The Effect of Using a Heating Tube in an Existing Spouted Bed Superheated Steam Dryer

Interest in the use of biofuels, such as pellets and briquettes, has continued to grow in the European market in recent years. In order to manage the increased use of biofuels, the dryer capacity must also increase. One possible way of accomplishing this is to install heating tubes into the already existing dryers. Therefore, industrially relevant and appropriate design data, such as energy efficiency and a possible increase in the capacity of developing drying systems, are needed. This article presents the experimental results obtained from drying sawdust in a continuous spouted bed using a heating tube submerged in the bed; the results are compared with those obtained from a bed without using a heating tube. Superheated steam is used as the drying gas in all tests. The drying test is performed with an almost constant inlet moisture content and at three different inlet and outlet temperatures. The drying efficiency increases when the heating tube is turned on. Some explanations of the relation between inlet and outlet gas temperature and moisture content are presented.

[1]  V. Vanec̆ĕk,et al.  Fluidized bed drying , 1966 .

[2]  Roland Wimmerstedt,et al.  Recent advances in biofuel drying , 1999 .

[3]  R. Renström.  Mean Residence Time and Residence Time Distribution When Sawdust Is Dried in Continuous Dryers , 2008 .

[4]  Jonas Berghel.  The Gas-to-Particle Heat Transfer and Hydrodynamics in Spouted Bed Drying of Sawdust , 2005 .

[5]  Magnus Ståhl,et al.  Validation of a Mathematical Model by Studying the Effects of Recirculation of Drying Gases , 2008 .

[6]  Alejandro Reyes,et al.  Drying Sawdust in a Pulsed Fluidized Bed , 2008 .

[7]  Arun S. Mujumdar,et al.  SLUDGE DEWATERING AND DRYING , 2002 .

[8]  Rogelio Moreno,et al.  SAWDUST FLUID-BED DRYING WITH HEATING TUBES , 1998 .

[9]  A. Mujumdar,et al.  Drying of a Dilute Suspension in a Revolving Flow Fluidized Bed of Inert Particles , 2004 .

[10]  Jonas Berghel,et al.  USEFULNESS AND SIGNIFICANCE OF ENERGY AND MASS BALANCES OF A FLUIDIZED SUPERHEATED STEAM DRYER , 2001 .

[11]  Jonas Berghel,et al.  DRYING OF SAWDUST IN AN ATMOSPHERIC PRESSURE SPOUTED BED STEAM DRYER , 2002 .

[12]  A. Mujumdar,et al.  Advanced drying technologies , 2001 .

[13]  R. Ríos,et al.  PH—Postharvest Technology: Study on Sawdust Drying Techniques in Fluidised Bed , 2002 .

[14]  Arun S. Mujumdar,et al.  Fluidized bed drying , 2006 .

[15]  Jonas Berghel,et al.  Usefulness and significance of energy and mass balances of a superheated steam dryer , 2001 .

[16]  Javier Bilbao,et al.  Hydrodynamics of sawdust and mixtures of wood residues in conical spouted beds , 1994 .

[17]  Jonas Berghel,et al.  Controllability of Product Moisture Content When Nonscreened Sawdust Is Dried in a Spouted Bed , 2004 .

[18]  R. Moreno,et al.  BATCH VIBRATING FLUID BED DRYER FOR SAWDUST PARTICLES: EXPERIMENTAL RESULTS , 2000 .

[19]  Arne Sloth Jensen.  Industrial Experience in Pressurized Steam Drying of Beet Pulp, Sewage Sludge and Wood Chips. , 1995 .

[20]  Roland Wimmerstedt,et al.  Steam Drying — History and Future , 1994 .

[21]  Roger Renström.  The potential of improvements in the energy systems of sawmills when coupled dryers are used for drying of wood fuels and wood products , 2006 .

[22]  Jonas Berghel,et al.  Basic design criteria and corresponding results performance of a pilot-scale fluidized superheated atmospheric condition steam dryer , 2002 .

[23]  H. A. Becker,et al.  Drying wheat in a spouted bed: On the continuous, moisture diffusion controlled drying of solid particles in a well-mixed, isothermal bed , 1961 .

[24]  T. Kudra,et al.  DRYING OF POWDERY MATERIALS IN A PULSED FLUID BED DRYER , 1999 .