Process simulation of rice straw torrefaction
Journal
Sustainable Environment Research
Journal Volume
22
Journal Issue
3
Pages
177-183
Date Issued
2012
Author(s)
Abstract
Crop residues are considered to be important feedstocks for partial fossil fuel substitution in energy production. Therefore, utilizing crop residues such as rice straw which is abundant in Taiwan has been proposed for electricity generation that enhances energy security and sustainability. However, the high moisture content and low heating value of rice straw affect its biomass utilization efficiency. Furthermore, poor grindability of rice straw decreases rates of co-milling with coal at coal-fired power plants. Torrefaction is a thermal pretreatment technology which improves the properties of biomass in order to deal with the above problems. Simulation of the process which produces biocoal from rice straw by torrefaction was conducted in this paper. It was found that the volatile gas is combustible even though the gas consists of 49 wt% non-combustible content. Results also show that the process which is carried out at 250 °C for 30 min can be operated autothermally when the input (wet rice straw) moisture content is less than 12 wt%. The process product yield increases with decreasing wet rice straw moisture content. Moreover, the process thermal energy efficiency was estimated to be 0.85 when the process was operated above the point of autothermal operation. According to the results, rice straw could be sun dried off in the field to reduce moisture content before transport to the torrefaction plant in order to improve process performance. The obtained information should be useful for the design of logistic studies of biomass, or future applications of rice straw torrefaction for energy production. © 2012, Chinese Institute of Environmental Engineering. All rights reserved.
Subjects
Autothermal operation; Combustibility; Energy model; Rice straw; Torrefaction
SDGs
Other Subjects
Agricultural wastes; Biomass; Coal; Crops; Energy efficiency; Energy security; Flammability; Moisture; Moisture determination; Auto-thermal operation; Coal-fired power plant; Electricity generation; Energy model; High moisture contents; Rice straws; Thermal pre-treatment; Torrefaction; Fossil fuel power plants
Publisher
Chinese Institute of Environmental Engineering
Type
journal article