Cement and Energy

As a matter of fact, the fur ther the injection is located from the name axis : • The worse the di~ribution of solid fuel particles in the tlame. • The more difficult ..1e p'enetration of the solid fuel stream into the flame. such solutions are less than ideal unless the 'f... ..1ty of waste fuel is low with regard to the total burner heat release. The distribution of particles to be burnt must be as homogeneous as possible to avoid some of them remaining partially unburnt, leading to high CO formation at the kiln end. It is recommended that, to r lsure proper combustion : .. In conclusion, integrat~d burners may be proposed where the alternative fuels are injected together, for better flame pattern control. This is definitely not possi ble when firi ng with injectors or auxil iary burners located outside the main burner, since they cause discrepancies in the original flame, irregularities in concentration , leading to CO formation. Burning alternative fuels in cement precalcincrs Due to the different types of precalciners available on the market, a close collaboration between cement producers, engineering companies, and Pillard, is needed to optimising the operating conditions when firing • The solid waste be ground as linely as is reasonably possible, with a homogeneous granulometry distribution so that no large pieces remain. _. .. &ANL~MR~a-~---·-·-·-·---·;·-·-·-·-·-·-·-·-·-·-·~·-·-·-·-·-·-·-·-·-----1--- ~ i I .-ll;J! ' . ., ·"" ,... ,. "'' ,.• '• .:·r: ...... ·:•.·: --:" . I _j..uwJ • The waste is conveyed (in general pneumatically), so that the injection is regular with no lluctuations of pressure and flow rate. Example of a Pillard precalciner burner firing gas and a pulverised solid fuel. • The waste is injected into the llamc as homogeneously as possible, and not through the external flame surface, which leads to poor mi-xing.' Two technologies are used for this purpose : the addi tional annular channel and central injection. The velocities, conveying ai r percentage and adjustment of swirl/axial primary air, must be optimised at the design stage for better flame control with more fl exibi lity than a conventional burner. The relative dimension of the burner stabil ising plate must be modified to ensure fl ame stability at all operating conditions. Simultaneously firing residues with different viscosities, volatile contents and linenesses may require higher primary air flows in order to increase ol % in the primary name. and higher veloci ties in order to shorten the flame. Sr ecilic designs adarted to any particu lar situation arc available after srecific calculation. ZV4 atomising gun. alternative fuels. Residence time and lower internal temperature than in the kiln are the main concerns. The precalciner burners are designed on a case-by-case basis according to precaleining process requirements. PASTY ~~S ZVK atomising gun for pasty residue. 9