Tail Gas Diverter Valve Systems Maintain Reliable SRU Operation

Principal Technology Inc., a provider of total system solutions for natural gas, refining, chemical, process and manufacturing facilities, leads the sulfur recovery industry in the development of high performance tail gas diverter valve systems. Out-performing other designs, Principal Technology’s tail gas diverter valve system uses components selected specifically for tail gas service that have proved to be reliable in scores of installations spanning more than thirty years. Principal Technology meets the industry’s need for specially designed tail gas diverter valve systems that provide exceptional performance, functionality and reliability.

“Principal Technology designed its tail gas diverter valve system to address the crucial need to keep elemental sulfur molten during the process of removing it from natural gas or refined petroleum products,” said Matthew S. Hodson, P.E., president and CEO of Principal Technology. “Solidified or freezing’ sulfur is the primary cause of unreliable operation of tail gas diverter valves because elemental sulfur tends to condense and collect on the inside of the pipe, packing and bearing surfaces in the SRU tail gas piping.”

The valve must also seal tightly to prevent sulfur compounds from leaking into the downstream equipment. Leakage into the incinerator can cause unexpected environmental emissions and leaks into the tail gas unit can cause safety or corrosion problems. Principal Technology’s system addresses all of these issues and more.

Because it is critical that SRU tail gas valves be maintained at a temperature greater than 280°F to prevent elemental sulfur from freezing, Principal Technology’s tail gas diverter valve operates properly up to a temperature of 500°F. The design includes the use of laminated graphite packing and a special disc seal system that meets ANSI Class VI shutoff criteria. The valve body is completely steam jacketed to maintain the entire body, shaft, disc and seal at a temperature between 280° and 300°F. The welded jacket is integrated with the body and the steam and condensate connections are located so as to ensure complete distribution of the steam around the valve body and the sensitive shaft bearing blocks.

An important accessory feature available on Principal Technology’s tail gas diverter valve system is real time temperature monitoring of the valve body internals. Principal Technology developed techniques for measuring the valve body temperature through finite element analysis and thermal modeling. By continuously monitoring the internal body temperature, plant operators can ensure that liquid sulfur will not solidify, causing the valve to freeze in position. The temperature monitoring system measures the temperature at a critical point in the body and reports to unit operators if the temperature goes outside pre-set parameters. Proper design and installation of the steam system and adjacent piping is critical for effective tail gas diverter valve operation. So Principal Technology created tail gas piping thermal maintenance systems for the piping adjacent to the tail gas valves as well as steam supply and condensate collection, piping, and controls.

“On line temperature measurement and alarming provides real-time status of the valve temperature to ensure steam supply is maintained and condensate is removed,” said Hodson. “Reliable tail gas valve operation goes beyond proper valve selection and installation. The Principal Technology SRU tail gas diverter valve system incorporates jog valves and automated accessories to facilitate regular partial stroking which increases dependability of the tail gas valves and reduces the possibility of an undetected valve failure. The Principal Technology tail gas diverter valve system uniquely provides all of these and other needed features and functions.”

Principal Technology’s tail gas diverter valve system with standard and optional accessories meets the rigors of sulfur recovery service and supports compliance with ANSI / ISA S84 Safety Instrumented System standards. With an experienced engineering staff, Principal Technology assists owners, operators, and construction contractors with the specialty engineering support needed not only for SRU tail gas treating but for successful sulfur recovery projects as well. Through this complete system approach Principal Technology ensures that customer’s receive a fully assembled, factory tested and documented tail gas valve package or complete SRU ready for easy integration into the their processing facility.