Tray capital cost

The economic objective function to be minimized is the cost, which combines the capital costs associated with building the column and the utility costs associated with operating the column. The form for the capital cost of the column depends upon the vapor boilup, the number of trays, and the column diameter... 

Figure 2.62 gives results over a range of reactor volumes. The reactor volume that minimizes TAC ( 1,117,000 per year) is 20 m3, giving a recycle flowrate D of 0.1241 kmol/s. Figure 2.63 gives the values of variables and parameters for the 10 m3 reactor process. The reactor concentration is Ca = 2.099 kmol/m3 (z = 0.262 mole fraction A). The column has 16 trays. The distillate composition is 0.3304 mole fraction A. Energy cost is 427,400 per year. The capital cost of the column is 123,000. The capital cost of the... 

Static extraction columns Spray column Baffle column Packed column (random and structured packing) Sieve tray column Deliver low to medium mass-transfer efficiency, simple construction (no internal moving parts), low capital cost, low operating and maintenance costs, best suited to systems with low to moderate interfacial tension, can handle high production rates Petrochemical Chemical Food... 

The economic objective function is formulated on the basis of (1) capital costs, (2) return on investment, and (3) operating costs. The objective function is formulated as an expression of the desire to minimize the total costs per mole of the most valuable product. The capital costs consist of the installed costs of the following items the pressure vessel or shell of the distillation column, the trays, the condenser, and the reboiler. 

Unlike the other systems, this system employs removable cassettes, which can be used in the bucky tray of a standard mammography unit While there are capital cost savings to this approach, it does require that phosphor plates be manually transported to the reader for processing. Because there are multiple detector plates, flat-fidd correction is normally not performed for the plates, but only for the plate reader. In principle, correction for nonuniformity of the individual plates could be done, but this would require precise registration within the reader and would be time-consuming. 

Chapter 17 and given by Eq. (17.10). This requires estimates of the total capital cost and the annual operating cost of the columns, trays, condensers, reboilers, and reflux accumulators. To estimate these costs, equipment sizes must be determined. In this example, calculations of the height and diameter are jJlustrated for one cdiumn in one of the segnences. 

Figure 12.1 gives the optimum economic design of the divided-wall column developed by Ling and Luyben using four RadFrac vessels. The optimum is based on minimizing total annual cost (TAG), which includes both energy and capital costs. The number of trays in... 

The Marshall and Stevens equipment cost index or the Chemical Engineering magazine plant cost index are usually used. Current values are given in each issue of Chemical Engineering magazine. Values for several years cost indices are tabulated in Table 11-1. The total uninstalled equipment cost will be the sum of condenser, reboiler, tower casing, and tray costs. The total capital cost is then found from Eq. (11-1). The capital cost per year equals the capital cost times the depreciation rate. Note that cost estimates can easily vary by up to 35%. 

The individual equipment costs depend on the condenser area, reboiler area, tower size, and tray diameter. Some of the variable effects on the capital costs are conplex. These are outlined in Table 11-5. The net result of increasing L/D is shown in Figure 11-4 capital cost goes through a minimum. 

Sieve trays have wide applications due to lower capital cost and less maintenance required. However, valve trays can promote froth regime and thus achieve distillation efficiency up to 20% higher than sieve trays (Anderdson et ah, 1976). Furthermore, valve trays can achieve 3 1 turndown compared to sieve trays in 2 1. However, the disadvantages of valve trays are higher pressure drop and cost. 

A decrease in A i is always connected with an increase of necessary tray numbers and total capital costs. Therefore, it is justified only in the case of massive energy expenditures. 

Operation conditions into the columns was calculated by Underwood, Fenske equations. However, any other set of equations including rigorous tray by tray calculations could be implemented. The conceptual procedure continue being the same and only the numerical performance would be affected. As an objective the total annualized cost (operating cost, annualized capital cost of columns and heat exchangers) is considered. Procedure proposed by Douglas (1988) has been implemented. 

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