ADVANCED CONTROL OF MULTIPLE SULFUR RECOVERY UNITS

摘要

Sulfur Recovery in a Refinery entails collecting sour vent gases (containing H2S) from arnnumber of process sources, including Hydrotreating Units, Hydrocracking Units, Crude Units,rnand others, then converting the H2S to a more useable form such as sulfuric acid or elementalrnsulfur. The feed rates and compositions to the Sulfur Recovery Units (SRUs) are notrncontrollable at the SRU. In addition, most Refineries employ multiple SRUs operating inrnparallel. This gives rise to a number of process control challenges, including:rnLoad balancing among the various unitsrnResponse to changing loads (total feed load cannot be controlled)rnResponse to variable compositionsrnAir/Oxygen load controlsrnResponse to one SRU shutdown (rapid load increase for the remaining SRUs)rnThis paper will present the ramifications of these control problems along with thernmethodology used for successful implementation of the advanced control scheme for each.