CN108479332A - A kind of low-temperature flue gas desulphurization denitration disappears white system - Google Patents

Abstract

A kind of low-temperature flue gas desulphurization denitration disappears white system, it is related to wet desulphurization, flue gas disappears white system after denitration, including wet desulfuration tower, gas-gas heat exchanger, Benitration reactor, chimney, wet flue gas after wet desulphurization enters gas-gas heat exchanger after mixing preheating with hot gas, enter denitration reaction removing nitrogen oxides after mixing heating after heated with hot gas again, flue gas after denitration is discharged after gas-gas heat exchanger cools down through chimney, on the one hand vapor is solved, influence of the dust to out of stock catalyst, still further aspect, in the case of same denitration reaction temperature, dehumidified the technique of last denitration again using first desulfurization, significantly reduce out of stock flue gas heating thermic load, effectively reduce plant investment and operating cost.

Description

A low-temperature flue gas desulfurization, denitrification and whitening system

technical field

The invention relates to the application field of low-temperature flue gas desulfurization, denitration and whitening elimination, in particular to a flue gas wet desulfurization, denitrification and whitening elimination system.

Background technique

Existing electric power, steel, petrochemical, biochemical and other industries generally require desulfurization, denitrification and other treatments before they can meet the discharge standards. Different, the high-temperature denitrification + low-temperature desulfurization process commonly used in the power industry is no longer applicable, and wet desulfurization is currently the most effective and dominant desulfurization process. Under the premise of comprehensive treatment, to meet the requirements of desulfurization, denitrification, whitening and so on.

Due to the low temperature of flue gas in petrochemical, steel, biochemical and other industries, the existing high-temperature denitrification process is no longer applicable, and low-temperature denitrification is required, and the low-temperature denitrification process has great impact on dust, flue gas moisture content, comprehensive utilization of waste heat, and whitening These issues are particularly prominent and need to be resolved as soon as possible.

In the existing technology, the technical route of denitrification first and then desulfurization is basically followed. On the one hand, the dust content and moisture content in the flue gas in the denitrification operation are high, which affects the use of denitrification catalysts. On the other hand, the flue gas after desulfurization is whitened The treatment requires a large amount of heat energy, the device is complex and the energy consumption is high, which is uneconomical.

Contents of the invention

Starting from the overall process of desulfurization and denitration, combined with key heat exchange equipment, the present invention firstly desulfurizes and then denitrates, first cools and dehumidifies the flue gas, and then raises the temperature to eliminate whiteness, which meets the requirements of desulfurization and denitrification, and at the same time reduces the system cost. Energy consumption is reduced, and the problem of white plume of flue gas is solved.

In summary, the present invention has the following innovations:

1) The flue gas is desulfurized first and then denitrified. The water vapor content, dust content and SOx content in the flue gas of the denitrification operation are greatly reduced, which reduces the failure risk of the denitrification reaction catalyst and is beneficial to prolong the service life of the denitrification catalyst. It has almost no effect on desulfurization influences;

2) Directly use the heat medium to mix with the desulfurized flue gas from the gas-gas heat exchanger, and use hot air to supplement the heat of the flue gas entering the denitrification reactor to meet the temperature requirements of the denitrification reaction, which can not only save the flue gas heater Equipment, and during the start-up process of the device, it can greatly improve the start-up process of the device, ensure that the denitrification is put into operation in a short time, and reduce the energy consumption of start-up and the emission of non-standard flue gas;

3) Cool the desulfurization slurry through the slurry cooler to improve the desulfurization efficiency, and reduce the moisture content in the desulfurized flue gas at the same time, or dehumidify the desulfurized flue gas through the flue gas condenser, which is beneficial to prolong the service life of the catalyst;

4) Compared with the denitrification first and then desulfurization process, under the same denitrification reaction temperature, the present invention greatly reduces the heat load of flue gas heating on the basis of reducing the moisture content of flue gas.

5) Use the gas-gas heat exchanger to recover the waste heat of the denitration reactor, use the waste heat of the flue gas after denitration to heat the flue gas entering the denitration reactor, and reduce the energy consumption of the system to the greatest extent;

6) The flue gas can be discharged directly after denitrification by the gas-gas heat exchanger, and the problem of white plume can be solved without reheating;

7) A flue gas preheater is installed before the gas-gas heat exchanger to heat the flue gas after desulfurization, increase the temperature of the flue gas, reduce corrosion of downstream equipment, and further reduce costs.

The present invention is achieved through the following technical solutions:

A low-temperature flue gas desulfurization, denitration and whitening system, characterized in that it includes a wet desulfurization tower, a gas-gas heat exchanger, a denitration reactor and a chimney, wherein,

The flue gas outlet of the wet desulfurization tower of the wet desulfurization tower is connected with the cold medium channel inlet of the gas-gas heat exchanger, and the cold medium channel outlet of the gas-gas heat exchanger is connected with the flue gas inlet of the denitrification reactor, and the denitrification reactor The flue gas outlet of the gas-gas heat exchanger communicates with the heat medium channel inlet of the gas-gas heat exchanger, and the heat medium channel outlet of the gas-gas heat exchanger communicates with the chimney;

The flue gas is supplemented with heat at the front end of the inlet of the cold medium channel of the air-gas heat exchanger and at the rear end of the outlet of the cold medium channel of the air-gas heat exchanger to increase the temperature.

The pipeline between the flue gas outlet of the wet desulfurization tower and the cold medium inlet of the gas-gas heat exchanger is mixed with heat medium and between the cold medium channel outlet of the gas-gas heat exchanger and the flue gas inlet of the denitrification reactor. The heat medium is mixed into the pipeline between them, so that the temperature of the flue gas is increased.

The heat medium is high temperature gas.

A flue gas heater is provided between the flue gas outlet of the wet desulfurization tower and the cold medium inlet of the gas-gas heat exchanger, and between the cold medium channel outlet of the gas-gas heat exchanger and the flue gas inlet of the denitrification reactor A flue gas heater is provided, the cold medium channel of the flue gas heater passes through the flue gas, and the hot medium channel of the flue gas heater passes through the heating medium.

A flue gas condenser is provided between the wet desulfurization tower flue gas outlet of the wet desulfurization tower and the cold medium channel inlet of the gas-gas heat exchanger near the wet desulfurization tower flue gas outlet.

The wet desulfurization tower includes a tower body and a desulfurization slurry tank arranged at the bottom of the tower body. The desulfurization slurry tank is provided with a slurry pipeline for slurry circulation, and the slurry pipeline is provided with a slurry cooler.

The slurry heat exchanger is a plate heat exchanger.

A wet dust collector close to the flue gas outlet of the wet desulfurization tower is arranged between the flue gas outlet of the wet desulfurization tower and the cold medium inlet of the gas-gas heat exchanger.

The beneficial effects of the present invention are:

For flue gas using wet desulfurization process, especially for low temperature sintering flue gas, kiln flue gas, etc., through the process route of wet desulfurization tower first and then denitrification, on the one hand, it solves the problem of water vapor and dust on the destocking catalyst. On the other hand, under the same denitrification reaction temperature, the process of desulfurization first, then dehumidification and final denitrification can greatly reduce the heating load of the off-stock flue gas, effectively reduce the investment of the device, and at the same time, the off-stock flue gas After the gas heat exchanger, it can be directly discharged through the chimney without the problem of white plume. Compared with the process of first denitrification and then desulfurization, the setting of flue gas heating heat exchanger is reduced, the device investment is saved and the system is simpler, and the transformation cost is low and It is simple and easy to operate, and at the same time, compared with the system with a flue gas heater downstream of the gas-gas heat exchanger, the system is simpler, the start-up process is faster, and the energy consumption is lower.

Description of drawings

Fig. 1 is a schematic diagram of the system of the present invention.

Fig. 2-Fig. 5 are other implementation connection schematic diagrams of the present invention.

In the figure: 1. Wet desulfurization tower, 101. Flue gas inlet of wet desulfurization tower, 102. Flue gas outlet of wet desulfurization tower, 103. Slurry inlet, 104. Slurry pipeline, 105. Slurry outlet, 106. Slurry pump, 2. Air-gas heat exchanger, 201. Cold medium channel inlet of air-gas heat exchanger, 202. Cold medium channel outlet of air-gas heat exchanger, 203. Hot medium channel inlet of air-gas heat exchanger, 204. Gas Heat medium channel outlet of gas heat exchanger, 3. flue gas heater, 4. denitrification reactor, 401. flue gas inlet of denitrification reactor, 402. flue gas outlet of denitrification reactor, 5. chimney, 6. slurry Cooler, 7. Flue gas condenser, 8. Second flue gas heater.

A. Flue gas before desulfurization, B. Flue gas after desulfurization, C. Flue gas after desulfurization, D. First heat medium, E. Desulfurization slurry, F. Cold medium, G. Cold medium, J. Second heat medium, H. Condensate.

Detailed ways

In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and preferred embodiments.

As shown in Figure 1, the present invention includes a wet desulfurization tower 1, a gas-gas heat exchanger 2, a denitrification reactor 4 and a chimney 5;

The wet desulfurization tower flue gas outlet 101 of the wet desulfurization tower communicates with the cold medium channel inlet 201 of the gas-gas heat exchanger, and the cold medium channel outlet 202 of the gas-gas heat exchanger communicates with the flue gas inlet 401 of the denitrification reactor , the flue gas outlet 402 of the denitrification reactor communicates with the heat medium channel inlet 203 of the gas-gas heat exchanger, and the heat medium channel outlet 204 of the gas-gas heat exchanger communicates with the chimney;

The flue gas is supplemented with heat at the front end of the inlet of the cold medium channel of the air-gas heat exchanger and at the rear end of the outlet of the cold medium channel of the air-gas heat exchanger to increase the temperature.

The heat supplement process for flue gas can be set at the front and rear ends of the cold medium channel of the gas-gas heat exchanger; specifically, it can be installed in the pipeline between the flue gas outlet of the wet desulfurization tower and the cold medium inlet of the gas-gas heat exchanger The heat medium is mixed in and the heat medium is mixed into the pipeline between the cold medium channel outlet of the gas-gas heat exchanger and the flue gas inlet of the denitration reactor, so that the temperature of the flue gas is increased. Preferably, the heat medium is high-temperature gas.

Before desulfurization, the flue gas A enters the wet desulfurization tower through the flue gas inlet 101 of the wet desulfurization tower, and is cooled, dehumidified, dust-removed and desulfurized under the action of the slurry. The cold medium channel of the gas heat exchanger, the temperature of the flue gas flowing out of the gas-gas heat exchanger from the cold medium channel is raised after being heated, and then enters the denitrification reactor, and the flue gas C is discharged and enters the gas-gas heat exchanger. The heat medium channel enters the chimney through the flue after being cooled, and is discharged into the atmosphere. The flue gas after desulfurization exchanges heat with the flue gas after denitrification in the gas-gas heat exchanger, which raises the temperature of the flue gas after desulfurization and cools down the flue gas after denitrification. During this process, the flue gas has undergone wet desulfurization, heating, heating, denitrification, cooling and other processes to achieve ultra-clean emissions without white smoke.

Supplementary heat is used to raise the temperature of flue gas by entering the front end of the denitrification reactor by directly mixing the first heat medium, and by directly mixing the second heat medium J at the back end of the denitrification reactor.

To heat up the flue gas, the first flue gas heater 3 is installed at the front end of the denitrification reactor, the first heat medium is passed into the flue gas heater to supplement the heat of the flue gas, and the second flue gas heater is installed at the rear end of the denitrification reactor. Gas heater 8, the second heat medium passes into the flue gas heater to supplement the heat of the flue gas;

As shown in Figure 3, in conjunction with Figure 1, a second flue gas heater 8 is provided on the flue between the flue gas outlet of the wet desulfurization tower and the desulfurized flue gas inlet of the gas-gas heat exchanger, close to the gas-gas heat exchanger, The flue gas after desulfurization is preheated by the heat medium J to increase the superheat of the water vapor in the flue gas, reduce the corrosion of downstream equipment and the thermal load of the flue gas heater, and improve the reliability of the device.

In this example, the first heat medium and the second heat medium can be used separately in the system; the first flue gas heater and the second flue gas heater can also be used separately in the system;

Preferably, the air-gas heat exchanger in this example is a partitioned wall heat exchanger, and its structure is a tube heat exchanger or a plate heat exchanger.

As shown in Figure 2, combined with Figure 1, the flue gas duct between the wet desulfurization tower flue gas outlet of the wet desulfurization tower and the cold medium channel inlet of the gas-gas heat exchanger is provided with flue gas near the wet desulfurization tower flue gas outlet The condenser 7 condenses and dehumidifies the desulfurized flue gas through a cold medium, reduces the dust content and moisture content of the desulfurized flue gas, and further reduces the heat load of the flue gas heater, which can effectively reduce device investment and operating costs. The flue gas condenser condenses the moisture in the flue gas and discharges the condensate H.

As shown in Figure 4, combined with Figures 2 and 3, the flue gas condenser and the flue gas preheater are jointly installed in the system and cooperate with each other to preheat the desulfurized flue gas after condensation and dehumidification.

In addition, a wet dust collector close to the flue gas outlet of the wet desulfurization tower is installed between the flue gas outlet of the wet desulfurization tower and the cold medium inlet of the gas-gas heat exchanger to dehumidify and remove dust from the flue gas.

As shown in Figure 5, in conjunction with Figure 1, the wet desulfurization tower includes a tower body and a desulfurization slurry tank located at the bottom of the tower body, the desulfurization slurry tank is provided with a slurry pipeline 104 for slurry circulation, and the slurry pipeline is provided with a slurry cooler6. The desulfurization slurry E is cooled by the cooling medium E, thereby improving the desulfurization efficiency, reducing the dust content and moisture content of the flue gas after desulfurization, and further reducing the heat load of the flue gas heater, which can effectively reduce the device investment and operating costs.

The slurry pipeline is connected between the slurry inlet 103 and the slurry outlet 105 of the desulfurization slurry tank, and a slurry pump 106 is arranged on the slurry pipeline to drive the slurry to circulate and cool down through the slurry pipeline.

The above is only a preferred embodiment of the present invention, and it should be pointed out that for those of ordinary skill in the art, some improvements and modifications can be made without departing from the principle of the present invention. It should be regarded as the protection scope of the present invention.

Claims (8)

1. The white system 1. a kind of low-temperature flue gas desulphurization denitration disappears, which is characterized in that including wet desulfuration tower, gas-gas heat exchanger, denitration Reactor and chimney, wherein

   The wet desulfuration tower exhanst gas outlet of the wet desulfuration tower is connected to the cold medium feeder connection of gas-gas heat exchanger, and gas gas changes The cold medium channel outlet of hot device is connected to the smoke inlet of Benitration reactor, the exhanst gas outlet and gas-gas heat exchange of Benitration reactor The hot media channel entrance of device is connected to, and the hot media channel outlet of gas-gas heat exchanger is connected to chimney；

   Cold medium channel outlet rear end of the flue gas in the cold medium feeder connection front end of the gas-gas heat exchanger and gas-gas heat exchanger By concurrent heating so that temperature is promoted.
2. 2. a kind of low-temperature flue gas desulphurization denitration disappears white system according to claim 1, which is characterized in that the wet desulfuration tower Cold Jie of thermal medium and the gas-gas heat exchanger is mixed into pipeline between exhanst gas outlet and the cold medium entrance of gas-gas heat exchanger It is mixed into thermal medium in pipeline between matter channel outlet and the smoke inlet of Benitration reactor so that flue-gas temperature is elevated.
3. 3. a kind of low-temperature flue gas desulphurization denitration disappears white system according to claim 2, which is characterized in that the thermal medium is high Wet body.
4. 4. a kind of low-temperature flue gas desulphurization denitration disappears white system according to claim 1, which is characterized in that the wet desulfuration tower The cold medium that flue gas heater and the gas-gas heat exchanger are equipped between exhanst gas outlet and the cold medium entrance of gas-gas heat exchanger is logical Road is exported is equipped with flue gas heater between the smoke inlet of Benitration reactor, and the cold medium channel of flue gas heater passes through cigarette The hot media channel of gas, flue gas heater passes through heat medium.
5. The white system 5. a kind of low-temperature flue gas desulphurization denitration according to any one of claim 1-4 disappears, which is characterized in that institute It states between the wet desulfuration tower exhanst gas outlet of wet desulfuration tower and the cold medium feeder connection of gas-gas heat exchanger close to wet desulphurization Tower flue gas outlet is equipped with flue gas condenser.
6. The white system 6. a kind of low-temperature flue gas desulphurization denitration according to claim 1,2,3, any one of 4 disappears, feature exist In the wet desulfuration tower includes tower body and the desulfurization slurry pond set on tower body bottom, and the desulfurization slurry pond is equipped with for starching The slurry line of liquid cycle, the slurry line are equipped with slurries cooler.
7. 7. being disappeared white system according to a kind of low-temperature flue gas desulphurization denitration described in claim 6, which is characterized in that its feature exists In the slurry heat exchanger is heat-exchangers of the plate type.
8. The white system 8. a kind of low-temperature flue gas desulphurization denitration according to any one of claim 1,2,3,4 or 7 disappears, feature It is, is equipped with close to wet desulphurization tower flue gas between the wet desulfuration tower exhanst gas outlet and the cold medium entrance of gas-gas heat exchanger The wet scrubber of outlet.