Cost Saving Example 3

$3,393 Annual Air Savings On A Tank Blowoff Operation

A company that refurbishes large tanks runs the tanks through an oven on a conveyor line to burn off the old paint. Only one tank at a time can be processed and each tank takes 6 minutes to complete the journey. Super Air Knives are used for blowoff at the exit of the oven.

However, the tank travels through the oven for 5 minutes before it reaches the knives for blowoff. At 80 PSIG (5.5 BAR), the four Super Air Knives consume 348 SCFM (9,854 SLPM). Once the tanks have been blown off, the conveyor stops, the air is shut off and the new tank is loaded at the other end. The operation runs 30 tanks per day, 5 days per week.
The timer was set to “on/off delay”. The sensor was mounted at the oven exit (1 minute away from the blowoff station). When the sensor detected a tank, the timer turned the air on for one minute, just as the next tank reached the blowoff station

Old Method

It takes 6 minutes to complete the process.
6 minutes x 348 SCF = 2,088 SCFM (59,090 SLPM)
2,088 SCFM x 30 tanks = 62,640 SCFM (1,772,712 SLPM)

EFC Solution

The EFC was installed to shut off the compressed air for the 5 minutes where no tank was present (one minute of air on).
1 minute X 348 SCFM = 348 SCF x 30 tanks = 10,440 SCF (295,452 SL)

Cost Difference

Most large plants know their air cost. If the actual cost is unknown, $0.25 per 1,000 SCF (28,329 SL) is reasonable.

Before the EFC installation:
62,640 SCFM/1,000 = 62.64 x $0.25 = $15.66 air cost per day.

With the EFC installed:
10,440 SCFM/1,000 = 10.44 x $0.25 = $2.61 air cost per day
$15.66 (old air cost) – $2.61 (new air cost)
= $13.05 savings per day x 5 days per week
= $65.25 savings per week x 52 weeks per year
= $3,393 savings per year