Future sludge treatment: Hydrothermal Carbonisation (HTC)

Transcription

1 NEST - HTC Future sludge treatment: Hydrothermal Carbonisation (HTC) Lübeck,

2 Future sludge treatment Processing of wet biomass Hydrothermal Conversion (HTC) Coal Petrology Products and properties of HTC Recovery of nutrients Technical implementation CO 2 Sequestration Potential of HTC

3 Processing of wet biomass Fermentation Digestion Hydrothermal liquefaction (Btl) Hydrothermal carbonisation Hydrothermal gasification Gas Alcohols Oils Chars Hydrothermal extraction Proteins, sugars, etc. Functional carbonaceus materials

4 Hydrothermal Carbonisation (HTC) HTC can be defined as combined dehydration and decarboxylation of a Biomass to raise its carbon content with the aim of achieving a higher calorific value C 6 H 12 O 6 C 6 H 2 O + 5 H 2 O + Energy Early patents can be traced back to 1850: wet carbonization of peat as a method for dewatering It is known that char can be produced through dewatering of peat The following range of operational conditions are known Elevated temperature C Steam saturated pressure The ph-value of the feed should be below 7 process times vary between 1 and 72 h The carbon is retained Funke, A. et al. Hydrothermal Carbonization of Biomass. Biofuels, Bioprod. & Biorefining. (2010)

5

6 Products of HTC Funke, A. et al. Hydrothermal Carbonization of Biomass. Biofuels, Bioprod. & Biorefining. (2010)

7 Products of HTC Feedstock properties relevant to thermal conversion processes Feedstock Woods Grasses Manure s Sewage Sludge Municipal solid waste Primary Digested Volatile fraction [%] dw Ash [%] dw 0,1-8 1,4-6, Moisture content [%] Energy content [MJ / kg] dw NR dw: dry weight Libra, J.A. et al. Hydrothermal Carbonization of Biomass residuals. Biofuels, Bioprod. & Biorefining. (2011)

8 Recovery of nutrients When utilizing (waste) biomass, the recovery of nutrients can possibly be incorporated in the processes The main focus is on the recovery of phosphorus because of the limited availability worldwide There is potential for nitrogen recovery Different options Pericipitation in Magnesium Ammonium Phosphate (MAP) The hydrochar can be charged with nutrients There is still a lot researchwork to be done on this subject

9 Recovery of nutrients Hydrochar MAP

10 Technical Implementation Operation with elevated pressure requires feeding against pressure, which need costly technical equipement For economic process a heat recovery from the hot process water is inevitable The HTC improves the dewatering capacity to a great extent, but still a Post-treatment is needed A facility for the treatment of process water is needed HTC seem to have potential for efficient small scale plants The logistics of the feed and The logistics of the dewatered and stable product need to be planned

11 Terra Preta In the recent years there has been intensive international research activities of the ancient Terra Preta soils in Amazonia The Terra Preta soils are over 2000 years old -- archeology They have remained fertile over the centuries Terra Preta contains Very high organics High amounts of nutrients High water holding capacity ph is close to 7 Several international research projects are constructing soils with qualities of Terra Preta Biochar is one element of these soils

12 CO 2 Sequestration Woolf, D. et al. Sustainable biochar to mitigate global climate change. Nat. Commun. (2010)

13 Potential of HTC The first plants for HTC are built operating Small scale applications Thermal potential Hydrochar with high calorific value (14 24 MJ / kg) Dry solids (DS) concentations of 80% are easily achieved CO 2 -sequestration potential Hydrochar can improve the soil (Terra Preta) Char will not be degraded (?) Additional CO 2 -sequestration through stronger growth Elimination of the PPCPs Integration with nutrients recovery N-P-K Charged (N-P-K) chars have small leaching potential

14 Thank You!