- #1
Sesha
- 5
- 0
- TL;DR Summary
- Drying of liquid digestate inside a drum dryer packed with cooling tower fills leads to deposition of tiny fibres on the fill material and clogging of air flow. Looking for new ideas to improve the contact surface area between the liquid digestate and hot air inside the drum dryer.
I am working on a project to dry liquid digestates (residue from the fermentation process of biogas plants).
The liquid digestate has a dry matter (DM) content of about 3%. The digestate is primarily made up of animal manure and maize silage. It is a non-Newtonian fluid having a viscosity of 4 - 15 mPa-s. It exhibits a shear thinning behaviour, where the viscosity decreases with shear rate.
The liquid digestate at a temperature of 40°C is fed into a drum dryer. Hot air with a temperature of 70°C is blown into the drum to dry the digestate. The drum is packed with cooling tower fills (see image Packed fills) in order to facilitate faster drying by increasing the heat transfer surface area between digestate and air.
The problem is that the tiny fibres from the liquid digestate gets deposited on the cooling tower fills (see image Fibre Deposition) and the clog the air flow. Thereby the whole functioning of the dryer is affected. These tiny fibres are suspended and float in the liquid digestate, as it is difficult to filter them out.
Hence, I would like to know, if heating the liquid digestate helps? What happens to these tiny floating fibres in the liquid, when the temperature is raised from 40°C to 60°C? Definitely the viscosity of the liquid would decrease, but does it affect these tiny fibres?
How can this fibre deposition and clogging of flow be avioded? Are there better methods to increase the heat transfer area, other than cooling tower fills? Any new suggestions are welcome.
Thank you.
The liquid digestate has a dry matter (DM) content of about 3%. The digestate is primarily made up of animal manure and maize silage. It is a non-Newtonian fluid having a viscosity of 4 - 15 mPa-s. It exhibits a shear thinning behaviour, where the viscosity decreases with shear rate.
The liquid digestate at a temperature of 40°C is fed into a drum dryer. Hot air with a temperature of 70°C is blown into the drum to dry the digestate. The drum is packed with cooling tower fills (see image Packed fills) in order to facilitate faster drying by increasing the heat transfer surface area between digestate and air.
The problem is that the tiny fibres from the liquid digestate gets deposited on the cooling tower fills (see image Fibre Deposition) and the clog the air flow. Thereby the whole functioning of the dryer is affected. These tiny fibres are suspended and float in the liquid digestate, as it is difficult to filter them out.
Hence, I would like to know, if heating the liquid digestate helps? What happens to these tiny floating fibres in the liquid, when the temperature is raised from 40°C to 60°C? Definitely the viscosity of the liquid would decrease, but does it affect these tiny fibres?
How can this fibre deposition and clogging of flow be avioded? Are there better methods to increase the heat transfer area, other than cooling tower fills? Any new suggestions are welcome.
Thank you.