A treatment system for fly ash washing water in a domestic waste incineration plant

Abstract

The utility model relates to the technical field of wastewater treatment systems, and specifically to a treatment system for fly ash washing water of a domestic waste incineration plant, comprising a fly ash washing water storage tank, the outlet of the fly ash washing water storage tank is connected to the inlet of a softening tank, the outlet of the softening tank is connected to the inlet of a softening membrane, the outlet of the softening membrane is connected to the inlet of an MVR evaporator, the outlet of the MVR evaporator is connected to the inlet of a thickener, the outlet of the thickener is connected to the inlet of a first centrifugal dehydrator, the outlet of the first centrifugal dehydrator is connected to the inlet of a cooling kettle, the outlet of the cooling kettle is connected to the inlet of a second centrifugal dehydrator, and the outlet pipe of the second centrifugal dehydrator is connected to the inlet of a dryer. The utility model solves the problem of environmental pollution caused by direct discharge of fly ash washing water, and realizes the resource utilization of fly ash washing water.

Description

Technical Field

[0001] The utility model relates to the technical field of wastewater treatment systems, in particular to a treatment system for fly ash washing water of a domestic waste incineration plant. Background Art

[0002] Fly ash from the incineration of domestic waste is a powdery substance with a light bulk density and fine particle size, which is mainly collected in flue gas ducts, flue gas purification devices, cyclone separators and bag filters during the process of incineration and power generation of domestic waste. In my country, waste incineration is mainly carried out by mechanical grate furnace incineration plants and circulating fluidized bed incineration plants. The amount of fly ash produced by grate furnaces accounts for about 3% to 5% of the amount of waste incineration, and the chlorine content is 12% to 20%; the amount of fly ash produced by circulating fluidized beds accounts for about 10% to 15% of the amount of waste incineration, and the chlorine content is 3% to 5%. Due to the explosive growth of the waste incineration industry, the future fly ash production will be huge. By the end of 2020, the total amount of waste incineration will reach 591,400 t / d, and the annual fly ash production will be about 10 million t. Fly ash treatment has gradually become an urgent problem to be solved in the treatment of urban domestic waste. The implementation of research on fly ash resource utilization is of great significance to the sustainable development of the ecological environment. At present, the main way to realize fly ash resource utilization is to wash the fly ash with water, that is, to remove the heavy metals and soluble salts contained in the fly ash by water before resource utilization. Fly ash washing will produce a large amount of fly ash washing water.

[0003] Fly ash washing water has high concentrations of heavy metals and high potassium, calcium and sodium salts, which will cause serious pollution to the environment if discharged directly. Utility Model Content

[0004] The utility model aims to provide a system for processing fly ash washing water in a domestic waste incineration plant.

[0005] The utility model provides the following technical solutions:

[0006] The utility model proposes a treatment system for fly ash washing water of a domestic waste incineration plant, comprising a fly ash washing water storage tank, the outlet of the fly ash washing water storage tank is connected to the inlet of a softening tank, the outlet of the softening tank is connected to the inlet of a softening membrane, the outlet of the softening membrane is connected to the inlet of an MVR evaporator, the outlet of the MVR evaporator is connected to the inlet of a thickener, the outlet of the thickener is connected to the inlet of a first centrifugal dehydrator, the water outlet of the first centrifugal dehydrator is connected to the inlet of a cooling kettle, the outlet of the cooling kettle is connected to the inlet of a second centrifugal dehydrator, and the water outlet pipe of the second centrifugal dehydrator is connected to the inlet of a dryer.

[0007] Furthermore, the softening tank includes a reaction tank, a sedimentation tank and an intermediate water tank. The upper end of the reaction tank is connected to the upper end of one side of the sedimentation tank, the upper end of the other side of the sedimentation tank is connected to the upper end of one side of the intermediate water tank, and the lower end of the other side of the intermediate water tank is provided with a softening tank outlet, and the softening tank outlet is connected to the inlet of the softening membrane.

[0008] Furthermore, the condensed water outlet of the MVR evaporator is connected to the inlet of the reused water storage tank, and the condensed water outlet of the dryer is also connected to the inlet of the reused water storage tank.

[0009] Furthermore, the sedimentation outlet of the softening tank is connected to the inlet of the sludge thickening tank, the outlet of the sludge thickening tank is connected to the inlet of the sludge dewatering device, and the outlet of the sludge dewatering device is connected to the inlet of the sludge low-temperature drying device.

[0010] Furthermore, the sludge dewatering device is one of a screw stacking machine and a plate and frame machine.

[0011] Furthermore, a first stirrer for stirring the substances in the reaction tank is provided in the reaction tank.

[0012] Furthermore, the lower end of the sedimentation tank is lower than the lower end of the reaction tank and the lower end of the intermediate water tank, the lower end of the sedimentation tank is in the shape of two funnels, and a sedimentation outlet is opened at the bottom.

[0013] Furthermore, the thickener is provided with a second agitator for stirring the solution in the thickener, and the cooling kettle is provided with a third agitator for stirring the solution in the cooling kettle.

[0014] The utility model provides a treatment system for fly ash washing water of a domestic waste incineration plant, which solves the problem of environmental pollution caused by direct discharge of fly ash washing water. Sodium chloride and potassium chloride are recycled by utilizing the treatment system of the utility model. At the same time, the water quality of condensed water generated by the utility model meets the requirements of fly ash washing and can be recycled for fly ash washing, thus realizing the resource utilization of fly ash washing water. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the connection of the device of the utility model.

[0016] (The arrows indicate the direction of material flow)

[0017] In the figure, 1-fly ash washing water storage tank; 2-softening tank; 21-reaction tank; 211-first agitator; 22-sedimentation tank; 221-inclined tube filler; 2211-baffle; 23-intermediate water tank; 3-softening membrane; 4-MVR evaporator; 5-thickener; 51-second agitator; 6-first centrifugal dehydrator; 7-cooling kettle; 71-third agitator; 8-second centrifugal dehydrator; 9-dryer; 10-sludge thickening tank; 11-sludge dehydration device; 12-sludge low-temperature drying device; 13-recycled water storage tank; 14-mother liquor storage tank; 15-permeate storage tank; 16-softening water pump. DETAILED DESCRIPTION

[0018] The following is combined with Figure 1 The utility model is further described.

[0019] Example 1

[0020] The softening membrane used in Example 1 is: 83G-I8-V external tubular ultrafiltration membrane; the MVR evaporator is: ZM-MVR-300; the thickener is: ZM-CH-1000; the first centrifugal dehydrator is: LW350 horizontal screw centrifuge; the second centrifugal dehydrator is: LW350 horizontal screw centrifuge; the dryer is: FLG-3000 dryer; the screw stacking machine is: KTDL303 screw stacking sludge dehydrator; the plate and frame machine is: XAMY100 / 1000-UB plate and frame filter press; the sludge low-temperature drying device is: KTGH-4800M sludge low-temperature drying machine.

[0021] It is worth mentioning that the above models are only used as examples of this embodiment 1. The models and names of machines from different manufacturers may be different and cannot be understood as limitations on the present utility model.

[0022] In one embodiment of the utility model, a system for treating fly ash washing water of a municipal solid waste incineration plant comprises a fly ash washing water storage tank 1, the outlet of the fly ash washing water storage tank 1 is connected to the inlet of a softening tank 2, the outlet of the softening tank 2 is connected to the inlet of a softening membrane 3, the outlet of the softening membrane 3 is connected to the inlet of an MVR evaporator 4, the outlet of the MVR evaporator 4 is connected to the inlet of a thickener 5, the outlet of the thickener 5 is connected to the inlet of a first centrifugal dehydrator 6, the water outlet of the first centrifugal dehydrator 6 is connected to the inlet of a cooling kettle 7, the outlet of the cooling kettle 7 is connected to the inlet of a second centrifugal dehydrator 8, and the water outlet of the second centrifugal dehydrator 8 is connected to the inlet of a dryer 9.

[0023] In one embodiment of the utility model, the softening tank 2 includes a reaction tank 21, a sedimentation tank 22 and an intermediate water tank 23. The upper end of the reaction tank 21 is connected to the upper end of one side of the sedimentation tank 22, and the upper end of the other side of the sedimentation tank 22 is connected to the upper end of one side of the intermediate water tank 23. A softening tank outlet is provided at the lower end of the other side of the intermediate water tank 23, and the softening tank outlet is connected to the inlet of the softening membrane 3; the fly ash washing water first enters the reaction tank to react with other substances, and then enters the sedimentation tank 22 for sedimentation and filtration, and the supernatant then enters the intermediate water tank 23 from the upper end of the sedimentation tank 22.

[0024] In the above embodiment, the precipitation outlet of the softening membrane 3 is connected to the inlet of the reaction tank 21; the substances that cannot be filtered out from the softening membrane 3 need to be reacted again.

[0025] In the above embodiment, an inclined tube filler 221 is provided in the sedimentation tank 22, and the baffle 2211 of the inclined tube filler is close to the connecting port between the reaction tank 21 and the sedimentation tank 22; it will not affect the solution of the reaction tank 21 entering the sedimentation tank 22, and an inclined tube filler is provided at the connection between the sedimentation tank 22 and the intermediate water tank 23 to efficiently remove the precipitate, thereby ensuring that the solution entering the intermediate water tank 23 is a solution for removing the precipitate.

[0026] In one embodiment of the utility model, the condensed water outlet of the MVR evaporator 4 is connected to the inlet of the reused water storage tank 13, and the condensed water outlet of the dryer 9 is also connected to the inlet of the reused water storage tank 13; the condensed water of the MVR evaporator 4 and the condensed water of the dryer 9 are collected into the reused water storage tank 13 and recycled for washing fly ash.

[0027] In one embodiment of the utility model, the sedimentation outlet of the softening tank 2 is connected to the inlet of the sludge thickening tank 10, the outlet of the sludge thickening tank 10 is connected to the inlet of the sludge dewatering device 11, and the outlet of the sludge dewatering device 11 is connected to the inlet of the sludge low-temperature drying device 12; after the sludge enters the sludge thickening tank 10 for concentration treatment, it enters the sludge dewatering device 11 for dehydration treatment, and then enters the sludge drying device 12 to further remove moisture from the sludge, obtaining sludge with a moisture content of 18 to 22%, which is then transported out for treatment in accordance with national regulations.

[0028] In the above embodiment, the sludge dewatering device 11 is one of a screw stacking machine and a plate and frame machine.

[0029] In one embodiment of the present invention, a first stirrer 211 for stirring the substances in the reaction tank is disposed in the reaction tank 21 .

[0030] In one embodiment of the utility model, the lower end of the sedimentation tank 22 is lower than the lower end of the reaction tank 21 and the lower end of the intermediate water tank 23. The lower end of the sedimentation tank 22 is in the shape of two funnels, and a sedimentation outlet is opened at the bottom; the solution coming in from the reaction tank 21 is first precipitated at the bottom of the sedimentation tank funnel close to the reaction tank 21, and then precipitated at the bottom of another funnel of the sedimentation tank to achieve a better precipitation effect.

[0031] In one embodiment of the present invention, the thickener 5 is provided with a second agitator 51 for agitating the solution in the thickener 5 , and the cooling kettle 7 is provided with a third agitator 71 for agitating the solution in the cooling kettle 7 .

[0032] In one embodiment of the utility model, the water outlet of the second centrifugal dehydrator 8 is connected to the inlet of a mother liquid storage tank 14, and the water outlet of the mother liquid storage tank is connected to the inlet of the dryer 9; the mother liquid storage tank is convenient for storing a certain amount of filtrate after centrifugation of the second centrifugal dehydrator 8.

[0033] In one embodiment of the present invention, the outlet of the softening membrane 3 is connected to the inlet of a permeate storage tank 15 , and the outlet of the permeate storage tank 15 is connected to the inlet of the MVR evaporator 4 ; the permeate storage tank 15 is convenient for storing a certain amount of permeate that passes through the softening membrane 3 .

[0034] In one embodiment of the utility model, the supernatant discharge outlet of the sludge thickening tank 10 is connected to the inlet of the fly ash washing water storage tank 1, and the filtrate discharge outlet of the sludge dewatering device 11 is connected to the inlet of the fly ash washing water storage tank 1; the supernatant of the sludge sedimentation tank 10 and the filtrate of the sludge dewatering device 11 return to the fly ash washing water storage tank 1, and undergo the next round of treatment with new fly ash washing water.

[0035] In one embodiment of the present invention, the condensed water outlet of the sludge drying device 11 is connected to the inlet of the reuse water storage tank 13; the condensed water of the sludge drying device 11 is collected into the reuse water storage tank 13 and recycled for washing fly ash.

[0036] In the above embodiment, the fly ash washing water storage tank 1, the softening tank 2, the softening membrane 3, the MVR evaporator 4, the thickener 5, the first centrifugal dehydrator 6, the cooling kettle 7, the second centrifugal dehydrator 8, the dryer 9, the mother liquor storage tank 14, the permeate storage tank 15, the sludge sedimentation tank 10, the sludge dehydration device 11, the low-temperature drying device 12, and the recycled water storage tank 13 are connected to each other, and pumps can be added to the connecting pipelines to facilitate the transportation of materials.

[0037] In practical applications, the fly ash washing water enters the fly ash washing water storage tank 1 for storage, and is pumped into the reaction tank 21 by a pump. At the same time, alkali (CaO or NaOH) and Na2CO3 are added to the reaction tank 21 in sequence, and the first agitator 211 is used to stir the mixture to make it uniform. The generated CaCO3 and MgCO3 precipitates are removed by the sedimentation tank 22, and the supernatant enters the intermediate water tank 23 and is pumped into the softening membrane 3 by a pump for membrane filtration. The permeate enters the permeate storage tank 15 for storage, and is pumped into the MVR evaporator 4 by a pump for evaporation and concentration to form sodium chloride. The saturated solution enters the thickener 5, and the sodium chloride supersaturated solution continuously precipitates sodium chloride, and then enters the first centrifugal dehydrator 6 for centrifugal dehydration. The sodium chloride is centrifugally dehydrated and recycled. The filtrate after centrifugal dehydration in the first centrifugal dehydrator 6 enters the cooling kettle 7 for cooling and crystallization to continuously precipitate potassium chloride, and enters the second centrifugal dehydrator 8 for centrifugal dehydration. The potassium chloride is centrifugally removed and recycled. The filtrate after centrifugal dehydration in the second centrifugal dehydrator 8 enters the dryer 9, and finally forms miscellaneous salts after drying for external transportation, and is treated in accordance with the treatment method in accordance with national regulations.

[0038] The implementation modes of the present invention are provided for the purpose of illustration and description. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A system for treating fly ash washing water from a domestic waste incineration plant, characterized in that: It comprises a fly ash washing water storage tank, the outlet of the fly ash washing water storage tank is connected to the inlet of a softening tank, the outlet of the softening tank is connected to the inlet of a softening membrane, the outlet of the softening membrane is connected to the inlet of an MVR evaporator, the outlet of the MVR evaporator is connected to the inlet of a thickener, the outlet of the thickener is connected to the inlet of a first centrifugal dehydrator, the water outlet of the first centrifugal dehydrator is connected to the inlet of a cooling kettle, the outlet of the cooling kettle is connected to the inlet of a second centrifugal dehydrator, and the water outlet pipe of the second centrifugal dehydrator is connected to the inlet of a dryer.

2. A system for treating fly ash washing water from a domestic waste incineration plant according to claim 1, characterized in that: The softening tank includes a reaction tank, a sedimentation tank and an intermediate water tank. The upper end of the reaction tank is connected to the upper end of one side of the sedimentation tank, the upper end of the other side of the sedimentation tank is connected to the upper end of one side of the intermediate water tank, and the lower end of the other side of the intermediate water tank is provided with a softening tank outlet, and the softening tank outlet is connected to the inlet of the softening membrane.

3. A system for treating fly ash washing water from a domestic waste incineration plant according to claim 1, characterized in that: The condensed water outlet of the MVR evaporator is connected to the inlet of the reused water storage tank, and the condensed water outlet of the dryer is also connected to the inlet of the reused water storage tank.

4. A system for treating fly ash washing water from a domestic waste incineration plant according to claim 1, characterized in that: The sedimentation outlet of the softening tank is connected to the inlet of the sludge thickening tank, the outlet of the sludge thickening tank is connected to the inlet of the sludge dewatering device, and the outlet of the sludge dewatering device is connected to the inlet of the sludge low-temperature drying device.

5. A system for treating fly ash washing water from a domestic waste incineration plant according to claim 4, characterized in that: The sludge dewatering device is one of a screw stacking machine and a plate and frame machine.

6. A system for treating fly ash washing water from a domestic waste incineration plant according to claim 2, characterized in that: The reaction tank is provided with a first stirrer for stirring the substances in the reaction tank.

7. A system for treating fly ash washing water from a domestic waste incineration plant according to claim 2, characterized in that: The lower end of the sedimentation tank is lower than the lower end of the reaction tank and the lower end of the intermediate water tank. The lower end of the sedimentation tank is in the shape of two funnels, and a sedimentation outlet is opened at the bottom.

8. The system for treating fly ash washing water of a domestic waste incineration plant according to claim 1, characterized in that: The thickener is provided with a second agitator for agitating the solution in the thickener, and the cooling kettle is provided with a third agitator for agitating the solution in the cooling kettle.

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