Natural gas dew point heating system for gas-steam combined cycle power plant

Abstract

The utility model relates to a natural gas dew point heating system for a gas-steam combined cycle power plant. The natural gas dew point heating system comprises a dew point heater, a circulating cooling water side system and a natural gas side system. The circulating cooling water side system comprises a booster pump water inlet pipeline and a water return pipeline; and a first stop valve, an electric control valve, a second stop valve and a third stop valve are arranged on the water return pipeline. The booster pump water inlet pipeline comprises a booster pump, a filter and a fourth stop valve; and a check valve and an electric shut-off valve are arranged between the water outlet of the booster pump and the water inlet of the dew point heater. The natural gas side system comprises a starting electric heater, a first manual ball valve, a second manual ball valve, a third manual ball valve, a fourth manual ball valve, a fifth manual ball valve and a sixth manual ball valve. According to the utility model, the waste heat of the returned circulating cooling water in a plant can be fully utilized, the comprehensive utilization of the waste heat is realized, meanwhile, the power consumption of the circulating cooling water pump and the mechanical cooling tower of the circulating cooling water system is reduced, and the plant power is saved.

Description

Technical Field

[0001] The utility model relates to the technical field of energy saving and consumption reduction of gas turbine power generation, and in particular to a natural gas dew point heating system for a gas-steam combined cycle power plant which utilizes waste heat of circulating cooling water in the plant. Background Art

[0002] The prime mover of a gas-steam combined cycle power plant is a gas turbine, and the fuel is generally natural gas. In order to increase the energy density of the gas turbine, there are usually certain pressure requirements for the natural gas entering the gas turbine. Taking a certain project as an example, the gas turbine is H-class, and the required natural gas pressure at the burner inlet of the gas turbine is 4.8-5.0MPa. At the same time, the gas turbine has certain superheat requirements for natural gas. If the natural gas temperature is too low, the water in the natural gas will be cooled into droplets, causing damage to the blades of the gas turbine. Taking the above project as an example, the superheat of natural gas during cold start is 11-60℃ higher than the water dew point.

[0003] The natural gas supply process is: natural gas delivery point outside the factory-natural gas pressure regulating station inside the factory-gas turbine front module-gas turbine fuel module. Among them, the core equipment is the natural gas pressure regulating station, which realizes functions such as emergency shutdown, metering, separation and filtration, heating, pressure reduction or pressurization, and finally ensures that the natural gas enters the gas turbine with qualified quality (certain pressure, temperature, calorific value, and no solid or liquid impurities). If the pressure of natural gas outside the factory is too high, it needs to be reduced in pressure. Due to the existence of Joule-Thomson effect, the temperature will decrease during pressure reduction. According to experience, if the natural gas pressure decreases by 0.1MPa, the corresponding temperature will decrease by about 0.4℃. If the temperature of the natural gas outside the factory cannot meet the superheat requirement after pressure reduction, heating measures need to be taken, that is, a heater is set in the pressure regulating station. This heater is usually called a dew point heater.

[0004] Taking the above project as an example, the guaranteed pressure of the natural gas delivery point outside the factory is 5.8MPa, the temperature range is 5-15℃, the water dew point of natural gas is 4.5℃ at 6.3MPa, and the natural gas is reduced to 5.0MPa through the pressure regulating station. The temperature drop caused by the pressure drop is about 2.8℃. If no dew point heater is installed, the temperature at the outlet of the pressure regulating station is 2.2-12.2℃. The natural gas temperature requirement when the gas turbine is started is 14.5-64.5℃. The natural gas temperature is too low to meet the gas turbine startup requirements, so a dew point heater is required. Taking into account a certain temperature margin, the dew point heater heats the natural gas to at least 20℃.

[0005] Combined with the thermal system of the gas-steam combined cycle power plant, considering energy saving and cascade utilization of heat, the current natural gas dew point heating system usually has the following configuration methods:

[0006] Solution 1: Setting up an electric heater: Taking the above project as an example, the natural gas flow rate is about 34Nm3 / s, the natural gas temperature rises by 17.8℃, and the power of the electric heater is about 1800kW. Long-term operation will increase the power consumption of the unit. At the same time, since the electric heater directly heats the natural gas, there are great safety hazards. Therefore, it is usually not directly set up a separate electric heater.

[0007] Solution 2 is to set up a tubular heat exchanger. Tubular heat exchangers are divided into two types: single-tube and double-tube. For the single-tube type, a spare heat exchanger is usually required to be set up in consideration of the wear of the heat exchange tube. Since the double-tube type has two layers of heat exchange tubes, a spare heat exchanger is generally not required. According to the different heat sources of the heat exchanger, it can be divided into steam type, hot water type, and multi-heat source type.

[0008] 1) The heating medium of steam type is auxiliary steam, which comes from the startup boiler or waste heat boiler low-pressure reheat steam or turbine extraction steam in the plant. Due to the use of high-quality steam heating, the heater is small in size and has a good heat exchange effect. However, due to the high quality of auxiliary steam, it is more suitable for power generation. Long-term use of auxiliary steam to heat natural gas will affect the power generation output of the unit and cause high-quality energy waste.

[0009] 2) The heating medium of the hot water type is the hot water at the tail of the waste heat boiler. Usually, a separate heat exchanger or an expanded low-level economizer is set at the tail of the waste heat boiler to extract hot water. This type of unit cannot produce qualified hot water during the cold start-up phase, so a startup electric heater needs to be set. This type belongs to waste heat utilization. Since a larger tail heat exchanger needs to be set, the length of the waste heat boiler will increase and the investment will increase. At the same time, after the heat exchanger is set in the waste heat boiler, its exhaust temperature will decrease, resulting in water analysis in the flue gas and aggravating the corrosion of the chimney.

[0010] 3) The heating medium of the multi-heat source type is auxiliary steam + hot water at the tail of the waste heat boiler. This type combines the advantages of the steam type and the hot water type. The startup electric heater can be eliminated, steam heating is used in the startup phase, and hot water heating is switched after the qualified hot water is produced. This type also has problems such as increased length of the waste heat boiler, increased investment, and aggravated chimney corrosion. Summary of the invention

[0011] In order to solve the problems of high investment, high-grade energy consumption, chimney corrosion and the like of natural gas dew point heating systems in existing natural gas combined cycle power plants, the utility model provides a natural gas dew point heating system for gas-steam combined cycle power plants which utilizes waste heat from circulating cooling water in the plant.

[0012] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0013] A natural gas dew point heating system for a gas-steam combined cycle power plant, the system comprising a dew point heater, a circulating cooling water water side system and a natural gas gas side system;

[0014] The circulating cooling water side system includes a booster pump inlet pipeline and a return pipeline; the booster pump inlet pipeline takes water from the circulating water cooling water return main pipe in the factory, and is equipped with a booster pump for use and a backup; the booster pump inlet pipeline includes a booster pump, and a filter and a fourth stop valve are arranged on the booster pump inlet pipeline; a check valve and an electric shut-off valve are arranged in sequence between the water outlet of the booster pump and the water inlet of the dew point heater; the water inlet of the return pipeline is connected to the water outlet of the dew point heater, and the return pipeline is equipped with a first stop valve, an electric regulating valve and a second stop valve; a bypass is arranged on the return pipeline, and a third stop valve is arranged on the bypass;

[0015] The natural gas gas side system includes a starting electric heater; the air inlet of the starting electric heater is connected to the natural gas main pipe through a first pipeline, and a first manual ball valve is arranged on the first pipeline; the air outlet of the starting electric heater is connected to the air inlet of the dew point heater through a second pipeline, and a second manual ball valve and a third manual ball valve are arranged on the second pipeline; an electric heater bypass pipeline is arranged between the air inlet of the first manual ball valve and the second manual ball valve, and a fourth manual ball valve is arranged on the electric heater bypass pipeline; the air outlet of the dew point heater is connected to the natural gas main pipe through a fourth pipeline, and a fifth manual ball valve is arranged on the fourth pipeline; a dew point heater bypass pipeline is arranged between the air inlet of the third manual ball valve and the air outlet of the fifth manual ball valve, and a sixth manual ball valve is arranged on the dew point heater bypass pipeline.

[0016] Furthermore, the water inlet and the water outlet of the booster pump are respectively provided with a connector.

[0017] Furthermore, the dew point heater adopts a double-tube shell and tube heat exchanger, which is made of stainless steel.

[0018] Furthermore, the heating medium of the dew point heater is the return water of the circulating cooling water system in the plant, which is waste heat of the power plant.

[0019] Furthermore, the booster pump is a centrifugal circulating cooling water booster pump;

[0020] The two booster pumps are one for use and one for backup, and adopt one-to-two frequency conversion control.

[0021] Furthermore, a first temperature measuring point is arranged on the first pipeline.

[0022] Furthermore, a second temperature measuring point is provided on the fourth pipeline.

[0023] Furthermore, a third temperature measuring point is provided at the water inlet of the booster pump.

[0024] Furthermore, a fourth temperature measuring point is provided on the return water pipeline.

[0025] Furthermore, the dew point heater is provided with a safety valve.

[0026] Compared with the prior art, the advantages of the utility model are:

[0027] Most of the existing technologies use steam and hot water at the tail of the boiler as heat sources. Long-term use of steam to heat natural gas will affect the power generation output of the unit, causing waste of high-grade energy and affecting the thermal efficiency of the power plant. Using hot water at the tail of the boiler as a heat source requires a larger tail heat exchanger, and the length of the waste heat boiler needs to be increased, which increases investment. At the same time, the exhaust temperature of the waste heat boiler is reduced, resulting in water separation in the flue gas and aggravating the corrosion of the chimney. The utility model overcomes the disadvantages of conventional dew point heaters using steam or hot water as heat sources, and fully utilizes the waste heat of the circulating water return water in the plant as a heat source to achieve waste heat utilization, without reducing the thermal efficiency of the unit or causing the risk of chimney corrosion. At the same time, it can reduce the circulating water pump output and cooling tower output by about 48kW and 42kW respectively based on a certain H-level combined cycle, accounting for 2.5% of the circulating water pump output and cooling tower power consumption. Calculated based on an annual utilization hour of 4000h, it saves 360,000 kW.h of plant electricity, with obvious economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a working principle diagram of the utility model.

[0029] in:

[0030] 1. Stop valve, 2. Filter, 3. Connector, 4. Booster pump, 5. Check valve, 6. Electric shut-off valve, 7. Manual ball valve, 8. Double-tube dew point heater, 9. Safety valve, 10. Stop valve, 11. Electric regulating valve, 12. Start electric heater, 13. Natural gas inlet temperature measuring point, 14. Natural gas outlet temperature measuring point, 15. Circulating water inlet temperature measuring point, 16. Circulating water return temperature measuring point. DETAILED DESCRIPTION

[0031] The utility model is further described below in conjunction with the accompanying drawings:

[0032] In order to cool the exhaust steam of the steam turbine, a gas-steam combined cycle unit usually has a circulating cooling water system, which consists of an inlet pipe, a return pipe, a cooling tower, a circulating pump, etc. Taking the above project as an example, a mechanical ventilation cooling tower is selected. The cooling tower consists of 7 sets of fans, and the power of each fan is about 240kW. In summer, the inlet water temperature is about 40.1℃ (circulating cooling water return water), the outlet water temperature is about 30.5℃ (circulating cooling water inlet water), the circulating water flow is about 39,000t / h, and the circulating water pump is one for use and one for standby, with a power of about 1900kW. Circulating cooling water return is waste heat and needs to be cooled by the cooling tower fan. If circulating water return is used to heat natural gas to 20°C, about 1000t / h of circulating cooling water return needs to be extracted. According to the calculation of the project mentioned above, the circulating water pump output and cooling tower output are reduced by about 48kW and 42kW respectively, accounting for 2.5% of the circulating water pump output and cooling tower power consumption. Calculated based on an annual utilization hour of 4000h, 360,000 kW.h of factory electricity is saved, with obvious economic benefits.

[0033] like Figure 1 A natural gas dew point heating system for a gas-steam combined cycle power plant using waste heat from circulating cooling water in the plant is shown, the system comprises a start-up electric heater 12, a dew point heater 8, a circulating cooling water water side system and a natural gas gas side system. The dew point heater 8 comprises a gas flow portion and a cooling water flow portion, the gas flow portion is respectively connected to a natural gas inlet and a natural gas outlet, the cooling water flow portion is taken from a return water system of circulating cooling water in the plant, and is respectively connected to a circulating cooling water inlet and a circulating cooling water return.

[0034] The circulating cooling water side system includes a booster pump inlet pipeline and a return pipeline. The booster pump inlet pipeline takes water from the circulating water cooling water return main pipe in the factory, and is equipped with a booster pump for use and a backup. The booster pump inlet pipeline includes Figure 1 The two branches shown have the same composition. The booster pump pipeline includes a booster pump 4, and a filter 2 and a fourth stop valve 1 are sequentially arranged on the water inlet pipeline of the booster pump 4; a check valve 5 and an electric shut-off valve 6 are sequentially arranged between the water outlet of the booster pump 4 and the water inlet of the dew point heater 8; the water inlet of the return water pipeline is connected to the water outlet of the dew point heater 8, and a first stop valve 10-1, an electric regulating valve 11 and a second stop valve 10-2 are arranged on the return water pipeline; a bypass is arranged on the return water pipeline, and a third stop valve 10-3 is arranged on the bypass.

[0035] The natural gas side system includes a starting electric heater 12; the air inlet of the starting electric heater 12 is connected to the natural gas main pipe through a first pipeline, and a first manual ball valve 7-1 is provided on the first pipeline; the air outlet of the starting electric heater 12 is connected to the air inlet of the dew point heater 8 through a second pipeline, and a second manual ball valve 7-2 and a third manual ball valve 7-3 are provided on the second pipeline; the electric heater is provided with an electric heater bypass pipeline, and a fourth manual ball valve 7-4 is provided on the electric heater bypass pipeline; the air outlet of the dew point heater 8 is connected to the natural gas main pipe through a fourth pipeline, and a fifth manual ball valve 7-5 is provided on the fourth pipeline; the dew point heater 8 is provided with a dew point heater bypass pipeline, and a sixth manual ball valve 7-6 is provided on the dew point heater bypass pipeline.

[0036] The water inlet of the dew point heater is taken from the circulating cooling water return water in the factory, and the water return water returns to the original circulating cooling water supply system; the natural gas gas side system of the natural gas dew point heater is equipped with front, rear and bypass manual ball valves to achieve maintenance isolation; the natural gas dew point heating system is equipped with water side water inlet, return water, gas side air inlet and outlet temperature measurement points, and an electric regulating valve group is set on the water side return water pipeline, which is interlocked with the gas side outlet temperature to achieve the control of the circulating water flow. The dew point heater adopts a double-tube type, stainless steel material, safe and reliable, and can be equipped with a heater to reduce equipment investment. The dew point heater system is equipped with a centrifugal circulating cooling water booster pump, one for use and one for backup, and adopts "one to two" frequency conversion control, the system is reliable, energy-saving and efficiency-improving; a startup electric heater is set during the unit startup phase, and the electric heater is equipped with front, rear and bypass manual ball valves, which are used during the startup phase or when the dew point heater is exited, thereby improving the reliability of the system.

[0037] In some embodiments, the dew point heater 8 is a shell and tube type, and a double-tube dew point heater is used, and its heat source is the circulating water return water in the plant, the natural gas goes to the pipe side, and the circulating water goes to the shell side. If there is no circulating water return water with a sufficient temperature during the unit startup phase, the startup electric heater 12 can be put into use first. After the unit establishes a cycle, the circulating water return water temperature meets the natural gas heating needs and switches to the double-tube dew point heater 8 to heat the natural gas. The dew point heater 8 is connected to the natural gas inlet and outlet, the circulating water inlet and return water, and is provided with a safety valve 9.

[0038] In some embodiments, the natural gas dew point heating system is provided with temperature measuring points on the natural gas inlet and outlet sides and the circulating water inlet and return sides, and the natural gas outlet side temperature is interlockedly controlled with the electric regulating valve on the circulating water return side, and the circulating water flow rate is adjusted according to the natural gas outlet side temperature.

[0039] A first temperature measuring point 13 is provided on the first pipeline. A second temperature measuring point 14 is provided on the fourth pipeline. A third temperature measuring point 15 is provided at the inlet of the circulating cooling water boosting pipeline. A fourth temperature measuring point 16 is provided on the return water pipeline of the dew point heater 8. The utility model sets a first temperature measuring point 13 (natural gas inlet temperature measuring point), a second temperature measuring point 14 (natural gas outlet temperature measuring point), a third temperature measuring point 15 (circulating water inlet temperature measuring point), and a fourth temperature measuring point 16 (circulating water return temperature measuring point). Four temperature measuring points are used to detect the temperature of natural gas and circulating water, wherein the natural gas outlet temperature measuring point 14 forms a chain control with the electric regulating valve 11, and the circulating water flow is controlled by the natural gas temperature. Whether heating is required is determined according to the temperature of the first temperature measuring point 13. When heating is not required, the natural gas can switch to start the electric heater bypass and the dew point heater bypass to reduce the resistance of the system equipment. If heating is required, determine whether the circulating cooling water waste heat temperature meets the heater requirements based on the water side inlet temperature. If not, start the electric heater 12 for auxiliary heating. If satisfied, stop starting the electric heater 12 and start the dew point heater 8. Obtain the gas side outlet temperature based on the second temperature measuring point 14, control the electric regulating valve 11, and then control the circulating cooling water flow.

[0040] The working principle of the utility model is:

[0041] (1) Dew point heater 8 gas side

[0042] A manual ball valve 7-1 is provided on the natural gas inlet pipeline, a manual ball valve 7-2 is provided on the natural gas outlet pipeline, and a bypass manual ball valve 7-4 is provided on the dew point heater to realize the maintenance and isolation of the dew point heater. When the dew point heater 8 stops running due to a fault, the starting electric heater + bypass ball valve can be used to meet the natural gas temperature requirements. The starting electric heater 12 is connected to the natural gas inlet and the natural gas outlet respectively, and a first manual ball valve 7-1, a second manual ball valve 7-2 and a manual ball valve bypass (the fourth manual ball valve 7-4 and the pipeline where it is located) are provided. The manual ball valve bypass is used to maintain and switch the bypass when the starting electric heater 12 is overhauled, isolated, or fails, to ensure the reliability of the system. The natural gas can also pass through the fourth manual ball valve 7-4 when the unit is operating normally to reduce the resistance loss of the natural gas system.

[0043] The startup electric heater 12 is used when there is no circulating cooling water of sufficient temperature during the startup phase of the unit or when the dew point heater fails or is under maintenance. The startup electric heater 12 is put into use when the circulating cooling water return temperature is low and cannot meet the dew point heating demand during the startup phase of a new unit. As the unit load increases, the electric heater is exited when the circulating cooling water return temperature rises, and the waste heat of the circulating cooling water is used to heat the natural gas. By setting the first manual ball valve 7-1, the second manual ball valve 7-2, the third manual ball valve 7-3 and the fourth manual ball valve 7-4, it has a non-stop isolation function. When the startup electric heater 12 fails or exits, the natural gas can pass through the bypass ball valve (i.e., the fourth manual ball valve 7-4) to reduce system resistance.

[0044] After the unit is started, the double-tube dew-point heater is switched according to the circulating water return temperature; the double-tube dew-point heater is also connected to the natural gas inlet and outlet, and is equipped with inlet, outlet and bypass ball valves. When the dew-point heater fails, the natural gas passes through the bypass ball valve + start-up electric heater to meet the needs of the gas turbine, and the dew-point heater failure will not cause shutdown, thereby improving system reliability.

[0045] (2) Dew point heater 8 water inlet side

[0046] The heating heat source comes from the circulating water return water in the plant. The temperature is about 40.1℃ in summer. Two booster pumps 4 are set. Stop valve 1 and filter 2 are set in front of the booster pumps. The filter is used to filter impurities in the pipeline to protect the booster pump 4 and the subsequent dew point heater 8; the stop valve 1 is used for maintenance and isolation of the two booster pumps; the check valve 5 and the electric shut-off valve 6 are set at the outlet of the booster pump 4. The check valve 5 is used to prevent the circulating water from flowing back, and the electric shut-off valve 6 is used for automatic switching of the two booster pumps 4. A connector 3 is set before and after the booster pump for connecting the circulating water pipeline. Two centrifugal circulating water booster pumps are set on the water inlet side of the double-tube dew point heater 8, one for use and one for backup, and are controlled by a "one-to-two" inverter.

[0047] (3) Dew point heater 8 return water side

[0048] The return water side of the natural gas dew point heater is equipped with an electric regulating valve group for controlling the circulating water flow. The regulating valve group consists of front and rear manual stop valves (first stop valve 10-1 and second stop valve 10-2) and a manual stop valve bypass (third stop valve 10-3), which is used for maintenance and isolation of the electric regulating valve 11. The return water temperature on the return water side is about 30°C (temperature measuring point 16) and matches the temperature of the circulating water supply in the plant, and the return water is returned to the original circulating cooling water supply system in the plant. The electric regulating valve and the temperature measuring point 14 of the outlet pipeline of the dew point heater form a chain control, and the temperature measuring point 14 is ensured to be kept above 20°C by adjusting the valve opening.

[0049] The above-described embodiments are merely descriptions of preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A natural gas dew point heating system for a gas-steam combined cycle power plant, characterized in that: The system comprises a dew point heater (8), a circulating cooling water water side system and a natural gas gas side system; The circulating cooling water water side system comprises a booster pump inlet pipeline and a return pipeline; the booster pump inlet pipeline takes water from the circulating water cooling water return main pipe in the factory, and is provided with a booster pump in use and a backup; the booster pump inlet pipeline comprises a booster pump (4), and a filter (2) and a fourth stop valve (1) are arranged on the booster pump (4); a check valve (5) and an electric shut-off valve (6) are arranged in sequence between the water outlet of the booster pump (4) and the water inlet of the dew point heater (8); the water inlet of the return pipeline is connected to the water outlet of the dew point heater (8), and a first stop valve (10-1), an electric regulating valve (11) and a second stop valve (10-2) are arranged on the return pipeline; a bypass is arranged on the return pipeline, and a third stop valve (10-3) is arranged on the bypass; The natural gas gas side system comprises a starting electric heater (12); an air inlet of the starting electric heater (12) is connected to a natural gas main pipe via a first pipeline, and a first manual ball valve (7-1) is provided on the first pipeline; an air outlet of the starting electric heater (12) is connected to an air inlet of the dew point heater (8) via a second pipeline, and a second manual ball valve (7-2) and a third manual ball valve (7-3) are provided on the second pipeline; an air inlet of the first manual ball valve (7-1) is connected to an air inlet of the second manual ball valve (7-1); An electric heater bypass pipeline is provided between the valves (7-2), and a fourth manual ball valve (7-4) is provided on the electric heater bypass pipeline; an outlet of the dew point heater (8) is connected to the natural gas main pipe via a fourth pipeline, and a fifth manual ball valve (7-5) is provided on the fourth pipeline; a dew point heater bypass pipeline is provided between the air inlet of the third manual ball valve (7-3) and the air outlet of the fifth manual ball valve (7-5), and a sixth manual ball valve (7-6) is provided on the dew point heater bypass pipeline.

2. The natural gas dew point heating system for a gas-steam combined cycle power plant according to claim 1, characterized in that: The water inlet and the water outlet of the booster pump (4) are respectively provided with a connector (3).

3. The natural gas dew point heating system for a gas-steam combined cycle power plant according to claim 1, characterized in that: The dew point heater (8) adopts a double-tube shell and tube heat exchanger, and its material is stainless steel.

4. The natural gas dew point heating system for a gas-steam combined cycle power plant according to claim 1, characterized in that: The heating medium of the dew point heater (8) is the return water of the circulating cooling water system in the plant, which is waste heat from the power plant.

5. The natural gas dew point heating system for a gas-steam combined cycle power plant according to claim 1, characterized in that: The booster pump (4) is a centrifugal circulating cooling water booster pump; the two booster pumps are one for use and one for backup, and adopt a one-to-two frequency conversion control.

6. The natural gas dew point heating system for a gas-steam combined cycle power plant according to claim 1, characterized in that: A first temperature measuring point (13) is provided on the first pipeline.

7. The natural gas dew point heating system for a gas-steam combined cycle power plant according to claim 1, characterized in that: The fourth pipeline is provided with a second temperature measuring point (14).

8. The natural gas dew point heating system for a gas-steam combined cycle power plant according to claim 1, characterized in that: A third temperature measuring point (15) is provided at the water inlet of the booster pump.

9. The natural gas dew point heating system for a gas-steam combined cycle power plant according to claim 1, characterized in that: A fourth temperature measuring point (16) is provided on the return water pipeline.

10. The natural gas dew point heating system for a gas-steam combined cycle power plant according to claim 1, characterized in that: The dew point heater (8) is provided with a safety valve (9).

Images