CN216024057U

CN216024057U - Active coke desulfurization and denitrification system

Info

Publication number: CN216024057U
Application number: CN202122073327.XU
Authority: CN
Inventors: 李启超; 安忠义; 段伦博; 孙镇坤
Original assignee: Huatian Engineering and Technology Corp MCC; Southeast University
Current assignee: Huatian Engineering and Technology Corp MCC; Southeast University
Priority date: 2021-08-31
Filing date: 2021-08-31
Publication date: 2022-03-15
Anticipated expiration: 2031-08-31

Abstract

The utility model discloses an active coke desulfurization and denitrification system. The system comprises: the system comprises a gas mixing tank, an ozone generator, an ammonia water evaporator and an active coke adsorption tower; wherein the gas mixing tank is provided with a sintering flue gas inlet, an ozone inlet and a gas outlet; the gas outlet of the ozone generator is communicated with the ozone inlet of the gas mixing tank; the gas outlet of the gas mixing tank and the gas outlet of the ammonia water evaporator are communicated with the gas inlet of the active coke adsorption tower. O in the utility model₃Is equal to the amount of NO species in the sintering flue gas, O₃Oxidation of NO to NO₂The traditional preposed oxidation wet absorption process needs to oxidize NO into nitrogen oxide N with higher valence state₂O₅The introduction of O with twice mole number of NO in the sintering flue gas is required₃The utility model obviously reduces O₃The introduction amount reduces the operation cost and simplifies the structure of the active coke adsorption tower.

Description

Active coke desulfurization and denitrification system

Technical Field

The utility model relates to an active coke desulfurization and denitrification system.

Background

The ferrous metallurgy industry plays a very important role in national economy in China, but simultaneously brings about the problems of high energy consumption and heavy pollution. The steel industry has various production processes, and comprises a plurality of process steps such as sintering pellets, coking, ironmaking, steelmaking, hot rolling, cold rolling and the like, wherein the sintering process is a main emission source of atmospheric pollutants in the whole production flow, and dust and SO in the generated sintering flue gas₂Nitrogen Oxide (NO)_x) And dioxin accounts for more than 40%, 70%, 50% and 90% of the total discharge amount of the whole process respectively. In 2019, five departments such as the department of ecological environment jointly release 'opinions about promoting implementation of ultra-low emission in the steel industry', and the requirement is that the ultra-low emission modification of steel enterprises in key areas is basically completed by the end of 2025. Along with the countryThe promotion of emission reduction policies and the enhancement of social environmental awareness gradually become research hotspots for removing sintering flue gas pollutants.

The active coke has a developed pore structure, rich surface functional groups and good adsorption and catalysis performances, and the active coke adsorption technology is considered to be one of the multi-pollutant cooperative treatment technologies most suitable for sintering flue gas. In engineering, a graded countercurrent process is usually adopted, namely, the lower part of an active coke adsorption tower is a desulfurization section, the upper part of the active coke adsorption tower is a denitration section, active coke flows from top to bottom, and flue gas flows from bottom to top in opposite directions. After the sintering flue gas enters a desulfurization section, dust and SO in the sintering flue gas₂And NO_xAdsorption of contaminants by activated coke, SO₂With H in the sintering flue gas₂O and O₂Reaction to form H₂SO₄And the sintering flue gas is added with NH before entering the denitration section₃And reacts with NO under the catalysis of active coke to generate N through Selective Catalytic Reduction (SCR) reaction₂And H₂And O, discharging the sintering flue gas subjected to pollutant removal from the top of the adsorption tower. And discharging the active coke subjected to adsorption saturation from the bottom of the adsorption tower, heating and regenerating the active coke in a regeneration system, and screening the regenerated active coke to reenter the adsorption tower for removing pollutants. The active coke adsorption technology has the advantages of high desulfurization efficiency, relatively matched denitration reaction window temperature and sintering flue gas exhaust temperature, capability of cooperatively removing various pollutants such as dust, dioxin and the like, but the technology has low denitration rate, large demand on active coke and relatively high operation cost, and the defects restrict the further popularization of the technology.

O₃The oxidation absorption technology is also one of the mainstream processes for desulfurization and denitrification of sintering flue gas. More than 90% of NO in sintering flue gas_xIs NO, and has a solubility in water of only 0.1g/dm³Therefore, semi-dry or wet desulfurization techniques cannot synergistically remove NO. O is₃Oxidation absorption technique using O₃Has the advantages of strong oxidizing property, strong NO selectivity and the like, and can oxidize NO in the sintering flue gas into NO with higher solubility₂(213g/dm³) Or N₂O₅(500g/dm³) And absorbing NO in the flue gas by alkali liquor_x、SO₂Thereby realizing simultaneous desulfurizationAnd (4) denitration. O is₃The oxidation absorption technology has simple process and high desulfurization and denitrification efficiency (all can reach more than 90%), but the technology needs to adopt alkali liquor to absorb the flue gas, so the requirement on the corrosion resistance of equipment and pipelines is higher. In addition, since N is₂O₅Has a higher water solubility than NO₂Therefore, in engineering applications, in order to be able to remove NO sufficiently_xIt is generally necessary to introduce an excess of O₃Thereby ensuring that NO can be oxidized into N with higher valence₂O₅. In the actual engineering, O₃The amount ratio of NO to NO is usually about 2, and O is generated while increasing the economic cost₃The problem of escape.

Therefore, the problem that the existing sintering flue gas desulfurization and denitration technology is difficult to consider lower economic cost and higher removal efficiency is generally solved, and the research on the efficient and economic sintering flue gas desulfurization and denitration technology has great application prospect and research value.

SUMMERY OF THE UTILITY MODEL

Aiming at the problems in the prior art, the utility model provides an active coke desulfurization and denitrification system which utilizes O₃Oxidizing NO in sintering flue gas to NO₂(ii) a Then the oxidized sintering flue gas is mixed with NH₃Mixing and entering into an active coke adsorption tower together to generate NH respectively under the catalytic action of the active coke₃-NO₂Reduction denitration reaction and NH₃-SO₂The desulfurization reaction realizes the simultaneous desulfurization and denitrification of the sintering flue gas, and the active coke after the reaction desorbs SO through a thermal regeneration system₂And NH₃Can be recycled and reduce NH₃Introducing amount and obtaining high concentration of SO₂By-products.

In order to achieve the above objects, the present invention provides an active coke desulfurization and denitrification system based on the synergistic effect of ozone and ammonia gas, wherein the system comprises: the system comprises a gas mixing tank, an ozone generator, an ammonia water evaporator and an active coke adsorption tower; wherein the content of the first and second substances,

the gas mixing tank is provided with a sintering flue gas inlet, an ozone inlet and a gas outlet; the gas outlet of the ozone generator is communicated with the ozone inlet of the gas mixing tank; the gas outlet of the gas mixing tank and the gas outlet of the ammonia water evaporator are communicated with the gas inlet of the active coke adsorption tower.

Further, the system comprises: the coke outlet of the active coke adsorption tower is connected with the inlet of the vibrating screen through a belt; the discharge hole of the vibrating screen is connected with the feed hole of the active coke regeneration system through a belt; the feed inlet of the active coke regeneration system is connected with the coke inlet of the active coke adsorption tower through a belt.

Furthermore, the sintering flue gas comes from steel plants, and the main components are NO and SO₂、O₂、H₂O and N₂The temperature is 80-200 ℃.

Further, the temperature in the gas mixing tank is 80-150 ℃.

Further, O is introduced into the gas mixing tank₃Is determined by the amount of NO species in the sintering flue gas, O₃The input amount of the nitrogen oxide is equal to the amount of NO substances in the sintering flue gas, so that the NO in the sintering flue gas is completely oxidized into NO₂。

Further, the temperature of the ammonia water evaporator is 320-350 ℃, and the pressure is 15000-25000 Pa.

Furthermore, the temperature in the active coke adsorption tower is 80-150 ℃, and the pressure is 1000-3000 Pa.

Furthermore, the particle size distribution of the active coke is 5-12 mm, and the specific surface area is more than 150m²The average pore diameter is more than 2nm, the content of C element on the surface is more than 75 percent, and the content of O element is more than 15 percent.

Further, NH introduced into the active coke adsorption tower₃The amount of the gas is determined by SO in sintering flue gas₂Determined by the number of moles of, NH₃The introduction amount of (2) and SO in the sintering flue gas₂The molar ratio of (A) to (B) is 1.5 to 2.

Further, NO in the sintering flue gas₂With NH under the catalysis of activated coke₃The reaction taking place is 8NH₃+6NO₂→7N₂+12H₂O，NO₂Finally converted to N₂Further realizes NO in the sintering flue gas_xAnd (4) removing.

Go toStep (b), SO in the sintering flue gas₂And NH₃The reactions taking place are each NH₃+SO₂+H₂O→NH₄HSO₃And 2NH₃+SO₂+H₂O→(NH₄)₂SO₃NH formed₄HSO₃And (NH)₄)₂SO₃Adsorbed on the surface of active coke and is O-coated₂Oxidation to NH₄HSO₄And (NH)₄)₂SO₄The reaction taking place is 2NH₄HSO₃+O₂→2NH₄HSO₄And 2 (NH)₄)₂SO₃+O₂→2(NH₄)₂SO₄Further realizing SO in the sintering flue gas₂And (4) removing.

Further, the vibrating screen is used for physically screening according to the difference of the particle sizes of the active coke, active coke powder with the particle size smaller than 5mm is screened out as the inactivated active coke, and the active coke with the particle size distributed within 5-12 mm is sent to an active coke regeneration system.

Furthermore, the temperature in the active coke regeneration system is 250-400 ℃, and the pressure is-270-50 Pa.

Further, SO can be obtained at the outlet of the active coke regeneration system₂、NH₃The gas mixture can respectively obtain high-concentration SO after passing through a gas separation device₂、NH₃By-products. This part of NH₃The by-product can be continuously used for desulfurization and denitrification in the active coke adsorption tower.

Compared with the prior art, the utility model has the following advantages:

1. o in the utility model₃Is equal to the amount of NO species in the sintering flue gas, O₃Oxidation of NO to NO₂The traditional preposed oxidation wet absorption process needs to oxidize NO into nitrogen oxide N with higher valence state₂O₅The introduction of O with twice mole number of NO in the sintering flue gas is required₃The utility model obviously reduces O₃The introduction amount reduces the operation cost;

2. by the process of the utility model₃And NH₃The synergistic effect is realized in the active coke adsorption tower to catalyze NH by active coke₃-NO₂Reduction denitration reaction and NH₃-SO₂Desulfurization reaction, desulfurization product NH₄HSO₄And (NH)₄)₂SO₄Is adsorbed by the active coke, and an active coke adsorption tower is not required to be divided into two stages of a desulfurization section and a denitration section, so that the structure of the active coke adsorption tower is simplified.

3. By the process of the utility model₃The oxidation oxidizes the NO in the sintering flue gas to NO₂And catalyze NH₃With NO₂A reduction reaction occurs, compared to NH₃The denitration efficiency is greatly improved by the standard SCR reduction reaction with NO, and simultaneously, the active coke adsorbs NH₃-SO₂The desulfurization reaction product improves the desulfurization effect of the active coke. The improvement of the desulfurization and denitrification efficiency reduces the required amount of the active coke.

4. The active coke discharged from the active coke adsorption tower is sent to an active coke regeneration system, and is regenerated at the temperature of 250-400 ℃ and NH is released₃And SO₂Gas, gas separation device for separating NH₃And SO₂After separation, SO₂Can be used for preparing sulfuric acid, NH₃With NH generated by ammonia water evaporators₃Mixing to realize NH₃And (4) recycling.

Drawings

FIG. 1 is a schematic diagram of an activated coke desulfurization and denitrification system.

The figure shows that: the device comprises a gas mixing tank (1), an active coke adsorption tower (2), an oxygen storage tank (3), an ozone generator (4), an ammonia water storage tank (5), an ammonia water pump (6), an ammonia water evaporator (7), a vibrating screen (8), an active coke regeneration system (9) and a gas separation device (10).

Detailed Description

The utility model is explained in more detail below with reference to exemplary embodiments and the accompanying drawings. The following examples are not intended to limit the present invention in any way, and all technical solutions obtained by means of equivalent substitution or equivalent transformation are within the scope of the present invention.

Examples

A schematic diagram of an active coke desulfurization and denitrification system is shown in FIG. 1, and the working process is as follows:

1) o in oxygen storage tanks₂Entering an ozone generator to react to generate O₃Enters a gas mixing tank to be mixed with sintering flue gas, and NO in the sintering flue gas is totally treated by O₃By oxidation to NO₂(ii) a In this example, the temperature in the gas mixing tank was 110 ℃ and O was introduced₃The ratio of the amount of NO substances in the sintering flue gas to the amount of NO substances in the sintering flue gas is 1: 1.

wherein the sintering flue gas is from steel plant, and comprises NO and SO as main components₂、O₂、H₂O and N₂The temperature is 80-200 ℃. The temperature in the gas mixing tank is 80-150 ℃. O introduced into the gas mixing tank in the step one₃Is determined by the amount of NO species in the sintering flue gas, O₃The input amount of the nitrogen oxide is equal to the amount of NO substances in the sintering flue gas, so that the NO in the sintering flue gas is completely oxidized into NO₂。

2) The ammonia water in the ammonia water storage tank enters an ammonia water evaporator after passing through an ammonia water pump, and evaporated NH is generated₃Mixing with the oxidized sintering flue gas in an active coke adsorption tower to obtain NO in the sintering flue gas₂With NH under the catalytic action of activated coke₃Reaction to produce N₂And H₂O, SO in sintering flue gas₂、O₂、H₂O and NH₃The reaction respectively generates NH₄HSO₄And (NH)₄)₂SO₄Adsorbing on the surface of active coke, and finally realizing NO in the sintering flue gas_xAnd SO₂And (4) removing. The temperature of the ammonia water evaporator in this example was 330 ℃ and the pressure was 20000 Pa. The temperature in the active coke adsorption column was 110 ℃ and the pressure was 2500 Pa. Introduction of NH₃With SO in the sintering flue gas₂The mass ratio of substances is 1.5: 1. the particle size distribution of the active coke is 7-10 mm, and the specific surface area is 300m²(ii)/g, the average pore diameter is 3nm, the surface C element content is 80%, and the O element content is 17%.

The temperature of the ammonia water evaporator is 320-350 ℃, and the pressure is 15000-25000 Pa. The temperature in the active coke adsorption tower is 80-150 ℃, and the pressure isIs 1000 to 3000 Pa. The particle size distribution of the active coke is 5-12 mm, and the specific surface area is more than 150m²The average pore diameter is more than 2nm, the content of C element on the surface is more than 75 percent, and the content of O element is more than 15 percent. The NH introduced into the active coke adsorption tower₃The amount of the gas is determined by SO in sintering flue gas₂Determined by the number of moles of, NH₃The introduction amount of (2) and SO in the sintering flue gas₂The molar ratio of (A) to (B) is 1.5 to 2. NO in the sintering flue gas₂With NH under the catalysis of activated coke₃The reaction taking place is 8NH₃+6NO₂→7N₂+12H₂O，NO₂Finally converted to N₂Further realizes NO in the sintering flue gas_xRemoving; SO in the sintering flue gas₂And NH₃The reactions taking place are each NH₃+SO₂+H₂O→NH₄HSO₃And 2NH₃+SO₂+H₂O→(NH₄)₂SO₃NH formed₄HSO₃And (NH)₄)₂SO₃Adsorbed on the surface of active coke and is O-coated₂Oxidation to NH₄HSO₄And (NH)₄)₂SO₄The reaction taking place is 2NH₄HSO₃+O₂→2NH₄HSO₄And 2 (NH)₄)₂SO₃+O₂→2(NH₄)₂SO₄Further realizing SO in the sintering flue gas₂And (4) removing.

3) Feeding the activated coke in the activated coke adsorption tower into a vibrating screen at intervals, screening and discharging the deactivated activated coke, feeding the rest of the activated coke into an activated coke regeneration system, desorbing and regenerating the activated coke under the heating condition, and releasing NH₃And SO₂The regenerated active coke and fresh active coke are sent into the active coke adsorption tower again to release NH₃And SO₂And after separation by a gas separation device, the separated NH3 is mixed with NH3 at the outlet of the ammonia water evaporator and then enters an active coke adsorption tower. In this example, the temperature in the activated coke regeneration system was 300 ℃ and the pressure was-200 Pa. Active coke powder with particle size less than 5mm is used as inactive active cokeAnd (4) screening out the active coke with the particle size distribution within 5-12 mm, and feeding the active coke into an active coke regeneration system.

The vibrating screen is used for physically screening according to the difference of the particle sizes of the active coke, active coke powder with the particle size smaller than 5mm is screened out as the inactivated active coke, and the active coke with the particle size distribution within 5-12 mm is sent to an active coke regeneration system; the temperature in the active coke regeneration system is 250-400 ℃, and the pressure is-270 to-50 Pa. SO can be obtained from the outlet of the active coke regeneration system₂、NH₃The gas mixture can respectively obtain high-concentration SO after passing through a gas separation device₂、NH₃By-products. This part of NH₃The by-product can be continuously used for desulfurization and denitrification in the active coke adsorption tower.

Claims

1. An active coke desulfurization and denitrification system, characterized in that the system comprises: the system comprises a gas mixing tank, an ozone generator, an ammonia water evaporator and an active coke adsorption tower; wherein the content of the first and second substances,

2. The activated coke desulfurization and denitrification system according to claim 1, further comprising: the coke outlet of the active coke adsorption tower is connected with the inlet of the vibrating screen through a belt; the discharge hole of the vibrating screen is connected with the feed hole of the active coke regeneration system through a belt; the feed inlet of the active coke regeneration system is connected with the coke inlet of the active coke adsorption tower through a belt.

3. The activated coke desulfurization and denitrification system according to claim 1, wherein the temperature in the gas mixing tank is 80 to 150 ℃.

4. The activated coke desulfurization and denitrification system according to claim 1, wherein the temperature of the ammonia water evaporator is 320 to 350 ℃ and the pressure is 15000 to 25000 Pa.

5. The activated coke desulfurization and denitrification system according to claim 1, wherein the temperature in the activated coke adsorption tower is 80 to 150 ℃ and the pressure is 1000 to 3000 Pa.

6. The activated coke desulfurization and denitrification system according to claim 1, wherein the particle size distribution of the activated coke is 5-12 mm, and the specific surface area is more than 150m²(ii)/g, the average pore diameter is greater than 2 nm.

7. The activated coke desulfurization and denitrification system according to claim 2, wherein the temperature in the activated coke regeneration system is 250 to 400 ℃ and the pressure in the activated coke regeneration system is-270 to-50 Pa.