Penetration model for gas absorption with reaction in a slurry containing fine insoluble particles

A pseudo-homogeneous penetration model describing the mass transfer of a gas to a slurry containing non-soluble reacting or adsorbing particles is presented. This numerical model takes into account the finite reaction/adsorption capacity of the particles. The consequences of this finite capacity on the enhanced absorption are demonstrated for the absorption of hydrogen in metal hydride slurries. Experimental enhancement factors for this system are evaluated and compared to the model predictions. A critical Hatta number has been derived above which saturation of the solid occurs resulting in decreased enhancement factors.\ud \ud The mass transfer of a gas into a slurry with adsorbing particles is a similar problem. For the regime of mass transfer limitation tot the particles with a linear adsorption isotherm the enhanced adsorption is discussed

Hot biogas conditioning using pulsed corona

A new technology area for pulsed corona is hot biogas cleaning, important in view of the growing interest in biomass gasification. Our work concentrates on the development and optimization of pulsed electrical methods for treatment of thermally generated biogas. Corona energized by narrow voltage pulses (100 kV) makes a well ordered and concentrated deposition possible of electrical energy from a circuit into a hot polluted gas. The created plasmas can break down various contaminants. Successful introduction of pulsed corona for industrial processes very much depends on the reliability of high-voltage and pulsed power technology and on the efficiency of energy transfer. In addition, we must achieve adequate electromagnetic compatibility (EMC)

Quantifying the environmental performance by exergy-based indicators

Over the last three decades environmental issues have a direct impact on technology assessment and policy decisions. One of the difficulties with measuring environmental performance is lack of consensus on evaluation of relevant aspects, including materials and energy use, air emissions, solid and hazardous waste and water pollution. In practice various environmental indicators are used, usually restricted to one specific aspect. In case of complex environmental metrics, such as Life Cycle Analysis, more environmental aspects are involved but they are usually judged in a subjective way. This Chapter presents development aspects of environmental performance indicators based on exergy. The concept exergy is based on the second law of thermodynamics and is very suitable for assessment of various systems, ranging from chemical and energy processes through economic sectors to entire societies. Traditionally, exergy-based indicators are restricted to measurement of thermodynamic efficiency. Recently, they are coupled with Life Cycle analyzes concepts, such as Cumulative Exergy Consumption (CExC). Finally, exergy indicators are extended with environmental and economic issues, as applied in Extended Exergy Accounting (EEA). EE indicators can be expressed in monetary as well as energy units. However, they are sensitive to capital conversion factors, which can be evaluated for various levels, including individual technologies, economic sectors, and entire societies

Quantifying the environmental performance by exergy-based indicators

Over the last three decades environmental issues have a direct impact on technology assessment and policy decisions. One of the difficulties with measuring environmental performance is lack of consensus on evaluation of relevant aspects, including materials and energy use, air emissions, solid and hazardous waste and water pollution. In practice various environmental indicators are used, usually restricted to one specific aspect. In case of complex environmental metrics, such as Life Cycle Analysis, more environmental aspects are involved but they are usually judged in a subjective way. This Chapter presents development aspects of environmental performance indicators based on exergy. The concept exergy is based on the second law of thermodynamics and is very suitable for assessment of various systems, ranging from chemical and energy processes through economic sectors to entire societies. Traditionally, exergy-based indicators are restricted to measurement of thermodynamic efficiency. Recently, they are coupled with Life Cycle analyzes concepts, such as Cumulative Exergy Consumption (CExC). Finally, exergy indicators are extended with environmental and economic issues, as applied in Extended Exergy Accounting (EEA). EE indicators can be expressed in monetary as well as energy units. However, they are sensitive to capital conversion factors, which can be evaluated for various levels, including individual technologies, economic sectors, and entire societies

Efficiency analysis for the production of modern energy carriers from renewable resources and wastes

Two global problems related to the use of fossil fuels are fast depletion and environmental damage. Biomass has a great potential as a clean renewable feedstock for producing modern energy carriers such as biodiesel, methanol, and hydrogen. However, the use of biomass is accompanied by possible ecological drawbacks such as limitations of land or water and competition with food production. For biomass-based systems, a key challenge is thus to develop efficient conversion technologies. This paper presents the efficiency analysis based on the Second Law of Thermodynamics for production of energy carriers from biomass. It is shown that the exergetic efficiency of renewable energy carriers is lower than that for fossil fuels. The highest efficiency is achieved for hydrogen production from high quality feedstock that is comparable with fossil fuels