated with a connecting pipeline between the self-soaking heat exchange tube bundle and the vapor-liquid isolating bag, and the cooling water supplementing pipe orifice is arranged at the inlet of the water preheating section 5;
the specific implementation method comprises the following steps:
the inlet air temperature is more than 130 ℃, so the heat exchange area is provided with a three-stage series flow: the positive pressure heat exchange area, the micro-positive pressure heat exchange area and the negative pressure heat exchange area are cooled by 30 ℃ boiler feed water.
Wherein, the gauge pressure of steam generated in the positive pressure heat exchange zone is controlled to be 0.35 MPa; the gauge pressure of steam generated in the micro-positive pressure heat exchange area is controlled to be 0.05 MPa; the gauge pressure of steam generated in the negative pressure heat exchange area is controlled to be-0.055 MPa;
after entering the flue 6, the flue gas sequentially flows through the positive pressure self-infiltration heat exchange tube bundle 31, the micro-positive pressure self-infiltration heat exchange tube 21 and the negative pressure self-infiltration heat exchange tube bundle 11, exchanges heat with boiler feed water in the tube pass of the self-infiltration heat exchange tube bundle, is cooled and enters the water preheating section 5;
boiler feed water enters a tube pass of the water preheating section 5 from a collecting pipe at the bottom of the water preheating section 5, flows out of the top of the water preheating section 5 after heat exchange, and is sent to a connecting pipeline of a self-infiltration heat exchange tube bundle and a vapor-liquid isolating bag through a circulating pump 14, so that the boiler feed water is filled in the self-infiltration heat exchange tube bundle and is subjected to heat absorption and vaporization in the tube pass of the self-infiltration heat exchange tube bundle to form steam, and the steam enters the vapor-liquid isolating bag from the self-infiltration heat exchange tube bundle to separate liquid water and then enters a vapor;
wherein, the steam at the top of the positive pressure steam-liquid separation bag 32 is directly sent to the steam main pipe; the steam at the top of the negative pressure steam-liquid isolating bag 12 is merged from the outlet of the negative pressure steam compressor 13 to the inlet of the micro-positive pressure steam compressor 23 for pressurization and then merged into a steam header pipe;
liquid water at the bottom of the positive pressure steam-liquid isolating bag 32 is flashed to a micro positive pressure heat exchange area along the direction A3-a2 through a pressure reducing valve, liquid water at the bottom of the micro positive pressure steam-liquid isolating bag 22 is flashed to a negative pressure heat exchange area along the direction A2-a1 through a pressure reducing valve, and the liquid water at the bottom of the negative pressure steam-liquid isolating bag 12 is converged with preheated boiler feed water along the direction A1 and then is conveyed to a connecting pipeline between the positive pressure self-soaking heat exchange tube bundle 31 and the positive pressure steam-liquid isolating bag 32 along the direction A3 through a circulating pump 14; the ratio of the on-line flow rate of the boiler feed water to the evaporation capacity is 1.8: 1;
the boiler feed water is continuously supplemented from the water preheating section 5, the supplementing quantity is larger than the liquid evaporation quantity, and the liquid water left after evaporation is discharged from a cooling water outlet pipe orifice at the bottom of the negative pressure steam-liquid isolating bag 12 along the direction A1.
TABLE 4 gas inlet parameter table for coal-fired boiler
The coal-fired boiler flue gas finally flows through the preheating section 5 to be further cooled to 75 ℃, and the total amount of recoverable steam is not less than 12300 kg/h.
The cooling flue gas gets into desulphurization unit and carries out wet flue gas desulfurization, and the flue gas gets into and purifies white cigarette unit that disappears after the desulfurization, and the white cigarette unit main equipment that purifies that disappears includes: a spray tower 7, a membrane demister 8 and a flue gas reheater 9; wherein, the upper part in the spray tower 7 is provided with a cooling spray device, and the lower part is provided with a tower tray; the space in the tower outside the cooling and spraying device is communicated with the gas side of the membrane demister 8, the membrane demister 8 is communicated with the chimney, and a flue gas reheater 9 is arranged between the membrane demister 8 and the inlet of the chimney.
The temperature of the cooled flue gas is reduced to 45 ℃ after wet desulphurization, the desulfurized flue gas enters a spray tower 7, the temperature is reduced to 38 ℃ by spraying, and the spraying water quantity of the spray tower 7 is 201m3The particle size of the fog drops is 150-300 mu m, and the temperature of spray water is increased from 19 ℃ to 43 ℃; the sprayed flue gas enters a membrane demister 8 to remove entrained water mist, the membrane demister 8 adopts a 1000nm flat ceramic membrane, and the transmembrane pressure difference is 0.03 MPa; the low-temperature saturated gas obtained by the membrane demister 8 is heated to 65 ℃ by a flue gas reheater 9, the relative humidity is reduced to 27%, and the gas is discharged through a chimney.
Although the present invention has been described with reference to the preferred embodiments, it should be understood that they are not intended to limit the scope of the invention, but rather, that various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention.
Claims (14)
1. The treatment process for deeply receiving and purifying the flue gas is characterized by comprising three units, namely a waste heat recovery unit, a desulfurization unit and a white smoke purification unit:
the flue gas passes through a waste heat recovery unit to obtain cooled flue gas, the cooled flue gas passes through a desulfurization unit to obtain desulfurized flue gas, and the desulfurized flue gas enters a chimney through a white smoke purification and elimination unit to be discharged;
wherein the waste heat recovery unit includes: a heat exchange zone, a circulation pump (14), and a water preheating zone (5); the heat exchange area comprises a negative pressure self-infiltration heat exchange tube bundle (11) which is arranged in the flue (6) and has a tube pass of cooling water, a negative pressure vapor-liquid isolating bag (12) outside the flue (6), a negative pressure vapor compressor (13), a cooling water supplementing tube orifice and a extracting tube orifice;
the cooling water heat exchange loop comprises: cooling water in the waste heat recovery unit enters a tube pass from a collecting pipe at the bottom of the water preheating section (5), flows out from the top of the water preheating section (5) after heat exchange, enters a cooling water replenishing pipe orifice of a heat exchange area, absorbs heat and vaporizes to form steam, enters a negative pressure steam-liquid isolating bag (12) from the tube pass of the negative pressure self-infiltration heat exchange tube bundle (11) to separate liquid water, and enters a steam main pipe after being pressurized by a negative pressure steam compressor (13);
the flue gas heat exchange loop is as follows: after entering a flue (6), flue gas in the waste heat recovery unit flows through a negative pressure self-soaking heat exchange tube bundle (11) in a heat exchange area, is cooled after exchanging heat with cooling water, and finally flows through a water preheating section (5) to be further cooled and then enters a desulfurization unit;
the negative pressure self-infiltration heat exchange tube bundle (11) in the heat exchange area is communicated with the negative pressure vapor-liquid isolating bag (12); a steam pipe at the top of the negative pressure steam-liquid isolating bag (12) is communicated with an inlet of a negative pressure steam compressor (13), and an outlet of the negative pressure steam compressor (13) is communicated with a steam main pipe; the cooling water supplementing pipe orifices are arranged at one or more positions in a negative pressure steam-liquid isolating bag (12), a connecting pipeline of the negative pressure self-infiltration heat exchange pipe bundle (11) and the negative pressure steam-liquid isolating bag (12), and a collecting pipe of the negative pressure self-infiltration heat exchange pipe bundle (11);
the steam pressures at the three positions of the negative pressure self-infiltration heat exchange tube bundle (11), the negative pressure steam-liquid isolating bag (12) and the inlet of the negative pressure steam compressor (13) are consistent, so that the three parts form a heat exchange area under independent working conditions; when the heat exchange area exceeds one stage, the steam pressure of each stage is different, and a multi-stage series heat exchange process is formed;
the multistage series heat exchange process of the heat exchange zone comprises the following steps: the cooling water is boiler feed water with the temperature lower than 33 ℃; the heat exchange area comprises a negative pressure heat exchange area, the corresponding steam gauge pressure is-0.06-0 MPa, and the multistage serial heat exchange process of the heat exchange area comprises the following steps: the method comprises the step of additionally arranging a micro-positive pressure heat exchange area in front of a negative pressure heat exchange area, wherein the corresponding steam gauge pressure is between 0 and 0.25 MPa.
2. The treatment process for deep heat collection and purification of flue gas according to claim 1, wherein a cooling water circulating pump (14) is arranged in a cooling water heat exchange loop, liquid cooling water enters an inlet of the circulating pump (14) from the bottom of the negative pressure steam-liquid isolating bag (12), is pressurized by the circulating pump (14), is then merged with preheated cooling water, and is sent to a cooling water supplementing pipe orifice of the heat exchange area.
3. The process for the deep heat collection and purification of flue gas as claimed in claim 1, wherein the multi-stage series heat exchange process of the heat exchange zone comprises: in the cooling water heat exchange loop of the heat exchange zone, liquid water at the bottom of the highest-pressure vapor-liquid isolating bag is subjected to pressure reduction and flash evaporation step by step through a pressure reducing valve to reach a next-stage heat exchange zone; liquid water in the negative pressure heat exchange area is pressurized by a circulating pump (14) and is converged with the preheated cooling water, and the liquid water is conveyed to a cooling water supplementing pipe orifice of the highest pressure positive pressure heat exchange area.
4. The process for the deep heat collection and purification of flue gas as claimed in claim 1, wherein the multi-stage series heat exchange process of the heat exchange zone comprises: in the cooling water heat exchange loop, liquid water at the bottom of the low-pressure vapor-liquid isolating bag is pressurized step by step to a previous stage heat exchange area through a circulating pump; liquid water in the highest pressure positive pressure heat exchange area is flashed to a cooling water replenishing pipe orifice of at least one lower pressure heat exchange area through a pressure reducing valve.
5. The process for the deep heat collection and purification of flue gas as claimed in claim 1, wherein the multi-stage series heat exchange process of the heat exchange zone comprises: in the cooling water heat exchange loop, steam at the top of the vapor-liquid isolating bag in the multi-stage heat exchange area flows to the outlet of the compressor with lower pressure and is combined to the inlet of the compressor with higher stage, and then the steam is conveyed to the steam main pipe.
6. The process for the deep heat collection and purification of flue gas as claimed in claim 1, wherein the multi-stage series heat exchange process of the heat exchange zone comprises: in the cooling water heat exchange loop, steam at the top of the vapor-liquid isolating bag in the multi-stage heat exchange area is directly pressurized by the compressor through the vapor compressor and then is conveyed to the steam header pipe.
7. The treatment process for deep heat collection and purification of flue gas as claimed in claim 2, wherein the ratio of the online circulation flow rate to the evaporation capacity of cooling water is (1.01-3): 1.
8. the treatment process for deep heat collection and purification of flue gas as claimed in claim 7, wherein the ratio of the online circulation flow rate to the evaporation capacity of cooling water is (1.2-2): 1.
9. the process according to claim 1, wherein the cooling water is continuously supplemented from the preheating section, the supplement amount is larger than the evaporation amount, and the liquid water left after evaporation is discharged from the cooling water outlet pipe orifice.
10. The treatment process for deep heat collection and purification of flue gas as claimed in claim 1, wherein the purification and white smoke elimination unit comprises a spray tower (7), a membrane demister (8) and a flue gas reheater (9) which are connected in sequence; a cooling spraying device is arranged at the upper part in the spraying tower (7), and a tower tray is arranged at the lower part; a hydrophilic microporous membrane is arranged in the membrane demister (8); the membrane demister (8) is divided into a gas side which is on one side of the membrane surface and is contacted with the flue gas and a liquid side which is on one side of the back surface and is not contacted with the flue gas by the hydrophilic microporous membrane, the gas side passes through the sprayed flue gas containing fog drops, and the liquid side is provided with a pipeline opening which is used for introducing water for infiltrating the membrane, extracting and collecting the water formed by the fog drops and maintaining the pressure of the liquid side to be lower than the pressure of the flue gas; the space in the spray tower (7) except the cooling and spraying device is communicated with the air side of a membrane demister (8), the air side of the membrane demister (8) is communicated with a chimney, and a flue gas reheater (9) is arranged between the membrane demister (8) and the inlet of the chimney;
cooling water enters a cooling spraying device on the upper part of a spraying tower (7), a part of cooling water is collected on a tower tray on the lower part of the spraying tower (7) and then discharged, and the rest of cooling water is collected on the liquid side of a membrane demister (8) and then discharged through a set pipeline port to form a spraying and mist collecting loop of the cooling water;
the desulfurized flue gas from the desulfurization unit is cooled and washed in a spray tower (7), fog drops and micro-foam are removed from the flue gas side of a membrane demister (8) to obtain low-temperature saturated gas, the low-temperature saturated gas is heated into unsaturated flue gas by a flue gas reheater (9), and the unsaturated flue gas is finally discharged from a chimney to form a flue gas purification and white smoke elimination loop of the flue gas.
11. The deep heat collection and purification treatment process for the flue gas as claimed in claim 10, wherein the cooling and spraying device at the upper part of the spraying tower (7) adopts industrial cooling water spraying, the generated fog drops have the particle size of 20-400 μm, the tray at the bottom is one or two of a float valve tray and a bubble cap tray, and the flue gas enters the spraying tower (7), firstly passes through the tray at the bottom and then is in countercurrent contact with the spraying.
12. The process for deeply receiving and purifying the smoke according to claim 10, wherein the pore diameter of the hydrophilic microporous membrane is 5-4000 nm, the structural shape of the hydrophilic microporous membrane is one or more of tubular, plate-shaped, honeycomb-shaped and hollow fibers, and the hydrophilic microporous membrane is made of an organic or inorganic material with a contact angle with water of less than 75 degrees.
13. The process for the deep recovery and purification of flue gases according to claim 10, wherein the heat source of the flue gas reheater (9) comprises steam generated by front end waste heat recovery.
14. The process of deep heat collection and purification of flue gas according to claim 10, wherein the flue gas purification white smoke elimination loop comprises a membrane demister (8) arranged inside the spray tower (7), the membrane demister (8) and the spray tower are combined into a single unit, the membrane demister (8) is arranged above the cooling spray device, and a buffering baffle plate is arranged between the membrane demister (8) and the cooling spray device to isolate water drops carried by the flue gas.
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| JP7356345B2 (en) * | 2019-12-27 | 2023-10-04 | 三菱重工業株式会社 | Exhaust gas treatment equipment and gas turbine plants |
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