Cement, Energy and Environment July-Sep 2002

separator wi th two dip tubes instead of one. One is situated at the top, as in common cyclones, and one at the bottom. With this doubled area for the clean gases, one can keep the velocity in the dip tubes low and therefore maintain a lower pressure drop. Additi ona ll y, one HURRIYAN E® unit is we lded to each dip tube, which brings further pressure loss reduction. With this low pressure drop, it is possible to design a smaller ou~s ide diameter and reach hi gher ve loc it ies to increase the centrifugal forces, thus resul ti ng in a better separati on effic iency. Depending on the parti c le s ize di stribution, gas quantity and dust load, the HURRICLQN®is able to reach a separation efficiency of up to 99%. Compared to common cyclones the HURRICLQN® requires less space, therefore the peripheral investment cos ts are also lower. With thi s redu ced space requirement, it is poss ibl e to build a small e r I!URR!CLON®, or replace two ex 1s t1n g cyc lones with one HURRICLQN®unit. J n the sintering zone of rotary kilns, parts of alkalis, sulphur and chlorine are liquid/gaseous. Above app rox imate ly 800 o C a lkali s, sul phur and chlorine start to vola tili se. With the gas flow through the ki ln, the volatile parts arr ive at the cooler preheater, where they condense on the material. This mechan ism IS the sta rt of recirculation. When di verting part of the gases through the by pass valve, by side-tracking part of the gases in the lowest part of cyclone stage IV riser duct, it is possible to reduce the circuit. The increase in heat consumption caused by the bypass operation amounts to 4 - 5 kcal/kg of clinker/ I vol% bypass. The kiln dust turned aside by the bypass va lve amo unts to approx imately 0. 1% per I vol% by-pass depending on the weight of the ~aw mix. The temperature of the bypass. gases· at the bypass va lve is approximately 11 00 o C. The chemical/physical be hav iour of alkali s, sulphur and chlorine requires the use of cold air for coo ling th e bypass gases to approximately 450 o C. This coo ling air wi ll be pressed in a quenching chambe r, with a fan driven by a speed controlled motor. The gases wil l be transported through a piping sys tem to an ex isting/modifi ed e le ctrostatic precipitator in which the gases are dedusted. The gas transport is carried out by an existing/modified fan driven by a speed contro lled moto r after th e e lectro sta ti c precipitato r. The clean gases after the fan will be used for drying raw material or in a future extension for drying slag. The materials that can be used in the WASTEPREP®process range from was te oil and so lvents, contaminated wood, tyres, plastics and domestic waste to animal meal with calorific values of2000- 8000 kcal/kg. The preparation process includes every necessary step from the delivery of the r.aw alternati ve material to the burner, in cluding storage, convey ing, se parating, shreddering and dos ing. The alternative fuels are brought into the kiln through the main burner, except prepared tyres and rubber, which are fed into the kiln entrance. Courlesy: World Cemellf June 2002. Pp 79-81. C.nqui1y no: '20. Fax: +.f./(0) 1252718992 Email: mail @ li'Orldcement. com Web: ll'll'll'. li!Orldcement.com QUENCHING A HOT TOPIC Dr. Michael Clark The Techni cal Forum receives questions every month concern ing flame s, fu e ls and combus ti on . Normal ly th ese quest ions are answered by empha sis ing th e compl ex ity of th ese iss ues and recommending that the advice of a speciali st comp any is so ught. Nevertheless, the questions keep coming. Why is thi s? Courtesy: lmernational Cemem Revieu•. July 2002 P33. E-mail: info@CemNet co.uk Web sire: CemNet. co. uk SUITABLE MAG-SPINEL BRICKS FOR Ti lE UPPER TRAI'iSITION ZONE OF ROTARY CEMENT KILNS Magnes ia Alumina Sp ine l Bricks are composed of dead burnt magnesia and different combination of s inte red and fu sed magnes ia alumina spinel. These bricks have high thermo mechanic properties li ke thermal shock, stability and elasticity. Magnesia alumina spi nel bricks have high performance at upper transition zone of rotary kiln whi ch has hi gh pe rcentage o f alkalies compounds. It is important to choose refractory bricks for upper transition zone ofcement rotary ki In aft er dete rmin ati on of alkali sulph ate ra tio (AS R) and .she ll deformation. SP 85 A and SP 90 A are new bri ck brand names for transition zone of cement rotary kiln which has high amount of alkalies compounds. Courte:,y : CementandConcrere World. A fay-Jun. 1002. P--19. Fax: (903 12) 2879r2 E-mail: i J?fo((~/cma. org.tr. -