Conversion of solids

Bi-Gas process A high-pressure operation for the conversion of solid fuel into substitute natural gas (SNG) using two stages of gasification. 

J. L. Jones and S. B. Radding, eds.. Thermal Conversion of Solid Wastes and Biomass, ACS Symposium Series 130, American Chemical Society, Washington,... 

H. Alter and J. J. Duim, Jr., Solid Waste Conversion to Energy Current European and U.S. Practices, Marcel Dekker, Inc., New York, 1980, Chapt. 5 H. Alter andj. A. CampbeU, in J. L. Jones and S. B. Radding, eds.. The Preparation and Properties ofDensified Refuse-Derived Fuel, Thermal Conversion of Solid Wastes andBiomass, American Chemical Society, Washington, D.C., 1980, pp. 127—142. 

Reactor calculations could relate to the fractional conversion of solid and the time for replacement of a given amount of solid (bed weight) to ensure that the outlet gas composition is within specifications. Such calculations are complicated by the unsteady-... 

We saw from the Clapeyron equation, Equation (5.1), how the decrease in freezing temperature dT is proportional to the applied pressure dp, so one of the easiest ways of avoiding the lethal conversion of solid ice forming liquid water is to apply a smaller pressure - which will decrease dT in direct proportion. 

Sublimation occurs when you heat a solid and it turns directly into a vapor. It does not pass GO nor does it turn into a liquid. If you reverse the process— cool the vapor so that it turns back into a solid—you ve condensed the vapor. Use the unique word, sublime, for the direct conversion of solid to vapor. Condense can refer to either vapor-to-solid or vapor-to-liquid conversions. 

Plasticisers are substances which can impart plasticity to a polymer, i.e., facilitate the conversion of solid and brittle... 

Fast pyrolysis oil has almost the same elemental composition as the biomass itself hence it can be seen as a kind of liquid wood. It can be transported, can be pressurized and processed more easily than solid biomass. One of the major difficulties in the catalytic conversion of solid biomass is achieving effident con-tad between the heterogeneous catalyst (which is most of the times a solid) and the biomass itself. In this context, bio-oil provides more options for easier catalytic conversion. However, pyrolysis is a very complex and the oil is a difficult to handle chemical mixture. Complete vaporization, for instance, is not possible because part of the components start to decompose and polymerize upon heating... 

Alternative pathways, also discussed in part in the various chapters, include (catalytic) pyrolysis, flash or fast processes for wet biomass without pre-drying, hydro-thermal upgrading (HTU), conversion of solid biomass more or less directly into a natural-gas equivalent called substitute natural gas (SNG), or even to hydrogen. 

A New Measurement Method to Analyse the Thermochemical Conversion of Solid Fuels... 

Finally, the novel part of the three-step model is the identification of a separate unit operation (subsystem) in a PBC system, that is, the thermochemical conversion of the fuel bed, which by logical consequence requires the introduction of a third subsystem referred to as the conversion system. Commonly, PBC systems are modelled with two steps, that is, a two-step model [3,15], see Figure 7. In the two-step model the thermochemical conversion of solid fuels and the gas-phase combustion are lumped together. Several new concepts are deduced in the scope of the three-step model in general and the conversion system in particular, for example the conversion gas, conversion concept, conversion zone, conversion efficiency, which are all explained later in this summary. 

The thermochemical conversion of solid fuels is a complex process consisting of drying, pyrolysis, char combustion, and char gasification. 

APPENDIX B - A REVIEW AND CLASSIFICATION OF THERMOCHEMICAL CONVERSION OF SOLID-FUELS IN THE CONTEXT OF PACKED-BED COMBUSTION AND BIOFUELS.35... 

B.4.2. The analogy between gas-phase combustion and thermochemical conversion of solid... 

APPENDIX B - A Review and Classification of Thermochemical Conversion of Solid-Fuels in the Context of Packed-Bed Combustion and Biofuels... 

Keywords, biomass combustion, solid-fuel combustion, packed bed combustion, grate combustion, thermochemical conversion of solid fuel. 

The success of any mathematical model, and in turn the computer code, depends completely on the clarity of the conceptual model (physical model). The authors have concluded from a comprehensive literature review on the subject of solid-fuel combustion, that there is a slight conceptual confusion in parts of this scientific domain. The first example of this is the lack of distinction between the thermochemical conversion of solid fuels and the actual gas-phase combustion process, which led these authors to the formulation of the three-step model. The thermochemical conversion of solid fuels is a two-phase phenomenon (fluid-solid phenomenon), whereas the gas-phase combustion is a one-phase phenomenon (fluid phenomenon). 

This section presents a classification of conversion concepts (read section 0), described in the literature on PBC, for example, fuel-bed mode (batch or continuous) and fuel-bed configuration (cocurrent, countercurrent, crosscurrent). Some new conversion concepts, namely fuel-bed movement (fixed, moving and mixed) and fuel-bed composition (homogeneous, heterogeneous), are introduced by these authors, which makes this an extended classification compared with earlier classifications in literature [8,9,10,11], The classification is made in the context of the three-step model. The three-step model, see Figure 14 below, is a system theory, which places the theory of thermochemical conversion of solid fuels into the context of PBC. 

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