22 Jan,2016 UTC+8 Views:
The impact of oxyfuel combustion applied to a rotary kiln producing lime. The interests are product quality, carbon dioxide emissions, energy efficiency, stack gas composition, and possible benefits related to carbon dioxide capture. Oxyfuel combustion is combustion of a fuel with pure oxygen or a mixture of oxygen, water, and carbon dioxide in contrast to conventional combustion which is done with air. This oxyfuel technology study involves combustion with pure oxygen and flue gas recirculation.
Lime is produced by calcination of limestone, containing a high concentration of calcium carbonate; Limestone is an abundant natural raw material. Lime is used for waste neutralization or flue gas desulphurization, or used for formation of metallurgical slags or for production of paper pigments.
Conventional lime production in rotary kilns, Lime is produced by calcination of calcium carbonates in industrial kilns. The mineral calcite containing the calcium carbonates is the main component in naturally abundant limestone. The limestone is quarried or mined, mechanically pretreated and delivered to the lime plant. One of the most common lime kiln types is the lime rotary kiln.
Oxyfuel combustion aims to concentrate carbon dioxide in the flue gases enough for utilization or storage. Replacing air (21% oxygen and 79% nitrogen) with pure oxygen can decrease the volume of flue gases from the process. This also increases the carbon dioxide concentration since no nitrogen is added to the system. Combustion in elevated oxygen concentrations increases the flame temperature. This increase in flame temperature changes the heat load of the kiln combustion area. Thus, flame temperature needs to be controlled. This is achieved by recirculating the flue gas back to the lower end of the rotary kiln. This work studies the effect of recirculation levels 50%, 60%, 70%, and 80%. The recirculated flue gas has a high carbon dioxide concentration. The increased carbon dioxide concentration increases the calcination temperature of the raw material. This will change the heat balances of the rotary kiln.
