Technical and thermodynamic impacts of heat recovery steam generator interior layout arrangement in the full repowering of an operating natural gas-fired steam power plant

Abstract

The present research paper investigates the technical and thermodynamic impacts of heat recovery steam generator (HRSG) interior layout arrangement in the full repowering of an operating 200 MW steam power plant. To do so, two main layouts are considered. In the first layout, a single HRSG and a 425 MW gas turbine (GT) are selected. In the second layout, two HRSGs and two GTs are investigated. In the case of using two HRSGs, different model GTs are used and examined. Single, double, and triple-pressure level HRSGs are tested in both layout arrangements. The impacts of pressure levels on how the new cycle performs and the negative results of implementing each case in repowered power plants are studied. Three new parameters are defined to evaluate the technical effect of each case. First, by assessing the impacts of each GT, the optimum one is determined, and then various effects of HRSG layout arrangement on the cycle performance are analyzed. The performance of the cooling tower, along with an existing steam turbine, mainly depends on HRSG pressure levels, particularly the number of pressure levels. This is why it is necessary to consider the performance of other components when determining the number of HRSG pressure levels. For the best efficiency while using two HRSGs, the GT model Siemens V84.3A is recommended. In this case, energy and exergy efficiencies increase to 58.5% and 57.57%, respectively. For the case of using one HRSG, using the GT model Siemens SGT5-8000H is highly advisable due to a 59.45 % and 57.41 % increase in energy and exergy efficiency, respectively.