Process cost comparison

With estimates of variable cost and capital requirement available the process cost table could be built up if an estimate of the labour requirement (process and maintenance and analytical) could be made. These items form part of the plant fixed costs and studies of a number of petrochemical processes show that an annual charge equivalent to 3-6% of the plant capital would be a suitable figure to include in a preliminary estimate for total plant fixed costs. For smaller batch operations a range of 8-12% of plant capital would be a reasonable figure to apply. A comprehensive cost table (Table 6.12) can then be built up. 

Basis Costs at January 1989 prices. Capital at a Process Engineering index 

Operating costs per tonne of maleic 33 million 36 million 

However, as previously stated, the cost table provides only an instant picture of the process cost and profitability. As the stage is approached when capital will have to be allocated for pilot-plant studies there is a need for a view of the prospects for a project over its expected life. This requires the use of NPV and DCF methods of evaluation which in turn necessitate estimates of product sales, raw material prices and product selling prices over the life of the project. 

In order to obtain the necessary information an estimate is required of the amount of the product which the market can take up and also an estimate of the share of the market which the Company carrying out the survey can expect to obtain. This will enable the size of the proposed new product unit to be fixed or set at a range of sizes to be evaluated in the NPV/DCF calculations. 

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Table 6.12 Process cost comparison for the production of maleic (cis-butenedioic) anhydride by benzene and butane oxidation...

Comparison to the Raschig Process. The economics of this peroxide process in comparison to the Raschig or hypochlorite—ketazine processes depend on the relative costs of chlorine, caustic, and hydrogen peroxide. An inexpensive source of peroxide would make this process attractive. Its energy consumption could be somewhat less, because the ketazine in the peroxide process is recovered by decantation rather than by distillation as in the hypcochlorite process. A big advantage of the peroxide process is the elimination of sodium chloride as a by-product this is important where salt discharge is an environmental concern. In addition to Elf Atochem, Mitsubishi Gas (Japan) uses a peroxide process. 

Economic Aspects. Several pubUcations probe the various areas of electroorganic process cost. CeUs (90), overaU process costs (41,91—93), economic optimization (94,95), and a comparison between the chemical and electrochemical methods (91,96) are aU discussed. 

Figure 2.2 (a) Tolerance versus production costs of various processes (b) comparison of cost-tolerance models (Dong, 1993)... 

As the materials used in drilling processes are produced from depletable mineral resources, there is a continuous upward trend of cost with time. The field engineer must make a detailed cost comparison of materials available within the target cost of the project. The final choice may be a tradeoff between cost and performance. This is because the choice may narrow down to two or more materials with different initial costs and different expected service lives. Transportation costs of selected materials must also be included in the final cost. 

Due to these advantages the overall production costs for the immobilised continuous process were found to be 40% lower than that of the batch process. In Figure A8.6 a comparison is given between the batch process costs and the continuous production costs. 

Both techniques have their advantages and their limitations with respect to process time, process temperatures, and process costs. However, the crucial question is How much does crosslinking contribute to the desired properties of the material The performance of the final product is, of course, the major issue. A lot of information on crosslinked polymers is available in the literature. There have been several attempts in the past [1-7], and also more recently [8-10], to sort out this accumulation of scientific data. Yet, it is neither simple nor particularly rewarding to undertake such a venture due to the multitude of variables which make direct comparisons difficult, and to the incidence of apparent contradictions. 

All DAFs are similar to each other in terms of theory, principles, design, operation, and secondary flotation performance. The authors select the circular DAF process equipment manufactured by KEC for the purpose of feasibility studies. The users should contact more than one major DAF and DAFF manufacturers for appropriate pilot plant demonstrations and cost comparisons. Rectangular DAF and DAFF clarifiers are as good as circular DAF and DAFF clarifiers. 

Brief economic comparison of some processing costs... 

Fig. 3. Cost comparison of different routes to 1,3-propanediol [74], Production costs for the chemical processes and glucose route are based on estimations from ChemSystems. Estimations for the glycerol processes are based on US market prices of raw materials in 1998 and a production scale of 65,000 t/a. The energy costs for the glucose process are assumed to be the same as the fed-batch glycerol process...

TABLE 1 Cost Comparison of ECOCHOICE to Other Advanced Oxidation Processes (AOPs)... 

In the first case, comparison with conventional low pressure solvent plants are not included, because of differences in the legal situation within diverse countries, which can result in higher or lower investment and processing costs due to regulations in regard to environmental protection, allowed remaining solvent residue levels, usage of diverse solvents and safety precautions. 

Figure 8.1-4. Cost comparison between different isobaric processes, and the non-isobaric process.

Figure 8.1-5. Annual production cost comparison between isobaric processes with the non-isobaric one, for a plant size of 3x4 m3.

Whereas the criteria (i) enantioselectivity, (ii) amount of product obtained per amount of catalyst used, and (iv) substrate specificity are of a quantitative nature, the point (iii) availability (though not cost) of a catalyst is only a semi-quantita-tive criterion, and (v) comparison of a method with alternative strategies is even redundant, as the process of comparison of options and their resulting evaluation and ranking are merely different parts of the decision-making process, and are not undertaken in parallel with performance measurements along dimensions of merit. 

Reliable capital and operating cost comparisons between pervaporation and distillation are not available. Pervaporation is less capital and energy intensive than distillation or adsorption processes for small plants treating less than 5000 L/h of feed solution. However, because of the modular nature of the process, the costs of pervaporation are not as sensitive to economies of scale as are the costs of distillation and adsorption processes. Distillation costs, on the other hand, scale at a rate proportional to 0.6-0.7 times the power consumption. Thus, distillation remains the most economical process for large plants. The cross-over point at which distillation becomes preferable to pervaporation from an energy and economic point of view currently appears to be 5000 L/h processing capacity. Bergdorf has made an analysis of the comparative costs of pervaporation, distillation and other processes [43],... 

Figure 11 Memstill technology of seawater desalination developed at the TNO institute (a) principle of the process (b) cost comparison with other desalination techniques. (From Ref. 226.)...

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