Transport of feedstock

This observation has important implications on the mechanism of agglomerate formation, since, during compaction, points of surface contact will increase together with interparticle attractive forces, and supports practical experience that more elastic agglomerates, such as those formed from phthalocyanines, are usually more difficult to disperse [3]. Powder compaction is relevant to many processing industries and has been considered with other material forms such as coal [4]. 

In response to external forces, particulate solids have characteristics of solid- and liquidlike behaviour, capable of resisting flow until a limiting shear stress is exceeded, after which infinite flow will occur. Unlike liquids, however, shear stress is proportional to the normal load applied rather than the rate of deformation and, unlike solids, the magnitude of shear stress is generally indeterminate, depending on the inter-particle static coefficient 

Displacement efficiency in twin-screw extruders depends on the flight geometry, the extent of conjugation (intermesh) between the screw flights (generally greatest for trapezoidal screws and channels) and the number of thread starts. Screw design and positive-displacement action will also be influenced by the direction of screw rotation. 

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Design possibilities for electrolytic cells are numerous, and the design chosen for a particular electrochemical process depends on factors such as the need to separate anode and cathode reactants or products, the concentrations of feedstocks, desired subsequent chemical reactions of electrolysis products, transport of electroactive species to electrode surfaces, and electrode materials and shapes. Cells may be arranged in series and/or parallel circuits. Some cell design possibiUties for electrolytic cells are... 

Despite the attractions of economic forces driving environmental protection, some cautions and failures have been noted. Firstly, the export of hazardous waste to countries where costs for treatment are lower enhances environmental risks during transport and has the potential for transboundary export in the event of pollution. At the same time, the loss of raw material may deprive the home market of an adequate supply of feedstock for the home-based industry. Secondly, there is considerable scepticism that self-regulation of TBT-based antifoulants could be achieved in a timely manner by the shipping industry. This is an instance where the cost benehts to one industry are born by another commercial sector, notably aquaculture. Thus, protection of the marine environment is likely to be aided by economic factors but the role of government, via taxation and standard setting, is not likely to be usurped. Public education and, in turn, pressure, can promote and support corporate environmentalism. 

At the Coal Research Establishment of the National Coal Board, methods for the liquefaction of coals to produce transport fuels, feedstocks for the chemical industry and high purity carbons suitable for electrode manufacture are being developed. 

The fossil hydrogen production option dominates during the first two decades while the infrastructure is being developed, and also in later periods if only economic criteria are applied initially on the basis of natural gas, later with increasing gas prices more and more on the basis of coal (where available). Carbon capture and storage will be critical for these pathways, if hydrogen is to contribute to an overall C02 reduction in the transport sector. The production mix between gas and coal is highly sensitive to the ratio of feedstock prices a switch occurs at a gas coal price ratio of about 2.5. 

Hydrogen corridors based on hard coal or natural gas are not suitable. It is better to transport these feedstocks directly instead of hydrogen, because of their much higher energy content and consequently lower transport cost and because the infrastructure for it is already in place. 

Biofuels such as biodiesel and bioethanol are, for now, the main alternatives to fossil fuels for the most polluting activities related to transportation. Presently, feedstocks for biofuels production are all of natural origin and as such are subject to uncontrolled seasonal variations. For economic reasons the purchase of these feedstocks from different parts of the world follows the dynamics of commodities markets. ... 

Nitroaromatic compounds (NACs) are one of the widespread contaminants in the environments. Sources of NACs are numerous they originate from insecticides, herbicides, explosives, pharmaceuticals, feedstock, and chemicals for dyes (Agrawal and Tratnyek, 1996). Under anaerobic conditions, the dominant action is nitro reduction by zero-valent iron to the amine. Other pathways do exist, such as the formation of azo and azoxy compounds, which is followed by the reduction of azo compounds to form amines. Also, in addition to the possibility of azo and azoxy compounds, phenylhydrox-ylamine may be an additional intermediate (Agrawal and Tratnyek, 1996). Nitrobenzene reduction forms the amine aniline. Known for its corrosion inhibition properties, aniline cannot be further reduced by iron. Additionally, it interferes with the mass transport of the contaminant to the surface of the iron. The overall reaction is as follows ... 

Feedstock, transportation, and labor cost are all key drivers of regional competitiveness. The cost of different types of feedstock is the least predictable variable, so it is crucial to develop well-informed scenarios before making capacity expansion decisions. The evolution of the competitive landscape, technological discontinuities, and industry conduct (pricing discipline) also need careful monitoring. 

In summary, it is essential that we develop a cost-effective infrastructure for production, collection, storage and pre-treatment of biomass. As highlighted by Nilsson and Kadam, the economic success of a large biorefinery will greatly depend upon the fundamental logistics of a consistent and orderly flow of feedstocks. (Nilsson, 1999 Kadam et al., 2000). Localised small-scale (and perhaps mobile) pre-treatment units will be necessary to minimise transportation costs and supply the biorefinery with a stabilised feedstock (e.g. in the form of a dry solid or a liquid (pyrolysis oil)), which can be stored and thus allow the biorefinery to run... 

Fortunately, the effects of most mobile-phase characteristics such as the nature and concentration of organic solvent or ionic additives the temperature, the pH, or the bioactivity and the relative retentiveness of a particular polypeptide or protein can be ascertained very readily from very small-scale batch test tube pilot experiments. Similarly, the influence of some sorbent variables, such as the effect of ligand composition, particle sizes, or pore diameter distribution can be ascertained from small-scale batch experiments. However, it is clear that the isothermal binding behavior of many polypeptides or proteins in static batch systems can vary significantly from what is observed in dynamic systems as usually practiced in a packed or expanded bed in column chromatographic systems. This behavior is not only related to issues of different accessibility of the polypeptides or proteins to the stationary phase surface area and hence different loading capacities, but also involves the complex relationships between diffusion kinetics and adsorption kinetics in the overall mass transport phenomenon. Thus, the more subtle effects associated with the influence of feedstock loading concentration on the... 

For each hydrogen production pathway and for both states of technology development (current and possible future), the committee developed engineering-economic models to estimate the primary inputs of feedstocks, of electricity or other energy, and of capital equipment for each standard-sized plant and to estimate the resulting outputs of H2 and C02. Within the models, a distinction is made between pathways in which the C02 is sequestered and those in which it is released back into the atmosphere. Additional costs of C02 separation, capture, compression, transport, and sequestration are included for processes in which most of the C02 is sequestered. 

For the hydrogen technologies, these measurements are not strictly well-to-wheels. The energy used is from the point of feedstock delivery to the conversion facility and ignores energy used to produce the feedstock or to transport the feedstock from the point of extraction ( well ) to the con-... 

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