Systematic screening of solvent properties linked to process costs

Are Ionic Liquids ready to be deployed for CO2-capture?

Patrick Brandl1,3, Maria T. Mota-Martinez2,3, Jason P. Hallett2, Niall Mac Dowell1,3*

Acknowledgements

1Centre for Environmental Policy, Imperial College London, South Kensington

Campus, London SW7 1NA, UK 2Department of Chemical Engineering, Imperial College London, South

Kensington Campus, London, SW7 2AZ, UK3Centre for Process Systems Engineering, Imperial College London, South

Kensington Campus, London, SW7 2AZ, UK

*E-mail address: niall@imperial.ac.uk

Sensitivity analysis: Evaluating economic feasibility and practical limits

Conclusions: Ils‘ high viscosity outweights increased solubility

• •

Moving from experience-based heuristic to systems-based assessment of solvents

Process Engineer

• Wants to reduce CO2footprint at best cost

• Needs to select process and solvent

Research Chemist

• Develops new CO2capture material

• Focused on increased CO2 capacity and/or reduced heat of regeneration

Rapid screening

• Bridges gap between lab and application

• Analyses process cost implications

R&D pipeline

Columns higher than 120m (tallest columns in world) are unfeasible; most ILs require

unrealistic columns

Installed cost of the main process units using 5 ILs as solvent for CO2 capture. Majority is

spent for heat exchangers and compressors.Screening of solvent’s viscosity and Henry’s constant and their impact on the total costs

Total costs of most promising ILs compared to the literature’s benchmark (30wt% MEA)

Process performance

indices

Solvent flowrate

Size of equipment

Heating requirements

Electricity requirements

Economicindices

CRF

CAPEX

OPEX

TAC

Sorbent properties

Henry’s constant

Density

Viscosity

Reaction constant

Surface tension

Thermalconductivity

Heat of absorption

Heat Capacity

Solvent Evaluation

New solvent

Financial parameters

£fuel

£CO2,emitted Lifetime of plant

Interest rate

Bespoke thermodynamic unit modelling of post-combustion CO2

capture plant implemented in gPROMS®

Thermodynamic models • Rate based mass transfer using two-film theory (Onda’s

correlation and Henry’s law) and assuming phase

equilibrium in the vapour-liquid interface.[3]

• Calculating the heat transfer via Nusselt-correlations

Total Annualised Cost TAC Τ$ 𝐭𝐨𝐧𝐂𝐎𝟐• Capital Expenditure CAPEX correlations based on key

characteristics of each unit, e.g., size, material, (…)

• Operating Expenditure OPEX based on Short-Run

Marginal Cost for production of electricity and heat

• Costs annualised via Capital Recovery Factor CRF

TAC = 𝐶𝑅𝐹 ∙

𝑘

units

𝐶𝐴𝑃𝐸𝑋𝑘 +

𝑙

𝑂𝑃𝐸𝑋𝑙

Affiliations

Designing ILs for CO2 capture should consider low viscosity as a primary design criterion.

Majority of literature, which proposes a new promising solvent, does not report the full property-dataset needed to assess ILs. An assessment must not be based solely on the solubility, but on a systemic evaluation of their various thermophysical properties.

Carbon Capture in the UK: Factsheet

• The UK has been committed to reduce the CO2 emissions by 80% from 1990 levels by 2050.

• Electricity generation from fossil fuels is one of the biggest single emission sources of CO2 (25% of total) [1].

• Capturing CO2 from the power plants’ flue gas emitted otherwise into the atmosphere can significantly reduce CO2 emissions.

• In conjunction with other technologies, CCS leads to a minimised overall costs of electricity supply in the long run [2].

@patrick_brandlPatrick focuses on the techno-economic assessmentof climate change mitigation technologies. He ispursuing a PhD in multi-scale modelling of CO2

capture processes and links molecularthermodynamics with process engineering. Patrickearned both his Bachelor’s and Master’s degree inChemical Engineering from the Technical University of Munich.

References[1] Department of Energy and Climate Change, Energy Trends: June 2016: URN 16D/79B.[2] International Energy Agency. World Energy Outlook, 2016.[3] Mota-Martinez MT et al., Sustainable Energy Fuels, 2017,1, 2078-2090

Reducing the interactions between the cation and anion is the most straightforward means of lowering the ionic liquid’s viscosity.

The authors thank the UKCCSRC (Grant No. UKCCSRC-199) for funding this work.Additional funding from Canada’s Oil Sands Innovation Alliance (COSIA) and theAbu Dhabi Petroleum Institute is gratefully acknowledged.