RESEARCH OF WHEAT BRAN AND PRODUCTS OF THEIR PYROLYSIS FOR EVALUATION OF ENERGY USE POSSIBILITY

Abstract

The aim of the work is research thermal characteristics of bran and products of pyrolytic processing to evaluation the possibility of their use as a fuel. As research methods, experiments were used to determine the yield of pyrolysis products and their characteristics, as well as differential thermal analysis. Thermotechnical characteristics of raw materials are determined by АСТМ Е1755-01, ISO 589:2008, ISO 5071-1:2013 and a bomb calorimeter ABK-1 (RET, Russia). The elemental composition of the raw materials is determined by the Vario Micro Cube analyzer (Elementar, Germany). In result of the work is established that wheat bran has a high heat of combustion (16.6 MJ/kg) for biomass and a high yield of volatile (81%). The ash content of raw materials was 6.9%, herewith the ash residue has a sintered character at temperatures above 725 °C, which indicates the slag ability. The active stage of bran decomposition proceeds in a temperature range 225–500 °C, that established by means of the differential thermal analysis. The results of material balance determination showed that the carbon residue (43%) has a predominant yield from the raw materials, the share of pyrogenetic water is 29%, which is due to the exothermic reactions in the bran during heating, resin – 12%, gas – 16%. The CO2 and CO concentrations are dominated in composition of pyrolysis gas during a heating temperature to 350 °C, which is associated with the decomposition of the main components in the bran – cellulose and hemicellulose. The methane concentration begins to increase after 350 °C and reaches a maximum at 450 °C, the decomposition of thermally more resistant lignin was occured at these temperatures. The maximum gas heat of combustion (9.3 MJ/m3) was associated to the peak of methane concentration in gas.