Process evaluation economics

The use of process flow diagrams and material balances are worthwhile methods to quantify losses or emissions and provide essential data to estimate the size and cost of additional equipment, other data to evaluate economic performance, and a basefine for tracking the progress of minimization efforts (Ref. 3). Material balances should be apphed to individual waste streams or processes and then utilized to construct an overall balance for the facility. Details on these calculations are available in the literature (Ref. 8). In addition, an introduction to this subject is provided in the next section. 

Because the physical characteristics of the particulate solids both affect, and are affected by each unit operation, there exists an interaction between them. The study of particulate systems thus provides methods for synthesizing and evaluating economically optimum process configurations. 

The flowsheet also describes the process to management as well as those concerned tvith preparing economic studies for process evaluation. 

There are different ways of producing chlorine from brine, for example, Dow cells, Hooker cells, and mercury cells. Which process is to be used must be known in order to make an accurate economic evaluation, since the capital costs and operating costs are different for each of these processes. The process engineer may have to investigate the different processes and economically evaluate each before deciding which process is best. 

Various additional (secondary solvent cleaning) procedures have been proposed, including vacuum distillation [30], treatment with macroreticular anion-exchange resins [31], and treatment with activated alumina [32,33]. These secondary cleanup operations increase solvent quality, and continue to be studied to better evaluate their process and economic advantages. In the French UP3 Purex plant, vacuum distillation is used to regulate TBP concentration and solvent quality with beneficial effects. The latter include... 

Evangelista, R.L., Kusnadi, A.R., Howard, J.A., andNikolov, Z.L. (1998). Process and economic evaluation of the extraction and purification of recombinant beta-glucuronidase from transgeiuc com. Biotechnol. Progress 14 807-614. 

Disparate elements, which affect economic decisions for bioprocesses, can be combined into a logical approach. An attempt must be made to combine fundamentals of bioreactor design, downstream processing, and properties of biomolecules in the context of process evaluation. The ability to set technical priorities based on economic assessment is essential, and requires communication betv/een researchers, process engineers, technical managers, and marketing managers. 

Process capability evaluation Stability and variability of process output, economic limits... 

Estimation of column costs for preliminary process evaluations requires consideration not only of the basic type of internals but also of their effect on overall system cost. For a distillation system, for example, the overall system can include the vessel (column), attendant structures, supports, and foundations auxiliaries such as reboiler, condenser, feed neater, and control instruments and connecting piping. The choice of internals influences all these costs, but other factors influence them as well. A complete optimization of the system requires a full-process simulation model that can cover all pertinent variables influencing economics. 

A group at Industrial Research Limited in New Zealand recently reported the results of a study to determine if a cross-linked enzyme crystal-catalyzed resolution can compete with alternative chiral technologies in the pharmaceutical and chemical process industries. The group used the enantioselective hydrolysis of a-phenylethyl acetate catalyzed by ChiroCLEC -PC as a model system (Fig. 13). Based on their results with 270 kg of racemate, they evaluated the economics of mnning the process at the 600-kg batch scale and concluded that this process is economically feasible [38],... 

D. Example 7 A Process and Economic Evaluation of /3-Glucuronidase (rGUS) Production from Transgenic Corn... 

To assess the feasibility of the proposed olive oil deacidification plant we need an economical evaluation of the overall process. An economical study (9) was thus performed by simulating all the debits and credits involved in the industrial plant. The analysis was performed at constant prices instead of real prices, and the units are in Portuguese escudos (PTE). 

Process identification Laboratory verification Reaction flow schematic Preliminary flow process Preliminary economic evaluation Process development Mass and energy balance Process flow scheme Site selection... 

To be capable of making a valid choice among the various alternatives, or to compile a classification in terms of overall flow sheets or operating sequences, if several processes are in competition, petrochemical process evaluation must be supplemented by an economic study. 

The difficulty in a process evaluation is not the computations, but the variability in tile terminology that appears in the literature, which is a result of differences in company practice. Another difficulty is that in many cases the basis of the economic data reported in the literature is not clear as to what is included in the data. When economic data are not clearly defined, our only recourse is to conqiare data fi-om several sources or to assume the worst case. Baasel [37] discusses the pitfalls of economic data. 

A thermal expansion joint may be installed on the exchanger shell. As plant size increases, the shell-and-tube heat exchanger becomes more cost effective and will be the exchanger of choice. At intermediate sizes, both types must be evaluated for process and economic reasons. 

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