Hi Friends,
All of us are well aware that aluminium smelting is power intesive process which requires about 13.5 MWh to 15 MWh per tonne of aluminium metal production which accounts for about 45% to 55% of total production cost of aluminium. Hence, even marginal reduction in cost of electrical power will contribute substantial in reducing the production cost of aluminium.
Presently, almost all the Captive power plant (CPP) of the World supplying electrical power to Aluminium smelters are Subcritical thermal power plants having overall thermal efficiency ranging from 28% to 38%. However, Super critical thermal power plants operative with 250 bar to 300 bar steam pressure and 540 deg.C to 615 deg.C steam temperature will have the overall thermal efficiency in between 42 to 44%. As we know, the thermal power plants operative with superheated steam on or above 220.6 bar (3200 psi or 22.06 Mpa) are the Super critical power plants which requires higher grade material for boiler tubes and turbine blades as well. Though the capital investment for Super critical power plants may be about 5 to 10% higher than the convensional Subcritical power plants. But the improved thermal efficiency of Super critical thermal power plant will result in substantial reduction in specific cost of electrical power ultimately reducing the production cost of aluminium thereby profitability of Aluminium smelters. Also, the improvement in power plant efficiency will result in lower generation of SPM, CO2, SOX and NOX emission per unit of electrical power because of lower coal consumption. With regard to reliability, the availability of Super critical power plant is high at around 98% excuding planned stoppages which meets the continuous power supply requirement for smelters.
It clearly reveals that the Super critical thermal power plant will be best suited as CPP for future Aluminium smelters aiming to achieve the overall thermal efficiency of CPP close to 50%.
I hope, the experts in the field will agree to my views. Kindly put your views / remarks for value addition on the subject.
Regards.
Kunwar Rajendra
Dear Mr. Rajendra,
ReplyDelete1) Based on my understanding, in India supercritical technology is being executed for plants with module sizes of 660 and 800 MW. Only plants of these sizes can operate with 250-300 bar steam pressure and 540-615 degrees C temperature
2) Globally, supercritical technology has been proven to work with 460 MW plants
FYI - http://www.fwc.com/publications/tech_papers/files/TP_CFB_04_02.pdf
3) As uninterrupted power supply is required in the aluminium smelting process, most of the plants that are coming up are setting up smaller modules (150-300 MW), which are all based on sub-critical technology
Ass the unit size is unlikely to exceed 300 MW, it is highly doubtful that supercritical technology will be adopted in the aluminium industry, although it is more efficient.
I hope to hear your thoughts on the same
Kind Regards,
Zahoor
Dear Mr. Zahoor,
ReplyDeleteI appreciate your views and remarks.
Regards.
Rajendra Kunwar