bioresources. com
PEER-REVIEWED ARTICLE
wood fiber or sanding dust silos, dry wood fiber conveying systems, mat forming units, mat or panel cutting units, wood dust collecting systems, as well as the grinding and sanding systems. Combustible dust clouds can be easily formed in the above units and thus could be ignited by heat, fire, or spark. Therefore, more attention should be paid to these units in production. The measurement of P max and (d p /d t ) max are the basis for designing, constructing, and monitoring critical equipment and protective systems. In this research, wood dust was obtained from Populus alba L., Pinus massoniana Lamb. and Cinnamonum camphora (L.) Pres., which are commonly utilized for fiberboard production in China. The influences of particle size and concentration on the wood dust explosive power were investigated. Wood dust samples from three species of trees, Populus alba L., Pinus massoniana Lamb., and Cinnamonum camphora (L.) Pres., commonly utilized in medium density fiberboard production in China, were used to investigate the explosion characteristics of wood dust. All dust samples were generated by sawing, chopping, and grinding from solid wood supported by Dare Artificial Board Group Co., Ltd., Jiangsu province. Four groups of wood dust samples with different particle size (250 to 500 μm, 125 to 250 μm, 63 to 125 μm, and 0 to 63 μm) for each species were obtained by sieving (Analysette 3 Spartan, Fritsch, Idar-Oberstein, Germany) and particle size analyzing (Mastersizer2000, Malvern Analytical, Malvern, UK). Experimental Methods EXPERIMENTAL Preparation of Wood Dust Samples Morphological, thermogravimetric, and elemental characteristics of wood dust from three different species were investigated using a polarizing microscope (Olympus BX51, Tokyo, Japan), a synchronous thermal analyzer (Netzsch STA 449C, Bavaria, Germany), and an elemental analyzer (2400 II, PE, Waltham, MA, USA), respectively. In the thermogravimetric analysis, dust was heated from room temperature to 750 °C using a heating ramp of 20 °C/min in an N 2 environment (20 mL/min). The content of carbon, hydrogen, nitrogen, and sulfur element were determined in an O 2 environment. Investigation of the maximum explosion pressure ( P max ) and the maximum rate of explosion pressure rise ((d p /d t ) max ) were carried out with a Siwek 20 L apparatus (Kuhuer, as shown in Fig. 1) in accordance with the standardized test procedures BS EN 14034-1 (2004) and BS EN 14034-2 (2006). This apparatus is comprised of a water- cooled explosion vessel with a volume of 20 dm 3 , an ignition source composed of two chemical igniters each with 5 kJ of energy, a control unit sequencing, and a pressure measuring system including at least two pressure sensors and one piece of recording equipment (KSEP 310 and KSEP 332, Kühner, Zurich, Switzerland). Before starting the test procedure, the moisture content of all dust samples was conditioned to less than 5% using an oven (BPG-9050AH, HASUC, Shanghai, China) and the temperature inside the vessel was 20 °C. For testing, the required amount of dust was placed in the dust container. After being vacuumed to a vacuum of 0.6 bar, the container was pressurized to an over-pressure of 20 bar. The dust sample was dispersed into the sphere from the dust container via the fast-acting valve and a rebound nozzle. The time lag of the outlet-valve ( t d ) was outside the acceptable range of 30 to 50 ms. The
3184
Guo et al . (2019 ). “Explosion of wood d usts,” B io R esources 14(2), 3182-3199.
Made with FlippingBook Digital Publishing Software