International Journal of Greenhouse Gas Control 34 (2015) 52–62 Contents lists available at ScienceDirect International Journal of Greenhouse Gas Control j ourna l ho me page: www.elsevier.com/locate/ijggc Rate-based model development, validation and analysis of chilled ammonia process as an alternative CO 2 capture technology for coal-fired power plants Dawid P. Hanak ∗ , Chechet Biliyok, Vasilije Manovic Combustion and CCS Centre, Cranfield University, Bedford, Bedfordshire MK43 0AL, UK a r t i c l e i n f o Article history: Received 10 October 2014 Received in revised form 22 December 2014 Accepted 22 December 2014 Keywords: Chilled ammonia process Coal-fired power plant Carbon capture Rate-based modelling a b s t r a c t Due to recent concerns about climate change, which has been triggered by greenhouse gas emissions, the European Union has recommended the decarbonisation of the power sector by 2050 in order to meet its emission reduction target. As a large share of the power generation is currently based on fossil fuels, mainly coal, with this trend expected to continue, clean coal technologies need to be developed. Carbon capture and storage using chemical solvents has been identified to be the most suitable option for coal-fired power plants. The technology which is closest to market commercialisation uses amines, such as monoethanolamine, as a solvent. However, high degradation rates due to impurities present in the flue gas and a considerable heat requirement for solvent regeneration make the application of alternative solvents necessary. In this study, a rate-based aqueous ammonia process model was developed, validated and then modified to a chilled ammonia process model. The model was then scaled up to process flue gas from a 580 MW el supercritical coal-fired power plant. A sensitivity study revealed that the lowest parasitic load occurs for the lean solvent characterised by 12.5% wt NH 3 concentration and 0.29 loading, with the stripper operated between 12.5 and 17.5 bar. The equivalent work requirement for a CAP plant operated at such conditions was found to be up to 15.7% lower than the reference amine scrubbing plant. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction To mitigate the adverse effects of climate change, the European Union committed to reduce its greenhouse gas emissions by at least 80% compared to 1990 levels by the year 2050 (European Commission, 2011). Although the power sector, which is currently dependent on fossil fuel combustion, is a major contributor to global CO 2 emissions, the 2 ◦ C scenario presented by the IEA (2011) assumes that coal-based power generation will still play an essential role in the future energy portfolio. Carbon capture and storage technologies are expected to contribute towards the power sector decarbonisation efforts (Qi et al., 2013), yet only one Abbreviations: AAP, aqueous ammonia process; CAP, chilled ammonia pro- cess; CCU, CO2 compression unit; CFPP, coal-fired power plant; DCC, direct contact cooler; ELECNRTL, electrolyte non-random two-liquid thermodynamic method; GHG, greenhouse gas; HP, high pressure; IP, intermediate pressure; LP, low pressure; MEA, monoethanolamine; PCC, post-combustion capture; PR–BM, Peng–Robinson–Boston–Mathias equation of state. ∗ Corresponding author. Tel.: +44 01234 750111x5235. E-mail address: d.p.hanak@cranfield.ac.uk (D.P. Hanak). commercial-scale full cycle facility has been recently commis- sioned (Fountain, 2014). Post-combustion capture (PCC) plants based upon chemical absorption are a recognised means of reduc- ing CO 2 emissions from coal-fired power plants (CFPP) (Wang et al., 2011; CO2CRC, 2011; Linnenberg et al., 2012). A key advantage of PCC plants is the ease with which they can be retrofitted to the existing fleet of the CFPPs and integrated to new installations (Rackley, 2010). Substantial changes to the CFPP equipment are avoided with a PCC plant retrofit, and a high operating flexibility would be maintained due to relatively independent operation of the CFPP and PCC plant (Wang et al., 2011; CO2CRC, 2011). Monoethanolamine (MEA) is regarded as the reference chemical solvent, as it will probably be used in the early stage commercial- scale PCC plants integrated to the CFPPs (Padurean et al., 2011; Pfaff et al., 2010). The drawback of using MEA as a solvent is a high penalty imposed on the power plant efficiency. This is mainly caused by a large amount of heat required for solvent regenera- tion. For the systems without a high degree of heat integration, a reported reduction of the net efficiency reaches up to 14.5% (Bozzuto et al., 2001) with the mean efficiency penalty of 9–11% points (Buchanan et al., 2000; Ciferno et al., 2005; Gerdes et al., http://dx.doi.org/10.1016/j.ijggc.2014.12.013 1750-5836/© 2014 Elsevier Ltd. All rights reserved.