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Digitized by Kansas Correctional Industries

Digitized by Kansas Correctional Industries

1 / Bing Shan

Biomass gasification is considered a key technology in reaching targets for renewable energy and CO2 emissions reduction. This thesis studies the feasibility of a new technology of biomass gasification called WoodRoll for the production of Syngas with the aim to replace fossil fuels in the furnaces of the steel company OVAKO in Hofors.  This research attempts to study the techno-economic viability of WoodRoll technology integration with the district heating company HEAB, creating a synergy between the companies and WoodRoll technology. Moreover, a theoretically study of the environmental impact, concerning greenhouse effect and pollutants it is also carried out.   In the future scenario HEAB, as an energy supplier will be the gasification plant owner supplying with Syngas 5% cheaper than the fuels that they use today to Ovako.  Three different scenarios have been studied varying the capacity of the gasification plant. The scenarios are 5MW, 10MW and 15MW capacity.   The study show that the system is technically viable being possible to create a synergy  between the three process improving efficiency and decreasing cost and CO2 emissions.   The results from the economic study show that biomass gasification using WoodRoll technology is a highly interesting investment option for HEAB. From Ovako side, the project is very interesting too since the company can have a combustible 5% cheaper than the fuels used today without doing any investment. In 5MW scenario, 40GWh per year are converted in Ovako from oil to Syngas. With an investment for HEAB of 9.8 mSEK, profits were a Net Present Value of 6.3mSEK with 7.8 years of payback period. In 10MW scenario 80GWh were replaced. In this scenario, required investment was 146 mSEK with a NPV of 32.5 mSEK . Payback in this case was 6.3 years. The most profitable scenario was the case of 15M. With an investment of 188 mSEK the profits of the project were 60mSEK with a payback period of 5.8 years. In the three cases, especially in 15MW case, sensitivity study of the system show that it is very robust to changes in biomass cost and Syngas price. This parameters have a big impact on the profits but a big margin until becomes unfeasible.   From Ovako side, savings for the fuel conversion were 1.2; 2.4 and 3.6mSEK for the 5, 10 and 15MW respectively. Reduction of CO2 emissions was 11, 20 and 30 thousands of CO2 tons for the three scenarios allowing  the company to sell CO2 allowances and having an extra profit of 3, 6 and 8mSEK per year in the 5, 10 and 15MW scenario respectively.

Thesis (M. Sc.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on Jan. 22, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Process Control, Department of Chemical and Materials Engineering, University of Alberta. Includes bibliographical references.

Includes bibliographical references (p. 103-109).

Several comprehensive but time consuming neutronic codes are available for performing nuclear reactor and fuel cycle evaluations. In addition, simple models utilizing collision probability theory are used to perform similar tasks with reasonable accuracy. However, the current collision probability theory treats the heterogeneous reactor configurations with a two region unit cell model. This model does not address several important reactor parameters including spatial self-shielding effects and simultaneous use of different reactor fuels within a reactor core. This dissertation studies the fidelity of expanding the collision probability theory to address the stated shortcomings through analyzing two problems. Problem 1 analyzes the effects of self-shielding. The cylindrical fuel region is divided into several sub-regions and an overall equivalent escape probability from the entire fuel region is developed based on the identified neutron transmission and escape probabilities within each fuel sub-region. The multiplication factor and radioisotopic inventory results based on modified V:BUDS (Visualize: Burnup, Depletion, Spectrum) code are in good agreement with benchmark scenarios for a reactor unit cell. The accurate multiplication factor calculation allows more accurate studies on the maximum fuel burnup and radionuclide inventories of interest in nuclear non-proliferation studies. Problem 2 analyzes the effects of simultaneous use of different fuels within a fuel lattice where the zero neutron leakage assumption across the unit cell boundaries is not valid. The developed methodology expands capabilities of the collision probability theory to a supercell model that allows existence of two different fuels. The radioisotopic inventory results for different fuels obtained from the modified V:BUDS code are in excellent agreement with the benchmark problems. These accurate results may be used in general fuel cycle and transmutation studies within power reactors.

Thesis (MTech. degree in Mechanical Engineering.)--Tshwane University of Technology, 2008.

published_or_final_version / Mechanical Engineering / Master / Master of Philosophy