With an increased urgency for global action towards climate change mitigation,
this research was undertaken with the aim of evaluating post-combustion CO2
capture as an emission abatement strategy for gas-fired power plants. A
dynamic rate-based model of a capture plant with MEA solvent was built, with
imposed chemical equilibrium, and validated at pilot scale under transient
conditions. The model predicted plant behaviour under multiple process inputs
and disturbances. The validated model was next used to analyse the process
and it was found that CO2 absorption is mass transfer limited. The model was
then improved by explicitly adding reactions rate in the model continuity, the first
such dynamic model to be reported for the capture process. The model is again
validated and is observed to provide better predictions than the previous model.
Next, high fidelity models of a gas-fired power plant, a scaled-up capture plant
and a compression train were built and integrated for 90% CO2 capture. Steam
for solvent regeneration is extracted from the power plant IP/LP crossover pipe.
Net efficiency drops from 59% to 49%, with increased cooling water demand. A
40% exhaust gas recirculation resulted in a recovery of 1% efficiency, proving
that enhanced mass transfer in the capture plant reduces solvent regeneration
energy demands. Economic analysis reveals that overnight cost increases by
58% with CO2 capture, and cost of electricity by 30%. While this discourages
deployment of capture technology, natural gas prices remain the largest driver
for cost of electricity. Other integration approaches – using a dedicated boiler
and steam extraction from the LP steam drum – were explored for operational
flexibility, and their net efficiencies were found to be 40 and 45% respectively.
Supplementary firing of exhaust gas may be a viable option for retrofit, as it is
shown to minimise integrated plant output losses at a net efficiency of 43.5%.
Areas identified for further study are solvent substitution, integrated plant part
load operation, flexible control and use of rotating packed beds for CO2 capture.
| Identifer | oai:union.ndltd.org:CRANFIELD1/oai:dspace.lib.cranfield.ac.uk:1826/12111 |
| Date | 11 1900 |
| Creators | Biliyok, Chechet |
| Contributors | Yeung, Hoi |
| Publisher | Cranfield University |
| Source Sets | CRANFIELD1 |
| Language | English |
| Detected Language | English |
| Type | Thesis or dissertation, Doctoral, PhD |
| Rights | © Cranfield University, 2013. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder. |
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