Method for preventing water impact on 9e unit steam turbine

Abstract

The application discloses a method for preventing water impact of a 9E unit steam turbine, which comprises the following steps: according to a historical curve, when the gas turbine load is reduced to 40 MW, the TTXM is about 430 DEG C; when the gas turbine TTXM is reduced by more than 100 DEG C, the main steam temperature parameter of the waste heat boiler will certainly change by more than 50 DEG C; therefore, the relationship between the gas turbine load and the exhaust gas temperature is comprehensively considered, a gas turbine partial load shedding judgment program is set on the basis of preventing misoperation, which is used as the first layer protection for preventing the steam temperature of the steam turbine from being reduced by more than 50 DEG C within 10 min, the change of the main steam temperature of the steam turbine directly indicates whether the steam turbine cylinder is subjected to water impact, therefore, a protection program for judging the sharp reduction of the main steam temperature needs to be set, the water impact protection program of the steam turbine is optimized, the protection program of the steam turbine is improved, and the major safety hazard of the equipment is eliminated, and the effect is remarkable.

Description

Technical Field

[0001] This invention relates to the field of steam turbine technology for 9E units, specifically a method for preventing water hammer in 9E unit steam turbines. Background Technology

[0002] If the temperature of the main or reheat steam suddenly drops by 50°C within 10 minutes during normal operation of the unit, it is considered water hammer. Water hammer causes great damage to the steam turbine and the unit should be shut down immediately.

[0003] However, there are difficulties in implementing the above functions because:

[0004] (1) As a real-time control system, the DCS system can only process real-time data and cannot retrieve historical data for logical operations. It is quite difficult to save all temperature data within 10 minutes and determine whether the temperature has dropped by 50 degrees.

[0005] (2) If the temperature deviation between a fixed time point and the time point 10 minutes ago can be achieved through special processing such as time delay, there is no clear method for calculating the situation where the steam temperature has dropped by 50 degrees within 8 minutes, 5 minutes, 1 minute, etc.

[0006] Therefore, we propose a method to prevent water hammer in the turbine of Unit 9E to solve the problems mentioned above. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preventing water hammer in the turbine of the 9E unit, so as to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for preventing water hammer in the turbine of Unit 9E is proposed. Based on historical curves, when the gas turbine load drops to 40 MW, the TTXM (Total Turbine Temperature) is approximately 430 °C. When the gas turbine TTXM drops by more than 100 °C, it will definitely affect the main steam temperature parameter of the waste heat boiler by more than 50 °C. Taking into account the relationship between gas turbine load and flue gas temperature, and to prevent false tripping, a gas turbine partial load shedding judgment procedure is set up as the first layer of protection to prevent the steam temperature from dropping by 50 °C within 10 minutes. The specific method is as follows:

[0010] (1) If the gas turbine load drops from above 80MW to below 40MW within 60s and remains below 40MW for 20s, the gas turbine control system will issue a “gas turbine load shedding” alarm.

[0011] (2) Within 60s, the exhaust gas temperature TTXM of the gas turbine drops from above 530 ℃ to below 430 ℃, and remains below 430 ℃ for 20s. The gas turbine control system issues an alarm for "exhaust gas temperature dropping too fast".

[0012] (3) To prevent signal failure and protection malfunction, when the gas turbine has a "partial load shedding" alarm and a "flue gas temperature drops too fast" alarm, the gas turbine Mark VIe control system will issue a trip turbine command.

[0013] As a further aspect of the present invention, the change in the main steam temperature of the turbine directly indicates whether the turbine cylinder is subjected to water impact, therefore a protection program for judging a sharp drop in the main steam temperature needs to be set.

[0014] As a further aspect of the present invention, the method of the protection procedure is as follows: the temperature measuring points involved in the turbine protection are: steam temperature measuring point TE2101 before the main steam electric valve, steam temperature measuring point TE2102 before the left main steam shut-off valve; and steam temperature measuring point TE2105 before the right main steam shut-off valve.

[0015] (1) Compare the current values ​​of the above 3 temperature measuring points with the signal values ​​1 min, 2 min, 3 min, ..., 10 min ago. If the temperature values ​​of 2 or more measuring points drop by more than 30°C, an alarm for "main steam temperature dropping too fast" will be issued.

[0016] (2) Compare the current values ​​of the above 3 temperature measuring points with the signal values ​​1 min, 2 min, 3 min, ..., 10 min ago. If the temperature values ​​of 2 or more measuring points drop by more than 50°C, then issue "Alarm 2 for main steam temperature dropping too fast" and trip the steam turbine at the same time.

[0017] As a further aspect of the present invention: the gas turbine Mark VIe control system consists of two parts: hardware and software. The hardware part includes a computer and its peripherals for monitoring, a control cabinet, various I / O cards and terminal boards, a communication network system and corresponding equipment, field sensors, and various connecting cables. The software part includes the graphics display system CIMPLICITY and the configuration software GETOOLBOX.

[0018] As a further aspect of the present invention: the control cabinet has dimensions of 1350mm×2400mm×900mm, and is equipped with a single-module or three-module redundant control module, a protection module and a power distribution module. The control module is connected to a remote I / O cabinet via I / ONET.

[0019] As a further aspect of the present invention: the communication network system is a hierarchical network structure, which is divided into four layers from top to bottom: enterprise-level control layer, monitoring-level control layer, process control layer and I / O control layer.

[0020] As a further aspect of the present invention: the enterprise-level control layer is the highest layer in the entire network system, providing the interface between the Mark Vee control system and the DCS control system.

[0021] As a further aspect of the present invention: the monitoring-level control layer provides an interface between the human-machine interface and the control server, and also realizes multiple functions such as historical data collection, remote monitoring and vibration analysis.

[0022] As a further aspect of the present invention: the process control level controls the field equipment to ensure the continuous operation of the unit; the I / O control layer is used for data communication between the microprocessor and various I / O cards and remote cabinets.

[0023] Compared with the prior art, the beneficial effects of the present invention are: the method for preventing water hammer in the turbine of the 9E unit improves the protection program of the turbine by optimizing the protection program for preventing water hammer in the turbine, eliminates major safety hazards of the equipment, and has significant effects. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the method for preventing water hammer in the turbine of Unit 9E in this invention. Detailed Implementation

[0025] In one embodiment, such as Figure 1 As shown, a method to prevent water hammer in the turbine of Unit 9E includes, according to historical curves, when the gas turbine load drops to 40 MW, the TTXM is about 430 ℃; when the gas turbine TTXM drops by more than 100 ℃, it will definitely affect the main steam temperature parameter of the waste heat boiler by more than 50 ℃.

[0026] Therefore, taking into account the relationship between gas turbine load and exhaust gas temperature, a gas turbine partial load shedding judgment procedure is set up to prevent malfunctions, which serves as the first layer of protection for the steam turbine to prevent the steam temperature from dropping by 50°C within 10 minutes.

[0027] It also includes the fact that changes in the main steam temperature of the turbine directly indicate whether the turbine cylinder is being impacted by water, so a protection program is needed to detect a sharp drop in the main steam temperature.

[0028] The existing ABB Symphony control system does not have corresponding function codes or data registers to store the highest value within 10 minutes. It can only use the existing function codes to edit and develop protection programs to detect a sharp drop in the main steam temperature.

[0029] The specific methods for the first layer of protection are as follows:

[0030] (1) If the gas turbine load drops from above 80MW to below 40MW within 60s and remains below 40MW for 20s, the gas turbine control system will issue a “gas turbine load shedding” alarm.

[0031] (2) Within 60s, the exhaust gas temperature TTXM of the gas turbine drops from above 530 ℃ to below 430 ℃, and remains below 430 ℃ for 20s. The gas turbine control system issues an alarm for "exhaust gas temperature dropping too fast".

[0032] (3) In order to prevent signal failure and protection malfunction, when the gas turbine has a "partial load shedding" alarm and a "flue gas temperature drops too fast" alarm at the same time (that is, in order to prevent protection malfunction, 1 and 2 must occur at the same time to be considered as possibly causing water hammer in the turbine), the gas turbine Mark VIe control system will issue a trip turbine command.

[0033] The protection procedure is as follows: The temperature measuring points involved in the turbine protection are: steam temperature measuring point TE2101 before the main steam electric valve, steam temperature measuring point TE2102 before the left main steam shut-off valve; and steam temperature measuring point TE2105 before the right main steam shut-off valve.

[0034] (1) Compare the current values ​​of the above 3 temperature measuring points with the signal values ​​1 min, 2 min, 3 min, ..., 10 min ago. If the temperature values ​​of 2 or more measuring points drop by more than 30°C, an alarm for "main steam temperature dropping too fast" will be issued.

[0035] (2) Compare the current values ​​of the above 3 temperature measuring points with the signal values ​​1 min, 2 min, 3 min, ..., 10 min ago. If the temperature values ​​of 2 or more measuring points drop by more than 50°C, then issue "Alarm 2 for main steam temperature dropping too fast" and trip the steam turbine at the same time.

[0036] This invention improves the turbine's protection program by optimizing the turbine's water hammer prevention procedure, thereby eliminating major safety hazards and achieving significant results.

[0037] The Mark VIe control system for gas turbines consists of two parts: hardware and software. The hardware part includes a computer and its peripherals for monitoring, a control cabinet, various I / O cards and terminal blocks, a communication network system and corresponding equipment, field sensors, and various connecting cables. The software part includes the CIMPLICITY graphical display system and the GETOOLBOX configuration software.

[0038] The control cabinet measures 1350mm × 2400mm × 900mm. It houses single-module or triple-module redundant control modules, protection modules, and power distribution modules. The control modules are connected to remote I / O cabinets via I / ONET. The communication network system employs a hierarchical network structure, with each layer using standard network components and protocols, greatly simplifying system integration between different platforms and improving reliability and maintainability. The communication network system is divided into four layers from top to bottom: enterprise-level control layer, monitoring-level control layer, process control layer, and I / O control layer. The enterprise-level control layer is the highest layer in the entire network system, providing the interface between the Mark VIE control system and the DCS control system. The monitoring-level control layer provides the interface between the human-machine interface and the control server, and also realizes various functions such as historical data collection, remote monitoring, and vibration analysis. The process control layer controls field equipment to ensure continuous operation of the unit. The I / O control layer is used for data communication between the microprocessor, various I / O cards, and remote cabinets.

[0039] The Mark-VIe side logic is as follows:

[0040] Signal names and settings to be added

[0041] KDWATT1: Load reduction limit constant, set at 80MW;

[0042] KDWATT2: Load reduction limit constant, set at 40MW;

[0043] LKDWATT1Y: Load descent delay constant, set to 60s;

[0044] LKDWATT2Y: Load descent delay constant, set to 20s;

[0045] KTTXM1: Exhaust temperature drop limiting constant, set at 530℃;

[0046] KTTXM2: Exhaust temperature drop limiting constant, set at 430℃;

[0047] LKTTXM1Y: Exhaust temperature drop delay constant, set to 60s;

[0048] LKTTXM2Y: Exhaust temperature drop delay constant, set to 20s;

[0049] LLOADREJECTION_ALM: Gas turbine load shedding alarm;

[0050] LTTXM_ALM: Alarm indicating excessively rapid drop in exhaust gas temperature;

[0051] L4TT1: Gas turbine load shedding and turbine tripping command.

[0052] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preventing water hammer in the turbine of a 9E unit, characterized in that, Based on historical curves, when the gas turbine load drops to 40 MW, the TTXM (Total Temperature Measured by the turbine) is approximately 430 ℃. When the gas turbine TTXM drops by more than 100 ℃, it will definitely affect the main steam temperature parameter of the waste heat boiler, causing a change of more than 50 ℃. Taking into account the relationship between the gas turbine load and the flue gas temperature, and to prevent false tripping, a gas turbine partial load shedding judgment procedure is set up as the first layer of protection to prevent the steam temperature from dropping by 50 ℃ within 10 minutes. The specific method is as follows: (1) If the gas turbine load drops from above 80MW to below 40MW within 60s and remains below 40MW for 20s, the gas turbine control system will issue a "gas turbine shedding part of the load" alarm. (2) Within 60s, the exhaust gas temperature TTXM of the gas turbine drops from above 530 ℃ to below 430 ℃, and remains below 430 ℃ for 20s. The gas turbine control system issues an alarm for "exhaust gas temperature dropping too fast". (3) To prevent signal failure and protection malfunction, when the gas turbine has a "partial load shedding" alarm and a "flue gas temperature drops too fast" alarm, the gas turbine Mark VIe control system will issue a trip turbine command.

2. The method for preventing water hammer in the turbine of Unit 9E according to claim 1, characterized in that, It also includes a protection program that detects a sharp drop in the main steam temperature of the turbine, as the change in the main steam temperature directly indicates whether the turbine cylinder is being impacted by water.

3. The method for preventing water hammer in the turbine of Unit 9E according to claim 2, characterized in that, The protection procedure is as follows: The temperature measuring points involved in the turbine protection are: steam temperature measuring point TE2101 before the main steam electric valve, steam temperature measuring point TE2102 before the left main steam shut-off valve, and steam temperature measuring point TE2105 before the right main steam shut-off valve. (1) Compare the current values ​​of the above 3 temperature measuring points with the signal values ​​1 min, 2 min, 3 min, ..., 10 min ago. If the temperature values ​​of 2 or more measuring points drop by more than 30°C, an alarm for "main steam temperature dropping too fast" will be issued. (2) Compare the current values ​​of the above 3 temperature measuring points with the signal values ​​1 min, 2 min, 3 min, ..., 10 min ago. If the temperature values ​​of 2 or more measuring points drop by more than 50°C, then issue "Alarm 2 for main steam temperature drop too fast" and trip the steam turbine at the same time.

4. The method for preventing water hammer in the turbine of Unit 9E according to claim 1, characterized in that, The gas turbine Mark VIe control system consists of two parts: hardware and software. The hardware part includes a computer and its peripherals for monitoring, a control cabinet, various I / O cards and terminal boards, a communication network system and corresponding equipment, field sensors, and various connecting cables. The software part includes the CIMPLICITY graphical display system and the GETOOLBOX configuration software.

5. A method for preventing water hammer in the turbine of a 9E unit according to claim 4, characterized in that, The control cabinet measures 1350mm × 2400mm × 900mm and contains a single-module or three-module redundant control module, a protection module, and a power distribution module. The control module is connected to a remote I / O cabinet via I / ONET.

6. A method for preventing water hammer in the turbine of a 9E unit according to claim 4, characterized in that, The communication network system is a hierarchical network structure, which is divided into four layers from top to bottom: enterprise-level control layer, monitoring-level control layer, process control layer, and I / O control layer.

7. A method for preventing water hammer in the turbine of a 9E unit according to claim 6, characterized in that, The enterprise-level control layer is the highest layer in the entire network system, providing the interface between the Mark Vee control system and the DCS control system.

8. A method for preventing water hammer in the turbine of a 9E unit according to claim 7, characterized in that, The monitoring-level control layer provides an interface between the human-machine interface and the control server, and also realizes multiple functions such as historical data collection, remote monitoring and vibration analysis.

9. A method for preventing water hammer in the turbine of a 9E unit according to claim 6, characterized in that, The process control level controls the field equipment to ensure the continuous operation of the unit; the I / O control layer is used for data communication between the microprocessor, various I / O cards, and remote cabinets.

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