Deep reduction dechlorination system for waste incineration fly ash

Abstract

The utility model relates to a deep reduction dechlorination system for waste incineration fly ash. The deep reduction dechlorination system comprises a first-stage rinsing device, a first-stage air through-flow filter press, a second-stage rinsing tank, a second-stage air through-flow filter press, a second-stage filtrate temporary storage tank, a third-stage rinsing tank, a third-stage air through-flow filter press and a third-stage filtrate temporary storage tank. The first-stage rinsing device comprises a pre-dissolving tank, a first pH adjusting tank, a second pH adjusting tank and a rinsing tank, the first pH adjusting tank and the second pH adjusting tank are sequentially connected in series, the first-stage rinsing device further comprises an acid dosing tank and a heavy metal stabilizer dosing tank, the pH value is accurately controlled through two-stage pH adjustment, fly ash soluble substances are deeply removed, and heavy metal is solidified; the size of the second pH adjusting tank is increased, and slurry reaction foam is prevented from overflowing; each stage of air through-flow filter press is used for solid-liquid separation of fly ash slurry, and the water content and soluble salt components of a filter cake are reduced through air purging. According to the utility model, through the cooperation of the three-stage countercurrent rinsing and the air cross-flow filter press, compared with the traditional process, the project construction and operation cost is obviously reduced, and the aim of deeply reducing and dechlorinating the waste incineration fly ash is effectively realized.

Description

deep dechlorination system for fly ash reduction in waste incineration Technical Field

[0001] This utility model belongs to the field of waste incineration fly ash treatment technology, specifically relating to a deep reduction and dechlorination system for waste incineration fly ash. Background Technology

[0002] With the acceleration of urbanization and the continuous increase in the amount of municipal solid waste generated, waste-to-energy incineration has become a widely used, efficient waste treatment method. However, the fly ash produced during waste incineration contains a large amount of harmful substances. Chloride components not only cause severe corrosion to equipment in subsequent resource utilization stages but may also migrate with leachate during landfilling, polluting soil and groundwater. Furthermore, heavy metals (such as lead, cadmium, and mercury) accumulated in fly ash, if directly discharged or disposed of without effective treatment, will pose a significant threat to the ecological environment and human health. Therefore, deep dechlorination treatment of waste incineration fly ash to achieve its harmlessness and resource utilization has become a critical issue that the waste incineration industry urgently needs to address.

[0003] Currently, common technologies for dechlorination of fly ash from waste incineration include water washing and chemical treatment. While traditional water washing dechlorination processes can remove some soluble chlorides, they suffer from low volume reduction efficiency, high water consumption, and high costs for subsequent wastewater treatment. Some systems using single pH adjustment struggle to precisely control pH, leading to insufficient removal of soluble substances from fly ash. In the solid-liquid separation stage, most systems use ordinary filter presses, which cannot effectively reduce the moisture content of the filter cake. This results in the filter cake carrying a large amount of salt solution into the subsequent rinsing process, requiring more rinsing cycles to achieve the dechlorination target, significantly increasing the project's construction and operating costs. Furthermore, existing dechlorination systems lack process continuity in their design, and at the pH adjustment endpoint, violent slurry reactions can easily generate large amounts of foam overflow, disrupting normal production and posing safety hazards.

[0004] Therefore, there is an urgent need in this field to develop a waste incineration fly ash treatment system that can achieve efficient deep dechlorination, precise pH adjustment, reduced operating costs, and ensure process continuity. Summary of the Invention

[0005] Based on the aforementioned shortcomings and deficiencies in the existing technology, one of the objectives of this utility model is to at least solve one or more of the aforementioned problems in the existing technology. In other words, one of the objectives of this utility model is to provide a waste incineration fly ash deep reduction and dechlorination system that meets one or more of the aforementioned requirements.

[0006] To achieve the above-mentioned objectives, this utility model adopts the following technical solution:

[0007] A deep dechlorination system for fly ash from waste incineration includes a primary rinsing device, a primary air-through filter press, a secondary rinsing tank, a secondary air-through filter press, a secondary filtrate storage tank, a tertiary rinsing tank, a tertiary air-through filter press, and a tertiary filtrate storage tank.

[0008] The primary rinsing device includes a pre-dissolving tank, a first pH adjusting tank, a second pH adjusting tank, a primary rinsing tank, an acid dosing tank, and a heavy metal stabilizer dosing tank. The incineration fly ash is fed into the pre-dissolving tank. The top of the pre-dissolving tank is connected to the first pH adjusting tank, the bottom of the first pH adjusting tank is connected to the second pH adjusting tank, and both the bottom and top of the second pH adjusting tank are connected to the primary rinsing tank. The acid dosing tank is connected to both the first and second pH adjusting tanks. The first pH adjusting tank is used for initial pH adjustment, and the second pH adjusting tank is used for fine-tuning the pH. The heavy metal stabilizer dosing tank is connected to the second pH adjusting tank.

[0009] The primary air-flow filter press is used for solid-liquid separation of fly ash slurry output from the primary rinsing tank;

[0010] The secondary rinsing tank is used to rinse the filter cake separated by the primary air-flow filter press. The secondary air-flow filter press is used to perform solid-liquid separation on the slurry rinsed in the secondary rinsing tank. The separated filtrate is temporarily stored in the secondary filtrate storage tank.

[0011] The three-stage rinsing tank is used to rinse the filter cake separated by the two-stage air-flow filter press. The three-stage air-flow filter press is used to perform solid-liquid separation on the slurry rinsed in the three-stage rinsing tank. The separated filtrate is temporarily stored in the three-stage filtrate storage tank.

[0012] As a preferred embodiment, the tertiary filtrate storage tank and the secondary rinsing tank are connected by a pumping pipeline, and the pumping pipeline is a tertiary filtrate pump.

[0013] As a preferred embodiment, the secondary filtrate storage tank and the pre-dissolving tank are connected by a pumping pipeline, and the pumping pipeline is a secondary filtrate pump.

[0014] As a preferred embodiment, the pre-dissolving tank, the first pH adjusting tank, and the second pH adjusting tank are all equipped with aeration devices.

[0015] As a preferred embodiment, the aeration device adopts an aeration disc or aeration pipe, and the aeration device is respectively installed at the bottom of the pre-dissolving tank, the first pH adjustment tank, and the second pH adjustment tank, and the aeration device is connected to an air compressor.

[0016] As a preferred embodiment, the acid dosing tank is connected to the first pH adjustment tank and the second pH adjustment tank via pumping pipelines;

[0017] The pumping pipeline connecting the acid dosing tank and the first pH adjustment tank uses a centrifugal pump or a metering pump.

[0018] The pumping pipeline connecting the acid dosing tank and the second pH adjustment tank uses a metering pump.

[0019] As a preferred embodiment, the volume of the second pH adjustment tank is larger than that of the pre-dissolving tank, the first pH adjustment tank, and the rinsing tank. This is to prevent the slurry from reacting violently and generating a large amount of foam at the pH endpoint.

[0020] As a preferred embodiment, the heavy metal stabilizer dosing tank and the second pH adjustment tank are connected by a pumping pipeline, and the dosing pump used in the pumping pipeline is a centrifugal pump or a metering pump.

[0021] As a preferred embodiment, the primary, secondary, and tertiary air-through filter presses are each connected to a compressed air compressor. After the primary, secondary, and tertiary air-through filter presses have finished pressing, compressed air is introduced to purge the filter cake, reducing its moisture content and soluble salt content.

[0022] As a preferred option, each rinsing tank is connected to its downstream air-flow filter press by a slurry lift pump, which is either a screw sludge pump or a slurry pump.

[0023] Compared with the prior art, the advantages of this utility model are:

[0024] (1) This utility model utilizes a two-stage pH adjustment tank. The first pH adjustment tank is used for initial adjustment, and the second pH adjustment tank is used for fine adjustment, which realizes high-precision control of pH and can deeply remove soluble substances from fly ash.

[0025] (2) This utility model utilizes two-stage pH adjustment tanks connected in series to ensure the continuity of the process, enabling the fly ash treatment process to proceed stably and efficiently, reducing the waste of time and resources caused by process interruption, and greatly improving the dechlorination treatment effect.

[0026] (3) This utility model utilizes the increased volume of the second pH adjustment tank, which has a larger capacity than other rinsing tanks, effectively buffering the violent reaction at the pH endpoint, preventing foam overflow, and ensuring the stability and production safety of the entire process.

[0027] (4) This utility model utilizes an aeration device inside the pH adjustment tank, which can simultaneously perform aeration and stirring, making the pH adjustment of the slurry more uniform under the combined action of aeration and stirring, thereby enhancing the washing effect and effectively preventing solid waste from settling in the pH adjustment tank.

[0028] (5) This utility model utilizes a heavy metal stabilizer dosing tank to efficiently solidify heavy metals in fly ash by adding a heavy metal solidifying agent during the rinsing process, thereby further improving the harmlessness of the fly ash.

[0029] (6) This utility model utilizes an air-flow filter press to blow away the filter cake through airflow, which significantly reduces the moisture content and soluble salt content of the filter cake and greatly reduces the amount of salt solution entering the next stage of the rinsing system.

[0030] (7) This utility model only requires three-stage countercurrent rinsing to meet the requirements of deep dechlorination, which greatly reduces the number of rinsing times compared with traditional processes, thereby significantly reducing the construction and operating costs of the project. Attached Figure Description

[0031] Figure 1 is a process flow diagram of the waste incineration fly ash deep reduction and dechlorination system of Embodiment 1 of this utility model;

[0032] Figure label:

[0033] 0-Fly ash from waste incineration; 1-Pre-dissolving tank; 2-Aeration device for pre-dissolving tank; 3-First pH adjustment tank; 4-Aeration device for first pH adjustment tank; 5-Acid dosing tank; 6-First pH adjustment pump; 7-Second pH adjustment pump; 8-Outlet valve of first pH adjustment tank; 9-Second pH adjustment tank; 10-Aeration device for second pH adjustment tank; 11-Heavy metal stabilizer dosing tank; 12-Heavy metal stabilizer dosing pump; 13-Second pH adjustment tank 14 - Tank outlet valve; 15 - Primary rinsing tank; 16 - Primary slurry lift pump; 17 - Primary air-through filter press; 18 - Secondary rinsing tank; 19 - Secondary slurry lift pump; 20 - Secondary air-through filter press; 21 - Secondary filtrate tank; 22 - Secondary filtrate pump; 23 - Tertiary rinsing tank; 24 - Tertiary slurry lift pump; 25 - Tertiary filtrate tank; 26 - Tertiary filtrate pump; 27 - Air compressor. Detailed Implementation

[0034] To more clearly illustrate the embodiments of this utility model, the specific implementation methods of this utility model will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of this utility model. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0035] Example 1:

[0036] As shown in Figure 1, the waste incineration fly ash deep reduction and dechlorination system of this embodiment includes: a primary rinsing device, a primary air-through filter press 16, a secondary rinsing tank 17, a secondary air-through filter press 19, a secondary filtrate storage tank 20, a tertiary rinsing tank 22, a tertiary air-through filter press 24, and a tertiary filtrate storage tank 25.

[0037] Specifically, the primary rinsing device includes a pre-dissolving tank 1, a first pH adjusting tank 3, a second pH adjusting tank 9, and a primary rinsing tank 14 connected in series. It also includes an acid dosing tank 5 and a heavy metal stabilizer dosing tank 11. Waste incineration fly ash is fed into the pre-dissolving tank 1. The top outlet of the pre-dissolving tank 1 is connected to the top inlet of the first pH adjusting tank 3. The bottom outlet of the first pH adjusting tank 3 is connected to the bottom inlet of the second pH adjusting tank 9 through the first pH adjusting tank outlet valve 8. The bottom and top outlets of the second pH adjusting tank 9 are respectively connected to the bottom and top inlet of the primary rinsing tank 14 through the second pH adjusting tank outlet valve 13. The first pH adjusting tank and the second pH adjusting tank are connected in series. The pH of the fly ash slurry is initially adjusted by the first pH adjusting tank, and the pH of the fly ash slurry is finely adjusted by the second pH adjusting tank, so as to control the pH adjustment accuracy and process continuity.

[0038] Among them, the outlet of the acid dosing tank 5 is divided into two pumping pipelines, which are respectively equipped with a first pH adjusting pump 6 and a second pH adjusting pump 7. The first pH adjusting pump 6 and the second pH adjusting pump 7 serve as the initial pH adjustment dosing pump and the fine pH adjustment dosing pump, respectively. The outlet of the first pH adjusting pump 6 is connected to the acid dosing port of the first pH adjusting tank 3, and the outlet of the second pH adjusting pump 7 is connected to the acid dosing port of the second pH adjusting tank 9.

[0039] The outlet of the aforementioned heavy metal stabilizer dosing tank 11 is equipped with a heavy metal stabilizer dosing pump 12, and the outlet of the heavy metal stabilizer dosing pump 12 is connected to the heavy metal stabilizer dosing port of the second pH adjustment tank 9.

[0040] The bottom of the pre-dissolving tank 1 is provided with a pre-dissolving tank aeration device 2, the bottom of the first pH adjusting tank 3 is provided with a first pH adjusting tank aeration device 4, and the bottom of the rinsing chamber of the second pH adjusting tank 9 is provided with a second pH adjusting tank aeration device 10. The aeration devices adopt aeration discs or aeration pipes, which are evenly distributed. The aeration devices have a gas inlet that connects to the aeration discs or aeration pipes, and the gas inlet is connected to the compressed air outlet of the air compressor 27.

[0041] In this embodiment, the outlet of the primary rinsing tank 14 is connected to the slurry lift pump 15, and the outlet of the slurry lift pump 15 is connected to the inlet of the primary air-flow filter press 16. The filter cake output from the primary air-flow filter press 16 is conveyed to the secondary rinsing tank 17 via a belt conveyor or screw conveyor, and the filtrate is conveyed to the water treatment system.

[0042] In this embodiment, the outlet of the secondary rinsing tank 17 is connected to the slurry lift pump 18, and the outlet of the slurry lift pump 18 is connected to the inlet of the secondary air-flow filter press 19. The filter cake output from the secondary air-flow filter press 19 is conveyed to the tertiary rinsing tank 22 by a belt conveyor or screw conveyor, and the filtrate is conveyed to the secondary filtrate storage tank 20. The outlet of the secondary filtrate storage tank 20 is equipped with a secondary filtrate pump 21, and the outlet of the secondary filtrate pump 21 is connected to the water inlet of the pre-dissolving tank 1.

[0043] In this embodiment, the outlet of the three-stage rinsing tank 22 is connected to the slurry lift pump 23, and the outlet of the slurry lift pump 23 is connected to the inlet of the three-stage air-flow filter press 24. The filter cake output from the three-stage air-flow filter press 24 is conveyed to the temporary storage tank by a belt conveyor or screw conveyor for water washing product treatment. The filtrate is conveyed to the three-stage filtrate temporary storage tank 25. The outlet of the three-stage filtrate temporary storage tank 25 is equipped with a three-stage filtrate pump 26, and the outlet of the three-stage filtrate pump 26 is connected to the two-stage rinsing tank 17.

[0044] In addition, in this embodiment, the first-stage air-through filter press 16, the second-stage air-through filter press 19, and the third-stage air-through filter press 24 are respectively connected to the compressed air compressor 27. After the first-stage, second-stage, and third-stage air-through filter presses have finished pressing, compressed air is introduced to blow through the filter cake to reduce the moisture content and soluble salt content of the filter cake.

[0045] In this embodiment, tap water is used for the three-stage rinsing and water replenishment.

[0046] The waste incineration fly ash deep reduction and dechlorination system in this embodiment achieves deep reduction and dechlorination of waste incineration fly ash through the combination of three-stage countercurrent rinsing and air-through filter press.

[0047] The waste incineration fly ash deep reduction and dechlorination system described in the above embodiment was applied to the treatment of incineration fly ash in a municipal solid waste incineration plant, as detailed below:

[0048] Deep dechlorination was performed on fly ash from a municipal solid waste incineration plant. The solid waste contained 15-20% chloride, 30-60% calcium, and 200-400 mg / kg of heavy metals. The fly ash entered the pre-dissolving tank 1 through the solid waste inlet, and secondary filtrate was added through the wash water inlet. The solid-liquid ratio of solid waste to wash water was 1:2. After mixing with agitation and aeration, the ash overflowed into the first pH adjustment tank 9. Hydrochloric acid was added through the first pH adjustment pump 6 to control the pH of the slurry to around 9. After mixing with agitation and aeration and once the pH stabilized, the ash flowed underflow into the second pH adjustment tank 9. Hydrochloric acid was added through the second pH adjustment pump 7 to control the pH of the slurry to around 9. The slurry pH is around 8. Simultaneously, 2.5-10% heavy metal stabilizer is added to the heavy metal stabilizer dosing tank 11 via the heavy metal stabilizer dosing pump 12. The mixture is stirred and aerated. After the pH stabilizes, the slurry flows to the rinsing tank 14. The pre-dissolving tank 1, the first pH adjusting tank 3, and the second pH adjusting tank 9 are aerated at a controlled pressure of 0.4-0.6 MPa and an aeration rate of 15:1 with a stirring speed of 150 r / min. After rinsing, the slurry is sent to the first-stage air-flow filter press 16 via the lift pump 15 to obtain filtrate and filter cake. The filtrate is discharged into the water treatment system for treatment, and the filter cake enters the subsequent process for two-stage countercurrent rinsing to obtain the fly ash treatment product.

[0049] The product contains less than 1% chloride leaching, less than 1 mg / L heavy metals, and 40-60% fly ash reduction, meeting the requirements for resource utilization.

[0050] The above description is only a detailed explanation of the preferred embodiments and principles of this utility model. For those skilled in the art, there may be changes in the specific implementation methods based on the ideas provided by this utility model, and these changes should also be considered within the protection scope of this utility model.

Claims

1. A deep dechlorination system for fly ash reduction in waste incineration, characterized in that, The system includes a primary rinsing unit, a primary air-through filter press, a secondary rinsing tank, a secondary air-through filter press, a secondary filtrate storage tank, a tertiary rinsing tank, a tertiary air-through filter press, and a tertiary filtrate storage tank. The primary rinsing unit comprises a pre-dissolving tank, a first pH adjusting tank, a second pH adjusting tank, a primary rinsing tank, an acid dosing tank, and a heavy metal stabilizer dosing tank. The incinerator fly ash is fed into the pre-dissolving tank. The top of the pre-dissolving tank is connected to the first pH adjusting tank, the bottom of the first pH adjusting tank is connected to the second pH adjusting tank, and both the bottom and top of the second pH adjusting tank are connected to the primary rinsing tank. The acid dosing tank is connected to both the first and second pH adjusting tanks. The first pH adjusting tank is used for pH adjustment. The system includes an initial pH adjustment tank and a second pH adjustment tank for fine-tuning the pH. A heavy metal stabilizer dosing tank is connected to the second pH adjustment tank. The primary air-flow filter press is used for solid-liquid separation of the fly ash slurry output from the primary rinsing tank. The secondary rinsing tank is used to rinse the filter cake separated by the primary air-flow filter press, and the secondary air-flow filter press is used to perform solid-liquid separation of the slurry rinsed in the secondary rinsing tank. The separated filtrate is temporarily stored in the secondary filtrate storage tank. The tertiary rinsing tank is used to rinse the filter cake separated by the secondary air-flow filter press, and the tertiary air-flow filter press is used to perform solid-liquid separation of the slurry rinsed in the tertiary rinsing tank. The separated filtrate is temporarily stored in the tertiary filtrate storage tank.

2. The waste incineration fly ash deep reduction and dechlorination system according to claim 1, characterized in that, The tertiary filtrate storage tank and the secondary rinsing tank are connected by a pumping pipeline, which uses a tertiary filtrate pump.

3. The waste incineration fly ash deep reduction and dechlorination system according to claim 1, characterized in that, The secondary filtrate storage tank and the pre-dissolving tank are connected by a pumping pipeline, which is a secondary filtrate pump.

4. The waste incineration fly ash deep reduction and dechlorination system according to any one of claims 1-3, characterized in that, The pre-dissolving tank, the first pH adjusting tank, and the second pH adjusting tank are all equipped with aeration devices.

5. The waste incineration fly ash deep reduction and dechlorination system according to claim 4, characterized in that, The aeration device adopts an aeration disc or aeration pipe. The aeration device is respectively installed at the bottom of the pre-dissolving tank, the first pH adjustment tank, and the second pH adjustment tank. The aeration device is connected to an air compressor.

6. The waste incineration fly ash deep reduction and dechlorination system according to any one of claims 1-3, characterized in that, The acid dosing tank is connected to the first pH adjustment tank and the second pH adjustment tank via pumping pipelines; the dosing pump used in the pumping pipeline connecting the acid dosing tank and the first pH adjustment tank is either a centrifugal pump or a metering pump; the dosing pump used in the pumping pipeline connecting the acid dosing tank and the second pH adjustment tank is a metering pump.

7. The waste incineration fly ash deep reduction and dechlorination system according to any one of claims 1-3, characterized in that, The volume of the second pH adjustment tank is larger than the volumes of the pre-dissolving tank, the first pH adjustment tank, and the rinsing tank.

8. The waste incineration fly ash deep reduction and dechlorination system according to any one of claims 1-3, characterized in that, The heavy metal stabilizer dosing tank is connected to the second pH adjustment tank by a pumping pipeline, and the dosing pump used in the pumping pipeline is either a centrifugal pump or a metering pump.

9. The waste incineration fly ash deep reduction and dechlorination system according to any one of claims 1-3, characterized in that, The primary air-through filter press, the secondary air-through filter press, and the tertiary air-through filter press are each connected to a compressed air compressor.

10. The waste incineration fly ash deep reduction and dechlorination system according to any one of claims 1-3, characterized in that, Each rinsing tank is connected to its downstream air-flow filter press by a slurry lift pump, which is either a screw sludge pump or a slurry pump.

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