CN211725339U - WESP device for efficient removal of heavy metals by two-stage adsorption and two-stage spraying - Google Patents

Abstract

The utility model relates to a WESP device for efficiently removing heavy metals by synergistic two-stage adsorption and two-stage spraying. Adsorption area, two-stage spray area, electrostatic dust removal area and secondary adsorption area, and the two-stage spray area and electrostatic dust removal area are arranged in order from bottom to top, and a sewage discharge area is arranged below the two-stage adsorption area; The area has a first-level spray area and a second-level spray area sequentially arranged from bottom to top, and a demisting area is arranged between the first-level spray area and the second-level spray area. Compared with the prior art, after the flue gas in the utility model is cooperatively treated by a wet electrostatic precipitator equipped with double-stage adsorption and double-stage spraying, various forms of heavy metals such as arsenic, selenium, and lead in the flue gas can be efficiently removed. Purify.

Description

WESP device for efficient removal of heavy metals by two-stage adsorption and two-stage spraying

technical field

The utility model relates to the technical field of wet electrostatic precipitators (WESP), in particular to a WESP device for efficiently removing heavy metals by synergistic two-stage adsorption and two-stage spraying.

Background technique

With the development of the economy, the demand for electricity in industrial production and people's life continues to increase. Although our country is vigorously

Advocate energy-saving power generation, develop new energy and other measures, but my country's coal-dominated energy structure will not change in a short period of time.

China is the largest coal producer and the largest coal consumer in the world, and coal currently accounts for about 70% of the energy mix. However, coal combustion will produce a large amount of SO _x , NO _x and heavy metals, among which heavy metals such as arsenic, selenium, and lead are more harmful. These heavy metals are mainly concentrated on submicron particles and are difficult to be effectively used by conventional pollutant control facilities. Captured, they mainly exist in the form of aerosols in the atmosphere, which are not easy to settle, and most of the harmful heavy metals are difficult to be degraded by microorganisms, and stay in the atmosphere for a long time, causing great harm to the ecosystem and human beings.

my country's research on how to control heavy metals in coal-fired power plant purification devices started relatively late. At present, the research direction in the existing technology is mainly the determination of heavy metal content in flue gas, but how to improve the removal efficiency of heavy metals in flue gas and strengthen the There is still no perfect solution for the removal of heavy metals in China.

Therefore, in order to reduce the emission of heavy metal pollutants in the atmosphere of coal-fired power plants, and to carry out the form transformation, distribution and control of heavy metals in the process of coal combustion, various technologies need to be developed to remove particulate matter and heavy metals in flue gas. Chinese patent CN108201974A discloses a wet electrostatic precipitator, including a cleaning component and a chassis, an air inlet is provided on one side of the chassis, an air outlet is provided on the top of the chassis, and a sedimentation tank is provided below the chassis. The disadvantage of this technical solution is that the removal process of heavy metals is single, and the classification treatment cannot be realized, resulting in a low removal rate.

Utility model content

The purpose of this utility model is to provide a WESP device for efficiently removing heavy metals by synergistic double-stage adsorption and double-stage spraying in order to overcome the above-mentioned defects of the prior art.

The purpose of the present utility model can be achieved through the following technical solutions:

A WESP device with two-stage adsorption and two-stage spraying synergistically removes heavy metals with high efficiency. It has a flue gas inlet and a flue gas outlet. There are two-stage spraying area, electrostatic precipitating area and two-stage adsorption area, and the two-stage spraying area and electrostatic precipitating area are arranged in sequence from bottom to top, and the sewage area is arranged below the two-stage adsorption area;

The two-stage spraying area has a first-level spraying area and a second-level spraying area sequentially arranged from bottom to top, and a demisting area is arranged between the first-level spraying area and the second-level spraying area.

As a preferred technical solution, the first-stage adsorption zone is provided with an adsorption bed of micron-sized porous sodium carbonate and sodium bicarbonate, which is used to adsorb particulate heavy metals, and utilizes SO2 in the flue gas to react with _sodium bicarbonate to generate active oxidation Oxidation of particulate heavy metals (such as As ³⁺ to As ⁵⁺ , Se ⁰ to Se ⁴⁺ , Pb ⁰ to Pb ²⁺ ) by ^compounds (such as sodium thiosulfate, etc.), the particulate state Heavy metals include As _p , _{Sep and Pb p in} particulate state.

As a preferred technical solution, the first-level spray area is used for the flue gas to contact the sodium hypochlorite solution sprayed in the first-level spray area, and the sodium hypochlorite is used to further oxidize heavy metals including arsenic, selenium and lead.

As a preferred technical solution, the secondary spray area is used for the contact between the flue gas and the solution prepared by the sodium carbonate and sodium bicarbonate powder sprayed in the secondary spray area, and the particulate state is further removed by using sodium carbonate and sodium bicarbonate. , elemental and compound heavy metals, particulate heavy metals include particulate As _p , _{Sep and Pb p ,} elemental heavy metals include elemental Se ⁰ and Pb ⁰ , compound heavy metals include compound As ³⁺ , As ^{5 +} , Se ⁴⁺ and Pb ²⁺ .

As a preferred technical scheme, the mass ratio of the sodium carbonate to sodium bicarbonate is 1:1～3.

As a preferred technical solution, the spray particle size of the primary spray zone and the secondary spray zone is 10 μm-200 μm.

As a preferred technical solution, the mist removal area is provided with a mist eliminator, and the mist eliminator is used to treat fine dust particles, mist particles and wet gas saturated with liquid vapor.

As a preferred technical solution, the sewage area is provided with an ash hopper and a sewage outlet. It is used to collect particles of heavy metals such as arsenic, selenium, and lead.

As a preferred technical solution, the electrostatic precipitator zone is provided with a central axis and an anode and a cathode that are alternately arranged and connected to the central axis, the cathode is provided with burrs, and the anode and the cathode are driven by the central axis to follow the cycle of the central axis Sexual rotation. Improving the dust removal effect in the electrostatic dust removal area can further improve the removal effect of the particles formed by the droplets such as arsenic, selenium, and lead after spraying.

As a preferred technical solution, the electrostatic precipitator area is also provided with a purging component, which is a high-pressure air ejector, located above the anode and the cathode, and used for purging the particles adsorbed on the electrode plate of the electrostatic precipitator area, so that they fall off. to the sewage area.

As a preferred technical solution, the secondary adsorption zone is provided with an adsorption bed of micron-sized porous activated carbon and CaO, and CaO and activated carbon are used to further adsorb heavy metals including arsenic, selenium and lead.

As a preferred technical solution, when the WESP removal efficiency drops significantly, operations such as replacing the adsorption bed and updating the spray liquid are required.

The flue gas enters the first-stage adsorption zone from the flue gas inlet, which is equipped with an adsorption bed of micron-scale porous sodium carbonate and sodium bicarbonate, which is used to adsorb the particulate heavy metals arsenic, selenium, and lead (As _p , _{Sep , Pb p )} . SO ₂ in the flue gas reacts with sodium bicarbonate to generate active oxides (such as sodium thiosulfate, etc.) to convert As ³⁺ into As ⁵⁺ , Se ⁰ into Se ⁴⁺ , and Pb ⁰ into Pb ²⁺ ; After the first-level adsorption, the flue gas enters the first-level spray area. The spray liquid used is sodium hypochlorite solution. The flue gas is fully contacted with the spray liquid in the spray area, and sodium hypochlorite is used to further oxidize heavy metals such as arsenic, selenium, and lead. After the first-level spraying, it enters the demisting area, where the mist eliminator treats fine dust particles, mist particles and wet gas saturated with liquid vapor; the flue gas enters the second-level spraying area after passing through the demisting area, and the spray liquid used is sodium carbonate The solution prepared with sodium bicarbonate powder, the flue gas is fully contacted with the spray liquid in the spray area, and sodium carbonate and sodium bicarbonate are used to further remove the particulate state (As _p , _{Sep , Pb p )} , elemental state (Se ⁰ , Pb ⁰ ) and heavy metals such as arsenic, selenium, and lead in the combined state (As ³⁺ , As ^{5 +} , Se ⁴⁺ , Pb ²⁺ ); the flue gas enters the electrostatic precipitator area after passing through the secondary spray area, where the anode and the device The thorned cathodes are staggered and connected to the central shaft. During operation, the electrodes follow the central shaft to rotate periodically, which improves the dust removal effect in the electrostatic dust removal area, and can further improve the particle state of arsenic, selenium, and lead formed by spraying with droplets. Removal effect; the flue gas enters the secondary adsorption zone after passing through the electrostatic dust removal zone, and is equipped with an adsorption bed of micron-sized porous activated carbon and CaO. CaO and activated carbon are used to further adsorb various forms of heavy metals such as arsenic, selenium and lead. The gas is discharged from the flue gas outlet.

Compared with the prior art, the beneficial effects of the utility model are: for the effective removal of pollutant particles and heavy metals, arsenic, selenium, and lead in the flue gas, the flue gas passes through the first-level adsorption zone, the first-level spray zone, and the mist removal in sequence. The wet electrostatic precipitator with double-stage adsorption and double-spray is used to synergistically treat the heavy metals arsenic, selenium, and lead in the flue gas, so as to remove various forms in the flue gas. The high-efficiency removal of arsenic, selenium, and lead improves the removal rate of heavy metals as a whole, and achieves ultra-low and near-zero emissions from coal-fired flue gas.

Description of drawings

FIG. 1 is a schematic diagram of the WESP device of the present invention for the synergistic and efficient removal of heavy metals by two-stage adsorption and two-stage spraying.

In the figure, 1 is the flue gas inlet, 2 is the primary adsorption zone, 3 is the primary spray zone, 4 is the mist eliminator, 5 is the secondary spray zone, 6 is the anode, 7 is the cathode, and 8 is the thorn , 9 is the secondary adsorption zone, 10 is the flue gas outlet, 11 is the ash hopper, 12 is the sewage outlet, and 321 is the purging part.

Detailed ways

The present utility model will be described in detail below with reference to the accompanying drawings and specific embodiments.

Example 1

A WESP device with two-stage adsorption and two-stage spraying synergistically and efficiently removes heavy metals, as shown in Figure 1, has a flue gas inlet 1 and a flue gas outlet 10, and the flue gas inlet 1 and the flue gas outlet 10 are along the flue gas. There are first-level adsorption zone 2, double-stage spray zone, electrostatic precipitator zone and second-stage adsorption zone 9 in order in the flow direction, and the two-stage spray zone and electrostatic precipitator zone are arranged in order from bottom to top, and the lower part of the two-stage adsorption zone is arranged. There is a sewage discharge area; the two-stage spray area has a first-level spray area 3 and a second-level spray area 5 arranged in sequence from bottom to top, and a demisting area is provided between the first-level spray area 3 and the second-level spray area 5 Area.

specifically:

In this embodiment, the WESP device includes a cylinder body, the sewage discharge area, the two-stage spray area and the electrostatic dust removal area are arranged in the cylinder body from bottom to top in sequence, and the primary adsorption area 2 and the secondary adsorption area 9 are arranged on the side of the cylinder body. , and the primary adsorption area 2 is connected to the primary spray area 3, the secondary adsorption area 9 is connected to the electrostatic precipitator area, the flue gas inlet 1 is connected to the primary adsorption area 2, and the flue gas outlet 10 is connected to the secondary adsorption area. 9 on.

In this embodiment, the first-stage adsorption zone 2 is provided with an adsorption bed of micron-sized porous sodium carbonate and sodium bicarbonate, which is used to adsorb particulate heavy metals, and the SO ₂ in the flue gas reacts with sodium bicarbonate to generate active oxides to remove the particles. The oxidation of heavy metals in the particulate state includes As _p , Sep _p and Pb _p in the particulate state.

In this embodiment, the primary spray area 3 is used for the flue gas to contact the sodium hypochlorite solution sprayed by the primary spray area 3, and the sodium hypochlorite is used to further oxidize heavy metals including arsenic, selenium and lead. The secondary spray zone 5 is used for the contact between the flue gas and the solution prepared by the sodium carbonate and sodium bicarbonate powder sprayed in the secondary spray zone 5, and the use of sodium carbonate and sodium bicarbonate to further remove the particulate state, elemental state and combined state Heavy metals, particulate heavy metals include granular As _p , _{Sep and Pb p ,} elemental heavy metals include elemental Se ⁰ and Pb ⁰ , combined heavy metals include combined As ³⁺ , As ⁵⁺ , Se ⁴⁺ and Pb ²⁺ . Preferably, the mass ratio of sodium carbonate to sodium bicarbonate is 1:1 to 3. More preferably, the spray particle size of the primary spray zone 3 and the secondary spray zone 5 is 10 μm-200 μm. A mist eliminator 4 is provided in the demisting area, and the mist eliminator 4 is used to treat fine dust particles, mist particles and wet gas saturated with liquid vapor.

In this embodiment, the electrostatic precipitator area is provided with a central axis and an anode 6 and a cathode 7 which are alternately arranged and connected to the central axis. The cathode 7 is provided with burrs 8, and the anode 6 and the cathode 7 follow the cycle of the central axis driven by the central axis. Sexual rotation. Improving the dust removal effect in the electrostatic dust removal area can further improve the removal effect of the particles formed by the droplets such as arsenic, selenium, and lead after spraying. Preferably, the electrostatic precipitator area is further provided with a purging component 321. The purging component 321 is a high-pressure air injector, located above the anode 6 and the cathode 7, and is used for purging the particles adsorbed on the electrode plate of the electrostatic precipitator area to make them fall off. to the sewage area.

The sewage area is provided with an ash hopper 11 and a sewage outlet 12 . It is used to collect particles of heavy metals such as arsenic, selenium, and lead.

In this embodiment, the secondary adsorption zone 9 is provided with an adsorption bed of micron-sized porous activated carbon and CaO, and CaO and activated carbon are used to further adsorb heavy metals including arsenic, selenium and lead.

When the WESP device works, the flue gas first enters the primary adsorption zone 2 from the flue gas inlet 1, the particulate arsenic, selenium, and lead in the flue gas are adsorbed by the porous sodium carbonate and sodium bicarbonate, and the flue gas SO ₂ reacts with the sodium bicarbonate to generate active Oxides (such as sodium thiosulfate, etc.) oxidize arsenic, selenium, and lead into As ⁵⁺ , Se ⁴⁺ and Pb ²⁺ ; then the flue gas enters the primary spray zone 3, and the sprayed sodium hypochlorite droplets and some heavy metal particles Combine to form larger particles and settle into the ash hopper 11, and further oxidize part of the heavy metals arsenic, selenium, and lead; then the flue gas passes through the demisting zone 4 and passes through the mist eliminator to treat fine dust particles, mist particles and wet gas saturated with liquid vapor ; Another part of heavy metal particles in the flue gas enters the secondary spray zone 5 upward, and fully contacts with the spray liquid sodium carbonate and sodium bicarbonate solution to further remove various forms of heavy metals such as arsenic, selenium, and lead; then the remaining heavy metal particles After entering the electrostatic precipitator area, it is partially adsorbed on the electrode plate after corona discharge. The electrode plate in the electrostatic precipitator area rotates periodically with the central axis. The heavy metal particles deposited at the bucket are discharged from the sewage outlet 12; the flue gas enters the secondary adsorption zone 9 after passing through the electrostatic dust removal area, and the residual heavy metals in the flue gas are further adsorbed by CaO and activated carbon, and the purified flue gas is finally removed by the flue gas. Outlet 10 discharges. Taking heavy metal lead as an example, after 5-10 tests of the simulated flue gas system, the lead concentration at the flue gas inlet is 30 μg/m ³ , the overall error of the simulated experiment is ±5%, and the flue gas flow is set to 1.2 L/min. The average lead content detected in the flue gas after double-stage adsorption and double-stage spray oxidation was 5.67μg/m ³ .

The above description of the embodiments is for the convenience of those skilled in the art to understand and use the utility model. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein can be applied to other embodiments without inventive step. Therefore, the present invention is not limited to the above-mentioned embodiments, and improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should all fall within the protection scope of the present invention.

Claims (5)

1. A WESP device for efficiently removing heavy metals by two-stage adsorption and two-stage spraying in a synergistic manner is characterized by comprising a flue gas inlet (1) and a flue gas outlet (10), wherein a first-stage adsorption area (2), a two-stage spraying area, an electrostatic dust removal area and a second-stage adsorption area (9) are sequentially arranged between the flue gas inlet (1) and the flue gas outlet (10) along the flow direction of flue gas, the two-stage spraying area and the electrostatic dust removal area are sequentially arranged from bottom to top, and a sewage discharge area is arranged below the two-stage adsorption area;

the double-stage spraying area is provided with a first-stage spraying area (3) and a second-stage spraying area (5) which are sequentially arranged from bottom to top, and a demisting area is arranged between the first-stage spraying area (3) and the second-stage spraying area (5).

2. The WESP device for high-efficiency removal of heavy metals by the synergy of two-stage adsorption and two-stage spraying according to claim 1, wherein the spraying particle size of the first-stage spraying area (3) and the second-stage spraying area (5) is 10-200 μm.

3. The WESP device for efficiently removing heavy metals by the synergy of two-stage adsorption and two-stage spraying according to claim 1, wherein the demisting zone is provided with a demister (4), and the demister (4) is used for processing fine dust particles, fog particles and wet gas saturated by liquid vapor.

4. The WESP device for efficiently removing heavy metals by the synergy of two-stage adsorption and two-stage spraying according to claim 1, wherein the electrostatic dust removal zone is provided with a central shaft, and an anode (6) and a cathode (7) which are alternately arranged and connected to the central shaft, the cathode (7) is provided with barbs (8), and the anode (6) and the cathode (7) are driven by the central shaft to periodically rotate along with the central shaft.

5. The WESP device for efficiently removing heavy metals by virtue of the synergy of two-stage adsorption and two-stage spraying according to claim 4, wherein the electrostatic dust removal area is further provided with a purging component (321), the purging component (321) is a high-pressure air injector and is positioned above the anode (6) and the cathode (7) for purging the particles adsorbed on the electrode plate of the electrostatic dust removal area to make the particles fall to the pollution discharge area.

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