Pretreatment of recycled paper sludge with a novel high-velocity pilot cyclone: Effect of process parameters on convective drying efficiency

Mäkelä, Mikko; Geladi, Paul; Larsson, Sylvia H.; Finell, Michael

doi:10.1016/j.apenergy.2014.06.057

Cited by 14 publications

(6 citation statements)

References 19 publications

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“…As previously described [24], velocities of inlet and humid air recirculation air flows were derived from pitot tube measurements of differential pressures using the Bernoulli equation [27]: As previously described [24], velocities of inlet and humid air recirculation air flows were derived from pitot tube measurements of differential pressures using the Bernoulli equation [27]:…”

Section: Calculations and Process Modellingmentioning

confidence: 99%

“…The design was composed of three controlled factors: inlet air heating, sludge feeding rate and humid drying air recirculation. Because our previous experiments indicated that the DSC of recycled paper sludge is maximized with a high slit position inside the cyclone [24], this process parameter was kept constant during the experiments. Inlet air heating and sludge feeding rate were varied on five respective levels: 20, 40, 55, 70 and 90°C; and 100, 200, 350, 500 and 600 kg h À1 , as the humid air recirculation valve allowed only three different levels designated as 1 (minimum air recycling), 2 (medium air recirculation) and 3 (maximum air recirculation).…”

Section: Drying Experimentsmentioning

confidence: 99%

“…where Q sh denotes sensible heat in drying air. As previously described [24], velocities of inlet and humid air recirculation air flows were derived from pitot tube measurements of differential pressures using the Bernoulli equation [27]:…”

Section: Calculations and Process Modellingmentioning

confidence: 99%

“…Design of experiments coupled with response surface methodology (RSM) is an economic and accurate method for performing process optimization by providing information on variable relations and determining which variables are critical and at which levels these variables enable optimal operation [19][20][21]. This work reports the use of these methods for optimizing a novel pilot dryer [22][23][24] for the treatment of industrial mixed biosludge.…”

Section: Introductionmentioning

confidence: 99%

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

Mäkelä

Geladi

2015

Int. J. Energy Res.

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Summary 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 (kWh kg−1 H2O) 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 <0.4–1.8 kWh kg−1 H2O 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 <0.7 kWh kg−1 H2O can be performed with inlet air temperatures ≥60 °C corresponding with pilot‐scale feeding capacities between 300–350 and 550 kg h−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 © 2015 John Wiley & Sons, Ltd.

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Section: Calculations and Process Modellingmentioning

confidence: 99%

Section: Drying Experimentsmentioning

confidence: 99%

Section: Calculations and Process Modellingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Mäkelä

Geladi

2015

Int. J. Energy Res.

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“…A special technology for sludge drying is cyclone drying. 14 This method is based on a high velocity cyclone dryer where sludge drying can be performed at low temperatures (<90°C) with a high-capacity fan. The feed material is fed to the inlet air stream, and the air-material suspension is directed to the cyclone where changes in pressure and radial velocity induce water vaporisation and possible particle grinding and separation phenomena.…”

Section: Dryingmentioning

confidence: 99%