The Model Steam Turbine: A Method of Evaluating a Heat Recovery Steam Generator in a Combined Cycle Plant

Turnkey and thermal island supply scopes present turbine manufacturers with a perfect way to sell their rotating products. The popularity of these plant configurations, along with the recent availability of more holistic test codes, has led to the need for an accurate and reasonable method of determining the thermal performance of the externally-purchased HRSG component. To assess a multiple pressure HRSG, it is advantageous and convenient to have one single criterion for the evaluation of performance, especially when this criterion provides for the compensation of the different outlet energy streams. The so-called Model Steam Turbine method of HRSG evaluation was developed for these reasons. The result of the calculation, a lone performance criterion, is the shaft power of the fictitious Model Steam Turbine. In this paper we will detail the components of the Model Steam Turbine calculation and explore the merits of this method. Some thoughts on performance corrections are also presented.