Economy Analysis On Thermal System Performance Of An Ultra-Supercritical Unit With Double Reheat

At present, the high-parameter and large-capacity unit have become the main body of thermal power units in China. The double reheat unit is an important developing direction of ultra supercritical power generation technology, which has a great application potential. Due to just a few ultra super critical units with double reheat go into operation in domestic, simulating thethermal system of the double reheat unit and analyzing its thermal economic comprehensively are of important significance to development of the double reheat technology. In this thesis, the study of the double reheat thermal system is carried out, and the following research is mainly as follows:On the basis of analysis of the double reheat thermodynamic system, the performance calculation model, variable-condition model, exergy analysis model were established. Based on the EES software, which is for Engineering Equation Solver, a simulation model of double reheat unit was established and the accuracy was verified.The thermal economic indices and other main operation parameters of a double reheat super-critical plant have been calculated by EES simulation model. Meanwhile, the distributions of main steam-water mass flow and the superheat degree of extraction steam were studied. The analysis shows that the superheat degree of extraction steam in double reheat system is relatively high. This paper presents a superheat utilization double reheat thermodynamic system with a regenerative turbine to solve this problem. Energy index calculation and comparative analyses were conducted on two systems.The calculation method of the important parameters’ target value in double reheat units was presented, providing the basic data for economic evaluation.The energy-loss calculation of main parameters including main steam temperature, main steam pressure, reheating temperature,which largely affect model output uncertainty were performed to provide the foundation of on-line calculating and analyzing.The economic performance of the double reheat unit was evaluated from the angle of economics with technological economics principles. Based on supervisory information system, on-line energy-loss analysis system software including performance appraisal was developed. The design idea of that program, calculating process and software function module were described in detail.