Cement Plant GeneralTechnologies & Measures
|Technology or Measure||Energy Savings Potential||CO2 Emission Reduction Potential Based on Literature||Costs||Development Status|
Reduction of up to 5 kWh/t-clinker through various preventative maintenance and process control measures was reported Typical savings are around 3 kWh/t clinker.
Start-up and implementation costs of preventive maintenance tend to be very low, often resulting in payback times of less than one year.
|High efficiency motors & drives|
Power savings may vary considerably between different plants, ranging from 3 to 8%.
By retrofitting 13 motors with high efficiency ones a cement plant in Davenport, California, has saved 2.1 MWh of electricity annually.
For a 5000 tons per day plant, it is estimated that replacing all motors in plant fan systems with high-efficiency motors costs US $0.22 per annual ton of cement capacity.
The cement plant in Davenport, California, has reduced its annual energy and maintenance costs by US $168 000 and US $30 000 annually. The implementation costs amounted to US $ 134 000 (including a rebate from the local utility company) giving a payback time of around 8 months.
|Variable Speed Drives|
The savings VSDs provide can vary between 7 to 60% depending on the flow pattern and loads. (ECRA, 2009).
Other sources estimate that the potential savings are 15% for 44% of the installed power, or roughly equivalent to 8 kWh/t cement (LBNL, 2008).
In a Canadian plant, replacing the kiln ID fans with VSDs saved 6 kWh/t.
The specific costs depend strongly on the size of the system. For systems over 300 kW the costs are estimated to be 70 €/kW (75 US$/kW) or less and for the range of 30-300 kW at 115-130 €/kW (120-140 US$/kW). Based on these, the specific costs for a modern cement plant was estimated to be roughly US $0.9 to 1.0/annual ton cement capacity.
VSDs for clinker cooler fans have a low payback, even when energy savings are the only reason for installing.
|Compressed air system maintenance|
Through more frequent filter chaning, a 2% reduction of annual energy consumption in compressed air systems can be realized.
The payback for filter cleaning and maintaining drain traps is usually under 2 years.
|Reduced Leaks in Compressed Air Systems|
A 20% reduction of annual energy consumption in compressed air systems is projected for fixing leaks.
Sophisticated controls can provide up to 12% energy savings annually.
Changing the compressor control from on/zero/off to a variable speed control can save up to 8% per year.
Typical payback for start/stop controls is 1 to 2 years.
|Proper Selection of Compressed Air Dryer|
A rule of thumb is that desiccant dryers consume 7 to 14% of the total energy of the compressor, whereas refrigerated dryers consume 1 to 2% as much energy as the compressor
|Reducing Compressor Inlet Air Temperature|
As a rule of thumb, each 3 °C will save 1% compressor energy use.
Importing fresh air can have paybacks of 2 to 5 years.
|Proper Sizing of Pipe Diamaters|
Increasing pipe diameter typically reduces annual energy consumption by 3%.
|Lighting Controls||Not available||Not available||Payback of lighting control systems is generally less than 2 years.||Commercial|
|Replace T-12 Tubes by T-8 Tubes||Efficacy of lighting can be doubled.||Not available||Not available||Commercial|
|Replacing Mercury Lights||Metal halide lamps can replace mercury or fluorescent lamps with an energy savings of 50%. High pressure sodium lamps offer energy savings of 50 to 60% compared to mercury lamps.||Not available||Not available||Commercial|
|Replacing Metal Halide HID||High-intensity fluorescent systems yield 50% electricity savings over standard metal halide HID.||Commercial|
|Replace Magnetic Ballasts with Electronic Ballasts||Electronic ballasts save 12-25 percent more power as compared to magnetic ballasts.||Not available||Not available||Commercial|