Performance improvement of heat recovery steam generator (HRSG) in combined cycle power plant by replacing tube of HP economizer and HP evaporator

Abstract

An efficiency of heat recovery steam generator (HRSG) plays an important role in the power productivity of combined cycle power plants. One of the essential systems in HRSG related to efficiency is high pressure (HP) economizer and high pressure (HP) evaporator. This paper presents a solution to overcome HRSG which has decreased energy performance output from low production high pressure steam flow system. The proposed method solves the problems associated with increasing the energy output performance of HRSG by increasing steam production. HP economizer and HP evaporator tube replacement solutions are based on the idea that high pressure steam system production is reduced due to low heat absorption due to blocking of gas flows from waste trapped between the fintubes that cannot be cleaned by water jet method, another thing is result of the assessment which the number of tubes below the minimum allowable wall thickness. The feasibility of this concept is assessed based on the calculation of the increase in steam production and energy output of HRSG using the thermodynamic concept. Steam production and energy output compared between at commissioning, before replacement tubes and after replacement tubes. The results presents that there is returned HP steam flow in HRSG output by 45.17 percent. The method proposed in this paper can be used for HRSG which has experienced decrease in performance at the high pressure system output flow due to low heat absorption, especially for horizontal dual pressure type HRSGs with an operating life of more than 20 years.