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Cost Comparison
Chemical Technology vs. AquaDyn Water Management
Based on Typical Operating Costs of a 500 ton Chiller and Tower
| Various Costs |
Chemical Technology
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AquaDyn Water Management
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Chemicals
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$ 5,000 1
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$ 0 2
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| Compressor Electricity (4¢) |
$115,200 3
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$ 96,000 4
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| Water and Sewage |
$ 20,520 5
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$ 16,416 6
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| Tower/Condenser Maint. |
$ 5,500 7
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$ 0 8
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| Tower Electricity (4¢) |
$ 8,076 9
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$ 5,854 10
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| Totals |
$154,296
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$ 118,270
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| Avg. Operating Cost per Ton |
$ 308.59/ Ton
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$ 236.54/ Ton
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Chemical Costs
1. Chemical Treatment.
Average Cost: $5,000
Chemicals cost an average of $10/ton/yr. in systems operating 6,000 hours per year. Chemicals used include bio-cide, algaecide, corrosion and scale inhibitors, and scale dispersant. This estimate includes annual costs of field monitoring and chemicals needed to recharge system after periodic bleeding to remove mineral concentrations.
2. AquaDyn Treatment.
Cost: 0
Compressor Electricity ($.04) Costs
3. Chemical Treatment.
Average Cost: $115,200
Notes: The U.S. Department of Energy estimates that a 1/8" buildup of scale on a heat exchange surface will reduce the efficiency by 25%. Cooling towers and condenser sections using chemical treatment of the cooling water inevitably generate scale in the sump and the piping of the chiller and/or heat exchangers. 500 ton X 0.8KWH/ton (conversion rate of electrical to mechanical energy) X 6,000 hrs X $0.04/KWH X 1 (load factor) = $96,000/yr X 120% (20% loss to scale or film) =$115,200.
4. AquaDyn Treatment Costs
Cost: $96,000.00
Notes: The AquaDyn physics technology will remove existing scale from the cooling tower sump and the piping. To be conservative, a 10% figure is used for efficiency improvement even though, as noted above, DOE estimates that 1/8" scale on condenser tubes can reduce operating efficiency by 25%. Chiller electricity savings and costs are calculated as $115,200 / 80% = 96.000.
Water and Sewage Costs
5. Chemical Treatment.
Average Cost:$20,520 (based on estimate of $2.40/1,000 gal)
Evaporation: 0.038gpm/ton X 500ton X 60min X 6,000hrs = 6,840,000gal/yr.
Water/sewage costs = $2.40/1,000gal \evaporation costs = $16,416
Blowdown: 10.0095 gpm/ton X 500 ton X 60 min. X 6,000 hrs = 1,710,000 gal/yr.
Water/sewage costs = $2.40/1,000 gal \Blowdown costs = $4,104
6. AquaDyn Treatment.
Cost: $16,416.
Notes: The AquaDyn Water Management System will eliminate Blowdown that results in water and sewage savings of $4,104.
Tower/Condenser Maintenance Costs
7. Chemical Treatment.
Average Cost: $5,500 per year
Notes Tower maintenance is estimated to require an annual effort of 76 hours to scrape, clean and recoat. The estimated time to disassemble and reassemble the tower diffusion plates and the condenser bells is 24 hours. At a labor rate of $55/hr. this maintenance costs $5,500 per year. No estimates are made for periodic flushing of the entire piping system with muriatic acid and then a neutralizer to reduce scale buildup.
8. AquaDyn Treatment.
Cost: 0.
Notes: All maintenance, calibration and water testing associated with the operation of the AquaDyn Water Management System is provided by AquaDyn through its water management contract.
Tower Electricity
9. Chemical Treatment.
Average Cost: $8,076 per year
Notes: Electrical costs associated with the operation of the cooling tower are based on
a 15 hp motor to drive the pump and a 30 hp motor to drive the cooling fan. These
assumptions yield a cost of: 45hp X 0.748/hp X 6,000hrs X $0.04/kwh = $8,076.
10. AquaDyn Treatment.
Cost: $5,854 per year
* These formulas are derived from Perry's Chemical Engineers' Handbook, 6th Edition {50th anniversary edition}
pp 12-17.
Notes: The AquaDyn system is expected to reduce operating costs for the cooling
tower by slightly less than 34 percent. Combining 66 percent of the cost of electricity for
the existing system and adding the cost of a two horsepower motor to operate the
AquaDyn system, obtain this estimate. The calculations are: $8,076 X 66% = $5,330/yr
plus operating costs for the AquaDyn system (2hp X 0.748/hp X 8,760hrs/yr X
$.040/KWH = $524.00). Total costs are, therefore: $5,330 + $524 = $5,854.
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