GMVC-based optimal plant-wide PID tuning for a multiple effect evaporator

In recent years, petroleum and petrochemical industries have been working aggressively to conserve energy. The conservation of energy by these industries will improve the profitability of individual corporations while contributing significantly to their exercise of Corporate Social Responsibility (CSR). Saving energy is achieved through a wide range of measures, including the replacement of equipment and other soft measures. Energy conservation by soft measures-particularly improved control-is highly cost-effective and easily implemented by corporations. This paper proposes energy conservation of multiple-effect evaporators installed in large numbers in chemical and paper industries. In multiple-effect evaporators, liquid level control systems are linked in a series; hence, poor controllability strongly impacts other effect evaporators. Performing liquid level control by minimizing variance accompanying input and output is the key to saving energy. Control improvement countermeasures to conserve energy consumption by multiple-effect evaporators are shown using sample applications.