Measurement of Heating Value of Rice Husk by Using Oxygen Bomb Calorimeter with Benzoic Acid as Combustion Adjuvant

Heating value is a primary parameter availed in the design process of thermochemical conversion apparatus of rice husk. The published data for rice husk are different due to the diversity of testing conditions and rice husk varieties. In this study, the higher heating value of rice husk was measured by using oxygen bomb calorimeter with benzoic acid as combustion adjuvant. The effects of sample mass, oxygen gauge pressure and mass ratio of rice husk and benzoic acid were discussed. The results indicate that the measured higher heating value of rice husk increases at first with the increase of oxygen gauge pressure and the mass ratio of benzoic acid and rice husk, and then decreases. When the rice husk sample mass is 0.6 g, the oxygen gauge pressure is 3.0 MPa, and the mass ratio of rice husk and benzoic acid is 1.2:1, the higher heating value of rice husk reaches maximal, i.e. 15944±55 J/g that corresponds to complete combustion and appropriate testing conditions. The measured heating value in this paper is higher than that based on the testing conditions specified in British and Chinese testing standards respectively. The present study documents new higher heating value of one Chinese rice husk and formulates a useful method for the determination of testing conditions under which the heating value of rice husks is measured.