Boiler waste heat utilization system in shutdown mode of gas heat supply unit

Abstract

The utility model relates to the technical field of energy conservation and emission reduction, in particular to a boiler waste heat utilization system in a shutdown and boiler shutdown mode of a gas heat supply unit, which comprises a boiler, a high-pressure system, a low-pressure system and a heat supply main pipe, a heat supply sub-pipe is arranged between the high-pressure system and the low-pressure system in a communicating mode, the heat supply sub-pipe is communicated with the heat supply main pipe, the heat supply sub-pipe is provided with a high-pressure isolation hand valve, and a high-pressure steam supply pressure adjusting valve is arranged in the high-pressure system. The high-pressure steam supply pressure adjusting valve is used for adjusting the pressure of high-pressure steam in the high-pressure system, and a low-pressure isolation hand valve is arranged in the low-pressure system. The system has the effects of improving the utilization rate of the boiler excess pressure heat energy and prolonging the heat supply duration.

Description

Technical Field

[0001] The utility model relates to the technical field of energy conservation and emission reduction, and in particular to a boiler waste heat utilization system in a shutdown mode of a gas heating unit. Background Art

[0002] A gas-fired heating unit is a device that uses the heat energy generated by the combustion of natural gas to generate electricity and heat. It usually includes a gas turbine and a waste heat boiler (high-pressure system heat exchanger, low-pressure system heat exchanger). The principle is that natural gas is transported to the combustion system of the gas turbine through a pipeline, mixed with the compressed air discharged from the compressor in a certain proportion and then burned to generate high-pressure and high-temperature gas. These high-energy gases are converted into mechanical energy through the gas turbine to drive the generator to generate electricity. The high-temperature gas of nearly 600 degrees discharged by the gas turbine is transferred to the waste heat boiler, which heats the water in the boiler and converts it into superheated steam. The superheated steam is sent to the steam turbine through a pipeline, and the steam turbine and the generator driven by it convert the mechanical energy into electrical energy. Among them, a part of the low-pressure steam in the waste heat boiler will be led to the heating pipeline to meet the needs of heat users.

[0003] In the prior art, when the unit stops running, the remaining residual pressure heat energy in the boiler can enable the low-pressure system to continue to heat the heating pipe for a period of time. When the pressure and temperature can no longer meet the heating requirements, other boilers are used for heating. However, when the unit stops running, the high-pressure system part in the boiler still has residual high-temperature and high-pressure heat energy, which cannot be effectively utilized, making it difficult to meet the requirements of energy conservation and emission reduction, and an urgent problem needs to be solved. Utility Model Content

[0004] In response to the deficiencies in the above-mentioned prior art, the present application provides a boiler waste heat utilization system in the shutdown mode of a gas-fired heating unit, which is intended to enable the gas-fired heating unit to automatically switch to the high-pressure system for heating when the actual pressure of the low-pressure system drops to the minimum pressure limit, and utilize the residual heat inside the boiler's high-pressure system; when the pressure of the low-pressure system rises to within the pressure range required for heating, it switches back to the low-pressure system for heating, thereby improving the utilization rate of the energy after the waste heat boiler is shut down, extending the heating time, and achieving the purpose of energy saving.

[0005] The above invention objectives of the present application are achieved through the following technical solutions:

[0006] A boiler waste heat utilization system in a shutdown mode of a gas-fired heating unit comprises a boiler, a high-pressure system, a low-pressure system and a heating main pipe, wherein the low-pressure system is connected to the heating main pipe, a heating sub-pipe is provided between the high-pressure system and the low-pressure system, the heating sub-pipe is connected to the heating main pipe, the heating sub-pipe is provided with a high-pressure isolation hand valve, a high-pressure steam supply pressure regulating gate is provided in the high-pressure system, the high-pressure steam supply pressure regulating gate is used to adjust the pressure of the high-pressure steam in the high-pressure system, and a low-pressure isolation hand valve is provided in the low-pressure system.

[0007] By adopting the above technical scheme, after the gas heating unit is shut down, the residual heat energy remaining in the boiler enables the low-pressure system to continue to supply heat to the heating pipeline. When the actual pressure of the low-pressure system drops to the minimum steam supply pressure limit, the high-pressure isolation hand valve is opened and the low-pressure isolation hand valve is closed. Then, the high-pressure steam supply pressure regulating gate adjusts the pressure of the high-pressure steam in the high-pressure system to the pressure value range required for heating of the low-pressure system. At this time, the steam in the high-pressure system can be transported to the heating main pipe through the heating sub-pipe to continue to supply heat to the heat users. Then, the residual heat stored in the high-pressure system inside the boiler, under the action of air flow, will gradually transfer the heat energy of the high-pressure part to the low-pressure system, so that the pressure of the steam in the low-pressure system gradually rises to the pressure value range required for heating. At this time, the high-pressure isolation hand valve is closed and the low-pressure isolation hand valve is opened, and the low-pressure system continues to supply heat to the heating main pipe, thereby realizing the high-pressure system and the low-pressure system to alternately supply heat under the action of the boiler residual pressure, so as to improve the utilization rate of the boiler residual pressure heat energy, extend the heating time, and maximize the utilization of heat energy.

[0008] In a preferred example, the present application can be further configured as follows: the low-pressure system includes a low-pressure superheater, a low-pressure steam collecting manifold and a low-pressure steam drum, the low-pressure superheater is arranged in the tail flue inside the boiler, the low-pressure steam collecting manifold and the low-pressure steam drum are both arranged outside the boiler, a low-pressure transmission pipeline is connected between the low-pressure steam drum and the low-pressure superheater, between the low-pressure superheater and the low-pressure steam collecting manifold, and between the low-pressure steam collecting manifold and the heating main pipe, and the low-pressure isolation manual valve is arranged on the low-pressure transmission pipeline between the low-pressure steam collecting manifold and the heating main pipe.

[0009] By adopting the above technical scheme, the low-pressure superheater exchanges heat with the flue gas in the tail flue of the boiler, so that the saturated steam from the low-pressure drum can be heated, and the heated steam is transported to the low-pressure steam collecting box through the low-pressure transmission pipeline, so that the low-pressure steam collecting box distributes the steam, and then it is transported to the heating pipe through the low-pressure transmission pipeline for heating. Since the temperature in the tail flue of the boiler is lower than that at the inlet, the low-pressure superheater is arranged in the tail flue of the boiler, which is suitable for the temperature conditions of the low-pressure system, can effectively utilize the waste heat of the flue gas at the tail of the boiler, and improve the thermal efficiency of the boiler. At the same time, the low-pressure isolation hand valve is arranged in the low-pressure transmission pipeline between the low-pressure steam collecting box and the heating main pipe, which can effectively control the steam supply function of the low-pressure system.

[0010] In a preferred example, the present application can be further configured as follows: the high-pressure system includes a high-pressure superheater, a high-pressure steam collecting manifold, and a high-pressure steam drum; the high-pressure superheater is arranged at the internal inlet of the boiler; the high-pressure steam collecting manifold and the high-pressure steam drum are both arranged outside the boiler; a high-pressure transmission pipeline is connected between the high-pressure steam drum and the high-pressure superheater, between the high-pressure superheater and the high-pressure steam collecting manifold, and between the high-pressure steam drum and the heating sub-pipe; the high-pressure steam supply pressure regulating valve is arranged on the high-pressure transmission pipeline between the high-pressure steam drum and the heating sub-pipe.

[0011] By adopting the above technical solution, since the temperature at the inlet of the boiler is relatively high, the high-pressure superheater is arranged at the inlet of the boiler, which is suitable for the temperature conditions of the high-pressure system, and compared with the low-pressure system, it can ensure that the pressure of the heating sub-pipe is maintained within the pressure value range required for heating, thereby improving the utilization rate of the boiler's excess pressure heat energy. At the same time, the high-pressure steam supply pressure regulating gate is arranged between the high-pressure steam drum and the heating sub-pipe, which can effectively control the steam supply pressure of the high-pressure system.

[0012] In a preferred example, the present application can be further configured as follows: the boiler waste heat utilization system in the shutdown mode of the gas heating unit also includes a DCS monitoring system, the high-pressure isolation manual valve and the low-pressure isolation manual valve are both controlled and connected to the DCS monitoring system, and the DCS monitoring system is used to detect the actual pressure value in the low-pressure system and monitor the internal temperature and pressure of the boiler.

[0013] By adopting the above technical solution, the DCS monitoring system can complete the data monitoring and decentralized control of the heating process, so as to adjust the switch status of the high-pressure isolation hand valve and the low-pressure isolation hand valve in the first time when the low-pressure system is lower than or within the pressure value range required for heating.

[0014] In summary, the present application includes at least one of the following beneficial technical effects:

[0015] 1. When the actual pressure of the low-pressure system drops to the minimum steam supply pressure limit, the high-pressure steam supply pressure regulating valve adjusts the pressure of the high-pressure steam in the high-pressure system to the pressure value range required for heating of the low-pressure system, and then opens the high-pressure isolation hand valve and closes the low-pressure isolation hand valve. At this time, the steam in the high-pressure system can be transported to the heating main pipe through the heating sub-pipe to continue heating. Then, under the action of the residual heat inside the boiler, the pressure of the low-pressure system gradually rises to the pressure value range required for heating. At this time, the pressure of the high-pressure steam in the high-pressure system is restored through the high-pressure steam supply pressure regulating valve, and then the high-pressure isolation hand valve is closed and the low-pressure isolation hand valve is opened, so that the low-pressure system can heat the heating main pipe, thereby realizing the alternating heating of the high-pressure system and the low-pressure system under the action of the boiler residual pressure, so as to improve the utilization rate of the boiler residual pressure heat energy and extend the heating time.

[0016] 2. By setting up a DCS monitoring system, data monitoring and decentralized control of the heating process can be completed, so that when the low-pressure system is lower than or within the pressure value range required for heating, the switch status of the high-pressure isolation hand valve and the low-pressure isolation hand valve can be adjusted in the first time. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a system schematic diagram of the utility model.

[0018] Figure numerals: 1. boiler; 2. high-pressure system; 21. high-pressure superheater; 22. high-pressure steam header; 23. high-pressure steam drum; 24. high-pressure transmission pipeline; 3. low-pressure system; 31. low-pressure superheater; 32. low-pressure steam header; 33. low-pressure steam drum; 34. low-pressure transmission pipeline; 4. heating main pipe; 5. heating sub-pipe; 6. high-pressure isolation manual valve; 7. high-pressure steam supply pressure regulating valve; 8. low-pressure isolation manual valve; 9. gas turbine compressor; 10. gas turbine combustion chamber; 11. gas turbine; 12. gas turbine generator. DETAILED DESCRIPTION

[0019] The following is a description of exemplary embodiments of the present application in conjunction with the accompanying drawings, including various details of the embodiments of the present application to facilitate understanding, which should be considered as merely exemplary. Therefore, it should be recognized by those of ordinary skill in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. Similarly, for the sake of clarity and conciseness, the description of well-known functions and structures is omitted in the following description.

[0020] It should be noted that the terms "first", "second", etc. in the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure.

[0021] In addition, the term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article, unless otherwise specified, generally means that the associated objects before and after are in an "or" relationship.

[0022] The following describes a boiler waste heat utilization system in a shutdown mode of a gas heating unit of the present application with reference to the accompanying drawings.

[0023] like Figure 1 As shown, the boiler waste heat utilization system in the shutdown mode of the gas heating unit includes a boiler 1, a high-pressure system 2, a low-pressure system 3, and a heating main pipe 4. The low-pressure system 3 is connected to the heating main pipe 4. A heating sub-pipe 5 is connected between the high-pressure system 2 and the low-pressure system 3. The heating sub-pipe 5 is connected to the heating main pipe 4. The heating sub-pipe 5 is provided with a high-pressure isolation hand valve 6. A high-pressure steam supply pressure regulating valve 7 is provided in the high-pressure system 2. The high-pressure steam supply pressure regulating valve 7 is used to adjust the pressure of the high-pressure steam in the high-pressure system 2. A low-pressure isolation hand valve 8 is provided in the low-pressure system 3. After the gas heating unit is shut down, the remaining waste pressure heat in the boiler 1 enables the low-pressure system 3 to continue to supply heat to the heating pipeline. When the actual pressure of the low-pressure system 3 drops to the minimum pressure limit, the high-pressure isolation hand valve 6 is opened and the low-pressure isolation hand valve 8 is closed, and then the high-pressure steam supply pressure regulating valve 7 is provided. The valve 7 adjusts the pressure of the high-pressure steam in the high-pressure system 2 to the pressure value range required for heating by the low-pressure system 3. At this time, the steam in the high-pressure system 2 can be transported to the heating main pipe 4 through the heating sub-pipe 5 to continue to provide heating to the heat users. Then, the residual heat stored in the high-pressure system 2 inside the boiler 1 will gradually transfer part of the heat energy of the high-pressure system 2 to the low-pressure system 3 under the action of air flow. That is, under the action of the residual heat inside the boiler 1, the pressure of the low-pressure system 3 gradually rises to the pressure value range required for heating. At this time, the high-pressure isolation hand valve 6 is closed and the low-pressure isolation hand valve 8 is opened, and the low-pressure system 3 is used to supply heat to the heating main pipe 4, thereby realizing alternating heating between the high-pressure system 2 and the low-pressure system 3 under the action of the residual pressure of the boiler 1, so as to improve the utilization rate of the residual pressure heat energy of the boiler 1, extend the heating time, and maximize the utilization of thermal energy.

[0024] It should be noted that, usually, a gas turbine compressor 9, a gas turbine combustion chamber 10, a gas turbine 11 and a gas turbine generator 12 are sequentially arranged at the internal entrance of the boiler 1. The gas turbine compressor 9 inhales external air and mixes it with the fuel gas to form a mixed gas of a specified pressure value, which is then burned in the gas turbine combustion chamber 10. The heat energy generated by the combustion is used to generate electricity under the action of the gas turbine 11 and the fuel turbine generator 12. Finally, the remaining heat energy enters from the internal entrance of the boiler 1 to maintain a high temperature and high pressure environmental condition at the internal entrance of the boiler 1, which is convenient for the operation of the high-pressure system 2. As the heat is transferred and dissipated during the flow of flue gas inside the boiler 1, the temperature in the tail flue inside the boiler 1 is lower than that at the entrance, which is convenient for the operation of the low-pressure system 3.

[0025] Furthermore, the low-pressure system 3 includes a low-pressure superheater 31, a low-pressure steam header 32 and a low-pressure drum 33. The low-pressure superheater 31 is arranged in the tail flue inside the boiler 1, and the low-pressure steam header 32 and the low-pressure drum 33 are both arranged outside the boiler 1. A low-pressure conveying pipeline 34 is arranged between the low-pressure drum 33 and the low-pressure superheater 31, between the low-pressure superheater 31 and the low-pressure steam header 32, and between the low-pressure steam header 32 and the heating mother pipe 4. A low-pressure isolation hand valve 8 is arranged on the low-pressure conveying pipeline 34 between the low-pressure steam header 32 and the heating mother pipe 4. The low-pressure superheater 31 performs heat exchange with the flue gas in the tail flue of the boiler 1, so that the flue gas from the low-pressure drum 33 is The saturated steam is heated, and the heated steam is transported to the low-pressure steam collecting box 32 through the low-pressure transmission pipe 34, so that the low-pressure steam collecting box 32 distributes the steam, and then transports it to the heating pipe through the low-pressure transmission pipe 34 for heating. Since the temperature in the tail flue of the boiler 1 is lower than that at the inlet, the low-pressure superheater 31 is arranged in the tail flue of the boiler 1, which is suitable for the temperature condition of the low-pressure system 3, and can effectively utilize the waste heat of the tail flue gas of the boiler 1 to improve the thermal efficiency of the boiler 1. At the same time, the low-pressure isolation manual valve 8 is arranged in the low-pressure transmission pipe 34 between the low-pressure steam collecting box 32 and the heating main pipe 4, which can effectively control the steam supply function of the low-pressure system 3.

[0026] In addition, the high-pressure system 2 includes a high-pressure superheater 21, a high-pressure steam header 22, and a high-pressure steam drum 23. The high-pressure superheater 21 is arranged at the internal inlet of the boiler 1, and the high-pressure steam header 22 and the high-pressure steam drum 23 are both arranged outside the boiler 1. A high-pressure delivery pipeline 24 is connected between the high-pressure steam drum 23 and the high-pressure superheater 21, between the high-pressure superheater 21 and the high-pressure steam header 22, and between the high-pressure steam drum 23 and the heating sub-pipe 5. A high-pressure steam supply pressure regulating gate 7 is arranged on the high-pressure delivery pipeline 24 between the high-pressure steam drum 23 and the heating sub-pipe 5. Since the temperature at the internal inlet of the boiler 1 is relatively high, the high-pressure superheater 21 is arranged at the internal inlet of the boiler 1, which is suitable for the temperature condition of the high-pressure system 2. Compared with the low-pressure system 3, it can ensure that the pressure of the heating sub-pipe 5 is maintained within the pressure value range required for heating, thereby improving the utilization rate of the excess pressure heat energy of the boiler 1. At the same time, the high-pressure steam supply pressure regulating gate 7 is arranged between the high-pressure steam drum 23 and the heating sub-pipe 5, which can effectively control the steam supply pressure of the high-pressure system 2.

[0027] Specifically, the high-pressure superheater 21 and the low-pressure superheater 31 are both heat exchangers that heat saturated steam into superheated steam to increase the dryness and temperature of the steam. The high-pressure steam collecting manifold 22 and the low-pressure steam collecting manifold 32 are both thick-diameter pipe boxes connected to multiple groups of heating surface tubes. Many pipe holes are opened on the box body for welding or expanding pipes so that the various heating surface tubes can be effectively connected and buffered to ensure the stable operation of the steam system. The high-pressure steam drum 23 and the low-pressure steam drum 33 are both storage devices for storing steam to ensure that stable pressure steam can be provided when needed to ensure the stable operation of the high-pressure system 2 and the low-pressure system 3.

[0028] In order to improve the automation level of the system, in one embodiment, the boiler waste heat utilization system in the shutdown mode of the gas heating unit also includes a DCS monitoring system (not shown in the figure), and the high-pressure isolation hand valve 6 and the low-pressure isolation hand valve 8 are both controlled and connected to the DCS monitoring system. The DCS monitoring system is used to detect the actual pressure value in the low-pressure system 3 and monitor the internal temperature and pressure of the boiler 1. The DCS monitoring system can complete data monitoring and decentralized control of the heating process to achieve the first adjustment of the switch status of the high-pressure isolation hand valve 6 and the low-pressure isolation hand valve 8 when the low-pressure system 3 is lower than or within the pressure value range required for heating.

[0029] Specifically, the DCS monitoring system is a computer system that integrates computers, communications, displays and controls for process control and process monitoring. The main functions of the system are data acquisition and processing, monitoring and alarm, control and regulation, historical data recording and trend analysis, etc. It aims to achieve goals such as automated control, optimization of production processes, and improvement of production efficiency and quality. It is suitable for the operating conditions of gas heating units.

[0030] The above specific implementations do not constitute a limitation on the protection scope of this application. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of this application should be included in the protection scope of this application.

Claims

1. A boiler waste heat utilization system in a shutdown mode of a gas heating unit, comprising a boiler (1), a high-pressure system (2), a low-pressure system (3) and a heating main pipe (4), wherein the low-pressure system (3) is connected to the heating main pipe (4), and is characterized in that: A heating sub-pipe (5) is provided between the high-pressure system (2) and the low-pressure system (3), the heating sub-pipe (5) is connected to the heating main pipe (4), the heating sub-pipe (5) is provided with a high-pressure isolation hand valve (6), a high-pressure steam supply pressure regulating valve (7) is provided in the high-pressure system (2), the high-pressure steam supply pressure regulating valve (7) is used to regulate the pressure of high-pressure steam in the high-pressure system (2), and a low-pressure isolation hand valve (8) is provided in the low-pressure system (3).

2. A boiler waste heat utilization system in a shutdown mode of a gas-fired heating unit according to claim 1, characterized in that: The low-pressure system (3) comprises a low-pressure superheater (31), a low-pressure steam collecting manifold (32) and a low-pressure steam drum (33); the low-pressure superheater (31) is arranged in the tail flue inside the boiler (1); the low-pressure steam collecting manifold (32) and the low-pressure steam drum (33) are both arranged outside the boiler (1); a low-pressure delivery pipeline (34) is arranged between the low-pressure steam drum (33) and the low-pressure superheater (31), between the low-pressure superheater (31) and the low-pressure steam collecting manifold (32), and between the low-pressure steam collecting manifold (32) and the heating main pipe (4); the low-pressure isolation manual valve (8) is arranged on the low-pressure delivery pipeline (34) between the low-pressure steam collecting manifold (32) and the heating main pipe (4).

3. A boiler waste heat utilization system in a shutdown mode of a gas-fired heating unit according to claim 1, characterized in that: The high-pressure system (2) comprises a high-pressure superheater (21), a high-pressure steam collecting manifold (22), and a high-pressure steam drum (23); the high-pressure superheater (21) is arranged at the internal entrance of the boiler (1); the high-pressure steam collecting manifold (22) and the high-pressure steam drum (23) are both arranged outside the boiler (1); a high-pressure delivery pipeline (24) is arranged between the high-pressure steam drum (23) and the high-pressure superheater (21), between the high-pressure superheater (21) and the high-pressure steam collecting manifold (22), and between the high-pressure steam drum (23) and the heating sub-pipe (5); and the high-pressure steam supply pressure regulating valve (7) is arranged on the high-pressure delivery pipeline (24) between the high-pressure steam drum (23) and the heating sub-pipe (5).

4. A boiler waste heat utilization system in a shutdown mode of a gas-fired heating unit according to claim 1, characterized in that: It also includes a DCS monitoring system, the high-pressure isolation hand valve (6) and the low-pressure isolation hand valve (8) are both controlled and connected to the DCS monitoring system, and the DCS monitoring system is used to detect the actual pressure value in the low-pressure system (3) and monitor the internal temperature and pressure of the boiler (1).

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