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

Mikko Mäkelä*, Paul Geladi

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

6 Citations (Scopus)

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-1H2O) 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-1H2O 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-1H2O can be performed with inlet air temperatures ≥60°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.

Original languageEnglish
Pages (from-to)1636-1648
Number of pages13
JournalInternational Journal of Energy Research
Volume39
Issue number12
DOIs
Publication statusPublished - 1 Jan 2015
MoE publication typeA1 Journal article-refereed

Keywords

  • Biosolids
  • Cyclone
  • Drying
  • Experimental design
  • Optimization
  • Response model
  • Secondary energy

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