Designing of cooling chamber of a rotary kiln incinerator.

Abstract

The report focuses on the failure of the cooling chamber of a rotary kiln incinerator at Luweero Industries Limited. The cooling chamber is supposed to cool the hot exhaust gases from a temperature of 13000C to a temperature of 800C which is the normal temperature accepted by the National Environmental Management Authority (NEMA). Due to its failure, hot exhaust gases are released to the environment causing adverse climatic conditions and attracts huge fines from NEMA. As a way of overcoming this problem, a shell and tube heat exchanger model was designed using Aspen software and an economic analysis was also carried in Aspen Exchanger Design and Rating Software to ensure that the model is economically feasible. Data from the faulty cooling chamber such as flowrate, temperature was used as input in the material flowsheet in Aspen. Several simulations were carried out so as to obtain a model with the desired temperature range. The model obtained after several iterations/runs showed that the hot exhaust gases coming in at a temperature of around 900OC are going to be cooled to a temperature of 80OC. The water used as a coolant in our model, flowing at a rate of 302.0801 liters/ minute will be warmed by the heat exchanged from a temperature of 25OC to a temperature of 59.06733OC. The model will have 221 tubes within its shell, arranged in a triangular tube pattern to increase the contact surface of the water with them hence allowing maximum exchange of heat. The tube length is 59.0551 inches, and this increases the contact time of the hot exhaust gases with the water. According to figure 4, the number of tubes arranged in each section of the shell is shown and their tubular spacing. The efficiency of the model was found to be at 87% and its total cost was 21627 USD for all the shells.