Process evaluation factors

When investigating the suitability of a particular resin-bound separations process, the following factors are often important (i) resin consumption (ii) solvent usage (iii) productivity-chemical, optical and volume yields (iv) total number of separations steps and (v) capital costs. For any particular process, these factors differ in their relative importance. However, when evaluating a new separations method it is useful to examine each of these factors. The nonchromatographic separation method... 

NFPA developed Standard 704 as a tool for identification and evaluation of potential hazards during emergency response, not for application to chemical process safety. The instability rating is a part of this standard. It was not intended to be used to measure reactivity, but rather to measure the inherent instability of a pure substance or product under conditions expected for product storage. The instability rating does not measure the tendency of a substance or compound to react with other substances or any other process-specific factors, such as operating temperature, pressure, quantity handled, chemical concentration, impurities with catalytic effects, and compatibility with other chemicals onsite. 

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. 

Stimulus trains of varying lengths (0.5-1.2 s) and frequencies of 10-200 pps can provide additional information. As stimulus frequency is increased, there is greater tetanic fusion and higher peak forces are produced. A force-frequency curve (F-F) can also be generated to evaluate factors that affect muscle contractile speed (time-to-peak, half-relaxation). If, for example, disease processes lead to slower contraction/relaxation time, more tetanization occurs at lower frequencies and the shape of the F-F curve will be shifted compared to normal muscle. 

This expression has the Arrhenius form and E is the maximum value of the potential energy, an activation energy for deposition. This is expected because the potential profile of fig. 2 resembles the plot of the energy against reaction coordinate used in the theory of rate processes. The factor /(//m) accounts for the dependence of the diffusion coefficient on the distance and evaluations show that it can decrease the frequency factor in eqn (16) by two orders of magnitude. 

Computers are used extensively in automatic plant process control systems. The computers must convert signals from devices monitoring the process, evaluate the data using the programmed engineering equations, and then feed back the appropriate control adjustments. The equations must be dimensionally consistent. Therefore, a conversion factor must be part of the equation to change thfe measured field variable into the proper units. 

Evaluate uncertainty and sensitivity analysis of the relative rankings. Uncertainty needs to be accounted for and tracked in the risk assessment process. At times it may be an accounting process, listing factors that introduced uncertainty into the assessment process. At other times the uncertainty can be represented by a distribution process and a Monte Carlo process employed to provide a range of values. 

Figure 4 provides an overview of the elements of a complete typical chemical process for consideration in targeting P2 opportunities. Although the focus for identifying P2 opportunities is necessarily on the process, other factors, such as off-specification (off-spec) product, maintenance wastes, leaks, and spills can also be significant causes of pollution. Table 2 identifies numerous examples of potential sources of pollution and waste in chemical process plants. Once these have been identified, P2 solutions can be subsequently evaluated based on the general guidelines provided in Table 3. ... 

The isolated vascular perfused liver preparation mimics the liver in vivo and has normal cell-cell topography, vasculature, blood, and bile hows. This model is used to directly measure the contribution of the Uver in the presystemic eUminahon of drugs, and to evaluate factors that affect this process. 

The magnitudes of chemical kinetic and macroscopic transport processes, evaluated as their linear rates [linear rate=(mass flux)/(concentration or density) = F/p], indicate that great differences exist between the mineral dissolution rates, as reported from laboratory measurements, and the rates derived from river-water composition and volume flow. These differences point to an important role of the physical structure of the weathering zone and water residence time within it that control mineral dissolution fluxes and transport of the reaction products. An additional factor responsible for the faster rates of chemical weathering could be bacterial, activity which may be expected to vary from lower levels in the cold regions to the higher levels in the tropics, in parallel with the rates of net primary productivity. 

Users need not complete data input in the Data Entry module. Any information omitted by the user will be requested interactively when required by POTW EXPERT during the Major Unit Process Evaluation or Evaluation of Performance Limiting Factors. POTW EXPERT will attempt to reason in the absence of user input data, but will not conclude its reasoning process if critical input is missing. 

Much of the information required to reason about the PLFs is carried from the Data Entry and Major Unit Process Evaluation modules. Using an essentially forward-chaining inference mechanism, the system uses information already available from these modules to complete a preliminary assessment of each PLF. The initial assessment collects and analyzes information to conclude whether a factor adversely... 

The POTW EXPERT system demonstrates that a microcomputer-based expert system can effectively represent a complex evaluation methodology, evaluate the capability of a secondary wastewater treatment facility s major unit processes, detect factors which potentially limit performance, and categorize them according to their influence on plant performance. The model is presented in a logical and structured manner to allow wastewater professionals unfamiliar with the CPE process to effectively employ this wastewater treatment methodology. 

ES-1 Evaluation Factor Rating Comparison of Tier 1 Munitions Processing Technologies with U.S.EDS, 3... 

Table ES-1 provides summary ratings of these Tier 1 international munitions processing technologies for the five evaluation factors noted above as well as comparative rat-...

Public stakeholders are concerned, naturally, about things like process maturity, efficacy, and safety however, the concerns raised under this evaluation factor have been raised specifically by public stakeholders in the United States in the past with regard to stockpile and non-stockpile operations. 

As defined in detail in Chapter 3, the committee used five basic evaluation factors to assess the status of Tier 1 technologies. These factors were commented on earlier in this chapter in the respective evaluation factors analysis sections for each of the three Tier 1 international munitions processing technologies. 

Table 4-9 rates the Tier 1 munitions processing technologies according to these evaluation factors and compares them to the EDS technology that is presently in use by the NSCMP. The symbols used in the ratings scheme are also defined in more detail in Chapter 3. 

Table 5-3 rates the Tier 1 agent-only processing technologies according to the evaluation factors defined in detail in Chapter 3. The ratings scheme is described in more detail in that chapter. 

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