Waste incineration fly ash washing water resource utilization and salt separation treatment device

Abstract

The utility model discloses a waste incineration fly ash washing water recycling salt separation treatment device which is characterized in that a fly ash washing water output pipe is connected with a circulating pipe of a forced crystallization system, a forced crystallization crystal slurry outlet is connected with an MVR (mechanical vapor recompression) thickening tank, a bottom outlet of the MVR thickening tank is connected with an MVR centrifugal machine, and a solid phase of the MVR centrifugal machine is connected with a potassium sodium carnallite articulated chute; a liquid phase is connected with an MVR mother liquor tank, a bottom outlet of the MVR mother liquor tank is connected with a flash evaporation crystallization system, a crystal slurry outlet of flash evaporation crystallization is connected with a flash evaporation thickening tank, a bottom outlet of the flash evaporation thickening tank is connected with a flash evaporation centrifugal machine, a solid phase of the flash evaporation centrifugal machine is connected with a potassium sodium mixed salt articulated chute, and the liquid phase is connected with an inlet of the flash evaporation mother liquor tank. An outlet of the flash evaporation mother liquor tank is connected with the flash evaporation thickening tank; an overflow port of the flash evaporation thickening tank is connected with the flash evaporation precipitation tank, and a precipitation clear liquid outlet is connected with a flash evaporation mother liquid discharge pipe. According to the device, fine grains can be effectively eliminated, calcium in the fly ash can be fully recycled, and high-value utilization of the waste incineration fly ash is achieved.

Description

Technical Field

[0001] The utility model relates to a garbage incineration fly ash treatment device, in particular to a salt separation treatment device for the resource utilization of washed water of garbage incineration fly ash, and belongs to the technical field of salt separation treatment equipment. Background Art

[0002] The garbage incineration technology has become the main disposal method of urban domestic garbage in China by virtue of reduction, harmlessness and resource utilization, and the incineration treatment ratio increases year by year. However, the incineration of domestic garbage will produce garbage incineration fly ash (referred to as fly ash) accounting for 2% - 15% of the total amount of the original garbage. The fly ash has complex components, including persistent organic pollutants such as dioxins and furans, and heavy metal salts, etc. If not properly disposed, it will pose a serious threat to the ecological environment and human health. On the other hand, the soluble substances in the fly ash contain rich potassium salt and sodium salt resources. By means of the technologies of washing and dechlorination and crystallization for potassium salt extraction, the potassium and sodium salt resources in the fly ash can be extracted. For the washing wastewater with a high chloride salt concentration, further improve the optimization treatment of the key process MVR crystallization system in the fly ash washing pretreatment production line, integrate and draw on the advantages of the same-performance equipment in other industries, carry out the research and development and promotion of the fly ash resource disposal technology application of the "fly ash washing pretreatment + high-temperature treatment" series, promote the transformation of research results, make the technology more perfect, provide safe, environmental protection, stable, efficient and controllable technical support for the industrial transformation of the co-disposal of fly ash in cement kilns, and explore and provide a safe and feasible practical route.

[0003] Generally speaking, the characteristics of domestic garbage incineration fly ash are complex and the harm is serious. Its treatment technical route must be overall planned, systematically designed, carefully selected, and environmental risks controlled. The treatment and utilization technology of fly ash should be considered from two aspects of resource utilization and environmental impact. It is necessary to consider the feasibility of the resource utilization of incineration fly ash, find the best balance point between economic cost and environmental protection, and make the environmental characteristics of the incineration fly ash treatment products meet the specified standards. In terms of environmental impact, not only the effective fixation of heavy metals should be improved, but also the dioxins in the fly ash should be destroyed or removed. The practice of the fly ash washing equipment for the co-disposal of fly ash in cement kilns provides effective experience for the disposal of domestic garbage incineration fly ash and is a commonly used fly ash disposal method at the present stage.

[0004] The Chinese invention patent application with the publication number of CN 109095531A discloses a resource treatment process for the washed water of garbage fly ash. Through steps such as preheating, evaporation concentration, forced circulation, salt crystallization, etc., the separation of sodium chloride and potassium chloride in the washed water of garbage fly ash is realized. Its system utilizes the MVR technology, reduces the dependence on boiler equipment, and reduces the operation cost. Although this technical solution reduces the system energy consumption by using the MVR technology, it does not consider the characteristic of the high boiling point temperature of the calcium chloride solution in the actual production process and cannot ensure the heat exchange of the recombination.

[0005] The utility model patent with the application number CN 213221026U discloses a device for improving the purity of fly ash washing water evaporation solution. By means of a cyclone separator, the amount of circulating liquid in the system is reduced, and the equipment investment is lowered. However, in the actual industrial production process, the fly ash washing water solution contains calcium chloride, and its solution has high corrosivity, high viscosity, and serious entrainment of secondary steam. Therefore, in the actual operation process, the secondary gas generated during the evaporation of fly ash washing water needs to be properly treated to avoid the excessive conductivity of the condensed water after its cooling, so as to achieve the zero-emission goal. In addition, during the dechlorination process of fly ash washing water, the potassium and sodium contents in the calcium chloride solution are still relatively high, which affects the quality of subsequent building materials products. Content of the utility model

[0006] The purpose of this part is to outline some aspects of the embodiments of the present utility model and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, as well as in the abstract of the specification and the name of the utility model of this application, but such simplifications or omissions cannot be used to limit the scope of the present utility model.

[0007] In view of the above and / or problems existing in the prior art, the present utility model is proposed.

[0008] The purpose of the present utility model is to overcome the problems existing in the prior art and provide a device for separating salts and recycling resources from fly ash washing water in garbage incineration, which can effectively eliminate fine crystals, fully recover calcium in fly ash, reduce waste during the fly ash treatment process, and realize the high-value utilization of garbage incineration fly ash.

[0009] To solve the above technical problems, a fractional salt treatment device for resource utilization of incineration fly ash washing water in the utility model includes a fly ash washing water output pipe. The outlet of the fly ash washing water output pipe is connected to the outlet circulation pipe of the MVR forced evaporator. The outlet of the outlet circulation pipe of the MVR forced evaporator is connected to the middle feed inlet of the MVR forced crystallizer. The lower circulation outlet of the MVR forced crystallizer is connected to the inlet of the MVR forced circulation pump. The outlet of the MVR forced circulation pump is connected to the lower inlet of the MVR forced evaporator. The salt leg slurry outlet of the MVR forced crystallizer is connected to the inlet of the MVR slurry pump. The outlet of the MVR slurry pump is connected to the inlet of the MVR thickening tank. The bottom outlet of the MVR thickening tank is connected to the inlet of the MVR centrifuge. The solid phase outlet of the MVR centrifuge is connected with a potassium-sodium mixed salt chute pipe. The liquid phase outlet of the MVR centrifuge and the overflow outlet of the MVR thickening tank are respectively connected to the inlet of the MVR mother liquor tank. The bottom outlet of the MVR mother liquor tank is connected to the outlet pipe of the flash evaporation circulation pump through the MVR mother liquor pump. The upper outlet of the outlet pipe of the flash evaporation circulation pump is connected to the middle inlet of the flash evaporation crystallizer. The lower circulation outlet of the flash evaporation crystallizer is connected to the inlet of the flash evaporation circulation pump. The salt leg slurry outlet of the flash evaporation crystallizer is connected to the inlet of the flash evaporation thickening tank through the flash evaporation slurry pump. The bottom outlet of the flash evaporation thickening tank is connected to the inlet of the flash evaporation centrifuge. The solid phase outlet of the flash evaporation centrifuge is connected with a potassium-sodium mixed salt chute pipe. The liquid phase outlet of the flash evaporation centrifuge is connected to the inlet of the flash evaporation mother liquor tank. The outlet of the flash evaporation mother liquor tank is connected to the inlet of the flash evaporation thickening tank through the flash evaporation mother liquor circulation pump. The overflow outlet of the flash evaporation thickening tank is connected to the inlet of the flash evaporation sedimentation tank. The clear liquid outlet of the flash evaporation sedimentation tank is connected to the flash evaporation mother liquor discharge pipe through the flash evaporation mother liquor discharge pump.

[0010] As an improvement of the utility model, the outlet pipe of the MVR slurry pump is also connected to the reflux port of the MVR forced crystallizer.

[0011] As a further improvement of the utility model, the top secondary steam outlet of the MVR forced crystallizer is connected to the upper inlet of the MVR scrubbing tower. The middle steam outlet of the MVR scrubbing tower is connected to the inlet of the first-stage steam compressor. The outlet of the first-stage steam compressor is connected to the inlet of the second-stage steam compressor. The outlet of the second-stage steam compressor is connected to the lower inlet of the gas-liquid separator. The upper outlet of the gas-liquid separator is connected to the shell-side steam inlet of the MVR forced evaporator through a compressed steam pipe.

[0012] Compared with the prior art, the utility model has achieved the following beneficial effects: 1. By means of the series connection of two steam compressors, the device provides a large temperature rise in the boiling point of the material, increases the evaporation heat transfer temperature difference, and improves the evaporation efficiency; the first gas is compressed multiple times, and the density of the gas will increase and the volume will decrease after each compression, increasing the gas delivery volume, thereby reducing the resistance during the gas transportation process and having a higher transportation efficiency; each time the second compressor compresses, the pressure of the gas will continuously increase, and the compression efficiency is higher; the double series connection can provide a temperature rise of up to 26°C and an evaporation heat transfer temperature difference of ≥10°C. The loss of the heat transfer temperature difference is small, providing the stability during the normal operation of the evaporation system and ensuring the evaporation capacity of the system.

[0013] 2. By combining the MVR system with the flash evaporation system, the device reduces the potassium and sodium ion content in calcium chloride. Utilizing the high vacuum degree characteristic of the flash evaporation system, the temperature of the material decreases after gasification and flash evaporation, further precipitating potassium and sodium crystal salts, and by increasing the residence time of the material, the particle size of the crystals is effectively improved. The MVR concentrated solution is further cooled by flash evaporation to reduce the temperature of the calcium chloride solution and simultaneously reduce the potassium and sodium content in the calcium chloride solution, ensuring the potassium and sodium content in the subsequent externally discharged calcium chloride solution.

[0014] 3. By designing a secondary precipitation method, the device eliminates fine crystals, and the discharged mother liquor adopts the method of secondary precipitation of the supernatant liquid to ensure a low content of potassium and sodium crystals in the externally discharged calcium chloride solution. The flash evaporation thickening tank and the flash evaporation precipitation tank are added, thereby reducing the loss rate of fine crystals in the flash evaporation mother liquor and simultaneously reducing the potassium and sodium content in the calcium chloride solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following will briefly introduce the drawings required for use in the description of the embodiments. Obviously, the following drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. The drawings are only for reference and explanation, and are not used to limit the present utility model. Among them:

[0016] Figure 1 is the flow chart of the device for separating salts from the recycled water of waste incineration fly ash washing of the present utility model;

[0017] In the figure: 1. MVR forced crystallizer; 2. MVR forced evaporator; 3. MVR thickening tank; 4. MVR centrifuge; 4a. Potassium and sodium miscellaneous salt chute; 5. MVR mother liquor tank; 6. Flash evaporation crystallizer; 7. Flash evaporation thickening tank; 8. Flash evaporation precipitation tank; 9. Flash evaporation centrifuge; 9a. Potassium and sodium mixed salt chute; 10. Flash evaporation mother liquor tank; 11. MVR gas scrubber; 12. First-stage steam compressor; 13. Second-stage steam compressor; 14. Gas-liquid separator;

[0018] G1. Fly ash washing water output pipe; G2. MVR mother liquor discharge pipe; G3. Flash evaporation mother liquor discharge pipe; G4. Compressed steam pipe;

[0019] B1. MVR forced circulation pump; B2. MVR crystal slurry pump; B3. MVR mother liquor pump; B4. Flash evaporation circulation pump; B5. Flash evaporation crystal slurry pump; B6. Flash evaporation mother liquor circulation pump; B7. Flash evaporation mother liquor discharge pump. Detailed implementation manners

[0020] In the following description of the present utility model, the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating that the device must have a specific orientation.

[0021] In order to make the technical means, creative features, achieved purposes and functions realized by the present utility model easy to understand, the present utility model will be further described below with reference to specific drawings. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present utility model belongs. The terms used in the description of the present utility model herein are only for the purpose of describing specific embodiments, and are not intended to limit the present utility model.

[0023] As Figure 1 shown, the device for separating salts from the resource utilization of fly ash washing water of the present utility model includes an MVR forced crystallization system and a flash evaporation crystallization system. The MVR forced crystallization system includes an MVR forced crystallizer 1, an MVR forced evaporator 2, an MVR forced circulation pump B1, an MVR thickening tank 3, an MVR centrifuge 4, an MVR mother liquor tank 5 and various pipelines. The flash evaporation crystallization system includes a flash evaporation crystallizer 6, a flash evaporation circulation pump B4, a flash evaporation crystal slurry pump B5, a flash evaporation thickening tank 7, a flash evaporation precipitation tank 8, a flash evaporation centrifuge 9, a flash evaporation mother liquor tank 10, a flash evaporation mother liquor circulation pump B6 and a flash evaporation mother liquor discharge pump B7.

[0024] The outlet of the fly ash washing water output pipe G1 is connected to the outlet circulation pipe of the MVR forced evaporator 2, the outlet of the outlet circulation pipe of the MVR forced evaporator 2 is connected to the middle feed inlet of the MVR forced crystallizer 1, the lower circulation outlet of the MVR forced crystallizer 1 is connected to the inlet of the MVR forced circulation pump B1, the outlet of the MVR forced circulation pump B1 is connected to the lower inlet of the MVR forced evaporator 2, the salt leg crystal slurry outlet of the MVR forced crystallizer 1 is connected to the inlet of the MVR crystal slurry pump B2, and the outlet of the MVR crystal slurry pump B2 is connected to the inlet of the MVR thickening tank 3 and the return port of the MVR forced crystallizer 1.

[0025] The bottom outlet of the MVR thickener 3 is connected to the inlet of the MVR centrifuge 4, and a potassium-sodium mixed salt chute is connected to the solid phase outlet of the MVR centrifuge 4; the liquid phase outlet of the MVR centrifuge 4 and the overflow outlet of the MVR thickener 3 are respectively connected to the inlet of the MVR mother liquor tank 5. The bottom outlet of the MVR mother liquor tank 5 is connected to the outlet pipeline of the flash evaporation circulation pump B4 through the MVR mother liquor pump B3. The upper outlet of the outlet pipeline of the flash evaporation circulation pump B4 is connected to the middle inlet of the flash evaporation crystallizer 6. The lower circulation outlet of the flash evaporation crystallizer 6 is connected to the inlet of the flash evaporation circulation pump B4; the salt leg slurry outlet of the flash evaporation crystallizer 6 is connected to the inlet of the flash evaporation thickener 7 through the flash evaporation slurry pump B5. The bottom outlet of the flash evaporation thickener 7 is connected to the inlet of the flash evaporation centrifuge 9. A potassium-sodium mixed salt chute is connected to the solid phase outlet of the flash evaporation centrifuge 9. The liquid phase outlet of the flash evaporation centrifuge 9 is connected to the inlet of the flash evaporation mother liquor tank 10. The outlet of the flash evaporation mother liquor tank 10 is connected to the inlet of the flash evaporation thickener 7 through the flash evaporation mother liquor circulation pump B6; the overflow outlet of the flash evaporation thickener 7 is connected to the inlet of the flash evaporation sedimentation tank 8. The clear liquid outlet of the flash evaporation sedimentation tank 8 is connected to the flash evaporation mother liquor discharge pipe G3 through the flash evaporation mother liquor discharge pump B7.

[0026] The fly ash washing water from waste incineration is a calcium chloride solution containing potassium and sodium. The calcium chloride solution with a low concentration of 15.54%wt is pumped into the material circulation pipeline of the MVR forced crystallizer 1 through the fly ash washing water output pipe G1 by an off-site water pump. The material is evaporated and concentrated in the MVR forced crystallizer 1 after heat exchange with steam under the action of the MVR forced circulation pump B1 through the MVR forced evaporator 2. After the solution is heated to about 87 °C through heat exchange in the heat exchanger pipeline, it enters the MVR forced crystallizer 1 for flashing. As the concentration increases, sodium chloride and potassium chloride first reach the saturation point and gradually crystallize out. The slurry in the MVR forced crystallizer 1 is transported to the MVR thickener 3 through the MVR slurry pump B2. The slurry settles in the MVR thickener 3, and then the bottom slurry undergoes solid-liquid separation by the MVR centrifuge 4. The separated solid is potassium-sodium mixed salt, which reaches the ground through the potassium-sodium mixed salt chute 4a.

[0027] The separated liquid is a high-temperature calcium chloride solution with a concentration of 30%wt, which enters the MVR mother liquor tank 5 and is then pumped into the subsequent flash evaporation crystallization system through the MVR mother liquor pump B3.

[0028] The top secondary steam outlet of the MVR forced crystallizer is connected to the upper inlet of the MVR scrubber 11. The middle steam outlet of the MVR scrubber 11 is connected to the inlet of the first-stage steam compressor 12. The outlet of the first-stage steam compressor 12 is connected to the inlet of the second-stage steam compressor 13. The outlet of the second-stage steam compressor 13 is connected to the lower inlet of the gas-liquid separator 14. The upper outlet of the gas-liquid separator 14 is connected to the shell-side steam inlet of the MVR forced evaporator through the compressed steam pipe G4.

[0029] The secondary steam at 85°C generated during the evaporation process in the MVR forced crystallizer 1 enters the MVR scrubbing tower 11 for washing and purification to reduce the possibility of entraining materials with gas. Subsequently, the purified secondary steam enters the first-stage steam compressor 12 to be heated and pressurized to 100°C. The outlet gas of the first-stage steam compressor 12 enters the second-stage steam compressor 13 for further pressurization and heating to 111°C. The outlet gas of the second-stage steam compressor 13 serves as the heat source for the MVR forced evaporator 2. The steam enters the shell side of the MVR forced evaporator 2 for heat exchange and condensation, and the condensed water is discharged externally.

[0030] The flash crystallization system includes a flash crystallizer 6, a flash circulation pump B4, a flash crystal slurry pump B5, a flash thickener 7, a flash sedimentation tank 8, a flash centrifuge 9, a flash mother liquor tank 10, a flash mother liquor circulation pump B6, and a flash mother liquor discharge pump B7. The mother liquor in the MVR mother liquor tank 5 in the MVR forced crystallization system is sent out by the MVR mother liquor pump B3 and pumped into the flash system through the MVR mother liquor discharge pipe G2. Due to the relatively high vacuum degree in the flash system, the high-temperature material enters from the outlet of the flash circulation pump B4. Using the liquid level pressure difference to prevent the high-temperature material from boiling violently, under the drive of the flash circulation pump B4, the material vaporizes and flashes, and the temperature drops to 42°C, further precipitating potassium and sodium crystal salts. After the solid-liquid ratio in the salt leg reaches 10 - 20, it is transported to the flash thickener 7 by the flash crystal slurry pump B5. The bottom discharge of the flash thickener 7 enters the flash centrifuge 9 for solid-liquid separation. The separated potassium and sodium mixed salt products are discharged through the potassium and sodium mixed salt chute 9a and then packed into bags.

[0031] The separated mother liquor enters the flash mother liquor tank 10. The mother liquor is pumped back to the flash thickener 7 by the flash mother liquor circulation pump B6 to form a cycle. The overflow of the flash thickener 7 enters the flash sedimentation tank 8. At this time, the mother liquor overflowing into the flash sedimentation tank 8 is the supernatant with less potassium and sodium, further reducing the fine crystals entrained in the sedimentation mother liquor. Subsequently, the mother liquor is discharged by the flash mother liquor discharge pump B7 and transported to the next process section.

[0032] This device can reduce the content of potassium and sodium in the calcium chloride solution, wash and remove chlorine in the waste incineration fly ash, and become a qualified building material product.

[0033] The above are only the preferred and feasible embodiments of the present utility model, which illustrate and describe the basic principles, main features and advantages of the present utility model. It is not intended to limit the patent protection scope of the present utility model thereby. Those skilled in the art should understand that the present utility model is not restricted by the above embodiments. Except for the above embodiments, without departing from the spirit and scope of the present utility model, the present utility model may have other implementation manners. The present utility model will also have various changes and improvements. Any technical solutions formed by equivalent substitution or equivalent transformation shall fall within the protection scope required by the present utility model. The protection scope required by the present utility model is defined by the appended claims and their equivalents. The technical features not described in the present utility model can be realized by or adopted from the prior art, and will not be elaborated herein.

Claims

1. A waste incineration fly ash washing water resource utilization and salt separation treatment device, comprising a fly ash washing water output pipe, characterized in that: The outlet of the fly ash washing water output pipe is connected to the outlet circulation pipe of the MVR forced evaporator, the outlet of the outlet circulation pipe of the MVR forced evaporator is connected to the middle feed port of the MVR forced crystallizer, the lower circulation outlet of the MVR forced crystallizer is connected to the inlet of the MVR forced circulation pump, the outlet of the MVR forced circulation pump is connected to the lower inlet of the MVR forced evaporator, the salt leg slurry outlet of the MVR forced crystallizer is connected to the inlet of the MVR slurry pump, the outlet of the MVR slurry pump is connected to the inlet of the MVR thickening tank, the bottom outlet of the MVR thickening tank is connected to the inlet of the MVR centrifuge, the solid phase outlet of the MVR centrifuge is connected to the potassium and sodium salt chute; the liquid phase outlet of the MVR centrifuge and the overflow port of the MVR thickening tank are respectively connected to the inlet of the MVR mother liquor tank, and the MVR mother liquor The bottom outlet of the tank is connected to the outlet pipe of the flash circulation pump through the MVR mother liquor pump, the upper end outlet of the outlet pipe of the flash circulation pump is connected to the middle inlet of the flash crystallizer, and the lower circulation outlet of the flash crystallizer is connected to the inlet of the flash circulation pump; the salt leg slurry outlet of the flash crystallizer is connected to the inlet of the flash thickening tank through the flash slurry pump, the bottom outlet of the flash thickening tank is connected to the inlet of the flash centrifuge, the solid phase outlet of the flash centrifuge is connected to the potassium-sodium mixed salt chute, the liquid phase outlet of the flash centrifuge is connected to the inlet of the flash mother liquor tank, and the outlet of the flash mother liquor tank is connected to the inlet of the flash thickening tank through the flash mother liquor circulation pump; the overflow port of the flash thickening tank is connected to the inlet of the flash precipitation tank, and the clear liquid outlet of the flash precipitation tank is connected to the flash mother liquor effluent pipe through the flash mother liquor effluent pump.

2. The device for recycling and salt separation of waste incineration fly ash washing water according to claim 1 is characterized in that: The outlet pipe of the MVR slurry pump is also connected to the reflux port of the MVR forced crystallizer.

3. The device for recycling and salt separation of waste incineration fly ash washing water according to claim 1 or 2, characterized in that: The top secondary steam outlet of the MVR forced crystallizer is connected to the upper inlet of the MVR scrubber, the middle steam outlet of the MVR scrubber is connected to the inlet of the first-stage steam compressor, the outlet of the first-stage steam compressor is connected to the inlet of the second-stage steam compressor, the outlet of the second-stage steam compressor is connected to the lower inlet of the gas-liquid separator, and the upper outlet of the gas-liquid separator is connected to the shell-side steam inlet of the MVR forced evaporator through a compressed steam pipe.

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