熱能與動力工程專業畢業論文外文文獻及翻譯(更新版)

　　

【正文】 he purposes of this analysis, no sulphur capture technology was built into the design. . Carrying charge Each technology option has its associated costs of implementation over and above the regular plant operational costs. All three options had associated carrying charge for the initial capital cost of the cofiring system. This is calculated using the following equation (input values are presented in Table 1): where V is the initial investment, D/V is the debt fraction of investment and cc is the carrying charge fraction. Another annual cost associated with the implementation of biomass cofiring is increased plant operation and maintenance costs. The gasification and direct cofiring options also have increased cost due to reduced capacity factor and plant’s annual generation. From these yearly savings and costs, the yearly ine after tax was calculated. All inputs for the economic analysis are also listed in Table 3. The cost of biomass in this analysis is the cost of delivered chipped hardwood, as shown in Table 2. Cofiring costs could be less if a biomass waste material, such as sawdust from lumber mills or sewage sludge from nearby plants were available and fuels need to be sourced locally as the transportation costs of biomass could erode its cost advantage due to the low energy density of biomass fuels. The present analysis is very conservative as it did not include the avoided tipping fees that would otherwise be incurred through the disposal of unwanted biomass. In one analysis performed by the . Department of Energy (TR109496), the avoided tipping fees accounted for over 50% of the savings generated. The increasing demand for biomass products in the power generation industry has made them a modity in a number of regions around the world. For this reason the authors did not include this savings as owing to this demand, it is unlikely that the ine from tipping fee avoidance would continue in the future. For the evaluation we used the Weighted Average Cost of Capital (WACC). This represents the rate of return required by a corporation on its new assets to maintain a firm value, and is 外文文獻 及譯文 13 prised of the rate of return required by both equity holders and debt holders. It is calculated by the following equation: where Re is the cost of equity, Rd is the cost of debt, Tc is the corporate tax rate, E is the equity amount, D is the debt amount and V is the total investment. . Capital cost allowance (CCA) Capital cost allowances for power generation equipment fall under CCA class 47 of Revenue Canada with a depreciation rate of 8%. Since biomass cofiring is not currently employed in Canada, equipment use for a cofiring operation is not specifically described under Canadian Ine Tax Act. From the foregoing description of cofiring technologies it would appear that direct cofiring option requires capital investment primarily for new fuel processing and handling equipment as it uses existing boiler and electrical generating equipment at the power plant. The CCA class 8 definition, which applies to processing machinery and material handling and storage equipment, better reflects the type of equipment used. The CCA class 8 has a 20% rate. For the other two cofiring options (indirect cofiring and gasifier cofiring), for capital cost amortization, the Revenue Canada guideline of allowing half the rate in the first year was used. . Internal rate of return 外文文獻 及譯文 14 Internal rate of return (IRR) for this new investment is the discount rate that would make the present value (NPV) of the investment’s ine stream total to zero. It is an indicator of the efficiency or quality of an investment, as opposed to present value (NPV), which indicates value or magnitude. The present analysis is based on IRR. 6. Results . Fuel consumption The biomass consumption differs for each cofiring option due to the different efficiencies of the cofiring systems. The fuel required for direct cofiring is the lowest and represents the base amount of biomass required to provide 10% of the heat energy in the furnace of the PC boiler. The fuel requirement for the external CFB boiler is the highest of the three and was calculated based on the given turbine efficiency of 88% as well as the calculated efficiency of CFB boiler. This efficiency was found to be % and was based on the calculated losses from the boiler. Table 4 presents the breakdown of energy losses in the external CFB boiler. The biomass consumption rates and costs of the three cofiring options are given in Table 5. 外文文獻 及譯文 15 . Emission credits ine For the economic analysis, the main source of ine for the three cofiring options is the emissions credits earned through the reduction in coal usage. The yearly offset of coal, subsequent reductions in emissions and emission credit ine are presented in Table 6. IRR estimates for the three cofiring options are given in Table 7. The analysis indicates that direct cofiring can offer an internal rate of return of more than twice that of indirect cofiring. Direct cofiring however suffers from the largest uncertainty about fouling and corrosion of its superheater tubes, and resulting breakdown of the plant while handling biomass. This loss, conservatively estimated at 1%, could have signif。 An option towards meeting a renewable energy portfolio: Cofiring offers a fast track, lowcost opportunity to add renewable energy capacity economically as it can be added to any coalfired plant immediately, with minimum investment. Ondemand power production: Unlike other renewable energy technologies (.: solar, wind), biomassbased power generation can be made available whenever it is needed. This helps to accelerate the capital investment payoff rate by utilizing a higher capacity factor. 18