Cement and Energy

made. Th e operator augments the information from the pressure under the grate with experience and intuition taking into account the broader kiln conditions and particularl y the kil n burn ing zone temperature. Irrespecti ve of the experience level of the operators they arc making infe rences as to the real situation in the cooler. This is where a Spyrometer can make a signifi cant contribution to kiln reliability and thermal cfli cicncy. A Spyromctcr in the Cooler With a Spyromcter installed in the cooler the operator can augment the information on under-grate pressure and burning ;.one temperature with a video image of the real situation in the cooler. Concerns that the cooler might be tilling can be set aside, and the thickness of the bed of clinker can he increased with confidence. Thermal erticicncy of the kiln and cooler can be increased without worrying that the cooler may fill and cause a kiln stop. The Spyromet cr is providing the missing information to sol ve the cfTicicncy/rcliability conflict. 1-"igure 2 Sflyromerer shows rhe rme conditions in rhe grate cooler The confidence which the Spyrometer, in stalled in the cooler, gives to the kiln operator is probably the greatest contribution it can make, but the benefits do not stop here. With a Spyrometer the progression of the surface temperature along the bed of clinker can be observed. Operators can adjust the air flow of the fans blowing cooling air into the under-grate chambers to adj ust this temperature progression. The cooling of the clinker and the recovery of thermal energy from the clinker can be optimised in a way which is impossible wi thout a Spyrometer. On a 3000 tpd cement kiln a one per cent saving in kiln fuel is sufficient to generate a return of investment for a Spyrometer in less than one year. The combined effects of giving the kiln operators the information and confidence to increase the clinker bed depth, and optimise the air flow of the cooling fans can be expected to achieve more than a one per cent kiln fuel savings. A Spyromcter install ation in a grate cooler can therefore be expected to give an attractive return on investment. There are also non-quantifiable benefits to installing a Spyrometer in a grate cooler. Optimisation of the cooling of the clinker will reduce the incidence of red hot clinker exiting the cooler. High temperature clinker presents a safety hazard for personnel and can present a fire hazard on rubber belt conveyors feeding cement mills out of clinker storage. High temperature clinker also adversely affects the efficiency of these finish grinding mills. Spyrometer in a Direct Aerated Cooler All cooler suppliers now offer a direct aerated cooler where the cooling air is passed through the grate and the bed of clinker via air beams, rather than being blown into a chamber beneath the grate. In th.is way an even distribution of air through the clinker bed can be achieved improving heat recovery and the cooling of the 8 ' __,