Cement, Energy & Environment Jan-Mar 2002

.. proposes a new innovative solution for achieving significant and controllable NOx reductions using the most cost-effective means. The author discusses that in view of the availability of quality information on temperature in the kiln, it is becoming less acceptable to emit high levels of NOx from cement kilns. Low NOx burners and high efficiencies are largely contradictory and as a result now kiln designs depend on some sort of post kiln staged combustion NOx reduction . Selective non catalytic reduction (SNCR) of NOx such as inj ection of NH 3 compounds, exothermic nature of temperature reaction for limiting to arow1d 1450°C and water injection around the burner sys tem and staged combustion have been discussed in the article. Courtesy : /ntemational Cement Review, jan. 2002, Pp. 63-66 E-mail: info@CemNet.co.uk Web: CemNet.com ARCHING AND RATHOLING IN SILOS I.. Peschl, The Netl1erlands The behaviour of a powder in an industrial installation is an interaction of the installation with the powder properties and the influence of powder properties on the functioning of the installation. In today's automatic production processes the proper function of all links of a chain of a process are responsible for the function of the whole process. A silo is one such link in the chain. Bridging or ratholing in the silo can block the whole process and cause a discontinuity with high technical and financial consequences . The influence of the silo are: silo geo.metry (diameter, height and angle of the hopper), pressure and wall friction. The influences through powder are the cohesion, angle of internal friction, density and unconfined compressive strength. The common interaction is between the wall friction and 28 the pressure in the silo. A number of approaches have been developed over the years, the best known being the 40 year old approach ofJENIKE. This approach, however, doesn't take into account the size of the silo nor of the hopper. We will try to develop a theoretic model based on soil mechanic as used in mining and civil engineering for calculation of pits, tunnels and shafts, Courtesy : Powder handing and processing, Vol. 13, No.4, Oct.-Dec. 2001, P 357 E-mail: powder@transtech-online.com Web: www. transtech-online.com THE POWER OF ACOUSTIC HORNS IN THE CEMENT INDUSTRY BHA Group International Pvt. Ltd., India This paper highlights a number of the primary applications of acoustic horns in the cement industryJ but is by no means definitive. Acoustic horns are available in many shapes and styles for the various applications mentioned. The sound waves are produced by compressed air rapidly entering the soun9. generator (driver), causing the diaphragm to fle x. As the pressure is equ alized, the diaphragm impacts the pedestal, generating a sound wave that is then amplified by the horn bell. The sound waves generated by an acoustic horn create vibrations that canbreak apart and dislodge material deposits from surfaces. The vibrations are similar those createdby striking the surface with a mechanical impact. However, with acoustic energy (unlike a sledgehammer) there is no threat of structural damage. The vibrations are powerful enough to break apart heavy concentrations of particulate, but gentle enough to not hurt the surface. Once the material has been dislodged, gravity and/or gas flow removes it.