New design options for concentrating solar integration in a real coal-fired steam power plant

The integration of Concentrating Solar Power (CSP) technology in large scale traditional power plant is one of the best options to promote the necessary transition to a totally renewable electric system. This work aims at providing a complete overview of the possible integration of CSP systems into an existing 320MW coal-fired steam power plant considering a fuel-saving approach. To this end, detailed off-design models of the existing steam power plant are first built and validated using experimental data measured on the field. Design and off-design models of solar sections including parabolic trough collectors, linear Fresnel collectors or a solar tower are then added considering several placement points. Twenty-two hybrid design options are compared including the partial or total replacement of the high-pressure preheaters and/or the economizer, the addition of steam in the high or medium pressure turbines and a modified path for the attemperator stream. The best promising integration of solar energy results to be in the high-pressure preheater/s: i) the highest hybrid thermal efficiency (42.67%) is obtained using parabolic trough/molten salt collectors to generate additional high-pressure steam from the drainage water of the last two parallel preheater (HPH3), ii) similar thermal efficiencies are achieved in a wide range of solar share (up to 9.1%) by including parabolic through/thermal oil collectors to heat part of the feedwater streams of HPH3 and iii) 15400 tons per year of coal can be saved when the solar field area is approximately four times as much the area of the existing coal storage area.