Effect of heat recovery steam generator on characteristics of combined cycle NPP with gas-cooled reactors

The combined cycle allows to obtain the highest efficiency possible for thermal power plants. Development of high temperature gas cooled reactor technologies allow to introduce this solution into nuclear energy. The heat recovery steam generator (HRSG) is an essential equipment of a combined cycle power plant that connects the gas turbine system to the steam cycle. This paper deals with the comprehensive optimization of the thermal design, dimensions and cost of an HRSG by using a genetic algorithm for conditions of high temperature gas cooled reactors, using actual design features of existing HRSG at combined cycle power plants. A single-circuit water tube HRSG with superheater, evaporator and economizer was studied. The optimization variables included the temperature differences at hot end of HRSG, at approach and pinch points, as well as water and steam velocities. On the other hand, the pressure at the outlet of the gas turbine, steam pressure drops, minimum guaranteed thermal efficiency of HRSG, the effective dimensions of HRSG have been considered as main constraints during the optimization. This work showed the total heat transfer area 20299 m2 and total tube length to be 281254.9 m while the total width of the HRSG is 28 m and combined cycle efficiency of 46.26% could be reached, as well as thermal power of HRSG is noted to be 453.08 MW.