Date of Award

1-1-2012

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemical Engineering

First Advisor

Steven A. Benson

Abstract

In 1992, international concern about climate change (a change to Earth's climate, especially those produced by global warming) led to the United Nations Framework Convention on Climate Change (UNFCCC). The ultimate objective of that convention was the "stabilization of greenhouse gas concentrations in the atmosphere at a level that mitigates anthropogenic interference with the climate system" (1). There has been a growing concern about global climate change which scientists believe is (arguably) caused mainly by anthropogenic emission of greenhouse gases (GHGs) into the atmosphere. The overall goal of this work was to evaluate next generation solvents at a pilot scale level to determine the advantages and disadvantages these advanced solvent have over the current industry standard. To accomplish this goal a pilot scale system was designed and fabricated on the back end of the Energy and Environmental Research Center's Combustion Test Facility. The system was used to evaluate six solvents which included Hitachi's H3-1, MDEA/Piperazine, Huntsman's Jeff Treat XP, MEA and two others. Because of the proprietary nature of these solvents not all information can be shared.

It was determined that advanced solvents are the best available technology for implementing CO2 capture at the large scale. Advanced solvents will be the technology that will make it to the market place sooner than other technologies due to the long time use of amine solvents in the oil and gas industry for their removal of CO2. For the case of postcombustion capture, the main conclusions are that 90% CO2 capture can be met with MEA and advanced solvents. The EERC system was able to capture at least 90% of the CO2 present in the flue gas for each advanced solvent and the baseline MEA. Results of the testing indicate that the use of advanced solvents, such as H3-1, can reduce the cost of capture considerably.

Data from the advanced solvents and MEA tests conducted show that for similar test conditions, MEA required about 10-40% more regeneration energy input to achieve 90% CO2 capture than the advanced amine-based solvents. H3-1 required the lowest heat input (~1475 Btu/lb CO2), and the reboiler duty for MDEA+PZ was ~1600 Btu/lb CO2. The regeneration energy requirement for MEA was estimated to be in the range of 1775-1940 Btu/lb CO2 captured. The MEA case required a 30% to 50% higher solvent flow rate than H3-1 to attain 90% CO2 capture for a given amount of treated flue gas. Conversely, tests on MDEA+PZ showed a solvent usage about 135% higher than MEA to reach 90% capture. Consequently, use of H3-1 for a large-scale process could lead to significant economic benefits over MEA and MDEA+PZ. Lower solvent flow rates require smaller pumps and less energy to pump the solvent through the columns.

Advanced solvents show promise, but improvements will still need to be made to reduce capital and operating costs to make the technology economically feasible for today's market. Advanced contactors and solvent promoters will be technologies that may enable these solvent to become more economically favorable.

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