CN-121977216-A - Coke oven flue gas purification system and method

CN121977216ACN 121977216 ACN121977216 ACN 121977216ACN-121977216-A

Abstract

The invention provides a coke oven flue gas purification system and method, wherein the purification system comprises a pretreatment unit, a heat storage incineration unit and an SCR (selective catalytic reduction) treatment unit which are sequentially arranged, the pretreatment unit is used for carrying out desulfurization treatment and dust removal treatment on coke oven flue gas to obtain first flue gas and conveying the first flue gas to the heat storage incineration unit, the heat storage incineration unit is used for carrying out preheating treatment, oxidation treatment and heat recovery treatment on the first flue gas to obtain second flue gas, and the SCR treatment unit is used for carrying out SCR denitration treatment on the second flue gas to obtain purified flue gas. According to the coke oven flue gas purification system and method provided by the invention, volatile organic compounds (such as NMHC) and combustible substances such as CO in the flue gas are efficiently oxidized and decomposed by the heat storage and incineration unit, and the flue gas is heated by heat generated by the oxidation and decomposition, so that the consumption of post-combustion gas is greatly reduced. The invention can not only stably meet the requirement that the NMHC emission concentration is not higher than 100mg/Nm 3 , but also reduce the energy consumption cost of the system.

Inventors

CUI KE
CHEN HUOHU
LI HONGXING
LI FENG

Assignees

宝武水务科技有限公司

Dates

Publication Date: 20260505
Application Date: 20260326

Claims (10)

1. The coke oven flue gas purification system is characterized by comprising a pretreatment unit, a heat storage incineration unit and an SCR treatment unit which are sequentially arranged; the pretreatment unit is used for carrying out desulfurization treatment and dust removal treatment on the coke oven flue gas to obtain first flue gas, and conveying the first flue gas to the heat storage incineration unit; the heat storage incineration unit is used for carrying out preheating treatment, oxidation treatment and heat recovery treatment on the first flue gas to obtain second flue gas; The SCR treatment unit is used for carrying out SCR denitration treatment on the second flue gas to obtain purified flue gas.
2. The coke oven flue gas cleaning system according to claim 1, wherein the pretreatment unit comprises a desulfurization device, a dust removal device and a flue gas conveying device which are sequentially connected, wherein the desulfurization device is used for desulfurizing the coke oven flue gas to obtain desulfurized flue gas, the dust removal device is used for conducting dust removal on the desulfurized flue gas to obtain the first flue gas, and the flue gas conveying device is used for conveying the first flue gas to the heat storage incineration unit.
3. The coke oven flue gas cleaning system of claim 2, wherein the flue gas delivery device comprises a booster fan.
4. The coke oven flue gas cleaning system of claim 1, wherein the thermal storage incineration unit comprises an oxidation chamber and a plurality of thermal storage chambers, the oxidation chamber is connected with a heating device, each thermal storage chamber is communicated with the oxidation chamber, and a thermal storage body is filled in each thermal storage chamber; The heating device is used for providing a heat source to enable the first flue gas entering the oxidation chamber to reach a preset oxidation temperature and perform oxidation reaction; The heat accumulator is used for alternately storing and releasing heat in the flue gas flowing process so as to preheat the first flue gas to be fed into the oxidation chamber and recover the heat of the first flue gas output from the oxidation chamber.
5. The coke oven flue gas cleaning system of claim 4, wherein the preset oxidation temperature range comprises 760 ℃ to 850 ℃.
6. The coke oven flue gas cleaning system of claim 4, further comprising a bypass attemperation unit comprising a bypass flue, a temperature controller, an attemperation valve mounted on the bypass flue, and a temperature sensor disposed within the oxidation chamber; one end of the bypass flue is connected to the oxidation chamber, and the other end of the bypass flue is connected to a discharge pipeline of the heat storage incineration unit; The temperature controller is respectively connected with the regulating valve and the temperature sensor, and is configured to control the regulating valve to be opened when the temperature sensor detects that the temperature in the oxidation chamber exceeds a preset over-temperature limit value, so that part of the first flue gas output from the oxidation chamber is bypassed to a discharge pipeline of the heat storage incineration unit through the bypass flue.
7. The coke oven flue gas cleaning system of claim 1, further comprising a heat supplementing unit disposed between the thermal storage incineration unit and the SCR treatment unit, the heat supplementing unit configured to activate to raise the temperature of the second flue gas when the temperature of the second flue gas is below a minimum active temperature of a catalyst in the SCR treatment unit.
8. The coke oven flue gas cleaning system according to claim 1, further comprising a waste heat recovery unit disposed between the heat storage incineration unit and the SCR treatment unit, wherein the second flue gas flows through the waste heat recovery unit for waste heat recovery to recover heat and reduce temperature, and then enters the SCR treatment unit.
9. A method for purifying coke oven flue gas, characterized in that the coke oven flue gas is treated with the coke oven flue gas purification system according to any one of claims 1 to 8, the method comprising: Desulfurizing and dedusting the coke oven flue gas to obtain first flue gas; Preheating, oxidizing and heat recovering the first flue gas to obtain second flue gas; and performing SCR denitration treatment on the second flue gas to obtain purified flue gas.
10. The coke oven fume cleaning method of claim 9, further comprising: when the first flue gas is subjected to preheating treatment, oxidation treatment and heat recovery treatment, monitoring the temperature in an oxidation chamber in real time, and when the temperature in the oxidation chamber is detected to exceed a preset over-temperature limit value, opening a regulating valve on a bypass flue so as to bypass part of the first flue gas output from the oxidation chamber to a discharge pipeline of a heat storage incineration unit through the bypass flue; after the second flue gas is obtained, detecting the temperature of the second flue gas; When the temperature of the second flue gas is lower than the lowest activity temperature of a catalyst in the SCR treatment unit, starting a heat supplementing unit to raise the temperature of the second flue gas; when the temperature of the second flue gas exceeds the highest limit value of the safe operation temperature of the SCR processing unit, the waste heat recovery unit is controlled to perform waste heat recovery so as to recover heat and reduce the temperature of the second flue gas, and then the second flue gas enters the SCR processing unit.

Description

Coke oven flue gas purification system and method Technical Field The invention relates to the technical field of chemical industry, in particular to a coke oven flue gas purification system and method. Background The coking chemical industry is an important coal energy conversion industry, the product coke of the coking chemical industry mainly supplies the steel industry, and the yield of Chinese coke is stable at the first place worldwide and accounts for about 70% of the total global yield. The coke oven chimney is an important atmospheric pollutant emission source in the coking industry, the temperature of the coke oven flue gas taking coke oven gas as fuel is higher, generally between 200 ℃ and 320 ℃, the initial concentration of nitrogen oxides is about 400mg/m 3~1500mg/m3, and the temperature of the coke oven flue gas taking blast furnace gas or mixed gas as fuel is lower, generally between 180 ℃ and 240 ℃, and the initial concentration of nitrogen oxides is about 300mg/m 3~600mg/m3. According to the opinion about ultra-low emission of the coking industry of advanced implementation and the emission standard of atmospheric pollutants of the coking chemical industry (GB 16171.1-2024) issued by the ecological environment department, the limit of the emission concentration of nitrogen oxides is explicitly specified to be 150mg/Nm 3. The existing exhaust gas denitration technology route mainly comprises an SCR (SELECTIVE CATALYTIC Reduction) technology, an activated carbon (coke) integrated technology, a catalytic oxidation technology and the like. Among them, the SCR technology is most widely used, and the proportion of enterprises adopting the technology is as high as 84%. However, since the temperature of the coke oven flue gas is reduced after desulfurization treatment, it is generally necessary to supplement the flue gas before entering the SCR denitration reactor in order to satisfy the temperature window required for the SCR reaction. At present, most of the heat is directly supplied by external fuel gas, so that the daily operation energy consumption cost of the coking industrial flue gas treatment facility is higher. In addition to nitrogen oxides, the non-methane total hydrocarbon (NMHC) emissions from coke oven stacks in the two documents are also mandatory to require that the non-methane total hydrocarbon emissions concentration be no higher than 100mg/Nm 3 from 2027 to 1, and from 2025 to 4 to 1. However, in the prior art, the end treatment of non-methane total hydrocarbons in coke oven flue gas is still in a blank state. The existing treatment means mainly depend on source control (such as sealing, grouting and the like), but the treatment efficiency of the old coke oven is less than 60%, and the requirements that the total non-methane hydrocarbon emission concentration is not higher than 100mg/Nm 3 are difficult to stably meet. In summary, the prior art has the main defects that part of enterprises cannot reach standards due to the lack of an efficient and stable coke oven flue gas non-methane total hydrocarbon tail end treatment technology and face survival challenges, and the existing SCR denitration technology relies on external fuel gas to supplement heat, so that the energy consumption cost is high. Therefore, a new technology for effectively reducing the emission concentration of non-methane total hydrocarbons and optimizing the energy consumption cost of a denitration system is needed. Disclosure of Invention The invention aims to provide a coke oven flue gas purification system and a method, which are used for solving one or more problems that the coke oven flue gas purification technology in the prior art is difficult to stably meet the requirements that the total non-methane hydrocarbon emission concentration is not higher than 100mg/Nm 3 and the energy consumption cost is higher. The coke oven flue gas purification system comprises a pretreatment unit, a heat storage incineration unit and an SCR treatment unit which are sequentially arranged, wherein the pretreatment unit is used for carrying out desulfurization treatment and dust removal treatment on coke oven flue gas to obtain first flue gas and conveying the first flue gas to the heat storage incineration unit, the heat storage incineration unit is used for carrying out preheating treatment, oxidation treatment and heat recovery treatment on the first flue gas to obtain second flue gas, and the SCR treatment unit is used for carrying out SCR denitration treatment on the second flue gas to obtain purified flue gas. Optionally, the pretreatment unit comprises a desulfurization device, a dust removal device and a flue gas conveying device which are sequentially connected, wherein the desulfurization device is used for desulfurizing the coke oven flue gas to obtain desulfurized flue gas, the dust removal device is used for conducting dust removal on the desulfurized flue gas to obtain the first flue gas, and the flue gas conveyi