Title:
Hydrothermal Carbonisation (HTC): Recycling of Process Water.
Author(s):
Stemann, J., Ziegler, F.
Document(s):
Paper
Abstract:
Hydrothermal carbonisation may be an efficient pretreatment process for wet lignocellulosic biomass. However, during the process considerable amounts of organics are dissolved in the liquid phase. Recycling of process water is explored in order to increase process efficiencies. Poplar wood and leaves were treated hydrothermally at 220°C for four hours. For the first experiment de-ionized water was used. After cooling, liquid and solid products were separated mechanically. For the following experiments water from each previous experiment was used - which was repeated 19 times. It was shown that by recycling of process water, organic acids in the liquid phase are concentrated whereas concentrations of reactive components increased less than expected. In the solid phase the carbon content and the HHV increased by 5+/- 1% to 26 MJ/kg and the energetic yield increased by 7+/-4% to 84%. Recycling of process water facilitated mechanical dewatering with a laboratory piston press at 10 MPa reducing the water content to 36+/-2% compared to 45+/-2% when de-ionized water was used. This may be explained by a reduction of functional groups and thus increased hydrophobicity of the char. Ash yields in the solid were 20% and 80% for wood and leaves respectively. For leaves P, N and Ca remained in the solid phase whereas K, Na and Mg rather dissolved in the liquid phase.
Keywords:
energetic yield, dissolution of organics, process efficiency, demineralization
Topic:
Processes for Fuels from Biomass
Subtopic:
Torrefaction and hydrothermal carbonisation
Event:
19th European Biomass Conference and Exhibition
Session:
OC8.2
Pages:
1894 - 1899
ISBN-13:
978-88-89407-55-4
ISBN-10:
88-89407-55-7
Paper DOI:
10.5071/19thEUBCE2011-OC8.2
Price:
FREE
