A furnace ash acidic water treatment system

Abstract

This utility model discloses a furnace ash acidic water treatment system, including a furnace ash conveying mechanism, a treatment mechanism connected downstream of the furnace ash conveying mechanism, and an intelligent control system. The treatment mechanism is also connected to an acidic water source for the synergistic treatment of acidic water and furnace ash. The intelligent control system is connected to the furnace ash conveying mechanism and the treatment mechanism to form a control and regulation loop that collects, stores, calculates, and regulates the output. This utility model combines the treatment of furnace ash and acidic water in an acrylonitrile co-processing unit, achieving "waste-to-waste" treatment, reduction of waste, and resource utilization, reducing the consumption of alkaline solutions for acidic water, and improving the economic efficiency of the system. Simultaneously, the intelligent control system enables automated operation of the system, reduces the frequency of manual operation, and solves the problems of over-adjustment, frequent adjustment, and instability that easily occur in traditional PID logic control, achieving rapid, stable, and precise control of the system.

Description

Technical Field

[0001] This utility model relates to the field of solid waste treatment and environmental protection technology, specifically to a furnace ash acidic water treatment system. Background Technology

[0002] The main method for acrylonitrile production in China is the propylene oxidation process, which produces acrylonitrile with high-purity acetonitrile and hydrogen cyanide as byproducts. High-purity acetonitrile can be sold directly, while high-purity hydrogen cyanide can be used in the acetone cyanohydrin process to produce MMA, and subsequently PMMA, improving the overall economic efficiency of the plant. Acrylonitrile plants generate large amounts of nitrile-containing wastewater, and the production of acrylonitrile and MMA also produces large amounts of sulfur-containing wastewater. Currently, thermal incineration and waste acid regeneration processes are widely used to treat these two types of wastewater separately.

[0003] Large quantities of furnace ash are generated in acrylonitrile wastewater treatment plants. The main components are sodium carbonate and sodium bicarbonate, with small amounts of heavy metals such as Fe, Ni, Bi, Cr, Cu, Mg, Hg, Zn, and Pb, as well as unburned carbonaceous compounds. Furthermore, due to differences in the quenching processes of upstream acrylonitrile plants, the composition of the wastewater varies, and some acrylonitrile plant furnace ash also contains a certain amount of nitrogen compounds and ammonium sulfate. This furnace ash falls under the category of hazardous waste as defined in the "National Hazardous Waste List (2021)" and cannot meet the landfill requirements of the "Standard for Pollution Control of Hazardous Waste Landfill" in GB18598-2019. Therefore, many chemical plants have to store large quantities of furnace ash in warehouses for extended periods, wasting land resources and posing significant safety risks. The treatment of acrylonitrile plant furnace ash has become an urgent problem to be solved in this industry.

[0004] The waste acid regeneration unit treats waste ammonium sulfate from the acrylonitrile unit and sulfur-containing wastewater from the MMA unit. This process generates a large amount of acidic water, primarily composed of 0.5–3% sulfuric acid, small amounts of ammonia nitrogen, and heavy metal pollutants. Industrially, this water is typically treated with alkali before being sent to a wastewater treatment plant, but this process consumes a significant amount of alkali. Summary of the Invention

[0005] To address the problems of excessive heavy metal content in acrylonitrile plant ash leading to excessive toxicity in landfill leaching and treatment difficulties, and the high alkali consumption (e.g., 8-12 kg of alkali per ton of water treated) in acidic water treatment, this invention aims to provide a furnace ash and acidic water treatment system. This system jointly treats furnace ash and acidic water from acrylonitrile combined plant, achieving "waste-to-waste" treatment, reducing the volume of waste and promoting resource utilization within the plant. This reduces alkali consumption in acidic water treatment and improves the system's economic efficiency. Simultaneously, an intelligent control system is employed, enabling automated operation, reducing the frequency of manual operation, and resolving issues such as over-adjustment, frequent adjustments, and instability common in traditional PID logic control. This results in rapid, stable, and precise control of the system.

[0006] The purpose of this utility model is to provide a treatment system for acidic wastewater from furnace ash, and the technical solution adopted is as follows:

[0007] A furnace ash acidic water treatment system includes a furnace ash conveying mechanism, a treatment mechanism connected downstream of the furnace ash conveying mechanism, and an intelligent control system; the treatment mechanism is also connected to an acidic water source for co-treatment of acidic water and furnace ash; the intelligent control system is connected to the furnace ash conveying mechanism and the treatment mechanism to form a control and regulation loop that collects, stores, calculates, and regulates the output.

[0008] In some embodiments, the ash conveying mechanism includes a dust collector ash hopper, a first automatic unloader, an ash storage hopper, and a second automatic unloader connected in sequence, and is connected to the processing mechanism via an ash conveying pipeline.

[0009] In some embodiments, the treatment apparatus includes a furnace ash dissolving tank, an oxidation tank, a heavy metal removal tank, a flocculation sedimentation tank, a settling tank, a fine filter, a denitrification tank, and a regulating tank, which are connected sequentially along the slurry flow direction; it also includes sludge drying equipment for receiving sludge from each unit; wherein, the furnace ash dissolving tank is connected downstream of the furnace ash conveying pipeline; the furnace ash dissolving tank is equipped with an acidic water supply pipe and a first alkali solution supply pipe, and the pH in the furnace ash dissolving tank is maintained at 2-4 by controlling the ratio of acidic water and furnace ash entering the furnace ash dissolving tank.

[0010] In some embodiments, the oxidation tank is equipped with an oxidant supply pipe for removing COD from furnace ash and acidic water; the heavy metal removal tank is equipped with a second alkali supply pipe and a first reagent supply pipe for adjusting the pH of the liquid in the heavy metal removal tank, while simultaneously precipitating and removing heavy metals and forming suspended solids; the flocculation sedimentation tank is connected to a second reagent feed pipe for further particle aggregation; the dust-laden liquid in the oxidation tank, heavy metal removal tank, and flocculation sedimentation tank is mixed through pipelines and then sent to a settling tank;

[0011] The fine filter is used to filter and obtain a clear solution; the denitrification tank is equipped with a denitrification agent supply pipe to remove ammonia nitrogen present in the feed liquid; the sludge drying equipment is connected to the bottom of the settling tank and the bottom of the fine filter through pipes respectively; the regulating tank is equipped with a regulating agent supply pipe to adjust the acidity and alkalinity of the outlet purified liquid.

[0012] In some embodiments, the ash dissolution box, oxidation box, heavy metal removal box, and denitrification box are all equipped with gas phase pipelines, and the gas phase is collected through the pipelines and enters the tail gas filtration equipment to the tail gas treatment system.

[0013] In some embodiments, the intelligent control system includes a data acquisition and storage module, a data calculation and processing module, an intelligent control module, and a historical data storage module;

[0014] The input end of the data acquisition and storage module is connected to the ash conveying mechanism and the processing mechanism, and is used to collect process parameters and parameter settings for data processing and storage.

[0015] The input end of the data calculation and processing module is connected to the output end of the data acquisition and storage module, so that the process parameters and parameter settings are processed and stored in the data acquisition and storage module and then transmitted to the data calculation and processing module for data calculation and processing.

[0016] The input end of the historical data storage module is connected to the output end of the data acquisition and storage module, and is used to store historical data within a certain period of time;

[0017] The input terminal of the intelligent control module is connected to the output terminals of the data calculation and processing module and the historical data storage module, respectively. It is used to perform intelligent calculation and adjustment on real-time data and historical data to obtain the system adjustment output value, and return the system adjustment output value to each control and adjustment loop of the system.

[0018] In some embodiments, the control and regulation loop includes: an intermittent ash feeding control loop formed by the intelligent control system and the dust collector ash hopper level signal and the switch signal of the first automatic unloader, used to control the opening and closing of the first automatic unloader according to the ash storage hopper level.

[0019] The control and regulation loop also includes an automatic acid water feeding control loop formed by the intelligent control system, the flow signal of the acid water supply pipe, the frequency signal of the regulating valve, and the frequency signal of the second automatic unloader. This loop is used to control the second automatic unloader to control the furnace ash to enter the furnace ash dissolution box at a certain frequency, and to control the flow rate and the opening of the regulating valve on the acid water supply pipe, so that the furnace ash is added to the acid water at a rate of 4-15 g / L.

[0020] The control and regulation loop also includes a pH regulation loop for the ash dissolving tank formed by the intelligent control system, the pH signal of the inlet liquid of the oxidation tank, and the regulating valve of the first alkali supply pipe, which is used to control the flow rate and valve opening of the first alkali supply pipe and control the pH in the ash dissolving tank between 2 and 4.

[0021] The control and regulation loop also includes an oxidant feed control loop formed by the intelligent control system, the control valve and flow meter signals of the oxidant supply pipe, and the COD detection signal of the outlet liquid of the oxidation tank. This loop is used to control the COD of the liquid after the oxidation tank to be ≤45mg / L by adjusting the amount of oxidant and the opening of the regulating valve.

[0022] The control and regulation loop also includes a pH regulation loop formed by the intelligent control system and the pH signal of the liquid in the heavy metal removal tank, the flow rate of the first alkali supply pipe, and the opening signal of the regulating valve. The pH of the liquid in the heavy metal removal tank is controlled by the pH of the liquid in the heavy metal removal tank to control the flow rate of the first alkali supply pipe and the opening of the regulating valve, so as to control the pH of the liquid in the heavy metal removal tank between 7 and 10.

[0023] The control and regulation loop also includes an automatic dosing control loop formed by the intelligent control system, the inlet liquid flow signal of the heavy metal removal box, the flow meters of the first and second reagent supply pipes, and the corresponding regulating valves;

[0024] The control and regulation loop also includes a suspended solids regulation loop formed by the intelligent control system, the suspended solids detector signal at the outlet of the fine filter, and the backwash controller in the fine filter. This loop is used to control the backwashing program in the fine filter to be activated when the suspended solids at the outlet of the fine filter exceed the standard, so that the suspended solids concentration is <50mg / L.

[0025] The control and regulation loop also includes a denitrification agent control loop formed by the intelligent control system and the ammonia nitrogen detector signal of the feed liquid after the denitrification tank and the flow rate and regulating valve opening signal on the denitrification agent supply pipe. This loop is used to control the opening of the regulating valve on the denitrification agent supply pipe according to the ammonia nitrogen content after the denitrification tank to ensure that the ammonia nitrogen content is <35mg / L.

[0026] The control and regulation loop also includes a regulator feed control loop formed by the intelligent control system, the pH detector signal of the liquid behind the regulating tank, and the regulating valve on the regulator supply pipe. This loop is used to control the opening of the valve on the regulator supply pipe according to the pH of the purified liquid outlet, so as to ensure that the pH of the purified liquid is between 6 and 9.

[0027] In some implementations, the intelligent control module employs a PID algorithm; the calculation formula for PID control is:

[0028]

[0029] Where U(t) is the control quantity, Kp is the proportional coefficient, Ki is the integral coefficient, Kd is the differential coefficient, e(t) is the error function, and de / dt is the derivative of the error function.

[0030] In some implementations, the PID algorithm includes data integration and deviation calculation. In the data integration and deviation calculation: historical data is fitted using MATLAB to obtain the curves showing the variation of Kp, Ki, and Kd coefficients with the deviation between real-time process parameters and parameter setpoints; based on the deviation between real-time process parameters and parameter setpoints, and the curves showing the variation of Kp, Ki, and Kd with the deviation, corrected Kp, Ki, and Kd values ​​are obtained; at this point, the deviation between the original Kp, Ki, and Kd coefficient values ​​and the corrected Kp, Ki, and Kd coefficient values ​​is determined.

[0031] When the deviation is less than 1, the corrected Kp, Ki, and Kd are directly used in the PID control calculation to obtain the adjusted output value. The output value is fed back to the actuator for loop control and adjustment. After adjustment, the real-time process parameters of each loop are fed back to the data acquisition and storage module. When the deviation is greater than 1, the system returns to the historical data storage module to call more historical data, re-integrates the data and recalculates the deviation until the deviation is less than 1. If the deviation cannot be less than 1, the average of the calculated coefficient value with the smallest deviation judgment data and the original coefficient value is taken as the PID calculation coefficient for this PID control calculation, that is, the calculation of the control quantity of each process parameter. Among them, the Kp, Ki, and Kd coefficients finally used for calculation are used as the design values ​​for the next calculation, and this data is fed back to the historical data storage module for subsequent data retrieval.

[0032] Based on the above-mentioned treatment system, this utility model can also implement a method for treating furnace ash and acidic water, which includes the following steps according to the treatment system:

[0033] The intelligent control system controls the mixing of furnace ash and acidic water conveyed by the furnace ash conveying mechanism, and controls the pH of the liquid to be 2-4 to oxidize the liquid. After oxidation, the liquid is controlled to precipitate under alkaline conditions with a pH of 7-10, and then the first agent is applied to remove heavy metals. Then, the second agent is applied to continue to flocculate and precipitate.

[0034] After flocculation and sedimentation, the liquid is separated by settling. The resulting clarified solution is then denitrified. The purified liquid after denitrification is discharged after adjustment. The separated precipitate is then dried to form a dry sludge mixture of heavy metals, which is sent to the heavy metal recovery unit. The resulting filtrate is returned to the heavy metal removal treatment unit via pipeline.

[0035] In some embodiments, acidic water and furnace ash are introduced into the furnace ash dissolution tank in a certain proportion. The amount of alkaline solution added to the furnace ash dissolution tank is controlled to make the pH of the solution 2-4 before it is sent to the oxidation tank. The oxidant enters the oxidation tank and reacts with the organic matter in the solution to reduce the COD of the solution. Subsequently, the solution enters the heavy metal removal tank, and the pH of the heavy metal removal tank is adjusted to 7-10 by adding alkaline solution. The heavy metal ions react under alkaline conditions and form precipitates.

[0036] The first reagent enters the heavy metal removal tank, causing the unprecipitated heavy metals to form suspended solids; the liquid containing the suspended solids enters the flocculation sedimentation tank, where the second reagent enters the flocculation sedimentation tank, causing the suspended solids to destabilize and aggregate into larger particles, thereby settling or floating to the surface.

[0037] The feed liquid from the oxidation tank, heavy metal removal tank, and flocculation sedimentation tank is mixed and sent to the settling tank for sedimentation and separation. The resulting clear liquid enters the fine filter, and the clarified solution then enters the denitrification tank. The amount of denitrifying agent added is controlled by the ammonia nitrogen detector signal of the feed liquid after the denitrification tank. After removing ammonia nitrogen from the liquid phase, the purified liquid enters the regulating tank and is discharged. The heavy metal precipitates from the settling tank and fine filter are sent to the sludge drying treatment. The dry sludge that forms a heavy metal mixture is sent to the heavy metal recovery device. The resulting filtrate is returned to the oxidation tank through pipeline.

[0038] Among them, the gas phase in the ash dissolution box, oxidation box, heavy metal removal box and denitrification box is collected through pipelines and then enters the tail gas filtration equipment to the tail gas treatment system.

[0039] In some embodiments, the first agent is a heavy metal scavenging agent, and the amount added is 10-120 mg / L.

[0040] In some embodiments, sodium hydroxide is added to the heavy metal removal chamber through a second alkali supply pipe to adjust the pH of the heavy metal removal chamber.

[0041] In some embodiments, the second agent is PAM or polymeric iron salt, added at a concentration of 10–60 mg / L.

[0042] In some implementations, the pH of the purified solution is adjusted to 6-9 by adding alkaline or acidic solutions to the conditioning tank.

[0043] In some implementations, sodium hypochlorite is added to the denitrification tank through a denitrification agent supply pipe to carry out a denitrification reaction on the feed liquid.

[0044] Beneficial effects:

[0045] 1) This utility model synergistically treats alkaline furnace ash generated by an acrylonitrile unit and acidic water generated by a SAR unit. The alkaline furnace ash can replace a certain alkaline source to treat the acidic water, solving the problems of the inability to landfill and the difficulty in treating acrylonitrile unit furnace ash. Compared with the process of treating acidic water separately in industry, the consumption of alkali solution is reduced by 1-20%, which significantly improves the economic benefits of the system.

[0046] 2) This utility model system can synergistically treat acrylonitrile plant ash and SAR acidic water. It constructs a three-dimensional synergistic system integrating acidic water pH gradient regulation, heavy metal classification and precipitation, and intelligent PID logic control to improve Ni... 2 +、Cr 3 The removal efficiency of heavy metal ions is significantly improved, increasing the heavy metal removal rate by 0.1% to 5%. At the same time, it also has better removal effects on COD, ammonia nitrogen, SS, etc. Compared with the separate treatment of acidic water and furnace ash, it reduces the equipment footprint and investment, and lowers the construction cost of the equipment.

[0047] 3) This utility model can reduce the amount of furnace ash in acrylonitrile equipment by more than 80%. The main component of the treated mixture is heavy metals, which can be recovered by a heavy metal recovery device, turning waste into treasure and further realizing the reduction and resource utilization of solid waste.

[0048] 4) The intelligent control system adopted in this invention, while realizing the automated operation of the device, can accurately control the operation of the device and improve system safety by collecting, storing, calculating, analyzing and intelligently controlling the process parameters of the system. Due to the adoption of intelligent system control logic, the problems of over-adjustment, slow control rate, frequent adjustment and poor effect in traditional control logic are solved. Dynamic compensation of PID parameters is achieved, realizing rapid, stable and smooth control of the system.

[0049] 5) The design of the intelligent control system of this utility model makes the device operate stably, reduces the impact of the system on the flow rate, composition and water quality fluctuations in the feed, and improves the impact resistance of the device. Attached Figure Description

[0050] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0051] Figure 1 This is a schematic diagram of the system of this utility model.

[0052] Figure 2 This is a schematic diagram of the logic control principle of a traditional PID controller.

[0053] Figure 3 This is a schematic diagram of the control principle of the intelligent control system of this utility model.

[0054] The meanings of the symbols marked in the figure are as follows:

[0055] 1-Ash conveying mechanism; 101-Dust collector ash silo; 102-First automatic unloader; 103-Ash storage silo; 104-Ash conveying pipeline; 105-Second automatic unloader;

[0056] 2-Processing unit; 21-Acidic water supply pipe; 22-Oxidant supply pipe; 23-First alkali solution supply pipe; 24-Second alkali solution supply pipe; 25-First reagent supply pipe; 26-Second reagent supply pipe; 27-Denitrifying agent supply pipe; 28-Regulator supply pipe; 201-Ash dissolving box; 202-Tail gas filtration equipment; 203-Oxidation box; 204-Tail gas treatment equipment; 205-Heavy metal removal box; 206-Flocculation sedimentation box; 207-Settler; 208-Fine filter; 209-Denitrification box; 210-Regulating box; 211-Sludge drying equipment;

[0057] 3-Intelligent control system; 31-Data acquisition and storage module; 32-Data calculation and processing module; 33-Intelligent control module; 34-Historical data storage module; 35-Human-machine interface. Detailed Implementation

[0058] The present invention will be further explained in detail below with reference to the accompanying drawings and specific embodiments. However, the following description of the embodiments is only intended to enable those skilled in the art to better understand the principles and essence of the present invention, and does not imply any limitation on the present invention.

[0059] To keep the drawings concise, each drawing only schematically shows the parts relevant to the application; these do not represent the actual structure of the product. Furthermore, to facilitate understanding, in some drawings, components with the same structure or function are shown only schematically, or only one is labeled.

[0060] In this document, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0061] Furthermore, in the description of this application, the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. It should be noted that the following embodiments can be freely combined as needed.

[0062] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0063] This utility model discloses a furnace ash acidic water treatment system, comprising a furnace ash conveying mechanism 1, a treatment mechanism 2 connected downstream of the furnace ash conveying mechanism, and an intelligent control system 3. The treatment mechanism 2 is also connected to an acidic water source for the synergistic treatment of the acidic water and furnace ash. The intelligent control system 3 is connected to the furnace ash conveying mechanism 1 and the treatment mechanism 2 to form a control and regulation loop that collects, stores, calculates, and adjusts the output. Based on this, by synergistically treating furnace ash and acidic water, combined with the design of an intelligent control system, the system achieves automated operation while simultaneously collecting, storing, calculating, analyzing, and intelligently controlling the system's process parameters. This enables precise output adjustment to control device operation, reducing labor costs and the frequency of misoperation, and improving system safety.

[0064] refer to Figure 1 The ash conveying mechanism 1 includes a dust collector ash silo 101, a first automatic unloading machine 102, and an ash storage silo 103 connected in sequence, and is connected to the processing unit 2 via an ash conveying pipeline 104. The dust collector ash silo 101 is the ash silo of the dust collector in the upstream original unit. The ash in silo passes sequentially through the first automatic unloading machine 102, the ash storage silo 103, and the second automatic unloading machine 105, and is then quantitatively and continuously fed into the processing unit 2 via the ash conveying pipeline 104. Generally, the ash conveying pipeline 104 adopts pneumatic conveying or chain conveying.

[0065] The processing unit 2 includes a furnace ash dissolving tank 201, an oxidation tank 203, a heavy metal removal tank 205, a flocculation sedimentation tank 206, a settling tank 207, a fine filter 208, a denitrification tank 209, and a regulating tank 210, all connected sequentially along the slurry flow direction. It also includes sludge drying equipment for receiving sludge from each unit. The furnace ash dissolving tank 201 is connected downstream of the furnace ash conveying unit 1. The furnace ash dissolving tank 201 is equipped with an acidic water supply pipe 21 and a first alkaline solution supply pipe 23. By controlling the ratio of acidic water to furnace ash entering the furnace ash dissolving tank 201, the pH of the slurry in the furnace ash dissolving tank 201 is maintained between 2 and 4. Thus, the acidity or alkalinity of the slurry in the furnace ash dissolving tank 201 is adjusted by controlling the feed ratio of acidic water and furnace ash. In one embodiment, the upper part of the ash dissolving box 201 is connected to a tail gas filtration device 202 via a pipeline, which is used to send the gas phase in the box to the tail gas treatment system. A fan can be installed downstream of the tail gas filtration device 202 to accelerate the tail gas treatment.

[0066] The processing unit 2 is equipped with corresponding pipelines for supplying various materials for the treatment of furnace ash and acidic water, including acidic water supply pipe 21, oxidant supply pipe 22, first alkali supply pipe 23, second alkali supply pipe 24, first reagent supply pipe 25, second reagent supply pipe 26, denitrifying agent supply pipe 27, and regulator supply pipe 28.

[0067] In a specific embodiment, the oxidation tank 203 is equipped with an oxidant supply pipe 22 for removing COD from furnace ash and acidic water. The oxidation tank 203 is also equipped with a gas phase pipeline connected to a tail gas processor 204. The gas phase inside the tank passes through the tail gas processor 204 and then enters the tail gas filtration device 202. The oxidant supplied is H2O2, or other commonly used oxidants of the same type in the art.

[0068] The heavy metal removal tank 205 is equipped with an alkali supply pipe 23 and a first reagent supply pipe 25, which are used to adjust the pH of the liquid in the heavy metal removal tank 205, and simultaneously precipitate and remove heavy metals therein, forming suspended solids. The flocculation sedimentation tank 206 is connected to a second reagent feed pipe 25, which is used to aggregate the suspended solids and heavy metal precipitates in the liquid into larger particles, facilitating subsequent sedimentation.

[0069] Specifically, sodium hydroxide is added through the alkali supply pipe 23 to adjust the pH of the heavy metal removal tank 205 to 7-10. Under alkaline conditions, heavy metal ions undergo the following reactions and form precipitates. The main reactions include:

[0070] ①Fe 3+ +OH - →Fe(OH)3↓

[0071] ②Ni 2+ +OH - →Ni(OH)2↓

[0072] ③Bi 3+ +OH - →Bi(OH)3↓

[0073] ④Cr 3+ +OH - →Cr(OH)3↓

[0074] ⑤Cu 2+ +OH - →Cu(OH)2↓

[0075] ⑥Hg 2+ +OH - →Hg(OH)2↓

[0076] ⑦Zn 2+ +OH - →Zn(OH)2↓

[0077] ⑧Pb 2+ +OH - →Pb(OH)2↓

[0078] ⑨NH 4+ +OH - →NH3↑+H2O

[0079] ⑩ NaOH + NaHCO3 → Na2CO3 + H2O

[0080] Fe, Ni, Bi, Cr, Cu, and Hg mostly react to form hydroxide precipitates under alkaline conditions. Furthermore, Fe(OH)3, as an excellent flocculant, can accelerate the precipitation rate of other metal ions. Sodium and a small portion of unreacted heavy metals remain in the liquid phase as ions. The first reagent enters the heavy metal removal tank 205 via the first reagent supply pipe 24, further promoting the formation of suspended precipitates from unprecipitated heavy metals. The first reagent is a heavy metal scavenging agent, typically sodium sulfide or an organic sulfide. The dosage of the first reagent is related to the feed flow rate, controlled at 10–120 mg / L. The feed containing suspended solids enters the flocculation sedimentation tank 206. The second reagent enters the flocculation sedimentation tank 206 via the second reagent supply pipe 25, further destabilizing the suspended solids and agglomerating them into larger particles, thus causing them to precipitate or float to the surface. The dosage of the second reagent is controlled at 10–60 mg / L, typically PAM or polyferric salt.

[0081] Continue to refer to Figure 1 The dust-laden liquid in the oxidation tank 203, heavy metal removal tank 205, and flocculation sedimentation tank 206 is mixed via pipelines and then sent to the settling tank 207. The settling tank 207 is equipped with inclined plates or inclined tubes. This increases the sedimentation area, shortens the sedimentation time, and improves sedimentation efficiency. Large particles of precipitate are removed from the flocculated and settled liquid.

[0082] The fine filter 208, located downstream of the settling tank 207, further filters the remaining small amount of suspended solids after sedimentation to obtain a clarified solution. The denitrification tank 209 is equipped with a denitrifying agent supply pipe 26 to remove ammonia nitrogen from the feed liquid. The regulating tank 210 is equipped with a regulating agent supply pipe 27 to adjust the pH of the outlet purified liquid to meet the requirements of downstream devices. In some embodiments, the fine filter 208 can be used for fine filtration using membrane filtration, metal cartridge filtration, or fixed-bed technology. To prevent clogging during long-term operation, it is cleaned periodically, and the waste liquid after cleaning is pumped to the sludge drying equipment 211 for treatment. Specifically, the sludge drying equipment 211 is connected to the bottom of the settling tank 207 and the bottom of the fine filter 208 via pipelines. The settled suspended solids and heavy metals precipitate in the sludge drying equipment 211, removing some water and forming a heavy metal mixture, which is then sent to the heavy metal recovery device as dry sludge. The sludge drying equipment 211 employs a plate and frame filter press, a dry sludge filter, etc. At this point, the purified liquid obtained from the regulating tank 210 is sent out of the system, and the sludge is dried to obtain a mixture containing heavy metals for heavy metal recovery. In addition, both the heavy metal removal tank 205 and the denitrification tank 209 are equipped with gas phase pipelines, and the gas phase is collected through the pipelines and enters the tail gas filtration equipment 202 to the tail gas treatment system.

[0083] The intelligent control system includes a data acquisition and storage module 31, a data calculation and processing module 32, an intelligent control module 33, a historical data storage module 34, and a human-machine interface 35.

[0084] The input terminal of the data acquisition and storage module 31 is connected to the ash conveying mechanism 1 and the processing mechanism 2, and is used to collect process parameters and parameter settings for data processing and storage. The process parameters include all relevant process data related to the aforementioned system structure. Examples of the main process parameters collected are as follows, including but not limited to: dust collector ash silo level, ash storage silo level, automatic unloading machine switch and frequency, acid water supply pipe flow rate, first alkali supply pipe flow rate, ash dissolving tank pH, oxidation tank inlet pH, oxidant supply pipe flow rate, oxidation tank outlet liquid COD, heavy metal removal tank liquid pH, second alkali supply pipe flow rate, metal removal tank inlet liquid flow rate, first reagent supply pipe flow rate, second reagent supply pipe flow rate, fine filter outlet suspended solids (SS) detection data, fine filter backwashing program parameters and frequency, ammonia nitrogen detection of liquid after denitrification tank, denitrifying agent supply pipe flow rate, regulating tank liquid pH and regulating agent supply pipe flow rate.

[0085] The input end of the data calculation and processing module 32 is connected to the output end of the data acquisition and storage module 31, so that the process parameters and parameter settings are processed and stored in the data acquisition and storage module 31 and then transmitted to the data calculation and processing module 32 for data calculation and processing.

[0086] The input end of the historical data storage module 34 is connected to the output end of the data acquisition and storage module 31, and is used to store historical data within a certain period of time for the intelligent control system 3 to call and analyze.

[0087] The input terminal of the intelligent control module 33 is connected to the output terminals of the data calculation and processing module 32 and the historical data storage module 34, respectively. It is used to perform intelligent calculation and adjustment on real-time data (such as real-time process parameters) and historical data to obtain the system adjustment output value, and return the system adjustment output value to each control and regulation loop of the system.

[0088] refer to Figure 3 The control and regulation loop formed by the intelligent control system interconnecting with the ash conveying mechanism 1 and the processing mechanism 2 includes: an intermittent ash feeding control loop formed by the intelligent control system 3 and the ash level signal of the dust collector ash hopper 101 and the switch signal of the first automatic unloader 102, used to control the opening and closing of the first automatic unloader 102 according to the ash level of the ash storage hopper 103; in specific application implementation, when the ash level of the ash storage hopper 103 is lower than 20%, the first automatic unloader 102 is opened; when the ash level of the ash storage hopper 103 reaches 80%, the first automatic unloader 102 is closed.

[0089] In one embodiment, it also includes an automatic acid water feeding control loop formed by the intelligent control system 3, the flow signal of the acid water supply pipe 21, the frequency signal of the regulating valve, and the frequency signal of the second automatic unloading machine 105. This loop is used to control the second automatic unloading machine 105 to feed the furnace ash into the furnace ash dissolving box 201 at a certain frequency, and to add the furnace ash to the acid water at a dosage of 4 to 15 g / L by controlling the flow rate on the acid water supply pipe 21 and the opening of the regulating valve.

[0090] In one embodiment, it also includes a pH adjustment loop for the ash dissolving tank formed by the intelligent control system, the pH signal of the feed liquid at the inlet of the oxidation tank 203, and the regulating valve of the first alkali supply pipe, for controlling the flow rate of the alkali supply pipe and the valve opening, so as to control the pH in the ash dissolving tank between 2 and 4.

[0091] In one embodiment, it also includes an oxidant feed control loop formed by the intelligent control system, the control valve and flow meter signal of the oxidant supply pipe 22, and the COD detection signal of the liquid at the outlet of the oxidation tank 203, for controlling and adjusting the amount of oxidant and the opening of the regulating valve so that the COD of the liquid after the oxidation tank is ≤45mg / L.

[0092] In one embodiment, the system further includes an intelligent control system and a pH regulation loop formed by the pH signal of the liquid in the heavy metal removal tank 205, the flow rate of the second alkali supply pipe 24, and the opening signal of the regulating valve. This loop is used to control the flow rate of the second alkali supply pipe 24 and the opening of the regulating valve by controlling the pH of the liquid in the heavy metal removal tank 205, thereby controlling the pH of the liquid in the heavy metal removal tank 205 between 7 and 10.

[0093] In one embodiment, an automatic dosing control loop is further included, consisting of an intelligent control system, the inlet liquid flow signal of the heavy metal removal tank 205, flow meters of the first reagent supply pipe 25 and the second reagent supply pipe 26, and corresponding regulating valves. The first reagent supplied by the first reagent supply pipe 25 is a heavy metal scavenging agent, typically sodium sulfide or an organic sulfide. The dosage of the first reagent is related to the liquid flow rate and ranges from 10 to 120 mg / L. The second reagent supplied by the second reagent supply pipe is selected from PAM, polyferric salts, or ferric sulfate, and the dosage ranges from 5 to 200 mg / L, controlled according to the inlet liquid flow rate.

[0094] In one embodiment, the system further includes a suspended solids regulation loop formed by the intelligent control system 3, the suspended solids detector signal at the outlet of the fine filter 208, and the backwash controller in the fine filter 208. This loop is used to control the backwashing program in the fine filter 208 to start when the suspended solids at the outlet of the fine filter exceed the standard, thereby increasing the filtration intensity in the precision filter box, preventing clogging, and ensuring that the suspended solids concentration is <50mg / L.

[0095] In one embodiment, the system further includes a denitrifying agent control loop formed by the intelligent control system 3, the ammonia nitrogen detector signal after the denitrification tank 209, and the flow rate and regulating valve opening signal on the denitrifying agent supply pipe 27. This loop controls the opening of the regulating valve on the denitrifying agent supply pipe 27 according to the ammonia nitrogen content after the denitrification tank 209, ensuring that the ammonia nitrogen content is <35 mg / L. Sodium hypochlorite is selected as the denitrifying agent.

[0096] In one embodiment, it also includes an intelligent control system 3 and a regulator feed control loop formed by the pH detector of the feed liquid after the regulating tank 210 (used to detect the pH of the purified liquid outlet downstream of the regulating tank) and the regulating valve on the regulator supply pipe 28, used to control the opening of the valve on the regulator supply pipe 28 according to the pH of the purified liquid outlet, so as to ensure that the pH of the purified liquid is between 6 and 9.

[0097] The adjustment and control signals involved in the above-mentioned control and regulation loops are all collected, stored, calculated, processed, and intelligently analyzed and adjusted by the intelligent control system 3 before being fed back to each loop of the system for signal control and adjustment of each process parameter, so as to achieve rapid, stable and precise control of the device.

[0098] In one embodiment, the intelligent control module 33 employs a PID algorithm, and the calculation formula for PID control is as follows:

[0099]

[0100] Where U(t) is the control input, Kp is the proportional coefficient, representing the proportional gain; Ki is the integral coefficient, reflecting the speed of error elimination; Kd is the derivative coefficient, used for the time span of derivative prediction; e(t) is the error function, and de / dt is the derivative of the error function.

[0101] However, in actual production, these three coefficients are often obtained based on experience or through manual adjustments during the start-up process, resulting in significant errors. For example... Figure 2 Traditional PID control methods are prone to problems such as over-adjustment, frequent adjustments, poor control performance, and adjustment lag when the initial value error is large.

[0102] In one embodiment, it was proposed Figure 3 The intelligent system control logic shown in the diagram involves inputting the real-time process parameters detected in the system and the required parameter setpoints for each process parameter into the data acquisition and storage module 31. After storage, the data is simultaneously transmitted to the data calculation and processing module 32 and the historical data storage module 34. In the data calculation and processing module 32, data processing is performed, including signal conversion, data compensation and correction, and deviation calculation between the real-time process parameters and parameter setpoints. Initial values ​​are calculated using given logical calculation formulas and input into the intelligent control module 33. Specifically, the data calculation and processing module 32 processes the real-time process parameters and parameter setpoints, such as converting flow signals into electrical signals and converting between flow signals and frequencies. The resulting converted or corrected data is then compared with the setpoints, and the difference is calculated. This difference is then input into the intelligent control module 33 for data integration.

[0103] Compared Figure 2 Traditional PID control methods, refer to Figure 3The PID algorithm includes data integration and deviation calculation. The difference between the real-time process parameters and parameter setpoints output from the data calculation and processing module 32 to the intelligent control module 33, and the historical data within a certain period of time called from the historical data storage module 34, including: real-time process parameter data, corresponding parameter setpoints, and corresponding Kp, Ki, and Kd data (assuming the initial data is historical data within 3 months), are jointly called in the intelligent control module 33 for data integration and deviation calculation. In data integration and deviation calculation: MATLAB is used to fit historical data to obtain the curves of Kp, Ki, and Kd coefficients changing with the deviation between real-time process parameters and parameter setpoints; based on the deviation between real-time process parameters and parameter setpoints, and the curves of Kp, Ki, and Kd coefficients changing with the deviation, the corrected Kp, Ki, and Kd coefficient values ​​are obtained; at this point, the original Kp, Ki, and Kd coefficient values ​​and the corrected Kp, Ki, and Kd coefficient values ​​are compared to determine the deviation: when the deviation is less than 1, the corrected Kp, Ki, and Kd are directly used in PID control calculation to obtain the adjusted output values ​​of each process parameter. The adjusted output values ​​are fed back to the actuator for loop control and adjustment, and the adjusted real-time process parameters of each loop are fed back to the data acquisition and storage module 31; when the deviation is greater than 1, the system returns to the historical data storage module 34 to call more historical data, and re-integrates and calculates the data deviation until the deviation is less than 1. In PID algorithms, historical data is typically retrieved at a frequency of one month, limited to six times. If the deviation judgment of less than 1 cannot be satisfied, the average of the calculated coefficient values ​​(Kp, Ki, and Kd) with the smallest deviation judgment data and the previously obtained design values ​​of Kp, Ki, and Kd is used as the input values ​​for the proportional coefficient Kp, integral coefficient Ki, and derivative coefficient Kd in the current PID calculation. The Kp, Ki, and Kd coefficients used in this calculation become the design values ​​for the next PID calculation, corresponding to the original Kp, Ki, and Kd coefficient values ​​recalculated for the next path. This Kp, Ki, and Kd data is fed back to the historical data storage module 34 for subsequent data retrieval by the intelligent control module 33. It should be noted that the deviation is calculated by dividing the difference between the corrected coefficient and the original coefficient by the original coefficient, and then taking the absolute value of the result. The absolute value is then compared with 1, which is the deviation judgment. After PID calculation, the real-time adjustment output values ​​of each process parameter are obtained and output to the corresponding control and regulation loop through the actuator. The real-time process parameters are also fed back to the data acquisition and storage module 31 for recalculation of the next path.

[0104] The intelligent control system 3 is also equipped with a human-machine interface 35, which is used by operators to visually monitor and operate the system, remotely access and control it, and restrict information security operations of the control system.

[0105] Combination Figure 1The acidic wastewater treatment system for furnace ash provided by the present invention, according to the above embodiments, can implement corresponding methods for treating furnace ash and acidic wastewater. The system performs the following steps:

[0106] The intelligent control system controls the mixing of furnace ash and acidic water conveyed by the furnace ash conveying mechanism 1, and controls the pH of the liquid to be 2-4 to oxidize the liquid. After oxidation, the liquid is controlled to precipitate under alkaline conditions with a pH of 7-10, and then the first agent is applied to remove heavy metals. Then, the second agent is applied to continue to cause flocculation and precipitation.

[0107] After flocculation and sedimentation, the liquid is separated by settling. The resulting clarified solution is then denitrified. The purified liquid after denitrification is discharged after adjustment. The separated precipitate is then dried to form a dry sludge mixture of heavy metals, which is sent to the heavy metal recovery unit. The resulting filtrate is returned to the heavy metal removal treatment unit via pipeline.

[0108] In one embodiment, the ash in the ash storage bin 103 is fed into the ash dissolving tank 201 via the automatic unloading machine 105 and the ash conveying pipeline 104. Acidic water from the acidic water supply pipe 21 and ash are introduced into the ash dissolving tank 201 in a certain proportion. The amount of alkali added to the ash dissolving tank 201 is controlled to make the pH of the liquid 2-4. The mixed liquid is then pumped into the oxidation tank 203. The oxidant enters the oxidation tank 203 through the oxidant supply pipe 22 and reacts with the organic matter in the liquid to reduce the COD of the liquid. The COD removal efficiency is controlled by the amount of oxidant added. Subsequently, the liquid is pumped into the heavy metal removal tank 205. Sodium hydroxide is added through the second alkali supply pipe 26 to adjust the pH of the heavy metal removal tank 205 to 7-10. Under alkaline conditions, the heavy metal ions undergo the following reaction and form precipitates.

[0109] The first reagent enters the heavy metal removal tank 205 through the first reagent supply pipe 25, further promoting the formation of suspended precipitates of unprecipitated heavy metals; the liquid containing suspended matter enters the flocculation sedimentation tank 206, and the second reagent enters the flocculation sedimentation tank 206 through the second reagent supply pipe 26, causing the suspended matter to destabilize and aggregate into larger particles, thereby settling or floating to the surface of the water.

[0110] After the feed liquid from oxidation tank 203, heavy metal removal tank 205 and flocculation sedimentation tank 206 is mixed, it is pumped to sedimentation tank 207 to remove large suspended particles. The resulting clear liquid enters fine filter 208 to further achieve liquid-solid separation, remove small precipitate, and obtain a clear solution.

[0111] The clarified solution then enters the denitrification tank 209, where it reacts with the sodium hypochlorite solution that enters from the denitrifying agent supply pipe 27 to remove ammonia nitrogen from the liquid phase. The amount of denitrifying agent added is controlled by the signal from the ammonia nitrogen detector in the feed liquid after the denitrification tank 209. The purified liquid after denitrification enters the regulating tank 210 and is discharged after meeting the downstream purified liquid receiving standards.

[0112] Heavy metal precipitates from settling tank 207 and fine filter 208 are pumped into sludge drying equipment 211. After settling, most of the water in the sludge drying equipment 211 is removed from the suspended solids and heavy metal precipitates. The resulting heavy metal mixture is sent to the heavy metal recovery device in the form of dry sludge. The generated filtrate is returned to oxidation tank 203 through pipeline.

[0113] Gas phase pipelines are installed on the ash dissolution box 201, oxidation box 203, heavy metal removal box 205 and denitrification box 209. The gas phase is collected through the pipelines and enters the tail gas filtration equipment 202 to the tail gas treatment system.

[0114] In one embodiment, the first reagent is a heavy metal scavenging agent, preferably sodium sulfide or an organosulfur compound; the amount of the first reagent added is related to the feed flow rate and is 10–120 mg / L. In the heavy metal removal tank 205, sodium hydroxide is added through the alkali supply pipe to adjust the pH to 7–10. The amount of the second reagent added is 10–60 mg / L, generally PAM or polyferric salt. In the adjustment tank 210, after adding alkali or acid, the pH of the purified solution is adjusted to between 6 and 9.

[0115] Based on the above embodiments, the following detailed implementation description is provided:

[0116] Example 1

[0117] The furnace ash from the acrylonitrile unit dust collector ash silo 101 contains a large amount of Na2CO3 and Fe, Ni, Bi, Cr, Cu, Hg, Zn, Pb, and a small amount of incompletely burned organic matter and ammonium sulfate. It enters the furnace ash storage silo 103 via the first automatic unloading machine 102. The intermittent feeding of furnace ash is regulated based on the material level signal of the furnace ash storage silo 103 and the on / off signal of the first automatic unloading machine 102. The furnace ash in the furnace ash storage silo 103 is then fed into the furnace ash dissolving tank 201 via the second automatic unloading machine 105 and the furnace ash conveying pipeline 104. Acidic water from the acidic water supply pipe 21 is mixed with furnace ash at a ratio of 4-15g furnace ash / 1L acidic water and enters the furnace ash dissolving tank 201. Simultaneously, the flow rate and valve opening of the first alkali supply pipe 23 are controlled, and sodium hydroxide solution is added to adjust the pH of the liquid in the furnace ash dissolving tank 201 to between 2 and 4. The mixed liquid is pumped into oxidation tank 203. Oxidant enters oxidation tank 203 via oxidant supply pipe 22 to react with organic matter in the liquid, reducing COD. The COD removal efficiency is controlled by the dosage of oxidant, ensuring COD ≤ 45 mg / L. H2O2 or O3 can be used as the oxidant. Subsequently, the liquid is pumped into heavy metal removal tank 205. Sodium hydroxide is added via second alkaline solution supply pipe 24 to adjust the pH of heavy metal removal tank 205 to 7–10. Heavy metal ions react and form precipitates under alkaline conditions. The first reagent enters via first reagent supply pipe 25. In the heavy metal removal tank 205, the unprecipitated heavy metals are further promoted to form suspended sediment. The first agent is a heavy metal capture agent, such as sodium sulfide or organic sulfides. The amount of the first agent added is related to the flow rate of the liquid, and the amount added is controlled at 10-120 mg / L. The liquid containing suspended solids further enters the flocculation sedimentation tank 206. The second agent enters the flocculation sedimentation tank 206 through the second agent supply pipe 26, which destabilizes the suspended solids and aggregates them into larger particles, thereby causing them to settle or float to the surface. The amount of the second agent added is 5-200 mg / L, and PAM, polyferric salts, or ferric sulfate are generally selected.

[0118] The dust-laden liquid from oxidation tank 203, heavy metal removal tank 205, and flocculation sedimentation tank 206 is mixed and pumped to settling tank 207 to remove large suspended particles. The resulting clear liquid enters fine filter 208 for further liquid-solid separation, removing small precipitates and yielding a clear solution. Fine filter 208 uses precision filtration methods including, but not limited to, filter cartridges, membranes, or fixed beds. The clear solution then enters denitrification tank 209, where it reacts with sodium hypochlorite solution supplied from denitrifying agent supply pipe 27. The amount of denitrifying agent added is fed back to the intelligent control system 3 via the ammonia nitrogen content in the liquid after denitrification tank 209 for output parameter control and adjustment. The purified liquid after ammonia nitrogen removal enters regulating tank 210, where alkaline or acidic solutions are added via regulating agent supply pipe 28 to adjust the pH of the purified liquid to between 6 and 9, meeting the downstream unit's purified liquid receiving standards before being discharged.

[0119] Heavy metal precipitates from settling tank 207 and fine filter 208 are pumped into sludge drying equipment 211. After settling, most of the water in the sludge drying equipment 211 is removed from the suspended solids and heavy metal precipitates. The resulting heavy metal mixture is sent to the heavy metal recovery device in the form of dry sludge to recover the heavy metal substances and increase the system's economic efficiency. The generated filtrate is returned to the heavy metal removal tank 205 via pipeline.

[0120] The oxidation chamber 203 is equipped with a gas phase pipeline, which leads to the exhaust gas filter 202 after passing through the exhaust gas processor 204. The ash dissolution chamber 201, the heavy metal removal chamber 205, and the denitrification chamber 209 are all equipped with gas phase pipelines, which collect the gas phase before it enters the exhaust gas filter 202 for the exhaust gas treatment system.

[0121] The process parameter detection signals in the above-mentioned adjustment and control loops are all transmitted to the intelligent control system 3. The real-time detected process parameters are first input into the data acquisition and storage module 31 for storage, and then the detection data are input into the data calculation and processing module 32 and the historical data storage module 34 respectively. In the data calculation and processing module 32, the real-time process parameters and parameter set values ​​are converted, data is compensated and corrected, and the deviation between the real-time process parameters and parameter set values ​​is calculated. The initial values ​​are calculated using the given logical calculation formula and input into the intelligent control module 33.

[0122] In data integration and deviation calculation, MATLAB is used to fit historical data, obtaining the curves of Kp, Ki, and Kd as a function of the deviation between the input parameters and the setpoint. Based on real-time data and the corresponding curves of Kp, Ki, and Kd as a function of the deviation between the input parameters and the setpoint, corrected Kp, Ki, and Kd values ​​are obtained. At this point, the original Kp, Ki, and Kd are compared with the corrected Kp, Ki, and Kd to determine the deviation. When the deviation is less than 1, the corrected Kp, Ki, and Kd are directly used in the PID control calculation to obtain the adjusted output value. This output value is fed back to the actuator for control loop adjustment and also to the historical data storage module 34 for subsequent data integration and deviation calculation in the intelligent control module 33. When the deviation is greater than 1, the system returns to the historical data storage module 34 to retrieve more historical data and re-integrate and calculate the deviation until the deviation is less than 1. Generally, historical data is retrieved at a frequency of one month, limited to six times. If the deviation cannot be less than 1, the average of the calculated data with the smallest deviation and the original data is used as the PID calculation input value.

[0123] The intelligent control system 3 also includes a human-machine interface 35, which is mainly used for personnel to perform visual monitoring and operation of the system, remote access and control, and to restrict information security operations of the control system.

[0124] Example 2

[0125] This example, based on Example 1, specifies concrete process parameters, specifically: The intelligent control system 3 automatically regulates the frequency of the automatic unloading machine, the flow rate of the acidic water supply pipe, and the opening of the regulating valve. The ratio of furnace ash to acidic water is set at 6 g / L, resulting in a furnace ash feed rate of 210 kg / h. The ash is then conveyed to the furnace ash dissolving tank 201 via the pneumatic conveying pipeline 104. The amount of acidic water added at this time is 35 m³. 3 The flow rate of the first alkali supply pipe 23 and the opening of the regulating valve are adjusted to make the pH of the liquid after the ash dissolution tank 201 2.5. 30wt% sodium hydroxide is used as the alkali solution, and the addition rate is controlled at 630kg / h. The mixed liquid enters the oxidation tank 203, and the addition rate of 7.5% H2O2 oxidant is controlled at 410L / h. At this time, the COD content at the outlet is 35mg / L. The oxidized liquid enters the heavy metal removal tank 205. The flow rate of sodium hydroxide solution added through the second alkali supply pipe 24 is controlled to make the pH of the heavy metal removal tank 205 8. Sodium sulfide heavy metal capture agent is added through the first reagent supply pipe 25 at a rate of 10mg / L. Then the liquid enters the flocculation sedimentation tank 206, and PAM second reagent is added through the second reagent supply pipe 26 at a rate of 10mg / L.

[0126] The dust-laden liquid from oxidation tank 203, heavy metal removal tank 205, and flocculation sedimentation tank 206 is mixed and pumped to settling tank 207 to remove large suspended particles. The resulting clear liquid enters fine filter 208 for further liquid-solid separation, removing small precipitates and yielding a clear solution. Fixed-bed filtration is used for this fine filtration, and the suspended solids (SS) in the filtrate are 33 mg / L. The clear solution then enters denitrification tank 209, where it reacts with sodium hypochlorite solution supplied from denitrifying agent supply pipe 27 to remove ammonia nitrogen from the liquid phase. The addition rate of 10 wt% sodium hypochlorite is 67 L / h. The purified liquid then enters regulating tank 210, where a small amount of acid is added via regulating agent supply pipe 28 to adjust the pH to approximately 7, meeting the downstream unit's purification liquid receiving standards before discharge. After processing by this system, the 210 kg / h furnace ash yields approximately 21.7 kg / h of sludge from the sludge drying equipment, representing a 90% reduction in sludge volume.

[0127] The final results for each pollutant indicator are shown in Table 1.

[0128] Table 1. Pollutant Indicators in Dissolving Tank, Oxidation Tank, Fine Filter, Denitrification Tank, and Purified Liquid

[0129] Logistics Name Dissolver tank outlet water Oxidation tank effluent Fine filter effluent Denitrification tank effluent Purification liquid <![CDATA[Flow rate m 3 / L]]> 35.5 35.5 35 35 35 <![CDATA[COD cr mg / L]]> 406 35 30 30 30 BOD mg / L 40 Not detected Not detected Not detected Not detected ammonia nitrogen mg / L 350 350 350 5 5 SS mg / L 234 234 5 5 5 pH 2.5 2.5 8 8.4 7.1

[0130] Comparative Example 1

[0131] Based on Example 2, the intelligent control system is removed, and based on Figure 2 The original PID control logic performs the above control process, and the final results of various pollutant indicators are shown in Table 2.

[0132] Table 2. Pollutant Indicators in Dissolving Tank, Oxidation Tank, Fine Filter, Denitrification Tank, and Purified Liquid

[0133] Logistics Name Dissolver tank outlet water Oxidation tank effluent Fine filter effluent Denitrification tank effluent Purification liquid <![CDATA[Flow rate m 3 / L]]> 35.5 35.5 35 35 35 <![CDATA[COD cr mg / L]]> 406 45 45 45 45 BOD mg / L 40 Not detected Not detected Not detected Not detected ammonia nitrogen mg / L 350 350 350 12 12 SS mg / L 234 234 8 8 8 pH 2.6 2.6 8～9 8～9 7～7.5

[0134] Comparative Example 2

[0135] Based on the same acidic water as in Example 2, without adding furnace ash, 30% w sodium hydroxide is directly used as the alkali source, and the pH of the acidic water is also adjusted to 2.5. At this time, the amount of alkali solution to be added increases from 630 kg / h to 706 kg / h, and the alkali consumption increases by about 12%.

[0136] Comparative Example 3

[0137] Based on Example 2, the amount of furnace ash added was increased to three times, i.e., 18 g / L. When the pH of the acidic water was also adjusted to 2.5, the dosage of 30% wt sodium hydroxide was 614.6 kg / h. The dosage of other unit reagents was also increased to three times, i.e., 7.5%. The H2O2 addition rate is 1230 L / h, at which point the outlet COD content is 43 mg / L. Sodium sulfide, a heavy metal scavenging agent, is added at a rate of 30 mg / L through the first reagent supply pipe 25, and PAM, a second reagent, is added at a rate of 30 mg / L through the second reagent supply pipe 26. The sodium hypochlorite solution entering from the denitrifying agent supply pipe 27 reacts to remove ammonia nitrogen from the liquid phase. The addition rate of 10 wt% sodium hypochlorite is 201 L / h. The purified liquid then enters the regulating tank 210. After adding a small amount of acid through the regulating agent supply pipe 28, the pH of the purified liquid is adjusted to approximately 7, meeting the downstream unit's purified liquid receiving standards before being discharged. The final results for various pollutant indicators are shown in Table 3.

[0138] As can be seen from Table 3, after the amount of furnace ash added was increased by 3 times, the corresponding amount of sodium hydroxide solution was reduced by only 2.5%. Although the amount of each treatment agent added in the downstream process was increased accordingly, the system treatment effect also deteriorated.

[0139] Table 3. Pollutant Indicators in Dissolving Tank, Oxidation Tank, Fine Filter, Denitrification Tank, and Purified Liquid

[0140] Logistics Name Dissolver tank outlet water Oxidation tank effluent Fine filter effluent Denitrification tank effluent Purification liquid <![CDATA[Flow rate m 3 / L]]> 35.5 35.5 35 35 35 <![CDATA[COD cr mg / L]]> 1138 48 43 43 43 BOD mg / L 40 Not detected Not detected Not detected Not detected ammonia nitrogen mg / L 998 998 995 10 10 SS mg / L 702 702 8 8 8 pH 2.5 2.5 8 8.4 7.1

[0141] Example 3

[0142] This example, based on Example 1, specifies concrete process parameters, specifically: The intelligent control system 3 automatically regulates the frequency of the automatic unloading machine and the opening of the acidic water supply pipe flow regulating valve, adjusting the ratio of furnace ash to acidic water at 8 g / L. At this point, the furnace ash feed rate is 360 kg / h, and the ash is conveyed to the furnace ash dissolving tank 201 via the pneumatic conveying pipeline 104. The amount of acidic water added is 45 m³. 3 The flow rate and valve opening of the first alkali supply pipe 23 are adjusted to make the pH of the ash solution after the ash dissolution tank 201 reach 3. 30wt% sodium hydroxide is used as the alkali solution, with an addition rate of 850 kg / h. The mixed ash solution enters the oxidation tank 203. The oxidant addition rate is controlled according to the COD detector. O3 is selected as the oxidant, and the addition rate of O3 is 40.5 kg / h. At this time, the COD content at the outlet of the oxidation tank is 37 mg / L. The oxidized ash solution enters the heavy metal removal tank 205. Sodium hydroxide solution is added through the second alkali supply pipe 24 to make the pH of the heavy metal removal tank 205 reach 8. Sodium sulfide, a heavy metal scavenging agent, is added through the first reagent supply pipe 25 at a rate of 12 mg / L. Subsequently, the ash solution enters the flocculation sedimentation tank 206. Ferric sulfate, a second reagent, is added through the second reagent supply pipe 26 at a rate of 120 mg / L.

[0143] The dust-laden liquid from oxidation tank 203, heavy metal removal tank 205, and flocculation sedimentation tank 206 is mixed and pumped to settling tank 207 to remove large suspended particles. The resulting clear liquid enters fine filter 208 for further liquid-solid separation, removing small precipitates and yielding a clear solution. Precision filtration uses a metal filter cartridge, and the suspended solids (SS) in the filtrate are 35 mg / L. The clear solution then enters denitrification tank 209, where it reacts with sodium hypochlorite solution supplied from denitrifying agent supply pipe 27 to remove ammonia nitrogen from the liquid phase. The addition rate of 10 wt% sodium hypochlorite is 71 L / h. The purified liquid then enters regulating tank 210, where a small amount of acid is added via regulating agent supply pipe 28 to adjust the pH to approximately 7, meeting the downstream unit's purified liquid receiving standards before discharge.

[0144] The final results for each pollutant indicator are shown in Table 4.

[0145] Table 4. Pollutant Indicators in Dissolving Tank, Oxidation Tank, Fine Filter, Denitrification Tank, and Purified Liquid

[0146] Logistics Name Dissolver tank outlet water Oxidation tank effluent Fine filter effluent Denitrification tank effluent Purification liquid <![CDATA[Flow rate m 3 / L]]> 45.8 45.8 45 45 45 <![CDATA[COD cr mg / L]]> 456 40 31 31 31 BOD mg / L 30 Not detected Not detected Not detected Not detected ammonia nitrogen mg / L 294 294 294 6 6 SS mg / L 296 296 5 5 5 pH 2.5 2.5 8 8.4 7.1

[0147] The above description, based on the preferred embodiments of this utility model, provides inspiration. Those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification but must be determined according to the claims.

Claims

1. A furnace ash acidic water treatment system, characterized in that: It includes an ash conveying mechanism, a processing mechanism connected downstream of the ash conveying mechanism, and an intelligent control system; the processing mechanism is also connected to an acidic water source for the synergistic treatment of acidic water and ash; the intelligent control system is connected to the ash conveying mechanism and the processing mechanism to form a control and regulation loop that collects, stores, calculates, and regulates the output.

2. The acidic wastewater treatment system for furnace ash according to claim 1, characterized in that: The furnace ash conveying mechanism includes a dust collector ash hopper, a first automatic unloader, a furnace ash storage hopper, and a second automatic unloader connected in sequence, and is connected to the processing mechanism via a furnace ash conveying pipeline.

3. The furnace ash acidic water treatment system according to claim 2, characterized in that: The processing unit includes a furnace ash dissolving tank, an oxidation tank, a heavy metal removal tank, a flocculation sedimentation tank, a fine filter, a denitrification tank, and a regulating tank, connected sequentially along the slurry flow direction; it also includes sludge drying equipment for receiving sludge from each unit; wherein, the furnace ash dissolving tank is connected downstream of the furnace ash conveying pipeline; the furnace ash dissolving tank is equipped with an acidic water supply pipe and a first alkali solution supply pipe, and the pH in the furnace ash dissolving tank is adjusted by controlling the ratio of acidic water and furnace ash entering the furnace ash dissolving tank.

4. The acidic wastewater treatment system for furnace ash according to claim 3, characterized in that: The oxidation tank is equipped with an oxidant supply pipe for removing COD from furnace ash and acidic water; the heavy metal removal tank is equipped with a second alkali supply pipe and a first reagent supply pipe for adjusting the pH of the liquid in the heavy metal removal tank, while simultaneously precipitating and removing heavy metals and forming suspended solids; the flocculation sedimentation tank is connected to a second reagent feed pipe for further particle aggregation; the dust-laden liquid in the oxidation tank and the heavy metal removal tank is mixed through pipelines and then sent to the settling tank; The fine filter is used to filter and obtain a clear solution; the denitrification tank is equipped with a denitrification agent supply pipe to remove ammonia nitrogen present in the feed liquid; the sludge drying equipment is connected to the bottom of the settling tank and the bottom of the fine filter through pipes respectively; the regulating tank is equipped with a regulating agent supply pipe to adjust the acidity and alkalinity of the outlet purified liquid.

5. The furnace ash acidic water treatment system according to claim 3, characterized in that: The furnace ash dissolution box, oxidation box, heavy metal removal box and denitrification box are all equipped with gas phase pipelines. The gas phase is collected through the pipelines and enters the tail gas filtration equipment to the tail gas treatment system.

6. The acidic wastewater treatment system for furnace ash according to claim 4, characterized in that: The intelligent control system includes a data acquisition and storage module, a data calculation and processing module, an intelligent control module, and a historical data storage module; The input end of the data acquisition and storage module is connected to the ash conveying mechanism and the processing mechanism, and is used to collect process parameters and parameter settings for data processing and storage. The input end of the data calculation and processing module is connected to the output end of the data acquisition and storage module, so that the process parameters and parameter settings are processed and stored in the data acquisition and storage module and then transmitted to the data calculation and processing module for data calculation and processing. The input end of the historical data storage module is connected to the output end of the data acquisition and storage module, and is used to store historical data within a certain period of time; The input terminal of the intelligent control module is connected to the output terminals of the data calculation and processing module and the historical data storage module, respectively. It is used to perform intelligent calculation and adjustment on real-time data and historical data to obtain the system adjustment output value, and return the system adjustment output value to each control and adjustment loop of the system.

7. The furnace ash acidic water treatment system according to claim 6, characterized in that, The control and regulation loop includes: The intelligent control system, together with the dust collector ash hopper level signal and the switch signal of the first automatic unloader, forms an intermittent ash feeding control loop, which is used to control the opening and closing of the first automatic unloader based on the ash storage hopper level. And / or, the intelligent control system, together with the flow signal of the acidic water supply pipe and the frequency signal of the regulating valve and the second automatic unloader, forms an automatic acidic water feeding control loop, which is used to control the second automatic unloader to control the furnace ash to enter the furnace ash dissolution box at a certain frequency, and to control the flow rate and the opening degree of the regulating valve on the acidic water supply pipe.

8. The furnace ash acidic water treatment system according to claim 6, characterized in that, The control and regulation loop includes: The intelligent control system, together with the pH signal of the inlet liquid in the oxidation box and the regulating valve of the first alkali supply pipe, forms a pH regulation loop for the ash dissolution box. This loop is used to control the flow rate and valve opening of the first alkali supply pipe and to regulate the pH in the ash dissolution box. And / or, the intelligent control system, together with the control valve and flow meter signals of the oxidant supply pipe and the COD detection signal of the outlet liquid of the oxidation tank, forms an oxidant feed control loop, which is used to control the COD of the liquid after the oxidation tank by adjusting the amount of oxidant and the opening of the regulating valve.

9. The furnace ash acidic water treatment system according to claim 6, characterized in that, The control and regulation loop includes: The intelligent control system forms a pH regulation loop with the pH signal of the liquid in the heavy metal removal tank, the flow rate of the second alkali supply pipe, and the opening signal of the regulating valve. The pH of the liquid in the heavy metal removal tank is adjusted by controlling the pH of the liquid in the heavy metal removal tank, the flow rate of the second alkali supply pipe, and the opening of the regulating valve. And / or, the intelligent control system forms an automatic dosing control loop with the inlet liquid flow signal of the heavy metal removal box and the flow meters and corresponding regulating valves of the first and second reagent supply pipes; And / or, the intelligent control system, together with the suspended solids detector signal at the outlet of the fine filter and the backwash controller in the fine filter, forms a suspended solids regulation loop to control the backwashing program in the fine filter to be activated when the suspended solids at the outlet of the fine filter exceed the standard. And / or, the intelligent control system, together with the ammonia nitrogen detector signal of the feed liquid after the denitrification tank and the flow rate and regulating valve opening signal on the denitrifying agent supply pipe, forms a denitrifying agent control loop, which is used to control the opening of the regulating valve on the denitrifying agent supply pipe according to the ammonia nitrogen content after the denitrification tank; And / or, the intelligent control system, together with the pH detector signal of the feed liquid after the regulating tank and the regulating valve on the regulating valve on the regulating valve, forms a regulating agent feed control loop, which is used to regulate the pH of the purified liquid by controlling the opening of the valve on the regulating agent supply pipe according to the pH of the purified liquid outlet.

10. The furnace ash acidic water treatment system according to claim 6, characterized in that, The intelligent control system also includes a human-machine interface for personnel to visually monitor and operate the system, remotely access and control it, and restrict information security operations.

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