Thermal Properties of Biocoke for Safety Storage

Abstract

In order to get out from under global warming, expanding use of renewable energy is proposed in many countries. Although biomass is one of the renewable energy, it is not common because of its disadvantage of low transport efficiency from low density. Since Biocoke of which biomass is heated with compression has high density and high compressive strength, it is used as substitute of coal coke in several types of furnaces or considered as an effective method of volume reduction of gathered radioactive biomass generated by the Great East Japan Earthquake. In Japan, Biocoke is determined as designated flammable goods in the same manner of Refuse-derived fuel, while it is reported that Biocoke is difficult to be ignited because of high density with little porosity. Although it is very important to know the thermal property while they are stored in other words, in the low temperature range, it has not investigated enough. So in this study, to investigate the possible origination of fire accidents, the generated heat from Biocoke made from bark and bark before making to Biocoke were measured by highly sensitive isothermal calorimeter in the condition of 50 °C, air packed atmosphere and for 3 days. The exothermic phenomenon which is caused by microbial fermentation was observed. Particularly, the sample with water addition appeared the large exothermal peak. In the both case with water addition and without water addition, the generated heat from Biocoke is less than that from bark. It is summarised that the storage of Biocoke is safer than that of raw material because microbial fermentation in the temperature range between 20 and 50 °C is inhibited by 130 °C heated in the Biocoke manufacturing process. In particular, Biocoke is much safer than raw material when stored in wet condition such as outdoor without roof.