Novel operation strategy for a gas turbine and high-temperature KCS combined cycle

This paper designs a high-temperature Kalina cycle system (KCS) to recover a gas turbine (GT) waste heat. A novel methodology of predicting off-design performance of GT-KCS combined cycle is presented by introducing geometric parameters of heat exchangers. The inlet guide vane of GT compressor operation strategy is applied in GT. Novel operation strategies named modified sliding pressure operation (MSPO) and novel modified sliding pressure operation (NMSPO) are proposed for KCS. The MSPO uses a fixed KCS turbine inlet temperature and an optimized ammonia concentration at KCS separator inlet under GT part-load conditions, while the NMSPO adopts an optimized ammonia concentration at KCS separator inlet and a fixed temperature difference between KCS turbine inlet and GT exhaust. The results show that the optimal ammonia concentrations at KCS separator inlet under the MSPO and NMSPO decrease with declining GT load. The MSPO has the highest bottoming KCS thermal efficiency among the sliding pressure operation (SPO), MSPO and NMSPO. The NMSPO recovers the most heat from GT exhaust, resulting in the highest KCS net power and GT-KCS thermal efficiency. The NMSPO recommended as the optimal operation strategy could produce 20.72 kW and 25.75 kW more net power than the MSPO and SPO, respectively.