FEED FORWARD ANALYSIS TO INCREASE THE CLAUS PROCESS EFFICIENCY IN SULFUR RECOVERY UNITS

摘要

The efficiency of Claus process, where H_2S is partially converted to sulfur dioxide (SO_2) and eventually to elemental sulfur, is largely dependent on the oxygen content used for conversion of H_2S to SO_2. The required oxygen amount or 'air demand' can be optimized either in the feed gas primarily, or in the tail gas. Although under normal operating conditions the air demand is expected to be nearly steady; upset or unexpected process conditions can affect the efficiency of Claus process dramatically and cause an increased amount of undesired components. While feed-back control provides an accurate air demand calculation, it is restricted by the process lag time, particularly if the composition of the acid (feed) gas changes rapidly. Quantification of H_2S in the feed gas provides a real-time air demand estimate, thereby, improving sulfur recovery unit (SRU) efficiency significantly. Here, we present an analysis protocol to simultaneously measure H_2S and THC as the main two contributors in the air demand, using a combination of UV and NDIR spectroscopy. By measuring these species, more than 99% of the stream composition will be defined, with some participating into several side reactions in the furnace. Our comprehensive approach has shown success in providing reliable, fast, and accurate real time analysis of acid gas in Claus process.