A drain control system for a gas-steam combined cycle unit

Abstract

The invention discloses a gas-steam combined cycle unit drain control system, comprising a first drain component comprising a first drain pipe, a first drain valve arranged between the first drain pipes, a first temperature detector arranged at the rear end pipe of the first drain pipe, and a first pressure detector arranged at the rear end pipe of the first drain pipe; a second drain component comprising a second drain pipe, a second drain valve, a second temperature detector, and a second pressure detector; a third drain component comprising a third drain pipe, a third drain valve, a third temperature detector, and a third pressure detector. By setting a drain control system, the opening and closing sequence of the drain valves is controlled, so that the problem of low efficiency and high gas consumption of the combined cycle unit in the start-up and shutdown stages caused by the opening and closing sequence of the drain valves is solved, and the drain pipes and drain valves are arranged in the waste heat boiler, the main steam pipe, and the turbine body of the combined cycle unit, so that the accumulated water in the pipes is discharged in time, and the startup safety of the unit is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of gas-steam combined cycle units, and in particular relates to a gas-steam combined cycle unit drain control system. Background Art

[0002] During the startup of the combined cycle unit, the pipes with lower temperatures cool the steam. When the steam temperature drops to its saturation temperature, part of the steam will condense into water. The condensed water will accumulate in the pipes and cause pipe water shock. If it enters the steam turbine, it will cause turbine water shock, which will seriously affect the safety of equipment operation. Therefore, drain pipes and drain pneumatic valves are installed in the waste heat boiler, main steam pipe, and turbine body of the combined cycle unit to drain the accumulated water in the pipes in time and improve the safety of unit startup.

[0003] In the existing technology of combined cycle unit drain system, the steam trap on the waste heat boiler side is opened with the ignition of the gas turbine as the opening condition. Since the steam trap is opened at the same time, the steam pressure in the steam pipeline is greatly reduced, and a false water level appears in the steam drum of the waste heat boiler, which is easy to trigger the high water level protection trip of the steam drum of the waste heat boiler; and when the waste heat boiler is cold started, since the waste heat boiler and the main steam pipeline are at normal pressure, the waste heat boiler drain is connected to the atmosphere, and the main steam pipeline is connected to the condenser. The drain valves of the main steam and the waste heat boiler are opened at the same time, forming a channel connecting the atmosphere and the condenser, causing the vacuum degree of the condenser to drop sharply, which is easy to trigger the low vacuum protection trip of the condenser; the steam trap on the waste heat boiler side uses the drain time as the closing condition. During the cold start of the unit, there is insufficient draining, which is easy to cause water accumulation in the pipeline and reduce the safety of the unit start-up; during the hot start of the unit, there is excessive draining, resulting in a high desalted water replenishment rate, reducing the economic efficiency of the unit start-up.

[0004] The steam trap on the main steam pipeline side uses the condenser vacuum as the opening condition, that is, the steam trap opens after the condenser establishes a vacuum. When the unit is shut down, the steam trap remains open. Due to the continuous extraction of air by the condenser vacuum, the metal temperature of the main steam pipeline drops significantly, and the insulation effect becomes worse; the steam trap on the main steam pipeline side uses the turbine load as the closing condition. During the cold start-up of the unit, since the heating surface of the low-pressure system of the waste heat boiler is at the tail end of the waste heat boiler, the steam in the low-pressure system heats up and pressurizes more slowly than the high and medium pressure systems. The low-pressure main regulating valve meets the steam inlet conditions only after the turbine is connected to the grid and the load is increased. If the turbine load is increased too quickly, the low-pressure main steam pipe steam trap will be closed before the low-pressure main regulating valve is opened, and the system pipeline will not be fully drained, which may easily cause water to enter the low-pressure cylinder of the turbine.

[0005] During the hot start-up of the unit, the opening of some drains will cause the metal temperature of the pipeline to drop, prolong the start-up time of the unit, and reduce the start-up economy of the unit. Summary of the invention

[0006] The present application provides a gas-steam combined cycle unit drain control system. By setting up a drain control system, the opening and closing sequence of the drain valve is controlled, thereby solving the problems of low efficiency and high gas consumption in the start-up and shutdown stages of the combined cycle unit caused by the opening and closing sequence of the drain valve. Drain pipes and drain valves are set in the waste heat boiler, main steam pipe, and turbine body of the combined cycle unit, so that the accumulated water in the pipes is drained away in time, thereby improving the safety of the unit startup.

[0007] The technical solution provided by this application is:

[0008] A gas-steam combined cycle unit drain control system, comprising:

[0009] A waste heat boiler component, wherein the waste heat boiler component includes a superheater;

[0010] A steam turbine component, wherein the steam turbine component comprises a main steam valve;

[0011] A main steam pipeline component, the main steam pipeline component is arranged between the outlet valve of the superheater and the main steam valve;

[0012] A first drain component, wherein the first drain component is arranged on one side of the waste heat boiler component;

[0013] a second drain component, the second drain component being arranged on one side of the main steam pipe component;

[0014] a third drain component, the third drain component being arranged on one side of the steam turbine component;

[0015] The first drain component includes a first drain pipe, a first drain valve disposed between the first drain pipes, a first temperature detector disposed at the rear end of the first drain pipe, and a first pressure detector disposed at the rear end of the first drain pipe;

[0016] The second drain component includes a second drain pipe, a second drain valve disposed between the second drain pipes, a second temperature detector disposed at the rear end of the second drain pipe, and a second pressure detector disposed at the rear end of the second drain pipe;

[0017] The third drain component includes a third drain pipe, a third drain valve disposed between the third drain pipes, a third temperature detector disposed at the rear end of the third drain pipe, and a third pressure detector disposed at the rear end of the third drain pipe.

[0018] The pressure levels measured by the pressure gauge are divided into three categories: high, medium and low.

[0019] Among them, the first drain component is used to drain the accumulated water in the waste heat boiler components; the second drain component is used to drain the accumulated water in the main steam pipe components; the third drain component is used to drain the accumulated water in the turbine components; the temperature detector is used to monitor the temperature changes after the drain valve.

[0020] In the present invention, the first steam trap monitors the temperature and pressure change signals in the waste heat boiler components through the first thermometer and the first pressure gauge, thereby opening and closing the first steam trap; the second steam trap monitors the temperature and pressure change signals in the main steam pipeline components through the second thermometer and the second pressure gauge, thereby opening and closing the second steam trap; the third steam trap monitors the temperature and pressure change signals in the main steam pipeline components through the third thermometer and the third pressure gauge, thereby opening and closing the third steam trap, wherein the program for processing the pressure and temperature signals in the steam trap control system to open and close the steam trap is implemented through the existing program, and the specific pressure and temperature value limit settings can be set according to the actual operation of the combined cycle unit. Through the above settings, it can be effectively guaranteed that the accumulated water in the steam trap pipes in the waste heat boiler components, main steam pipeline components, and turbine components of the combined cycle unit is drained away in time, the safety of the unit startup is improved, and the economic efficiency of the unit startup is effectively reduced.

[0021] Furthermore, the opening of the first steam trap is initiated by the combined action of the engine ignition signal and the pressure signal measured by the first pressure gauge, and the first steam trap is opened in sequence from small to large according to the pressure value measured by the first pressure gauge. This arrangement can effectively avoid a sudden drop in steam pressure caused by the simultaneous opening of the first steam traps in the waste heat boiler component, thereby preventing a false water level from appearing in the steam drum of the waste heat boiler component, and preventing a sudden drop in steam pressure from causing an increase in the flow rate of the steam-water mixture in the first steam trap, thereby causing water shock in the first steam trap of the waste heat boiler component, thereby effectively ensuring stable pressure and improving the safety of unit startup.

[0022] Furthermore, the first steam trap is closed by the combined effect of the temperature value measured by the first thermometer and the pressure signal measured by the first pressure gauge, and the closing order of the first steam trap is based on the distance between the first steam trap and the main steam pipe component, from far to near; wherein, the existing program obtains the temperature value measured by the first thermometer and the pressure value measured by the first pressure gauge and calculates the superheat of the steam in the first steam trap, and then closes the steam trap based on the combined effect of the pressure value measured by the first pressure gauge and the superheat information. Through this setting, insufficient drainage during the cold start-up of the unit and excessive drainage during the hot start-up are effectively avoided, and at the same time, water accumulated in the pipeline is prevented from flowing to the rear pipeline, effectively ensuring the drainage effect.

[0023] Furthermore, the opening of the second steam trap is initiated by the combined action of the engine ignition signal and the pressure signal measured by the second pressure gauge, and the opening order of the second steam trap is from near to far according to the distance between the second steam trap and the waste heat boiler component. Through this arrangement, it is effectively avoided that the air in the pipeline enters the condenser at the same time due to the main steam pipeline steam trap being opened at the same time, thereby reducing the condenser vacuum and ensuring the condenser vacuum degree.

[0024] Furthermore, the second steam trap is closed by the combined effect of the engine flameout signal and the pressure signal measured by the second pressure gauge, wherein the pressure value measured by the second pressure gauge corresponds to the valve opening of the steam turbine component, that is, the second steam trap is closed by the combined effect of the engine flameout signal and the valve opening of the steam turbine component. This arrangement can effectively avoid the situation where the cylinder of the pressure level of the steam turbine component does not enter steam, resulting in the second steam trap being closed and insufficient drainage, causing water to enter the steam turbine component. When the unit is shut down and vacuum is maintained, the drainage of the main steam pipe component is closed to slow down the temperature drop of the main steam pipe component and improve the thermal insulation effect of the pipeline.

[0025] Furthermore, the opening of the third steam trap is initiated by a combustion engine ignition signal.

[0026] Furthermore, the third steam trap is closed by the pressure signal measured by the third pressure gauge, wherein the pressure value measured by the third pressure gauge corresponds to the regulating valve opening of the steam turbine component, that is, the third steam trap is closed by the regulating valve opening of the steam turbine component.

[0027] Furthermore, the second steam trap and the third steam trap are opened simultaneously with the temperature value measured by the third thermometer being 20 degrees Celsius greater than the temperature value measured by the second thermometer as a simultaneous opening condition. Through this setting, when the second steam trap and the third steam trap are opened simultaneously, the temperature reduction amplitude measured by the third thermometer can be effectively reduced, the warm-up time of the unit can be effectively shortened, and the startup economy of the unit can be improved.

[0028] Furthermore, the temperature detector is arranged at the rear end of the drain pipe 0.4-0.6 m away from the drain valve, which effectively improves the accuracy of the detected temperature.

[0029] Beneficial effects of the present invention:

[0030] By setting up a drain control system to control the opening and closing sequence of the drain valve, the problem of low efficiency and high gas consumption in the start-up and shutdown stages of the combined cycle unit caused by the opening and closing sequence of the drain valve is solved. Drain pipes and drain valves are set in the waste heat boiler, main steam pipe, and turbine body of the combined cycle unit to drain the accumulated water in the pipes in time, thereby improving the safety of unit startup. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of the present invention;

[0032] Figure 2 This is a control logic diagram for opening the first steam trap in the present invention;

[0033] Figure 3 This is a control logic diagram for closing the first steam trap in the present invention;

[0034] Figure 4 This is a control logic diagram for opening the second steam trap in the present invention;

[0035] Figure 5 This is a control logic diagram for closing the second steam trap in the present invention;

[0036] Figure 6 This is a control logic diagram for opening the third steam trap in the present invention;

[0037] Figure 7 This is a control logic diagram for closing the third steam trap in the present invention.

[0038] Markings in the figure: waste heat boiler component 1, superheater 11; steam turbine component 2, main steam valve 21; main steam pipe component 3; first drain component 4, first drain pipe 41, first drain valve 42, first temperature detector 43, first pressure detector 44; second drain component 5, second drain pipe 51, second drain valve 52, second temperature detector 53, second pressure detector 54; third drain component 6, third drain pipe 61, third drain valve 62, third temperature detector 63, third pressure detector 64. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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. Example

[0040] To facilitate those skilled in the art to understand the present invention, the present invention will be further described in detail below in conjunction with specific embodiments and drawings.

[0041] like Figure 1-7As shown in the figure, a gas-steam combined cycle unit drain control system provided by an embodiment of the present invention controls the opening and closing sequence of the drain valve by setting a drain control system, thereby solving the problems of low efficiency and high gas consumption of the combined cycle unit in the start-up and shutdown stages caused by the opening and closing sequence of the drain valve, and realizing that drain pipes and drain valves are set in the waste heat boiler, main steam pipe, and turbine body of the combined cycle unit, so that the accumulated water in the pipe is drained away in time, thereby improving the safety of the unit startup.

[0042] The technical solution provided by this application is:

[0043] A gas-steam combined cycle unit drain control system, comprising:

[0044] A waste heat boiler component 1, wherein the waste heat boiler component 1 includes a superheater 11;

[0045] A steam turbine component 2, wherein the steam turbine component 2 includes a main steam valve 21;

[0046] A main steam pipeline component 3, wherein the main steam pipeline component 3 is provided between the outlet valve of the superheater 11 and the main steam valve 21;

[0047] A first drain component 4, wherein the first drain component 4 is disposed on one side of the waste heat boiler component 1;

[0048] A second drain component 5, wherein the second drain component 5 is arranged on one side of the main steam pipe component 3;

[0049] A third drain component 6, wherein the third drain component 6 is disposed on one side of the steam turbine component 2;

[0050] The first drain component 4 includes a first drain pipe 41, a first drain valve 42 disposed between the first drain pipes, a first temperature detector 43 disposed at the rear end of the first drain pipe, and a first pressure detector 44 disposed at the rear end of the first drain pipe;

[0051] The second drain component 5 includes a second drain pipe 51, a second drain valve 52 disposed between the second drain pipes, a second temperature detector 53 disposed at the rear end of the second drain pipe, and a second pressure detector 54 disposed at the rear end of the second drain pipe;

[0052] The third drain component 6 includes a third drain pipe 61, a third drain valve 62 disposed between the third drain pipes, a third temperature detector 63 disposed at the rear end of the third drain pipe, and a third pressure detector 64 disposed at the rear end of the third drain pipe.

[0053] The pressure levels measured by the pressure gauge are divided into three categories: high, medium and low.

[0054] Among them, the first drain component 4 is used to drain the accumulated water in the waste heat boiler component 1; the second drain component 5 is used to drain the accumulated water in the main steam pipe component 3; the third drain component 6 is used to drain the accumulated water in the turbine component 2; the temperature detector is used to monitor the temperature change after the drain valve.

[0055] In the present invention, the first steam trap 42 monitors the temperature and pressure change signals in the waste heat boiler component 1 through the first thermometer 43 and the first pressure gauge 44, thereby opening and closing the first steam trap 42; the second steam trap 52 monitors the temperature and pressure change signals in the main steam pipeline component 3 through the second thermometer 53 and the second pressure gauge 54, thereby opening and closing the second steam trap 52; the third steam trap 62 monitors the temperature and pressure change signals in the main steam pipeline component 3 through the third thermometer 63 and the third pressure gauge 64, thereby opening and closing the third steam trap 62, wherein the program for processing the pressure and temperature signals in the steam trap control system to open and close the steam trap is realized through the existing program, and the specific pressure and temperature value limit settings can be set according to the actual operation of the combined cycle unit. Through the above settings, it can effectively ensure that the accumulated water in the steam trap pipes in the waste heat boiler component 1, the main steam pipeline component 3, and the turbine component 2 of the combined cycle unit is discharged in time, improve the safety of the unit startup, and effectively reduce the unit startup economy.

[0056] Furthermore, the opening of the first steam trap 42 is initiated by the combined action of the engine ignition signal and the pressure signal measured by the first pressure gauge 44. The first steam trap 42 is opened in sequence from small to large according to the pressure value measured by the first pressure gauge 44. This arrangement effectively avoids a sudden drop in steam pressure caused by the simultaneous opening of the first steam traps 42 in the waste heat boiler component, thereby preventing a false water level from appearing in the steam drum of the waste heat boiler component 1, and preventing a sudden drop in steam pressure from causing an increase in the flow rate of the steam-water mixture in the first steam trap 41, thereby causing water shock in the first steam trap 41 of the waste heat boiler component. This effectively ensures pressure stability and improves the safety of unit startup.

[0057] Further, the first steam trap 42 is closed by the combined effect of the temperature value measured by the first thermometer 43 and the pressure signal measured by the first pressure meter 44. The closing order of the first steam trap 42 is based on the distance between the first steam trap 42 and the main steam pipe component 3, from far to near. The existing program obtains the temperature value measured by the first thermometer 42 and the pressure value measured by the first pressure meter 44 and calculates the superheat of the steam in the first steam trap 41, and then closes it based on the pressure value measured by the first pressure meter 44 and the superheat information. Through this setting, insufficient drainage during the cold start-up of the unit and excessive drainage during the hot start-up are effectively avoided, and at the same time, water accumulated in the pipeline is prevented from flowing to the rear pipeline, effectively ensuring the drainage effect.

[0058] Furthermore, the opening of the second steam trap 52 is initiated by the combined action of the engine ignition signal and the pressure signal measured by the second pressure gauge 54. The opening order of the second steam trap 52 is based on the distance between the second steam trap and the waste heat boiler component 1 from near to far. Through this arrangement, it is effectively avoided that the second steam trap 52 in the main steam pipeline component is opened at the same time, and the air in the pipeline enters the condenser at the same time, causing the condenser vacuum to decrease, thereby ensuring the condenser vacuum degree.

[0059] Further, the second steam trap 52 is closed by the combined effect of the engine flameout signal and the pressure signal measured by the second pressure gauge 54, wherein the pressure value measured by the second pressure gauge 54 corresponds to the valve opening of the steam turbine component 2, that is, the second steam trap 51 is closed by the combined effect of the engine flameout signal and the valve opening of the steam turbine component 2. This arrangement can effectively avoid the situation where the cylinder of the pressure level of the steam turbine component 2 does not enter steam, resulting in the second steam trap 52 being closed and insufficient drainage, causing water to enter the steam turbine component 2. When the unit is shut down and vacuum is maintained, the drainage of the main steam pipe component 3 is closed to slow down the temperature drop of the main steam pipe component 3 and improve the pipeline insulation effect.

[0060] Furthermore, the opening of the third steam trap 62 is initiated by a combustion engine ignition signal.

[0061] Furthermore, the third steam trap 62 is closed by the pressure signal measured by the third pressure gauge 64, wherein the pressure value measured by the third pressure gauge 64 corresponds to the regulating valve opening of the steam turbine component 1, that is, the third steam trap 62 is closed by the regulating valve opening of the steam turbine component 1.

[0062] Furthermore, the second steam trap 52 and the third steam trap 62 are opened simultaneously with the temperature value measured by the third thermometer 63 being 20 degrees Celsius greater than the temperature value measured by the second thermometer 53 as a simultaneous opening condition. Through this setting, when the second steam trap 52 and the third steam trap 62 are opened simultaneously, the temperature reduction amplitude measured by the third thermometer 63 can be effectively reduced, the warm-up time of the unit can be effectively shortened, and the startup economy of the unit can be improved.

[0063] Furthermore, the temperature detector is arranged at the rear end of the drain pipe 0.4-0.6 m away from the drain valve, which effectively improves the accuracy of the detected temperature.

[0064] The following table shows the changes in the temperature values ​​measured by the third temperature detector before and after the optimization of the hydrophobic control system:

[0065]

[0066] It can be clearly seen from the above table that the decrease in the temperature value measured by the third temperature sensor during the startup process is effectively reduced, the unit warm-up time is effectively shortened, and the unit startup economy is improved.

[0067] Beneficial effects of the present invention:

[0068] By setting up a drain control system to control the opening and closing sequence of the drain valve, the problem of low efficiency and high gas consumption in the start-up and shutdown stages of the combined cycle unit caused by the opening and closing sequence of the drain valve is solved. Drain pipes and drain valves are set in the waste heat boiler, main steam pipe, and turbine body of the combined cycle unit to drain the accumulated water in the pipes in time, thereby improving the safety of unit startup.

[0069] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0070] In addition, it should be understood that although this specification is described in accordance with the implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. It should be noted that the technical features not described in detail in the present invention can be realized by any existing technology.

Claims

1. A gas-steam combined cycle unit drain control system, characterized in that: Included are: A waste heat boiler component, wherein the waste heat boiler component includes a superheater; A steam turbine component, wherein the steam turbine component comprises a main steam valve; A main steam pipeline component, the main steam pipeline component is arranged between the outlet valve of the superheater and the main steam valve; A first drain component, wherein the first drain component is arranged on one side of the waste heat boiler component; a second drain component, the second drain component being arranged on one side of the main steam pipe component; a third drain component, the third drain component being arranged on one side of the steam turbine component; The first drain component includes a first drain pipe, a first drain valve disposed on the first drain pipe, a first temperature detector disposed on the rear end of the first drain pipe, and a first pressure detector disposed on the rear end of the first drain pipe; The second drain component includes a second drain pipe, a second drain valve disposed on the second drain pipe, a second temperature detector disposed on the rear end of the second drain pipe, and a second pressure detector disposed on the rear end of the second drain pipe; The third drain component includes a third drain pipe, a third drain valve disposed on the third drain pipe, a third temperature detector disposed on the rear end of the third drain pipe, and a third pressure detector disposed on the rear end of the third drain pipe; The opening of the first steam trap is initiated by the combined action of the engine ignition signal and the pressure signal measured by the first pressure gauge, and the first steam trap is opened in sequence from small to large according to the pressure value measured by the first pressure gauge; The first steam trap is closed by the combined effect of the temperature value measured by the first temperature detector and the pressure signal measured by the first pressure detector. The first steam trap is closed in sequence from far to near according to the distance between the first steam trap and the main steam pipeline component. The opening of the second steam trap is initiated by the combined action of the engine ignition signal and the pressure signal measured by the second pressure gauge. The opening sequence of the second steam trap is from near to far according to the distance between the second steam trap and the waste heat boiler component.

2. A gas-steam combined cycle unit drain control system according to claim 1, characterized in that: The second steam trap is closed by the combined effect of a flameout signal of the combustion engine and a pressure signal measured by the second pressure measuring device.

3. A gas-steam combined cycle unit drain control system according to claim 1, characterized in that: The opening of the third steam trap is initiated by a combustion engine ignition signal.

4. A gas-steam combined cycle unit drain control system according to claim 3, characterized in that: The third steam trap is closed by the pressure signal measured by the third pressure sensor.

5. A gas-steam combined cycle unit drain control system according to claim 1, characterized in that: The second steam trap and the third steam trap are opened simultaneously with the temperature value measured by the third temperature detector being 20 degrees Celsius greater than the temperature value measured by the second temperature detector as a simultaneous opening condition.

6. A gas-steam combined cycle unit drain control system according to claim 1, characterized in that: The temperature detector is arranged at the rear end of the drain pipe 0.4-0.6m away from the drain valve.

7. A gas-steam combined cycle unit drain control system according to claim 1, characterized in that: The pressure levels measured by the pressure gauge are divided into three categories: high, medium and low.

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