Integration optimisation of elevated pressure air separation unit with gas turbine in an IGCC power plant

Highlights: • IGCC thermodynamic model was setup carefully. • Simulations focus on integration between an elevated pressure ASU with gas turbine. • Different recommended solutions from those of low pressure ASUs are figured out. • Full N₂ injection and 80% air extraction was suggested as the optimum integration. - Abstract: The integration optimisation between an elevated pressure air separation unit (EP-ASU) and gas turbine is beneficial to promote net efficiency of an integrated gasification combined cycle (IGCC) power plant. This study sets up the thermodynamic model for a 400 MW plant specially coupled with an EP-ASU, aiming to examine system performances under different integrations and acquire the optimum solution. Influences of air extraction rate at conditions of without, partial and full N₂ injection, as well as the effects of N₂ injection rate when adopting separate ASU, partial and full integrated ASU were both analysed. Special attention has been paid to performance differences between utilising an EP-ASU and a low pressure unit. Results indicated that integration solution with a separate EP-ASU or without N₂ injection would not be reasonable. Among various recommended solutions for different integration conditions, N₂ injection rate increased with the growth of air extraction rate. The integration with an air extraction rate of 80% and full N₂ injection was suggested as the optimum solution. It is concluded that the optimum integration solution when adopting an EP-ASU is different from that using a low pressure one.