Low-water-consumption energy-saving high-strength gypsum phase change evaporation drying system and method

Abstract

The invention belongs to the technical field of power plant waste treatment, and particularly relates to a low-water-consumption energy-saving high-strength gypsum phase change evaporation drying system and method. Comprising a high-strength gypsum preparation system used for blending desulfurized gypsum to form gypsum slurry, carrying out a hydrothermal reaction on the gypsum slurry, and separating to obtain an initial product; the product waste heat utilization drying system comprises a boiler, and a steam outlet of the boiler is sequentially connected with a vacuum dryer, a first heat exchange unit, a second heat exchange unit and a third heat exchange unit; the separation unit is connected with a vacuum dryer, the vacuum dryer is further connected with a second heat exchange unit and a third heat exchange unit, and the second heat exchange unit and the third heat exchange unit are both connected with a tail smoke waste heat utilization unit. According to the invention, waste heat recovery and phase change latent heat of products are realized, the heat efficiency of the system is improved, the water consumption in the system is reduced through cyclic utilization of reaction effluent, and the exhaust smoke heat loss of the boiler is reduced through arrangement of a tail smoke waste heat utilization device.

Description

Technical Field

[0001] The invention belongs to the technical field of power plant waste treatment, and in particular relates to a low-water-consumption and energy-saving high-strength gypsum phase-change evaporation system and method. Background Art

[0002] my country's annual output of industrial by-product gypsum is huge, and the cumulative stockpile exceeds 1 billion tons, of which desulfurized gypsum and phosphogypsum account for more than 70%. Desulfurized gypsum is mainly produced by using limestone wet flue gas desulfurization technology to desulfurize tail flue gas to prevent sulfur dioxide emissions in tail flue gas from affecting air quality. Limestone wet flue gas desulfurization technology is particularly suitable for desulfurization of boiler flue gas in thermal power plants, with the advantages of fast reaction speed, high desulfurization efficiency and good comprehensive economic performance. The desulfurization of boiler flue gas in thermal power plants mainly uses lime slurry to react chemically with SO2 or SO3 in flue gas to form calcium sulfate, namely desulfurized gypsum. The by-product desulfurized gypsum produced by flue gas desulfurization in thermal power plants has a variety of uses and is widely used in cement products, fertilizers, ceramics and glass products, construction, soil improvement and other fields. For example, desulfurized gypsum can be used as an additive for ceramic raw materials to control the firing temperature and the fineness and strength of ceramic products. However, due to limited applications, desulfurized gypsum is rarely reused. Therefore, it is necessary to further increase the value of desulfurized gypsum and make use of it as a resource.

[0003] At present, the wet desulfurization process of boiler flue gas in thermal power plants produces a large amount of calcium sulfate dihydrate (also known as desulfurized gypsum). Nowadays, the main way to utilize desulfurized gypsum resources is to prepare calcium sulfate hemihydrate. Calcium sulfate hemihydrate mainly includes α-type calcium sulfate hemihydrate and β-type calcium sulfate hemihydrate. Among them, β-type calcium sulfate hemihydrate, also known as gypsum, has a high porosity and a low strength value obtained during the processing. Compared with α-type calcium sulfate hemihydrate, its by-product economic benefits are poor. α-type calcium sulfate hemihydrate, also known as high-strength building gypsum, has a high density and strength after hardening. It can be used to make high-strength gypsum components, gypsum boards, etc.; it can be used as a material for solid gel processing parts during mechanical processing; when a waterproofing agent is added, its products can also be used in a high humidity environment. Therefore, how to realize the conversion of desulfurized gypsum to high-value α-type calcium sulfate hemihydrate is of great significance for the high-value resource utilization of desulfurized gypsum in thermal power plants.

[0004] In addition, due to the inherent chlorine-containing components in fuel coal and desulfurization quicklime, the chloride ion content in the desulfurized gypsum obtained by wet flue gas desulfurization is often high. Due to the high chloride ion content, the obtained gypsum products often have problems such as easy moisture, low whiteness, and difficulty in meeting market demand. Therefore, the resource utilization potential and economic value of desulfurized gypsum are greatly limited.

[0005] At present, the commonly used technologies for upgrading desulfurized gypsum include atmospheric pressure salt solution method, autoclave method and subcritical hydrothermal method. However, the atmospheric pressure salt solution method and autoclave method cannot effectively remove chloride ions in desulfurized gypsum, and have a series of disadvantages such as high production energy consumption, long cycle, low product strength, and high equipment requirements, which makes industrial promotion difficult. The subcritical hydrothermal method can not only effectively reduce the chloride ion content in desulfurized gypsum, but also has a short production cycle, high reaction product strength, and no secondary pollutants. Therefore, it has a very significant prospect in the technology of green dechlorination and upgrading of industrial by-product gypsum, especially desulfurized gypsum hydrothermal method.

[0006] However, the most important key point of preparing α-type calcium sulfate hemihydrate by hydrothermal method is to achieve thorough drying of the reactants and prevent the temperature from being too low, which will lead to the transformation of α-type calcium sulfate hemihydrate into calcium sulfate dihydrate. At the same time, it is also necessary to reduce the overall energy consumption and water consumption of the system, and achieve efficient utilization of thermal energy and recycling of water. However, the existing technology cannot achieve deep dehydration of the reactants and avoid the crystal transformation of α-type calcium sulfate hemihydrate while ensuring the lowest energy consumption and water consumption of the system. Summary of the invention

[0007] In order to solve the above problems, the present invention provides a low-water consumption and energy-saving high-strength gypsum phase change evaporation drying system and method. It solves the problem of preparing α-type high-strength gypsum from existing desulfurized gypsum, ensures that the prepared high-strength gypsum can be fully dried, and at the same time makes the system low in water consumption and high in energy efficiency.

[0008] The present invention solves the above technical problems through the following technical solutions.

[0009] One of the purposes of the present invention is to provide a low water consumption and energy-saving high-strength gypsum phase change evaporation system, comprising: The high-strength gypsum preparation system is used to prepare desulfurized gypsum to form gypsum slurry, and to separate the gypsum slurry after hydrothermal reaction to obtain the primary product.

[0010] The product waste heat utilization drying system is connected with a vacuum dryer, a first heat exchange unit, a second heat exchange unit and a third heat exchange unit in sequence along the steam outlet direction of the boiler and the steam outlet of the boiler; the high-strength gypsum preparation system is connected with the vacuum dryer, and the vacuum dryer is also connected with the second heat exchange unit and the third heat exchange unit respectively, and the second heat exchange unit and the third heat exchange unit are both connected with a tail flue gas waste heat utilization unit, and the tail flue gas waste heat utilization unit is connected to the boiler.

[0011] Among them, the vacuum dryer uses steam to phase-change evaporate the primary product to obtain α-type hemihydrate calcium sulfate, first steam and steam after heat exchange. The first heat exchange unit forms first hot air after heat exchange on the α-type hemihydrate calcium sulfate to obtain high-strength gypsum; the second heat exchange unit exchanges heat between the first hot air and the first steam to form first condensed water and second hot air. The third heat exchange unit is used to heat exchange the second hot air to form boiler combustion air and to heat exchange the steam after heat exchange to form second condensed water. The tail flue gas waste heat utilization unit heats the first condensed water and the second condensed water and then transports them to the boiler to increase the boiler feed water temperature; the primary product is phase-changed evaporated in a circulation manner to form steam phase change latent heat and flue gas waste heat.

[0012] Furthermore, the above-mentioned low-water consumption and energy-saving high-strength gypsum phase change evaporation system, along the separation direction of gypsum, the high-strength gypsum preparation system includes a desulfurized gypsum silo, a gypsum slurry mixing tank, a hydrothermal reactor and a separation unit connected in sequence; the separation unit includes a primary separation unit and a secondary separation unit. Along the separation direction of gypsum, the hydrothermal reactor is connected to the primary separation unit, the primary separation unit is connected to the secondary separation unit, and the secondary separation unit is connected to the vacuum dryer.

[0013] Furthermore, in the above-mentioned low-water consumption and energy-saving high-strength gypsum phase change drying system, the flue gas outlet of the boiler is connected to the vacuum dryer through a first pipe, the first pipe is connected to a sewage branch pipe, and a sewage valve is provided on the sewage branch pipe. The first pipe is also connected to the hydrothermal reactor through a branch pipe, and the first pipe located behind the branch pipe along the steam direction of the boiler is also provided with a first regulating valve and a temperature monitor B, and a reagent unit is provided on the boiler.

[0014] Furthermore, in the above-mentioned low-water consumption and energy-saving high-strength gypsum phase change evaporation and drying system, the first heat exchange unit is provided with a first inlet, a second inlet, a first outlet and a second outlet. The first inlet of the first heat exchange unit is connected to the vacuum dryer, the second inlet is connected to the combustion air of the boiler, the first outlet is connected to the finished product warehouse, and the second outlet is connected to the second heat exchange unit.

[0015] Furthermore, in the above-mentioned low-water consumption and energy-saving high-strength gypsum phase change evaporation and drying system, the second heat exchange unit is provided with a third inlet, a fourth inlet, a third outlet and a fourth outlet, the third inlet is connected to the second outlet, the fourth inlet is connected to the vacuum dryer, the third outlet is connected to the third heat exchange unit, and the fourth outlet is connected to the adaptive desalination and desolidification unit.

[0016] Furthermore, in the above-mentioned low-water-consumption and energy-saving high-strength gypsum phase change evaporation and drying system, the third heat exchange unit is provided with a fifth inlet, a sixth inlet, a fifth outlet and a sixth outlet, the fifth inlet is connected to the third outlet, the sixth inlet is connected to the vacuum dryer, the fifth outlet is connected to a water storage tank, and the sixth outlet is connected to a boiler; the water storage tank is provided with a seventh inlet, an eighth inlet, and a seventh outlet, the seventh inlet is connected to the fifth outlet, the eighth inlet is connected to the adaptive desalination and desolidification unit, the seventh outlet is connected to the tail flue gas waste heat utilization unit, and the flue gas waste heat utilization unit is connected to the boiler through a water feed pump.

[0017] Furthermore, in the above-mentioned low-water-consumption and energy-saving high-strength gypsum phase change evaporation and drying system, the vacuum dryer is provided with a ninth inlet, a tenth inlet, an eighth outlet, a ninth outlet and a tenth outlet, the ninth inlet is connected to the separation unit, the tenth inlet is connected to the inlet of the first pipeline, the eighth outlet is connected to the first inlet, the ninth outlet is connected to the third inlet, and the tenth outlet is connected to the fifth inlet; the flue gas waste heat utilization unit is provided with a flue gas inlet pipe, the flue gas inlet pipe is connected to the flue gas at the tail of the boiler, and the flue gas waste heat utilization unit is provided with a flue gas outlet pipe for discharging flue gas.

[0018] Furthermore, in the above-mentioned low-water consumption and energy-saving high-strength gypsum phase change evaporation system, a flue gas waste heat utilization unit is provided with a flue gas inlet pipe, the flue gas inlet pipe is connected to the flue gas at the tail end of the boiler, and the flue gas waste heat utilization unit is provided with a flue gas outlet pipe for discharging flue gas.

[0019] Furthermore, the above-mentioned low-water consumption and energy-saving high-strength gypsum phase change evaporation system has a dryness detector at the first outlet, and a temperature monitor A is provided on the hydrothermal reactor, wherein the temperature monitor A and the feed water pump are both connected to the first signal control system, and the temperature of the hydrothermal reactor is monitored by the temperature monitor A to control the water supply of the feed water pump to the boiler; the boiler, the temperature monitor B, the dryness detector and the regulating valve are all connected to the second signal control system, and the temperature of the vacuum dryer is monitored by the temperature monitor B to control the coal burning amount of the boiler, and the dryness detector monitors the water content of the primary product for phase change evaporation to control the opening of the first regulating valve.

[0020] Furthermore, in the above-mentioned low-water consumption and energy-saving high-strength gypsum phase change evaporation system, the gypsum slurry mixing tank is connected to a dosing unit, the dosing unit and the adaptive desalination and desolidification unit are connected through a dosing branch pipe, and a second regulating valve is provided on the dosing branch pipe. The desulfurized gypsum silo and the adaptive desalination and desolidification unit are connected through a regulating pipe, and a third regulating valve is provided on the regulating pipe.

[0021] The second object of the present invention is a low-water consumption and energy-saving high-strength gypsum phase change drying method, based on the low-water consumption and energy-saving high-strength gypsum phase change drying system, comprising the following steps: The desulfurized gypsum is mixed in the high-strength gypsum preparation system to form gypsum slurry, which enters the hydrothermal reactor for hydrothermal reaction at a reaction temperature of 90°C to 200°C. After the reaction, the slurry is initially separated by a separation unit to obtain the primary product and separation water, which enters the high-strength gypsum preparation system for recycling; The primary product enters the vacuum dryer, and the boiler steam outlet is connected to the vacuum dryer. The steam generated by the boiler is used as the drying medium of the vacuum dryer to dry the primary product at a drying temperature of 90°C to 150°C. α-type calcium sulfate hemihydrate, the first steam, and steam after heat exchange are obtained by drying; α-type hemihydrate calcium sulfate enters the first heat exchange unit, and the boiler fuel air required by the boiler is used as the heat exchange medium of the first heat exchange unit. The α-type hemihydrate calcium sulfate is heat exchanged and cooled by the first heat exchange unit to obtain high-strength gypsum and first hot air, and the first hot air enters the second heat exchange unit; The first steam enters the second heat exchange unit, and the first hot air is used as the heat exchange medium of the second heat exchange unit. The first steam is heat exchanged and cooled by the second heat exchange unit to obtain the second hot air and the first condensed water. The second hot air enters the third heat exchange unit, and the first condensed water enters the tail flue gas waste heat utilization unit. The steam after heat exchange enters the third heat exchange unit, and the second hot air is used as the heat exchange medium of the third heat exchange unit. The steam after heat exchange is cooled by the third heat exchange unit to obtain second condensed water and boiler combustion air. The boiler combustion air enters the boiler, and the second condensed water enters the tail flue gas waste heat utilization unit; The tail flue gas waste heat utilization unit uses the tail flue gas of the boiler as the heat exchange medium, heats the first condensed water and the second condensed water, and then transmits them to the boiler to increase the feed water temperature of the boiler; Thus, a circulation mode of steam phase change latent heat and flue gas waste heat is formed to phase change and evaporate the primary product to obtain high-strength gypsum.

[0022] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a low-water-consumption and energy-saving high-strength gypsum phase-change evaporation system, comprising a high-strength gypsum preparation system and a product waste heat utilization drying system. After the high-strength gypsum preparation system mixes and reacts the gypsum, a slurry is formed, and a primary product is obtained by preliminary separation through a separation unit. The primary product is subjected to phase-change evaporation by using steam from a boiler through a vacuum dryer to obtain α-type hemihydrate calcium sulfate, a first steam, and steam after heat exchange, thereby achieving full drying of the α-type hemihydrate calcium sulfate, deep dehydration of the reactant, and avoiding the conversion of the α-type hemihydrate calcium sulfate to dihydrate calcium sulfate due to excessively low temperature. At the same time, during the phase-change evaporation process, the first steam generated by the primary product is heat-exchanged by a second heat exchange unit to form first condensed water and steam after heat exchange formed by heat exchange of boiler steam. The second condensed water is formed by heat exchange in the third unit, which makes full use of the phase change latent heat of steam. The tail flue gas waste heat utilization unit uses the tail flue gas waste heat to exchange heat, thereby increasing the boiler feed water temperature. In the phase change evaporation process, the reaction water is recycled to reduce the water consumption in the system, ensuring that the prepared high-strength gypsum can be fully dried, while making the system low in water consumption and high in energy efficiency. Secondly, the heat exchange medium used by the first heat exchange unit for heat exchange on α-type hemihydrate calcium sulfate is air, and the first hot air is formed after heat exchange, and continues to exchange heat through the second heat exchange unit and the third heat exchange unit in turn to form boiler combustion air, providing the necessary conditions for boiler combustion, realizing the waste heat recovery of the product and the phase change latent heat, and improving the thermal efficiency of the system. According to the present invention, after the desulfurized gypsum is transported, blended, reacted and separated step by step by the high-strength gypsum preparation system, the residual heat of the product is used to form steam phase change latent heat and flue gas residual heat in a circulation manner to phase-change evaporate the initial product, thereby improving the thermal efficiency of the system, and reducing the water consumption in the system by recycling the reaction water, ensuring that the prepared high-strength gypsum can be fully dried, while making the system low in water consumption and high in energy efficiency.

[0023] The present invention realizes precise control of boiler load: in the present invention, the changes of boiler load, main steam temperature and boiler fuel amount are precisely controlled by the temperature of the hydrothermal reactor, the temperature of the vacuum dryer and the dryness of the product at the vacuum dryer outlet, so that the boiler load changes in real time with the reaction conditions, avoiding energy loss caused by high or too high boiler load. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic structural diagram of the high-strength gypsum phase change evaporation system of the present invention.

[0025] Illustration Description: 1. Desulfurized gypsum silo, 2. Gypsum slurry mixing tank, 3. Hydrothermal reactor, 4. Primary separation unit, 5. Secondary separation unit, 6. Temperature monitor A, 7. Temperature monitor B, 8. Finished product warehouse, 9. First heat exchange unit, 10. Dryness detector, 11. Vacuum dryer, 12. Dosing unit, 13. Adaptive desalination and desolidification unit, 14. Second heat exchange unit, 15. Boiler, 16. Feed water pump, 17. Flue gas waste heat utilization unit, 18. Water storage tank, 19. Third heat exchange unit, 20. Agent unit, V1. First regulating valve, V2. Second regulating valve, V3. Third regulating valve, V4. Drain valve. DETAILED DESCRIPTION

[0026] 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.

[0027] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Certain words are used in the present invention to refer to specific components. Those skilled in the art should understand that technicians will use different nouns to refer to the same component. The present invention does not distinguish between components by the difference in nouns, but by the difference in the functions of the components. As mentioned throughout the specification and claims, "including" is an open term and should be understood as "including but not limited to".

[0028] At present, the commonly used technologies for upgrading desulfurized gypsum include atmospheric pressure salt solution method, autoclave method and subcritical hydrothermal method. However, the atmospheric pressure salt solution method and autoclave method cannot effectively remove chloride ions in desulfurized gypsum, and have a series of disadvantages such as high production energy consumption, long cycle, low product strength, and high equipment requirements, which makes industrial promotion difficult. The subcritical hydrothermal method can not only effectively reduce the chloride ion content in desulfurized gypsum, but also has a short production cycle, high reaction product strength, and no secondary pollutants. Therefore, it has a very significant prospect in the technology of green dechlorination and upgrading of industrial by-product gypsum, especially desulfurized gypsum hydrothermal method.

[0029] The most important key point of the existing hydrothermal method for preparing α-type calcium sulfate hemihydrate is to achieve thorough drying of the reactants and prevent the temperature from being too low, which may lead to the conversion of α-type calcium sulfate hemihydrate into calcium sulfate dihydrate. At the same time, it is also necessary to reduce the overall energy consumption and water consumption of the system, and achieve efficient utilization of thermal energy and recycling of water. However, the existing technology cannot achieve deep dehydration of the reactants and avoid the crystal transformation of α-type calcium sulfate hemihydrate while ensuring the lowest energy consumption and water consumption of the system.

[0030] Based on the above problems, the present invention provides a low water consumption and energy-saving high-strength gypsum phase change evaporation system, such as Figure 1 As shown, including: The high-strength gypsum preparation system is used to prepare desulfurized gypsum to form gypsum slurry, and to separate the gypsum slurry after hydrothermal reaction to obtain the primary product.

[0031] The product waste heat utilization drying system includes a boiler 15, along the steam outlet direction of the boiler 15, the steam outlet of the boiler 15 is sequentially connected to a vacuum dryer 11, a first heat exchange unit 9, a second heat exchange unit 14 and a third heat exchange unit 19; the high-strength gypsum preparation system is connected to the vacuum dryer 11, and the vacuum dryer 11 is also respectively connected to the second heat exchange unit 14 and the third heat exchange unit 19, the second heat exchange unit 14 and the third heat exchange unit 19 are both connected to a tail flue gas waste heat utilization unit 17, and the tail flue gas waste heat utilization unit 17 is connected to the boiler 15.

[0032] Among them, the vacuum dryer 11 uses steam to phase-change evaporate the primary product to obtain α-type hemihydrate calcium sulfate, first steam and steam after heat exchange. The first heat exchange unit 9 forms a first hot air after heat exchange on the α-type hemihydrate calcium sulfate to obtain high-strength gypsum; the second heat exchange unit 14 exchanges heat between the first hot air and the first steam to form a first condensed water and a second hot air. The third heat exchange unit 19 is used to heat exchange the second hot air to form boiler combustion air and to heat exchange the steam after heat exchange to form a second condensed water. The tail flue gas waste heat utilization unit 17 heats the first condensed water and the second condensed water and transports them to the boiler 15 to increase the feed water temperature of the boiler 15, thereby forming a circulation method of steam phase change latent heat and flue gas waste heat to phase-change evaporate the primary product.

[0033] The present invention provides a low-water consumption and energy-saving high-strength gypsum phase change evaporation system. The high-strength gypsum preparation system transports, mixes, reacts and separates desulfurized gypsum step by step to obtain an initial product. The waste heat of the product is utilized in a drying system. The gypsum is phase-changed and evaporated in a circulation manner using phase change latent heat and flue gas waste heat to obtain α-type calcium sulfate hemihydrate, that is, high-strength gypsum. Among them, after the desulfurized gypsum is prepared and reacted with the high-strength gypsum preparation system, a slurry is formed, which enters the hydrothermal reactor 3 for hydrothermal reaction, and is initially separated by the separation unit to obtain the primary product. The primary product is phase-changed and evaporated by the steam of the boiler 15 through a vacuum dryer to obtain α-type calcium sulfate hemihydrate, the first steam and the steam after heat exchange, so as to achieve sufficient drying of the α-type calcium sulfate hemihydrate and deep dehydration of the reactants to avoid the conversion of the α-type calcium sulfate hemihydrate to calcium sulfate dihydrate due to too low temperature, so as to obtain high-strength gypsum; at the same time, during the phase-change evaporation, the first steam generated by the primary product is heat-exchanged by the second heat exchange unit to form the first condensed water, and the steam after heat exchange formed by the heat exchange of the furnace steam is heat-exchanged by the third unit to form the second condensed water, so that the phase change latent heat of the steam is fully utilized, and the heat exchange of the tail flue gas waste heat of the boiler 15 is carried out by the tail flue gas waste heat utilization unit to increase the boiler feed water temperature; during the phase-change evaporation, the water consumption in the system is reduced by recycling the reaction water. It ensures that the prepared high-strength gypsum can be fully dried, and at the same time, the system has low water consumption and high energy efficiency; secondly, the heat exchange medium used by the first heat exchange unit for heat exchange of α-type hemihydrate calcium sulfate is air, and the first hot air is formed after heat exchange, and then passes through the second heat exchange unit and the third heat exchange unit in sequence to continue heat exchange to form boiler combustion air, which provides the necessary conditions for boiler combustion, realizes the product's waste heat recovery and phase change latent heat, and improves the thermal efficiency of the system. After the high-strength gypsum preparation system transports, mixes, reacts and separates the desulfurized gypsum step by step, the product waste heat uses the drying system to form steam phase change latent heat and flue gas waste heat in a cyclic manner to phase change evaporate the initial product, thereby improving the thermal efficiency of the system, and by recycling the reaction water, the water consumption in the system is reduced, ensuring that the prepared high-strength gypsum can be fully dried, and at the same time, the system has low water consumption and high energy efficiency.

[0034] The invention is further described below through specific examples.

[0035] Example A low water consumption and energy-saving high-strength gypsum phase change evaporation system, such as Figure 1 As shown, including: The high-strength gypsum preparation system is used to prepare desulfurized gypsum to form gypsum slurry, and to separate the gypsum slurry after hydrothermal reaction to obtain the primary product.

[0036] The product waste heat utilization drying system utilizes the phase change latent heat and the flue gas waste heat in a circulation manner to phase change and evaporate the gypsum to form α-type hemihydrate calcium sulfate; the product waste heat utilization drying system includes a boiler 15, and along the steam outlet direction of the boiler 15, the boiler 15 is sequentially connected with a vacuum dryer 11, a first heat exchange unit 9, a second heat exchange unit 14 and a third heat exchange unit 19; the high-strength gypsum preparation system is connected with the vacuum dryer 11, and the vacuum dryer 11 is also respectively connected with the second heat exchange unit 14 and the third heat exchange unit 19, and the second heat exchange unit 14 and the third heat exchange unit 19 are both connected with a tail flue gas waste heat utilization unit 17, and the tail flue gas waste heat utilization unit 17 is connected with the boiler 15. Among them, the vacuum dryer 11 uses steam to phase-change evaporate the initial product to obtain α-type calcium sulfate hemihydrate, the first steam and the steam after heat exchange. The first heat exchange unit 9 forms the first hot air after heat exchange with the α-type calcium sulfate hemihydrate; the second heat exchange unit 14 exchanges the first hot air and the first steam to form the first condensed water and the second hot air. The third heat exchange unit 19 is used to heat the second hot air to form boiler combustion air and to heat the steam after heat exchange to form the second condensed water. The tail flue gas waste heat utilization unit 17 heats the first condensed water and the second condensed water and then transports them to the boiler 15 to increase the feed water temperature of the boiler 15, thereby forming a circulation mode of steam phase change latent heat and flue gas waste heat to phase-change evaporate the initial product to obtain α-type calcium sulfate hemihydrate.

[0037] It should be noted that the vacuum dryer 11 mainly achieves the drying of the initial product by lowering the boiling point of water. The boiler 15 is a soft water boiler. The steam generated by the boiler 15 is used as the drying medium of the vacuum dryer 11 to dry the initial product. However, under vacuum conditions, the boiling point of water can be reduced to 80°C, 60°C or even 40°C, which allows the water to begin to evaporate at a lower temperature to obtain a solid phase product, thereby achieving sufficient drying of α-type calcium sulfate hemihydrate and deep dehydration of the reactants to avoid the conversion of α-type calcium sulfate hemihydrate to calcium sulfate dihydrate due to too low a temperature.

[0038] The heat exchange medium of the first heat exchange unit 9 is the boiler fuel air required by the boiler 15. The fuel air is the air required for combustion. The α-type calcium sulfate hemihydrate dried out from the vacuum dryer 11 has a certain temperature. The temperature generated during the drying process of the α-type calcium sulfate hemihydrate is used to exchange the fuel air to form the first hot air, thereby recovering a portion of the heat of the solid. The α-type calcium sulfate hemihydrate is condensed and cooled to obtain high-strength gypsum.

[0039] After the first hot air enters the second heat exchange unit 14, it serves as the heat exchange medium of the second heat exchange unit 14 to exchange heat with the first steam generated in the phase change evaporation process of the primary product to form second hot air. After the first hot air exchanges heat with the first steam, it condenses the first steam to generate first condensed water.

[0040] After the second hot air enters the third heat exchange unit 19, it acts as the heat exchange medium of the third heat exchange unit 19 to exchange heat with the steam after heat exchange in the vacuum dryer 11 to form boiler combustion air. The third heat exchange unit 19 is connected to the boiler 15, and the boiler combustion air enters the boiler 15 to provide the necessary conditions for combustion. The steam after heat exchange is condensed through heat exchange to produce the second condensed water.

[0041] The tail flue gas waste heat utilization unit 17 is connected to the tail flue gas of the boiler. The first condensed water and the second condensed water are exchanged with the tail flue gas waste heat of the boiler 15 through the tail flue gas waste heat utilization unit 17, and the first condensed water and the second condensed water are heated, and the heated water is transported to the boiler 15, thereby increasing the feed water temperature of the boiler 15. The reaction water is recycled during the phase change evaporation process, thereby reducing the water consumption in the system, ensuring that the prepared high-strength gypsum can be fully dried, and at the same time making the system low in water consumption and high in energy efficiency.

[0042] In a specific embodiment, along the separation direction of gypsum, the high-strength gypsum preparation system includes a desulfurized gypsum silo 1, a gypsum slurry preparation tank 2, a hydrothermal reactor 3 and a separation unit connected in sequence; the separation unit includes a primary separation unit 4 and a secondary separation unit 5, and along the separation direction of gypsum, the hydrothermal reactor 3 is connected to the primary separation unit 4, the primary separation unit 4 is connected to the secondary separation unit 5, and the secondary separation unit 5 is connected to a vacuum dryer 11. In the present invention, after the post-reaction slurry is preliminarily separated by the primary separation unit 4 and the secondary separation unit 5, the solid phase product enters the vacuum dryer 11 for drying, wherein the separated water of the primary separation unit 4 and the secondary separation unit 5 is recycled, thereby realizing the recycling of water and reducing the water consumption of the entire system.

[0043] In a specific embodiment, the steam outlet direction of the boiler 15 is connected to the vacuum dryer 11 through a first pipe, the first pipe is connected to a sewage branch pipe, and a sewage valve V4 is provided on the sewage branch pipe. The first pipe is also connected to the hydrothermal reactor 3 through a branch pipe. The first pipe located along the steam direction of the boiler 15 and behind the branch pipe is also provided with a first regulating valve V1 and a temperature monitor B7. The boiler 15 is provided with a reagent unit 20. In the present invention, the boiler 15 is a soft water boiler, and the soft water boiler can be softened by the reagent unit 20. The steam outlet of the boiler 15 is divided into two paths, one path enters the hydrothermal reactor 3, and the other path enters the vacuum dryer 11 through the first pipeline. The temperature of the steam entering the vacuum dryer 11 is monitored by the temperature monitor B7, and the steam flow of the boiler 15 is adjusted by the first regulating valve V1, thereby controlling the evaporation temperature of the vacuum dryer 11 and the dryness of the product; the first pipeline is connected with a sewage branch pipe, and the sewage branch pipe is provided with a sewage valve V4, which discharges sewage from the steam outlet of the boiler 15, and the opening of the sewage valve V4 is controlled by the sewage valve V4.

[0044] In a specific embodiment, the first heat exchange unit 9 is provided with a first inlet, a second inlet, a first outlet and a second outlet. The first inlet of the first heat exchange unit 9 is connected to the vacuum dryer 11, the second inlet is connected to the combustion air of the boiler 15, the first outlet is connected to the finished product warehouse 8, and the second outlet is connected to the second heat exchange unit 14. In the present invention, the heat exchange medium of the first heat exchange unit 9 is the combustion air of the boiler 15, and the combustion air is input into the first heat exchange unit 9 through the second inlet. The vacuum dryer 11 performs phase change evaporation on the initial product, and the solid phase product produced by drying enters the first heat exchange unit 9 through the first inlet. After the first heat exchange unit 9 performs heat exchange on the solid phase product, α-type calcium sulfate hemihydrate is obtained, and the α-type calcium sulfate hemihydrate is sent to the finished product warehouse 8 through the first outlet. The first hot air produced by heat exchange enters the second heat exchange unit 14 through the second outlet.

[0045] In a specific embodiment, the second heat exchange unit 14 is provided with a third inlet, a fourth inlet, a third outlet and a fourth outlet, the third inlet is connected to the second outlet, the fourth inlet is connected to the vacuum dryer 11, the third outlet is connected to the third heat exchange unit 19, and the fourth outlet is connected to the adaptive desalination and desolidification unit 13. The first steam generated by the vacuum dryer 11 drying the primary product enters the second heat exchange unit 14 through the fourth inlet, and the first hot air generated by the first heat exchange unit 9 enters the second heat exchange unit 14 through the third inlet, the second heat exchange unit 14 condenses the first steam to generate the first condensed water, the first hot air is heat exchanged to form the second hot air, enters the adaptive desalination and desolidification unit 13, separates the solid residue from the first condensed water, and realizes the removal of chlorine, the separated water enters the water storage tank 18, and then enters the tail flue gas waste heat utilization unit 17, the tail flue gas waste heat utilization unit 17 exchanges heat with the condensed water, increases the feed water temperature of the boiler 15, makes full use of the phase change latent heat of the steam at the outlet of the vacuum dryer 11, and performs efficient heat recovery.

[0046] In a specific embodiment, the third heat exchange unit 19 is provided with a fifth inlet, a sixth inlet, a fifth outlet and a sixth outlet, the fifth inlet is connected to the third outlet, the sixth inlet is connected to the vacuum dryer 11, the fifth outlet is connected to the water storage tank 18, and the sixth outlet is connected to the boiler 15; the water storage tank 18 is provided with a seventh inlet, an eighth inlet, and a seventh outlet, the seventh inlet is connected to the fifth outlet, the eighth inlet is connected to the adaptive desalination and desolidification unit 13, the seventh outlet is connected to the tail flue gas waste heat utilization unit 17, and the flue gas waste heat utilization unit 17 is connected to the boiler 15 through the feed water pump 16. Among them, the third heat exchange unit 19 heats the steam after heat exchange to form the second condensed water, the second condensed water enters the water storage tank 18 and enters the tail flue gas waste heat utilization unit 17 to heat the condensed water, and the feed water temperature of the boiler 15 is increased; the second hot air is heat-exchanged by the third heat exchange unit 19 to form boiler combustion air, and the boiler combustion air is input into the boiler 15 to provide the necessary conditions for combustion.

[0047] In summary, the present invention recovers the waste heat of solid and liquid products in multiple stages through the first heat exchange unit, the second heat exchange unit and the third heat exchange unit, utilizes the phase change latent heat of the steam at the outlet of the vacuum dryer to phase-change evaporate the gypsum, and efficiently recovers heat, thereby improving the thermal efficiency of the system.

[0048] In a specific embodiment, the vacuum dryer 11 is provided with a ninth inlet, a tenth inlet, an eighth outlet, a ninth outlet and a tenth outlet, the ninth inlet is connected to the separation unit, the tenth inlet is connected to the inlet of the first pipeline, the eighth outlet is connected to the first inlet, the ninth outlet is connected to the third inlet, and the tenth outlet is connected to the fifth inlet. The flue gas waste heat utilization unit 17 is provided with a flue gas inlet pipe, the flue gas inlet pipe is connected to the flue gas at the tail of the boiler 15, and the flue gas waste heat utilization unit 17 is provided with a flue gas outlet pipe for discharging flue gas. In the present invention, the primary product is dried by the vacuum dryer, and the solid phase product produced by drying is heat exchanged by the first heat exchange unit 9 to obtain α-type hemihydrate calcium sulfate; the steam produced by drying enters the second heat exchange unit 14 to heat the boiler 15 combustion air to form the first hot air, and the steam produced by the boiler 15 enters the third heat exchange unit 19 after heat exchange with the steam obtained after circulating drying in the vacuum dryer 11. The flue gas waste heat utilization unit 17 is provided with a flue gas inlet pipe, the flue gas inlet pipe is connected to the flue gas at the tail of the boiler 15, and the flue gas waste heat utilization unit 17 is provided with a flue gas outlet pipe for discharging flue gas. In the present invention, the tail flue gas waste heat utilization unit 17 utilizes the high temperature of the tail flue gas of the boiler 15 to heat the first condensed water and the second condensed water, thereby increasing the feed water temperature of the boiler 15 and fully recovering the waste heat of the tail flue gas of the boiler. The flue gas outlet pipe discharges the flue gas after waste heat utilization. The combustion air of the boiler 15 enters the boiler 15 after absorbing heat through the first heat exchange unit 9, the second heat exchange unit 14 and the third heat exchange unit 19 to provide the air required for boiler combustion.

[0049] In a specific embodiment, a dryness detector 10 is provided at the first outlet, and a temperature monitor A 6 is provided on the hydrothermal reactor 3, wherein the temperature monitor A 6 and the feed water pump 16 are both connected to the first control system by signals, and the temperature of the hydrothermal reactor 3 is monitored by the temperature monitor A 6 to control the water supply of the feed water pump 16 to the boiler 15.

[0050] The temperature monitor A 6 and the water supply pump 16 are interlocked. The reaction temperature of the hydrothermal reactor 3 is monitored by the temperature monitor A 6, and the signal is transmitted to the first control system. The first control system controls the water supply amount of the water supply pump 16 after comparative analysis.

[0051] In a specific embodiment, the boiler 15, the temperature monitor B7, the dryness detector 10 and the regulating valve V1 are all connected to the second control system by signal. The dryness detector 10 monitors the water content of the initial product in the vacuum dryer 11 by phase change evaporation, controls the opening of the first regulating valve V1, and then controls the flow of steam from the boiler 15 into the vacuum dryer 11, and controls the drying temperature of the vacuum dryer 11. The dryness detector 10, the temperature monitor B7 and the first regulating valve V1 are interlocked to control the steam input of the boiler 15. The dryness detector 10 measures the dryness of the initial product and transmits the signal to the second control system. The second control system controls the opening of the first regulating valve V1 after comparative analysis, adjusts the steam flow entering the vacuum dryer 11, and adjusts the temperature of the product dryness.

[0052] In a specific embodiment, the gypsum slurry preparation tank 2 is connected to a dosing unit 12, and the dosing unit 12 and the adaptive desalination and desolidification unit 13 are connected through a dosing branch pipe, and a second regulating valve V2 is provided on the dosing branch pipe, and the desulfurized gypsum silo 1 and the adaptive desalination and desolidification unit 13 are connected through a regulating pipe, and a third regulating valve V3 is provided on the regulating pipe. In the present invention, in addition to mixing the gypsum slurry in the gypsum slurry preparation tank 2, the dosing unit 12 also mixes the adaptive desalination and desolidification unit 13 through the dosing branch pipe and the desulfurized gypsum silo 1 to achieve the removal of chlorine in the adaptive desalination and desolidification unit 13, wherein the reagent entering the dosing unit 12 is controlled by the second regulating valve V2, and the desulfurized gypsum entering the desulfurized gypsum silo 1 is controlled by the third regulating valve V3.

[0053] In summary, the present invention sets a multi-stage heat exchange unit to realize the waste heat recovery and phase change latent heat of the product, thereby improving the thermal efficiency of the system. By recycling the reaction water, the water consumption in the system is reduced. And by setting up a tail flue gas waste heat utilization device, the exhaust heat loss of the boiler is reduced. In addition, by setting up a parameter detector and a corresponding control method, the boiler load is accurately controlled to avoid energy loss caused by high or low boiler load.

[0054] A method for performing phase-change evaporation of high-strength gypsum using the low-water consumption and energy-saving high-strength gypsum phase-change evaporation system comprises the following steps: The material in the desulfurized gypsum silo 1 is mixed with water in a certain proportion in the gypsum slurry preparation tank 2, and then enters the hydrothermal reactor 3 for hydrothermal reaction at a reaction temperature of 90°C to 200°C. The slurry after the reaction is initially separated by the primary separation unit 4 and the secondary separation unit 5 to obtain the initial product and separated water, and the liquid product (water) is recycled for gypsum slurry preparation.

[0055] The primary product enters the vacuum dryer 11, and the steam outlet of the boiler 15 is connected to the vacuum dryer 11. The steam generated by the boiler 15 is used as the drying medium of the vacuum dryer 11 to dry the primary product at a drying temperature of 90° C. to 150° C., and α-type calcium sulfate hemihydrate, the first steam and the steam after heat exchange are obtained by drying.

[0056] Among them, the steam required by the hydrothermal reactor 3 and the vacuum dryer 11 comes from the boiler 15, and the first pipeline entering the vacuum dryer 11 is provided with a first regulating valve V1 and a temperature monitor B7, the hydrothermal reactor 3 is provided with a temperature monitor A6 and a temperature monitor B7, and the solid phase product outlet pipeline in the hydrothermal reactor 3 is provided with a dryness detector 10.

[0057] α-type hemihydrate calcium sulfate enters the first heat exchange unit 9, and the boiler fuel air required by the boiler 15 is used as the heat exchange medium of the first heat exchange unit 9. The α-type hemihydrate calcium sulfate is heat exchanged and cooled by the first heat exchange unit 9 to obtain high-strength gypsum and the first hot air. The first hot air enters the second heat exchange unit 14, and the high-strength gypsum enters the finished product warehouse 8; The first steam enters the second heat exchange unit 14, and the first hot air is used as the heat exchange medium of the second heat exchange unit 14. The first steam is heat exchanged and cooled by the second heat exchange unit 14 to obtain the second hot air and the first condensed water. The second hot air enters the third heat exchange unit 19, and the first condensed water enters the sedimentation and filtration device 13 and the desalination device 12 in sequence, and enters the water storage tank 18 after sedimentation, filtration and desalination respectively, and then enters the tail flue gas waste heat utilization unit 17; The steam after heat exchange enters the third heat exchange unit 19, and the second hot air is used as the heat exchange medium of the third heat exchange unit 19. The third heat exchange unit 19 performs heat exchange and cooling on the steam after heat exchange to obtain second condensed water and boiler combustion air. The boiler combustion air enters the boiler 15 to provide air required for boiler combustion. The second condensed water enters the water storage tank 18 and then enters the tail flue gas waste heat utilization unit 17. The tail flue gas waste heat utilization unit 17 uses the tail flue gas of the boiler 15 as a heat exchange medium, heats the first condensed water and the second condensed water, and then transports the heated water to the boiler 15 through the water pump 16, thereby increasing the feed water temperature of the boiler 15; In the system, the dryness detector 10 is interlocked with the first regulating valve V1. When the dryness detector 10 measures that the product dryness is low, the regulating valve V1 is controlled to increase its opening, thereby increasing the steam flow rate of the boiler steam entering the vacuum dryer 11, controlling the temperature of the vacuum dryer 11, and thereby increasing the dryness of the initial product; the temperature monitor A 6 is interlocked with the feed water pump 16. When the temperature measured by the temperature monitor A 6 is lower than the set value, the feed water pump 16 is controlled to increase the flow rate, thereby increasing the steam flow rate entering the hydrothermal reactor 3, thereby increasing the temperature of the hydrothermal reactor; the temperature monitor B 7 controls the boiler fuel amount. When the temperature of the vacuum dryer 11 is lower than the set value, the boiler fuel amount is increased, the steam temperature is increased, and thereby the temperature of the vacuum dryer 11 is increased.

[0058] Thus, a circulation mode of steam phase change latent heat and flue gas waste heat is formed to phase change and evaporate the primary product to obtain high-strength gypsum.

[0059] 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.

[0060] Obviously, those skilled in the art can 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 low water consumption and energy-saving high-strength gypsum phase change evaporation system, characterized in that: include: High-strength gypsum preparation system, used to prepare desulfurized gypsum to form gypsum slurry, and to separate the gypsum slurry after hydrothermal reaction to obtain the primary product; A product waste heat utilization drying system comprises a boiler (15), wherein a vacuum dryer (11), a first heat exchange unit (9), a second heat exchange unit (14) and a third heat exchange unit (19) are sequentially connected along the steam outlet direction of the boiler (15) and the steam outlet of the boiler (15); the high-strength gypsum preparation system is connected to the vacuum dryer (11), the vacuum dryer (11) is further connected to the second heat exchange unit (14) and the third heat exchange unit (19), respectively; the second heat exchange unit (14) and the third heat exchange unit (19) are both connected to a tail flue gas waste heat utilization unit (17), and the tail flue gas waste heat utilization unit (17) is connected to the boiler (15); The vacuum dryer (11) uses steam to perform phase change evaporation on the primary product to obtain α-type calcium sulfate hemihydrate, first steam, and steam after heat exchange. The first heat exchange unit (9) performs heat exchange on the α-type calcium sulfate hemihydrate to form first hot air to obtain high-strength gypsum. The second heat exchange unit (14) performs heat exchange on the first hot air and the first steam to form first condensed water and second hot air. The third heat exchange unit (19) is used to perform heat exchange on the second hot air to form boiler combustion air and to perform heat exchange on the steam after heat exchange to form second condensed water. The tail flue gas waste heat utilization unit (17) heats the first condensed water and the second condensed water and then transports them to the boiler (15), thereby increasing the feed water temperature of the boiler (15), thereby forming a circulation mode of steam phase change latent heat and flue gas waste heat to perform phase change evaporation on the primary product.

2. The low water consumption and energy-saving high-strength gypsum phase change evaporation system according to claim 1 is characterized in that: Along the separation direction of gypsum, the high-strength gypsum preparation system comprises a desulfurized gypsum silo (1), a gypsum slurry preparation tank (2), a hydrothermal reactor (3) and a separation unit which are connected in sequence; the separation unit comprises a primary separation unit (4) and a secondary separation unit (5); along the separation direction of gypsum, the hydrothermal reactor (3) is connected to the primary separation unit (4), the primary separation unit (4) is connected to the secondary separation unit (5), and the secondary separation unit (5) is connected to a vacuum dryer (11).

3. The low water consumption and energy-saving high-strength gypsum phase change evaporation system according to claim 2 is characterized in that: The steam outlet of the boiler (15) is connected to the vacuum dryer (11) via a first pipeline, the first pipeline is connected to a sewage branch pipe, and the sewage branch pipe is provided with a sewage valve (V4). The first pipeline is also connected to the hydrothermal reactor (3) via a branch pipe. The first pipeline located behind the branch pipe along the steam direction of the boiler (15) is also provided with a first regulating valve (V1) and a temperature monitor B (7). The boiler (15) is provided with a reagent unit (20).

4. The low water consumption and energy-saving high-strength gypsum phase change evaporation system according to claim 3 is characterized in that: The first heat exchange unit (9) is provided with a first inlet, a second inlet, a first outlet and a second outlet; the first inlet of the first heat exchange unit (9) is connected to the vacuum dryer (11), the second inlet is connected to the combustion air of the boiler (15), the first outlet is connected to the finished product bin (8), and the second outlet is connected to the second heat exchange unit (14).

5. The low water consumption and energy-saving high-strength gypsum phase change evaporation system according to claim 4 is characterized in that: The second heat exchange unit (14) is provided with a third inlet, a fourth inlet, a third outlet and a fourth outlet, the third inlet is connected to the second outlet, the fourth inlet is connected to the vacuum dryer (11), the third outlet is connected to the third heat exchange unit (19), and the fourth outlet is connected to the adaptive desalination and desolidification unit (13).

6. The low water consumption and energy-saving high-strength gypsum phase change evaporation system according to claim 5 is characterized in that: The third heat exchange unit (19) is provided with a fifth inlet, a sixth inlet, a fifth outlet and a sixth outlet, the fifth inlet is connected to the third outlet, the sixth inlet is connected to the vacuum dryer (11), the fifth outlet is connected to a water storage tank (18), and the sixth outlet is connected to a boiler (15); the water storage tank (18) is provided with a seventh inlet, an eighth inlet and a seventh outlet, the seventh inlet is connected to the fifth outlet, the eighth inlet is connected to the adaptive desalination and desolidification unit (13), the seventh outlet is connected to a tail flue gas waste heat utilization unit (17), and the flue gas waste heat utilization unit (17) is connected to the boiler (15) via a feed water pump (16).

7. The low water consumption and energy-saving high-strength gypsum phase change evaporation system according to claim 6 is characterized in that: The vacuum dryer (11) is provided with a ninth inlet, a tenth inlet, an eighth outlet, a ninth outlet and a tenth outlet, the ninth inlet is connected to the separation unit, the tenth inlet is connected to the inlet of the first pipeline, the eighth outlet is connected to the first inlet, the ninth outlet is connected to the third inlet, and the tenth outlet is connected to the fifth inlet; the flue gas waste heat utilization unit (17) is provided with a flue gas inlet pipe, the flue gas inlet pipe is connected to the tail flue gas of the boiler (15), and the flue gas waste heat utilization unit (17) is provided with a flue gas outlet pipe for discharging flue gas.

8. The low water consumption and energy-saving high-strength gypsum phase change evaporation system according to claim 3 is characterized in that: A dryness detector (10) is provided at the first outlet, and a temperature monitor A (6) is provided on the hydrothermal reactor (3), wherein the temperature monitor A (6) and the water supply pump (16) are both connected to a first control system by signal, and the temperature of the hydrothermal reactor (3) is monitored by the temperature monitor A (6), and the water supply amount of the water supply pump (16) to the boiler (15) is controlled; the boiler (15), the temperature monitor B (7), the dryness detector (10) and the regulating valve (V1) are all connected to a second signal control system, and the temperature of the vacuum dryer (11) is monitored by the temperature monitor B (7), and the coal burning amount of the boiler (15) is controlled; the dryness detector (10) monitors the water content of the initial product after phase change evaporation, and controls the opening of the first regulating valve (V1).

9. The low water consumption and energy-saving high-strength gypsum phase change evaporation system according to claim 5 is characterized in that: The gypsum slurry mixing tank (2) is connected to a dosing unit (12); the dosing unit (12) and the adaptive desalination and desolidification unit (13) are connected via a dosing branch pipe, on which a second regulating valve (V2) is provided; the desulfurized gypsum silo (1) and the adaptive desalination and desolidification unit (13) are connected via a regulating pipe, on which a third regulating valve (V3) is provided.

10. A low-water-consumption and energy-saving high-strength gypsum phase change drying method, characterized in that: The low-water-consumption and energy-saving high-strength gypsum phase-change evaporation system according to any one of claims 1 to 9 comprises the following steps: The desulfurized gypsum is mixed in the high-strength gypsum preparation system to form a gypsum slurry, which enters the hydrothermal reactor (3) for hydrothermal reaction at a reaction temperature of 90°C to 200°C. After the reaction, the slurry is initially separated in a separation unit to obtain a primary product and separation water, which enters the high-strength gypsum preparation system for recycling; The primary product enters the vacuum dryer (11), and the steam outlet of the boiler (15) is connected to the vacuum dryer (11). The steam generated by the boiler (15) is used as the drying medium of the vacuum dryer (11) to dry the primary product at a drying temperature of 90° C. to 150° C., thereby obtaining α-type calcium sulfate hemihydrate, first steam, and steam after heat exchange; α-type calcium sulfate hemihydrate enters the first heat exchange unit (9), and the boiler fuel air required by the boiler (15) is used as the heat exchange medium of the first heat exchange unit (9). The α-type calcium sulfate hemihydrate is heat exchanged and cooled by the first heat exchange unit (9) to obtain high-strength gypsum and first hot air, and the first hot air enters the second heat exchange unit (14); The first steam enters the second heat exchange unit (14), the first hot air is used as the heat exchange medium of the second heat exchange unit (14), the first steam is heat exchanged and cooled in the second heat exchange unit (14), and second hot air and first condensed water are obtained. The second hot air enters the third heat exchange unit (19), and the first condensed water enters the tail flue gas waste heat utilization unit (17); The steam after heat exchange enters the third heat exchange unit (19), and the second hot air is used as the heat exchange medium of the third heat exchange unit (19). The steam after heat exchange is cooled by the third heat exchange unit (19) to obtain second condensed water and boiler combustion air. The boiler combustion air enters the boiler (15), and the second condensed water enters the tail flue gas waste heat utilization unit (17); The tail flue gas waste heat utilization unit (17) uses the tail flue gas of the boiler (15) as a heat exchange medium, heats the first condensed water and the second condensed water, and then transmits the heat to the boiler (15), thereby increasing the feed water temperature of the boiler (15); Thus, a circulation mode of steam phase change latent heat and flue gas waste heat is formed to phase change and evaporate the primary product to obtain high-strength gypsum.

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