Optimization of ranking cycle

ABSTRACT: Optimization of steam power plants has always been a major concern for industries. Even one percent increase in thermal efficiency of a power plant could save lots of money. A power plant which consumes sea water as a working fluid has been studied which simulated by VisSim software. The ideal steam power plant is called Rankine cycle. In this study, cycle efficiency and optimal placement of FWHs in three regenerative Rankine cycle from one feedwater heater (FWH) up to three feedwater heaters (FWHs) have been investigated in ideal and actual case. Different parameters that affects cycle efficiency include boiler pressure, condenser pressure, boiler temperature, pump efficiency, turbine efficiency, cooling water temperature and the number of feedwater heaters utilized in a power plant. Based on the acquired data from VisSim software, in actual base one, two and three FWHs, the efficiency was 38.87%, 39.68% and 43.55% respectively and the change from ideal cycle was 10.16% decrease, 10.17% decrease and 2.73% decrease respectively. As the number of FWHs increased, the efficiency also increased and it got closer to ideal cycle. The parameter which had the highest impact on increasing efficiency was turbine efficiency. By raising turbine efficiency by 5%, the efficiency moved up around 5% for one and two FWHs and 1.11% for three FWHs. After that boiler temperature had the highest impact on efficiency change which was about 3.5% increase in efficiency by rising it up to 20%. By raising boiler pressure by 20% the efficiency raised by around 1.80% and finally lowering condenser pressure by 20%, led to around 1.40% efficiency increase for actual one, two and three FWHs. Another purpose of this study was to find the optimal placement of feedwater heaters in each cycle. In 1 FWH and 2 FWHs regenerative Rankine cycle, the optimal pressure of the FWHs in both ideal and actual cycles are almost the same, however in 3 FWHs regenerative Rankine cycle, optimal pressure of the feedwater heaters in actual cycle is much less than those in ideal cycle for corresponding feedwater heaters. Keywords: Rankine Cycle, Feedwater Heater, Vissim, Optimization, Power Plant. …………………………………………………………………………………………………………………………………………………………………………………………………………