Repowering of existing AL-Hartha gas-fuelled conventional steam power plant with molten salt cavity tubular solar central receiver

Abstract

This paper introduces a new method to repower the existing equipment of the AL-Hartha steam plant located in Basra, Iraq, using a molten salt cavity tubular solar central receiver (SCR). Cycle Tempo is used to simulate the existing natural gas-fuelled conventional steam power cycle with consideration of the heat and pressure losses. The heliostat field and the central receiver subsystems are coded using MATLAB. The model couples the heat balance with the temperature computation of the receiver walls for calculation and analysis of the thermal losses. The proposed modified codes are capable of calculating heat losses, evaluating the integrated power plant and satisfying a wide range of SCRs. The results are verified against plant data and previous works in the literature and good agreement is obtained. The results show the potential of using a molten salt cavity tubular SCR for low-range temperature feedwater preheating, as well as the optimum scheme for the integration of the existing plant with an SCR. It is observed that the maximum improvement for the existing AL-Hartha steam plant and the integrated molten salt cavity tubular SCR is obtained by substituting the bleed steam in all the high-pressure feedwater heaters. For this scheme, the obtained receiver energy efficiency reaches up to 94.1 % and the maximum reduction in instantaneous gas fuel consumption is about 10.1 % with a solar-electricity improvement of about 21.6 % over the design case.