CN201105202Y - A device for synergistically removing fine particles in wet flue gas desulfurization - Google Patents

Abstract

A device for synergistically removing fine particles in flue gas wet desulfurization, including a desulfurization tower, a dust collector, a flue gas reheater, an induced draft fan, and a flue gas humidity adjustment chamber, a phase change condensation chamber, and a flue gas humidity adjustment chamber It is installed between the outlet of the dust collector and the flue gas inlet of the desulfurization tower, and the phase change condensation chamber is installed between the flue gas outlet of the desulfurization tower and the inlet of the flue gas reheater. The condensation chamber and the induced draft fan are located at the outlet of the flue gas reheater. The utility model has a simple process, as long as a flue gas humidity adjustment chamber and a phase change condensation chamber are added to the existing flue gas wet desulfurization device, and an appropriate amount of atomized hot water or steam is added, the wet desulfurization device can have simultaneous The effect of promoting the increase and removal of PM _2.5 particle size can be widely used in existing power plant flue gas wet desulfurization devices.

Description

A device for synergistically removing fine particles in wet flue gas desulfurization

1. Technical field

The utility model belongs to the technology for removing PM _2.5 particles in flue gas, in particular to a device for synergistically removing PM _2.5 by applying the principle of steam phase transition in flue gas wet desulfurization.

2. Background technology

Inhalable particulate matter is currently the primary pollutant in the urban air environment _{in China, especially PM 2.5 ,} which has an aerodynamic diameter of less than 2.5 μm. Carcinogens, which are difficult to be effectively captured by conventional dedusting technologies, such as wet desulfurization towers (including mist eliminators, scrubbers) have very low capture efficiency for PM _2.5 , but the removal efficiency for particles above 3-5 μm is high. up to 70-90% or more; Wang Hui of Tsinghua University and others tested the removal effect of WFGD on fine particles in flue gas by wet desulfurization system of a 300MW coal-fired power plant, and found that WFGD has a mass removal efficiency of 74.5% for PM ₁₀ , but for The removal efficiency of PM _2.5 is not high, and the removal efficiency decreases significantly with the decrease of particle size (Proceedings of the Chinese Society for Electrical Engineering, Vol. 27, 2007). Coal burning is the main reason for the increase of PM _2.5 content in China's atmospheric environment. Therefore, the control of coal-fired PM _2.5 emissions is a key issue that needs to be solved urgently. The main way of technological development is to install pretreatment measures in front of the dust removal equipment, so that they can grow into larger particles through physical or chemical action and then be removed; among them, the The combination of steam phase change pretreatment technology and existing coal-fired boiler flue gas wet desulfurization technology is one of the most important ways to realize engineering application. The mechanism of steam phase change to increase the size of particles is: in the supersaturated water vapor environment, the water vapor takes PM _2.5 particles as condensation nuclei to undergo phase change, which increases the particle size and mass, and produces the effects of diffusion swimming and thermophoresis at the same time. Promote particle migration, collision and contact with each other, and further promote PM _2.5 particles to condense and grow. At present, the flue gas wet desulfurization technology has become more and more mature and popular. In the desulfurization tower, the high-temperature flue gas is in contact with the medium-low temperature desulfurization liquid, and a strong heat and mass transfer process occurs. The high-temperature flue gas vaporizes part of the desulfurization absorption liquid. As the relative humidity of the flue gas increases, the temperature of the flue gas decreases and can approach a saturated state. However, in the existing flue gas wet desulfurization technology, the supersaturated water vapor environment required to realize the steam phase change cannot be achieved. Therefore, although the existing flue gas wet desulfurization technology can effectively remove SO ₂ and coarse dust, the capture efficiency of PM _2.5 is very low, causing a large amount of PM _2.5 to be discharged into the atmosphere.

3. Contents of utility model

Aiming at the above technical problems, the utility model provides a method that fully utilizes the characteristics of high moisture content in flue gas in the existing wet desulfurization technology, and uses the principle of steam phase transition to realize effective removal of SO ₂ by WFGD, and at the same time promote the condensation of PM _2.5 for a long time. Large and efficient removal device.

The technical solution of the utility model is: a device for realizing the method of synergistically removing PM _2.5 in wet flue gas desulfurization, including a desulfurization tower, a dust collector, a flue gas reheater, an induced draft fan, and a flue gas humidity adjustment chamber , The phase change condensation chamber, the flue gas humidity adjustment chamber is set between the outlet of the dust collector and the flue gas inlet of the desulfurization tower, and the phase change condensation chamber is set at the top outlet of the desulfurization tower. As a phase change condensing chamber, the outlet of the phase change condensing chamber is connected to the flue gas reheater, and the induced draft fan is installed at the outlet of the flue gas reheater; the desulfurization tower and the phase change condensing chamber are respectively equipped with a desulfurization tower demister and a phase change condensing chamber. Chamber demister. The phase change condensation chamber demister is a wire mesh demister, a baffle plate demister or a swirl plate demister, preferably a wire mesh demister. The desulfurization tower is a spray tower, packed tower or plate tower.

The technical solution of the utility model is to improve the existing coal-fired flue gas wet desulfurization device, add a flue gas humidity adjustment chamber and a phase change condensation chamber, so that it can simultaneously remove SO ₂ and promote PM _2.5 condensation growth and Efficient removal effect; it is characterized in that the flue gas humidity adjustment chamber is set between the outlet of the dust collector and the flue gas inlet of the desulfurization tower, and the phase change condensation chamber is set between the flue gas outlet of the desulfurization tower and the flue gas reheater. Increase the height of the desulfurization tower, use the top space of the desulfurization tower as a phase change condensation chamber; install a high-efficiency demister at the flue gas outlet of the phase change condensation chamber, and the lining of the phase change condensation chamber has low surface energy that enhances the phase change effect and anti-corrosion dual effects Material.

According to the utility model, the method of synergistically removing PM _2.5 by applying the principle of steam phase change in wet desulfurization of flue gas is as follows: the dusty flue gas from the coal-fired boiler is removed by a dust collector (such as an electrostatic precipitator) to remove coarse particles and then enters the flue gas. In the air humidity control room, spray fine hot water mist with a particle size of 20-30 μm, use the heat of the flue gas to vaporize the water mist or directly inject an appropriate amount of water vapor to increase the humidity of the flue gas from 5-12% to 20-50%, and then from The bottom of the desulfurization tower enters the desulfurization tower. In the desulfurization tower, the high-temperature and wet flue gas contacts with the medium and low temperature absorption liquid countercurrently. The flue gas is humidified and cooled, and reaches a supersaturated state in the middle and upper part of the desulfurization tower. The supersaturated water vapor takes PM _2.5 particles as condensation nuclei A phase change occurs to increase the particle size and quality of PM _2.5 particles, and then the condensed and grown dusty droplets are captured by the desulfurization liquid and the demister demister of the desulfurization tower. After the flue gas is desulfurized and partially PM _2.5 , it enters the phase change condensation chamber. In the phase change condensation chamber, an appropriate amount of water vapor is injected or a cooling device is installed to adjust the supersaturation of the flue gas, so that the unremoved PM _2.5 undergoes phase change condensation and grows up. The demister in the phase change condensation chamber removes the condensed and grown dusty droplets; the purified flue gas is heated by the flue gas reheater to 70-80°C and discharged from the chimney.

The flue gas temperature at the inlet of the desulfurization tower is 70-120°C, and the temperature of the absorbing liquid at the inlet of the desulfurization tower is 20-50°C, which is 30-80°C lower than that of the inlet flue gas.

Phase change condensation chamber demisters can be wire mesh eliminators, baffle plate demisters, swirl plate demisters, preferably wire mesh demisters; desulfurization towers are spray towers, packed towers, plate towers; smoke Gas wet desulfurization technology can be limestone-gypsum method, double alkali method, ammonia method, etc.

In order to improve the removal effect of PM _2.5 , a small amount can be added to the atomized hot water, water vapor or desulfurization absorption liquid, which can significantly reduce the critical supersaturation of water vapor nucleation and the surface tension of the aqueous solution, so that the particles are easily wetted by water Wetting agents generally belong to surfactants, such as sodium lauryl sulfate, fatty alcohol polyoxyethylene ether, or directly use commercially available wetting agents; wetting agents may contain various synergists or Auxiliaries, such as magnesium chloride, sodium sulfate, etc., the addition amount of wetting agent is generally 0.001-0.01% of the weight of the solution or water vapor.

The beneficial effects produced by the utility model are as follows: using steam phase change as a pretreatment technology for removing PM _2.5 , a supersaturated water vapor environment should be established first, but simply relying on adding steam or cooling means to make the flue gas supersaturated and energy consumption is too high, The utility model makes full use of the characteristics of high moisture content of the flue gas in the existing flue gas wet desulfurization device (for example, the relative humidity of the desulfurized purified gas can reach more than 90-95%, and the temperature is 40-60°C). Set up a flue gas humidity control room, increase the moisture content of the flue gas by spraying hot water or directly injecting an appropriate amount of steam, and promote part of the PM _2.5 to undergo a phase change and condense in the desulfurization tower to grow and be captured by the desulfurization liquid and the demister demister of the desulfurization tower . Install a phase change condensation chamber between the outlet of the desulfurization tower and the flue gas reheater or the top space of the desulfurization tower, inject a small amount of steam or cool the flue gas by 5-10°C to make the unremoved PM _2.5 particles condense and grow in the phase change condensation chamber , and the condensed and grown dusty droplets are removed by the demister. Using corrosion-resistant low surface energy materials as the wall or wall lining of the phase change condensation chamber, on the one hand, can promote the condensation of water vapor on the surface of PM _2.5 particles and inhibit its condensation on the wall of the phase change condensation chamber, thereby enhancing the phase change effect, and at the same time Solve corrosion problems caused by condensation of acidic pollutants. Add a small amount of wetting agent to reduce the water vapor supersaturation required for PM _2.5 condensation growth, and finally achieve efficient removal of PM _2.5 . The utility model has a simple process, as long as a flue gas humidity adjustment chamber and a phase change condensation chamber are added to the existing flue gas wet desulfurization device, and an appropriate amount of atomized hot water or steam is added, the wet desulfurization device can have simultaneous The effect of promoting the increase and removal of PM _2.5 particle size can be widely used in existing power plant flue gas wet desulfurization devices.

4. Description of drawings

Fig. 1 is the device structural representation of the utility model embodiment 1;

Fig. 2 is a schematic diagram of the device structure of Embodiment 2 of the present utility model.

In the figure: 1-dust collector; 2-flue gas humidity adjustment chamber; 3-atomized water nozzle; 4-flue gas reheater; 5-desulfurization tower; 6-desulfurization liquid nozzle; 8-Desulfurization liquid circulating pump; 9-Phase change condensation chamber; 10-Steam nozzle; 11-Phase change condensation chamber demister; 12-Induced fan.

5. Specific implementation

Example 1:

The method for synergistic removal of PM _2.5 in the wet flue gas desulfurization of the present invention is shown in Figure 1: the dusty flue gas produced by the coal-fired boiler is removed by a dust collector (such as an electrostatic precipitator) 1 to remove particles with a particle size ≥ 2.5 μm After the coarse particles enter the flue gas humidity adjustment chamber 2, atomized water droplets with a particle size of 20-30 μm are sprayed through the atomized water nozzle 3, and the atomized water droplets are completely evaporated in the humidity adjustment chamber 2 by using the heat of the flue gas. The amount of water added is determined by increasing the relative humidity of the flue gas from 5-12% to 20-50% after adjustment. The humidity-adjusted flue gas enters the desulfurization tower 5 from the lower part of the desulfurization tower, and in the desulfurization tower 5, the high-temperature wet flue gas (temperature: 70-120°C) contacts with the medium-low temperature desulfurization absorption liquid (temperature: 20-50°C) countercurrently, and the high temperature The flue gas vaporizes part of the absorption liquid, the relative humidity of the flue gas increases, the temperature of the flue gas decreases, and reaches a supersaturated state in the upper middle of the desulfurization tower 5. While desulfurization is completed, the supersaturated water vapor undergoes a phase change with PM _2.5 particles as condensation nuclei , to increase the particle size and quality of PM _2.5 particles, and the desulfurization liquid and the desulfurization tower demister 7 capture the condensed and grown dusty droplets, and remove about 40-60% of PM _2.5 particles; the characteristics of this process It is desulfurization and the condensation growth and removal of PM _2.5 at the same time, but when water vapor condenses on the surface of PM _2.5 particles, it will also condense on the surface of desulfurization droplets and be lost. After the flue gas is desulfurized and partially PM _2.5 , it enters the phase change condensation chamber 9 from the desulfurization tower 5, and injects an appropriate amount of steam through the steam nozzle 10 to make the unremoved PM _2.5 particles undergo phase change condensation and grow up, and is demister 11. Remove condensed and grown dusty droplets and remove about 40-60% of PM _2.5 . Add 0.001-0.01% wetting agent to the atomized hot water and water vapor to promote the condensation of water vapor on the surface of particles and reduce the critical supersaturation of water vapor where phase transition occurs. The purified flue gas is heated by the flue gas reheater 4 to 70-80°C, and then introduced into the chimney by the induced draft fan 12 and discharged into the atmosphere.

As shown in Figure 1, the device of the utility model for synergistically removing PM _2.5 in wet flue gas desulfurization mainly consists of a flue gas humidity adjustment chamber 2, a desulfurization tower 5, and a phase change condensation chamber 9; the flue gas humidity adjustment chamber 2. It is installed between the outlet of the dust collector 1 and the flue gas reheater 4. There is an atomized water nozzle 3 inside. The size of the flue gas humidity adjustment chamber 2 is such that the residence time of the flue gas in the adjustment chamber is longer than that required for the complete evaporation of the atomized water droplets. The time is determined; the phase-change condensation chamber 9 is placed between the outlet of the desulfurization tower 5 and the flue gas reheater 4, and a steam nozzle 10 is installed inside, and a high-efficiency demister 11 is installed at the outlet of the phase-change condensation chamber 9, and the inner layer is lined with corrosion-resistant Low surface energy material, the size of the phase change condensation chamber 9 is determined by the fact that the residence time of the flue gas in the condensation chamber is greater than the time required for the nucleation and condensation growth of water vapor on the surface of PM _2.5 particles (about 50-200ms).

Example 2:

As shown in Figure 2, the difference from Example 1 is that no phase change condensation chamber is specially provided, but the height of the desulfurization tower is appropriately increased, and the phase change is performed in the top space of the desulfurization tower 5 (that is, the part above the demister 7 of the desulfurization tower) The condensing chamber 9 is injected with an appropriate amount of steam, and a high-efficiency demister 11 is installed on the top of the tower. The purified flue gas at the tower outlet is heated by the flue gas reheater 4 and then discharged from the chimney.

Example 3:

A steam nozzle is installed in the flue gas humidity adjustment chamber 2, and an appropriate amount of steam is directly injected to adjust the moisture content of the flue gas, and the rest is the same as that of Embodiment 1 or 2.

Example 4:

The flue gas humidity adjustment chamber 2 is placed after the flue gas reheater 4, that is, between the outlet of the flue gas reheater 4 and the flue gas inlet of the desulfurization tower 5, and the rest is the same as that of Embodiment 3.

Example 5:

A flue gas cooling device is installed in the phase change condensation chamber 9 to cool the desulfurized and purified flue gas by 5°C to 10°C to make it reach a supersaturated state, and the rest are the same as in Embodiment 1.

Embodiment 6:

The flue gas is produced by a fully automatic coal-fired boiler with a flue gas volume of 100Nm ³ /h. The desulfurization tower adopts a spray tower with a diameter of 150mm and a height of 1500mm. The wet desulfurization technology is limestone-gypsum method, and the phase change condensation chamber is placed in the desulfurization tower Swirl plate demisters and wire mesh demisters are installed at the outlet, desulfurization tower and phase change condensation chamber respectively. The dust-laden flue gas produced by the coal-fired boiler enters the humidity control chamber after the coarse particles are removed by the cyclone dust collector, and the fine water mist with a temperature of 70 ° C and a particle size of about 20-30 μm is sprayed from the atomizing nozzle, and the injection volume is 0.025kg/Nm ³ flue gas, after adjustment, the flue gas temperature at the inlet of the desulfurization tower is 80°C, and the relative humidity is 35%; the temperature of the limestone desulfurization suspension is 20°C, the liquid-gas ratio is 2.5L/Nm ³ The gas is in countercurrent contact with the limestone suspension; through the online test of the electric low-pressure impactor ELPI, the mass removal efficiency of PM _2.5 is 42%; the flue gas enters the phase change condensation chamber after desulfurization and part of the PM _2.5 , and every Nm ³ flue gas is injected 0.015kg steam, PM _2.5 is removed twice, and the total mass removal efficiency of PM _2.5 reaches 86%.

Embodiment 7:

The desulfurization tower is a swirl plate tower with a diameter of 150mm and a height of 2000mm. The phase change condensation chamber is placed in the top space of the desulfurization tower. The flue gas wet desulfurization technology is a double alkali method, and the rest are the same as in Example 6; According to the test, the total mass removal efficiency of PM _2.5 reaches 82%.

Comparative example 1:

The test system of Example 6 and the limestone-gypsum desulfurization technology are adopted, but no water vapor and atomized water are added to the flue gas humidity adjustment chamber, and no steam is injected into the phase change condensation chamber _. The mass removal efficiency was 12%.

Comparative example 2:

The test system of Example 7 and the double-alkali desulfurization technology are adopted, but no water vapor and atomized water are added to the flue gas humidity adjustment chamber, no steam is injected into the phase change condensation chamber, and the quality of PM _2.5 is tested by an electric low-pressure impactor ELPI online test The removal efficiency was 17%.

Claims (5)

1. the fine grain device of cooperation-removal in the smoke-gas wet desulfurization, comprise desulfurizing tower (5), deduster (1), smoke re-heater (4), air-introduced machine (12), it is characterized in that also comprising smoke moisture conditioning chamber (2), phase transformation condensing chamber (9), the smoke moisture conditioning chamber is arranged between deduster (1) outlet and desulfurizing tower (5) gas approach, phase transformation condensing chamber (9) is located between desulfurizing tower (5) exhanst gas outlet and smoke re-heater (4) import, also can suitably increase the desulfurizing tower height, make the phase transformation condensing chamber with the desulfurizing tower headroom, air-introduced machine (12) is located at smoke re-heater (4) exit.

2. the fine grain device of cooperation-removal in the smoke-gas wet desulfurization according to claim 1 is characterized in that described phase transformation condensing chamber liner has the low-surface-energy material of promoting phase transformation effect and anticorrosion double effects, as polytetrafluoroethylene (PTFE).

3. the fine grain device of cooperation-removal in the smoke-gas wet desulfurization according to claim 1 is characterized in that being respectively equipped with in described desulfurizing tower and the phase transformation condensing chamber desulfurizing tower demister (7) and phase transformation condensing chamber demister (11).

4. the fine grain device of cooperation-removal in the flue gas warm therapy according to claim 3 desulfurization is characterized in that described demister is mesh mist eliminator, baffle plate demister or eddy flow plate demister.

5. the fine grain device of cooperation-removal in the smoke-gas wet desulfurization according to claim 3 is characterized in that described demister is a mesh mist eliminator.

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