Development and manufacturing of a prototype pulverized fuel feeder for a micro burner
Botha, Daniel Jacobus
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Existing coal fired power stations could be improved by increasing the efficiency of the combustion process. The combustion process is incorrectly set up since inaccurate calorific values (CV) for the pulverized fuel is used in the calculations. These inaccurate calorific values are the result of there not currently being a way to correctly measure the energy released during fuel combustion. Hence, current calorific measuring devices cannot simulate the conditions found inside the combustion chamber of a power station. A microburner should be built that is capable of simulating the combustion chamber environment and allow for correct measurements of calorific values of the pulverized fuel (PF). During operation of the microburner, the initial combustion of the powder inside of the combustion chamber is done by using propane gas. Thereafter, the microburner has to solely rely on the PF flow into the microburner to keep the flames ignited. As a result, this continual flow of PF into the microburner is of great importance for the operation of the burner. In this study, a prototype pulverized fuel feeder was designed and build that fulfils the requirements needed for a microburner. Various tests were conducted with the prototype pulverized fuel feeder and these tests can be divided into four distinct phases. The first two phases tested the feeder’s functionality and was used to alter the design of the pulverized fuel feeder. Also, the proper method to attach measuring devices to the feeder was studied in these two phases. In the last two phases the repeatability, accuracy and possibility of a set flow rate of the feeder was tested. The results obtained showed that the current design of the prototype PF feeder is incapable of successfully delivering a specific constant flow rate. However, the feeder is capable of delivering flow rates within the required range if some requirements were met. These requirements are: PF should contain no moisture, operational sizes should be small and more pre-test should be done to predict operational size to adjust gas input accordingly. In conclusion, several types of bridge formations was identified and classified based on their strength and how they influence the feeder’s performance. Therefore, the prototype feeder design can be improved with the knowledge obtained in this study.
- Engineering