Carbon capture for fossil fuel power generation draws an increasing attention because of significant challenges of global climate change. This study aims to explore the integration of a 453 MWe natural gas combined cycle (NGCC) power plant with an MEA-based post-combustion carbon capture (PCC) process and CO2 compression train. The steady state models of the NGCC power plant, the PCC process and compression train were developed using Aspen Plus (R) and were validated with the published data and experimental data. The interfaces between NGCC and PCC were discussed. Exhaust gas recirculation (EGR) was also investigated. With EGR, a great size reduction of the absorber and the stripper was achieved. An advanced supersonic shock wave compressor was adopted for the CO2 compression and its heat integration was studied. The case study shows net efficiency based on low heating value (LHV) decreases from 58.74% to 49.76% when the NGCC power plant is integrated with the PCC process and compression. Addition of EGR improves the net efficiency to 49.93% and two compression heat integration options help to improve the net efficiency to 50.25% and 50.47% respectively. This study indicates NGCC including EGR integrated with PCC and supersonic shock wave compression with new heat integration opportunity would be the future direction of carbon capture deployment for NGCC power plant. (C) 2015 Elsevier Ltd. All rights reserved.

Coal-fired power plant (CFPP) is one of the main sources of anthropogenic CO2 emissions. Capturing CO2 from CFPP by post-combustion process plays an important role to mitigate CO2 emissions. However, a significant thermal efficiency drop was observed when integrating CFPP with post-combustion carbon capture (PCC) process due to the steam extraction for capture solvent regeneration. Thus research efforts are required to decrease this energy penalty. In this study, a steady state model for 600 MWe supercritical CFPP was developed as a reference case with a low heating value (LHV) based efficiency of 41.6%. A steady state model for MEA-based PCC process was also developed and scaled up to match the capacity of the CFPP. CO2 compression process was simulated to give an accurate prediction of its electricity consumption and cooling requirement. Different integration cases were set up according to different positions of steam extraction from the CFPP. The results show that the efficiency penalty is 12.29% and 14.9% when steam was extracted at 3.64 bar and at 9.1 bar respectively. Obvious improvements were achieved by utilizing waste heat from CO2 capture and compression process, taking part of low pressure cylinders out of service, and adding an auxiliary turbine to decompress the extracted steam. The efficiency penalty of the best case decreases to 9.75%. This study indicates that comprehensive heat integrations can significantly improve the overall energy efficiency when the CFPP is integrated with PCC and compression process. Crown Copyright (C) 2015 Published by Elsevier Ltd. All rights reserved.

Effective recovery of ethylene from dry gas plays an increasingly important role to improve economic performance of refineries. Conventional approaches such as cryogenic separation and cold oil absorption are energy consuming. Hybrid hydration-absorption (HHA) process may be an effective way as hydrate formation takes place at temperature near the icing point. This paper aims to study the HHA column, which is the heart of the HHA process, through modelling and process analysis. A detailed steady state model was developed in gPROMS (R) for this vapour-liquid-water-hydrate (V-L-W-H) four phases system. A base case was analysed with real industry data as inputs. The composition distribution profiles inside the column were explored and the key parameters related with kinetics-controlled hydration process were investigated. Three case studies were carried out for different C2H4 concentrations in gas feed, L/G ratios and temperature profiles respectively. The results show (a) the separation performance of CH4 and C2H4 in the HHA process remains significant for big range of C2H4 feed concentration; (b) L/G ratio has a great impact for hydrate formation and the separation performance of CH4 and C2H4 improves when L/G ratio increases until reaching an optimal point; and (c) a cooling system is required to draw out the heat generated inside the HHA column so that the operating temperature of each plate can be at the temperature near the icing point to retain hydrate formation. This study indicates that the HHA process may be a more promising approach to recover ethylene from refinery dry gas in future industry application. (C) 2015 Elsevier Ltd. All rights reserved.