Alpha-type high-strength gypsum drying system based on double-medium boiler

Abstract

The invention belongs to the technical field of power plant waste treatment, and particularly relates to an alpha-type high-strength gypsum drying system based on a double-medium boiler. Comprising a hydrothermal reaction unit and a slurry separation unit which are connected in sequence; a product waste heat utilization drying system comprises a solid phase drying unit, a first heat exchange unit and a boiler, a slurry separation unit is connected with the solid phase drying unit, the solid phase drying unit is connected with the first heat exchange unit and the boiler, a steam outlet of the boiler is connected with a hydrothermal reaction unit, and the first heat exchange unit is connected with the boiler. The solid phase drying unit is further connected with a tail smoke waste heat utilization device. According to the invention, hot air generated by the boiler is used for heat exchange to circularly dry the primary product, so that the alpha-type calcium sulfate hemihydrate is fully dried, the conversion of the alpha-type calcium sulfate hemihydrate to calcium sulfate dihydrate caused by too low temperature is avoided, and water vapor generated by the boiler is used as a hydrothermal reaction medium of the hydrothermal reaction unit; and the desulfurized gypsum is dried in a double-medium circulation manner.

Description

Technical Field

[0001] The invention belongs to the technical field of power plant waste treatment, and in particular relates to an alpha-type high-strength gypsum drying system based on a dual-medium boiler. Background Art

[0002] Coal-fired boiler flue gas contains a large amount of sulfur oxides. At present, limestone wet flue gas desulfurization technology is mainly used to remove sulfur oxides in boiler flue gas. In the process of wet flue gas desulfurization, a large amount of by-product desulfurized gypsum is produced. Since my country's energy consumption is mainly based on coal, the annual amount of desulfurized gypsum can reach 120 million tons. Although the by-product desulfurized gypsum can be used in cement products, construction and other fields, its utilization rate is still very low. Therefore, how to achieve high-value treatment and utilization of desulfurized gypsum has become an important research topic.

[0003] Desulfurized gypsum is mainly calcium sulfate dihydrate. At present, one of the ways to achieve high-value processing and utilization of desulfurized gypsum is to convert it into α-type calcium sulfate hemihydrate. α-type calcium sulfate hemihydrate is also called high-strength building gypsum. After hardening, it has high density and strength. It can be used to make high-strength gypsum components, gypsum boards, etc., and has broad application prospects and development directions. In addition, due to the high chloride ion content in coal, the chloride ion content in desulfurized gypsum exceeds the standard. The high chloride ion content will cause the resulting gypsum products to be prone to moisture, low whiteness, and difficult to meet market demand, which greatly limits the resource utilization potential and economic value of desulfurized gypsum.

[0004] Subcritical hydrothermal method can effectively reduce the chloride ion content in desulfurized gypsum, and has a short production cycle, high reaction product strength, and no secondary pollutants. Therefore, subcritical hydrothermal technology has a very significant prospect in the technology of green dechlorination and quality improvement of industrial by-product gypsum, especially desulfurized gypsum hydrothermal method. However, during subcritical hydrothermal treatment, there are problems such as incomplete drying of desulfurized gypsum and the conversion of α-type calcium sulfate hemihydrate to calcium sulfate dihydrate due to too low temperature. Summary of the invention

[0005] In order to solve the above problems, the present invention provides an α-type high-strength gypsum drying system based on a dual-medium boiler. The system solves the problem that the existing subcritical hydrothermal method is difficult to completely dry the desulfurized gypsum, ensures that the gypsum after the reaction is α-type high-strength gypsum, and at the same time ensures certain conditions to avoid the gypsum from changing its crystal form during the drying process, thereby reducing the product quality.

[0006] The present invention solves the above technical problems through the following technical solutions.

[0007] The present invention provides an α-type high-strength gypsum drying system based on a dual-medium boiler, 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, including a hydrothermal reaction unit and a slurry separation unit connected in sequence.

[0008] The product waste heat utilization drying system uses a dual-medium circulation method of steam and hot air to dry the initial product, including a solid-phase drying unit, a first heat exchange unit and a dual-medium variable-mode boiler. The slurry separation unit is connected to the solid-phase drying unit, and the solid-phase drying unit is connected to the first heat exchange unit and the dual-medium variable-mode boiler. The steam outlet of the dual-medium variable-mode boiler is connected to the hydrothermal reaction unit, and the first heat exchange unit is connected to the combustion air outlet of the dual-medium variable-mode boiler. The solid-phase drying unit is also connected to a tail flue gas waste heat utilization device; wherein the hydrothermal reaction unit uses the steam generated by the dual-medium variable-mode boiler to perform a hydrothermal reaction. The slurry separation unit separates the initial product, and the solid phase drying unit uses the hot air generated by the dual-medium variable operating condition boiler to circulate and dry the initial product to form a solid phase product and a liquid phase product; the first heat exchange unit uses the boiler fuel air to exchange heat with the solid phase product to obtain α-type high-strength gypsum, and increase the boiler fuel air temperature used for combustion in the dual-medium variable operating condition boiler; the tail flue gas waste heat utilization device exchanges heat with the liquid phase product to increase the feed water temperature of the dual-medium variable operating condition boiler, and the steam generated by the dual-medium variable operating condition boiler is used to perform a hydrothermal reaction on the hydrothermal reaction unit, forming a dual-medium circulation method to dry the desulfurized gypsum.

[0009] Furthermore, in the α-type high-strength gypsum drying system based on the dual-medium boiler, the solid phase drying unit is provided with a first inlet, a second inlet, a first outlet and a second outlet, the first inlet is connected to the slurry separation unit, the first outlet is connected to the first heat exchange unit, the second inlet is connected to the air heating outlet of the dual-medium variable-condition boiler, and the second outlet is connected to the air heating inlet of the dual-medium variable-condition boiler through an induced draft fan.

[0010] Furthermore, in the α-type high-strength gypsum drying system based on the dual-medium boiler, a first temperature monitor is provided on the air heating outlet of the dual-medium variable-operating-condition boiler, a dryness detector is provided at the first outlet, the first temperature monitor and the dual-medium variable-operating-condition boiler are connected to a first control system, and the dryness detector and the induced draft fan signal are connected to a second control system.

[0011] Furthermore, in the α-type high-strength gypsum drying system based on the dual-medium boiler, the outlet of the slurry separation unit is connected to an outlet pipeline, a chloride ion monitor is provided on the outlet pipeline, and a first valve is provided on the outlet pipeline behind the chloride ion monitor along the separation direction of the gypsum.

[0012] Furthermore, the α-type high-strength gypsum drying system based on the dual-medium boiler has a bypass branch in the outlet pipeline, a second valve is provided on the bypass branch, the outlet of the bypass branch is connected to the sedimentation and filtration device, the water storage tank and the tail flue gas waste heat utilization device in sequence, and the tail flue gas waste heat utilization device is connected to the water feed inlet of the dual-medium variable operating condition boiler.

[0013] Furthermore, in the α-type high-strength gypsum drying system based on the dual-medium boiler, the chloride ion monitor, the first valve and the second valve signals are connected to a third control system.

[0014] Furthermore, in the α-type high-strength gypsum drying system based on the dual-medium boiler, the water storage tank is also connected to the solid phase drying unit, and a water supply pump is provided between the tail flue gas waste heat utilization device and the water storage tank.

[0015] Furthermore, in the α-type high-strength gypsum drying system based on the dual-medium boiler, a heater is provided between the hydrothermal reaction unit and the dual-medium variable-operating-state boiler, and a second temperature monitor is provided between the heater and the dual-medium variable-operating-state boiler.

[0016] Furthermore, the α-type high-strength gypsum drying system based on the dual-medium boiler, along the separation direction of the gypsum, the high-strength gypsum preparation system includes a desulfurized gypsum silo, a gypsum slurry mixing tank, a hydrothermal reaction unit and a slurry separation unit which are connected in sequence; the gypsum slurry mixing tank is used to form gypsum slurry after mixing the desulfurized gypsum, the hydrothermal reaction unit performs a hydrothermal reaction on the gypsum slurry, and the initial product is separated by the slurry separation unit, and a temperature monitor A is provided on the hydrothermal reaction unit, and the temperature monitor A and the water supply pump signal are connected to a fourth control system.

[0017] Furthermore, in the α-type high-strength gypsum drying system based on the dual-medium boiler, the first heat exchange unit is connected to the finished product warehouse.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides an α-type high-strength gypsum drying system based on a dual-medium boiler, comprising a high-strength gypsum preparation system and a product waste heat utilization drying system. The desulfurized gypsum is prepared by water in a gypsum slurry preparation tank to form gypsum slurry. The gypsum slurry enters a hydrothermal reaction unit to undergo a hydrothermal reaction. Steam generated by a dual-medium variable-operating-mode boiler is used to provide the hydrothermal reaction conditions for the hydrothermal reaction unit. The primary product is separated by a slurry separation unit. The solid-phase drying unit utilizes the hot air generated by the dual-medium variable-operating-mode boiler for heat exchange to circulate and dry the primary product to form a solid-phase product and a liquid-phase product, thereby achieving full drying of the target product. , deeply dehydrate the reactants to avoid the transformation of phase byproducts caused by too low temperature. The heat generated after the solid phase product is dried is exchanged by the first heat exchange unit to obtain α-type high-strength gypsum, and the temperature of the boiler combustion air required for the combustion of the dual-medium variable-condition boiler is increased; the liquid phase product is used as the dual-medium variable-condition boiler feed water, and the liquid phase product is heat exchanged by the tail flue gas waste heat utilization device to increase the dual-medium variable-condition boiler feed water temperature, forming a dual-medium circulation to dry the desulfurized gypsum, ensuring that under the gypsum reaction and drying conditions, the reacted gypsum is dried to α-type high-strength gypsum, which increases the product quality and improves the utilization rate of the desulfurized gypsum.

[0019] The present invention is provided with a hydrothermal reaction unit temperature monitor, a solid phase drying unit temperature monitor and a dryness detector. The temperature of the hydrothermal reaction unit and the solid phase drying unit can be monitored in real time by the temperature monitor, the dryness detector monitors the dryness of the solid phase product, and the flow rate of the induced draft fan is adjusted to achieve precise temperature control of the solid phase product, to ensure that the gypsum reaction and drying conditions reach the set value, to achieve sufficient drying of α-type hemihydrate calcium sulfate, to deeply dehydrate the reactants, and to achieve the preparation of high-strength gypsum. The hydrothermal reaction unit temperature monitor and the solid phase drying unit temperature monitor are used to adjust the load of the dual-medium variable operating condition boiler and the fuel amount of the dual-medium variable operating condition boiler, respectively, to ensure that the dual-medium variable operating condition boiler works under the corresponding load and avoid boiler energy consumption loss. The waste heat in the solid product and the waste heat of the flue gas at the tail of the dual-medium variable operating condition boiler are fully utilized to heat the boiler combustion air and boiler feed water temperature, respectively, which not only reduces the waste of high-quality energy, but also improves the boiler efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the α-type high-strength gypsum drying system based on a dual-medium boiler of the present invention.

[0021] Illustration Description: 1. Desulfurized gypsum silo, 2. Gypsum slurry mixing tank, 3. Third temperature detector, 4. Hydrothermal reaction unit, 5. Slurry separation unit, 6. Heater, 7. First temperature monitor, 8. Solid phase drying unit, 9. Dryness detector, 10. First heat exchange unit, 11. Finished product warehouse, 12. Induced draft fan, 13. Dual-medium variable operating condition boiler, 14. Tail flue gas waste heat utilization device, 15. Feed water pump, 16. Water storage tank, 17. Sedimentation and filtration device, 18. Chloride ion monitor, 19. Second temperature monitor. DETAILED DESCRIPTION

[0022] 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.

[0023] 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".

[0024] Gypsum drying is an important step. If the drying is not thorough, α-calcium sulfate hemihydrate will be transformed into calcium sulfate dihydrate. However, the existing subcritical hydrothermal treatment technology for desulfurized gypsum is difficult to dry the desulfurized gypsum thoroughly.

[0025] Based on the above problems, the present invention provides an α-type high-strength gypsum drying system based on a dual-medium boiler, 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, including a hydrothermal reaction unit 4 and a slurry separation unit 5 connected in sequence.

[0026] The product waste heat utilization drying system includes a solid-phase drying unit 8, a first heat exchange unit 10 and a dual-medium variable operating condition boiler 13, wherein the slurry separation unit 5 is connected to the solid-phase drying unit 8, the solid-phase drying unit 8 is connected to the first heat exchange unit 10 and the dual-medium variable operating condition boiler 13, the steam outlet of the dual-medium variable operating condition boiler 13 is connected to the hydrothermal reaction unit 4, the first heat exchange unit 10 is connected to the combustion air outlet of the dual-medium variable operating condition boiler 13, and the solid-phase drying unit 8 is also connected to the tail flue gas waste heat utilization device 14; wherein the hydrothermal reaction unit 4 uses the steam generated by the dual-medium variable operating condition boiler 13 to perform a hydrothermal reaction, and the slurry separation unit 5 is separated to obtain the primary product, and the solid phase drying unit 8 uses the hot air generated by the dual-medium variable operating condition boiler 13 to circulate and dry the primary product to form a solid phase product and a liquid phase product; the first heat exchange unit 10 obtains α-type high-strength gypsum by exchanging heat with the solid phase product, and increases the boiler combustion air temperature used for combustion in the dual-medium variable operating condition boiler 13; the tail flue gas waste heat utilization device 14 exchanges heat with the liquid phase product to form steam, and increases the feed water temperature of the dual-medium variable operating condition boiler 13. The steam generated by the dual-medium variable operating condition boiler 13 is used to perform a hydrothermal reaction on the hydrothermal reaction unit 4, forming a dual-medium circulation method to dry the desulfurized gypsum.

[0027] The present invention provides an α-type high-strength gypsum drying system based on a dual-medium boiler, comprising a high-strength gypsum preparation system and a product waste heat utilization drying system. The desulfurized gypsum is prepared by water in a gypsum slurry preparation tank to form gypsum slurry. The gypsum slurry enters a hydrothermal reaction unit to undergo a hydrothermal reaction. The steam generated by the boiler is used to provide the hydrothermal reaction conditions for the hydrothermal reaction unit. The primary product is separated by a slurry separation unit. The solid phase drying unit utilizes the hot air generated by the dual-medium variable operating condition boiler to circulate and dry the primary product to form a solid phase product and a liquid phase product, thereby achieving the α-type calcium sulfate hemihydrate. The reactants are fully dried and deeply dehydrated to avoid the conversion of α-type calcium sulfate hemihydrate to calcium sulfate dihydrate caused by too low temperature. The heat generated after the solid phase product is dried is exchanged through the first heat exchange unit to obtain α-type high-strength gypsum, and the boiler air temperature required for the combustion of the dual-medium variable-condition boiler is increased. The liquid phase product is heat exchanged through the tail flue gas waste heat utilization device to increase the boiler feed water temperature, forming a dual-medium circulation to dry the desulfurized gypsum, ensuring that under the gypsum reaction and drying conditions, the gypsum after the reaction is dried to α-type high-strength gypsum, thereby increasing product quality and improving the utilization rate of the desulfurized gypsum.

[0028] The invention is further described below through specific examples.

[0029] Example An α-type high-strength gypsum drying system based on a dual-medium boiler, 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 to obtain the primary product after hydrothermal reaction. It includes a hydrothermal reaction unit 4 and a slurry separation unit 5 connected in sequence. The hydrothermal reaction unit 4 performs a hydrothermal reaction on the gypsum slurry, and separates the primary product through the slurry separation unit 5.

[0030] The product waste heat utilization drying system utilizes the dual-medium circulation mode of steam and hot air to dry the initial product. The product waste heat utilization drying system includes a solid-phase drying unit 8, a first heat exchange unit 10 and a dual-medium variable-operating-mode boiler 13. The slurry separation unit 5 is connected to the solid-phase drying unit 8. The solid-phase drying unit 8 is connected to the first heat exchange unit 10 and the dual-medium variable-operating-mode boiler 13. The steam outlet of the dual-medium variable-operating-mode boiler 13 is connected to the hydrothermal reaction unit 4. The first heat exchange unit 10 is connected to the dual-medium variable-operating-mode boiler 13. Among them, the hydrothermal reaction unit 4 utilizes the steam generated by the dual-medium variable-operating-mode boiler 13 to perform a hydrothermal reaction. The separation unit 5 is used for separation to obtain the primary product, and the solid phase drying unit 8 utilizes the hot air generated by the dual-medium variable operating condition boiler 13 for heat exchange to circulate and dry the primary product to form a solid phase product and a liquid phase product; the first heat exchange unit 10 utilizes the boiler fuel air to exchange heat with the solid phase product to obtain α-type high-strength gypsum, and increases the boiler fuel air required for the combustion of the dual-medium variable operating condition boiler 13; the tail flue gas waste heat utilization device 14 exchanges heat with the liquid phase product to increase the feed water temperature of the dual-medium variable operating condition boiler 13, and the steam generated by the dual-medium variable operating condition boiler 13 is used to perform a hydrothermal reaction on the hydrothermal reaction unit 4, forming a dual-medium circulation method to dry the desulfurized gypsum.

[0031] It should be noted that the solid-phase drying unit 8 mainly dries the initial product through the hot air generated by the dual-medium variable-operating-mode boiler 13. The solid-phase drying unit 8 is a dryer, which can be either a partition type or a direct contact type. The hot air generated by the dual-medium variable-operating-mode boiler 13 is used as the circulating drying medium of the solid-phase drying unit 8 to dry the initial product to obtain a solid-phase product and a liquid-phase product, thereby achieving 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.

[0032] The solid phase product dried out from the solid phase drying unit 8 has a certain temperature. The temperature generated in the solid phase product drying process is used to exchange heat with the boiler fuel air (air required for boiler combustion) to form the temperature of the boiler fuel air required for combustion of the dual-medium variable operating condition boiler 13, and a part of the heat of the solid phase product is recovered. The first heat exchange unit 10 condenses and cools the α-type hemihydrate calcium sulfate to obtain high-strength gypsum.

[0033] The liquid product is used as feed water for the dual-medium variable operating condition boiler 13. The liquid product passes through the tail flue gas waste heat utilization device 14 and utilizes the tail flue gas waste heat of the dual-medium variable operating condition boiler 13 for heat exchange, thereby increasing the feed water temperature of the dual-medium variable operating condition boiler 13, realizing the thermal circulation of the separated water, and reducing the water consumption in the system.

[0034] The desulfurized gypsum is dried by forming a dual-medium cycle through the drying system using the waste heat of the product, ensuring the gypsum reaction and drying conditions so that the gypsum after the reaction is dried into α-type high-strength gypsum, avoiding the crystal transformation of gypsum during the drying process, increasing product quality, and improving the utilization rate of desulfurized gypsum.

[0035] In a specific embodiment, the solid phase drying unit 8 is provided with a first inlet, a second inlet, a first outlet and a second outlet, the first inlet is connected to the slurry separation unit 5, the first outlet is connected to the first heat exchange unit 10, the second inlet is connected to the air heating outlet of the dual medium variable working condition boiler 13, and the second outlet is connected to the air heating inlet of the dual medium variable working condition boiler 13 through the induced draft fan 12. The solid phase drying unit 8 forms a hot air medium after the hot air of the dual medium variable working condition boiler 13 is heat exchanged to circulate and dry the primary product to form a solid phase product; wherein the induced draft fan 12 is used to increase the flow rate of the hot air heat exchange and increase the degree of circulated drying.

[0036] In a specific embodiment, a first temperature monitor 7 is provided on the air heating outlet of the dual-medium variable operating condition boiler 13, a dryness detector 9 is provided on the first outlet, a first control system is connected to the first temperature monitor 7 and the dual-medium variable operating condition boiler 13, and a second control system is connected to the dryness detector 9 and the induced draft fan 12. The temperature monitor 7 is provided on the air heating outlet of the dual-medium variable operating condition boiler 13, that is, on the hot air pipeline entering the solid phase drying unit 8. The first temperature monitor 7 is used to monitor the hot air temperature of the solid phase drying unit 8, and feed back the temperature signal to the first control system, and the coal burning amount of the dual-medium variable operating condition boiler 13 is controlled after comparison and analysis by the first control system; the dryness detector 9 is used to monitor the dryness of the solid phase product, and feed back the dryness signal to the second control system, and the wind speed of the induced draft fan 12 is controlled after comparison and analysis by the second control system.

[0037] In a specific embodiment, the outlet of the slurry separation unit 5 is connected to an outlet pipeline, a chloride ion monitor 18 is provided on the outlet pipeline, and a first valve V1 is provided on the outlet pipeline behind the chloride ion monitor 18 along the separation direction of gypsum.

[0038] In a specific embodiment, the outlet pipeline is also provided with a bypass branch, on which a second valve V2 is provided, and the outlet of the bypass branch is connected in sequence to a sedimentation and filtration device 17, a water storage tank 16 and a tail flue gas waste heat utilization device 14, and the tail flue gas waste heat utilization device 14 is connected to the water feed inlet of the dual-medium variable operating condition boiler 13. In the present invention, the gypsum slurry enters the hydrothermal reaction unit 4 to undergo a hydrothermal reaction, and is separated into a primary product and water by the slurry separation unit 5. The slurry separation unit 5 is divided into two branches through the outlet pipeline. Along the separation direction of the gypsum, the first valve V1 is located behind the inlet of the bypass branch pipe, and the outlet pipeline discharges water. The first valve V1 controls the water flow discharged from the outlet pipeline to the outside, and the second valve V2 controls the water to be transported to the sedimentation and filtration device 17 and enters the water storage tank 16. At the same time, the water generated by the solid phase drying unit 8 for drying the primary product is also transported to the water storage tank 16. The water in the water storage tank 16 is transported to the tail flue gas waste heat utilization device 14 through the water supply pump 15. The tail flue gas waste heat utilization device 14 uses the water pump 15 to transport the water with a certain temperature formed by the heat exchange of the liquid phase product to the dual-medium variable operating condition boiler 13, thereby increasing the water supply temperature of the dual-medium variable operating condition boiler 13. The tail flue gas waste heat utilization device 14 is also provided with a discharge port for discharging the flue gas after waste heat utilization.

[0039] In a specific embodiment, the chloride ion monitor 18, the first valve V1 and the second valve V2 are connected to a third control system. The chloride ion monitor 18 is used to monitor the chloride ion concentration of the outlet pipeline, and feed back the chloride ion concentration signal to the third control system. The third control system controls the opening of the first valve V1 and the second valve V2 after comparative analysis, and then controls the chloride ion concentration content of the outlet pipeline to meet the emission standards.

[0040] In a specific embodiment, the water tank 16 is also connected to the solid phase drying unit 8, and a water supply pump 15 is provided between the tail flue gas waste heat utilization device 14 and the water tank 16. The water supply pump 15 is used to transport the water in the water tank 16 to the tail flue gas waste heat utilization device 14, thereby increasing the water transport rate in the water tank 16, and the water generated by the solid phase drying unit 8 after drying the solid phase product is transported to the water tank 16, thereby realizing water circulation.

[0041] In a specific embodiment, a heater 6 is provided between the hydrothermal reaction unit 4 and the dual-medium variable operating condition boiler 13, and a second temperature monitor 19 is provided between the heater 6 and the dual-medium variable operating condition boiler 13. A heater 6 is provided in front of the hydrothermal reaction unit 4, and if the main steam temperature is low, supplementary heat is provided by the heater 6. When the main steam temperature is low, the second temperature monitor 19 detects and controls the heating temperature of the heater 6.

[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 reaction unit 4 and a slurry separation unit 5 connected in sequence; the gypsum slurry preparation tank 2 is used to prepare the desulfurized gypsum to form gypsum slurry, the hydrothermal reaction unit 4 performs a hydrothermal reaction on the gypsum slurry, and the initial product is separated by the slurry separation unit 5. The hydrothermal reaction unit 4 is provided with a third temperature monitor 3, and the third temperature monitor 3 and the water supply pump 15 are connected to a fourth control system. The third temperature monitor 3 is used to monitor the temperature of the hydrothermal reaction unit 4, and feed back the temperature signal to the fourth control system, and the fourth control system controls the flow of the water supply pump 15 after comparison and analysis.

[0043] In summary, the present invention is provided with a hydrothermal reaction unit temperature monitor, a solid phase drying unit temperature monitor and a dryness detector. The temperature monitor can monitor the temperature of the hydrothermal reaction unit and the solid phase drying unit in real time. The dryness detector monitors the dryness of the solid phase product, and by adjusting the flow rate of the induced draft fan, the temperature of the solid phase product can be precisely controlled to ensure that the gypsum reaction and drying conditions reach the set value, and the α-type hemihydrate calcium sulfate is fully dried, and the reactants are deeply dehydrated, thereby realizing the preparation of high-strength gypsum. The boiler load and the boiler fuel amount are adjusted by the hydrothermal reaction unit temperature monitor and the solid phase drying unit temperature monitor, respectively, to ensure that the boiler works under the corresponding load and avoid boiler energy consumption loss. The waste heat in the solid product and the waste heat of the flue gas at the tail of the boiler are fully utilized to heat the boiler combustion air and boiler feed water temperature respectively, which not only reduces the waste of high-quality energy, but also improves the boiler efficiency.

[0044] In a specific embodiment, the first heat exchange unit 10 is connected to a finished product bin 11. The solid phase product after heat exchange in the first heat exchange unit 10 is collected through the finished product bin 11.

[0045] The above-mentioned method of the α-type high-strength gypsum drying system based on the dual-medium boiler comprises the following steps: After the material in the desulfurized gypsum silo 1 is mixed with water in a certain proportion in the gypsum slurry mixing tank 2, it enters the hydrothermal reaction unit 4 for hydrothermal reaction. The hydrothermal reaction temperature is 90°C~200°C. After the reaction, the slurry enters the slurry separation unit 5 for separation. The steam required for the hydrothermal reaction unit 4 comes from the steam in the dual-medium variable-operating boiler 13, and a heater 6 is provided before entering the hydrothermal reaction unit. If the main steam temperature is low, the heater 6 is used for supplementary heat. After separation, the solid phase product enters the solid phase drying unit 8 for drying. The drying temperature of the solid phase drying unit 8 is 90°C~150°C, and the liquid phase product is divided into two branches after passing through the chloride ion monitor 18. If the chloride ion in the liquid phase product exceeds the set value, the first valve V1 is opened and the second valve V2 is closed for external discharge; if the chloride ion content is low, the first valve V1 is closed and the second valve V2 is opened, and the liquid phase product enters the water storage tank 16 after passing through the filter pool 17.

[0046] After being dried by the solid-phase drying unit 8, the solid-phase product enters the first heat exchange unit 10, exchanges heat with the boiler combustion air, and then enters the finished product bin 11; the liquid-phase product enters the water storage tank 16, and the water at the outlet of the water storage tank 16 enters the second heat exchange unit 14 through the feed water pump 15. The water absorbs the waste heat of the tail flue gas and increases the boiler feed water temperature, and then enters the dual-medium variable operating condition boiler 13; the medium in the solid-phase drying unit 8 is hot air (high-temperature air). After cooling in the solid-phase drying unit 8, it enters the dual-medium variable operating condition boiler 13 through the induced draft fan 12 for heating, and after heating, it re-enters the solid-phase drying unit 8 to dry the initial product to form a solid-phase product and a liquid-phase product.

[0047] The hydrothermal reaction unit 4 is provided with a third temperature monitor 3, which is interlocked with the water feed pump 15. If the temperature of the hydrothermal reaction unit 4 is lower than the set value, the water feed pump 15 is controlled to increase the flow rate; the solid phase drying unit 8 is provided with a first temperature monitor 7, which controls the fuel amount of the dual-medium variable operating condition boiler 13. If the temperature is lower than the set value, the fuel amount of the dual-medium variable operating condition boiler 13 is increased; the solid phase drying unit 8 solid phase product outlet pipeline is provided with a dryness detector 9, which is interlocked with the induced draft fan 12. When the dryness of the solid phase product is low, the induced draft fan 12 is controlled to increase the flow rate to achieve sufficient drying of the solid phase product.

[0048] In summary, the present invention avoids the conversion of high-strength gypsum to low-quality gypsum in the product by accurately controlling the parameters of the solid-phase drying unit, thereby improving the utilization rate of desulfurized gypsum. In addition, through accurate control strategies and the setting of heat exchange units, it is ensured that the boiler load can change with the changes in system parameters, thereby improving the boiler efficiency and reducing the overall energy consumption of the system.

[0049] 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.

[0050] 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. An α-type high-strength gypsum drying system based on a dual-medium boiler, characterized in that: include: A high-strength gypsum preparation system, used for preparing desulfurized gypsum to form gypsum slurry, and subjecting the gypsum slurry to a hydrothermal reaction and then separating to obtain a primary product, comprising a hydrothermal reaction unit (4) and a slurry separation unit (5) connected in sequence; A product waste heat utilization drying system comprises a solid phase drying unit (8), a first heat exchange unit (10) and a dual medium variable operating condition boiler (13); a slurry separation unit (5) is connected to the solid phase drying unit (8); the solid phase drying unit (8) is connected to the first heat exchange unit (10) and the dual medium variable operating condition boiler (13); the steam outlet of the dual medium variable operating condition boiler (13) is connected to the hydrothermal reaction unit (4); the first heat exchange unit (10) is connected to the combustion air outlet of the dual medium variable operating condition boiler (13); the solid phase drying unit (8) is also connected to a tail flue gas waste heat utilization device (14); wherein the hydrothermal reaction unit (4) utilizes the steam generated by the dual medium variable operating condition boiler (13) to perform a hydrothermal reaction; The material separation unit (5) separates the initial product, and the solid phase drying unit (8) uses the hot air generated by the dual-medium variable operating condition boiler (13) to circulate and dry the initial product to form a solid phase product and a liquid phase product; the first heat exchange unit (10) uses the boiler combustion air to exchange heat with the solid phase product to obtain α-type high-strength gypsum, and increases the boiler combustion air temperature used for combustion in the dual-medium variable operating condition boiler (13); the tail flue gas waste heat utilization device (14) exchanges heat with the liquid phase product to increase the feed water temperature of the dual-medium variable operating condition boiler (13), and the steam generated by the dual-medium variable operating condition boiler (13) is used to perform a hydrothermal reaction on the hydrothermal reaction unit (4), thereby forming a dual-medium circulation method to dry the desulfurized gypsum.

2. The α-type high-strength gypsum drying system based on a dual-medium boiler according to claim 1 is characterized in that: The solid phase drying unit (8) is provided with a first inlet, a second inlet, a first outlet and a second outlet, the first inlet being connected to the slurry separation unit (5), the first outlet being connected to the first heat exchange unit (10), the second inlet being connected to the air heating outlet of the dual-medium variable operating condition boiler (13), and the second outlet being connected to the air heating inlet of the dual-medium variable operating condition boiler (13) via an induced draft fan (12).

3. The α-type high-strength gypsum drying system based on a dual-medium boiler according to claim 2 is characterized in that: A first temperature monitor (7) is provided at the air heating outlet of the dual-medium variable operating condition boiler (13), a dryness detector (9) is provided at the first outlet, the first temperature monitor (7) and the dual-medium variable operating condition boiler (13) are connected to a first control system, and the dryness detector (9) and the induced draft fan (12) are connected to a second control system.

4. The α-type high-strength gypsum drying system based on a dual-medium boiler according to claim 1 is characterized in that: The outlet of the slurry separation unit (5) is connected to an outlet pipeline, on which a chloride ion monitor (18) is provided, and along the separation direction of gypsum, a first valve (V1) is provided on the outlet pipeline behind the chloride ion monitor (18).

5. The α-type high-strength gypsum drying system based on a dual-medium boiler according to claim 4 is characterized in that: The outlet pipeline is also provided with a bypass branch pipe, on which a second valve (V2) is provided, and the outlet of the bypass branch pipe is connected in sequence to a sedimentation filter device (17), a water storage tank (16) and a tail flue gas waste heat utilization device (14), and the tail flue gas waste heat utilization device (14) is connected to the water feed inlet of the dual-medium variable operating condition boiler (13).

6. The α-type high-strength gypsum drying system based on a dual-medium boiler according to claim 5 is characterized in that: The chloride ion monitor (18), the first valve (V1) and the second valve (V2) are signal-connected to a third control system.

7. The α-type high-strength gypsum drying system based on a dual-medium boiler according to claim 5 is characterized in that: The water storage tank (16) is also connected to the solid phase drying unit (8), and a water supply pump (15) is provided between the tail flue gas waste heat utilization device (14) and the water storage tank (16).

8. The α-type high-strength gypsum drying system based on a dual-medium boiler according to claim 3 is characterized in that: A heater (6) is provided between the hydrothermal reaction unit (4) and the dual-medium variable operating condition boiler (13), and a second temperature monitor (19) is provided between the heater (6) and the dual-medium variable operating condition boiler (13).

9. The α-type high-strength gypsum drying system based on a dual-medium boiler according to claim 7, 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 reaction unit (4) and a slurry separation unit (5) which are connected in sequence; the gypsum slurry preparation tank (2) is used to prepare the desulfurized gypsum to form gypsum slurry, the hydrothermal reaction unit (4) performs a hydrothermal reaction on the gypsum slurry, and the slurry separation unit (5) separates the gypsum slurry to obtain a primary product, and the hydrothermal reaction unit (4) is provided with a temperature monitor A (3), and the temperature monitor A (3) and the water supply pump (15) are connected to a fourth control system by signal.

10. The α-type high-strength gypsum drying system based on a dual-medium boiler according to claim 1, characterized in that: The first heat exchange unit (10) is connected to a finished product bin (11).

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