Comprehensive deep treatment system for dust fall and white smoke elimination of tail gas

Abstract

The invention is suitable for the technical field of tail gas treatment, and particularly relates to a tail gas dust falling and white smoke eliminating comprehensive deep treatment system which comprises a dust falling subsystem and a white smoke eliminating subsystem, the dust falling subsystem comprises a washing tower, and a tempering reactor is arranged at the bottom of an inner cavity of the washing tower; a special-shaped demister is arranged at the position, located above the tempering reactor, in the washing tower, a water collector is arranged above the special-shaped demister, a three-stage ridge demister is arranged above the water collector, the washing tower is connected with a white smoke elimination subsystem, and the white smoke elimination subsystem condenses, defogs and heats tail gas from the washing tower to eliminate the tail gas in the tail gas. The treated tail gas is discharged from the top of the washing tower. The device integrates the characteristics of a heating technology and a condensation technology, is slightly influenced and restricted by external conditions such as environment temperature and relative humidity, is wide in application range and relatively low in cost, and gives consideration to elimination of sensory pollution of colored smoke plume and guarantee of thermal lifting and diffusion effects of pollutants on the premise of guaranteeing a certain pollutant emission reduction effect.

Description

Technical Field

[0001] The invention belongs to the technical field of tail gas treatment, and in particular relates to a tail gas dust reduction and de-dusting comprehensive deep treatment system. Background Art

[0002] Tail gas dust reduction and white smoke elimination technology refers to the process of removing particulate matter in tail gas, reducing pollutant concentration, and eliminating the "white smoke" phenomenon through a series of physical and chemical methods during the treatment of industrial exhaust gas. "White smoke" is actually a large amount of water vapor carried in the tail gas that condenses when it is cold and forms mist droplets, which often carry fine particulate matter and pollutants. By adopting efficient dust removal devices, wet desulfurization systems, flue gas reheating technology, and advanced spray absorption measures, the emission of particulate matter in tail gas can be effectively reduced, and the appearance of white smoke can be avoided by controlling the temperature and humidity of the flue gas, thereby meeting environmental emission standards and improving the quality of the atmospheric environment.

[0003] However, the conventional technology generally adopts spray absorption and other methods to eliminate the whitening, but the effect is not ideal, and the exhaust gas is prone to not meet the standards. Summary of the invention

[0004] The purpose of the present invention is to provide a comprehensive deep treatment system for exhaust gas dust reduction and de-dusting, aiming to solve the problem that the existing technology generally adopts methods such as spraying absorption for de-dusting, but the effect is not ideal and the exhaust gas is prone to substandard.

[0005] The present invention is implemented in this way: a tail gas dust reduction and whitening comprehensive deep treatment system, the system comprising:

[0006] A dust reduction subsystem and a de-whitening subsystem, wherein the dust reduction subsystem comprises a washing tower, a tempering reactor is arranged at the bottom of the inner cavity of the washing tower, a special demister is arranged at a position above the tempering reactor inside the washing tower, a water collector is arranged above the special demister, a three-stage ridge demister is arranged above the water collector, the three-stage ridge demister has a flushing device, a spray assembly is arranged above the tempering reactor, the washing tower is connected to the de-whitening subsystem, the de-whitening subsystem completes the de-whitening treatment of the exhaust gas by condensing, demisting and heating the exhaust gas from the washing tower, the exhaust gas after de-whitening treatment returns to the flue above the washing tower, and the treated exhaust gas is discharged from the flue above the top of the washing tower.

[0007] Preferably, the dedusting subsystem includes a condenser, a flue demister and a heater. The exhaust gas that has been subjected to dust reduction treatment in the washing tower enters the condenser, and is condensed by the condenser. The condensed exhaust gas enters the flue demister, and is defogged by the flue demister. The defogged exhaust gas is input to the heater through a booster fan, and the heater heats the exhaust gas and sends the heated exhaust gas back to the flue above the top of the washing tower for discharge.

[0008] Preferably, the exhaust gas dust reduction and whitening comprehensive deep treatment system also includes a washing liquid circulation subsystem. A liquid storage layer is provided at the bottom of the inner cavity of the washing tower. The liquid storage layer is used to store washing liquid. The washing liquid circulation subsystem extracts the washing liquid in the liquid storage layer and transports it to the spray assembly above the tempering reactor.

[0009] Preferably, the exhaust gas dust reduction and whitening comprehensive deep treatment system also includes a flushing water circulation subsystem, the flushing water circulation subsystem includes a demister flushing water tank, the demister flushing water tank is used to store condensed water generated from the whitening subsystem, the flushing water circulation subsystem is used to flush the three-stage roof ridge demister, the flushing water after flushing is recovered through the water collector, and the recovered flushing water is returned to the demister flushing water tank again.

[0010] Preferably, a liquid level meter is provided at the bottom of the inner cavity of the washing tower, and the washing liquid is monitored by the liquid level meter. When the water level of the washing liquid in the liquid storage layer is lower than a preset value, the washing liquid is transported to the liquid storage layer through the flushing water circulation subsystem.

[0011] Preferably, the number of the conditioning reactors is at least one group, and multiple groups of conditioning reactors are arranged up and down in the washing tower.

[0012] Preferably, the descaling subsystem comprises a condensate water tank, which is used to store condensate water, and the condensate water tank is connected to the flushing water circulation subsystem.

[0013] Preferably, the condensers are provided in multiple groups, and the multiple groups of condensers are arranged in series, and the flow direction of cooling water in the condensers is opposite to the flow direction of the exhaust gas.

[0014] Preferably, the heaters are provided in multiple groups, and the multiple groups of heaters are arranged in series, and the flow direction of the hot water in the heaters is opposite to the flow direction of the exhaust gas.

[0015] Preferably, a densitometer is provided at the bottom of the washing tower, and when the density of the liquid in the washing tower is greater than a preset value, it is discharged.

[0016] The exhaust gas dust reduction and whitening comprehensive deep treatment system provided by the present invention first cools down and condenses the exhaust gas, and then heats the defogged exhaust gas before discharging it. The condensation and reheating technology combines the characteristics of the heating technology and the condensation technology, is less affected by external conditions such as ambient temperature and relative humidity, has a wide range of applications, and is relatively low in cost. While ensuring a certain pollutant emission reduction effect, it takes into account the elimination of sensory pollution of colored smoke plumes and ensures the thermal lifting and diffusion effect of pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of the dust reduction part of a tail gas dust reduction and whitening comprehensive deep treatment system provided by an embodiment of the present invention;

[0018] Figure 2 A schematic structural diagram of the whitening part of a comprehensive deep treatment system for exhaust gas dust reduction and whitening provided in an embodiment of the present invention.

[0019] Figure numerals: 1. Scrubber; 2. Tempering reactor; 3. Spray assembly; 4. Special demister; 5. Water collector; 6. Three-stage roof demister; 7. demister flushing water tank; 8. Condensate water tank; 9. Booster fan; 10. Heater; 11. Condenser; 12. Flue demister. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0021] like Figure 1 The figure is a schematic diagram of the dust reduction structure of a tail gas dust reduction and whitening comprehensive deep treatment system provided by an embodiment of the present invention, and the system includes:

[0022] A dust reduction subsystem and a whitening subsystem, wherein the dust reduction subsystem comprises a washing tower 1, a tempering reactor 2 is arranged at the bottom of the inner cavity of the washing tower 1, a special demister 4 is arranged at a position above the tempering reactor 2 inside the washing tower 1, a water collector 5 is arranged above the special demister 4, a three-stage ridge demister 6 is arranged above the water collector 5, the three-stage ridge demister 6 has a flushing device, a spray assembly 3 is arranged above the tempering reactor 2, the washing tower 1 is connected to the whitening subsystem, the whitening subsystem completes the whitening treatment of the exhaust gas from the washing tower 1 by condensing, defogging and heating the exhaust gas, the exhaust gas after the whitening treatment returns to the flue above the washing tower 1 again, and the treated exhaust gas is discharged from the flue above the top of the washing tower 1.

[0023] The deduster subsystem includes a condenser 11, a flue demister 12 and a heater 10. The exhaust gas that has been subjected to dust reduction treatment in the washing tower 1 enters the condenser 11, is condensed by the condenser 11, and the condensed exhaust gas enters the flue demister 12, is defogged by the flue demister 12, and the defogged exhaust gas is input to the heater 10 through the booster fan 9. The heater 10 heats the exhaust gas and sends the heated exhaust gas back to the flue above the top of the washing tower 1 for discharge.

[0024] In this embodiment, the exhaust gas dust reduction and whitening comprehensive deep treatment system includes a dust reduction subsystem and a whitening subsystem. The exhaust gas in this system is industrial exhaust gas, which contains a lot of impurities (fluorine, escaped ammonia, SO2, particulate matter, etc.), and needs to adopt flue gas condensation reheating technology, which is a combination of flue gas condensation technology and heating technology. Its wet smoke plume elimination mechanism is to reduce the absolute moisture content in the wet flue gas by cooling, so that the saturated water vapor in the flue gas precipitates into condensed water, and at the same time reduces the emission of soluble salts and condensable particulate matter in the flue gas; then heat the flue gas to reduce the relative moisture content of the wet flue gas, thereby further eliminating the visual "colored" smoke plume and ensuring the thermal lifting and diffusion height of the flue gas.

[0025] The main components of the system are a condenser 11, a washing liquid circulation subsystem, a flushing water circulation subsystem, a demister (including a special demister, a three-stage roof demister and a flue demister), a tempering reactor 2, and a heater 10 (the heater 10 is equipped with a hot water system). In the present invention, the industrial exhaust gas enters from the bottom of the washing tower 1. Since the temperature of the industrial exhaust gas is relatively high, it will gradually rise. During the rising process, it will first pass through the three-layer tempering reactor 2. During this process, the tempering reactor 2 is continuously sprayed by the spray component 3. The exhaust gas that has been sprayed and tempered rises further and passes through the special demister 4 for the first defog operation. The exhaust gas dust reduction and whitening comprehensive deep treatment system also includes a washing liquid circulation subsystem. A liquid storage layer is provided at the bottom of the inner cavity of the washing tower 1. The liquid storage layer is used to store washing liquid. The washing liquid circulation subsystem extracts the washing liquid in the liquid storage layer and transports it to the tempering reactor 2. The spray assembly 3 above, then the washing liquid in the washing liquid circulation subsystem will enter the liquid storage layer under the action of its own weight, so as to be recycled. After the exhaust gas has passed the first defog operation, it will rise again to the three-stage roof ridge demister 6 for a flushing defog operation. The exhaust gas dust reduction and de-whitening comprehensive deep treatment system also includes a flushing water circulation subsystem. The flushing water circulation subsystem includes a defogger flushing water tank 7. The defogger flushing water tank 7 stores the condensed water generated from the de-whitening subsystem. The flushing water circulation subsystem is used to flush the three-stage roof ridge demister 6. The flushing water after flushing is recovered through the water collector 5, and the recovered water returns to the defogger flushing water tank again. 7, so as to circulate. When the water in the liquid storage layer is insufficient, the flushing water in the defogger flushing water tank 7 is introduced into the liquid storage layer for replenishment. The industrial tail gas is sprayed and defogged twice, and then it is exported to the de-whitening subsystem. In the de-whitening subsystem, the tail gas first enters the condenser 11. The condenser 11 is provided with multiple groups, and the multiple groups of condensers 11 are arranged in series. The flow direction of the cooling water in the condenser 11 is opposite to the flow direction of the tail gas. The condenser 11 contacts with the tail gas, and the moisture in the tail gas will condense and finally enter the condensation water tank 8. The condensation water tank 8 is connected to the defogger flushing water tank through the flushing water circulation subsystem. 7 is connected, and the exhaust gas passing through the condenser 11 enters the flue type demister 12 for the third defogger. The exhaust gas pressure after the third defogger is reduced. At this time, its pressure is increased by the booster fan 9 and it is transported to the heater 10. The heater 10 is provided with multiple groups, and the multiple groups of heaters 10 are arranged in series. The flow direction of the hot water in the heater 10 is opposite to the flow direction of the exhaust gas. The hot water in the heater 10 flows from top to bottom, and the exhaust gas is transported from bottom to top, and the two directions are opposite. After heating, the exhaust gas returns to the top flue of the washing tower 1 again and is emptied. At this time, the exhaust gas has undergone the two processes of dust reduction and whitening and meets the emission standards.

[0026] The high-efficiency conditioning reactor 2 uses the gas flow rate as the disturbance term, so that the liquid forms a multi-scale, heterogeneous, three-dimensional state in the gas flow. In this state, the gas and liquid mix, transfer mass and transfer heat, which greatly improves the gas-liquid mass and heat transfer contact time. The liquid film surface is constantly renewed, and the gas-liquid contact is sufficient. Compared with a simple spray reaction, it can greatly improve the efficiency of gas-liquid mass and heat transfer, simplify the system structure, reduce the investment cost and operating cost of the equipment, streamline the process and equipment, and improve the system reliability.

[0027] The flue gas enters from the bottom of the absorption tower, and the gas-liquid two-phase passes through the conditioning reactor 2 in reverse. The flue gas is dispersed into small streams on the high-efficiency mass transfer component and evenly distributed to the entire cross-section of the absorption tower. The slurry sprayed from the nozzle is sprayed from the upper part of the tower and falls on the conditioning reactor 2, where it contacts the flue gas. Some SO2, dust and other pollutants (ammonia, fluorine and fluoride) are captured by the droplets that flow down from the mesh of the conditioning reactor 2, or due to the inertial force of the airflow when changing direction, some coarse dust particles settle to the bottom of the tower and are captured by the bottom liquid film; while most of the ammonia, fine dust and flue gas enter the liquid film layer on the upper part of the conditioning reactor 2 through the small holes. The flue gas enters the liquid film layer at a high speed, stirring up a large number of bubbles. The formed liquid film can effectively increase the mass transfer surface area between the flue gas and the slurry. The flue gas is constantly disturbed by the bubbles under the inertia and diffusion, and changes direction, which increases the contact opportunities between fluorine and fluoride, dust, ammonia and liquid, and the gas is well purified. The air flow bubbles in the liquid layer, the fluid is violently turbulent, forming a gas-liquid contact interface, and the liquid falls from the small holes, completing the absorption of gaseous ammonia in the process.

[0028] The conditioning reactor 2 utilizes flue gas disturbance to tear and blow up the liquid on the conditioning part again, so that the unreacted liquid is updated to contact with the gas, which increases the liquid residence time, improves the liquid utilization rate, and increases the specific surface area of ​​gas-liquid contact. At the same time, it also greatly improves the gas-liquid reaction efficiency.

[0029] The conditioning reactor 2 is different from the tray and sieve plate. The main function of the high-efficiency mass transfer component is to use the flue gas to tear and disperse the sprayed slurry again, thereby improving the utilization rate of the slurry, indirectly increasing the gas-liquid contact time, increasing the residence time of the slurry in the reaction section, and increasing the specific surface area of ​​the slurry.

[0030] The conditioning reactor 2 is different from the rectifying effect of the tray. It has almost no liquid holding layer, and the resistance of a single device is only about 300Pa, which is lower than the resistance of one spray layer. If one spray layer is opened, the total resistance will be slightly reduced. The way the tray increases the desulfurization efficiency is to rectify the flue gas, increase the uniformity of the gas velocity in the reaction section, and increase the gas-liquid reaction at the opening of the tray. Since the gas-liquid reaction is on the membrane surface where the gas and liquid are in contact, the tray cannot significantly increase the reaction surface, and the improvement of the desulfurization efficiency is very limited. The mechanism of tray flue gas rectification is to rely on resistance to balance the flow rate. The resistance of a single-layer tray should be relatively around 600Pa.

[0031] By using the conditioning reactor 2, one or several circulating pumps are used to achieve near-zero emission levels, and the spray tower technology transformation can reduce the power consumption of the desulfurization reaction part by about 30%, saving energy and improving efficiency. It also improves the reliability and stability of the desulfurization system.

[0032] The tempering reactor 2 also has a very high dust removal efficiency. Since the high-efficiency tempering components increase the liquid-gas contact time, increase the specific surface area of ​​the slurry, and increase the residence time of the slurry in the flue gas, the slurry's ability to capture dust is increased, and the PM2.5 removal rate is as high as over 85%.

[0033] The setting of the conditioning reactor 2 also makes the operation and maintenance of the desulfurization tower more convenient. When inspecting and repairing components in a conventional spray tower, the slurry in the tower must be completely drained, and then a temporary maintenance platform must be built inside the tower for inspection and maintenance. However, with the high-efficiency conditioning component technology, the operation and maintenance personnel can directly stand on the high-efficiency conditioning component to maintain and repair the components in the tower, which greatly reduces the time for operation and maintenance and promotes the improvement of maintenance efficiency.

[0034] The conditioning reactor 2 disperses the flue gas and liquid flow into millions of turbulent chaotic states, stabilizes the impact of load fluctuations on the desulfurization system, smoothly reduces the fluctuation peaks of dust and other pollutant emissions, reduces the workload of operators, and reduces the environmental risks caused by fluctuation peaks.

[0035] The conditioning reactor 2 technology sets a special mass transfer element above the inlet flue or between the spray layers, so that the desulfurization slurry in the desulfurization tower and the flue gas are remixed above the reactor and in the reactor. The desulfurization slurry is converted into a widely distributed droplet group, forming a broad, heterogeneous mixing state, so that the desulfurized flue gas and the slurry can transfer mass and heat in the most complete state. The residence time of the desulfurization liquid is significantly increased, the gas-liquid contact time and the contact specific surface area are increased accordingly, and the desulfurization mass transfer rate and mass transfer efficiency are significantly improved. The desulfurization efficiency and dust removal efficiency are improved.

[0036] In the present invention, the tail gas enters the condenser 11, and the condenser 11 is installed vertically in multiple modules, and a multi-module layout is adopted. The tail gas flows from the top to the bottom in the condenser 11, which is conducive to the discharge of tail gas condensate into the condensate tank 8, and the condensate can be recycled for defogger flushing; a flue-type defogger 12 is installed at the rear end of the condenser 11, which is conducive to reducing the condensation mechanical water entering the rear end heater, effectively reducing the heating load and improving the demisting effect. The heater 10 is arranged on the upper part of the defog system, and a countercurrent heat transfer method is also adopted with the heating water. The heater 10 and the smoke exhaust sensor adopt an automatic control system to automatically adjust the hot water supply according to the climatic conditions, which can achieve the demisting effect and reduce the operating cost. The control system communicates with the DCS system in the control room to realize remote monitoring.

[0037] In the present invention, the liquid in the liquid storage layer arranged in the washing tower 1 will contain a large amount of dissolved matter after being used for a certain period of time. When the concentration rises to a certain value, it can be used as raw material, which greatly improves the utilization rate of raw materials, reduces waste emissions, and reduces the impact on the environment.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A comprehensive and deep treatment system for tail gas dust reduction and whitening, characterized in that: The system comprises: A dust reduction subsystem and a whitening subsystem, wherein the dust reduction subsystem comprises a washing tower (1), a conditioning reactor (2) is arranged at the bottom of the inner cavity of the washing tower (1), a special type demister (4) is arranged at a position above the conditioning reactor (2) inside the washing tower (1), a water collector (5) is arranged above the special type demister (4), a three-stage roof ridge demister (6) is arranged above the water collector (5), the three-stage roof ridge demister (6) is provided with a flushing device, a spray assembly (3) is arranged above the conditioning reactor (2), the flue above the washing tower (1) is connected to the whitening subsystem, the whitening subsystem completes the whitening treatment of the tail gas by condensing, demisting and heating the tail gas from the washing tower (1), the tail gas after the whitening treatment returns to the flue above the washing tower (1), and the treated tail gas is discharged from the flue above the washing tower (1).

2. The exhaust gas dust reduction and whitening comprehensive deep treatment system according to claim 1 is characterized in that: The deduster subsystem comprises a condenser (11), a flue demister (12) and a heater (10). The exhaust gas that has been subjected to dust reduction treatment in the scrubbing tower (1) enters the condenser (11), and is condensed by the condenser (11). The condensed exhaust gas enters the flue demister (12), and is defogged by the flue demister (12). The defogged exhaust gas is input to the heater (10) through a booster fan (9). The heater (10) heats the exhaust gas and sends the heated exhaust gas back to the flue above the scrubbing tower (1) for discharge.

3. The exhaust gas dust reduction and whitening comprehensive deep treatment system according to claim 1 is characterized in that: The exhaust gas dust reduction and whitening comprehensive deep treatment system also includes a washing liquid circulation subsystem. A liquid storage layer is provided at the bottom of the inner cavity of the washing tower (1). The liquid storage layer is used to store washing liquid. The washing liquid circulation subsystem extracts washing liquid from the liquid storage layer and transports it to the spray assembly (3) above the tempering reactor (2).

4. The exhaust gas dust reduction and whitening comprehensive deep treatment system according to claim 1 is characterized in that: The exhaust gas dust reduction and de-whitening comprehensive deep treatment system also includes a demister flushing water circulation subsystem, the demister flushing water circulation subsystem includes a demister flushing water tank (7), the demister flushing water tank (7) is used to store condensed water generated from the de-whitening subsystem, the demister flushing water circulation subsystem is used to flush the three-stage roof ridge demister (6), the flushing water after flushing is recovered through the water collector (5), and the recovered flushing water is returned to the demister flushing water tank (7) again.

5. The exhaust gas dust reduction and whitening comprehensive deep treatment system according to claim 1 is characterized in that: A liquid level meter is provided at the bottom of the inner cavity of the washing tower (1), and the washing liquid is monitored by the liquid level meter. When the washing liquid level in the liquid storage layer is lower than a preset value, water is replenished to the liquid storage layer through the mist flushing water circulation subsystem.

6. The exhaust gas dust reduction and whitening comprehensive deep treatment system according to claim 1 is characterized in that: The number of the conditioning reactors (2) is at least one group, and the conditioning reactors (2) are arranged up and down in the washing tower (1).

7. The exhaust gas dust reduction and whitening comprehensive deep treatment system according to claim 4 is characterized in that: The de-bleaching subsystem comprises a condensation water tank (8), which is used to store condensation water. The condensation water tank (8) is connected to the demister flushing water circulation subsystem.

8. The exhaust gas dust reduction and whitening comprehensive deep treatment system according to claim 2 is characterized in that: The condensers (11) are provided in multiple groups, and the multiple groups of condensers (11) are arranged in series. The flow direction of cooling water in the condensers (11) is opposite to the flow direction of the exhaust gas.

9. The exhaust gas dust reduction and whitening comprehensive deep treatment system according to claim 2 is characterized in that: The heaters (10) are provided in multiple groups, and the multiple groups of heaters (10) are arranged in series, and the flow direction of the hot water in the heaters (10) is opposite to the flow direction of the exhaust gas.

10. The exhaust gas dust reduction and whitening comprehensive deep treatment system according to claim 1 is characterized in that: A densitometer is provided at the bottom of the washing tower (1), and when the density of the liquid in the washing tower (1) is greater than a preset value, the liquid is discharged.

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