CN112755740A - Wet desulphurization tail gas evaporation water step recovery system and method - Google Patents
Wet desulphurization tail gas evaporation water step recovery system and method Download PDFInfo
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 289
- 238000001704 evaporation Methods 0.000 title claims abstract description 32
- 230000008020 evaporation Effects 0.000 title claims abstract description 32
- 238000011084 recovery Methods 0.000 title claims abstract description 30
- 238000000034 method Methods 0.000 title claims abstract description 18
- 238000009833 condensation Methods 0.000 claims abstract description 90
- 230000005494 condensation Effects 0.000 claims abstract description 90
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 88
- 238000005507 spraying Methods 0.000 claims abstract description 73
- 239000003546 flue gas Substances 0.000 claims abstract description 62
- 239000007789 gas Substances 0.000 claims abstract description 52
- 238000006477 desulfuration reaction Methods 0.000 claims abstract description 49
- 230000023556 desulfurization Effects 0.000 claims abstract description 49
- 238000004140 cleaning Methods 0.000 claims abstract description 39
- 239000002002 slurry Substances 0.000 claims abstract description 37
- 238000009990 desizing Methods 0.000 claims abstract description 34
- 230000003009 desulfurizing effect Effects 0.000 claims abstract description 31
- 239000007788 liquid Substances 0.000 claims description 148
- 239000012528 membrane Substances 0.000 claims description 43
- 239000003570 air Substances 0.000 claims description 38
- 239000012080 ambient air Substances 0.000 claims description 16
- 239000003344 environmental pollutant Substances 0.000 claims description 15
- 231100000719 pollutant Toxicity 0.000 claims description 15
- 230000002829 reductive effect Effects 0.000 claims description 9
- 230000009467 reduction Effects 0.000 claims description 7
- 229920006395 saturated elastomer Polymers 0.000 claims description 6
- 239000012530 fluid Substances 0.000 claims description 5
- 230000036961 partial effect Effects 0.000 claims description 3
- 230000002441 reversible effect Effects 0.000 claims description 3
- 238000009776 industrial production Methods 0.000 claims description 2
- 238000000746 purification Methods 0.000 claims description 2
- 238000004064 recycling Methods 0.000 abstract description 5
- 230000008569 process Effects 0.000 description 10
- 239000000779 smoke Substances 0.000 description 7
- 239000007921 spray Substances 0.000 description 7
- 230000009471 action Effects 0.000 description 6
- 230000005484 gravity Effects 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- 239000003245 coal Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000018044 dehydration Effects 0.000 description 2
- 238000006297 dehydration reaction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000005200 wet scrubbing Methods 0.000 description 2
- 239000002253 acid Substances 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
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- 230000000670 limiting effect Effects 0.000 description 1
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- 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
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/80—Semi-solid phase processes, i.e. by using slurries
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- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/48—Sulfur compounds
- B01D53/50—Sulfur oxides
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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
- B01D53/96—Regeneration, reactivation or recycling of reactants
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- B—PERFORMING OPERATIONS; TRANSPORTING
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Abstract
The invention discloses a wet desulphurization tail gas evaporation water step recovery system and a wet desulphurization tail gas evaporation water step recovery method, wherein the system comprises a desulphurization tower, a slurry pump, a primary circulation tank, a primary condensing pump, a primary air cooler, a secondary circulation tank, a secondary condensing pump and a secondary air cooler; the side wall of the desulfurizing tower is provided with a flue gas inlet, and the top of the desulfurizing tower is provided with a flue gas outlet; a desulfurization spraying layer, a desizing cleaning layer, a primary water collecting layer, a primary condensation spraying layer, a secondary water collecting layer, a secondary condensation spraying layer, a demister layer and a demister cleaning layer are sequentially arranged between a flue gas inlet and a flue gas outlet in the desulfurization tower from bottom to top; a slurry pool is arranged below the flue gas inlet in the desulfurizing tower. The invention reduces the running water consumption of the wet desulphurization device and the water vapor discharge in the tail gas by carrying out fractional condensation and water collection on the wet desulphurization tail gas and carrying out step recycling on the recovered condensed water.
Description
Technical Field
The invention relates to the field of resources and environment, in particular to a wet desulphurization tail gas evaporation water step recovery system and a wet desulphurization tail gas evaporation water step recovery method.
Background
At present, over 90 percent of thermal power coal-fired units in China adopt wet scrubbing flue gas desulfurization technology. In the operation process of the coal-fired boiler wet desulphurization device, high-temperature flue gas is contacted with spray liquid, water in washing liquid is evaporated into steam to enter the flue gas, high-temperature saturated wet flue gas is formed and discharged to the ambient air, simultaneously, a large amount of evaporated water is discharged to the ambient air, the exhaust gas temperature of wet desulphurization tail gas is 50-60 ℃, the flue gas is supersaturated wet flue gas, and the discharged flue gas contains steam, condensed water drops, slurry fog drops, CO2Unremoved SOx、NOxSoluble salts, gel dust, micro dust and the like (which are main components of haze) and the like.
The high-humidity desulfurization tail gas enters the atmosphere and contacts with ambient air with lower temperature for heat exchange, and saturated water vapor is further condensed to generate more obvious white smoke plume. The white smoke containing a large amount of fog drops not only causes serious visual pollution, but also can increase the difficulty of pollutant diffusion in smoke under the action of gravity, and pollutants are easy to be enriched near a white smoke emission source, thereby causing serious adverse effect on the regional environment quality. Meanwhile, in the condensation process of evaporated moisture discharged by the wet desulphurization system, acid gas remained in the flue gas has strong corrosive acidity. The high-humidity desulfurization tail gas carrying a large amount of evaporated moisture and various residual pollutants enters the atmosphere, and the evaporation speed of condensed water drops and the pollutant diffusion speed are influenced by the temperature and the stability of ambient air. When the smoke is heated in summer, the convection strength of ambient air is high, the air saturation is low, the bearing capacity of the smoke on water vapor is large, and condensed water drops and pollutants carried by high-humidity smoke can be quickly volatilized and diffused; at cold air temperature in winter, the stability and saturation of ambient air are high, and condensed water drops and pollutants carried by high-humidity flue gas are difficult to volatilize and diffuse.
The discharge of a large amount of evaporated water is the main reason of large water consumption in the operation of a wet desulphurization device, and 300MW coal is used as fuelFor example, a wet desulfurization system consumes about 50m of water per hour3And/h, the annual water consumption is about 40 ten thousand tons. Meanwhile, in the operation process of the wet desulphurization device of the thermal power unit, a large amount of moisture is discharged to the environment in the form of water vapor from the high-humidity desulphurization tail gas, when a 300MW unit runs at full load, the desulphurization device discharges about 120 tons of water vapor to the environment per hour (including coal combustion moisture, air carrying water and evaporation moisture in the operation process of the wet desulphurization system), and the annual water discharge amount is about 100 ten thousand tons. The amount of evaporated water discharged to the environment by the wet desulphurization device of the thermal power generating unit is far larger than the water consumption of the wet desulphurization device. The method develops a wet desulphurization tail gas evaporation water recycling technology, can reduce the evaporation water discharge amount of the wet desulphurization tail gas, and can use the recovered evaporation water for water replenishing in the wet desulphurization process, thereby reducing the water consumption of the wet desulphurization device, and even realizing zero water consumption operation of the wet desulphurization device when the evaporation water recovery amount reaches a certain value. Therefore, the development of a low-cost wet desulphurization tail gas evaporation water recovery technology and a recovery condensate water cascade utilization technology is urgent.
Disclosure of Invention
The invention provides a wet desulphurization tail gas evaporation water step recovery system, which reduces the running water consumption of a wet desulphurization device and the water vapor discharge in tail gas by carrying out fractional condensation and water collection on the wet desulphurization tail gas and carrying out step recovery and utilization on the recovered condensed water.
The technical scheme of the invention is as follows:
a wet flue gas desulfurization evaporation water cascade recovery system includes:
the system comprises a desulfurizing tower, a slurry pump, a primary circulating tank, a primary condensing pump, a primary air cooler, a secondary circulating tank, a secondary condensing pump and a secondary air cooler;
the side wall of the desulfurizing tower is provided with a flue gas inlet, and the top of the desulfurizing tower is provided with a flue gas outlet; a desulfurization spraying layer, a desizing cleaning layer, a primary water collecting layer, a primary condensation spraying layer, a secondary water collecting layer, a secondary condensation spraying layer, a demister layer and a demister cleaning layer are sequentially arranged between a flue gas inlet and a flue gas outlet in the desulfurization tower from bottom to top; a slurry pool is arranged below a flue gas inlet in the desulfurizing tower;
the liquid inlet of the slurry pump is communicated with the slurry pool through a connecting pipeline, and the liquid outlet of the slurry pump is communicated with the liquid inlet of the desulfurization spraying layer through a connecting pipeline;
the liquid outlet of the primary water collecting layer is communicated with the liquid inlet of the primary air cooler through a connecting pipeline, the liquid outlet of the primary air cooler is communicated with the liquid inlet of the primary circulating tank through a connecting pipeline, the liquid outlet of the primary circulating tank is communicated with the liquid inlet of the primary condensing pump through a connecting pipeline, and the liquid outlet of the primary condensing pump is respectively communicated with the liquid inlet of the desizing cleaning layer and the liquid inlet of the primary condensing spraying layer through connecting pipelines;
the leakage fluid dram of water layer is received to the second grade passes through the income liquid mouth intercommunication of connecting tube and second grade air cooler, and the liquid outlet of second grade air cooler passes through the income liquid mouth intercommunication of connecting tube and second grade circulating tank, and the liquid outlet of second grade circulating tank and the income liquid mouth intercommunication of second grade condensate pump, the liquid outlet of second grade condensate pump pass through the connecting tube respectively with the income liquid mouth of desizing cleaning layer, the income liquid mouth of one-level condensation spraying layer, the income liquid mouth of second grade condensation spraying layer and the income liquid mouth intercommunication of defroster cleaning layer.
Preferably, the first-stage water receiving layer and the second-stage water receiving layer respectively comprise a plurality of water receiving modules and a liquid guide tank; the water collecting modules are symmetrically arranged obliquely in rows, and two adjacent rows of the water collecting modules form a V shape; the liquid guide groove is horizontally arranged below the joint of the bottoms of the two adjacent water collecting modules and is used for receiving liquid collected by the water collecting modules.
Furthermore, the included angle between the obliquely installed water collecting module and the horizontal plane is 30-57 degrees.
Furthermore, each water collecting module comprises a plurality of water collecting membranes which are arranged transversely at equal intervals, each water collecting membrane is of a parallelogram corrugated plate structure, a corrugated channel is formed between every two adjacent water collecting membranes, and the direction of an air inlet of each corrugated channel is parallel to the axial direction of the center of the desulfurizing tower.
Preferably, in each water collecting module, the distance between adjacent water collecting membranes is 12-28 mm; the length of each water-receiving film sheet is 0.8m-1.6m, and the width is 0.1m-0.3 m.
And a convex arc curved surface is arranged in the middle of each water receiving membrane in the width direction, namely the direction of the connecting line of the top points of the arc curved surfaces of the water receiving membranes is consistent with the length direction of the water receiving membranes. When the water collecting module is installed, the water collecting module is obliquely installed, so that the included angle between the length direction of the water collecting membrane and the horizontal plane is 30-57 degrees.
The arc-shaped baffle plate is arranged on the convex side of the arc-shaped curved surface of the water collecting diaphragm, the arc-shaped baffle plate and the water collecting diaphragm form a water return groove, and the water return groove is used for guiding and collecting liquid collected by the water collecting diaphragm.
Preferably, one end of the arc-shaped baffle connected with the water receiving membrane is positioned 5-10mm below the vertex of the arc-shaped curved surface of the water receiving membrane, and the curved surface of the arc-shaped baffle is parallel to the arc-shaped curved surface of the water receiving membrane; preferably, the width of the opening end of the water return groove is 6mm-14mm, and the depth of the water return groove is 10mm-30 mm.
Preferably, the water collecting module further comprises a water distributor, the water distributor comprises a first cavity and a second cavity, and a liquid outlet at the bottom of the water distributor is communicated with the liquid guide groove; the first cavity is communicated with the water return groove of each water receiving membrane in the water receiving module at one side, and the second cavity is communicated with the water return groove of each water receiving membrane in the water receiving module at the other side.
The two adjacent water collecting modules are symmetrically and obliquely arranged to form a V shape, the water guider is positioned at the joint of the two adjacent water collecting modules, the first cavity is communicated with the water return groove of each water collecting membrane in one water collecting module, and the second cavity is communicated with the water return groove of each water collecting membrane in the other water collecting module. After the water collecting membrane collects liquid water, the liquid water flows into the water return tank under the action of gravity, is guided into the first cavity or the second cavity through the water return tank, and is finally discharged into the liquid guide tank through the liquid outlet of the water guider.
And liquid outlets of the liquid guide groove penetrate through the tower wall of the desulfurizing tower and are communicated with liquid inlets of the primary air cooler or the secondary air cooler through connecting pipelines.
Preferably, the liquid outlet of one-level condensate pump and the income liquid mouth of the washing layer that destarchs, the liquid outlet of one-level condensate pump and the income liquid mouth on one-level condensation spray layer, the liquid outlet of second grade condensate pump and the income liquid mouth on defroster layer, the liquid outlet of second grade condensate pump and the income liquid mouth on second grade condensation spray layer, the liquid outlet of second grade condensate pump and the connecting pipeline that the income liquid mouth on one-level condensation spray layer, the liquid outlet of second grade condensate pump and the income liquid mouth of the washing layer that destarchs all are equipped with flow control valve.
The invention also provides a wet desulphurization tail gas evaporation water cascade recovery method, which is preferably realized by the wet desulphurization tail gas evaporation water cascade recovery system, and comprises the following steps:
(1) high-temperature flue gas containing pollutants enters the desulfurization tower from the flue gas inlet to flow upwards, and desulfurization slurry in the slurry pool is conveyed to the desulfurization spraying layer through the desulfurization pump and flows downwards after being sprayed and atomized by the desulfurization spraying layer; under the desulfurization spraying layer, the high-temperature flue gas is in reverse contact with the desulfurization slurry, the high-temperature flue gas and the desulfurization slurry carry out heat exchange and temperature reduction while pollutants in the flue gas are removed, a large amount of water in the desulfurization slurry is evaporated into steam to enter the flue gas, and the flue gas after desulfurization and purification is saturated;
(2) the desulfurized and purified saturated flue gas sequentially passes through a primary water receiving layer and a primary condensation spraying layer; the low-temperature condensate in the primary circulation tank is conveyed to a primary condensation spraying layer through a primary condensation pump, is atomized by the primary condensation spraying layer and then is subjected to contact heat exchange with saturated flue gas, the temperature of the saturated flue gas is reduced by 3-5 ℃, partial steam in the saturated flue gas is condensed to generate liquid water, the liquid water enters a primary water collecting layer along with the primary condensation spraying liquid, the condensed water and the primary condensate are guided to enter a primary air cooler through a water return tank and a water guider and enter the primary circulation tank after being subjected to heat exchange and temperature reduction, the condensed and recovered water is used as cleaning water of a desizing cleaning layer, and the water consumption of the desizing cleaning layer is reduced;
(3) when the ambient air temperature is higher than 5 ℃, the secondary condensation water-receiving section is not started, and the saturated flue gas after primary condensation water-receiving upwards sequentially passes through the demister layer and the demister cleaning layer and is discharged from the flue gas outlet of the desulfurizing tower;
when the ambient air temperature is lower than 5 ℃, the secondary condensation water-receiving section is opened, and the desulfurized tail gas is deeply water-received: the saturated flue gas which finishes the primary condensation water collection continuously flows upwards and sequentially passes through a secondary water collection layer and a secondary condensation spraying layer; the low-temperature condensate in the secondary circulation tank is conveyed to a secondary condensation spraying layer through a secondary condensation pump, is atomized by the secondary condensation spraying layer and then is in contact heat exchange with saturated flue gas, the temperature of the saturated flue gas is reduced by 10-25 ℃, most of water vapor in the saturated flue gas is condensed to generate liquid water, the liquid water enters a secondary air cooler along with the secondary condensation spraying liquid to be subjected to heat exchange and temperature reduction and is stored in the secondary circulation tank, and then the liquid water is respectively conveyed to a demister cleaning layer, a section of condensation spraying layer and a desizing cleaning layer through the secondary condensation pump, and the surplus water is discharged out of the wet desulphurization system to serve as other industrial production water; the saturated flue gas which finishes the water collection by the two-stage condensation is discharged from the flue gas outlet of the desulfurizing tower after sequentially passing through the demister layer and the demister cleaning layer, so that the deep step recovery of the wet desulphurization tail gas evaporation water is realized.
Preferably, the inlet pressure of the first-stage condensation spraying layer is 0.1-0.2MPa, and the spraying liquid-gas ratio of the first-stage condensation spraying layer is 0.5-1.0L/Nm3The coverage rate of the spraying liquid level is 200-300%.
Preferably, the inlet pressure of the secondary condensation spraying layer is 0.15-0.25MPa, and the spraying liquid-gas ratio of the secondary condensation spraying layer is 1.5-3.0L/Nm3The coverage rate of the spraying liquid level is 250-400 percent.
Compared with the prior art, the invention has the following beneficial effects:
(1) the invention provides a solution for recovering water evaporated from wet desulphurization tail gas and reducing the tail gas emission humidity of a desulphurization device, which is characterized in that condensation heat exchange is carried out on the wet desulphurization tail gas, most saturated vapor in the wet desulphurization tail gas is condensed to generate liquid water for recycling, and the low-operation water consumption operation of the wet desulphurization device is realized;
(2) the invention provides a solution for recovering evaporation water of wet desulphurization tail gas with low energy consumption, which utilizes ambient air as a cold source and adopts spray atomized liquid drops to directly contact with high-temperature saturated wet flue gas for heat exchange, thereby greatly improving the heat exchange efficiency. Condensed water is collected and recovered by the water collecting module with the functions of collecting water and demisting, so that the low-resistance, low-energy-consumption and stable operation of a condensed water collecting system can be realized while the condensed water recovery efficiency is greatly improved;
(3) the invention provides a solution for recycling condensed water by a wet desulphurization device in a gradient manner, which adopts a two-stage condensation device, recycles a small part of evaporated water in the first stage of condensation, is used for meeting the requirements of washing a desizing layer of a wet desulphurization system and replenishing water in the wet desulphurization process, recycles a large part of evaporated water in the second stage of condensation, and can generate a large amount of clean water which can provide water sources for other production processes while meeting the requirement of zero water consumption operation of the system;
(4) the invention provides a solution for recovering water evaporated by a wet desulphurization device in different seasons, according to the ambient air temperature and climate change, when the ambient air temperature is higher, only primary condensation is carried out on flue gas for recovering a small part of evaporated water; when the ambient air temperature is lower, the secondary condensation water-receiving system is started to realize the deep condensation of the saturated flue gas.
Drawings
FIG. 1 is a schematic structural diagram of a wet desulfurization tail gas evaporation water step recovery system;
FIG. 2 is a schematic structural view of a water receiving module and a liquid guiding tank;
fig. 3 is a schematic arrangement diagram of water collecting membranes in the water collecting module.
Detailed Description
The invention will be described in further detail below with reference to the drawings and examples, which are intended to facilitate the understanding of the invention without limiting it in any way.
One embodiment of the wet desulfurization tail gas evaporation water step recovery system of the present invention is shown in fig. 1, and comprises: desulfurizing tower 1, thick liquid pump 2, one-level circulating tank 3, one-level condensate pump 4, one-level air cooler 5, second grade circulating tank 6, second grade condensate pump 7, second grade air cooler 8.
The side wall of the desulfurizing tower 1 is provided with a flue gas inlet 101, and the top of the desulfurizing tower 1 is provided with a flue gas outlet 102; the bottom of the desulfurizing tower 1 is a slurry pool 103.
A desulfurization spraying layer 104, a desizing layer 105, a desizing cleaning layer 106, a primary water collecting layer 107, a primary condensation spraying layer 108, a secondary water collecting layer 109, a secondary condensation spraying layer 110, a demister layer 111 and a demister cleaning layer 112 are sequentially arranged between a flue gas inlet 101 and a flue gas outlet 102 in the desulfurizing tower 1 from bottom to top.
The liquid inlet of the slurry pump 2 is communicated with the slurry pool 103 through a connecting pipeline, and the liquid outlet of the slurry pump 2 is communicated with the liquid inlet of the desulfurization spraying layer 104 through a connecting pipeline.
The leakage fluid dram of water layer 107 is received to the one-level passes through the connecting tube and communicates with the income liquid mouth of one-level air cooler 5, and the liquid outlet of one-level air cooler 5 passes through the connecting tube and communicates with the income liquid mouth of one-level circulating tank 3, and the liquid outlet of one-level circulating tank 3 passes through the connecting tube and communicates with the income liquid mouth of one-level condensate pump 4, and the liquid outlet of one-level condensate pump 4 passes through the connecting tube and communicates with the income liquid mouth of desizing cleaning layer 106 and the income liquid mouth of one-level condensation spray layer 108 respectively.
The leakage fluid dram of second grade water receiving layer 109 passes through the income liquid mouth intercommunication of connecting tube and second grade air cooler 8, the liquid outlet of second grade air cooler 8 passes through the income liquid mouth intercommunication of connecting tube and second grade circulating tank 6, the liquid outlet of second grade circulating tank 6 and the income liquid mouth intercommunication of second grade condensate pump 7, the liquid outlet of second grade condensate pump 7 pass through the connecting tube respectively with the income liquid mouth of desizing cleaning layer 106, the income liquid mouth of layer 108 is sprayed in the one-level condensation, the income liquid mouth of layer 110 and the income liquid mouth intercommunication of defroster cleaning layer 112 are sprayed in the second grade condensation.
The liquid outlet of one-level condensate pump 4 and the income liquid mouth of desizing cleaning layer 106, the liquid outlet of one-level condensate pump 4 and the income liquid mouth of one-level condensation spraying layer 108, the liquid outlet of second grade condensate pump 7 and the income liquid mouth of defroster layer 111, the liquid outlet of second grade condensate pump 7 and the income liquid mouth of second grade condensation spraying layer 110, the liquid outlet of second grade condensate pump 7 and the income liquid mouth of one-level condensation spraying layer 108, the liquid outlet of second grade condensate pump 7 and the connecting pipeline of the income liquid mouth of desizing cleaning layer 106 all are equipped with flow control valve.
The first-stage water receiving layer 107 consists of a plurality of water receiving modules 107-1 and a liquid guide tank 107-2; the structure of the secondary water-collecting layer 109 is the same as that of the primary water-collecting layer 107. As shown in fig. 2, the water receiving modules 107-1 are symmetrically arranged in rows and in an inclined manner, and two adjacent water receiving modules 107-1 form a V shape; the liquid guide groove 107-2 is horizontally arranged below the joint of the bottoms of the two adjacent water receiving modules and is used for receiving liquid collected by the water receiving module 107-1.
Each water collecting module 107-1 comprises a plurality of water deflectors 107-3 and water collecting membranes which are arranged in an equidistant and transverse mode. As shown in FIG. 3, each water-collecting membrane 107-4 has a parallelogram corrugated plate structure. In each water receiving module 107-1, the distance between adjacent water receiving membranes 107-4 is 12mm-28 mm; each water-receiving membrane 107-4 has a length of 0.8m-1.6m and a width of 0.1m-0.3 m.
As shown in FIG. 3, in the water collecting membrane 107-4, a water returning groove 107-5 composed of an arc baffle and a curved surface of the water collecting membrane is arranged on the outer side of the convex arc surface of the corrugated surface. The connecting end of the arc-shaped baffle plate of the water return tank 107-5 and the water receiving membrane is positioned 5-10mm below the top point of the curved surface of the water receiving membrane, and the curved surface of the arc-shaped baffle plate is parallel to the curved surface of the water receiving membrane; the opening width of the water return groove 107-5 is 6mm-14mm, and the depth of the water return groove 107-5 is 10mm-30 mm.
The two adjacent water receiving modules are symmetrically and obliquely arranged to form a V shape, the water guider 107-3 is positioned at the joint of the two adjacent water receiving modules, the first cavity is communicated with the water return groove 107-5 of each water receiving membrane 107-4 in one water receiving module, and the second cavity is communicated with the water return groove 107-5 of each water receiving membrane 107-4 in the other water receiving module. After the water collecting membrane 107-4 collects the liquid water, the liquid water flows into the water returning tank 107-5 under the action of gravity, is guided into the first cavity or the second cavity through the water returning tank 107-5, and is finally discharged into the liquid guide tank through the liquid outlet of the water guider 107-3. The liquid outlets of the liquid guide groove penetrate through the tower wall of the desulfurizing tower 1 and are communicated with the liquid inlets of the first-stage air cooler 5 or the second-stage air cooler 8 through connecting pipelines.
The specific implementation mode of performing step recovery on the evaporation water of the wet desulphurization tail gas by adopting the system is as follows:
high-temperature flue gas containing a large amount of pollutants enters the desulfurizing tower 1 from a flue gas inlet 101 of the desulfurizing tower 1 and flows upwards, the high-temperature flue gas and the desulfurizing slurry sent to the desulfurizing spraying layer 104 by the slurry pump 2 are in reverse contact above an inlet flue and below the desulfurizing spraying layer 104, the pollutants in the flue gas are collected and absorbed by the desulfurizing slurry, and part of moisture in the desulfurizing slurry is evaporated into steam by the high-temperature flue gas in the gas-liquid contact process and enters the flue gas. And cooling the desulfurization tail gas subjected to wet scrubbing to 50-60 ℃ and reaching a saturated state.
The desulfurized saturated flue gas carries part of fine desulfurized slurry fog drops to pass through the desizing cleaning layer 106 after the slurry fog drops are removed from the desizing layer 105, cleaning liquid of the desizing layer 105 is sent to the desizing cleaning layer 106 by the primary condensing pump 4 to be atomized and then sent to the surface of the desizing layer 105, the slurry fog drops deposited on the surface of the desizing layer 105 are cleaned, and the slurry fog drops collected by the desizing layer 105 are prevented from depositing and blocking the desizing layer 105. The fine desizing layer 105 cleaning fluid droplets atomized by the desizing layer 105 enter the primary water collecting layer 107 along with the flue gas flow, are subjected to inertial collision with a square wave channel below the primary water collecting layer 107 and are trapped, and pass through the desizing cleaning layer 106, the desizing layer 105 and the desulfurization spraying layer 104 under the action of gravity to fall into the slurry tank 103; the content of pollutants in the flue gas entering the primary water receiving section is effectively reduced and the quality of primary water receiving water is improved by trapping and recovering the lower ends of the desizing layer 105 and the primary water receiving layer 107.
In the process that high-temperature flue gas passes through the primary water collecting layer 107 and the primary condensation spraying layer 108, most of low-temperature condensate in the primary circulating tank 3 is sent to the primary condensation spraying layer 108 through the primary condensation pump 4, atomized by the primary condensation spraying layer 108 and then falls onto the upper surface of the primary water collecting layer 107, and guided to a liquid guide tank through a water return tank 107-5 on the water collecting membrane 107-4 of the water collecting layer. The high-temperature saturated flue gas and the low-temperature condensate are subjected to contact heat exchange on the surfaces of the primary condensation spraying layer 108 and the primary water collecting layer 107, the temperature of the wet desulphurization tail gas is reduced by 3-5 ℃, partial steam is condensed and cooled to form liquid water drops, the primary condensate after heat exchange is discharged into the primary air cooler 5 through the outlet of the liquid guide groove to be subjected to heat exchange and cooling with ambient air, and the primary condensate after heat exchange is discharged into the primary circulation tank 3 from the outlet of the primary air cooler 5 to be recycled. The saturated flue gas which finishes the primary condensation water collection carries a small amount of fine water drops to enter a secondary water collection layer 109, avoids inertial collision with a water collection membrane 107-4 in a square wave channel below the secondary water collection layer 109, is collected, and finally falls into the primary water collection layer 107 under the action of gravity to be recovered. In the primary water collecting process, a small amount of residual gaseous pollutants and slurry fog drops in the flue gas are further captured in the condensation collision process.
Under winter and low temperature conditions, the ambient air temperature is low, the wet desulphurization tail gas has a secondary condensation water-collecting condition, the low-temperature condensate in the secondary circulation tank 6 is sent to the secondary condensation spraying layer 110 through the secondary condensation pump 7, deep heat exchange is carried out on the low-temperature condensate and the saturated flue gas passing through the secondary water-collecting layer 109 and the secondary condensation spraying layer 110, the temperature of the saturated flue gas after primary condensation is reduced by 10-25 ℃, and most of evaporated water in the wet desulphurization tail gas is recovered. Evaporated water and secondary condensate recovered in the secondary water collecting section are delivered to a secondary air cooler 8 through an outlet of a liquid guide groove, low-temperature environment air flows through the secondary air cooler 8 under the action of an air cooler fan to indirectly condense and cool recovered water, and low-temperature water after heat exchange and temperature reduction is delivered to a secondary circulating tank 6 through a caliber pipeline of the secondary air cooler 8 for recycling. Through the entrapment of dehydration layer 105 and one-level water receiving layer 107, pollutant content is few in the flue gas that gets into the second grade condensation, and the quality of water after the second grade condensation obtains further improvement, and moisture after the second grade condensation can be used to defroster cleaning layer 112, the one-level condensation sprays layer 108 and dehydration layer 105 water supply, and unnecessary moisture still can provide the water source for other production processes.
The desulfurization tail gas after being subjected to desizing and water collection by two-stage condensation is demisted and dried by a demister and then is discharged from a flue gas outlet 102 of the desulfurizing tower 1.
The above-mentioned embodiments are intended to illustrate the technical solutions and advantages of the present invention, and it should be understood that the above-mentioned embodiments are only specific embodiments of the present invention, and are not intended to limit the present invention, and any modifications, additions, equivalents, etc. made within the scope of the principles of the present invention should be included in the scope of the present invention.
Claims (10)
1. The utility model provides a wet flue gas desulfurization tail gas evaporation water cascade recovery system which characterized in that includes:
the system comprises a desulfurizing tower, a slurry pump, a primary circulating tank, a primary condensing pump, a primary air cooler, a secondary circulating tank, a secondary condensing pump and a secondary air cooler;
the side wall of the desulfurizing tower is provided with a flue gas inlet, and the top of the desulfurizing tower is provided with a flue gas outlet; a desulfurization spraying layer, a desizing cleaning layer, a primary water collecting layer, a primary condensation spraying layer, a secondary water collecting layer, a secondary condensation spraying layer, a demister layer and a demister cleaning layer are sequentially arranged between a flue gas inlet and a flue gas outlet in the desulfurization tower from bottom to top; a slurry pool is arranged below a flue gas inlet in the desulfurizing tower;
the liquid inlet of the slurry pump is communicated with the slurry pool through a connecting pipeline, and the liquid outlet of the slurry pump is communicated with the liquid inlet of the desulfurization spraying layer through a connecting pipeline;
the liquid outlet of the primary water collecting layer is communicated with the liquid inlet of the primary air cooler through a connecting pipeline, the liquid outlet of the primary air cooler is communicated with the liquid inlet of the primary circulating tank through a connecting pipeline, the liquid outlet of the primary circulating tank is communicated with the liquid inlet of the primary condensing pump through a connecting pipeline, and the liquid outlet of the primary condensing pump is respectively communicated with the liquid inlet of the desizing cleaning layer and the liquid inlet of the primary condensing spraying layer through connecting pipelines;
the leakage fluid dram of water layer is received to the second grade passes through the income liquid mouth intercommunication of connecting tube and second grade air cooler, and the liquid outlet of second grade air cooler passes through the income liquid mouth intercommunication of connecting tube and second grade circulating tank, and the liquid outlet of second grade circulating tank and the income liquid mouth intercommunication of second grade condensate pump, the liquid outlet of second grade condensate pump pass through the connecting tube respectively with the income liquid mouth of desizing cleaning layer, the income liquid mouth of one-level condensation spraying layer, the income liquid mouth of second grade condensation spraying layer and the income liquid mouth intercommunication of defroster cleaning layer.
2. The wet desulfurization tail gas evaporation water step recovery system of claim 1, wherein the primary water receiving layer and the secondary water receiving layer respectively comprise a plurality of water receiving modules and a liquid guide tank; the water collecting modules are symmetrically arranged obliquely in rows, and two adjacent rows of the water collecting modules form a V shape; the liquid guide groove is horizontally arranged below the joint of the bottoms of the two adjacent water collecting modules and is used for receiving liquid collected by the water collecting modules.
3. The wet desulfurization tail gas evaporation water step recovery system of claim 2, wherein the included angle between the obliquely installed water collection module and the horizontal plane is 30-57 °.
4. The wet desulfurization tail gas evaporation water cascade recovery system of claim 2, wherein each water collection module comprises a plurality of water collection membranes which are arranged in a transverse arrangement at equal intervals, each water collection membrane is in a parallelogram corrugated plate structure, corrugated channels are formed between adjacent water collection membranes, and the air inlet directions of the corrugated channels are parallel to the central axis of the desulfurization tower.
5. The wet desulfurization tail gas evaporation water step recovery system of claim 4, wherein in each water collection module, the distance between adjacent water collection membranes is 12mm-28 mm; the length of each water-receiving film sheet is 0.8m-1.6m, and the width is 0.1m-0.3 m.
6. The wet desulfurization tail gas evaporation water step recovery system of claim 4, wherein each water collection membrane is provided with a convex arc-shaped curved surface in the middle in the width direction, an arc-shaped baffle is arranged on the convex side of the arc-shaped curved surface, the arc-shaped baffle and the water collection membrane form a water return tank, and the water return tank is used for guiding the liquid collected by the water collection membrane.
7. The wet desulphurization tail gas evaporation water step recovery system according to claim 6, wherein the end of the curved baffle connected with the water collection membrane is positioned 5-10mm below the vertex of the circular arc curved surface of the water collection membrane, and the curved surface of the curved baffle is parallel to the circular arc curved surface of the water collection membrane; the width of the opening end of the water return groove is 6mm-14mm, and the depth of the water return groove is 10mm-30 mm.
8. The wet desulfurization tail gas evaporation water step recovery system of claim 6, wherein the water collection module further comprises a water distributor, the water distributor comprises a first cavity and a second cavity, and a liquid outlet at the bottom of the water distributor is communicated with the liquid guide groove; the first cavity is communicated with the water return groove of each water receiving membrane in the water receiving module at one side, and the second cavity is communicated with the water return groove of each water receiving membrane in the water receiving module at the other side.
9. A wet desulphurization tail gas evaporation water step recovery method is characterized by comprising the following steps:
(1) high-temperature flue gas containing pollutants enters the desulfurization tower from the flue gas inlet to flow upwards, and desulfurization slurry in the slurry pool is conveyed to the desulfurization spraying layer through the desulfurization pump and flows downwards after being sprayed and atomized by the desulfurization spraying layer; under the desulfurization spraying layer, the high-temperature flue gas is in reverse contact with the desulfurization slurry, the high-temperature flue gas and the desulfurization slurry carry out heat exchange and temperature reduction while pollutants in the flue gas are removed, a large amount of water in the desulfurization slurry is evaporated into steam to enter the flue gas, and the flue gas after desulfurization and purification is saturated;
(2) the desulfurized and purified saturated flue gas sequentially passes through a primary water receiving layer and a primary condensation spraying layer; the low-temperature condensate in the primary circulation tank is conveyed to a primary condensation spraying layer through a primary condensation pump, is atomized by the primary condensation spraying layer and then is subjected to contact heat exchange with saturated flue gas, the temperature of the saturated flue gas is reduced by 3-5 ℃, partial steam in the saturated flue gas is condensed to generate liquid water, the liquid water enters a primary water collecting layer along with the primary condensation spraying liquid, the condensed water and the primary condensate are guided to enter a primary air cooler through a water return tank and a water guider and enter the primary circulation tank after being subjected to heat exchange and temperature reduction, the condensed and recovered water is used as cleaning water of a desizing cleaning layer, and the water consumption of the desizing cleaning layer is reduced;
(3) when the ambient air temperature is higher than 5 ℃, the secondary condensation water-receiving section is not started, and the saturated flue gas after primary condensation water-receiving upwards sequentially passes through the demister layer and the demister cleaning layer and is discharged from the flue gas outlet of the desulfurizing tower;
when the ambient air temperature is lower than 5 ℃, the secondary condensation water-receiving section is opened, and the desulfurized tail gas is deeply water-received: the saturated flue gas which finishes the primary condensation water collection continuously flows upwards and sequentially passes through a secondary water collection layer and a secondary condensation spraying layer; the low-temperature condensate in the secondary circulation tank is conveyed to a secondary condensation spraying layer through a secondary condensation pump, is atomized by the secondary condensation spraying layer and then is in contact heat exchange with saturated flue gas, the temperature of the saturated flue gas is reduced by 10-25 ℃, most of water vapor in the saturated flue gas is condensed to generate liquid water, the liquid water enters a secondary air cooler along with the secondary condensation spraying liquid to be subjected to heat exchange and temperature reduction and is stored in the secondary circulation tank, and then the liquid water is respectively conveyed to a demister cleaning layer, a section of condensation spraying layer and a desizing cleaning layer through the secondary condensation pump, and the surplus water is discharged out of the wet desulphurization system to serve as other industrial production water; the saturated flue gas which finishes the water collection by the two-stage condensation is discharged from the flue gas outlet of the desulfurizing tower after sequentially passing through the demister layer and the demister cleaning layer, so that the deep step recovery of the wet desulphurization tail gas evaporation water is realized.
10. The method for cascade recovery of evaporated water from tail gas of wet desulfurization according to claim 9, wherein the inlet pressure of the primary condensation spraying layer is 0.1-0.2MPa, and the spraying liquid-gas ratio of the primary condensation spraying layer is 0.5-1.0L/Nm3The coverage rate of the spraying liquid level is 200 plus 300 percent; the inlet pressure of the secondary condensation spraying layer is 0.15-0.25MPa, and the spraying liquid-gas ratio of the secondary condensation spraying layer is 1.5-3.0L/Nm3The coverage rate of the spraying liquid level is 250-400 percent.
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Application publication date: 20210507 |