Dechlorination upgrading system for preparing alpha-type semi-hydrated gypsum from industrial by-product gypsum and control method

Abstract

The invention discloses a dechlorination upgrading system for preparing alpha-type semi-hydrated gypsum from industrial byproduct gypsum and a control method, and belongs to the technical field of alpha-semi-hydrated gypsum production. In the system, a hydrothermal reaction system is communicated with a mechanical extrusion dehydration device through a supercharging power device, and the mechanical extrusion dehydration device, a high-temperature drying device and a post-treatment system are sequentially communicated; a hot side inlet of the heat exchanger is communicated with the mechanical extrusion dehydration device and the high-temperature drying device, a cold side inlet of the heat exchanger is communicated with the industrial water inlet, a cold side outlet of the heat exchanger is communicated with the hydrothermal reaction system, and the circulating water treatment unit is communicated with the mechanical extrusion dehydration device and the high-temperature drying device. The circulating water treatment unit is communicated with the sedimentation tank through a circulating water pump; the sedimentation tank is converged with a hot side outlet of the heat exchanger and then is communicated with the hydrothermal reaction system and the tail water treatment unit; and the steam heat supply system is communicated with the hydrothermal reaction system and the high-temperature drying device. The system can operate stably, and the yield of finished gypsum is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of alpha hemihydrate gypsum production, and more specifically to a dechlorination and quality-improving system and a control method for preparing alpha hemihydrate gypsum from industrial by-product gypsum. Background Art

[0002] Industrial by-product gypsum is a by-product of wet flue gas desulfurization technology such as boiler combustion systems. Its main component is calcium sulfate dihydrate (CaSO4·2H2O). Industrial by-product gypsum belongs to the category of solid waste, and its disposal method is generally harmless landfill treatment. However, this method does not fully utilize the high concentration of calcium sulfate dihydrate in desulfurized gypsum, and improper disposal will cause the leakage of trace elements in industrial by-product gypsum, endangering the safety of soil and water resources, and having an adverse effect on the animals and plants around the landfill site. Therefore, the resource utilization of desulfurized gypsum, a solid waste, has a positive significance for environmental protection, and is also conducive to the improvement of its economic value.

[0003] Since industrial by-product gypsum contains a large amount of calcium sulfate dihydrate (CaSO4·0.5H2O), preparing it into calcium sulfate hemihydrate is a common resource utilization method. However, the current process is mainly used to produce β-hemihydrate gypsum (β-CaSO4·0.5H2O), which is mostly used in the construction field. The economic value of the product is low, and the large amount of chloride ions contained in the industrial by-product gypsum cannot be effectively removed, resulting in insufficient product strength. Although there are some process methods aimed at producing α-hemihydrate gypsum, they are mainly based on autoclaving, which is also unable to effectively remove chloride ions in the product, resulting in poor water absorption, whiteness, and strength of the product, and cannot meet the industrial needs of continuous production. In addition, in response to the problem of high chloride ion content in gypsum products, the current method is mostly water washing, which consumes a lot of water and cannot remove the chloride ions contained in the lattice, so the efficiency is low.

[0004] The hydrothermal treatment method prepares industrial by-product gypsum into a slurry and places it in a high-temperature and high-pressure water environment for reaction. It can remove harmful substances such as chloride ions while preparing α-hemihydrate gypsum. The hydrothermal method for treating industrial by-product gypsum has excellent development prospects. However, in actual industrial operation, the hydrothermal method needs to ensure the stability of the temperature during the hydrothermal reaction, regulate the removal process of chloride ions, and improve the economy of the system through water circulation, pressure energy reuse, and heat recovery. At the same time, if there are operational problems in the hydrothermal reaction process system, the system is out of the optimal operating range, which may cause the finished α-hemihydrate gypsum to be unqualified, the chloride ions to be incompletely removed, the system energy consumption to increase, and the economy to decrease. Therefore, in order to improve the stability and economic operation of the hydrothermal method for treating industrial by-product gypsum, a complete set of control strategies is urgently needed to adapt to different industrial by-product gypsum raw materials, ensure the yield of finished gypsum, and deal with possible operating condition fluctuations and safety risks during operation. Summary of the invention

[0005] In view of the above problems, the present invention provides a dechlorination and upgrading system and control method for preparing α-type hemihydrate gypsum from industrial by-product gypsum. The system of the present invention can operate stably and ensure the yield rate of the finished gypsum.

[0006] The object of the present invention is to provide a dechlorination and upgrading system for preparing α-type hemihydrate gypsum from industrial by-product gypsum, comprising a hydrothermal reaction system, a water reuse system, a steam heating system, a dehydration system and a post-processing system.

[0007] The dehydration system includes a booster power device, a mechanical extrusion dehydration device and a high-temperature drying device. The outlet of the hydrothermal reaction system is connected to the inlet of the mechanical extrusion dehydration device through the booster power device, the outlet of the mechanical extrusion dehydration device is connected to the material inlet of the high-temperature drying device, and the material outlet of the high-temperature drying device is connected to the post-processing system; the moisture content of α hemihydrate gypsum at the material outlet of the high-temperature drying device is regulated by the dehydration system to meet the requirements.

[0008] The water reuse system includes a second reagent tank, a circulating water treatment unit, a circulating water pump, a sedimentation tank, a heat exchanger and a tail water treatment unit, wherein the hot side inlet of the heat exchanger is connected to the water outlet of the mechanical extrusion dehydration device and the high-temperature drying device, the cold side inlet of the heat exchanger is connected to the industrial water inlet, the cold side outlet of the heat exchanger is connected to the water inlet of the hydrothermal reaction system, the inlet of the circulating water treatment unit is connected to the water outlet of the mechanical extrusion dehydration device and the high-temperature drying device, the outlet of the circulating water treatment unit is connected to the inlet of the sedimentation tank through the circulating water pump, the outlet of the sedimentation tank is combined with the hot side outlet of the heat exchanger and is divided into a first mixed outlet and a second mixed outlet, the first mixed outlet is connected to the water inlet of the hydrothermal reaction system, and the second mixed outlet is connected to the tail water treatment unit; if the chloride ions in the water removed by the mechanical extrusion dehydration device and the high-temperature drying device meet the requirements, the water enters the circulating water treatment unit for reuse, and if the chloride ions in the water discharged from the sedimentation tank meet the requirements, the water enters the hydrothermal reaction system for reuse.

[0009] The steam heating system is communicated with the hydrothermal reaction system and the high-temperature drying device.

[0010] In a preferred embodiment of the present invention, the hydrothermal reaction system includes a raw material supply device, a mixing device, a slurry pump, a hydrothermal reaction device, a distributor, a first reagent tank, and a reagent pump. The outlet of the raw material supply device is respectively connected to the material inlet of the mixing device and the raw material inlet of the circulating water treatment unit. The distributor is arranged between the raw material supply device and the raw material inlet of the circulating water treatment unit. The outlet of the mixing device is connected to the inlet of the hydrothermal reaction device after passing through the slurry pump. The outlet of the first reagent tank is respectively connected to the crystal control agent inlet of the mixing device and the first reagent inlet of the circulating water treatment unit.

[0011] In a preferred embodiment of the present invention, the steam heating system includes a heating unit, a first outlet of the heating unit is connected to the steam inlet of the hydrothermal reaction device, and a second outlet of the heating unit is connected to the steam heating inlet of the high-temperature drying device.

[0012] In a preferred embodiment of the present invention, a feeder motor and a first flow detection instrument are provided between the raw material supply device and the mixing device; and a second flow detection instrument is provided between the medicine pump and the mixing device.

[0013] In a preferred embodiment of the present invention, a first temperature detection instrument is provided at the inlet of the hydrothermal reaction device; and a second temperature detection instrument is provided at the outlet of the hydrothermal reaction device.

[0014] In a preferred embodiment of the present invention, a moisture content detection instrument is provided between the high-temperature drying device and the post-processing device; a bypass solenoid valve is provided on the pipeline connecting the mechanical extrusion dehydration device and the hydrothermal reaction device; a first circulating water solenoid valve is provided on the pipeline connected to the circulating water treatment unit after the water outlets of the mechanical extrusion dehydration device and the high-temperature drying device are combined; a second circulating water solenoid valve is provided on the pipeline between the heat exchanger after the water outlets of the mechanical extrusion dehydration device and the high-temperature drying device are combined; a first chloride ion detection instrument is provided on the pipeline connected to the water outlets of the mechanical extrusion dehydration device and the high-temperature drying device; a second chloride ion detection instrument is provided on the outlet pipeline of the sedimentation tank; a pH value detection instrument is included in the circulating water treatment unit; and the sedimentation tank includes a Ca 2+ Ion content detection instrument; a fourth circulating water solenoid valve is provided on the pipeline of the tail water treatment unit and the second mixed outlet after the outlet of the sedimentation tank and the hot side outlet of the heat exchanger are merged, and a third circulating water solenoid valve is provided on the pipeline of the mixing device and the first mixed outlet after the outlet of the sedimentation tank and the hot side outlet of the heat exchanger are merged.

[0015] In a preferred embodiment of the present invention, a second reagent tank solenoid valve is provided between the circulating water treatment unit and the second reagent tank, and a sewage discharge solenoid valve is provided on the sedimentation tank.

[0016] In a preferred embodiment of the present invention, an industrial water solenoid valve is provided between the cold side inlet of the heat exchanger and the industrial water inlet.

[0017] In a preferred embodiment of the present invention, a first steam solenoid valve is provided on the steam outlet main pipeline of the heating unit; and a second steam solenoid valve is provided between the first outlet of the heating unit and the hydrothermal reaction device.

[0018] The second object of the present invention is to provide a control method for the dechlorination and upgrading system of the above-mentioned industrial by-product gypsum for preparing α-hemihydrate gypsum, comprising the following steps: When the system starts, water is injected into the mixing device through the industrial water solenoid valve. When the material level in the mixing device reaches the L1 value, the slurry pump is turned on to inject water into the hydrothermal reaction device. When the hydrothermal reaction device is full of water, the industrial water solenoid valve is closed to complete the water injection.

[0019] The value of L1 is 1 / 3~2 / 3 of the internal height of the mixing device.

[0020] Open the bypass solenoid valve, open the heating unit, the first steam solenoid valve and the second steam solenoid valve, heat the water in the hydrothermal reaction device until the temperature reaches T1 value, the pressure reaches P1 value, and the temperature in the high-temperature drying device reaches T2 value, completing the temperature and pressure increase process of the hydrothermal reaction.

[0021] The value of T1 is 90℃~200℃, the value of T2 is 60℃~200℃, and the value of P1 is 0.1MPa~15MPa.

[0022] Turn on the feeder motor, the reagent pump, the first circulating water solenoid valve and the third circulating water solenoid valve, adjust the fourth circulating water solenoid valve to the K value, turn on the circulating water pump, turn on the high-temperature drying device and the post-processing device, and complete the system startup process.

[0023] The value of K is 0~50% of the valve opening.

[0024] The first flow detection instrument controls the feeder motor power in a proportional constraint relationship with the third circulating water solenoid valve and the industrial water solenoid valve, so that the moisture content of the desulfurized gypsum slurry prepared by the preparation device is the FW1 value; the first flow detection instrument controls the feeder motor power in a proportional constraint relationship with the agent pump power controlled by the second flow detection instrument, so that the amount of crystal control agent added is the A1 value of the desulfurized gypsum flow rate.

[0025] The value of FW1 is 30wt%~70wt%, and the value of A1 is 0.01wt%~10wt%.

[0026] If the pressure in the hydrothermal reaction device is low, close the bypass solenoid valve and start the booster pump to ensure that the slurry has enough pressure energy to drive the mechanical extrusion dehydration device to rotate and dehydrate. If the pressure in the hydrothermal reaction device returns to P1, open the bypass solenoid valve and close the booster power device.

[0027] The reaction temperature of the hydrothermal reaction device is determined by comparing the temperature measurement values ​​of the first temperature detection instrument and the second temperature detection instrument. If the maximum value of the reaction temperature of the hydrothermal reaction device is lower than T1, the openings of the first steam solenoid valve and the second steam solenoid valve are increased so that the maximum temperature in the hydrothermal reaction device is higher than T1; if the minimum value of the reaction temperature of the hydrothermal reaction device is higher than T1, the openings of the first steam solenoid valve and the second steam solenoid valve are reduced so that the minimum temperature in the hydrothermal reaction device is lower than T1.

[0028] If the value of the moisture content detection instrument is greater than the FW2 value, increase the opening of the first steam solenoid valve, increase the power of the heating unit, and increase the power of the feeder motor; if the value of the moisture content detection instrument is less than the FW2 value, reduce the opening of the first steam solenoid valve, reduce the power of the heating unit, and reduce the power of the feeder motor.

[0029] The value of FW2 is 0.1wt%~10wt%.

[0030] If the chlorine content of the first chloride ion content detection instrument is greater than the Cl1 value, open the industrial water solenoid valve and the second circulating water solenoid valve, close the first circulating water solenoid valve and the third circulating water solenoid valve, and adjust the fourth circulating water solenoid valve to the maximum opening; if the chlorine content of the first chloride ion content detection instrument is lower than the Cl1 value, open the first circulating water solenoid valve and the third circulating water solenoid valve, close the industrial water solenoid valve and the second circulating water solenoid valve, and adjust the fourth circulating water solenoid valve to the third circulating water solenoid valve to satisfy the proportional constraint relationship.

[0031] The Cl1 value is 200ppm~20000ppm.

[0032] If the pH value detection instrument detects that the pH value in the circulating water treatment device is greater than the pH1 value, the solenoid valve of the second reagent tank is opened, and acidic substances such as sulfuric acid are added to lower the pH value. If the pH value detection instrument detects that the pH value in the circulating water treatment device is less than the pH2 value, Ca(OH)2 is added to increase the pH value.

[0033] The pH1 value is 4-10, and the pH2 value is 3-9.

[0034] If Ca 2+ The supernatant Ca detected by the ion content detection instrument 2+ If the concentration is lower than the target value Ca1, the distributor is opened to add the raw material in the raw material supply device to the circulating water treatment device.

[0035] The Ca1 value is 20ppm~20000ppm.

[0036] If the second chloride ion detection instrument detects that the chloride ion content is higher than the target value Cl2, the opening of the reagent solenoid valve is increased.

[0037] The Cl2 value is 200ppm~20000ppm.

[0038] After the reaction is finished, the feeder motor and the reagent pump are turned off. After the slurry in the hydrothermal reaction device has finished reacting, the second steam solenoid valve is closed to cool down and reduce the pressure of the hydrothermal reaction device.

[0039] After the high-temperature drying device has finished discharging the materials, the heating unit and the first steam solenoid valve are closed.

[0040] Close the third circulating water solenoid valve, the second reagent tank solenoid valve and the reagent solenoid valve, adjust the fourth circulating water solenoid valve, and close the slurry pump and circulating water pump.

[0041] After the post-processing device has finished processing the finished material, the post-processing device is closed.

[0042] After the tailwater treatment unit has finished treating the wastewater, shut down the tailwater treatment unit and close all valves that are not closed.

[0043] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention controls the moisture content of α-hemihydrate gypsum at the material outlet of the high-temperature drying device through a dehydration system to meet the requirements; the chloride ions in the water removed by the mechanical extrusion dehydration device and the high-temperature drying device meet the requirements and enter the circulating water treatment unit for repeated use; the chloride ions in the water discharged from the sedimentation tank meet the requirements and enter the hydrothermal reaction system for repeated use; through real-time monitoring of the chlorine content and moisture content and control of water circulation and steam supply, the stable operation of the process system for preparing α-hemihydrate gypsum from desulfurized gypsum by the hydrothermal method is achieved, ensuring that the finished α-hemihydrate gypsum meets the requirements of chlorine content, moisture content and purity, reducing the probability of abnormal operation of the system and improving the product yield.

[0044] 2. The present invention realizes accurate recycling of dry and removed water through a water reuse system. By efficiently dechlorinating the circulating water, the system's dependence on replenishing circulating water is reduced. New industrial water is only required when the chlorine content of the circulating water is too high, thereby improving the utilization efficiency of water resources. By monitoring and removing the chloride ion content of the circulating water and efficiently controlling and switching the circulating water / industrial water, it is ensured that the prepared slurry is always lower than the maximum critical value of the chlorine content of the hydrothermal reaction system.

[0045] 3. The present invention utilizes the pressure energy of the high-temperature and high-pressure slurry after the hydrothermal reaction to drive mechanical extrusion rotary dehydration and heat recycling, thereby realizing dual recovery of system temperature and pressure, and removing part of the moisture before high-temperature drying, thereby jointly reducing the energy consumption of the process system and improving economy.

[0046] 4. The present invention realizes stable and accurate heat supply and efficient heat recovery of the system through temperature detection of the reactor, moisture content detection of the dehydration system, and interlocking control of water and steam valves, ensures that the reaction temperature and concentration are always in a high reaction efficiency range, and ensures the stability of the drying temperature, effectively preventing the reverse transformation or complete dehydration of α-hemihydrate gypsum.

[0047] 5. According to the control method of the dechlorination and upgrading system for preparing α-hemihydrate gypsum from industrial by-product gypsum in the present invention, even if different raw materials are input, the operation strategy can be dynamically adjusted through the system control method so that the product meets the requirements and the system operates stably. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A schematic diagram of a dechlorination and upgrading system for preparing α-type hemihydrate gypsum from industrial by-product gypsum provided by the present invention.

[0049] Figure numerals: 1-heating unit; 2-raw material supply device; 3-blending device; 4-slurry pump; 5-hydrothermal reaction device; 6-boosting power device; 7-mechanical extrusion dehydration device; 8-high temperature drying device; 9-post-processing device; 10-second reagent tank; 11-circulating water treatment unit; 12-circulating water pump; 13-sedimentation tank; 14-heat exchanger; 15-distributor; 16-first reagent tank; 17-reagent pump; 18-tail water treatment unit; V01-first circulating water solenoid valve; V02-second circulating water solenoid valve; V03-second reagent tank solenoid valve; V04-sewage solenoid valve; V05-industrial water solenoid valve; V06-third circulating water solenoid valve; V07-fourth circulating water solenoid valve; V08-first reagent tank solenoid valve; V09-first steam solenoid valve; V10-second steam solenoid valve; V11-bypass solenoid valve; M01-feeder motor; F01-first flow detection instrument; F02-second flow detection instrument; T01-first temperature detection instrument; T02-second temperature detection instrument; W01-water content detection instrument; Cl01-first chloride ion content detection instrument; Cl02-second chloride ion content detection instrument; Ca01-Ca 2+ Ion content detection instrument; pH01-pH value detection instrument; R1-inlet for industrial by-product gypsum; R2-inlet for industrial water. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0053] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features; in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0054] The technical solution of the present invention is further described below.

[0055] Based on this, the present invention provides a dechlorination and quality improvement system and method for preparing α-hemihydrate gypsum from industrial by-product gypsum, which can realize the efficient conversion of desulfurized gypsum into α-hemihydrate gypsum, remove chloride ions, and ensure the stability of system operation and the yield rate of products, thereby improving the economic value of resource utilization of desulfurized gypsum.

[0056] Example 1 This embodiment provides a dechlorination and upgrading system for preparing α-type hemihydrate gypsum from industrial by-product gypsum, such as Figure 1 , Figure 1 The dotted lines in the figure refer to the paths of water and steam, and the solid lines refer to the paths of slurry. The dechlorination and upgrading system includes a hydrothermal reaction system, a water reuse system, a steam heating system, a dehydration system and a post-treatment system.

[0057] The hydrothermal reaction system includes a raw material supply device 2, a mixing device 3, a slurry pump 4, a hydrothermal reaction device 5, a distributor 15, a first reagent tank 16, and a reagent pump 17. The outlet of the raw material supply device 2 is respectively connected to the material inlet of the mixing device 3 and the raw material inlet of the circulating water treatment unit 11. The distributor 15 is arranged between the raw material supply device 2 and the raw material inlet of the circulating water treatment unit 11. The outlet of the mixing device 3 is connected to the inlet of the hydrothermal reaction device 5 after passing through the slurry pump 4. The outlet of the first reagent tank 16 is respectively connected to the crystal control agent inlet of the mixing device 3 and the first reagent inlet of the circulating water treatment unit 11.

[0058] Before the reaction, the industrial by-product gypsum in the raw material supply device 2 and the crystal control agent in the first reagent tank 16 are added to the preparation device 3 through the reagent pump 17. After the preparation is completed, they are added to the hydrothermal reaction device 5 through the slurry pump 4 for hydrothermal reaction. After the hydrothermal reaction is completed, the prepared product enters the dehydration system for dehydration treatment.

[0059] The dehydration system includes a booster power device 6, a mechanical extrusion dehydration device 7 and a high-temperature drying device 8. The product prepared by the hydrothermal reaction enters the mechanical extrusion dehydration device 7, the high-temperature drying device 8 and the post-processing device 9 in sequence; if the pressure of the hydrothermal reaction device 5 does not meet the standard value, it enters the mechanical extrusion dehydration device 7 through the booster power device 6. During the dehydration process, the finished slurry of the hydrothermal reaction device 5 is mechanically dehydrated in the mechanical extrusion dehydration device 7, and then the treated product enters the high-temperature drying device 8. The treated product enters the post-processing system for high-temperature dehydration.

[0060] The water reuse system includes a second reagent tank 10, a circulating water treatment unit 11, a circulating water pump 12, a sedimentation tank 13, a heat exchanger 14 and a tail water treatment unit 18. The hot side inlet of the heat exchanger 14 is connected to the water outlet of the mechanical extrusion dehydration device 7 and the water outlet of the high-temperature drying device 8, the cold side inlet of the heat exchanger 14 is connected to the industrial water inlet R2, the cold side outlet of the heat exchanger 14 is connected to the water inlet of the blending device 3, the inlet of the circulating water treatment unit 11 is connected to the water outlet of the mechanical extrusion dehydration device 7 and the high-temperature drying device 8, the outlet of the circulating water treatment unit 11 is connected to the inlet of the sedimentation tank 13 through the circulating water pump 12, the outlet of the sedimentation tank 13 is combined with the hot side outlet of the heat exchanger 14 and is divided into a first mixed outlet and a second mixed outlet, the first mixed outlet is connected to the water inlet of the blending device 3, and the second mixed outlet is connected to the tail water treatment unit 18.

[0061] During the operation of the water reuse system, the separated water in the mechanical extrusion device 7 and the dried condensed water in the high-temperature drying device 8 are detected as qualified by the first chloride ion content detection instrument Cl01, and then enter the circulating water treatment unit 11, in which the crystal control agent in the first reagent tank 16 and the pH adjuster in the second reagent tank 10 are added, and then the prepared circulating water passes through the circulating water pump 12 and enters the sedimentation tank 13, in which the chlorine-containing precipitate is removed, and the generated pure circulating water flows out from the outlet of the sedimentation tank 13, and after being detected as qualified by the second chloride ion content detection instrument Cl02, it enters the preparation device 3 from the first mixing outlet for slurry preparation. If the second chloride ion content detection instrument Cl02 fails to detect qualified, it is necessary to increase the amount of crystal control agent added to the circulating water treatment unit 11. The pure circulating water produced in the sedimentation tank 13 is added to the blending device 3, and the excess pure circulating water or circulating water with too high chloride ion content that cannot be reused enters the tail water treatment unit 18 from the second mixing outlet for water discharge.

[0062] After the separated water in the mechanical extrusion device 7 and the dried condensed water in the high-temperature drying device 8 are detected by the first chloride ion content detection instrument Cl01, if the chloride ion content does not meet the treatment requirements, the removed water enters the hot side inlet of the heat exchanger 14 to exchange heat with the newly-input industrial water. The industrial water enters the heat exchanger 14 from the industrial water inlet R2 and the cold side inlet of the heat exchanger 14 in turn, and the heat of the circulating water is recovered. The obtained hot industrial water enters the preparation device 3 from the cold side outlet of the heat exchanger 14 and the water inlet of the preparation device 3 for slurry preparation.

[0063] The steam heating system comprises a heating unit 1, a first outlet of the heating unit 1 being connected to a steam inlet of the hydrothermal reaction device (5), and a second outlet of the heating unit 1 being connected to a steam heating inlet of a high-temperature drying device 8. The heating unit is used to provide steam to the hydrothermal reaction system and the high-temperature drying device 8, so as to provide a heat source for reaction heating and drying and dehydration.

[0064] In order to better monitor the temperature, moisture content, pH, chloride ion content, calcium ion content, etc. in the entire system, a feeder motor M01 and a first flow detection instrument F01 are provided between the raw material supply device 2 and the mixing device 3 of the present invention; a second flow detection instrument F02 is provided between the reagent pump 17 and the mixing device 3. A first temperature detection instrument T01 is provided at the inlet of the hydrothermal reaction device 5; and a second temperature detection instrument T02 is provided at the outlet of the hydrothermal reaction device 5. A moisture content detection instrument W01 is provided between the high-temperature drying device 8 and the post-processing device 9; a bypass solenoid valve V11 is provided on the pipeline connecting the mechanical extrusion dehydration device 7 and the hydrothermal reaction device 5; a first circulating water solenoid valve V01 is provided on the pipeline connecting the water outlets of the mechanical extrusion dehydration device 7 and the high-temperature drying device 8 to the circulating water treatment unit 11; a second circulating water solenoid valve V02 is provided on the pipeline connecting the water outlets of the mechanical extrusion dehydration device 7 and the high-temperature drying device 8 to the heat exchanger 14; a first chloride ion detection instrument Cl01 is provided on the pipeline connecting the water outlets of the mechanical extrusion dehydration device 7 and the high-temperature drying device 8; a second chloride ion detection instrument Cl02 is provided on the outlet pipeline of the sedimentation tank 13; the circulating water treatment unit 11 includes a pH value detection instrument pH01; and the sedimentation tank 13 includes a Ca 2+ Ion content detection instrument Ca01; a fourth circulating water solenoid valve V07 is provided on the pipeline between the second mixed outlet after the outlet of the sedimentation tank 13 and the hot side outlet of the heat exchanger 14 are merged and the tail water treatment unit 18, and a third circulating water solenoid valve V06 is provided on the pipeline between the first mixed outlet after the outlet of the sedimentation tank 13 and the hot side outlet of the heat exchanger 14 are merged and the mixing device 3.

[0065] A second reagent tank electromagnetic valve V03 is provided between the circulating water treatment unit 11 and the second reagent tank 10 , and a sewage discharge electromagnetic valve V04 is provided on the sedimentation tank 13 .

[0066] An industrial water solenoid valve V05 is provided between the cold side inlet of the heat exchanger 14 and the industrial water inlet R2.

[0067] A first steam solenoid valve V09 is provided on the steam outlet main pipeline of the heating unit 1 ; a second steam solenoid valve V10 is provided between the first outlet of the heating unit 1 and the hydrothermal reaction device 5 .

[0068] Example 2 This embodiment provides a control method for a dechlorination and upgrading system for preparing α-type hemihydrate gypsum from industrial by-product gypsum, which specifically includes the following steps: When the system starts, water is injected into the mixing device 3 through the industrial water solenoid valve V05. When the material level in the mixing device 3 reaches the L1 value, the slurry pump 4 is turned on to inject water into the hydrothermal reaction device 5. When the hydrothermal reaction device 5 is full of water, the industrial water solenoid valve V05 is closed to complete the water injection.

[0069] The value of L1 is 1 / 3 to 2 / 3 of the internal height of the mixing device 3 .

[0070] Open the bypass solenoid valve V11, open the heating unit 1, the first steam solenoid valve V09, and the second steam solenoid valve V10, heat the water in the hydrothermal reaction device 5 until the temperature reaches T1 value, the pressure reaches P1 value, and the temperature in the high-temperature drying device 8 reaches T2 value, completing the temperature and pressure increase process of the hydrothermal reaction.

[0071] The value of T1 is 90℃~200℃, the value of T2 is 60℃~200℃, and the value of P1 is 0.1MPa~15MPa.

[0072] Turn on the feeder motor M01, the reagent pump 17, the first circulating water solenoid valve V01, the third circulating water solenoid valve V06, adjust the fourth circulating water solenoid valve V07 to the K value, turn on the circulating water pump 12, turn on the high-temperature drying device 8 and the post-processing device 9, and complete the system startup process.

[0073] The value of K is 0~50% of the valve opening.

[0074] The first flow detection instrument F01 controls the power of the feeder motor M01 to be in proportional constraint relationship with the third circulating water solenoid valve V06 and the industrial water solenoid valve V05, so that the moisture content of the desulfurized gypsum slurry prepared by the preparation device 3 is FW1 value; the first flow detection instrument F01 controls the power of the feeder motor M01 to be in proportional constraint relationship with the power of the reagent pump 17 controlled by the second flow detection instrument F02, so that the amount of crystal control agent added is A1 value of the desulfurized gypsum flow rate.

[0075] The value of FW1 is 30wt%~70wt%, and the value of A1 is 0.01wt%~10wt%.

[0076] If the pressure in the hydrothermal reaction device 5 is low, close the bypass solenoid valve V11 and turn on the booster pump 6 so that the slurry has enough pressure energy to drive the mechanical extrusion dehydration device 7 to rotate and dehydrate. If the pressure in the hydrothermal reaction device 5 returns to P1, open the bypass solenoid valve V11 and turn off the booster power device 6.

[0077] The reaction temperature of the hydrothermal reaction device 5 is determined by comparing the temperature measurement values ​​of the first temperature detection instrument T01 and the second temperature detection instrument T02. If the maximum value of the reaction temperature of the hydrothermal reaction device 5 is lower than T1, the openings of the first steam solenoid valve V09 and the second steam solenoid valve V10 are increased to make the maximum temperature in the hydrothermal reaction device 5 higher than T1; if the minimum value of the reaction temperature of the hydrothermal reaction device 5 is higher than T1, the openings of the first steam solenoid valve V09 and the second steam solenoid valve V10 are reduced to make the minimum temperature in the hydrothermal reaction device 5 lower than T1.

[0078] If the value of the moisture content detection instrument W01 is greater than the FW2 value, increase the opening of the first steam solenoid valve V09, increase the power of the heating unit 1, and increase the power of the feeder motor M01; if the value of the moisture content detection instrument W01 is less than the FW2 value, reduce the opening of the first steam solenoid valve V09, reduce the power of the heating unit 1, and reduce the power of the feeder motor M01.

[0079] The value of FW2 is 0.1wt%~10wt%.

[0080] If the chlorine content of the first chloride ion content detection instrument Cl01 is greater than the Cl1 value, open the industrial water solenoid valve V05 and the second circulating water solenoid valve V02, close the first circulating water solenoid valve V01 and the third circulating water solenoid valve V06, and adjust the fourth circulating water solenoid valve V07 to the maximum opening; if the chlorine content of the first chloride ion content detection instrument Cl01 is lower than the Cl1 value, open the first circulating water solenoid valve V01 and the third circulating water solenoid valve V06, close the industrial water solenoid valve V05 and the second circulating water solenoid valve V02, and adjust the fourth circulating water solenoid valve V07 to the third circulating water solenoid valve V03 to satisfy the proportional constraint relationship.

[0081] The Cl1 value is 200ppm~20000ppm.

[0082] If the pH value detection instrument pH01 detects that the pH value in the circulating water treatment device 11 is greater than the pH1 value, the solenoid valve V03 of the second reagent tank is opened, and acidic substances such as sulfuric acid are added to lower the pH value. If the pH value detection instrument pH01 detects that the pH value in the circulating water treatment device 11 is less than the pH2 value, Ca(OH)2 is added to increase the pH value.

[0083] The pH1 value is 4-10, and the pH2 value is 3-9.

[0084] If Ca 2+ The supernatant Ca detected by the ion content detection instrument Ca01 2+ If the concentration is lower than the target value Ca1, the distributor 15 is opened to add the raw material in the raw material supply device 2 to the circulating water treatment device 11.

[0085] The Ca1 value is 20ppm~20000ppm.

[0086] If the second chloride ion detection instrument Cl02 detects that the chloride ion content is higher than the target value Cl2, the opening of the reagent solenoid valve V08 is increased.

[0087] The Cl2 value is 200ppm~20000ppm.

[0088] After the reaction is finished, the feeder motor M01 and the reagent pump 17 are turned off. After the slurry in the hydrothermal reaction device 5 has finished reacting, the second steam solenoid valve V10 is closed to cool down and reduce the pressure of the hydrothermal reaction device 5 .

[0089] After the high-temperature drying device 8 has finished discharging the materials, the heating unit 1 and the first steam solenoid valve V09 are closed.

[0090] Close the third circulating water solenoid valve V06, the second reagent tank solenoid valve V03, and the reagent solenoid valve V08, adjust the fourth circulating water solenoid valve V07, and close the slurry pump 4 and the circulating water pump 12.

[0091] After the post-processing device 9 has finished processing the finished material, the post-processing device 9 is closed.

[0092] After the tail water treatment unit 18 has finished treating the waste water, the tail water treatment unit 18 is closed and all valves that are not closed are closed.

[0093] It should be noted that the component connection relationships not specifically mentioned in the present invention are assumed to adopt the existing technology. Since they do not involve the invention point and are widely used in the existing technology, the structural connection relationships are not described in detail.

[0094] It should be noted that when the present invention involves a numerical range, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes a preferred embodiment. Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the attached claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0095] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A dechlorination and upgrading system for preparing α-type hemihydrate gypsum from industrial by-product gypsum, characterized in that: Including hydrothermal reaction system, water reuse system, steam heating system, dehydration system and post-processing system; The dehydration system comprises a booster power device (6), a mechanical extrusion dehydration device (7) and a high-temperature drying device (8); the outlet of the hydrothermal reaction system is connected to the inlet of the mechanical extrusion dehydration device (7) via the booster power device (6); the outlet of the mechanical extrusion dehydration device (7) is connected to the material inlet of the high-temperature drying device (8); and the material outlet of the high-temperature drying device (8) is connected to a post-processing system; the moisture content of α-hemihydrate gypsum at the material outlet of the high-temperature drying device (8) is regulated by the dehydration system to meet the requirements; The water reuse system comprises a second reagent tank (10), a circulating water treatment unit (11), a circulating water pump (12), a sedimentation tank (13), a heat exchanger (14), and a tail water treatment unit (18); the hot side inlet of the heat exchanger (14) is connected to the water outlet of the mechanical extrusion dehydration device (7) and the high temperature drying device (8); the cold side inlet of the heat exchanger (14) is connected to the industrial water inlet (R2); the cold side outlet of the heat exchanger (14) is connected to the water inlet of the hydrothermal reaction system; the inlet of the circulating water treatment unit (11) is connected to the water outlet of the mechanical extrusion dehydration device (7) and the high temperature drying device (8); The outlet of the water treatment unit (11) is connected to the inlet of the sedimentation tank (13) via a circulating water pump (12); the outlet of the sedimentation tank (13) is combined with the hot side outlet of the heat exchanger (14) to form a first mixed outlet and a second mixed outlet; the first mixed outlet is connected to the water inlet of the hydrothermal reaction system; the second mixed outlet is connected to the tail water treatment unit (18); if the chloride ions in the water removed by the mechanical extrusion dehydration device (7) and the high-temperature drying device (8) meet the requirements, the water enters the circulating water treatment unit (11) for reuse; if the chloride ions in the water discharged from the sedimentation tank (13) meet the requirements, the water enters the hydrothermal reaction system for reuse; The steam heating system is in communication with the hydrothermal reaction system and the high-temperature drying device (8).

2. The dechlorination and upgrading system for preparing α-type hemihydrate gypsum from industrial by-product gypsum according to claim 1, characterized in that: The hydrothermal reaction system comprises a raw material supply device (2), a mixing device (3), a slurry pump (4), a hydrothermal reaction device (5), a distributor (15), a first reagent tank (16), and a reagent pump (17). The outlet of the raw material supply device (2) is respectively connected to the material inlet of the mixing device (3) and the raw material inlet of the circulating water treatment unit (11). The distributor (15) is arranged between the raw material supply device (2) and the raw material inlet of the circulating water treatment unit (11). The outlet of the mixing device (3) is connected to the inlet of the hydrothermal reaction device (5) after passing through the slurry pump (4). The outlet of the first reagent tank (16) is respectively connected to the crystal control agent inlet of the mixing device (3) and the first reagent inlet of the circulating water treatment unit (11).

3. The dechlorination and upgrading system for preparing α-type hemihydrate gypsum from industrial by-product gypsum according to claim 2, characterized in that: The steam heating system comprises a heating unit (1), a first outlet of the heating unit (1) being connected to a steam inlet of the hydrothermal reaction device (5), and a second outlet of the heating unit (1) being connected to a steam heating inlet of a high-temperature drying device (8).

4. The dechlorination and upgrading system for preparing α-type hemihydrate gypsum from industrial by-product gypsum according to claim 3, characterized in that: A feeder motor (M01) and a first flow detection instrument (F01) are provided between the raw material supply device (2) and the mixing device (3); and a second flow detection instrument (F02) is provided between the drug pump (17) and the mixing device (3).

5. The dechlorination and upgrading system for preparing α-type hemihydrate gypsum from industrial by-product gypsum according to claim 4, characterized in that: The inlet of the hydrothermal reaction device (5) is provided with a first temperature detection instrument (T01); the outlet of the hydrothermal reaction device (5) is provided with a second temperature detection instrument (T02).

6. The dechlorination and upgrading system for preparing α-type hemihydrate gypsum from industrial by-product gypsum according to claim 5, characterized in that: A moisture content detection instrument (W01) is provided between the high-temperature drying device (8) and the post-treatment device (9); a bypass solenoid valve (V11) is provided on the pipeline connecting the mechanical extrusion dehydration device (7) and the hydrothermal reaction device (5); a first circulating water solenoid valve (V01) is provided on the pipeline connecting the water outlets of the mechanical extrusion dehydration device (7) and the high-temperature drying device (8) to the circulating water treatment unit (11); a second circulating water solenoid valve (V02) is provided on the pipeline connecting the water outlets of the mechanical extrusion dehydration device (7) and the high-temperature drying device (8) to the heat exchanger (14); a first chloride ion detection instrument (Cl01) is provided on the pipeline connecting the water outlets of the mechanical extrusion dehydration device (7) and the high-temperature drying device (8); a second chloride ion detection instrument (Cl02) is provided on the outlet pipeline of the sedimentation tank (13); the circulating water treatment unit (11) includes a pH value detection instrument (pH01); the sedimentation tank (13) includes a Ca2+ detector (Cl2); 2+ An ion content detection instrument (Ca01); a fourth circulating water solenoid valve (V07) is provided on a pipeline between a second mixed outlet after the outlet of the sedimentation tank (13) and the hot side outlet of the heat exchanger (14) are combined and the tail water treatment unit (18); a third circulating water solenoid valve (V06) is provided on a pipeline between a first mixed outlet after the outlet of the sedimentation tank (13) and the hot side outlet of the heat exchanger (14) are combined and the mixing device (3).

7. The dechlorination and upgrading system for preparing α-hemihydrate gypsum from industrial by-product gypsum according to claim 6, characterized in that: A second reagent tank electromagnetic valve (V03) is provided between the circulating water treatment unit (11) and the second reagent tank (10), and a sewage discharge electromagnetic valve (V04) is provided on the sedimentation tank (13).

8. The dechlorination and upgrading system for preparing α-hemihydrate gypsum from industrial by-product gypsum according to claim 7, characterized in that: An industrial water solenoid valve (V05) is provided between the cold side inlet of the heat exchanger (14) and the industrial water inlet (R2).

9. The dechlorination and upgrading system for preparing α-type hemihydrate gypsum from industrial by-product gypsum according to claim 8, characterized in that: A first steam solenoid valve (V09) is provided on the steam outlet main pipeline of the heating unit (1); and a second steam solenoid valve (V10) is provided between the first outlet of the heating unit (1) and the hydrothermal reaction device (5).

10. A control method for a dechlorination and upgrading system for preparing α-hemihydrate gypsum from industrial by-product gypsum according to claim 9, characterized in that: The following steps are involved: When the system is started, water is injected into the mixing device (3) through the industrial water solenoid valve (V05). When the material level in the mixing device (3) reaches the value L1, the slurry pump (4) is turned on to inject water into the hydrothermal reaction device (5). When the hydrothermal reaction device (5) is full of water, the industrial water solenoid valve (V05) is closed to complete the water injection. The value of L1 is 1 / 3 to 2 / 3 of the internal height of the mixing device (3); Open the bypass solenoid valve (V11), open the heating unit (1), the first steam solenoid valve (V09) and the second steam solenoid valve (V10), heat the water in the hydrothermal reaction device (5) until the temperature reaches a value T1, the pressure reaches a value P1, and the temperature in the high-temperature drying device (8) reaches a value T2, thereby completing the temperature and pressure increase process of the hydrothermal reaction; The value of T1 is 90℃~200℃, the value of T2 is 60℃~200℃, and the value of P1 is 0.1MPa~15MPa; Turn on the feeder motor (M01), the reagent pump (17), the first circulating water solenoid valve (V01) and the third circulating water solenoid valve (V06), adjust the fourth circulating water solenoid valve (V07) to the K value, turn on the circulating water pump (12), turn on the high-temperature drying device (8) and the post-processing device (9), and complete the system startup process; The value of K is 0~50% of the valve opening; The first flow detection instrument (F01) controls the power of the feeder motor (M01) to be in a proportional constraint relationship with the third circulating water solenoid valve (V06) and the industrial water solenoid valve (V05), so that the moisture content of the desulfurized gypsum slurry prepared by the preparation device (3) is FW1 value; the first flow detection instrument (F01) controls the power of the feeder motor (M01) to be in a proportional constraint relationship with the power of the reagent pump (17) controlled by the second flow detection instrument (F02), so that the amount of crystal control agent added is A1 value of the desulfurized gypsum flow rate; The value of FW1 is 30wt%~70wt%, and the value of A1 is 0.01wt%~10wt%; If the pressure in the hydrothermal reaction device (5) is low, the bypass solenoid valve (V11) is closed and the booster pump (6) is turned on, so that the slurry has sufficient pressure energy to drive the mechanical extrusion dehydration device (7) to rotate and dehydrate. If the pressure in the hydrothermal reaction device (5) is restored to P1, the bypass solenoid valve (V11) is opened and the booster power device (6) is turned off; The reaction temperature of the hydrothermal reaction device (5) is determined by comparing the temperature measurement values ​​of the first temperature detection instrument (T01) and the second temperature detection instrument (T02); if the maximum value of the reaction temperature of the hydrothermal reaction device (5) is lower than T1, the openings of the first steam solenoid valve (V09) and the second steam solenoid valve (V10) are increased so that the maximum temperature in the hydrothermal reaction device (5) is higher than T1; if the minimum value of the reaction temperature of the hydrothermal reaction device (5) is higher than T1, the openings of the first steam solenoid valve (V09) and the second steam solenoid valve (V10) are reduced so that the minimum temperature in the hydrothermal reaction device (5) is lower than T1; If the value of the moisture content detection instrument (W01) is greater than the FW2 value, the opening of the first steam solenoid valve (V09) is increased, the power of the heating unit (1) is increased, and the power of the feeder motor (M01) is increased; if the value of the moisture content detection instrument (W01) is less than the FW2 value, the opening of the first steam solenoid valve (V09) is reduced, the power of the heating unit (1) is reduced, and the power of the feeder motor (M01) is reduced; The value of FW2 is 0.1wt%~10wt%; If the chlorine content of the first chloride ion content detection instrument (Cl01) is greater than the Cl1 value, the industrial water solenoid valve (V05) and the second circulating water solenoid valve (V02) are opened, the first circulating water solenoid valve (V01) and the third circulating water solenoid valve (V06) are closed, and the fourth circulating water solenoid valve (V07) is adjusted to the maximum opening; if the chlorine content of the first chloride ion content detection instrument (Cl01) is lower than the Cl1 value, the first circulating water solenoid valve (V01) and the third circulating water solenoid valve (V06) are opened, the industrial water solenoid valve (V05) and the second circulating water solenoid valve (V02) are closed, and the fourth circulating water solenoid valve (V07) is adjusted to the third circulating water solenoid valve (V03) to satisfy the proportional constraint relationship; Cl1 value is 200ppm~20000ppm; If the pH value detection instrument (pH01) detects that the pH value in the circulating water treatment device (11) is greater than the pH1 value, the solenoid valve (V03) of the second reagent tank is opened, and an acidic substance such as sulfuric acid is added to lower the pH value; if the pH value detection instrument (pH01) detects that the pH value in the circulating water treatment device (11) is less than the pH2 value, Ca(OH)2 is added to increase the pH value; pH1 is 4-10, pH2 is 3-9; If Ca 2+ The supernatant Ca detected by the ion content detection instrument (Ca01) 2+ If the concentration is lower than the target value Ca1, the distributor (15) is opened to add the raw material in the raw material supply device (2) to the circulating water treatment device (11); Ca1 value is 20ppm~20000ppm; If the second chloride ion detection instrument (Cl02) detects that the chloride ion content is higher than the target value Cl2, the opening of the reagent solenoid valve (V08) is increased; Cl2 value is 200ppm~20000ppm; After the reaction is finished, the feeder motor (M01) and the reagent pump (17) are turned off. After the slurry in the hydrothermal reaction device (5) has finished reacting, the second steam solenoid valve (V10) is closed to cool down and reduce the pressure of the hydrothermal reaction device (5); After the high-temperature drying device (8) has finished discharging the materials, the heating unit (1) and the first steam solenoid valve (V09) are closed; Close the third circulating water solenoid valve (V06), the second reagent tank solenoid valve (V03) and the reagent solenoid valve (V08), adjust the fourth circulating water solenoid valve (V07), and close the slurry pump (4) and the circulating water pump (12); After the post-processing device (9) has finished processing the finished material, the post-processing device (9) is closed; After the tail water treatment unit (18) has finished treating the wastewater, the tail water treatment unit (18) is closed and all valves that are not closed are closed.

Images