Flue gas pretreatment system for biomass blending combustion boiler

Abstract

The invention discloses a flue gas pretreatment system for a biomass blending combustion boiler, and belongs to the technical field of environmental protection. The device comprises a flue gas washing tower, a flue gas detergent preparation tank and a slurry treatment system, a flue inlet channel is arranged on the lower portion of the side wall of the flue gas washing tower, a flue gas outlet is formed in the top of the flue gas washing tower, and a rotational flow guide plate, a first spraying washing pipe, a turbulent flow washing assembly, a baffle plate demister and a superfine demister are sequentially installed in the flue gas washing tower from bottom to top. The rotational flow guide plate is located above the inlet flue, a slurry outlet of the flue gas washing tower is communicated with the first spraying washing pipe, the turbulent flow washing assembly and the slurry treatment system through a slurry main pipeline and branch slurry pipelines, and the flue gas washing agent preparation tank is communicated with the branch slurry pipelines. And the flue gas detergent preparation tank pumps a flue gas detergent into the first spray washing pipe and the turbulent flow washing assembly. According to the invention, the biomass blending combustion flue gas is subjected to multi-stage cooperative treatment, so that harmful substances in the flue gas are removed, and the flue gas is more suitable for ammonia desulfurization.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection and relates to a flue gas pretreatment system for a biomass-blended boiler. Background Art

[0002] Biomass co-firing technology, due to its low cost and ease of implementation, is considered an effective way to rapidly reduce carbon emissions from the coal-fired power generation industry. By reducing reliance on fossil fuels, this technology provides crucial support for the transition to a zero-carbon energy system. However, the biomass co-firing process generates complex pollutants, including dioxins, volatile metal compounds, and high concentrations of dust.

[0003] Ammonia-based desulfurization technology is widely used for ultra-low emission retrofits of coal-fired boilers due to its advantages, such as the production of ammonium sulfate fertilizer as a byproduct and stable operation. However, the addition of biomass significantly complicates the flue gas composition: organic pollutants (such as dioxins), volatile metals, and dust levels increase, leading to a continuous accumulation of impurities within the desulfurization tower. The ammonium sulfate crystallization system is interfered with by chlorides, complexes, and organic matter, resulting in crystallization difficulties, darkening and yellowing of the mother liquor, system corrosion, and sediment blockage. In severe cases, the desulfurization unit is forced to shut down, which not only affects the quality of the ammonium sulfate product but also significantly increases equipment operation and maintenance costs, hindering the normal and continuous production.

[0004] Therefore, it is necessary to provide a flue gas pretreatment system for biomass co-firing boilers to pretreat the flue gas before it enters the ammonia desulfurization device, thereby improving the quality of the flue gas entering the ammonia desulfurization process, reducing the negative impact of the flue gas generated by biomass co-firing directly undergoing ammonia desulfurization, effectively improving the quality of ammonium sulfate products, reducing the probability of equipment damage and equipment operation and maintenance costs, and providing a good foundation for ensuring normal and continuous production. Summary of the Invention

[0005] In order to overcome the problems in the background technology, the present invention designs a flue gas pretreatment system for a biomass co-firing boiler to pre-purify the flue gas generated by biomass co-firing, and more thoroughly removes harmful substances contained in the flue gas that will affect the subsequent flue gas ammonia desulfurization process, so that the quality of the flue gas entering the ammonia desulfurization process is improved, which is beneficial to improving the quality of the ammonium sulfate product formed in the ammonia desulfurization process, reducing the cost of the ammonia desulfurization process, and improving the efficiency of the ammonia desulfurization process.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions: The pretreatment system includes a flue gas scrubber 1, a flue gas scrubber preparation tank 2, and a slurry treatment system 3. The flue gas scrubber 1 is provided with a flue gas inlet 4 at the lower part of the side wall, and a flue gas outlet 5 is provided at the top of the flue gas scrubber 1. The flue gas scrubber 1 is provided with a swirl guide plate 6, a first spray washing pipe 7, a turbulent washing component 8, a baffle demister 9, and an ultrafine demister 10 fixedly installed in sequence from bottom to top. The swirl guide plate 6 is located above the flue gas inlet 4. The flue gas scrubber 1 is provided with a slurry outlet 11 at the bottom of the side wall. The slurry outlet 11 is connected to the slurry main body 10. One end of the pipeline 12 is connected, and the other end of the slurry main pipeline 12 branches to form a first branch slurry pipeline 13 and a second branch slurry pipeline 14. The first branch slurry pipeline 13 is connected to the slurry treatment system 3, and the second branch slurry pipeline 14 branches again and is connected to the first spray washing pipe 7 and the turbulent washing component 8 respectively. The discharge port of the flue gas scrubber preparation tank 2 is connected to the second branch slurry pipeline 14 through the liquid supply pipe 15, and the flue gas scrubber preparation tank 2 pumps flue gas scrubber into the first spray washing pipe 7 and the turbulent washing component 8.

[0007] Preferably, an annular guide plate 16 is fixedly installed in the flue gas scrubber 1, and the annular guide plate 16 is located between the swirl guide plate 6 and the inlet flue and is close to the swirl guide plate 6; The swirl guide plate 6 is evenly provided with a number of micro-holes with a diameter of 4 mm, and the opening rate is 10% to 20%.

[0008] Preferably, the pretreatment system also includes a second spray washing pipe 17 and a third spray washing pipe 18, which are both connected to a water source, and water is pumped into the second spray washing pipe 17 and the third spray washing pipe 18 by pumping. The second spray washing pipe 17 is fixedly arranged above the baffle demister 9, and the third spray washing pipe 18 is fixedly arranged above the ultrafine demister 10.

[0009] Preferably, the ultrafine mist eliminator 10 is composed of stacked steel meshes.

[0010] Preferably, the turbulent washing assembly 8 includes a mounting plate 801, a turbulent tube bundle 802, and a liquid inlet pipe 803. The mounting plate 801 is two pieces, and the mounting plate 801 is fixedly installed in the flue gas washing tower 1. A plurality of through holes 8011 are opened on the mounting plate 801. The turbulent tube bundle 802 is composed of a plurality of unit turbulent tubes 8021. The unit turbulent tube 8021 is located between the two mounting plates 801. The two ends of the unit turbulent tube 8021 are respectively connected to the through holes 8011 on the two mounting plates 801. After the second branch slurry pipeline 14 branches again, one of the branch pipelines is connected to the liquid inlet pipe 803. The liquid inlet pipe 803 is located above the turbulent tube bundle 802, and a plurality of liquid outlets are opened at the bottom of the liquid inlet pipe 803. The liquid outlets are aligned with the unit turbulent tube 8021. A spoiler 8022 is fixedly provided in the unit turbulence tube 8021. The height of the spoiler 8022 is the same as the length of the unit turbulence tube 8021 and the diameter of the spoiler 8022 coincides with that of the unit turbulence tube 8021. Two to three spoilers 8022 are provided, which are evenly distributed circumferentially along the unit turbulence tube 8021. A circular plate 8023 is also fixedly provided on the spoiler 8022. An annular plate 8024 is fixedly installed on the inner wall of the unit turbulence tube 8021. The circular plates 8023 and the annular plates 8024 are evenly spaced and staggered along the axial direction of the unit turbulence tube 8021. The distance between adjacent circular plates 8023 and annular plates 8024 is 1 / 3-1 / 5 of the length of the unit turbulence tube 8021. The inner diameter of the annular plate 8024 is larger than the outer diameter of the circular plate 8023.

[0011] Preferably, the slurry treatment system 3 includes a reaction tank 301, a sedimentation tank 302, an evaporation crystallization tank 303, and a centrifugal separator 304. The slurry outlet 11 is connected to the feed port of the reaction tank 301 through the slurry main pipeline 12 and the first branch slurry pipeline 13. The discharge port of the reaction tank 301 is connected to the feed port of the sedimentation tank 302. The reaction tank 301 pumps material into the sedimentation tank 302. The discharge port of the sedimentation tank 302 is connected to the feed port of the evaporation crystallization tank 303. The sedimentation tank 302 pumps material into the evaporation crystallization tank 303. The discharge port of the evaporation crystallization tank 303 is connected to the feed port of the centrifugal separator 304. A gas phase discharge port is opened on the top surface of the evaporation crystallization tank 303. The drug inlet of the reaction tank 301 is connected to the drug supply equipment.

[0012] Preferably, a circulating material inlet is provided on the reaction tank 301 , and an overflow weir 305 is provided on the upper portion of the outer wall of the sedimentation tank 302 along the circumference of the sedimentation tank 302 , and the overflow weir 305 and the liquid outlet of the centrifuge 304 are both connected to the circulating material inlet of the reaction tank 301 .

[0013] Preferably, a heating coil 3031 and a demister 3032 are fixedly installed in the evaporation crystallization tank 303, the demister 3032 is located above the heating coil 3031, the gas phase exhaust port is connected to the air inlet of the heating coil 3031, a steam compressor 3033 is installed on the pipe connecting the gas phase exhaust port and the heating coil 3031, and the pipe connecting the gas phase exhaust port and the heating coil 3031 is connected to the steam supply pipe.

[0014] Preferably, a circulating discharge port is opened on the side wall of the evaporation crystallization tank 303, and the circulating discharge port is connected to the feed port of the evaporation crystallization tank 303. The material discharged from the circulating discharge port is transported to the evaporation crystallization tank 303 by pumping. The circulating discharge port is located below the heating coil 3031.

[0015] Preferably, valves are provided at the liquid inlets of the first spray washing pipe 7 and the turbulent washing assembly 8 , and solenoid valves are installed on the first branch slurry pipeline 13 and the liquid supply pipeline 15 .

[0016] Beneficial effects of the present invention: 1. The present invention provides a flue gas scrubber with swirl guide plates, a first spray scrubber, a turbulent scrubber assembly, a demister, and other components to perform multi-stage coordinated treatment of biomass-co-combustion flue gas, effectively removing impurities such as organic pollutants from the flue gas, making the flue gas more suitable for ammonia desulfurization. This improves the quality of the ammonium sulfate product produced in the ammonia desulfurization process, reduces the cost of the ammonia desulfurization equipment, and improves the efficiency of the ammonia desulfurization process.

[0017] 2. The present invention provides an annular guide plate, which, on the one hand, concentrates the flue gas toward the middle of the flue gas scrubber, increases the probability that the flue gas scrubber sprayed from the first spray scrubbing pipe contacts the flue gas, and enhances the spray scrubbing effect; on the other hand, after being sprayed, the flue gas scrubber falls onto the annular guide plate, accumulates on the annular guide plate, and flows down along the inner edge of the annular guide plate to form a water curtain. The flue gas moving toward the side wall of the flue gas scrubber will first contact the flue gas scrubber, thereby lowering the flue gas temperature and reducing high-temperature corrosion of the side wall of the flue gas scrubber by the flue gas.

[0018] 3. Since waste liquid containing some harmful substances will be generated during the use of the system of the present invention, direct discharge will cause pollution to the environment. The present invention uses a slurry treatment system to treat this part of the liquid, remove some pollutants in the liquid, and at the same time convert the liquid into a solid for centralized collection and storage.

[0019] 4. The present invention provides micropores on the swirl guide plate. When the flue gas scrubber falls on the swirl guide plate, a liquid film is easily formed at the micropores. When the flue gas moves, it can pass through the liquid film at the micropores, thereby further increasing the probability of contact between the flue gas and the flue gas scrubber and enhancing the flue gas treatment effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the overall structure of the pretreatment system of the present invention; Figure 2 This is a schematic diagram of the top view of the swirl guide plate of the present invention; Figure 3 This is a perspective structural diagram of a unit turbulence tube of the present invention; Figure 4 This is a schematic diagram of the top view of the unit turbulence tube of the present invention; Figure 5 This is a schematic diagram of the top view of the turbulent washing component of the present invention.

[0021] In the figure, 1-flue gas scrubber, 2-flue gas scrubber preparation tank, 3-slurry treatment system, 301-reaction tank, 302-sedimentation tank, 303-evaporation crystallization tank, 3031-heating coil, 3032-demister, 3033-steam compressor, 304-centrifugal separator, 305-overflow weir, 4-flue inlet, 5-flue gas outlet, 6-swirl guide plate, 7-first spray washing pipe, 8-turbulent washing assembly, 801-mounting plate, 801 1-through hole, 802-turbulence tube bundle, 8021-unit turbulence tube, 8022-spoiler, 8023-circular plate, 8024-annular plate, 803-liquid inlet pipe, 9-baffle demister, 10-ultrafine demister, 11-slurry outlet, 12-slurry main pipeline, 13-first branch slurry pipeline, 14-second branch slurry pipeline, 15-liquid supply pipeline, 16-annular guide plate, 17-second spray washing pipe, 18-third spray washing pipe. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0023] like Figure 1-4As shown, the pretreatment system includes a flue gas scrubber 1, a flue gas scrubber preparation tank 2, and a slurry treatment system 3. The lower part of the side wall of the flue gas scrubber 1 is provided with a flue gas inlet 4, and the top of the flue gas scrubber 1 is provided with a flue gas outlet 5. The flue gas scrubber 1 is fixed with a swirl guide plate 6, a first spray washing pipe 7, a turbulent washing component 8, a baffle demister 9, and an ultrafine demister 10 from bottom to top. The swirl guide plate 6 is located above the flue gas inlet 4. The bottom of the side wall of the flue gas scrubber 1 is provided with a slurry outlet 11, and the slurry outlet 11 is connected to the slurry outlet 11. One end of the liquid main pipeline 12 is connected, and the other end of the slurry main pipeline 12 branches to form a first branch slurry pipeline 13 and a second branch slurry pipeline 14. The first branch slurry pipeline 13 is connected to the slurry treatment system 3, and the second branch slurry pipeline 14 branches again and is connected to the first spray washing pipe 7 and the turbulent washing component 8 respectively. The discharge port of the flue gas scrubber preparation tank 2 is connected to the second branch slurry pipeline 14 through the liquid supply pipeline 15, and the flue gas scrubber preparation tank 2 pumps the flue gas scrubber into the first spray washing pipe 7 and the turbulent washing component 8.

[0024] When pre-treating the flue gas, the flue gas from the biomass co-firing boiler is first introduced into the flue gas scrubber 1 through the flue duct 4. At this time, the first branch slurry pipeline 13 is in a closed state (the pipeline can be controlled by installing a valve on the first branch slurry pipeline 13). The liquid in the flue gas scrubber 1 does not enter the slurry treatment system 3. At the same time, the first spray washing pipe 7, turbulent washing component 8, etc. in the flue gas scrubber 1, and the flue gas scrubber preparation tank 2 are all in working state. As shown in the figure, the flue gas scrubber preparation raw materials are added to the flue gas scrubber preparation tank 2, and flue gas scrubber can be formed in the flue gas scrubber preparation tank 2. A solenoid valve is installed on the flue gas scrubber preparation raw material conveying path. The solenoid valve can be controlled to be on or off or open according to actual needs through the control system to prepare flue gas scrubber with appropriate concentration. After the flue gas enters the flue gas scrubber 1, it moves from bottom to top. When it passes through the swirl guide plate 6, the flue gas flow rotates at high speed under the action of the swirl blades to form a centrifugal field. Under the action of centrifugal force, the particles in the flue gas are thrown to the tower wall and removed. After the flue gas passes through the swirl guide plate 6, it contacts the flue gas scrubber sprayed from the first spray washing pipe 7 in reverse direction, and removes most of the organic pollutants, metal volatiles, etc. in the flue gas mainly through chemical reactions. The flue gas scrubber is mainly pumped from the flue gas scrubber preparation tank 2 to the first spray washing pipe 7, and then sprayed from the first spray washing pipe 7. When the flue gas scrubber sprayed from the first spray washing pipe 7 falls on the swirl guide plate 6, it is hindered by the swirl guide plate 6 and will accumulate and flow out from the gap of the swirl guide plate 6 to form a liquid film with a certain area. Therefore, the flue gas below the swirl guide plate 6 is more likely to contact with the flue gas scrubber during the upward movement. At the same time, the flue gas continues to move upward to reach the turbulent washing component 8. Since the movement paths of the flue gas scrubber and the flue gas are relatively random during the spray washing process, it is easy for the flue gas to not contact with the flue gas scrubber. As for the purification effect, even if the existence of the swirl guide plate 6 increases the contact probability between the flue gas and the flue gas scrubber to a certain extent, it still cannot completely remove impurities in the flue gas. At the same time, in order to increase the gas-liquid mass transfer area, the first spray washing pipe 7 adopts a high-pressure atomizing nozzle. The flue gas scrubber is atomized into very fine droplets, which greatly increases the gas-liquid mass transfer area and is beneficial to the absorption reaction. However, it also makes it difficult to separate the gas and liquid, resulting in serious entrainment of droplets in the flue gas after spray washing, and the impurities after absorption are carried away by the flue gas. Therefore, a turbulent washing component 8 is set after the first spray washing pipe 7. On the one hand, the contact probability between the flue gas and the flue gas scrubber is further increased to achieve the effect of deep washing of the flue gas. At the same time, the extremely fine droplets produced by the atomizing nozzle of the first spray washing pipe 7 contact and collide with a large amount of liquid in the turbulent washing component 8, and are merged by large droplets to reduce gas-liquid entrainment.The purified flue gas that has passed through the swirl plate, spray washing and turbulent washing continues to move upward and reaches the baffle demister 9. Since both spray washing and turbulent washing use liquid flue gas scrubbers to wash the flue gas, droplets will inevitably form after washing. The turbulent washing component 8 can reduce gas-liquid entrainment to a certain extent, but its reduction effect is limited. After using the flue gas scrubber to wash the flue gas, the used flue gas scrubber will also contain harmful substances originally in the flue gas. The droplets entrained in the flue gas contain the used flue gas scrubber and impurities in the flue gas itself. Therefore, when the flue gas continues to move upward with these droplets and reaches the baffle demister 9, the baffle demister 9 can remove larger droplets in the flue gas. The flue gas continues to move upward and reaches the ultrafine demister 10. The ultrafine demister 10 removes smaller droplets in the flue gas. Finally, the pretreated flue gas is transported to the ammonia desulfurization process through the flue gas outlet 5.

[0025] The baffle demister 9 and the ultrafine demister 10 are used to perform graded treatment on the mist droplets of different particle sizes in the flue gas. On the one hand, this can reduce the workload of the components, and on the other hand, it can also help to improve the treatment effect.

[0026] After the flue gas scrubbing is carried out for a period of time, the used flue gas scrubber will fall to the bottom of the flue gas scrubbing tower 1 and accumulate. At this time, the liquid accumulated at the bottom of the flue gas scrubbing tower 1 can be pumped to the first spray pipe and the turbulent washing component 8 for recycling. The effective ingredients in the flue gas scrubber after washing will continue to decrease. According to the operation progress of the device, the flue gas scrubber preparation tank 2 can pump in the flue gas scrubber to continuously replenish the effective ingredients for washing.

[0027] When the flue gas passes through the turbulent scrubbing assembly 8, the fine particles in the flue gas tend to agglomerate to form large-size particles (mist droplets), so that the baffle demister 9 and the ultrafine demister 10 can more effectively remove impurities in the flue gas.

[0028] During the flue gas purification process, when the flow rate of the incoming flue gas is controlled at 10~15m / s, the treatment effect is better, the spray pressure of the first spray washing pipe 7 is 0.06~0.3MPa, and the volume ratio of the flue gas scrubber sprayed from the first spray washing pipe 7 to the flue gas is controlled at 0.5~1L / m 3 It is appropriate.

[0029] An annular guide plate 16 is also fixedly installed in the flue gas scrubber 1 . The annular guide plate 16 is located between the swirl guide plate 6 and the inlet flue and is close to the swirl guide plate 6 . On the one hand, the annular guide plate 16 can form a blocking effect on the flue gas moving upward along the side wall of the flue gas washing tower 1, change the flue gas movement path, and concentrate the flue gas in the middle of the flue gas washing tower 1, thereby increasing the probability that the flue gas detergent sprayed from the first spray washing pipe 7 contacts the flue gas and enhances the spray washing effect. On the other hand, after the flue gas detergent is sprayed, it will fall on the annular guide plate 16, and then accumulate on the annular guide plate 16 and flow down along the inner edge of the annular guide plate 16. Usually, during the flue gas spray washing process, the amount of flue gas detergent sprayed is large, and the temperature of the flue gas detergent is low, while the temperature of the flue gas is high. The flue gas contacts the side wall of the flue gas washing tower 1, which may cause high-temperature corrosion to the side wall of the flue gas washing tower 1. After the flue gas detergent flows down from the inner edge of the annular guide plate 16, a water curtain can be formed. The flue gas moving toward the side wall of the flue gas washing tower 1 will first contact the flue gas detergent, thereby lowering the flue gas temperature and reducing the high-temperature corrosion of the flue gas on the side wall of the flue gas washing tower 1.

[0030] The swirl deflector 6 is uniformly provided with numerous micropores with a diameter of 4 mm, resulting in a porosity of 10% to 20%. The flue gas scrubber sprayed from the first spray scrubbing pipe 7 forms a liquid film through the micropores of the swirl deflector 6. The flue gas passes through this liquid film, increasing the gas-liquid mass transfer area and achieving a preliminary purification effect while also cooling the flue gas.

[0031] The pretreatment system also includes a second spray washing pipe 17 and a third spray washing pipe 18. The second spray washing pipe 17 and the third spray washing pipe 18 are both connected to a water source, and water is pumped into the second spray washing pipe 17 and the third spray washing pipe 18 by pumping. The second spray washing pipe 17 is fixedly arranged above the baffle demister 9, and the third spray washing pipe 18 is fixedly arranged above the ultrafine demister 10.

[0032] like Figure 1As shown in the figure, the water source is stored in the process water tank. After the flue gas washing tower 1 completes the flue gas washing, the working process of the baffle demister 9 and the ultrafine demister 10 will cause the impurities such as droplets removed from the flue gas to remain and adhere to the baffle demister 9 and the ultrafine demister 10. If the baffle demister 9 and the ultrafine demister 10 are not cleaned, the residual impurities will accumulate for a long time, which will have a negative impact on the normal operation of the baffle demister 9 and the ultrafine demister 10, and even cause component damage. Therefore, after the flue gas washing is completed, the second spray washing pipe 17 and the third spray washing pipe 18 are opened, and water is sent to the second spray washing pipe 17 and the third spray washing pipe 18 by pumping. The second spray washing pipe 17 sprays water to clean the baffle demister 9, and the third spray washing pipe 18 cleans the ultrafine demister 10. The cleaned liquid falls to the bottom of the flue gas washing tower 1.

[0033] The ultra-fine mist eliminator 10 is composed of stacked steel meshes.

[0034] The turbulent washing assembly 8 includes a mounting plate 801, a turbulent tube bundle 802, and a liquid inlet pipe 803. The mounting plate 801 is in two pieces. The mounting plate 801 is fixedly installed in the flue gas washing tower 1. A plurality of through holes 8011 are provided on the mounting plate 801. The turbulent tube bundle 802 is composed of a plurality of unit turbulent tubes 8021. The unit turbulent tube 8021 is located between the two mounting plates 801. Both ends of the unit turbulent tube 8021 are respectively connected to the through holes 8011 on the two mounting plates 801. After the second branch slurry pipeline 14 branches again, one of the branch pipelines is connected to the liquid inlet pipe 803. The liquid inlet pipe 803 is located above the turbulent tube bundle 802, and a plurality of liquid outlets are provided at the bottom of the liquid inlet pipe 803. The liquid outlets are aligned with the unit turbulent tube 8021. A spoiler 8022 is fixedly provided in the turbulence tube 8021. The height of the spoiler 8022 is the same as the length of the unit turbulence tube 8021 and the diameter of the spoiler 8022 coincides with that of the unit turbulence tube 8021. Two to three spoilers 8022 are provided, which are evenly distributed along the circumference of the unit turbulence tube 8021. A circular plate 8023 is also fixedly provided on the spoiler 8022. An annular plate 8024 is fixedly installed on the inner wall of the unit turbulence tube 8021. The circular plates 8023 and the annular plates 8024 are evenly spaced and staggered along the axial direction of the unit turbulence tube 8021. The distance between adjacent circular plates 8023 and annular plates 8024 is 1 / 3-1 / 5 of the length of the unit turbulence tube 8021. The inner diameter of the annular plate 8024 is larger than the outer diameter of the circular plate 8023.

[0035] When the flue gas reaches the turbulent scrubber assembly 8, due to the blocking effect of the mounting plate 801, the flue gas can only continue to move upward through the through hole 8011 on the mounting plate 801, and then enter the turbulent tube bundle 802. At the same time, the flue gas scrubber flows out from the liquid outlet at the bottom of the liquid inlet pipe 803. The liquid outlet is aligned with the unit turbulent tube 8021, and the flue gas scrubber flowing out from the liquid outlet enters the unit turbulent tube 8021. The flue gas and the flue gas scrubber enter the unit turbulent tube 8021 at the same time. The flue gas and the flue gas scrubber in the unit turbulent tube 8021 collide with each other, which is conducive to increasing the contact probability between the flue gas and the flue gas scrubber, thereby enhancing the flue gas treatment effect. In addition, the flue gas enters the turbulent tube and collide with the flue gas scrubber. The gas and liquid phases are intercepted and collided by the internal spoiler 8022, circular plate 8023, and annular plate 8024, constantly changing the flow direction and updating the gas-liquid contact surface, further enhancing the flue gas treatment effect.

[0036] The slurry treatment system 3 includes a reaction tank 301, a sedimentation tank 302, an evaporation crystallization tank 303, and a centrifugal separator 304. The slurry outlet 11 is connected to the feed port of the reaction tank 301 through the slurry main pipeline 12 and the first branch slurry pipeline 13. The discharge port of the reaction tank 301 is connected to the feed port of the sedimentation tank 302. The reaction tank 301 pumps material into the sedimentation tank 302. The discharge port of the sedimentation tank 302 is connected to the feed port of the evaporation crystallization tank 303. The sedimentation tank 302 pumps material into the evaporation crystallization tank 303. The discharge port of the evaporation crystallization tank 303 is connected to the feed port of the centrifugal separator 304. A gas phase discharge port is opened on the top surface of the evaporation crystallization tank 303. The drug inlet of the reaction tank 301 is connected to the drug supply equipment.

[0037] After the baffle demister 9 and the ultrafine demister 10 have completed washing, the used flue gas scrubber and water will accumulate at the bottom of the flue gas washing tower 1 to form a slurry. When the slurry reaches a certain concentration, the washing effect will also deteriorate. At this time, the first branch slurry pipe 13 is opened to send out the liquid accumulated at the bottom of the flue gas washing tower 1, and the flue gas purification treatment can be carried out in the tower at the same time. The liquid at the bottom of the flue gas scrubber 1 is pumped along the first branch slurry pipeline 13 to the slurry treatment system 3, and first enters the reaction tank 301. At the same time, the slurry (i.e., the liquid accumulated at the bottom of the flue gas scrubber 1) is fed into the reaction tank 301 through the reagent source (as shown in the figure, there are two types of reagents, which are stored in two reagent bins respectively, and the amount of reagents transported to the reaction tank by the reagent bin can be controlled by a valve) to treat the reagent. The reagent and the slurry are stirred and reacted in the reaction tank 301 (the reaction tank 301 with a stirring function belongs to the existing conventional equipment) to generate precipitated material. Then, the material in the reaction tank 301 is pumped to the sedimentation tank 302 for sedimentation. The sedimentation time is generally controlled to be 2 to 4 hours. After sedimentation, the discharge valve of the sedimentation tank 302 is opened (the sedimentation tank 302 with a valve belongs to the existing conventional equipment), and the settled material is pumped It is sent to the evaporation crystallization tank 303 for evaporation crystallization treatment, and the gaseous substance formed by evaporation crystallization is discharged from the evaporation crystallization tank 303 through the gaseous phase discharge port (after the slurry reacts with the reagent in the reaction tank 301, the use of appropriate reagents can almost make the harmful components in the slurry converted into precipitated substances. Therefore, the gaseous substance formed by evaporation crystallization will hardly cause harm to the environment), and the formed solid substance is transported to the centrifugal separator 304 by its own gravity. Although the evaporation crystallization process can allow most of the liquid in the slurry to form a gas phase and be discharged, in order to avoid accidental situations, the solid substance is further centrifuged to further reduce the amount of liquid in the solid substance, obtain a solid substance with a higher degree of drierness, and further reduce the possibility of seepage of the solid substance. After centrifugation, the solid substance obtained by centrifugation is uniformly collected and stored.

[0038] The reaction tank 301 is also provided with a circulating material inlet, and an overflow weir 305 is provided on the upper portion of the outer wall of the sedimentation tank 302 along the circumference of the sedimentation tank 302 . The overflow weir 305 and the liquid outlet of the centrifugal separator 304 are both connected to the circulating material inlet of the reaction tank 301 .

[0039] After the slurry reacts with the reagent in the reaction tank 301, a precipitate is formed. The material transferred from the reaction tank 301 to the settling tank 302 is a mixture of liquid and solid (a suspension). After settling in the settling tank 302, a supernatant is obtained. As the amount of material entering the settling tank 302 increases, the amount of supernatant increases, and the supernatant overflows from the settling tank 302 and enters the overflow weir 305. The supernatant in the overflow weir 305 is then transferred to the reaction tank 301 for recycling. Similarly, after the centrifugal separator 304 centrifuges the solid matter, liquid matter is also produced, which is transferred to the reaction tank 301 for collection. The suspension transferred to the settling tank 302 enters the middle of the settling tank 302. Due to the principle of gravity, the solid matter slowly descends to the bottom of the settling tank 302, becoming a thick slurry. The clear liquid rises to the top of the settling tank 302, becoming the overflow clear liquid.

[0040] A heating coil 3031 and a demister 3032 are fixedly installed in the evaporation crystallization tank 303. The demister 3032 is located above the heating coil 3031. The gas phase exhaust port is connected to the air inlet of the heating coil 3031. A steam compressor 3033 is installed on the pipe connecting the gas phase exhaust port and the heating coil 3031. The pipe connecting the gas phase exhaust port and the heating coil 3031 is connected to the steam supply pipe.

[0041] Since the evaporation crystallization tank 303 is a device that heats the material to convert the liquid phase in the material into the gas phase, thereby separating the liquid phase and solid phase in the material, the secondary steam generated by the evaporation crystallization is compressed by the steam compressor 3033, and the temperature and pressure are increased, and the thermal enthalpy is increased. It is then transported back to the heating coil 3031 and used as a heating source for the evaporation crystallization tank 303, so that the originally wasted steam is fully utilized and the latent heat is recovered. Except for starting the machine, no new steam is required from the steam source during the entire evaporation process, which greatly improves the thermal efficiency and helps save costs.

[0042] A circulating discharge port is provided on the side wall of the evaporation crystallization tank 303 , and the circulating discharge port is connected to the feed port of the evaporation crystallization tank 303 . The material discharged from the circulating discharge port is pumped into the evaporation crystallization tank 303 . The circulating discharge port is located below the heating coil 3031 .

[0043] The material circulates repeatedly into the evaporation crystallization tank 303, which can disturb the material undergoing evaporation crystallization in the evaporation crystallization tank 303, so that more material is heated more evenly, which is beneficial to improving the evaporation crystallization efficiency and evaporation crystallization effect.

[0044] Valves are provided at the liquid inlets of the first spray washing pipe 7 and the turbulent washing assembly 8 , and solenoid valves are installed on the first branch slurry pipeline 13 and the liquid supply pipeline 15 .

[0045] On other conveying pipelines, corresponding valves or solenoid valves can be set according to actual needs to realize the control of material conveying volume and the on and off of material conveying. The solenoid valve can be connected to the control system to realize automatic control.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A flue gas pretreatment system for a biomass-fired boiler, characterized by: The pretreatment system comprises a flue gas scrubber (1), a flue gas scrubber preparation tank (2), and a slurry treatment system (3). A flue gas inlet (4) is provided at the lower portion of the side wall of the flue gas scrubber (1), and a flue gas outlet (5) is provided at the top of the flue gas scrubber (1). A swirl guide plate (6), a first spray scrubbing pipe (7), a turbulent scrubbing assembly (8), a baffle demister (9), and an ultrafine demister (10) are fixedly installed in the flue gas scrubber (1) from bottom to top. The swirl guide plate (6) is located above the flue gas inlet (4). A slurry outlet (11) is provided at the bottom of the side wall of the flue gas scrubber (1), and the slurry outlet (11) is connected to the flue gas scrubber (10). One end of the slurry main pipeline (12) is connected, and the other end of the slurry main pipeline (12) branches to form a first branch slurry pipeline (13) and a second branch slurry pipeline (14). The first branch slurry pipeline (13) is connected to the slurry treatment system (3), and the second branch slurry pipeline (14) branches again and is connected to the first spray washing pipe (7) and the turbulent washing component (8). The discharge port of the flue gas scrubber preparation tank (2) is connected to the second branch slurry pipeline (14) through the liquid supply pipe (15), and the flue gas scrubber preparation tank (2) pumps the flue gas scrubber into the first spray washing pipe (7) and the turbulent washing component (8).

2. The flue gas pretreatment system for a biomass-fired boiler according to claim 1, characterized in that: An annular guide plate (16) is also fixedly installed in the flue gas scrubber (1), and the annular guide plate (16) is located between the swirl guide plate (6) and the inlet flue and is close to the swirl guide plate (6); The swirl guide plate (6) is evenly provided with a number of micropores with a diameter of 4 mm, and the opening rate is 10% to 20%.

3. The flue gas pretreatment system for a biomass-fired boiler according to claim 1, characterized in that: The pretreatment system further includes a second spray washing pipe (17) and a third spray washing pipe (18), the second spray washing pipe (17) and the third spray washing pipe (18) are both connected to a water source, and water is pumped into the second spray washing pipe (17) and the third spray washing pipe (18) by pumping. The second spray washing pipe (17) is fixedly arranged above the baffle demister (9), and the third spray washing pipe (18) is fixedly arranged above the ultrafine demister (10).

4. The flue gas pretreatment system for a biomass-fired boiler according to claim 1, characterized in that: The ultrafine demister (10) is composed of stacked steel wire meshes.

5. The flue gas pretreatment system for a biomass-fired boiler according to claim 1, characterized in that: The turbulent washing assembly (8) includes a mounting plate (801), a turbulent tube bundle (802), and a liquid inlet pipe (803). The mounting plates (801) are two in number. The mounting plates (801) are fixedly mounted in the flue gas washing tower (1). A plurality of through holes (8011) are provided on the mounting plates (801). The turbulent tube bundle (802) is composed of a plurality of unit turbulent tubes (8021). The unit turbulent tubes (8021) are located between the two mounting plates (801). Both ends of the unit turbulent tubes (8021) are respectively connected to the through holes (8011) on the two mounting plates (801). After the second branch slurry pipeline (14) branches again, one of the branch pipelines is connected to the liquid inlet pipe (803). The liquid inlet pipe (803) is located above the turbulent tube bundle (802), and a plurality of liquid outlets are provided at the bottom of the liquid inlet pipe (803). The liquid outlets are aligned with the unit turbulent tubes (8021). A spoiler (8022) is fixedly provided in the unit turbulence tube (8021), wherein the height of the spoiler (8022) is the same as the length of the unit turbulence tube (8021), and the diameter of the spoiler (8022) coincides with the diameter of the unit turbulence tube (8021), and 2 to 3 spoilers (8022) are provided and are evenly distributed along the circumference of the unit turbulence tube (8021), and a circular plate (8023) is also fixedly provided on the spoiler (8022). An annular plate (8024) is fixedly mounted on the inner wall of the unit turbulence tube (8021); the circular plate (8023) and the annular plate (8024) are evenly spaced and staggered along the axial direction of the unit turbulence tube (8021); the distance between adjacent circular plates (8023) and annular plates (8024) is 1 / 3-1 / 5 of the length of the unit turbulence tube (8021); and the inner diameter of the annular plate (8024) is greater than the outer diameter of the circular plate (8023).

6. The flue gas pretreatment system for a biomass-fired boiler according to claim 1, characterized in that: The slurry treatment system (3) comprises a reaction tank (301), a sedimentation tank (302), an evaporation crystallization tank (303), and a centrifugal separator (304); the slurry outlet (11) is connected to the feed port of the reaction tank (301) through a slurry main pipeline (12) and a first branch slurry pipeline (13); the discharge port of the reaction tank (301) is connected to the feed port of the sedimentation tank (302); the reaction tank (301) pumps material into the sedimentation tank (302); the discharge port of the sedimentation tank (302) is connected to the feed port of the evaporation crystallization tank (303); the sedimentation tank (302) pumps material into the evaporation crystallization tank (303); the discharge port of the evaporation crystallization tank (303) is connected to the feed port of the centrifugal separator (304); a gas phase discharge port is provided on the top surface of the evaporation crystallization tank (303); and the drug inlet of the reaction tank (301) is connected to a drug supply device.

7. The flue gas pretreatment system for a biomass-fired boiler according to claim 6, characterized in that: The reaction tank (301) is also provided with a circulating material inlet. An overflow weir (305) is provided on the upper portion of the outer wall of the sedimentation tank (302) along the circumference of the sedimentation tank (302). The overflow weir (305) and the liquid outlet of the centrifugal separator (304) are both connected to the circulating material inlet of the reaction tank (301).

8. The flue gas pretreatment system for a biomass-fired boiler according to claim 6, characterized in that: A heating coil (3031) and a demister (3032) are fixedly arranged in the evaporation crystallization tank (303), the demister (3032) is located above the heating coil (3031), the gas phase discharge port is connected to the air inlet of the heating coil (3031), a steam compressor (3033) is installed on the pipe connecting the gas phase discharge port and the heating coil (3031), and the pipe connecting the gas phase discharge port and the heating coil (3031) is connected to a steam supply pipe.

9. The flue gas pretreatment system for a biomass-fired boiler according to claim 8, characterized in that: A circulating discharge port is provided on the side wall of the evaporation crystallization tank (303), the circulating discharge port is connected to the feed port of the evaporation crystallization tank (303), and the material discharged from the circulating discharge port is transported to the evaporation crystallization tank (303) by pumping. The circulating discharge port is located below the heating coil (3031).

10. The flue gas pretreatment system for a biomass-fired boiler according to claim 1, characterized in that: Valves are provided at the liquid inlets of the first spray washing pipe (7) and the turbulent washing assembly (8), and solenoid valves are installed on the first branch slurry pipeline (13) and the liquid supply pipeline (15).

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