Steam supply system of zero high-pressure heater

Abstract

The utility model discloses a steam supply system of a zero high-pressure heater, and relates to the technical field of steam supply of coal-fired power generating units. The device comprises a pressure matcher, a high-pressure steam inlet of the pressure matcher is connected to a high-pressure steam source through a high-pressure steam inlet pipeline, a low-pressure steam inlet of the pressure matcher is connected to a low-pressure steam source through a low-pressure steam inlet pipeline, and a steam outlet of the pressure matcher is connected to a zero high-pressure heater through a steam outlet pipeline; at least one high-pressure check valve is arranged on the high-pressure steam inlet pipeline, a first on-off valve is arranged between the high-pressure check valve and the high-pressure steam source, and a second on-off valve is arranged between the high-pressure check valve and the pressure matcher; a low-pressure check valve, a first regulating valve and a third on-off valve are sequentially arranged on the low-pressure steam inlet pipeline in the direction from the low-pressure steam source to the pressure matcher; the high-pressure steam inlet pipeline and the high-pressure steam source are connected through a first connecting piece. The zero high-pressure heater steam supply system can solve the problems that steam extracted by an existing zero high-pressure heater steam supply system is a high-grade heat source, and large throttling loss can be generated.

Description

Technical Field

[0001] This utility model relates to the field of steam supply technology for coal-fired power generation units, and in particular to a steam supply system for a No. 0 high-pressure heater. Background Technology

[0002] With the changing energy structure, the installed capacity and proportion of wind power and solar power are gradually increasing. Coal-fired power generating units will inevitably participate in deep peak shaving. As the load of coal-fired power generating units decreases, the boiler feedwater temperature decreases, leading to a decrease in flue gas temperature under low load conditions. Denitrification devices will then be shut down, causing the unit's emissions to fail to meet environmental protection requirements under low load conditions. Therefore, under low load conditions, increasing the boiler feedwater temperature can reduce heat consumption under low load conditions, and increasing the flue gas temperature can reduce the number of operating conditions where emissions fail to meet standards due to the shutdown of denitrification devices.

[0003] Under high-load conditions, the boiler feedwater temperature is heated by using multiple high-pressure heaters that utilize turbine extraction steam or boiler exhaust steam. Under low-load conditions, to increase the feedwater temperature, typically only the No. 0 high-pressure heater with the highest extraction steam pressure is used. At 50% THA, the No. 0 high-pressure heater can increase the feedwater temperature by 50°C. The No. 0 high-pressure heater has two steam source options: one is to extract steam through holes drilled in the turbine body, and the other is to extract steam from the turbine's make-up steam pipe. The existing No. 0 high-pressure heater steam supply system is as follows: Figure 1 As shown, high-pressure steam drawn from the high-pressure cylinder 101 of the steam turbine or the make-up steam pipeline 102 provides heating steam to the zero high-pressure heater 103 through the steam supply pipeline. From the high-pressure steam source to the zero high-pressure heater 103, the steam supply pipeline is sequentially equipped with a first electric gate valve 104, a pneumatic check valve 105, a check valve 106, and two parallel regulating branches. The first regulating branch is equipped with a second electric gate valve 107 and a regulating valve 108, and the second regulating branch is equipped with a third electric gate valve 109 and a bypass regulating valve 110. The second regulating branch is a spare pipeline. A safety valve 111 is also provided between the two parallel regulating branches and the zero high-pressure heater.

[0004] Since the extracted steam pressure is much higher than the steam pressure required by the No. 0 high-pressure heater, the steam supply system can adjust the steam pressure entering the No. 0 high-pressure heater through regulating valves, thereby adjusting the outlet feedwater temperature of the No. 0 high-pressure heater. However, the steam extracted by this steam supply system is all high-grade heat source, which will produce a large throttling loss. As the throttling loss increases, the effective energy actually used for production decreases, thereby reducing the energy utilization efficiency of the entire steam supply system. Throttling loss means that more high-grade heat source is needed to meet the given energy demand, which will increase fuel consumption and operating costs. Therefore, long-term throttling loss will accumulate into a huge economic burden. Utility Model Content

[0005] The purpose of this invention is to provide a steam supply system for a No. 0 high-pressure heater, which can solve the problem that the steam extracted by the existing No. 0 high-pressure heater steam supply system is all high-grade heat source, resulting in a large throttling loss.

[0006] To solve the above problems, the technical solution adopted by this utility model is as follows: This zero-pressure heater steam supply system includes a pressure matching device. Its high-pressure steam inlet is connected to a high-pressure steam source through a high-pressure steam inlet pipe, its low-pressure steam inlet is connected to a low-pressure steam source through a low-pressure steam inlet pipe, and its steam outlet is connected to the zero-pressure heater through an outlet pipe. At least one high-pressure check valve is provided on the high-pressure steam inlet pipe. A first on / off valve is provided between the high-pressure check valve and the high-pressure steam source, and a second on / off valve is provided between the high-pressure check valve and the pressure matching device. From the low-pressure steam source to the pressure matching device, a low-pressure check valve, a first regulating valve, and a third on / off valve are sequentially provided on the low-pressure steam inlet pipe. The high-pressure steam inlet pipe and the high-pressure steam source are connected by a first connecting member.

[0007] A more specific technical solution than the above-mentioned technical solution could be that a safety valve is provided on the steam outlet pipe.

[0008] Furthermore, a backup steam supply pipeline is provided between the high-pressure check valve and the safety valve. The backup steam supply pipeline is equipped with a fourth on / off valve and a second regulating valve. The fourth on / off valve is located on the side closer to the high-pressure check valve, and the second regulating valve is located on the side closer to the safety valve.

[0009] Furthermore, pressure measuring instruments are installed on the high-pressure steam inlet pipe, the low-pressure steam inlet pipe, and the steam outlet pipe.

[0010] Furthermore, the high-pressure steam source is the high-pressure cylinder of the steam turbine and / or the make-up steam pipeline, and the low-pressure steam source is the intermediate-pressure cylinder of the steam turbine and / or the low-pressure cylinder of the steam turbine.

[0011] Furthermore, the first on / off valve, the second on / off valve, and the fourth on / off valve are all electric gate valves, the third on / off valve is an electric shut-off valve, there are two high-pressure check valves, one of which and the other of which is a pneumatic check valve, the first regulating valve is a hydraulic quick-closing regulating valve, and the second regulating valve is a bypass regulating valve.

[0012] Furthermore, the low-pressure steam inlet pipe and the low-pressure steam source are connected by a second connector.

[0013] Furthermore, both the first connector and the second connector are tee fittings.

[0014] By adopting the above technical solution, this utility model has the following beneficial effects compared with the prior art:

[0015] 1. This utility model uses a pressure matching device to mix high-pressure steam and low-pressure steam. The mixed steam is adjusted to a suitable pressure by the pressure matching device and then supplied to the zero high-pressure heater. This not only makes full use of the pressure of the high-pressure steam source, but also uses the exhaust steam from the intermediate-pressure cylinder to reduce the amount of high-grade heat source used, and introduces low-pressure steam sources from the intermediate-pressure cylinder and the low-pressure cylinder, increasing the use of low-grade heat source, reducing throttling losses, improving the energy utilization efficiency of the entire steam supply system, achieving the goal of energy saving and consumption reduction, thereby reducing fuel consumption and operating costs, and alleviating the economic burden on enterprises.

[0016] 2. This utility model also provides a backup solution: when the generator set load is low and the pressure of the high-pressure steam extracted from the high-pressure steam source does not meet the working conditions of the pressure matching device, the high-pressure steam is supplied to the zero high-pressure heater through the backup steam supply pipeline and the pressure is reduced by the second regulating valve.

[0017] 3. High-pressure steam can be drawn simultaneously from the high-pressure cylinder and the make-up steam pipeline of the turbine, or one of them can be selected for extraction. Low-pressure steam can be drawn simultaneously from the intermediate-pressure cylinder and the low-pressure cylinder of the turbine, or one of them can be selected for extraction. Two high-pressure check valves are installed on the high-pressure steam inlet pipeline to effectively prevent high-pressure steam backflow. The low-pressure check valve installed on the low-pressure steam inlet pipeline can prevent high-pressure steam from entering the intermediate-pressure cylinder and the low-pressure cylinder from the pressure matching device. The safety valve can automatically open when the system pressure is too high to release excess pressure and protect the system safety. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the existing No. 0 high-pressure heater steam supply system;

[0019] Figure 2 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0021] like Figure 2The steam supply system for the No. 0 high-pressure heater shown includes a pressure matching device 1, whose high-pressure steam inlet is connected to a high-pressure steam source through a high-pressure steam inlet pipe 2, whose low-pressure steam inlet is connected to a low-pressure steam source through a low-pressure steam inlet pipe 3, and whose steam outlet is connected to the No. 0 high-pressure heater 5 through a steam outlet pipe 4. From the high-pressure steam source to the pressure matching device 1, the high-pressure steam inlet pipe 2 is sequentially equipped with a first on / off valve 6, a first high-pressure check valve 7, a second high-pressure check valve 8, and a second on / off valve 9. From the low-pressure steam source to the pressure matching device 1, the low-pressure steam inlet pipe 3 is sequentially equipped with a low-pressure check valve 10, a first regulating valve 11, and a third on / off valve 12.

[0022] A safety valve 13 is provided on the steam outlet pipeline 4. A backup steam supply pipeline 14 is provided between the second high-pressure check valve 8 and the safety valve 13. A fourth on / off valve 15 and a second regulating valve 16 are provided on the backup steam supply pipeline 14. The fourth on / off valve 15 is located on the side closer to the second high-pressure check valve 8, and the second regulating valve 16 is located on the side closer to the safety valve 13.

[0023] The high-pressure steam source is the high-pressure cylinder 17 and / or the make-up steam pipe 18 of the steam turbine, and the low-pressure steam source is the intermediate-pressure cylinder 19 and / or the low-pressure cylinder 20 of the steam turbine. The high-pressure steam inlet pipe 2, the high-pressure cylinder 17 and the make-up steam pipe 18 of the steam turbine are connected by a first connector, and the low-pressure steam inlet pipe 3, the intermediate-pressure cylinder 19 and the low-pressure cylinder 20 of the steam turbine are connected by a second connector. In this embodiment, both the first connector and the second connector are tee joints.

[0024] Pressure measuring instruments are installed on the high-pressure steam inlet pipe 2, the low-pressure steam inlet pipe 3, and the steam outlet pipe 4. Three heating steam pressure measuring instruments P1 are installed on the side of the steam outlet pipe 4 near the zero high-pressure heater 5. Three high-pressure steam source pressure measuring instruments P2 are installed on the side of the high-pressure steam inlet pipe 2 near the pressure matching device 1. Three low-pressure steam source pressure measuring instruments P3 are installed on the side of the low-pressure steam inlet pipe 3 near the low-pressure cylinder 20.

[0025] The first on / off valve 6, the second on / off valve 9, and the fourth on / off valve 15 are all electric gate valves; the third on / off valve 12 is an electric shut-off valve; the first high-pressure check valve 7 and the low-pressure check valve 10 are pneumatic check valves; the first regulating valve 11 is a hydraulic quick-closing regulating valve; and the second regulating valve 16 is a bypass regulating valve.

[0026] The steam supply method using the above-mentioned No. 0 high-pressure heater steam supply system includes the following steps:

[0027] A. When the generator set load is high and the pressure of the high-pressure steam extracted from the high-pressure steam source meets the working conditions of the pressure matching device 1, the pressure matching device 1 is set with the parameters and then started. The third on / off valve 12, the first regulating valve 11, the second on / off valve 9 and the first on / off valve 6 are opened in sequence. The high-pressure steam is injected at high speed, generating a negative pressure effect, thereby drawing the low-pressure steam into the pressure matching device 1 and mixing it. The mixed steam is then transported from the steam outlet of the pressure matching device 1 to the zero high-pressure heater 5 through the steam outlet pipe 4.

[0028] B. When the generator set load is low and the pressure of the high-pressure steam extracted from the high-pressure steam source does not meet the working conditions of the pressure matching device 1, the third on / off valve 12, the second on / off valve 9 and the first regulating valve 11 are closed, and the fourth on / off valve 15, the first on / off valve 6 and the second regulating valve 16 are opened in sequence. The high-pressure steam is directly transported from the standby steam supply pipeline 14 into the steam outlet pipeline 4 and then to the zero high-pressure heater 5.

[0029] This invention uses a pressure matching device 1 to mix high-pressure steam and low-pressure steam. The mixed steam is adjusted to a suitable pressure by the pressure matching device 1 and then supplied to the zero high-pressure heater 5. This not only makes full use of the pressure of the high-pressure steam source, but also uses the exhaust steam of the intermediate-pressure cylinder 19 to reduce the amount of high-grade heat source used, and introduces the low-pressure steam source of the intermediate-pressure cylinder 19 and the low-pressure cylinder 20, thereby increasing the use of low-grade heat source, reducing throttling losses, improving the energy utilization efficiency of the entire steam supply system, achieving the goal of energy saving and consumption reduction, thereby reducing fuel consumption and operating costs, and alleviating the economic burden on enterprises.

[0030] This utility model also provides a backup solution: when the generator set load is low and the pressure of the high-pressure steam extracted from the high-pressure steam source does not meet the working conditions of the pressure matching device 1, the high-pressure steam is supplied to the zero high-pressure heater 5 through the backup steam supply pipeline 14 and the pressure is reduced by the second regulating valve 16.

[0031] The high-pressure steam source can be drawn simultaneously from the high-pressure cylinder 17 and the make-up steam pipeline 18 of the steam turbine, or one of them can be selected for extraction. The low-pressure steam source can be drawn simultaneously from the intermediate-pressure cylinder 19 and the low-pressure cylinder 20 of the steam turbine, or one of them can be selected for extraction. Two high-pressure check valves are installed on the high-pressure steam inlet pipeline 2 to effectively prevent high-pressure steam backflow. The low-pressure check valve 10 installed on the low-pressure steam inlet pipeline 3 can prevent high-pressure steam from entering the intermediate-pressure cylinder 19 and the low-pressure cylinder 20 from the pressure matching device 1. The safety valve 13 can automatically open when the system pressure is too high to release excess pressure and protect the system safety.

[0032] Three pressure gauges are installed at the same location on each pipeline to prevent the system from malfunctioning due to external factors. Therefore, as long as two of the three pressure gauges are working properly, the average value can be taken.

[0033] The parameters of pressure matcher 1 are set according to the equipment and specific operating conditions.

Claims

1. A steam supply system for a No. 0 high-pressure heater, characterized in that: The device includes a pressure matching unit, whose high-pressure steam inlet is connected to a high-pressure steam source via a high-pressure steam inlet pipe, its low-pressure steam inlet is connected to a low-pressure steam source via a low-pressure steam inlet pipe, and its steam outlet is connected to a zero-pressure heater via an outlet pipe. At least one high-pressure check valve is provided on the high-pressure steam inlet pipe, a first on / off valve is provided between the high-pressure check valve and the high-pressure steam source, and a second on / off valve is provided between the high-pressure check valve and the pressure matching unit. From the low-pressure steam source to the pressure matching unit, a low-pressure check valve, a first regulating valve, and a third on / off valve are sequentially provided on the low-pressure steam inlet pipe. The high-pressure steam inlet pipe and the high-pressure steam source are connected via a first connecting member.

2. The steam supply system for the No. 0 high-pressure heater according to claim 1, characterized in that: A safety valve is installed on the steam outlet pipeline.

3. The steam supply system for the No. 0 high-pressure heater according to claim 2, characterized in that: A backup steam supply pipeline is provided between the high-pressure check valve and the safety valve. The backup steam supply pipeline is equipped with a fourth on / off valve and a second regulating valve. The fourth on / off valve is located on the side closer to the high-pressure check valve, and the second regulating valve is located on the side closer to the safety valve.

4. The steam supply system for the No. 0 high-pressure heater according to claim 3, characterized in that: Pressure measuring instruments are installed on the high-pressure steam inlet pipe, the low-pressure steam inlet pipe, and the steam outlet pipe.

5. The steam supply system for the No. 0 high-pressure heater according to claim 4, characterized in that: The high-pressure steam source is the high-pressure cylinder of the steam turbine and / or the make-up steam pipeline, and the low-pressure steam source is the intermediate-pressure cylinder of the steam turbine and / or the low-pressure cylinder of the steam turbine.

6. The steam supply system for the No. 0 high-pressure heater according to claim 5, characterized in that: The first on / off valve, the second on / off valve, and the fourth on / off valve are all electric gate valves, the third on / off valve is an electric shut-off valve, there are two high-pressure check valves, one of which and the other of which is a pneumatic check valve, the first regulating valve is a hydraulic quick-closing regulating valve, and the second regulating valve is a bypass regulating valve.

7. The steam supply system for the No. 0 high-pressure heater according to claim 6, characterized in that: The low-pressure steam inlet pipe and the low-pressure steam source are connected by a second connector.

8. The steam supply system for the No. 0 high-pressure heater according to claim 7, characterized in that: Both the first connector and the second connector are tee fittings.

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