Determining the Tail Gas Analyzer Control Loop Equations for Required Air Flow Adjustment in Sulfur Recovery Unit

Measurement of sulfur compounds in the tail gas flow in the sulfur recovery unit is necessary in order to fine control the combustion furnace airflow and efficiency enhancement. In this research, required equations for calculation of air demand in feedforward and feedback control loops in the sulfur recovery unit of Ilam Gas Treating Plant are developed. First, the process was simulated. Then, using MLP neural network and nonlinear regression, K factor was determined for tail gas analyzer air demand calculation. Total required air is sent to the combustion furnace through two lines: trim and main, such that 92.5% of air is passed through the main line. Meanwhile, tail gas analyzer air demand is in the range of -5 to +5 % of the total required air. The presented equations in this research can be employed for other sulfur recovery units.