Production Test of Torrefied Woody Biomass Solid Fuel in an Original Small-scale Plant

Abstract

In this study, an original small-scale demonstration plant was manufactured to produce upgraded wood fuel by torrefaction. The plant consists of a rotary-kiln type oven and a ring-die type pelletizer, and they were optimized for torrefaction based on the commercial models. We succeeded in more than 240 h operation of the torrefaction oven and produced 2.3 t of torrefied chips from raw Japanese cedar chips without drying. The energy yield of the torrefied chips was more than double the energy yield of conventional charcoal chips. The average length of the torrefied pellets was 7.4 mm, which is shorter than the length of the normal wood pellets. In the combustion test using a cone calorimeter, no delay in ignition time and small decease in heat release rate were seen for torrefied pellets in comparison with the results of normal pellets.

Production Test of Torrefied Woody Biomass Solid Fuel in an Original Small Scale Plant: (2) Effects of Automatic Temperature Control in Torrefaction and the Use of Additives in Pelletization

“…After mixing the ground torrefied wood powder (obtained from the hammer mill) with starch, pelletization was conducted under the same conditions that were described in a previous study 3) . The mixing ratio of the additive was determined to be 2 wt.%, according to ISO 17225-2 4) .…”

“…TC: Thermocouple. The location of the thermocouple was explained in a previous study 3) 1 is based on the test conditions of the previous study 3) , assuming that that the raw materials were purchased for JPY 8/kg-wet. It is also assumed that the total number of laborers required is ten (six personnel for the operation of the torrefaction oven and the remaining four for the operation of the pelletizer).…”

“…Currently, our group is focusing the small-scale utilization of forest resources, establishing a new bio-economy within a local community, and designing a demonstration plant 2) . We conducted more than 240 h of operation on a torrefaction oven and produced 2.3 t of torrefied wood chips from Japanese cedar (Sugi, Cryptomeria japonica) 3) . In the combustion test of torrefied pellets, there was no delay in the ignition time.…”

“…Process flow of the demonstration plant for torrefied wood fuel3) Product yield (wt%) = × 100 Wp Wp + Wd demonstrates the temperature profile before and after the installation of the automatic control device. By controlling the temperature based on the readings detected from two of the four thermocouples3) , which are installed in the oven, the operation was almost automatically completed. In addition, there was an approximately 30% reduction in the additional fuel placed in the furnace.…”

Water Resistance of Torrefied Wood Pellets Prepared by Two Methods

“…With regard to use on small scales, Yoshida et al studied the effects of torrefaction treatment conditions, mass yields, and calorific values at a laboratory scale [5,6]. They then constructed a demonstration plant with a treatment amount of 20 kg/h to continuously produce torrefaction chips from raw wood chips [7,8]. As a result of burning trials for the torrefied pellets in a commercial pellet stove, we found that the torrefied pellets demonstrated faster ignition time than normal pellets.…”