Medium-pressure flexible heat supply system

Abstract

The invention discloses a medium-pressure flexible heat supply system, and relates to the technical field of boiler heat supply, the medium-pressure flexible heat supply system comprises a main steam standby heat supply pipeline system, a medium-pressure heat supply pipeline system, a reheating pipeline system and a control system, the main steam standby heat supply pipeline system is used for supplying heat to users under the medium-pressure heat supply 30%-40% operation condition, and the reheating pipeline system is used for supplying heat to the users under the medium-pressure heat supply 30%-40% operation condition; according to the main steam standby heat supply pipeline system, holes are formed in a main steam pipeline led out of a boiler for air exhaust, and heat is supplied to a user after temperature and pressure reduction; the medium-pressure heat supply pipeline system is used for supplying heat to users under the medium-pressure heat supply 40%-100% operation condition, and the medium-pressure heat supply pipeline system supplies heat to the users through temperature reduction after punching and air exhausting of a high-pressure cylinder of a steam turbine and reheating of a medium-pressure heat supply reheater. The reheating pipeline system is used for returning heat supply flow required by heat supply of redundant users in the medium-pressure heat supply pipeline system to the boiler for reheating; the control system controls operation of all the pipeline systems. By means of the system, energy waste can be effectively reduced.

Description

Technical Field

[0001] The present application relates to the technical field of boiler heating, and in particular to a medium-pressure flexible heating system. Background Art

[0002] The medium-pressure heating pressure is generally greater than 4.0MPa, and factories and enterprises have strict requirements on heating flow, temperature, and stability. In the heat recovery system of 300MW subcritical units, there is no suitable steam extraction port except the main steam pipeline. Therefore, under the premise of medium-pressure and large-flow heating, the main steam is often used for direct temperature reduction and pressure reduction. The traditional use of main steam direct temperature reduction and pressure reduction for heating leads to high energy and low use. Although the heating capacity is improved, the energy-saving effect is poor and there is a large waste of energy. Summary of the invention

[0003] The main purpose of this application is to provide a medium-pressure flexible heating system to solve the above-mentioned technical problems.

[0004] The technical solutions adopted in this application are as follows:

[0005] A medium-pressure flexible heating system, comprising:

[0006] The main steam standby heating pipeline system is used to provide heating to users under the medium-pressure heating 30% to 40% operating condition. The main steam standby heating pipeline system uses holes in the main steam pipeline drawn from the boiler to extract air, and provides heating to users after reducing temperature and pressure;

[0007] A medium-pressure heating pipeline system, which is used to provide heating to users under the operating condition of 40% to 100% medium-pressure heating. The medium-pressure heating pipeline system uses the air extracted from the high-pressure cylinder of the steam turbine to be reheated by the medium-pressure heating reheater and then provides heating to users by cooling;

[0008] A reheat piping system, the reheat piping system is used to return the excess heat flow of the user's heating demand in the medium-pressure heating piping system to the boiler for reheating and then send it to the medium-pressure cylinder of the steam turbine; and,

[0009] A control system, wherein the control system is used to control the operation of the main steam standby heating pipeline system, the medium-pressure heating pipeline system, and the reheat pipeline system.

[0010] Optionally, the main steam standby heating pipeline system includes:

[0011] A main steam pipe, which is led out from the boiler and connected to the high-pressure cylinder of the steam turbine;

[0012] A main steam standby heating pipeline, one end of which is connected to the main steam pipeline, and the other end is connected to the user-end heating pipeline.

[0013] Optionally, the main steam standby heating pipeline is provided with a quick-closing check valve A, a quick-closing valve A, and an electric shut-off valve A in sequence from one side of the main steam pipeline to the other side of the user-end heating pipeline. 1 , Temperature and pressure reduction device, Safety valve A, Electric shut-off valve A 2 .

[0014] Optionally, the temperature reduction and pressure reduction device is externally connected to a temperature reduction water pipeline A, and the temperature reduction water pipeline A is provided with a flow valve A and an electric shut-off valve A. 3 , electric regulating valve A, check valve A.

[0015] Optionally, the medium-pressure heating pipeline system includes:

[0016] A medium-pressure heating and exhaust pipe, one end of which is connected to the high-pressure cylinder of the steam turbine;

[0017] A medium-pressure heating reheater, the medium-pressure heating reheater is connected to the other end of the medium-pressure heating exhaust pipeline;

[0018] A medium-pressure heating pipeline, one end of which is connected to the medium-pressure heating reheater, and the other end is connected to the user-end heating pipeline.

[0019] Optionally, the medium-pressure heating exhaust pipe is provided with a quick-closing check valve B, a quick-closing valve B and a quick-closing valve B in sequence from the high-pressure cylinder side of the steam turbine to the medium-pressure heating reheater side. 1 , Electric regulating valve B 1 And flow valve B 1 , pressure sensor.

[0020] Optionally, the medium-pressure heating pipeline is provided with a temperature reduction device and a quick-closing valve B in sequence from one end of the medium-pressure heating reheater to one side of the user-end heating pipeline. 2 The cooling device is connected to a cooling water pipeline B, and a flow valve B is provided on the cooling water pipeline B. 2 , Electric shut-off valve B, Electric regulating valve B 2 , check valve B.

[0021] Optionally, a flow valve C, an electric shut-off valve C and a safety valve C are provided on the client heating pipeline.

[0022] Optionally, the reheat piping system includes:

[0023] A reheat cold section pipeline, one end of which is connected to the high pressure cylinder of the steam turbine;

[0024] A temperature mixing device, the temperature mixing device is connected to the other end of the reheat cold section pipeline;

[0025] A boiler reheater, wherein the boiler reheater is connected to the temperature mixing device through a pipeline;

[0026] A reheat hot section pipeline, one end of which is connected to the boiler reheater, and the other end of which is connected to the intermediate pressure cylinder of the steam turbine;

[0027] A return air duct, one end of which is connected to the temperature reduction device and the quick-closing valve B 2 The other end is connected between the temperature mixing device and the boiler reheater, and the return air pipeline is provided with an electric shut-off valve D 1 , Electric regulating valve D and electric shut-off valve D 2 .

[0028] Optionally, the temperature mixing device is connected to a cooling water pipeline C, and the cooling water pipeline C is provided with a flow valve C, an electric shut-off valve C, an electric regulating valve C, and a check valve C.

[0029] Compared with the prior art, the beneficial effects of this application are:

[0030] A medium-pressure flexible heating system proposed in the embodiment of the present application can provide heating to users under a wide load condition of 30% to 100% by adding a medium-pressure heating pipeline system on the basis of the main steam standby heating pipeline system. The medium-pressure heating pipeline system is used to replace the simple main steam medium-pressure heating under the operating condition of 40% to 100%, thereby reducing the disadvantages of high energy and low utilization caused by direct temperature and pressure reduction heating of the main steam pipeline, reducing energy waste, and creating considerable economic value for the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a structural block diagram of the medium-pressure flexible heating system provided in an embodiment of the present application.

[0032] Description of the reference numerals in the accompanying drawings:

[0033] 1- boiler, 2- turbine high pressure cylinder, 3- turbine medium pressure cylinder, 4- turbine low pressure cylinder, 5- generator, 6- control system, 7- quick closing check valve B, 8- quick closing valve B 1 , 9-Electric regulating valve B 1 , 10-flow valve B 1 , 11-medium pressure heating reheater, 12-cooling device, 13-fast closing valve B 2 , 14-flow valve C, 15-electric shut-off valve, 16-electric shut-off valve D 1 , 17-Electric regulating valve D, 18-Electric shut-off valve D 2 , 19-Quick closing check valve A, 20-Quick closing valve A, 21-Electric shut-off valve A 1 , 22-temperature and pressure reduction device, 23-safety valve A, 24-electric shut-off valve A2 , 25-safety valve C, 26-flow valve, 27-electric shut-off valve A 3 , 28-electric regulating valve A, 29-check valve A, 30-flow valve C, 31-electric shut-off valve C, 32-electric regulating valve C, 33-check valve C, 34-mixing temperature device, 35-flow valve B 2 , 36-electric shut-off valve B, 37-electric regulating valve B 2 , 38-check valve B, 39-pressure sensor, 40-boiler reheater. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0035] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0036] In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0037] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0038] See attached Figure 1 The embodiment of the present application provides a medium-pressure flexible heating system, including a main steam standby heating pipeline system, a medium-pressure heating pipeline system, a reheating pipeline system and a control system. Among them, the main steam standby heating pipeline system is used to provide heating for users under the medium-pressure heating 30% to 40% operating condition. The main steam standby heating pipeline system uses the main steam pipeline drawn from the boiler to extract air through holes, and then provides heating for users after reducing temperature and pressure; the medium-pressure heating pipeline system is used to provide heating for users under the medium-pressure heating 40% to 100% operating condition. The medium-pressure heating pipeline system uses the high-pressure cylinder of the steam turbine to extract air through holes, and then reheats it through the medium-pressure heating reheater, and then provides heating for users through reducing temperature; the reheating pipeline system is used to return the excess heating flow of the user's heating demand in the medium-pressure heating pipeline system to the boiler for reheating and then sends it to the medium-pressure cylinder of the steam turbine; the control system is used to control the operation of the main steam standby heating pipeline system, the medium-pressure heating pipeline system, and the reheating pipeline system.

[0039] Specifically:

[0040] The medium-pressure heating pipeline system includes a medium-pressure heating exhaust pipeline, a medium-pressure heating reheater 11 and a medium-pressure heating pipeline. Among them, one end of the medium-pressure heating exhaust pipeline is connected to the high-pressure cylinder 2 of the steam turbine, and the medium-pressure heating exhaust pipeline is connected by drilling a hole on the high-pressure cylinder 2 of the steam turbine for exhaust. The steam extraction port needs to meet the 40% to 100% working condition. The extraction pressure is higher than 4.2MPa. Therefore, the actual working pressure of the steam extraction port is between 4.2 and 7MPa, and the extraction temperature is between 370 and 400℃ according to different operating conditions. The other end of the medium-pressure heating exhaust pipeline is connected to the medium-pressure heating reheater 11. The medium-pressure heating reheater 11 is set in the boiler 1. The extraction temperature cannot meet the industrial heating demand, and the extraction steam is sent to the boiler 1 for reheating. First, according to the various operating conditions of the steam turbine, the boiler reduces the original boiler reheater 40 heating surface, and uses the reduced area to set the heating surface of the medium-pressure heating reheater, so that the medium-pressure heating temperature meets the heating demand. At the same time, the medium-pressure heating reheater 11 is connected to one end of the medium-pressure heating pipeline, and the other end is connected to the user-end heating pipeline, and the user-end heating pipeline is provided with a flow valve C14, an electric shut-off valve C15 and a safety valve C25.

[0041] like Figure 1 As shown, the medium-pressure heating exhaust pipe is provided with a quick-closing check valve B7, a quick-closing valve B 1 8. Electric regulating valve B 1 9 and flow valve B 1 10. Pressure sensor 39. The gas extracted from the high-pressure cylinder 2 of the steam turbine is reheated by the medium-pressure heating reheater 11 and then sent to the user end for use. The steam temperature after being heated by the medium-pressure heating reheater 11 needs to be controlled within the design parameter range. To ensure the suitability of the steam temperature, a temperature reduction device 12 and a quick-closing valve B are sequentially arranged on the medium-pressure heating pipeline from one end of the medium-pressure heating reheater 11 to the side of the heating pipeline at the user end. 2 13. The cooling device 12 is connected to a cooling water pipeline B, and a flow valve B is provided on the cooling water pipeline B. 2 35. Electric shut-off valve B36. Electric regulating valve B 2 37. Check valve B38. It can be understood that when the steam heated by the medium-pressure heating reheater 11 passes through the temperature reducing device 12, the temperature reducing device 12 monitors the temperature and cooperates with the temperature reducing water pipeline B to pass the temperature reducing water to the temperature reducing device 12 to form heat exchange with the steam, thereby adjusting the gas temperature to meet user needs. The temperature reducing water comes from the high-pressure water supply system and is configured with flow valves B in sequence. 2 35. Electric shut-off valve B36. Electric regulating valve B 2 37. Check valve B38, based on the monitored gas temperature, controls the electric shut-off valve B36 and the electric regulating valve B through the controller. 2The opening size of 37 is used to adjust the flow rate of desuperheating water to adjust the air temperature. The design flow rate of medium-pressure heating is 80t / h. The heating users may have steam load fluctuations, but the medium-pressure heating reheater 11 requires a stable steam flow rate. Therefore, the medium-pressure heating steam extraction volume should maintain a certain flow rate Q unchanged. When the external heat supply Q1 is consistent with the temperature-adjusted steam volume Q2, heat is directly supplied to the outside. When the external heat supply Q1 < Q2, the excess steam returns to the boiler through the reheat pipe system for reheating.

[0042] like Figure 1 As shown, the reheat pipe system includes a reheat cold section pipe, a temperature mixing device 34, a boiler reheater 40, a reheat hot section pipe and a return air pipe. Among them, one end of the reheat cold section pipe is connected to the high pressure cylinder 2 of the steam turbine, the other end of the reheat cold section pipe is connected to the temperature mixing device 34, the temperature mixing device 34 is connected to the boiler reheater 40 through a pipe, one end of the reheat hot section pipe is connected to the boiler reheater 40, and the other end is connected to the steam turbine intermediate pressure cylinder 3, the steam turbine intermediate pressure cylinder 3 is connected to the steam turbine low pressure cylinder 4, the steam turbine low pressure cylinder 4 is connected to the engine 5, and one end of the return air pipe is connected to the temperature reduction device 12 and the quick closing valve B 2 13, the other end is connected to the temperature mixing device 34 and the boiler reheater 40, and an electric shut-off valve D is provided on the return air pipeline. 1 16. Electric regulating valve D17 and electric shut-off valve D 2 18. The temperature mixing device is connected to a cooling water pipeline C, and the cooling water pipeline C is provided with a flow valve C30, an electric shut-off valve C31, an electric regulating valve C32, and a check valve C33.

[0043] Based on the structural characteristics of the medium-pressure heating pipeline system, its working logic is:

[0044] First: When the medium pressure heating is put into normal operation under the operating conditions of 40% to 100%

[0045] S1: The control logic of steam extraction pressure is: the control system 6 issues a command to open the fast closing check valve B7 and the fast closing valve B 1 8. Electric regulating valve B 1 9. Quick closing check valve B7, quick closing valve B 1 8 is in full open state. The pressure control value of the medium-pressure heating exhaust pipeline is set to 4.2MPa in the control system 6, and a pressure sensor 39 is installed on the exhaust pipeline. The actual measured value of the pressure sensor 39 is sent to the control system 6, and the electric regulating valve B is adjusted through the calculation logic of the control system 6. 1 9 opening, through valve throttling to achieve wide load control of extraction pressure, flow valve B 1 10. Monitor the extraction steam flow rate (Q).

[0046] S2: The control logic of external heating temperature is as follows: the control system 6 issues a command, the temperature reduction device 12 is put into use, and the fast closing check valve B7 and the fast closing valve B 1 8. Electric regulating valve B 1 9. Quick closing valve B 2 13. Electric shut-off valve C15, external heat supply. The medium-pressure extraction steam is heated by the modified medium-pressure heating reheater 11. The temperature measurement point signal in the temperature reduction device 12 is sent to the control system 6. After the operation logic of the control system 6, the electric shut-off valve B36 and the check valve B38 are opened, and the opening of the electric regulating valve 37 is adjusted. The temperature control is achieved by adjusting the temperature reduction water volume. Flow valve B 2 35 Monitor the cooling water flow rate (Q4).

[0047] S3: The control logic of external heat supply flow is as follows: based on the flow valve C14 monitoring the actual flow (Q1) at the user end, it is sent to the control system 6. After the operation logic of the control system 6, when the extraction steam flow (Q) is greater than the external heat supply flow (Q1), the electric shut-off valve D is opened. 1 16. Electric regulating valve D17 and electric shut-off valve D 2 18. Adjust the opening of the electric regulating valve D17 to return the exhaust flow to the reheat pipeline system to achieve external heat supply flow control.

[0048] Second: When the medium-pressure heating is shut down at 40% to 100% of the working condition

[0049] S1: The control logic of extraction steam pressure is consistent with normal operation.

[0050] S2: The temperature control logic for external heating is consistent with normal operation.

[0051] S3: The control logic of the external heat supply flow is consistent with the normal operation, which is an extreme case where Q1 = 0. At this time, the control system 6 sends a signal to close the electric shut-off valve C15, and no heat is supplied to the outside.

[0052] Third: Safety protection for accident conditions

[0053] When the external heat supply is suddenly cut off, the control system 6 receives the external heat supply cut-off signal and quickly closes the quick-closing valve B. 2 13. The external heating flow is zero, and all the medium-pressure heating extraction steam returns to the reheat pipeline system.

[0054] When external heat supply is suddenly cut off, it may cause instantaneous overpressure in the external medium-pressure pipeline. A safety valve C25 is installed to serve as an emergency relief.

[0055] In this implementation, if Figure 1As shown, the main steam standby heating pipeline system includes a main steam pipeline and a main steam standby heating pipeline. The main steam pipeline is led out from the boiler 1 and connected to the high-pressure cylinder 2 of the steam turbine. One end of the main steam standby heating pipeline is connected to the main steam pipeline. The main steam pipeline is punched and evacuated to connect to the main steam standby heating pipeline. The other end of the main steam standby heating pipeline is connected to the user-end heating pipeline, located at the quick-closing valve B. 2 Between 13 and flow valve C14.

[0056] Among them, the main steam standby heating pipeline is provided with a quick closing check valve A19, a quick closing valve A20, an electric shut-off valve A19 and a quick closing check valve A20 in sequence from the main steam pipeline side to the user end heating pipeline side. 1 21. Temperature and pressure reduction device 22. Safety valve A 23. Electric shut-off valve A 2 24. At the same time, the temperature reduction and pressure reduction device is connected to a temperature reduction water pipeline A, on which a flow valve A26 and an electric shut-off valve A are provided. 3 27. Electric regulating valve A28, check valve A29.

[0057] When the medium-pressure heating extraction steam pressure cannot meet the external heating demand, it is necessary to switch to the medium-pressure heating 30% to 40% operating condition (main steam emergency standby condition). Control system 6 issues a switching command to close the quick-closing valve B. 2 13. The medium-pressure heating pipeline system continues to maintain the balance of the thermal system according to the logic when the medium-pressure heating is shut down at 40% to 100% operating conditions.

[0058] The main steam pipeline is perforated with holes for steam extraction, and is equipped with quick-closing check valve A19, quick-closing valve A20, electric shut-off valve A 1 21. Temperature and pressure reduction device 22. Safety valve A 23. Electric shut-off valve A 2 24, the pipeline is finally merged into the user-side heating pipeline. The temperature reduction and pressure reduction device 22 is equipped with a temperature reduction water system. The temperature reduction water comes from the high-pressure water supply system and is equipped with a flow valve A26, an electric shut-off valve A 3 27. Electric regulating valve A28, check valve A29.

[0059] When switching to the main steam emergency standby mode, the steam flow rate of the reheat cold section will inevitably decrease. In order to achieve the design flow rate for external heat supply, there is a safety risk of overheating of the boiler reheater 40. A new desuperheating water pipeline C is configured. A high-pressure desuperheating water is introduced to the reheat cold section pipeline to reduce the temperature of the reheat cold section pipeline, increase the steam flow rate of the reheat cold section pipeline, and protect the boiler reheater 40. The desuperheating water comes from the high-pressure water supply system, and is sequentially provided with a flow valve C30, an electric shut-off valve C31, an electric regulating valve C32, and a check valve C33, and finally enters the temperature mixing device 34 on the reheat cold section pipeline to establish a new thermodynamic cycle and avoid overheating of the boiler reheater 40.

[0060] Based on the structural characteristics of the main steam standby heating pipeline system, its working logic is:

[0061] When medium pressure heating is put into normal operation at 30% to 40% working condition

[0062] When switching to the main steam emergency standby state, the control system 6 issues a command to close the quick closing valve B 2 13. The medium-pressure heating pipeline system continues to maintain the balance of the thermal system according to the logic when the medium-pressure heating is shut down at 40% to 100% operating conditions.

[0063] When switching to the main steam emergency standby state, the control system 6 issues a command to open the quick-closing check valve A19, quick-closing valve A20, and electric shut-off valve A 1 21. Temperature and pressure reduction device 22. Electric shut-off valve A 2 twenty four.

[0064] Pressure measuring points are provided before and after the temperature reduction and pressure reduction device 22. The actual measured value after the temperature reduction and pressure reduction device 22 is sent to the control system 6. Through the operation logic of the control system 6, the opening of the pressure reducing valve of the temperature reduction and pressure reduction device 22 is adjusted, and the precise control of the steam extraction pressure is achieved through valve throttling.

[0065] A temperature measuring point is provided behind the cooling and pressure reducing device 22, and the actual measured value behind the cooling and pressure reducing device 22 is sent to the control system 6. After the operation logic of the control system 6, the opening of the electric regulating valve A28 is adjusted, and precise temperature control is achieved by adjusting the cooling water volume.

[0066] A flow valve C14 is provided on the external heating steam pipeline. The actual measured value of the flow valve C14 is sent to the control system 6. After the operation logic of the control system 6, the opening of the pressure reducing valve of the temperature reduction and pressure reducing device 22 is adjusted, and the extraction steam flow is precisely controlled through valve throttling.

[0067] The reheat flow regulation control leads a high-pressure desuperheating water to the reheat cold section pipeline, reduces the temperature of the reheat cold section pipeline, increases the steam flow of the reheat cold section pipeline, and protects the boiler reheater 40. The control system 6 issues a command to open the electric shut-off valve C31, the electric regulating valve C32, and the check valve C33. The reheat cold section flow and temperature parameters are sent to the control system 6. After the operation logic of the control system 6, the opening of the electric regulating valve C32 is adjusted. The reheat flow is regulated by adjusting the desuperheating water volume to prevent the boiler reheater 40 from overheating.

[0068] When the medium pressure heating is stopped at 30% to 40%

[0069] When the medium-pressure heating 30% to 40% operating condition stops, the operating logic is switched to the medium-pressure heating 40% to 100% operating condition.

[0070] The control system 6 issues a command to close the quick-closing check valve A19, quick-closing valve A20, and electric shut-off valve A 1 21. Temperature and pressure reduction device 22. Electric shut-off valve A 2 24. Shut down the standby heating and cooling water system and close the electric shut-off valve A. 3 27. Electric regulating valve A28, check valve A29.

[0071] The control system 6 issues a command to shut down the reheat pipeline system, close the electric shut-off valve C31, the electric regulating valve C32, and the check valve C33.

[0072] Safety protection for accident conditions under medium pressure heating 30% to 40% conditions

[0073] When the external heat supply is suddenly cut off, the main steam emergency standby mode is shut down. The control system 6 receives the external heat supply cut-off signal and quickly closes the quick-closing check valve A19, quick-closing valve A20, and electric shut-off valve A 1 21. Temperature and pressure reduction device 22. Electric shut-off valve A 2 24. Electric shut-off valve A 3 27. Electric regulating valve A28, check valve A29. The standby extraction steam flow rate for external heating is zero, and all the medium-pressure heating extraction steam returns to the original system.

[0074] When the temperature and pressure reduction device 22 fails to regulate the pressure, a safety valve A23 is provided to protect the safety of the subsequent system pipelines. The safety valve A23 will trip when the preset value is exceeded to protect the safety of the system pipelines.

[0075] In summary, after adopting the medium-pressure flexible heating system, it replaces the simple main steam medium-pressure heating under 40% to 100% working conditions. Taking 80t / h heating steam as an example, 3.5MW more electricity can be generated per hour; based on 7000h a year, 24.5 million more electricity can be generated throughout the year. According to the on-grid electricity price of 0.4 yuan / KWh, 9.8 million yuan can be earned each year, 7,350 tons of standard coal can be saved each year, and 19,447.5 tons of carbon dioxide emissions can be reduced.

[0076] After adopting the medium-pressure flexible heating system, wide-load medium-pressure heating can be achieved under 30% to 100% operating conditions, ensuring the safety of downstream enterprises and bringing good economic benefits to coal-fired power units. Based on the main steam medium-pressure heating scheme for 1,000 hours, the heating price is calculated at 200 yuan / ton, and considering other operating costs, without considering the initial fine, the company can directly benefit by 6 million yuan after adopting the medium-pressure flexible heating system.

[0077] After adopting the medium-pressure flexible heating system, when operating under conditions below 40%, the reheat steam flow rate is increased through the desuperheating water pipeline C, effectively preventing the boiler reheater from overheating, providing technical support for further improving the main steam and reheat cold section heating, and providing a solid theoretical foundation for enterprises to respond to new power systems and gain benefits from the heating transformation.

[0078] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A medium-pressure flexible heating system, characterized in that: include: The main steam standby heating pipeline system is used to provide heating to users under the medium-pressure heating 30% to 40% operating condition. The main steam standby heating pipeline system uses holes in the main steam pipeline drawn from the boiler to extract air, and provides heating to users after reducing temperature and pressure; A medium-pressure heating pipeline system, which is used to provide heating to users under the operating condition of 40% to 100% medium-pressure heating. The medium-pressure heating pipeline system uses the air extracted from the high-pressure cylinder of the steam turbine to be reheated by the medium-pressure heating reheater and then provides heating to users by cooling; A reheat piping system, the reheat piping system is used to return the excess heat flow of the user's heating demand in the medium-pressure heating piping system to the boiler for reheating and then send it to the medium-pressure cylinder of the steam turbine; and, A control system, wherein the control system is used to control the operation of the main steam standby heating pipeline system, the medium-pressure heating pipeline system, and the reheat pipeline system.

2. The medium-pressure flexible heating system according to claim 1, characterized in that: The main steam standby heating pipeline system comprises: A main steam pipe, which is led out from the boiler and connected to the high-pressure cylinder of the steam turbine; A main steam standby heating pipeline, one end of which is connected to the main steam pipeline, and the other end is connected to the user-end heating pipeline.

3. The medium-pressure flexible heating system according to claim 2, characterized in that: The main steam standby heating pipeline is provided with a quick-closing check valve A, a quick-closing valve A, an electric shut-off valve A1, a temperature and pressure reduction device, a safety valve A, and an electric shut-off valve A2 in sequence from one side of the main steam pipeline to the other side of the user-end heating pipeline.

4. The medium-pressure flexible heating system according to claim 3, characterized in that: The temperature reduction and pressure reduction device is externally connected to a temperature reduction water pipeline A, and the temperature reduction water pipeline A is provided with a flow valve A, an electric shut-off valve A3, an electric regulating valve A, and a check valve A.

5. The medium-pressure flexible heating system according to claim 1, characterized in that: The medium-pressure heating pipeline system comprises: A medium-pressure heating and exhaust pipe, one end of which is connected to the high-pressure cylinder of the steam turbine; A medium-pressure heating reheater, the medium-pressure heating reheater is connected to the other end of the medium-pressure heating exhaust pipeline; A medium-pressure heating pipeline, one end of which is connected to the medium-pressure heating reheater, and the other end is connected to the user-end heating pipeline.

6. The medium-pressure flexible heating system according to claim 5, characterized in that: The medium-pressure heating exhaust pipeline is provided with a quick-closing check valve B, a quick-closing valve B1, an electric regulating valve B1, a flow valve B1, and a pressure sensor in sequence from the high-pressure cylinder side of the steam turbine to the medium-pressure heating reheater side.

7. The medium-pressure flexible heating system according to claim 5, characterized in that: A cooling device and a quick-closing valve B2 are sequentially arranged on the medium-pressure heating pipeline from one end of the medium-pressure heating reheater to one side of the user-end heating pipeline. The cooling device is connected to a cooling water pipeline B, and the cooling water pipeline B is provided with a flow valve B2, an electric shut-off valve B, an electric regulating valve B2, and a check valve B.

8. The medium-pressure flexible heating system according to claim 2 or 5, characterized in that: A flow valve C, an electric shut-off valve C and a safety valve C are arranged on the client heating pipeline.

9. The medium-pressure flexible heating system according to claim 7, characterized in that: The reheat piping system comprises: A reheat cold section pipeline, one end of which is connected to the high pressure cylinder of the steam turbine; A temperature mixing device, the temperature mixing device is connected to the other end of the reheat cold section pipeline; A boiler reheater, wherein the boiler reheater is connected to the temperature mixing device through a pipeline; A reheat hot section pipeline, one end of which is connected to the boiler reheater, and the other end of which is connected to the intermediate pressure cylinder of the steam turbine; A return air pipeline, one end of which is connected between the temperature reducing device and the quick-closing valve B2, and the other end is connected between the temperature mixing device and the boiler reheater. An electric shut-off valve D1, an electric regulating valve D and an electric shut-off valve D2 are provided on the return air pipeline.

10. The medium-pressure flexible heating system according to claim 9, characterized in that: The temperature mixing device is connected to a cooling water pipeline C, and a flow valve C, an electric shut-off valve C, an electric regulating valve C, and a check valve C are arranged on the cooling water pipeline C.

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