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Folie Nr. 1Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
Biogas Production fromStillage
–Scientific, Technical and
Economical Aspects
Prof. Dr.-Ing. Artur Mennerich, University of Lueneburg
Dipl.-Ing. Adelbert Lühring,pbe energietechnik GmbH
Folie Nr. 2Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
Contents
IntroductionFactors affecting biogas productionLab scale tests for substrate analysis and processcontrolBiogas potential of different substratesFertilizer qualities of biogas plant output
Folie Nr. 3Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
IntroLeuphana-University of Lueneburg
Lower Saxony
Hamburg
Bremen
Hanover
Folie Nr. 4Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
Intro
Leuphana-University of Lueneburg
www.leuphana.de
10,000 students
4 faculties
Campus Suderburg:Campus Suderburg:
500 500 studentsstudents
Labs Labs forfor waterwater and and solidssolids analysisanalysis
Labs Labs forfor biogasbiogas teststests
WaterWater / / WasteWaste WaterWater
Folie Nr. 5Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
Factors affecting biogas production
Substrate composition (and degradability):
• organic. compound (oDS) contains approx. 48% C (Carbon)
• 1 kg Carbon is equivalent to 1,870 liters biogas (CH4 or CO2)
⇒ degradation of 1 kg oDS → approx. 0.48 x 1,870 = 897 liters biogas
degradation ratio = 85 % ⇒ 85 % x 897 l = 762 liters biogas per kg oDS
• Material with a high carbon content may produce more gas, but not unlimited!!
762 m³ / t oDS = appr. 12.1 cu ft per lb oDS
Folie Nr. 6Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
Factors affecting biogas production
Temperature:
80 100 120 140 F
Narrow temp. range
Folie Nr. 7Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
Thermophilic vs. mesophilic digestion
Pro
Higher degradation ratioShorter HRTSmaller reactor volume(appr. 20% based on practical experiences withsewage sludge digestion)
Con
Higher energy demand forheatingNarrow range of optimumoperationDanger of AmmoniatoxicityHigher tear and wear dueto temperature gradients
Folie Nr. 8Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
Factors affecting biogas production
pH:
Optimum for methane production: neutral to slightly alcalinic(7.0 to 7.5)
Problem: Once pH drops below 6.5, methane production mayalready be inhibited severely
Therefore, another method is needed for process control:FOS/TAC-ratio is practiced with good resultsRedox potential may also be useful
Folie Nr. 9Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
Factors affecting biogas production
Toxic gases (NH3, H2S):
Folie Nr. 10Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
Factors affecting biogas production
Toxic gases (NH3, H2S):
Folie Nr. 11Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
VVHRT R=
BR load of reactor (volume) [kg oDS/(m³xd)]
m feed rate [kg oDS/d]
c oDS concentration of feed [%]
VR reactor volume [m³]
HRT hydraulic retention time [d]
VR reactor volume [m³]
V feed flow rate [m³/d]
2. Anaerober Gärprozess
Volumetric loading rate :
Hydraulic retention time :
R
R VcmB ×
=
Factors affecting biogas production
Folie Nr. 12Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
2. Anaerober Gärprozess
Factors affecting biogas production
rye
grass
straw
cow manure
Folie Nr. 13Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
2. Anaerober Gärprozess
Factors affecting biogas production
0
2
4
6
8
10
12
14
16
18
20
0 10 20 30 40 50 60
Verweilzeit (Tage)
oTS-
Rau
mbe
last
ung
[kg
/(m³ u
nd T
ag)]
oTS = 1%oTS = 2%oTS = 5%oTS = 10%oTS = 20%
HRT (days)
Vol
umet
ricLo
adin
gR
ate
[kg
oDS
/(m³x
d)]
Folie Nr. 14Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
Lab scale testsfor substrate analysis and process control
Batch tests:
Folie Nr. 15Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
Lab scale testsfor substrate analysis and process control
Continuous fermenters:
Folie Nr. 16Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
Biogas production from stillageResults of lab tests at the University of Lueneburg:
0
100
200
300
400
500
600
700
800
900
0 5 10 15 20 25
Zeit (d)
spez
. Gas
ertr
ag (m
³N/ t
oTS
)
Whole
Whole
Gas
-gen
erat
ion
(m³/
t O
DS)
hydraulic retention time (d)
Folie Nr. 17Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
Laboratory equipment at the University of Lueneburg:
Chemical lab fully equipped, with respect to biogas:• gas chromatography for biogas analysis• ion chromatography for VFA analysis• simple analysis (DS, oDS, pH, FOS/TAC etc.)• metal analyis (AAS, ICP)
Folie Nr. 18Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
Biogas production from stillage
Results of lab tests at the University of Lueneburg:
Example: 10 mgal per year ethanol plant;
Digestion of 1.5 mgd stillage
Stillage input metric t/d 5146 tons/d 5674
Dry solids content % 12,3 12,3
Dry solids load metric t/d 635 tons/d 700
Biogas production m³/d 414964 million cuft/d 14,7
primary energy content MW 101 Million BTU/h 346
Folie Nr. 19Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
Biogas production from stillageProperties of digested stillage as a fertilizer:
Assumption: 261 t/d digested stillage, dried to a DS content = 95%
No Nitrogen, Phosphorus and Potassium are lost during biogas process
Nitrogen Phosphorus Potassium
N P K
3,46% 1,05% 2,03% on DS basis
15,7 4,8 9,2 g/lb DS
9,89% 3,00% 5,80% onDS basis
44,8 13,6 26,3 g/lb DS
21,9 6,7 12,9 metric t/d
24,2 7,3 14,2 tons/d
48371 14679 28380 lbs/d
Contents in raw stillage
Contents in digested stillage
Daily nutrient load
Folie Nr. 20Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
Biogas production from stillageWhat we can do for you:
Analyses and lab tests for substrate evaluation
Economical evaluation of biogas projects
Technical design and supervision of construction
Support with start up and process optimization based
on on line and lab analysis/tests
Education of and support for operation staff
Folie Nr. 21Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
Process Monitoring, Optimisation
On-site or in central - laboratory Wisconsin
Determination of key process parameter
volatile organic acids
buffer-capacity
ph
dry-solids
Folie Nr. 22Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lühring - pbe energietechnik GmbH
Biogas production from stillage
offers a possibility to make use of the energypotential still present in stillage after ethanolproductionreduces overall process water demandproduces a valuable fertilizer
Thank you for listening!
a.mennerich@uni-lueneburg.de lue@born-ermel.de
Folie Nr. 23Prof. Dr.-Ing. Artur Mennerich, Universität Lüneburg; Dipl. Ing. Adelbert Lührung - pbe energietechnik GmbH
2. Anaerober Gärprozess
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