Condensers costing analysis

Because the performance of a power station is very dependent upon the steam pressure within the condenser, cost analysis is often based on the achievable condenser pressure. In general terms the lower the condenser pressure the lower the unit production cost of electricity. 

TABLE 8.34 Modular Cost Analysis—Coolers and Condensers... 

The best inemals and the optimum values of pressure, vapor velocity, and reboil vapor ratio are those that permit production of heavy water at minimum cost. The initial cost of the plant depends on a number of factors including the total number of towers, the total amount of reboiler and condenser surface, and the total volume of tower internals. The principal operating cost is for power, which is proportional to total loss in availability of steam as it flows through the towers. A complete minimum-cost analysis requires knowledge of the unit cost of all the important cost components and is beyond the scope of this book. Design for minimum volume of tower internals or minimum loss in availability due to tower pressure drop and for minimum cost of these two important contributors to total cost can be carried out without complete unit-cost data and will be discussed. Because the same choice of reboil vapor ratio minimizes the number of towers, their volume, and the loss of availability within them, this reboil vapor ratio is close to that which leads to minimum production cost. An equation for this optimum reboil vapor ratio will now be derived, and expressions will be developed for the total volume of towers and the total loss in availability in towers designed for the optimum ratio. 

Preparation of soil—sediment of water samples for herbicide analysis generally has consisted of solvent extraction of the sample, followed by cleanup of the extract through Uquid—Uquid or column chromatography, and finally, concentration through evaporation (285). This complex but necessary series of procedures is time-consuming and is responsible for the high cost of herbicide analyses. The advent of soUd-phase extraction techniques in which the sample is simultaneously cleaned up and concentrated has condensed these steps and thus gready simplified sample preparation (286). 

Figure 3.6a shows how costs for a new distillation system vary with the reflux ratio. It expresses the capital cost as an annual cost. This can be achieved hy dividing the capital cost by the expected payout period. A discounted cash flow (DCF) analysis is used for estimating this payout period. The capital cost shonld include the costs of auxiliaries (reboiler, condenser, vacuum equipment, pumps, piping in many cases, costs of vent systems, coolant, and heating medium handling equipment are also affected). The operating costs should include reboiler... 

The total-cost method does not in general provide a satisfactory means for making most insulation investment decisions, since an economic return on investment is required by investors and the method does not properly consider this factor. Return on investment is considered by Rubin ( Piping Insulation—Economics and Profits, in Practical Considerations in Piping Analysis, ASME Symposium, vol. 69,1982, pp. 27-A6). The incremental method used in this reference requires that each incremental in of insulation provide the predetermined return on investment. The minimum thickness of installed insulation is used as a base for calculations. The incremental installed capital cost for each additional V2 in of insulation is determined. The energy saved for each increment is then determined. The value of this energy varies directly with the temperature level [e.g., steam at 538°C (1000°E) has a greater value than condensate at 100°C (212°F)]. The final increment selected for use is required either to provide a satisfactory return on investment or to have a suitable payback period. 

Eco-efficiency analysis permits a condensed representation of complex interrelationships, which, as a result, are easier to grasp and to understand. Often, the facts and implications of a case are only vaguely understood. The results of an eco-efficiency analysis allow the visual presentation of these facts and provide a sound basis for discussion. Moreover, the detailed information gained from the investigations enables a more targeted technical, ecological, and economic development of the products and processes. From a user s perspective, the understanding of costs and various environmental aspects of a product is often of a relatively subjective nature. The eco-efficiency analysis illustrates these aspects and makes them more readily accessible for discussion. 

Designers of evaporation systems strive to achieve high heat transfer rates. This can be justified by a cost/benefit analysis. High rates of heat transfer in theory must often be proved in practice. Evaporators designed for high rates of heat transfer are generally more affected by traces of scale or non-condensable gases. 

In this subsection the more accurate CMD method [4-6,8] is described and analyzed in some detail. The method holds great promise for the study of quantum dynamics in condensed matter because systems having nonquadratic many-body potentials can be simulated for relatively long times. The numerical effort in this approach scales with system size as does a classical MD simulation, although the total overall computational cost will always be larger. Here the CMD method is first motivated by further analysis of the effective harmonic theory. This discussion is an abbreviated form of the historical line of development contained in Paper... 

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