A dechlorination and upgrading system for preparing alpha-type hemihydrate gypsum from industrial by-product gypsum and a control method thereof

Abstract

The application discloses a kind of industrial byproduct gypsum preparation α-type hemihydrate gypsum dechlorination quality improving system and control method, belong to α hemihydrate gypsum production technical field.The system, hydrothermal reaction system and mechanical extrusion dehydration device are communicated by booster power device between, mechanical extrusion dehydration device, high-temperature drying device and post-processing system are sequentially communicated;The hot side entrance of heat exchanger is communicated with mechanical extrusion dehydration device and high-temperature drying device, the cold side entrance of heat exchanger is communicated with industrial water inlet, the cold side outlet of heat exchanger is communicated with hydrothermal reaction system, circulating water treatment unit is communicated with mechanical extrusion dehydration device and high-temperature drying device, circulating water treatment unit is communicated with sedimentation tank by circulating water pump, sedimentation tank and the hot side outlet of heat exchanger are gathered and communicated with hydrothermal reaction system and with tail water treatment unit;Steam heating system is communicated with hydrothermal reaction system and high-temperature drying device.The system can be stably operated, and the good product rate of finished gypsum is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of α-hemihydrate gypsum production technology, and more specifically to a dechlorination and upgrading system and control method for preparing α-type hemihydrate gypsum from industrial by-product gypsum. Background Technology

[0002] Industrial by-product gypsum is a byproduct of wet flue gas desulfurization technology used in boiler combustion systems and other applications. Its main component is calcium sulfate dihydrate (CaSO4·2H2O). Industrial by-product gypsum falls under the category of solid waste, and its disposal method is generally harmless landfilling. However, this method does not fully utilize the high concentration of calcium sulfate dihydrate in the desulfurization gypsum, and improper disposal can cause the leaching of trace elements from the industrial by-product gypsum, endangering soil and water resources and adversely affecting the flora and fauna surrounding the landfill site. Therefore, the resource utilization of desulfurization gypsum, this solid waste, is of positive significance for environmental protection and also helps to enhance its economic value.

[0003] Because industrial by-product gypsum contains a large amount of calcium sulfate dihydrate (CaSO4·0.5H2O), preparing it as calcium sulfate hemihydrate is a common resource utilization method. However, current processes mainly produce β-hemihydrate gypsum (β-CaSO4·0.5H2O), which is primarily used in the construction industry, resulting in low economic value. Furthermore, the large amount of chloride ions in industrial by-product gypsum cannot be effectively removed, leading to insufficient product strength. Although some processes exist aimed at producing α-hemihydrate gypsum, these mainly rely on autoclaving, which also fails to effectively remove chloride ions, resulting in poor water absorption, whiteness, and strength, and failing to meet the demands of continuous industrial production. In addition, the current method for addressing the high chloride ion content in gypsum products is mostly water washing, which consumes a large amount of water and cannot remove chloride ions contained in the crystal lattice, thus resulting in low efficiency.

[0004] Hydrothermal treatment, which involves preparing industrial by-product gypsum into a slurry and reacting it in a high-temperature, high-pressure aqueous environment, can simultaneously produce α-hemihydrate gypsum and remove harmful substances such as chloride ions. This method shows great promise for the treatment of industrial by-product gypsum. However, in actual industrial operation, it is crucial to ensure temperature stability during the hydrothermal reaction, control the chloride ion removal process, and improve system economy through water circulation, pressure energy reuse, and heat recovery. Furthermore, if operational problems occur in the hydrothermal reaction system, causing it to operate outside its optimal range, it may result in substandard α-hemihydrate gypsum, incomplete chloride ion removal, increased system energy consumption, and decreased economic efficiency. Therefore, to improve the stability and economical operation of hydrothermal treatment of industrial by-product gypsum, a comprehensive control strategy is urgently needed to adapt to different industrial by-product gypsum raw materials, ensure the yield of finished gypsum, and address potential fluctuations in operating conditions and safety risks. Summary of the Invention

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

[0006] The purpose of this 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-treatment system.

[0007] The dehydration system includes a booster power unit, a mechanical extrusion dehydration unit, and a high-temperature drying unit. The outlet of the hydrothermal reaction system is connected to the inlet of the mechanical extrusion dehydration unit via the booster power unit. The outlet of the mechanical extrusion dehydration unit is connected to the material inlet of the high-temperature drying unit. The material outlet of the high-temperature drying unit is connected to the post-processing system. The dehydration system regulates the moisture content of the α-hemihydrate gypsum at the material outlet of the high-temperature drying unit 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 tailwater treatment unit. The hot-side inlet of the heat exchanger is connected to the 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 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 via the circulating water pump. The outlet of the sedimentation tank and the hot-side outlet of the heat exchanger converge and are 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 tailwater treatment unit. If the chloride ions removed from the water 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. 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 connected to 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 connected to the material inlet of the mixing device and the raw material inlet of the circulating water treatment unit, respectively. The distributor is located 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 connected to the crystallizer inlet of the mixing device and the first reagent inlet of the circulating water treatment unit, respectively.

[0011] In a preferred embodiment of the present invention, the steam heating system includes a heating unit, the first outlet of which is connected to the steam inlet of the hydrothermal reaction device, and the second outlet of which 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 meter are provided between the raw material supply device and the mixing device; a second flow meter is provided between the reagent pump and the mixing device.

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

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

[0015] In a preferred embodiment of the present invention, a second chemical tank solenoid valve is provided between the circulating water treatment unit and the second chemical 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 main steam outlet pipeline of the heating unit; a second steam solenoid valve is provided between the first outlet of the heating unit and the hydrothermal reaction device.

[0018] The second objective of this invention is to provide a control method for the dechlorination and upgrading system of the above-mentioned industrial by-product gypsum in the preparation of α-hemihydrate gypsum, comprising the following steps:

[0019] When the system starts up, 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.

[0020] The value of L1 is 1 / 3 to 2 / 3 of the internal height of the regulating device.

[0021] Open the bypass solenoid valve, start 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 the T1 value and the pressure reaches the P1 value, and the temperature in the high-temperature drying device reaches the T2 value, thus completing the heating and pressurization process of the hydrothermal reaction.

[0022] The value of T1 is 90℃~200℃, the value of T2 is 60℃~200℃, and the value of P1 is 0.1MPa~15MPa.

[0023] Turn on the feeder motor, reagent pump, first circulating water solenoid valve and third circulating water solenoid valve, adjust the fourth circulating water solenoid valve to the K value, turn on the circulating water pump, start the high temperature drying device and post-treatment device, and complete the system startup process.

[0024] The value of K is 0 to 50% of the valve opening.

[0025] The power of the feeder motor controlled by the first flow meter is proportionally constrained to the power of the third circulating water solenoid valve and the industrial water solenoid valve, so that the water content of the desulfurized gypsum slurry prepared by the mixing device is the value of FW1; the power of the feeder motor controlled by the first flow meter is proportionally constrained to the power of the reagent pump controlled by the second flow meter, so that the amount of crystal control agent added is the value of A1 of the desulfurized gypsum flow rate.

[0026] The value of FW1 is 30wt%~70wt%, and the value of A1 is 0.01wt%~10wt%.

[0027] If the pressure in the hydrothermal reactor is low, close the bypass solenoid valve and turn on the booster pump to give the slurry enough pressure to drive the mechanical extrusion dewatering device to rotate and dewater. If the pressure in the hydrothermal reactor returns to P1, open the bypass solenoid valve and turn off the booster power device.

[0028] The reaction temperature of the hydrothermal reactor is determined by comparing the temperature measurements of the first and second temperature measuring instruments. If the highest reaction temperature of the hydrothermal reactor is lower than T1, the opening of the first and second steam solenoid valves is increased to make the highest temperature in the hydrothermal reactor higher than T1. If the lowest reaction temperature of the hydrothermal reactor is higher than T1, the opening of the first and second steam solenoid valves is decreased to make the lowest temperature in the hydrothermal reactor lower than T1.

[0029] If the value of the moisture content meter 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 meter is less than the FW2 value, decrease the opening of the first steam solenoid valve, decrease the power of the heating unit, and decrease the power of the feeder motor.

[0030] The value of FW2 is 0.1wt%~10wt%.

[0031] If the chlorine content of the first chloride ion content detector 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 its maximum opening. If the chlorine content of the first chloride ion content detector 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 until the third circulating water solenoid valve satisfies the aforementioned proportional constraint relationship.

[0032] Cl1 values ​​range from 200ppm to 20000ppm.

[0033] If the pH meter detects that the pH value in the circulating water treatment device is greater than pH1, 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 meter detects that the pH value in the circulating water treatment device is less than pH2, Ca(OH)2 is added to increase the pH value.

[0034] pH1 is 4-10, and pH2 is 3-9.

[0035] If Ca 2+ The Ca content detected by the ion content detection instrument in the supernatant 2+ If the concentration is lower than the target value Ca1, the distributor is opened to add the raw material from the raw material supply device to the circulating water treatment device.

[0036] The Ca1 value ranges from 20 ppm to 20,000 ppm.

[0037] If the second chloride ion detector detects that the chloride ion content is higher than the target value Cl2, the opening degree of the reagent solenoid valve will be increased.

[0038] Cl2 values ​​range from 200ppm to 20000ppm.

[0039] After the reaction is complete, turn off the feeder motor and reagent pump. After the slurry in the hydrothermal reactor has finished reacting, close the second steam solenoid valve to cool and depressurize the hydrothermal reactor.

[0040] After the high-temperature drying device finishes discharging the material, the heating unit and the first steam solenoid valve are shut off.

[0041] 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 the circulating water pump.

[0042] After the post-processing unit has finished processing the finished material, it is turned off.

[0043] After the wastewater treatment unit has finished treating the wastewater, shut down the wastewater treatment unit and close all valves that are not closed.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] 1. This invention regulates the moisture content of α-hemihydrate gypsum at the material outlet of the high-temperature drying device through a dehydration system to meet requirements; the chloride ions removed from the water by the mechanical extrusion dehydration device and the high-temperature drying device meet requirements and are reused in the circulating water treatment unit; the chloride ions discharged from the sedimentation tank meet requirements and are reused in the hydrothermal reaction system; by real-time monitoring of chloride content and moisture content and controlling water circulation and steam supply, the stable operation of the process system for preparing α-hemihydrate gypsum from desulfurized gypsum based on the hydrothermal method is achieved, ensuring that the finished α-hemihydrate gypsum meets the requirements for chloride content, moisture content, and purity, reducing the probability of abnormal system operation, and improving the product yield.

[0046] 2. This invention achieves precise recycling of dechlorinated 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 needed when the chlorine content of the circulating water is too high, thus improving the efficiency of water resource utilization. Through monitoring and removing chloride ions from the circulating water and efficiently controlling the switching between circulating water and industrial water, it is ensured that the prepared slurry is always below the maximum critical value of chlorine content in the hydrothermal reaction system.

[0047] 3. This invention utilizes the pressure energy of the high-temperature and high-pressure slurry after hydrothermal reaction to drive mechanical extrusion and rotation for dehydration and heat recycling, achieving dual recovery of system temperature and pressure. It also removes some moisture before high-temperature drying, thus reducing the energy consumption of the process system and improving economic efficiency.

[0048] 4. This invention achieves stable and precise heat supply and efficient heat recovery by detecting the temperature of the reactor, the moisture content of the dehydration system, and the interlocking control of the water and steam valves. It also ensures that the reaction temperature and concentration are always within the high reaction efficiency range and that the drying temperature is stable, effectively preventing the reversal or complete dehydration of α-hemihydrate gypsum.

[0049] 5. According to the control method of the dechlorination and upgrading system for preparing α-hemihydrate gypsum from industrial by-product gypsum in this invention, even if different raw materials are input, the operating strategy can be dynamically adjusted through the system control method to ensure that the product meets the requirements and the system operates stably. Attached Figure Description

[0050] Figure 1 This is 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.

[0051] Figure reference 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 dewatering device; 8-High temperature drying device; 9-Post-treatment 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-Tailwater treatment unit; V01-First circulating water solenoid valve; V02-Second circulating water solenoid valve; V03-Second reagent tank solenoid valve; V04-Sewage discharge solenoid valve Valves; 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 meter; F02 - Second flow meter; T01 - First temperature meter; T02 - Second temperature meter; W01 - Moisture content meter; Cl01 - First chloride ion content meter; Cl02 - Second chloride ion content meter; Ca01 - Ca 2+ Ion content detection instrument; pH01 - pH value detection instrument; R1 - Industrial by-product gypsum inlet; R2 - Industrial water inlet. Detailed Implementation

[0052] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" 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 of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0054] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0055] 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 invention, unless otherwise stated, "a plurality of" means two or more.

[0056] The technical solution of the present invention will be further described below.

[0057] Based on this, the present invention provides a dechlorination and upgrading system and method for preparing α-type hemihydrate gypsum from industrial by-product gypsum, realizing the efficient conversion of desulfurized gypsum into α-type hemihydrate gypsum, removing chloride ions, and ensuring the stability of system operation and the yield of products, thereby improving the economic value of desulfurized gypsum resource utilization.

[0058] Example 1

[0059] 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 dashed lines in the diagram represent the paths of water and steam, while the solid lines represent the paths of the slurry. This dechlorination and upgrading system includes a hydrothermal reaction system, a water reuse system, a steam heating system, a dewatering system, and a post-treatment system.

[0060] 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 connected to the material inlet of the mixing device 3 and the raw material inlet of the circulating water treatment unit 11, respectively. The distributor 15 is located 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 via the slurry pump 4. The outlet of the first reagent tank 16 is connected to the crystallizer inlet of the mixing device 3 and the first reagent inlet of the circulating water treatment unit 11, respectively.

[0061] Before the reaction, the industrial by-product gypsum from the raw material supply device 2 and the crystal-controlling agent from the first reagent tank 16 are added to the mixing device 3 via the reagent pump 17. After mixing, the mixture is added to the hydrothermal reaction device 5 via the slurry pump 4 for hydrothermal reaction. After the hydrothermal reaction is completed, the prepared product enters the dehydration system for dehydration treatment.

[0062] The dehydration system includes a pressurizing power unit 6, a mechanical extrusion dehydration unit 7, and a high-temperature drying unit 8. The product obtained from the hydrothermal reaction sequentially enters the mechanical extrusion dehydration unit 7, the high-temperature drying unit 8, and the post-treatment unit 9. If the pressure of the hydrothermal reaction unit 5 does not meet the standard value, it enters the mechanical extrusion dehydration unit 7 through the pressurizing power unit 6. During the dehydration process, the finished slurry from the hydrothermal reaction unit 5 undergoes mechanical removal of moisture in the mechanical extrusion dehydration unit 7. The processed product then enters the high-temperature drying unit 8, and the processed product enters the post-treatment system for high-temperature removal of moisture.

[0063] 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 tailwater treatment unit 18. The hot-side inlet of the heat exchanger 14 is connected to the outlet of the mechanical extrusion dewatering device 7 and the 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 mixing device 3. The inlet of the circulating water treatment unit 11 is connected to the outlets of the mechanical extrusion dewatering 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 via the circulating water pump 12. The outlet of the sedimentation tank 13 and the hot-side outlet of the heat exchanger 14 converge and are divided into a first mixed outlet and a second mixed outlet. The first mixed outlet is connected to the water inlet of the mixing device 3, and the second mixed outlet is connected to the tailwater treatment unit 18.

[0064] During operation, the water reuse system receives separated water from the mechanical extrusion device 7 and dried condensate from the high-temperature drying device 8. After passing the test by the first chloride ion content detector ClO1, the water enters the circulating water treatment unit 11. In the circulating water treatment unit, a crystal-controlling agent from the first reagent tank 16 and a pH adjuster from the second reagent tank 10 are added. The resulting well-prepared circulating water then enters the sedimentation tank 13 via the circulating water pump 12. Chlorine-containing precipitates are removed in the sedimentation tank 13, and the resulting pure circulating water flows out from the outlet of the sedimentation tank 13. After passing the test by the second chloride ion content detector ClO2, the water enters the mixing device 3 from the first mixing outlet for slurry preparation. If the second chloride ion content detector ClO2 fails to meet the test, the amount of crystal-controlling agent added to the circulating water treatment unit 11 needs to be increased. The pure circulating water generated in the sedimentation tank 13 is added to the mixing device 3. Excess pure circulating water or circulating water with too high chloride ion content that cannot be reused enters the tailwater treatment unit 18 from the second mixing outlet for water discharge.

[0065] The separated water in the mechanical extrusion device 7 and the dried condensate in the high-temperature drying device 8 are detected by the first chloride ion content detector 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 entered industrial water. The industrial water enters the heat exchanger 14 sequentially from the industrial water inlet R2 and the cold side inlet of the heat exchanger 14 to recover the heat of the circulating water. The resulting hot industrial water enters the blending device 3 from the cold side outlet of the heat exchanger 14 and the water inlet of the blending device 3 for slurry blending.

[0066] The steam heating system includes a heating unit 1. The first outlet of the heating unit 1 is connected to the steam inlet of the hydrothermal reaction device (5), and the second outlet of the heating unit 1 is connected to the steam heating inlet of the 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, and to provide a heat source for reaction heating and drying dehydration.

[0067] To better monitor the temperature, moisture content, pH, chloride ion content, and calcium ion content of the entire system, a feeder motor M01 and a first flow meter F01 are provided between the raw material supply device 2 and the mixing device 3; a second flow meter F02 is provided between the reagent pump 17 and the mixing device 3. A first temperature meter T01 is provided at the inlet of the hydrothermal reaction device 5; a second temperature meter T02 is provided at the outlet of the hydrothermal reaction device 5. A moisture content measuring instrument WO1 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 measuring 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 measuring instrument Cl02 is provided on the outlet pipeline of the sedimentation tank 13; the circulating water treatment unit 11 includes a pH measuring instrument pH01; and the sedimentation tank 13 includes Ca... 2+ An ion content detection instrument Ca01 is provided; 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 combined and the tailwater treatment unit 18; 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 combined and the mixing device 3.

[0068] A second chemical tank solenoid valve V03 is provided between the circulating water treatment unit 11 and the second chemical tank 10, and a sewage discharge solenoid valve V04 is provided on the sedimentation tank 13.

[0069] An industrial water solenoid valve V05 is provided between the cold side inlet of the heat exchanger 14 and the industrial water inlet R2.

[0070] A first steam solenoid valve V09 is provided on the main steam outlet 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.

[0071] Example 2

[0072] This embodiment provides a control method for a dechlorination and upgrading system in the preparation of α-type hemihydrate gypsum from industrial by-product gypsum, specifically including the following steps:

[0073] 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.

[0074] The value of L1 is 1 / 3 to 2 / 3 of the internal height of the dispensing device 3.

[0075] Open the bypass solenoid valve V11, start 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 the T1 value and the pressure reaches the P1 value, and the temperature in the high-temperature drying device 8 reaches the T2 value, thus completing the heating and pressurization process of the hydrothermal reaction.

[0076] The value of T1 is 90℃~200℃, the value of T2 is 60℃~200℃, and the value of P1 is 0.1MPa~15MPa.

[0077] 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, and turn on the high-temperature drying device 8 and the post-treatment device 9 to complete the system startup process.

[0078] The value of K is 0 to 50% of the valve opening.

[0079] The power of the feeder motor M01 controlled by the first flow meter F01 is proportionally constrained to the power of 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 mixing device 3 is the value FW1; the power of the feeder motor M01 controlled by the first flow meter F01 is proportionally constrained to the power of the reagent pump 17 controlled by the second flow meter F02, so that the amount of crystallizing agent added is the value A1 of the desulfurized gypsum flow rate.

[0080] The value of FW1 is 30wt%~70wt%, and the value of A1 is 0.01wt%~10wt%.

[0081] If the pressure in the hydrothermal reactor 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 dewatering device 7 to rotate and dewater. If the pressure in the hydrothermal reactor 5 returns to P1, open the bypass solenoid valve V11 and turn off the booster power device 6.

[0082] The reaction temperature of the hydrothermal reactor 5 is determined by comparing the temperature measurements of the first temperature measuring instrument T01 and the second temperature measuring instrument T02. If the highest reaction temperature of the hydrothermal reactor 5 is lower than T1, the opening of the first steam solenoid valve V09 and the second steam solenoid valve V10 is increased to make the highest temperature in the hydrothermal reactor 5 higher than T1. If the lowest reaction temperature of the hydrothermal reactor 5 is higher than T1, the opening of the first steam solenoid valve V09 and the second steam solenoid valve V10 is decreased to make the lowest temperature in the hydrothermal reactor 5 lower than T1.

[0083] If the value of the moisture content measuring instrument W01 is greater than the value of FW2, the opening degree 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 measuring instrument W01 is less than the value of FW2, the opening degree of the first steam solenoid valve V09 is decreased, the power of the heating unit 1 is reduced, and the power of the feeder motor M01 is reduced.

[0084] The value of FW2 is 0.1wt%~10wt%.

[0085] If the chlorine content of the first chloride ion content detector 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 its maximum opening. If the chlorine content of the first chloride ion content detector 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 until the third circulating water solenoid valve V03 satisfies the aforementioned proportional constraint relationship.

[0086] Cl1 values ​​range from 200ppm to 20000ppm.

[0087] If the pH meter 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 meter 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.

[0088] pH1 is 4-10, and pH2 is 3-9.

[0089] If Ca 2+ The Ca content in the supernatant detected by the Ca01 ion content detection instrument 2+ If the concentration is lower than the target value Ca1, then the distributor 15 is opened to add the raw material from the raw material supply device 2 to the circulating water treatment device 11.

[0090] The Ca1 value ranges from 20 ppm to 20,000 ppm.

[0091] If the second chloride ion detector Cl02 detects a chloride ion content higher than the target value Cl2, then the opening degree of the reagent solenoid valve V08 is increased.

[0092] Cl2 values ​​range from 200ppm to 20000ppm.

[0093] After the reaction is completed, turn off the feeder motor M01 and the reagent pump 17. After the slurry in the hydrothermal reaction device 5 has finished reacting, turn off the second steam solenoid valve V10 to cool down and depressurize the hydrothermal reaction device 5.

[0094] After the high-temperature drying device 8 finishes discharging material, the heating unit 1 and the first steam solenoid valve V09 are shut off.

[0095] 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.

[0096] After the post-processing device 9 has finished processing the finished material, it is turned off.

[0097] After the wastewater treatment unit 18 has finished treating the wastewater, it shall be shut down and all valves that are not closed shall be closed.

[0098] It should be noted that the connection relationships of components not specifically mentioned in this invention are all assumed to be based on existing technology. Since they do not involve the inventive point and are commonly used in existing technology, the structural connection relationships are not described in detail.

[0099] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

[0100] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends 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, It includes a hydrothermal reaction system, a water reuse system, a steam heating system, a dehydration system, and a post-treatment device (9); The dehydration system includes a booster power unit (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) through the booster power unit (6). The outlet of the mechanical extrusion dehydration device (7) is connected to the material inlet of the high-temperature drying device (8). The material outlet of the high-temperature drying device (8) is connected to the post-processing device (9). The dehydration system controls the moisture content of the α-hemihydrate gypsum at the material outlet of the high-temperature drying device (8) to meet the requirements. 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 tailwater treatment unit (18). The hot-side inlet of the heat exchanger (14) is connected to the outlet of the mechanical extrusion dewatering 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 outlet of the mechanical extrusion dewatering 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 the circulating water pump (12). The outlet of the sedimentation tank (13) and the hot side outlet of the heat exchanger (14) are combined and 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 tailwater treatment unit (18). If the chloride ions removed by the mechanical extrusion dewatering device (7) and the high temperature drying device (8) meet the requirements, they are reused in the circulating water treatment unit (11). If the chloride ions discharged from the sedimentation tank (13) meet the requirements, they are reused in the hydrothermal reaction system. The steam heating system is connected to 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 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 connected to the material inlet of the mixing device (3) and the raw material inlet of the circulating water treatment unit (11), respectively. The distributor (15) is located 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 connected to the crystal control agent inlet of the mixing device (3) and the first reagent inlet of the circulating water treatment unit (11), respectively.

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 includes a heating unit (1), the first outlet of which is connected to the steam inlet of the hydrothermal reaction device (5), and the second outlet of which is connected to the steam heating inlet of the 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 meter (F01) are provided between the raw material supply device (2) and the mixing device (3); a second flow meter (F02) is provided between the reagent 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 equipped with a first temperature detection instrument (T01); the outlet of the hydrothermal reaction device (5) is equipped 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 measuring instrument (WO1) 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 content measuring 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 content measuring instrument (Cl02) is provided on the outlet pipeline of the sedimentation tank (13); the circulating water treatment unit (11) includes a pH measuring instrument (pH01); and the sedimentation tank (13) includes Ca. 2+ An ion content detection instrument (Ca01); a fourth circulating water solenoid valve (V07) is provided on the pipeline between the outlet of the sedimentation tank (13) and the hot side outlet of the heat exchanger (14) and the tailwater treatment unit (18); a third circulating water solenoid valve (V06) is provided on the pipeline between the outlet of the sedimentation tank (13) and the hot side outlet of the heat exchanger (14) and the mixing device (3).

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

8. The dechlorination and upgrading system for preparing α-type 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, The heating unit (1) is provided with a first steam solenoid valve (V09) on the main steam outlet pipeline; 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, Includes the following steps: 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 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 turned off to complete the water injection. The value of L1 is 1 / 3 to 2 / 3 of the internal height of the dispensing device (3); Open the bypass solenoid valve (V11), turn on 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 the T1 value and the pressure reaches the P1 value, and the temperature in the high temperature drying device (8) reaches the T2 value, thus completing the heating and pressurization 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-treatment device (9) to complete the system startup process; The value of K is 0% to 50% of the valve opening. The first flow meter (F01) controls the power of the feeder motor (M01) to be proportionally constrained with the power of the third circulating water solenoid valve (V06) and the industrial water solenoid valve (V05), so that the water content of the desulfurized gypsum slurry prepared by the mixing device (3) is the value of FW1; the first flow meter (F01) controls the power of the feeder motor (M01) to be proportionally constrained with the power of the reagent pump (17) controlled by the second flow meter (F02), so that the amount of crystal control agent added is the value of A1 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 reactor (5) is low, close the bypass solenoid valve (V11) and turn on the booster power device (6) so that the slurry has enough pressure energy to drive the mechanical extrusion dewatering device (7) to rotate and dewater. If the pressure in the hydrothermal reactor (5) returns to P1, open the bypass solenoid valve (V11) and turn off the booster power device (6). The reaction temperature of the hydrothermal reactor (5) is determined by comparing the temperature measurements of the first temperature measuring instrument (T01) and the second temperature measuring instrument (T02). If the highest value of the reaction temperature of the hydrothermal reactor (5) is lower than T1, the opening of the first steam solenoid valve (V09) and the second steam solenoid valve (V10) is increased so that the highest temperature in the hydrothermal reactor (5) is higher than T1. If the lowest value of the reaction temperature of the hydrothermal reactor (5) is higher than T1, the opening of the first steam solenoid valve (V09) and the second steam solenoid valve (V10) is decreased so that the lowest temperature in the hydrothermal reactor (5) is lower than T1. If the value of the moisture content measuring instrument (W01) is greater than the value of FW2, 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 measuring instrument (W01) is less than the value of FW2, decrease the opening of the first steam solenoid valve (V09), decrease the power of the heating unit (1), and decrease the power of the feeder motor (M01). The value of FW2 is 0.1wt%~10wt%; If the chlorine content of the first chloride ion content detector (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 its maximum opening. If the chlorine content of the first chloride ion content detector (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) until the third circulating water solenoid valve (V06) satisfies the aforementioned proportional constraint relationship. Cl1 values ​​range from 200 ppm to 20000 ppm; If the pH meter (pH01) detects that the pH value in the circulating water treatment unit (11) is greater than the pH1 value, the second agent tank solenoid valve (V03) is opened, and acidic substances such as sulfuric acid are added to lower the pH value. If the pH meter (pH01) detects that the pH value in the circulating water treatment unit (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 Ca content detected by the ion content detection instrument (Ca01) in the supernatant 2+ If the concentration is lower than the target value Ca1, the distributor (15) is opened to add the raw material from the raw material supply device (2) to the circulating water treatment unit (11); Ca1 values ​​range from 20 ppm to 20,000 ppm; If the second chloride ion content detection instrument (ClO2) detects that the chloride ion content is higher than the target value Cl2, then the opening degree of the reagent solenoid valve (V08) is increased; Cl2 value is 200ppm~20000ppm; After the reaction is completed, turn off the feeder motor (M01) and the reagent pump (17). After the slurry in the hydrothermal reaction device (5) has finished reacting, turn off the second steam solenoid valve (V10) to cool down and reduce the pressure of the hydrothermal reaction device (5). After the high-temperature drying device (8) finishes discharging material, 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, it is turned off. After the wastewater treatment unit (18) has finished treating the wastewater, it shall be shut down and all valves that are not closed shall be closed.

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