Continuous Drying of Slurry in a Jet Spouted Bed

Abstract

The performance of a laboratory scale jet spouted bed (JSB) for drying rice flour sluny was studied. The bed consisted of ceramic balls (5.28 mm diameter) and the rice flour slurry was sprayed onto the moving particle surface near the air inlet port. All the experiments were carried out at the jet spouting regime. This regime has high bed void fraction and violent movement and collision of bed panicles. As a result, the dried product layer is attrited from particle surface as a fine powder and entrained from the bed by the spouting air. The experimental results were presented to show the effects of static bed heicht. inlet air flow rate and temoerature. and feed concentrotion and flow r 3 t C on thhoutlet air temper~ture. ther&l efficiency. and mean panicle size 2nd moisturecontentof the product. A simple m~lhemal~cal model. which is based on the conservation of mass ind energy eqiations, was developed. Predicted results agreed well with those obtained from the experiment.

Hydrodynamic characteristics of a pulsed spouted bed of food particulates

“…Due to many shortcomings and limitations of a conventional spouted bed (CSB), however, a number of research works have been devoted to the study of modified spouted beds, both in terms of their hydrodynamic and heat/mass transfer (especially drying) behavior. These include studies of two-dimensional spouted beds (Kalwar et al, 1992;Passos et al, 1993;Prachayawarakorn et al, 2006), which can be scaled up easier than a conventional spouted bed; multiple spouted beds (Wang and Wei, 1999;Ren et al, 2010), which give higher circulation velocity of solids comparing with a conventional spouted bed at the same unit size; annular spouted beds (Hao et al, 2008;Guoxin et al, 2008), which present higher gas-solid heat transfer rate than a conventional spouted bed; draft-tube spouted beds (Freitas and Freire, 2001;Marmo, 2007), which provide more uniform particle residence time and exhibit lower pressure drops than a conventional spouted bed; jet spouted beds (Tia et al, 1995;Shuhama et al, 2003;Devahastin et al, 2006), which have been developed for very large, irregularly shaped and difficult-to-spout particulates and for drying of liquid slurries via the use of inert particles; rotating jet spouted bed (RJSB) and rotating jet annular spouted bed (RJASB) (Jumah et al, 1996;Devahastin et al, 1999), which can minimize the energy consumption during drying of large particles in the falling rate period.…”

Drying of Liquid Feedstocks in a Spout‐Fluid‐Bed with Draft‐Tube Submerged in Inert Solids: Hydrodynamics and Drying Performance

“…Since then, this technique has been used for drying chemicals (Mathur and Epstein, 1974;Ormos and Blickle, 1980) as well as biological products such as: animal blood, animal blood plasma, egg white, and protein-containing solutions, among others (Fane et al, 1980;Pham and Pooley, 1981;Pham, 1983;Rashkovskaya et al, 1979;Kutsakova and Utkin, 1983). More recently, reports by Markowski (1992), Reyes et al (1998), Brereton and Lim (1993), Ochoa-Martínez et al (1993), Szentmarjay et al (1996) and Tia et al (1995) who dried a variety of products, ranging from chemicals to liquid foods, have shown the feasibility of the process to obtain good quality dry powdered solids, which make the system, a low-cost, compact alternative to spray drying. Most of these authors have worked with conventional spouted beds, and practically none of them mention any limitations to the system employed.…”

Periodic Fluctuations of Flow and Porosity in Spouted Beds

“…The DTSB were initially developed for the drying of wheat grains (Mathur and Epstein 1974). Nowadays they are used for drying grain agricultural products (Devahastin et al 1998;Kudra et al 2001), dispersed materials (Kmiec and Szafran 2000), paste-like materials on inert bodies (Kudra et al 1989;Arsenijevic et al 2004), slurries and solutions (Tia et al 1995). The SB dryers have also been used for coating particles to obtain products with special properties, such as tablets (Kucharski and Kmiec 1983;Publio and Oliveira 2004).…”