Case study
Basic info:
End user has 2 pcs 137kw screw air compressor and 1 pc 37kw screw air compressor. Providing air for 24 hours a day
The 2 pcs 137kw compressor will be running in turn. The 37kw compressor is a back up to be opened when sometimes air supply is not enough
All compressor is imported compressor over 10 years ago.

Considering the compressor is old technology and have served for a long time, there could be great potential of energy to be saved. Although user is not willing to purchase any new instruments, the compressor reseller start by providing customer a efficiency test, and try to conduct a compressor
replacement with this customer
Considering there is no money charged and can has a new compressor, user is willing to have a try

1 st step , a pretest is conducted to preview the energy saving potential
Compressor re-seller use a CAE350S from COMATE to run some test on all 3 compressors

       

Manufacturer: Unit air power consumption 0.1312kWh/Nm3
Purchased on: 02/2006 pressure: 0.6Mpa
Rated power: 132.00kW Actual power under test: 147.9kW
Rated capacty: 24.7m3/min Actual capacity under test: 20.6m3/min
Rated power efficiency: 6.80kWh/m3/min Actual overall power efficiency: 7.184kWh/m3/min

 

Real-time monitoring data

compressor real-time monitoring data

 

According to the test result to compare with the new compressor and calculate possible energy saving

Manufacturer: Unit air power consumption 0.1312kWh/Nm3
Purchased on: 05/2016 pressure: 0.6Mpa
Rated power: 132.00kW Actual power under test: 162kW
Rated capacty: 28m3/min Actual capacity under test: 27.5m3/min
Rated power efficiency: 5.80kWh/m3/min Actual overall power efficiency: 5.89kWh/m3/min

According to the test result ,it is easy to calculate potential energy saving
0.1323-0.0981=0.0331
Potential energy saving rate: 0.0331/0.1312*100%= 25.22%

2 nd step , perform a long term monitoring . To make correct offer to customer, compressor reselling installed COMATE flow meter and power meter with on-line monitoring for customer. Not only to understand the air consumption pattern of the user, but also get a more accurate power consumption.

To make correct offer to customer, compressor reselling installed COMATE flow meter and power
N meter with on-line monitoring for customer. Not only to understand the air consumption pattern of
the user, but also get a more accurate power consumption.
According to the test, find out that the long term efficiency of the old machine is even lower. Thus now can make accurate offer to customer

 

3 rd step , Contracting
According to the test result ,it is easy to calculate potential energy saving 0.1410-0.0981=0.0429
Potential energy saving rate: 0.0429/0.1410*100%= 30.43%

According to this number, compressor re-seller sign a compressor replacement contract . A new 132kwh permanent magnet VSD compressor if provided for free. In the next 3 years, according to this unit air electricity consumption , end user charge 70% of the energy saving
Considering there is no cost for the compressor, and payment will only be made if electricity power is saved, customer agreed with the plan

4 th stepShort ROI- Return on Investment
To make correct offer to customer, compressor reselling installed COMATE flow meter and power meter with 0n-line monitoring for customer. Not only to understand the air consumption pattern of
the user, but also get a more accurate power consumption
According to the test, find out that the long term efficiency of the old machine is even lower. Thus now can make accurate offer to customer

Calculation
0.1410-0.1055=0.0355
Actual energy saving rate: 0.0355/0.1410*100%= 25.18%
During 2017 Oct 3 rd to Oct 6 th , total power consumption 12305.304 kwh
0.8 rmb/kwh * 12305.304kwh* 25.18%*70%= 1735.15 rmb
Presuming the compressor works 250 days per year, they can get paid about 144,600RMB in 1 st year
If they sell the compressor, it will only make 170,000~180,000 RMB in total