Numerical Computation of Pressure Drop across an Off Supplementary Firing Burner in Heat Recovery Steam Generator

摘要

Combined-gas and steam-turbine power plants have become popular in recent years for distributed power generation and heat production. The optimal thermodynamic and economical design of these plants requires the study of their main components, which are the gas turbine, the steam turbine and the Heat Recovery Steam Generator (HRSG). The HRSG is a heat exchanger that recovers heat from the gas turbine cycle and produces steam and/or hot water, either to be used in a downstream steam cycle or to feed industrial/civil utilities. Some HRSGs include Supplementary Firing (SF) which are additional burners providing additional energy at lower capital costs. However, the supplementary burners cause pressure drops through the duct burner bars which makes the gas turbine to be exhausted at higher pressures. The gas pressure drop should be limited, as previous works show each additional 10 millibars gas pressure drop in the HRSG decreases the gas turbine power output by about 1%. In this work, pressure drop in an off-Supplementary Firing burner of HRSGs has been simulated using two- and three-dimensional models. Simulations indicate that the pressure drop increases with the temperature of the flow entering the burner section. The computational results show very good agreement with semi-empirical results.