Steam supply system and steam supply method for zero high-pressure heater

Abstract

The invention discloses a steam supply system and a steam supply method for 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; a first on-off valve, a first check valve, a second check valve and a second on-off valve are sequentially arranged on the high-pressure steam inlet pipeline in the direction from the high-pressure steam source to the pressure matcher; a third 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; and pressure measuring instruments are arranged on the high-pressure steam inlet pipeline, the low-pressure steam inlet pipeline and the steam outlet pipeline. Compared with the prior art, the problem 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 can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of steam supply for coal-fired generator sets, and in particular to a steam supply system and a steam supply method for a zero-level high-pressure heater. Background Art

[0002] With the changes in energy structure, the installed capacity and proportion of wind power and photovoltaic power are gradually increasing. Coal-fired power generation units will inevitably participate in deep peak regulation. As the load of coal-fired power generation units decreases, the boiler feed water temperature decreases, resulting in a decrease in the exhaust temperature under low load conditions and the withdrawal of the denitrification device, which makes the unit's low-load operation emission indicators fail to meet environmental protection policy requirements. Therefore, under low load conditions, on the one hand, increasing the boiler feed water temperature can reduce the heat consumption of low load conditions. On the other hand, increasing the exhaust temperature can reduce the operating conditions where emissions do not meet the standards due to the withdrawal of the denitrification device.

[0003] The method of heating the boiler feed water temperature under high load conditions is to use multiple high-pressure heaters to heat the boiler feed water using the steam extraction of the steam turbine or the exhaust steam of the boiler. To increase the feed water temperature under low load conditions, usually only the zero-level high-pressure heater with the highest extraction pressure is used to heat the boiler feed water temperature. Under 50% THA conditions, the zero-level high-pressure heater can increase the feed water temperature by 50°C. There are two options for the heating steam source of the zero-level high-pressure heater. One is to extract steam by drilling holes in the steam turbine body, and the other is to extract steam from the steam supply pipe of the steam turbine. The existing steam supply system of the zero-level high-pressure heater is as follows: Figure 1 As shown, the high-pressure steam source extracted from the high-pressure cylinder 101 of the steam turbine or the supplementary steam pipeline 102 provides heating steam to the No. 0 high-pressure heater 103 through the steam supply pipeline. From the high-pressure steam source to the No. 0 high-pressure heater 103, the steam supply pipeline is sequentially provided 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 provided with a second electric gate valve 107 and a regulating valve 108, the second regulating branch is provided with a third electric gate valve 109 and a bypass regulating valve 110, wherein the second regulating branch is a spare pipeline, and a safety valve 111 is also provided between the two parallel regulating branches and the No. 0 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 a regulating valve, thereby adjusting the outlet feed water temperature of the No. 0 high-pressure heater; however, the steam extracted by the steam supply system is a 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; and throttling loss means that more high-grade heat sources are needed to meet the established energy needs, which will increase fuel consumption and operating costs. Therefore, long-term throttling losses will also accumulate into a huge economic burden. Summary of the invention

[0005] The purpose of the present invention is to provide a steam supply system and a steam supply method 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, which will cause large throttling losses.

[0006] In order to solve the above problems, the technical solution adopted by the present invention is: this No. 0 high-pressure heater steam supply system includes a pressure matcher, whose high-pressure steam inlet is connected to the high-pressure steam source through a high-pressure steam inlet pipe, and whose low-pressure steam inlet is connected to the low-pressure steam source through a low-pressure steam inlet pipe, and whose steam outlet is connected to the No. 0 high-pressure heater through a steam outlet pipe; from the high-pressure steam source to the pressure matcher, the high-pressure steam inlet pipe is provided with a first on-off valve, a first check valve, a second check valve and a second on-off valve in sequence; from the low-pressure steam source to the pressure matcher, the low-pressure steam inlet pipe is provided with a third check valve, a first regulating valve and a third on-off valve in sequence; pressure measuring instruments are provided on the high-pressure steam inlet pipe, the low-pressure steam inlet pipe and the steam outlet pipe.

[0007] In the above technical solution, a more specific technical solution may also be: a safety valve is provided on the steam outlet pipe.

[0008] Furthermore, a spare steam supply pipeline is provided between the second check valve and the safety valve, and a fourth on-off valve and a second regulating valve are provided on the spare steam supply pipeline. The fourth on-off valve is located close to the second check valve, and the second regulating valve is located close to the safety valve.

[0009] Furthermore, the high-pressure steam source is from the high-pressure cylinder and / or the supplementary steam pipeline of the steam turbine, and the low-pressure steam source is from the medium-pressure cylinder and / or the low-pressure cylinder of the steam turbine.

[0010] Furthermore, the steam outlet pipe is provided with three heating steam pressure measuring instruments near the No. 0 high-pressure heater, the high-pressure steam inlet pipe is provided with three high-pressure steam source pressure measuring instruments near the pressure matcher, and the low-pressure steam inlet pipe is provided with three low-pressure steam source pressure measuring instruments near the low-pressure cylinder.

[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, the first check valve and the third check valve are pneumatic check valves, the first regulating valve is a hydraulic quick-closing regulating valve, and the second regulating valve is a bypass regulating valve.

[0012] The steam supply method using the above-mentioned zero-level high-pressure heater steam supply system comprises the following steps: A. When the load of the generator set is high and the pressure of the high-pressure steam extracted from the high-pressure steam source meets the working conditions of the pressure matcher, the pressure matcher is started after the parameters are set, and the third on-off valve, the first regulating valve, the second on-off valve and the first on-off valve are opened in sequence, and the high-pressure steam is ejected at a high speed to produce a negative pressure effect, thereby sucking the low-pressure steam into the pressure matcher and mixing it. The mixed steam is transported from the steam outlet of the pressure matcher through the steam outlet pipeline to the zero-pressure heater; B. When the load of the generator set is low and the high-pressure steam pressure extracted from the high-pressure steam source does not meet the working conditions of the pressure matcher, close the third on-off valve, the second on-off valve and the first regulating valve, and open the fourth on-off valve, the first on-off valve and the second regulating valve in sequence. The high-pressure steam directly enters the steam outlet pipeline from the standby steam supply pipeline and is then transported to the No. 0 high-pressure heater.

[0013] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art: 1. The present invention uses a pressure matcher to mix high-pressure steam and low-pressure steam. The mixed steam is adjusted to a suitable pressure by the pressure matcher and then supplied to the zero-pressure high-pressure heater. Not only the pressure of the high-pressure steam source is fully utilized, but also the exhaust steam of the medium-pressure cylinder is used to reduce the use of high-grade heat sources, and the low-pressure steam sources of the medium-pressure cylinder and the low-pressure cylinder are introduced, which increases the use of low-grade heat sources, reduces throttling losses, improves the energy utilization efficiency of the entire steam supply system, and achieves the purpose of energy saving and consumption reduction, thereby reducing fuel consumption and operating costs, and alleviating the economic burden of enterprises.

[0014] 2. The present invention also provides a backup plan. When the load of the generator set 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 matcher, the high-pressure steam is reduced in pressure through the second regulating valve through the backup steam supply pipeline to provide heating steam to the No. 0 high-pressure heater.

[0015] 3. The high-pressure steam source can be extracted from the high-pressure cylinder and the supplementary steam pipeline of the steam turbine at the same time, or one of them can be selected for extraction. The low-pressure steam source can be extracted from the intermediate-pressure cylinder and the low-pressure cylinder of the steam turbine at the same time, or one of them can be selected for extraction. Two check valves are set on the high-pressure steam inlet pipeline to effectively prevent the backflow of high-pressure steam. The third check valve set 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 matcher. The safety valve can automatically open when the system pressure is too high to release excess pressure and protect the safety of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the existing steam supply system of the zero-level high-pressure heater; Figure 2 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the accompanying drawings: like Figure 2 The steam supply system of the No. 0 high-pressure heater shown in the figure includes a pressure matcher 1, whose high-pressure steam inlet is connected to the high-pressure steam source through a high-pressure steam inlet pipe 2, whose low-pressure steam inlet is connected to the 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 matcher 1, the high-pressure steam inlet pipe 2 is provided with a first on-off valve 6, a first check valve 7, a second check valve 8 and a second on-off valve 9 in sequence; from the low-pressure steam source to the pressure matcher 1, the low-pressure steam inlet pipe 3 is provided with a third check valve 10, a first regulating valve 11 and a third on-off valve 12 in sequence; pressure measuring instruments are provided on the high-pressure steam inlet pipe 2, the low-pressure steam inlet pipe 3 and the steam outlet pipe 4.

[0018] A safety valve 13 is provided on the steam outlet pipe 4, and a spare steam supply pipe 14 is provided between the second check valve 8 and the safety valve 13. A fourth on-off valve 15 and a second regulating valve 16 are provided on the spare steam supply pipe 14. The fourth on-off valve 15 is located close to the second check valve 8, and the second regulating valve 16 is located close to the safety valve 13.

[0019] The high-pressure steam source is the high-pressure cylinder 17 of the steam turbine and / or the supplementary steam pipeline 18, and the low-pressure steam source is the intermediate-pressure cylinder 19 of the steam turbine and / or the low-pressure cylinder 20 of the steam turbine; the high-pressure steam inlet pipeline 2, the high-pressure cylinder 17 of the steam turbine and the supplementary steam pipeline 18 are connected through a first three-way joint, and the low-pressure steam inlet pipeline 3, the intermediate-pressure cylinder 19 of the steam turbine and the low-pressure cylinder 20 of the steam turbine are connected through a second three-way joint.

[0020] The steam outlet pipe 4 is provided with three heating steam pressure measuring instruments P1 on the side near the zero-level high-pressure heater 5, the high-pressure steam inlet pipe 2 is provided with three high-pressure steam source pressure measuring instruments P2 on the side near the pressure matcher 1, and the low-pressure steam inlet pipe 3 is provided with three low-pressure steam source pressure measuring instruments P3 on the side near the low-pressure cylinder 20.

[0021] 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 check valve 7 and the third check valve 10 are pneumatic check valves, the first regulating valve 11 is a hydraulic fast closing regulating valve, and the second regulating valve 16 is a bypass regulating valve.

[0022] The steam supply method using the above-mentioned zero-level high-pressure heater steam supply system comprises the following steps: A. When the load of the generator set is high and the pressure of the high-pressure steam extracted from the high-pressure steam source meets the working conditions of the pressure matcher 1, the pressure matcher 1 is started after the parameters are set, and 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, and the high-pressure steam is ejected at a high speed to generate a negative pressure effect, thereby sucking the low-pressure steam into the pressure matcher 1 and mixing it. The mixed steam is transported from the steam outlet of the pressure matcher 1 through the steam outlet pipe 4 to the zero-pressure heater 5; B. When the load of the generator set 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 matcher 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, and the high-pressure steam directly enters the steam outlet pipe 4 from the standby steam supply pipe 14 and is then transported to the No. 0 high-pressure heater 5.

[0023] The present invention uses a pressure matcher 1 to mix high-pressure steam and low-pressure steam. The mixed steam is adjusted to a suitable pressure by the pressure matcher 1 and then supplies steam to the No. 0 high-pressure heater 5. Not only does it make full use of the pressure of the high-pressure steam source, but it also uses the exhaust steam of the medium-pressure cylinder 19 to reduce the use of high-grade heat sources, and introduces low-pressure steam sources from the medium-pressure cylinder 19 and the low-pressure cylinder 20, thereby increasing the use of low-grade heat sources, reducing throttling losses, and improving the energy utilization efficiency of the entire steam supply system, achieving the purpose of energy saving and consumption reduction, thereby reducing fuel consumption and operating costs, and alleviating the economic burden on enterprises.

[0024] The present invention also provides a backup plan. When the load of the generator set 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 matcher 1, the high-pressure steam is reduced in pressure through the backup steam supply pipeline 14 and the second regulating valve 16 to provide heating steam to the zero-pressure heater 5.

[0025] The high-pressure steam source can be extracted from the high-pressure cylinder 17 and the supplementary steam pipe 18 of the steam turbine at the same time, or one of them can be selected for extraction. The low-pressure steam source can be extracted from the intermediate-pressure cylinder 19 and the low-pressure cylinder 20 of the steam turbine at the same time, or one of them can be selected for extraction. Two check valves are arranged on the high-pressure steam inlet pipe 2 to effectively prevent the backflow of high-pressure steam. The third check valve 10 arranged on the low-pressure steam inlet pipe 3 can prevent the high-pressure steam from entering the intermediate-pressure cylinder 19 and the low-pressure cylinder 20 from the pressure matcher 1. The safety valve 13 can automatically open when the system pressure is too high to release excess pressure and protect the safety of the system.

[0026] Three pressure gauges are set at the same position on each pipeline to prevent one of the pressure gauges from operating abnormally due to external reasons, thereby causing the system to operate incorrectly. Therefore, as long as two of the three pressure gauges operate normally, the average value can be taken.

[0027] The parameters of the pressure matcher 1 are set according to the equipment and specific working conditions.

Claims

1. A steam supply system for a zero-level high-pressure heater, characterized in that: It includes a pressure matcher, whose high-pressure steam inlet is connected to a high-pressure steam source through a high-pressure steam inlet pipe, whose low-pressure steam inlet is connected to a low-pressure steam source through a low-pressure steam inlet pipe, and whose steam outlet is connected to a zero-pressure high-pressure heater through a steam outlet pipe; from the high-pressure steam source to the pressure matcher, the high-pressure steam inlet pipe is provided with a first on-off valve, a first check valve, a second check valve and a second on-off valve in sequence; from the low-pressure steam source to the pressure matcher, the low-pressure steam inlet pipe is provided with a third check valve, a first regulating valve and a third on-off valve in sequence; and pressure measuring instruments are provided on the high-pressure steam inlet pipe, the low-pressure steam inlet pipe and the steam outlet pipe.

2. The steam supply system for the zero-level high-pressure heater according to claim 1 is characterized in that: A safety valve is provided on the steam outlet pipeline.

3. The steam supply system for the zero-level high-pressure heater according to claim 2 is characterized in that: A spare steam supply pipeline is provided between the second check valve and the safety valve, and a fourth on-off valve and a second regulating valve are provided on the spare steam supply pipeline. The fourth on-off valve is located close to the second check valve, and the second regulating valve is located close to the safety valve.

4. The steam supply system for the zero-level high-pressure heater according to claim 3 is characterized in that: The high-pressure steam source is from the high-pressure cylinder and / or the supplementary steam pipeline of the steam turbine, and the low-pressure steam source is from the medium-pressure cylinder and / or the low-pressure cylinder of the steam turbine.

5. The steam supply system for the zero-level high-pressure heater according to claim 4 is characterized in that: The steam outlet pipe is provided with three heating steam pressure measuring instruments near the No. 0 high-pressure heater, the high-pressure steam inlet pipe is provided with three high-pressure steam source pressure measuring instruments near the pressure matcher, and the low-pressure steam inlet pipe is provided with three low-pressure steam source pressure measuring instruments near the low-pressure cylinder.

6. The steam supply system for a zero-level high-pressure heater according to any one of claims 3 to 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, the first check valve and the third check valve are pneumatic check valves, the first regulating valve is a hydraulic fast-closing regulating valve, and the second regulating valve is a bypass regulating valve.

7. A steam supply method for a zero-level high-pressure heater steam supply system according to any one of claims 3 to 6, characterized in that: The following steps are involved: A. When the load of the generator set is high and the pressure of the high-pressure steam extracted from the high-pressure steam source meets the working conditions of the pressure matcher, the pressure matcher is started after the parameters are set, and the third on-off valve, the first regulating valve, the second on-off valve and the first on-off valve are opened in sequence, and the high-pressure steam is ejected at a high speed to produce a negative pressure effect, thereby sucking the low-pressure steam into the pressure matcher and mixing it. The mixed steam is transported from the steam outlet of the pressure matcher through the steam outlet pipeline to the zero-pressure heater; B. When the load of the generator set is low and the high-pressure steam pressure extracted from the high-pressure steam source does not meet the working conditions of the pressure matcher, close the third on-off valve, the second on-off valve and the first regulating valve, and open the fourth on-off valve, the first on-off valve and the second regulating valve in sequence. The high-pressure steam directly enters the steam outlet pipeline from the standby steam supply pipeline and is then transported to the No. 0 high-pressure heater.

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