A combined cycle unit waste heat utilization system and method

Abstract

This invention discloses a waste heat recovery system and method for a combined cycle power unit. The gas-side inlet pipe of the TCA is connected to the gas-side inlet of the TCA, and the gas-side outlet of the TCA is connected to an external turbine via the TCA gas-side outlet pipe. The water-side inlet pipe of the TCA is connected to the water-side inlet of the TCA via a condensate booster pump. The water-side outlet of the TCA is connected to the water-side inlet of the FGH via the TCA water-side outlet pipe and an electric heater bypass valve. The water-side outlet of the FGH is connected to the FGH water-side outlet pipe. The gas-side inlet pipe of the FGH is connected to the first opening of the FGH gas-side inlet temperature control valve. The second opening of the FGH gas-side inlet temperature control valve is connected to the gas-side inlet of the FGH. The gas-side outlet of the FGH is connected to the FGH gas-side outlet pipe. The third opening of the FGH gas-side inlet temperature control valve is connected to the FGH gas-side outlet pipe via the FGH bypass pipe. This system and method can fully recover the heat of the system.

Description

Technical Field

[0001] This invention belongs to the field of thermal system operation optimization of combined cycle units, and relates to a waste heat utilization system and method for combined cycle units. Background Technology

[0002] Waste heat recovery in Mitsubishi M701F3 combined cycle turbine units. This type of unit is equipped with a turbine cooling system (TCA) and a fuel gas heating module (FGH) to cool the turbine blades and heat the natural gas, aiming to ensure unit safety and improve operating efficiency. However, because both the TCA and FGH use open-type forced heat exchange with the air, the air is blown by a convection fan and passes through the TCA and FGH sequentially for heat exchange before being directly discharged into the atmosphere. However, this discharged air still contains a significant amount of unused heat, resulting in heat waste. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a combined cycle unit waste heat utilization system and method that can fully recover the system's heat.

[0004] To achieve the above objectives, the present invention discloses a combined cycle unit waste heat utilization system, including a TCA gas-side inlet pipe, a TCA, a TCA gas-side outlet pipe, a TCA water-side inlet pipe, a condensate booster pump, a TCA water-side outlet pipe, an electric heater bypass valve, an FGH, an FGH water-side outlet pipe, an FGH gas-side inlet pipe, an FGH gas-side inlet temperature control valve, and an FGH gas-side outlet pipe.

[0005] The gas-side inlet pipe of the TCA is connected to the gas-side inlet of the TCA, and the gas-side outlet of the TCA is connected to the external turbine through the gas-side outlet pipe of the TCA.

[0006] The TCA water-side inlet pipe is connected to the TCA water-side inlet via a condensate booster pump. The TCA water-side outlet is connected to the FGH water-side inlet via the TCA water-side outlet pipe and the electric heater bypass valve. The FGH water-side outlet is connected to the FGH water-side outlet pipe.

[0007] The FGH gas-side inlet pipe is connected to the first opening of the FGH gas-side inlet temperature control valve. The second opening of the FGH gas-side inlet temperature control valve is connected to the FGH gas-side inlet. The FGH gas-side outlet is connected to the FGH gas-side outlet pipe. The third opening of the FGH gas-side inlet temperature control valve is connected to the FGH gas-side outlet pipe via the FGH bypass pipe.

[0008] Furthermore, the electric heater bypass valve is connected in parallel to the electric heater pipeline.

[0009] Furthermore, the electric heater pipeline is sequentially equipped with an electric heater inlet valve, an electric heater, and an electric heater outlet valve.

[0010] Furthermore, the TCA gas-side inlet pipe is connected to the TCA gas-side inlet via the TCA gas-side inlet valve.

[0011] Furthermore, it also includes the FGH water-side steam drum outlet valve and the FGH water-side condenser outlet valve. The water-side outlet of the FGH is connected to the FGH water-side steam drum outlet valve and the FGH water-side condenser outlet valve via the FGH water-side outlet pipeline.

[0012] This invention discloses a method for utilizing waste heat from a combined cycle power unit, based on a combined cycle power unit waste heat utilization system, including a unit start-up phase and a load operation phase.

[0013] Furthermore, during the unit startup phase, the condensate booster pump is started to deliver low-temperature condensate to the water side of the TCA for heat exchange with the compressor's extraction steam. Simultaneously, the condensate flow rate is adjusted by regulating the frequency of the condensate booster pump to ensure that the gas-side outlet temperature of the TCA meets the operating requirements. During this process, the compressor extraction steam, cooled by the condensate, is transported to the air turbine through the TCA gas-side outlet pipeline to cool the turbine blades. At the same time, the electric heater bypass valve is closed, and the electric heater inlet valve and outlet valve are opened to start the electric heater. The condensate output from the TCA is heated by the electric heater and then enters the FGH to heat the natural gas. The natural gas enters the FGH through the FGH gas-side inlet temperature control valve to absorb heat, and the heated natural gas is then transported to the gas turbine for combustion.

[0014] Furthermore, during the load operation phase, the frequency of the condensate booster pump is increased with the TCA outlet temperature as the control target to increase the condensate flow rate. The cooled compressed gas is transported to the air turbine through the TCA gas-side outlet pipeline to cool the turbine blades. At the same time, the electric heater bypass valve is gradually opened, the electric heater is closed, and the electric heater inlet valve and outlet valve are gradually closed. The heated condensate releases heat in the FGH. The natural gas is divided into two paths. One path enters the FGH through the FGH gas-side inlet temperature control valve to absorb heat and then enters the FGH gas-side outlet pipeline. The other path mixes with the high-temperature natural gas in the FGH gas-side outlet pipeline through the FGH bypass pipeline to make its temperature meet the unit's operating requirements.

[0015] Furthermore, the TCA gas-side inlet pipe is connected to the TCA gas-side inlet via the TCA gas-side inlet valve.

[0016] Furthermore, it also includes the FGH water-side steam drum outlet valve and the FGH water-side condenser outlet valve. The water-side outlet of the FGH is connected to the FGH water-side steam drum outlet valve and the FGH water-side condenser outlet valve via the FGH water-side outlet pipeline.

[0017] The present invention has the following beneficial effects:

[0018] In specific operation, the combined cycle unit waste heat utilization system and method described in this invention utilizes condensate to absorb heat in the TCA, then releases the heat through the FGH to heat the natural gas, and finally delivers it to the condenser or condensate system according to the condensate parameters. This invention abandons the original open air heat exchange and uses condensate as an intermediate heat exchange medium to not only realize closed-loop cascade utilization of heat, but also ensure the safe and efficient operation of the unit. Attached Figure Description

[0019] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0020] Figure 1 This is a structural diagram of the present invention.

[0021] Among them, 1 is the condensate booster pump, 2 is the TCA, 3 is the electric heater, 4 is the FGH, 5 is the TCA gas-side inlet valve, 6 is the electric heater inlet valve, 7 is the electric heater outlet valve, 8 is the electric heater bypass valve, 9 is the FGH gas-side inlet temperature control valve, 10 is the FGH water-side steam drum outlet valve, 11 is the FGH water-side condenser outlet valve, 12 is the TCA water-side inlet pipe, 13 is the TCA water-side outlet pipe, 14 is the electric heater pipe, 15 is the FGH water-side outlet pipe, 16 is the TCA gas-side inlet pipe, 17 is the TCA gas-side outlet pipe, 18 is the FGH gas-side inlet pipe, 19 is the FGH bypass pipe, and 20 is the FGH gas-side outlet pipe. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0024] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0025] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0026] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0027] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0029] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0030] Example 1

[0031] refer to Figure 1 The combined cycle unit waste heat utilization system of the present invention includes a TCA gas-side inlet pipe 16, TCA2, a TCA gas-side outlet pipe 17, a TCA water-side inlet pipe 12, a condensate booster pump 1, a TCA water-side outlet pipe 13, an electric heater bypass valve 8, FGH4, an FGH water-side outlet pipe 15, an FGH gas-side inlet pipe 18, an FGH gas-side inlet temperature control valve 9, and an FGH gas-side outlet pipe 20; the TCA gas-side inlet pipe 16 is connected to the gas-side inlet of TCA2, and the gas-side outlet of TCA2 is connected to the external turbine via the TCA gas-side outlet pipe 17; the TCA water-side inlet pipe 12 is boosted by condensate... Pump 1 is connected to the water inlet of TCA2. The water outlet of TCA2 is connected to the water inlet of FGH4 via TCA water outlet pipe 13 and electric heater bypass valve 8. The water outlet of FGH4 is connected to FGH water outlet pipe 15. FGH gas inlet pipe 18 is connected to the first opening of FGH gas inlet temperature control valve 9. The second opening of FGH gas inlet temperature control valve 9 is connected to FGH4 gas inlet. FGH4 gas outlet is connected to FGH gas outlet pipe 20. The third opening of FGH gas inlet temperature control valve 9 is connected to FGH gas outlet pipe 20 via FGH bypass pipe 19.

[0032] Example 2

[0033] refer to Figure 1 The combined cycle unit waste heat utilization system of the present invention includes a condensate booster pump 1, a TCA 2, an electric heater 3, an FGH 4, a TCA gas-side inlet valve 5, an electric heater inlet valve 6, an electric heater outlet valve 7, an electric heater bypass valve 8, an FGH gas-side inlet temperature control valve 9, an FGH water-side steam drum outlet valve 10, an FGH water-side condenser outlet valve 11, a TCA water-side inlet pipe 12, a TCA water-side outlet pipe 13, an electric heater pipe 14, an FGH water-side outlet pipe 15, a TCA gas-side inlet pipe 16, a TCA gas-side outlet pipe 17, an FGH gas-side inlet pipe 18, an FGH bypass pipe 19, and an FGH gas-side outlet pipe 20.

[0034] The TCA gas-side inlet pipe 16 is connected to the gas-side inlet of TCA2 via the TCA gas-side inlet valve 5, and the gas-side outlet of TCA2 is connected to the external turbine via the TCA gas-side outlet pipe 17.

[0035] The TCA water-side inlet pipe 12 is connected to the water-side inlet of TCA2 via the condensate booster pump 1. The water-side outlet of TCA2 is connected to the water-side inlet of FGH4 via the TCA water-side outlet pipe 13 and the electric heater bypass valve 8. The water-side outlet of FGH4 is connected to the FGH water-side steam drum outlet valve 10 and the FGH water-side condenser outlet valve 11 via the FGH water-side outlet pipe 15.

[0036] The electric heater bypass valve 8 is connected in parallel to the electric heater pipeline 14. The electric heater pipeline 14 is sequentially equipped with the electric heater inlet valve 6, the electric heater 3, and the electric heater outlet valve 7.

[0037] The FGH gas-side inlet pipe 18 is connected to the first opening of the FGH gas-side inlet temperature control valve 9, the second opening of the FGH gas-side inlet temperature control valve 9 is connected to the gas-side inlet of FGH4, the gas-side outlet of FGH4 is connected to the FGH gas-side outlet pipe 20, and the third opening of the FGH gas-side inlet temperature control valve 9 is connected to the FGH gas-side outlet pipe 20 via the FGH bypass pipe 19.

[0038] Example 3

[0039] refer to Figure 1 This embodiment discloses a method for utilizing waste heat from a combined cycle unit. The method is based on a combined cycle unit waste heat utilization system, which includes a condensate booster pump 1, a TCA 2, an electric heater 3, an FGH 4, a TCA gas-side inlet valve 5, an electric heater inlet valve 6, an electric heater outlet valve 7, an electric heater bypass valve 8, an FGH gas-side inlet temperature control valve 9, an FGH water-side steam drum outlet valve 10, an FGH water-side condenser outlet valve 11, a TCA water-side inlet pipe 12, a TCA water-side outlet pipe 13, an electric heater pipe 14, an FGH water-side outlet pipe 15, a TCA gas-side inlet pipe 16, a TCA gas-side outlet pipe 17, an FGH gas-side inlet pipe 18, an FGH bypass pipe 19, and an FGH gas-side outlet pipe 20. The combined cycle unit waste heat utilization method includes a unit start-up phase and a load operation phase.

[0040] 1) Unit start-up phase

[0041] During unit startup, the gas turbine high-pressure plate is ignited, and condensate booster pump 1 is started to deliver 30°C low-temperature condensate to the water side of TCA2 for heat exchange with the compressor extraction steam. This not only ensures that the TCA2 water-side inlet temperature meets startup requirements, but also allows for condensate flow rate adjustment by regulating the frequency of condensate booster pump 1, ensuring the TCA2 gas-side outlet temperature meets operational requirements. During this process, the compressor extraction steam, cooled by the condensate, is transported to the air turbine through TCA gas-side outlet pipe 17 to cool the turbine blades. Furthermore, due to the low compressor extraction steam temperature during startup, the condensate absorbs limited heat in TCA2, resulting in a low temperature rise. To effectively improve the heating effect of the low-temperature natural gas in FGH4, the electric heater bypass valve 8 is closed, and the electric heater inlet valve 6 and outlet valve 7 are opened. The electric heater 3 is then started to heat the condensate, which in turn heats the natural gas in FGH4. The heated natural gas comes from the natural gas booster station and enters FGH4 through FGH gas-side inlet temperature control valve 9 to absorb heat. The heated natural gas is then transported to the gas turbine for combustion. During this process, the entire flow of natural gas enters FGH4 through FGH gas-side inlet pipe 18. The condensate parameters are low after heat release in FGH4, allowing the FGH water-side condenser outlet valve 11 to be opened and the condensate to be delivered to the condenser.

[0042] 2) Operation under load

[0043] As the gas turbine connects to the grid and begins to operate under load, the compressor's extraction temperature gradually increases. To meet the heat exchange requirements of TCA2 and the cooling air requirements for the blades, the frequency of the condensate booster pump 1 is increased, with the TCA2 outlet temperature as the control target, to increase the condensate flow rate. The cooled compressed air is transported to the air turbine through the TCA gas-side outlet pipe 17 to cool the turbine blades. At this time, because the condensate absorbs heat in TCA2, its temperature rises to meet the heat release requirements of the gas in FGH4. The electric heater bypass valve 8 is gradually opened, the electric heater 3 is closed, and the electric heater inlet valve 6 and outlet valve 7 are gradually closed. The heated condensate then releases heat in FGH4. Similarly, the natural gas that needs to be heated enters FGH4 through the FGH gas-side inlet temperature control valve 9 to absorb heat. Because the water-side heat of FGH4 is relatively large, the temperature rise of the natural gas after being heated in FGH4 is relatively high. To ensure the natural gas entering the gas turbine meets operational requirements, a portion of the low-temperature natural gas is mixed with the high-temperature natural gas from the FGH gas-side outlet pipe 20 via the FGH gas-side inlet temperature control valve 9 and the FGH bypass pipe 19 before entering FGH4, thus achieving the required temperature for unit operation. Due to pressurization by the condensate booster pump 1, the condensate releasing heat in FGH4 has a high pressure and temperature. To fully utilize the condensate parameters, the FGH water-side condenser outlet valve 11 is closed, and the FGH water-side steam drum outlet valve 10 is opened, delivering the condensate to the parameter-matched steam drum for the next stage of thermodynamic cycling.

[0044] Example 4

[0045] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of a combined cycle unit waste heat utilization method. The memory may include main memory, such as high-speed random access memory (RAM), and may also include non-volatile memory, such as at least one disk storage device. The processor, network interface, and memory are interconnected via an internal bus, which may be an industry-standard architecture bus, a peripheral component interconnection standard bus, an extended industry-standard architecture bus, etc. The bus can be categorized as an address bus, data bus, control bus, etc. The memory stores the program; specifically, the program may include program code, which includes computer operation instructions. The memory may include main memory and non-volatile memory, and provides instructions and data to the processor.

[0046] Example 5

[0047] A computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the combined cycle unit waste heat utilization method. Specifically, the computer-readable storage medium includes, but is not limited to, volatile memory and / or non-volatile memory. The volatile memory may include random access memory (RAM) and / or cache memory, etc. The non-volatile memory may include read-only memory (ROM), hard disk, flash memory, optical disk, magnetic disk, etc.

[0048] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0049] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0050] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0051] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0052] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0053] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

[0054] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for waste heat utilization of a combined cycle unit, characterized in that, The combined cycle unit waste heat utilization system comprises a TCA gas side inlet pipeline (16), a TCA (2), a TCA gas side outlet pipeline (17), a TCA water side inlet pipeline (12), a condensate water booster pump (1), a TCA water side outlet pipeline (13), an electric heater bypass valve (8), an FGH4, an FGH water side outlet pipeline (15), an FGH gas side inlet pipeline (18), an FGH gas side inlet temperature control valve (9) and an FGH gas side outlet pipeline (20); The TCA gas side inlet pipeline (16) is in communication with the gas side inlet of the TCA (2), and the gas side outlet of the TCA (2) is in communication with an external turbine through the TCA gas side outlet pipeline (17); The TCA water side inlet pipeline (12) is in communication with the water side inlet of the TCA (2) through the condensate water booster pump (1), the water side outlet of the TCA (2) is in communication with the water side inlet of the FGH (4) through the TCA water side outlet pipeline (13) and the electric heater bypass valve (8), and the water side outlet of the FGH4 is in communication with the FGH water side outlet pipeline (15); The FGH gas side inlet pipeline (18) is in communication with the first opening of the FGH gas side inlet temperature control valve (9), the second opening of the FGH gas side inlet temperature control valve (9) is in communication with the gas side inlet of the FGH (4), the gas side outlet of the FGH (4) is in communication with the FGH gas side outlet pipeline (20), and the third opening of the FGH gas side inlet temperature control valve (9) is in communication with the FGH gas side outlet pipeline (20) through an FGH bypass pipeline (19); The electric heater bypass valve (8) is in parallel with a post-electric heater pipeline (14); An electric heater inlet valve (6), an electric heater (3) and an electric heater outlet valve (7) are sequentially arranged on the electric heater pipeline (14); The combined cycle unit waste heat utilization system comprises a unit starting stage and a load running stage; In the unit starting stage, the condensate water booster pump (1) is started, low-temperature condensate water is sent to the water side of the TCA (2), heat exchange is performed with the steam extraction of the compressor, the frequency of the condensate water booster pump (1) is adjusted to adjust the condensate water flow, so that the gas side outlet temperature of the TCA (2) meets the operation requirement, in the process, the steam extraction of the compressor cooled by the condensate water is transported to the air turbine through the TCA gas side outlet pipeline (17) to cool the turbine blade, at the same time, the electric heater bypass valve (8) is closed, the electric heater inlet valve (6) and the electric heater outlet valve (7) are opened, the electric heater (3) is started, the condensate water output by the TCA (2) is heated by the electric heater (3) and then enters the FGH4 to heat the natural gas, the natural gas enters the FGH (4) through the FGH gas side inlet temperature control valve (9) to absorb heat, and the heated natural gas is transported to the gas turbine for combustion; In the load operation stage, the frequency of the condensate booster pump (1) is increased to increase the condensate flow with the outlet temperature of the TCA (2) as the control target, and the compressed air is delivered to the air turbine cooling turbine blades through the TCA gas side outlet pipeline (17). At the same time, the electric heater bypass valve (8) is gradually opened, the electric heater (3) is closed, the electric heater inlet valve (6) and the electric heater outlet valve (7) are gradually closed, the warmed condensate is cooled in the FGH (4), and the natural gas is divided into two paths, one of which enters the FGH (4) through the FGH gas side inlet temperature control valve (9) to absorb heat, and then enters the FGH gas side outlet pipeline (20), and the other path is mixed with the high-temperature natural gas in the FGH gas side outlet pipeline (20) through the FGH bypass pipeline (19), so that the temperature meets the unit operation requirement.

2. The method according to claim 1, wherein, The TCA gas side inlet pipeline (16) is connected to the gas side inlet of the TCA (2) through the TCA gas side inlet valve (5).

3. The method of claim 1, wherein, It also includes the FGH water side steam drum outlet valve (10) and the FGH water side condenser outlet valve (11), and the water side outlet of the FGH (4) is connected to the FGH water side steam drum outlet valve (10) and the FGH water side condenser outlet valve (11) through the FGH water side outlet pipeline (15).

4. The method of claim 1, wherein, The TCA gas side inlet pipeline (16) is connected to the gas side inlet of the TCA (2) through the TCA gas side inlet valve (5).

5. The method of claim 1, wherein, It also includes the FGH water side steam drum outlet valve (10) and the FGH water side condenser outlet valve (11), and the water side outlet of the FGH (4) is connected to the FGH water side steam drum outlet valve (10) and the FGH water side condenser outlet valve (11) through the FGH water side outlet pipeline (15).

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