Solvent technology – environmental issues (Task 2)

The task works to understand degrading of solvents better by investigating which factors has the highest impact on the stability of amines (organic compound derived from ammonia). Furthermore, the task will contribute to reduction of operational- and investment cost by indicating amines with higher stability and developing technologies to control and monitor solvent stability.

This task is primarily related to Deployment Case 1, and will provide important insight on solvent technology and its related environmental issues.

The research results will provide useful information on solvent behaviour for parties like:

  • Authorities
  • Technology- and solvent vendors
  • Carbon capture facilities

The task will work to understand degrading of solvents better by investigating which factors has the highest impact on the stability of amines (organic compound derived from ammonia). Furthermore, the task will contribute to reduction of operational- and investment cost by indicating amines with higher stability and developing technologies to control and monitor solvent stability.

This is important because solvent technology is widely used in industry and is the most mature technology for large scale CCS. Two full scale post combustion CO2 capture plants based on solvent technology are in operation in USA and Canada. Our research focuses on solvent management and is relevant for the Norwegian cases and any full-scale plants worldwide. Furthermore, the research results will also be important for actors in the power generation industry, oil and gas industries and aluminium and cement production.

The task is working closely with the following partners:

Main results 2019

The technology developed in Task 2 will positively impact CCS' already positive effect on the environment and reduce CCS costs through developing more stable solvents with longer lifespans.

Oxygen solubility

Throughout 2019 different factors influencing oxygen solubility have been investigated and several methods to measure oxygen solubility have been evaluated. Oxygen reduces the stability of the solvent and if oxygen solubility could be measured and if a correlation between oxygen solubility and degradation could be identified, a faster method to evaluate chemical stability of new solvents would be available. The limitations and opportunities with online oxygen sensors have been identified and recommendations for their applicability were made. Online oxygen sensors (analytical instrument measuring oxygen concentration) have shown to be very useful for stable solvents, while measurements of oxygen concentration in fast degrading solvents is challenging with all available measurement methods.

DORA - Dissolved oxygen removal apparatus

Oxygen from the flue gas is a contributor to decomposition of amine solvents, the decomposition mechanism is also more difficult to follow since the initial step involves radical reactions. We've performed lab scale experiments to demonstrate Dissolved oxygen removal apparatus' (DORA)  ability to reduce oxygen concentration in the solvent. It was demonstrated that ammonia concentration is reduced when DORA is used, which indicate less decomposition of the solvent. The technology has been qualified for testing at a larger scale pilot campaign (1 kg CO2/hour) for a longer time period to take place in 2020.

Technologies like DORA is an example of both the cost and environment aspect of CCS. Our results thus far show that DORA will reduce solvent loss through mitigating solvent degradation. Less solvent loss means less environmental impact and costs saved, e.g. by not having to handle as much waste and consuming less solvents.

PLS-model validated

The Partial Least Square (PLS) model (statistical method used to evaluate data sets) developed in Task 2 in 2018, was validated in 2019 using samples from pilot projects around the world. It was proved that the PLS-model accurately predicts the concentrations of ethanolamine (MEA) and CO2 in the solvent, these components are important input to daily operation of the pilot plant. It can therefore potentially be used for online solvent analysis using Fourier-transform infrared spectroscopy (FT-IR) technology. Infrared spectroscopy exploits the fact that molecules absorb frequencies that are characteristic of their structure and functional groups give rise to characteristic bands both in terms of intensity and position (frequency). For gas samples, this is a technology that is used to monitor emissions from process industry overall the world.

Illustrating 2019's main results – Score plot from Principal Component Analysis (statistical method to investigate dataset) over different lab experiments (batch and solvent degradation rig- SDR) and Tiller pilot (x-axes-Principal Component 1, y-axes-Principal Component 2). The figure shows that the open batch lab-scale experiments at low O2, in regard to degradation compounds profile, shows highest resemblance to cycled experiment (SDR) and pilot demonstration (Tiller).

Main Results 2018

Main Results

  • Verification of experimental set-up for degradation tests and oxygen solubility.
  • Effect of amine concentration, loading and temperature on O2-solubility studied.
  • Guidelines/lessons learned for evaluating solvent stability presented
  • PLS model tested on real/aged MEA samples from bench scale experiments to large Pilot Plant.
  • Developed techniques for oxygen removal showed good results with removal rate above 80% obtained.
  • Test and scale up study of oxygen removal techniques performed

Impact and innovations

  • Observation from pilot plant operations in several capture plants shows that there is a correlation between the level of dissolved oxygen in the rich absorption liquid and the degradation profile. Reduction /removal of dissolved oxygen can significantly reduce solvent degradation and then reducing operational problems and cost of carbon capture plants using amine technology.
  • Reaction schemes for MEA or other amines are transferable to other amines. Data from pilots, especially, for MEA is currently available and could be used to verify different laboratory set-ups.
Figure illustrating 2018's main results: DORA LL MODE, Sodium Sulphite as scavanger

Results 2017

One of the drawbacks for post-combustion CO2 capture with solvent technology is that absorption capacity of a solvent is reduced because of for example degradation. This mean that unwanted chemical reactions (degradation) occur in addition to the CO2 absorption and desorption reaction.

Different strategies are used to reduce unwanted reactions:

  • Development of mitigation technologies to reduce degradation
  • Development of new experimental methodologies to predict chemicals stability of new solvents at process conditions
  • Gathering of knowledge on relation between amine structure and chemical stability. In addition, online monitoring of the solvent status in the process has been a focus

The main results from 2017:

  • Successful proof-of-principle of the oxygen removal concept (mitigation technology)
  • New methodology has been suggested for evaluation of chemical stability of solvents
  • Several amine structures sensitive to degradation have been identified
  • The existing Partial Least Square (PLS) model used to evaluate solvent status has been improved

Journal Publications

2019: 

 

Conference Publications

2020:

  • Oxidative and biological degradability of aqueous amine solvents for CO2 capture - V. Buvik, S. J. Vevelstad, H. K. Knuutila. University of Texas 5th Conference on Carbon Capture and Storage, UTCCS-5

2019:

  • De-oxygenation as countermeasure for the reduction of oxidative degradation of CO2 capture solvents - R. V. Figueiredo, D. Bakker, A. Huizinga, J. Monteiro, E. Goetheer. TCCS-10 conference, Trondheim, Norway
  • Short-cut oxidative degradation test for CO2 capture solvents - J. Monteiro, P. Gravesteijn, E. Goetheer. TCCS-10 conference, Trondheim, Norway
  • Comparison of oxidative degradation and biodegradability of aqueous amine solvents for CO2 capture - V. Buvik, S. J. Vevelstad, H. K. Knuutila. TCCS-10 conference, Trondheim, Norway
  • Oxygen solubility of amine solutions - V. Buvik, S. J. Vevelstad, H. K. Knuutila. PCCC-5 conference, Kyoto, Japan

2018:

  • O2 solubility and oxidative degradability of aqueous amine solutions for CO2 capture - V. Buvik, S.J. Vevelstad, H.K. Knuutila. GHGT-14, Melbourne
  • Multi-component analysis of liquid samples by FTIR - A. Grimstvedt, M. Wiig, A. Einbu, S.J. Vevelstad. GHGT-14, Melbourne
  • Review of oxidative degradation of 30 wt. % MEA in pilot campaigns- V. Buvik, H.K. Knuutila. University of Texas 4th Conference on Carbon Capture and Storage UTCCS-4

Pop Science Articles

2019:

  • Etter-forbrenning fangst (post-combustion) av CO2 - Potensiale og utfordringer - Vevelstad S.J., #SINTEFBlog, 2019.09.12
  • FTIR combined with multivariate analysis for monitoring of solvent composition in CO2 capture plant - Grimstvedt A., #SINTEFBlog, 2019.09.03

 

Task leader