Methodology for Attrition Evaluation of Oxygen Carriers in Chemical Looping Systems: Final Scientific/Technical Report - Phase II
- Envergex LLC, Sturbridge, MA (United States)
- Univ. of North Dakota, Grand Forks, ND (United States)
- Microbeam Technologies Inc., Grand Forks, ND (United States)
This Small Business Innovation Research (SBIR/STTR) Phase 2 project targets the continued development of novel equipment/methodology for the attrition evaluation of oxygen carriers (OCs) in coal-based Chemical Looping Combustion (CLC) systems. Proof-of-concept was conducted during the Phase I program, in which the equipment/test methodologies were evaluated with a limited number of oxygen carriers and test conditions for jet attrition in fluidized bed-based CLC systems. The overall objective of the Phase II project was to develop the characterization methodology further to include a second-attrition mechanism (cyclonic attrition) critical in CLC systems involving circulation of OC materials; and to more extensively evaluate an extended number of materials being considered by the development community. Experimental results obtained from this research have shown that the constructed jet attrition and cyclonic attrition evaluation laboratory testing units provide valuable results for the rapid screening of oxygen carriers. Based on the test data, numerical models were developed for each attrition mode that can be used to investigate attrition rates at operational CLC conditions. Initial validation has been carried out using pilot-scale data from the literature and shows promise; however, the models require additional verification and potential refinement to establish their operability and applicability limits to larger-scale industrial process conditions. Testing at high temperature and cyclic oxidation-reduction conditions using the developed evaluation method shows that thermal and chemical effects are crucial to accurately determine the performance of oxygen carriers. We show that “standardized” testing under ambient conditions used by previous researchers is unreliable, and in many cases provides incorrect results regarding oxygen carrier attrition and performance. The laboratory jet and cyclonic attrition evaluation test units are extremely versatile; they can be used to obtain data on multiple parameters related to the oxygen carrier including the degree of reduction, oxygen carrying capacity, attrition resistance, agglomeration, optimum material operability conditions, and OC lifetime. From the data obtained in this study, attrition in the cyclone(s) was estimated to have a slightly more pronounced impact than the jetting region for an industrial fluidized bed-based CLC system. The attrition results from the two laboratory setups were scalable and the model projections for attrition in a 10 kWth unit was within an order of magnitude of the predicted values. Ultimately, the developed test method and the associated test facility designs will allow for rapid evaluation of a wide range of oxygen carrier materials for CLC. The proposed test methodology has much broader applicability to other gas-solid reacting systems such as limestone reactivity and performance for sulfur capture in fluidized bed combustion. As an example, during the Phase I project, we performed screening of various limestone materials for optimum performance and usage in a coal-fired fluid bed boiler for a commercial client. These tests identified the lowest cost sorbent that the client should deploy resulting in significant annual savings in material consumption and operating costs. The most important anticipated public benefit of this research is the acceleration of the development of chemical looping technology for lowering greenhouse gas emissions from fossil fuel combustion.
- Research Organization:
- Envergex LLC, Sturbridge, MA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- SC0011984
- OSTI ID:
- 1465206
- Type / Phase:
- STTR (Phase II)
- Report Number(s):
- DOE-Envergex-PhII-SC0011984
- Country of Publication:
- United States
- Language:
- English
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