Annual operating cost

Operating Costs Annual operating costs for the example in Table 22-18 are shown in Table 22-19. For this 0.25 mVs plant, a service factor of 90 percent is assumed. 

TOTAL ANNUAL OPERATING COSTS ASSUMES CONSTANT ELECTRIC RATES OVER LIFE OF PROJECT... 

Figure 4-107. Total annual operating costs for three different FCC power recovery schemes.

Calculate the annual operating costs for the existing process that needs waste treatment, and estimate how these costs would be altered by the introduction of waste-reduction options. Tabulate and compare the process and waste-treatment operating costs for both the existing and proposed waste-management options. If there are any monetary benefits (such as recycled or reused materials or wastes), then these should be subtracted from the total process or waste-treatment costs as appropriate. The expanded cost-analysis scheme discussed in Chapter 8 is appropriate to include at this point in the process. 

TAC = annual operating cost -I- annualized fixed cost. 

Air stripping is used to remove 90% of the toluene (molecular weight = 92) dissolved in a 10 kg/s (159 gpm) wastewater stream. The inlet composition of toluene in the wastewater is 500 ppm. Air (essentially free of toluene) is compressed to 202.6 kPa (2 atm) and bubbled through a stripper which contains sieve trays. In order to avoid fire hazards, the concentration of toluene in the air leaving the stripper is taken as 50% of the lower flammability limit (LFL) of toluene in air. The toluene-laden air exiting the stripper is fed to a condenser which recovers almost all the toluene. A schematic representation of the process is shown in Fig. 2.11. Calculate the annual operating cost and the fixed capital investment for the system. The following physical and economic data are available ... 

But, operating cost is primarily attributed to compression and condensation. Hence, Annual operating cost... 

Since activated carbon lies to the left of the extractant and has a lower c, it will be used to remove the remaining load (0.0003 kg toluene/s, as shown by Fig. 3.19b). The flowrate of activated carbon is 0.015 kg/s. For 8000 operating hours per year, the annual operating cost of the system is 96,700/year. The annualized fixed cost can be calculated after equipment sizing (as shown in Example 2.1). 

In order to synthesize an optimal MEN for intercepting the off-gas condensate, we constnict the pinch diagram as shown in Fig. 4.9. Since the three MSA s lie completely to the left of the rich stream, they are all thermodynamically feasible. Hence, we choose the one with the least cost ( /kg NH3 removed) namely the resin. The annual operating cost for removing ammonia using the resin is ... 

Annual Savings = Annual avoided cost of off-site treatment — Annual operating cost of on-site system... 

A biotreatraent facility that can handle 0.35 kg/s wastewater has a fixed cost of 240,000 and an annual operating cost of 60,000/yr. 

Additional annual operating cost due to increase in flowrate of Sj... 

In-plant interception may be superior to terminal-waste separation. For instance, separating CE from the terminal wastewater stream incurs an annual operating cost of 827,820/year, which is 44% more expensive than the optimal solution. 

Solution Figures 9.6-9.8 illustrate the hot composite stream, the cold composite stream and the pinch diagram, respectively. As can be seen from Fig. 9.8, the two composite streams touch at 310 K on the hot scale (300 K on the cold scale). The minimum heating and cooling utilities are 2,620 and 50 kW, respectively, leading to an annual operating cost of... 

TAG - Annualized fixed cost of modules -f Annualized fixed cost of pump -f Annualized fixed cost of turbine -H Annual operating cost of pump -h Annual operating cost of chemicals — Operating value of turbine... 

Annual operating cost of pretreatment (chemicals) - 0,03/m of feed. 

Annualized fixed cost of piping = 50/m yr Annual operating cost of pump... 

An alternative cost also became apparent from the case studies. If the mean hourly steaming rate in kilograms is multiplied by 2.25, it produces a figure roughly equivalent to the annual operating costs in pounds, excluding the cost of fuel. 

If the fluid has to be pumped through the pipe, the size should be selected to give the least annual operating cost. 

The capital cost of a pipe run increases with diameter, whereas the pumping costs decrease with increasing diameter. The most economic pipe diameter will be the one which gives the lowest annual operating cost. Several authors have published formulae and nomographs for the estimation of the economic pipe diameter, Genereaux (1937), Peters and Timmerhaus (1968) (1991), Nolte (1978) and Capps (1995). Most apply to American practice and costs, but the method used by Peters and Timmerhaus has been modified to take account of UK prices (Anon, 1971). 

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