CN115845588A

CN115845588A - SNCR + preposed temperature-rise-free high-temperature SCR denitration system applied to rotary kiln of chain grate machine

Info

Publication number: CN115845588A
Application number: CN202211530250.7A
Authority: CN
Inventors: 张现花; 董建彬; 李凌洁; 李红玲; 邹杨; 许丽莎
Original assignee: Zhongrui Engineering Design Institute Co ltd
Current assignee: Zhongrui Engineering Design Institute Co ltd
Priority date: 2022-12-01
Filing date: 2022-12-01
Publication date: 2023-03-28

Abstract

The invention relates to the technical field of an SNCR + preposed temperature-rise-free high-temperature SCR denitration system of a chain grate rotary kiln, and discloses an SNCR + preposed temperature-rise-free high-temperature SCR denitration system applied to the chain grate rotary kiln, wherein flue gas of pellet flue gas subjected to SCR denitration reaction enters the SNCR system for denitration, and the SNCR denitration reaction can fully utilize a denitration reducing agent injector connected with SCR, so that ammonia escape is reduced, and the denitration efficiency is improved; the SNCR system in the combined system for denitration and active coke desulfurization of the pellet flue gas of the grate rotary kiln provided stretches the denitration reducing agent injector into the flue gas outlet and the chute of the drying section I and sprays the reducing agent for denitration, and the denitration reducing agent injector is combined with the SCR system for use, so that the requirement of ultra-clean emission can be met, and the investment cost and the operation cost of the denitration system can be obviously reduced; set up first SCR denitration unit, the flue gas temperature is high and need not to heat the flue gas, and catalyst activity is good, the system is simple and the reliability is high, can reduce the catalyst quantity and can satisfy ultralow emission standard.

Description

SNCR + preposed temperature-rise-free high-temperature SCR denitration system applied to rotary kiln of chain grate machine

Technical Field

The invention relates to the technical field of SNCR and SCR denitration systems of a rotary kiln of a chain grate machine, in particular to an SNCR + preposed temperature-rise-free high-temperature SCR denitration system applied to the rotary kiln of the chain grate machine.

Background

The steel industry, as an important part of the national industry, produces NOx second in total in fixed sources, second only to SO2 emissions. Wherein, the NOx emission amount in the sintering and pelletizing processes is about half of the total NOx emission amount of the steel plant. The environmental protection department of 6 months in 2017 issues a amendment request draft of the emission standard of atmospheric pollutants for the steel sintering and pellet industry (GB 28662-2012), and the limit of nitrogen oxides is required to be adjusted from 300mg/m3 to 100mg/m3. As the national environmental protection policy becomes stricter, the denitration during sintering and pelletizing is imperative.

At present, the mature flue gas denitration technology mainly adopts a selective non-catalytic reduction (SNCR) method and a Selective Catalytic Reduction (SCR) method, and in addition, the flue gas denitration technology also adopts a liquid phase oxidation method, an electron beam method, a pulse corona method, a complex oxidation method, an organic catalysis method and the like, but most of the flue gas denitration technologies are in a test stage and have no mature industrial application yet.

The existing pellet flue gas denitration and desulfurization process is high in cost and low in efficiency, so that a high-efficiency and low-cost pellet flue gas SNCR/SCR denitration and active coke desulfurization combined system needs to be designed, and an SNCR + front-mounted temperature-rise-free high-temperature SCR denitration system applied to a grate rotary kiln is provided on the basis.

Disclosure of Invention

The invention aims to provide an SNCR + preposed temperature-rise-free high-temperature SCR denitration system applied to a rotary kiln of a chain grate machine, which solves the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme: the utility model provides a be applied to SNCR + leading high temperature SCR deNOx systems that exempts from to heat up of chain grate rotary kiln, includes deNOx systems, preheats I section, preheats II section, dry I section, dry II section, SNCR system and SCR system, its characterized in that: the denitration system comprises a chain grate, a rotary kiln and a ring cooling machine which are connected in sequence, wherein the chain grate is used for drying and preheating green pellets and conveying the green pellets to the rotary kiln for roasting, the rotary kiln is used for roasting the dried and preheated pellets, and the ring cooling machine is used for cooling the roasted pellets; the rotary kiln is also circularly connected with a chain grate through a flue gas return pipeline, and a selective non-catalytic reduction device is arranged on the flue gas return pipeline; the chain grate is sequentially connected with an ozone generating device and a desulfurizing device along the flow direction of roasting flue gas;

the flue gas inlet of the SCR system is communicated with one side of the drying I section close to the rotary kiln; the flue gas outlet of the drying I section is communicated with a denitration reducing agent injector of the SNCR system; the flue gas outlet of the SNCR system is communicated with the flue gas inlet of the drying section II; and the flue gas outlet of the drying section II and the flue gas outlet of the preheating section I are communicated with the flue gas inlet of the active coke desulfurization adsorption tower, and the purified flue gas outlet of the active coke desulfurization adsorption tower is communicated with a chimney.

Preferably, the chain grate is divided into a blast drying section, an air draft drying section, a medium temperature preheating section and a high temperature preheating section along the feeding direction of the pellets; a pellet inlet and a flue gas outlet are formed in one end, close to the chain grate, of the rotary kiln, a fuel inlet is formed in one end, far away from the chain grate, of the rotary kiln, and pellets are in reverse contact with fuel in the rotary kiln; introducing fuel and a combustion improver into the fuel inlet; the flue gas outlet is circularly connected with the top inlet of the high-temperature preheating section through a flue gas return pipeline; a selective non-catalytic reduction device is arranged on the flue gas return pipeline, and roasting flue gas generated in the rotary kiln enters a high-temperature preheating section after being treated by the selective non-catalytic reduction device; the bottom outlet of the high-temperature preheating section is connected with the top inlet of the air draft drying section through a flue gas circulating pipeline; a dust removal device and a flue gas circulating fan are sequentially arranged on the flue gas circulating pipeline along the flow direction of flue gas; the dust removal device is a cyclone dust collector.

Preferably, the flue gas outlet of the SCR system is communicated with the flue gas inlet of the drying I section through a heat-resistant fan; the device also comprises a regeneration tower, wherein a discharge hole of the regeneration tower is connected with an active coke feed inlet of the active coke desulfurization adsorption tower through a first chain bucket machine, and a feed inlet of the regeneration tower is connected with an active coke discharge hole of the active coke desulfurization adsorption tower through a second chain bucket machine; and a screening device is further arranged between the regeneration tower discharge port and the first chain bucket machine, the regeneration tower discharge port is communicated with a feed inlet of the screening device, and a qualified material outlet of the screening device is connected with the feed inlet of the first chain bucket machine.

Preferably, the denitration system comprises a first SCR denitration unit arranged at a flue gas outlet of a preheating section II of the chain grate and a second SCR denitration unit arranged at a flue gas outlet of a preheating section I of the chain grate, wherein the second SCR denitration unit further comprises a flue gas heating subunit.

Preferably, the first SCR denitration unit includes a first denitration flue, a first denitration reducing agent supply subunit, and a first SCR denitration reactor; a flue gas inlet of the first denitration flue is connected with a heat return fan, and a flue gas outlet of the first denitration flue is connected with the first SCR denitration reactor; the first denitration reducing agent supply subunit comprises a first denitration reducing agent storage container, a first denitration reducing agent conveying pipeline and a first denitration reducing agent injection grid arranged in a first denitration flue; the flue gas outlet of the first SCR denitration reactor is connected with the air draft drying section of the chain grate machine, and a first denitration catalyst is arranged in the first SCR denitration reactor.

Preferably, the second SCR denitration unit includes a second denitration flue, a flue gas heating subunit, a second denitration reducing agent supply subunit and a second SCR denitration reactor; a flue gas inlet of the second denitration flue is directly connected with a flue gas outlet of the preheating I section of the chain grate machine, and the flue gas outlet is connected with the second SCR denitration reactor; the flue gas heating subunit is arranged to heat flue gas entering the second denitration flue; the second denitration reducing agent supply subunit comprises a second denitration reducing agent storage container, a second denitration reducing agent conveying pipeline and a second denitration reducing agent injection grid arranged in a second denitration flue; and the flue gas outlet of the second SCR denitration reactor is sequentially connected with the main dust remover and the main exhaust fan, and a second denitration catalyst is arranged in the second SCR denitration reactor.

Preferably, the flue gas heating subunit is a hot blast stove, a burner with a built-in flue or high-temperature air in a denitration system.

Preferably, a screening device is further arranged between the discharge port of the regeneration tower and the first chain bucket machine, the discharge port of the regeneration tower is communicated with the feed port of the screening device, and a qualified material outlet of the screening device is connected with the feed port of the first chain bucket machine.

The invention provides an SNCR + preposed temperature-rise-free high-temperature SCR denitration system applied to a rotary kiln of a chain grate machine. The SNCR + preposed temperature-rise-free high-temperature SCR denitration system applied to the rotary kiln of the chain grate machine has the following structure

Has the advantages that:

1. flue gas after the chain grate rotary kiln pelletizing flue gas of this system setting is reacted through the SCR denitration gets into the SNCR system and carries out the denitration, and the denitration reductant sprayer that SNCR denitration reaction can make full use of SCR connects reduces ammonia escape, improves denitration efficiency.

2. The SNCR system among chain grate rotary kiln pelletizing flue gas SNCR/SCR denitration and active coke desulfurization combined system that this system provided stretches into flue gas outlet and the chute of dry I section with denitration reductant sprayer and spouts into the reductant and carry out the denitration, simple structure, with low costs, uses with the combination of SCR system, both can satisfy the ultra-clean emission requirement, can obviously reduce denitration system investment cost and running cost again.

3. The system is provided with the first SCR denitration unit, so that the flue gas temperature is high, the flue gas is not required to be heated, the catalyst activity is good, the investment and operation cost is low, the system is simple and high in reliability, the catalyst consumption can be reduced, and the ultralow emission standard can be met; through set up second SCR denitration unit and set up flue gas heating device preheating I section exhanst gas outlet, total gas consumption reduces and investment cost descends. The invention is provided with a plurality of sets of SCR denitration reactors, thereby facilitating batch management of the service life of the catalyst, being more flexible when the catalyst is replaced and indirectly reducing the operation cost.

Drawings

FIG. 1 is a schematic view of a pin removal system module of a rotary kiln of a chain grate machine according to the present invention;

FIG. 2 is a schematic view of the connection of the rotary kiln apparatus of the present invention;

FIG. 3 is a schematic view of a structural denitration system according to the present invention;

FIG. 4 is a schematic view of a first SCR denitration unit according to the present invention;

FIG. 5 is a schematic view of a second SCR denitration unit according to the present invention.

Detailed Description

As shown in fig. 1 to 5, the present invention provides a technical solution: an SNCR + front-mounted temperature-rise-free high-temperature SCR denitration system applied to a grate rotary kiln comprises a denitration system, a preheating I section, a preheating II section, a drying I section, a drying II section, an SNCR system and an SCR system, wherein the denitration system comprises a grate, a rotary kiln and a ring cooling machine which are sequentially connected, the grate is used for drying and preheating green pellets and conveying the green pellets to the rotary kiln for roasting, the rotary kiln is used for roasting the dried and preheated pellets, and the ring cooling machine is used for cooling the roasted pellets; the rotary kiln is also circularly connected with a chain grate through a flue gas return pipeline, and a selective non-catalytic reduction device is arranged on the flue gas return pipeline; the chain grate machine is sequentially connected with an ozone generating device and a desulfurizing device along the flow direction of roasting flue gas; the chain grate machine is divided into a blast drying section, an air draft drying section, a medium temperature preheating section and a high temperature preheating section along the feeding direction of the pellets; a pellet inlet and a flue gas outlet are formed in one end, close to the chain grate, of the rotary kiln, a fuel inlet is formed in one end, far away from the chain grate, of the rotary kiln, and pellets are in reverse contact with fuel in the rotary kiln; introducing fuel and a combustion improver into the fuel inlet; the flue gas outlet is circularly connected with the top inlet of the high-temperature preheating section through a flue gas return pipeline; a selective non-catalytic reduction device is arranged on the flue gas return pipeline, and roasting flue gas generated in the rotary kiln enters a high-temperature preheating section after being treated by the selective non-catalytic reduction device; the bottom outlet of the high-temperature preheating section is connected with the top inlet of the air draft drying section through a flue gas circulation pipeline; a dust removal device and a flue gas circulating fan are sequentially arranged on the flue gas circulating pipeline along the flow direction of flue gas; the dust removing device is a cyclone dust remover; the flue gas inlet of the SCR system is communicated with one side of the drying section I, which is close to the rotary kiln; the flue gas outlet of the drying I section is communicated with a denitration reducing agent injector of the SNCR system; a flue gas outlet of the SNCR system is communicated with a flue gas inlet of the drying section II; the flue gas outlet of the drying section II and the flue gas outlet of the preheating section I are both communicated with the flue gas inlet of the active coke desulfurization adsorption tower, and the purified flue gas outlet of the active coke desulfurization adsorption tower is communicated with a chimney; the flue gas heating subunit is a hot blast stove, a flue built-in burner or high-temperature air in a denitration system; the flue gas outlet of the SCR system is communicated with the flue gas inlet of the drying section I through a heat-resistant fan; the device also comprises a regeneration tower, wherein a discharge hole of the regeneration tower is connected with an active coke feed inlet of the active coke desulfurization adsorption tower through a first chain bucket machine, and a feed inlet of the regeneration tower is connected with an active coke discharge hole of the active coke desulfurization adsorption tower through a second chain bucket machine; a screening device is also arranged between the discharge port of the regeneration tower and the first chain bucket machine, the discharge port of the regeneration tower is communicated with the feed port of the screening device, and the qualified material outlet of the screening device is connected with the feed port of the first chain bucket machine; the denitration system comprises a first SCR denitration unit arranged at a flue gas outlet of the preheating section II of the chain grate and a second SCR denitration unit arranged at a flue gas outlet of the preheating section I of the chain grate, wherein the second SCR denitration unit also comprises a flue gas heating subunit; the first SCR denitration unit comprises a first denitration flue, a first denitration reducing agent supply subunit and a first SCR denitration reactor; a flue gas inlet of the first denitration flue is connected with the heat return fan, and a flue gas outlet of the first denitration flue is connected with the first SCR denitration reactor; the first denitration reducing agent supply subunit comprises a first denitration reducing agent storage container, a first denitration reducing agent conveying pipeline and a first denitration reducing agent injection grid arranged in the first denitration flue; a flue gas outlet of the first SCR denitration reactor is connected with an air draft drying section of the chain grate, and a first denitration catalyst is arranged in the first SCR denitration reactor; the second SCR denitration unit comprises a second denitration flue, a flue gas heating subunit, a second denitration reducing agent supply subunit and a second SCR denitration reactor; a flue gas inlet of the second denitration flue is directly connected with a flue gas outlet of the preheating I section of the chain grate machine, and the flue gas outlet is connected with the second SCR denitration reactor; the flue gas heating subunit is arranged to heat flue gas entering the second denitration flue; the second denitration reducing agent supply subunit comprises a second denitration reducing agent storage container, a second denitration reducing agent conveying pipeline and a second denitration reducing agent injection grid arranged in the second denitration flue; a flue gas outlet of the second SCR denitration reactor is sequentially connected with the main dust remover and the main exhaust fan, and a second denitration catalyst is arranged in the second SCR denitration reactor; and a screening device is also arranged between the discharge port of the regeneration tower and the first chain bucket machine, the discharge port of the regeneration tower is communicated with the feed port of the screening device, and the qualified material outlet of the screening device is connected with the feed port of the first chain bucket machine.

In the actual application process of the SNCR + preposed temperature-rise-free high-temperature SCR denitration system applied to the grate rotary kiln, pellet materials are conveyed to the rotary kiln after being dried and preheated by the grate, the pellet materials are in countercurrent contact with fuel for roasting, generated roasting smoke is treated by a selective non-catalytic reduction device and then flows back to a high-temperature preheating section, the pellet materials conveyed into the high-temperature preheating section are preheated, discharged roasting smoke after the preheating is returned to an air draft drying section, and the pellet materials conveyed to the air draft drying section are dried; conveying the pellets after being baked to a cold ring machine, conveying a heat exchange medium into the first cold ring section, and discharging the heat exchange medium and the pellets after heat exchange and temperature rise to a rotary kiln to participate in baking the pellets; conveying a heat exchange medium into the second cold ring section, discharging the heat exchange medium and the pellets after heat exchange and temperature rise to a medium-temperature preheating section to participate in preheating the pellets, mixing the heat exchange medium discharged out of the medium-temperature heat exchange section with the roasting flue gas discharged out of the exhaust drying section after preheating is finished, and emptying the mixture after dust removal, ozone oxidation and desulfurization treatment in sequence; and conveying a heat exchange medium into the third cold ring section, discharging the heat exchange medium and the pellets after heat exchange and temperature rise to a blast drying section to participate in drying of the pellets, emptying the heat exchange medium discharged from the blast drying section through a chimney after drying is finished, conveying the generated active coke which is adsorbed and saturated in the middle active coke desulfurization adsorption tower to a regeneration tower through a second chain bucket machine for regeneration, screening the regenerated active coke through screening equipment, and conveying the qualified active coke to the active coke desulfurization adsorption tower through a first chain bucket machine.

Claims

1. The utility model provides a be applied to SNCR + leading high temperature SCR deNOx systems that exempts from to heat up of chain grate rotary kiln, includes deNOx systems, preheats I section, preheats II section, dry I section, dry II section, SNCR system and SCR system, its characterized in that: the denitration system comprises a chain grate, a rotary kiln and a ring cooling machine which are sequentially connected, wherein the chain grate is used for drying and preheating green pellets and conveying the green pellets to the rotary kiln for roasting, the rotary kiln is used for roasting the dried and preheated pellets, and the ring cooling machine is used for cooling the roasted pellets; the rotary kiln is also circularly connected with a chain grate through a flue gas return pipeline, and a selective non-catalytic reduction device is arranged on the flue gas return pipeline; the chain grate is sequentially connected with an ozone generating device and a desulfurizing device along the flow direction of roasting flue gas;

the SCR system flue gas inlet is communicated with one side of the drying section I, which is close to the rotary kiln; the flue gas outlet of the drying I section is communicated with a denitration reducing agent injector of the SNCR system; the flue gas outlet of the SNCR system is communicated with the flue gas inlet of the drying section II; and the flue gas outlet of the drying section II and the flue gas outlet of the preheating section I are both communicated with the flue gas inlet of the active coke desulfurization adsorption tower, and the purified flue gas outlet of the active coke desulfurization adsorption tower is communicated with a chimney.

2. The SNCR + preposed temperature-rise-free high-temperature SCR denitration system applied to the rotary kiln of the chain grate machine as recited in claim 1, which is characterized in that: the chain grate machine is divided into a blast drying section, an air draft drying section, a medium temperature preheating section and a high temperature preheating section along the feeding direction of the pellets; a pellet inlet and a flue gas outlet are formed in one end, close to the chain grate, of the rotary kiln, a fuel inlet is formed in one end, far away from the chain grate, of the rotary kiln, and pellets are in reverse contact with fuel in the rotary kiln; introducing fuel and a combustion improver into the fuel inlet; the flue gas outlet is circularly connected with the top inlet of the high-temperature preheating section through a flue gas return pipeline; a selective non-catalytic reduction device is arranged on the flue gas return pipeline, and roasting flue gas generated in the rotary kiln enters a high-temperature preheating section after being treated by the selective non-catalytic reduction device; the bottom outlet of the high-temperature preheating section is connected with the top inlet of the air draft drying section through a flue gas circulating pipeline; a dust removal device and a flue gas circulating fan are sequentially arranged on the flue gas circulating pipeline along the flow direction of flue gas; the dust removal device is a cyclone dust collector.

3. The SNCR + preposed temperature-rise-free high-temperature SCR denitration system applied to the rotary kiln of the chain grate machine as recited in claim 1, which is characterized in that: the flue gas outlet of the SCR system is communicated with the flue gas inlet of the drying I section through a heat-resistant fan; the device also comprises a regeneration tower, wherein a discharge hole of the regeneration tower is connected with an active coke feed inlet of the active coke desulfurization adsorption tower through a first chain bucket machine, and a feed inlet of the regeneration tower is connected with an active coke discharge hole of the active coke desulfurization adsorption tower through a second chain bucket machine; and a screening device is further arranged between the regeneration tower discharge port and the first chain bucket machine, the regeneration tower discharge port is communicated with a feed inlet of the screening device, and a qualified material outlet of the screening device is connected with the feed inlet of the first chain bucket machine.

4. The SNCR + preposed temperature-rise-free high-temperature SCR denitration system applied to the rotary kiln of the chain grate machine as recited in claim 1, which is characterized in that: the denitration system comprises a first SCR denitration unit arranged at a chain grate preheating section II flue gas outlet and a second SCR denitration unit arranged at a chain grate preheating section I flue gas outlet, wherein the second SCR denitration unit further comprises a flue gas heating subunit.

5. The SNCR + preposed temperature-rise-free high-temperature SCR denitration system applied to the rotary kiln of the chain grate machine as claimed in claim 4, wherein: the first SCR denitration unit comprises a first denitration flue, a first denitration reducing agent supply subunit and a first SCR denitration reactor; a flue gas inlet of the first denitration flue is connected with a heat return fan, and a flue gas outlet of the first denitration flue is connected with the first SCR denitration reactor; the first denitration reducing agent supply subunit comprises a first denitration reducing agent storage container, a first denitration reducing agent conveying pipeline and a first denitration reducing agent injection grid arranged in a first denitration flue; the flue gas outlet of the first SCR denitration reactor is connected with the air draft drying section of the chain grate machine, and a first denitration catalyst is arranged in the first SCR denitration reactor.

6. The SNCR + preposed temperature-rise-free high-temperature SCR denitration system applied to the rotary kiln of the chain grate machine as claimed in claim 4, wherein: the second SCR denitration unit comprises a second denitration flue, a flue gas heating subunit, a second denitration reducing agent supply subunit and a second SCR denitration reactor; a flue gas inlet of the second denitration flue is directly connected with a flue gas outlet of the preheating I section of the chain grate machine, and the flue gas outlet is connected with the second SCR denitration reactor; the flue gas heating subunit is arranged to heat flue gas entering the second denitration flue; the second denitration reducing agent supply subunit comprises a second denitration reducing agent storage container, a second denitration reducing agent conveying pipeline and a second denitration reducing agent injection grid arranged in a second denitration flue; and a flue gas outlet of the second SCR denitration reactor is sequentially connected with the main dust remover and the main exhaust fan, and a second denitration catalyst is arranged in the second SCR denitration reactor.

7. The SNCR + preposed temperature-rise-free high-temperature SCR denitration system applied to the rotary kiln of the chain grate machine as claimed in claim 4, wherein: the flue gas heating subunit is a hot blast stove, a flue built-in burner or high-temperature air in a denitration system.

8. The SNCR + preposed temperature-rise-free high-temperature SCR denitration system applied to the rotary kiln of the chain grate machine as claimed in claim 3, which is characterized in that: and a screening device is further arranged between the discharge port of the regeneration tower and the first chain bucket machine, the discharge port of the regeneration tower is communicated with the feed port of the screening device, and a qualified material outlet of the screening device is connected with the feed port of the first chain bucket machine.