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Show Vacuum Mode 35% OEA 2 ~ 25°C c::::l 50°C Figure 4. Recovery 25 C 30% 50 C 20% Capital Cost Effect of Temperature on OEA Energy Requirements, Operating Costs, and Capi tal Costs. Vacuum Mode 25 C 2 flllJ 35% 0 40% Figure 5. Energy 35% OEA 40% OEA Recovery Compression Ratio 5 8 .5 Operating Capital Cost Cost Effect of Concentration on OEA Energy Requirements, Operating Costs, and Capi tal Costs. OEA SYSTEM CAPACITY The modular nature of membrane gas separation systems makes them economical at both small and large system capacities. Economies of scale do come into play, however, primarily in terms of blower and vacuum pump capital costs and improved efficiencies (lower energy requirements) for these devices. Pump capital costs decline continuously on a unit capacity basis as air/OEA flow increases. Pump efficiencies, on the other hand, improve in a step wise manner. 183 The effect of pump capital cost efficiencies on overall membrane OEA system capital costs is shown in Figure 6 over the range of 3 to 20 tons/ day pure available oxygen at a 35% oxygen concentration (9). Curves for both 25 and 50 C operating temperatures are provided. At both temperature levels, a 35% reduction in system costs occurs over this capacity range. For the blowers and vacuum pumps of interest for membrane OEA systems, typical efficiencies are 65% for the blower and 60% for the vacuum pump. These efficiencies remain relatively constant for capacities up to 12 tons/ day pure available oxygen. Beyond this range, more efficient equipment is offered with blower efficiencies increasing to about 75% and vacuum pump efficiencies being as high as 80%. This higher efficiency equipment typically has a higher capital cost than less efficient hardware, but the payback in energy savings should be over a short period of time. These efficiency improvements reduce the power requirement for 35% OEA generation from about 215 Kwh/ton for systems with capacities below about 12 tons/day pure available oxygen to about 200 Kwh/ton for larger hollow fiber membrane systems. >tV ~ 30.000 ...... ....;;;::IIiIlIo.,,;;;:s:..>c-'" QI Q. C 2 ;... 20.000 J----~. ...._ _ III o U ~ 10 .000~------I------+---4--~ Q. A/G Technology Membranes ~ Vacuum Mode of Operation O~ __________ ~ __________ ~ ______ ~ __ --J 3 5 10 20 ~25°C c::::J50°C Figure 6. Plant Capacity. Tons/day Pure Available Oxygen Projected Capital Costs for Production of 35% OEA. The combined effect of reduced pump costs and improved pump efficiencies as a function of plant capacity is shown in the Figure 7 plot of operating costs over the range of 3 to 20 tons/ day pure available oxygen (35% oxygen). A gradual decrease in operating costs is observed as system size increases from 3 to 12 tons/day pure available oxygen, with an overall average reduction of 20% over this entire capacity range. A significant further reduction in operating costs, of about 10%, occurs between 12 and 20 tons/day due primarily to the reduced energy requirements of the vacuum pump. A the 20 ton/day plant level, operating cost projections for |