I. Project Background Huaneng Dalian Power Plant is located on the coast of the Bohai Sea in the outskirts of Dalian, close to Dalian Economic and Technological Development Zone and about 30 km from the city center. It is a large-scale thermal power plant built in China by foreign capital and fund-raising. It now has an installed capacity of 1.4 million kilowatts and is composed of four 350,000-kilowatt coal-fired units. One of the first phase of two thermal power plants using Japanese equipment, respectively, in September 1988 and December put into operation and has 700,000 kilowatts of generating capacity. ; Phase II expansion project started in March 1996, December 1998 has put into operation. At present, the power produced by Huaneng Dalian Power Plant is sold through the Northeast Power Grid. Over the past few years, the plant annual power generation in 3.8 billion degrees above the basic production of the entire factory automation control. The plant's power generation capacity has now reached 1.05 million kilowatts. Premier Li Peng and Minister Shi Dazhen of the Ministry of Electric Power proposed to the plant the requirements for the modernization of management and hoped to build Huaneng Dalian Power Plant into a model for the national power enterprises and achieve world-class standards. However, due to the first-phase engineering equipment has been used for many years, the aging equipment, some of the system control level is relatively backward, in the thermal automatic adjustment, the peripheral control equipment failure is too much, not reliable, most of the actuators are pneumatic actuators, is eight The products of the decade, its performance is not good, adjust the door refused to move, vibration occurs from time to time, adjust the error. Some automation equipment can no longer meet the needs of the rapid development of automation systems. In this case, the reformation of the valve positioner has come into being. In this transformation, the first phase of Unit 2 is retrofitted, involving 6 sets of fan flow control gates, Mill 10 sets of cold and hot air damper, burner angle control 4 sets of high and low side pressure and water temperature regulating valve 6 sets, and other 20 sets of regulating doors and 13 sets of secondary air baffle; Second, the project implementation process Problems encountered in the solution and solution: 1,4 burner swing angle valve positioner installation, the valve stroke to 400mm, so to be straight stroke displacement to small displacement (measurable range) conversion, the original old locator Spring and pressure sensor using the way, but the spring vibration, the transformation of the use of oblique iron way is the valve positioner guide rails attached to the inclined iron, the larger the vertical displacement into a horizontal direction of the more Small displacement, the field application is good, a high pressure bypass temperature control valve and two low pressure bypass temperature control valve, also have the above problems, because the valve is placed horizontally, In order to facilitate the installation and reduce the weight of the measuring connector, the modification uses the universal joint method, but a bit error, but for the 300mm range, 2 ~ 3mm error is negligible, the field application is better; 2,1 A high pressure bypass temperature control valve and two low pressure bypass temperature control valve, also have the above problems, because the valve is placed horizontally, in order to facilitate the installation and reduce the weight of the measurement connector, the transformation of universal joints, But a little error, but for the 300mm range, 2 ~ 3mm error is negligible, the field application is better; 3,6 fan inlet adjustment door, the angular travel mode of work, Party A requires a loss of power with Paul function , When the power of the positioner disappears, the valve should be kept in the current position to avoid that once the 4 ~ 20mA signal from the DCS disappears (the AO signal of the DCS valve positioner is not redundant), the fan inlet adjusts the door rapidly Enter the fully open or fully closed position, leaving the boiler pressure fluctuations occur more likely to cause the boiler trip, which led to production accidents, we use the current relay plus solenoid valve Way, when the DCS signal disappears, with a solenoid valve to lock the fan inlet adjustment door cylinder gas source, thereby achieving power loss protection function; 4, in the field debugging should be noted that in the case of vibration, the valve positioning Otherwise, since the Siemens SIPART PS2 Smart Positioner uses a microprocessor to compare the setpoint with the position feedback, if the microprocessor detects a deviation, it uses a five-step switching program to control the piezo Valve, piezoelectric valve control instructions will be converted to incremental gas displacement, when the control deviation is not (low speed zone), the positioner output continuous pulse, precise adjustment, the valve positioner will be due to the vibration of the endless precise regulation, This will inevitably affect the life of the control valve, the dead zone set so that the above problems are well resolved; In addition, the need to set the valve confinement function to prevent the valve does not close, both residual pressure in the valve cylinder; above the Siemens SIPART PS2 Intelligent valve positioner has been successfully put into use in Huaneng Dalian Power Plant, its application is convenient, flexible, high control accuracy, Compact structure, etc., users get the praise, won a high reputation for the Siemens SIPART PS2 smart valve positioner, further Siemens SIPART PS2 smart valve positioner has accumulated valuable experience for us!
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