Desirable modifications
The first months of operation revealed the following shortcomings in design and lay-out:
1. The accessibility of the impingement separator is poor and a vacuum cleaner is required to remove the dust.
2. The bag house filter maintenance is difficult. Removal of the top lid requires removal of a flange and the lid is too heavy requiring either three people or a mechanical device to raise it.
3. The grate shaker is not convenient to operate. A lever system which could be operated while standing up would be an improvement.
4. Condensate from the cooling tubes collected in the piping close to the engine inlet. It was necessary to fix and additional drain tank to this pipe.
5. Refractory lining flakes off, probably as a result of the frequent heating/cooling cycle. This could be avoided by supporting the base of the lining with a metal flange.
6. Hot radiator cooling air from the engine is partially directed towards the cooler of the gasifier. This diminishes the effectiveness of the gas cooler.
7. The fuel hopper is too small for coconut shells. It is inconvenient to have to refill the fuel bunker every 15 minutes.
8. The engine’s maximum power output is too low. Although the system is designed to deliver 40 kVA, it is possible to get 35 kVA only. This is probably due to the unorthodox system of engine speed control, which controls the gas and the air input to the engine simultaneously, instead of using the normal system where only a gas/air mixture valve is controlled.
Also from general principles it seems possible that the air/gas mixing in the engine’s simple gas/air carburettor is not complete, as a result of which some cylinders may get too rich and others too poor mixture.
5.1 Economic evaluation of electricity generation costs at