Calculating process control parameters from steady state operating data

Abstract The tutorial paper will show that chemical process control parameters can be obtained from steady state operating data in combination with simple algebraic equations. The parameters include steady state process gain, feedforward control factor and approximate process time constant. Here, we treat ‘self-regulating’ processes first. Integrating processes and unstable processes are treated separately, unlike the standard method of setting up linear differential equations followed by Laplace transformations. With the standard method, a steady state portion of dynamic response, if there is any, appears as a part of equations of a complex variable. Many control engineers in the chemical industries who might have studied the method, do not use it because of mathematical difficulties. Instead, they may resort to plant tests that are often time consuming and costly. The parameters obtained by this paper's method will aid improvement of control systems. We will address the relation of this method with that of commercial software, which implement advanced process controls based on plant tests.