Energy Utilisation in Brick Kilns
Sameer Maithel, Ph.D, 03
Supervisor(s): A. W. Date
This thesis deals with experimental and analytical investigations on energy utilisation in two types of continuous brick kilns - Bull's Trench Kilns (BTK) and Vertical Shaft Brick Kiln (VSBK). Methodology and instrumentation are developed for the field experimental work. Experimental investigations are carried out on two commercial kilns - one each, of both types. The novel features of the field experiments are: measurement of the brick and gas temperature distribution in BTK; use of travelling as well as fixed thermocouples for measuring brick temperatures in VSBK; measurement of ground temperatures to evaluate ground heat loss in BTK; and measurement of air infiltration in BTK. To the best knowledge of the author, these measurements are carried out for the first time in these kilns. The VSBK was found to have lower SEC (0.84 � 0.04 MJ/kg) compared to the BTK (1.12 � 0.03 MJ/kg). The experimental investigations resulted in evaluation of comprehensive energy balance statements and characterisation of firing behaviour of the kilns in the form of heating and cooling rates, temperature distribution across kiln cross-section, estimation of airflow rate, air infiltration etc. The experimental investigations on BTK identified ground and surface heat losses as the main heat losses contributing towards 27.5\% of the heat loss. Sensible heat loss associated with fired bricks and dry flue gases were identified as the main heat loss in VSBK. The ratio of airflow to brick flow (l) in VSBKs was found to remain close to 1.0 and this was identified as the main reason for its low energy consumption. Surface and ground heat losses are the focus of study during analytical investigations on BTK. The heat transfer through the roof and the ground is considered as one-dimensional transient heat conduction problem and effect of various operating and design parameters on these heat losses is studied. A one-dimensional heat transfer and combustion model for VSBK is developed. The model is used for studying the effect of geometric and operating parameters on kiln performance. Guidelines are presented for improving energy performance of BTK and VSBK.