Industrial & Engineering Chemistry Research, Vol.40, No.4, 1157-1167, 2001
Dynamic modeling and control of a hot-gas desulfurization process with a transport desulfurizer
In a previous paper, a dynamic mathematical model of bubbling fluidized-bed reactors in a hot-gas desulfurization process was developed and several control structures were evaluated. This paper extends this work in three areas: (1) a dynamic model of a transport-type reactor is developed for the desulfurizer, (2) the hydraulics of the solid flows in the system are more rigorously modeled, and (3) the use of the regenerator feed temperature to control the regenerator temperature is explored. Process designs are studied with two different cross-unit solids circulation rates. The impact of alternative process configurations on both steady-state economics (capital investment) and dynamic controllability is explored. The control structure used for the bubbling-bed desulfurizer process is shown to provide effective control for the transport desulfurizer process. Although solids circulation between units depends strongly on pressure differentials between the desulfurizer and regenerator, effective control of solids flow rates can be achieved if standpipes are designed with sufficient height. The temperature of the feed gas to the regenerator provides an effective manipulated variable for the control of the regenerator temperature.