Reduced Integration Optimization Model for Coupled Elevated-Pressure Air Separation Unit and Gas Turbine in Oxy-combustion and Gasification Power Plant

Abstract

For the promising and green oxy-combustion and gasification power plant, the most efficient and assessable approach for further improvements on the current situation with less investment turned to be process optimization and integration. In this work, the gap of systematic analysis of air separation unit (ASU) and gas turbine (GT) integrations in integrated gasification combined cycle (IGCC) power plant has been fulfilled in the elevated-pressure ASU operation conditions beyond discrete case studies. Based on the conventional rigorous mathematical simulation, a series of model reductions have been proposed and applied to increase the computational flexibility. To validate the reduced model, a base case is built and settled as the benchmark, which is consistent with the industrial experiences. Afterwards, based on the reduced model, the effects of air integration on the thermal performance of IGCC power plant have been explored under the conditions of various nitrogen injection levels. The individual influences of nitrogen injection level on IGCC plant efficiency have been explored as well. To achieve best IGCC performance, the optimization of coupled air integration and nitrogen injection as a whole is completed. Based on the proposed reduced model, the three dimensional figure about systematics analysis of integration optimization for IGCC power plant is generated for the first time. Based on its two-dimensional top view, the feasible regions are identified and optimal solution is generated through nonlinear programming problem solver based on enhanced generalized reduced gradient method.