CN113058371B - Device and method for removing fine particulate matters by coupling reflux turbulence agglomeration with water vapor phase change - Google Patents
Device and method for removing fine particulate matters by coupling reflux turbulence agglomeration with water vapor phase change Download PDFInfo
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- CN113058371B CN113058371B CN202110276654.7A CN202110276654A CN113058371B CN 113058371 B CN113058371 B CN 113058371B CN 202110276654 A CN202110276654 A CN 202110276654A CN 113058371 B CN113058371 B CN 113058371B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D51/00—Auxiliary pretreatment of gases or vapours to be cleaned
- B01D51/02—Amassing the particles, e.g. by flocculation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
- B01D46/10—Particle separators, e.g. dust precipitators, using filter plates, sheets or pads having plane surfaces
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
- B01D46/66—Regeneration of the filtering material or filter elements inside the filter
- B01D46/70—Regeneration of the filtering material or filter elements inside the filter by acting counter-currently on the filtering surface, e.g. by flushing on the non-cake side of the filter
- B01D46/72—Regeneration of the filtering material or filter elements inside the filter by acting counter-currently on the filtering surface, e.g. by flushing on the non-cake side of the filter with backwash arms, shoes or nozzles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D51/00—Auxiliary pretreatment of gases or vapours to be cleaned
- B01D51/10—Conditioning the gas to be cleaned
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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
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
- Y02A50/2351—Atmospheric particulate matter [PM], e.g. carbon smoke microparticles, smog, aerosol particles, dust
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Abstract
The invention discloses a device and a method for removing fine particulate matters by coupling reflux type turbulence agglomeration with water vapor phase change, which can solve the problems that wet flue gas desulfurization of a coal-fired power plant contains a large amount of PM2.5, which is not easy to be removed by conventional dust removal equipment, and the direct discharge is easy to cause air pollution. The device comprises a phase change removal tower, wherein the lower part of the phase change removal tower is provided with a flue gas inlet, and the top of the phase change removal tower is provided with a flue gas outlet; a first turbulence generator, a cooling heat exchanger, a second turbulence generator, a wire mesh demister and a flushing water system are sequentially arranged in an inner cavity of the phase change removal tower from bottom to top; a flue gas reflux pipeline is arranged on the outer side of the phase change removal tower and comprises a flue gas reflux section, the top end of the flue gas reflux pipeline is a flue gas reflux inlet, and the bottom end of the flue gas reflux pipeline is a flue gas reflux outlet; an air extracting pump is arranged in the flue gas reflux section; the flue gas backward flow entry is located between second turbulence generator and the silk screen defroster, and the flue gas backward flow export is located first turbulence generator below.
Description
Technical Field
The invention belongs to the technical field of emission control of fine particulate matters PM2.5 in coal-fired flue gas, and particularly relates to a device and a method for removing fine particulate matters by coupling reflux turbulence agglomeration with water-vapor phase change.
Background
PM2.5 refers to particles with a kinetic equivalent diameter of 2.5 microns or less in ambient air. It can be suspended in air for a long time. It not only causes serious atmospheric pollution to the environment, but also enters the human body along with the respiration of the human body, thereby causing a plurality of diseases such as arrhythmia, arteriosclerosis, myocardial infarction and the like. Analysis and research on PM2.5 sources show that the fine particulate matter PM2.5 discharged by coal is one of the main sources, so that the control of the discharge of the fine particulate matter in the coal-fired power plant is particularly important.
At present, the fine particle removal technology of the coal-fired power plant is mainly divided into two types: a novel high-efficiency dust removal technology and an agglomeration promotion technology. The novel high-efficiency dust removal technology comprises a low-temperature electrostatic dust removal technology, a wet-type electric dust removal technology, an electric bag composite dust removal technology and the like. These dedusting techniques are highly effective for mass removal of total dust but are not effective for the removal of the number of small particle size particles. The agglomeration promoting technology mainly comprises the following steps: acoustic agglomeration, electric coagulation, turbulent agglomeration, chemical agglomeration, water vapor phase change and the like. The idea of the technology is to agglomerate and grow fine particles into large particles which can be trapped by the existing dust removal equipment through physical or chemical action, thereby realizing the high-efficiency removal of the fine particles. At present coal fired power plant generally installs wet flue gas desulfurization device (WFGD), and flue gas is close saturated state basically through wet flue gas desulfurization back flue gas humidity, and the vapor that can make in the flue gas through the heat exchanger cooling with the flue gas this moment is in the oversaturated state to realize the structure in oversaturated field, impel steam to condense at the fine particle surface heterogeneous.
According to Fletcher heterogeneous nucleation theory, the smaller the particle size of the fine particles, the greater the critical supersaturation required for heterogeneous condensation of water vapor on the particle surface. The particle size of the fine particles in the flue gas after wet flue gas desulfurization is less, needs bigger supersaturation just can take place heterogeneous and condense, but the supersaturation that founds after conventional heat exchanger is to the flue gas cooling is less, leads to the supersaturation field that conventional heat exchanger cooling found can not reach the requirement that the granule grows up. This patent proposes after the extraction heat exchanger partly long contain granule liquid drop before to the heat exchanger with the flue gas entry new fine particle collision coagulation that gets into, increase the granule particle diameter that gets into the supersaturated field that the heat exchanger founded to can reach fine heterogeneous condensation effect under lower supersaturation.
In order to promote the collision and coalescence between the wetting particles in the backflow flue gas and the fine particles entering from the flue gas inlet, a turbulence generator is arranged behind the backflow outlet, and the agglomeration and growth effects among the particles are promoted through the turbulence agglomeration effect; secondly, a turbulence generator is also arranged after the heat exchanger, so as to promote agglomeration among the wetted particles at the outlet of the heat exchanger through turbulence.
Disclosure of Invention
The technical problem is as follows: the invention provides a device and a method for removing fine particles by coupling reflux turbulent flow agglomeration with water vapor phase change, aiming at the problems that the wet flue gas desulfurization of a coal-fired power plant contains a large amount of PM2.5 which is difficult to remove by conventional dust removal equipment and is easy to cause atmospheric pollution by direct discharge.
The technical scheme is as follows: in order to solve the technical problem, the invention adopts the following technical scheme:
in a first aspect, an embodiment of the present invention provides a device for removing fine particulate matters by coupling reflux turbulent agglomeration with water vapor phase change, including a phase change removal tower, wherein a flue gas inlet is arranged at the lower part of the phase change removal tower, and a flue gas outlet is arranged at the top of the phase change removal tower; a first turbulence generator, a cooling heat exchanger, a second turbulence generator, a wire mesh demister and a flushing water system are sequentially arranged in an inner cavity of the phase change removal tower from bottom to top; a flue gas reflux pipeline is arranged on the outer side of the phase change removal tower and comprises a flue gas reflux section, the top end of the flue gas reflux pipeline is a flue gas reflux inlet, and the bottom end of the flue gas reflux pipeline is a flue gas reflux outlet; an air extracting pump is arranged in the flue gas reflux section; the flue gas backward flow entry is located between second turbulence generator and the silk screen defroster, and the flue gas backward flow export is located first turbulence generator below.
Preferably, the cooling heat exchanger includes a cooling medium inlet and a cooling medium outlet, and the cooling medium inlet is located above the cooling medium outlet.
Preferably, the washing water system comprises a distributor, a water inlet pipe and a control valve, the distributor is communicated with the water inlet pipe, and the control valve is positioned on the water inlet pipe; the distributor consists of a plurality of water pipes, water distribution holes of 0.1-2 mm are uniformly distributed on the water pipes, and flushing water is sprayed out of the water distribution holes.
Preferably, the cross-sectional area of the first turbulence generator, the cross-sectional area of the second turbulence generator and the cross-sectional area of the wire mesh demister are respectively equal to the cross-sectional area of the phase-change removal tower; the water distribution area of the flushing water system is equal to the cross-sectional area of the phase change removal tower.
Preferably, the number of the flue gas return pipelines is 2-6, and the flue gas return pipelines are uniformly distributed on the outer wall surface of the phase-change removal tower.
Preferably, the first turbulence generator comprises two layers of triangular turbulence bars, the material of the turbulence bars is carbon steel, and the surfaces of the turbulence bars are subjected to anti-abrasion treatment and coated with PTFE coatings; the second turbulence generator has the same structure and material as the first turbulence generator.
Preferably, the material of the flue gas return pipeline is hydrophobic material, and the outer surface of the flue gas return pipeline is provided with a heat insulation layer; the heat-insulating layer is divided into two layers, wherein the inner layer is an aluminum silicate blanket, and the outer layer is a rock wool seam felt; the distance between the flue gas backflow inlet and the second turbulence generator is 1500-2000 mm, and the distance between the flue gas backflow outlet and the first turbulence generator is 200-300 mm.
Preferably, the device still includes the waste liquid collecting pit, and the waste liquid collecting pit is located the bottom of phase transition desorption tower, the waste liquid collecting pit includes delivery pipe and valve, and the valve is used for controlling the waste water of waste liquid collecting pit collection and passes through the delivery pipe and discharge.
In a second aspect, an embodiment of the present invention further provides a method for removing fine particulate matters by coupling reflux turbulence agglomeration with water vapor phase change, including the following steps:
step 10) saturated flue gas at an outlet of a desulfurization tower is discharged into a flue gas inlet of a phase change removal tower, the saturated flue gas flows from bottom to top in the phase change removal tower, passes through a first turbulence generator and a cooling heat exchanger, the flue gas is cooled to form supersaturation, steam is condensed on the surface of fine particles, then passes through a second turbulence generator to form turbulence, agglomeration among wet particles is promoted to grow, and finally the agglomerated and grown particles are removed by a wire mesh demister;
while the process is carried out, adjusting the air suction pump on the flue gas return pipeline to ensure that the flue gas at the outlet of the second turbulence generator flows back to the front of the first turbulence generator, wherein the returned flue gas contains part of the grown wet particles; the backflow flue gas contains part of grown wetting particles and the fine particles newly entering the flue gas inlet together pass through the first turbulence generator to generate turbulence, so that the newly entering fine particles are promoted to collide and coalesce with the wetting particles in the backflow flue gas to form grown particles, and the grown particles enter a supersaturated field constructed by the cooling heat exchanger to realize heterogeneous condensation of water vapor on the surfaces of the particles;
and 20) cleaning the fine particles collected by the wire mesh demister by using a washing water system, and discharging the cleaned waste liquid through a discharge pipe after the waste liquid flows into a waste liquid collecting tank.
Preferably, the air suction pump on the flue gas return pipeline is adjusted, so that the sum of the return flue gas amount of the return pipeline is controlled to be 20-80% of the flue gas inlet flow amount before the flue gas at the outlet of the second turbulence generator flows back to the first turbulence generator.
Has the advantages that: compared with the prior art, the device has the advantages of simple structure, no complex structural device and low cost, couples two fine particle agglomeration technologies of turbulent flow agglomeration and water vapor phase change, has high applicability to nearly saturated flue gas, and not only the fine particles in the flue gas grow up due to water vapor phase change agglomeration, but also the collision rate among the particles is obviously increased through turbulent flow. Meanwhile, a return pipeline is arranged to return part of the flue gas to the front of the heat exchanger, so that the particle size of the particles entering a supersaturated field constructed by the heat exchanger is increased, and the particles can grow up well under a lower supersaturation degree. The problem that when the particle size is small, the critical supersaturation degree required by the heterogeneous condensation of water vapor on the surface of fine particles is large, but the supersaturation degree of a supersaturation field constructed by cooling flue gas by a conventional heat exchanger is small, and the requirement of particle growth cannot be met is solved.
Drawings
Fig. 1 is a structural view of a phase-change removal column of the present invention.
In the figure: 1. flue gas entry, 2, first turbulence generator, 3, cooling heat exchanger, 4, second turbulence generator, 5, silk screen defroster, 6, wash water system, 7, exhanst gas outlet, 8, flue gas backward flow entry, 9, flue gas backward flow section, 10, aspiration pump, 11, heat preservation, 12, flue gas backward flow export, 13, cooling medium entry, 14, cooling medium export, 15, waste liquid collecting pit, 16, delivery pipe, 17, valve.
Detailed Description
To further clarify the disclosure of the present invention, a more particular description of the invention will be rendered by reference to the appended drawings.
As shown in fig. 1, the device for removing fine particulate matters by coupling reflux turbulent agglomeration with water vapor phase change comprises a phase change removal tower, wherein a flue gas inlet 1 is arranged at the lower part of the phase change removal tower, and a flue gas outlet 7 is arranged at the top of the phase change removal tower. Preferably, the central axis of the flue gas outlet 7 coincides with the central axis of the phase-change removal tower. Flue gas entry 1 can be located phase transition desorption tower bottom side, and phase transition desorption tower is stretched out to the one end of flue gas entry 1. From down upwards being equipped with first turbulence generator 2, cooling heat exchanger 3, second turbulence generator 4, silk screen defroster 5 and sparge water system 6 in proper order in the inner chamber of phase transition desorption tower. A flue gas reflux pipeline is arranged on the outer side of the phase change removal tower and comprises a flue gas reflux section 9, the top end of the flue gas reflux pipeline is a flue gas reflux inlet 8, and the bottom end of the flue gas reflux pipeline is a flue gas reflux outlet 12; an air extracting pump 10 is arranged in the flue gas reflux section 9; the flue gas return inlet 8 is located between the second turbulence generator 4 and the wire mist eliminator 5 and the flue gas return outlet 12 is located below the first turbulence generator 2.
In the device, the inner surface of the phase change removal tower is made of polytetrafluoroethylene materials, so that water vapor can be prevented from being condensed on the inner surface, unnecessary dissipation of the water vapor is avoided, the supersaturation degree in the tower is improved, and meanwhile, the corrosion resistance effect is also achieved. The cooling heat exchanger 3 is made of a fluorine steel pipe, has good pressure resistance, bending resistance and plasticity, and is suitable for a low-temperature acid-corrosive working environment. The smoke return pipeline is provided with an air pump 10 for controlling the amount of the returned smoke.
The invention provides a device for removing fine particles by coupling reflux turbulence agglomeration and water vapor phase change. And the inlet of the phase-change removal tower is connected with the flue gas outlet of the desulfurization tower. The bottom of phase transition desorption tower has flue gas entry 1, and there is flue gas outlet 7 at the top, and the flue gas is in the tower from bottom to top flow, passes through first turbulence generator 2, cooling heat exchanger 3, second turbulence generator 4, silk screen defroster 5 and wash water system 6 in proper order, flows out from the flue gas outlet 7 at top at last to there is the return line to flow some flue gas before first turbulence generator 2 behind second turbulence generator 4.
Saturated flue gas that contains the fine particle gets into the phase transition desorption tower from flue gas entry 1, reaches the supersaturated state after the cooling of cooling heat exchanger 3, and then forms heterogeneous condensation on the fine particle surface, and the surface contains between the fine particle of condensate water through mutual collision growing into the large granule, later is got rid of through silk screen mist eliminator 5. In order to promote the heterogeneous condensation of water vapor on the surface of the fine particles, the flue gas after the extraction of part of the cooling heat exchanger 3 collides with and coalesces with the newly introduced fine particles before returning to the cooling heat exchanger 3. This increases the particle size entering the supersaturated field so that at lower supersaturations the water vapour in the flue gas can condense on the particle surface. Meanwhile, turbulence generators are arranged at the front and the rear of the cooling heat exchanger 3, and the first turbulence generator 2 is arranged at the front of the cooling heat exchanger and is used for promoting the collision growth between large particles in the returned flue gas and newly-entered fine particles through turbulence agglomeration; the effect of providing the second turbulence generator 4 after cooling the heat exchanger is to promote collision growth between particles wetted by heterogeneous condensation in the supersaturated field.
Preferably, the distance between the flue gas backflow inlet 8 and the second turbulence generator 4 is 1500-2000 mm, and the distance between the flue gas backflow outlet 12 and the first turbulence generator 2 is 200-300 mm. Flue gas backward flow entry 8 and second turbulence generator 4's distance is bigger because the distance is farther away from second turbulence generator 4, and the particle diameter of granule tends to the definite value after can increasing earlier, and the granule particle diameter is better more in the backward flow flue gas, so flue gas backward flow entry 8 need be in second turbulence generator 4 rear than far away place. The flue gas at the flue gas reflux outlet 12 and the newly-entered flue gas at the flue gas inlet 1 need to be mixed and then enter the cooling heat exchanger 3. Without the first turbulence generator 2 a relatively long distance is needed for mixing, but due to the arrangement of the first turbulence generator 2 the two gas flows are mixed relatively well after passing the first turbulence generator 2, so that the distance of the flue gas return outlet 12 from the first turbulence generator 2 can be short.
Preferably, the cooling heat exchanger 3 comprises a cooling medium inlet 13 and a cooling medium outlet 14, the cooling medium inlet 13 being located above the cooling medium outlet 14. Thus, the cooling medium flows from top to bottom, while the flue gas located in the phase change removal column flows from bottom to top. The relative countercurrent of the flue gas and the cooling medium is beneficial to the cooling medium to fully cool the flue gas and strengthen the heat exchange. Preferably, the cooling medium is cooling water.
Preferably, the washing water system 6 comprises a distributor, a water inlet pipe and a control valve, the distributor is communicated with the water inlet pipe, and the control valve is positioned on the water inlet pipe; the distributor consists of a plurality of water pipes, water distribution holes with the diameter of 0.1-2 mm are uniformly distributed on the water pipes, and flushing water is sprayed out from the water distribution holes. The water sprayed from the water distribution holes can cover the whole wire mesh demister 5. When the control valve is opened, the washing water flows into the water distribution holes of the distributor from the water inlet pipe and flows outwards. The water sprayed from the water distribution holes can cover the whole wire mesh demister.
Preferably, the cross-sectional area of the first turbulence generator 2, the cross-sectional area of the second turbulence generator 4 and the cross-sectional area of the wire mesh demister 5 are respectively equal to the cross-sectional area of the phase-change removal tower. The water distribution area of the flushing water system 6 is equal to the cross-sectional area of the phase change removal tower. The cross-sectional area of the first turbulence generator 2 and the cross-sectional area of the second turbulence generator 4 are equal to the cross-sectional area of the phase-change removal tower to sufficiently achieve turbulence. The cross-sectional area of the wire mesh demister 5 is equal to that of the phase change removal tower, so that the particles can be fully trapped. The cross-sectional area of the washing water system 6 is equal to that of the phase-change removal tower, so that the whole wire mesh demister 5 can be washed sufficiently.
Preferably, the number of the flue gas return pipelines is 2-6, and the flue gas return pipelines are uniformly distributed on the outer wall surface of the phase-change removal tower. For example, 4 flue gas return lines are arranged. A certain number of flue gas return pipelines are reasonably arranged to realize a certain amount of flue gas return.
Preferably, the first turbulence generator 2 comprises two layers of triangular turbulence bars, the material of the turbulence bars is carbon steel, and the surfaces of the turbulence bars are subjected to anti-abrasion treatment and coated with PTFE coatings. This ensures that the turbulator bar is suitable for use in low temperature, acid-corrosive working environments. The second turbulence generator 4 has the same structure and material as the first turbulence generator 2.
Preferably, the material of the flue gas return pipeline is hydrophobic material, and the outer surface of the flue gas return pipeline is provided with a heat insulation layer 11; the heat-insulating layer is divided into two layers, wherein the inner layer is an aluminum silicate blanket, and the outer layer is a rock wool seam felt. This prevents the droplets condensed on the surface of the particles from evaporating to the wall surface, and prevents unnecessary dissipation of water vapor.
Preferably, the device further comprises a waste liquid collecting tank 15, the waste liquid collecting tank 15 is located at the bottom of the phase change removal tower, the waste liquid collecting tank 15 comprises a discharge pipe 16 and a valve 17, and the valve 17 is used for controlling the discharge of the waste water collected by the waste liquid collecting tank 15 through the discharge pipe 16. The waste liquid collecting tank 15 is used for collecting waste water generated after the washing water system 6 washes the wire mesh demister 5 and condensed water cooled in the phase change removal tower.
The working method of the device for removing the fine particles by coupling the reflux type turbulent flow agglomeration and the water-vapor phase change comprises the following steps:
step 10) saturated flue gas at the outlet of the desulfurization tower is discharged into a flue gas inlet 1 of a phase change removal tower, the saturated flue gas flows from bottom to top in the phase change removal tower, passes through a first turbulence generator 2 and a cooling heat exchanger 3, the flue gas is cooled to form supersaturation, steam is condensed on the surface of fine particles, then passes through a second turbulence generator 4 to form turbulence, agglomeration and growth among wet particles are promoted, and finally the agglomerated and grown particles are removed by a wire mesh demister 5;
while the process is carried out, the air suction pump 10 on the flue gas return pipeline is adjusted, so that the returned flue gas contains part of the grown wet particles before the flue gas at the outlet of the second turbulence generator 4 returns to the first turbulence generator 2; the backflow flue gas contains part of grown wetting particles and the fine particles newly entering the flue gas inlet 1 and pass through the first turbulence generator 2 together to generate turbulence, so that the newly entering fine particles are promoted to collide and coalesce with the wetting particles in the backflow flue gas to form grown particles, the grown particles enter a supersaturated field constructed by the cooling heat exchanger 3, and the heterogeneous condensation of water vapor on the surfaces of the particles can be realized only by lower supersaturation degree;
and 20) cleaning the fine particles collected by the wire mesh demister 5 by using a washing water system 6, and discharging the cleaned waste liquid into a waste liquid collecting tank 15 through a discharge pipe 16.
And adjusting the air suction pump 10 on the flue gas return pipeline to control the sum of the returned flue gas amount of the flue gas return pipeline to be 20-80% of the flue gas inlet flow before the flue gas at the outlet of the second turbulence generator 4 flows back to the first turbulence generator 2. For example, when 4 flue gas return pipelines are arranged, the return flue gas amount of each pipe can be controlled to be about 5-20% of the flue gas inlet flow.
When total flue gas reflux is less than flue gas inlet flow 20%, then the reflux flue gas volume is too little, and then the quantity of large granule is also less in the flue gas, and then just also little with the collision probability of the fine particle in the flue gas that flue gas inlet 1 got into, can't form fine reunion and grow up the effect, and then the particle size in supersaturation field after getting into the heat exchanger is also little, just can't form the heterogeneous condensation of ideal under this supersaturation field. If the total smoke reflux is more than 80% of the smoke inlet flow, the smoke flow speed in the tower is too large, the retention time of particles in the tower is very short, and the particles with ideal large and large particle sizes are discharged from the smoke outlet 7.
By using the device, the nucleation and growth of fine particles are promoted by coupling turbulent aggregation and water vapor phase change, and the fine particles are finally removed. In the process, the flue gas with the outlet close to saturation of the desulfurization tower enters the phase-change removal tower through the flue gas inlet 1 of the phase-change removal tower, flows from bottom to top in the phase-change removal tower, is cooled by the cooling heat exchanger 3 to reach an oversaturated state, and at the moment, water vapor in the flue gas is condensed on the surfaces of fine particles; then, the smoke continuously flows upwards, and passes through the second turbulence generator 4, the smoke forms turbulence to increase disturbance, the collision probability among fine particles is increased, and finally the fine particles with larger particle size are agglomerated; meanwhile, the air pump 10 of the flue gas return pipeline is started, and the sum of the return flue gas amount of the return pipeline is controlled to be 20-80% of the flue gas inlet flow by adjusting the power of the air pump 10. The flue gas portion after the second turbulence generator 4 is returned to before the first turbulence generator 2. The main functions of the flue gas reflux are as follows: on one hand, the backflow flue gas contains condensed wet large particles and fine particles entering from the flue gas inlet 1 and are subjected to turbulence agglomeration through the first turbulence generator, so that the fine particles and the large particles are enabled to collide and condense, the particle size of the particles entering a supersaturated field is improved, and therefore, better effect can be achieved due to heterogeneous condensation under lower supersaturation; the second aspect is that the flue gas is cooled for the second time, so that the supersaturation degree in the phase change chamber is further improved, and the further condensation of water vapor in the flue gas is promoted; the third aspect is to reflux a portion of the already agglomerated particles to the bottom of the phase change removal column, increasing the residence time of the particles in the column, allowing them to continue to collide with other particles, further increasing their size. After the flue gas passes through the second turbulence generator 4, the dust-containing liquid drops are agglomerated and grown up and are finally removed by the wire mesh demister 5. Then, the washing water system 6 sprays water to the wire mesh demister 5 for cleaning, and the dust-containing wastewater is drained to a waste liquid collecting tank 15 at the bottom of the phase change removal tower through a pipeline and is finally discharged through a discharge pipe 16.
Claims (9)
1. The utility model provides a device of coupling vapor phase transition desorption fine particles is reunited to backward flow formula torrent which characterized in that: comprises a phase-change removal tower, wherein the lower part of the phase-change removal tower is provided with a flue gas inlet (1), and the top of the phase-change removal tower is provided with a flue gas outlet (7); a first turbulence generator (2), a cooling heat exchanger (3), a second turbulence generator (4), a wire mesh demister (5) and a washing water system (6) are sequentially arranged in an inner cavity of the phase change removal tower from bottom to top;
a flue gas reflux pipeline is arranged on the outer side of the phase change removal tower and comprises a flue gas reflux section (9), the top end of the flue gas reflux pipeline is provided with a flue gas reflux inlet (8), and the bottom end of the flue gas reflux pipeline is provided with a flue gas reflux outlet (12); an air pump (10) is arranged in the flue gas reflux section (9); the flue gas backflow inlet (8) is positioned between the second turbulence generator (4) and the wire mesh demister (5), and the flue gas backflow outlet (12) is positioned below the first turbulence generator (2);
the returned flue gas in the flue gas return pipeline contains part of grown wetting particles and newly-entered fine particles at the flue gas inlet (1) and passes through the first turbulence generator (2) to generate turbulence, so that the newly-entered fine particles are promoted to collide and coalesce with the wetting particles in the returned flue gas to form grown particles, and the grown particles enter a supersaturated field constructed by the cooling heat exchanger (3) again to realize the heterogeneous condensation of water vapor on the surfaces of the particles;
the distance between the flue gas backflow inlet (8) and the second turbulence generator (4) is 1500-2000 mm, and the distance between the flue gas backflow outlet (12) and the first turbulence generator (2) is 200-300 mm; and controlling the sum of the return flue gas amount of the flue gas return pipeline to be 80% of the flue gas inlet flow.
2. The device for removing fine particulate matters by coupling reflux turbulence agglomeration and water-vapor phase change according to claim 1, which is characterized in that: the cooling heat exchanger (3) comprises a cooling medium inlet (13) and a cooling medium outlet (14), and the cooling medium inlet (13) is positioned above the cooling medium outlet (14).
3. The device for removing fine particulate matters by coupling reflux turbulence agglomeration and water-vapor phase change according to claim 1, which is characterized in that: the flushing water system (6) comprises a distributor, a water inlet pipe and a control valve, wherein the distributor is communicated with the water inlet pipe, and the control valve is positioned on the water inlet pipe; the distributor consists of a plurality of water pipes, water distribution holes with the diameter of 0.1-2 mm are uniformly distributed on the water pipes, and flushing water is sprayed out from the water distribution holes.
4. The device for removing fine particulate matters by coupling reflux turbulence agglomeration and water-vapor phase change according to claim 1, which is characterized in that: the cross sectional area of the first turbulence generator (2), the cross sectional area of the second turbulence generator (4) and the cross sectional area of the wire mesh demister (5) are respectively equal to the cross sectional area of the phase change removal tower; the water distribution area of the flushing water system (6) is equal to the cross-sectional area of the phase change removal tower.
5. The device for removing fine particulate matters by coupling reflux turbulence agglomeration and water-vapor phase change according to claim 1, which is characterized in that: 2 ~ 6 flue gas return lines, flue gas return line evenly distributed is on the outer wall of phase transition desorption tower.
6. The device for removing fine particulate matters by coupling reflux turbulence agglomeration and water-vapor phase change according to claim 5, characterized in that: the first turbulence generator (2) comprises two layers of triangular turbulence bars, the material of each turbulence bar is carbon steel, and the surface of each turbulence bar is subjected to anti-abrasion treatment and coated with a PTFE coating; the structure and the material of the second turbulence generator (4) are the same as those of the first turbulence generator (2).
7. The device for removing fine particulate matters by coupling reflux turbulence agglomeration with water vapor phase change according to claim 1, which is characterized in that: the material of the flue gas return pipeline is hydrophobic material, and the outer surface of the flue gas return pipeline is provided with a heat insulation layer (11); the heat-insulating layer is divided into two layers, wherein the inner layer is an aluminum silicate blanket, and the outer layer is a rock wool seam felt.
8. The device for removing fine particulate matters by coupling reflux turbulence agglomeration and water-vapor phase change according to claim 1, which is characterized in that: still include waste liquid collecting pit (15), waste liquid collecting pit (15) are located the bottom of phase transition desorption tower, waste liquid collecting pit (15) are including delivery pipe (16) and valve (17), and valve (17) are used for controlling the waste water of waste liquid collecting pit (15) collection and pass through delivery pipe (16) and discharge.
9. A method for removing fine particles by coupling reflux type turbulence agglomeration with water vapor phase change is characterized by comprising the following steps:
step 10) saturated flue gas at an outlet of a desulfurization tower is discharged into a flue gas inlet (1) of a phase change removal tower, the saturated flue gas flows from bottom to top in the phase change removal tower, passes through a first turbulence generator (2) and a cooling heat exchanger (3), the flue gas is cooled to form supersaturation, steam is condensed on the surface of fine particles, then passes through a second turbulence generator (4) to form turbulence, agglomeration among wet particles is promoted to grow, and finally the agglomerated and grown particles are removed by a wire mesh demister (5);
while the process is carried out, the air suction pump (10) on the flue gas return pipeline is adjusted, so that the returned flue gas contains part of the grown wet particles before the flue gas at the outlet of the second turbulence generator (4) flows back to the first turbulence generator (2); the returned flue gas contains part of the grown wet particles and the newly entered fine particles at the flue gas inlet (1) pass through the first turbulence generator (2) to generate turbulence, so that the newly entered fine particles are promoted to collide and coalesce with the wet particles in the returned flue gas to form grown particles, and the grown particles enter a supersaturated field constructed by the cooling heat exchanger (3) again to realize the heterogeneous condensation of water vapor on the surfaces of the particles;
step 20) cleaning the fine particles collected by the wire mesh demister (5) by using a washing water system (6), enabling the cleaned waste liquid to flow into a waste liquid collecting tank (15), and finally discharging the waste liquid through a discharge pipe (16);
a flue gas reflux pipeline is arranged on the outer side of the phase change removal tower, the top end of the flue gas reflux pipeline is a flue gas reflux inlet (8), and the bottom end of the flue gas reflux pipeline is a flue gas reflux outlet (12); the distance between the flue gas backflow inlet (8) and the second turbulence generator (4) is 1500-2000 mm, and the distance between the flue gas backflow outlet (12) and the first turbulence generator (2) is 200-300 mm; and controlling the sum of the return flue gas amount of the flue gas return pipeline to be 80% of the flue gas inlet flow.
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