1. Stable control of upper tower pressure
This parameter is the basis for the normal operation of the entire fractionation column, and it directly affects the operating conditions of the entire air separation plant.
Features are as follows:
1) The feedback control instrumentation of all the regulation loops and the sequence control elements are organically combined, with the control mode and loop state automatic change function to prevent the overshoot of the regulation loops from occurring.
2) All adjustment circuits have non-telescoping switching function. Even if the hand-held controller is installed next to the machine, we have also designed a non-disturbing switching tracking function. The working mode of the hand-held controller can be arbitrarily changed. It is not necessary to choose local control or remote control. Worrying about switching disturbances and destroying working conditions greatly reduces the work intensity and pressure of the operator.
3) For important loop regulators for special occasions, use a combination of different types of feedback control instruments to monitor, expand the control ideas of single loop regulators, and adopt new meanings to achieve more advanced feedback control. This is well reflected in the relevant regulation loop of the molecular sieve system. It changes due to changes in operating conditions. In order to prevent the disturbance of working conditions caused by sudden changes in process data, MV values and different output change rate limiters are used. , To avoid the sharp changes in output, enhance the system's anti-interference ability, and ensure the stability of the working conditions.
4) For controlled objects that have not yet fully understood the objective function, especially in the new process and new process control scheme, a control scheme based on linguistic variables is used. Only in the process of practice, the process parameter variables are re-established. Awareness, mechanism analysis, and numerical regression can achieve good results, such as in a crude tower system. In order to find the changing trend of the parameters of the crude tower, step-by-step work was carried out, and the internal change law was found, and the adjustment object was changed. The stable automatic control of the rough and rough flow was realized, and how to play an active role in stabilizing the working conditions of the argon system.
2. Design of molecular sieve switching program
The design of the switching program has greatly increased the size of the operation through the organic combination of feedback control, sequence control and dynamic flowchart. Its characteristics are as follows:
1) The program has the functions of pause, continue, skip, stop, single-point jog, etc.
2) The two major groups of molecular sieves MS1 and MS2 have any starting function.
3) A step number that dynamically displays the entire switching cycle.
4) It has the function of arbitrarily adjusting the switching period (changing the time of each time of pressure relief, heating, cooling, charging, etc.)
5) Each switching valve has a self-diagnostic function of the fault, which will automatically display the text signal of the valve position I and the fault signal, and the alarm will prompt the operator in time.
6) It has a pause time recording function and a countdown function to switch the four time periods within the cycle.
7) The switching valve of the molecular sieve flow chart can dynamically respond to the change of the switching status of each valve in the switching cycle.
