阅读说明：本技术 一种氨法-scr联合脱硫脱硝装置及方法 (Ammonia process-SCR combined desulfurization and denitrification device and method ) 是由 潘日喜 于 2020-05-12 设计创作，主要内容包括：本发明公开了一种氨法-SCR联合脱硫脱硝装置及方法,通过对所述净化塔内部结构以及所述第一换热器和所述第二换热器与所述净化塔连接关系的改进,并配合所述混合室、所述温度检测器和所述加热器,使得所述氨法-SCR联合脱硫脱硝装置的脱硫脱硝效果更好,效率更快,从而提升了净化效果。(The invention discloses an ammonia process-SCR combined desulfurization and denitrification device and method, which have the advantages that the desulfurization and denitrification effect of the ammonia process-SCR combined desulfurization and denitrification device is better and the efficiency is higher by improving the internal structure of a purification tower, the connection relation between a first heat exchanger and a second heat exchanger and the purification tower and matching with a mixing chamber, a temperature detector and a heater, so that the purification effect is improved.)

1. An ammonia process-SCR combined desulfurization and denitrification device is characterized in that,

the device comprises a purification tower, a first partition plate, a second partition plate, an alkali liquor spray pipe, a dust remover, a first induced draft fan, a first heat exchanger, a second induced draft fan, a mixing chamber, a temperature detector, a heater, an ammonia spraying spray pipe, a second heat exchanger and an ammonia pump;

the second partition board is provided with air holes, the first partition board and the second partition board are respectively fixedly connected with the purification tower and divide the purification tower into a desulfurization chamber, a denitrification chamber and a spraying ammonia absorption chamber, the desulfurization chamber is internally provided with the alkali liquor spraying pipe, the spraying ammonia absorption chamber is internally provided with an ammonia absorption spraying pipe, the spraying ammonia absorption chamber is provided with an exhaust chimney, a heat medium inlet of the first heat exchanger is connected with a flue gas outlet pipeline of the coke oven through a dust remover, a heat medium outlet of the first heat exchanger is connected with a pipeline of the desulfurization chamber, an air outlet of the first induced draft fan is connected with a refrigerant inlet pipeline of the first heat exchanger, a refrigerant outlet of the first heat exchanger is respectively connected with an air outlet of the second induced draft fan and an air inlet pipeline of the mixing chamber, and an air inlet of the second induced draft fan is communicated with the desulfurization chamber, the air outlet of the mixing chamber is communicated with the denitration chamber, the temperature detector and the heater are arranged in the mixing chamber, the ammonia spraying spray pipe is arranged inside the denitration chamber and is connected with a refrigerant outlet pipeline of the second heat exchanger, a heat medium inlet of the second heat exchanger is connected with the denitration chamber pipeline, a refrigerant inlet of the second heat exchanger is connected with the ammonia pump pipeline, and a heat medium outlet of the second heat exchanger is connected with the ammonia spraying and absorbing chamber pipeline.

2. The ammonia process-SCR combined desulfurization and denitrification apparatus according to claim 1,

the ammonia-SCR combined desulfurization and denitrification device further comprises an SCR catalyst plate, wherein the SCR catalyst plate is fixedly connected with the purification tower and is positioned inside the denitrification chamber.

3. The ammonia process-SCR combined desulfurization and denitrification apparatus according to claim 2,

the SCR catalyst plates are arranged in the denitration chamber in a staggered mode, and air permeable gaps are formed between each SCR catalyst plate and the side wall of the purification tower.

4. The ammonia process-SCR combined desulfurization and denitrification apparatus according to claim 3,

the ammonia spraying device comprises a plurality of ammonia spraying spray pipes, wherein the plurality of ammonia spraying spray pipes are arranged below the SCR catalyst plates respectively.

5. The ammonia process-SCR combined desulfurization and denitrification apparatus according to claim 4,

the ammonia-SCR combined desulfurization and denitrification device further comprises a first spray head, and the first spray head is perpendicular to the ammonia spraying spray pipe.

6. The ammonia process-SCR combined desulfurization and denitrification apparatus according to claim 5,

the ammonia-SCR combined desulfurization and denitrification device further comprises a second spray head, the second spray head is fixedly connected with the ammonia spraying spray pipe, an included angle of 30-60 degrees is formed between the axial line of the second spray head and the axial line of the first spray head, the number of the second spray heads is multiple, and the second spray heads are arranged around the first spray head in a circumferential mode.

7. The ammonia process-SCR combined desulfurization and denitrification apparatus according to claim 6,

the ammonia process-SCR combined desulfurization and denitrification device further comprises a wire mesh demister, wherein the wire mesh demister is fixedly connected with the purification tower and is positioned between the spraying ammonia absorption chamber and the exhaust chimney.

8. The ammonia process-SCR combined desulfurization and denitrification apparatus according to claim 7,

the ammonia process-SCR combined desulfurization and denitrification device further comprises a desulfurization filter screen, wherein the desulfurization filter screen is fixedly connected with the purification tower, is positioned in the purification tower and is positioned below the alkali liquor spray pipe.

9. The ammonia process-SCR combined desulfurization and denitrification apparatus according to claim 8,

the ammonia-SCR combined desulfurization and denitrification device further comprises a collecting tank, and the collecting tank is respectively connected with the desulfurization chamber and the denitrification chamber through pipelines.

10. The method for adopting the ammonia process-SCR combined desulfurization and denitrification device as claimed in claim 9, which comprises the following steps:

the first heat exchanger is used for introducing high-temperature flue gas discharged by a coke oven into the desulfurization chamber for desulfurization treatment, then discharging the high-temperature flue gas into the mixing chamber, and simultaneously mixing the heat of the high-temperature flue gas with air by using the first heat exchanger and discharging the mixed gas into the mixing chamber;

the temperature detector detects the temperature of the mixing chamber after the desulfurized flue gas is mixed with the hot air, if the temperature is more than or equal to a preset temperature value, the heater stops acting, if the temperature is less than the preset temperature value, the heater acts until the temperature of the flue gas in the mixing chamber is more than or equal to the preset temperature value, and then the flue gas is discharged into the denitration chamber;

the SCR catalyst plate is matched with ammonia water sprayed by the ammonia spraying spray pipe, denitration treatment is carried out on the smoke in the denitration chamber, then the smoke enters the spraying ammonia absorption chamber, the ammonia absorption spray pipe sprays an ammonia absorbent, and then the smoke is discharged from the exhaust chimney.

Technical Field

The invention relates to the technical field of coke oven flue gas purification, in particular to an ammonia method-SCR combined desulfurization and denitrification device and method.

Background

At present, NOx is one of the main atmospheric pollutants, and is easy to form acid rain and photochemical smog in the atmosphere, so that the ecological environment is influenced and the human health is harmed, and the current situation of NOx emission in the steel industry is particularly severe. According to statistics, the emission of NOx gas in the steel industry accounts for about 10% of the total emission of the industry, and the sintering process is one of the main sources for generating NOx and accounts for about 50% of the total emission of the NOx. The energy consumption of the iron ore sintering process is mainly the consumption of solid fuels such as coke powder, anthracite and other fossil fuels, which accounts for about 75-80% of the total energy consumption of the process, and more than 90% of NOx discharged by the sintering process is converted from nitrogen in the fuels. The new NOx emission standard specified in the "emission Standard for Steel sintering and pellet industry atmospheric pollutants" of 1 month and 1 year in 2015 is implemented in the existing enterprises, and the sintering process is facing huge NOx emission reduction pressure. Most enterprises purify sintering flue gas by utilizing an ammonia method-SCR combined desulfurization and denitrification device, but the existing SCR combined desulfurization and denitrification device has low purification efficiency and poor purification effect.

Disclosure of Invention

The invention aims to provide an ammonia-SCR combined desulfurization and denitrification device and method, and aims to solve the technical problems of low purification efficiency and poor purification effect of an SCR combined desulfurization and denitrification device in the prior art.

In order to achieve the purpose, the ammonia method-SCR combined desulfurization and denitrification device comprises a purification tower, a first partition plate, a second partition plate, an alkali liquor spray pipe, a dust remover, a first induced draft fan, a first heat exchanger, a second induced draft fan, a mixing chamber, a temperature detector, a heater, an ammonia spraying spray pipe, a second heat exchanger and an ammonia pump;

the second partition board is provided with air holes, the first partition board and the second partition board are respectively fixedly connected with the purification tower and divide the purification tower into a desulfurization chamber, a denitrification chamber and a spraying ammonia absorption chamber, the desulfurization chamber is internally provided with the alkali liquor spraying pipe, the spraying ammonia absorption chamber is internally provided with an ammonia absorption spraying pipe, the spraying ammonia absorption chamber is provided with an exhaust chimney, a heat medium inlet of the first heat exchanger is connected with a flue gas outlet pipeline of the coke oven through a dust remover, a heat medium outlet of the first heat exchanger is connected with a pipeline of the desulfurization chamber, an air outlet of the first induced draft fan is connected with a refrigerant inlet pipeline of the first heat exchanger, a refrigerant outlet of the first heat exchanger is respectively connected with an air outlet of the second induced draft fan and an air inlet pipeline of the mixing chamber, and an air inlet of the second induced draft fan is communicated with the desulfurization chamber, the air outlet of the mixing chamber is communicated with the denitration chamber, the temperature detector and the heater are arranged in the mixing chamber, the ammonia spraying spray pipe is arranged inside the denitration chamber and is connected with a refrigerant outlet pipeline of the second heat exchanger, a heat medium inlet of the second heat exchanger is connected with the denitration chamber pipeline, a refrigerant inlet of the second heat exchanger is connected with the ammonia pump pipeline, and a heat medium outlet of the second heat exchanger is connected with the ammonia spraying and absorbing chamber pipeline.

The ammonia-SCR combined desulfurization and denitrification device further comprises an SCR catalyst plate, wherein the SCR catalyst plate is fixedly connected with the purification tower and is positioned inside the denitrification chamber.

The SCR catalyst plates are arranged in the denitration chamber in a staggered mode, and air permeable gaps are formed between each SCR catalyst plate and the side wall of the purification tower.

The number of the ammonia spraying spray pipes is multiple, and the multiple ammonia spraying spray pipes are respectively arranged below each SCR catalyst plate.

The ammonia-SCR combined desulfurization and denitrification device further comprises a first spray head, and the first spray head is perpendicular to the ammonia spraying spray pipe.

The ammonia-SCR combined desulfurization and denitrification device further comprises a plurality of second spray heads, the second spray heads are fixedly connected with the ammonia spraying spray pipes, included angles of 30-60 degrees are formed between the axial lines of the second spray heads and the axial lines of the first spray heads, and the second spray heads are arranged in a plurality of circumferential mode around the first spray heads.

The ammonia-SCR combined desulfurization and denitrification device further comprises a wire mesh demister, wherein the wire mesh demister is fixedly connected with the purification tower and is positioned between the spraying ammonia absorption chamber and the exhaust chimney.

The ammonia process-SCR combined desulfurization and denitrification device further comprises a desulfurization filter screen, wherein the desulfurization filter screen is fixedly connected with the purification tower and is positioned in the purification tower and below the alkali liquor spray pipe.

The ammonia-SCR combined desulfurization and denitrification device further comprises a collecting tank, and the collecting tank is respectively connected with the desulfurization chamber and the denitrification chamber through pipelines.

The invention also provides an ammonia method-SCR combined desulfurization and denitrification method, which comprises the following steps:

the first heat exchanger is used for introducing high-temperature flue gas discharged by a coke oven into the desulfurization chamber for desulfurization treatment, then discharging the high-temperature flue gas into the mixing chamber, and simultaneously mixing the heat of the high-temperature flue gas with air by using the first heat exchanger and discharging the mixed gas into the mixing chamber;

the temperature detector detects the temperature of the mixing chamber after the desulfurized flue gas is mixed with the hot air, if the temperature is more than or equal to a preset temperature value, the heater stops acting, if the temperature is less than the preset temperature value, the heater acts until the temperature of the flue gas in the mixing chamber is more than or equal to the preset temperature value, and then the flue gas is discharged into the denitration chamber;

the SCR catalyst plate is matched with ammonia water sprayed by the ammonia spraying spray pipe, denitration treatment is carried out on the smoke in the denitration chamber, then the smoke enters the spraying ammonia absorption chamber, the ammonia absorption spray pipe sprays an ammonia absorbent, and then the smoke is discharged from the exhaust chimney.

The invention has the beneficial effects that: through the improvement of the connection relation between the purification tower internal structure and the first heat exchanger and the second heat exchanger and the purification tower and the cooperation of the mixing chamber, the temperature detector and the heater, the ammonia-SCR combined desulfurization and denitrification device has better desulfurization and denitrification effects and higher efficiency, thereby improving the purification effect.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic structural diagram of an ammonia process-SCR combined desulfurization and denitrification device.

FIG. 2 is a flow chart of the ammonia process-SCR combined SOx/NOx process of the present invention.

1-a purification tower, 2-a first clapboard, 3-a second clapboard, 4-an alkali liquor spray pipe, 5-a dust remover, 6-a first induced draft fan, 7-a first heat exchanger, 8-a second induced draft fan, 9-a mixing chamber, 10-a temperature detector, 11-a heater, 12-an ammonia spray pipe, 13-a second heat exchanger, 14-an ammonia pump, 15-an air vent, 16-a desulfurization chamber, 17-a denitration chamber, 18-a spray ammonia absorption chamber, 19-an ammonia absorption spray pipe, 20-an exhaust chimney, 21-an SCR catalyst plate, 22-an air vent gap, 23-a first spray head, 24-a second spray head, 25-a silk screen demister, 26-a desulfurization filter screen and 27-a collecting tank.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

In the description of the present invention, it is to be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships illustrated in the drawings, and are used merely for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention. Further, in the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

Referring to fig. 1, the invention provides an ammonia process-SCR combined desulfurization and denitrification device, which comprises a purification tower 1, a first partition plate 2, a second partition plate 3, an alkali liquor spray pipe 4, a dust remover 5, a first induced draft fan 6, a first heat exchanger 7, a second induced draft fan 8, a mixing chamber 9, a temperature detector 10, a heater 11, an ammonia spray pipe 12, a second heat exchanger 13 and an ammonia pump 14;

the second partition board 3 is provided with air holes 15, the first partition board 2 and the second partition board 3 are respectively fixedly connected with the purification tower 1 and divide the purification tower 1 into a desulfurization chamber 16, a denitration chamber 17 and a spraying ammonia absorption chamber 18, the desulfurization chamber 16 is internally provided with the alkali liquor spraying pipe 4, the spraying ammonia absorption chamber 18 is internally provided with an ammonia gas absorption spraying pipe 19, the spraying ammonia absorption chamber 18 is provided with an exhaust chimney 20, a heat medium inlet of the first heat exchanger 7 is connected with a flue gas outlet pipeline of the coke oven through a dust remover 5, a heat medium outlet of the first heat exchanger 7 is connected with the desulfurization chamber 16 through a pipeline, an air outlet of the first induced draft fan 6 is connected with a refrigerant inlet pipeline of the first heat exchanger 7, a refrigerant outlet of the first heat exchanger 7 is respectively connected with an air outlet of the second induced draft fan 8 and an air inlet pipeline of the mixing chamber 9, the air inlet of the second induced draft fan 8 is communicated with the desulfurization chamber 16, the air outlet of the mixing chamber 9 is communicated with the denitration chamber 17, the temperature detector 10 and the heater 11 are arranged in the mixing chamber 9, the ammonia spraying spray pipe 12 is arranged inside the denitration chamber 17, the ammonia spraying spray pipe 12 is connected with the refrigerant outlet pipeline of the second heat exchanger 13, the heat medium inlet of the second heat exchanger 13 is connected with the denitration chamber 17 through a pipeline, the refrigerant inlet of the second heat exchanger 13 is connected with the ammonia pump 14 through a pipeline, and the heat medium outlet of the second heat exchanger 13 is connected with the ammonia spraying chamber 18 through a pipeline.

In the present embodiment, the ammonia-SCR combined desulfurization and denitrification apparatus adopts a mode of desulfurization before denitrification, firstly, high-temperature flue gas discharged from a coke oven of a coke plant is dedusted by the deduster 5, enters the heat medium inlet of the first heat exchanger 7, flows out from the refrigerant outlet of the first heat exchanger 7 to the mixing chamber 9, air enters the first heat exchanger 7 from the refrigerant inlet thereof through the first induced draft fan 6, flows out to the mixing chamber 9 from the refrigerant inlet of the first heat exchanger 7, heat in the high-temperature flue gas is temporarily stored in the air in the first heat exchanger 7, enters the desulfurization chamber 16 of the purification tower 1 after the temperature of the flue gas after passing through the first heat exchanger 7 is reduced, and is sprayed with a sodium carbonate solution, a calcium hydroxide solution, etc. through the alkali liquor spray pipe 4, so as to perform desulfurization treatment on the flue gas entering the desulfurization chamber 16, after the flue gas is subjected to desulfurization treatment, the desulfurized flue gas quickly enters the mixing chamber 9 under the action of the second induced draft fan 8 and is mixed with the hot air which enters the mixing chamber 9, then the temperature detector 10 detects the temperature condition of the flue gas in the mixing chamber 9, if the temperature is greater than or equal to a preset temperature value, the heater 11 stops acting, if the temperature is less than the preset temperature value, the heater 11 acts until the temperature of the flue gas in the mixing chamber 9 is greater than or equal to the preset temperature value, and then the flue gas is discharged into the denitration chamber 17; wherein through the flue gas after the heat transfer of first heat exchanger 7 after the desulfurization, denitration after mixing with the air of storage heat again, reduced the calorific loss in desulfurization process, promoted flue gas heat utilization ratio, energy saving, simultaneously through thermodetector 10 real-time detection flue gas heat temperature in mixing chamber 9 to cooperate heater 11, guarantee mixing chamber 9 gets into the stability of the flue gas temperature of denitration chamber 17 promotes the device's SOx/NOx control speed and quality to this promotes purifying effect. The flue gas temperature of mixing chamber 9 reaches the standard and gets into after denitration chamber 17, spout ammonia shower 12 and spray the aqueous ammonia, carry out denitration treatment, wherein through will pass through the gas that denitration chamber 17 was handled passes through second heat exchanger 13 with get into the aqueous ammonia before denitration chamber 17 carries out the heat transfer, has practiced thrift the energy that the aqueous ammonia preheats, has reduced the aqueous ammonia and has mixed the decline influence to flue gas temperature in the flue gas, and then has guaranteed more thoroughly to flue gas denitration, has promoted the device's purifying effect. After the flue gas is denitrated, the flue gas enters the spraying ammonia absorption chamber 18 through the air holes 15, the ammonia absorption spraying pipe 19 sprays ammonia absorbent, so that the flue gas is purified, and the flue gas is discharged through the exhaust chimney 20 after the purification treatment is finished, wherein the ammonia absorbent is water, dilute nitric acid or dilute sulfuric acid, so that the purification effect of the ammonia-SCR combined desulfurization and denitrification device on the flue gas is further improved.

Further, the ammonia-SCR combined desulfurization and denitrification device further comprises an SCR catalyst plate 21, wherein the SCR catalyst plate 21 is fixedly connected with the purification tower 1 and is positioned inside the denitrification chamber 17. The number of the SCR catalyst plates 21 is plural, the plural SCR catalyst plates 21 are alternately arranged inside the denitration chamber 17, and an air permeable gap 22 is provided between each SCR catalyst plate 21 and the side wall of the purification tower 1.

In this embodiment, the plurality of SCR catalyst plates 21 are sequentially arranged in the denitration chamber 17 in a staggered manner from top to bottom, so that the plurality of SCR catalyst plates 21 and the inner wall of the purification tower 1 form staggered ventilation gaps 22, thereby improving the flow stroke of the flue gas in the denitration chamber 17, increasing the contact area and time between the sprayed ammonia water and the flue gas, improving the denitration efficiency, and improving the overall purification rate of the device.

Further, the number of the ammonia injection showers 12 is plural, and the plural ammonia injection showers 12 are respectively disposed below each of the SCR catalyst plates 21.

In this embodiment, through every all set up below SCR catalyst plate 21 spout ammonia shower 12, can further increase the area of contact of the aqueous ammonia that sprays and flue gas, improve the denitration effect to the flue gas to promote the device's whole purifying effect.

Further, the ammonia process-SCR combined desulfurization and denitrification device further comprises a first spray head 23, and the first spray head 23 is perpendicular to the ammonia spraying spray pipe 12.

In this embodiment, the setting of first shower nozzle 23 can increase the injection dynamics of the 12 spun aqueous ammonia of ammonia spray pipe for the aqueous ammonia can be better with the contact of mobile flue gas, play better denitration effect, promote the whole purifying effect of the device to the flue gas.

Further, the ammonia process-SCR combined desulfurization and denitrification device further comprises a second spray head 24, the second spray head 24 is fixedly connected with the ammonia spraying spray pipe 12, an included angle of 30-60 degrees is formed between the axial line of the second spray head 24 and the axial line of the first spray head 23, the number of the second spray heads 24 is multiple, and the second spray heads 24 are circumferentially arranged around the first spray head 23.

In this embodiment, through a plurality of second shower nozzle 24 winds first shower nozzle 23 is the circumference setting, can further improve spout the injection dynamics and the spray regime of ammonia shower 12 spun aqueous ammonia, the area of contact of increase aqueous ammonia and flue gas plays better denitration effect, promotes the whole purifying effect of the device to the flue gas.

Further, the ammonia process-SCR combined desulfurization and denitrification device further comprises a wire mesh demister 25, wherein the wire mesh demister 25 is fixedly connected with the purification tower 1 and is positioned between the spray ammonia absorption chamber 18 and the exhaust chimney 20.

In the present embodiment, the wire mesh demister 25 is mainly composed of a wire mesh, a wire mesh grid, a wire mesh block, and a supporting device for fixing the wire mesh block, the wire mesh is a gas-liquid filter screen made of various materials, and the gas-liquid filter screen is made of metal wires or nonmetal wires. The non-metallic wire of the gas-liquid filter screen is formed by twisting a plurality of strands of non-metallic fibers and can also be a single-stranded non-metallic wire. This silk screen demister 25 not only can filter suspend in the great liquid foam in the air current, can filter moreover less and little liquid foam, the process the flue gas that sprays ammonia absorption room 18 can pass through the silk pad on the silk screen demister 25 is detached the entrainment and is had a fog foam, further promotes the purifying effect to the flue gas.

Further, the ammonia process-SCR combined desulfurization and denitrification device further comprises a desulfurization filter screen 26, wherein the desulfurization filter screen 26 is fixedly connected with the purification tower 1, is positioned in the purification tower 1, and is positioned below the alkali liquor spraying pipe 4.

In this embodiment, the desulfurization filter screen 26 adopts a c-276 hastelloy wire mesh, and is matched with the alkali liquor spray pipe 4, so that the flue gas can be desulfurized more quickly and better, and the purification effect and the purification rate of the flue gas are indirectly improved.

Further, the ammonia-SCR combined desulfurization and denitrification device further comprises a collecting tank 27, and the collecting tank 27 is respectively connected with the desulfurization chamber 16 and the denitrification chamber 17 through pipelines.

In this embodiment, after the flue gas is sprayed by the alkali liquor spraying pipe 4 for desulfurization, the wastewater is accumulated at the bottom of the purification tower 1, and after the flue gas is sprayed by the ammonia spraying pipe 12, the wastewater is accumulated at the first partition plate 2, and the collection pool 27 is respectively connected with the desulfurization chamber 16 and the denitration chamber 17 through pipelines, so as to collect the wastewater.

Referring to fig. 2, the present invention also provides an ammonia process-SCR combined desulfurization and denitrification method, which includes the following steps:

s100: the first heat exchanger 7 is used for introducing high-temperature flue gas exhausted by a coke oven into the desulfurization chamber 16 for desulfurization treatment, then the high-temperature flue gas is exhausted into the mixing chamber 9, and meanwhile, the heat of the high-temperature flue gas is mixed with air by the first heat exchanger 7 and exhausted into the mixing chamber 9;

s200: the temperature detector 10 detects the temperature of the mixing chamber 9 after the desulfurized flue gas is mixed with the hot air, if the temperature is greater than or equal to a preset temperature value, the heater 11 stops acting, if the temperature is less than the preset temperature value, the heater 11 acts until the temperature of the flue gas in the mixing chamber 9 is greater than or equal to the preset temperature value, and then the flue gas is discharged into the denitration chamber 17;

s300: the SCR catalyst plate 21 is matched with ammonia water sprayed by the ammonia spraying spray pipe 12, denitration treatment is carried out on the flue gas in the denitration chamber 17, then the flue gas enters the spraying ammonia absorption chamber 18, the ammonia absorption spray pipe 19 sprays ammonia absorbent, and then the flue gas is discharged from the exhaust chimney 20.

Wherein, firstly, the high temperature flue gas discharged from coke oven of coke plant is dedusted by the deduster 5, enters the heat medium inlet of the first heat exchanger 7, flows out from the refrigerant outlet of the first heat exchanger 7 to the mixing chamber 9, the air enters from the refrigerant inlet of the first heat exchanger 7 through the first induced draft fan 6, flows out from the refrigerant inlet of the first heat exchanger 7 to the mixing chamber 9, the heat in the high temperature flue gas is temporarily stored in the air in the first heat exchanger 7, the temperature of the flue gas after passing through the first heat exchanger 7 is reduced, then the flue gas enters the desulfurizing chamber 16 of the purifying tower 1, sodium carbonate solution, calcium hydroxide solution and the like are sprayed through the alkali liquor spraying pipe 4, thereby the flue gas entering the desulfurizing chamber 16 is desulfurized, after the flue gas is desulfurized, under the action of the second induced draft fan 8, the desulfurized flue gas rapidly enters the mixing chamber 9 and is mixed with the hot air which enters the mixing chamber 9, then the temperature detector 10 detects the temperature condition of the flue gas in the mixing chamber 9, if the temperature is greater than or equal to a preset temperature value, the heater 11 stops acting, if the temperature is less than the preset temperature value, the heater 11 acts until the temperature of the flue gas in the mixing chamber 9 is greater than or equal to the preset temperature value, and then the flue gas is discharged into the denitration chamber 17; the flue gas temperature of mixing chamber 9 reaches the standard and gets into after denitration chamber 17, spout ammonia shower 12 and spray the aqueous ammonia, carry out denitration treatment, wherein through will pass through the gas that denitration chamber 17 was handled passes through second heat exchanger 13 with get into the aqueous ammonia before denitration chamber 17 carries out the heat transfer, has practiced thrift the energy that the aqueous ammonia preheats, has reduced the aqueous ammonia and has mixed the decline influence to flue gas temperature in the flue gas, and then has guaranteed more thoroughly to flue gas denitration, has promoted the device's purifying effect. After denitration is performed on flue gas, the flue gas enters the spraying ammonia absorption chamber 18 through the air holes 15, the ammonia absorption spraying pipe 19 sprays ammonia absorbent, so that purification treatment is performed on the flue gas, and the flue gas is discharged through the exhaust chimney 20 after the purification treatment is completed.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.