Biomimetic Membrane for CO2 Capture from Flue Gas
These Phase III experiments successfully addressed several issues needed to characterize a permeator system for application to a pulverized coal (PC) burning furnace/boiler assuming typical post-combustion cleanup devices in place. We completed key laboratory stage optimization and modeling efforts needed to move towards larger scale testing. The SOPO addressed six areas. Task 1--Post-Combustion Particle Cleanup--The first object was to determine if the Carbozyme permeator performance was likely to be reduced by particles (materials) in the flue gas stream that would either obstruct the mouth of the hollow fibers (HF) or stick to the HF bore wall surface. The second, based on the Acceptance Standards (see below), was to determine whether it would be preferable to clean the inlet gas stream (removing acid gases and particulates) or to develop methods to clean the Carbozyme permeator if performance declined due to HF block. We concluded that condensation of particle and particulate emissions, in the heat exchanger, could result in the formation of very sticky sulfate aerosols with a strong likelihood of obtruding the HF. These must be managed carefully and minimized to near-zero status before entering the permeator inlet stream. More extensive post-combustion cleanup is expected to be a necessary expense, independent of CO{sub 2} capture technology This finding is in agreement with views now emerging in the literature for a variety of CO{sub 2} capture methods. Task 2--Water Condensation--The key goal was to monitor and control temperature distributions within the permeator and between the permeator and its surroundings to determine whether water condensation in the pores or the HF bore would block flow, decreasing performance. A heat transfer fluid and delivery system were developed and employed. The result was near isothermal performance that avoided all instances of flow block. Direct thermocouple measurements provided the basis for developing a heat transfer model that supports prediction of heat transfer profiles for larger permeators Tasks 3. 4.1, 4.2--Temperature Range of Enzymes--The goal was to determine if the enzyme operating temperature would limit the range of thermal conditions available to the capture system. We demonstrated the ability of various isozymes (enzyme variants) to operate from 4-85 C. Consequently, the operating characteristics of the enzyme are not a controlling factor. Further, any isozyme whose upper temperature bound is at least 10 C greater than that of the planned inlet temperature will be stable under unanticipated, uncontrolled 'hiccups' in power plant operation. Task 4.4, 4.4--Examination of the Effects of SOx and NOx on Enzyme Activity (Development of Flue Gas Composition Acceptance Standards)--The purpose was to define the inlet gas profile boundaries. We examined the potential adverse effects of flue gas constituents including different acids from to develop an acceptance standard and compared these values to actual PC flue gas composition. Potential issues include changes in pH, accumulation of specific inhibitory anions and cations. A model was developed and validated by test with a SO{sub 2}-laden stream. The predicted and actual data very largely coincided. The model predicted feed stream requirements to allow continuous operation in excess of 2500 hours. We developed operational (physical and chemical) strategies to avoid or ameliorate these effects. Avoidance, the preferred strategy (noted above), is accomplished by more extensive cleanup of the flue gas stream. Task 5--Process Engineering Model--We developed a process-engineering model for two purposes. The first was to predict the physical and chemical status at each test point in the design as a basis for scale-up. The second was to model the capital and operating cost of the apparatus. These were accomplished and used to predict capex, opex and cost of energy. Task 6--Preliminary Commercialization Plan--We carried out analyses of the market and the competition by a variety of parameters. The conclusion was that there is a large and rapidly growing market that will support good business growth.
- Research Organization:
- Carbozyme, Incorporated
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG26-06NT42824
- OSTI ID:
- 926669
- Country of Publication:
- United States
- Language:
- English
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