Energy integration issues for hydrogen and electricity co-production based on gasification process with Carbon Capture and Storage (CCS)

摘要

Integrated Gasification Combined Cycle (IGCC) is a technology for power production in which the feedstock is partially oxidized with oxygen and steam to produce syngas. In a conventional IGCC design without carbon capture, the syngas is purified for dust and hydrogen sulphide removal and then sent to a Combined Cycle Gas Turbine (CCGT) for power production. Carbon capture technology is expected to play a significant role in the coming decades for curbing the greenhouse gas emissions. IGCC is one of the power generation technologies having the highest potential to capture carbon dioxide with the low penalties in term of efficiency and cost. In a modified IGCC design for carbon capture, the syngas is catalytically shifted to maximize the hydrogen level in the syngas and to concentrate the carbon species in the form of carbon dioxide that can be later capture in a pre-combustion arrangement. After carbon dioxide capture, the hydrogen-rich syngas can be either purified in a Pressure Swing Adsorption (PSA) unit and exported to the external customers (e.g. PEM fuel cells) or used in a CCGT for power generation. This paper investigates the most important energy integration issues for hydrogen and electricity co-production scheme based on coal gasification process with carbon capture and storage (CCS). The coal-based IGCC case study produces around 400 MW net electricity and a flexible hydrogen output in the range of 0 to 200 MW (LHV) with 90 % carbon capture rate. The principal focus of the paper is concentrated on overall energy efficiency optimization by better heat and power integration of the main plant sub-systems (e.g. integration of steam generated in gasification island and syngas treatment line into combined cycle, integration of PSA tail gas in the power block, heat and power demand for Acid Gas Removal unit, ASU – GT integration etc.).