SBIR-STTR Award

If CO2 could be scrubbed from the flue gas of power plants and safely sequestered, the country’s most important source of electricity, fossil-fired power plants, could operate without emitting significant amounts of greenhouse gases. Although technology for scrubbing CO2 from the flue gas of a power plant is commercially available, it is far too expensive and requires too much energy to be widely deployed. This project will develop technology to reduce the costs and energy requirements for the stripper of a CO2 scrubber, with the objective of making CO2 scrubbing an affordable technology for controlling emissions. Phase I will study the feasibility of using plastic heat exchangers, which are now being commercialized in HVAC applications, as an internally heated contactor and a cross exchanger in a CO2 stripper. Small-scale bench-top experiments will be conducted to measure the heat and mass transfer coefficients in the internally-heated contactor that forms the core of the stripper. This data will be used to prepare a conceptual design for a large-scale stripper. A plastic-plate heat exchanger, which could be used as the cross exchanger, will be designed. Finally, an engineering analysis will be performed to estimate the impact of the plastic heat exchangers on the cost and energy-use of an advanced CO2 scrubber for a 500 MW pulverized-fuel power plant.

Commercial Applications and Other Benefits as described by the awardee:
The advanced stripper should limit CO2 emissions at the stack of the power plant, providng: (1) a 32% reduction in the capital cost for the scrubber, (2) much lower maintenance costs (due to the replacement of steel heat transfer surfaces with corrosion-resistant plastic), and (3) when used with advanced solvents, a more than 50% reduction in the thermal energy required to operate the scrubber. In addition, the absorption of acid gases is an important part of many chemical processes, including the cleaning of raw natural gas and the removal of CO2 from synthesis gas; consequently, the plastic heat exchanger technology could become an important part of processes that produce a carbon-free fuel from coal and natural gas.

If CO2 could be scrubbed from the flue gas of power plants and safely sequestered, the country’s most important source of electricity, fossil-fired power plants, could operate without emitting significant amounts of greenhouse gases. Although technology for scrubbing CO2 from flue gas is commercially available, it is far too expensive and requires too much energy to be widely deployed. This project will develop technology to reduce the costs and energy requirements for the stripper of a CO2 scrubber, with the objective of making CO2 scrubbing an affordable technology for controlling emissions. Specifically, the expensive metallic heat exchangers, which are fundamental to CO2 scrubber operation, will be converted to plastic designs. Thermal efficiency of the scrubber will be improved by replacing the conventional reboiler and stripper column with a unique heat and mass exchanger that again is based on a plastic heat exchanger. In Phase I, performance data from a proof-of-concept experiment confirmed that the proposed technology could effectively strip the CO2 from an MEA absorbent at a significantly lower temperature than required by a conventional stripper. By lowering the temperature for stripping, and by using the plastic heat exchangers, the derating of a power plant that used an MEA scrubber could be reduced from 35% to 20%. Moreover the use of plastic heat exchangers would reduce capital costs for the MEA scrubber by 24%. In Phase II, the plastic heat exchanger technology will be scaled-up and tested under controlled laboratory conditions, using several thermally-regenerated absorbents. A preferred absorbent will be identified. Engineering analyses will be performed to determine the potential reductions in energy use and capital costs.

Commercial Applications and Other Benefits as described by the awardee:
The new scrubber technology would allow the nation to use its vast reserves of coal in existing and planned power plants, without contributing to the accumulation of CO2 in the atmosphere. Furthermore, since CO2 is increasingly being used to recover "stranded" oil reserves, the technology could play an important part in extending the nation’s oil resource, by lowering the cost of CO2.