CN113277660A - Desulfurization wastewater concentration and zero-emission treatment process based on flue gas evaporation - Google Patents
Desulfurization wastewater concentration and zero-emission treatment process based on flue gas evaporation Download PDFInfo
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- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
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Abstract
The invention relates to a process, and belongs to the field of wastewater treatment. The device comprises a desulfurization wastewater buffer tank, an integrated coagulation and clarification device, a sludge concentration tank, a sludge dewatering device, a passivation reaction device, a standby heat source heating device, a low-temperature flue gas evaporation and concentration device, a neutralization tank, a precise filtering device and a bypass flue evaporation and drying device; the desulfurization wastewater buffer tank is connected with the integrated coagulation clarification device, the integrated coagulation clarification device is connected with the passivation reaction device, the passivation reaction device is connected with the standby heat source heating device, the standby heat source heating device is connected with the low-temperature flue gas evaporation concentration device, the low-temperature flue gas evaporation concentration device is connected with the neutralization tank, the neutralization tank is connected with the precise filtering device, and the precise filtering device is connected with the bypass flue gas evaporation drying device; the sludge concentration box is connected with the integrated coagulation and clarification device, and the sludge dewatering device is connected with the sludge concentration box. The invention has simple and reasonable treatment process, safety and reliability, less energy consumption and low investment and cost.
Description
Technical Field
The invention relates to a treatment process, in particular to a desulfurization wastewater concentration and zero-discharge treatment process based on flue gas evaporation, and belongs to the technical field of wastewater treatment.
Background
At present, the specific processes for zero discharge treatment of desulfurization wastewater of coal-fired power plants mainly comprise the following steps:
firstly, desulfurized wastewater → neutralization and softening precipitation → deep filtration → steam heating → high-temperature flue gas bypass evaporation zero-emission treatment process. Chinese patent like application number 201710427299.2 adds the medicine for earlier with soften and deposit the processing to desulfurization waste water, then carry out filtration treatment to handling out water and get rid of the suspended solid, deep filtration device handles out water and gets into the heat exchanger, utilize the steam in the heating power oxygen-eliminating device to the waste water heating, later waste water gets into behind the baffle-box and carries out drying process to bypass flue evaporating tower through the waste water pump sending, the atomizing mode of waste water adopts two-fluid atomizing in the bypass flue evaporating tower, the air after the atomizing air adopts solar energy heating. This patent technique directly adopts steam heating after precipitating the preliminary treatment with desulfurization waste water, then gets into the evaporation drying that high temperature flue gas bypass system realized desulfurization waste water, does not carry out concentrated decrement to desulfurization waste water and handles for high temperature flue gas bypass system's processing water yield is great, and the high temperature flue gas volume that needs to use is great, and system operation energy consumption is higher. In addition, because the high-concentration chloride ions in the desulfurization wastewater have strong corrosivity, the corrosion prevention level of system equipment is higher, and the investment cost is higher.
Adopting the processes of desulfurized wastewater → dosing flocculation pretreatment → direct contact heating concentration treatment → solidification treatment. For example, chinese patent application No. 202010607464.4 includes a pretreatment unit, a concentration and decrement unit, and an end curing unit. In the pretreatment unit, a medicament is added to remove heavy metal ions, ammonia nitrogen, COD, solid suspended matters and the like in the desulfurization wastewater, sludge generated by the pretreatment unit is dewatered and then treated, and pretreated effluent enters a concentration and decrement unit. In the concentration and decrement unit, dry hot flue gas is used as a heat source and is in direct contact with the wastewater to exchange heat so as to evaporate and concentrate the wastewater, and slurry generated after concentration enters a tail end solidification unit. In the tail end solidification unit, the concentrated slurry is mixed with fly ash, quicklime, ferrous sulfate, inorganic flocculant and the like and then processed into building materials. According to the technology, the waste water is evaporated and concentrated to be crystallized by adopting the low-temperature flue gas, the heat consumption is large, and the amount of the low-temperature flue gas to be used is large, so that a low-temperature flue gas evaporation and concentration tower is large, and the system investment cost is high; the crystallized salt is recycled for being used as a building material, the proportion of blending fly ash, quicklime and the like is calculated, the product quality is ensured to be qualified, and otherwise, certain environmental protection risk is caused; because the high-concentration chloride ions in the desulfurization wastewater have strong corrosivity, the corrosion resistance level of system equipment is higher, and the investment cost is higher.
③ desulfurization waste water → pretreatment → flash evaporation concentration treatment → flue evaporation drying treatment. For example, in the Chinese patent with the application number of 202010785308.7, the desulfurization wastewater is subjected to dosing, coagulation and clarification treatment and then enters a flash evaporation concentration unit. In the flash evaporation concentration unit, hot air generated by the hot blast stove enters the desorption tower and then is mixed, contacted and heated with the wastewater through the induced draft fan, so that the wastewater is subjected to flash evaporation concentration. And atomizing the concentrated wastewater in a flue evaporation drying unit under the action of a two-fluid atomizing nozzle, mixing the concentrated wastewater with sintering flue gas, and performing secondary evaporation and drying to realize zero emission treatment of the desulfurization wastewater. This patent technique adopts the concentration of flash distillation concentration + flue evaporation drying's technology to realize desulfurization waste water's concentration and zero release processing, but does not carry out passivation treatment to the chloride ion in the desulfurization waste water, and desulfurization waste water still has stronger corrosivity, and consequently the anticorrosive grade of system equipment is higher, and investment cost will be higher to this technology is sintering furnace system application, does not have the application condition at coal fired power plant.
Desulfurization waste water → flue gas heating waste water → multi-effect forced circulation evaporation crystallization treatment. For example, in the Chinese patent with the application number of 202010574952.X, the desulfurization wastewater is heated by using the waste heat of the flue gas, the heated desulfurization wastewater enters multiple-effect forced circulation evaporative crystallization for circulation evaporative crystallization, and the heat source of the multiple-effect forced circulation evaporative crystallization system also adopts the heat of the flue gas, so that the zero emission treatment of the desulfurization wastewater under the gradient utilization of the heat of the flue gas is realized. The technology does not carry out concentration and decrement treatment on the desulfurization wastewater, and the multi-effect forced circulation evaporation crystallization device has larger output; in addition, because high-concentration chloride ions in the desulfurization wastewater have strong corrosivity, the corrosion resistance level of system equipment is high, and the system investment is high; the crystallized salt generated by the evaporative crystallization of the desulfurization wastewater needs to be treated and disposed, so that certain environmental protection risks exist.
Desulfurized wastewater → low-temperature flue gas evaporation concentration treatment → high-temperature flue gas bypass rotary atomization evaporation drying treatment. According to the method, the desulfurization waste water is heated, evaporated and concentrated by using the low-temperature flue gas waste heat at the outlet of a dust remover as the Chinese patent with the application number of 202010858255.7, heavy metal ions are removed by adding the desulfurization waste water after concentration, then the desulfurization waste water enters a bypass flue through a delivery pump and is evaporated and crystallized in a rotary atomization mode, and the heat source of an evaporation system of the bypass flue comes from the high-temperature flue gas before the inlet of an air preheater. In the technology, the concentrated solution of the desulfurization wastewater subjected to low-temperature flue gas evaporation concentration treatment is subjected to clarification treatment by adding a medicament, the water conservancy residence time of a clarification device is longer, and the equipment size and the occupied area are larger; the bypass flue evaporation system in the patent realizes the atomization of wastewater by adopting a rotary atomization mode, and has higher investment cost and operation cost per ton of water for a working condition system with smaller water quantity; because the high-concentration chloride ions in the desulfurization wastewater have strong corrosivity, the corrosion resistance level of system equipment is higher, and the system investment is higher; the bypass flue evaporation system of the patent technology adopts a one-furnace one-tower design, and the system investment and the operation cost are higher for a multi-unit wastewater treatment project.
Therefore, in order to overcome the defects of the various treatment processes, the market urgently needs to develop a coal-fired power plant desulfurization wastewater concentration and reduction and zero-emission treatment process and system with low energy consumption and low investment and operation cost.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide the desulfurization wastewater concentration and zero-discharge treatment process based on flue gas evaporation, which has the advantages of simple and reasonable process design, safety, reliability, low energy consumption and low investment and operation cost.
The technical scheme adopted by the invention for solving the problems is as follows: the desulfurization wastewater concentration and zero emission treatment process based on flue gas evaporation comprises a desulfurization wastewater buffer tank, an integrated coagulation clarification device, a sludge concentration box, a sludge dewatering device, a passivation reaction device, a standby heat source heating device, a low-temperature flue gas evaporation concentration device, a neutralization tank, a precise filtering device and a bypass flue gas evaporation drying device, wherein the desulfurization wastewater buffer tank is connected with the integrated coagulation clarification device, the integrated coagulation clarification device is connected with the passivation reaction device, the passivation reaction device is connected with the standby heat source heating device, the standby heat source heating device is connected with the low-temperature flue gas evaporation concentration device, the low-temperature flue gas evaporation concentration device is connected with the neutralization tank, the neutralization tank is connected with the precise filtering device, and the precise filtering device is connected with the bypass flue gas evaporation drying device; sludge thickening case is connected with the clarification device that thoughtlessly congeals of integration, and sludge dewatering device is connected its characterized in that with sludge thickening case: the method comprises the following specific steps:
s1: the desulfurization wastewater in the desulfurization wastewater buffer tank is pumped to an integrated coagulation and clarification device through a wastewater lifting pump, and the sludge of the integrated coagulation and clarification device enters a sludge concentration tank through a sludge discharge pipe;
s2: after sludge generated by the integrated coagulation and clarification device is kept stand and concentrated in the sludge concentration box, supernatant is conveyed to an inlet of the integrated coagulation and clarification device through a clear water pump for treatment, the concentrated sludge is conveyed to a sludge dewatering device through a sludge conveying pump for dewatering treatment, mud cakes are transported outside for treatment, and clear water generated by the sludge dewatering device is also conveyed to the inlet of the integrated coagulation and clarification device for treatment;
s3: the effluent of the integrated coagulation and clarification device enters a passivation reaction device;
s4: the water discharged from the passivation reaction device enters a standby heat source heating device for heating, and the heated wastewater is pumped to a low-temperature flue gas evaporation and concentration device for concentration treatment;
s5: the heat source of the low-temperature flue gas evaporation and concentration device adopts low-temperature flue gas at the outlet of an induced draft fan, the waste water is subjected to evaporation and concentration treatment, and the generated concentrated solution is pumped to a neutralization tank through a concentrated solution pump for treatment;
s6: a NaOH dosing system, a stirrer, a pH meter, a liquid level meter, a corresponding instrument and a valve are matched and arranged in the neutralization tank, and the pH of the concentrated solution is adjusted to be more than 8 in the neutralization tank;
s7: after the pH of the concentrated solution is adjusted in the neutralization tank, the concentrated solution is conveyed to a precise filtering device for treatment through a wastewater pump, and the effluent of the precise filtering device enters a bypass flue evaporation drying device for evaporation drying treatment;
s8: the bypass flue evaporation drying device is provided with two paths of high-temperature flue gas inlet flues which are respectively taken from SCR (selective catalytic reduction) outlet flues of the two units, wherein the two paths of high-temperature flue gas inlet flues are provided with flue gas baffle doors, the flow of the high-temperature flue gas is adjusted according to the amount of the treated wastewater, and the outlet flues of the bypass flue evaporation drying device are provided with one set and connected to a main flue in front of the inlet of a dust remover of one unit.
Preferably, in S1 of the present invention, the integrated coagulation and clarification device is provided with a stirrer, an integrated coagulant adding device, an inclined plate clarifier, a sludge hopper, a sludge discharge pipe, and a valve and a level meter which are matched with the sludge hopper and the sludge discharge pipe.
Preferably, in S1, the content of the solid suspended matters in the effluent of the integrated coagulation and clarification device is reduced to below 20 mg/L; the capacity of the sludge concentration tank is not less than 10 hours of sludge production.
Preferably, in S2 of the present invention, the water content of the sludge concentrated in the sludge concentrating tank is not less than 5%, and the water content of the sludge cake after the sludge dewatering treatment is not less than 45%.
Preferably, in the S3, a stirrer, a passivating agent dosing device, an attached valve and a level meter are arranged in the passivation reaction device; the content of free chloride ions in the effluent of the passivation reaction device is controlled below 1000 mg/L.
Preferably, in S4 of the present invention, the backup heat source heating device uses hot water, steam exhaust or hot air in an air cooling tower; heating the waste water to 80-90 ℃.
Preferably, in S5 of the present invention, the low temperature flue gas evaporative concentration apparatus includes an evaporative concentration tower, a booster fan, a circulation pump, a disturbance pump, a concentrated liquid discharge pump, a demister, an inlet/outlet flue, a baffle door, a flowmeter, a level meter, a pH meter, and an attached valve; controlling the salt content of the concentrated solution within 250000 mg/L.
Preferably, in S6 of the present invention, the neutralization tank has a volume that satisfies the amount of the concentrated solution produced in 1 hour or more.
Preferably, in S7 of the present invention, a precision filter screen is disposed in the precision filter device, the precision filter screen is made of 2205 alloy steel or 316L stainless steel, and suspended particles with a particle size greater than 10 μm are filtered and removed; the precise filtering device is matched with a backwashing pump and a pressure gauge, the backwashing pump is started to automatically wash the filter screen according to pressure signals on two sides of the filter screen, backwashing water is taken from the neutralization pond, and backwashing sludge is conveyed to the sludge dewatering device through the slurry pump for dewatering treatment.
Preferably, in S8 of the present invention, the atomizing device associated with the bypass flue evaporation drying device employs a two-fluid atomizing or rotary atomizing system; the bypass flue evaporation drying device is matched with a powder bin and a bin pump, and the fly ash at the bottom of the drying tower is periodically conveyed to an ash bin; the bypass flue evaporation drying device is matched with auxiliary equipment provided with a waste water flowmeter, a smoke flowmeter, a thermometer corresponding instrument and a valve.
Compared with the prior art, the invention has the following advantages and effects: (1) the process reduces the activity and corrosivity of chloride ions by utilizing passivation and complexing free chloride ions in the desulfurization wastewater, so that the corrosion resistance grade of a flow passage device of related equipment is reduced, the system investment and maintenance cost can be obviously reduced, and the safety and stability of system operation are improved; (2) the process utilizes the heat of the low-temperature flue gas to be coupled with the heat of the standby heat source to heat the wastewater, can utilize partial waste heat, reduce the use amount of the low-temperature flue gas, reduce the investment and the operation cost of a concentration system, and adopts multi-heat-source coupling to ensure that the system operation is less influenced by the unit load, thereby improving the flexibility and the stability of the system operation; (3) the bypass flue evaporation device in the process adopts a two-furnace one-tower design, can flexibly cope with water volume change, improves the commissioning rate of a system device, and saves system investment and operation cost.
Drawings
Fig. 1 is a schematic structural diagram of an embodiment of the present invention.
In the figure: desulfurization waste water buffer pool 1, integration clarification device 2 that thoughtlessly congeals, sludge thickening case 3, sludge dewatering device 4, passivation reaction device 5, reserve heat source heating device 6, low temperature flue gas evaporative concentration device 7, neutralization pond 8, precision filtration device 9, bypass flue evaporation drying device 10.
Detailed Description
The present invention will be described in further detail below by way of examples with reference to the accompanying drawings, which are illustrative of the present invention and are not to be construed as limiting the present invention.
Examples are given.
Referring to fig. 1, the desulfurization wastewater concentration and zero-emission treatment process based on flue gas evaporation of the embodiment includes a desulfurization wastewater buffer tank 1, an integrated coagulation and clarification device 2, a sludge concentration tank 3, a sludge dewatering device 4, a passivation reaction device 5, a standby heat source heating device 6, a low-temperature flue gas evaporation and concentration device 7, a neutralization tank 8, a precise filtering device 9 and a bypass flue evaporation and drying device 10; the desulfurization (high-salt) wastewater buffer tank 1 is connected with an integrated coagulation and clarification device 2, the integrated coagulation and clarification device 2 is connected with a passivation reaction device 5, the passivation reaction device 5 is connected with a standby heat source heating device 6, the standby heat source heating device 6 is connected with a low-temperature flue gas evaporation and concentration device 7, the low-temperature flue gas evaporation and concentration device 7 is connected with a neutralization tank 8, the neutralization tank 8 is connected with a precise filtering device 9, and the precise filtering device 9 is connected with a bypass flue evaporation and drying device 10; the sludge concentration box 3 is connected with the integrated coagulation and clarification device 2, and the sludge dewatering device 4 is connected with the sludge concentration box 3.
The water quality and the water quantity of the desulfurization wastewater generated by a certain thermal power generating unit are as follows: electric conductivity of 52000 μ s/cm, TDS43000mg/L, chloride ion concentration of 13600mg/L, suspended solid content of 35000mg/L, and water amount of 20m3H is used as the reference value. By adopting the process for treatment and integrated coagulation clarification treatment, the concentration of suspended solids is reduced to be below 20mg/L, heavy metal ions (Cr, Cd, Hg, Pb, Cu and the like) are effectively removed, and the discharge standard is met. The effluent water after the integrated coagulation clarification treatment enters a passivation treatment system, chloride ions are complexed under the action of a secondary passivation agent, the concentration of free chloride ions is obviously reduced (reduced to below 1000 mg/L), and the passivation treatment effluent water is heated to about 85 ℃ in a standby heat source heating device 6 and then enters a low-temperature flue gas evaporation and concentration device 7. The concentration multiple of the waste water is controlled to be 5-5.5 times by controlling the use amount of the low-temperature flue gas and the running mode of the circulating pump, and the water amount of the concentrated solution is about 3.5-4m3The TDS is about 220000mg/L, and the pH is about 1.5. The pH of the concentrated solution is adjusted to about 8.5 in a neutralization pond 8, and then the concentrated solution enters a bypass flue evaporation drying system for treatment, and the treated water amount is 3.5-4m3Under the working condition of/h, the high-temperature flue gas amount of an SCR outlet which is led from 2 units is about 40000m3The temperature of the flue gas is about 345 ℃, the temperature of the flue gas at the outlet of the evaporation drying tower is about 145 ℃, and the outlet flue gas enters a main flue in front of the inlet of the dust remover of one unit. By implementing the process, the high-efficiency and low-cost concentration and decrement and zero-emission treatment of the desulfurization wastewater of the thermal power plant can be realized.
Compared with the conventional low-temperature flue gas evaporation concentration-high-temperature flue gas evaporation drying treatment process, the process has the advantages that the stability and flexibility of system operation are obviously improved, and the requirement on the corrosion resistance of an overflowing device of the system is lowered, so that the equipment investment of the system is obviously reduced (the equipment cost per ton of water treatment device is reduced by more than 20 ten thousand yuan).
The desulfurization wastewater concentration and zero-emission treatment process based on flue gas evaporation comprises the following steps:
s1: the desulfurization wastewater in the desulfurization wastewater buffer tank 1 is pumped to an integrated coagulation and clarification device 2 through a wastewater lifting pump, and a stirrer, an integrated coagulant dosing device, an inclined plate clarifier, a sludge hopper, a sludge discharge pipe, a matched valve, a liquid level meter and the like are arranged in the integrated coagulation and clarification device 2. The content of solid suspended matters in the effluent of the integrated coagulation and clarification device 2 is reduced to be below 20mg/L, and heavy metal ions are effectively removed and can meet the requirements of the relevant standard of Integrated wastewater discharge Standard (GB 8978-1996); the sludge of the integrated coagulation and clarification device 2 enters a sludge concentration tank 3 (the capacity of the sludge is not less than 10 hours of sludge production) through a sludge discharge pipe.
S2: after the sludge generated by the coagulation clarification device is statically concentrated in the sludge concentration tank 3, supernatant is conveyed to the inlet of the integrated coagulation clarification device 2 through a clear water pump for treatment, the concentrated sludge is conveyed to the sludge dewatering device 4 through a sludge conveying pump for dewatering treatment, mud cakes are transported outside for treatment, and clear water generated by the sludge dewatering device 4 is also conveyed to the inlet of the integrated coagulation clarification device 2 for treatment. The water content of the concentrated sludge in the sludge concentration tank 3 is usually not less than 5%, and the water content of the sludge cake after the sludge dewatering machine treatment is usually not less than 45%.
S3: effluent of the integrated coagulation and clarification device 2 enters a passivation reaction device 5, and a stirrer, a passivating agent dosing device, an attached valve, a liquid level meter and the like are arranged in the passivation reaction device 5. The hydraulic retention time of the passivation device is generally not less than 30 minutes, the passivation medicament adopts a special organic polymer chelating agent and can strongly complex chloride ions, so that the chloride ions are changed from a free state to a complex state, and the content of the free chloride ions in the effluent of the passivation treatment device can be controlled below 1000 mg/L.
S4: the water discharged from the passivation treatment device enters a standby heat source heating device 6 for heating. The standby heat source can adopt hot water, exhaust steam or hot air in an air cooling tower, and the standby heat source heats the wastewater after passivation treatment through a heat exchange device (fluorine plastic, ND steel fins, 2205 alloy steel fins and the like can be adopted). The heating temperature of the waste water is controlled by adjusting the standby heat source flow, the waste water is usually heated to 80-90 ℃, and the heated waste water is sent to the low-temperature flue gas evaporation and concentration device 7 by a waste water pump for concentration treatment.
S5: the heat source of the low-temperature flue gas evaporation and concentration device 7 adopts low-temperature flue gas at the outlet of an induced draft fan, and the low-temperature flue gas evaporation and concentration device 7 mainly comprises an evaporation and concentration tower, a booster fan, a circulating pump, a disturbance pump, a concentrated solution discharge pump, a demister, an inlet and outlet flue, a baffle door, meters such as a flowmeter, a liquid level meter and a pH meter, and auxiliary valves. The heated wastewater is directly contacted with low-temperature flue gas in an evaporation concentration tower for heat exchange and evaporation concentration, and the wastewater is circularly heated, evaporated and concentrated to the expected concentration multiple by controlling the flow rate of the low-temperature flue gas and the running mode of a circulating pump. After the wastewater is evaporated and concentrated in the evaporation concentration tower, the evaporated water vapor enters the desulfurization system along with the flue gas in the front flue of the inlet of the desulfurization tower for treatment, and the generated concentrated solution (usually, the salt content of the concentrated solution is controlled within 250000mg/L, so that crystallization and scaling are avoided) is pumped to the neutralization tank 8 for treatment through the concentrated solution pump.
S6: the neutralization tank 8 is provided with a NaOH dosing system, a stirrer, a pH meter, a liquid level meter and other instruments and valves in a matched manner, the pH of the concentrated solution is adjusted to be more than 8 in the neutralization tank 8, and the volume of the neutralization tank 8 meets the concentrated solution production amount of more than 1 hour.
S7: the concentrated solution is sent to a precise filtering device 9 for treatment through a wastewater pump after the pH value of the concentrated solution is adjusted in a neutralization tank 8, a precise filter screen (the material is 2205 alloy steel, 316L stainless steel and the like, the aperture can be selected and matched according to the requirement) is arranged in the precise filtering device 9, and suspended particles with the particle size larger than 10 mu m can be filtered and removed. The precise filtering device 9 is matched with a backwashing pump and a pressure gauge, the backwashing pump is started to automatically wash the filter screen according to pressure signals on two sides of the filter screen, backwashing water can be taken from the neutralization pond 8, and backwashing sludge is conveyed to the sludge dewatering device 4 through the slurry pump for dewatering treatment. And the outlet water of the precise filtering device 9 enters a bypass flue evaporation drying device 10 for evaporation drying treatment.
S8: the bypass flue evaporation drying device 10 is provided with two paths of high-temperature flue gas inlet flues which are respectively taken from SCR outlet flues of two units, wherein the two paths of high-temperature flue gas inlet flues are provided with flue gas baffle doors, the flow of the high-temperature flue gas can be adjusted according to the amount of waste water to be treated, and the outlet flue of the bypass flue evaporation drying device 10 is provided with one set which is connected to a main flue in front of the inlet of a dust remover of one unit. The atomization device matched with the bypass flue evaporation drying device 10 can adopt a double-fluid atomization or rotary atomization system (different atomization modes need to be matched with corresponding auxiliary equipment, and the sizes of corresponding bypass flue evaporation drying towers are different and can be calculated according to parameters such as evaporation water quantity and the like); the bypass flue evaporation drying device 10 is matched with a powder bin and a bin pump, and the fly ash at the bottom of the drying tower is periodically conveyed to an ash bin; the bypass flue evaporation drying device 10 is provided with a waste water flowmeter, a flue gas flowmeter, a thermometer and other instruments and valves and other auxiliary equipment in a matching way.
And will be apparent to those skilled in the art from the foregoing description.
In addition, it should be noted that the specific embodiments described in the present specification may be different in the components, the shapes of the components, the names of the components, and the like, and the above description is only an illustration of the structure of the present invention. Equivalent or simple changes in the structure, characteristics and principles of the invention are included in the protection scope of the patent. Various modifications, additions and substitutions for the specific embodiments described may be made by those skilled in the art without departing from the scope of the invention as defined in the accompanying claims.
Claims (10)
1. A desulfurization waste water concentration and zero emission treatment process based on flue gas evaporation comprises a desulfurization waste water buffer tank (1), an integrated coagulation clarification device (2), a sludge concentration box (3), a sludge dewatering device (4), a passivation reaction device (5), a standby heat source heating device (6), a low-temperature flue gas evaporation concentration device (7), a neutralization tank (8), a precise filtering device (9) and a bypass flue gas evaporation drying device (10), wherein the desulfurization waste water buffer tank (1) is connected with the integrated coagulation clarification device (2), the integrated coagulation clarification device (2) is connected with the passivation reaction device (5), the passivation reaction device (5) is connected with the standby heat source heating device (6), the standby heat source heating device (6) is connected with the low-temperature flue gas evaporation concentration device (7), and the low-temperature flue gas evaporation concentration device (7) is connected with the neutralization tank (8), the neutralization pond (8) is connected with a precise filtering device (9), and the precise filtering device (9) is connected with a bypass flue evaporation drying device (10); sludge thickening case (3) are connected with integration coagulation and clarification device (2), and sludge dewatering device (4) are connected its characterized in that with sludge thickening case (3): the method comprises the following specific steps:
s1: the desulfurization wastewater in the desulfurization wastewater buffer tank (1) is pumped to an integrated coagulation and clarification device (2) through a wastewater lifting pump, and the sludge of the integrated coagulation and clarification device (2) enters a sludge concentration tank (3) through a sludge discharge pipe;
s2: after sludge generated by the integrated coagulation and clarification device (2) is kept stand and concentrated in the sludge concentration tank (3), supernatant is conveyed to an inlet of the integrated coagulation and clarification device (2) through a clear water pump for treatment, the concentrated sludge is conveyed to a sludge dewatering device (4) through a sludge conveying pump for dewatering treatment, mud cakes are transported outside for treatment, and clear water generated by the sludge dewatering device (4) is also conveyed to an inlet of the integrated coagulation and clarification device (2) for treatment;
s3: the effluent of the integrated coagulation and clarification device (2) enters a passivation reaction device (5);
s4: the effluent of the passivation reaction device (5) enters a standby heat source heating device (6) for heating, and the heated wastewater is pumped to a low-temperature flue gas evaporation and concentration device (7) for concentration treatment;
s5: the heat source of the low-temperature flue gas evaporation and concentration device (7) adopts low-temperature flue gas at the outlet of an induced draft fan, the waste water is subjected to evaporation and concentration treatment, and the generated concentrated solution is pumped to a neutralization tank (8) through a concentrated solution pump for treatment;
s6: a NaOH dosing system, a stirrer, a pH meter, a liquid level meter corresponding instrument and a valve are arranged in the neutralization tank (8) in a matched manner, and the pH of the concentrated solution is adjusted to be more than 8 in the neutralization tank (8);
s7: after the pH of the concentrated solution is adjusted in the neutralization tank (8), the concentrated solution is conveyed to a precise filtering device (9) through a wastewater pump for treatment, and the effluent of the precise filtering device (9) enters a bypass flue evaporation drying device (10) for evaporation drying treatment;
s8: the bypass flue evaporation drying device (10) is provided with two paths of high-temperature flue gas inlet flues which are respectively taken from SCR outlet flues of two units, wherein the two paths of high-temperature flue gas inlet flues are provided with flue gas baffle doors, the flow of the high-temperature flue gas is adjusted according to the amount of waste water to be treated, and the outlet flues of the bypass flue evaporation drying device (10) are provided with one set and connected to a main flue in front of the inlet of a dust remover of one unit.
2. The desulfurization wastewater concentration and zero-emission treatment process based on flue gas evaporation as claimed in claim 1, characterized in that: and in the S1, the integrated coagulation and clarification device (2) is internally provided with a stirrer, an integrated coagulant dosing device, an inclined plate clarifier, a sludge hopper, a sludge discharge pipe, a matched valve and a matched liquid level meter.
3. The desulfurization wastewater concentration and zero-emission treatment process based on flue gas evaporation as claimed in claim 1, characterized in that: in the S1, the content of solid suspended matters in the effluent of the integrated coagulation and clarification device (2) is reduced to below 20 mg/L; the capacity of the sludge concentration tank (3) is not less than the sludge production amount in 10 hours.
4. The desulfurization wastewater concentration and zero-emission treatment process based on flue gas evaporation as claimed in claim 1, characterized in that: in the S2, the water content of the concentrated sludge of the sludge concentration box (3) is not less than 5%, and the water content of the mud cake treated by the sludge dewatering machine is not less than 45%.
5. The desulfurization wastewater concentration and zero-emission treatment process based on flue gas evaporation as claimed in claim 1, characterized in that: in the S3, a stirrer, a passivator dosing device, an attached valve and a liquid level meter are arranged in the passivation reaction device (5); the content of free chloride ions in the effluent of the passivation reaction device (5) is controlled below 1000 mg/L.
6. The desulfurization wastewater concentration and zero-emission treatment process based on flue gas evaporation as claimed in claim 1, characterized in that: in the step S4, the standby heat source heating device (6) adopts hot water, dead steam or hot air in an air cooling tower; heating the waste water to 80-90 ℃.
7. The desulfurization wastewater concentration and zero-emission treatment process based on flue gas evaporation as claimed in claim 1, characterized in that: in the S5, the low-temperature flue gas evaporation concentration device (7) comprises an evaporation concentration tower, a booster fan, a circulating pump, a disturbance pump, a concentrated liquid discharge pump, a demister, an inlet and outlet flue, a baffle door, a flowmeter, a liquid level meter, a pH meter corresponding instrument and an auxiliary valve; controlling the salt content of the concentrated solution within 250000 mg/L.
8. The desulfurization wastewater concentration and zero-emission treatment process based on flue gas evaporation as claimed in claim 1, characterized in that: in S6, the volume of the neutralization tank (8) satisfies the amount of the concentrated solution produced for 1 hour or more.
9. The desulfurization wastewater concentration and zero-emission treatment process based on flue gas evaporation as claimed in claim 1, characterized in that: in the step S7, a precise filter screen is arranged in the precise filter device (9), the precise filter screen is made of 2205 alloy steel or 316L stainless steel, and suspended particles with the particle size larger than 10 mu m are filtered and removed;
the precise filtering device (9) is matched with a backwashing pump and a pressure gauge, the backwashing pump is started to automatically wash the filter screen according to pressure signals on two sides of the filter screen, backwashing water is taken from the neutralization pond (8), and backwashing sludge is conveyed to the sludge dewatering device (4) through the slurry pump for dewatering treatment.
10. The desulfurization wastewater concentration and zero-emission treatment process based on flue gas evaporation as claimed in claim 1, characterized in that: in the S8, an atomization device matched with the bypass flue evaporation drying device (10) adopts a double-fluid atomization or rotary atomization system; the bypass flue evaporation drying device (10) is matched with a powder bin and a bin pump, and the fly ash at the bottom of the drying tower is periodically conveyed to an ash bin; the bypass flue evaporation drying device (10) is matched with auxiliary equipment provided with a waste water flowmeter, a smoke flowmeter, a thermometer corresponding instrument and a valve.
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| CN117521963A (en) * | 2023-11-14 | 2024-02-06 | 大唐环境产业集团股份有限公司 | Desulfurization wastewater bypass hot flue gas evaporation coal consumption influence evaluation method, device and medium |
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| CN110759567A (en) * | 2019-10-22 | 2020-02-07 | 武汉天空蓝环保科技有限公司 | Chloride ion passivator, preparation method and desulfurization wastewater treatment method |
| CN111908696A (en) * | 2020-08-24 | 2020-11-10 | 西安热工研究院有限公司 | Zero-discharge system and method for flue gas and water co-treatment of desulfurization wastewater |
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| CN110759567A (en) * | 2019-10-22 | 2020-02-07 | 武汉天空蓝环保科技有限公司 | Chloride ion passivator, preparation method and desulfurization wastewater treatment method |
| CN111908696A (en) * | 2020-08-24 | 2020-11-10 | 西安热工研究院有限公司 | Zero-discharge system and method for flue gas and water co-treatment of desulfurization wastewater |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117521963A (en) * | 2023-11-14 | 2024-02-06 | 大唐环境产业集团股份有限公司 | Desulfurization wastewater bypass hot flue gas evaporation coal consumption influence evaluation method, device and medium |
| CN117521963B (en) * | 2023-11-14 | 2024-07-16 | 大唐环境产业集团股份有限公司 | Desulfurization wastewater bypass hot flue gas evaporation coal consumption influence evaluation method, device and medium |
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