CN202191838U - A coal-fired industrial boiler flue gas treatment device - Google Patents

Abstract

The utility model discloses a coal-fired industrial boiler flue gas processing apparatus, including venturi spraying reactor, wet-type electrostatic reactor, high voltage power supply, absorbent circulation pond, draught fan and chimney, venturi sprayer's diffuser pipe be connected with wet-type electrostatic reactor's air inlet, wet-type electrostatic reactor's gas outlet and draught fan, chimney connect gradually, delivery port be connected with absorbent circulation pond, absorbent storehouse is connected in the absorbent circulation pond. The utility model discloses dust, SO in the flue gas can be realized to the device₂And NOx and other various pollutants, has high pollutant removal efficiency and simple and reliable process, and can greatly save investment and operation cost.

Description

A coal-fired industrial boiler flue gas treatment device

technical field

The utility model relates to a flue gas treatment device, in particular to a device for removing various pollutants in the flue gas of coal-fired industrial boilers by using Venturi spray combined with wet static electricity. the

Background technique

my country is a big country in the production and use of industrial boilers. According to statistics, in 2008, there were more than 500,000 industrial boilers in use in my country, with a large number and wide distribution, and more than 80% of them are coal-fired boilers. At present, my country's coal-fired industrial boilers have the following characteristics: (1) The average capacity of a single boiler is small, the overall energy consumption level of the boiler is high, the management level of energy conservation and emission reduction is low, energy waste and environmental pollution are serious. (2) The types of coal used by boilers are varied, the coal quality is poor, the combustion is deteriorating, and the combustion method is outdated. The main layer-fired boilers have low combustion efficiency and high pollutant emission intensity. (3) The boiler chimney is low, the exhaust gas temperature is high, and the pollution is large. (4) The number of boilers in use is large and the layout is quite scattered, making pollution control and emission reduction difficult. As an important energy conversion equipment, the total annual coal consumption of my country's coal-fired industrial boilers is nearly 500 million tons, accounting for about 1/5 of the country's total coal consumption. It is the second largest energy-consuming equipment except power generation boilers. my country's energy consumption is large and one of the main sources of air pollution. In 2010, coal-fired industrial boilers in my country emitted about 10 million tons of sulfur dioxide, about 2 million tons of nitrogen oxides, about 1 million tons of dust, and about 90 million tons of waste residue, which is the second largest soot type in my country after coal-fired power generation. source of pollution. Therefore, vigorously developing the comprehensive control of various pollutants in the flue gas of coal-fired industrial boilers is the key link to achieve a substantial reduction of air pollutants, which puts forward very urgent requirements for the development and application of flue gas pollution control technologies for coal-fired industrial boilers requirements. the

However, due to the poor economic strength of general industrial enterprises in my country and the backwardness of the existing flue gas pollution control technology, most coal-fired industrial boiler dust removal and desulfurization equipment is still relatively backward, and some even have no dust removal and desulfurization devices, and very few denitrification devices. At present, domestic coal-fired industrial boiler flue gas pollution control mainly focuses on dust removal. Most of the supporting dust removal equipment is cyclone dust collector, but 50% of cyclone dust collectors are not operating normally and are being phased out. The main reason is that the cyclone dust collector is easy to block and leak air, which makes the dust removal efficiency drop significantly; my country began to develop the flue gas desulfurization technology of coal-fired industrial boilers in the early 1990s, and there are about 10 flue gas desulfurization methods that can operate stably at present. There are only a few kinds, but only a few kinds actually enter the market, and the investment and operation costs are relatively expensive, and it is difficult to promote and apply. Some thorny technical problems, such as low operating efficiency, corrosion, scaling, clogging, secondary pollution, steam-water separation and gray-water separation, have not been well resolved, making it difficult for the development of flue gas desulfurization of coal-fired industrial boilers; and for The flue gas denitrification of coal-fired industrial boilers is still blank in China. the

The traditional control of coal-fired flue gas pollutants is a kind of pollutant control method that adopts a set of flue gas removal devices. When multiple pollutants need to be controlled at the same time, it will inevitably lead to problems such as complex system, large footprint, and high cost. . According to the current and future market demand for the development of flue gas pollution control of coal-fired industrial boilers, research and development of high-efficiency and new simultaneous removal technologies for multiple pollutants and realize industrial demonstrations, and gradually popularize and apply them will be the key to the flue gas of coal-fired industrial boilers in the future. The focus and trend of pollution control technology development. the

In recent years, the United States, Japan and other developed countries have been active in the research on the integrated removal of multiple pollutants from coal combustion, and some of these technologies are already in the early stage of commercialization. At present, the simultaneous removal of multiple pollutants in the flue gas that has been studied more includes oxidation absorption technology (such as plasma method, photocatalysis method, hydrogen peroxide oxidation absorption technology), reduction technology (such as urea simultaneous desulfurization and denitrification technology) and Wet complexation absorption technology, etc. But these technologies are not yet very mature, most of them are in the demonstration stage, and have not yet achieved large-scale industrial application. Although preliminary progress has been made in the research on the integrated control technology of coal-fired flue gas pollutants, it still takes time before industrial application, and key technical issues such as system design, process control, and technology integration need to be solved. the

Contents of the invention

The purpose of this utility model is to provide a device that uses Venturi spray combined with wet static electricity to simultaneously remove various pollutants such as dust, _SO2 and NOx in the flue gas of coal-fired industrial boilers, so as to solve the problem of large investment in the prior art. , low operating efficiency, and difficulty in promotion and application.

A coal-fired industrial boiler flue gas treatment device, including a Venturi spray reactor, a wet electrostatic reactor, a high-voltage power supply, an absorbent circulation pool, an induced draft fan, a chimney, and an absorbent bin,

The Venturi spray reactor includes a constriction tube, a throat and a diffuser tube. A plurality of absorbent nozzles, preferably four, are evenly arranged around the throat at the entrance of the throat. The length of the throat is preferably 1 to 1.2 times the diameter of the throat. The contraction angle of the shrink tube is preferably 25-30°, and the divergence angle of the diffuser tube is preferably 6-8°. The Venturi spray reactor is preferably arranged horizontally. the

The wet electrostatic reactor includes a shell, the upper part of the shell is provided with an air outlet, and the lower part of the shell is provided with an air inlet. The interior of the housing is composed of a plurality of unit discharge channels. An insulating plate is arranged above the discharge channel of the unit and higher than the gas outlet, and an insulator is arranged above the insulating plate, and the insulating plate is used to isolate the insulator from the flue gas. The bottom of the housing is provided with an ash hopper and a water outlet. The water outlet is connected to the absorbent circulation pool. The wet electrostatic reactor is preferably arranged vertically. the

Each unit discharge channel includes a discharge electrode plate and a discharge electrode, the discharge electrode is arranged in the center of the discharge channel, and the discharge electrode plate constitutes the channel wall of the discharge unit. The discharge electrode plate is grounded, and the discharge electrode is connected to the negative high voltage of the high voltage power supply. the

As a preferred solution, the discharge electrode plate is a stainless steel plate, and a water spray pipe is arranged above the discharge electrode plate. The material of the water spray pipe is PPR, with a diameter of 6-8 mm. Water spray ports are set every 100 mm directly below the water spray pipe, and the water spray ports are 10 mm higher than the discharge plate. The discharge electrode is a stainless steel tube with a diameter of 6-8 mm, a helix wound on the surface of the stainless steel tube, the pitch of the helix is 25 mm, and the diameter of the helix is 2-3 mm. the

The unit discharge channel is preferably a square with a side length of 300-400 mm or a circle with a diameter of 300-400 mm. The cross-sectional area of the wet electrostatic reactor can be determined according to the amount of flue gas to be treated and the flue gas flow rate in the unit channel. The flue gas flow rate in the unit channel is generally controlled at 0.2-0.4m/s. the

As a preference, the upper part of the air inlet of the wet electrostatic reactor can be provided with a porous air distribution plate. the

The diffusion pipe of the Venturi sprayer is connected with the air inlet of the wet electrostatic reactor, and the air outlet of the wet electrostatic reactor is connected with the induced draft fan and the chimney in sequence. the

The absorbent circulation pool is connected with the absorbent nozzle of the Venturi sprayer, and the absorbent circulation pool is connected with the absorbent bin. the

The coal-fired industrial boiler flue gas to be treated enters the Venturi spray reactor from the boiler, and the flow velocity gradually increases after passing through the shrinking tube to form a high-speed flowing gas. The absorbent from the absorbent circulation pool is evenly distributed along the periphery of the throat pipe When the nozzle enters, the absorbent droplets are atomized and accelerated by the high-speed flue gas flow in the throat, and there is an inertial collision between the absorbent droplets and the dust particles to achieve the initial agglomeration of the dust; in the diffuser pipe, the air velocity decreases And the pressure rises, so that the condensation speed of the dust particles as the condensation nuclei is accelerated, and the dust-containing droplets with a larger diameter are formed, which greatly facilitates the collection and removal. At the same time, due to the reduction of flue gas flow rate and the increase of residence time, the absorption reaction between SO ₂ and droplets will be further strengthened, and the removal efficiency of SO ₂ will be further improved. After the flue gas passes through the Venturi sprayer, the large liquid droplets flow into the ash hopper at the bottom of the wet electrostatic reactor under the action of gravity settling. The tiny dusty droplets are negatively charged when they pass through the cell discharge channel, and move toward the discharge plate under the action of the electric field force, and are finally captured by the discharge plate. The liquid droplets collected during the discharge process flow into the ash hopper along the discharge electrode plate from top to bottom, and finally collect and discharge at the water outlet, flow into the absorbent circulation pool and perform water sealing. At the same time, the mass transfer and absorption reaction between _SO2 and the droplets in the wet electrostatic reactor is still going on, and the dust in the droplets has a catalytic oxidation effect on sulfite, which can further improve the absorption effect of _SO2 . In addition, the corona discharge process under high humidity can produce more oxidative radicals OH, HO _2, etc., which can oxidize NO in the flue gas into NO ₂ , HNO ₂ and HNO ₃ , and the dust in the droplets has Catalytic oxidation can promote the absorption of these oxidized substances by droplets, and finally realize the effective removal of NOx. In this way, the simultaneous removal of dust, SO ₂ and NOx is realized.

In a Venturi spray reactor, the flue gas flow at the throat can effectively atomize the liquid absorbent, and the atomization effect depends on the flow velocity of the flue gas at the throat. The greater the flue gas velocity, the better the atomization effect. But the resistance also increases at the same time, so considering the practical application, the flue gas flow velocity at the throat is generally 90-110m/s. In addition, in order to obtain efficient dust capture and _SO2 absorption effect, the injected amount of absorbent is very important. According to the traditional wet flue gas desulfurization technology, the injected amount of absorbent described in the utility model is liquid The gas ratio is controlled at 8-15L/m ³ .

In the wet electrostatic reactor, the cross-sectional area of the reactor can be determined according to the amount of flue gas to be treated and the flue gas flow rate. In order to obtain a better droplet collection effect, compared with the traditional dry electrostatic precipitator, it needs to be reduced The flue gas flow rate of the wet electrostatic reactor, so the flue gas flow rate described in the utility model is controlled at 0.2-0.4m/s. In the utility model, because more liquid absorbent is injected into the Venturi spray reactor, a thin liquid film can be formed on the discharge electrode plate in the wet electrostatic reactor, which is helpful for the absorption of SO ₂ and NOx , At the same time, this can avoid the occurrence of problems such as dust back-mixing and anti-corona in dry electrostatic precipitator, and improve the removal of fine particles. Since the long-term operation of the dust particles will stick to the discharge electrode plate and affect the corona discharge, so a water spray pipe is arranged above the discharge electrode plate to regularly spray water on the electrode plate for cleaning. The cleaning method adopts high-flow intermittent water spray cleaning, the water spray volume is 3-4kg/(m ³ .h), and the water supply pressure is 0.2-0.3MPa.

The discharge electrode plate in the shell of the wet electrostatic reactor adopts a square or circular structure, which is compact in structure, easy to process, and the reactor is easy to enlarge to adapt to different boiler capacities; the discharge electrode in the shell of the wet electrostatic reactor adopts a stainless steel tube wound with a spiral wire. This is because: due to the high humidity in the discharge space, spark discharge is prone to occur during discharge, resulting in an overall drop in discharge voltage, thereby reducing the defogging effect, so it is not suitable to use conventional prickly electrodes. The helical discharge electrode is not easy to break down, and can increase the discharge voltage, thereby improving the collection effect of droplets. The discharge plate and the discharge electrode operate under the state of condensation, in order to prevent the corrosion of SO ₂ and NOx and ensure stable operation, the materials of the discharge plate and the discharge electrode are all stainless steel.

The device of the utility model realizes the simultaneous removal of multiple pollutants dust, _SO2 and NOx in the flue gas of coal-fired boilers by using composite technology, which greatly saves flue gas purification investment and operating costs, and the process is simple and reliable; and the flue gas pollutants The removal efficiency is high, among which the removal efficiency of dust can reach more than 99%, the removal efficiency of _SO2 can reach more than 95%, and the removal efficiency of NOx can reach about 50%, which adapts to the development trend of the field of flue gas purification.

Description of drawings

Fig. 1 is the technological process diagram that adopts the utility model device. the

Fig. 2 is a structural schematic diagram of a venturi sprayer and a wet electrostatic reactor of the utility model device. the

Fig. 3 is a layout diagram of the unit discharge channel and the water spray pipe on the discharge electrode plate in the wet electrostatic reactor. the

Fig. 4 is a structural schematic diagram of the helical discharge electrode of the wet electrostatic reactor in the device of the present invention. the

Explanation of each reference sign in the figure:

1- Boiler 2- Venturi spray reactor 3- Wet electrostatic reactor 4- High voltage power supply

5-Absorbent circulating pool 6-Induced fan 7-Chimney 8-Absorbent warehouse

9-shrink tube 10-throat tube 11-diffusion tube 12-housing

13-Inlet 14-Outlet 15-Discharge plate 16-Discharge electrode

17-Water spray pipe 18-Ash hopper 19-Even air distribution plate 20-Water outlet

21-Insulator 22-Insulation plate 23-Discharge channel 24-Helix

Detailed ways

The coal-fired industrial boiler flue gas treatment device shown in Figure 1 includes a Venturi spray reactor 2, a wet electrostatic reactor 3, a high-voltage power supply 4, an absorbent circulation pool 5, an induced draft fan 6, a chimney 7, and an absorbent warehouse 8 . Venturi spray reactor 2, wet electrostatic reactor 3, induced draft fan 6 and chimney 7 are connected in sequence, high voltage power supply 4 is connected with wet electrostatic reactor 3, absorbent circulation pool 5 is connected with the lower part of wet electrostatic reactor 3 through pipelines . the

The Venturi spray composite wet electrostatic reactor is shown in FIG. 2 , which includes a horizontally arranged Venturi spray reactor 2 and a vertically arranged wet electrostatic reactor 3 . The Venturi spray reactor 2 is composed of a shrinkage pipe 9 , a throat pipe 10 and a diffuser pipe 11 . The shrinkage angle of the shrink tube 9 is 25-30°. The flue gas velocity in the throat pipe 10 is controlled at 90-110m/s, the length of the throat pipe 10 is 1-1.2 times the diameter of the throat pipe, and four nozzles are evenly arranged around the entrance of the throat pipe 10 . The diffusion angle of the diffusion pipe 11 is 6-8°. the

Described wet electrostatic reactor 3 comprises shell 12, and shell 12 bottom is provided with air inlet 13, and air inlet 13 is connected with the diffusion pipe 11 of Venturi sprayer, and the length of connection section is more than 2m. The upper part of the casing is provided with an air outlet 14, and the air outlet 14 is connected with the induced draft fan 6 and the chimney 7 in sequence. At the same time, the upper part of the air inlet 13 is provided with a porous airflow uniform distribution plate 19, and the opening ratio is 30-50%. the

As shown in Figure 3, the interior of the housing 12 is composed of multiple unit discharge channels 23, which can be enlarged according to the size of the flue gas volume and the requirements for pollutant removal. The unit discharge channel 23 is a square or a circle, and the side length of the square or the diameter of the circle is 300-400 mm. The flue gas velocity in the unit discharge channel 23 is controlled at 0.2-0.4m/s. The unit discharge channel 23 is made up of the discharge electrode plate 15 and the discharge electrode 16, the discharge electrode 16 is arranged at the center of the discharge channel, and the discharge electrode plate 15 constitutes the unit discharge channel wall. The discharge electrode plate 15 is grounded, and the discharge electrode 16 is connected to the negative high voltage of the high voltage power supply to form a negative corona. The insulator 21 is arranged on the top of the wet electrostatic reactor 3 and is isolated from the outlet flue gas by an insulating plate 22 . The droplets collected during the corona discharge flow along the discharge plate 15 from top to bottom, flow into the ash hopper 18 of the wet electrostatic reactor 3, and finally collect at the water outlet 20, flow into the absorbent circulation pool 5 and perform water sealing . the

The top of the discharge electrode plate 15 is provided with a water spray pipe 17, and the water spray pipe 17 regularly sprays water to clean the pole plate. The layout of the spray pipes is shown in Figure 3. Water spray pipe 17 material is PPR, and diameter is 6～8mm. Spray pipe 17 just below offers water spout every 100mm, and higher 10mm than discharge electrode plate 15. Since the dust particles will stick to the discharge electrode plate after long-term operation, a water spray pipe is arranged above the discharge electrode plate, and water is regularly sprayed on the electrode plate for cleaning. The cleaning method adopts high-flow intermittent water spray cleaning, the water spray volume is 3-4kg/(m ³ .h), and the water supply pressure is 0.2-0.3MPa.

As shown in Fig. 4, the discharge electrode 16 is a stainless steel tube, and the diameter of the stainless steel tube is 6-8mm. The surface of the stainless steel pipe is wound with helical wires 24, the distance between the helical wires 24 is 25 mm, and the diameter of the helical wires 24 is 2-3 mm. Due to the high humidity in the discharge space, the helical discharge electrode is used, which is not easy to break down during discharge, and can increase the discharge voltage, thereby improving the collection effect of droplets. the

The water outlet (20) of the wet electrostatic reactor 3 is connected to the absorbent circulation pool 5, and the absorbent circulation pool 5 replenishes the absorbent regularly through the absorbent bin 8. the

The flue gas coming out from the boiler 1 first enters the Venturi spray reactor 2, and the flue gas is raised in the shrinkage tube 9 of the Venturi sprayer 2, and the high-speed flowing flue gas atomizes the injected absorbent in the throat pipe 10, Acceleration, after the flue gas collides with the atomized absorbent droplets, it realizes the preliminary settlement of dust and the preliminary removal of SO ₂ . Afterwards, the flue gas enters the wet electrostatic reactor 3 through the diffusion pipe 11 of the Venturi sprayer 2, and the large liquid droplets flow into the ash hopper 18 at the bottom of the wet electrostatic reactor 3 under the action of gravity settling. The discharge electrode plate 15 is grounded, and the discharge electrode 16 is connected to negative high voltage. The fine dusty droplets are charged with negative charges when passing through the discharge channel 23, and move toward the discharge electrode plate 15 under the action of the electric field force, and are finally captured by the discharge electrode plate 15, and flow into the discharge electrode plate 15 from top to bottom. The ash hopper 18 is finally collected and discharged to the absorbent circulation pool 5 at the water outlet 20 . The absorbent bin 8 replenishes absorbent to the absorbent circulation pool 5 on a regular basis. At the same time, the mass transfer and absorption reaction between _SO2 and the liquid droplets in the wet electrostatic reactor 3 is still going on, and the dust in the liquid droplets has a catalytic oxidation effect on sulfite, which can further improve the absorption effect of _SO2 . In addition, the corona discharge process under high humidity can produce more oxidative radicals OH, HO _2, etc., which can oxidize NO in the flue gas into NO ₂ , HNO ₂ and HNO ₃ , and the dust in the droplets has Catalytic oxidation can promote the absorption of these oxidized substances by droplets to achieve the removal of _NOx . Finally, the purified flue gas passes through the induced draft fan 6 and is discharged from the chimney 7 at last.

Application example 1

Using the removal method shown in Figure 1, the flue gas velocity in the throat is controlled at 100m/s, and the flue gas velocity in the channel of the wet electrostatic reactor is 0.3m/s. Treating 3000m ³ /h of coal-fired industrial boiler flue gas, using NaOH lye as the absorbent, applying 55kV DC high voltage, monitored by the environmental protection department, the dust removal efficiency is 99.15%, the desulfurization efficiency is 96.91%, and the denitrification efficiency is 47.57%.

Claims (10)

1. coal-burned industrial boiler flue gas processing device comprises venturi spray reactor (2), wet electrostatic reactor (3), high voltage source (4), absorbent circulatory pool (5), air-introduced machine (6), chimney (7) and absorbent storehouse (8), it is characterized in that:

Described venturi spray reactor (2) comprises collapsible tube (9), trunnion (10) and anemostat (11), and the porch of described trunnion (10) is provided with the absorbent nozzle along the periphery of trunnion (10);

Described wet electrostatic reactor (3) comprises housing (12), and the upper and lower of described housing (12) is respectively equipped with gas outlet (14) and air inlet (13); The inside of described housing (12) is provided with some cell discharge passages (23), and described cell discharge passage (23) top is provided with insulation board (22), and described insulation board (22) top is provided with insulator (21); The bottom of described housing (12) is provided with ash bucket (18) and delivery port (20);

The anemostat (11) of described venturi spray reactor (2) is connected with the air inlet (13) of wet electrostatic reactor (3); The gas outlet (14) of described wet electrostatic reactor (3) is connected with air-introduced machine (6), chimney (7) successively, and described delivery port (20) is connected with absorbent circulatory pool (5).

2. coal-burned industrial boiler flue gas processing device as claimed in claim 1 is characterized in that: the top of the air inlet (13) of described wet electrostatic reactor (3) is provided with porous airflow uniform distribution plate (19).

3. coal-burned industrial boiler flue gas processing device as claimed in claim 1; It is characterized in that: described cell discharge passage (23) comprises discharge plate (15) and sparking electrode (16); Described sparking electrode (16) is located at the center of cell discharge passage (23), and described discharge plate (15) constitutes the cell discharge conduit wall; Described discharge plate (15) ground connection, described sparking electrode (16) connects the negative high voltage of high voltage source (4).

4. coal-burned industrial boiler flue gas processing device as claimed in claim 1 is characterized in that: described venturi spray reactor (2) horizontal arrangement, described wet electrostatic reactor (3) is vertical to be arranged.

5. coal-burned industrial boiler flue gas processing device as claimed in claim 1 is characterized in that: described absorbent nozzle has 4.

6. coal-burned industrial boiler flue gas processing device as claimed in claim 1 is characterized in that: the length of described trunnion (10) is 1～1.2 times of trunnion (10) diameter.

7. coal-burned industrial boiler flue gas processing device as claimed in claim 1 is characterized in that: the angle of throat of described collapsible tube (9) is 25～30 °.

8. coal-burned industrial boiler flue gas processing device as claimed in claim 1 is characterized in that: the angle of flare of described anemostat (11) is 6～8 °.

9. coal-burned industrial boiler flue gas processing device as claimed in claim 1 is characterized in that: described cell discharge passage (23) is the square of 300～400mm or the circle of diameter 300～400mm for the length of side.

10. coal-burned industrial boiler flue gas processing device as claimed in claim 3 is characterized in that: described discharge plate (15) is a stainless-steel sheet, and discharge plate (15) top is furnished with sparge pipe (17); Described sparking electrode (16) is a stainless steel tube, and the stainless steel tube diameter is 6～8mm; Stainless steel pipe surface winding screw line (24), helix (24) spacing 25mm, helix (24) diameter 2～3mm.

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