Evaluation of the Different Rice Hull Gasifiers Developed at CPU APPROTECH Center


       Four gasifier stoves, all developed at the Appropriate Technology Center (APPROTECH Center) of CPU, were evaluated in this study. These include: Gasifier A or the cylindrical-type single-burner, top-lit updraft (T-LUD); Gasifier B or the cylindrical-type double-burner, T-LUD (for household use), and, Gasifier C or the conical-type double-burner T-LUD(for household use), and Gasifier D or the conical-type double-burner T-LUD (for industrial use). Evaluation was conducted at the APPMTECH Center on April 23 to May 29, 2007. The stoves consisted of similar pans, namely air moving device, burner, char chamber, char grate, char lever, chimney, control switch, gas pipe, gas regulators, reactor, and pot support. Results of the study revealed that Gasifier A significantly (P<0.01) had the highest percentage production of char and thermal efficiency while Gasifier D significantly (P<0.01) produced the highest fuel consumption rate. In general, however, all the three double-burner stoves (Gasifiers B, C and D) significantly (P<0.01) had the highest fire zone rate and consumption of electric energy compared to Gasifier A since these stoves have the same number of burners and air moving device used. The gas emitted by the gasifier stoves were estimated to contain born 20-24% carbon monoxide, 13-23% hydrogen gas, 8-15% carbon dioxide, 38-42% nitrogen, 0-2% methane and 7-9% water or moisture. Among the gasifiers evaluated, only Glasifier A has the economic advantage over the LPG stove when used. The three other stoves were not practical to use in the household level.