Field Experience with a UV + TCD Analyzer and Application Specific Sample System for Amine Based Tail Gas Treating Units

摘要

The paper describes the development and subsequent field experience of a gas analyzer that utilizes a combination of UV and thermal conductivity detection principals for on-line process measurement of H_2S, COS and H_2 on amine based tail gas treating units (TGTU). The process requires measurement of H_2 (Hydrogen) and COS (Carbonyl Sulfide) to control and monitor the CoMo (Cobalt Molybdenum) catalytic reactor and the measurement of H_2S (Hydrogen Sulfide) to monitor the efficiency of the amine contactor. The analyzer combines a non-dispersive ultraviolet (NDUV) optical bench with a thermal conductivity detector (TCD) for simultaneous measurement of H_2S, COS and H_2 from a sample point at the amine absorber overhead. The measurement has been performed over the years using various techniques and analyzers. The driving force in this development the request was significant reduction in cost, maintenance and improvement in safety. The sample system was given special attention in this application. The toxicity of H_2S is well known and isolation from the process was a prime consideration during development. Sample is taken from and spent sample returned to the process at a single point. It can be isolated from the process and back flushed with N2 so safety integrity is maintained during service intervention. After experiencing a major upset the sample system was revised to block the salts and particulate from entering the sample system. Much was learned over the three years and the deployment of 60+ units. The paper sums this history, chronicles the lessons learned and improvement in the measurements).