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This paper now examines the costs, capital and operating, of the various competitive energy recovery devices (ERDs), as theywould be encountered over a warranty period, assumed here to be 5 years. The Francis turbine hasbeen excluded because of its significantly poorer efficiency relative to the other devices. Also, inthe last 3 years, ERD manufacturers have made significant improvements in their units and thispaper updates the power consumption of all devices based on information from current internationaltenders.Basic case study conditions for this paper are 800-psi (55 bar) to 900-psig (62 bar) single stage,operating applied pressure over 5 years at an availability of 95%, 36,000 mg/L feed waterconcentration and 45% recovery. Case differences include temperature variances from 18 C to 25C with plant capacities at 2 MGD (7,570 msup3/sup/d), 12 MGD (45,420 msup3/sup/d and 35 MGD (132,475msup3/sup/d). The ageing factor of the spiral wound cartridges, required to establish the pressure increasewith time, is assumed at 7%/yr. For simplicity and symbolism of every device's performance, justone membrane manufacturer's computer projection program is used. The cases considered alsohave varying power costs of 4/kWh, 10/kWh and 25/kWh. High-pressure and booster pumpsand motor types, VFD usage, train sizes, etc. are chosen via "industry standards" to be compatiblewith the capacities under study. Train sizes of 0.5 MGD (1,893 msup3/sup/d) for the low capacity system, 2MGD (7,570 msup3/sup/d) for the middle capacity system and 3.5 MGD (13,248 msup3/sup/d) largest system willbe used. Membrane projections assume 6 cartridges per pressure vessel and will base pressures, etc.,on initial startup and five year projections for simplicity. Includes tables, figures.

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Edition: Vol. - No. Published: 03/01/2005 Number of Pages: 11File Size: 1 file , 680 KB