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Old Town Station outbound position online chromatographic analyzer can analyze two components and the calorific value of the gas used to detect gas and spend gas field to the east of the calorific value of the gas by the SCADA system according to the desired heat setting value and two calorific value detected automatically calculates spend gas field to the east of gas and gas mixing ratio. According to the flow of gas mixing ratio can guarantee calorific value equal to the desired heat value. Select a small flow of traffic flower field to gas as a reference to calculate the gas flow to the east. The FT-6001 and the electric control valve PG6112 constitute flow ratio control loop FICQ-6001, traffic flow FICQ-6001 given signal by mixing ratio is calculated based on the SCADA system and the current field of flowers to the gas calculated that the east gas the traffic flow according to a certain proportion of gas to the gas field with flowers for automatic adjustment.
Achieve control scheme envisaged control scheme using ROCKWELL ControlLogix system to prepare the company's control procedures, control functions. The control system schematics, ratio calculator, expanding value calculator preparation is the key to whether this system can be successful.
1) The ratio calculator conversion relationship, gas mixing ratio can be calculated according to the following formula based on various - the calculated flow setpoint East to gas (standard square / hour); flow SP_FLOWRATE- flower field to gas set value (standard square / h), when the cascade manually by PV5003, PV5004 PID regulator setting the value of the panel set up; BTU- mixed gas calorific value of the expected value (kcal / standard square); BTU_HC- flower field to gas heating value (BTU / ft3), the value is taken from the spectrum analyzer; BTU_DF- East to gas calorific value (BTU / ft3), the value is taken from the spectrum analyzer; so, you can according to the calorific value of the gas mixture expectations set by the operator, traffic and expand based on the calculated value from the calculator out of a field of flowers to a given value of the gas flow rate calculated from the East to the gas given value, and the value given to East to gas flow PID control.
2) expanding value calculator Calculator is used to extend the value of outbound pressure loop PID control output value expanded to an appropriate value of a given flow rate calculator, which is the entire control system is the most no basis in place. It is necessary to take into account the value can be expanded to a desired range, but also consider expanding value due to spend gas field to bring gas to the gas mixture flow to the east end of the station Haikou East to the Old Town station to gas and gas field of flowers system delays or other issues too sensitive reactions. After continuous simulation test and the actual test site, found a more ideal method of calculating the value of the expanded practical application shows are very good.
After continuous simulation tests, and finally completed a good deal of the above problems, PID parameter tuning also reached the ideal state, not only to ensure the stability of the system in response speed has also been relatively good results. This control system involving a total of five PID regulator, the ratio is calculated, expanding value is calculated, four circuit switch without disturbance, a single PID's hand automatically switch without disturbance, circuit undisturbed manual, automatic switching and Cascade No disturbance hand automatic switching functions. The ratio of the flow rate adjustment and cascade control can be divided into two independent control loop, each can run alone, you can also run automatically.
After commissioning summary control system has been stable operation more than two years, the good operating results. The actual operation of the screen can be seen from the field of the reaction, the trend of all the parameters are stabilized. |
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