Coal-fired flue gas desulfurization and demercuration device

Abstract

A coal-fired flue gas desulfurization and demercuration device comprises a flue gas input module, the flue gas input module is a flue and desulfurization and demercuration absorption tower connecting device, and the flue outlet end of a power plant can be connected with the inlet end of a desulfurization and demercuration absorption single tower; the outlet end of the desulfurization and demercuration absorption single tower is connected with the inlet end of the tail gas treatment module through a second three-way valve; the flue gas input module is used for introducing flue gas containing SO2 and mercury ions into the absorption single tower; after entering the desulfurization and demercuration absorption single tower, flue gas flows upwards to pass through a multi-stage nozzle arranged in the absorption tower and a corresponding gas distribution plate below the nozzle, and desulfurization and demercuration operation is carried out; according to the utility model, the single-tower combined desulfurization and demercuration technology is realized, the process flow and the device structure are simplified, the number of common multi-tower arrangement is reduced, the operation and the maintenance are simple, the space is saved, and the material consumption cost is reduced; the method can be applied to coal-fired power plant boilers, industrial boilers, garbage incinerators and the like, is particularly suitable for transforming built small and medium-sized coal-fired boilers, and has a wide market application prospect.

Description

Technical Field

[0001] The utility model relates to the technical field of environmental pollution control, in particular to a device for desulfurization and demercuration of coal-fired flue gas. Background Art

[0002] At present, the control methods of mercury in coal-fired power plants are mainly divided into mercury removal before combustion, during combustion, and after combustion. Pre-combustion control mainly includes coal washing and pyrolysis technology; during combustion control refers to some technical means adopted by power plants, such as fluidized bed combustion and low-nitrogen combustion; post-combustion mercury removal is the focus of coal emission reduction technology, and there are two main development directions: mercury adsorbent development and transformation of existing flue gas treatment equipment to achieve the coordinated removal of other pollutants and mercury.

[0003] The removal of mercury requires different technologies due to its different forms in coal-fired flue gas. There are three main forms of mercury in coal-fired flue gas: elemental mercury (Hg 0 ), oxidized mercury (Hg 2+ ) and particulate mercury (Hg p ), and account for 16%, 61% and 23% of the flue gas mercury emissions respectively. Among them, particulate mercury is easily captured and removed by dust removal devices or WFGD and other devices; oxidized mercury is easily soluble in water and can also be adsorbed on particulate matter, which is easy to remove; elemental mercury is the most difficult to control. In view of the above characteristics, different methods can be used to treat mercury in flue gas: ① Mercury adsorbent removal technology, which uses carbon-based, calcium-based adsorbents, and mineral adsorbents to remove mercury from flue gas after modification, but there is a problem of adsorbent regeneration, so the cost is relatively high, and the abandonment of the adsorbent is prone to cause secondary pollution; ② Elemental mercury oxidation technology, which mainly uses a wet desulfurization system to absorb and remove divalent mercury Hg 2+ The method of single element Hg 0 It is difficult to dissolve in water and needs to increase the divalent mercury Hg in the flue gas. 2+ This method is more reasonable in terms of device setting, technical economy, but the Hg absorbed by WFGD 2+ In the desulfurization slurry, it will react with reducing substances such as SO3 2- 、HSO3 - The reaction regenerates Hg 0 , resulting in the secondary release of mercury. Therefore, inhibiting the re-release of mercury is of great significance to controlling mercury emissions from coal-fired flue gas.

[0004] There are three main ways to inhibit divalent mercury in the liquid phase: 1. Changing operating conditions, such as changing the aeration volume or increasing the cumulative concentration of liquid chloride ions. This method is generally difficult to carry out and difficult to control; 2. Changing the redox environment of the desulfurization slurry, such as adding a strong oxidant to the desulfurization slurry to oxidize the reducing substances in the slurry to inhibit the reduction of divalent mercury. This method requires continuous addition of oxidants and has poor economic efficiency. Summary of the invention

[0005] In order to overcome the problems existing in the above-mentioned prior art, the purpose of the utility model is to provide a flue gas wet synergistic desulfurization and demercuration system. First, the flue gas input module will draw flue gas from the flue and pass it into the absorption tower; after entering the single absorption tower, the flue gas flows upward through the absorption section below the nozzle for synergistic desulfurization and demercuration, so as to achieve the purpose of synergistic desulfurization and demercuration using a single tower, simplify the process flow and operation steps, and reduce equipment changes. The gas after desulfurization and demercuration will be defogged by the wire mesh defog section arranged on the upper part of the absorption tower, and will be passed through the top of the tower body to the flue gas analyzer for component analysis. A three-way valve is arranged in the passage to adjust the source of the gas path entering the flue gas analyzer, which can meet the measurement of the components of the two gas paths of intake and exhaust gas; the utility model has a simple structure and a clever design. Only one spray tower is used to realize the effective desulfurization and demercuration of the flue gas in a circulation manner, which simplifies the process flow and device structure, greatly reduces the investment and operation costs, and the process is simple and reliable, the operation and maintenance are simple, and it is suitable for promotion.

[0006] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0007] A coal-fired flue gas desulfurization and demercuration device comprises a flue gas input module 9, the outlet end of the flue gas input module 9 is respectively connected to the inlet end of the tail gas treatment module 8 and the pressurizing module 5 through a first three-way valve 91, the outlet end of the pressurizing module 5 is connected to the inlet end of the desulfurization and demercuration absorption single tower 7 through a secondary flue gate valve 6; the outlet end of the desulfurization and demercuration absorption single tower 7 is connected to the inlet end of the tail gas treatment module 8 through a second three-way valve 83.

[0008] The flue gas input module 9 includes a flue 1 , a flue gas thermometer 2 , a primary flue gate valve 3 , and a flue gas flowmeter 4 which are sequentially connected through pipelines; the outlet of the flue gas flowmeter 4 is connected to the inlet of the first three-way valve 91 .

[0009] The desulfurization and demercuration absorption single tower 7 includes a slurry pool 74 at the bottom, a tower 77 is provided on the top of the slurry pool 74, and a multi-stage nozzle 72 is provided in the vertical direction of the middle section of the tower 77. An air distribution plate 73 is provided below each stage of the nozzle 72, and a wire mesh demisting section 71 is provided above the highest stage of the nozzle 72; the inlet end of the multi-stage nozzle 72 is connected to the outlet end of the peristaltic pump 75, and the inlet end of the peristaltic pump 75 is connected to the outlet end of the slurry pool 74; a stirring paddle 76 is also provided on the upper part of the slurry pool 74, and the blades of the stirring paddle 76 extend into the slurry in the slurry pool 74.

[0010] The exhaust gas treatment module 8 includes a flue gas analyzer 81 and a flue gas collection device 82 connected in parallel. The inlet end of the flue gas analyzer 81 is connected to the outlet ends of the first three-way valve 91 and the second three-way valve 83 respectively through a third three-way valve 84.

[0011] The pressurizing module 5 adopts an axial flow fan.

[0012] The multi-stage nozzle 72 is preferably a two-stage nozzle.

[0013] A plurality of flow guiding holes 78 are evenly distributed on the air distribution plate 73 .

[0014] Compared with the prior art, the utility model provides a wet flue gas collaborative desulfurization and demercuration device, which has the following technical effects:

[0015] 1. After the flue gas is drawn into the single absorption tower, it flows upward through the set multi-stage nozzles and the corresponding gas distribution plates, and the synergistic desulfurization and demercuration are carried out in the absorption section. The slurry can be desulfurized and demercured through the slurry pool to achieve the purpose of synergistic control using a single tower. This device simplifies the desulfurization and demercuration process and operation steps, reduces the number of common multi-tower arrangements, saves space, and reduces investment and operating costs. The process is simple and reliable, and the operation and maintenance are simple, which is suitable for promotion.

[0016] 2. Install fixed multi-layer nozzles on the side wall of the absorption section in the tower to achieve the purpose of setting up multi-layer spraying. The slurry is transported to the two nozzles through the peristaltic circulation pump for counter-convection with the flue gas to absorb SO2 and Hg in the flue gas. 2+ , increasing the contact time.

[0017] 3. The gas after desulfurization and demercuration will be defogged by the wire mesh defogger section installed on the upper part of the absorption tower, and will be discharged from the top of the tower body and led to the flue gas analyzer for component analysis. A second three-way valve is set in the passage to adjust the source of the gas path entering the flue gas analyzer, which can meet the measurement of the composition of the intake gas and the exhaust gas.

[0018] 4. The desulfurization and demercuration absorption single tower 7 uses the desulfurization and demercuration liquid stored in the slurry pool 74 to meet the coordinated operation of desulfurization and demercuration in a single absorption tower. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the utility model.

[0020] In the figure: 1. Flue, 2. Flue gas thermometer, 3. Primary flue valve, 4. Flue gas flowmeter, 5. Pressurization module, 6. Secondary flue valve, 7. Desulfurization and demercuration absorption tower, 71. Wire mesh demisting section, 72. Nozzle, 73. Gas distribution plate, 74. Slurry pool, 75. Peristaltic pump, 76. Agitator, 77. Tower, 78. Diversion hole. 8. Exhaust treatment module, 81. Flue gas analyzer, 82. Exhaust gas collection device, 83. Second three-way valve, 84. Third three-way valve, 9. Flue gas simulation module, 91. First three-way valve.

[0021] Figure 2 Schematic diagram of the air distribution plate structure. DETAILED DESCRIPTION

[0022] The embodiments of the present utility model are further described below in conjunction with the accompanying drawings.

[0023] See also Figure 1 A coal-fired flue gas desulfurization and demercuration device comprises a flue gas input module 9, the outlet end of the flue gas input module 9 is respectively connected to the inlet end of the tail gas treatment module 8 and the pressurizing module 5 through a first three-way valve 91, the outlet end of the pressurizing module 5 is connected to the inlet end of the desulfurization and demercuration absorption single tower 7 through a secondary flue plug-in valve 6; the outlet end of the desulfurization and demercuration absorption single tower 7 is connected to the inlet end of the tail gas treatment module 8 through a second three-way valve 83.

[0024] The flue gas input module 9 includes a flue 1 , a flue gas thermometer 2 , a primary flue gate valve 3 , and a flue gas flowmeter 4 which are sequentially connected through pipelines; the outlet of the flue gas flowmeter 4 is connected to the inlet of the first three-way valve 91 .

[0025] The desulfurization and demercuration absorption single tower 7 includes a slurry pool 74 at the bottom, a tower 77 is provided on the top of the slurry pool 74, and a multi-stage nozzle 72 is provided in the vertical direction of the middle section of the tower 77. An air distribution plate 73 is provided below each stage of the nozzle 72, and a wire mesh demisting section 71 is provided above the highest stage of the nozzle 72; the inlet end of the multi-stage nozzle 72 is connected to the outlet end of the peristaltic pump 75, and the inlet end of the peristaltic pump 75 is connected to the outlet end of the slurry pool 74; a stirring paddle 76 is also provided on the upper part of the slurry pool 74, and the blades of the stirring paddle 76 extend into the slurry in the slurry pool 74.

[0026] The exhaust gas treatment module 8 includes a flue gas analyzer 81 and a flue gas collection device 82 connected in parallel. The inlet end of the flue gas analyzer 81 is connected to the outlet ends of the first three-way valve 91 and the second three-way valve 83 respectively through a third three-way valve 84.

[0027] The pressurizing module 5 adopts an axial flow fan.

[0028] The multi-stage nozzle 72 is preferably a two-stage nozzle.

[0029] The air distribution plate 73 is evenly distributed with a number of guide holes 78, which has the function of evenly distributing the air flow velocity and can provide good vulcanization conditions.

[0030] The desulfurization and demercuration absorption single tower 7 satisfies the coordinated operation of desulfurization and demercuration in a single absorption tower by adjusting the desulfurization and demercuration liquid stored in the slurry pool 74 .

[0031] The working principle of the utility model is as follows:

[0032] The flue gas thermometer 2 and the flue gas flowmeter 4 are used to measure and control the temperature and flow of the tail flue gas extracted from the flue 1, and the flue gas is led to the flue gas analyzer 81 through the first three-way valve 91 and the third three-way valve 84 to measure the inlet gas composition, or the flue gas is led to the pipeline connected to the absorption tower 7. A pressurizing device 5 and a secondary flue plug valve 6 are arranged in this section of the pipeline. The flue gas enters the absorption tower 7 after passing through the pressurizing device 5. The inlet gas will flow from bottom to top in the absorption tower 7, and will flow through the primary and secondary nozzles 72 and the primary and secondary gas distribution plates 73 arranged inside the single tower in turn. In the embodiment, the slurry sprayed from the nozzle 72 is transported after being connected to the slurry pool 74 through a peristaltic circulation pump 75 and a pipeline, and two stirring paddles 76 are arranged on the upper part of the slurry pool 74 to achieve the purpose of stirring the slurry to make it uniform. The slurry sprayed from the nozzle 72 is in convection contact with the gas flowing from bottom to top to remove sulfur and mercury in the flue gas. By adjusting the composition of the slurry sprayed from the nozzle 72, the coordinated desulfurization and demercuration in the single absorption tower can be met, and the gas after absorption will first be defogged by the wire mesh defog section 71 arranged on the upper part of the absorption single tower barrel 7, and then discharged from the top thereof. The exhaust gas is connected to the second three-way valve 83 through a pipeline. The second three-way valve 83 can be used to select two routes for the exhaust gas to lead to the exhaust gas treatment module 8, which are: a flue gas analyzer 81 and a tail gas absorption device 82. The flue gas analyzer 81 can measure the exhaust gas and analyze its specific components. The tail gas absorption device 82 is filled with an acidic potassium permanganate solution to absorb the sulfur and mercury that are not completely absorbed in the exhaust gas. The treated exhaust gas will be discharged into the atmosphere.

Claims

1. A coal-fired flue gas desulfurization and demercuration device, comprising a flue gas input module (9), characterized in that: The outlet end of the flue gas input module (9) is connected to the inlet end of the tail gas treatment module (8) and the pressurizing module (5) respectively through a first three-way valve (91); the outlet end of the pressurizing module (5) is connected to the inlet end of the desulfurization and demercuration absorption single tower (7) through a secondary flue gate valve (6); and the outlet end of the desulfurization and demercuration absorption single tower (7) is connected to the inlet end of the tail gas treatment module (8) through a second three-way valve (83).

2. A coal-fired flue gas desulfurization and demercuration device according to claim 1, characterized in that: The flue gas input module (9) comprises a flue (1), a flue gas temperature measuring instrument (2), a primary flue gas plug valve (3), and a flue gas flow meter (4) which are sequentially connected via pipelines; the outlet end of the flue gas flow meter (4) is connected to the inlet end of the first three-way valve (91).

3. The device for desulfurization and demercuration of coal-fired flue gas according to claim 1, characterized in that: The desulfurization and demercuration absorption single tower (7) comprises a slurry pool (74) at the bottom, a tower (77) is provided at the top of the slurry pool (74), a multi-stage nozzle (72) is provided in the vertical direction in the middle section of the tower (77), an air distribution plate (73) is provided below each stage of the nozzle (72), and a wire mesh demisting section (71) is provided above the highest stage of the nozzle (72); the inlet end of the multi-stage nozzle (72) is connected to the outlet end of a peristaltic pump (75), and the inlet end of the peristaltic pump (75) is connected to the outlet end of the slurry pool (74); a stirring paddle (76) is also provided at the top of the slurry pool (74), and the paddles of the stirring paddle (76) extend into the slurry in the slurry pool (74).

4. The device for desulfurization and demercuration of coal-fired flue gas according to claim 1, characterized in that: The exhaust gas treatment module (8) comprises a flue gas analyzer (81) and an exhaust gas collection device (82) connected in parallel with each other, and the inlet end of the flue gas analyzer (81) is connected to the outlet ends of the first three-way valve (91) and the second three-way valve (83) respectively through a third three-way valve (84).

5. The device for desulfurization and demercuration of coal-fired flue gas according to claim 1, characterized in that: The pressurizing module (5) adopts an axial flow fan.

6. The device for desulfurization and demercuration of coal-fired flue gas according to claim 3, characterized in that: The multi-stage nozzle (72) is a two-stage nozzle.

7. The device for desulfurization and demercuration of coal-fired flue gas according to claim 3, characterized in that: A plurality of flow guide holes (78) are evenly distributed on the air distribution plate (73).

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