Selectivity of energy requirements

On to the specificity of energy disposal and selectivity of energy requirements... 

The prior distribution does not seek to match experimental results. Rather, it provides a reference against which to compare. The (logarithmic) deviation of the actual (observed or computed) distribution Irom the prior one is known as the surprisal. Then, armed with detailed balance, we will also seek to characterize the energy requirements of chemical reactions. Consistent with the arguments already presented, tiie measnre of specificity of energy disposal in the forward reaction turns out to be equal to the measure of selectivity of energy requirement in the reverse reaction. 

The prior distribution is not chosen to agree with experiment. It is instead a reference against which experimental (or computational) results are to be evaluated. We discuss such applications in Section 6.4.2. Then we go to measures of selectivity of energy requirements. In Section 6.4.5 we modify the prior distribution by taking into consideration that not only energy but also angular momentum need to be conserved. Explicit results for prior distributions are given in Section 6.4.1.2. 

Measure of selectivity in energy requirements of chemical reactions... 

This characteristic will govern, to a large extent, the operating expenses (OPEX) of the process. Standard post-combustion capture processes, such as gas liquid absorption in a chemical solvent (MEA), typically require 3.5 GJ (thermal basis) per ton of recovered CO2, and 2 GJ ton is often considered as a target. The importance of energy requirement considerations in the carbon capture process selection results from the secondary CO2 emissions which are generated by the capture process. Figure 2.5 summarizes the interplay between CO2 emissions by the reference plant and secondary, additional CO2 emissions due to the capture step. 

Figure 2.8 Influence of membrane selectivity on energy requirement for 10% and 20% CO2 content in feed mixture. Operating conditions vacuum pumping. Separation targets capture ratio R) 80%, CO2 purity (y) 0.8.

The transition between levels coupled by the oscillating magnetic field B corresponds to the absorption of the energy required to reorient the electron magnetic moment in a magnetic field. EPR measurements are a study of the transitions between electronic Zeeman levels with A = 1 (the selection rule for EPR). 

The selection of a process can be complex, requiring carehil evaluation of the many variables for each appHcation. The hemihydrate process is energy efficient, but this may not be an overriding consideration when energy is readily available from an on-site sulfuric acid plant. The energy balance in the total on-site complex may be the determining factor. 

Synthesis. Because of the limited availabiUty of by-product isoprene much effort has been devoted to synthesis of isoprene. Most routes tend to have marginal selectivity and require large amounts of energy. The choice of which route is preferable depends on availabiUty and cost of raw materials and cost of energy. Several synthetic routes have been practiced commercially (103—108). 

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