Denitration device for reducing fuel consumption of low-temperature flue gas catalytic denitration

Abstract

The utility model discloses a denitration device and method for reducing fuel consumption of low-temperature flue gas catalytic denitration, and the denitration device comprises a desulfurization device, a dust remover, an SCR (Selective Catalytic Reduction) reactor, an induced draft fan and a chimney which are sequentially communicated through flues, and heat exchangers are arranged on the flues at the input end and the output end of the SCR reactor; a heat exchanger is arranged at the input end of the SCR reactor, a hot blast stove and a reducing agent spraying device are sequentially arranged on a flue between the heat exchanger and the input end of the SCR reactor, and a CO oxidation catalyst and a plurality of denitration catalysts located above the CO oxidation catalyst are arranged in the SCR reactor. According to the low-temperature flue gas SCR denitration device, NOx and CO up-to-standard emission of sintering flue gas, steel rolling flue gas and the like which are relatively low in temperature of iron and steel enterprises can be continuously and stably achieved, the requirement of SCR denitration for flue gas temperature rising can be met, fuel consumption of a hot blast stove is reduced, and the low-temperature flue gas SCR denitration operation cost is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of environmental protection technology equipment, especially a denitration device of reducing low-temperature flue gas catalytic denitration fuel consumption. BACKGROUND

[0002] China is the world's largest steel producer, and in steel enterprises, coking, ironmaking and steelmaking processes are supported, and at the same time, flue gas pollution is also generated, including dust, SO2, NO X x, CO, etc. In June 2019, the five ministries and commissions jointly issued the "Opinions on Promoting the Implementation of Ultra-Low Emission in the Steel Industry", which stipulates that the NOx generated by steel enterprises needs to reach 50 mg / m 3 The following ultra-low emission standard; in addition, due to the influence of raw materials, fuel and carbon content in steel plants, a large amount of CO is contained in part of the flue gas, and its concentration is generally 6000~12000mg / m 3 , which accounts for about 50% of the emission amount of the steel plant, and the emission equivalent has a greater impact on the environmental air quality. In May 2023, the "Hebei Province Key Industry Environmental Protection Performance A-Grade Standard Steel Industry Long Process" issued by Hebei Province stipulates that in the organized emission control technology, the CO emission concentration is required to be not higher than 6000mg / m 3 Therefore, it is imperative to treat the existing steel emission pollution flue gas with ultra-low emission technology.

[0003] The existing SO2 treatment generated by steel enterprises generally adopts semi-dry and dry desulfurization technology, and the dust treatment adopts high-efficiency bag dust removal technology, and for the treatment of NO X , the selective catalytic reduction denitration technology SCR technology is adopted, and the mature denitration catalyst used today has a temperature window of 180~500℃, and has a higher denitration effect in the temperature range, if the flue gas temperature is lower than the minimum use temperature, then the method of external hot air is needed to continuously heat the flue gas before denitration to above 180℃, and the heating fuel used mainly has coke oven gas, blast furnace gas and converter gas, etc. For the treatment of NO X , most of the steel flue gas today has set up SCR denitration equipment, and a catalyst standby air layer is arranged in the reactor, and for the treatment of CO, it has not been popularized in the existing steel flue gas.

[0004] The mature denitration catalyst used in the present SCR denitration technology has a temperature window of 180-500 DEG C, and has high denitration effect in the temperature range, and is widely applied in the power industry, cement industry and other high-temperature flue gas purification treatment. Because the flue gas temperature meets the use requirement of the catalyst, the catalyst is placed in the flue gas to achieve the denitration effect. However, the flue gas temperature generated in some production processes of the steel industry such as sintering, rolling and coking is less than 180 DEG C. The denitration equipment is placed at the rear end of the wet desulfurization, and the flue gas temperature is lower, only about 50 DEG C, which belongs to the category of low-temperature flue gas denitration. In order to meet the minimum use temperature of the catalyst, the flue gas needs to be heated and warmed to 180 DEG C or more by using a hot blast furnace during denitration. The heating fuel mainly includes coke oven gas, blast furnace gas and converter gas, etc. However, due to the large flue gas volume, the heating heat required is huge, and the fuel consumption is high, which leads to high denitration operation cost. Taking a 430m 2 sintering flue gas treatment as an example, if the flue gas temperature is increased by 30 DEG C, and the blast furnace gas is used as the heat source, the annual consumption of the blast furnace gas fee can reach 15.5 million yuan. If the converter gas is used as the heat source, the annual consumption of the converter gas fee is higher, which can reach 42 million yuan. SUMMARY

[0005] The purpose of the utility model is to solve the problems in the prior art, and provide a denitration device and method for reducing fuel consumption of low-temperature flue gas catalytic denitration. The separate NOx removal equipment and CO removal equipment are combined together. The sintering flue gas and rolling flue gas with relatively low temperature of the steel enterprise can continuously and stably realize the standard emission of NOx and CO, can meet the needs of SCR denitration for flue gas warming, reduce the fuel consumption of the hot blast furnace, and reduce the operation cost of low-temperature flue gas SCR denitration.

[0006] In order to realize the above purpose, the utility model provides a kind of denitration device for reducing fuel consumption of low-temperature flue gas catalytic denitration, including desulfurization device, dust collector, SCR reactor, induced draft fan and chimney that are sequentially communicated by flue, the flue of the input end and the output end of the SCR reactor is equipped with heat exchanger, heat exchanger and the flue between the input end of SCR reactor are sequentially equipped with hot blast furnace and reducing agent injection device, CO oxidation catalyst and a plurality of denitration catalysts located above CO oxidation catalyst are equipped in the SCR reactor.

[0007] As preferred, the SCR reactor is provided with two or three layers of denitration catalysts arranged at intervals.

[0008] As preferred, the denitration catalyst and the CO oxidation catalyst are both in honeycomb type, and the number of holes of the catalyst is 25-35 holes.

[0009] As preferred, the removal of nitrogen oxides and CO can be simultaneously realized in the SCR reactor (1).

[0010] As preferred, the heat exchanger is a rotary heat exchanger, a plate heat exchanger or a tube heat exchanger, which transfers the large amount of chemical heat generated by the catalytic combustion of CO from the hot end to the cold end, and increases the temperature of the flue gas at the entrance of the SCR reactor by 15-35℃.

[0011] As preferred, the combustion fuel used by the hot blast furnace is coke oven gas, blast furnace gas or converter gas.

[0012] The beneficial effects of the present application are as follows:

[0013] 1. The separate NOx removal equipment and CO removal equipment are combined together, and the sintering flue gas and rolling flue gas with relatively low temperature in the steel enterprise can realize the continuous and stable standard emission of NOx and CO, and compared with other technologies, the present application has the following advantages: 1. The catalyst containing noble metal or non-noble metal is used to reduce the emission of CO pollutants in the flue gas through catalytic combustion;

[0014] 2. The catalyst used for removing CO can be arranged in the standby layer of the existing SCR denitration reactor, and the reactor and the bracket are shared, so that no other space is occupied, the investment is low, and the transformation period is short;

[0015] 3. When the CO is removed, a large amount of chemical heat is released through catalytic combustion, and the heat is transferred to the flue gas at the front end of the denitration through the heat exchanger after the temperature of the flue gas is increased, so that the heat energy is indirectly recycled, the need of the SCR denitration for the flue gas temperature increase is met, the fuel consumption of the hot blast furnace is reduced, and the operation cost of the low-temperature flue gas SCR denitration is reduced;

[0016] 4. The CO catalyst has a certain effect of removing NOx, and can cooperatively improve the SCR denitration efficiency and reduce the consumption of the denitration reducing agent;

[0017] 5. The oxygen in the flue gas is consumed when the CO is removed, so that the oxygen content in the flue gas is reduced, and after being converted by the standard oxygen, the emission of the flue gas is indirectly reduced.

[0018] The features and advantages of the present application will be described in detail with reference to the embodiments and the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a structure schematic view of a denitration device for reducing the fuel consumption of low-temperature flue gas catalytic denitration.

[0020] In the figure: 1-SCR reactor, 2-de-nitration catalyst, 3-CO oxidation catalyst, 4-heat exchanger, 5-draught fan, 6-chimney, 7-hot blast stove, 8-reducing agent injection device, 9-flue, 10-desulfurization device, 11-dust remover. DETAILED DESCRIPTION

[0021] Referring to Figure 1 The utility model relates to a kind of de-nitration devices for reducing low-temperature flue gas catalytic de-nitration fuel consumption, including the desulfurization device 10, dust remover 11, SCR reactor 1, draught fan 5 and chimney 6 sequentially communicated by 9 flue, the flue 9 of the input end and the output end of the SCR reactor 1 is equipped with heat exchanger 4, the flue 9 between the heat exchanger 4 and the input end of SCR reactor 1 is sequentially equipped with hot blast stove 7 and reducing agent injection device 8, the SCR reactor 1 is equipped with CO oxidation catalyst 3 and a plurality of de-nitration catalyst 2 located above CO oxidation catalyst 3.

[0022] SCR reactor 1 is cuboid structure, the SCR reactor 1 is provided with two layers or three layers of de-nitration catalyst 2 arranged at intervals, de-nitration catalyst 2 is arranged in the uppermost layer of SCR reactor 1, to remove NO X CO oxidation catalyst 3 is arranged in the original reserved position of the innermost layer of SCR reactor 1.

[0023] The main active ingredients of the CO oxidation catalyst 3 have noble metal or non-noble metal, and the noble metal catalyst includes one or more of Pd, Pt, Au and Ag, and the non-noble metal catalyst includes one or more of Cu, Mn, Co and Fe.

[0024] The de-nitration catalyst 2 and the CO oxidation catalyst 3 are both in honeycomb form, and the number of holes of the catalyst is 25-35.

[0025] The removal of nitrogen oxides and CO can be realized simultaneously in the SCR reactor (1).

[0026] The heat exchanger 4 is a rotary heat exchanger, a plate heat exchanger or a tube heat exchanger, and the heat exchanger 4 transfers a large amount of chemical heat generated by the combustion of the CO oxidation catalyst 3 from the hot end to the cold end, so as to increase the flue gas temperature at the de-nitration inlet of the SCR reactor 1 by 15-35°C.

[0027] The combustion fuel used by the hot blast stove 7 is coke oven gas, blast furnace gas or converter gas.

[0028] A method for reducing the fuel consumption of low-temperature flue gas catalytic denitration, which is realized based on the above-mentioned denitration device for reducing the fuel consumption of low-temperature flue gas catalytic denitration, comprising the following steps: the 100-150 DEG C flue gas after sintering / rolling is firstly subjected to a desulfurization reaction in a dry / wet desulfurization device 10, the flue gas after removing SO2 is subjected to dust removal in a dust remover 11, at this time, the outlet flue gas temperature of the dust remover 11 is changed to 50-80 DEG C, the low-temperature flue gas is firstly introduced into the cold end inlet of a heat exchanger 4 and flows out from the cold end outlet, under the action of the heat exchanger 4, the flue gas temperature flowing out from the cold end outlet is increased to 150-250 DEG C, then the flue gas is mixed with high-temperature hot air by a hot blast stove 7, so that the flue gas temperature is increased from 150-250 DEG C to 180-280 DEG C, the heat required for the initial flue gas temperature rise is provided by the combustion of gaseous fuel in the hot blast stove 7, when the flue gas reaches the temperature window of the denitration catalyst, the denitration reducing agent is sprayed from a denitration reducing agent spraying device 8, the flue gas and the reducing agent are fully mixed and uniformly distributed in the flue 9 at the denitration inlet, and then contact with the denitration catalyst 2 in the upper part of the SCR reactor 1, so that the removal of NO X is realized, the flue gas after removing NO X is contacted with the CO oxidation catalyst 3 in the lowermost part of the SCR reactor 1, the CO in the flue gas is oxidized and combusted under the action of the CO oxidation catalyst 3, the removal of CO is realized, and a large amount of chemical reaction heat is generated, so that the flue gas temperature is increased from 180-280 DEG C after denitration to 200-310 DEG C, under the action of the heat exchanger 4, the heat is transferred from the hot end to the cold end, so that the flue gas temperature at the cold end outlet of the heat exchanger 4 is increased from 150-250 DEG C to 180-280 DEG C, so that the fuel consumption of the hot blast stove 7 is reduced, and even the hot blast stove 7 can be stopped to heat the flue gas, thereby saving a large amount of fuel; under the action of the heat exchanger 4, the flue gas temperature is decreased from the hot end inlet 200-310 DEG C to the hot end outlet 80-110 DEG C, and finally the flue gas is extracted by the induced draft fan 5 and discharged through the chimney 6.

[0029] The above examples are used to illustrate the present application, but not to limit the present application, and any simple transformation of the present application also belongs to the protection scope of the present application.

Claims

1. A denitration device for reducing low-temperature flue gas catalytic denitration fuel consumption, characterized by: It comprises desulfurization device (10), dust collector (11), SCR reactor (1), induced draft fan (5) and chimney (6) communicated in sequence through flue (9), heat exchanger (4) is arranged on the flue (9) of the input end and output end of the SCR reactor (1), hot blast stove (7) and reducing agent injection device (8) are arranged in sequence on the flue (9) between the heat exchanger (4) and the input end of the SCR reactor (1), CO oxidation catalyst (3) and a plurality of denitration catalysts (2) located above the CO oxidation catalyst (3) are arranged in the SCR reactor (1).

2. The denitration device of claim 1, wherein the low-temperature flue gas catalytic denitration fuel consumption is reduced. Two or three layers of denitration catalysts (2) are arranged in the SCR reactor (1) at intervals.

3. The denitration device of claim 1, wherein the low-temperature flue gas catalytic denitration fuel consumption is reduced. The denitration catalyst (2) and the CO oxidation catalyst (3) are both in honeycomb type, and the number of holes of the catalyst is 25-35.

4. The denitration device of claim 1, wherein the low-temperature flue gas catalytic denitration fuel consumption is reduced. Nitrogen oxide and CO can be removed simultaneously in the SCR reactor (1).

5. The denitration device of claim 1, wherein the low-temperature flue gas catalytic denitration fuel consumption is reduced. The heat exchanger (4) is in rotary type, plate type or tube type, a large amount of chemical heat generated by the CO oxidation catalyst (3) is transferred from the hot end to the cold end of the heat exchanger (4), and the flue gas temperature at the denitration inlet of the SCR reactor (1) is increased by 15-35 DEG C.

6. The denitration device of claim 1, wherein the low-temperature flue gas catalytic denitration fuel consumption is reduced. The combustion fuel used by the hot blast stove (7) is coke oven gas, blast furnace gas or converter gas.

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