Effect of Torrefaction on Physical Properties and Conversion Behavior of High Heating Rate Char of Forest Residue

Abstract

In the work reported here, both forest residue (FR) and torrefied forest residue (TFR) were devolatilized in a drop tube reactor at 1473 K at a heating rate greater than 10 4 K/s. The physical properties of parent fuel particles and their corresponding char particles were examined by using a scanning electron microscope and a granulometer. After the same milling and sieving process, the TFR particles had a smaller size and smaller aspect ratio than the FR particles. The char particles consisted of two types of particles with different sizes and morphologies: a small particle mode (presumably char fragments) and a large particle mode. The volume fraction of char fragments in the TFR char was considerably less than for the FR char. Both types of char were converted in a drop tube reactor under oxidation and gasification conditions at 1473 and 1573 K, respectively. The total organic mass loss and release of individual organic elements during char conversion were determined using a tracer method. Calcium, manganese, barium, and magnesium were found to be suitable for use as tracers. The fractional carbon conversion rate of TFR char was found to be slower than that of FR char under both oxidation and gasification conditions. The fractional release rate of hydrogen was much higher than that of total organic mass loss, while the corresponding oxygen release was lower for both types of char and for different reactive environments.

Experimental and Modeling Study of the Effect of Torrefaction on the Rapid Devolatilization of Biomass

“…As shown in Figure 1, the DTR features a 1.5 m long vertical reactive section (tube reactor with 5.08 cm inner diameter) and a 1.0 m long horizontal gas preheater section. 12 The sieved biomass particles were supplied at a mass flow rate of approximate 50 g/h by a 4 standard liter per minute (slpm) room-temperature N 2 carrier gas. Fuel particles were injected through a water-cooled injection tube into the reactive section of the reactor.…”

Comprehensive Compositional Study of Torrefied Wood and Herbaceous Materials by Chemical Analysis and Thermoanalytical Methods

“…[6][7][8] Several types of biomass materials have been torrefied including agricultural [9][10][11][12][13][14][15] and forestry byproducts. [16][17][18][19][20] Torrefied wood and straw in the form of pellets can be directly co-fired with coal in a relatively high ratio hereby utilizing the processing infrastructures at existing coal power plants. As a consequence of the difference in the relative amount of cellulose, hemicellulose, lignin, and extractives, the woody and herbaceous materials behave differently during thermal decomposition.…”

Investigation into mean residence time and filling factor in flighted rotary torrefier

“…[2] Torrefaction is a slow heating process that is usually carried out in an inert environment and at atmospheric pressure within a narrow temperature range of 200-300 8C. [3][4][5][6] Torrefaction can increase energy density and reduce the moisture content and the hygroscopic nature of the raw biomass. This process also improves the grindability and flowability of biomass, making it more suitable to use in co-firing power plants.…”

“…Torrefaction is a slow heating process that is usually carried out in an inert environment and at atmospheric pressure within a narrow temperature range of 200–300 °C . Torrefaction can increase energy density and reduce the moisture content and the hygroscopic nature of the raw biomass.…”