A natural gas power plant fuel supply system and method

Abstract

The present invention discloses a fuel supply system and method for a natural gas power plant, the system includes a heater, a start-up boiler, a waste heat boiler, a gas turbine and a steam turbine; the inlet, the first outlet and the second outlet of the start-up boiler are respectively connected to the heater; the inlet of the gas turbine is connected to the heater, and the outlet is connected to the inlet of the waste heat boiler; the first outlet of the waste heat boiler is connected to the steam turbine, and the second outlet and the third outlet are respectively connected to the heater; the method includes a preheating start mode, a linkage start mode, a linkage preheating mode and a linkage heating mode. The present invention greatly reduces energy costs, fully considers the use of waste heat and steam as heat media, and reduces the cost of heating energy consumption in the prior art; and directly controls the temperature of the natural gas after depressurization before entering the gas turbine, avoiding the problem of temperature deviation caused by heating first and then depressurizing in the prior art, and providing temperature control accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas power plants, and in particular to a fuel supply system and method for natural gas power plants. Background Art

[0002] The gas supply system of a natural gas power plant is a typical high-pressure difference and large-flow application scenario. The high pressure difference is caused by the internal pressure regulating system reducing the pressure of the high-pressure gas, resulting in a huge pressure difference before and after the system, and thus a huge natural gas temperature drop. The gas turbine has strict requirements on the natural gas temperature, so a series of heating and temperature control are required for the natural gas after the pressure reduction.

[0003] At present, the existing technology usually electrically heats or heat-exchanges the gas source before the pressure regulating system reduces the pressure; however, there is an upper limit problem of the operating temperature of the equipment for heating or heat-exchanging natural gas before reducing the pressure. For example, the operating temperature of key equipment such as the pressure regulator and the safety shut-off valve is below 60°C, so the temperature of the gas source after heating cannot exceed 60°C, resulting in a low temperature at the low-pressure end after a huge pressure drop, and the temperature drop caused by the pressure reduction will cause a secondary change in the natural gas temperature. Its instability cannot accurately control the temperature of the natural gas entering the gas turbine, thereby affecting the operation of the gas turbine. Summary of the invention

[0004] The purpose of the present invention is to provide a natural gas power plant fuel supply system and method, aiming to significantly reduce energy costs, fully consider the use of waste heat and steam as heat medium, and reduce the cost of heating energy consumption in the prior art.

[0005] The embodiments of the present invention are implemented by the following technical solutions:

[0006] In one aspect, the present invention discloses a fuel supply system for a natural gas power plant, comprising a heater, a startup boiler, a waste heat boiler, a gas turbine and a steam turbine;

[0007] The inlet, the first outlet and the second outlet of the startup boiler are respectively connected to the heater; the inlet of the gas turbine is connected to the heater, and the outlet is connected to the inlet of the waste heat boiler; the first outlet of the waste heat boiler is connected to the steam turbine, and the second outlet and the third outlet are respectively connected to the heater.

[0008] In a further technical solution, the heater includes a steam portion, a circulating water portion and a natural gas portion;

[0009] The steam part has a first pipeline arranged in the circulating water part, the circulating water part has a second pipeline arranged in the natural gas part, the liquid in the circulating water part can circulate inside, and the natural gas part has a heating element;

[0010] The inlet of the startup boiler is connected to the natural gas part, the first outlet is connected to the steam part, and the second outlet is connected to the circulating water part;

[0011] The inlet of the gas turbine is connected to the natural gas portion;

[0012] The second outlet of the waste heat boiler is connected to the steam part, and the third outlet is connected to the circulating water part.

[0013] In a further technical solution, a first temperature threshold is set, and when the temperature of the natural gas in the natural gas portion is lower than the first temperature threshold, the heating element is started, the inlet of the start-up boiler is connected to the natural gas portion, and the inlet of the gas turbine is cut off from the natural gas portion;

[0014] When the temperature of the natural gas in the natural gas portion reaches the first temperature threshold, the heating element is turned off, the inlet of the startup boiler is disconnected from the natural gas portion, and the inlet of the gas turbine is connected to the natural gas portion.

[0015] In a further technical solution, a liquid level threshold is set, and when the water level in the circulating water portion reaches the liquid level threshold, the second outlet of the startup boiler and the second outlet of the waste heat boiler are cut off from the circulating water portion;

[0016] When the water level in the circulating water portion is lower than the liquid level threshold, the second outlet of the startup boiler and the second outlet of the waste heat boiler are communicated with the circulating water portion.

[0017] In a further technical solution, a second temperature threshold is set, and when the temperature in the circulating water portion reaches the second temperature threshold, the liquid in the circulating water portion circulates in the circulating water portion;

[0018] When the temperature in the circulating water portion is lower than the second temperature threshold, the liquid in the circulating water portion is stationary.

[0019] In a further technical solution, the heater, the start-up boiler, the waste heat boiler, the gas turbine and the steam turbine are respectively connected through a plurality of third pipelines, and valves are respectively provided on the plurality of third pipelines.

[0020] In a further technical solution, the first outlet of the startup boiler and the second outlet of the waste heat boiler are connected in parallel and then connected to the heater; the second outlet of the startup boiler and the third outlet of the waste heat boiler are connected in parallel and then connected to the heater.

[0021] In a further technical solution, the opening and closing of the valve can be remotely controlled.

[0022] In a further technical solution, a generator is also included, and the output end of the steam turbine is connected to the generator.

[0023] On the other hand, the present invention also discloses a natural gas power plant fuel supply method, which is applied to the above natural gas power plant fuel supply system and comprises the following steps:

[0024] Low-temperature natural gas enters the natural gas section, and the heating element heats the natural gas; when the temperature of the natural gas reaches the preset value, it enters the start-up boiler;

[0025] The liquid generated by starting the boiler to burn natural gas enters the circulating water part, and the gas generated by starting the boiler to burn natural gas enters the steam part, and heats the liquid in the circulating water part through the first pipeline;

[0026] When the temperature of the liquid in the circulating water portion reaches a preset value, the liquid in the circulating water portion heats the natural gas in the natural gas portion through the second pipeline, then returns to the circulating water portion, and circulates in the circulating water portion;

[0027] When the temperature of the natural gas in the natural gas part reaches the preset value, the boiler and the heating element are started and stopped, and the natural gas enters the gas turbine, generating a large amount of flue gas which is then passed into the waste heat boiler; part of the gas generated by the waste heat boiler is provided to the steam turbine, and the other part of the gas enters the incoming gas area, and the liquid generated by the waste heat boiler is passed to the circulating water part.

[0028] The technical solution of the embodiment of the present invention has at least the following advantages and beneficial effects:

[0029] 1. Fully consider the use of waste heat and steam as heat medium to reduce the cost of heating energy consumption in existing technologies; and directly control the temperature of the natural gas after decompression before entering the gas turbine, avoiding the problem of temperature deviation caused by heating first and then decompression in the existing technology, and improving temperature control accuracy;

[0030] 2. Through the setting of the heater, the multi-heat medium linkage function is completed in one device, reducing the equipment cost;

[0031] 3. Through the control of multi-heat medium linkage, it can respond to and take into account the natural gas temperature requirements of the entire process of gas turbine startup, medium load, and high load. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of the present invention;

[0033] Figure 2 is a schematic diagram of the structure of the heater;

[0034] Figure 3 This is the schematic diagram of the preheating startup mode;

[0035] Figure 4 This is the schematic diagram of the linkage startup mode;

[0036] Figure 5 This is the schematic diagram of the linkage preheating mode;

[0037] Figure 6 This is the schematic diagram of the linkage heating mode.

[0038] Icons: 1-heater, 11-incoming gas area, 12-recovery area, 13-first pipeline, 14-water heating area, 15-return water area, 16-second pipeline, 17-gas heating area, 18-heating element, 2-start-up boiler, 3-gas turbine, 4-waste heat boiler, 5-steam turbine, 6-third pipeline;

[0039] EV101, EV102, EV201, EV301, EV302, EV303, EV401, EV402 - valve;

[0040] R1-water pump;

[0041] A1-gas inlet, A2-gas outlet, B1-water inlet, B2-water outlet, C-natural gas inlet, D1, D2-natural gas outlet;

[0042] A0-a-the first outlet of the startup boiler, B0-a-the second outlet of the startup boiler, A0-b-the second outlet of the waste heat boiler, B0-b-the third outlet of the waste heat boiler. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0044] 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 invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] It should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying importance. They are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0046] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it 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 it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] In the description of the present invention, “plurality” means two or more than two, unless otherwise clearly and specifically defined.

[0048] Embodiment 1:

[0049] like Figure 1 As shown, the inlet of the startup boiler 2, the first outlet A0-a of the startup boiler and the second outlet B0-a of the startup boiler are respectively connected to the heater 1; the inlet of the gas turbine 3 is connected to the heater 1, and the outlet is connected to the inlet of the waste heat boiler 4; the first outlet of the waste heat boiler is connected to the steam turbine 5, and the second outlet A0-b of the waste heat boiler and the third outlet B0-b of the waste heat boiler are respectively connected to the heater 1.

[0050] Specifically, Figure 1 As shown, the heater 1 includes a steam part, a circulating water part and a natural gas part, the steam part has a first pipe 13 arranged in the circulating water part, the circulating water part has a second pipe 16 arranged in the natural gas part, the liquid in the circulating water part can circulate internally, and the natural gas part has a heating element 18; the inlet of the starting boiler 2 is connected to the natural gas part, the first outlet A0-a of the starting boiler is connected to the steam part, and the second outlet B0-a of the starting boiler is connected to the circulating water part; the inlet of the gas turbine 3 is connected to the natural gas part; the second outlet A0-b of the waste heat boiler is connected to the steam part, and the third outlet B0-b of the waste heat boiler is connected to the circulating water part.

[0051] It also includes a generator. The outlet of the steam turbine 5 is connected to the generator. The generator converts the mechanical energy generated by the steam turbine 5 into electrical energy to realize power generation of the natural gas power plant.

[0052] After the low-temperature natural gas enters the natural gas part, the heating element 18 heats the low-temperature natural gas in the natural gas part and enters the startup boiler 2. The liquid generated by the combustion of natural gas in the startup boiler 2 enters the circulating water part, and the generated gas enters the steam part, and heats the liquid in the circulating water part through the first pipeline 13; when the temperature of the liquid in the circulating water part reaches a preset value, the liquid in the circulating water part heats the natural gas in the natural gas part through the second pipeline 16, and then returns to the circulating water part and circulates in the circulating water part; when the temperature of the natural gas in the natural gas part reaches a preset value, the startup boiler 2 and the heating element 18 stop working, the natural gas enters the gas turbine 3, generates a large amount of flue gas and passes into the waste heat boiler 4; most of the gas generated by the waste heat boiler 4 is provided to the steam turbine 5, and a small part of the gas enters the incoming gas area 11, and the liquid generated by the waste heat boiler 4 passes into the circulating water part.

[0053] like Figure 1 As shown, the heater 1, the starting boiler 2, the waste heat boiler 4, the gas turbine 3 and the steam turbine 5 are respectively connected through a plurality of third pipelines 6, and valves are respectively provided on the plurality of third pipelines 6; the connection and closing of each component can be controlled by the valve, so as to better control the flow of liquid and gas.

[0054] In this embodiment, the first outlet A0-a of the starting boiler and the second outlet A0-b of the waste heat boiler are connected in parallel to the steam part of the heater 1; the third outlet B0-b of the waste heat boiler and the second outlet B0-a of the starting boiler are connected in parallel to the circulating water part of the heater 1; by connecting in parallel, only one interface is required for the steam part and the circulating water part, which can reduce the manufacturing cost of the heater 1.

[0055] The working principle of this embodiment is as follows:

[0056] Preheat start mode, such as Figure 3 As shown, after the natural gas enters the natural gas part, the heating element 18 heats the low-temperature natural gas in the natural gas part and enters the start-up boiler 2. The amount of natural gas required for the start-up boiler 2 is small, and the flow rate is Qmin; the hot water generated by the combustion of natural gas by the start-up boiler 2 enters the circulating water part until the liquid level threshold. After reaching the liquid level threshold, the third outlet B0-b of the waste heat boiler and the second outlet A0-b of the waste heat boiler are cut off from the circulating water part.

[0057] Linkage startup mode, such as Figure 4As shown, after the third outlet B0-b of the waste heat boiler and the second outlet A0-b of the waste heat boiler are cut off from the circulating water part, the steam generated by burning natural gas in the start-up boiler 2 enters the steam part, and the steam transfers heat to the water medium in the circulating water part through the first pipe 13; since the heating rate of water is increased, the start-up boiler 2 will increase the natural gas consumption to increase the steam generation; at this time, the natural gas flow rate is Q1, Q1>Qmin.

[0058] Linked preheating mode, such as Figure 5 As shown, when the temperature of the liquid in the circulating water portion reaches the second temperature threshold, the liquid in the circulating water portion circulates within itself, and the liquid also flows through the natural gas portion through the second pipeline 16 to heat the natural gas in the natural gas portion.

[0059] Linked heating mode, such as Figure 6 As shown, when the natural gas in the natural gas part reaches the first temperature threshold, the heating element 18 is turned off, the inlet of the start-up boiler 2 is cut off from the natural gas part, the inlet of the gas turbine 3 is connected to the natural gas part, and the natural gas enters the gas turbine 3, generating a large amount of high-temperature flue gas and passing into the waste heat boiler 4; at this time, the gas turbine 3 is running at high load, and the flow rate of natural gas is Qmax; the waste heat boiler 4 uses the high-temperature flue gas to generate a large amount of steam and waste hot water, most of the steam is provided to the steam turbine 5 for power generation of the generator, and a small amount of steam enters the steam part; in the linkage heating mode, the steam of the heater 1 all comes from the waste heat boiler 4; when the water level in the water heating area 14 drops, the second outlet A0-b of the waste heat boiler is connected to the circulating water part, and the waste hot water in the waste heat boiler 4 enters the circulating water part to replenish the water circulating water part.

[0060] In the whole process, the heating element 18 is only used briefly at the initial stage of startup, and a small amount of natural gas is used by the startup boiler 2 in the preheating startup mode. In addition, the natural gas power plant fuel supply system of this embodiment no longer consumes external energy during operation, which greatly reduces energy costs, fully considers the use of waste heat and steam as heat media, and reduces the cost of heating energy consumption in the prior art; and directly controls the temperature of the natural gas after decompression before entering the gas turbine 3, avoiding the problem of temperature deviation caused by heating first and then decompressing in the prior art, and providing temperature control accuracy.

[0061] Embodiment 2:

[0062] This embodiment is improved on the basis of embodiment 2. Figure 2 As shown, the heater 1 includes a steam part, a circulating water part and a natural gas part; the steam part includes a gas incoming area 11, a recovery area 12 and a first pipeline 13; the circulating water part includes a water heating area 14, a return water area 15 and a second pipeline 16; the natural gas part includes a gas heating area 17 and a heating element 18;

[0063] One end of the first pipe 13 is connected to the incoming gas area 11, and the other end is connected to the recovery area 12 through the water heating area 14; one end of the second pipe 16 is connected to the water heating area 14, and the other end is connected to the return water area 15 through the gas heating area 17, and the return water area 15 is also connected to the water heating area 14; the heating element 18 is arranged in the gas heating area 17.

[0064] The gas incoming area 11 has a gas inlet A1, and the recovery area 12 has a gas outlet A2, and the gas flows in the direction of gas inlet A1-gas incoming area 11-first pipeline 13-recovery area 12-gas outlet A2; the water heating area 14 has a water inlet B1, and the return water area 15 has a water outlet B2, and the liquid flows in the direction of water inlet B1-water heating area 14-second pipeline 16-return water area 15-water outlet B2-water inlet B1; the gas heating area 17 has a natural gas inlet C, a natural gas outlet D1 and a natural gas outlet D2, and the natural gas flows in the direction of natural gas inlet C-gas heating area 17-natural gas outlet D1 and / or natural gas outlet D2.

[0065] The air incoming area 11 has a safety valve to avoid safety accidents caused by excessive pressure in the air incoming area 11. The recovery area 12 has a sewage outlet to facilitate the discharge of impurities in the recovery area 12; the water heating area 14 also has a sewage outlet to facilitate the discharge of circulating water in the water heating area 14.

[0066] The first pipe 13 is preferably a plurality of U-shaped tube bundles to increase the length of the first pipe 13, thereby increasing the residence time of the gas in the water heating area 14 and the area of ​​heat exchange with the water heating area 14, thereby improving the heat exchange efficiency; the second pipe 16 is also preferably a plurality of U-shaped tube bundles to increase the length of the second pipe 16, thereby increasing the residence time of the liquid in the gas heating area 17 and the area of ​​heat exchange with the gas heating area 17, thereby improving the heat exchange efficiency.

[0067] The heating element 18 is preferably electric heating, which has the advantages of simple structure, convenient control, cleanliness, environmental protection, safety and reliability, and can well meet the demand for preliminary heating of natural gas in the gas heating area 17.

[0068] In this embodiment, the heater 1 has a shell, and three partitions are arranged axially in the shell to divide the shell into a first chamber, a second chamber, a third chamber and a fourth chamber. A partition is also provided in the first chamber to divide the first chamber into an upper chamber and a lower chamber; the upper chamber is an incoming air area 11, the lower chamber is a recovery area 12, the second chamber is a water heating area 14, the third chamber is a return water area 15, and the fourth chamber is a gas heating area 17; the first pipe 13 is located in the water heating area 14, and its two ends pass through the partition to communicate with the incoming air area 11 and the recovery area 12 respectively; the second pipe 16 is located in the return water area 15 and the gas heating area 17, one end passes through the partition to communicate with the water heating area 14, and the other end passes through the partition to communicate with the return water area 15.

[0069] To meet usage requirements, the volumes of the incoming gas area 11 and the recovery area 12 are equal, the volume of the water heating area 14 is larger than the volume of the return water area 15, and the volume of the gas heating area 17 is the largest, which is larger than the volumes of the incoming gas area 11, the recovery area 12, the water heating area 14 and the return water area 15.

[0070] It should be noted that there can be many layouts of the incoming gas area 11, the recovery area 12, the water heating area 14, the return water area 15 and the gas heating area 17. The layout scheme provided in this embodiment is one of them and can be flexibly set according to needs.

[0071] like Figure 1 and Figure 2 As shown, the inlet of the startup boiler 2 is connected to the natural gas outlet D1 of the gas heating area 17 through the third pipeline 6 and the valve EV101, the first outlet A0-a of the startup boiler is connected to the gas inlet A1 of the gas incoming area 11 through the third pipeline 6 and the valve EV401, and the third outlet B0-b of the waste heat boiler is connected to the water inlet B1 of the water heating area 14 through the third pipeline 6, the valve EV302 and the valve EV301; the inlet of the gas turbine 3 is connected to the natural gas outlet D1 of the gas heating area 17 through the third pipeline 6 and the valve EV102. The gas outlet D2 is connected, the outlet of the gas turbine 3 is connected to the inlet of the waste heat boiler 4 through the third pipeline 6, the first outlet of the waste heat boiler is connected to the steam turbine 5 through the third pipeline 6, the second outlet is connected to the gas inlet A1 of the incoming gas area 11 through the third pipeline 6 and the valve EV402, and the third outlet is connected to the water inlet B1 of the water heating area 14 through the third pipeline 6 and the valve EV303; the water outlet B2 of the return water area 15 is connected to the water inlet B1 of the water heating area 14 through the third pipeline 6, the water pump R1 and the valve EV201.

[0072] In this embodiment, the gas incoming area 11 is provided with a pressure sensor, the water heating area 14 is provided with a liquid level sensor and a temperature sensor, and the gas heating area 17 is provided with a temperature sensor and a pressure sensor, so as to monitor various data of the heater 1 in real time.

[0073] When a power plant uses LNG as a gas source, the requirements for heating equipment will be higher, because the temperature of LNG in liquid state is about -160°C, and the gasification process usually uses an air-temperature heat exchanger or heater 1, and the temperature of the gasified natural gas is usually relatively low; the heating effect of the air-temperature heat exchanger is greatly affected by the ambient temperature, and the insufficient heating is particularly obvious in winter; if the heater 1 is used to gasify LNG, the LNG at about -160°C will be gasified when it is heated to about -150°C. As the heating temperature increases, the amount of gasification increases. The volume ratio of liquid LNG to gaseous natural gas is about 1:600. Once overheated, the gas will expand and the gas pressure will increase, which is very difficult to control.

[0074] In combination with the natural gas power plant fuel supply system of the present invention, the LNG gas source only needs to be simply heated by an air temperature vaporizer as long as the gasification amount is guaranteed; even if the temperature of the natural gas after gasification is low, passing through the natural gas power plant fuel supply system can ensure that the temperature of the natural gas finally entering the gas turbine 3 is within the required control range.

[0075] The working principle of this embodiment is:

[0076] Preheat start mode, such as Figure 3 As shown, natural gas enters the gas heating area 17 from the natural gas inlet C, the heating element 18 works, the valve EV101 is opened, and the natural gas enters the start-up boiler 2. The amount of natural gas required for the start-up boiler 2 is small, and the flow rate is Qmin; the start-up boiler 2 passes the hot water generated by the combustion of natural gas into the water heating area 14 along the third outlet B0-b of the waste heat boiler-the water inlet B1 of the water heating area 14 and fills it; after reaching the upper limit of the liquid level, the valve EV301 and the valve EV302 are closed.

[0077] Linkage startup mode, such as Figure 4 As shown, after valve EV301 and valve EV302 are closed, the starting boiler 2 allows the steam generated by the combustion of natural gas to enter the gas incoming area 11 along the first outlet A0-a of the starting boiler-the gas inlet A1 of the gas incoming area 11, and enter the recovery area 12 through the first pipe 13, and then be discharged from the gas outlet A2 of the recovery area 12; the steam transfers heat to the water medium in the water heating area 14 through the first pipe 13; since the heating rate of water is increased, the starting boiler 2 will increase the natural gas consumption to increase the steam generation; at this time, the natural gas flow rate is Q1, Q1>Qmin.

[0078] Linked preheating mode, such as Figure 5As shown, when the hot water temperature in the water heating area 14 reaches the preset value, the valve EV201 is opened, the water pump R1 works, and the hot water in the circulating water part flows and circulates along the direction of the water heating area 14-the second pipe 16-the return water area 15-the water heating area 14; the hot water heats the natural gas in the gas heating area 17 through the second pipe 16.

[0079] Linked heating mode, such as Figure 6 As shown, natural gas enters from port C. When the natural gas temperature in the gas heating area 17 reaches a usable state, the electric valve EV102 is opened, and the natural gas enters the gas turbine 3 through the natural gas outlet D2 of the gas heating area 17. The natural gas generates a large amount of high-temperature flue gas in the gas turbine 3 and passes into the waste heat boiler 4. At this time, the gas turbine 3 operates at a high load, and the flow rate of the natural gas is Qmax. The waste heat boiler 4 uses the high-temperature flue gas to generate a large amount of steam and waste hot water, most of which is provided to the steam turbine 5 for power generation. The valve EV402 is opened, and a small part of the steam flows along the waste heat boiler The second outlet A0-b is directed toward the gas inlet A1 of the air incoming area 11; at the same time, valve EV101 and valve EV401 are closed, and the starter boiler 2 and the heating element 18 are stopped; in the linkage heating mode, all the steam of the heater 1 comes from the waste heat boiler 4; when the water level in the water heating area 14 drops, valve EV303 and valve EV301 are opened, and the waste hot water enters the water heating area 14 along the third outlet B0-b of the waste heat boiler toward the water inlet B1 of the water heating area 14 to replenish the water inlet B1 of the water heating area 14.

[0080] The other parts of this embodiment are the same as those of the above-mentioned embodiment 1, and thus will not be described in detail.

[0081] Embodiment 3:

[0082] A natural gas power plant fuel supply method, applied to the natural gas power plant fuel supply system in Example 2, comprises the following steps:

[0083] 100. Low-temperature natural gas enters the natural gas section, and the heating element 18 heats the natural gas; when the temperature of the natural gas reaches a preset value, it enters the startup boiler 2;

[0084] 200. The liquid generated by starting the boiler 2 to burn natural gas enters the circulating water part, and the gas generated by starting the boiler 2 to burn natural gas enters the steam part, and heats the liquid in the circulating water part through the first pipeline 13;

[0085] 300. When the temperature of the liquid in the circulating water portion reaches a preset value, the liquid in the circulating water portion heats the natural gas in the natural gas portion through the second pipeline 16, and then returns to the circulating water portion and circulates in the circulating water portion;

[0086] 400. When the temperature of the natural gas in the natural gas part reaches the preset value, the boiler 2 is started and the heating element 18 stops working, and the natural gas enters the gas turbine 3, generates a large amount of flue gas and is passed into the waste heat boiler 4; most of the gas generated by the waste heat boiler 4 is provided to the steam turbine 5, and a small part of the gas enters the gas supply area 11, and the liquid generated by the waste heat boiler 4 is passed to the circulating water part.

[0087] Step 100 is a preheating start mode, such as Figure 3 As shown, natural gas enters the gas heating area 17 from the natural gas inlet C, the heating element 18 works, the valve EV101 is opened, and the natural gas enters the start-up boiler 2. The amount of natural gas required for the start-up boiler 2 is small, and the flow rate is Qmin; the start-up boiler 2 passes the hot water generated by the combustion of natural gas into the water heating area 14 along the third outlet B0-b of the waste heat boiler-the water inlet B1 of the water heating area 14 and fills it; after reaching the upper limit of the liquid level, the valve EV301 and the valve EV302 are closed.

[0088] Step 200 is the linkage start mode, such as Figure 4 As shown, after valve EV301 and valve EV302 are closed, the starting boiler 2 allows the steam generated by the combustion of natural gas to enter the gas incoming area 11 along the first outlet A0-a of the starting boiler-the gas inlet A1 of the gas incoming area 11, and enter the recovery area 12 through the first pipe 13, and then be discharged from the gas outlet A2 of the recovery area 12; the steam transfers heat to the water medium in the water heating area 14 through the first pipe 13; since the heating rate of water is increased, the starting boiler 2 will increase the natural gas consumption to increase the steam generation; at this time, the natural gas flow rate is Q1, Q1>Qmin.

[0089] Step 300 is a linkage preheating mode, such as Figure 5 As shown, when the hot water temperature in the water heating area 14 reaches the preset value, the valve EV201 is opened, the water pump R1 works, and the hot water in the circulating water part flows and circulates along the direction of the water heating area 14-the second pipe 16-the return water area 15-the water heating area 14; the hot water heats the natural gas in the gas heating area 17 through the second pipe 16.

[0090] Step 400 is a linkage heating mode, such as Figure 6As shown, when the temperature of the natural gas in the gas heating area 17 reaches a usable state, the electric valve EV102 is opened, and the natural gas enters the gas turbine 3 through the natural gas outlet of the gas heating area 17. The natural gas generates a large amount of high-temperature flue gas in the gas turbine 3 and passes into the waste heat boiler 4; at this time, the gas turbine 3 operates at a high load, and the flow rate of the natural gas is Qmax; the waste heat boiler 4 uses the high-temperature flue gas to generate a large amount of steam and waste hot water, most of which is provided to the steam turbine 5 for power generation, and the valve EV402 is opened, and a small part of the steam is discharged along the second outlet A of the waste heat boiler. 0-b-the direction of the gas inlet A1 of the air incoming area 11 is entered into the air incoming area 11; at the same time, valve EV101 and valve EV401 are closed, and the starter boiler 2 and the heating element 18 are stopped; in the linkage heating mode, the steam of the heater 1 all comes from the waste heat boiler 4; when the water level in the water heating area 14 drops, valve EV303 and valve EV301 are opened, and the waste hot water enters the water heating area 14 along the third outlet B0-b-of the waste heat boiler in the direction of the water inlet B1 of the water heating area 14, and the water heating area 14 is replenished with water.

[0091] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A natural gas power plant fuel supply system, characterized in that: Including heaters, start-up boilers, waste heat boilers, gas turbines and steam turbines; The inlet, the first outlet and the second outlet of the startup boiler are respectively connected to the heater; the inlet of the gas turbine is connected to the heater, and the outlet is connected to the inlet of the waste heat boiler; the first outlet of the waste heat boiler is connected to the steam turbine, and the second outlet and the third outlet are respectively connected to the heater; The heater includes a steam part, a circulating water part and a natural gas part; The steam part has a first pipeline arranged in the circulating water part, the circulating water part has a second pipeline arranged in the natural gas part, the liquid in the circulating water part can circulate inside, and the natural gas part has a heating element; The inlet of the startup boiler is connected to the natural gas part, the first outlet is connected to the steam part, and the second outlet is connected to the circulating water part; The inlet of the gas turbine is connected to the natural gas portion; The second outlet of the waste heat boiler is connected to the steam part, and the third outlet is connected to the circulating water part.

2. A natural gas power plant fuel supply system according to claim 1, characterized in that: A first temperature threshold is set, and when the temperature of the natural gas in the natural gas portion is lower than the first temperature threshold, the heating element is started, the inlet of the start-up boiler is connected to the natural gas portion, and the inlet of the gas turbine is cut off from the natural gas portion; When the temperature of the natural gas in the natural gas portion reaches the first temperature threshold, the heating element is turned off, the inlet of the startup boiler is disconnected from the natural gas portion, and the inlet of the gas turbine is connected to the natural gas portion.

3. A natural gas power plant fuel supply system according to claim 1, characterized in that: Setting a liquid level threshold, when the water level in the circulating water portion reaches the liquid level threshold, the second outlet of the startup boiler and the second outlet of the waste heat boiler are cut off from the circulating water portion; When the water level in the circulating water portion is lower than the liquid level threshold, the second outlet of the startup boiler and the second outlet of the waste heat boiler are communicated with the circulating water portion.

4. A natural gas power plant fuel supply system according to claim 1, characterized in that: Setting a second temperature threshold, when the temperature in the circulating water portion reaches the second temperature threshold, the liquid in the circulating water portion circulates in the circulating water portion; When the temperature in the circulating water portion is lower than the second temperature threshold, the liquid in the circulating water portion is stationary.

5. A natural gas power plant fuel supply system according to claim 1, characterized in that: The heater, the start-up boiler, the waste heat boiler, the gas turbine and the steam turbine are connected respectively through a plurality of third pipelines, and valves are respectively arranged on the plurality of third pipelines.

6. A natural gas power plant fuel supply system according to claim 5, characterized in that: The first outlet of the startup boiler and the second outlet of the waste heat boiler are connected in parallel and then connected to the heater; the second outlet of the startup boiler and the third outlet of the waste heat boiler are connected in parallel and then connected to the heater.

7. A natural gas power plant fuel supply system according to claim 5, characterized in that: The opening and closing of the valve can be remotely controlled.

8. A natural gas power plant fuel supply system according to claim 1, characterized in that: A generator is also included, and the output end of the steam turbine is connected to the generator.

9. A method for supplying fuel to a natural gas power plant, characterized in that: The natural gas power plant fuel supply system applied to any one of claims 1 to 8 comprises the following steps: Low-temperature natural gas enters the natural gas section, and the heating element heats the natural gas; when the temperature of the natural gas reaches the preset value, it enters the start-up boiler; The liquid generated by starting the boiler to burn natural gas enters the circulating water part, and the gas generated by starting the boiler to burn natural gas enters the steam part, and heats the liquid in the circulating water part through the first pipeline; When the temperature of the liquid in the circulating water portion reaches a preset value, the liquid in the circulating water portion heats the natural gas in the natural gas portion through the second pipeline, then returns to the circulating water portion, and circulates in the circulating water portion; When the temperature of the natural gas in the natural gas part reaches the preset value, the boiler and the heating element are started and stopped, and the natural gas enters the gas turbine, generating a large amount of flue gas which is then passed into the waste heat boiler; part of the gas generated by the waste heat boiler is provided to the steam turbine, and the other part of the gas enters the incoming gas area, and the liquid generated by the waste heat boiler is passed to the circulating water part.

Images