Total cost approach

Capital, operating, and environmental control costs and life-cycle analysis (Total Systems Approach)... 

Careful consideration has to be given to all aspects of each approach—such as the reliability, the total cost, and the need for equipment and expertise—before making the final decision. The main advantage of measurements is the reliability of the results, the disadvantage being the need for often expensive equipment. 

TCM uses an approach to cost estimating in which each of the elements that contribute to the total cost is estimated individually. These individual estimates are derived from basic principles and the manufacturing process. This reduces the complex problem of cost analysis to a series of simpler estimating problems and brings processing expertise rather than intuition to bear on solving these problems. 

Apart from the actual purchase cost a business pays a supplier for a chemical, there are costs that are usually not considered. Happily there has been considerable development of approaches to Total Cost Assessments or environmental accounting, and the reader is strongly encouraged to seek out more information about how this is done. Application of Total Cost Assessment will provide a strategic view of trends that can directly affect the long-term viability of a process and is well worth the effort. 

Jodicke, G., Fischer, U., Hungerbtihler, K., 2001. Wastewater reuse a new approach to screen for designs with minimal total costs. Comp. Chem. Eng., 25 203-215... 

High Response Building/component has lost structural integrity and may collapse due to environmental conditions (i.e. wind, snow, rain). Total cost of repairs approach replacement cost of building. 

Hydrogen from surplus wind electricity as vehicle fuel is fairly expensive. According to the calculations and assumptions of Wietschel et al. (2006) the price is 9.5 ct/kWh hydrogen. This is calculated with the assumptions shown in Table 16.2, compression costs of 1.5 ct/kWh and electricity costs from wind power of 4 ct/kWh. However, the 4 ct/kWh, which has a major influence on the total cost (see Fig. 16.10) is debatable, because we are talking about surplus wind and the question is what other alternatives for use exist. An opportunity cost approach may be useful, e.g., taking into account the gains of other uses, like electricity production via the compressed air option, which will lead to a much lower price for the electricity. 

Two advantages of this approach would be the minimized capital and operating costs, along with minimal space requirements. The best process (for iron removal) would probably be chemical precipitation with lime through a rapid mix, flocculation, and DAF step. DAF size requirements would be in the range of a 300- to 350-ft2 unit. Total costs for operation and maintenance of the preliminary treatment facility using an interest rate of 10% over 10 years are estimated at 0.44/1000 gal. A summary of the capital and operating cost estimates is presented in Table 8.2. 

To get some idea of the prices to be expected for compounds produced with these approaches, we have estimated the total cost of producing 10,000 tons per annum of 1-octanol from w-octane, based on data collected for this conversion by P. oleovorans, during growth in a two-liquid-phase system containing 15% (v/v) hexadecane as a carrier phase. n-Octane is dissolved in the carrier phase to a concentration of 5-10% (v/v), converted by the P. oleovorans cells in the aqueous phase, and the product 1 -octanol dissolves in the hexadecane phase once more. Downstream processing consists of a phase separation, followed by two distillation steps. In the first step, the C8 alkane/alkanol are separated from the hexadecane, which is recycled into the bioreactor. In the second step, the w-octane is distilled off the n-octanol the octane is recycled to the bioreactor, and the octanol is collected as the desired product. This approach leads to a very clean product stream of >98% pure 1-octanol. ... 

Quantification of impurities can be conducted through a number of different methods. The two most often used are the mass balance approach and the standardization approach. The preferred quantification method is standardization, due to its greater accuracy. In this approach, the analyte sample is compared to a sample having a known quantity of a known standard substance. This standard can be either internal or external, or direct or indirect. The mass balance approach adds all of the peaks found in a chromatogram and calculates a percentage of total detected area. This is a much quicker and less costly approach than the standardization approach, but is susceptible to systemic bias, on account of which its accuracy suffers. 

Estimated Total Costs of Direct vs Phased Approaches to Sampling and Analysis... 

The importance of stabilizers for SCF polymerization was briefly outlined in Section 9.1.4. The drawback with existing stabilizers, however, is that most of them are based on fluorocarbons or siloxanes, which are high-cost chemicals. Cheaper polymeric stabilizers are usually only soluble in SCCO2 at pressures too high to make viable their widespread use. Very recently, Beckman and co-workers reported [68] a totally new approach to the problem polymers were prepared by co-polymerization of propene oxide and SCCO2. These polymers are not only much cheaper than fluorinated polymers but are more soluble than these materials in SCCO2. The polyether polymers are likely to have widespread applicability, not only as building blocks for stabilizers for SCF polymerization, but also as the basis of... 

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