APLICABILITY OF THE SPOUTING REGIME FOR DRYING OF BIOMASS WASTES IN CONICAL SPOUTED BEDS WITH A DRAFT TUBE
Sustainable process-product development & green chemistry
Sustainable & Clean Technologies-I: Extraction & Remediation (T1-4P)
Keywords: Conical spouted bed, draft tube, wastes, drying
Since biomass and agroforestal wastes usually have high humidity content is necessary to reduce this one before the treatment methods, so it is necessary to make a previous drying to other treatment operations. The spouted bed technology is very useful for applications where a vigorous movement of the solids is required, as happens in the handling of solids that are sticky, of irregular texture and with a wide particle size distribution (San José et al., 1993). The first application of spouted beds was drying of grain. Several authors (Passos et al., 1987; Mujundar, 1984; Strumillo et al., 1980; Viswanathan, 1986) have used spouted bed in drying of granulated materials.
In order to determine the applicability of the spouted beds with a draft tube in the drying, in this paper the operating conditions in spouted bed regime of uniform beds made up of different biomass wastes dry and wet have been studied. This experimental study has been carried out at 20 ºC and the effect of the solid humidity on the stability of beds of biomass wastes has been determined. It is proven the great stability of beds of moist sawdust (up to wt % 50) and that system stability decreases as solid moisture increases.
The experimental unit design at pilot plant scale is provided with a blower that supplies a maximum air flowrate of 300 Nm3/h at a pressure of 1500 mm of water column.
Five conical contactors of poly(methyl methacrylate) with the following dimensions: column diameter, 0.36 m; cone angle between 28 and 45º; base diameter Di, 0.62 m, gas inlet diameter Do= 0.03, 0.04 and 0.05 m. The values of the stagnant bed height Ho, used are between 0.05 and 0.30 m. The values of length of the central draft tubes, lt, are between 0.010 to 0.30 m and the distance between the base of the contactor and the lower level of the device, ht, between 0.01 and 0.10 m, respectively. Solid moisture has been measured by means of a hygrometer AQUA-Boy KPM HM III.
The solids studied have been pine bark of Sauter average particle diameter, dS= 1.5 and 3.5 mm, pine sawdust of Sauter average particle diameter, dS= 0.95, 1.5 y 4.2 mm, pine shavings of dimensions between 5x15x0.05 y 15x35x0.05 mm and cork wastes of Sauter average particle diameter dS= 1.5 and 2.5 mm.
-Mujumdar, A. S. In Drying'84; Mujumdar, A. S., Eds.; Hemisphere Publishing Corporation, 1984, pp. 151-157.
-Passos, M. L.; Mujumdar, A. S.; Raghavan, V. G. S. In Advances in Drying,; Mujundar, A. S., Ed.; Hemisphere Publishing Corporation, 1987, pp. 359-396.
-San José, M. J.; Olazar, M.; Aguayo, A. T.; Arandes, J. M.; Bilbao, J. Expansion of Spouted Beds in Conical Contactors. Chem. Eng. J. 1993, 51, 45-52.
-Strumillo, C.; Pakowski, Z.; Stolarek, P. In Drying'80, Vol. I, McGraw-Hill, 1980, pp.4-15.
-Viswanathan, K. Can. J. Chem. Eng., 1986, 64, 87.
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Presented Monday 17, 13:30 to 15:00, in session Sustainable & Clean technologies - I: Extraction-Remediation (T1-4P).
