Application case of the air-bearing centrifugal blower in the cement industry
Saving energy and reducing consumption is an important part of achieving high-quality development in the cement industry. Roots blowers and conventional centrifugal blowers are currently widely used in cement plants, but they have the drawbacks of high energy consumption, high noise, and frequent and costly maintenance. The air-bearing centrifugal blower solves these problems effectively. A blower energy-saving retrofit at a cement plant is analyzed below:
3.1 Operating condition of the original Roots blower
The original Roots blower had been in service for many years; its efficiency was gradually declining and its failure rate rising. At an on-site operating pressure of 31 kPa, the Roots blower actually drew 142 kW and its noise level was 110 dB. When the user increased production and needed the pressure raised to 35 kPa, the original Roots blower could not meet the requirement.
Roots blower nameplate data (Table 2)
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Application
Blower type
Nameplate flow
m³/min
Nameplate pressure
kPa
Nameplate power
kW
| | | |
Kiln-head primary air blower
Roots blower
169
29.4
132
3.2 Retrofit solution
Subject to meeting the maximum operating pressure requirement, a 132 kW air-bearing centrifugal blower was selected to replace the original Roots blower, which can be kept as a standby unit.
Air-bearing centrifugal blower nameplate data (Table 3)
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Application
Blower type
Nameplate flow
m³/min
Nameplate pressure
kPa
Nameplate power
kW
| | | |
Kiln-head primary air blower
Air-bearing centrifugal blower
175
40
132
3.3 Results of the retrofit
Table 4 compares the blower data before and after the retrofit.
Comparison of blower data before and after the retrofit (Table 4)
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No.
Blower type
Operating pressure
kPa
Operating flow
m³/min
Operating power
kW
Specific energy consumption
kWh/m³
Electricity saving
%
| | | | | |
1
Roots blower
31
169
142
0.014
28.5
| | | | |
2
Air-bearing centrifugal blower
31
169
105
0.01
| | | | |
|
1
Roots blower
35
169
Cannot meet the requirement
| | | | | |
2
Air-bearing centrifugal blower
35
169
123
0.012
(1) Economic benefits
1) Electricity cost: compared with the original Roots blower, the air-bearing centrifugal blower saves 37 kW of power every hour, an electricity saving of 28.5%. This amounts to 266400 kWh a year (7200 h/a) and a total saving of RMB 146520 (at RMB 0.55/kWh).
2) Maintenance cost: the original Roots blower required scheduled overhauls and replacement of lubricating oil and mechanical bearings; including labor, the average annual maintenance cost was RMB 2000. Maintenance of the air-bearing centrifugal blower consists only of cleaning or replacing the filter mat, and costs no more than RMB 700 a year.
(2) Social benefits: on-site noise fell from 110 dB to 75 dB, greatly improving the working environment, and noise across the plant site was reduced as well.
5 Conclusions
(1) The air-bearing centrifugal blower is energy-saving and environmentally friendly, with low noise, low vibration, no lubricating oil and no routine maintenance. The equipment is also compact, highly automated and easy to install and operate, which makes it very well suited to cement plants and to energy-saving retrofits.
(2) The purchase cost of an air-bearing centrifugal blower is higher than that of a conventional blower, but the annual energy saving is more than enough to offset its amortization: the energy saved alone repays the investment in the equipment within 2 years. The blower has broad prospects for application in the cement industry.