Common standard for gas turbine exhaust systems

The Exhaust Systems Working Group is finalizing the Waste Heat Recovery Units (WHRU) standard to be submitted to the ISO/TC 192. The next big steps of the Exhaust Systems Project are the validation of the modeling method through a benchmark case on a unit and the review of the HRSG API recommendation in order to amend it.

The European Turbine Network's Exhaust Systems Project was initiated by Statoil, Shell and Total in 2009, as operators experienced problems with their exhaust systems. The goal was to bring together operators facing similar problems with their exhaust systems, as well as exhaust system designers and external expertise and support, who could address the problems by developing a common standard for the design of gas turbine (GT) exhaust systems.

The main objective of the project is to create an ISO standard on exhaust system designs for gas turbines, at first for Oil & Gas application and therefore, essentially concerning Waste Heat Recovery Units and standard Exhaust Systems for gas turbines, according to Amélie Pesquet, Chair of the ETN Exhaust Systems project from Total.

Currently, AAF, Aarding, Alstom, BIHL, Camfil, Dresser-Rand, GE Oil & Gas, Kanfa-Tec, Mjorud, TOTAL, RWTH, Shell, Statoil, TechPart and Frazer-Nash are working together to finalize the first version of this standard.

In the first phase of the project, the group carried out a gap analysis, uploaded an index to facilitate the creation of the standard, and collected valuable material. Both Shell and Statoil shared their internal standard. In the autumn of 2010 Total took over the lead of the project group. The shared standards were then merged as well as supplemented by additional internal documents, which had been provided by exhaust system designers, such as Mjørud and BIHL.

During various meetings it was decided to focus on the creation of the Waste Heat Recovery Unit (WHRU) standard and later amend the existing API standard on Heat Steam Recovery Generators (HRSG). The different organisations have reviewed their section of the standard which will be rewritten to fit ISO standard regulations.

Moreover, it has been decided that the standard should highlight the possibilities and importance of Computational fluid dynamics (CFD) simulation. The group agreed that the best way to validate the CFD code is to use a benchmark case which can be included in the appendix of the standard. ETN, Total and Frazer-Nash are currently writing the Description of Work (DoW) for the benchmark test, explaining the benefits of the study and including a clear timeline and financial overview.

After the completion of the WHRU standard, the group will focus on HRSGs and aims to submit comments for improving the current existing API standard.

Utilities are encouraged to join the Exhaust Systems Project which provides a forum to present and discuss problems experienced in the design of WRHU and HRSG systems, as well as to exchange best practices with the other project group members.