Tar content and composition during a low-temperature steam gasification of rice husks

摘要

The research work extends our recent empirical knowledge on the rice husks, a carbonaceous solid material. This solid biofuel option was characterized with a potential net heating value of 16-17 MJ/kg, significant high ash deformation temperature recorded above 1450 °C, capable and considerable for thermochemical conversion systems. An experimental performance on a dual fluidized bed steam gasifier using rice husks pellets was carried out at a low temperature between 600 and 650 °C and fuel power of 100 kW_(th). Pure steam was used as a gasification agent in fluidization at a steam to fuel ratio of 1.2 kg/kg on dry basis. Calcite with mainly CaCO_3 in composition was used as bed material for the reactor. Tar content and composition in the product gas stream were analyzed with a gas chromatograph coupled with mass spectrometer (GC-MS). Significant high amounts of total GC-MS tar components (without benzene, ethylbenzene, and xylene) and gravimetric tar (higher molecular tar) were detected at 29.44 and 17.82 g/m3 on dry basis. Benzene content was, respectively, presented on a value of 9 g/m3 on dry basis. Obtained products consisted of relevant amount of phenol and heterocyclic aromatic tars (class 2). The specific composition of common and additional analytes presented in GS-MS tar was summarized for better understanding of tar formation and reduction phenomena of rice husk gasification.