CN111318162A - Belt type pellet roasting flue gas SCR and active coke combined denitration and desulfurization system and method - Google Patents

Abstract

The invention belongs to the technical field of industrial waste gas treatment, and provides a belt type pellet roasting flue gas SCR and active coke combined denitration and desulfurization system and a method. The system is combinedThe gas flow channel is arranged, and the coke oven gas is used as fuel, so that the purpose of roasting pellets is achieved, and the fuel cost is reduced; can also obviously reduce NO in the discharged flue gas_xThe concentration and the concentration of oxysulfide have high dust removal efficiency, the iron-containing dust is recycled, and the smoke pollutants can meet the requirement of ultralow emission; and the active coke unit can utilize unreacted ammonia gas in SCR denitration to be combined with the active coke to cooperatively perform denitration and desulfurization treatment, and meanwhile, the ammonia escape phenomenon is avoided.

Description

A combined denitration and desulfurization system and method for belt-type pellet roasting flue gas SCR and activated coke

technical field

The invention belongs to the technical field of waste gas treatment, and relates to a flue gas denitration and desulfurization system and method, in particular to a combined denitration and desulfurization system and method of belt pellet roasting flue gas SCR and activated coke.

Background technique

Sinter is an irregularly shaped porous lump ore that requires the addition of fuel to the batch. The pellets are regular-shaped balls with small and uniform particle size, which is beneficial to the improvement of the air permeability of the blast furnace column and the uniform distribution of the air flow; the cold strength (compression resistance and wear resistance) is high, which is convenient for transportation, handling and storage, and less powder. ; The high iron content and bulk density of the pellets are beneficial to increase the effective weight of the blast furnace column, increase the output and reduce the coke ratio; the pellets have good reducibility.

There are three main production processes for pellets: shaft furnace method, chain grate-rotary kiln method, and belt roaster method. These three pelletizing production processes have their own characteristics.

The temperature in the shaft furnace is difficult to control, the output of a single furnace is small, the adaptability to raw materials is poor, the quality of pellets is easy to fluctuate, and it cannot meet the requirements of modern blast furnaces for clinker, so it is limited in application and development; chain grate machine-rotary In the kiln pellet roasting process, if the quality of green pellets is poor, the preheating strength is not good enough, the powder is too much, or the temperature in the kiln is not properly controlled, the phenomenon of "ringing" is easy to occur. When baking flux pellets, the phenomenon of "ringing" is more prominent. , maintenance is also more difficult; the belt roaster has centralized equipment, convenient operation, maintenance and management, short roasting cycle, easy adjustment of roasting temperature, strong adaptability to raw materials, and the produced pellets are of good quality and uniform particle size. Suitable for large pelletizing plants.

In the pellet production process, the _NOx emission intensity of the pellet roasting flue gas is relatively high. CN 108404660A discloses an SCR denitration method in the production process of iron ore oxidation pellets. The method performs ammonia spraying in the drafting and drying section of pellet production. SCR denitration, the specific method is to divide the draft drying section and the preheating section into sections, with the average water content of pellets in the material layer as the limit of 3%, into the front and rear sections of the draft drying, and divide the preheating section into high-sulfur flue gas and low-sulfur flue gas. The low-sulfur flue gas is introduced into the latter part of the exhaust drying, and the concentration of SO ₂ in the hood in the latter part of the exhaust drying is controlled to be less than 600mg/m ³ . NH ₃ , the ratio of NH ₃ /NO is controlled according to the ratio of magnetite and hematite in the pellet raw material to achieve 20%-40% emission reduction of NO _x , but this method does not fully utilize the heat of the flue gas , and only the flue gas in the extraction and drying section is treated.

CN 108355488A discloses a waste gas circulating denitrification method for iron ore pellets. The method is to circulate the _NOx flue gas generated by iron ore pellets in the production process of iron ore pellets to the medium and low temperature cooling section, and carry out the process in the medium and low temperature cooling section. Ammonia spraying for denitrification, the specific method is to combine the exhaust gas from the exhaust drying section with the high-sulfur flue gas with a SO ₂ concentration greater than 300mg/m ³ in the preheating and heating section, and then go through dust removal, desulfurization and purification in sequence, and desulfurize it to less than 50mg/m ³ , and then remove it. It is combined with the waste gas from the previous section whose SO ₂ concentration is lower than 300 mg/m ³ in the preheating and heating section, and is circulated to the medium and low temperature cooling section as a cooling medium. However, this method can only achieve 15%-25% emission reduction of _NOx , and the desulfurization and denitrification efficiency is poor.

The more mature flue gas desulfurization technologies mainly include wet, dry and semi-dry flue gas desulfurization technologies. Among them, the wet desulfurization process system is complex, the equipment is huge, the water consumption is large, and the one-time investment is high, and it is generally suitable for large power plants; It seriously affects the comprehensive utilization of by-products, and has high requirements for the automatic control of the drying process; the semi-dry desulfurization process has low investment, low operating costs, small corrosion, less floor space, reliable process, and has a good development prospect.

Therefore, in view of the deficiencies of the prior art, an appropriate method must be used to efficiently treat the _NOx , sulfur oxides and particulate matter produced by the belt roaster.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a combined denitration and desulfurization system and method of belt-type pellet roasting flue gas SCR and activated coke, which can reasonably utilize belt-type roasting machine The heat of each section of flue gas, and the particulate matter, nitrogen oxides and sulfur oxides in the flue gas are removed according to the characteristics of each section of the flue gas, and the overall emission reduction effect of pollutants is good.

In order to achieve this object of the invention, the present invention adopts the following technical solutions:

In a first aspect, the present invention provides a combined denitration and desulfurization system for SCR and activated coke from flue gas roasting of belt pellets. The system includes a belt roasting unit, an SCR denitration device, an activated coke unit and a dust removal unit.

The dedusting unit includes a first dedusting device, a second dedusting device, a third dedusting device and a fourth dedusting device.

The belt roasting unit includes a belt roaster and a matching gas conveying device, and the belt roaster includes a blast drying section, a suction drying section, a preheating section, a roasting section, a soaking section, a Cold section and secondary cold section.

The gas conveying device conveys the external cooling source to the first cooling section and the second cooling section independently.

The hot exhaust gas in the second cooling section flows through the blast drying section and the first dust removal device in sequence and then is discharged through the chimney.

The hot exhaust gas in the first cold section flows into the preheating section, the roasting section and the soaking section independently; the mixed flue gas generated in the roasting section and soaking section flows through the second dust removal device and the SCR denitration device in sequence, and then flows into the extraction and drying section. .

The mixed flue gas generated by the extraction and drying section and the preheating section flows through the third dust removal device, the active coke unit and the fourth dust removal device in sequence, and is discharged through the chimney.

In the present invention, a second dust removal device is arranged before the SCR denitration device, and the iron-containing dust is captured by the second dust removal device, so that the iron-containing dust can be recycled to the belt roaster for reuse.

In the pellet production process of the belt roaster, the temperature of the flue gas before entering the ventilation drying section is usually 300-400 °C, which meets the temperature window of the SCR reaction. Therefore, an SCR denitration device is installed in this section to realize the pellet roasting flue gas. Effective removal of nitrogen oxides from gas.

The flue gas after SCR denitration treatment flows into the extraction and drying section, and the mixed flue gas generated in the extraction and drying section and the preheating section is then subjected to dust removal, activated coke adsorption, denitration and desulfurization, and dust removal in sequence to meet the emission standards.

The belt-type pellet roasting flue gas denitration and desulfurization system provided by the present invention can effectively reduce the concentration of nitrogen oxides, sulfur oxides and particulate matter in the exhausted flue gas according to the characteristics of the flue gas of each section of the belt roaster, and significantly improve the smoke Qi management effect.

The supporting gas conveying device of the present invention includes but is not limited to a blower and/or an induced draft fan. Those skilled in the art can reasonably select the model and installation position of the gas conveying device according to the flow direction of the gas. The external cooling source is a gas with a relatively low temperature, preferably air.

Preferably, the fuel used in the belt roaster is coke oven gas.

The traditional belt roaster needs to use gas and/or heavy oil with high calorific value as fuel. In the present invention, the hot exhaust gas of a cold section is introduced into the preheating section, the roasting section and the soaking section, so that the hot exhaust gas of a cold section is used as a preheating section. The combustion-supporting gas in the hot section, the roasting section and the soaking section reduces the demand of the belt roaster for high calorific value fuel, so that the belt roaster can still complete the pellet roasting when the coke oven gas is used as the fuel.

Preferably, the coke oven gas is injected into the belt roaster by a coke oven gas burner with an automatic adjustment device, so as to adjust the roasting temperature of each stage.

Preferably, the first dust removal device includes any one or a combination of at least two of electrostatic precipitators, cyclones or bag filters, and a typical but non-limiting combination includes a combination of electrostatic precipitators and cyclones. A combination, a combination of a cyclone and a bag filter, a combination of an electrostatic precipitator and a bag filter, or a combination of an electrostatic precipitator, a cyclone and a bag filter, preferably an electrostatic precipitator.

Preferably, the second dust removal device includes any one or a combination of at least two of electrostatic precipitators, cyclones or bag filters, and a typical but non-limiting combination includes a combination of electrostatic precipitators and cyclones. A combination, a combination of a cyclone and a bag filter, a combination of an electrostatic precipitator and a bag filter, or a combination of an electrostatic precipitator, a cyclone and a bag filter, preferably a cyclone.

The iron-containing dust collected by the second dedusting unit of the present invention can be returned to the belt roaster for recycling, thereby reducing the efflux of dust.

Preferably, the third dust removal device includes any one or a combination of at least two of an electrostatic precipitator, a cyclone or a bag filter, and a typical but non-limiting combination includes a combination of an electrostatic precipitator and a cyclone. A combination, a combination of a cyclone and a bag filter, a combination of an electrostatic precipitator and a bag filter, or a combination of an electrostatic precipitator, a cyclone and a bag filter, preferably an electrostatic precipitator.

Preferably, the fourth dust removal device includes any one or a combination of at least two of electrostatic precipitators, cyclones or bag filters, and a typical but non-limiting combination includes a combination of electrostatic precipitators and cyclones. A combination, a combination of a cyclone and a bag filter, a combination of an electrostatic precipitator and a bag filter, or a combination of an electrostatic precipitator, a cyclone and a bag filter, preferably a bag filter.

Preferably, the activated coke unit includes an activated coke reaction tower and an activated coke regeneration tower, and the mixed flue gas generated by the extraction and drying section and the preheating section flows through the third dust removal device, the activated coke reaction tower and the fourth dust removal device in sequence. , out through the chimney.

The active coke reaction tower and the active coke regeneration tower described in the present invention are both devices commonly used in the art, and the present invention does not specifically limit the parameters of the active coke reaction tower and the active coke regeneration tower.

Activated coke adsorption desulfurization is an oxygen purification process in which activated coke is used to adsorb SO ₂ in flue gas, and in the presence of flue oxygen and water vapor, sulfur oxides are converted into sulfuric acid and adsorbed in the pores of activated coke. The activated coke after adsorption saturation is transported from the activated coke reaction tower to the activated coke regeneration tower, and desorbs SO ₂ under heating conditions, releasing a mixed gas with a volume fraction of SO ₂ exceeding 20%, so that the activated coke can restore the adsorption performance, so that the The desorbed activated coke can be reused to adsorb sulfur dioxide; and the mixed gas with SO ₂ volume fraction exceeding 20% produced by desorption can be used to produce sulfur-containing chemical products such as sulfuric acid. Moreover, by setting an active coke unit, the present invention combines the unreacted NH ₃ in the SCR denitration treatment process with the active coke in the active coke unit to synergistically perform denitration and desulfurization, while avoiding the occurrence of ammonia escape.

In a second aspect, the present invention provides a method for denitrification and desulfurization of belt-type pellet roasting flue gas by using the belt-type pellet roasting flue gas SCR and activated coke combined denitration and desulfurization system as described in the first aspect, and the method It includes the following steps:

(1) The hot waste gas flowing through the second cooling section of the blast drying section is dedusted and discharged through the chimney;

(2) The mixed flue gas generated in the roasting section and the soaking section is subjected to dedusting treatment and SCR denitration treatment in sequence, and the flue gas after denitration treatment flows into the extraction and drying section; the mixed flue gas generated in the extraction and drying section and the preheating section is sequentially subjected to dedusting treatment , activated coke denitration and desulfurization treatment and dust removal treatment, and then discharged;

Step (1) and step (2) are in no particular order.

Preferably, the iron-containing dust captured by the dust removal treatment in step (2) is recycled back to the belt roaster for reuse.

Preferably, the SCR denitration treatment in step (2) is to use NH ₃ for SCR denitration treatment, and the molar ratio of NH ₃ to the mixed flue gas produced _by the roasting section and the soaking section is (0.8-1.5):1, For example, it can be 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1 or 1.5:1, but is not limited to the listed values, and other values within the range are not listed The same applies to the value of , preferably (0.9-1.1):1.

Preferably, the source of NH ₃ includes any one or a combination of at least two of ammonia water, urea or liquid ammonia, and typical but non-limiting combinations include the combination of ammonia water and urea, the combination of urea and liquid ammonia, ammonia water Combination with liquid ammonia or combination of ammonia water, urea and liquid ammonia.

The denitration and desulfurization treatment of activated coke in the present invention is to use activated coke to adsorb SO ₂ in flue gas, and in the presence of flue gas and water vapor, SO ₂ is oxidized to sulfuric acid and adsorbed in the pores of activated coke; at the same time, The activated coke and the remaining NH ₃ after the SCR denitrification process synergistically denitrify, and avoid the occurrence of ammonia escape.

Preferably, the method further includes the step of desorbing the adsorption-saturated activated coke generated after the denitration and desulfurization treatment of the activated coke and recycling it to the denitration and desulfurization treatment of the activated coke.

The activated coke saturated with adsorption is transported from the activated coke reaction tower to the activated coke regeneration tower, and desorbed in the activated coke regeneration tower to release a mixed gas with a volume fraction of SO ₂ above 20%. The activated coke restores the adsorption performance and can be transported to the activated coke Reuse in the coke reaction tower.

As a preferred technical solution of the method described in the second aspect of the present invention, the method comprises the following steps:

(1) The hot waste gas flowing through the second cooling section of the blast drying section is dedusted and discharged through the chimney;

(2) The mixed flue gas generated in the roasting section and the soaking section is subjected to dedusting treatment and SCR denitration treatment in sequence, and the denitrified flue gas flows into the extraction and drying section; Activated coke denitrification and desulfurization treatment and dust removal treatment are discharged through the chimney; the adsorption saturated activated coke generated after activated coke denitration and desulfurization treatment is desorbed and reused to the activated coke reaction tower;

Step (1) and step (2) are in no particular order;

The SCR denitration treatment in step (2) is to use _NH3 for SCR denitration treatment, and the molar ratio of _NH3 to _NOx in the mixed flue gas generated in the roasting section and the soaking section is (0.8-1.5):1.

Further preferably, the iron-containing dust captured by the dedusting treatment in step (2) is recycled back to the belt roaster for reuse.

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

(1) The belt-type pellet roasting flue gas SCR and activated coke combined denitration and desulfurization system according to the present invention reasonably sets the gas flow channel, and treats nitrogen oxides, sulfur oxides and particulate matter in the flue gas according to the characteristics of each section of the flue gas , effectively utilize the heat of the flue gas itself;

(2) The present invention arranges the gas flow channels reasonably, and the system uses coke oven gas as the fuel to achieve the purpose of roasting pellets and reduce the fuel cost;

(3) The combined denitration and desulfurization system of the belt-type pellet roasting flue gas SCR and activated coke of the present invention can significantly reduce the concentration of _NOx and sulfur oxides in the exhaust flue gas, has high dust removal efficiency, and can also remove iron-containing dust Recycling, pollutants can meet the requirements of ultra-low emission;

(4) The activated coke unit described in the present invention can utilize the SCR denitration unreacted ammonia gas, combine with the activated coke, and synergistically carry out denitration and desulfurization treatment, while avoiding the phenomenon of ammonia escape.

Description of drawings

FIG. 1 is a schematic structural diagram of the combined denitration and desulfurization system of the belt-type pellet roasting flue gas SCR and activated coke provided by the present invention.

Among them: 1, blast drying section; 2, suction drying section; 3, preheating section; 4, roasting section; 5, soaking section; 6, first cooling section; 7, second cooling section; 8, first dust removal device 9, the second dust removal device; 10, the SCR denitration device; 11, the third dust removal device; 12, the activated coke reaction tower; 13, the activated coke regeneration tower; 14, the fourth dust removal device; 15, the chimney.

Detailed ways

The technical solutions of the present invention are further described below through specific embodiments. It should be understood by those skilled in the art that the embodiments are only for helping the understanding of the present invention, and should not be regarded as a specific limitation of the present invention.

The present invention provides a belt-type pellet roasting flue gas SCR and activated coke combined denitration and desulfurization system. The schematic structural diagram of the system is shown in Figure 1, including a belt-type roasting unit, an SCR denitration device 10, an activated coke unit and a dust removal unit. unit.

The dedusting unit includes a first dedusting device 8 , a second dedusting device 9 , a third dedusting device 11 and a fourth dedusting device 14 .

The belt roasting unit includes a belt roasting machine and a matching gas conveying device. The belt roasting machine includes a blast drying section 1, a suction drying section 2, a preheating section 3, a roasting section 4, and a soaking section arranged in sequence. Section 5, first cooling section 6 and second cooling section 7.

The gas conveying device transports the external cold source to the first cooling section 6 and the second cooling section 7 independently; the hot exhaust gas of the second cooling section 7 flows through the blast drying section 1 and the first dust removal device 8 in sequence through the chimney 15 Exhaust; the hot waste gas of the first cold section 6 flows into the preheating section 3, the roasting section 4 and the soaking section 5 independently; the mixed flue gas generated by the roasting section 4 and the soaking section 5 flows through the second dust removal device in turn 9. The SCR denitration device 10 flows into the extraction and drying section 2.

The active coke unit includes an active coke reaction tower 12 and an active coke regeneration tower 13; the mixed flue gas generated by the extraction and drying section 2 and the preheating section 3 flows through the third dust removal device 11, the active coke reaction tower 12 and the third dust removal device in sequence. Four dust removal devices 14 are discharged through the chimney 15 . The activated coke saturated with adsorption in the activated coke reaction tower 12 is desorbed and regenerated in the activated coke regeneration tower 13, and the regenerated activated coke is transported from the activated coke regeneration tower 13 to the activated coke reaction tower 12 for adsorption, denitration and desulfurization.

Further, the first dust removal device 8 includes any one or a combination of at least two of an electrostatic precipitator, a cyclone precipitator or a bag filter, preferably an electrostatic precipitator.

Further, the second dust removal device 9 includes any one or a combination of at least two of an electrostatic precipitator, a cyclone dust collector or a bag filter, preferably a cyclone dust collector.

Further, the third dust removal device 11 includes any one or a combination of at least two of an electrostatic precipitator, a cyclone precipitator or a bag filter, preferably an electrostatic precipitator.

Further, the fourth dust removal device 14 includes any one or a combination of at least two of an electrostatic precipitator, a cyclone dust collector or a bag filter, preferably a bag filter.

The matching gas conveying device includes, but is not limited to, a blower and/or an induced draft fan, and those skilled in the art can reasonably select the model and installation position of the gas conveying device according to the flow direction of the gas. The external cooling source is a gas with a relatively low temperature, preferably air.

The belt-type pellet roasting flue gas SCR and activated coke combined denitration and desulfurization system uses coke oven gas as fuel, and the coke oven gas is injected into the belt roaster by a coke oven gas burner with an automatic adjustment device, so as to facilitate the adjustment of each section roasting temperature.

Example 1

This embodiment provides a preferred technical solution of the belt-type pellet roasting flue gas SCR and activated coke combined denitration and desulfurization system according to the present invention, including a belt-type roasting unit, an SCR denitration device 10, an activated coke unit, a dust removal unit and a chimney 15.

The dedusting unit includes a first dedusting device 8 , a second dedusting device 9 , a third dedusting device 11 and a fourth dedusting device 14 .

The belt roasting unit includes a belt roasting machine and a matching gas conveying device. The belt roasting machine includes a blast drying section 1, a suction drying section 2, a preheating section 3, a roasting section 4, and a soaking section arranged in sequence. Section 5, first cooling section 6 and second cooling section 7.

The gas conveying device transports the external cold source to the first cooling section 6 and the second cooling section 7 independently; the hot exhaust gas of the second cooling section 7 flows through the blast drying section 1 and the first dust removal device 8 in sequence, and then flows into the first cooling section 6 and the second cooling section 7. The chimney 15 is discharged outside; the hot waste gas of the first cold section 6 flows into the preheating section 3, the roasting section 4 and the soaking section 5 independently; the flue gas generated by the roasting section 4 and the soaking section 5 flows through the second dust removal in turn The device 9 and the SCR denitration device 10 flow into the extraction and drying section 2 after that.

The active coke unit includes an active coke reaction tower 12 and an active coke regeneration tower 13; the mixed flue gas generated by the extraction and drying section 2 and the preheating section 3 flows through the third dust removal device 11, the active coke reaction tower 12 and the third dust removal device in sequence. The four dust removal devices 14 then flow into the chimney 15 for discharge. The activated coke saturated with adsorption in the activated coke reaction tower 12 is desorbed and regenerated in the activated coke regeneration tower 13, and the regenerated activated coke is transported from the activated coke regeneration tower 13 to the activated coke reaction tower 12 for adsorption, denitration and desulfurization.

The first dust removal device 8 is an electrostatic precipitator; the second dust removal device 9 is a cyclone dust collector; the third dust removal device 11 is an electrostatic precipitator; and the fourth dust removal device 14 is a bag filter.

The matching gas conveying device includes, but is not limited to, a blower and/or an induced draft fan, and those skilled in the art can reasonably select the model and installation position of the gas conveying device according to the flow direction of the gas. The external cooling source is a gas with a relatively low temperature, preferably air.

The belt-type pellet roasting flue gas SCR and activated coke combined denitration and desulfurization system uses coke oven gas as fuel, and the coke oven gas is injected into the belt roaster by a coke oven gas burner with an automatic adjustment device, so as to facilitate the adjustment of each section roasting temperature.

Application example 1

This application example provides a method for flue gas treatment by applying the belt pellet roasting flue gas SCR and activated coke combined denitration and desulfurization system provided in Example 1, including the following steps:

(1) The hot waste gas flowing through the second cooling section of the blast drying section 1 is dedusted and discharged through the chimney 15;

(2) The mixed flue gas generated by the roasting section 4 and the soaking section 5 is subjected to dedusting treatment and SCR denitration treatment in turn, and then flows into the extraction and drying section 2; the mixed flue gas generated by the extraction and drying section 2 and the preheating section 3 is sequentially subjected to dedusting treatment , activated coke denitration and desulfurization treatment and dust removal treatment are discharged through the chimney 15; the adsorption saturated activated coke generated after the activated coke denitration and desulfurization treatment is desorbed and reused to the activated coke reaction tower 12;

Step (1) and step (2) are in no particular order;

The SCR denitration treatment described in step (2) is to use NH ₃ to carry out SCR denitration treatment, and the molar ratio of NH ₃ to the mixed flue gas produced _by the roasting section 4 and the soaking section 5 is 1:1;

The iron-containing dust captured by the dedusting treatment in step (2) is recycled back to the belt roaster for reuse.

Use the infrared flue gas analyzer MGA6 to measure the concentration of nitrogen oxides, sulfur oxides and particulate matter in the external exhaust gas, the concentration of NO _{x ≤} 18mg/Nm ³ , the concentration of SO ₂ ≤ 15mg/Nm ³ and the concentration of particulate matter ≤ 6mg /Nm ³ .

Application example 2

This application example provides a method for flue gas treatment by applying the belt pellet roasting flue gas SCR and activated coke combined denitration and desulfurization system provided in Example 1, including the following steps:

(1) The hot waste gas flowing through the second cooling section of the blast drying section 1 is dedusted and discharged through the chimney 15;

(2) The mixed flue gas generated by the roasting section 4 and the soaking section 5 is subjected to dedusting treatment and SCR denitration treatment in turn, and then flows into the extraction and drying section 2; the mixed flue gas generated by the extraction and drying section 2 and the preheating section 3 is sequentially subjected to dedusting treatment , activated coke denitration and desulfurization treatment and dust removal treatment are discharged through the chimney 15; the adsorption saturated activated coke generated after the activated coke denitration and desulfurization treatment is desorbed and reused to the activated coke reaction tower 12;

Step (1) and step (2) are in no particular order;

The SCR denitration treatment described in step (2) is to use NH ₃ for SCR denitration treatment, and the molar ratio of NH ₃ to the mixed flue gas produced _by the roasting section 4 and the soaking section 5 is 1.5:1;

The iron-containing dust captured by the dedusting treatment in step (2) is recycled back to the belt roaster for reuse.

Use the infrared flue gas analyzer MGA6 to measure the concentration of nitrogen oxides, sulfur oxides and particulate matter in the external exhaust gas, the concentration of NO _{x ≤} 10mg/Nm ³ , the concentration of SO ₂ ≤ 11mg/Nm ³ and the concentration of particulate matter ≤ 6mg /Nm ³ .

Application example 3

This application example provides a method for flue gas treatment by applying the belt pellet roasting flue gas SCR and activated coke combined denitration and desulfurization system provided in Example 1, including the following steps:

(1) The hot waste gas flowing through the second cooling section of the blast drying section 1 is dedusted and discharged through the chimney 15;

(2) The mixed flue gas generated by the roasting section 4 and the soaking section 5 is subjected to dedusting treatment and SCR denitration treatment in turn, and then flows into the extraction and drying section 2; the mixed flue gas generated by the extraction and drying section 2 and the preheating section 3 is sequentially subjected to dedusting treatment , activated coke denitration and desulfurization treatment and dust removal treatment are discharged through the chimney 15; the adsorption saturated activated coke generated after the activated coke denitration and desulfurization treatment is desorbed and reused to the activated coke reaction tower 12;

Step (1) and step (2) are in no particular order;

The SCR denitration treatment described in step (2) is to use NH ₃ for SCR denitration treatment, and the molar ratio of NH ₃ to the mixed flue gas produced _by the roasting section 4 and the soaking section 5 is 0.8:1;

The iron-containing dust captured by the dedusting treatment in step (2) is recycled back to the belt roaster for reuse.

Use the infrared flue gas analyzer MGA6 to measure the concentration of nitrogen oxides, sulfur oxides and particulate matter in the external exhaust gas, the concentration of NO _{x ≤} 18mg/Nm ³ , the concentration of SO ₂ ≤ 20mg/Nm ³ and the concentration of particulate matter ≤ 6mg /Nm ³ .

To sum up, the combined denitration and desulfurization system and method of the belt-type pellet roasting flue gas SCR and activated coke provided by the present invention can not only significantly reduce the concentration of pollutants in the pellet roasting flue gas, but also reduce the operating cost of the equipment , and the device is easy to operate, and can realize long-term stable and low-energy consumption operation.

The applicant declares that the above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should Changes or substitutions that can be easily conceived within the technical scope all fall within the protection scope and disclosure scope of the present invention.

Claims (10)

1. a belt type pellet roasting flue gas SCR and active coke combined denitration and desulfurization system, it is characterized in that, described system comprises belt type roasting unit, SCR denitrification device, active coke unit and dust removal unit; The dedusting unit includes a first dedusting device, a second dedusting device, a third dedusting device and a fourth dedusting device; The belt roasting unit includes a belt roaster and a matching gas conveying device, and the belt roaster includes a blast drying section, a suction drying section, a preheating section, a roasting section, a soaking section, a Cold section and secondary cold section; The gas conveying device conveys the external cooling source to the first cooling section and the second cooling section independently; The hot exhaust gas of the second cooling section flows through the blast drying section and the first dust removal device in sequence, and is discharged through the chimney; The hot exhaust gas in the first cold section flows into the preheating section, the roasting section and the soaking section independently; the mixed flue gas generated in the roasting section and soaking section flows through the second dust removal device and the SCR denitration device in sequence, and then flows into the extraction and drying section. ; The mixed flue gas generated by the extraction and drying section and the preheating section flows through the third dust removal device, the active coke unit and the fourth dust removal device in sequence, and is discharged through the chimney. 2 . The combined denitration and desulfurization system of belt-type pellet roasting flue gas SCR and activated coke according to claim 1, characterized in that, the fuel used in the belt-type roasting machine is coke oven gas. 3. The combined denitration and desulfurization system of belt-type pellet roasting flue gas SCR and activated coke according to claim 1 or 2, wherein the first dust removal device comprises an electrostatic precipitator, a cyclone dust collector or a bag filter any one or a combination of at least two; Preferably, the second dust removal device includes any one or a combination of at least two of an electrostatic precipitator, a cyclone dust collector or a bag filter; Preferably, the third dust removal device comprises any one or a combination of at least two of an electrostatic precipitator, a cyclone dust collector or a bag filter; Preferably, the fourth dust removal device includes any one or a combination of at least two of an electrostatic precipitator, a cyclone or a bag filter. 4. The belt-type pellet roasting flue gas SCR and activated coke combined denitration and desulfurization system according to claim 3, wherein the first dust removal device is an electrostatic precipitator; Preferably, the second dust removal device is a cyclone dust collector; Preferably, the third dust removal device is an electrostatic precipitator; Preferably, the fourth dust removal device is a bag filter. 5. The combined denitration and desulfurization system of belt pellet roasting flue gas SCR and activated coke according to any one of claims 1-4, wherein the activated coke unit comprises an activated coke reaction tower and an activated coke regeneration tower; The mixed flue gas generated by the extraction and drying section and the preheating section flows through the third dust removal device, the active coke reaction tower and the fourth dust removal device in sequence, and is discharged through the chimney. 6. A method for treating the belt-type pellet roasting flue gas by applying the belt-type pellet roasting flue gas SCR and active coke combined denitration and desulfurization system according to any one of claims 1-5, wherein the The method includes the following steps: (1) The hot waste gas flowing through the second cooling section of the blast drying section is dedusted and discharged through the chimney; (2) The mixed flue gas generated in the roasting section and the soaking section is subjected to dedusting treatment and SCR denitration treatment in sequence, and the denitrified flue gas flows into the extraction and drying section; Activated coke denitration and desulfurization treatment and dust removal treatment are discharged through the chimney; Step (1) and step (2) are in no particular order. 7. The method according to claim 6, wherein the SCR denitration treatment in step (2) is to use NH ₃ for SCR denitration treatment, and NO _x in the mixed flue gas generated by NH ₃ and the roasting section and the soaking section The molar ratio of (0.8-1.5):1. 8 . The method according to claim 7 , wherein the molar ratio of NH ₃ to NO _x in the mixed flue gas produced by the roasting section and the soaking section is (0.9-1.1):1. 9 . 9. The method according to any one of claims 6-8, characterized in that, the method further comprises the step of reusing the adsorbed saturated activated coke generated after the activated coke denitration and desulfurization treatment and desorbed and reused it to the activated coke denitration and desulfurization treatment. 10. The method according to any one of claims 7-9, wherein the method comprises the steps of: (1) The hot waste gas flowing through the second cooling section of the blast drying section is dedusted and discharged through the chimney; (2) The mixed flue gas generated in the roasting section and the soaking section is subjected to dedusting treatment and SCR denitration treatment in sequence, and the denitrified flue gas flows into the extraction and drying section; Activated coke denitrification and desulfurization treatment and dust removal treatment are discharged through the chimney; the adsorption saturated activated coke generated after activated coke denitration and desulfurization treatment is desorbed and reused to the activated coke reaction tower; Step (1) and step (2) are in no particular order; The SCR denitration treatment in step (2) is to use _NH3 for SCR denitration treatment, and the molar ratio of _NH3 to _NOx in the mixed flue gas generated in the roasting section and the soaking section is (0.8-1.5):1.

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