Performance Analysis Of A Model Pulverized Coal Combustion System

ABSTRACT

Performance analysis of a model pulverized coal combustion system is undertaken. The system consists of a hopper, screw conveyor, blower, electric motor, among others. The design and construction of the system focused on the following procedures in this work: The outlet of the pulverized coal from the silo opens directly into the receiving hopper of the screw conveyor. The drive of the blower is connected to the drive of the screw conveyor via bearings, pulleys, belt and gears. This means that one electric motor drives both the blower impeller and the screw conveyor shaft. The outlet of the conveyor is connected to the blower outlet hole so that the air from the blower meets the incoming pulverized coal. The air then sprays the pulverized coal into the already heated combustion chamber. The combustion chamber is heated initially with a pilot flame from burning wood so that the temperature of the chamber is elevated so as to make it easy for the pulverized particles of coal to ignite easily in the chamber. Once the combustion of the pulverized coal has started, the pilot flame can be withdrawn, combustion of the coal then continues until the content of the silo is finished. The ash formed during combustion of coal goes out through the ash exit outlet. Performance analyses results show that the designed system has a maximum thermal efficiency of 46.5%, maximum system efficiency of 43%. This shows an encouraging performance when compared with the thermal efficiencies expected in the brown coal fired plants which are around 42%, and 45% for equivalent new bituminous coal fired units. Furthermore, the performance of the designed system is good when compared with some wood based fuel burners such as the improved vented mud burner (IVM) which has the thermal efficiency values across fuels that varies from 10% to 23%.