Experimental Study On Material Resistance And Cooling Heat Transfer Of The Cement Clinker Grate Cooler

Grate cooler is the core equipment in the cement clinker production,the amount of heat recovery and hot air quality have a direct impact on the stability of the kiln system and energy consumption level.At present,most of the researches focus on the computer simulation of clinker cooler cooling heat transfer,which acted a certain guiding role in the production.However,due to the actual conditions of the complexity and uncertainty,it cannot reflect the current problems of the grate cooler,and exist some limitations.In this paper,the cold test and thermal experiments are carried out by using the method of small-scale engineering experiment to the material layer resistance and cooling heat transfer with different grate wind speed,different particle size and different material thickness.What’s more,the experimental verification and analysis of the phenomenon of grate cooler in the production process are studied,such as the wide grate plate gap,material segregation,flying sand and so on.The main conclusions as followed:(1)The results show that with the decrease of clinker particle size,the resistance of the material layer gradually increased.The void ratio has the greatest influence on the resistance of the material layer.The Eugen formula is not applied for calculating the resistance of the grate cooler.Through the repeated experiments on the clinker with different particle size,the empirical formula of accurately estimating the resistance of the layer is summarized.(2)In the direction of the height of the material layer,the distribution of the resistance of the layer is not the same,and the resistance of the bottom layer is much larger than the upper,and the explanations are found.In actual production,It should be considered when designing the grate plate and matching the fan.(3)The fluidized experimental characteristics of flying sand are in good agreement with the non-uniform fluidization of gas-solid system.The experimental results showed that the fluidization velocity was about 0.38 m/s,which was smaller than the theoretical calculation,and the curves of ΔP~u were drawn.Among them,the flow velocity and fluidization limit velocity were calculated by the method of Archimedes quasi-method,which was close to the actual test value.(4)In a certain range,increasing the wind speed is con ducive to the heat transfer air and clinker.When the Clinker particle size is 20-31.5mm,the temperature is 850℃,and the wind speed increases from 1.17m/s to 1.29m/s,it is benefitful to clinker heat transfer.However,when the wind speed beyond 1.29m/s,the effect is no longer obvious.The particle size of clinker particles is the maximum factor affecting the comprehensive heat transfer coefficient.The smaller the particle size is,the faster the heat transfer is.At the initial stage of cooling,the temperature clinker surface is high,and the temperature difference between clinker and air is large,but the cooling rate is basically the same.(5)under the condition of the ventilation area is 2.48%,particle size is 20-31.5mm,material layer is 200 mm,the clinker cooling rate is significantly reduced and the air temperature dropped 31℃caused by the grate gap of 3mm.In the test of coarse and fine material segregation,it is found that the air temperature of Φ10-16mm+Φ20-31.5mm is 71℃ higher than the experimental group of Φ5-10mm+Φ20-31.5mm.It is also concluded that the gap between the grate plate and particle segregation is the main reason for the uneven distribution of the cooling air and the low temperature of the second and third air.