1. Use venturi amplifier air nozzle instead of compressed air
Recommended Action
It is recommended to use an alternate method for supplying compressed air using venturi air
amplifier nozzles instead of spray nozzle. These nozzles use a small amount of compressed air
and produce high energy and high velocity air flow as output. Such nozzles have produced
significant savings for large manufacturing companies by reducing their compressed air usage.
Energy Cost Savings
Case 1:
For blow off nozzles:
We know, nozzle hole size = 3/32in., Pressure = 90 psi and total of 3 nozzles
From table 1, we calculate CFM based on the given information:
CFM v/s PSI For Nozzles
CFM Free Air Flow @ Nozzle Diameter (inch)
PSI 1/64 1/32 3/64 1/16 3/32 1/8 3/16 1/4
1 0.03 0.11 0.2 0.4 1 1.7 3.9 6.8
5 0.03 0.24 0.5 1 2.2 3.9 8.7 15.4
10 0.06 0.34 0.8 1.4 3.1 5.4 12.3 21.8
15 0.1 0.042 0.9 1.6 3.7 6.6 15 26.7
20 0.12 0.48 1.1 1.9 4.2 7.7 17.1 30.8
25 0.13 0.54 1.2 2.2 4.7 8.6 19.4 34.5
30 0.16 0.63 1.4 2.5 5.6 10 22.5 40
40 0.19 0.77 1.7 3.1 6.8 12.3 27.5 49.1
50 0.22 0.91 2 3.6 8.2 14.5 32.8 58.2
60 0.26 1.05 2.3 4.2 9.4 16.8 37.5 67
70 0.29 1.19 2.7 4.8 10.7 19 43 76
80 0.33 1.33 3 5.3 11.9 21.2 47.5 85
90 0.36 1.47 3.3 5.9 13.1 23.5 52.5 94
100 0.4 1.61 3.7 6.4 14.5 25.8 58.3 103
110 0.43 1.76 3.9 7 15.7 28 63 112
120 0.47 1.9 4.3 7.6 17 30.2 68 121
130 0.5 2.04 4.6 8.1 18.2 32.4 73 130
140 0.54 2.17 4.9 8.7 19.5 34.5 78 138
2. 150 0.57 2.33 5.2 9.2 20.7 36.7 83 147
175 0.66 2.65 5.9 10.6 23.8 42.1 85 169
200 0.76 3.07 6.9 12.2 27.5 48.7 110 195
Table 1 (see reference)
Total no. of hours each nozzle is used per year = 6,840 hrs*0.5 = 3,420 hrs (Blow off is done
for 0.5 sec at every other second)
Current annual consumption in 1 nozzle = 13.1 cfm * 0.18 kW/cfm * 2,280 hours = 5,376.24
kWh/year (13.1 cfm from the table 1)
Annual consumption for 3 nozzles = 3* 5,376.24 kWh/year = 16,128.72 kWh/year
It is estimated that a typical venturi nozzle saves 60% of compressed air as it draws in
surrounding air. Therefore, annual usage savings for one spray nozzle with a venturi retrofit =
5,376.24 kWh/year * 0.60 = 3,225.74 kWh/year
Annual electric usage savings for 3 nozzles = 3 * 3,225.74 = 9,677.23 kWh/year
Annual electricity cost savings = 9,677.23 kWh/year * $0.043/ kWh = $416.12/year
Case 2:
For blow off nozzles used:
We know, nozzle hole size = 1/8in., Pressure = 90 psi and total of 50 nozzles
From table 1, we calculate CFM based on the given information:
Total no. of hours each nozzle is used per year = 3*6*3*285 days = 15,390 mins = 256.5 hrs
(Blow off is done for 3 minutes per use, 6 times per shift for a total of 3 shifts/day)
Current annual consumption in 1 nozzle = 23.5 cfm * 0.18 kW/cfm * 256.5 hours = 1,084.99
kWh/year (23.5 cfm from the table 1)
Annual consumption for 50 nozzles = 50*1,084.99 kWh/year = 54,249.75 kWh/year
It is estimated that a typical venturi nozzle saves 60% of compressed air as it draws in
surrounding air. Therefore, annual usage savings for one spray nozzle with a venturi retrofit =
1,084.99 kWh/year * 0.60 = 650.99 kWh/year
Annual electric usage savings for 50 nozzles = 50 * 650.99 = 32,549.70 kWh/year
Annual electricity cost savings = 32,549.70 kWh/year * $0.043/ kWh = $1,399.63/year
3. Total annual electric usage savings = 9,677.23 kWh/year + 32,549.70 kWh/year = 42,226.93
kWh/year
Total annual electricity cost savings = $416.12/year + $1,399.63/year = $1,815.75/year
Emissions Reduction Analysis
At these usage savings (42,226.93 kWh/year) the annual reduction in carbon dioxide is:
77,698 pounds (pounds of CO2 per kWh = 1.84)
Implementation Cost and Payback
Cost of 1 venturi nozzle = $20
Cost of 53 nozzles = 53 * $20 = $1,060
Estimating 53 hrs time to retrofit 53 nozzles at a unit labor cost of $40/hour, the total labor
cost is = 53 hr * $40/hr = $2,120
Implementation cost = $1,060 + $2,120 = $3,180
Payback period = $3,180/$1,815.75= 1.75 years
References:
http://azglassclasses.com/Reference/CFM-PSI.htm