A fan-coil air conditioning water system with steam condensate as heat source

Abstract

A fan coil air conditioning water system with steam condensate as the heat source comprises a steam condensate subsystem for recovering condensate from production units in industrial plants or combined air conditioning units in air conditioning rooms with low-pressure steam as the heat source; an air conditioning hot water subsystem for providing heat to the air conditioning terminals during winter operation; a steam subsystem for providing the heating load required by the air conditioning water system during winter operation; a variable frequency automatic water supply pump for water replenishment and pressure stabilization in the hot water subsystem, with the steam condensate subsystem serving as the water supply source; a PLC control subsystem for providing control circuitry and control commands to the air conditioning hot water subsystem; and an air conditioning chilled water subsystem for providing cooling to the air conditioning terminals during summer operation. This invention avoids the drawbacks of direct discharge of steam condensate from industrial plants, significantly saves energy and reduces emissions, greatly improves the utilization rate of low-grade heat energy from steam condensate in industrial plants, and has significant energy-saving and efficiency-enhancing effects.

Description

Technical Field

[0001] This invention belongs to the field of waste heat utilization of steam condensate in industrial plants and design of central air conditioning water systems, specifically relating to a fan coil air conditioning water system with steam condensate as the heat source. Background Technology

[0002] In industrial buildings, such as those in the chemical and fiber industries producing polyester filament, polyester staple fiber, spandex, and polyester film, stable operation of process production equipment requires steam heating and heat tracing at a certain flow rate. Additionally, depending on production needs, some functional areas within the plant require centralized air conditioning, specifically a "cold / heat source + combined air conditioning unit" configuration. During winter operation, the heating section of the combined air conditioning unit typically uses low-pressure saturated steam.

[0003] In these heat exchange processes, steam releases its latent heat and generates condensate. The flow inside the pipe is a non-full-pipe, two-phase flow of gas and liquid, which is neither continuous nor stable. Although the temperature of the condensate is as high as 90-100℃, it cannot be directly connected to the air conditioning hot water network or the plant's heating network. If the waste heat and water volume of the condensate are not recovered and utilized, it needs to be cooled to below 35℃ before being discharged into the municipal sewage network. This not only wastes the heat energy of the condensate but also results in a loss of condensate volume, which is detrimental to the company's green and sustainable development. Summary of the Invention

[0004] Therefore, this invention provides a fan coil air conditioning water system with steam condensate as the heat source, so as to maximize the utilization of waste heat from steam condensate generated in industrial plants and solve the problem of low utilization rate and waste of low-grade heat energy from steam condensate in industrial plants.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a fan coil air conditioning water system with steam condensate as the heat source, comprising a steam condensate subsystem, an air conditioning hot water subsystem, a steam subsystem, a water replenishment and pressure stabilization device for the hot water subsystem, a PLC control subsystem, and an air conditioning chilled water subsystem;

[0006] The steam condensate subsystem is used to recover condensate from production equipment in industrial plants or combined air conditioning units in air conditioning rooms where the heat source is low-pressure steam. The steam condensate subsystem includes an open condensate tank, condensate pipes, a condensate pump, and a condensate tank in the plant area.

[0007] The air conditioning hot water subsystem is used to provide a heat source for the air conditioning terminals under winter operating conditions. The air conditioning hot water subsystem includes hot water pipes, a first filter, a hot water circulation pump, a water-to-water heat exchanger, and a fan coil unit.

[0008] The steam subsystem is used to provide the heating load required by the air conditioning water system under winter operating conditions. The steam subsystem includes a steam-water heat exchanger, steam pipes, a second filter, a steam electric regulating valve group, and a steam trap group.

[0009] The water replenishment and pressure stabilization device of the hot water subsystem adopts a variable frequency automatic water replenishment pump for water replenishment and pressure stabilization, and the water replenishment and pressure stabilization device of the hot water subsystem uses the open condensate tank of the steam condensate subsystem as the water replenishment source;

[0010] The PLC control subsystem is used to provide control circuits and control implementation instructions for the air conditioning and hot water subsystem;

[0011] The air conditioning chilled water subsystem is used to provide a cooling source for the air conditioning terminals under summer operating conditions. The air conditioning chilled water subsystem includes a chiller, a chilled water circulation pump set, and a third filter.

[0012] As a preferred solution for fan coil air conditioning water systems with steam condensate as the heat source, the combined air conditioning units in the production equipment and air conditioning room of the industrial plant use steam heating or heat tracing to generate steam condensate, which is then transported and centrally recycled to the open condensate tank through the condensate pipeline.

[0013] The liquid level in the open condensate tank is between the low alarm level and the high alarm level.

[0014] When the liquid level in the open condensate tank reaches the high level alarm, the condensate pump is started in a chain. The condensate in the open condensate tank is heated by the return water of the fan coil unit through the water-to-water heat exchanger and then transported to the condensate tank in the plant area for demineralized water recovery.

[0015] When the liquid level in the open condensate tank reaches a low level alarm, the condensate pump is shut off, and the open condensate tank begins to store water.

[0016] The open condensate tank is provided with an overflow port on the top side. When the liquid level reaches the overflow port, the condensate is discharged into the condensate cooling pool through the overflow pipe.

[0017] The open condensate tank is equipped with a drain outlet at the bottom. When the open condensate tank is being repaired or cleaned, the drain valve is opened to discharge the condensate into the condensate cooling pool.

[0018] The top of the open condensate tank is provided with a vent hole; the outer surface of the open condensate tank is provided with insulation material, which is made of rock wool board or aluminum silicate board, and the outer protective layer of the insulation material is made of aluminum plate or galvanized steel plate.

[0019] As a preferred embodiment of the fan coil air conditioning water system with steam condensate as the heat source, the capacity of the open condensate tank is determined based on the hourly condensate flow rate of the plant area and the operating time of the fan coil air conditioning system; the condensate pump is turned on for heat exchange only during the fan coil unit's operating period, and stops operating when the fan coil air conditioning is turned off at night; the open condensate tank can hold the amount of water needed for the condensate pump to stop operating at night.

[0020] The open condensate tank is used for condensate recovery and also serves as a makeup water tank for the air conditioning hot water subsystem; the capacity of the open condensate tank is included in the expansion of the air conditioning hot water subsystem.

[0021] The pump inlet of the condensate pump is connected to a reducer, and the pump outlet of the condensate pump is connected to a flexible metal connector. A pressure gauge and a check valve are installed at the downstream end of the flexible metal connector at the pump outlet. Two condensate pumps are installed, one in use and one on standby, and are switched by the first shut-off valve.

[0022] The flow rate of the condensate pump is the average hourly flow rate of the total amount of steam condensate recovered in 24 hours during daytime operation.

[0023] As a preferred solution for fan coil air conditioning water systems with steam condensate as the heat source, during winter heating, the hot water return from the fan coil unit in the air-conditioned room is first purified by the first filter, then the pressure is increased by the hot water circulation pump, and the water absorbs heat from the condensate in the open condensate tank in the water-to-water heat exchanger, and then flows through the steam-to-water heat exchanger.

[0024] The first filter is equipped with a bypass pipeline and a shut-off valve is used to switch it; pressure gauges are installed before and after the first filter to detect the pressure difference before and after the first filter.

[0025] A pressure gauge and a check valve are installed at the downstream end of the metal flexible connection pipe at the pump outlet of the hot water circulation pump; a total of 2 hot water circulation pumps are installed, 1 for use and 1 for standby, which are switched by a third shut-off valve; the bypass pipeline of the hot water circulation pump is used to absorb the water hammer impact that occurs when the pump stops; a low-pressure discharge valve is installed on the inlet pipe of the hot water circulation pump.

[0026] The flow rate of the hot water circulation pump is the hot water flow rate of the fan coil unit air conditioner, which is determined according to the design heat load of the air-conditioned room.

[0027] As a preferred embodiment of the fan coil air conditioning water system with steam condensate as the heat source, the water-to-water heat exchanger is a plate heat exchanger, the primary fluid is condensate from the open condensate tank, and the secondary fluid is return water from the fan coil unit.

[0028] The primary water flow rate of the water-to-water heat exchanger is determined based on the amount of condensate that can be recycled in the plant area, while the secondary fan coil unit hot water flow rate is determined based on the design heat load of the air-conditioned room.

[0029] As a preferred embodiment of the fan coil air conditioning water system with steam condensate as the heat source, if the temperature of the air conditioning hot water after absorbing heat from the steam condensate through the steam subsystem reaches the rated water supply temperature of the fan coil unit, then no additional heat is needed from the steam source, and the steam-water heat exchanger will not operate; if the temperature of the air conditioning hot water after passing through the water-water heat exchanger does not reach the rated water supply temperature of the fan coil unit, heat is supplemented through the steam source so that the air conditioning hot water reaches the rated water supply temperature of the fan coil unit after being heated in the steam-water heat exchanger.

[0030] As a preferred option for a fan coil air conditioning water system with steam condensate as the heat source, the steam source is low-pressure saturated steam or low-pressure superheated steam. The steam source first passes through a second filter to remove impurities and then enters a steam-water heat exchanger. The hot side outlet of the steam-water heat exchanger is the condensate from the steam source, which is discharged to the open condensate tank after passing through a condensate trap group.

[0031] The primary inlet fluid of the steam-water heat exchanger is steam from the plant area, and its enthalpy value is determined based on the steam pressure and temperature parameters provided by the plant area. The secondary inlet fluid is the return water from the fan coil units after preliminary heating by the water-to-water heat exchanger. The primary outlet fluid is the condensate from the steam after the latent heat of steam is released. The secondary outlet temperature is a set value to ensure a constant supply water temperature for the fan coil units at the air conditioning terminals. The primary steam flow rate of the steam-water heat exchanger is determined based on the heat balance between the primary and secondary sides. By connecting the water-to-water heat exchanger and the steam-water heat exchanger in series, the design heat load requirements of the air-conditioned rooms are guaranteed.

[0032] As a preferred solution for a fan coil air conditioning water system with steam condensate as the heat source, the water replenishment and pressure stabilization device of the hot water subsystem adopts a variable frequency automatic water replenishment pump for water replenishment and pressure stabilization. The pressure replenishment point is set on the pipeline at the inlet of the hot water circulation pump. A safety valve is installed after the valve group of the water replenishment pump. When the system is over-pressurized, the safety valve opens and the pressure is released to the open condensate tank through the return pipe.

[0033] The inlet and outlet of the water supply pump are connected to a reducer and a flexible metal connector, respectively. A pressure gauge and a check valve are installed at the end of the flexible metal connector at the pump outlet. Two water supply pumps are installed, one for operation and one for standby, and are switched via a second shut-off valve.

[0034] As a preferred solution for a fan coil air conditioning water system with steam condensate as the heat source, the PLC control subsystem displays the high-level alarm and low-level alarm signals of the open condensate tank and realizes the start and stop control of the condensate pump through the PLC control circuit.

[0035] The PLC control subsystem, based on the pressure monitoring value after the water supply pump valve group, realizes the frequency conversion automatic water supply control and start / stop switching of the water supply pump through the PLC control circuit and the electrical control box panel; and realizes the start / stop switching of the hot water circulation pump through the PLC control circuit and the electrical control box panel.

[0036] The PLC control subsystem adjusts the opening of the steam electric regulating valve based on the temperature monitoring value set at the outlet of the steam-water heat exchanger by the water supply pipe of the fan coil unit, thereby regulating the flow rate of the steam source.

[0037] As a preferred solution for a fan coil air conditioning water system with steam condensate as the heat source, the air conditioning chilled water subsystem, during summer cooling operation, has its rated supply and return water from the fan coil chilled water return of the air-conditioned room fan coil unit. The water is first purified by a third filter, then its pressure is increased by a chilled water circulation pump unit, and after being cooled in the evaporator of the chiller, the air conditioning chilled water reaches the rated supply water temperature of the fan coil unit.

[0038] During winter heating operation, both the supply and return water main switching valves of the air conditioning chilled water subsystem are closed, while both the supply and return water main switching valves of the air conditioning hot water subsystem are open. During summer cooling operation, both the supply and return water main switching valves of the air conditioning chilled water subsystem are open, while both the supply and return water main switching valves of the air conditioning hot water subsystem are closed.

[0039] This invention has the following advantages: it includes a steam condensate subsystem, an air conditioning hot water subsystem, a steam subsystem, a water replenishment and pressure stabilization device for the hot water subsystem, a PLC control subsystem, and an air conditioning chilled water subsystem; the steam condensate subsystem is used to recover condensate from combined air conditioning units in industrial plant production equipment or air conditioning rooms where the heat source is low-pressure steam, and includes an open condensate tank, condensate pipes, a condensate pump, and a plant condensate tank; the air conditioning hot water subsystem is used to provide a heat source for air conditioning terminals under winter operating conditions, and includes hot water pipes, a first filter, a hot water circulation pump, a water-to-water heat exchanger, and fan coil units; steam... The subsystem provides the heating load required by the air conditioning water system under winter conditions. The steam subsystem includes a steam-water heat exchanger, steam pipes, a second filter, a steam electric regulating valve group, and a steam trap group. The hot water subsystem uses a variable frequency automatic water supply pump for water supply and pressure regulation, and the water supply source for the hot water subsystem is the steam condensate subsystem. The PLC control subsystem provides control circuits and control operation commands for the air conditioning hot water subsystem. The air conditioning chilled water subsystem provides a cold source for the air conditioning terminals under summer conditions. The air conditioning chilled water subsystem includes a chiller, a chilled water circulation pump group, a third filter, and a condition switching valve. This invention avoids the drawbacks of direct discharge of steam condensate from industrial plants, greatly saves energy and reduces emissions, and significantly improves the utilization rate of low-grade heat energy from steam condensate in industrial plants, resulting in significant energy-saving and efficiency-enhancing effects. The open condensate tank serves as both a steam condensate storage tank and a makeup water tank for a constant pressure water supply device, making it more flexible. The air conditioning hot water process is a closed-loop system, ensuring stable and reliable operation, and pioneering a new process for the recovery and utilization of condensate from industrial plants. Attached Figure Description

[0040] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of a fan coil air conditioning water system with steam condensate as the heat source, provided in an embodiment of the present invention.

[0042] In the diagram: 1. Open condensate tank; 2. Condensate pipe; 3. Condensate pump; 4. Plant condensate tank; 5. Hot water pipe; 6. First filter; 7. Hot water circulation pump; 8. Water-to-water heat exchanger; 9. Fan coil unit; 10. Steam-water heat exchanger; 11. Steam pipe; 12. Second filter; 13. Steam electric regulating valve assembly; 14. Steam trap assembly; 15. Make-up water pump; 16. Refrigeration unit; 17. Cold water circulation pump assembly; 18. Third filter; 19. Overflow port; 20. Drain port; 21. Vent. Detailed Implementation

[0043] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] See Figure 1 This invention provides a fan coil air conditioning water system with steam condensate as the heat source, including a steam condensate subsystem, an air conditioning hot water subsystem, a steam subsystem, a water replenishment and pressure stabilization device for the hot water subsystem, a PLC control subsystem, and an air conditioning chilled water subsystem. The steam condensate subsystem is used to recover condensate from production equipment in industrial plants or combined air conditioning units in air conditioning rooms where the heat source is low-pressure steam. The steam condensate subsystem includes an open condensate tank 1, condensate pipes 2, a condensate pump 3, and a plant condensate tank 4. The air conditioning hot water subsystem is used to provide a heat source for air conditioning terminals under winter operating conditions. The air conditioning hot water subsystem includes a hot water pipe 5, a first filter 6, a hot water circulation pump 7, a water-to-water heat exchanger 8, and fan coil units. 9; The steam subsystem is used to provide the heating load required by the air conditioning water system under winter conditions. The steam subsystem includes a steam-water heat exchanger 10, a steam pipe 11, a second filter 12, a steam electric regulating valve group 13, and a steam trap group 14; The water replenishment and pressure stabilization device of the hot water subsystem adopts a variable frequency automatic water replenishment pump 15 for water replenishment and pressure stabilization. The water replenishment and pressure stabilization device of the hot water subsystem uses the open condensate tank 1 of the steam condensate subsystem as the water replenishment source; The PLC control subsystem is used to provide control circuits and control implementation operation commands for the air conditioning hot water subsystem; The air conditioning chilled water subsystem is used to provide a cold source for the air conditioning terminals under summer conditions. The air conditioning chilled water subsystem includes a chiller 16, a chilled water circulation pump group 17, and a third filter 18.

[0045] In this embodiment, the combined air conditioning unit in the industrial plant production unit and the air conditioning room uses 2.5t / h of steam for heating and steam tracing. The steam condensate generated by the combined air conditioning unit in the air conditioning room after steam heating has a flow rate of 3.5t / h. The condensate is transported and collected to the open condensate tank 1 through the condensate pipeline 2.

[0046] The open-type condensate tank 1 has a liquid level between the low alarm and the high alarm levels. When the liquid level in the open-type condensate tank 1 reaches the high alarm level, the interlocking condensate pump 3 starts. The condensate in the open-type condensate tank 1 is heated by the return water of the fan coil unit 9 through the water-to-water heat exchanger 8 and then transported to the condensate tank 4 in the plant area for demineralized water recovery. When the liquid level in the open-type condensate tank 1 reaches the low alarm level, the interlocking condensate pump 3 stops, and the open-type condensate tank 1 begins to store water. An overflow port 19 is provided on the top side of the open-type condensate tank 1. When the liquid level reaches the overflow port 19, the condensate is discharged to the condensate cooling pool through the overflow pipe. A drain port 20 is provided at the bottom of the open-type condensate tank 1. When the open-type condensate tank 1 is under maintenance or being cleaned, the drain valve is opened to discharge the condensate to the condensate cooling pool.

[0047] In this embodiment, the open-type condensate tank 1 has a vent 21 at the top and is an atmospheric pressure tank. The temperature of the steam condensate from the production equipment and combined air conditioning units in the industrial plant is 90-100℃, therefore, the outer surface of the open-type condensate tank 1 is insulated. Common insulation materials such as rock wool board or aluminum silicate board can be used. The outer protective layer of the insulation material is usually made of aluminum plate or galvanized steel plate.

[0048] In this embodiment, the capacity of the open condensate tank 1 is determined based on the hourly condensate flow rate of the factory area and the operating time of the fan coil unit 9 air conditioning system. It is assumed that the operating time of the fan coil unit 9 air conditioning in the office area is from 8:00 to 22:00, and the fan coil unit 9 stops operating from 22:00 to 8:00 in the morning. The condensate pump 3 is turned on for heat exchange only during the operating time of the fan coil unit 9. When the fan coil unit 9 air conditioning is turned off at night, the condensate pump 3 stops operating. Therefore, the open condensate tank 1 has a water storage function, and the open condensate tank 1 can hold the water volume of approximately 60t for one night when the condensate pump 3 stops operating.

[0049] In this embodiment, the open condensate tank 1 serves not only as a condensate recovery tank but also as a makeup water tank for the air conditioning hot water subsystem; the capacity of the open condensate tank 1 is factored into the expansion of the air conditioning hot water subsystem; the effective volume of the selected open condensate tank 1 is V = 72 m³. 3 .

[0050] The inlet of condensate pump 3 is connected to a reducer, and the outlet of condensate pump 3 is connected to a flexible metal connector. A pressure gauge and a check valve are installed at the downstream end of the flexible metal connector at the pump outlet. To ensure the safe and stable operation of the system, two condensate pumps 3 are installed, one for operation and one for standby, and are switched through the first shut-off valve. The flow rate of condensate pump 3 is the average hourly flow rate of the total amount of steam condensate recovered in 24 hours during daytime operation, which is 8.4 t / h.

[0051] In this embodiment, the air conditioning hot water subsystem provides a heat source for the air conditioning terminals during winter operation. During winter heating, the rated supply and return water temperatures of the fan coil unit 9 are 50℃ / 60℃. The hot water return pipe from the fan coil unit 9 in the air-conditioned room has a temperature of 50℃. It is first purified by the first filter 6, then pressurized by the hot water circulation pump 7, and absorbs heat from the condensate in the open condensate tank 1 in the water-to-water heat exchanger 8. It then flows through the steam-to-water heat exchanger 10 to ensure that the air conditioning hot water reaches the rated supply water temperature of 60℃ for the fan coil unit 9.

[0052] The first filter 6 of the air conditioning hot water subsystem is used to filter metal debris, dirt, and other impurities in the air conditioning hot water subsystem. The first filter 6 is equipped with a bypass pipeline and a shut-off valve is used for switching. Pressure gauges are installed before and after the first filter 6 to detect the pressure difference before and after the first filter 6.

[0053] The hot water circulation pump 7 in the air conditioning hot water subsystem is equipped with a pressure gauge and a check valve at the downstream end of the metal flexible connection pipe at the pump outlet. Two hot water circulation pumps 7 are installed, one in operation and one on standby, switched via a third shut-off valve. Furthermore, the bypass pipe of the hot water circulation pump 7 is used to absorb water hammer impacts occurring during pump shutdown, and a low-pressure discharge valve is installed on the inlet pipe of the hot water circulation pump 7 to protect the pump. The flow rate of the hot water circulation pump 7 is the same as the air conditioning hot water flow rate of the fan coil unit 9, determined based on the design heat load of the air-conditioned room. The design heat load of the air-conditioned room is 488kW, requiring an air conditioning hot water flow rate of 42.0t / h from the fan coil unit 9.

[0054] In this embodiment, the water-to-water heat exchanger 8 of the air conditioning hot water subsystem is a plate heat exchanger. The primary fluid is condensate from the open condensate tank 1, and the secondary fluid is return water from the fan coil unit 9. The primary water flow rate of the water-to-water heat exchanger 8 is determined based on the amount of condensate that can be recycled in the plant area, and the secondary air conditioning hot water flow rate of the fan coil unit 9 is determined based on the heat load of the air-conditioned room.

[0055] Specifically, the primary side condensate inlet temperature of water-to-water heat exchanger 8 is t1' = 95℃, and the primary side condensate outlet temperature is t1” = 55℃; the secondary side return water inlet temperature of fan coil unit 9 is t2' = 50℃, and the secondary side hot water outlet temperature is t2” = 58℃. The primary side steam condensate flow rate of water-to-water heat exchanger 8 is the average hourly flow rate of the total amount of steam condensate recovered in 24 hours during daytime operation, which is 8.4 t / h. The secondary side air conditioning water flow rate of fan coil unit 9 is 42.0 t / h. The heat exchange capacity of water-to-water heat exchanger 8 is 390.4 kW.

[0056] In this embodiment, if the temperature of the air-conditioning hot water after absorbing the heat of the steam condensate from the water-water heat exchanger 8 reaches the rated water supply temperature of 60°C for the fan coil unit 9, then no additional heat is needed from the steam source, and the steam-water heat exchanger 10 will not operate. If the temperature of the air-conditioning hot water after passing through the water-water heat exchanger 8 does not reach the rated water supply temperature of 60°C for the fan coil unit 9, heat is supplemented by the steam source so that the air-conditioning hot water reaches the rated water supply temperature of 60°C for the fan coil unit 9 after being heated in the steam-water heat exchanger 10.

[0057] The steam source is low-pressure saturated steam or low-pressure superheated steam. The steam temperature and pressure parameters provided by the plant are P = 0.3 MPa and T = 144℃. The steam source first enters the steam-water heat exchanger 10 after being purified by the second filter 12. The hot side outlet of the steam-water heat exchanger 10 is the condensate from the steam source, which is discharged to the open condensate tank 1 after passing through the steam trap group.

[0058] The primary inlet fluid of the steam-water heat exchanger 10 is steam from the plant area, specifically low-pressure saturated steam with a pressure of P1 = 0.3 MPa and a corresponding saturation temperature of T1 = 144℃. The secondary inlet fluid is the return water from the fan coil unit 9, preheated by the water-to-water heat exchanger 8, at a temperature of T2' = t2” = 58℃. The primary outlet fluid is the condensate from the steam after the release of latent heat, with a temperature of T1” = 95℃. The secondary hot water outlet temperature of the steam-water heat exchanger 10 is set at T2” = 60℃ to ensure a constant supply water temperature to the fan coil unit 9. The heat exchange capacity of the steam-water heat exchanger 10 is 97.6 kW. The two-stage series connection of the water-to-water heat exchanger 8 and the steam-water heat exchanger 10 satisfies the design heat load requirements of the air-conditioned room.

[0059] In this embodiment, the water replenishment and pressure stabilization device of the hot water subsystem adopts a variable frequency automatic water replenishment pump 15, and the pressure stabilization and water replenishment point is set on the pipeline at the inlet of the hot water circulation pump 7. A safety valve is installed after the valve group of the water replenishment pump 15. When the system is over-pressurized, the safety valve opens and the pressure is released to the open condensate tank 1 through the return pipe. The pump inlet and outlet of the water replenishment pump 15 are connected to a reducer and a metal flexible connection pipe, respectively. A pressure gauge and a check valve are installed after the metal flexible connection pipe at the pump outlet. Two water replenishment pumps 15 are installed, one in use and one on standby, and are switched through a second shut-off valve.

[0060] In this embodiment, the PLC control subsystem displays the high and low alarm signals of the open condensate tank 1 and controls the start and stop of the condensate pump 3 through the PLC control circuit. Based on the pressure monitoring value after the valve group of the make-up water pump 15, the PLC control subsystem controls the frequency conversion automatic water replenishment and start / stop switching of the make-up water pump 15 through the PLC control circuit and the electrical control box panel. It also controls the start and stop switching of the hot water circulation pump 7 through the PLC control circuit and the electrical control box panel. Finally, based on the temperature monitoring value set at the outlet of the steam-water heat exchanger 10 by the water supply pipe of the fan coil unit 9, the PLC control subsystem adjusts the opening of the steam electric regulating valve through the PLC control circuit to regulate the steam source flow rate.

[0061] In this embodiment, during the summer cooling operation, the rated supply and return water of the air conditioning chilled water subsystem comes from the chilled water return of the air conditioning room fan coil unit 9. The rated supply and return water temperature of the fan coil unit 9 is 7℃ / 12℃. The temperature of the chilled water return pipe from the air conditioning room fan coil unit 9 is 12℃. The water is first purified by the third filter 18, and then the pressure is increased by the chilled water circulation pump group 17. After being cooled in the evaporator of the chiller 16, the chilled water reaches the rated supply water temperature of 7℃ of the fan coil unit 9.

[0062] For the designated air-conditioned area, the fan coil unit 9 air conditioning water system uses a two-pipe system, with the chilled water pipe for summer cooling and the hot water pipe for winter heating shared. Therefore, a bridging connection between the heat source and the cold source is required on the main water system pipe for the air-conditioned area. During winter heating, both the supply and return water main switching valves of the chilled water subsystem are closed, while both the supply and return water main switching valves of the hot water subsystem are open. During summer cooling, both the supply and return water main switching valves of the chilled water subsystem are open, while both the supply and return water main switching valves of the hot water subsystem are closed.

[0063] In summary, this invention includes a steam condensate subsystem, an air conditioning hot water subsystem, a steam subsystem, a water replenishment and pressure stabilization device for the hot water subsystem, a PLC control subsystem, and an air conditioning chilled water subsystem. The steam condensate subsystem is used to recover condensate from combined air conditioning units in industrial plant production equipment or air conditioning rooms where the heat source is low-pressure steam. The steam condensate subsystem includes an open condensate tank 1, condensate pipes 2, a condensate pump 3, and a plant condensate tank 4. The air conditioning hot water subsystem provides a heat source for air conditioning terminals during winter operation. The air conditioning hot water subsystem includes hot water pipes 5, a first filter 6, a hot water circulation pump 7, a water-to-water heat exchanger 8, and a fan coil unit 9. The steam subsystem is used to... The steam subsystem supplies the heating load required by the air conditioning water system under winter operating conditions. It includes a steam-water heat exchanger 10, steam pipes 11, a second filter 12, a steam electric regulating valve group 13, and a steam trap group 14. The water supply and pressure stabilization device of the hot water subsystem adopts a variable frequency automatic water supply pump 15, which uses the steam condensate subsystem as the water supply source. The PLC control subsystem provides control circuits and control operation commands for the air conditioning hot water subsystem. The air conditioning chilled water subsystem provides a cold source for the air conditioning terminals under summer operating conditions. It includes a chiller 16, a chilled water circulation pump group 17, a third filter 18, and an operating condition switching valve. This invention avoids the drawbacks of direct discharge of steam condensate from industrial plants, greatly saves energy and reduces emissions, and significantly improves the utilization rate of low-grade heat energy from steam condensate in industrial plants, thus having a significant energy-saving and efficiency-enhancing effect. The open condensate tank 1 serves as both a steam condensate storage tank and a makeup water tank for a constant pressure water supply device, making it more flexible. The air conditioning hot water process is a closed-loop system, which is stable and reliable in operation, and has pioneered a new process for the recycling and utilization of condensate in industrial plants.

[0064] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A fan coil unit air conditioning water system with steam condensate as the heat source, characterized in that, It includes a steam condensate subsystem, an air conditioning hot water subsystem, a steam subsystem, a water supply and pressure stabilization device for the air conditioning hot water subsystem, a PLC control subsystem, and an air conditioning chilled water subsystem; The steam condensate subsystem is used to recover condensate from production equipment in industrial plants or combined air conditioning units in air conditioning rooms where the heat source is low-pressure steam. The steam condensate subsystem includes an open condensate tank (1), condensate pipes (2), a condensate pump (3), and a plant condensate tank (4). The inlet of the open condensate tank (1) is connected to the condensate pipes (2), and the outlet of the open condensate tank (1) is connected to the condensate pump (3). The air conditioning hot water subsystem is used to provide a heat source for the air conditioning terminals under winter operating conditions. The air conditioning hot water subsystem includes a hot water pipe (5), a first filter (6), a hot water circulation pump (7), a water-to-water heat exchanger (8), and a fan coil unit (9). The fan coil unit (9), the first filter (6), the hot water circulation pump (7), and the secondary side of the water-to-water heat exchanger (8) are sequentially connected to the hot water pipe (5). The condensate pump (3) is connected to the plant condensate tank (4) through the primary side of the water-to-water heat exchanger (8). The secondary side of the water-to-water heat exchanger (8) is connected to the secondary side inlet of the steam-water heat exchanger (10), and the primary side outlet of the steam-water heat exchanger (10) is connected to the open condensate tank (1). The steam subsystem is used to provide the heating load required by the air conditioning water system under winter conditions. The steam subsystem includes a steam-water heat exchanger (10), a steam pipe (11), a second filter (12), a steam electric regulating valve group (13), and a steam trap group (14). The second filter (12) and the steam electric regulating valve group (13) are connected to the steam pipe (11) in sequence. The primary side inlet of the steam-water heat exchanger (10) is connected to the steam pipe (11), and the steam trap group (14) is connected to the outlet of the steam-water heat exchanger (10). The steam trap group (14) is also connected to the inlet of the open condensate tank (1). The water replenishment and pressure stabilization device of the air conditioning hot water subsystem adopts a variable frequency automatic water replenishment pump (15) for water replenishment and pressure stabilization. The water replenishment and pressure stabilization device of the air conditioning hot water subsystem uses the open condensate tank (1) of the steam condensate subsystem as the water replenishment source. The water replenishment port of the variable frequency automatic water replenishment pump (15) is connected between the fan coil unit (9) and the first filter (6). The PLC control subsystem is used to provide control circuits and control implementation instructions for the air conditioning and hot water subsystem; The air conditioning chilled water subsystem is used to provide a cold source for the air conditioning terminal under summer conditions. The air conditioning chilled water subsystem includes a chiller (16), a chilled water circulation pump group (17), and a third filter (18).

2. The fan coil air conditioning water system with steam condensate as the heat source according to claim 1, characterized in that, The combined air conditioning units in the production equipment and air conditioning room of the industrial plant use steam heating or heat tracing to generate steam condensate, which is then transported and centrally collected to the open condensate tank (1) through the condensate pipeline (2). The liquid level of the open condensate tank (1) is between the low alarm level and the high alarm level; When the liquid level of the open condensate tank (1) reaches the high level alarm, the condensate pump (3) is started in a chain. The condensate in the open condensate tank (1) is heated by the return water of the fan coil unit (9) through the water-to-water heat exchanger (8) and then transported to the plant condensate tank (4) for demineralized water recovery of condensate volume. When the liquid level in the open condensate tank (1) reaches a low level alarm, the condensate pump (3) is shut off, and the open condensate tank (1) begins to store water. An overflow port (19) is provided on the top side of the open condensate tank (1). When the liquid level reaches the overflow port (19), the condensate is discharged to the condensate cooling pool through the overflow pipe. The open condensate tank (1) is provided with a drain outlet (20) at the bottom. When the open condensate tank (1) is being repaired or cleaned, the drain valve is opened to discharge the condensate into the condensate cooling pool. The top of the open condensate tank (1) is provided with a vent (21); the outer surface of the open condensate tank (1) is provided with insulation material, which is made of rock wool board or aluminum silicate board, and the outer protective layer of the insulation material is made of aluminum plate or galvanized steel plate.

3. A fan coil air conditioning water system with steam condensate as the heat source according to claim 2, characterized in that, The capacity of the open condensate tank (1) is determined based on the hourly flow rate of condensate in the plant area and the operating time of the fan coil unit (9) air conditioning system; the condensate pump (3) is turned on for heat exchange only during the operating time of the fan coil unit (9), and the condensate pump (3) stops operating when the fan coil unit (9) air conditioning is turned off at night; the open condensate tank (1) holds the amount of water stored when the condensate pump (3) stops operating at night; The open condensate tank (1) is used for condensate recovery and also serves as a makeup water tank for the air conditioning hot water subsystem; the capacity of the open condensate tank (1) is included in the expansion of the air conditioning hot water subsystem. The pump inlet of the condensate pump (3) is connected to a reducer, and the pump outlet of the condensate pump (3) is connected to a metal flexible connecting pipe. A pressure gauge and a check valve are installed at the rear end of the metal flexible connecting pipe at the pump outlet. A total of 2 condensate pumps (3) are installed, 1 for use and 1 for standby, and are switched by the first shut-off valve. The flow rate of the condensate pump (3) is the average hourly flow rate of the total amount of steam condensate recovered in 24 hours during daytime operation.

4. A fan coil air conditioning water system with steam condensate as the heat source according to claim 3, characterized in that, During winter heating, the hot water return from the fan coil unit (9) in the air-conditioned room is first purified by the first filter (6), then the pressure is increased by the hot water circulation pump (7), and it absorbs the heat from the condensate from the open condensate tank (1) in the water-to-water heat exchanger (8), and then flows through the steam-water heat exchanger (10), and then flows into the fan coil unit (9). The first filter (6) is provided with a bypass pipeline and a shut-off valve is used to switch it; pressure gauges are installed before and after the first filter (6) to detect the pressure difference before and after the first filter (6); A pressure gauge and a check valve are installed at the rear end of the metal flexible connection pipe at the pump outlet of the hot water circulation pump (7); a total of 2 hot water circulation pumps (7) are installed, 1 for use and 1 for standby, which are switched by the third shut-off valve; the bypass pipeline of the hot water circulation pump (7) is used to absorb the water hammer impact that occurs when the pump stops; a low discharge valve is installed on the inlet pipe of the hot water circulation pump (7). The flow rate of the hot water circulation pump (7) is the same as the hot water flow rate of the fan coil unit (9) for air conditioning, which is determined according to the design heat load of the air-conditioned room.

5. A fan coil air conditioning water system with steam condensate as the heat source according to claim 4, characterized in that, The water-to-water heat exchanger (8) is a plate heat exchanger. The primary fluid is condensate from the open condensate tank (1), and the secondary fluid is return water from the fan coil unit (9). The primary water flow rate of the water-to-water heat exchanger (8) is determined based on the amount of condensate that can be recycled in the plant area, and the secondary fan coil unit (9) air conditioning hot water flow rate is determined based on the design heat load of the air-conditioned room.

6. A fan coil air conditioning water system with steam condensate as the heat source according to claim 5, characterized in that, If the temperature of the air-conditioning hot water after absorbing the heat of the steam condensate in the water-water heat exchanger (8) reaches the rated water supply temperature of the fan coil unit (9), then the steam source does not need to supplement the heat and the steam-water heat exchanger (10) will not operate; if the temperature of the air-conditioning hot water after passing through the water-water heat exchanger (8) does not reach the rated water supply temperature of the fan coil unit (9), the steam source will supplement the heat so that the air-conditioning hot water reaches the rated water supply temperature of the fan coil unit (9) after being heated in the steam-water heat exchanger (10).

7. A fan coil air conditioning water system with steam condensate as the heat source according to claim 6, characterized in that, The steam source is low-pressure saturated steam or low-pressure superheated steam. The steam source first passes through the second filter (12) to remove impurities and then enters the steam-water heat exchanger (10). The primary side outlet of the steam-water heat exchanger (10) is the condensate of the steam source, which is discharged to the open condensate tank (1) after passing through the steam trap group. The primary side inlet fluid of the steam-water heat exchanger (10) is the steam source from the plant area, and its enthalpy value is determined according to the steam pressure and temperature parameters provided by the plant area; the secondary side inlet fluid is the return water of the fan coil unit (9) after being preheated by the water-water heat exchanger (8); the primary side outlet fluid is the steam condensate after the steam releases its latent heat; the secondary side outlet temperature is a set value to ensure that the water supply temperature of the air conditioning terminal fan coil unit is constant; the primary side steam flow rate of the steam-water heat exchanger (10) is determined according to the heat balance between the primary and secondary sides; the design heat load requirements of the air-conditioned room are guaranteed by the two-stage series connection of the water-water heat exchanger (8) and the steam-water heat exchanger (10).

8. A fan coil air conditioning water system with steam condensate as the heat source according to claim 7, characterized in that, The water replenishment and pressure stabilization device of the air conditioning hot water subsystem adopts a variable frequency automatic water replenishment pump (15) for water replenishment and pressure stabilization. The pressure replenishment point is set on the pipeline at the inlet of the hot water circulation pump (7). A safety valve is set after the valve group of the water replenishment pump (15). When the system is over-pressured, the safety valve opens and the pressure is released to the open condensate tank (1) through the return pipe. The inlet and outlet of the water supply pump (15) are connected to a reducer and a flexible metal connector, respectively. A pressure gauge and a check valve are installed at the rear end of the flexible metal connector at the pump outlet. A total of two water supply pumps (15) are installed, one for use and one for standby, and are switched by the second shut-off valve.

9. A fan coil air conditioning water system with steam condensate as the heat source according to claim 8, characterized in that, The PLC control subsystem displays the high and low alarm signals of the open condensate tank (1) and controls the start and stop of the condensate pump (3) through the PLC control circuit. The PLC control subsystem, based on the pressure monitoring value after the valve group of the water supply pump (15), realizes the frequency conversion automatic water supply control and start / stop switching of the water supply pump (15) through the PLC control line and the electrical control box panel; and realizes the start / stop switching of the hot water circulation pump (7) through the PLC control line and the electrical control box panel. The PLC control subsystem adjusts the opening of the steam electric regulating valve through the PLC control circuit based on the temperature monitoring value set at the outlet of the steam-water heat exchanger (10) of the water supply pipe of the fan coil unit (9), thereby realizing the flow regulation of the steam source.

10. A fan coil air conditioning water system with steam condensate as the heat source according to claim 9, characterized in that, During the summer cooling operation, the rated supply and return water of the air conditioning chilled water subsystem comes from the chilled water return of the air conditioning room fan coil unit (9). It is first purified by the third filter (18), and then the pressure is increased by the chilled water circulation pump group (17). After being cooled in the evaporator of the chiller (16), the air conditioning chilled water reaches the rated supply water temperature of the fan coil unit (9). During winter heating operation, both the supply and return water main switching valves of the air conditioning chilled water subsystem are closed, while both the supply and return water main switching valves of the air conditioning hot water subsystem are open. During summer cooling operation, both the supply and return water main switching valves of the air conditioning chilled water subsystem are open, while both the supply and return water main switching valves of the air conditioning hot water subsystem are closed.

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