A waste incineration fly ash resource recovery system based on molten salt heat treatment technology

Abstract

This invention discloses a waste incineration fly ash resource recovery system based on molten salt heat treatment technology, comprising a molten salt furnace system, a molten salt cooling and recovery system, a brine purification system, an MVR evaporation and salt separation system, and a rapid cooling water quenching system. The molten salt furnace system includes a molten salt furnace and a heating mechanism for heating the molten salt. The molten salt cooling and recovery system includes a slag cooler. The brine purification system dissolves the solid salt blocks discharged from the slag cooler to form brine and purifies the brine. The MVR evaporation and salt separation system evaporates and crystallizes the purified brine discharged from the brine purification system to obtain salt products. The beneficial effects of this invention are as follows: it solves the problems of fly ash resource recovery and secondary flue gas generation; it does not generate large amounts of harmful secondary flue gas during the process, eliminating the risk of secondary pollution; it saves significant investment and operating costs for auxiliary flue gas purification systems; and it enables the resource recovery of inorganic salts contained in fly ash.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hazardous solid waste treatment, in particular to a waste incineration fly ash resource treatment system based on molten salt heat treatment technology. BACKGROUND

[0002] Currently, the main disposal methods of fly ash are: chelation landfill, water washing + cement kiln co-disposal, high temperature melting.

[0003] Chelation landfill is to mix fly ash, heavy metal chelating agent, cement, etc. in a certain proportion, to stabilize heavy metals in fly ash, reduce the leaching toxicity of fly ash, and then be sent to a safe landfill for disposal. This technology is the mainstream of fly ash disposal at present because of its low disposal cost, simple and reliable process. However, it has occupied a large amount of land resources and cannot meet the development requirements of China. In the future, it will be gradually replaced on a large scale and only used as an emergency treatment method.

[0004] Water washing + cement kiln co-disposal is to wash fly ash with a certain proportion of water by mixing pulp, leaching, etc. to reduce the content of chloride salt in the ash residue to below 1%, and then send it to the cement kiln for co-disposal. Fly ash is used as part of the cement production raw material, and the heavy metals in it can be fixed in the cement product. In addition, the fly ash washing liquid contains a large amount of Na and K salts, which can be recovered after purification, conditioning, evaporation crystallization and other processes and used as industrial salt. Water washing + cement kiln co-disposal realizes the resource disposal of fly ash and is an ideal disposal method for fly ash. However, this process needs to be co-disposed with a cement kiln, so it must rely on the construction of a cement plant. In addition, the washed fly ash is still a hazardous waste, which also has the problem of cross-border transportation, which seriously restricts the application range of this process.

[0005] High temperature melting technology uses one or more of plasma heating, electrode heating, resistance heating, chemical fuel heating, etc. to heat fly ash to 1300-1500℃. Fly ash is in a molten state at this temperature, and dioxins are decomposed at high temperature during the melting process. The molten fly ash becomes a glass body with large density (about 2.5t / m 3 ), hard texture after cooling. The glass body is mainly composed of Ca, Si, Al, Fe and other elements, and the heavy metals in fly ash are firmly locked in the crystal lattice. High temperature melting is the most thorough harmless treatment method for fly ash, with good volume reduction effect (more than 70%), stable and reliable treatment effect, simple process flow, and can be directly supported by the construction of a waste incineration plant. The glass body produced can also be used for resource utilization.

[0006] At present, the high-temperature melting disposal process of fly ash generally adopts plasma melting technology, which has good heating effect, but high energy consumption. In addition, secondary flue gas will be generated in the high-temperature melting process, which contains a large amount of dust particles and volatilized heavy metals and chlorides, so a complex flue gas purification system needs to be separately configured, which further increases the disposal cost of fly ash, resulting in that the disposal cost of fly ash by the plasma melting process is as high as 2000-3000 yuan / ton; in addition, the fly ash contains a large amount of inorganic salts, and the current high-temperature plasma melting process not only cannot effectively recover the inorganic salts in the fly ash, but also volatilizes a large amount of inorganic salts into the flue gas, which not only wastes resources, but also increases the difficulty of disposal of the flue gas at the back end. The present application can effectively extract and recover the inorganic salts in the fly ash, and realize the comprehensive resource utilization of fly ash. SUMMARY

[0007] Therefore, it is necessary to provide a waste incineration fly ash resource treatment system based on molten salt heat treatment technology to solve the technical problems that the high-temperature melting disposal process of fly ash generates secondary flue gas in the high-temperature melting process, has high disposal cost, and cannot effectively recover the inorganic salts in the fly ash.

[0008] In order to achieve the above-mentioned purpose, the present application provides a waste incineration fly ash resource treatment system based on molten salt heat treatment technology, comprising:

[0009] a molten salt furnace system, the molten salt furnace system comprising a molten salt furnace and a heating mechanism, the molten salt furnace being provided with molten salt, the molten salt being used for treating the fly ash after compounding, and the heating mechanism being used for heating the molten salt;

[0010] a molten salt cooling and recovery system, the molten salt cooling and recovery system comprising a slag cooler, the slag cooler being used for cooling the molten salt discharged from the molten salt furnace into solid salt blocks;

[0011] a brine purification system, the brine purification system being used for dissolving the solid salt blocks discharged from the slag cooler to form brine, and purifying the brine;

[0012] an MVR evaporation and salt separation system, the MVR evaporation and salt separation system being used for evaporating and crystallizing the purified brine discharged from the brine purification system to obtain salt products; and

[0013] a quenching water quenching system, the quenching water quenching system being used for water quenching the molten slag discharged from the molten salt furnace to form glass body particles.

[0014] In some embodiments, the waste incineration fly ash resource processing system based on molten salt heat treatment technology further comprises a pretreatment system, the pretreatment system comprises a crusher, a grinder, a mixer and a granulator, the crusher and the grinder are used for crushing and grinding of compatible adjuvants, the mixer is used for uniformly mixing fly ash and ground compatible adjuvants, and the granulator is used for granulating the mixed material.

[0015] In some embodiments, the waste incineration fly ash resource processing system based on molten salt heat treatment technology further comprises a feeding system for feeding the compatible material to the molten salt furnace system, the feeding system comprises a first conveying cylinder, a first shaftless screw and a first rotating driving member, one end of the first conveying cylinder is provided with a first feeding port, the other end of the first conveying cylinder is provided with a first discharging port, the first shaftless screw is rotatably arranged in the first conveying cylinder, and the first rotating driving member is connected with the first shaftless screw and used for driving the first shaftless screw to rotate.

[0016] In some embodiments, the feeding system further comprises a hopper for storing the compatible material, the outlet of the hopper is in communication with the first feeding port, and the outlet of the hopper is provided with a discharging valve.

[0017] In some embodiments, the molten salt furnace comprises a furnace body and a furnace cover covering the furnace body, the furnace cover is provided with a gas collecting port, an observation port and an electrode insertion port, the upper part of one side of the furnace body is provided with a fly ash feeding port, the fly ash feeding port is in communication with the first discharging port, the lower part of the other side of the furnace body is provided with a molten salt overflow port, the lower end of the furnace body is provided with a slag discharging port, and the heating mechanism comprises a heating electrode and an electric control device, the heating electrode is inserted into the furnace body through the electrode insertion port and extends to the molten slag layer, the electric control device is electrically connected with the heating electrode to realize power supply to the heating electrode and temperature control.

[0018] In some embodiments, the molten salt cooling and recycling system further comprises a temporary storage salt bin, the slag cooler comprises a second conveying cylinder, a second shaftless screw, a second rotating driving member and a cooling water circulating mechanism, one end of the second conveying cylinder is provided with a second feeding port, the second feeding port is in communication with the upper end of the overflow pipe, the other end of the second conveying cylinder is provided with a second discharging port, the second discharging port is in communication with the inlet of the temporary storage salt bin, a cooling water channel is formed in the side wall of the second conveying cylinder, one end of the side wall of the second conveying cylinder is provided with a cooling water inlet in communication with the cooling water channel, the other end of the side wall of the second conveying cylinder is provided with a cooling water outlet in communication with the cooling water channel, the second shaftless screw is rotatably arranged in the second conveying cylinder, the second rotating driving member is connected with the second shaftless screw and is used for driving the second shaftless screw to rotate, the cooling water circulating mechanism comprises a cooling water pool, a water inlet pump and a radiator, the inlet of the water inlet pump is in communication with the cooling water pool, the outlet of the water inlet pump is in communication with the cooling water inlet, the inlet of the radiator is in communication with the cooling water outlet, and the outlet of the radiator is in communication with the cooling water pool.

[0019] In some embodiments, the second rotating driving member comprises a second motor and a second speed reducer, the output end of the second motor is connected with the input end of the second speed reducer, and the output end of the second speed reducer is connected with the second shaftless screw.

[0020] In some embodiments, the salt water purification system comprises a dissolving mechanism, a liquid pump and a purification mechanism, the dissolving mechanism comprises a dissolving tank, the inlet of the dissolving tank is in communication with the outlet of the temporary storage salt bin, the inlet of the liquid pump is in communication with the outlet of the dissolving tank, the purification mechanism comprises a first reaction pool, a second reaction pool, a third reaction pool, a fourth reaction pool and a fifth reaction pool, the inlet of the first reaction pool is in communication with the outlet of the liquid pump, the first reaction pool is provided with a first dosing port for adding Na2SO4 solution and PAC, the inlet of the second reaction pool is in communication with the outlet of the first reaction pool, the second reaction pool is provided with a second dosing port for adding PAM, the inlet of the third reaction pool is in communication with the outlet of the second reaction pool, the third reaction pool is provided with a third dosing port for adding hydrochloric acid, the inlet of the fourth reaction pool is in communication with the outlet of the third reaction pool, the fourth reaction pool is provided with a fourth dosing port for adding PAC, heavy metal capturing agent and Na2CO3 solution, and the inlet of the fifth reaction pool is in communication with the outlet of the fourth reaction pool, and the fifth reaction pool is provided with a fifth dosing port for adding PAM.

[0021] In some embodiments, the quenching water quenching system comprises a water quenching pool, a slag skimmer and a heat exchange pipe row, the water quenching pool is arranged below the slag discharging port, and the slag skimmer and the heat exchange pipe are integrated in the water quenching pool.

[0022] In some embodiments, the waste incineration fly ash resource utilization system based on molten salt heat treatment technology further includes a flue gas purification system. The flue gas purification system includes a quench tower, a bag filter, an induced draft fan, and a chimney. The inlet of the quench tower is connected to the gas collection port, the outlet of the quench tower is connected to the inlet of the bag filter, the outlet of the bag filter is connected to the inlet of the induced draft fan, and the outlet of the induced draft fan is connected to the inlet of the chimney.

[0023] Compared with the prior art, the beneficial effects of the technical solution proposed in this invention are as follows:

[0024] (1) It realizes the complete resource utilization of fly ash from municipal solid waste incineration. At the same time, the process flow is short and the equipment layout is compact. It can be directly built based on existing waste incineration plants without considering the issue of coordination with other processes.

[0025] (2) The problem of secondary flue gas has been solved. This process uses molten salt high-temperature melting to treat fly ash. During the process, a large amount of harmful secondary flue gas will not be generated, and there is no risk of secondary pollution.

[0026] (3) Cost saving: Since there is no large amount of secondary harmful flue gas generated, the investment and operating costs of the auxiliary flue gas purification system are saved. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of an embodiment of the waste incineration fly ash resource utilization system based on molten salt heat treatment technology provided by the present invention;

[0028] Figure 2 yes Figure 1 A schematic diagram of the feeding system and molten salt furnace system in the middle;

[0029] Figure 3 yes Figure 1 A schematic diagram of the molten salt cooling and recovery system in the diagram;

[0030] Figure 4 yes Figure 3 A magnified view of a portion of region A in the middle;

[0031] Figure 5 yes Figure 3 A schematic diagram of the cooling water circulation mechanism in the diagram;

[0032] Figure 6 yes Figure 1 A schematic diagram of the brine purification system in the diagram;

[0033] In the diagram: 1-Feeding system, 11-First conveyor cylinder, 111-First feed inlet, 112-First discharge outlet, 12-First shaftless screw, 13-First rotating drive component, 131-First motor, 132-First reducer, 14-Hopper, 141-Discharge valve, 2-Molten salt furnace system, 21-Molten salt furnace, 211-Furnace body, 2111-Fly ash feed inlet, 2112-Molten salt overflow outlet, 2113-Slag discharge outlet, 2114-Melting zone, 2115-Molten salt zone, 2116-Cavity zone, 212-Furnace cover, 2121-Gas collection port, 2122- Observation port, 213-overflow pipe, 22-heating mechanism, 221-heating electrode, 3-molten salt cooling and recovery system, 31-slag cooler, 311-second conveying cylinder, 3111-second feed inlet, 3112-second discharge outlet, 3113-cooling water channel, 3114-cooling water inlet, 3115-cooling water outlet, 312-second shaftless screw, 313-second rotation drive component, 3131-second motor, 3132-second reducer, 314-cooling water circulation mechanism, 3141-cooling water pool, 31411-pool body, 314111- First water tank, 314112-Second water tank, 31412-Baffle, 314121-Connecting hole, 31413-One-way valve, 31414-Mesh cover, 3142-Inlet pump, 3143-Radiator, 31431-First water tank, 31432-Second water tank, 31433-Radiator pipe, 3144-Outlet pump, 3145-Drain pipe, 32-Temporary salt storage tank, 4-Brine purification system, 41-Dissolving mechanism, 411-Dissolving tank, 4111-Dissolving stirrer, 42-Liquid pump, 43-Purification mechanism, 431-First reaction tank, 431 1-First dosing port, 4312-First stirrer, 432-Second reaction tank, 4321-Second dosing port, 4322-Second stirrer, 433-Third reaction tank, 4331-Third dosing port, 4332-Third stirrer, 434-Fourth reaction tank, 4341-Fourth dosing port, 4342-Fourth stirrer, 435-Fifth reaction tank, 4351-Fifth dosing port, 4352-Fifth stirrer, 436-First inclined plate sedimentation tank, 437-Second inclined plate sedimentation tank, 438-Clear water tank, 5-Quenching water system, 51-Water quenching tank. Detailed Implementation

[0034] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0035] Please refer to Figures 1-6This invention provides a waste incineration fly ash resource recovery system based on molten salt heat treatment technology, including a pretreatment system, a feeding system 1, a molten salt furnace system 2, a molten salt cooling and recovery system 3, a brine purification system 4, an MVR evaporation and salt separation system, a rapid cooling water quenching system 5, and a flue gas purification system.

[0036] The pretreatment system includes a crusher, a grinder, a mixer, and a granulator. The crusher and grinder are used for crushing and grinding the auxiliary materials. The mixer is used to uniformly mix the fly ash with the ground auxiliary materials. The granulator is used to form the mixed material into particles with a particle size of 10-20 mm. The purpose of the pretreatment system is to reduce the temperature required for fly ash melting, thereby saving energy and extending the service life of the molten salt furnace. Before melting, the fly ash needs to be blended. The auxiliary materials can be selected from fly ash, slag, waste glass, etc., and the proportion of auxiliary materials added can be adjusted from 10% to 30% depending on the composition of the incoming fly ash.

[0037] Please refer to Figure 1 and Figure 2 The feeding system 1 is used to convey the mixed materials to the molten salt furnace system 2. The feeding system 1 includes a first conveying cylinder 11, a first shaftless screw 12, and a first rotation drive 13. One end of the first conveying cylinder 11 has a first inlet 111, and the other end has a first outlet 112. The first shaftless screw 12 is rotatably disposed inside the first conveying cylinder 11. The first rotation drive 13 is connected to the first shaftless screw 12 and is used to drive the first shaftless screw 12 to rotate. In use, the mixed materials are fed into the first inlet 111, and the first rotation drive 13 drives the first shaftless screw 12 to rotate, thereby moving the mixed materials inside the first conveying cylinder 11 and discharging them from the first outlet 112.

[0038] Preferably, please refer to Figure 1 and Figure 2 The feeding system 1 further includes a hopper 14, which is used to store the mixed materials. The outlet of the hopper 14 is connected to the first feed inlet 111, and the outlet of the hopper 14 is equipped with a discharge valve 141. By setting up the hopper 14, the mixed materials can be conveniently stored.

[0039] Specifically, please refer to Figure 1 and Figure 2 The first rotation drive 13 includes a first motor 131 and a first reducer 132. The output end of the first motor 131 is connected to the input end of the first reducer 132, and the output end of the first reducer 132 is connected to the first shaftless screw 12.

[0040] Please refer to Figure 1 andFigure 2 The molten salt furnace system 2 includes a molten salt furnace 21 and a heating mechanism 22. The molten salt furnace 21 contains molten salt, which is used to treat the mixed fly ash. The heating mechanism 22 is used to heat the molten salt.

[0041] Specifically, the molten salt furnace 21 includes a furnace body 211 and a furnace cover 212 covering the furnace body 211. The furnace cover 212 has a gas collecting port 2121, an observation port 2122, and an electrode insertion port. A fly ash inlet 2111 is located on the upper part of one side of the furnace body 211, and the fly ash inlet 2111 is connected to the first discharge port 112. A molten salt overflow port 2112 is located on the lower part of the other side of the furnace body 211, and a slag discharge port 2113 is located at the bottom of the furnace body 211. The heating mechanism 22 includes a heating electrode 221 and an electrical control device. The heating electrode 221 is inserted into the furnace body 211 through the electrode insertion port and extends therein. The electrical control device is electrically connected to the heating electrode 221 to supply power to the heating electrode 221 and control its temperature. During normal operation, the molten salt furnace 21 should ensure that the mass ratio of molten salt to fly ash is not less than 5:1, ensuring sufficient contact and reaction conditions for the fly ash in the molten salt. The interior of the furnace body 211 can be divided into a molten zone 2114, a molten salt zone 2115, and a cavity zone 2116 from bottom to top. The heating electrode 221 must extend into the molten zone 2114. During normal operation, the temperature from the molten salt zone 2115 to the bottom molten zone 2114 should be maintained within the range of 800-1300℃ by means of temperature control, adjustment of feed rate, and adjustment of discharge rate.

[0042] In operation, the mixed materials are conveyed to the first feed inlet 111. The first rotating drive component 13 drives the first shaftless screw 12 to rotate, thereby moving the mixed materials within the first conveying cylinder 11 and discharging them from the first discharge outlet 112 into the fly ash feed inlet 2111, and then into the furnace body 211. The furnace body 211 is filled with molten salt of the NaCl-KCl system. Due to the density difference between the molten salt and the material particles, the material particles sink and undergo dissolution and melting reactions during this process. Some of the inorganic salts in the fly ash dissolve in the molten salt, becoming part of the molten salt system, while the remainder sinks to the bottom and forms a molten glass under high temperature.

[0043] Preferably, the molten salt furnace 21 further includes an overflow pipe 213, which is vertically arranged. The lower end of the overflow pipe 213 is connected to the molten salt overflow port 2112, and the upper end of the overflow pipe 213 is used to connect to the molten salt cooling and recovery system 3. The height of the upper end of the overflow pipe 213 is the boundary between the molten salt zone 2115 and the cavity zone 2116. When the liquid level in the molten salt furnace 21 is higher than the height of the upper end of the overflow pipe 213, the molten salt in the molten salt furnace 21 will overflow from the upper end of the overflow pipe 213, thereby ensuring that the molten salt liquid level in the molten salt furnace 21 is stable.

[0044] Please refer to Figure 1 , Figure 3 and Figure 4 The molten salt cooling and recovery system 3 includes a slag cooler 31 and a temporary salt storage tank 32. The slag cooler 31 is used to cool the molten salt discharged from the molten salt furnace 21 into solid salt blocks.

[0045] Specifically, the slag cooler 31 includes a second conveying cylinder 311, a second shaftless screw 312, a second rotating drive component 313, and a cooling water circulation mechanism 314. One end of the second conveying cylinder 311 has a second feed inlet 3111, which is connected to the upper end of the overflow pipe 213. The other end of the second conveying cylinder 311 has a second discharge outlet 3112, which is connected to the inlet of the temporary salt storage bin 32. A cooling water channel 3113 is formed inside the side wall of the second conveying cylinder 311. One end of the side wall of the second conveying cylinder 311 has a cooling water inlet 3114 connected to the cooling water channel 3113. The other end of the side wall of the second conveying cylinder 311... A cooling water outlet 3115 is provided, which communicates with the cooling water channel 3113. The second shaftless spiral 312 is rotatably disposed inside the second conveying cylinder 311. The second rotation drive member 313 is connected to the second shaftless spiral 312 and is used to drive the second shaftless spiral 312 to rotate. The cooling water circulation mechanism 314 includes a cooling water pool 3141, an inlet pump 3142, and a radiator 3143. The inlet of the inlet pump 3142 is connected to the cooling water pool 3141, and the outlet of the inlet pump 3142 is connected to the cooling water inlet 3114. The inlet of the radiator 3143 is connected to the cooling water outlet 3115, and the outlet of the radiator 3143 is connected to the cooling water pool 3141.

[0046] During use, the molten salt in the molten salt furnace 21 gradually increases with the increase of fly ash treatment. The excess molten salt needs to be discharged to maintain the normal liquid level in the furnace body 211. The molten salt overflows from the upper end of the overflow pipe 213 and then enters the second conveying cylinder 311 of the slag cooler through the second feed port 3111. The second rotating drive component 313 drives the second shaftless screw 312 to rotate, thereby causing the molten salt to flow in the second conveying cylinder 311. At the same time, cold water is introduced into the side wall of the second conveying cylinder 311 through the water pump 3142. Under the cooling effect of the partition wall, the molten salt in the second conveying cylinder 311 gradually solidifies. At the same time, the molten salt is crushed by the squeezing and cutting action of the second shaftless screw 312, so that the molten salt is discharged from the second discharge port 3112 in small blocks, which is beneficial for downstream recycling. The blocky salt discharged from the slag cooler enters the temporary salt storage bin 32.

[0047] Specifically, please refer to Figure 1 andFigure 3 The second rotation drive 313 includes a second motor 3131 and a second reducer 3132. The output end of the second motor 3131 is connected to the input end of the second reducer 3132, and the output end of the second reducer 3132 is connected to the second shaftless screw 312.

[0048] Preferably, please refer to Figures 1-5 In order to improve the cooling water circulation efficiency, the cooling water circulation mechanism 314 also includes an outlet pump 3144, the inlet of which is connected to the cooling water outlet 3115, and the outlet of which is connected to the inlet of the radiator 3143.

[0049] Preferably, please refer to Figures 1-5 The radiator 3143 includes a first water tank 31431, a second water tank 31432, and a plurality of heat dissipation pipes 31433. The first water tank 31431 is connected to the outlet of the water pump 3144, the second water tank 31432 is connected to the cooling water pool 3141, one end of each heat dissipation pipe 31433 is connected to the first water tank 31431, and the other end of each heat dissipation pipe 31433 is connected to the second water tank 31432.

[0050] Specifically, please refer to Figures 1-5 The second water tank 31432 is connected to the cooling water pool 3141 via a drain pipe 3145.

[0051] Preferably, please refer to Figures 1-5 The cooling water tank 3141 includes a tank body 31411 and a partition 31412. The partition 31412 is vertically disposed within the tank body 31411 and divides the tank body 31411 into a first tank 314111 and a second tank 314112. A connecting hole 314121 is provided on the partition 31412. The first tank 314111 is connected to the drain pipe 3145, and the second tank 314112 is connected to the inlet of the water pump 3142. By setting up the first tank 314111 and the second tank 314112, the water discharged from the heat dissipation pipe 31433 first enters the first tank 314111 for natural cooling, and then enters the second tank 314112 to supply water to the water pump 3142, thereby improving the cooling effect.

[0052] Preferably, please refer to Figures 1-5 The cooling water pool 3141 also includes a one-way valve 31413, which is disposed in the connecting hole 314121. The one-way valve 31413 only allows water in the first water pool 314111 to enter the second water pool 314112, thereby reducing heat convection between the two water pools.

[0053] Preferably, please refer to Figures 1-5 The cooling water pool 3141 also includes a mesh cover 31414, which covers the outside of the connecting hole 314121, thereby intercepting impurities.

[0054] Preferably, the cooling water circulation mechanism 314 further includes a water supply pipe, one end of which is connected to a water source, and the other end of which is connected to the cooling water pool 3141. A water supply valve is provided on the water supply pipe.

[0055] The brine purification system 4 is used to dissolve the solid salt blocks discharged from the cold slag machine 31 to form brine, and to purify the brine.

[0056] Specifically, please refer to Figure 1 and Figure 6 The brine purification system 4 includes a dissolving mechanism 41, a liquid pump 42, and a purification mechanism 43. The dissolving mechanism 41 includes a dissolving tank 411, the inlet of which is connected to the outlet of the temporary salt storage tank 32. The inlet of the liquid pump 42 is connected to the outlet of the dissolving tank 411. The purification mechanism 43 includes a first reaction tank 431, a second reaction tank 432, a third reaction tank 433, a fourth reaction tank 434, and a fifth reaction tank 435. The inlet of the first reaction tank 431 is connected to the outlet of the liquid pump 42. The first reaction tank 431 is provided with a first dosing port 4311 for adding Na2SO4 solution and PAC (polyaluminum chloride). The inlet of the second reaction tank 432 is connected to the outlet of the first reaction tank 431. The second reaction tank 432 is provided with a second dosing port 4321 for adding PAM (polyacrylamide). The inlet of the third reaction tank 433 is connected to the outlet of the second reaction tank 432. The third reaction tank 433 is provided with a third dosing port 4331 for adding hydrochloric acid. The inlet of the fourth reaction tank 434 is connected to the outlet of the third reaction tank 433. The fourth reaction tank 434 is provided with a fourth dosing port 4341 for adding PAC, a heavy metal scavenger (mainly composed of Na2S), and Na2CO3 solution. The inlet of the fifth reaction tank 435 is connected to the outlet of the fourth reaction tank 434. The fifth reaction tank 435 is provided with a fifth dosing port 4351 for adding PAM.

[0057] During use, the lumpy salt in the temporary salt storage tank 32 is discharged into the dissolving tank 411. At the same time, water is added to the dissolving tank 411 to dissolve the lumpy salt and form brine. The brine is introduced into the first reaction tank 431 via the liquid pump 42, where it reacts with Na2SO4 solution and PAC to perform primary hardening removal. Then, the brine enters the second reaction tank 432 to react with PAM to perform flocculation and sedimentation. After that, the brine enters the third reaction tank 433 to react with hydrochloric acid to adjust the pH. Then, the brine enters the fourth reaction tank 434 to react with PAC, heavy metal precipitator and Na2CO3 solution to perform secondary hardening and heavy metal removal. After that, the brine enters the fifth reaction tank 435 to react with PAM to perform flocculation and sedimentation. The brine after the above treatment can meet the standards for industrial salt.

[0058] The processes of primary hardening, secondary hardening, and heavy metal removal generate sludge. Therefore, a solid-liquid separation device is required to separate the sludge from the brine, and the separated sludge is returned to the compounding and granulation process.

[0059] Specifically:

[0060] The purification mechanism 43 also includes a first inclined plate sedimentation tank 436, the inlet of which is connected to the outlet of the second reaction tank 432, and the outlet of which is connected to the inlet of the third reaction tank 433, thereby separating the sludge generated in the first reaction tank 431 and the second reaction tank 432.

[0061] The purification mechanism 43 also includes a second inclined plate sedimentation tank 437 and a clear water tank 438. The inlet of the second inclined plate sedimentation tank 437 is connected to the outlet of the fifth reaction tank 435, and the outlet of the second inclined plate sedimentation tank 437 is connected to the inlet of the clear water tank 438, so that the sludge generated in the third reaction tank 433, the fourth reaction tank 434 and the fifth reaction tank 435 can be separated. The clear water tank 438 is used to collect the purified brine.

[0062] Preferably, please refer to Figure 1 and Figure 6 The dissolving tank 411 is equipped with a dissolving stirrer 4111.

[0063] Preferably, please refer to Figure 1 and Figure 6 The first reaction tank 431 is equipped with a first stirrer 4312, the second reaction tank 432 is equipped with a second stirrer 4322, the third reaction tank 433 is equipped with a third stirrer 4332, the fourth reaction tank 434 is equipped with a fourth stirrer 4342, and the fifth reaction tank 435 is equipped with a fifth stirrer 4352.

[0064] The MVR evaporation and salt separation system is used to evaporate and crystallize the purified brine discharged from the brine purification system 4 to obtain salt products.

[0065] Specifically, please refer to Figure 1 and Figure 6 The MVR evaporation and salt separation system is connected to the clear water tank 438 and is used to evaporate and crystallize the brine discharged from the clear water tank 438 to obtain salt products.

[0066] Specifically, the MVR evaporation and salt separation system includes a compressor, heat exchanger, evaporator, separator, first thickener, second thickener, condenser, first solid-liquid separation device, second solid-liquid separation device, first drying device, and second drying device. The purified brine is heated by the evaporator and then enters the separator for gas-liquid separation. Water is continuously evaporated, and the secondary steam is extracted by the compressor, compressed again, and recycled for evaporation and heating. The brine is continuously concentrated at the bottom of the separator. When the brine reaches its saturation point, sodium (Na) salt precipitates first. The first thickener then thickens and recovers the Na salt. The first batch of brine slurry is dehydrated using the first solid-liquid separation device and then further dehydrated in the first drying device. The resulting salt is NaCl. The brine separated by the first thickener is cooled, causing potassium (K) salt crystals to precipitate. It then enters the second thickener for thickening. The resulting brine slurry subsequently passes through the second solid-liquid separation device and the second drying device to obtain KCl. The brine obtained from the second thickener and second solid-liquid separation device is recycled as mother liquor to the MVR feed water. All the condensate generated by the system is recycled and used as water for dissolving salt blocks.

[0067] In use, small salt blocks are transported to dissolving tank 411, mixed with a certain proportion of clean water, stirred, and dissolved to form a 30% (by mass) salt solution (based on total chlorine). Subsequently, the salt solution undergoes two stages of hardness removal, pH adjustment, heavy metal removal, and ultrafiltration in brine purification system 4, until the brine meets the downstream process water quality requirements. The qualified brine then enters the MVR evaporation and salt separation system, where it undergoes preheating, evaporation concentration, and cooling crystallization processes to obtain sodium chloride and potassium chloride salt products, which can be used as industrial salt.

[0068] like Figure 1 and Figure 2 The rapid cooling water quenching system 5 is used to quench the molten slag discharged from the molten salt furnace 21 to form glassy particles.

[0069] Specifically, the rapid cooling water quenching system 5 includes a water quenching tank 51, a slag remover, and a heat exchange tube bank. The water quenching tank 51 is located below the slag discharge port 2113, and the slag remover and the heat exchange tubes are integrated into the water quenching tank 51. The molten slag discharged from the slag discharge port 2113 of the molten salt furnace 21 falls directly into the water quenching tank 51. The slag remover can remove the glass particles that have sunk to the bottom of the water quenching tank. Cooling water is circulated through the heat exchange tube bank to cool the water temperature in the water quenching tank 51. By controlling the discharge rate of the molten slag, it can form glass particles with uniform particle size and hard texture when cooled in the water quenching tank. Since the molten slag inevitably carries some molten salt into the water quenching tank 51, increasing the salt content of the water in the water quenching tank 51, the water quenching water in the water quenching tank 51 needs to be isolated from the external circulating cooling water. When the salt content of the water quenching water reaches 30% (calculated as total chlorine), it needs to be replaced and pumped into the brine tank of the water purification system. Slag removal equipment is used to retrieve glass particles that have sunk to the bottom of the water quenching tank, and can then package and sell them for use as building material aggregates, etc.

[0070] The flue gas purification system includes a quench tower, a bag filter, an induced draft fan, and a chimney. The inlet of the quench tower is connected to the gas collection port 2121, the outlet of the quench tower is connected to the inlet of the bag filter, the outlet of the bag filter is connected to the inlet of the induced draft fan, and the outlet of the induced draft fan is connected to the inlet of the chimney. The quench tower is used to rapidly cool the high-temperature flue gas collected from the molten salt furnace, reducing it to below 200°C. The flue gas then enters the bag filter for further purification. The induced draft fan provides the flow power for the flue gas and maintains a slight negative pressure state in the front-end system.

[0071] The beneficial effects of the waste incineration fly ash resource recovery system based on molten salt heat treatment technology provided by this invention are as follows:

[0072] (1) The problem of fly ash resource utilization has been solved. Similar to the fly ash washing + cement kiln co-process, this invention realizes the complete resource utilization of fly ash from municipal solid waste incineration. However, this process can be directly built based on existing waste incineration plants without considering the problem of co-operation with other projects.

[0073] (2) The problem of secondary flue gas has been solved. This process uses molten salt high-temperature melting to treat fly ash. During the process, a large amount of harmful secondary flue gas will not be generated, and there is no risk of secondary pollution.

[0074] (3) Cost-saving: Compared with processes such as plasma melting, this process uses electrode heating as the main heating method, which has a high electrothermal conversion rate and low energy consumption. At the same time, since no large amount of secondary harmful flue gas is generated, it saves a lot of investment and operating costs for auxiliary flue gas purification systems.

[0075] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A waste incineration fly ash resource processing system based on molten salt heat treatment technology, characterized in that, Comprise: a molten salt furnace system, which comprises a molten salt furnace containing molten salt for treating the fly ash after compounding, and a heating mechanism for heating the molten salt; a molten salt cooling and recovery system, which comprises a slag cooler for cooling the molten salt discharged from the molten salt furnace into solid salt blocks; a brine purification system for dissolving the solid salt blocks discharged from the slag cooler into brine and purifying the brine; an MVR evaporation and salt separation system for evaporating and crystallizing the purified brine discharged from the brine purification system to obtain salt products; and a quenching water quenching system for water quenching the molten slag discharged from the molten salt furnace to form glass particles. The molten salt cooling and recycling system further comprises a temporary storage salt bin, the slag cooler comprises a second conveying cylinder, a second shaftless screw, a second rotating driving member and a cooling water circulating mechanism, one end of the second conveying cylinder is provided with a second feeding port, the second feeding port is communicated with the upper end of the overflow pipe, the other end of the second conveying cylinder is provided with a second discharging port, the second discharging port is communicated with the inlet of the temporary storage salt bin, a cooling water channel is formed in the side wall of the second conveying cylinder, one end of the side wall of the second conveying cylinder is provided with a cooling water inlet communicated with the cooling water channel, the other end of the side wall of the second conveying cylinder is provided with a cooling water outlet communicated with the cooling water channel, the second shaftless screw is rotatably arranged in the second conveying cylinder, the second rotating driving member is connected with the second shaftless screw and is used for driving the second shaftless screw to rotate, the cooling water circulating mechanism comprises a cooling water pool, a water inlet pump and a radiator, the inlet of the water inlet pump is communicated with the cooling water pool, the outlet of the water inlet pump is communicated with the cooling water inlet, the inlet of the radiator is communicated with the cooling water outlet, and the outlet of the radiator is communicated with the cooling water pool; the salt water purification system comprises a dissolving mechanism, a liquid pump and a purification mechanism, the dissolving mechanism comprises a dissolving tank, the inlet of the dissolving tank is communicated with the outlet of the temporary storage salt bin, the inlet of the liquid pump is communicated with the outlet of the dissolving tank, the purification mechanism comprises a first reaction pool, a second reaction pool, a third reaction pool, a fourth reaction pool and a fifth reaction pool, the inlet of the first reaction pool is communicated with the outlet of the liquid pump, a first dosing port for adding Na2SO4 solution and PAC is arranged on the first reaction pool, the inlet of the second reaction pool is communicated with the outlet of the first reaction pool, a second dosing port for adding PAM is arranged on the second reaction pool, the inlet of the third reaction pool is communicated with the outlet of the second reaction pool, a third dosing port for adding hydrochloric acid is arranged on the third reaction pool, the inlet of the fourth reaction pool is communicated with the outlet of the third reaction pool, a fourth dosing port for adding PAC, a heavy metal capturing agent and Na2CO3 solution is arranged on the fourth reaction pool, and the inlet of the fifth reaction pool is communicated with the outlet of the fourth reaction pool.

2. The molten salt processing technology based system for resource recovery of municipal solid waste incineration fly ash according to claim 1, characterized in that, The pre-treatment system further comprises a crusher, a grinder, a mixer and a granulating device, the crusher and the grinder are used for crushing and grinding the auxiliary materials, the mixer is used for uniformly mixing the fly ash and the auxiliary materials after grinding, and the granulating device is used for granulating the mixed materials.

3. The molten salt processing technology based system for resource recovery of municipal solid waste incineration fly ash according to claim 1, characterized in that, The feeding system for feeding the prepared material to the molten salt furnace system comprises a first feeding cylinder, a first shaftless screw and a first rotating driving member.

4. The molten salt processing technology-based system for resource recovery of waste incineration fly ash according to claim 3, characterized in that, The feeding system further comprises a hopper for storing the prepared material, and an outlet of the hopper is communicated with the first feeding port and is provided with a discharging valve.

5. The molten salt processing technology based system for resource recovery of municipal solid waste incineration fly ash according to claim 1, wherein, The molten salt furnace comprises a furnace body and a furnace cover covering the furnace body, the furnace cover is provided with a gas collecting port, an observation port and an electrode insertion port, an upper portion of one side of the furnace body is provided with a fly ash feeding port communicated with the first discharging port, a lower portion of the other side of the furnace body is provided with a molten salt overflow port, a lower end of the furnace body is provided with a slag discharging port, and the heating mechanism comprises a heating electrode and an electric control device, the heating electrode is inserted into the furnace body through the electrode insertion port and extends to the molten slag layer, and the electric control device is electrically connected with the heating electrode to realize power supply and temperature control of the heating electrode.

6. The molten salt processing technology based system for resource recovery of municipal solid waste incineration fly ash according to claim 1, wherein, The second rotating driving member comprises a second motor and a second speed reducer, an output end of the second motor is connected with an input end of the second speed reducer, and an output end of the second speed reducer is connected with the second shaftless screw.

7. The molten salt processing technology based system for resource recovery of waste incineration fly ash according to claim 5, characterized in that, The quenching water quenching system comprises a water quenching tank, a slag grab and a heat exchange pipe row, the water quenching tank is arranged below the slag discharging port, and the slag grab and the heat exchange pipe are integrated in the water quenching tank.

8. The molten salt processing technology based system for resource recovery of municipal solid waste incineration fly ash according to claim 1, wherein, The flue gas purification system comprises a quenching tower, a bag-type dust collector, an induced draft fan and a chimney, an inlet of the quenching tower is communicated with the gas collecting port, an outlet of the quenching tower is communicated with an inlet of the bag-type dust collector, an outlet of the bag-type dust collector is communicated with an inlet of the induced draft fan, and an outlet of the induced draft fan is communicated with an inlet of the chimney.

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