Operational experience
5.3.1 Operating record and observations on the performance
The biomass gasification plant was in operation intermittently for about forty hours in November 1982 on several fuels at Peradeniya University.
Operational data are presented in Table 5.1
Some tendency to slagging was observed when operating on coconut husks, rubber tree wood and coir dust briquettes. Quite possibly this was due to a relatively large amount of sand that was introduced into the gasifier together with the fuel. Regular grid rotation prevented excessive pressure drop across reactor and bunker, and bunker flow could be maintained at the de-sired levels.
At the end of November 1982 the unit was transferred to Giriulla Mills where it has since been operating, fuelled by coconut shells.
Operational data for this period are also summarized in Table 5.1. The system is producing power for six desiccating motors at a load of up to 30 kVA.
The system can follow a step load change of 20 kVA.
Collected condensate appears to be a clear liquid, indicating that only traces of tarry components are present in the producer gas.
The overall system efficiency was between 15 and 20 percent, as a ratio of output electrical energy to input biomass energy.
System efficiency is of course dependent on fuel characteristics, load characteristics and environmental conditions. The highest efficiency was obtained when operating on coir dust briquettes; the slagging tendency of this fuel has to be further tested in an extended run, in order to decide whether automatic and continuous grid rotation is necessary.
At Giriulla Mills the system was continuously operated for about 1000 hours.
From Table 5.1 it is clear that on average the installation was operating at 50 percent of its full capacity. From the more detailed data it may be concluded that operation periods at loads of around 33 percent of full capacity are frequent.