Water circulation system for realizing dead steam waste heat recovery

Abstract

The invention belongs to the technical field of energy-saving and environment-friendly equipment, and particularly relates to a water circulation system for achieving dead steam waste heat recovery. The waste heat recovery device is used for recovering waste heat of waste steam which is discharged unstably in production and realizing cyclic utilization of production water. The water circulation system comprises a buffer water tank, a heat storage water tank, a dead steam recovery device, a main cold water pump, a heat exchanger, a main hot water pump, a pressure sensor and a controller. Circulating water internally circulates in the buffer water tank, the heat storage water tank, the dead steam recovery device and the heat exchanger. The dead steam recovery device comprises a condenser, a hot well and an axial flow fan. The pressure sensor detects the dead steam pressure at the front end. And the controller is electrically connected with the main cold water pump, the main hot water pump, the axial flow fan and the pressure sensor. And the controller is used for dynamically adjusting the operation states of the axial flow fan and the water pump by combining the pressure relief curve at the front end and the dead steam pressure so as to achieve the optimal heat exchange efficiency. The scheme of the invention can adapt to different scenes, and has higher environmental protection performance and economic value.

Description

Technical Field

[0001] The invention belongs to the technical field of energy-saving and environmental protection equipment, and in particular relates to a water circulation system for realizing exhaust steam waste heat recovery. Background Art

[0002] In the production process of building materials such as aerated concrete blocks, concrete pipe piles, lime sand bricks, fly ash bricks, microporous calcium silicate boards, new lightweight wall materials, thermal insulation asbestos boards, high-strength gypsum, calcium silicate boards, etc., the processed prefabricated products need to be autoclaved and cured. During the autoclave curing stage, the factory's equipment often generates a large amount of exhaust steam. On the one hand, the temperature of the exhaust steam is relatively high. If it is discharged directly, it may damage the natural environment and cause a large amount of heat loss. On the other hand, the exhaust steam discharged by the building materials factory often contains some white smoke and unpleasant odors, which will pollute the atmosphere if discharged directly. Therefore, how to effectively absorb and treat the exhaust steam has become a problem that must be solved by various building materials manufacturers.

[0003] In order to solve the problem of exhaust steam emission, existing large-scale building materials manufacturing plants are usually equipped with professional exhaust steam recovery equipment. These exhaust steam recovery equipment absorbs the heat in the exhaust steam by condensation, and converts the exhaust steam into condensed water before discharging it. However, for some small and medium-sized building materials factories, the exhaust steam emission conditions in the hot plant area are not stable. In certain periods of time, the exhaust steam discharged from the front end is even discontinuous, which makes it difficult to recover and reuse the waste heat of the exhaust steam. The inability to stably supply exhaust steam will cause traditional exhaust steam recovery equipment to be unable to operate stably for a long time, which will not only affect the normal operation of the equipment, but may even cause serious production safety accidents.

[0004] In addition, the autoclave curing process in building materials production generates huge energy losses, as well as a large amount of water resource losses in the entire process including recycling, which is also a major pain point for building materials manufacturers. Summary of the invention

[0005] In order to solve the problem that the existing exhaust steam recovery equipment is difficult to handle industrial exhaust steam with unstable front-end emission and easily causes waste of water resources; the present invention provides a water circulation system for realizing exhaust steam waste heat recovery.

[0006] The present invention is implemented by the following technical solutions:

[0007] A water circulation system for recovering waste heat from exhaust steam is used to recover the heat of the waste steam that is unstable during production and to realize the recycling of production water. In the present invention, the water circulation system for recovering waste heat from exhaust steam includes: a buffer water tank, a hot water storage tank, an exhaust steam recovery device, a main cold water pump, a heat exchanger, a main hot water pump, a pressure sensor, and a controller.

[0008] Among them, the buffer water tank is used to store circulating water in a low-temperature state; the circulating water in a low-temperature state is used as a refrigerant.

[0009] The hot water storage tank uses a tank with an insulation layer and is used to store circulating water in a high-temperature state; the circulating water in a high-temperature state serves as a heat medium.

[0010] The exhaust steam recovery device includes a condenser, a hot well and an axial flow fan. The condenser includes a refrigerant channel and an exhaust steam channel. One end of the refrigerant channel is connected to the buffer water tank through a pipeline, and the other end is connected to the hot water storage tank through a pipeline. One end of the exhaust steam channel is connected to the exhaust steam exhaust pipeline, and the other end is connected to the axial flow fan. The axial flow fan serves as a power source to drive the exhaust steam in the exhaust steam exhaust pipeline to flow through the condenser. The hot well is used to collect condensed water after the exhaust steam is condensed by the condenser.

[0011] The main cold water pump is installed at the drain outlet of the buffer water tank; the main cold water pump is used to pump the refrigerant in the buffer water tank along the pipeline passing through the condenser to the hot water storage tank.

[0012] The heat exchanger includes a hot water channel and a cold water channel; one end of the hot water channel is connected to the hot water storage tank through a pipe, and the other end is connected to the buffer water tank through a pipe. The heat medium in the hot water storage tank flows through the hot water channel and is used to heat the production water flowing through the cold water channel.

[0013] The main hot water pump is installed at the drain outlet of the hot water storage tank; the main hot water pump is used to pump the heat medium in the hot water storage tank to the circulating water tank along the pipeline passing through the heat exchanger.

[0014] The pressure sensor is used to detect the exhaust steam pressure in the exhaust steam exhaust pipeline.

[0015] The controller is electrically connected to the main cold water pump, the main hot water pump, the axial flow fan and the pressure sensor. The controller is used to adjust the exhaust power of the axial flow fan and the water pump flow of the main cold water pump and the main hot water pump according to the predicted control strategy in combination with the pressure relief curve of the steam generating equipment that generates the exhaust steam and the exhaust steam pressure detected by the pressure sensor, so that the condenser and the heat exchanger can achieve the best heat exchange efficiency.

[0016] As a further improvement of the present invention, the buffer water tank includes a water inlet, which is connected to the water supply pipeline through a water inlet valve.

[0017] A liquid level gauge is provided in the buffer water tank and the heat storage tank respectively; both liquid level gauges are electrically connected to the controller; the controller calculates the real-time circulating water surplus in the system according to the detection results of the two liquid level gauges and makes a decision: when the circulating water surplus is lower than the preset lower limit threshold, the water inlet valve is opened to replenish water into the buffer water tank; when the circulating water surplus is higher than the preset upper limit threshold, the water inlet valve is closed.

[0018] As a further improvement of the present invention, the heat storage tank also includes a water supply port for supplying hot water to the outside; the water supply port is connected to the heating pipe through a first stop valve; the first stop valve is electrically connected to the controller; the controller is used to manage the on-off of the hot water supply channel in the heat storage tank through the first stop valve.

[0019] As a further improvement of the present invention, the water circulation system for realizing exhaust steam waste heat recovery also includes a standby cold water pump and a standby hot water pump. The water inlet ends of the standby cold water pump and the main cold water pump are respectively connected to the drain port of the buffer water tank through a three-way pipe. The water inlet ends of the standby hot water pump and the main hot water pump are respectively connected to the drain port of the hot water storage tank through a three-way pipe.

[0020] As a further improvement of the present invention, an electric gate valve is respectively provided at the water inlet end of the main cold water pump, the main hot water pump, the standby cold water pump and the standby hot water pump; each electric gate valve is electrically connected to the controller; the controller is used to manage the opening and closing of the drainage channel in the buffer water tank or the hot water storage tank through each electric gate valve.

[0021] and / or

[0022] A second stop valve is respectively provided at the water outlet of the main cold water pump, the main hot water pump, the standby cold water pump and the standby hot water pump; each second stop valve is electrically connected to the controller; the controller is used to manage the on-off of the refrigerant channel inlet in the condenser and the on-off of the hot water channel inlet in the heat exchanger through each second stop valve.

[0023] As a further improvement of the present invention, the exhaust steam discharge pipeline has two discharge ports, one of which flows through the condenser and is connected to the axial flow fan, and the other is directly connected to the axial flow fan.

[0024] and / or

[0025] An electric ball valve is provided at each of the two exhaust ports; the electric ball valve is electrically connected to the controller and is used to manage the on-off of the exhaust steam exhaust port in the exhaust steam exhaust pipeline.

[0026] As a further improvement of the present invention, the axial flow fan has two air inlets, one of which is connected to the exhaust steam exhaust pipe through the exhaust steam channel of the condenser, and the other is directly connected to the exhaust steam exhaust pipe through a pipeline.

[0027] and / or

[0028] A butterfly valve is provided in each of the pipes connecting the two air inlets of the axial flow fan; the two butterfly valves are electrically connected to the controller, and the controller realizes flow distribution of the exhaust steam discharged from the front end by adjusting the opening of the two butterfly valves.

[0029] As a further improvement of the present invention, the hot well includes a discharge port, which is connected to the condensate pool through a condensate discharge pipe. A drain valve is provided at the discharge port, which is electrically connected to the controller, and the controller manages the on-off of the discharge port in the hot well through the drain valve.

[0030] A liquid level meter is provided in the hot well, and the liquid level meter is electrically connected to the controller. The controller obtains the water level in the hot well through the liquid level meter, and makes the water level in the hot well at the target height by opening and closing the drain valve.

[0031] As a further improvement of the present invention, the water circulation system for realizing exhaust steam waste heat recovery also includes a rack, and the exhaust steam recovery device, main cold water pump, heat exchanger, main hot water pump, controller, and various pipes for connecting the buffer water tank and the hot water storage tank are all installed on the rack to realize integrated assembly.

[0032] As a further improvement of the present invention, the condenser is any one of a shell and tube condenser, a sleeve condenser, a shell-and-coil condenser, a spiral plate condenser, an immersion condenser or a spray condenser;

[0033] The heat exchanger adopts any one of a shell and tube heat exchanger, a coil heat exchanger, a sleeve heat exchanger, a fin tube heat exchanger, a flat plate heat exchanger and a heat pipe heat exchanger.

[0034] As a further improvement of the present invention, a straight overflow pipe is arranged near the safe water level of the hot water storage tank and the buffer water tank, and a third stop valve is installed in the overflow pipe.

[0035] and / or

[0036] The outlet of the middle refrigerant channel of the condenser is connected to the buffer water tank and the hot water storage tank respectively through a three-way pipe, and a fourth stop valve is respectively arranged on the pipes of the two flow directions.

[0037] The technical solution provided by the present invention has the following beneficial effects:

[0038] This embodiment provides a water circulation system for recovering waste heat from exhaust steam. The system can recover and utilize waste heat from exhaust steam while avoiding the pollution of water resources in different processes and reducing the waste of production water. Therefore, it has excellent environmental protection significance. The system equipped by the present invention absorbs and stores waste heat from exhaust steam, which can be converted into stable and continuous heat energy output for use in other continuous heat-using processes on the production line, reducing the energy consumption of other processes, effectively solving the existing industry pain points, and greatly improving economic benefits.

[0039] The technical solution of the present invention can be applied to projects without external power and discontinuous steam heat recovery such as building materials factories. In the early design stage, the equipment systematically considers the pressure relief curve of the exhaust process of industrial steam heat equipment, and the exhaust flow rate obtained after theoretical calculation based on the pressure relief curve is used as the design parameter of the equipment. Considering the characteristics of low exhaust steam flow rate, low pressure and difficult exhaust at the end of exhaust, the steam extraction system of the condensation process is optimized and designed, which recovers the waste heat of exhaust steam without affecting the pressure relief curve of the steam generating equipment.

[0040] The water circulation system for realizing exhaust steam waste heat recovery provided by the present invention adopts a multiple redundant design and has higher safety. The controller can flexibly adjust the operating status of each valve and electronic control device in the system according to the exhaust steam production at the front end and the heat demand at the back end, so that the operating status of the system is adapted to the real-time working conditions, thereby improving the efficiency of the system operation. In addition, the system of the present invention also adopts an integrated design, which can realize integrated deployment, and then adjust the equipment model according to different needs, and expand or increase the internal actuator. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0042] Figure 1 This is a schematic diagram of the overall structure of the water circulation system for realizing exhaust steam waste heat recovery provided in Example 1 of the present invention.

[0043] Figure 2 This is a schematic diagram of a water circulation system for realizing exhaust steam waste heat recovery in Example 1 of the present invention.

[0044] Figure 3 This is a schematic diagram of the structure of the core components of the water circulation system of Example 1 of the present invention, except for the two water tanks.

[0045] Figure 4 This is a location distribution diagram of various valves in the water circulation system of Example 1 of the present invention.

[0046] Figure 5 This is a schematic structural diagram from a top perspective of a water circulation system for realizing exhaust steam waste heat recovery in Example 1 of the present invention.

[0047] Figure 6 This is a schematic structural diagram of the axial flow fan from one side according to Example 1 of the present invention.

[0048] Figure 7 Schematic diagram of the core structure installed on the rack.

[0049] Figure 8Schematic diagram of the overall structure of the water circulation system including the rack in Example 2 of the present invention.

[0050] The markings in the figure are:

[0051] 1. Buffer water tank; 2. Heat storage tank; 3. Exhaust steam recovery device; 4. Main cold water pump; 5. Main hot water pump; 6. Controller; 7. Standby cold water pump; 8. Standby hot water pump; 9. Heat exchanger; 31. Condenser; 32. Hot well; 33. Axial flow fan; 92. Electric gate valve; 93. Second stop valve; 94. Electric ball valve; 95. Butterfly valve; 96. Drain valve; 97. Overflow pipe; 98. Third stop valve; 99. Fourth stop valve. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0053] Example 1

[0054] This embodiment provides a water circulation system for realizing waste heat recovery of exhaust steam, which is used to recover the heat of the exhaust steam that is unstable during production and realize the recycling of production water. Figure 1 As shown, the water circulation system for realizing exhaust steam waste heat recovery provided in the present embodiment includes: a buffer water tank 1, a heat storage tank 2, an exhaust steam recovery device 3, a main cold water pump 4, a heat exchanger 9, a main hot water pump 5, a pressure sensor, and a controller 6. In the water circulation system provided in the present embodiment, circulating water is used as a medium for absorbing, storing and releasing heat. The circulating water in a low temperature state is used to absorb the heat in the exhaust steam to realize the condensation of the exhaust steam. After absorbing the heat, the circulating water becomes a high temperature state, and the circulating water in a high temperature state is used to heat the production water. After heat exchange with the production water, the circulating water becomes a low temperature state again and can be reused to absorb the heat in the exhaust steam.

[0055] The basic principle diagram of the water circulation system for realizing exhaust steam waste heat recovery provided in this embodiment is as follows Figure 2 As shown in the figure, it can be seen that the circulating water circulates between the buffer water tank 1, the exhaust steam recovery device 3, the hot water storage tank 2 and the heat exchanger 9 and exchanges heat with the production water and the exhaust steam. The circulating water is located in the internal circulation of the system, and the circulating water in the internal circulation will not exchange substances with the production water in the external circulation. Therefore, while absorbing and utilizing the waste heat in the exhaust steam, the water circulation system can also effectively avoid water pollution and water resource loss problems; it has better energy-saving and environmental protection performance.

[0056] Specifically, the buffer water tank 1 in this embodiment is used to store circulating water in a low temperature state, and the circulating water in a low temperature state is used as a "refrigerant". The refrigerant is used to absorb the heat in the exhaust steam flowing through the condenser 31 of the exhaust steam recovery device 3. In actual application, the temperature of the circulating water in the buffer water tank 1 is usually below 60°C, and the thermal cycle process usually requires the refrigerant to maintain a low temperature as much as possible. Therefore, the buffer water tank 1 has no requirements for the thermal insulation performance of the container. In addition, the atmosphere can exchange heat with the circulating water in the buffer water tank 1, so that the temperature of the circulating water therein is further reduced, and its heat exchange effect as a refrigerant is improved. The buffer water tank 1 in this embodiment can use a metal water storage container with good heat dissipation performance. The volume of the buffer water tank 1 is adaptively designed according to the system's requirements for the heat storage performance of the circulating water in the thermal cycle. When the exhaust steam generation in the production process is relatively high, the heat storage requirements for the circulating water are high. At this time, a buffer water tank 1 with a larger volume should be configured. On the contrary, if the exhaust steam generation in the production process is relatively low, a buffer water tank 1 with a relatively small volume can be configured.

[0057] In the scheme of this embodiment, the hot water storage tank 2 is used to store circulating water in a high temperature state; the circulating water in a high temperature state is used as a "heat medium". The heat medium is used to exchange heat with the production water in the heat exchanger 9, thereby realizing preheating of the production water. For example, the heat medium can heat the boiler water for steam production to a higher temperature to reduce the energy consumption of the steam production process; or the heat medium is input into the hot water heating pipeline to continuously and stably provide heat for other heat use scenarios. In actual application, the temperature of the circulating water in the buffer water tank 1 is usually above 80°C, and the heat cycle process usually requires the heat medium to be kept at a relatively high temperature. Therefore, the buffer water tank 1 requires the container to have a relatively good thermal insulation performance to inhibit the heat loss caused by the heat exchange between the circulating water and the atmosphere. Based on this goal, the hot water storage tank 2 in the water circulation system provided in this embodiment should adopt a box with an insulation layer. In addition, in the heat cycle process of this embodiment, in order to ensure the stable operation of the system, the heat absorption and release process in the circulating water should be balanced. Therefore, the volume of the hot water storage tank 2 and the buffer water tank 1 is usually consistent, and the volume of the hot water storage tank 2 can also be appropriately expanded when necessary.

[0058] In this embodiment, Figure 3As shown, the exhaust steam recovery device 3 includes a condenser 31, a heat well 32 and an axial flow fan 33. Among them, the condenser 31 includes a refrigerant channel and an exhaust steam channel. The function of the exhaust steam recovery device 3 is to continuously pump the refrigerant in the buffer water tank 1 into the condenser 31 along the refrigerant channel, and continuously pump the exhaust steam discharged from the exhaust steam exhaust pipe into the exhaust steam channel of the condenser 31 through the axial flow fan 33. In the condenser 31, the exhaust steam and the refrigerant flow in opposite directions along the two channels, thereby achieving sufficient heat exchange. In this process, the refrigerant absorbs heat in the condenser 31 and heats up, and then is converted into a heat medium discharged into the hot water storage tank 2. The exhaust steam releases heat in the condenser 31 and is converted into condensed water. The hot well 32 is used to collect the condensed water after the exhaust steam is condensed by the condenser 31.

[0059] Specifically, one end of the refrigerant channel in the condenser 31 of this embodiment is connected to the buffer water tank 1 through a pipeline, and the other end is connected to the hot water storage tank 2 through a pipeline. The refrigerant (low-temperature circulating water) discharged from the buffer water tank 1 is converted into a heat medium (high-temperature circulating water) after passing through the condenser 31 and is collected by the hot water storage tank 2. The main cold water pump 4 is installed at the drain outlet of the buffer water tank 1; the main cold water pump 4 is used to pump the refrigerant in the buffer water tank 1 to the hot water storage tank 2 along the pipeline passing through the condenser 31. That is, the main cold water pump 4 serves as a power source to drive the circulating water in the refrigerant channel in the condenser 31 to flow.

[0060] One end of the exhaust steam channel in the condenser 31 is connected to the exhaust steam exhaust pipe, and the other end is connected to the axial flow fan 33. The axial flow fan 33 serves as a power source for driving the exhaust steam in the exhaust steam exhaust pipe to flow through the condenser 31. In this embodiment, the operating power of the axial flow fan 33 can be adjusted. When the pressure of the exhaust steam output by the exhaust steam exhaust pipe at the front end changes, the operating power of the axial flow fan 33 can be appropriately adjusted to change the flow rate of the exhaust steam flowing through the condenser 31, thereby ensuring that the efficiency of the heat exchange process between the refrigerant and the exhaust steam in the condenser 31 is maximized.

[0061] The function of the condenser 31 of this embodiment is to realize heat exchange between high-temperature gas phase (referring to exhaust steam) material and low-temperature liquid phase (referring to refrigerant) material, and then use the low-temperature liquid phase material to condense the high-temperature gas phase material, and through the heat exchange between the two, the gas phase material undergoes a phase change from gas phase to liquid phase. Therefore, in practical applications, the condenser 31 can adopt various condensers 31 that can realize heat exchange between gas and liquid, such as: shell and tube condenser 31, sleeve condenser 31, shell-coil condenser 31, spiral plate condenser 31, immersion condenser 31, spray condenser 31, and the like.

[0062] In the solution of this embodiment, the heat exchanger 9 includes a hot water channel and a cold water channel; one end of the hot water channel is connected to the hot water storage tank 2 through a pipeline, and the other end is connected to the buffer water tank 1 through a pipeline. Figure 4As shown, the main hot water pump 5 is installed at the drain outlet of the hot water storage tank 2; the main hot water pump 5 serves as a power source to drive the heat medium in the hot water storage tank 2 to flow along the hot water channel, and then pumps the heat medium in the hot water storage tank 2 to the circulating water tank along the pipeline passing through the heat exchanger 9. The production water to be heated enters from one end of the cold water channel and flows out from the other end.

[0063] In the heat exchanger 9 provided in this embodiment, the heat medium in a high temperature state and the production water in a low temperature state flow in opposite directions along their respective channels, and then complete the heat exchange in the heat exchanger 9. In this process, the circulating water in a high temperature state in the hot water storage tank 2 will release heat after passing through the heat exchanger 9, and then be converted into circulating water in a low temperature state and flow into the buffer water tank 1; the production water in a low temperature state will absorb heat after passing through the heat exchanger 9 and then be converted into production water in a high temperature state. The production water in a high temperature state can be supplied to the needs of the factory. The heat exchanger 9 of this embodiment is used to realize heat exchange between liquid phase substances and liquid phase substances, and then use the high temperature liquid phase substance (referring to the heat medium) to heat the low temperature liquid phase substance (referring to the production water). Therefore, in practical applications, the heat exchanger 9 can adopt various heat exchangers 9 that can realize heat exchange between liquid and liquid, such as any one of a shell and tube heat exchanger 9, a coil heat exchanger 9, a sleeve heat exchanger 9, a fin tube heat exchanger 9, a plate heat exchanger 9 and a heat pipe heat exchanger 9.

[0064] In the scheme of this embodiment, a pressure sensor is also provided at the exhaust steam discharge pipe at the front end, and the pressure sensor can monitor the exhaust steam pressure in the exhaust steam discharge pipe in real time. In addition, in this embodiment, the main cold water pump 4, the main hot water pump 5, the axial flow fan 33 and the pressure sensor are electrically connected to the controller 6. In this state, the controller 6 is used to adjust the exhaust power of the axial flow fan 33 and the pump flow of the main cold water pump 4 and the main hot water pump 5 according to the predicted control strategy in combination with the pressure relief curve of the steam generating equipment that generates the exhaust steam and the exhaust steam pressure detected by the pressure sensor, so that the condenser 31 and the heat exchanger 9 can achieve the best heat exchange efficiency.

[0065] The controller 6 of this embodiment is preset with a mapping relationship between the exhaust steam production, the exhaust steam pressure, the power of the axial flow fan 33, and the flow rate of the main cooling water pump 4. This achieves the purpose of collaboratively adjusting the operating states of the rear axial flow fan 33 and the main cooling water pump 4 according to the dynamic changes of the exhaust steam production and the exhaust steam pressure at the front end.

[0066] Specifically, when the exhaust steam output at the front end is high and the pressure in the exhaust steam discharge pipe is at a high level, the axial flow fan 33 will operate at a relatively low power. At this time, the flow rate through the exhaust steam channel in the condenser 31 will still remain at a relatively high state. In this state, the controller 6 will appropriately increase the water pump flow rate of the main cold water pump 4, thereby increasing the flow rate of the refrigerant in the refrigerant channel in the condenser 31, and then adapting to the high flow rate of the exhaust steam in the exhaust steam channel; to ensure that the refrigerant can convert all the exhaust steam into condensed water.

[0067] On the contrary, when the exhaust steam output at the front end is low and the pressure in the exhaust steam discharge pipe is at a low level, the axial flow fan 33 will operate at a relatively high power. At this time, the flow rate in the exhaust steam channel in the condenser 31 will be appropriately increased under the suction effect of the axial flow fan 33. In this state, the controller 6 will appropriately reduce the water pump flow rate of the main cold water pump 4, thereby reducing the flow rate of the refrigerant in the refrigerant channel in the condenser 31 and matching the low flow rate of the exhaust steam in the exhaust steam channel; to ensure that the refrigerant can convert all the exhaust steam into condensed water and avoid waste caused by excessive refrigerant flow.

[0068] In the water circulation system for realizing waste heat recovery of exhaust steam provided in the present embodiment, the internal circulation with circulating water as the medium includes a heat absorption process from the buffer water tank 1 through the condenser 31 to the hot water storage tank 2, and a heat release process from the hot water storage tank 2 through the heat exchanger 9 to the circulating water tank. The former is used to absorb waste heat in the exhaust steam, and the latter is used to heat production water. In the water circulation system of the present embodiment. The heat absorption process and the heat circulation process can be carried out simultaneously, or they can be completed at different times according to the actual production scenarios of the enterprise. In order to meet the differentiated needs of different application scenarios such as factories for the heat absorption process and the heat release process, the buffer water tank 1 and the hot water storage tank 2 of the present embodiment have a large capacity. Therefore, the two can temporarily store the low-temperature circulating water and high-temperature circulating water generated during the circulation process.

[0069] Taking a building materials factory as an example, when it is necessary to continuously produce building materials products in large quantities, the heat absorption process and the heat release process can be implemented simultaneously. The former is used to recover the waste heat of the exhaust steam in the production process, and the latter is used to preheat the production water in the evaporation production process. Thereby maintaining the heat balance and material balance of the circulating water in the system. When only a small batch production task needs to be arranged, only part of the equipment in the heat absorption process can be started to recover the waste heat of the exhaust steam in the production process. A large amount of high-temperature circulating water accumulated in this process is temporarily stored in the hot water storage tank 2 for later use. On the contrary, if the enterprise does not arrange production tasks and there is no exhaust steam generated at the front end, the heat absorption process can be turned off. During this process, the high-temperature circulating water cached in the hot water storage tank 2 can still continue to output heat to the outside to meet the factory's heat demand.

[0070] It should be additionally explained that: in the water circulation system for realizing exhaust steam waste heat recovery provided in the present embodiment, the circulating water can not only be used as a refrigerant and a heat medium to circulate in the closed internal environment formed by the buffer water tank 1, the exhaust steam recovery device 3, the hot water storage tank 2 and the heat exchanger 9, but also through heat exchange with external substances (referring to exhaust steam and production water), the waste heat in the exhaust steam can be absorbed, stored and reused. The user can also be allowed to directly use the circulating water in a high-temperature state stored in the hot water storage tank 2 to meet the demand for hot water in actual application scenarios. In the present embodiment, the circulating water in a high-temperature state in the hot water storage tank 2 only flows between the buffer water tank 1, the exhaust steam recovery device 3, the hot water storage tank 2 and the heat exchanger 9, and does not participate in other production processes, so the water quality can be guaranteed to be clean and pollution-free.

[0071] In order to realize the function of directly providing high-temperature circulating water to the outside, the heat storage tank 2 of this embodiment also includes a water supply port for supplying hot water to the outside; the water supply port is connected to the heating pipeline through a first stop valve. The first stop valve is electrically connected to the controller 6, and the controller 6 is used to manage the on-off of the hot water supply channel in the heat storage tank 2 through the first stop valve. Correspondingly, in order to ensure that the residual amount of circulating water inside the buffer water tank 1, the exhaust steam recovery device 3, the heat storage tank 2 and the heat exchanger 9 remains stable, the present embodiment also provides a water inlet in the buffer water tank 1, and the water inlet is connected to the water supply pipeline through a water inlet valve. A liquid level gauge is respectively provided in the buffer water tank 1 and the heat storage tank 2; both liquid level gauges are electrically connected to the controller 6; the controller 6 calculates the real-time circulating water surplus in the system based on the detection results of the two liquid level gauges to realize dynamic water replenishment of the system. The decision-making process of dynamic water replenishment is as follows:

[0072] (1) When the circulating water surplus is lower than the preset lower limit threshold, the water inlet valve is opened to replenish water into the buffer water tank 1.

[0073] (2) When the circulating water surplus is higher than the preset upper limit threshold, close the water inlet valve.

[0074] In the more optimized solution of this embodiment, Figure 5 As shown, the water circulation system for realizing exhaust steam waste heat recovery also includes a standby cold water pump 7 and a standby hot water pump 8. The water inlet ends of the standby cold water pump 7 and the main cold water pump 4 are respectively connected to the drain port of the buffer water tank 1 through a three-way pipe. The water inlet ends of the standby hot water pump 8 and the main hot water pump 5 are respectively connected to the drain port of the hot water storage tank 2 through a three-way pipe.

[0075] Combined with the foregoing, it can be seen that the main cold water pump 4 and the main hot water pump 5 are the power sources that drive the circulating water of different temperature states in the buffer water tank 1 and the hot water storage tank 2 to circulate between the condenser 31 and the heat exchanger 9. If any one of them is damaged, the heat absorption process or heat release process in the system will not be realized. Therefore, this implementation adds a backup cold water pump 7 and a backup hot water pump 8 as system redundancy, and the main cold water pump 4, the main hot water pump 5 and the backup cold water pump 7, the backup hot water pump 8 are backed up by each other, thereby ensuring that after one of the water pumps is damaged, the other water pump can be started in time and seamlessly switched to ensure the safe and stable operation of the system.

[0076] like Figure 4 As shown, in the scheme of this embodiment, an electric gate valve 92 can be respectively provided at the water inlet end of the main cold water pump 4, the main hot water pump 5, the standby cold water pump 7 and the standby hot water pump 8. Each electric gate valve 92 is electrically connected to the controller 6; the controller 6 is used to manage the on-off of the drainage channel in the buffer water tank 1 or the hot water storage tank 2 through each electric gate valve 92. In addition, a second stop valve 93 can be respectively provided at the water outlet end of the main cold water pump 4, the main hot water pump 5, the standby cold water pump 7 and the standby hot water pump 8. Each second stop valve 93 is electrically connected to the controller 6; the controller 6 is used to manage the on-off of the refrigerant channel inlet in the condenser 31 and the on-off of the hot water channel inlet in the heat exchanger 9 through each second stop valve 93.

[0077] The function of the electric gate valve 92 installed on the water inlet side of each water pump is to prevent the circulating water in the buffer water tank 1 or the hot water storage tank 2 from leaking. Each electric gate valve 92 is opened only when the corresponding water pump starts working. When the corresponding water pump is in a standby state, the electric gate valve 92 is closed. The function of the second stop valve 93 installed on the water outlet side of each water pump is to prevent the circulating water in the buffer water tank 1 or the hot water storage tank 2 from flowing back and flowing back into the condenser 31 or the heat exchanger 9. Each electric gate valve 92 is opened only when the corresponding water pump starts working. When the corresponding water pump is in a standby state, the second stop valve 93 is closed.

[0078] like Figure 4 and Figure 5As shown, in a more optimized solution of this embodiment, the exhaust steam exhaust pipeline has two exhaust ports, the exhaust steam discharged from one exhaust port flows through the exhaust steam channel in the condenser 31 and reaches the axial flow fan 33, and the exhaust steam discharged from the other exhaust port does not pass through the exhaust steam channel in the condenser 31, and directly reaches the axial flow fan 33. Further, both exhaust ports are provided with an electric ball valve 94. The electric ball valve 94 is electrically connected to the controller 6, and the controller 6 is used to manage the on-off of the exhaust steam exhaust port in the exhaust steam exhaust pipeline through the electric ball valve 94. Specifically, under the control strategy of the controller 6 of this embodiment, the electric ball valve 94 is opened when the front end generates exhaust steam output, and is closed when the front end does not generate exhaust steam or the flow rate of the generated exhaust steam is too low.

[0079] Correspondingly, Figure 6 As shown, the axial flow fan 33 used in this embodiment also has two air inlets, one of which is connected to the exhaust steam exhaust pipe through the exhaust steam channel of the condenser 31, and the other air inlet is directly connected to the exhaust steam exhaust pipe through a pipe. Further, a butterfly valve 95 is provided in each of the pipes connecting the two air inlets of the axial flow fan 33; the two butterfly valves 95 are electrically connected to the controller 6, and the controller 6 realizes flow distribution of the exhaust steam discharged from the front end by adjusting the opening of the two butterfly valves 95.

[0080] Specifically, the butterfly valve 95 provided at the air inlet of the axial flow fan 33 in this embodiment has two functions. One is that after the flow rate of the exhaust steam generated at the front end changes, the butterfly valve 95 is used in conjunction with the electric ball valve 94 to prevent the reflux of condensed water in the respective gas channels. The other is that during the condensation process of the condenser 31, the exhaust steam discharged from the front end is distributed by cooperatively controlling the two butterfly valves 95. The flow distribution strategy is as follows:

[0081] When the controller 6 determines that the flow rate of the exhaust steam generated at the front end exceeds the maximum flow rate tolerance supported by the condenser 31 according to the pressure relief curve of the steam generating equipment and the exhaust steam pressure detected by the pressure sensor, the butterfly valve 95 of the channel flowing through the condenser 31 is opened to the maximum, and the opening of the butterfly valve 95 in the exhaust steam channel directly connected to the axial flow fan 33 is adaptively adjusted in combination with the flow rate of the exhaust steam actually generated, so that the excess exhaust steam is directly discharged through the axial flow fan 33. If the flow rate of the exhaust steam generated at the front end does not exceed the maximum flow rate tolerance supported by the condenser 31, the butterfly valve 95 in the exhaust steam channel directly connected to the axial flow fan 33 is closed, and the exhaust steam is allowed to flow through the condenser 31, so as to ensure that the waste heat in the exhaust steam is maximized.

[0082] The heat well 32 is a water collection well for collecting condensed water at the bottom of the condenser 31. The water level of the condensed water in the heat well 32 is extremely important for the safe and economical operation of the system. During the start-up and shutdown of each device in the heat absorption process, the water level of the condensed water will change, so the water level of the heat well 32 needs to be closely monitored and dynamically adjusted. Figure 4 As shown, the hot well 32 in the exhaust steam recovery device 3 of this embodiment includes a discharge port, which is connected to the condensate pool through a condensate discharge pipe. A drain valve 96 is provided at the discharge port, and the drain valve 96 is electrically connected to the controller 6. The controller 6 manages the opening and closing of the discharge port in the hot well 32 through the drain valve 96. In addition, a liquid level gauge is provided in the hot well 32, and the liquid level gauge is electrically connected to the controller 6. The controller 6 obtains the water level in the hot well 32 through the liquid level gauge, and makes the water level in the hot well 32 at the target height by opening and closing the drain valve 96.

[0083] In actual application, the water circulation system for realizing exhaust steam waste heat recovery provided in this embodiment needs to be specifically designed according to parameters such as actual exhaust steam production and heat demand in each application scenario, and is a type of customized equipment. The buffer water tank 1 and the heat storage tank 2 in the equipment are large in size and are non-critical equipment. The part including the exhaust steam recovery device 3, the main cold water pump 4, the heat exchanger 9, the main hot water pump 5, and the controller 6 is the core part of the entire system. Therefore, during the stages of product production and sales and transportation, the core part and the two containers can be sold and installed separately.

[0084] Specifically, in the more optimized solution of this embodiment, if Figure 7 and Figure 8 As shown, the water circulation system for realizing exhaust steam waste heat recovery also includes a rack, and the exhaust steam recovery device 3, the main cold water pump 4, the heat exchanger 9, the main hot water pump 5, the controller 6, and various pipes for connecting the buffer water tank 1 and the hot water storage tank 2 are all installed on the rack to realize integrated assembly. Under this condition, the customer only needs to purchase the corresponding model of integrated equipment according to his own needs, and then configure the corresponding hot water storage tank 2 and buffer water tank 1, and install the integrated core equipment with the two water tanks on site.

[0085] In addition, considering that the exhaust heat recovery and heat demand of some users are not synchronized, this may cause the circulating water in one of the hot water storage tank 2 and the buffer water tank 1 to continue to increase and exceed the preset safety capacity of the container. The present invention also adds redundant measures for circulating water surplus management between the hot water storage tank 2 and the buffer water tank 1, such as Figure 4 As shown, specifically including:

[0086] 1. A straight overflow pipe 97 is arranged near the safe water level of the hot water storage tank 2 and the buffer water tank 1 , and a third stop valve 98 is installed in the overflow pipe 97 .

[0087] The third stop valve 98 in this embodiment is electrically connected to the controller 6. The controller 6 can use the liquid level gauges in the hot water storage tank 2 and the buffer water tank 1 to monitor the real-time liquid level heights of the two, and then adjust the switch state of the third stop valve 98 according to the liquid level changes. Further, when the liquid level height of one of the containers exceeds the safe liquid level, the third stop valve 98 is opened so that part of the circulating water therein can naturally overflow into the other tank. When the liquid level heights of the two containers are both lower than the safe liquid level, the stop valves are closed to inhibit the circulating water of different temperatures in the two tanks from exchanging substances or heat due to evaporation or other reasons.

[0088] Second, the outlet of the middle refrigerant channel of the condenser 31 is connected to the buffer water tank 1 and the hot water storage tank 2 through a three-way pipe, and a fourth stop valve 99 is respectively provided on the pipes of the two flow directions.

[0089] The two fourth stop valves 99 in this embodiment are electrically connected to the controller 6. The controller 6 can use the liquid level gauges in the hot water storage tank 2 and the buffer water tank 1 to monitor the real-time liquid level heights of the two, and then adjust the switch states of the two fourth stop valves 99 according to the liquid level changes. Further, when the liquid level in the hot water storage tank 2 is lower than the upper limit of safety, the fourth stop valve 99 flowing to the side of the buffer water tank 1 is closed, and the fourth stop valve 99 flowing to the side of the hot water storage tank 2 is opened, so that the circulating water in the high temperature state generated in the condenser 31 all flows into the hot water storage tank 2. On the contrary, when the liquid level in the hot water storage tank 2 is higher than the upper limit of safety, the fourth stop valve 99 flowing to the side of the buffer water tank 1 is opened, and the fourth stop valve 99 flowing to the side of the hot water storage tank 2 is closed, so that the circulating water in the high temperature state generated in the condenser 31 no longer flows into the hot water storage tank 2.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A water circulation system for realizing exhaust steam waste heat recovery, characterized in that: It is used to recover the heat of the unstable exhaust steam discharged during production and realize the recycling of production water; the water circulation system for realizing the exhaust steam waste heat recovery includes: A buffer water tank is used to store circulating water at low temperature; the circulating water at low temperature is used as a refrigerant; The hot water storage tank adopts a tank with a thermal insulation layer and is used to store circulating water at a high temperature; the circulating water at a high temperature is used as a heat medium; An exhaust steam recovery device, comprising a condenser, a hot well and an axial flow fan; the condenser comprises a refrigerant channel and an exhaust steam channel; one end of the refrigerant channel is connected to a buffer water tank through a pipeline, and the other end is connected to the hot water storage tank through a pipeline; one end of the exhaust steam channel is connected to an exhaust steam exhaust pipeline, and the other end is connected to the axial flow fan; the axial flow fan serves as a power source to drive the exhaust steam in the exhaust steam exhaust pipeline to flow through the condenser; the hot well is used to collect condensed water after the exhaust steam is condensed by the condenser; A main cold water pump, which is installed at the drain outlet of the buffer water tank; the main cold water pump is used to pump the refrigerant in the buffer water tank to the hot water storage tank along the pipeline passing through the condenser; A heat exchanger, comprising a hot water channel and a cold water channel; one end of the hot water channel is connected to a hot water storage tank through a pipeline, and the other end is connected to a buffer water tank through a pipeline; the heat medium in the hot water storage tank flows through the hot water channel and is used to heat the production water flowing through the cold water channel; A main hot water pump, which is installed at the drain outlet of the hot water storage tank; the main hot water pump is used to pump the heat medium in the hot water storage tank into the circulating water tank along the pipeline passing through the heat exchanger; A pressure sensor, used for detecting the exhaust steam pressure in the exhaust steam discharge pipeline; A controller is electrically connected to the main cold water pump, the main hot water pump, the axial flow fan and the pressure sensor; the controller is used to adjust the exhaust power of the axial flow fan and the water pump flow rates of the main cold water pump and the main hot water pump according to the predicted control strategy in combination with the pressure relief curve of the steam generating equipment that generates exhaust steam and the exhaust steam pressure detected by the pressure sensor, so that the condenser and the heat exchanger achieve optimal heat exchange efficiency.

2. The water circulation system for realizing exhaust steam waste heat recovery according to claim 1, characterized in that: The buffer water tank includes a water inlet, which is connected to the water supply pipeline through a water inlet valve; A liquid level gauge is respectively provided in the buffer water tank and the heat storage tank; both liquid level gauges are electrically connected to the controller; the controller calculates the real-time circulating water surplus in the system according to the detection results of the two liquid level gauges, and makes a decision: when the circulating water surplus is lower than the preset lower limit threshold, the water inlet valve is opened to replenish water into the buffer water tank; when the circulating water surplus is higher than the preset upper limit threshold, the water inlet valve is closed.

3. The water circulation system for realizing exhaust steam waste heat recovery according to claim 1, characterized in that: The heat storage tank also includes a water supply port for supplying hot water to the outside; the water supply port is connected to the heating pipeline through a first stop valve; the first stop valve is electrically connected to the controller; the controller is used to manage the on-off of the hot water supply channel in the heat storage tank through the first stop valve.

4. The water circulation system for realizing exhaust steam waste heat recovery according to claim 1, characterized in that: It also includes a backup cold water pump and a backup hot water pump; the water inlet ends of the backup cold water pump and the main cold water pump are connected to the drain outlet of the buffer water tank through a three-way pipe respectively; the water inlet ends of the backup hot water pump and the main hot water pump are connected to the drain outlet of the hot water storage tank through a three-way pipe respectively.

5. The water circulation system for realizing exhaust steam waste heat recovery according to claim 3, characterized in that: An electric gate valve is respectively provided at the water inlet end of the main cold water pump, the main hot water pump, the standby cold water pump and the standby hot water pump; each electric gate valve is electrically connected to the controller; the controller is used to manage the on-off of the drainage channel in the buffer water tank or the hot water storage tank through each electric gate valve; and / or A second stop valve is respectively provided at the water outlet end of the main cold water pump, the main hot water pump, the standby cold water pump and the standby hot water pump; each second stop valve is electrically connected to the controller; the controller is used to manage the on-off of the refrigerant channel inlet in the condenser and the on-off of the hot water channel inlet in the heat exchanger through each second stop valve.

6. The water circulation system for realizing exhaust steam waste heat recovery according to claim 1, characterized in that: The exhaust steam discharge pipeline has two discharge ports, one of which flows through the condenser and is connected to the axial flow fan, and the other is directly connected to the axial flow fan; and / or An electric ball valve is provided at each of the two exhaust ports; the electric ball valve is electrically connected to the controller and is used to manage the on-off of the exhaust steam exhaust port in the exhaust steam exhaust pipeline.

7. The water circulation system for realizing exhaust steam waste heat recovery according to claim 6, characterized in that: The axial flow fan has two air inlets, one of which is connected to the exhaust steam exhaust pipeline through the exhaust steam channel of the condenser; the other air inlet is directly connected to the exhaust steam exhaust pipeline through a pipeline; and / or A butterfly valve is provided in each of the pipes connecting the two air inlets of the axial flow fan; the two butterfly valves are electrically connected to the controller, and the controller realizes flow distribution of the exhaust steam discharged from the front end by adjusting the opening of the two butterfly valves.

8. The water circulation system for realizing exhaust steam waste heat recovery according to claim 7, characterized in that: The hot well comprises a discharge port, which is connected to a condensate pool via a condensate discharge pipe; a drain valve is provided at the discharge port, which is electrically connected to a controller, and the controller manages the on / off of the discharge port in the hot well via the drain valve; A liquid level meter is provided in the hot well, and the liquid level meter is electrically connected to the controller; the controller obtains the water level in the hot well through the liquid level meter, and makes the water level in the hot well reach the target height by opening and closing the drain valve.

9. The water circulation system for realizing exhaust steam waste heat recovery according to claim 1, characterized in that: It also includes a frame, on which the exhaust steam recovery device, the main cold water pump, the heat exchanger, the main hot water pump, the controller, and various pipes for connecting the buffer water tank and the hot water storage tank are installed to achieve integrated assembly; and / or The condenser is any one of a shell and tube condenser, a sleeve condenser, a shell-coil condenser, a spiral plate condenser, an immersed condenser or a spray condenser; The heat exchanger is any one of a shell and tube heat exchanger, a coil heat exchanger, a sleeve heat exchanger, a fin tube heat exchanger, a flat plate heat exchanger and a heat pipe heat exchanger.

10. The water circulation system for realizing exhaust steam waste heat recovery according to claim 1, characterized in that: A straight overflow pipe is arranged near the safe water level of the hot water storage tank and the buffer water tank, and a third stop valve is installed in the overflow pipe; and / or The outlet of the middle refrigerant channel of the condenser is connected to the buffer water tank and the hot water storage tank respectively through a three-way pipe, and a fourth stop valve is respectively arranged on the pipes of the two flow directions.

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