Carbide slag oxidation-cyclone coupling pretreatment system for coal-fired power plant

Abstract

The utility model discloses a carbide slag oxidation-cyclone coupling pretreatment system for a coal-fired power plant. The carbide slag oxidation-cyclone coupling pretreatment system comprises a material conveying device, a crushing and screening unit, a multi-stage impurity removal unit, a dewatering and drying unit, a finished product activating treatment module and a dust removal unit. After iron impurities are removed through magnetic separation, sulfide and phosphide are oxidized in a reaction tank by adopting hydrogen peroxide, and a hydrocyclone is combined for separation and precipitation; and after dehydration and drying, the activity of the carbide slag is improved by ultrasonic-assisted superfine grinding. The system integrates waste heat recovery and cooling interlayer design, energy consumption is reduced, and material agglomeration is avoided. The device efficiently removes harmful components in the carbide slag, realizes resource utilization of the carbide slag, and is suitable for water softening and solid waste treatment in a coal-fired power plant.

Description

Technical Field

[0001] This application relates to the field of industrial solid waste treatment technology, and in particular to a pretreatment system for carbide slag oxidation-cyclone coupling in coal-fired power plants. Background Technology

[0002] Calcium carbide slag is the industrial waste residue produced by the hydrolysis of calcium carbide to produce acetylene. Its main component is calcium hydroxide (Ca(OH)2), and it also contains sulfides (S). 2- ), phosphide (P 3- Harmful impurities such as sulfides (S) in carbide slag 2- ) and phosphates (P 3- The residue of ) will reduce the desulfurization efficiency.

[0003] Currently, Chinese invention application CN118371512A discloses a method and system for pretreatment of calcium carbide slag from coal-fired power plants. This method employs natural sedimentation and mechanical separation to pretreat the calcium carbide slag, relying on high-temperature calcination and natural sedimentation. High-temperature calcination consumes a large amount of heat energy, increasing carbon emissions and operating costs; the natural sedimentation method has low treatment efficiency. Although adding modifiers can improve the activity of the calcium carbide slag, it may also introduce new impurities, and removal may be incomplete.

[0004] Chinese invention application CN118344036A discloses a purification and processing system for desulfurizing agent of carbide slag slurry. It uses a centrifugal filter or plate and frame filter to separate the carbide slag slurry. Although the pretreatment process is a physical process and does not require complex chemical reactions, it can only remove surface impurities and cannot deeply remove sulfides and phosphides in carbide slag. Utility Model Content

[0005] To address the aforementioned issues, this application provides a pretreatment system for carbide slag oxidation-cyclone coupling in coal-fired power plants. This system can efficiently remove harmful impurities such as sulfides and phosphides from carbide slag, reduce moisture content, and enhance the activity of carbide slag, thus providing a foundation for its resource utilization.

[0006] To achieve the objectives of this application, the following technical solution is provided:

[0007] This application provides a pretreatment system for carbide slag oxidation-cyclone coupling in a coal-fired power plant, comprising a material conveying device, a crushing and screening unit, a multi-stage impurity removal unit, a dewatering and drying unit, a finished product activation treatment module, and a dust removal unit connected in sequence.

[0008] The material transport device is a belt conveyor, whose discharge port is connected to the feed port of the crushing and screening unit;

[0009] The crushing and screening unit includes a crusher, a vibrating screen and a magnetic separator connected in sequence. The screen mesh size of the vibrating screen is 5mm, and the magnetic separator is located at the discharge port of the vibrating screen.

[0010] The multi-stage impurity removal unit includes a reaction tank, a stirrer, a metering pump, and a hydrocyclone. The inlet of the reaction tank is connected to the outlet of the magnetic separator via a screw pump. The metering pump is used to add hydrogen peroxide to the reaction tank. The inlet of the hydrocyclone is connected to the outlet of the reaction tank via a slurry conveying pump.

[0011] The dehydration and drying unit includes a plate and frame filter press and a rotary dryer. The feed inlet of the plate and frame filter press is connected to the overflow port of the hydrocyclone, and the feed inlet of the rotary dryer is connected to the discharge port of the plate and frame filter press.

[0012] The finished product activation treatment module includes an ultrafine grinder and an ultrasonic vibration device integrated in its grinding chamber. The feed inlet of the ultrafine grinder is connected to the discharge outlet of the rotary dryer and is provided with a sodium polyacrylate addition port.

[0013] The dust removal unit is a bag filter, which is connected to the discharge port of the ultrafine grinding mill.

[0014] In one possible implementation, the reaction tank is equipped with a pH sensor, and the metering pump dynamically adjusts the amount of hydrogen peroxide added based on the feedback signal from the pH sensor.

[0015] In one possible implementation, the rotary dryer is provided with an inert gas inlet and a waste heat recovery pipeline, which is connected to the hot air outlet of the rotary dryer for recovering heat from the exhaust gas.

[0016] In one possible implementation, the outer wall of the grinding chamber of the ultrafine grinder is provided with a cooling jacket, and the cooling medium circulates through the jacket to control the grinding temperature. The frequency of the ultrasonic vibration device is 20-40kHz.

[0017] In one possible implementation, the underflow port of the hydrocyclone is connected to an impurity collection tank for separating and discharging calcium sulfate and calcium phosphate precipitates.

[0018] The pretreatment system for carbide slag oxidation-cyclone coupling provided in this application can efficiently remove impurities from carbide slag and reduce its moisture content, providing the necessary conditions for the resource utilization of carbide slag. Attached Figure Description

[0019] The accompanying drawings are provided to further understand this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof.

[0020] Figure 1 A schematic diagram of the process flow provided for an embodiment of this application;

[0021] Figure 2 This is a schematic diagram of the apparatus provided in an embodiment of this application.

[0022] In the diagram: 1. Belt conveyor; 2. Crusher; 3. Vibrating screen; 4. Magnetic separator; 5. Reaction tank; 6. Agitator; 7. Slurry transfer pump; 8. Hydrocyclone; 9. Impurity collection tank; 10. Plate and frame filter press; 11. Rotary dryer; 12. Ultrafine grinder; 13. Ultrasonic vibration device; 14. Inert gas inlet; 15. Waste heat recovery pipeline; 16. Cooling jacket; 17. Bag filter. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this application, unless otherwise stated, "multiple" means two or more.

[0025] Example 1

[0026] Figure 1-2 An embodiment of this application provides a pretreatment system for the oxidation-cyclone coupling of calcium carbide slag in a coal-fired power plant, comprising a material conveying device, a crushing and screening unit, a multi-stage impurity removal unit, a dewatering and drying unit, a finished product activation treatment module, and a dust removal unit connected in sequence.

[0027] The material transport device is a belt conveyor 1, whose outlet is connected to the inlet of the crushing and screening unit;

[0028] The crushing and screening unit includes a crusher 2, a vibrating screen 3 and a magnetic separator 4 connected in sequence. The screen mesh size of the vibrating screen 3 is 5mm, and the magnetic separator 4 is located at the discharge port of the vibrating screen 3.

[0029] The multi-stage impurity removal unit includes a reaction tank 5, a stirrer 6, a metering pump, and a hydrocyclone 8. The inlet of the reaction tank 5 is connected to the outlet of the magnetic separator 4 via a screw pump. The metering pump is used to add hydrogen peroxide to the reaction tank 5. The inlet of the hydrocyclone 8 is connected to the outlet of the reaction tank 5 via a slurry transfer pump 7. A pH sensor is installed in the reaction tank 5, and the metering pump dynamically adjusts the amount of hydrogen peroxide added based on the feedback signal from the pH sensor.

[0030] The dehydration and drying unit includes a plate and frame filter press 10 and a rotary dryer 11. The feed inlet of the plate and frame filter press 10 is connected to the overflow port of the hydrocyclone 8, and the feed inlet of the rotary dryer 11 is connected to the discharge port of the plate and frame filter press 10. The rotary dryer 11 is provided with an inert gas inlet 14 and a waste heat recovery pipeline 15. The waste heat recovery pipeline 15 is connected to the hot air outlet of the rotary dryer 11 for recovering the heat of the exhaust gas.

[0031] The finished product activation treatment module includes an ultrafine grinder 12 and an ultrasonic vibration device 13 integrated in its grinding chamber. The feed port of the ultrafine grinder 12 is connected to the discharge port of the rotary dryer 11, and is provided with a sodium polyacrylate addition port.

[0032] The dust removal unit is a bag filter 17, which is connected to the discharge port of the ultrafine grinding mill 12;

[0033] The outer wall of the grinding chamber of the ultrafine grinding machine 12 is provided with a cooling jacket 16, and the cooling medium circulates through the jacket to control the grinding temperature; the frequency of the ultrasonic vibration device 13 is 20-40kHz.

[0034] The underflow port of the hydrocyclone 8 is connected to the impurity collection tank 9, which is used to separate and discharge calcium sulfate and calcium phosphate precipitates.

[0035] In one possible implementation, carbide slag powder is prepared into a slurry in reaction tank 5 and stirred evenly at a stirring speed of 200-400 r / min for 15-20 min. Then, by adding an excess of 10-20% H2O2, the sulfur in the carbide slag is removed. 2- P 3- Oxidized to SO4 2- and PO4 3- Finally, the slurry is injected into a hydrocyclone 8 to perform solid-liquid separation and particle classification based on centrifugal force and density differences, thereby separating the heavier calcium sulfate and calcium phosphate.

[0036] In one possible implementation, the primary slurry flowing out of the overflow port of the hydrocyclone 8 is filtered by plate and frame filtration to form carbide slag cake and the moisture content of the carbide slag cake is controlled to be ≤30%.

[0037] In one possible implementation, the carbide slag cake that has been filtered is dried until its moisture content is ≤5%, and an inert gas is introduced and a waste heat recovery pipeline 15 is connected to reduce energy consumption. At the same time, the drying temperature is controlled at 200-500°C to prevent the activity of calcium hydroxide from decreasing.

[0038] In one possible implementation, 0.1-0.5% sodium polyacrylate is added to the dried carbide slag cake and further pulverized by an ultrafine grinder 12, and particle agglomeration during grinding is reduced by an ultrasonic vibration device 13 to improve the activity of carbide slag.

[0039] In one possible implementation, the bag filter 17 is connected to the discharge port of the ultrafine grinder 12 to collect the carbide slag dust and avoid causing air pollution.

[0040] Example 2

[0041] Figure 1-2 The present application provides a coal-fired power plant calcium carbide slag oxidation-cyclone coupling pretreatment system. The calcium carbide slag is conveyed to the crusher 2 by the belt conveyor 1, and the calcium carbide slag is crushed into powder with a pore size ≤5mm. Then it is filtered through the 18-50 mesh vibrating screen 3. The filtered powder is then filtered through the magnetic separator 4 to remove iron filings, forming calcium carbide slag pre-powder.

[0042] The calcium carbide slag powder is transported to reaction tank 5 via a screw pump. The calcium carbide slag is mixed with water to prepare a suspension with a solid content of 20%, and stirred evenly using a stirrer 6 at a speed of 200 r / min for 15 min. Then, 10-20% excess H2O2 is added to oxidize the sulfides and phosphides in the calcium carbide slag into sulfate and phosphate ions, which combine with calcium ions to form calcium sulfate and calcium phosphate. Finally, the calcium carbide slag slurry is transported to the feed inlet of hydrocyclone 8 by slurry pump 7. Calcium hydroxide is discharged from the overflow port using the centrifugal sedimentation principle, while other high-density impurities are discharged from the bottom outlet. The primary slurry flowing out of the overflow port is then filtered through a plate and frame filter press. The carbide slag cake is pressed and filtered by machine 10 to form a sludge cake with a moisture content of ≤30%. The filtered carbide slag cake is dried until its moisture content is ≤5%, and inert gas is introduced and a waste heat recovery pipeline 15 is connected to reduce energy consumption. At the same time, the drying temperature is controlled at 200-500℃ to prevent the activity of calcium hydroxide from decreasing. 0.1-0.5% sodium polyacrylate is added to the dried carbide slag cake and further pulverized by ultrafine grinding mill 12. The ultrasonic vibration device 13 is used to reduce particle agglomeration during the grinding process and improve the activity of carbide slag. A bag filter 17 is connected to the discharge port of ultrafine grinding mill 12 to collect carbide slag dust and avoid air pollution.

[0043] The calcium hydroxide product obtained above has a purity of 93.2%, with the Fe2O3 content reduced to 0.36%, the MgO content reduced to 0.17%, the SiO2 content reduced to 3.09%, and the Al2O3 content reduced to 1.31%.

[0044] The beneficial effects of adopting the embodiments of this application are as follows: This application uses an oxidation-precipitation method to separate the solid and liquid components of calcium carbide slag slurry, which can efficiently remove more than 95% of impurities such as sulfides and phosphides that affect the softening and hardening of calcium carbide slag; hydrogen peroxide, as a common green oxidant, significantly reduces the environmental toxicity of calcium carbide slag by converting sulfides and phosphides into stable sulfates and phosphates; the waste heat recovery system effectively utilizes the heat energy of the drying tail gas for preheating, reducing coal consumption by 30-50%, bringing significant economic benefits to enterprises. Through the synergistic effect of multiple links, this application achieves the harmlessness, reduction, and resource utilization of calcium carbide slag, combining environmental, economic, and technical benefits, and providing a scalable green solution for solid waste treatment in coal-fired power plants.

[0045] In the embodiments provided in this application, it should be understood that the disclosed systems, modules, and methods can be implemented in other ways. For example, the module embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, or indirect coupling or communication connection between modules or units, and may be electrical, mechanical, or other forms.

[0046] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. This application is not limited to the exact structures described above and illustrated in the accompanying drawings, and it should not be considered that the specific implementation of this application is limited to these descriptions. For those skilled in the art, various changes and modifications made without departing from the concept of this application should be considered to fall within the protection scope of this application.

Claims

1. A pretreatment system for carbide slag oxidation-cyclone coupling in coal-fired power plants, characterized in that, It includes a material conveying device, a crushing and screening unit, a multi-stage impurity removal unit, a dehydration and drying unit, a finished product activation treatment module, and a dust removal unit connected in sequence; The material transport device is a belt conveyor, whose discharge port is connected to the feed port of the crushing and screening unit; The crushing and screening unit includes a crusher, a vibrating screen and a magnetic separator connected in sequence. The screen mesh size of the vibrating screen is 5mm, and the magnetic separator is located at the discharge port of the vibrating screen. The multi-stage impurity removal unit includes a reaction tank, a stirrer, a metering pump, and a hydrocyclone. The inlet of the reaction tank is connected to the outlet of the magnetic separator via a screw pump. The metering pump is used to add hydrogen peroxide to the reaction tank. The inlet of the hydrocyclone is connected to the outlet of the reaction tank via a slurry conveying pump. The dehydration and drying unit includes a plate and frame filter press and a rotary dryer. The feed inlet of the plate and frame filter press is connected to the overflow port of the hydrocyclone, and the feed inlet of the rotary dryer is connected to the discharge port of the plate and frame filter press. The finished product activation treatment module includes an ultrafine grinder and an ultrasonic vibration device integrated in its grinding chamber. The feed inlet of the ultrafine grinder is connected to the discharge outlet of the rotary dryer and is provided with a sodium polyacrylate addition port. The dust removal unit is a bag filter, which is connected to the discharge port of the ultrafine grinding mill.

2. The pretreatment system for carbide slag oxidation-cyclone coupling in a coal-fired power plant according to claim 1, characterized in that, The reaction tank is equipped with a pH sensor, and the metering pump dynamically adjusts the amount of hydrogen peroxide added based on the feedback signal from the pH sensor.

3. The pretreatment system for carbide slag oxidation-cyclone coupling in a coal-fired power plant according to claim 1, characterized in that, The rotary dryer is equipped with an inert gas inlet and a waste heat recovery pipeline. The waste heat recovery pipeline is connected to the hot air outlet of the rotary dryer for recovering heat from the exhaust gas.

4. The pretreatment system for carbide slag oxidation-cyclone coupling in a coal-fired power plant according to claim 1, characterized in that, The grinding chamber of the ultrafine grinding machine is provided with a cooling jacket on its outer wall. The cooling medium circulates through the jacket to control the grinding temperature. The frequency of the ultrasonic vibration device is 20-40kHz.

5. The pretreatment system for carbide slag oxidation-cyclone coupling in a coal-fired power plant according to claim 1, characterized in that, The underflow port of the hydrocyclone is connected to an impurity collection tank, which is used to separate and discharge calcium sulfate and calcium phosphate precipitates.

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