A sequential control design method for preheating valve cavity of steam turbine

Abstract

The application provides a sequential control design method for a steam turbine preheating valve chamber, comprising the following steps: S1, first, an operator clicks a preheating valve chamber button to start a sequential control program; and S2, after the sequential control program starts, it is first determined whether a temperature measurement point TI1200 measurement value reaches a certain temperature. The sequential control design method for the steam turbine preheating valve chamber is based on a steam turbine control system, temperature and pressure measurement points are arranged on site, the measurement values collected by the measurement points on site are used for real-time determination, a shut-off valve XV1011 is controlled to be closed, and a steam electrodynamic valve is adjusted in real time, so that the steam pipeline and the steam turbine valve chamber are uniformly and stably heated, the valve chamber is preheated, the conditions for starting the steam turbine are met as soon as possible, the situation that the steam turbine starting process is affected by the quick closing of the valve due to the uneven heating caused by the fast heating speed of the valve chamber in the manual operation environment is avoided, the degree of automation of the equipment is improved, the steam use efficiency is improved, and the labor and time costs are saved.

Description

Technical Field

[0001] This invention relates to the field of preheating control of the valve chamber before cold start of a steam turbine, and particularly to a sequential control design method for the preheating valve chamber of a steam turbine. Background Technology

[0002] A steam turbine, also known as a steam engine, is a rotary steam power unit. High-temperature, high-pressure steam passes through a fixed nozzle, becomes an accelerated airflow, and is then injected onto the blades, causing the rotor, which is equipped with rows of blades, to rotate and perform work. Steam turbines are the main equipment in modern thermal power plants and are also used in the metallurgical industry, chemical industry, and ship propulsion systems.

[0003] The newly constructed air compressor unit in the plant project consists of a raw material air compressor, a steam turbine, and an air booster. When the steam turbine is started cold (i.e., the lower cylinder temperature is below 140℃), the main steam pipeline needs to be preheated first. After the pipeline reaches a certain temperature, the turbine's quick-closing valve is opened to preheat the valve chamber until the start-up conditions are met. The heating rate during the preheating process of the steam turbine valve chamber is strictly controlled. If the heating rate is too fast, the quick-closing valve will close, the valve chamber heating will stop, and the quick-closing valve needs to be opened again to restart the preheating of the valve chamber. Because the valve chamber heating process is manually controlled by the operator, uneven temperature rise and excessive speed often occur during the steam turbine start-up process, causing the quick-closing valve to close. This not only wastes manpower and affects the start-up progress but also wastes steam.

[0004] Therefore, it is necessary to provide a sequential control design method for the preheating valve chamber of a steam turbine to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention provides a sequential control design method for the preheating valve chamber of a steam turbine, which solves the problems of uneven temperature rise and excessively rapid temperature rise in the valve chamber that often occur during the start-up of steam turbines.

[0006] To solve the above-mentioned technical problems, the present invention provides a sequential control design method for a steam turbine preheating valve chamber, comprising:

[0007] S1. First, the operator clicks the preheating valve chamber button to start the sequential control program;

[0008] S2. After the sequential control program starts, it first determines that the temperature measurement value of temperature measuring point TI1200 has reached a certain temperature, and then opens the steam pipeline bypass valve XV1011.

[0009] S3. After a 5-minute delay, open the steam electric valve to heat the steam pipe before the quick-closing valve.

[0010] S4. When the temperature measuring point TI1011 reaches 490℃, close the steam electric valve and the auxiliary line shut-off valve XV1011. When the opening conditions of the quick-closing valve are met, the shutdown signal is reset and the quick-closing valve is opened to start preheating of the turbine valve chamber.

[0011] S5. When the signal of the quick-closing valve being fully open is returned, open the auxiliary line shut-off valve XV1011, and after a delay of 10 minutes, open the steam electric valve. At the same time, make real-time judgment on the temperature difference TDI1018. Once the valve chamber preheating is completed, the conditions for starting the machine are met.

[0012] The temperature difference TDI1018 is the theoretical temperature value obtained by converting the valve cavity pressure measuring point PI1012 after a series of conversions by consulting the saturated steam temperature table, and the actual temperature measuring point TI1013.

[0013] Preferably, both temperature measuring point TI1200 and temperature measuring point TI1011 are arranged in a three-point configuration at the same measuring point, with three instruments installed at one measuring point to return three measurement values.

[0014] Preferably, when all three instruments are measuring normally, the sequential control program takes the middle value of the three measurements for logical judgment; when one instrument fails, the sequential control program takes the lower value of the remaining two measurements as the judgment basis.

[0015] Preferably, the temperature measuring point TI1200 is a thermocouple measuring point with a range of 0~800℃.

[0016] Preferably, the temperature measuring point TI1011 is a resistance temperature measuring point with a range of 0~600℃.

[0017] Preferably, the pressure measuring point PI1012 is a current output type pressure transmitter with a current signal standard of 4~20mA and a range of 0~10MPa.

[0018] Preferably, the steam electric valve is an intelligent electric regulating valve with valve position opening feedback function, and the power source is 380VAC.

[0019] Preferably, the secondary line shut-off valve XV1011 is a shut-off valve with both fully open and fully closed functions.

[0020] Preferably, the quick-closing valve is a shut-off valve with fully open and fully closed functions, and the valve body is equipped with a valve position fully open and fully closed signal detection device.

[0021] Compared with related technologies, the sequential control design method for the preheating valve chamber of a steam turbine provided by this invention has the following advantages:

[0022] This invention provides a sequential control design method for a steam turbine preheating valve chamber. The sequential control program is based on the steam turbine control system. Temperature and pressure measuring points are arranged on-site. By judging the measured values ​​collected from the on-site equipment measuring points in real time, the shut-off valve XV1011 is controlled and the steam electric valve is adjusted in real time to achieve uniform and stable temperature rise of the steam pipeline and the steam turbine valve chamber, thus completing the valve chamber preheating and meeting the steam turbine start-up conditions as soon as possible. This avoids the situation where the valve chamber closes due to rapid temperature rise and uneven heating under manual operation, which may affect the steam turbine start-up process. In this way, the automation level of the equipment is improved, the steam utilization efficiency is increased, and labor and time costs are saved. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a preferred embodiment of the sequential control design method for a steam turbine preheating valve cavity provided by the present invention;

[0024] Figure 2 for Figure 1 The diagram shown is a logic diagram for converting the valve cavity temperature difference TDI1018.

[0025] Figure 3 for Figure 1 The diagram shows the sequential control logic of the turbine preheating valve chamber. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] Please refer to the following: Figure 1 , Figure 2 and Figure 3 ,in, Figure 1 This is a schematic diagram of a preferred embodiment of the sequential control design method for a steam turbine preheating valve cavity provided by the present invention; Figure 2 for Figure 1 The diagram shown is a logic diagram for converting the valve cavity temperature difference TDI1018. Figure 3 for Figure 1 The diagram shows the sequential control logic of the turbine preheating valve chamber. A sequential control design method for the turbine preheating valve chamber includes: A sequential control design method for the turbine preheating valve chamber includes:

[0028] S1. First, the operator clicks the preheating valve chamber button to start the sequential control program;

[0029] S2. After the sequential control program starts, it first determines that the temperature measurement value of temperature measuring point TI1200 has reached a certain temperature, and then opens the steam pipeline bypass valve XV1011.

[0030] S3. After a 5-minute delay, open the steam electric valve to heat the steam pipe before the quick-closing valve.

[0031] S4. When the temperature measuring point TI1011 reaches 490℃, close the steam electric valve and the auxiliary line shut-off valve XV1011. When the opening conditions of the quick-closing valve are met, the shutdown signal is reset and the quick-closing valve is opened to start preheating of the turbine valve chamber.

[0032] S5. When the signal of the quick-closing valve being fully open is returned, open the auxiliary line shut-off valve XV1011, and after a delay of 10 minutes, open the steam electric valve. At the same time, make real-time judgment on the temperature difference TDI1018. Once the valve chamber preheating is completed, the conditions for starting the machine are met.

[0033] TDI1018 is the temperature difference between the theoretical temperature value obtained by converting the valve cavity pressure measuring point PI1012 after a series of conversions and by querying the saturated steam temperature table, and the actual temperature measuring point TI1013.

[0034] Both temperature measuring points TI1200 and TI1011 are arranged in a three-point configuration, with three instruments installed at each measuring point, returning three measurement values.

[0035] The instrument measuring points TI1200, TI1011, TI1013, and PI1012 are all arranged in a three-point configuration at the same measuring point. Three identical instruments are installed at one measuring point, and three measurement values ​​are returned.

[0036] When all three instruments are measuring normally, the sequential control program takes the middle value of the three measurements for logical judgment. When one instrument fails, the sequential control program takes the lower value of the remaining two measurements as the basis for judgment.

[0037] The temperature measuring point TI1200 is a thermocouple-type temperature measuring point with a range of 0~800℃.

[0038] The temperature measuring point TI1011 is a resistance temperature detector (RTD) with a range of 0~600℃.

[0039] Temperature measuring points TI1011 and TI1013 are resistance temperature measuring points with a range of 0~600℃.

[0040] The pressure measuring point PI1012 is a current output type pressure transmitter with a current signal standard of 4~20mA and a range of 0~10MPa.

[0041] The steam electric valve is an intelligent electric regulating valve with valve position opening feedback function, and the power source is 380VAC.

[0042] The secondary line shut-off valve XV1011 is a shut-off valve with both fully open and fully closed functions.

[0043] The quick-closing valve is a shut-off valve with both fully open and fully closed functions, and the valve body is equipped with a valve position fully open and fully closed signal detection device.

[0044] Temperature measuring points TI1200, TI1011, and TI1013; pressure measuring point PI1012; adjustable steam electric valve MT1011; auxiliary line shut-off valve XV1011; quick-closing valve and accessories; and main steam regulating valve; sequential control program; one-button start-up automatic control function; based on the turbine control system; utilizing on-site temperature and pressure measuring points; and judging the measured values ​​of pressure and temperature measuring points in real time, the system completes the opening and closing of the auxiliary line shut-off valve under the control of the sequential control program and continuously adjusts the on-site steam electric valve. This ensures stable and uniform temperature rise in the steam pipeline before the valve chamber and during the preheating of the valve chamber, avoiding the repeated closure of the quick-closing valve due to uneven heating caused by manually controlling the valve chamber preheating rate, which affects the turbine start-up process.

[0045] Before a steam turbine can be started from a cold state, the valve chamber needs to be preheated. Only after the preheating meets the requirements can the main steam regulating valve be opened, and high-temperature, high-pressure steam be used to drive the turbine rotor to accelerate and start the turbine. Preheating of the turbine valve chamber requires a uniform temperature rise, and the heating rate cannot be too fast; otherwise, the quick-closing valve at the steam inlet of the valve chamber will close, and the preheating process will be interrupted. To meet these requirements, an automatic sequential control logic is designed to judge the collected temperature values ​​in real time, thereby ensuring uniform heating of the valve chamber.

[0046] Before a steam turbine is started from a cold state, the valve chamber needs to be preheated. Only after the conditions are met can the main steam regulating valve be opened, and the high-temperature and high-pressure steam is used to drive the turbine rotor to speed up and start the turbine.

[0047] Preheating of the turbine valve chamber requires uniform temperature rise within the chamber, and the heating rate should not be too fast, otherwise the quick-closing valve at the steam inlet of the valve chamber will close, and the preheating process will be interrupted.

[0048] To meet the above requirements, an automatic sequential control logic is designed to make real-time judgments on the collected temperature values, thereby ensuring uniform heating of the valve cavity.

[0049] After the sequential control program starts, it first checks the temperature measuring point TI1200. Once the temperature at this measuring point reaches 495℃, it opens the steam pipeline bypass valve XV1011 to preheat the downstream pipeline and balance the pressure on both sides of the steam electric valve. Then, it gradually increases the opening of the steam electric valve. When the temperature at measuring point TI1011 reaches 490℃, it closes XV1011 and the steam electric valve, resets the stop signal, and opens the quick-closing valve to preheat the valve chamber. After the quick-closing valve is fully open, it opens XV1011 to slowly heat the valve chamber. After a delay, it opens the steam electric valve and continues to increase its opening. At the same time, it monitors the valve chamber temperature difference TDI1018 in real time. Figure 2TDI1018, as shown, is the temperature difference between the theoretical temperature value obtained from valve chamber pressure measuring point PI1012 after a series of calculations and by querying the saturated steam temperature gauge (function block SSC), and the actual temperature measuring point TI1013. When TDI1018 is greater than or equal to 110K, the steam electric valve maintains its current opening and does not adjust further. It waits until TDI1018 is lower than 110K before increasing the opening again until the valve chamber preheating is complete, ready for startup. If TDI1018 suddenly reaches or exceeds 130K during this period, the quick-closing valve closes, the steam electric valve returns to a 15% opening, and after the quick-closing valve opening condition is met, the shutdown signal is reset and the quick-closing valve reopens to continue preheating the valve chamber.

[0050] The working principle of the sequential control design method for the preheating valve chamber of a steam turbine provided by this invention is as follows:

[0051] The turbine control screen has a soft button for "Preheating Valve Chamber". During cold start, when the operator clicks the button, the control program will proceed according to the specified sequence. Figure 3 The control logic begins execution. First, it checks the temperature measurement value at temperature measuring point TI1200, requiring the temperature at this measuring point to be greater than or equal to 495℃. Once this condition is met, it opens the steam pipeline bypass valve XV1011 to preheat the subsequent pipeline and balance the pressure on both sides of the steam electric valve. After a 5-minute delay, it opens the steam electric valve to heat the steam pipeline before the quick-closing valve, increasing its opening degree by 2% every 2 minutes, with a maximum opening limit of 55%. When the temperature measuring point TI1011 reaches 490℃, close the steam electric valve and XV1011. Once the opening conditions of the quick-closing valve are met, the shutdown signal is reset and the quick-closing valve is opened to begin preheating the turbine valve chamber. After the quick-closing valve fully opens signal returns, open XV1011. After a 10-minute delay, open the steam electric valve, increasing the opening by 1% every two minutes. Simultaneously, monitor the temperature difference TDI1018 in real time. When TDI1018 is below 110K, the steam electric valve continues to increase its opening as required. If TDI1018 is greater than or equal to 110K, the steam electric valve stops increasing its opening and maintains the current opening. Wait for the TDI1018 value to drop below 110K before increasing its opening again. Continue this cycle until the valve chamber preheating is complete and the turbine is ready for startup.

[0052] If TDI1018 suddenly reaches or exceeds 130K during the period, the quick-closing valve closes, the steam electric valve returns to 15% of its opening, and after the conditions for opening the quick-closing valve are met, the stop signal is reset and the quick-closing valve is reopened, and the sequential control program is entered again to continue preheating the valve chamber.

[0053] Compared with related technologies, the sequential control design method for the preheating valve chamber of a steam turbine provided by this invention has the following advantages:

[0054] This invention provides a sequential control design method for a steam turbine preheating valve chamber. The sequential control program is based on the steam turbine control system. Temperature and pressure measuring points are arranged on-site. By judging the measured values ​​collected from the on-site equipment measuring points in real time, the shut-off valve XV1011 is controlled and the steam electric valve is adjusted in real time to achieve uniform and stable temperature rise of the steam pipeline and the steam turbine valve chamber, thus completing the valve chamber preheating and meeting the steam turbine start-up conditions as soon as possible. This avoids the situation where the valve chamber closes due to rapid temperature rise and uneven heating under manual operation, which may affect the steam turbine start-up process. In this way, the automation level of the equipment is improved, the steam utilization efficiency is increased, and labor and time costs are saved.

[0055] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A sequential control design method for a steam turbine preheating valve chamber, characterized in that, include: S1. First, the operator clicks the preheating valve chamber button to start the sequential control program; S2. After the sequential control program starts, it first determines that the temperature measurement value of temperature measuring point TI1200 has reached a certain temperature, and then opens the steam pipeline bypass valve XV1011. S3. After a 5-minute delay, open the steam electric valve to heat the steam pipe before the quick-closing valve. S4. When the temperature measuring point TI1011 reaches 490℃, close the steam electric valve and the auxiliary line shut-off valve XV1011. When the opening conditions of the quick-closing valve are met, the shutdown signal is reset and the quick-closing valve is opened to start preheating of the turbine valve chamber. S5. When the signal of the quick-closing valve being fully open is returned, open the auxiliary line shut-off valve XV1011, and after a delay of 10 minutes, open the steam electric valve. At the same time, make real-time judgment on the temperature difference TDI1018. Once the valve chamber preheating is completed, the conditions for starting the machine are met. The temperature difference TDI1018 is the theoretical temperature value obtained by converting the valve cavity pressure measuring point PI1012 after a series of conversions by consulting the saturated steam temperature table, and the actual temperature measuring point TI1013.

2. The sequential control design method for a steam turbine preheating valve chamber according to claim 1, characterized in that, Both temperature measuring points TI1200 and TI1011 are arranged in a three-point configuration, with three instruments installed at each measuring point, returning three measurement values.

3. The sequential control design method for a steam turbine preheating valve chamber according to claim 2, characterized in that, When all three instruments are measuring normally, the sequential control program takes the middle value of the three measurements for logical judgment. When one instrument fails, the sequential control program takes the lower value of the remaining two measurements as the basis for judgment.

4. The sequential control design method for a steam turbine preheating valve chamber according to claim 1, characterized in that, The temperature measuring point TI1200 is a thermocouple-type temperature measuring point with a range of 0~800℃.

5. The sequential control design method for a steam turbine preheating valve chamber according to claim 1, characterized in that, The temperature measuring point TI1011 is a resistance temperature detector (RTD) with a range of 0~600℃.

6. The sequential control design method for a steam turbine preheating valve chamber according to claim 1, characterized in that, The pressure measuring point PI1012 is a current output type pressure transmitter with a current signal standard of 4~20mA and a range of 0~10MPa.

7. The sequential control design method for a steam turbine preheating valve chamber according to claim 1, characterized in that, The steam electric valve is an intelligent electric regulating valve with valve position opening feedback function, and the power source is 380VAC.

8. The sequential control design method for a steam turbine preheating valve chamber according to claim 1, characterized in that, The secondary line shut-off valve XV1011 is a shut-off valve with both fully open and fully closed functions.

9. The sequential control design method for a steam turbine preheating valve chamber according to claim 1, characterized in that, The quick-closing valve is a shut-off valve with both fully open and fully closed functions, and the valve body is equipped with a valve position fully open and fully closed signal detection device.

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