阅读说明：本技术 一种基于链篦机-回转窑的球团焙烧烟气脱硝脱硫装置及方法 (Pellet roasting flue gas denitration and desulfurization device and method based on chain grate-rotary kiln ) 是由 朱廷钰 刘霄龙 刘法高 范朝伟 赵瑞壮 郜国平 蔡茂宇 于 2019-12-02 设计创作，主要内容包括：本发明提供了一种基于链篦机-回转窑的球团焙烧烟气脱硝脱硫装置及方法,所述装置包括反应系统和烟气处理系统,反应系统包括依次连接的链篦机和回转窑,烟气处理系统包括SNCR单元、SCR单元、臭氧氧化单元和硫硝吸收单元,所述回转窑的烟气出口经过SNCR单元后连接至链篦机的气体入口,所述链篦机的气体出口再依次连接SCR单元、臭氧氧化单元和硫硝吸收单元。本发明所述装置将球团生产系统和烟气处理系统相结合,利用焙烧烟气的温度、组成特点以及与链篦机的换热,依次进行脱硝、脱硫处理,提高烟气污染物的脱除效率；所述装置利用链篦机不同区域的温度特性与不同阶段的烟气换热,提高热量的利用效率,降低能耗与运行成本。(The invention provides a pellet roasting flue gas denitration and desulfurization device and method based on a grate-rotary kiln, wherein the device comprises a reaction system and a flue gas treatment system, the reaction system comprises the grate and the rotary kiln which are sequentially connected, the flue gas treatment system comprises an SNCR unit, an SCR unit, an ozone oxidation unit and a sulfur and nitrate absorption unit, a flue gas outlet of the rotary kiln is connected to a gas inlet of the grate after passing through the SNCR unit, and a gas outlet of the grate is sequentially connected with the SCR unit, the ozone oxidation unit and the sulfur and nitrate absorption unit. The device combines a pellet production system and a flue gas treatment system, sequentially carries out denitration and desulfurization treatment by utilizing the temperature and composition characteristics of roasting flue gas and the heat exchange with a chain grate machine, and improves the removal efficiency of flue gas pollutants; the device utilizes the temperature characteristic of the chain grate in different areas and the flue gas heat exchange in different stages, improves the utilization efficiency of heat, and reduces energy consumption and operation cost.)

1. The utility model provides a pellet calcination flue gas denitration desulphurization unit based on grate-rotary kiln which characterized in that, the device includes reaction system and flue gas processing system, reaction system is including the grate and the rotary kiln that connect gradually, flue gas processing system includes SNCR unit, SCR unit, ozone oxidation unit and sulphur nitre absorption unit, the gas outlet of rotary kiln is connected to the gas inlet of grate behind the SNCR unit, the gas outlet of grate connects gradually SCR unit, ozone oxidation unit and sulphur nitre absorption unit again.

2. The apparatus of claim 1, wherein the grate is sequentially divided into a first drying section, a second drying section, a first preheating section and a second preheating section along the feeding direction of the pellets;

preferably, one end of the rotary kiln, which is close to the chain grate, is provided with a pellet inlet and a flue gas outlet, and the other end of the rotary kiln is provided with a pellet outlet and a fuel inlet;

preferably, the reaction system further comprises an annular cooler, and a pellet outlet of the rotary kiln is connected with the annular cooler;

preferably, the circular cooler sequentially comprises a first cooling section, a second cooling section and a third cooling section along the conveying direction of the pellets.

3. The apparatus according to claim 2, wherein the flue gas outlet of the rotary kiln is connected to the second preheating section of the grate by a flue gas return line;

preferably, the SNCR unit is disposed at the top of the second preheating section;

preferably, a gas outlet of the second preheating section is connected to a gas inlet of the SCR unit, a gas outlet of the SCR unit is connected to a gas inlet of the second drying section, and a gas outlet of the second drying section is sequentially connected to the ozone oxidation unit and the sulfur and nitrate absorption unit;

preferably, the SCR unit comprises an SCR reactor;

preferably, the ozone oxidation unit comprises an ozone generating device, and an outlet of the ozone generating device is connected with a flue gas pipeline;

preferably, the sulfur and nitrate absorption unit comprises a semi-dry desulfurization unit.

4. The apparatus of any one of claims 1-3, wherein the flue gas treatment system comprises a dust removal unit comprising at least one stage of dust remover;

preferably, the dust removal unit comprises a first dust remover, a second dust remover and a third dust remover, the first dust remover is arranged between the gas outlet of the second preheating section and the SCR unit, the second dust remover is arranged between the gas outlet of the second drying section and the ozone oxidation unit, and the third dust remover is arranged behind the sulfur and nitrate absorption unit;

preferably, the flue gas treatment system comprises a chimney, and the gas outlet of the third dust remover is connected with the chimney;

preferably, the first dust separator includes a cyclone;

preferably, the second precipitator comprises an electrostatic precipitator;

preferably, the third precipitator comprises a bag precipitator.

5. The device according to any one of claims 2 to 4, wherein a cold air device is connected to the bottom of the circular cooler and is used for introducing a heat exchange medium into the circular cooler;

preferably, top outlets of different cooling sections of the circular cooler are independently connected with the chain grate machine or the rotary kiln;

preferably, the top outlet of the first cooling section is connected with the fuel inlet of the rotary kiln, the top outlet of the second cooling section is connected with the gas inlet of the first preheating section, and the top outlet of the third cooling section is connected with the gas inlet of the first drying section;

preferably, a fourth dust remover is arranged on a pipeline between the top outlet of the third cooling section and the gas inlet of the first drying section;

preferably, the fourth dust separator includes a cyclone;

preferably, the gas outlet of the first preheating section is connected to a second dust collector, and the gas outlet of the first drying section is connected to a chimney.

6. A method for denitration and desulfurization of pellet roasting flue gas by using the device of any one of claims 1 to 5, which is characterized by comprising the following steps:

the flue gas generated by roasting the pellet materials is subjected to SNCR treatment, then enters a chain grate for heat exchange, and then is subjected to SCR treatment, ozone oxidation treatment and sulfur and nitrate absorption treatment in sequence to obtain the purified flue gas.

7. The method as claimed in claim 6, wherein the pellet materials are dried and preheated by a chain grate and enter a rotary kiln for roasting;

preferably, the fuel used for roasting comprises any one or a combination of at least two of natural gas, coal gas, heavy oil or coal, preferably coal gas;

preferably, NO in the roasting flue gas_xThe concentration of (A) is 300-400 mg/Nm³，SO₂The concentration of (A) is 750-900 mg/Nm³The concentration of the particulate matter is 50-130 mg/Nm³；

Preferably, the temperature of the SNCR treatment of the flue gas is 800-1100 ℃;

preferably, ammonia gas is sprayed into the flue gas during SNCR treatment;

preferably, the ammonia gas and NO in the roasting flue gas_xThe molar ratio of (0.5-1.0): 1.

8. The method according to claim 6 or 7, characterized in that the roasting flue gas enters a second preheating section of the chain grate for heat exchange and temperature reduction after being subjected to SNCR treatment;

preferably, the SCR treatment temperature is 300-400 ℃;

preferably, the catalyst used for the SCR treatment comprises a vanadium tungsten titanium-based catalyst or a vanadium molybdenum titanium-based catalyst;

preferably, ammonia gas is sprayed into the flue gas during SCR treatment;

preferably, the ammonia gas and residual NO in the roasting flue gas_xThe molar ratio of (0.8-1.2) to (1);

preferably, the flue gas after SCR treatment passes through a second drying section of the chain grate machine to dry the pellet materials.

9. The method according to any one of claims 6 to 8, wherein ozone is introduced into the flue gas during the ozone oxidation treatment;

preferably, the ozone and the residual NO in the roasting flue gas_xThe molar ratio of (0.8-1.5) to (1);

preferably, the sulfur and nitrate absorption treatment adopts semi-dry desulfurization and denitrification;

preferably, the semi-dry process comprises any one of a circulating fluidized bed process, a rotary spray drying process or a dense phase drying tower process;

preferably, the flue gas is subjected to dust removal treatment before SCR treatment, before ozone oxidation treatment and after sulfur and nitrate absorption treatment.

10. The method according to any one of claims 6 to 9, wherein the pellet material is subjected to tertiary cooling in an annular cooler after roasting;

preferably, a heat exchange medium is introduced into the circular cooler in the cooling process;

preferably, the heat exchange medium comprises air;

preferably, the heat exchange medium after the primary cooling enters the rotary kiln and is used for roasting the pellet materials;

preferably, the heat exchange medium after the secondary cooling enters a first preheating section of the drying grate for preheating the pellet materials, and then is mixed with the outlet flue gas of the second drying section;

preferably, the heat exchange medium after the tertiary cooling enters a first drying section of the chain grate machine and is used for drying the pellet materials;

preferably, the heat exchange medium after the three-stage cooling is subjected to dust removal treatment before entering the first drying section.

Technical Field

The invention belongs to the technical field of flue gas treatment, and relates to a pellet roasting flue gas denitration and desulfurization device and method, in particular to a pellet roasting flue gas denitration and desulfurization device and method based on a grate-rotary kiln.

Background

At present, main production enterprises in the iron and steel industry adjust the structure of a blast furnace to improve the economic indexes of iron-making technology, expand the requirements on pellets and better develop the pellets. Compared with sintered ore, the pellet ore has the advantages of uniform granularity, high iron content, good reducibility and good low-temperature strength, and the use of the pellet ore can generally improve the yield and reduce the coke ratio.

The pellet production process mainly comprises the steps of raw material preparation, burdening, mixing, pelletizing, drying, roasting, cooling, finished product screening and the like, and at present, the pellet roasting process mainly comprises a shaft furnace roasting process, a belt type roasting machine process and a grate-rotary kiln process. The shaft furnace has the disadvantages of nonuniform roasting, poor product quality and low production rate due to the process limitation of the shaft furnace, and is difficult to meet the production requirements of a large-scale blast furnace; the travelling grate needs to be made of heat-resistant steel because the trolley and the grate run at high temperature, so that the equipment manufacturing cost is high, and in addition, the air supply system has high power consumption, larger running cost and less application. The grate-rotary kiln has the advantages of high production capacity, high heat utilization rate, low total energy consumption, uniform quality of produced pellets, high strength and more application in pellet production.

In pellet production processes, especially pellet firing processes, NO_xThe emission intensity is higher, and as the emission standard of atmospheric pollutants is more strict, the treatment of pellet roasting flue gas is urgent, so that a proper method must be adopted to treat NO generated by the grate-rotary kiln process_xAnd carrying out high-efficiency treatment. At present, the methods for treating nitrogen oxides mainly comprise a selective catalytic reduction method (SCR), a selective non-catalytic reduction method (SNCR) and an ozone oxidation denitration method.

CN 108392984A discloses grate rotary kiln deNOx systems and denitration method, the system is including the grate, rotary kiln and the ring cold machine that connect gradually, the grate includes the dry section of forced air, convulsions dry section, first preheating section and the second preheating section that connect gradually, deNOx systems still includes the denitration reactor of locating the grate outside, the second preheating section has the exhanst gas outlet, the convulsions dry section has the flue gas entry, the denitration reactor is connected between the exhanst gas outlet of second preheating section and the flue gas entry of convulsions dry section, still be connected with reductant injection apparatus between the exhanst gas outlet of denitration reactor and second preheating section. The flue gas that this system was handled is mainly the flue gas of second preheating section in the chain grate, and this part flue gas temperature is higher, is difficult to directly carry out SCR denitration treatment, and does not handle the flue gas in the rotary kiln, and flue gas treatment is not thorough.

CN 206168206U discloses a grate-rotary kiln denitration system, which comprises a first preheating section and a second preheating section for heating pellets, and further comprises a denitration device for removing nitrogen oxides in flue gas, wherein the denitration device is arranged in an inner cavity of the second preheating section; the device only utilizes the temperature of the second preheating section to carry out SNCR treatment on the flue gas, but the treatment time and the efficiency at the stage are lower, the emission requirement is difficult to reach, and only denitration treatment is carried out, and sulfur oxides are not treated and cannot be directly discharged.

In summary, for the flue gas treatment generated by the grate-rotary kiln process, the corresponding treatment measures are required to be performed in combination with the structure, the temperature and the composition of the flue gas, so as to realize the efficient purification of the flue gas.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a pellet roasting flue gas denitration and desulfurization device and method based on a grate-rotary kiln.

In order to achieve the purpose, the invention adopts the following technical scheme:

on one hand, the invention provides a pellet roasting flue gas denitration and desulfurization device based on a grate-rotary kiln, which comprises a reaction system and a flue gas treatment system, wherein the reaction system comprises the grate and the rotary kiln which are sequentially connected, the flue gas treatment system comprises an SNCR unit, an SCR unit, an ozone oxidation unit and a sulfur and nitrate absorption unit, a flue gas outlet of the rotary kiln is connected to a gas inlet of the grate after passing through the SNCR unit, and a gas outlet of the grate is sequentially connected with the SCR unit, the ozone oxidation unit and the sulfur and nitrate absorption unit.

According to the invention, roasting flue gas is treated on the basis of a grate-rotary kiln system used for pellet production, the heat of the flue gas is fully utilized for drying and preheating pellet materials, firstly SNCR treatment is carried out by utilizing the characteristic of high temperature of the roasting flue gas, the generated flue gas is taken away while the materials are preheated when the roasting flue gas passes through the grate, SCR denitration treatment and ozone oxidation treatment are further carried out in sequence, and then sulfur and nitrate absorption treatment is carried out, so that pollutants in the flue gas are fully removed; and the heat exchange with different areas of the chain grate machine in the flue gas treatment process can also greatly improve the utilization efficiency of heat, and reduce the energy consumption and the operation cost of the device.

The following technical solutions are preferred technical solutions of the present invention, but not limited to the technical solutions provided by the present invention, and technical objects and advantageous effects of the present invention can be better achieved and achieved by the following technical solutions.

As the preferable technical scheme of the invention, the chain grate is sequentially divided into a first drying section, a second drying section, a first preheating section and a second preheating section along the feeding direction of the pellets.

In the invention, the temperature in the chain grate is gradually increased along the conveying direction of the pellet materials, and the drying and preheating of the materials are sequentially completed; according to the difference of the water content of the materials in the first drying section and the second drying section, the former adopts forced air drying, and the latter adopts air draft drying.

Preferably, one end of the rotary kiln, which is close to the chain grate, is provided with a pellet inlet and a flue gas outlet, the other end of the rotary kiln is provided with a pellet outlet and a fuel inlet, and pellet materials and fuel reversely contact in the rotary kiln.

Preferably, the reaction system further comprises an annular cooler, and the pellet outlet of the rotary kiln is connected with the annular cooler.

Preferably, the circular cooler sequentially comprises a first cooling section, a second cooling section and a third cooling section along the conveying direction of the pellets.

As a preferable technical scheme of the invention, the flue gas outlet of the rotary kiln is connected to the second preheating section of the chain grate machine through a flue gas return pipeline.

Preferably, the SNCR unit is disposed at the top of the second preheating section.

Preferably, the gas outlet of the second preheating section is connected to the gas inlet of the SCR unit, and the gas outlet of the SCR unit is connected to the gas inlet of the second drying section, and the gas outlet of the second drying section is sequentially connected to the ozone oxidation unit and the sulfur and nitrate absorption unit.

In the invention, the flue gas is subjected to SCR treatment after passing through the second preheating section according to the temperature condition, and the temperature is still higher if the flue gas is directly subjected to ozone denitration treatment after being reduced again, so that the flue gas is firstly subjected to temperature matching with the flue gasThe second drying section carries out heat exchange and can also take away a small amount of flue gas in the section, the content of the nitrogen oxide is lower, the required ozone amount is less, and the oxidized nitrogen oxide is carried with SO₂Absorbing during the sulfur and nitrate absorption treatment.

Preferably, the SCR unit comprises an SCR reactor.

Preferably, the ozone oxidation unit comprises an ozone generating device, and an outlet of the ozone generating device is connected with a flue gas pipeline.

In the invention, the ozone denitration treatment can be finished by mixing with ozone in the movement process of the flue gas, a reaction device is not required to be specially arranged, and only an ozone generating device is required.

Preferably, the sulfur and nitrate absorption unit comprises a semi-dry desulfurization unit.

In the invention, the flue gas desulfurization adopts a semidry method, the calcium-based desulfurizer is mainly used, no wastewater is generated, besides the main desulfurization, the calcium-based desulfurizer also has a good absorption effect on acid gases HF, HCl, heavy metal Hg and the like in the flue gas, and the high-efficiency synergistic purification of various pollutants can be realized.

As the preferable technical scheme of the invention, the flue gas treatment system comprises a dust removal unit, and the dust removal unit comprises at least one stage of dust remover.

Preferably, the dust removal unit comprises a first dust remover, a second dust remover and a third dust remover, the first dust remover is arranged between the gas outlet of the second preheating section and the SCR unit, the second dust remover is arranged between the gas outlet of the second drying section and the ozone oxidation unit, and the third dust remover is arranged behind the sulfur and nitrate absorption unit.

In the present invention, the flue gas contains NO in addition to NO_xAnd SO₂When the gas pollutants contain dust particles, the dust removal treatment is needed, and according to the treatment path of the flue gas, the flue gas needs to be removed with dust after passing through the chain grate and before being discharged.

Preferably, the flue gas treatment system comprises a chimney, and the gas outlet of the third dust remover is connected with the chimney.

Preferably, the first dust separator includes a cyclone.

Preferably, the second precipitator comprises an electrostatic precipitator.

Preferably, the third precipitator comprises a bag precipitator.

In the invention, the multistage dust remover is selected to carry out classification treatment on the particles, and the particle size of the separable particles is gradually reduced, namely the precision of the dust remover is gradually improved.

As a preferred technical scheme of the invention, the bottom of the circular cooler is connected with a cold air device, and the cold air device is used for introducing a heat exchange medium into the circular cooler.

Preferably, top outlets of different cooling sections of the circular cooler are independently connected with the chain grate machine or the rotary kiln.

Preferably, the top outlet of the first cooling section is connected with the fuel inlet of the rotary kiln, the top outlet of the second cooling section is connected with the gas inlet of the first preheating section, and the top outlet of the third cooling section is connected with the gas inlet of the first drying section.

In the invention, the ring cooling machine cools the pellet materials, and the temperatures of media after heat exchange at different cooling sections are different, so that the ring cooling machine can be used in different areas in the device according to the temperature of the media, and the heat carried by the media can be fully utilized.

Preferably, a fourth dust remover is arranged on a pipeline between the top outlet of the third cooling section and the gas inlet of the first drying section.

Preferably, the fourth dust separator includes a cyclone.

Preferably, the gas outlet of the first preheating section is connected to a second dust collector, and the gas outlet of the first drying section is connected to a chimney.

On the other hand, the invention provides a method for denitration and desulfurization of pellet roasting flue gas by adopting the device, which comprises the following steps:

the flue gas generated by roasting the pellet materials is subjected to SNCR treatment, then enters a chain grate for heat exchange, and then is subjected to SCR treatment, ozone oxidation treatment and sulfur and nitrate absorption treatment in sequence to obtain the purified flue gas.

As the preferable technical scheme of the invention, the pellet materials are dried and preheated by the chain grate and enter the rotary kiln for roasting.

Preferably, NO in the roasting flue gas_xThe concentration of (A) is 300-400 mg/Nm³E.g. 300mg/Nm³、320mg/Nm³、340mg/Nm³、360mg/Nm³、380mg/Nm³Or 400mg/Nm³And the like, but are not limited to the recited values, and other unrecited values within the numerical range are equally applicable; SO (SO)₂The concentration of (A) is 750-900 mg/Nm³E.g. 750mg/Nm³、780mg/Nm³、800mg/Nm³、820mg/Nm³、850mg/Nm³、880mg/Nm³Or 900mg/Nm³And the like, but are not limited to the recited values, and other unrecited values within the numerical range are equally applicable; the concentration of the particulate matter is 50-130 mg/Nm³E.g. 50mg/Nm³、60mg/Nm³、80mg/Nm³、100mg/Nm³、120mg/Nm³Or 130mg/Nm³And the like, but are not limited to the recited values, and other values not recited within the numerical range are also applicable.

Preferably, the temperature of the flue gas subjected to SNCR treatment is 800 to 1100 ℃, for example 800 ℃, 850 ℃, 900 ℃, 950 ℃, 1000 ℃, 1050 ℃, or 1100 ℃, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.

Preferably, the SNCR treatment is carried out by injecting ammonia gas into the flue gas, wherein the source of ammonia gas comprises any one of ammonia water, urea or liquid ammonia or a combination of at least two of them, typically but not limited to: combinations of ammonia and urea, urea and liquid ammonia, urea and liquid ammonia, and the like.

Preferably, the ammonia gas and NO in the roasting flue gas_xIs (0.5-1.0) 1, for example 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1 or 1.0:1, etc., but are not limited to the recited values, and other values not recited within the numerical range are also applicable.

In the invention, the temperature of the roasting flue gas is high、NO_xHigh concentration, SNCR treatment first, NO_xThe removal rate of the catalyst can reach about 40 percent.

As the preferred technical scheme of the invention, the roasting flue gas enters the second preheating section of the chain grate machine for heat exchange and temperature reduction after being subjected to SNCR treatment.

Preferably, the temperature of the SCR treatment is 300 to 400 ℃, for example, 300 ℃, 320 ℃, 340 ℃, 360 ℃, 380 ℃ or 400 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the catalyst used for the SCR treatment comprises a vanadium tungsten titanium based catalyst or a vanadium molybdenum titanium based catalyst, in particular V₂O₅-WO₃/TiO₂Or V₂O₅-MoO₃/TiO₂。

Preferably, the SCR treatment is carried out by injecting ammonia gas into the flue gas, wherein the source of ammonia gas comprises any one of ammonia water, urea or liquid ammonia or a combination of at least two of them, typical but non-limiting examples of which are: combinations of ammonia and urea, urea and liquid ammonia, urea and liquid ammonia, and the like.

Preferably, the ammonia gas and residual NO in the roasting flue gas_xThe molar ratio of (1) to (0.8: 1.2), for example, 0.8:1, 0.9:1, 1.0:1, 1.1:1 or 1.2:1, is not limited to the above-mentioned values, and other values not shown in the above-mentioned numerical range are also applicable.

Preferably, the flue gas after SCR treatment passes through a second drying section of the chain grate machine to dry the pellet materials.

As a preferable technical scheme of the invention, during the ozone oxidation treatment, ozone is introduced into the flue gas.

Preferably, the ozone and the residual NO in the roasting flue gas_xThe molar ratio of (1) to (0.8-1.5), for example, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1 or 1.5:1, is not limited to the values listed, and other values not listed in the numerical range are also applicable.

Preferably, the sulfur and nitrate absorption treatment adopts semi-dry desulfurization and denitrification.

Preferably, the semi-dry process comprises any one of a circulating fluidized bed process, a rotary spray drying process, or a dense phase drying tower process.

In the invention, the flue gas desulfurization adopts a semidry method, the calcium-based desulfurizer is mainly used, no wastewater is generated, the semidry method is mainly used for desulfurization, a small amount of nitrogen oxides generated in an ozone oxidation stage can be absorbed, and meanwhile, the semidry method also has a good absorption effect on acid gases HF, HCl, heavy metal Hg and the like in the flue gas, and can realize efficient synergistic purification of various pollutants.

Preferably, the flue gas is subjected to dust removal treatment before SCR treatment, before ozone oxidation treatment and after sulfur and nitrate absorption treatment.

As the preferable technical scheme of the invention, the pellet material is roasted and then is subjected to three-level cooling in the circular cooler.

Preferably, a heat exchange medium is introduced into the circular cooler in the cooling process.

Preferably, the heat exchange medium comprises air.

Preferably, the heat exchange medium after the primary cooling enters the rotary kiln and is used for roasting the pellet materials.

Preferably, the heat exchange medium after the secondary cooling enters a first preheating section of the drying grate for preheating the pellet materials, and then is mixed with the outlet flue gas of the second drying section.

Preferably, the heat exchange medium after the tertiary cooling enters a first drying section of the chain grate machine and is used for drying the pellet materials.

Preferably, the heat exchange medium after the three-stage cooling is subjected to dust removal treatment before entering the first drying section.

Compared with the prior art, the invention has the following beneficial effects:

(1) the device combines a pellet production system and a flue gas treatment system, sequentially carries out denitration and desulfurization treatment by utilizing the temperature and composition characteristics of roasting flue gas and the heat exchange with a chain grate machine, improves the removal efficiency of flue gas pollutants, and improves the NO in the purified flue gas_xThe concentration is reduced to 16mg/Nm³Hereinafter, SO₂The concentration is reduced to 20mg/Nm³Thereafter, the concentration of the particulate matter was reduced to 10mg/Nm³The following;

(2) the device of the invention utilizes the temperature characteristics of different areas of the chain grate to exchange heat with the flue gas in different stages, thereby improving the utilization efficiency of heat and reducing the energy consumption and the operation cost;

(3) the invention does not need to reheat the discharged flue gas, simplifies the process and reduces the cost of investment on reheating equipment.

Drawings

FIG. 1 is a schematic structural diagram of a pellet-roasting flue gas denitration and desulfurization device based on a grate-rotary kiln, which is provided by embodiment 1 of the invention;

the method comprises the following steps of 1-a first drying section, 2-a second drying section, 3-a first preheating section, 4-a second preheating section, 5-a rotary kiln, 6-a first cooling section, 7-a second cooling section, 8-a third cooling section, 9-a cold air device, 10-an SNCR unit, 11-a first dust remover, 12-an SCR unit, 13-a second dust remover, 14-an ozone oxidation unit, 15-a sulfur and nitrate absorption unit, 16-a third dust remover, 17-a fourth dust remover and 18-a chimney.

Detailed Description

In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the following embodiments are only simple examples of the present invention and do not represent or limit the scope of the present invention, which is defined by the claims.

The invention provides a pellet roasting flue gas denitration and desulfurization device and method based on a grate-rotary kiln, wherein the device comprises a reaction system and a flue gas treatment system, the reaction system comprises the grate and the rotary kiln 5 which are sequentially connected, the flue gas treatment system comprises an SNCR unit 10, an SCR unit 12, an ozone oxidation unit 14 and a sulfur and nitrate absorption unit 15, a flue gas outlet of the rotary kiln 5 is connected to a gas inlet of the grate after passing through the SNCR unit 10, and a gas outlet of the grate is sequentially connected with the SCR unit 12, the ozone oxidation unit 14 and the sulfur and nitrate absorption unit 15.

The method comprises the following steps:

the flue gas generated by roasting the pellet materials is subjected to SNCR treatment, then enters a chain grate for heat exchange, and then is subjected to SCR treatment, ozone oxidation treatment and sulfur and nitrate absorption treatment in sequence to obtain the purified flue gas.

The following are typical but non-limiting examples of the invention: