The overall production of beer products in Russia in 2019 amounted to about 14 million decaliters. Production of beer products involves a large amount of various resources consumption (both energy and manufacture), which leads to a significant amount of waste and CO2 emissions.
Currently, one of the successful approaches to reducing solid-phase waste from such production is their use in agricultural industry in the form of food additives for cattle. Often, the amount of waste produced in the regions significantly exceeds the consumption volume of the agroindustrial sector. Their transportation to neighboring regions is not cost-effective due to logistical difficulties. An alternative method of converting this type of waste is thermal conversion. The main product of thermal conversion is biochar, which is used as a biofuel for households.
This work is devoted to the study of the physical and chemical characteristics of biochar obtained by the method of steam gasification of biomass. Waste from the brewing industry was used as a sample of biomass (Tomsk, Russian Federation). Sample with initial humidity of 80 wt.% was drained to 10 wt.% using an air heater at a temperature of 60 °C. Steam gasification of the studied samples of beer industry waste was carried out using a vertical batch reactor at a steam temperature of 450 °C for 1 hour. The sample weight was 1 kg.
Quantitative values of non-condensable gas composition and changes in the sample temperature were obtained in the process of steam gasification of the biomass sample. The following compounds were identified as gas-phase products: CO2 (22.6 vol%), CO (19.6 vol%), CH4 (16 vol%), H2 (5.9 vol%). Biochar was used as the main product of the steam gasification process. Next, the sample was crushed and fractionated on sieves with a cell size of less than 200 microns. It was found using ultimate analysis that the carbon content in the test sample was about 64 wt.%. Also, sulfur (value) and oxygen (value) were recorded in the composition of the sample. Presence of a large amount of the latter is due to the natural origin of the sample and the presence of oxygen-containing functional groups. The obtained value of the lower calorific value (Qir=19.6 MJ/kg) was comparable to traditional solid fuels (coal, wood waste, peat, etc.). At the same time, it is important to note that degree of carbonification of the studied biomass sample increased by 24.1 % as a result of the gasification process. In turn, the ash residue increased by 10 % and amounted to 17.1 wt.%. Thermal analysis, which was performed at a heating rate of 10 °C/min and a temperature range of 25-1000 °C in air and argon (150 ml/min), showed that the biochar is characterized by a different reactivity in contrast to the original sample. Thus, there is a significant increase in the initial and final temperatures of intensive oxidation (∆Ti and ∆Tf 150 and 75 °C, respectively) and activation energy (by 57.4%) for this sample, as well as a decrease in the maximum reaction rate (∆wmax = 3,19 %/min). Significant change in the morphology of the particles was observed as a result of steam gasification of the studied biomass sample. Thus, the particles of the biochar sample are characterized by inhomogeneous surface with a large number of open pores and channels. The tubular structure of the carbon residue particles under study is clearly visible, which is formed as a result of volatile compounds release. This material is of interest for the energy industry, as well as for creation of new carbon-containing materials. It is also possible to assume a high increase in the value of the specific surface area and porosity of this material as a result of its chemical activation due to the high content of the mineral residue, which includes various alkali metals.
|Affiliation of speaker||Tomsk Polytechnic University|
|Position of speaker||Engineer|
|Publication||International journal «Resource-Efficient Technologies»|