سيدرضا مرتضوي

One of the ways to increase the efficiency of converting fuel into energy is to combine two or more thermal cycles at the same time in a power plant. The main challenge in the design of the combined cycle power plant is the proper use of the hot gas output from the turbine in the steam cycle by the heat recovery steam generator (HRSG) so that the most optimal output of the steam gas is received. The design of the heat recovery steam generator system is so important that only by changing one of its functional parameters, the efficiency and multiplication of the heat recovery steam generator performance and, as a result, the efficiency and overall power production of the combined cycle power plant, can change significantly. In this research, the issue has been looked from the designer point of view, so that the effect of changes in pressure levels as well as the functional saturation pressure value of each of the drums on the overall performance of the combined cycle power plant system has been measured. Also, considering that the input to the heat recovery steam generator is ultimately from the hot gas produced by the gas cycle, two changes in the gas cycle part are considered and their performance is eva‎luated and the power production of the combined cycle is examined. These two important changes are: changing the temperature input to the gas turbine (TIT) and the presence or absence of a recuperated heat exchanger. The three general systems investigated in this research include: 1. cycle with dual-pressure heat recovery steam generator with reheating, 2. cycle with triple-pressure heat recovery steam generator with reheating, 3. cycle with triple-pressure heat recovery steam generator with reheating and recuperated heat exchanger. By changing the four mentioned parameters in the sections of gas cycle and heat recovery steam generator, the efficiency and power production of gas cycle and combined cycle have been compared. Furthermore, the amount of irreversibility and unavailable exergy (the sum of destroyed exergy and lost exergy) is calculated to study the performance of the systems from the second law of thermodynamics. Then, by calculating the number of heat transfer units (NTU) for each of the economizer, evaporator and superheater sections, as well as the total number of heat transfer units, the performance of all three cycles has been eva‎luated. The reason is that the heat transfer units have a direct relationship with the production costs of the heat recovery steam generator and thus the overall costs for power production.

بويلر بازياب حرارت , قانون اول ترموديناميك , قانون دوم ترموديناميك , تعداد واحدهاي انتقال حرارت , سيكل تركيبي

Heat recovery steam generator , first law of thermodynamics , second law of thermodynamics , number of heat transfer units , combined cycle

Seyed Reza Mortazavi

Dr. Seyed Mostafa HosseinAliPoor