A nitrate-containing process waste heat recovery and wastewater cooling integrated solution method

Abstract

The application belongs to the technical field of waste heat and wastewater treatment, and discloses a nitrate-containing process waste heat recovery and wastewater cooling integrated solution, wherein a nitrate-containing process waste heat recovery and wastewater cooling integrated system comprises a buffer energy storage module, an anti-cavitation conveying module, a heat exchange module, a cooling module and a control module, the anti-cavitation conveying module is in communication with the buffer energy storage module and the heat exchange module through pipelines, the cooling module is in communication with the heat exchange module through a pipeline, and the control module is electrically connected with the heat exchange module, the buffer energy storage module, the anti-cavitation conveying module and the cooling module. Through integrated design of the buffer energy storage module, the anti-cavitation conveying module, the heat exchange module, the cooling module and the control module, waste heat recovery and cooling integrated treatment of nitrate-containing alkaline high-temperature wastewater is realized, and the system is suitable for complex site layout and special water quality conditions.

Description

Technical Field

[0001] This invention relates to the field of waste heat and wastewater treatment technology, and in particular to an integrated solution for the recovery of process waste heat and the cooling of wastewater containing nitrate esters. Background Technology

[0002] In the production process of nitrate esters, two types of high-temperature hot fluids are generated: process wastewater and steam condensate. These hot fluids need to be cooled to below 40°C before entering the subsequent wastewater treatment system, and a large amount of recoverable waste heat is released during the cooling process. Simultaneously, the process requires a continuous and stable supply of process hot water, sourced from pure process water. This process wastewater contains trace amounts of nitrate esters, as well as alkaline components such as sodium hydroxide, nitrates, and sulfates, posing an explosion hazard. The water's pH is approximately 10. Although the explosion risk is eliminated after stabilization treatment, the special components and alkaline conditions place specific requirements on the corrosion resistance and operational safety of heat exchange and conveying equipment.

[0003] Existing technologies for high-temperature hot fluid treatment and process hot water supply in this type of process generally adopt the traditional solution of natural cooling in a cooling tank + full steam heat exchange: high-temperature wastewater and steam condensate are discharged after natural cooling in a large cooling tank, with a large amount of waste heat being directly lost during the cooling process; process hot water is prepared entirely by steam heating, without utilizing the waste heat from the high-temperature fluid cooling. This technology has the following drawbacks: it has high site requirements, relies on open and excavable construction conditions, and cannot adapt to restricted sites with complex pipeline layouts; the thermal energy utilization rate is extremely low, failing to meet energy conservation and carbon reduction policy requirements; the cooling, heat exchange, and transportation stages are independent of each other, lacking integrated design and resulting in poor system coordination. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides an integrated solution for the recovery of process waste heat and the cooling of wastewater containing nitrate esters.

[0005] The above-mentioned technical objective of this invention is achieved through the following technical solution: an integrated system for recovering process waste heat and cooling wastewater containing nitrate esters, comprising a buffer energy storage module, an anti-cavitation conveying module, a heat exchange module, a cooling module, and a control module. The anti-cavitation conveying module is connected to the buffer energy storage module and the heat exchange module via pipelines. The cooling module is connected to the heat exchange module via pipelines. The control module is electrically connected to the heat exchange module, the buffer energy storage module, the anti-cavitation conveying module, and the cooling module. The heat exchange module consists of several parallel dual-channel plate heat exchangers, and the dual-channel plate heat exchangers have a double-layer sandwich structure. The buffer energy storage module is a wastewater tank with a floating cover and an energy dissipation cylinder, and the wastewater tank is connected to an external hot wastewater pipe. The anti-cavitation conveying module consists of several parallel variable frequency water pumps. The cooling module consists of several dry closed-loop cooling towers.

[0006] By adopting the above technical solutions, the core components and core device types of each module of the system are defined. Through the integrated design of buffer energy storage, anti-cavitation conveying, heat exchange, cooling, and control modules, the system achieves integrated waste heat recovery and cooling of alkaline high-temperature wastewater containing nitrate esters, adaptable to complex site layouts and special water quality conditions. The wastewater tank with a floating cover and energy dissipation cylinder enables high-temperature water storage, buffering, and vapor-liquid separation, improving thermal efficiency. Parallel variable frequency water pumps ensure stable conveying. The dry-mix closed-loop cooling tower eliminates the need for a cooling pond, overcoming site excavation limitations and achieving efficient wastewater cooling. The collaborative operation of each module solves the problems of poor system integration, low site adaptability, and difficulty in heat exchange for special water qualities found in existing technologies.

[0007] Furthermore, the wastewater tank is equipped with a mechanical breather valve at the top and a drain valve at the bottom. The inlet of the wastewater tank is located below the water surface, and the outlet is located at the bottom of the wastewater tank. The wastewater tank is also equipped with a magnetic float level gauge with remote signal transmission.

[0008] By adopting the above technical solutions, the wastewater tank of the buffer energy storage module has been structurally refined. A mechanical breather valve enables the wastewater tank to operate at normal pressure, preventing abnormal pressure from affecting system safety. The bottom drain valve facilitates the cleaning and maintenance of the wastewater tank, ensuring stable water quality. The subsurface water inlet and bottom water outlet design, combined with a floating cover, isolates high-temperature water from air, reducing heat loss and avoiding gas-liquid interface interference. A magnetic float level gauge with remote signal transmission enables real-time monitoring of the wastewater tank level and high / low level alarms, providing data support for system condition switching and safe operation. This solves the problems of existing wastewater tanks having no accurate monitoring, prone to abnormal pressure, and large heat loss.

[0009] Furthermore, the lowest liquid level of the wastewater tank is at least 3.0m higher than the center line of the pump shaft of the variable frequency water pump, and the suction pipe of the variable frequency water pump is left with a gap of not less than D / 2 from the bottom plate of the wastewater tank, where D is the diameter of the suction pipe.

[0010] By adopting the above technical solution, the relative positions of the wastewater tank and the variable frequency water pump, as well as the installation requirements of the variable frequency water pump's suction port, are structurally defined. The lowest liquid level in the wastewater tank is at least 3.0m higher than the center line of the variable frequency water pump shaft, enabling positive pressure water intake for the variable frequency water pump and suppressing the saturated vapor pressure of the high-temperature water. A gap of not less than D / 2 is left between the suction port and the bottom plate of the wastewater tank to eliminate eddy currents and gas-liquid interface interference, fundamentally eliminating the cavitation problem of the variable frequency water pump during the transportation of wastewater at temperatures above 90℃. This solves the industry pain points of existing variable frequency water pumps being prone to cavitation and vibration, and having poor stability during continuous system operation, ensuring the system's stable operation year-round.

[0011] Furthermore, the heat medium inlet of the dual-channel plate heat exchanger is connected to the outlet of the variable frequency water pump, and the outlet is connected to the cooling module. The heat exchange module also includes a steam-water heat exchanger. The cold medium inlet of the dual-channel plate heat exchanger is connected to the pure water delivery pipeline, and the outlet is connected to the water inlet of the steam-water heat exchanger. The steam inlet of the steam-water heat exchanger is connected to the process steam pipeline, and the steam condenses into water at the outlet. The outlet of the steam-water heat exchanger is connected to the process heat equipment.

[0012] By adopting the above technical solution, the pipeline connection relationship of the heat exchange module is refined, the collaborative working mode of the dual-channel plate heat exchanger and the steam-water heat exchanger is clarified, the dual heat source switching of waste heat exchange and steam heat exchange is realized, the waste heat of high-temperature wastewater is maximized, the traditional all-steam heating mode is replaced, fossil energy consumption is significantly reduced, and operating costs are reduced.

[0013] Furthermore, the variable frequency water pump is equipped with an operation and fault detection alarm component, and the water inlet of the variable frequency water pump is connected to the outlet of the wastewater tank.

[0014] By adopting the above technical solution, the functions of the variable frequency water pump in the anti-cavitation conveying module are refined, and the operation and fault detection alarm components can monitor the working status of the variable frequency water pump in real time.

[0015] Furthermore, the inlet end of the dry closed cooling tower is connected to the heat medium outlet of the dual-channel plate heat exchanger, and the outlet end of the dry closed cooling tower is connected to the wastewater treatment device. The dry closed cooling tower is equipped with a cooling fan, a spray device, and an adjustable exhaust valve.

[0016] By adopting the above technical solution, the structure and pipeline of the dry-mix closed cooling tower of the cooling module are refined. The pipeline of the cooling tower and the heat exchange module are connected to achieve further cooling of the wastewater after heat exchange, ensuring that the wastewater is transported to the wastewater treatment device after being reduced to below 40°C, so as to achieve compliant discharge. The configuration of cooling fans and spray devices, together with the adjustable exhaust valve, realizes multi-mode cooling of air cooling and spray + air cooling, which can be flexibly adjusted according to the working conditions to improve the cooling efficiency. At the same time, there is no need to build a traditional cooling pool, which is suitable for site constraints such as complex pipeline layout and inability to excavate downwards. This solves the problems of existing technologies for wastewater cooling being limited by site and having a single cooling mode.

[0017] Furthermore, the control module includes a temperature sensor, a pressure sensor, a flow sensor, and several regulating valves. Several temperature sensors are respectively installed in the wastewater tank, the outlet of the dual-channel plate heat exchanger, and the inlet and outlet of the dry closed cooling tower. The pressure sensor is installed in the external hot wastewater pipe.

[0018] By adopting the above technical solution, the composition of the control module and the placement of sensors and regulating valves are limited. Temperature sensors at multiple locations enable real-time temperature monitoring of key system nodes, pressure sensors ensure stable wastewater supply pressure, and flow sensors assist in regulating the flow rate of the medium. The configuration of hot wastewater regulating valves and bypass regulating valves enables precise control of hot wastewater flow and pipeline pressure, providing data and execution support for the system's automated operating condition switching, heat exchange regulation, and cooling mode switching, thereby improving the system's automation and intelligence level and solving the problems of low precision in manual control and poor system stability in existing technologies.

[0019] Furthermore, a KM12 valve is installed near the steam-water heat exchanger in the pure water delivery pipeline, and a KM11 valve is installed on the pipeline between the dual-channel plate heat exchanger and the steam-water heat exchanger. There are two variable frequency water pumps, and the inlet ends of the two variable frequency water pumps are respectively equipped with a TM1 bypass regulating valve and a TM2 hot wastewater regulating valve.

[0020] By adopting the above technical solution, the configuration of key valves and regulating valves of the variable frequency water pumps in the system is refined. Valves KM11 and KM12 enable automated and rapid switching between waste heat exchange and steam heat exchange, ensuring a continuous and stable supply of process hot water. The two variable frequency water pumps are respectively equipped with TM1 bypass regulating valve and TM2 hot wastewater regulating valve, which can independently control the flow and pressure of a single variable frequency water pump, adapting to the parallel operation of variable frequency water pumps, further improving the accuracy of system heat exchange regulation, avoiding insufficient heat exchange or excessive wastewater discharge due to flow and pressure fluctuations, and solving the problems of cumbersome heat source switching and low heat exchange regulation accuracy in existing technologies.

[0021] Furthermore, all the pipelines are stainless steel seamless pipes for transporting fluids, and the seamless pipes are wrapped with a hydrophobic composite silicate insulation shell.

[0022] By adopting the above technical solutions, the material and insulation layer of the system pipeline are limited. The seamless stainless steel pipe for conveying fluids has excellent corrosion resistance and can be adapted to alkaline wastewater containing nitrate esters, avoiding pipeline corrosion and damage and extending the service life of the equipment. The encapsulation design of the hydrophobic composite silicate insulation pipe shell effectively reduces heat loss in the pipeline, improves the overall thermal efficiency of the system, and avoids the decrease in insulation effect caused by water absorption of the insulation layer. This solves the problems of easy corrosion and large heat loss in existing pipelines, further ensuring the long-term stable operation and energy-saving effect of the system.

[0023] This application also provides an integrated solution for process waste heat recovery and wastewater cooling of nitrate esters, applied to the aforementioned integrated system for process waste heat recovery and wastewater cooling of nitrate esters, including the following steps: S1. Initial Operation: Sodium hydroxide alkaline solution is added to the nitrate-containing hot wastewater to carry out a saponification reaction. Steam is added as a heat source to accelerate the reaction. At the same time, the steam pressure is used as a power source to pressurize the mixed solution through a steam ejector. After a certain period of saponification reaction, the nitrate content in the wastewater decreases significantly and the temperature rises significantly. Then, it is transported through the hot wastewater pipe. The KM11 valve connecting the steam-water heat exchanger and the heat exchange module is closed, the KM12 valve is opened, the steam-water heat exchanger is started, and process steam is introduced to heat the pure water to prepare process hot water for use by process heat equipment. S2. Working condition switching detection: Introduce alkaline high-temperature process wastewater containing nitrate ester and steam condensate into the wastewater tank of the buffer energy storage module. The temperature T1 of the wastewater tank is detected by a temperature sensor and the liquid level of the wastewater tank is detected by a magnetic float level gauge. When T1≥40℃ and the liquid level of the wastewater tank≥3.0m, proceed to step S3. S3. Waste heat exchanger start-up: Automatically open valve KM11 and close valve KM12 to switch to wastewater heat exchange system, with steam-water heat exchanger as a backup heat source; start the variable frequency water pump of the anti-cavitation conveying module to transport the high-temperature wastewater in the wastewater tank to the dual-channel plate heat exchanger of the heat exchange module for heat exchange with pure water to prepare process hot water. S4. Heat exchange regulation: The control module adjusts the opening of the TM2 hot wastewater regulating valve according to the heat exchanger outlet temperature T2 of the dual-channel plate heat exchanger to control the hot wastewater flow rate. At the same time, it adjusts the opening of the TM1 bypass regulating valve according to the pressure of the wastewater supply main pipe to ensure stable heat exchange. S5. Wastewater Cooling: After heat exchange, the wastewater is mixed with the excess heat wastewater bypassing the wastewater tank and transported to the dry closed cooling tower of the cooling module. The opening of the exhaust valve is adjusted according to the temperature of the wastewater heat exchange room, and the speed of the cooling fan is adjusted according to the wastewater discharge temperature. Under low temperature conditions, the spray device is turned off and the air-cooled mode is used to cool the wastewater to below 40℃. S6. Compliant Discharge: The cooled wastewater is transported to a wastewater treatment device to complete the integrated treatment of waste heat recovery and wastewater cooling; S7. Fault Switching: If the variable frequency water pump or the dual-channel plate heat exchanger fails during system operation, the system will automatically switch to the standby equipment operation through the fault detection alarm component.

[0024] By adopting the above technical solution, the specific operation method of the system is defined. Through step-by-step initial operation, operating condition switching detection, waste heat exchange start-up, heat exchange regulation, wastewater cooling, compliant discharge, and fault switching, the system achieves automated and standardized operation. Automatic switching of dual heat sources ensures continuous supply of process hot water, precise heat exchange regulation ensures waste heat recovery efficiency and stable hot water temperature, multi-mode wastewater cooling achieves compliant wastewater cooling, and automatic fault switching ensures continuous system operation. The entire process takes into account multiple objectives such as waste heat recovery, compliant wastewater discharge, and stable system operation, replacing the traditional solution of natural cooling in a cooling tank + full steam heat exchange. It significantly improves thermal energy utilization, reduces operating costs, and is adaptable to special water quality and complex site constraints. It solves the problems of cumbersome operation methods, poor energy-saving effect, and inability to meet multiple operating conditions of existing technologies, and has good value for large-scale promotion. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention.

[0026] In the diagram: 10. Buffer energy storage module; 11. Wastewater tank; 12. Mechanical breather valve; 13. Magnetic level gauge; 20. Anti-cavitation conveying module; 21. Variable frequency water pump; 30. Heat exchange module; 31. Dual-channel plate heat exchanger; 32. Steam-water heat exchanger; 40. Cooling module; 41. Dry closed-loop cooling tower; 42. Cooling fan; 50. KM12 valve; 51. KM11 valve; 52. TM1 bypass regulating valve; 53. TM2 hot wastewater regulating valve. Detailed Implementation

[0027] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0028] like Figure 1 As shown in the embodiment of this application, an integrated system for process waste heat recovery and wastewater cooling containing nitrate esters is disclosed, including: a buffer energy storage module 10, an anti-cavitation conveying module 20, a heat exchange module 30, a cooling module 40, and a control module. The anti-cavitation conveying module 20 is connected to the buffer energy storage module 10 and the heat exchange module 30 through pipelines, and the cooling module 40 is connected to the heat exchange module 30 through pipelines. The control module is electrically connected to the other four modules to realize automated monitoring and control of the entire system. All pipelines in the system use seamless stainless steel pipes for fluid transportation, with an external hydrophobic composite silicate insulation shell, which is suitable for alkaline water corrosion conditions and reduces heat loss.

[0029] Buffer energy storage module 10: A stainless steel atmospheric pressure sealed wastewater tank 11 with a stainless steel float cover and an internal energy dissipation cylinder is used. A mechanical breather valve 12 is installed on the top of the wastewater tank 11 to maintain the pressure difference between the indoor and outdoor environments, ensuring that the wastewater tank 11 is at atmospheric pressure and avoiding abnormal pressure from affecting system safety. A drain valve is installed at the bottom to facilitate the cleaning and maintenance of the wastewater tank 11 and ensure stable water quality. The float cover is used to isolate high-temperature water from air, reducing heat loss and avoiding gas-liquid interface interference. The inlet is located below the water surface to achieve submerged water intake, and the outlet is located at the bottom of the wastewater tank 11. The float cover is used to isolate high-temperature water from air, reducing heat loss and avoiding gas-liquid interface interference. The wastewater tank 11 is equipped with a magnetic float level gauge 13 with remote signal transmission to realize high and low liquid level alarm and real-time liquid level monitoring. The wastewater tank 11 is also connected to an external hot wastewater pipe to receive alkaline high-temperature process wastewater containing nitrate esters and steam condensate.

[0030] The anti-cavitation conveying module 20 includes two parallel variable frequency water pumps 21. Each pump 21 is equipped with operation and fault detection alarm components. Its inlet is connected to the outlet of the wastewater tank 11, and its outlet is connected to the heat exchange module 30. The lowest liquid level in the wastewater tank 11 is at least 3.0m higher than the centerline of the pump shaft of the variable frequency water pump 21. A gap of not less than D / 2 (where D is the diameter of the suction pipe) is maintained between the suction port of the variable frequency water pump 21 and the bottom plate of the wastewater tank 11. Structurally, this defines the relative position of the wastewater tank 11 and the variable frequency water pump 21, as well as the suction... The installation requirements for the water inlet are as follows: the lowest liquid level of the wastewater tank 11 must be at least 3.0m higher than the center line of the pump shaft of the variable frequency water pump 21 to achieve positive pressure water intake of the variable frequency water pump 21 and suppress the saturated vapor pressure of the high-temperature water; the suction pipe inlet must have a gap of not less than D / 2 from the bottom plate of the wastewater tank 11 to eliminate eddy current and gas-liquid interface interference, fundamentally eliminating the cavitation problem of the variable frequency water pump 21 during the transportation of wastewater at temperatures above 90℃, solving the industry pain points of easy cavitation and vibration of the existing variable frequency water pump 21 and poor stability of continuous system operation, and ensuring the stable operation of the system year-round.

[0031] The heat exchange module 30 includes two parallel dual-channel plate heat exchangers 31 and a steam-water heat exchanger 32. The dual-channel plate heat exchanger 31 has a double-layer sandwich structure. Its hot medium inlet is connected to the outlet of the variable frequency water pump 21, and its hot medium outlet is connected to the cooling module 40. Its cold medium inlet is connected to the pure water delivery pipeline, and its cold medium outlet is connected to the inlet of the steam-water heat exchanger 32. The steam inlet of the steam-water heat exchanger 32 is connected to the process steam pipeline. After heat exchange, the steam condenses into water and is discharged. The outlet of the steam-water heat exchanger 32 is connected to the process heat equipment, providing process hot water for production. This design clarifies the collaborative working mode of the dual-channel plate heat exchanger 31 and the steam-water heat exchanger 32, enabling dual heat source switching between waste heat exchange and steam heat exchange. This maximizes the utilization of the waste heat from high-temperature wastewater, replacing the traditional all-steam heating mode, significantly reducing fossil energy consumption, and lowering operating costs. A KM12 valve 50 is installed near the steam-water heat exchanger 32 in the pure water delivery pipeline, and a KM11 valve 51 is installed on the pipeline between the dual-channel plate heat exchanger 31 and the steam-water heat exchanger 32 to realize the switching of heat source for heat exchange.

[0032] Cooling module 40 includes two dry-mix closed-circuit cooling towers. The inlet end of each tower is connected to the heat medium outlet of a dual-channel plate heat exchanger 31, and the outlet end is connected to a wastewater treatment device. Each dry-mix closed-circuit cooling tower is equipped with a cooling fan 42, a spray system, and adjustable indoor and outdoor exhaust valves, allowing for switching between air-cooled and spray-plus-air-cooled cooling modes depending on the operating conditions. The cooling towers are connected to the heat exchange module 30 via piping, further cooling the wastewater after heat exchange. This ensures the wastewater is cooled to below 40°C before being transported to the wastewater treatment device for compliant discharge. The configuration of the cooling fan 42 and spray system, combined with the adjustable exhaust valves, enables multi-mode cooling (air-cooled and spray-plus-air-cooled), which can be flexibly adjusted according to operating conditions to improve cooling efficiency. Furthermore, it eliminates the need for traditional cooling ponds, making it suitable for complex pipeline layouts and sites where excavation is not feasible. This solves the problems of existing wastewater cooling technologies being limited by site constraints and having only one cooling mode.

[0033] The control module includes several temperature sensors, pressure sensors, flow sensors, and several regulating valves. The temperature sensors are respectively installed at the wastewater tank 11, the outlet of the dual-channel plate heat exchanger 31, and the inlet and outlet of the dry-mix closed cooling tower. The pressure sensors are installed on the external hot wastewater pipe. The regulating valves include the TM1 bypass regulating valve 52 and the TM2 hot wastewater regulating valve 53 installed at the inlet of the variable frequency water pump 21, so as to realize real-time monitoring and precise control of temperature, pressure, and flow.

[0034] A solution for integrated waste heat recovery and wastewater cooling of nitrate-containing processes is also provided, applied to the aforementioned integrated waste heat recovery and wastewater cooling system for nitrate-containing processes, comprising the following steps: S1. Initial Operation: Sodium hydroxide alkaline solution is added to the nitrate-containing hot wastewater to carry out a saponification reaction. Steam is added as a heat source to accelerate the reaction. At the same time, the steam pressure is used as a power source to pressurize the mixed solution through a steam ejector. After a certain period of saponification reaction, the nitrate content in the wastewater decreases significantly and the temperature rises significantly. Then, it is transported through the hot wastewater pipe. The KM11 valve 51 connecting the steam-water heat exchanger 32 and the heat exchange module 30 is closed, the KM12 valve 50 is opened, the steam-water heat exchanger 32 is started, and process steam is introduced to heat the pure water to prepare process hot water for use by process heat equipment. S2. Working condition switching detection: Introduce alkaline high-temperature process wastewater containing nitrate ester and steam condensate into the wastewater tank 11 of the buffer energy storage module 10. The temperature T1 of the wastewater tank 11 is detected by a temperature sensor and the liquid level of the wastewater tank 11 is detected by a magnetic float level gauge 13. When T1≥40℃ and the liquid level of the wastewater tank 11≥3.0m, proceed to step S3. S3. Waste heat exchanger start-up: Automatically open valve 51 of KM11 and close valve 50 of KM12 to switch to wastewater heat exchange system, with steam-water heat exchanger 32 as a backup heat source; start the variable frequency water pump 21 of anti-cavitation conveying module 20 to transport high-temperature wastewater in wastewater tank 11 to dual-channel plate heat exchanger 31 of heat exchange module 30 for heat exchange with pure water to prepare process hot water; S4. Heat exchange regulation: The control module adjusts the opening of the TM2 hot wastewater regulating valve 53 according to the outlet temperature T2 of the dual-channel plate heat exchanger 31 to control the hot wastewater flow rate. At the same time, it adjusts the opening of the TM1 bypass regulating valve 52 according to the pressure of the wastewater supply main pipe to ensure stable heat exchange. S5. Wastewater cooling: After heat exchange, the wastewater is mixed with the excess heat wastewater bypassed by the wastewater tank 11 and transported to the dry closed cooling tower 41 of the cooling module 40. The opening of the exhaust valve is adjusted according to the temperature of the wastewater heat exchange room, and the speed of the cooling fan 42 is adjusted according to the wastewater discharge temperature. Under low temperature conditions, the spray device is turned off and the air-cooled mode is used to cool the wastewater to below 40°C. S6. Compliant Discharge: The cooled wastewater is transported to a wastewater treatment device to complete the integrated treatment of waste heat recovery and wastewater cooling; S7. Fault Switching: If the variable frequency water pump 21 or the dual-channel plate heat exchanger fails during system operation, the system will automatically switch to standby equipment operation through the fault detection alarm component.

[0035] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. An integrated system for recovering process waste heat and cooling wastewater containing nitrate esters, characterized in that: It includes a buffer energy storage module (10), an anti-cavitation conveying module (20), a heat exchange module (30), a cooling module (40), and a control module. The anti-cavitation conveying module (20) is connected to the buffer energy storage module (10) and the heat exchange module (30) through pipelines. The cooling module (40) is connected to the heat exchange module (30) through pipelines. The control module is electrically connected to the heat exchange module (30), the buffer energy storage module (10), the anti-cavitation conveying module (20), and the cooling module (40). The heat exchange module (30) consists of several parallel dual-channel plate heat exchangers (31), and the dual-channel plate heat exchangers (31) have a double-layer sandwich structure. The buffer energy storage module (10) is a wastewater tank (11) with a floating cover and an energy dissipation cylinder. The wastewater tank (11) is connected to an external hot wastewater pipe. The anti-cavitation conveying module (20) consists of several parallel variable frequency water pumps (21). The cooling module (40) consists of several dry closed cooling towers (41).

2. The integrated system for process waste heat recovery and wastewater cooling containing nitrate esters according to claim 1, characterized in that: The wastewater tank (11) is equipped with a mechanical breather valve (12) at the top and a drain valve at the bottom. The inlet of the wastewater tank (11) is located below the water surface and the outlet is located at the bottom of the wastewater tank (11). The wastewater tank (11) is also equipped with a magnetic float level gauge (13) with remote signal transmission.

3. The integrated system for process waste heat recovery and wastewater cooling containing nitrate esters according to claim 2, characterized in that: The lowest liquid level of the wastewater tank (11) is at least 3.0m higher than the center line of the pump shaft of the variable frequency pump (21). The suction pipe of the variable frequency pump (21) is left with a gap of not less than D / 2 from the bottom plate of the wastewater tank (11), where D is the diameter of the suction pipe.

4. The integrated system for process waste heat recovery and wastewater cooling containing nitrate esters according to claim 3, characterized in that: The inlet of the heat medium of the dual-channel plate heat exchanger (31) is connected to the outlet of the variable frequency water pump (21), and the outlet is connected to the cooling module (40). The heat exchange module (30) also includes a steam-water heat exchanger (32). The inlet of the cold medium of the dual-channel plate heat exchanger (31) is connected to the pure water conveying pipeline, and the outlet is connected to the water inlet of the steam-water heat exchanger (32). The steam inlet of the steam-water heat exchanger (32) is connected to the process steam pipeline, and the steam at the outlet condenses into water. The outlet of the steam-water heat exchanger (32) is connected to the process heat equipment.

5. The integrated system for process waste heat recovery and wastewater cooling containing nitrate esters according to claim 4, characterized in that: The variable frequency water pump (21) is equipped with an operation and fault detection alarm component, and the inlet of the variable frequency water pump (21) is connected to the outlet of the wastewater tank (11).

6. The integrated system for process waste heat recovery and wastewater cooling containing nitrate esters according to claim 5, characterized in that: The inlet of the dry closed cooling tower (41) is connected to the heat medium outlet of the dual-channel plate heat exchanger (31), and the outlet of the dry closed cooling tower (41) is connected to the wastewater treatment device. The dry closed cooling tower (41) is equipped with a cooling fan (42), a spray device, and an adjustable exhaust valve.

7. The integrated system for process waste heat recovery and wastewater cooling containing nitrate esters according to claim 6, characterized in that: The control module includes a temperature sensor, a pressure sensor, a flow sensor and several regulating valves. Several temperature sensors are respectively installed at the outlet of the wastewater tank (11), the heat exchanger (31) of the dual-channel plate heat exchanger, and the inlet and outlet of the dry closed cooling tower (41). The pressure sensor is installed on the external hot wastewater pipe.

8. The integrated system for process waste heat recovery and wastewater cooling containing nitrate esters according to claim 7, characterized in that: A KM12 valve (50) is installed near the steam-water heat exchanger (32) in the pure water delivery pipeline. A KM11 valve (51) is installed on the pipeline between the dual-channel plate heat exchanger (31) and the steam-water heat exchanger (32). There are two variable frequency water pumps (21). The inlet of the two variable frequency water pumps (21) is respectively equipped with a TM1 bypass regulating valve (52) and a TM2 hot wastewater regulating valve (53).

9. The integrated system for process waste heat recovery and wastewater cooling containing nitrate esters according to claim 8, characterized in that: All pipelines are stainless steel seamless pipes for transporting fluids, and the seamless pipes are wrapped with a hydrophobic composite silicate insulation shell.

10. An integrated solution for process waste heat recovery and wastewater cooling of nitrate-containing esters, employing the integrated system for process waste heat recovery and wastewater cooling of nitrate-containing esters as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Initial operation: Sodium hydroxide alkaline solution is added to the hot wastewater containing nitrate esters to carry out saponification reaction, and steam is added as a heat source to accelerate the reaction. At the same time, the steam pressure is used as a power source to pressurize the mixed solution through a steam ejector. After a certain period of saponification reaction, the nitrate ester content in the wastewater decreases significantly and the temperature rises significantly. Then it is transported by the hot wastewater pipe. The KM11 valve (51) connecting the steam-water heat exchanger (32) and the heat exchange module (30) is closed, the KM12 valve (50) is opened, the steam-water heat exchanger (32) is started, and process steam is introduced to heat the pure water to prepare process hot water for use by process heat equipment. S2. Working condition switching detection: Introduce alkaline high-temperature process wastewater containing nitrate ester and steam condensate into the wastewater tank (11) of the buffer energy storage module (10). Detect the temperature T1 of the wastewater tank (11) through a temperature sensor and the liquid level of the wastewater tank (11) through a magnetic float level gauge (13). When T1≥40℃ and the liquid level of the wastewater tank ≥3.0m, proceed to step S3. S3. Waste heat exchange start-up: Automatically open valve KM11 (51) and close valve KM12 (50) to switch to wastewater heat exchange system, with steam-water heat exchanger (32) as a backup heat source; start the variable frequency water pump (21) of the anti-cavitation conveying module (20) to transport the high temperature wastewater in the wastewater tank (11) to the dual-channel plate heat exchanger (31) of the heat exchange module (30) for heat exchange with pure water to prepare process hot water; S4. Heat exchange regulation: The control module adjusts the opening of the TM2 hot wastewater regulating valve (53) according to the outlet temperature T2 of the dual-channel plate heat exchanger (31) to control the hot wastewater flow rate. At the same time, the opening of the TM1 bypass regulating valve (52) is adjusted according to the pressure of the wastewater supply main pipe to ensure stable heat exchange. S5. Wastewater cooling: After heat exchange, the wastewater is mixed with the excess heat wastewater bypassed by the wastewater tank (11) and transported to the dry closed cooling tower (41) of the cooling module (40). The opening of the exhaust valve is adjusted according to the temperature of the wastewater heat exchange room, and the speed of the cooling fan (42) is adjusted according to the wastewater discharge temperature. Under low temperature conditions, the spray device is turned off and the air-cooled mode is used to cool the wastewater to below 40°C. S6. Compliant Discharge: The cooled wastewater is transported to a wastewater treatment device to complete the integrated treatment of waste heat recovery and wastewater cooling; S7. Fault Switching: If the variable frequency water pump (21) or the dual-channel plate heat exchanger (31) fails during system operation, the system will automatically switch to standby equipment operation through the fault detection alarm component.

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