Dynamic simulation of a hybrid once-through and natural circulation Heat Recovery Steam Generator (HRSG)

Considering the steam generator startup process and its dynamic response to the stimulations applied in the downstream and upstream cycles is crucial for predicting the system performance. In the present work, a novel hybrid once-through and natural circulation Heat Recovery Steam Generator (HRSG) is numerically simulated to demonstrate how it may improve the performance of a power plant. Dynamic numerical simulation is carried out to show the advantages of hybrid HRSG over natural circulation type. The main focus is to reduce the steam generation startup period via a hybrid once-through and natural circulation HRSG. Results showed that the system reaches the steady-state condition after 60 min for the once-through section compared to the 180 min for the natural circulation section. In other words, the hybrid HRSG can reach 50% of its nominal capacity utilizing only the once-through section just 60 min after startup. After 120 min, the natural circulation section also comes fully online. Additionally, steadystate simulation results showed that in the hybrid HRSG, the drum wall thickness, drum diameter, and weight decreased by 54, 30, and 65% compared to the drum of a natural circulation type. (c) 2021 Elsevier Ltd. All rights reserved.