Product yield and composition

When the first edition of Chemistry of Petrochemical Processes was written, the intention was to introduce to the users a simplified approach to a diversified subject dealing with the chemistry and technology of various petroleum and petrochemical process. It reviewed the mechanisms of many reactions as well as the operational parameters (temperature, pressure, residence times, etc.) that directly effect products yields and composition. To enable the readers to follow the flow of the reactants and products, the processes were illustrated with simplified flow diagrams. 

Tables 4.4 and 4.5 show the effect of temperature on product yield and composition from the pyrolysis of mixed municipal solid waste (MSW) and bituminous coal. Other data11 show that beyond a certain temperature char yield does...

ABSTRACT The radiative pyrolysis of wood (thick cylinders and chip beds) has been investigated experimentally for external radiative heat fluxes in the range 28-80kW/m, resulting in maximum sample temperatures of 600-950K. Radial temperature profiles, product yields and composition, and devolatilization rates have been measured. The influences of wood variety (hardwoods and softwoods) on the pyrolysis characteristics are discussed and comparisons are made with biomass (agricultural residues). 

The scope of work in a first phase of the project included the adaptation of this peat pyrolysis system for conversion of agricultural residues, preliminary testing to identify operating problems, characterization of two feedstocks (oat straw and corn stover) and finally, experiments to determine product yield and composition at various operating conditions. 

Product Yield and Composition. Product yield and composition did not vary significantly within the range of residence times studies. Feed rate did not have a noticeable effect either, although further experiments at 10 kg/h are required. The system output was limited by the feeding system used. It is likely that the kiln could convert more material since conversion was completed within 10 minutes. This was indicated by the fact that gas production fell to zero within 5 to 10 minutes after feeding was stopped. As well, during previous experiments with peat (Campion, 1978), feed rates up to 18 kg/h were used. 

Tsai WT, Lee MK, Chang YM (2007) Fast pyrolysis of rice husk product yields and compositions. Bioresour Technol 98 22-28... 

Beis, S. H., Onay, O., Kockar, O. M. Fixed-bed pyrolysis of safflower seed influence of pyrolysis parameters on product yields and compositions. Renew Energ 2002, 26, 21-32. 

Ultimately, the importance of process control is seen through increased overall process efficiency, allowing the plant engineer to get the most from the process design. This is especially true of distillation control. Most distillation columns are inherently flexible, and a wide range of product yields and compositions can be obtained at varying levels of energy input. A key requirement of any control system is that it relates directly to the process objectives. A control system that does not meet the process objectives or produces results that conflict with the process objectives does not add value to the process. 

Heating rate and residence time exhibit a combined effect on gasification product yields and composition, particularly on tars. These two parameters strongly affect the devolatilization stage, which in turn has an influence on the oxidation stage (Kandiyoti et al., 2006). 

Investigation of the effects of various process parameters on product yield and composition... 

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