Heat supply steam extraction residual pressure utilization system of cogeneration unit

Abstract

The invention provides a cogeneration unit heat supply steam extraction residual pressure utilization system which comprises a gas supply unit and a heating unit, and the gas supply unit comprises a boiler (4), a high-pressure cylinder (1) communicated with the boiler (4), an intermediate-pressure cylinder (2) communicated with the high-pressure cylinder (1) and a low-pressure cylinder (3) communicated with the intermediate-pressure cylinder (2); the residual pressure utilization unit comprises a vortex tube (10), and the vortex tube (10) is connected with the intermediate pressure cylinder (2) through a steam extraction pipe (31); the system further comprises a heat supply network heat exchanger, hot airflow at the hot end of the vortex tube (10) sequentially passes through a hot end tube (34), the heat supply network heat exchanger (7) and a backflow tube (35) to enter the condenser (6), the cold end of the vortex tube (10) is connected into the condenser (6) through a cold end tube (36), and a heat user (8) is connected into the heat supply network heat exchanger (7) through a heat exchange pipeline (37). Due to the fact that incoming flow of the steam extraction pipe is separated into lower-temperature cold air flow or a gas-liquid mixture and higher-temperature hot air flow through the vortex pipe, after the hot air flow enters the heat supply network heat exchanger, the temperature is higher than the traditional steam extraction temperature, and large heat transfer temperature difference means that the area of the heat exchanger can be greatly reduced on the premise that the heat exchange amount of the heat exchanger is not changed. The investment cost and occupied area of the heat exchanger are reduced; and meanwhile, a cold end outlet product directly enters the condenser, so that the cold load required by the condenser can be reduced, and the operation cost of the air cooler is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial energy conservation, in particular to a system for utilizing excess pressure of steam extraction for heating in a cogeneration unit. Background Art

[0002] Industrial residual pressure mainly refers to the unused pressure difference energy generated in the process of industrial production, etc., and usually refers to the pressure energy that can be recycled but has not been recycled. There are two main sources: 1) pressurized byproducts generated by the process; 2) some working media that require pressure to transport or meet the process pressure requirements have residual pressure after use. From the current status of my country's industry, residual pressure resources mainly exist in production processes such as blast furnace ironmaking, natural gas transportation, centralized heating pipelines, and reverse osmosis seawater desalination.

[0003] Combined heat and power (CHP) is an efficient way to use energy. It improves energy efficiency by generating electricity and useful heat in one process. Combined heat and power refers to the process of using heat engines or power plants to generate electricity and useful heat at the same time. This technology can significantly improve the thermal efficiency of fuels because it converts heat energy that is usually wasted in traditional power generation into useful heat energy for heating, industrial processes or other applications. In a cogeneration system, the heat energy generated by the combustion of fuel is first used to generate electricity, usually through a steam turbine or gas turbine. The waste heat after power generation is used for heating or cooling, realizing the cascade utilization of energy. Cogeneration systems can be "generation-first" or "generation-after". In a generation-first system, boiler steam is first used to generate electricity, and then the remaining heat is used for heating; while in a generation-after system, the steam is first used in industrial processes, and then the remaining heat is used for power generation.

[0004] In a cogeneration system, waste pressure utilization refers to the effective use of the pressure and temperature of the turbine exhaust steam to further improve the energy utilization rate of the system. This usually involves the use of waste heat recovery devices, such as waste heat boilers or heat pumps, to capture and utilize this waste heat. Waste pressure utilization is widely used in district heating, industrial processes, domestic hot water supply and other fields. For example, in cold areas in winter, waste heat can be used to provide heating for residential and commercial buildings; in the industrial field, waste heat can be used to heat raw materials or as part of the production process. In cogeneration units with extraction steam for heating, especially those converted for heating, the extraction steam parameters are often higher than the required values ​​for heating. On the one hand, it will affect the safe operation of the heat exchanger, and on the other hand, the steam work potential is not fully utilized, which reduces the efficiency of the heating field. In order to solve the problem of mismatch of extraction steam parameters for heating, the extraction steam can be throttled and cooled by a desuperheater and pressure reducer before going to the heat exchanger for heat exchange. This method is widely used due to its simple equipment structure and adjustment method. However, due to the use of a throttle valve, this method causes a large amount of heat energy loss and still cannot effectively utilize the work potential of the extraction steam. Summary of the invention

[0005] In view of the problems existing in the prior art, the purpose of the present invention is to provide a system for utilizing the residual pressure of steam extracted from a cogeneration unit for heating. Cogeneration refers to the process of using a heat engine or a power station to simultaneously generate electricity and useful heat. Therefore, a vortex tube can be used to efficiently recover and utilize the residual pressure energy generated during the operation of the cogeneration system. Compared with the traditional technology of using a throttle valve to reduce the pressure of the medium-pressure cylinder, this system uses a vortex tube to separate the steam extracted from the medium-pressure cylinder into hot and cold by utilizing the residual pressure, and separates and converts the energy in the high-speed airflow, which can be used for refrigeration, turbine power generation, or heating circulating water for hot users, significantly improving the comprehensive utilization rate of energy. Specifically, it includes an air supply unit and a heating unit.

[0006] The air supply unit includes a boiler, a high-pressure cylinder connected to the boiler, a medium-pressure cylinder connected to the high-pressure cylinder, and a low-pressure cylinder connected to the medium-pressure cylinder;

[0007] The heating unit includes a low-pressure heater connected to the low-pressure cylinder, a high-pressure heater connected to the high-pressure cylinder and the medium-pressure cylinder, a condenser connected to the low-pressure heater and the low-pressure cylinder, and a deaerator connected to the low-pressure heater and the high-pressure heater;

[0008] It also includes a surplus pressure utilization unit, which includes a vortex tube, which is connected to the medium-pressure cylinder through a steam extraction pipe; it also includes a heat network heat exchanger, and the hot air flow at the hot end of the vortex tube enters the condenser through the hot end pipe, the heat network heat exchanger and the return pipe in sequence, and the cold end of the vortex tube is connected to the condenser through the cold end pipe, and the heat user is connected to the heat network heat exchanger through the heat exchange pipeline.

[0009] The vortex tube comprises a vortex chamber, an inlet nozzle, a cold end, and a hot end all of which are connected to the vortex chamber, and further comprises:

[0010] The inlet transmission structure includes a cylinder and a circular ring structure driven to rotate by the cylinder; the inlet main pipeline is connected to the inlet nozzle, the inlet branch pipeline is communicated with the rodless cavity of the cylinder, and the piston rod of the cylinder is drivingly connected to the circular ring structure;

[0011] The control valve plate is located between the valve seat and the nozzle. The control valve plate can adjust the opening of the nozzle and control the flow rate of the incoming flow in the inlet nozzle under the drive of the circular ring structure; when the incoming flow pressure increases, part of the incoming flow gas enters the rodless chamber of the cylinder through the incoming flow branch pipeline, and the piston rod of the cylinder drives the circular ring structure to rotate and expand the flow area of ​​the inlet nozzle by rotating the control valve plate, automatically adapting to the higher inlet pressure and flow.

[0012] The high-pressure cylinder is a subcritical boiler with a steam temperature of about 540°C and a working pressure of 15.7-19.6Mpa.

[0013] The intermediate pressure cylinder is located after the high pressure cylinder. The exhaust steam pressure of the intermediate pressure cylinder is guaranteed to be above 0.4Mpa, the exhaust temperature is about 240℃, the extraction steam pressure of the intermediate pressure cylinder is 0.3Mpa-0.5Mpa, and the temperature is 134-152℃.

[0014] The beneficial effects described in this application are as follows:

[0015] 1) Compared with the traditional technology of using throttle valve to reduce the pressure of the intermediate pressure cylinder, the steam extracted from the pressure cylinder in this embodiment uses vortex tube to separate hot and cold by using residual pressure, thereby replacing the throttle valve of the prior art. The temperature of the hot end outlet increases to produce superheated steam, which increases the heat exchange capacity of the steam. The heat exchange can be saved by entering the heat network heater; the temperature of the cold end outlet decreases, and part of the gas can even condense. The gas-liquid mixture with reduced temperature enters the air cooler, which can also reduce part of the cold load of the air cooler; of course, the working fluid at the hot end outlet and the cold end outlet can also be mixed by the ejector before entering the air cooler. It can be seen that the residual pressure utilization system can improve the efficiency of heat exchange and condensation of the heat network by using vortex tubes in combination with the heat network heat exchanger and condenser, thereby reducing the size of the heat network heat exchanger and condenser. In the construction of the cogeneration unit, the investment cost of the heat network heat exchanger and the condenser heat exchanger can be greatly reduced, and the economic benefits can be significantly improved.

[0016] 2) When phase change occurs in the vortex tube, the condensed water can be discharged from the cold end of the vortex tube and then directly enter the condenser to mix with the fluid returned from the return pipe, thereby improving the condensation effect of the condenser. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of a system for utilizing the excess pressure of steam extracted from a combined heat and power unit for heating used in the present invention;

[0018] Figure 2 It is a three-dimensional schematic diagram of the inlet self-adjusting structure of the vortex tube in the present invention in response to the change of the incoming flow pressure.

[0019] Figure 3 for Figure 2 Side view.

[0020] Figure 4 for Figure 3 AA cross-section diagram.

[0021] Figure 5 Based on Figure 1 The proposed location diagram of the combined power and heating extraction steam surplus pressure utilization system.

[0022] Description of reference numerals:

[0023] 1. High-pressure cylinder; 2. Medium-pressure cylinder; 3. Low-pressure cylinder; 4. Boiler; 5. Deaerator; 6. Condenser; 7. Heat network heat exchanger; 8. Heat user; 9. Hot steam desuperheater; 10. Vortex tube; 11. Inlet nozzle; 12. First control ring; 13. Second control ring; 14. Adjustment block; 15. Control rod; 16. Control valve plate; 17. Nozzle; 18. Valve seat; 19. Drive block; 21. High-pressure heater; 22. Low-pressure heater; 31. Extraction pipe; 32. Cooling steam pipe; 33. Middle row pressure reducing branch; 34. Hot end pipe; 35. Reflux pipe; 36. Cold end pipe; 37. Heat exchange pipeline. DETAILED DESCRIPTION

[0024] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0025] Although the present invention is disclosed as above, the present invention is not limited thereto. In the description of this specification, the description of reference terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, so the scope of protection of the present invention should be based on the scope defined by the claims.

[0026] Air supply unit

[0027] Figure 1 It is a schematic diagram of the system for utilizing the excess pressure of steam extracted from a cogeneration unit for heating. The system converts steam energy into mechanical energy to drive the generator and provides steam for heating to heat user 8 at the same time.

[0028] Boiler 4 is a device for generating steam, and its function is to heat water into high-temperature and high-pressure steam. In the steam supply unit, the steam generated by the boiler first enters the high-pressure cylinder to do work, and then passes through the medium-pressure cylinder and the low-pressure cylinder in turn, and finally completes the cascade utilization of energy. For subcritical pressure boilers, the outlet steam pressure is 15.7-19.6MPa; for supercritical pressure boilers, the outlet steam pressure exceeds the critical pressure by 22.1MPa. The supercritical pressure used by power station boilers is mostly between 25-27MPa, and the temperature range of steam is determined according to the heating demand and equipment technical indicators. Generally speaking, the temperature of steam leaving the boiler is around 540℃.

[0029] The high-pressure cylinder 1 is the part of the steam turbine that bears the highest pressure and temperature, and is usually made of high-temperature and pressure-resistant materials. In the steam supply unit, the high-pressure cylinder receives high-temperature and high-pressure steam from the boiler, and drives the turbine to rotate by expansion work, thereby driving the generator to generate electricity. Its working pressure usually matches the boiler outlet pressure, so it can be considered to be the same as the boiler. For a subcritical boiler, the steam temperature of the high-pressure cylinder is around 540°C and the working pressure is 15.7-19.6Mpa.

[0030] The intermediate pressure cylinder 2 is located after the high pressure cylinder and receives the steam exhausted by the high pressure cylinder. Here, the pressure and temperature of the steam are reduced, but still maintain a high level. The design of the intermediate pressure cylinder takes into account the balance between cost and efficiency. Medium temperature resistant materials are usually used, and a single-layer cylinder structure may be adopted to reduce costs. The specific working pressure and temperature of the intermediate pressure cylinder may vary due to different cogeneration system unit designs and heating and power supply requirements. Generally, the working pressure of the intermediate pressure cylinder will be lower than that of the high pressure cylinder, and the temperature will also be reduced accordingly. In order to ensure the safety of the last stage blades of the intermediate pressure cylinder, the exhaust pressure is generally guaranteed to be above 0.4Mpa, and the exhaust temperature is generally around 240℃. Regarding the extraction of steam from the intermediate pressure cylinder, in order to ensure heating safety and heating needs, the extraction pressure is 0.3Mpa-0.5Mpa and the temperature is 134-152℃.

[0031] The low-pressure cylinder 3 is the last stop in the steam energy conversion process. Here, the temperature and pressure of the steam reach their lowest point. The low-pressure cylinder is characterized by its large size because it needs to handle a large amount of low-temperature steam. It is usually made of ordinary steel and may adopt a welded double-layer cylinder structure in structure to improve strength and durability. Its steam pressure is usually 0.1-0.5MPa, and this pressure range allows the steam to expand further and be converted into mechanical energy.

[0032] The deaerator 5 is used to remove dissolved oxygen and other gases in the boiler feed water to prevent oxygen from corroding the boiler equipment and pipelines and extend the service life of the equipment.

[0033] The main function of the condenser 6 is to condense the low-pressure steam discharged from the steam turbine into water for recycling. In the steam supply unit, the condenser also plays a role in maintaining the system vacuum and improving the thermal efficiency of the entire system.

[0034] The cooling steam pipe 33 is an important component for cooling the intermediate pressure cylinder 2. During the operation of the steam turbine, the intermediate pressure cylinder generates a large amount of heat. If it is not cooled in time, it may cause the equipment to overheat or even be damaged. The cooling steam pipe effectively reduces the temperature of the intermediate pressure cylinder by introducing cooling steam, ensuring the normal operation and long-term stability of the equipment.

[0035] The middle row pressure reducing branch 32 is an important pipeline connecting the medium pressure cylinder and the low pressure cylinder. Its main function is to reduce the pressure of the steam entering the low pressure cylinder to ensure that the steam can flow smoothly and convert energy in the low pressure cylinder. The existence of the middle row pressure reducing branch enables the steam turbine to flexibly adjust the flow and pressure of steam under different loads, thereby improving the adaptability and economy of the equipment.

[0036] The high-pressure heater 21 is a device that uses part of the steam turbine's exhaust to heat the feed water. It is a prior art device that consists of two major parts: a shell and a pipe system. A steam condensation section is set at the upper part of the shell cavity, a drain cooling section is set at the lower part, and a feed water inlet and a feed water outlet are set at the top of the inlet and outlet pipes. When superheated steam enters the shell from the inlet, it can heat the feed water in the upper main spiral tube. After the steam condenses into water, the condensed hot water can heat part of the feed water in the lower drain cooling spiral tube. The condensed water after use flows out of the body through the drain outlet.

[0037] The function of the low-pressure heater 22 is to utilize the steam that has done some work in the steam turbine, pump it into the heater to heat the feed water, increase the water temperature, reduce the amount of steam discharged from the steam turbine to the condenser, reduce energy loss, and improve the cycle efficiency of the thermal system. The structure is mostly vertical tube plate heater. The heating surface of the heater is generally composed of a straight tube bundle or a U-shaped tube bundle made of brass tubes or seamless steel tubes. The heated water enters one side of the separated water chamber from the upper water inlet pipe, and then flows into the U-shaped tube bundle. The U-shaped tube absorbs the heat of the heating steam in the steam space of the heater, and transfers it to the water flowing in the tube by the tube wall. The heated water flows out through the outlet water chamber of the heater.

[0038] A hot steam desuperheater 9 is a device used to reduce the temperature of steam. Its main function is to reduce the temperature of the steam to a suitable level before it enters the turbine to protect the turbine from overheating damage. The working principle of the hot steam desuperheater is based on the principle of heat exchange. When high-temperature steam flows through the desuperheater, it exchanges heat with the cooling medium (usually water or air) inside the desuperheater. In this way, the temperature of the steam is reduced, while the cooling medium absorbs the heat of the steam and heats up. The direct contact desuperheater uses cooling water to mix directly with the steam and reduce the steam temperature by absorbing heat through the evaporation of water. The indirect contact desuperheater uses metal or other heat-conducting materials as a heat transfer medium to transfer heat between steam and cooling water without directly mixing the two. This type of desuperheater generally has better control performance and higher efficiency.

[0039] How does a cogeneration system work?

[0040] Water is heated in the boiler 4 to become high-pressure and high-temperature steam. The steam pressure is . The steam first enters the high-pressure cylinder 1 to do work, and then passes through the medium-pressure cylinder 2 and the low-pressure cylinder 3 in turn, finally completing the cascade utilization of energy, and in this process, it drives the turbine to rotate to generate electricity. In this process, part of the steam extracted from the high-pressure cylinder 1 and the medium-pressure cylinder 2 of the steam turbine is used to heat the water in the high-pressure heater 21. After three rounds of heating, the superheated steam is condensed into water and enters the deaerator 5 to remove the dissolved oxygen in the water; the steam that has done part of the work is extracted from the low-pressure cylinder 3 and enters the low-pressure heater 22 to heat the feed water to increase its temperature, thereby reducing the steam discharged from the steam turbine to the condenser 6, reducing the condensation load of the condenser 6, and improving the cycle efficiency of the system. In addition, the hot steam desuperheater 9 can reduce the steam temperature to a suitable level by heat exchanging the steam with the cooling medium inside the desuperheater 9 before the superheated steam enters the steam turbine, thereby protecting the steam turbine from overheating damage.

[0041] Operating principle of the residual pressure utilization system

[0042] The excess pressure utilization unit is an excess pressure utilization device added to the front end of the heat network heat exchanger, which includes a vortex tube 10, which is connected to the medium pressure cylinder 2 through a steam extraction pipe 31. The vortex tube is a device that can separate compressed gas into two parts: a cold air flow and a hot air flow. Its working principle is based on the vortex effect and the principle of fluid dynamics. When the compressed gas enters the vortex chamber through the nozzle in a high-speed rotating manner, a free vortex is formed. Due to the difference in angular velocity, friction is generated between the layers of the free vortex, resulting in a decrease in the temperature of the air flow in the center, which becomes a cold air flow, while the temperature of the air flow in the outer part increases, becoming a hot air flow. This separation leads to the formation of a temperature gradient, so that cold air is released at one end and hot air is released at the other end, which is achieved by the vortex tube relying on the high energy of the incoming compressed gas. In this embodiment, the inlet of the vortex tube utilizes the excess pressure of the steam extraction of the medium pressure cylinder to separate the steam of this part into a cold air flow and a hot air flow. It should be noted that the cold and hot air flows here are relative descriptions relative to the inlet of the vortex tube.

[0043] It can be seen that the high-temperature steam extracted from the medium-pressure cylinder 2 enters the self-regulating vortex tube 10 through the extraction pipe 31, and the high-temperature steam is separated into a cold air flow and a hot air flow through the vortex tube, so as to achieve the purpose of utilizing the residual pressure of the cogeneration system, and the outlet pressure can be reduced to a threshold value that meets the heating system. Since the temperature of the hot air flow is higher than the extraction temperature, the hot air flow is introduced into the heat network heat exchanger 7 to heat the heat network circulating water that returns from the heat user 8 to the heat network heat exchanger. After heating the circulating water, the temperature of the hot air flow is reduced and enters the condenser through the connecting pipe 35 and mixes with the cold air flow. The heated circulating water also reaches the heating temperature to continue to heat the heat user.

[0044] The excess pressure utilization unit also includes a heat network heat exchanger, which is mainly used to utilize the steam extraction of the steam turbine or the steam generated by the boiler to heat the circulating water in the hot water supply system to meet the heating demand. In the shell and tube structure, the heat medium (such as steam) flows in the inner tube, and the heat exchanged material transfers heat through the shell outside the tube. Heat exchange is completed through the wall of the tube to achieve cooling of the heat medium or heating of the heat exchanged material.

[0045] The hot air flow at the hot end of the vortex tube 10 enters the condenser 6 through the hot end tube 34, the heat network heat exchanger 7 and the return pipe 35 in sequence. The cold end of the vortex tube 10 is connected to the condenser 6 through the cold end tube 36. The heat user 8 is connected to the heat network heat exchanger 7 through the heat exchange pipeline 37. When a phase change occurs in the vortex tube, the precipitated condensed water can be discharged from the cold end of the vortex tube and then directly enter the condenser 6 to mix with the fluid returned by the return pipe 35, thereby improving the condensation effect of the condenser 6.

[0046] Since the vortex tube 10 separates the incoming flow of the steam extraction pipe 31 into a cold air flow and a hot air flow, after the hot air flow enters the heat network heat exchanger 7, the temperature is higher than the traditional steam extraction temperature. The larger heat transfer temperature difference means that under the premise of the heat exchange capacity of the heat exchanger remaining unchanged, the heat exchanger area can be greatly reduced, and the investment cost and floor space / area of ​​the heat exchanger can be reduced; at the same time, the cold end outlet product enters the condenser directly, which can also reduce the cold load required by the condenser and reduce the operating cost of the air cooler. That is, the volume or heat exchange area of ​​the heat network heat exchanger 7 can be reduced. The cold air flow separated by the vortex tube 10 directly enters the condenser 6, which also reduces the heat exchange pressure of the condenser 6, and thus the volume or heat exchange area of ​​the condenser 6 can also be reduced.

[0047] Compared with the traditional technology of using throttle valve to extract steam and reduce the pressure of the intermediate pressure cylinder, the steam extracted from the pressure cylinder in this embodiment uses a vortex tube to separate hot and cold by utilizing the residual pressure, thereby replacing the throttle valve of the prior art. The hot end outlet temperature increases to produce superheated steam, which increases the heat exchange capacity of the steam. The heat exchange can be saved by entering the heat network heater; the cold end outlet temperature decreases, and a part of the gas can even condense. The gas-liquid mixture with reduced temperature enters the air cooler, which can also reduce a part of the cold load of the air cooler; of course, the working fluid at the hot end outlet and the cold end outlet can also be mixed by the ejector before entering the air cooler. Therefore, the residual pressure utilization system can improve the efficiency of heat exchange and condensation of the heat network by using the vortex tube 10 in conjunction with the heat network heat exchanger 7 and the condenser 6, thereby reducing the size of the heat network heat exchanger 7 and the condenser 6. In the construction of the cogeneration unit, the investment cost of the heat network heat exchanger 7 and the condenser 6 can be greatly reduced, and the economic benefits can be significantly improved. Compared with the traditional excess pressure utilization system that uses extraction steam to heat circulating water through a throttle valve, the excess pressure utilization system with integrated vortex tube has a larger heat exchange temperature difference and enhances the degree of fluid chaos, so its heat exchange capacity is stronger, reducing the heat exchange area required by the heat exchanger and thus reducing economic costs. In addition, due to the separation effect of the vortex tube, the cold air flow is mixed with the hot air flow after heat exchange, and the temperature of the gas-liquid mixture is lower than that of the traditional excess pressure utilization system, which also reduces the condensing load of the condenser to a certain extent, thereby reducing its economic cost.

[0048] According to actual engineering experience, the vortex tube is considered as an isenthalpic process, the inlet temperature of the vortex tube is consistent with the extraction temperature of 134-152℃, and the inlet pressure is 0.3-0.5Mpa; existing technical research shows that when the cold flow ratio is 0.76, if the cold end outlet and inlet pressure ratio is calculated as 0.25, according to the principles of conservation of mass and energy, it can be calculated according to the formula P h =P in *(1-c) / c calculates the approximate range of the hot end pressure value. However, to calculate the exact value of the heat transfer outlet temperature rise and the cold end outlet temperature drop, numerical simulation calculations are also required based on the state of the hot and cold end outlet steam, enthalpy value, specific heat capacity and other parameters.

[0049] Heating network heater: When the system power is 300MW, the steam saturation pressure is 0.07-0.14Mpa, the design water supply temperature is 120-130℃, the actual water supply temperature is 80-100℃, the design return water temperature is 70℃, the actual return water temperature is 50℃, and the upper end difference of the heater is 10℃.

[0050] Self-regulating vortex tube

[0051] The vortex tube 10 is a device that uses high-speed rotating airflow for energy separation. By injecting compressed gas into the vortex tube, it rotates at high speed in the tube, thereby achieving temperature separation and forming two cold and hot airflows. In this specific embodiment, it is proposed to adaptively adjust the flow rate of the vortex tube according to the parameters (temperature and pressure) of the incoming flow of the vortex tube, and always keep the vortex tube in a better working state, so as to cope with the fluctuation of the incoming flow of the high-temperature steam extracted from the medium-pressure cylinder 2 into the self-regulating vortex tube 10 through the extraction pipe 31. The self-regulating vortex tube is described in detail in the applicant's prior application CN2024112063768. In this specific embodiment, the self-regulating vortex tube is applied to the cogeneration system to prevent the incoming flow fluctuation of the extraction pipe 31 from causing damage to the rear-end equipment.

[0052] The self-adjusting vortex tube has a vortex chamber and an inlet nozzle 11, a cold end tube, and a hot end tube all connected to the vortex chamber. On the basis of the main structure of the vortex tube, a piston cylinder and an inlet transmission structure are newly added, that is, Figure 2 The inlet transmission structure includes a cylinder and a ring structure driven to rotate by the cylinder; the inlet main pipeline is connected to the inlet nozzle 11, the inlet branch pipeline is connected to the rodless cavity of the cylinder, and the piston rod of the cylinder is drivingly connected to the ring structure;

[0053] The control valve plate 16 is located between the valve seat 18 and the nozzle 17. The control valve plate 16 can adjust the opening of the nozzle 17 and control the flow rate of the incoming flow in the inlet nozzle 11 under the drive of the circular ring structure; when the incoming flow pressure increases, part of the incoming flow gas enters the rodless chamber of the cylinder through the incoming flow branch pipeline, and the piston rod of the cylinder 8 drives the circular ring structure to rotate and expands the flow area of ​​the inlet nozzle 11 by rotating the control valve plate 16, automatically adapting to the higher inlet pressure and flow.

[0054] When in use, if the incoming flow pressure increases, part of the incoming flow gas enters the piston cylinder through the bypass, the gas pressure above the self-adjusting vortex tube cylinder increases and squeezes the piston to move downward, thereby driving the outer ring of the inlet transmission device to rotate clockwise, and then pushing the control rod to move inward, squeezing the movable valve plate to expand the inlet nozzle area of ​​the vortex tube, so as to adapt to higher inlet pressure and flow. When the incoming flow pressure decreases, part of the gas in the piston cylinder leaves the cylinder and merges into the main road from the bypass, the gas pressure above the cylinder decreases and pulls the piston upward, thereby driving the outer ring of the inlet transmission device to rotate counterclockwise, and then pulling the control rod to move outward, the movable valve plate rebounds to reduce the inlet nozzle area of ​​the vortex tube, so as to adapt to lower inlet pressure and flow. As a result, the device realizes that the vortex tube pressure reduction system can maintain a relatively stable gas outlet state under different incoming flow pressures.

[0055] The cylinder-driven adaptive adjustment structure of the self-regulating vortex tube can respond quickly when the fluid pressure fluctuates, so as to cope with the fluctuation of the incoming flow of high-temperature steam extracted from the medium-pressure cylinder 2 through the steam extraction pipe 31 into the self-regulating vortex tube 10, and reduce the oscillation and over-adjustment of the system. Moreover, the cylinder can adapt to harsh environments, such as high temperature, high pressure, corrosive media, etc., to ensure the normal operation of the valve under these conditions. This structure helps to maintain the stable operation of the production line.

[0056] See also Figure 2-4 , and also includes: a circular ring structure is coaxially installed with the vortex tube, an adjusting block 14 is provided on the circular ring structure, a driving block 19 is provided on the side of the vortex chamber, the driving block 19 can control the valve plate 16 to rotate relative to the valve seat 18, and the driving control rod 15 passes through the adjusting block 14 and is connected to the driving block 19.

[0057] In this embodiment, there are multiple inlet nozzles 11 and they are evenly distributed in the circumferential direction. The multiple inlet nozzles 11 can better accelerate the high-pressure incoming gas and form a high-speed swirl, creating conditions for energy separation. When the gas passes through the inlet nozzles 11, it will expand and accelerate rapidly, forming a strong swirling airflow. This swirling airflow produces an energy separation effect inside the vortex chamber, causing the temperature of the gas to differ between the center and the outer edge.

[0058] The ring structure is used to synchronously control the valve opening of multiple inlet nozzles 11, so it is installed coaxially with the self-adjusting vortex tube. The gas pressure above the cylinder increases and squeezes the piston to move downward, thereby driving the outer ring of the inlet transmission device to rotate clockwise. A driving block 19 is provided on the side of the vortex chamber. Figure 4 The driving block 19 is arranged on the side end of the vortex chamber near the cold end tube. The driving block 19 can control the rotation of the valve plate 16 relative to the valve seat 18, and drive the control rod 15 to pass through the adjusting block 14 and be connected to the driving block 19. When the gas pressure above the self-adjusting vortex tube cylinder increases and squeezes the piston to move downward, the outer ring structure of the inlet transmission device is driven to rotate clockwise. The ring structure then rotates the driving block 19 by pushing the control rod 15. The driving block 19 further rotates the control valve plate 16, and the rotation angles of multiple control valve plates 16 are the same, so the openings of each nozzle 11 are also the same.

[0059] In this embodiment, the ring structure further includes: the ring structure includes a first control ring 12 and a second control ring 13, the adjustment block 14 is rotatably arranged between the first control ring 12 and the second control ring 13, and the hole of the adjustment block 14 is relatively slidably connected with the control rod 15. The driving block 19 includes a sleeve and a shaft outside the sleeve, the sleeve is fixedly connected with the control rod 15, and the shaft passes through the side of the vortex chamber and is fixedly connected with the control valve plate 16.

[0060] When the circular ring structure rotates to push the control rod 15, the control rod 15 changes its position, and its relative position with the adjustment block 14 also changes, and a sliding displacement occurs between the control rod 15 and the hole of the adjustment block 14. This sliding fit between the hole and the shaft can prevent motion interference between the transmission components.

[0061] In this embodiment, a reset element is further included, which can keep the control valve plate 16 at a preset opening of the nozzle 17 or restore it to a preset opening of the nozzle 17 .

[0062] The reset element is a prior art, such as using a spring sleeved on the cylinder piston rod, when the incoming flow pressure returns to the preset value, the cylinder piston can return to the preset position under the action of the spring, that is, the entire self-regulating vortex tube is reset.

[0063] This embodiment also includes a hot end self-regulating component, and further includes:

[0064] A temperature conduction module, a bimetallic structure 7 and a linkage lever, wherein the temperature conduction module can transfer heat to the bimetallic structure 7 and is respectively connected to the incoming flow main line and the hot end outlet of the vortex tube. When the bimetallic structure 7 changes shape according to temperature changes, it drives the linkage lever to move. The linkage lever is connected to the regulating valve 5. The regulating valve 5 can move axially along the hot end tube 4 and adjust the opening of the hot end outlet of the vortex tube.

[0065] The hot end self-regulating component is used to control the hot end control valve to adjust the hot end outlet area according to the temperature of the incoming gas, thereby adjusting the flow rate of the hot end outlet of the vortex tube, and then adjusting the flow ratio of the hot and cold ends of the vortex tube.

[0066] The bimetallic structure is composed of two different metals. This composite structure can bring out the advantages of the two metals and produce a synergistic effect, thereby improving the overall performance. In the temperature adaptive regulation system, the bimetallic structure is used in conjunction with the temperature conduction module to respond to changes in the incoming flow temperature according to the temperature of the incoming flow main line and the hot end outlet of the vortex tube.

[0067] Economic Benefit Analysis

[0068] This embodiment provides a calculation method for economic benefit analysis of the aforementioned combined heat and power unit heat supply steam extraction residual pressure utilization system. It should be noted that this method is only a preferred calculation method and cannot be regarded as a limitation of the aforementioned technology.

[0069] In order to facilitate the analysis and research of the system, Figure 1 Mark the points as follows Figure 5 As shown, a simplified mathematical model is proposed before data analysis:

[0070] 1) The performance of water vapor in the vortex tube is referenced to air with the same parameters;

[0071] 2) All points in the entire system are in a steady state during operation;

[0072] 3) Ignore the pressure loss caused by each connecting pipe;

[0073] 4) The process in the vortex tube is an isenthalpic process.

[0074] 1 Energy analysis

[0075] First, monitoring instruments are arranged at key locations such as the inlet and outlet of the vortex tube and the inlet and outlet of the heat exchanger to monitor parameters such as temperature, pressure, flow rate and humidity in real time. The mass conservation and energy conservation equations of various components including boilers, turbines, heaters, vortex tubes and heat network heat exchangers are established. Based on the first law of thermodynamics, the enthalpy changes at the inlet and outlet of each component are calculated under specified operating conditions to obtain the energy change and mass change of steam in each heat exchange process, and evaluate the energy conversion efficiency and loss. Finally, the experimental results of the residual pressure utilization system of the integrated vortex tube and the system using a throttle valve for air flow decompression are compared and analyzed, and improvement measures to improve energy conversion efficiency and reduce energy loss are proposed.

[0076] For the residual pressure utilization system, the enthalpy calculation of the vortex tube inlet and outlet can be carried out according to the following formula:

[0077] h out =h in -η nozzle (h in -h out,is ), where η nozzle The isentropic efficiency refers to the degree of closeness between the gas state change and the isentropic process during the operation of the vortex tube. The isentropic efficiency η nozzle Determined by multiple factors such as cold flow ratio, pressure ratio, and structural design, a vortex tube with high isentropic efficiency means that it has less energy loss and better performance. Therefore, the mass and energy conservation equations of the vortex tube are: m in =m cold +m hot ,h in =ch cold +(1-c)h hot , c is the cold flow ratio of the vortex tube.

[0078] according to Figure 5 Based on the point diagram and the above assumptions, the mass conservation and energy conservation equations of the residual pressure utilization system of the integrated vortex tube are as follows:

[0079]

[0080] 2 analyze

[0081] As the maximum limit of energy available in the system, it reflects the irreversibility of the energy conversion process. Based on temperature, pressure, flow and other data, the actual cogeneration cycle and the cogeneration cycle with integrated vortex tube are calculated for each link. Values, including input Output and Loss. By comparing the input With useful output The ratio of the residual pressure utilization system of the integrated vortex tube and the air flow pressure reduction system using a throttle valve are compared and analyzed. Efficiency and The main link of loss. For links with greater losses, it is proposed to reduce irreversibility and improve Efficiency improvement measures.

[0082] Each state point The value is calculated as follows:

[0083] E x =m[(h-h0)-T0(s-s0)], h0 and s0 are the specific enthalpy and specific entropy of steam at the reference point. Generally, the ambient temperature T0 is taken as 298.15K and P0 is taken as 101.325kPa.

[0084] Thermodynamic processes The loss is calculated according to the following formula:

[0085] Ex d,k =∑EX in,k -∑EX out,k ±Q(1-T0 / T)±W

[0086] Ex in，k and Ex out,k represents the thermodynamic process of flow into and out of the kth component Q(1-T0 / T) and W represent the heat exchanged between the working fluid in the component and the outside world and the work done by the component. Exd,k represents the loss.

[0087] according to Figure 5 Based on the above assumptions, the residual pressure of the integrated vortex tube is utilized by the components of the system. The loss calculation is as follows:

[0088]

[0089] 3 Economic Analysis

[0090] Build on Cost Conservation Equation Economic model is used to quantify economic costs, and by calculating system construction investment costs, fuel costs, and operation and maintenance costs, the system's Economic coefficient f k 、Fuel cost C F,k , product cost C P as well as Loss Cost C D，k The economic feasibility of the system is evaluated by these indicators, and the economic benefits of the residual pressure utilization system with integrated vortex tube and the air flow pressure reduction system using throttle valve are compared.

[0091] The cost conservation equation is: ∑C in,k +C Q,k +Z k =∑C out,k +C w,k , where C in,k , C Q,k , C W,k , C out, k represents the cost rate associated with the fluid input, heat input, work input, and fluid output of the kth component, Z k is the cost rate of the component itself.

[0092] Cost rate C ex =cEx,C w =cW,C q =cQ(1-T0 / T), where c is the unit cost, respectively Unit cost, unit cost of work done, unit cost of heat exchange.

[0093] In addition, the system fuel cost rate C F,k and product cost rate C P,k There is the following relationship: C P，k =C F,k +Z k , Z k =Z k ci +Z k om , Z k om =1.5% Z k ci , where Z k is the total investment cost rate of the component itself, Z k ci is the investment cost rate of the component, Z k om is the operating cost rate of the component, zk is the component cost, is the maintenance factor, τ is the annual operating time (hours). CRF=i(i+1) n / [(i+1) n -1] is the capital recovery factor, i is the annual interest rate, and n is the useful life of the component. Fuel cost rate C F,k and product cost rate C P,k is empirical data. Zk can be calculated according to the formula given by empirical data. For high-pressure cylinder, medium-pressure cylinder and low-pressure cylinder, Z tur =4405W k 0.7 , the rest of the components can use Z k =130(A k / 0.093) 0.78 , where Ak is the heat transfer area of ​​the component [ 4 ].

[0094] and Economic coefficient f k It can be calculated by the following formula: k =Z k / (Z k +C D,K ), you can use f k Evaluate the importance of system components, where C D,k represents the kth component The loss cost rate can be calculated as follows: C D,k =c f,k *Ex D,k , c f,k is the average unit cost c of the kth component fuel f,k =C F,k / E f,k , E f,k For fuel System fuel cost rate is the total system cost rate, is the total fuel cost rate of the system, The total output of the system

[0095] according to Figure 5 Based on the above assumptions, the residual pressure of the integrated vortex tube is utilized by the components of the system. The cost conservation equation is shown below:

[0096]

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. Heat and power cogeneration unit heat extraction steam excess pressure utilization system, including: The air supply unit and the heating unit are characterized by: The air supply unit comprises a boiler (4), a high-pressure cylinder (1) connected to the boiler (4), a medium-pressure cylinder (2) connected to the high-pressure cylinder (1), and a low-pressure cylinder (3) connected to the medium-pressure cylinder (2); The heating unit comprises a low-pressure heater (22) connected to the low-pressure cylinder (3), a high-pressure heater (21) connected to the high-pressure cylinder (1) and the medium-pressure cylinder (2), a condenser (6) connected to the low-pressure heater (23) and the low-pressure cylinder (3), and a deaerator (5) connected to the low-pressure heater (22) and the high-pressure heater (21); It also includes a surplus pressure utilization unit, which includes a vortex tube (10), which is connected to the medium-pressure cylinder (2) through a steam extraction pipe (31); and a heat network heat exchanger, wherein the hot air flow at the hot end of the vortex tube (10) passes through a hot end pipe (34), a heat network heat exchanger (7) and a return pipe (35) in sequence to enter the condenser (6), and the cold end of the vortex tube (10) is connected to the condenser (6) through a cold end pipe (36), and a heat user (8) is connected to the heat network heat exchanger (7) through a heat exchange pipeline (37).

2. The system for utilizing excess pressure of steam extraction from a combined heat and power unit for heating according to claim 1, characterized in that: The high-pressure cylinder 1 is a subcritical boiler, the steam temperature of the high-pressure cylinder is about 540°C, and the working pressure is 15.7-19.6Mpa.

3. The system for utilizing excess pressure of steam extraction from a combined heat and power unit for heating according to claim 1, characterized in that: The intermediate pressure cylinder 2 is located after the high pressure cylinder. The exhaust steam pressure of the intermediate pressure cylinder is guaranteed to be above 0.4Mpa, the exhaust temperature is about 240℃, the extraction steam pressure of the intermediate pressure cylinder is 0.3Mpa-0.5Mpa, and the temperature is 134-152℃.

4. The system for utilizing excess pressure of steam extraction from a combined heat and power unit for heating according to claim 1, characterized in that: The vortex tube (10) comprises a vortex chamber, an inlet nozzle (11) which is in communication with the vortex chamber, a cold end, and a hot end, and further comprises: The inlet transmission structure comprises a cylinder and a circular ring structure driven to rotate by the cylinder; the inlet main pipeline is connected to the inlet nozzle (11), the inlet branch pipeline is communicated with the rodless cavity of the cylinder, and the piston rod of the cylinder is drivingly connected to the circular ring structure; A control valve plate (16) is located between the valve seat (18) and the nozzle (17). The control valve plate (16) can adjust the opening of the nozzle (17) and control the flow rate of the incoming flow in the inlet nozzle (11) under the drive of the circular ring structure; when the incoming flow pressure increases, part of the incoming flow gas enters the rodless chamber of the cylinder through the incoming flow branch pipeline, and the piston rod of the cylinder (8) drives the circular ring structure to rotate and expands the flow area of ​​the inlet nozzle (11) by rotating the control valve plate (16), automatically adapting to the higher inlet pressure and flow rate.

Images