Design demands

The facts that different companies using different processes can each make money and that even within the same company a product may be produced by two entirely different processes illustrate the challenge and headaches connected with process design. Design demands a large amount of creativity. It differs from the usual mathematics problem in that there is more than one acceptable answer. Theoretically there may be a best answer, but rarely are there enough data to show conclusively what this is. Even if it could be identified, this best design would vary with time, place, and company. 

As argued in Chapter 2.1.2 this work focuses on production network design. Demand is assumed to be independent of production network design decisions and the cost structure achieved. Also, unlimited quantities of raw materials are assumed to be available. An extensions to include make-or-buy decisions (and possibly vendor selection) is provided to accommodate application cases where sourcing decisions have to be included. 

While it should be self-evident that a rational reactor design demands a knowledge of both the fluid dynamic environment and the detailed process kinetics, the latter are rarely available. In many instances this leads to the severe limitation of many important reactions by an inadequate fluid dynamic intensity. Some of these are known to be fast, e.g., liquid-phase nitrations, while others are (incorrectly) assumed to be slow, e.g., most polymerizations. In these circumstances the pragmatic approach is to use a high-intensity reactor for each system and then to assess the impact upon the space-time productivity. Obviously, an intrinsically slow system is resistant to further acceleration and this will rapidly become evident. One significant qualification of this contention involves the very... 

Commercialization of PCN requires close consideration of potential environmental impacts, an improved understanding of synthesis mechanisms, and the PCN designs demanded by end-users. " ... 

In addition the electrodes contain a metal grid as current collector. As different partial processes are combined in the operation of a gas-fed electrode its design demands a optimization with respect to its parameters. The operation can be tuned to the electrolyte/reactant system by the choise of composition (binder, catalyst support carbon. 

The compositional Box design [4], for three input variables was used to plan the experiments. This design demanded defining three material variables (which were later transformed into coded values), their ranges and technical properties to be selected as representative. 

The design of internals for RD is more severe than for conventional nonreactive countercurrent vapor-Uquid processes [5-7]. Feasibility and efficiency of a particular RD process strongly depend on the appropriate choice of internal characteristics Uke liquid residence time, separation efficiency, liquid holdup and pressure drop. Even if column internals for homogeneous RD are similar to noncatalytic column internals, modifications are often necessary to meet optimum reactor design demands. If the use of solid catalysts is necessary, specific bifunctional... 

Dangerous failure rates of safety instrumented system components assumed during the design Demand rate on the safety instrumented system assumed during the risk assessment... 

Non-destructive testing (NDT) Design demands on materials selection Failure analysis... 

As shown in Table 1, it could be concluded that when the repair cycle is short than 70 days, the MTBCF of the source array will be larger than 35,000 hours, and there are still a tolerance of 11.73%. In this way, the designing demand will be satisfied properly. 

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