Reaction lumped

Because the conversion gas is a direct product from the solid-fuel convertibles, according to the lumped reaction formula above, it is composed of a fuel part and a moisture part that is,... 

Fig. 9. Reforming lump reaction network. N, cyclopentane and cyclohexane naphthenes P, C6. paraffins A, aromatics C5-, pentane and lighter.

First, the detailed model is used to simulate the behavior of the real system, and a set of simulated isothermal experimental data is generated including the total heat released by reaction. Then, these data are used to estimate the kinetic parameters of the reduced models and the heats of reaction of the lumped reactions. Finally, the reduced kinetic models are tested in a validation procedure which simulates the operation of a batch reactor and allows one to identify the best reduced model. 

Two different reduced kinetic models have been considered, both involving four lumped chemical species and three and four lumped reactions, respectively. These models describe the time evolution of the following components ... 

It is worth noticing that, in the presence of lumped compounds and lumped reactions, the molar heats of reaction AAr are not known and may vary significantly with temperature. 

Each row of a can be regarded as a lumped reaction that yields a unit amount of the corresponding pivotal species. Thus ai, is the production of species i per mole produced of the first pivotal species, and a2i is the production of species i per mole produced of the second pivotal species. Adding these contributions, we get... 

Although the kinetics of reforming of pure paraffins may be satisfactorily represented by LHHW-type models, such models are difficult to apply for real fuels, such as diesel or gasoline. For such complex systems, it may be more practical to use pseudo-homogeneous kinetics. For example, hydrocarbon fuel components can be lumped in groups with similar properties and kinetic behaviors for example, paraffins are also grouped into lumped reactions. However, the levels of simplification must be carefully evaluated to make them consistent with the final aim of the kinetic model. 

Appendix 1. MAMA Program Automatic Generation of Primary Lumped Reactions 152... 

In principle, heavy radicals could undergo also H-abstraction, addition on unsaturated bonds and recombination reactions. It is quite easy to demonstrate how little relevance these reactions have compared with the isomerization and decomposition ones. This helps drastically reduce the total number of radicals and reactions to be considered. All of the intermediate alkyl radicals, higher than C4, are supposed to be instantaneously transformed into their final products. With reference to the primary products of Table III, the heavy radicals from pentyl up to octyl undergo direct isomerization and decomposition reactions to form smaller radicals and alkenes. Therefore, large sections of the kinetic scheme can be reduced to a few equivalent or lumped reactions whilst still maintaining a high level of accuracy. The complete kinetic scheme shown in Fig. 2 can be then simply reduced to this single, equivalent or lumped reaction ... 

The sets of similar reactants, intermediates and products in the previous lumped reaction are also an initial example of lumped species. Thus, lumped species A are defined as a weighted mixture of several isomers ... 

It is important to stress that this lumped reaction allows a significant reduction in both feed and intermediate species as well as in reactions, yet still retaining a very high level of accuracy in the prediction of the various products of pyrolysis. 

For an exponential initial distribution (a = 1), the lump reaction thus is second order. 

The lumped reactions (1) and (2) group together the following elementary reactions ... 

The corresponding lumped reaction can be obtained by multiplying each reaction by a coefficient and adding them and stating that the quasi-stationary species do not appear in the lumped equation for the reaction the following system is then obtained ... 

This computer program carries out the reduction of detailed mechanisms using the Quasi- Stationary-State Approximation (QSSA). When the negligible species have been eliminated and the quasi-stationary species identified, the algorithm looks for a set of independent reactions allowing the quasi-stationary concentrations to be calculated by applying the QSSA. Lumped reactions are obtained by a linear combination of elementary reactions of the detailed mechanism. 

Fluidized Bed Reactor. Two-Phase Model with Ten Lump Reaction Scheme... 

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