The Final Design

As the flowsheet becomes more firmly defined, the detailed process 

LinnhoflF, B., Townsend, D. W., and Boland, D., et al., A Users Guide on Process Integration for the Efficient Use of Energy, IChemE, Rugby, U.K., 1982. 

Stephanopoulos, G., Linnhoff, B., and Sophos, A., Synthesis of Heat Integrated Distillation Sequences, /ChetnE Symp. Ser., 74 111, 1982. 

Triantafyllou, C., and Smith, R., The Design and Optimization of Fully Thermally Coupled Distillation Columns, Trans. IChemE, part A, 70 118, 1992. 

and Linnhoff, B., The Design of Separators in the Context of Overall Processes, Trans. IChemE ChERD, 66 195, 1988. 

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In general, the final network design should be achieved in the minimum number of units to keep down the capital cost (although this is not the only consideration to keep down the capital cost). To minimize the number of imits in Eq. (7.1), L should be zero and C should be a maximum. Assuming L to be zero in the final design is a reasonable assumption. However, what should be assumed about C Consider the network in Fig. 7.16, which has two components. For there to be two components, the heat duties for streams A and B must exactly balance the duties for streams E and F. Also, the heat duties for streams C and D must exactly balance the duties for streams G and H. Such balemces are likely to be unusual and not easy to predict. The safest assumption for C thus appears to be that there will be one component only, i.e., C = 1. This leads to an important special case when the network has a single component and is loop-free. In this case, ... 

These small positive and negative errors partially cancel each other. The result is that capital cost targets predicted by the methods described in this chapter are usually within 5 percent of the final design, providing heat transfer coefficients vary by less than one order of magnitude. If heat transfer coefficients vary by more than one order of magnitude, then a more sophisticated approach can sometimes be justified. ... 

The final design shown in Fig. 16.7 amalgamates the hot-end design from Fig. 16.5c and the cold-end design from Fig. 16.6c. The duty on hot utility of 7.5 MW agrees with Qnmm and the duty on the cold utility of 10 MW agrees with Qcmm predicted by the composite curves and the problem table algorithm. 

Following this approach, the design is straightforward, and the final design is shown in Fig. 16.176. It achieves the energy targets... 

D. R. Mouta and co-workeis, Mayards Analysis of the Final Design of the Improved Black Powder Process, Vols. 1—2, Rpt. J6329, Illinois Institute of Technology, Chicago, 1963. 

Flux response to concentration, cross flow or shear rate, pressure, and temperature should be determined for the allowable plant excursions. Fouling must be quantified and cleaning procedures proven. The final design flux should reflect long-range variables such as feed-composition changes, reduction of membrane performance, long-term compaction, new foulants, and viscosity shifts. 

The final design should meet process requirements (within reasonable expectations of error) at lowest cost. The lowest cost should include operation and maintenance costs and credit for ability to meet long-term process changes, as well as installed (capital) cost. Ex(mangers should not be selected entirely on a lowest-first-cost basis, which frequently results in future penalties. 

The scale-up of the Scheibel column is still considered proprietary, and therefore the vendor (Glitsch Process Systems Inc.) should be consulted for the final design. From pilot tests in 0.075-m diameter column, industrial columns up to 3 m in diameter and containing 90 actual stages have been provided. 

As with the other extractors, the final design of a Karr column depends on the scale-up from a pilot test. The following procedure is recommended. 

Overall Scale-Up Factor The final design filtration rate is determined by multiplying the bench-scale filtration rate by each of... 

After the final designs are complete it is recommended that the actual touch (actual) and step voltage (actual) are rechecked for both power plant and switchyard areas separately, to ensure that they are within the tolerable limits as determined above. After the ground stations have been finally installed the actual step and touch voltages must be measured to verify the designs. 

Here Acto is the cyclic stress range for failure in Nf cycles under zero mean stress, and Acr m is the same thing for a mean stress of a .) Goodman s Rule is empirical, and does not always work - then tests simulating service conditions must be carried out, and the results used for the final design. But preliminary designs are usually based on this rule. 

Ultimately, the designer must try-out the final design and check the output ripple voltage and the temperature rise of each capacitor. 

Not all reactions take place in a designated reactor. Some occur in a heat exchanger, a distillation column, or a tank. Understand the reaction mechanisms and know where the reactions occur before selecting the final design. 

Crystallization proeess systems design and operation is a eomplex matter requiring extensive data for systematie evaluation. Whilst simplified design methods and heuristies are available, the simple faet remains that the more and better the data input, the better the final design and reliability of the plant. Ideally, amongst the data required are the following ... 

After designing an approximate unit area requirement, it is important to review the final design performance details with a qualified exchanger manufacturer. See Table 10-42. 

Just obtaining these cylinders does not setde the design. The manufacturer must verify that no cylinder interferences exist and that the rod loading in tension and compression is satisfactory. This design detail is handled by the manufacturer. The final design agreement should be by the manufacturer, as he should be responsible for the final quoted performance of the unit. 

BS 6374 Part 5 1985 gives full details of design and fabrication requirements and it is advisable to consult this document as well as the lining contractor prior to arriving at the final design. 

This is the one serious limitation in plastic design problems. Even if the designer did wait for data on one material, chances are the final design might be switched to another plastic or formulation. Thus, as a compromise, data from relatively short-term tests are extrapolated by means of theory to long-term problems. However, when this is done, the limitations inherent in the procedure should be kept in mind. 

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