Response surface optimization of a novel pilot dryer forprocessing mixed forest industry biosludge

Abstract

As a promising sludge handling alternative capable of utilizing the secondary energies in industrial environments, we investigated the use of a novel pilot-scale cyclone dryer for processing industrial mixed sludge from the forest industry. Attainable sludge dry solids contents (%) and respective specific energy consumption of drying (kWhkg(-1)H(2)O) were successfully modelled by response surface methodology based on a constructed design of experiments. Predicted sludge dry solids and the specific energy consumption of drying varied between <30-65% and <0.4-1.8kWhkg(-1)H(2)O depending on controlled inlet air temperature, sludge feeding rate and humid air recirculation levels. The response models were further optimized for efficient combustion of processed sludge with inlet air temperatures corresponding to potentially available secondary heat. According to the results, energy efficient drying of mixed sludge with a specific energy consumption <0.7kWhkg(-1)H(2)O can be performed with inlet air temperatures 60 degrees C corresponding with pilot-scale feeding capacities between 300-350 and 550kgh(-1) depending on inlet air temperature. These findings suggest that the introduction of novel drying systems capable of utilizing the available secondary energies of industrial environments could significantly improve the energy efficiency of sludge drying and potentially allow considerable cost savings for industrial operators. Copyright (c) 2015 John Wiley & Sons, Ltd.

Keywords

biosolids; cyclone; drying; experimental design; optimization; response model; secondary energy

Published in

International Journal of Energy Research
2015, volume: 39, number: 12, pages: 1636-1648

SLU Authors

• Mäkelä, Mikko

  • Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences
    

• Geladi, Paul

  • Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences
    

Global goals (SDG)

SDG7 Affordable and clean energy

UKÄ Subject classification

Energy Systems
Chemical Process Engineering
Energy Engineering

Publication identifier

• DOI: https://doi.org/10.1002/er.3367

Permanent link to this page (URI)

https://res.slu.se/id/publ/68411