CN102000489A - Thermal power plant wet desulfurization agent and its desulfurization method - Google Patents

Abstract

A wet desulfurizing agent for thermal power plant and its desulfurizing method are disclosed, which comprises a desulfurizing absorption tower, the desulfurizing absorption tower is provided with: the saturated absorption liquid that is in the lime stone, absorption liquid overflow pipe and fluid infusion pipe on the absorption tower lateral wall, flue gas entry, absorption liquid spray zone, defroster and exhanst gas outlet, and its technical essential is: adding adipic acid into the saturated absorption liquid, wherein the solute weight ratio of the adipic acid to the limestone is 0.2-0.3: 100, pumping the desulfurizer into the spray layer by a circulating pump and spraying the desulfurizer in a mist form, washing the desulfurizer in a countercurrent manner with sulfur-containing flue gas entering the desulfurization absorption tower through a flue gas inlet at the moment and absorbing the sulfur, and discharging the flue gas through a demister and a flue gas outlet. The invention can realize the clean SO of the flue gas of the power plant caused by the change of the coal types₂The concentration reaches the standard and is discharged, and low load and raw flue gas SO can be realized₂On the premise of lower concentration, the operation number of the pumps is reduced by changing the combination mode of the circulating pumps, so that the economic and energy-saving operation of the desulfurization system is realized.

Description

Thermal power plant wet desulfurization agent and its desulfurization method

technical field

The invention relates to the technical field of desulfurization technology for thermal power plants, in particular to a thermal power plant wet desulfurizer and a desulfurization method thereof.

Background technique

With the comprehensive development of my country's flue gas desulfurization industrialization, limestone gypsum wet desulfurization process has become the preferred process for coal-fired power plants in my country due to its wide adaptability, mature process, high desulfurization efficiency, rich source of desulfurizer and low price. At present, the localization rate of desulfurization equipment has reached over 90%.

However, due to changes in domestic coal power supply and demand, in the actual operation of the power plant, due to the constraints of coal type and other factors, the flue gas volume at the inlet of the desulfurization system and the concentration of sulfur dioxide in the flue gas often exceed the design value, which causes the actual desulfurization system. The efficiency is low and the relevant performance parameters are not good, and the energy consumption of the desulfurization system is serious.

In recent years, various domestic power plants have successively launched large-scale flue gas desulfurization facilities. However, due to coal quality supply problems, the actual coal quality of the power plant is often very different from the design coal quality, and the power plant cannot operate with the design coal quality. The sulfur content of the pieced together coal quality varies greatly, which causes large fluctuations in the concentration of sulfur dioxide in the original flue gas, unstable operation of the desulfurization system, and the desulfurization efficiency will be significantly lower than the design value when the concentration of sulfur dioxide is too high. It also causes poor quality of desulfurization by-product gypsum and low utilization rate of limestone. In order to avoid excessive emissions, the power plant adopts the method of increasing the supply of limestone, which still cannot solve the problem of high sulfur dioxide emission concentration and also increases the energy consumption of the system operation. Out of helplessness, some power plants have to choose load-limited operation, thus cause great loss.

Introduction of Existing Wet Desulfurization Process

At present, more than 95% of thermal power units in China are equipped with wet desulfurization systems. The principle of wet desulfurization process is that the mixture of limestone and water is sent from the slurry pool of the absorption tower to the spray layer when fresh limestone is added; The slurry is atomized into mist droplets with a certain diameter through the nozzle on the spray layer; during the falling process of the mist droplets, it is in countercurrent contact with the rising flue gas in the absorption tower, and the mist droplets will absorb the acid components in the liquid, such as SO ₂ , SO ₃ , HF and HCl removal; the clean flue gas leaving the washing part of the absorption tower passes through the demister to remove the entrained liquid droplets, and the liquid droplets return to the absorption tower, while the clean flue gas is directly discharged through the chimney. The main process of the desulfurization system is as follows:

(1) Mix and add the saturated absorption liquid of limestone and water;

(2) absorb sulfur dioxide in the flue gas and react to generate calcium sulfite;

(3) Introducing air to forcibly oxidize calcium sulfite to generate gypsum;

(4) Separation of gypsum from the absorption liquid.

The flue gas from the boiler enters the absorption tower through the electrostatic precipitator, induced draft fan, and booster fan. After washing and desulfurization, the fine droplets are removed through the demister.

The absorbent is prepared by dissolving limestone (CaCO ₃ ) with an appropriate amount of water. According to the pH value of the slurry in the absorption tower and the mass concentration of SO ₂ in the original flue gas, a quantitative amount of absorbent slurry is added to the absorption tower through a circulating pump. The chemical reaction in the absorption tower mainly has the following processes:

(1) Absorption process

(2) Oxidation process

(3) Neutralization process

The total chemical reaction formula in the absorption tower is:

The gypsum slurry in the absorption tower is sent to the gypsum hydrocyclone station through the gypsum discharge pump, and the concentrated gypsum slurry is collected into the gypsum slurry tank, and then sent to the vacuum belt dehydrator by the gypsum slurry pump. The gypsum slurry entering the vacuum belt dehydrator is dehydrated and has a surface moisture content of less than 10%. The gypsum slurry is sent to the gypsum storage room by the belt conveyor for comprehensive utilization. The overflow liquid of the gypsum cyclone is collected by the overflow box and sent to the corresponding waste water cyclone. The overflow liquid of the waste water cyclone returns to the absorption tower for recycling.

Considering the high cost of desulfurization system transformation and the difficulty of transformation space, it is difficult to change the design of the desulfurization system. In order to improve the desulfurization efficiency, adding desulfurization additives is an effective method.

Contents of the invention

The object of the present invention is to provide a thermal power plant wet desulfurization agent and a desulfurization method thereof which can improve the desulfurization efficiency of the system under different working conditions. That is, organic acid is used to improve the desulfurization efficiency, so as to prevent SO ₂ from being able to meet the standard emission after using high-sulfur coal quality.

The object of the present invention is achieved like this: described thermal power plant wet desulfurizer, it comprises: the saturated absorbing liquid of limestone and water in saturated state or supersaturated state, it is characterized in that: in saturated absorbing liquid, add Diacid, the solute weight and number ratio of adipic acid and limestone in the saturated absorption liquid is 0.2-0.3:100.

The above-mentioned limestone has a purity of more than 90%, and its particle size distribution is 90% passing through a 250-mesh sieve; the adipic acid has a purity of more than 99.7%, and is a white powder.

The desulfurization method of the wet desulfurizer of the present invention comprises a desulfurization absorption tower, and the desulfurization absorption tower is sequentially arranged with: saturated absorption liquid of limestone and water in a saturated state or a supersaturated state, on the side wall of the absorption tower The saturated absorption liquid overflow pipe and liquid replenishment pipe, the flue gas inlet, the saturated absorption liquid spray area, the demister and the flue gas outlet after desulfurization are characterized in that: adipic acid is added to the saturated absorption liquid, and the saturated absorption liquid The solute weight ratio of adipic acid and limestone in the liquid is 0.2-0.3:100, and it becomes a desulfurization agent; the desulfurization agent is pumped into the spray layer through a circulation pump and sprayed out in mist form. After the sulfur dioxide-containing flue gas of the desulfurization absorption tower is washed countercurrently, after the sulfur dioxide is absorbed, the flue gas is discharged through the demister and the flue gas outlet at the top of the desulfurization absorption tower, and then discharged into the atmosphere through the chimney;

The desulfurizer absorbs sulfur dioxide in the flue gas and reacts to form calcium sulfite, introduces air to force the oxidation of calcium sulfite to form gypsum, and separates the gypsum from the saturated absorption liquid;

The temperature range of the saturated absorption liquid is 50-65°C.

The saturated absorption liquid overflow pipe and liquid replenishment pipe all lead into a pit circulation pool of a desulfurization absorption tower with an agitator, and adipic acid is added through the pit circulation pool of the absorption tower until it is in a saturated state or In the saturated absorption solution of supersaturated limestone and water.

The mechanism of action of adipic acid:

When the _CaCO solution containing adipic acid is used for the reaction of absorbing SO ₂ , there are mainly the following main reactions:

Among them: H ₂ A - adipic acid;

AH ^- , A ^2-- ——Ions produced by the hydrolysis of adipic acid.

aq, s, l—represent the gas phase, solid phase, and liquid phase, respectively.

The whole reaction process involves three interphase processes of gas-liquid, liquid-liquid and liquid-solid. The whole reaction process is shown in the table below:

Limestone gypsum process of the present invention Adipic acid strengthens limestone and SO _Mass transfer mechanism

As can be seen from the table above, on the surface of the gas phase and in the liquid film, dissolved _SO2 reacts with water to dissociate into H ⁺ according to the formula (1); at the boundary of the liquid film and the main body of the liquid phase, AH ^- and H ⁺ are expressed according to the formula ( 2) The reaction generates H ₂ A(aq), so that H ⁺ is transferred to the main body of the liquid phase, and the decrease of [H ⁺ ] concentration in the liquid film accelerates the equilibrium shift of formula (1) to the right, thereby promoting the dissolution of SO ₂ , Then the desulfurization efficiency is improved; in the solid phase and liquid film, the dissolved CO ₃ ^2- of formula (6) reacts with the dissociated H ⁺ of formula (3) to generate HCO ₃ ^- according to formula (5); in the liquid phase, H ⁺ reacts with HCO ₃ ^- to generate CO ₂ and H ₂ O according to formula (4), and the decrease of [HCO ₃ ^- ] concentration in the liquid phase body makes the equilibrium of formula (5) and formula (6) shift to the right, thereby promoting Dissolution of CaCO ₃ .

From the above analysis, it can be seen that the presence of adipic acid strengthens the transfer from the gas phase to the solid phase, and at the same time promotes the dissolution of SO ₂ and CaCO ₃ , and accelerates the chemical absorption of SO ₂ , thus improving the desulfurization efficiency.

If the ratio of adipic acid to limestone is too low: the amount of adipic acid is insufficient, the H ₂ A(aq) generated by the reaction of formula (2) will decrease, the effect of adipic acid on enhancing H ⁺ transfer will be reduced, and the effect on improving the activity of limestone will be reduced. Also worse.

If the ratio of adipic acid to limestone is too high: the amount of adipic acid is too high. At this time, there is still a surplus of adipic acid compared with the amount required to improve the activity of limestone, which is not only uneconomical, but also because adipic acid is a weak acid. The presence of a large amount of adipic acid will reduce the pH value of the slurry, which will have a negative effect on the desulfurization efficiency.

The advantages of the present invention are:

In particular, the present invention has carried out research on the addition of adipic acid in a wet desulfurization system on a 600MW unit, and obtained an unexpected desulfurization effect.

The research of the present invention combines the two parts of the laboratory and the field application of the project, and analyzes the comprehensive influence of adipic acid on the desulfurization system in multiple directions, and proposes a new energy-saving operation optimization scheme for the desulfurization system, which significantly improves the efficiency of the wet desulfurization system. Desulfurization efficiency.

The desulfurizing agent of the present invention can not only realize that the _SO2 concentration in the net flue gas of the power plant reaches the standard discharge due to the change of the coal type, but also exempts the penalty for exceeding the standard. It can also be realized under the premise of low load and low concentration of SO ₂ in the original flue gas, by changing the combination of circulating pumps to reduce the number of pumps running, realize the economical and energy-saving operation of the desulfurization system, reduce the power consumption rate of the plant, and save millions of dollars per year The electricity bill has very good practical significance. And it can avoid the loss caused by the load limit operation of the power plant because the operating parameters exceed the design value. In addition, it can improve the operational flexibility and fuel flexibility of the system, alleviate system fouling and blockage, adapt to sudden changes in the original flue gas SO ₂ concentration, buffer changes in slurry pH, and reduce the operating loss of the slurry circulation pump impeller, etc. Therefore, the application prospect is very broad.

The invention also has the advantages of simple process, no change to the original device, low operation and operation cost, wide application range and the like.

Description of drawings

Fig. 1 is a schematic diagram of the process flow of the present invention.

The present invention will be described in further detail below by examples, but following examples are only examples of the present invention, and do not represent the limited scope of rights protection of the present invention, and the scope of protection of rights of the present invention is as the criterion with claims.

Detailed ways

As shown in Figure 1, Fig. 1 is the desulfurization technological process schematic diagram that the present invention is applied on the No. 2 600MW unit of Guodian Kangping Power Plant;

6 in the figure is a desulfurization absorption tower, and the desulfurization absorption tower 6 is arranged sequentially from bottom to top: a supersaturated absorption liquid 601 of supersaturated limestone and water, a saturated absorption liquid overflow pipe on the side wall of the absorption tower and Liquid replenishment pipe inlet and outlet 602, flue gas inlet 603, saturated absorption liquid spray area 604, demister 605 and flue gas outlet 606 after desulfurization; Desulfurization absorption tower pit circulation pool 4, adipic acid is added or added to the supersaturated absorption liquid of supersaturated limestone and water through the absorption tower pit circulation pool. When the temperature is 50-65°C, the solute weight ratio of adipic acid and limestone in the supersaturated absorption liquid is 0.2-0.3:100, thus becoming a desulfurizer.

The use of limestone supersaturated absorption solution is mainly to relatively reduce the input times of limestone.

1 in the figure is the flue gas dust collector. The flue gas containing pollutants from the tail of the boiler first passes through the dust collector 1 for dust removal treatment, and then enters the desulfurization absorption from the middle flue gas inlet 603 of the desulfurization absorption tower 6 through the booster fan 2. In the tower; while the desulfurizer is pumped into the saturated absorption liquid spray layer 604 through the circulation pump 7 and sprayed out in mist form. At this time, after countercurrent washing with the sulfur dioxide-containing flue gas entering the desulfurization absorption tower through the flue gas inlet 603, the sulfur dioxide is absorbed , the flue gas is discharged through the mist eliminator 605 and the flue gas outlet 606 at the top of the desulfurization absorption tower, and then discharged into the atmosphere through the chimney 8 .

In addition, the desulfurizer absorbs sulfur dioxide in the flue gas and reacts to form calcium sulfite, introduces air to force the oxidation of calcium sulfite to form gypsum, and separates the gypsum from the saturated absorption liquid;

The slurry in the absorption tower is pumped by the slurry circulation pump to the spray layer for repeated recycling. The function of the pit in the absorption tower area is to store the overflowed liquid from the absorption tower, and then pump it through the automatic interlocking device to circulate the limestone slurry. use. Add adipic acid at this position. After adipic acid is stirred into liquid by the agitator in the pit, it is pumped back to the absorption tower (the ratio of solute to limestone in the tower is 0.2-0.3:100 by weight), and Through the uninterrupted operation of the slurry circulation pump, it enters the spray layer and sprays mist liquid from the nozzle to contact and react with the flue gas.

Dosing method: The dosing of adipic acid is automatically controlled by pit pump interlocking, and the flow rate of the pit pump is 45m ³ /h. It takes 4 to 5 hours for all the adipic acid to be added for the first time.

Supplementary method: After the first dosage, the daily loss of adipic acid needs to be supplemented. The replenishment of adipic acid also adopts the method of adding to the pit of the absorption tower, adding 100 kg of adipic acid at the same time every day, and the adding time takes 3 to 4 hours.

The above-mentioned limestone has a purity of more than 90%, and its particle size distribution is 90% passing through a 250-mesh sieve; the adipic acid has a purity of more than 99.7%, and is a white powder.

The direct effect of the present invention is to improve the desulfurization efficiency of the system under different working conditions, realize higher desulfurization efficiency at lower pH, buffer the change of slurry pH, and reduce the liquid-gas ratio of the system. Improve the utilization rate of limestone.

A. Under different working conditions, the influence of adipic acid on the desulfurization efficiency is shown in the following tables.

Based on the above tables, it can be seen that under different raw flue gas conditions and the combination of slurry circulating pumps, the desulfurization efficiency can be increased by 2% to 5% by adding adipic acid, especially when the unit load is high and the raw flue gas When the mass concentration of SO ₂ reaches about 3600mg/Nm ³ , the desulfurization efficiency can be maintained at about 95%, which is very important for the system desulfurization efficiency and net flue gas SO ₂ emission to meet the standard when the coal has a high sulfur content and the original flue gas exceeds the design value. Guarantee is provided, which has very good practical significance.

B. Changes of gypsum quality and limestone utilization rate after adding adipic acid

Analysis and comparison table of main components of gypsum before and after adding adipic acid

It can be seen from the above table that after adding adipic acid, the purity of gypsum rose from 91.46% to 95.34%, an increase of 3.88%. The mass fractions of CaCO ₃ and CaSO ₃ ·1/2H ₂ O in gypsum decreased to varying degrees. The comprehensive analysis of each component shows that the quality of gypsum has been greatly improved. After calculation, before and after adding adipic acid, the calcium-sulfur ratio of the system increased from 1.034 to 1.002, and the calcium-sulfur ratio increased by 3%. This shows that after adding adipic acid, the utilization rate of limestone increased by 3%.

C. Under different working conditions, the optimization results of the slurry circulation pump in the desulfurization system after adding adipic acid

After adding adipic acid, the desulfurization efficiency of the system is improved, and the combination of the slurry circulation pump is optimized under the premise of maintaining a certain desulfurization efficiency and net flue gas SO ₂ emissions, and the energy-saving operation of the desulfurization system is realized. Before and after adding adipic acid, the comparison of the combination of slurry circulating pumps in Kangping Power Plant under different working conditions and the change of system liquid-gas ratio before and after optimization are shown in the following tables.

Combination of slurry circulating pumps and changes in liquid-gas ratio in Kangping Power Plant before and after adding adipic acid

It can be seen from the above table that after adding adipic acid, the combination of slurry circulation pumps under different working conditions has changed. Under the same working conditions, under the premise of satisfying the desulfurization efficiency, the liquid-gas ratio of the system can be reduced by adopting a smaller slurry circulation pump or stopping one pump, which can greatly save the power consumption of the system operation. When the system is at higher load and lower load, the liquid-gas ratio can be saved by 30% and 50% respectively. When the load of the unit is (350-450) MW, the liquid-gas ratio of the system does not change before and after adding adipic acid.

After adding adipic acid, the optimization results of the slurry circulation pump combination in Kangping Power Plant are shown in the table below.

Optimization results of slurry circulation pump combination mode in Kangping Power Plant after adding adipic acid

It can be seen from the above table that when the load of the unit is greater than 450MW and the concentration of SO ₂ in the original flue gas is (3400-3600) mg/Nm ³ , the slurry circulation pump after adding adipic acid can be operated simultaneously by the three pumps before adding adipic acid. Running, change to #1, #3 pump running, saving 852kWh of electricity per hour, the energy saving effect is obvious.

When the load of the unit is greater than 340MW-450MW and the concentration of SO ₂ in the original flue gas is (3000-3400) mg/ ^Nm3 , the slurry circulation pump after adding adipic acid can be operated by any two pumps before adding adipic acid, and the change In order to uniformly adopt the operation of #1 and #2 pumps, that is, two small pumps operate, saving 62kWh~166kWh of electricity per hour.

D. Other beneficial effects on the operation of the desulfurization system

After adding adipic acid, not only can the desulfurization efficiency reach the standard when the coal type changes, causing the flue gas parameters at the inlet of the desulfurization system to exceed the design value, but also to ensure that the SO ₂ concentration of the net flue gas reaches the standard discharge. On the premise of ensuring a certain desulfurization efficiency and outlet _SO2 concentration, the combination mode of the slurry circulation pump can be optimized to greatly reduce the operating cost of the system.

It can be seen from the observation of the operation situation and on-site understanding that by optimizing the combination of the slurry circulation pump, the flexibility of the system operation is improved, the repeated start and stop of the pump is avoided, and the loss of the impeller is reduced; at the same time, the quality of the gypsum is improved after adding adipic acid , to promote the formation of calcium sulfate dihydrate, which can effectively prevent the system from clogging and scaling; after adding adipic acid, the pH value is buffered, which has a good buffering effect on the boiler load, and the desulfurization efficiency will not fluctuate greatly, avoiding short-term At the same time, it can also avoid the reduction of direct economic benefits caused by the power plant’s fear of SO ₂ exceeding the standard and the reduction of the point load.

After the application of the invention, the desulfurization efficiency of the wet desulfurization system of Kangping Power Plant is obviously improved, and the stability of system operation is increased. And under the premise of ensuring the desulfurization efficiency of the power plant and the SO ₂ concentration of the net flue gas up to the standard discharge and the total amount of SO ₂ control, the optimal combination of slurry circulation pumps under different working conditions has been found, which greatly reduces the power consumption of the desulfurization system, Liquid-to-gas ratio and plant power consumption rate.

After the application of the invention, there are detailed data showing that under different working conditions, the desulfurization efficiency of the system is increased by 3% to 5%, the liquid-gas ratio is reduced by more than 30%, and the utilization rate of limestone can be increased by 5% to 10%. During energy-saving operation, based on the annual operation of the desulfurization system for 6,000 hours, by optimizing the combination of slurry circulation pumps, the annual power consumption of the desulfurization system can be reduced by about 6 million to 10 million kWh. Calculated at 0.3 yuan/kWh, the removal of di After the acid investment cost, our factory can save about 1.5 million to 2.4 million electricity bills every year, which has good economic benefits. The specific basis is as follows:

After adding adipic acid, the combination of slurry circulating pumps under different working conditions is optimized, which saves the operating cost of the desulfurization system, and the operating costs are not the same according to different working conditions. The economic benefit analysis mainly considers the following two situations: 1. The load of the unit fluctuates uniformly throughout the year, and the time distribution of each load period is the same; 2. The unit is under heavy load throughout the year, and the concentration of SO ₂ in the original flue gas is high.

The first case of economic benefit analysis: the annual operating hours of the desulfurization system are calculated as 6000h, of which (450-600) MW, (400-450) MW, (340-400) MW, and 340MW and below load conditions are respectively calculated as 1500h. See the table below for the economic benefit analysis.

Comparison table of economic benefits before and after optimization of desulfurization system operating parameters

Note: In the calculation of the relative cost of SO ₂ removal per unit mass, the power consumption of the desulfurization system is only calculated according to the power consumption of the slurry circulation pump, and the influence of power consumption of other equipment in the desulfurization system is not considered.

It can be seen from the above table that when the unit distributes the running time according to different loads throughout the year, and calculates the desulfurization cost before and after adding adipic acid, after adding adipic acid, the total cost of the desulfurization system can be reduced by 1.079 million yuan throughout the year , among which the reduction in electricity consumption is relatively large, and the annual reduction can be 794,700 yuan. After adding adipic acid, the relative cost of SO ₂ removal per ton was reduced by 33.4 yuan, and the economic effect was remarkable.

Economic benefit analysis The second case: the annual operating hours of the desulfurization system is calculated as 6000h, the unit load is (450-600) MW, and the original flue gas SO ₂ concentration is (3400-3600) mg/Nm ³ . See the table below for the economic benefit analysis.

Comparison table of economic benefits before and after optimization of desulfurization system under heavy load conditions

Note: In the calculation of the relative cost of SO ₂ removal per unit mass, the power consumption of the desulfurization system is only calculated according to the power consumption of the slurry circulation pump, and the influence of power consumption of other equipment in the desulfurization system is not considered.

It can be seen from the above table that when the unit operates under heavy load throughout the year, after adding adipic acid, the relative cost of SO ₂ removal per ton is reduced by 37.78 yuan, and the total cost of the desulfurization system can be reduced by 1.952 million yuan throughout the year The electricity consumption can be reduced by 1.5336 million yuan for the whole year. This is because under the condition of heavy load and the desulfurization efficiency is maintained at 92%, after adding adipic acid, the slurry circulation pump of the desulfurization system can The operation of the three pumps before the acid is changed to #1 and #3, and one pump is operated less, so the electric energy is greatly saved. When the unit is at a high or low load, the energy-saving space is the largest, and after adding adipic acid, the energy-saving effect of the desulfurization system is the most significant.

2) Environmental benefits

After adding adipic acid, the desulfurization efficiency of the system is greatly improved, and the concentration of SO ₂ emission is reduced. A single 600MW unit can reduce SO ₂ emission by at least 900t per year, and the environmental benefits are remarkable.

Claims (6)

1. A thermal power plant wet desulfurizer, which includes: a saturated absorption liquid of limestone and water in a saturated or supersaturated state, characterized in that: adipic acid is added in the saturated absorption liquid, and adipic acid is added in the saturated absorption liquid. The solute weight and number ratio of adipic acid to limestone is 0.2-0.3:100. 2. The thermal power plant wet desulfurizer according to claim 1, characterized in that: the limestone has a purity of more than 90%, and its particle size distribution is 90% passing through a 250-mesh sieve; the adipic acid has a purity of more than 99.7% and is white powder. 3. The thermal power plant wet desulfurizer according to claim 1, characterized in that: the temperature range of the saturated absorption liquid is 50-65°C. 4. A desulfurization method of a thermal power plant wet desulfurizer, which includes a desulfurization absorption tower, which is successively provided with: limestone in saturated state or supersaturated state and saturated absorption liquid of water, absorbing The saturated absorption liquid overflow pipe and liquid replenishment pipe on the side wall of the tower, the flue gas inlet, the saturated absorption liquid spray area, the mist eliminator and the flue gas outlet after desulfurization are characterized in that adipic acid is added to the saturated absorption liquid , the solute weight ratio of adipic acid and limestone in the saturated absorption liquid is 0.2-0.3:100, and becomes a desulfurization agent; After the flue gas inlet enters the desulfurization absorption tower, the sulfur dioxide-containing flue gas is countercurrently washed, and after the sulfur dioxide is absorbed, the flue gas is discharged through the demister and the flue gas outlet at the top of the desulfurization absorption tower, and then discharged into the atmosphere through the chimney; The desulfurizer absorbs sulfur dioxide in the flue gas and reacts to form calcium sulfite, introduces air to force the oxidation of calcium sulfite to form gypsum, and separates the gypsum from the saturated absorption liquid; The temperature range of the saturated absorption liquid is 50-65°C. 5. The desulfurization method of wet desulfurization agent in thermal power plant according to claim 4, characterized in that: the saturated absorption liquid overflow pipe and liquid replenishment pipe all lead into a desulfurization absorption tower pit circulation pool with agitator, The addition or addition of adipic acid is added to the saturated absorption liquid of limestone and water in a saturated state or a supersaturated state through the pit circulation pool of the absorption tower. 6. The desulfurization method of thermal power plant wet desulfurization agent according to claim 4, characterized in that: the limestone has a purity of more than 90%, and the particle size distribution is 90% through a 250 mesh sieve; the purity of adipic acid is more than 99.7%, white powder .

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