DYNAMICS AND CONTROL OF AN INDUSTRIAL FRONT-END ACETYLENE CONVERTER

The dynamic simulation of a frontal industrial acetylene converter and its closed-loop performance under three different control strategies are discussed in the present work. The reactor is used for the selecti ve hydrogenation of acetylene in the presence of large amounts of ethy lene. It consists of a condenser followed by three catalytic beds with intermediate cooling. In the first step, the steady-state and the ope n-loop dynamic modeling and simulation of the converter are described. An analysis of the closed-loop behavior follows, starting with the ex isting control scheme, i.e. three conventional feedback loops located at the condenser and at the two intermediate heat exchangers respectiv ely. The second control configuration studied is formed by adding feed forward scheme, which acts on the set points of the feedback loops. Th is configuration proves to diminish the peaks in the reactor temperatu re produced by changes in the total reactants flowrate and/or in the C O or the C2H2 concentration. The last scheme studied is the previous o ne plus an external feedback composition loop. To keep the acetylene c oncentration in the final ethylene below 3 ppm, this controller should ensure around 1 ppm C2H2 at the reactor outlet (approximately 1.4 10( -4) wt% for a typical process stream composition).