Flue gas waste heat recovery and purification system

Abstract

The invention provides a flue gas waste heat recovery and purification system, which comprises a discharge device, a purification tower, a circulating water storage device, a heat pump unit and a pulse automatic decontamination device, and is characterized in that a combination of a plurality of rotational flow atomizers and a multi-stage rotational flow demister is adopted in the purification tower, so that the convective heat exchange capability of flue gas and circulating water is enhanced; more flue gas waste heat is captured into the circulating water, more flue gas condensate can be separated and collected into the circulating water, the smoke exhaust latent heat loss is greatly reduced, and the purification operation water consumption is also reduced; through the two-stage arrangement of the circulating water storage device and the pulse automatic decontamination device, the water quality of purified circulating water is greatly improved, the waste heat recovery capacity is improved, system scaling and sewage blockage are reduced, scouring and abrasion of a heat exchanger are reduced, and the purification efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas waste heat recovery and flue gas purification, and in particular to a high-temperature flue gas waste heat recovery and purification system that can meet the needs of heating self-circulation. Background Art

[0002] At present, during the operation of the boilers of coal-fired power plants, the flue gas temperature is mostly between 110-150℃, and its heat loss can reach 4%-8% of the total input fuel heat of the power plant. A large amount of flue gas waste heat is not effectively utilized and is directly discharged into the atmosphere, resulting in energy waste. At present, the common way to utilize the flue gas waste heat of power plant boilers is to install a flue gas heat exchanger in the tail flue of the boiler. This waste heat recovery method is currently the most widely used flue gas waste heat direct utilization technology, but its improvement in energy utilization is no more than 2%, and there is still a large amount of flue gas sensible heat and latent heat that cannot be recovered, resulting in waste.

[0003] In addition, thermal power plants generally adopt wet purification technology. The flue gas and the purification circulating slurry flow in the purification tower in reverse and directly exchange heat, so that the flue gas changes from high-temperature dry flue gas to low-temperature saturated wet flue gas. Part of the flue gas sensible heat and all the flue gas latent heat are discharged to the atmosphere at the same time. The water vapor absorbed by the flue gas from the purification slurry accounts for about 80% of the purification water consumption, so that the flue gas after wet purification is humidified to saturated wet flue gas at about 50℃-60℃, mostly saturated or nearly saturated. However, the effective contact area between the purification slurry and the flue gas in the existing purification tower is not large, the capture capacity of the flue gas is insufficient, and the particulate matter in the flue gas cannot be effectively carried, and the purification efficiency is insufficient; in addition, the saturated wet flue gas after filtration cannot be effectively condensed and removed, and the water collection effect is not good. The flue gas containing a large amount of latent heat of vaporization and water resources is not effectively recycled and utilized, and the heat contained in the temperature difference of about 20℃ is discharged to the atmosphere in the form of latent heat of vaporization of water vapor. Summary of the invention

[0004] The purpose of the present invention is to solve the above technical problems, and thus provide a flue gas waste heat recovery and purification system, which adopts the flue gas direct condensation method, comprehensively considers increasing the liquid-gas ratio of the purification spray, improving the mass transfer and heat transfer efficiency in the purification tower, and reasonably selecting a low-resistance and high-efficiency gas-liquid separation and demisting device. At the same time, in conjunction with the heat pump unit process system, the flue gas waste heat is deeply recovered and utilized, and the flue gas temperature can be reduced to 20-25°C, or even lower. The specific system structure is as follows:

[0005] A flue gas waste heat recovery and purification system comprises an emission device, a purification tower, a circulating water storage device, a heat pump unit and a pulse automatic decontamination device, wherein the flue gas inlet at the bottom of the purification tower is connected to the flue gas outlet of the boiler through a pipeline, and the flue gas outlet at the top of the purification tower is connected to the emission device through a pipeline, and the circulating water storage device comprises a cold water pool and a hot water pool isolated from each other, and a cold water pool outlet, a cold water pool inlet, a hot water pool outlet and a hot water pool inlet are arranged on the circulating water storage device; a spray device and a multi-stage cyclone demister located above the spray device are arranged above the interior of the purification tower, and the water inlet of the spray device is connected to the cold water pool outlet through a pipeline and comprises a plurality of cyclone atomizers; the water outlet at the bottom of the purification tower is connected to the hot water pool inlet through a pipeline, and the cold water pool inlet is connected to the hot water pool inlet through a pipeline The water outlet of the hot water tank is connected to the pulse automatic dirt removal device through a pipeline, the pulse automatic dirt removal device includes a cyclone drainer and a degassing drainer connected in series, the cyclone drainer includes a main cyclone cylinder and an eccentric filter cylinder, the main cyclone cylinder includes a water inlet, an upper outlet, a discharge port and an inspection port, the water inlet is connected to the water outlet of the hot water tank through a pipeline, and the upper outlet is connected to the inlet of the degassing drainer; the degassing drainer includes a water outlet and a pressure automatic exhaust valve, the water outlet is connected to the water inlet of the heat pump unit through a pipeline, the discharge port of the cyclone drainer and the degassing discharge port of the degassing drainer are respectively connected to the water inlet of the cold water tank through pipelines; the cyclone demister includes a streamlined guide pipe, a three-stage centrifugal separation guide blade and a droplet collection separator.

[0006] Furthermore, the cyclone atomizer includes a cyclone atomizer shell, a cyclone passage, an air flow inlet, a liquid phase flow pipe, an atomized liquid outlet and an air flow outlet. The cyclone atomizer shell is annular, and a liquid phase flow pipe is provided in the tangential direction of the cyclone atomizer shell to receive the water flow from the cold water pool outlet. The "L"-shaped air-assisted air intake pipe is connected to the tangential inlet section of the cyclone atomizer shell. The air flow inlet of the air-assisted air intake pipe and the liquid phase flow pipe are perpendicular to each other, and the air flow outlet of the air-assisted air intake pipe is parallel to the axis of the liquid phase flow pipe. An atomized liquid outlet is provided on the lower surface of the cyclone atomizer shell. The cyclone passage is surrounded by the inner wall of the cyclone atomizer shell. The air flow and the water flow from the cold water pool outlet simultaneously enter the cyclone passage along the tangential direction to mix and accelerate and are sprayed from the atomized liquid outlet to form an umbrella-shaped water mist composed of fine droplets.

[0007] Furthermore, the diameter of the swirl atomizer shell is 26-35 mm, the diameter of the swirl flow passage is 8-12 mm, and the pressure loss value of the airflow from entry to ejection is between 0.04-0.11 MPa.

[0008] Furthermore, the eccentric angle of the eccentric filter cylinder is 56-61°, preferably 58°, and it adopts an assembled structure and is made of stainless steel. The eccentric filter is umbrella-shaped.

[0009] Furthermore, the degassing and draining device is controlled by a PLC chip, which controls the opening and closing of the solenoid valve or the electric valve according to the pressure difference, the turbidity of the effluent or the running time, and automatically discharges sewage during the operation.

[0010] Furthermore, the degassing and draining device performs gas-water separation, spiral sedimentation, precision filtration and the like, so that the insoluble gas accumulates in the gas buffer area at the top of the cylinder after entering the cylinder of the degassing and draining device, and is discharged through the pressure automatic exhaust valve.

[0011] Furthermore, each pipeline is provided with a circulating water pump.

[0012] Furthermore, the circulating water storage device adopts cold and hot partitions, including a pool wall, a surface corrosion-resistant layer, an insulating layer, and mutually isolated cold water pool and hot water pool. An internal partition is arranged between the cold water pool and the hot water pool, and a balancing overflow pipe is left on the upper part of the internal partition.

[0013] Furthermore, the heat pump unit is connected to the heating network, and the water in the heating network returns to the heating network after heat exchange with the heat pump unit. The heat pump unit is an electric compression heat pump.

[0014] The present invention produces the following technical effects through the innovative arrangement of the above specific structure:

[0015] 1. The purification tower of the flue gas waste heat recovery and purification system integrates purification and heat exchange. Through independent research and development and transformation of the internal spray device and demister device, the convection heat exchange capacity between the flue gas and the circulating water is enhanced, so that more flue gas waste heat can be captured in the circulating water, and then through the coupling heat pump technology, more flue gas waste heat can be transferred to the heat exchange medium. At the same time, the fine circulating water atomized particles enhance and promote the purification chemical reaction rate and improve the purification efficiency. The improvement of the demister device is conducive to the separation and collection of more flue gas condensate into the circulating water, which greatly reduces the exhaust latent heat loss and also reduces the water consumption of purification operation.

[0016] 2. The two-stage setting of the circulating water storage device and the pulse automatic decontamination device greatly improves the water quality of the purified circulating water, which is beneficial to improving the waste heat recovery capacity, reducing system scaling and fouling, reducing the scouring and wear of the heat exchanger, and is beneficial to improving the purification efficiency.

[0017] 3. The cyclone demister in the purification tower adopts a multi-stage design with a resistance of 60-180Pa and an average inlet particle concentration of 5.8mg / m 3 The average outlet particle concentration is 5.5 mg / m 3 , the particle concentration at the outlet is lower than that at the inlet. The flue gas resistance loss is 50-100Pa greater than that of the flat-plate demister, but the water collection effect is excellent, allowing more flue gas condensate to flow back into the purification circulating water system.

[0018] 4. Pulse automatic decontamination device for concentration 1.6g / cm 3 The rust, mud and sand impurities are separated with a particle size of 0.05mm. When the particle size is 0.32mm, the decontamination efficiency is 98%. The two-stage setting of the hot and cold water pool and the decontamination filter device greatly improves the water quality of the purified circulating water, which is beneficial to improving the waste heat recovery capacity, reducing system scaling and fouling, reducing the scouring and wear of the heat exchanger, and improving the purification efficiency.

[0019] 5. For the cyclone decontaminator, the water flows into the cylinder along the tangential direction. Under the action of centrifugal force and gravity, the silt and granular impurities therein sink into the dirt accumulation area of ​​the cylinder. After the water flow with large particles of dirt is removed, it still contains tiny particles and insoluble gases that are difficult to capture and remove. In order to further reduce the scouring, wear and accumulation of particles in the water on the system pipes and valves and other accessories, as well as the cavitation of the pump impeller caused by insoluble gases, and reduce gas-water impact accidents, an automatically operated degassing decontaminator is connected in series after the cyclone decontaminator. The decontaminator uses gas-water separation, spiral sedimentation, precision filtration, etc. to make the insoluble gas accumulate in the gas buffer area at the top of the cylinder after entering the cylinder, and is discharged through the pressure automatic exhaust valve. The decontaminator can effectively remove impurity particles larger than 5μm. The impurity particles condense and settle in the dirt accumulation area at the bottom of the cylinder and are automatically discharged, which reduces labor intensity and saves water resources at the same time.

[0020] 6. The system uses an electric compression heat pump, which can solve the problem of "more electricity and less heat" in thermal power plants, solve the problem of limited power output of small thermal power units, and improve the economy and flexibility of heating units. The waste heat recovery capacity of the system is specifically manifested in the surplus of the heat pump unit, that is, the ability of the heat pump to capture waste heat. The recovered heat can be used to heat the return water for heating in winter. The heating capacity of the system is more significant than the heat recovery potential and purification effect of similar flue gas purification and recovery systems, and the COP performance, the main evaluation index for evaluating the heat recovery performance of the heat pump system, is good. The flue gas waste heat recovery and purification system can be extended to the flue gas waste heat recovery and purification of gas-steam combined cycle waste heat boilers and gas boilers, and can also be extended to the flue gas waste heat recovery and purification of ship diesel engines to achieve cascade utilization of heat. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It is obvious that the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 : Structural diagram of the flue gas waste heat recovery and purification system of this application.

[0023] Figure 2 : Schematic diagram of the structure of the multi-stage cyclone demister of the present application.

[0024] Figure 3 : Schematic diagram of the overall structure of the pulse automatic dirt removal device of the present application.

[0025] Figure 4 : Schematic diagram of the structure of the cyclone drainer of the present application.

[0026] Figure 5 : Bottom view of the cyclone atomizer of the present application.

[0027] Figure 6 : Side view of the cyclone atomizer of the present application.

[0028] Figure 7 : The main view of the appearance of the circulating water storage device of the present application.

[0029] Figure 8 : Schematic diagram of the internal structure of the circulating water storage device of the present application.

[0030] Reference numerals:

[0031] 1-discharge device; 2-purification tower; 3-multi-stage cyclone demister; 31-streamlined guide pipe; 32-three-stage centrifugal separation guide blade; 33-droplet collection separator; 4-spraying device; 5-circulating water storage device; 5a-cold water pool; 5b-hot water pool; 51-cold water pool outlet; 52-cold water pool inlet; 53-hot water pool outlet; 54-hot water pool inlet; 55-sewage outlet; 6-heat pump unit; 7-pulse automatic decontamination device; 71-cyclone drainer; 72-degassing drainer; 711-main cyclone Cylinder; 712-eccentric filter cylinder; 7111-water inlet; 7112-upper outlet; 7113-discharge outlet; 7114-inspection port; 721-pressure automatic exhaust valve; 722-degassing discharge outlet; 723-water outlet; 8-cyclone atomizer; 81-cyclone atomizer shell; 82-cyclone flow passage; 83-air flow inlet; 84-liquid phase inlet pipeline; 85-atomized liquid outlet; 86-air flow outlet; 9-pool wall; 91-inner partition; 92-balance overflow pipe; 93-surface corrosion resistant layer; 94-thermal insulation layer. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. It is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0033] like Figure 1 As shown, the flue gas waste heat recovery and purification system includes an emission device 1, a purification tower 2, a circulating water storage device 5, a heat pump unit 6 and a pulse automatic decontamination device 7. The flue gas inlet at the bottom of the purification tower 2 is connected to the flue gas outlet of the boiler through a pipeline, and the flue gas outlet at the top of the purification tower 2 is connected to the emission device 1 through a pipeline. The circulating water storage device 5 includes a cold water pool 5a and a hot water pool 5b isolated from each other. A spray device 4 and a multi-stage cyclone demister 3 located above the spray device 4 are provided above the purification tower 2. The water inlet of the spray device 4 is connected to the cold water pool outlet 51 through a pipeline and includes a plurality of cyclone atomizers 8; the water outlet at the bottom of the purification tower 2 is connected to the hot water pool inlet 54 through a pipeline, the cold water pool inlet 52 is connected to the water outlet of the heat pump unit 6 through a pipeline, the hot water pool outlet 53 is connected to the water inlet of the pulse automatic decontamination device 7 through a pipeline, and the water outlet of the pulse automatic decontamination device 7 is connected to the water inlet of the heat pump unit 6 through a pipeline.

[0034] The cyclone demister includes a streamlined guide tube 31, a three-stage centrifugal separation guide blade 32 and a droplet collection separator 33. The flue gas enters the cyclone demister 3 from the streamlined guide tube 31, collides with the streamlined guide tube 31 and the three-stage centrifugal guide blade 32 during the flow process, and removes large droplets and dust particles. Then the flue gas enters the droplet separator 33 to remove small droplets and dust particles, thereby improving the removal efficiency. The cyclone demister has a resistance of 60-180Pa and an average inlet particle concentration of 5.8mg / m 3 The average outlet particle concentration is 5.5 mg / m 3 , the particle concentration at the outlet is lower than that at the inlet. The flue gas resistance loss is 50-100Pa greater than that of the flat-plate demister, but the water collection effect is excellent, allowing more flue gas condensate to flow back into the purification circulating water system.

[0035] The spray device 4 includes a plurality of cyclone atomizers 8, wherein the cyclone atomizer 8 includes a cyclone atomizer housing 81, a cyclone flow passage 82, an air flow inlet 83, a liquid phase inlet pipe 84, an atomized liquid outlet 85 and an air flow outlet 86. The cyclone atomizer housing 81 is annular, and a liquid phase inlet pipe 84 is provided in the tangential direction of the cyclone atomizer housing 81 for receiving water flow from the cold water pool outlet 51. An "L"-shaped air booster intake pipe is connected to the tangential inlet section of the cyclone atomizer housing 81. The air booster intake pipe 84 is provided in the tangential direction of the cyclone atomizer housing 81. The airflow inlet 83 of the air inlet pipe is perpendicular to the liquid phase flow pipe 84, and the airflow outlet 86 of the air-assisted air inlet pipe is parallel to the axis of the liquid phase flow pipe 84. An atomized liquid outlet 85 is provided on the lower surface of the cyclone atomizer shell 81, and the cyclone passage 82 is surrounded by the inner wall of the cyclone atomizer shell 81. The air flow and the water flow from the cold water pool outlet 51 enter the cyclone passage 82 along the tangential direction, mix and accelerate, and spray out from the atomized liquid outlet 85, forming an umbrella-shaped water mist composed of fine droplets. The diameter of the cyclone atomizer shell 81 is 26-35mm, and the diameter of the cyclone passage 82 is 8-12mm. The pressure loss value of the airflow from entering to spraying is between 0.04-0.11MPa, the injection resistance is small, the atomized particles are finer than the water particles of conventional nozzles, and the atomization cone angle is large, and the effective contact area with the flue gas is wider, which greatly enhances the ability of circulating water to capture flue gas waste heat and purification performance.

[0036] The pulse automatic dirt removal device 7 includes a cyclone drainer 71 and a degassing drainer 72 connected in series. The discharge port of the cyclone drainer 71 and the degassing discharge port 722 of the degassing drainer 72 are connected to the cold water pool water inlet 52 through a pipeline; the cyclone drainer 71 includes a main cyclone cylinder 711 and an eccentric filter cylinder 712, and the main cyclone cylinder 711 includes an inlet 7111, an upper outlet 7112, a discharge port 7113 and an inspection port 7114. In the main cyclone cylinder 711, the dirt swirls along the cylinder wall to the cylinder bottom outlet under the action of water flow and its own gravity and is discharged. The eccentric angle of the eccentric filter cylinder 712 is 58°, and it adopts an assembled structure, made of stainless steel, and the filter is umbrella-shaped. The degassing drainer 72 is controlled by a PLC chip, and the opening and closing of the solenoid valve or the electric valve are controlled according to the pressure difference, the turbidity of the outlet water or the running time, and the dirt is automatically discharged during the operation. The pulse automatic decontamination device 7 is for a concentration of 1.6 g / cm 3 The rust, mud and sand impurities are separated with a particle size of 0.05mm. When the particle size is 0.32mm, the decontamination efficiency is 98%. The two-stage setting of the circulating water storage device 5 and the pulse automatic decontamination device 7 greatly improves the water quality of the purified circulating water, is conducive to improving the waste heat recovery capacity, reducing system scaling and fouling, reducing the scouring and wear of the heat exchanger, and is conducive to improving the purification efficiency.

[0037] The heat pump unit 6 is connected to the heat network, and the water returns to the heat network after heat exchange through the heat pump unit 6. The heat pump unit 6 is an anti-corrosion heat pump unit, such as an electric compression heat pump. The entire flue gas waste heat recovery and purification system forms a closed loop. The electric compression heat pump can solve the problem of more electricity and less heat in thermal power plants and the imbalance of electricity and heat, solve the dilemma of limited power output of small thermal power units, and improve the economy and flexibility of heating units.

[0038] The flue gas waste heat recovery and purification system of the present application, when working, specifically includes the following steps:

[0039] S1: The boiler flue gas is sent to the flue gas inlet at the bottom of the purification tower 2 through the induced draft fan, and the flue gas flows upward inside the purification tower 2;

[0040] S2: A spray device 4 and a multi-stage cyclone demister 3 located above the spray device 4 are arranged above the purification tower 2. The water inlet of the spray device 4 is connected to the cold water pool outlet 51 of the circulating water storage device 5 through a pipeline and includes a plurality of cyclone atomizers 8. Water flows through the plurality of cyclone atomizers 8 to obtain umbrella-shaped water mist composed of fine droplets and falls. The falling umbrella-shaped water mist completes heat exchange with the rising flue gas, and realizes the dissolution and precipitation of inorganic substances in the flue gas.

[0041] S3: The flue gas that continues to flow upward is low-temperature saturated wet flue gas containing a large amount of dust and droplets, which enters the cyclone demister 3 upward. The cyclone demister 3 includes a streamlined guide pipe 31, a three-stage centrifugal separation guide blade 32 and a droplet collection separator 33. The flue gas enters the cyclone demister 3 from the streamlined guide pipe 31, collides with the streamlined guide pipe 31 and the three-stage centrifugal guide blade 32 during the flow process, and is gathered into liquid under the action of the redirecting centrifugal force of the three-stage centrifugal guide blade 32. It flows back to the bottom of the purification tower 2 under the action of its own gravity, and then the flue gas enters the droplet separator 33; the purified flue gas is discharged from the purification tower 2 and discharged to the outside through the discharge device 1;

[0042] S4: The water falling into the purification tower accumulates at the bottom of the purification tower 2 and is discharged to the hot water pool 5b of the circulating water storage device 5 through a pipeline. The water in the hot water pool 5b enters the pulse automatic decontamination device 7 under the action of a water pump;

[0043] S5: The hot water entering the pulse automatic dirt removal device 7 first undergoes a cyclone in the cyclone drainer 71 to separate water and insoluble matter. The cyclone drainer 71 includes a main cyclone cylinder 711 and an eccentric filter cylinder 712. The main cyclone cylinder includes an inlet 7111, an upper outlet 7112, a discharge port 7113 and an inspection port 7114. In the main cyclone cylinder 711, dirt swirls along the cylinder wall under the action of water flow and its own gravity to the cylinder bottom outlet for discharge;

[0044] S6: The water separated by the cyclone drainer 71 enters the degassing drainer 72 through the upper outlet 7112. The degassing drainer 72 separates gas and water, performs spiral sedimentation and precision filtration, so that the insoluble gas accumulates in the gas buffer area at the top of the cylinder after entering the cylinder of the degassing drainer 72, and is discharged through the pressure automatic exhaust valve 721. The reacted water enters the heat pump unit 6 after being filtered. The separated insoluble matter and the filtered solid matter are further dehydrated and sent to the waste residue storage. The dehydrated water returns to the cold water tank through the pipeline;

[0045] S7: The water entering the heat pump unit 6 is sent to the cold water pool 5a of the circulating water storage device 5 after completing the heat exchange. The refrigerant in the heat pump unit 6 completes the heat exchange with the water entering the heat pump unit 6 and enters the heat network to heat the heating place;

[0046] S8: The refrigerant in the heat pump unit 6 is heated up in the evaporator and becomes a high-temperature, low-pressure gas, which is then converted into a high-temperature, high-pressure gas by the compressor. It enters the condenser to exchange heat with the water from the degassing drain device 72 and becomes a high-pressure, low-temperature liquid. It is then reduced in pressure by the throttle valve and becomes a low-temperature, low-pressure liquid and enters the evaporator for circulation.

[0047] Boiler flue gas (90-130℃) enters purification tower 2 through induced draft fan, and water enters purification tower 2 from cold water pool 5a, and is sprayed downward through cyclone atomizer 8. The falling water completes heat exchange with the rising flue gas, and dissolves and settles inorganic matter in the flue gas. After the flue gas is purified, it is defogged and further cooled by multi-stage cyclone demister 3, and then discharged from purification tower 2 and finally discharged through discharge device 1. According to the change of ambient temperature in winter, the flue gas temperature becomes 18-25℃. The water sprayed into the purification tower 2 accumulates at the bottom of the purification tower 2, and the water temperature rises by 10-15°C, and then is discharged to the hot water pool 5b of the circulating water storage device 5. The water in the hot water pool 5b is sent by the circulating water pump to the cyclone drain 71 and the degassing drain 72 connected in series. The water and the insoluble matter are separated by cyclone in the cyclone drain 71, and the separated water enters the degassing drain 72, where the gas is released by the reaction to form a precipitate. The reacted water enters the heat pump unit 6 after filtration, and the separated insoluble matter and the filtered solid matter are further dehydrated and sent to the waste residue storage. The dehydrated water returns to the cold water pool 5a of the circulating water storage device 5 through a pipeline. The water entering the heat pump unit 6 is sent to the cold water pool 5a of the circulating water storage device 5 after completing the heat exchange. The refrigerant in the heat pump unit 6 and the water entering the heat pump unit 6 complete the heat exchange and enter the heat network to heat the heating place. The refrigerant heats up in the evaporator and becomes a high-temperature, low-pressure gas. It then passes through the compressor and becomes a high-temperature, high-pressure gas. It then enters the condenser to exchange heat with the circulating water and becomes a high-pressure, low-temperature liquid. It then passes through the throttle valve to reduce the pressure and becomes a low-temperature, low-pressure liquid that enters the evaporator for circulation.

[0048] The circulating water storage device 5 adopts cold and hot partitions, including a pool wall 9 and a cold water pool 5a and a hot water pool 5b that are isolated from each other, an inner partition 91 is arranged between the two, and a balance overflow pipe 92 is left on the upper part of the inner partition 91. The circulating water storage device 5 can separate the hot and cold desulfurization slurry when the flue gas waste heat recovery purification system is running, and can also overflow balance when the cold water pool 5a and the hot water pool 5b are unevenly circulated, which is convenient for the actual operation of the system. The balance overflow pipe 92 can also make the desulfurization circulation system form a separate circulation to maintain operation when the flue gas waste heat recovery purification system stops running. The cold water pool 5a and the hot water pool 5b can be cast with concrete or brick-concrete structure during construction, or steel structure can be used to ensure structural strength. Then, a heat insulation layer 94 is formed on the surface using heat insulation materials such as rock wool to reduce the heat loss and conduction of the desulfurization slurry, and finally, a corrosion-resistant material such as glass flakes or PP is used on the surface for treatment to form a surface corrosion-resistant layer 93. The high-temperature circulating water flowing out of the purification tower 2 flows downstream to the hot water pool 5b, is sampled and tested and a slow-release scale inhibitor is added to reduce the hardness of the circulating water, and then is boosted by a circulating pump and flows through a pulse automatic decontamination device 7 to remove the silt particles and silicon-calcium compounds generated by the reaction in the circulating water, thereby improving the water quality of the circulating water. The purified high-temperature circulating water directly enters the heat pump unit 6 to release more waste heat into the heat exchange medium water. The circulating water discharged by the pulse automatic decontamination device 7 flows back to the cold water pool 5a, and is recycled after sedimentation and filtration, thereby improving and reducing the turbidity of the circulating water and reducing the discharged wastewater during the purification process.

[0049] The swirl atomizer 8 forms a high-kinetic energy liquid phase fluid by controlling the internal flow field and the circulation velocity distribution. At its tangential inlet section, an "L"-shaped air-assisted air intake pipe is connected, so that the airflow entering along the tangential direction helps to increase the outlet velocity of the nozzle as the inlet pressure increases, and the droplets show a significant decreasing trend. The high-kinetic energy liquid phase fluid increases the mixing intensity of the water flow and the airflow, and the turbulence of the droplets is enhanced, making the liquid film in a more unstable state and more prone to rupture.

[0050] The low-temperature saturated wet flue gas at the top of the purification tower 2 contains a large amount of dust and droplets. The cyclone demister 3 utilizes the mutual collision of a large number of particles of different particle sizes as the flue gas flow rises, and the droplets and fine ash particles condense and hit the blades under the action of the linear motion of the airflow. The liquid is gathered into liquid under the action of the centrifugal force of the blades, and flows back to the bottom of the tower under the action of its own gravity, so as to capture and remove the dust and droplets in the flue gas, thereby achieving the separation and purification of flue gas, droplets and dust, with good environmental protection performance and economic performance. According to the Gravimetric Method for Determining Low-Concentration Particles in Waste Gas from Stationary Pollution Sources (HJ836-2017), particle sampling and testing were carried out before and after the cyclone demister of the purification tower. According to the method for determining residual droplets in the flue gas at the demister outlet in the Demister for Special Equipment for Wet Flue Gas Desulfurization Devices (JB / T10989-2010), the conductivity of condensed water before and after the demister was continuously tested, proving that the cyclone demister has a higher efficiency in capturing residual droplets of desulfurization slurry than the flat-plate demister and the tube bundle demister.

[0051] The pollution removal mechanism of the cyclone discharger 71 in the pulse automatic pollution removal device 7 is as follows: water flows into the main cyclone cylinder 711 along the tangential direction, and under the action of centrifugal force and gravity, the mud and granular impurities therein sink into the pollution accumulation area of ​​the main cyclone cylinder 711. After the water flow of large particles of dirt is removed, it still contains tiny particles and insoluble gases that are difficult to capture and remove. In order to further reduce the scouring, wear and accumulation of particles in the water on system pipes and valves and other accessories, as well as the cavitation of the water pump impeller caused by insoluble gases, and to reduce gas-water impact accidents, an automatically operated degassing drainer 72 is connected in series after the cyclone separator 71. The degassing drainer 72 uses gas-water separation, spiral sedimentation, precision filtration and other functions to make the insoluble gas accumulate in the gas buffer area at the top of the cylinder after entering the cylinder of the degassing drainer 72, and is discharged through the pressure automatic exhaust valve 721. The degassing drainer 72 can effectively remove impurity particles larger than 5μm, and the impurity particles condense and settle in the pollution accumulation area at the bottom of the cylinder and are automatically discharged, which reduces labor intensity and saves water resources at the same time.

[0052] The above is a detailed introduction to a flue gas waste heat recovery and purification system provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core ideas of the present invention. For ordinary technicians in this field, the technical solution of the present invention is not limited to the solution defined by the specific implementation method. The technical solutions formed by other changes that can be obviously realized according to the common technical knowledge in this field are all within the protection scope of the present invention.

Claims

1. A flue gas waste heat recovery and purification system, comprising a discharge device (1), a purification tower (2), a circulating water storage device (5), a heat pump unit (6) and a pulse automatic decontamination device (7), wherein the flue gas inlet at the bottom of the purification tower (2) is connected to the flue gas outlet of the boiler through a pipeline, and the flue gas outlet at the top of the purification tower (2) is connected to the discharge device (1) through a pipeline, and the circulating water storage device (5) comprises a cold water pool (5a) and a hot water pool (5b) which are isolated from each other, and a cold water pool outlet (51), a cold water pool inlet (52) and a hot water pool outlet (53) are provided on the circulating water storage device (5). 2), a hot water pool outlet (53) and a hot water pool inlet (54); a spray device (4) and a multi-stage cyclone demister (3) located above the spray device (4) are provided inside the purification tower (2); the water inlet of the spray device (4) is connected to the cold water pool outlet (51) through a pipeline and includes a plurality of cyclone atomizers (8); the water outlet at the bottom of the purification tower (2) is connected to the hot water pool inlet (54) through a pipeline, the cold water pool inlet (52) is connected to the water outlet of the heat pump unit (6) through a pipeline, and the hot water pool outlet (53) is connected to the heat pump unit (6) through a pipeline. The pulse automatic dirt removal device (7) is connected to the pulse automatic dirt removal device (7); the pulse automatic dirt removal device (7) comprises a cyclone dirt remover (71) and a degassing dirt remover (72) connected in series with each other, the cyclone dirt remover (71) comprises a main cyclone cylinder (711) and an eccentric filter cylinder (712), the main cyclone cylinder (711) comprises a water inlet (7111), an upper outlet (7112), a discharge port (7113) and an inspection port (7114), the water inlet (7111) is connected to the hot water tank outlet (53) through a pipeline, and the upper outlet (7112) is connected to the degassing dirt remover (72). The degassing drain device (72) comprises a water outlet (723) and a pressure automatic exhaust valve (721), and the water outlet (723) is connected to the water inlet of the heat pump unit (6) through a pipeline; the discharge port (7113) of the cyclone drain device (71) and the degassing discharge port (722) of the degassing drain device (72) are respectively connected to the water inlet (52) of the cold water pool through pipelines; the cyclone demister (3) comprises a streamlined guide pipe (31), a three-stage centrifugal separation guide blade (32) and a droplet collection separator (33).

2. The flue gas waste heat recovery and purification system according to claim 1 is characterized in that: The cyclone atomizer (8) comprises a cyclone atomizer housing (81), a cyclone flow passage (82), an air flow inlet (83), a liquid phase inlet pipe (84), an atomized liquid outlet (85) and an air flow outlet (86). The cyclone atomizer housing (81) is annular. A liquid phase inlet pipe (84) is provided in the tangential direction of the cyclone atomizer housing (81) for receiving water flow from a cold water pool outlet (51). An "L"-shaped air-assisted air intake pipe is connected to the tangential inlet section of the cyclone atomizer housing (81). The air flow of the air-assisted air intake pipe is The inlet (83) and the liquid phase flow pipe (84) are perpendicular to each other, the air flow outlet (86) of the air-assisted air inlet pipe is parallel to the axis of the liquid phase flow pipe (84), and an atomized liquid outlet (85) is provided on the lower surface of the cyclone atomizer housing (81). The cyclone passage (82) is surrounded by the inner wall of the cyclone atomizer housing (81). The air flow and the water flow from the cold water pool outlet (51) simultaneously enter the cyclone passage (82) along a tangential direction, are mixed and accelerated, and are ejected from the atomized liquid outlet (85), forming an umbrella-shaped water mist composed of fine droplets.

3. The flue gas waste heat recovery and purification system according to claim 2 is characterized in that: The diameter of the cyclone atomizer housing (81) is 26-35 mm, and the diameter of the cyclone passage (82) is 8-12 mm.

4. The flue gas waste heat recovery and purification system according to any one of claims 1 to 3, characterized in that: The eccentric filter cylinder (712) has an eccentric angle of 56-61°, adopts an assembled structure, is made of stainless steel, and has an umbrella shape.

5. The flue gas waste heat recovery and purification system according to claim 4 is characterized in that: The eccentric angle of the eccentric filter cylinder (712) is 58°.

6. The flue gas waste heat recovery and purification system according to any one of claims 1 to 3, characterized in that: The degassing and sewage discharger (72) is controlled by a PLC chip, and controls the opening and closing of the solenoid valve or the electric valve according to the pressure difference, the turbidity of the outlet water or the operating time, and automatically discharges sewage during the operation.

7. The flue gas waste heat recovery and purification system according to any one of claims 1 to 3, characterized in that: The degassing and draining device (72) performs gas-water separation, spiral sedimentation and precision filtration so that the insoluble gas, after entering the cylinder of the degassing and draining device (72), accumulates in the gas buffer area at the top of the cylinder and is discharged through the pressure automatic exhaust valve (721).

8. The flue gas waste heat recovery and purification system according to any one of claims 1 to 3, characterized in that: A circulating water pump is provided on each pipeline.

9. The flue gas waste heat recovery and purification system according to any one of claims 1 to 3, characterized in that: The circulating water storage device (5) adopts cold and hot partitions, comprising a water pool wall (9), a surface corrosion-resistant layer (93), a heat-insulating layer (94), and a cold water pool (5a) and a hot water pool (5b) that are isolated from each other. An inner partition (91) is provided between the cold water pool (5a) and the hot water pool (5b), and a balancing overflow pipe (92) is left on the upper part of the inner partition (91).

10. The flue gas waste heat recovery and purification system according to any one of claims 1 to 3, characterized in that: The heat pump unit (6) is an anti-corrosion heat pump unit, which is connected to a heat network. Water in the heat network returns to the heat network after undergoing heat exchange with the heat pump unit (6).

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