http://hdl.handle.net/2282/256 Search the Channel search http://teora.hit.no:8443/dspace/simple-search http://hdl.handle.net/2282/440 Title: Carbon dioxide emission reduction by increased utilization of waste-derived fuels in the cement industry <br/> <br/>Authors: Tokheim, Lars-André; Brevik, Per <br/> <br/>Abstract: Considerable reductions in Norway's emissions of greenhouse gases like CO2 are required to meet the commitments of the Kyoto Protocol. CO2 emissions from cement clinker production originate from decarbonation of limestone as well as fuel combustion, and the cement plants in Norway have to comply with requirements given by the pollution control authorities via the national emissions trading system. There are several ways of reducing CO2 emissions from the cement industry. Utilizing CO2- neutral waste fuels as a replacement for fossil fuels is an attractive means of reducing the net CO2 emissions. Using modern kiln technology is another important measure facilitating lower emissions. The Norcem plant in Brevik carried out an extensive modernization project in 2004-5, and as a result of this the plant in Brevik currently uses close to 100,000 tons of CO2-neutral wastefuels every year. The outcome of this is a reduction in fuel-generated CO2 emissions of about 25 % from 1995 to 2005. Reduction of CO2 emissions by secondary methods such as post-combustion measures using amine absorption for the capture of CO2 in the exhaust gas from the cement plant is technically feasible, but expensive and risky. http://hdl.handle.net/2282/436 Title: Assessment of mercury emission at Norcem's cement kiln by use of 203 Hg tracer <br/> <br/>Authors: Eriksen, Dag Øistein; Tokheim, Lars-André; Eriksen, T.A.; Meyer, Julien; Qvenild, Carsten <br/> <br/>Abstract: In manufacture of cement clinker, mercury is introduced in the cement kiln system via the fuels and as constituents in the raw materials, i.e., limestone, iron ore, etc. The permissible emission of Hg to air is very low (0.05 mg/Nm3) due to its toxicity. Thus, it is important to know how mercury distributes and behaves in the kiln system. The objective of the study was to measure the distribution of mercury in the kiln system, to measure the hold up time of Hg, to measure the portion of emission through the chimneys, and to see the dependence of the injection sites on these parameters. The results showed that the amounts of mercury being emitted through the exhaust gases were largely dependent on where it was injected. The residence time of mercury in the system was nevertheless long, after 10 hours it was still increase in the count rate of the mercury absorbed. There was also an immediate increase in the filter dust, but nothing could be measured in the clinker. This knowledge is needed for the reduction of mercury emissions. <br/> <br/>Description: The original publication is available at www.springerlink.com http://hdl.handle.net/2282/369 Title: Nosé-Hoover simulations of aqueous mixtures of small alcohols <br/> <br/>Authors: Holta, Randi Toreskås <br/> <br/>Abstract: We have performed constant energy and constant temperature equilibrium molecular dynamics simulations of model liquids of water, methanol, and ethanol, and of the binary aqueous mixtures of the alcohols at mole fractions alcohol of 0.25, 0.50, and 0.75 at room temperature. The total number of molecules is 256 and the integration timestep is 0.5fs. The molecules are modelled with rigid, nonpolarizable effective site potentials. The TIP4P model is applied for water, and the OPLS models for methanol and ethanol (trans). The thermostatically controlled simulations are performed within the Nose-Hoover formalism, with separate temperature control of the translational and rotational degrees of freedom. Reservoir coupling in the mixtures is determined as a weighted average of the liquid values. We present enthalpies of vaporization and excess configurational energies for the mixtures. Further, we show all radial site-site correlation functions for the self- and cross-interactions. We also present results for self-diffusion coefficients for the components, and the velocity auto correlations functions. The NVT simulations are investigated with respect to the possibility of reproducing the canonical ensemble. We find that the simulations are not entirely within the premises of the canonical ensemble. We suggest that this is due to a too weak coupling (too large heat bath mass). The results are nevertheless found to be in good agreement with experiments and published simulational studies. The NVE simulations for the mixtures reproduce the desired temperature well. The energy conservation is good and improves with decreasing water content. Effects of using only trans-ethanol might be seen for the self-diffusion coefficients. Structural results for both the model alcohols are found to be consistent with V-chains. Upon addition of water, methyl-methyl coordination numbers for both alcohols decrease less than the hydroxyl coordination numbers. <br/> <br/>Description: Avhandling (dr.ing.) - Høgskolen i Telemark / Norges teknisk-naturvitenskapelige universitet http://hdl.handle.net/2282/362 Title: Investment cost estimates and investment decisions <br/> <br/>Authors: Emhjellen, Kjetil; Emhjellen, Magne; Osmundsen, Petter <br/> <br/>Abstract: When evaluating new investment projects, oil companies traditionally use the discounted cashflow method. This method requires expected cashflows in the numerator and a risk-adjusted required rate of return in the denominator in order to calculate net present value. The capital expenditure (CAPEX) of a project is one of the major cashflows used to calculate net present value. Usually the CAPEX is given by a single cost figure, with some indication of its probability distribution. In the oil industry and many other industries, it is a common practice to report a CAPEX that is the estimated 50/50 (median) CAPEX instead of the estimated expected (expected value) CAPEX. In this article, we demonstrate how the practice of using a 50/50 (median) CAPEX, when the cost distributions are asymmetric, causes project valuation errors and therefore may lead to wrong investment decisions with acceptance of projects that have negative net present values.