A
PRESENTATION
Downloaded from CivilDigital.com
ON
ENERGY GENERATION FROM BIO GAS PRODUCED AT STP
GUIDED BY:
Presented By:
Dr A.B. Gupta
K M Jaiswal
Professor
M.Tech. Ist Sem.
Civil Department
ID-2012 PCE5237
Downloaded from CivilDigital.com
Excreta and wastewater sludge are resources. Finding
ways to put them to their best uses is part of developing
sustainable technologies.
At the same time, excreta and wastewater sludge – if not
managed properly – can be dangerous to human health
and the environment.
Source :-GLOBAL ATLAS OF EXCRETA, WASTEWATER SLUDGE, AND BIOSOLIDS
MAGEMENT: UN-HABITAT
Downloaded from CivilDigital.com
WE CAN GENERATE ELECTRICITY AT PLANT, RUN IC ENGINES
AND USE AS FUEL BY BOTTLING THE BIO GAS PRODUCED AT
STP DURING ANAEROBIC DIGESTION OF WASTE WATER,
WHICH OTHERWISE CAN BE HARMFUL FOR ENVIRONMENT IF
ALLOWED TO ESCAPE IN ATMOSPHERE.
BY DOING THIS WE CAN SAVE ELECTRICITY BILL OF STP
THERE BY MAKING THEM SULF SUSTAINING
BY REDUCING GHGs WE CAN EARN CARBON CREDITS
Case studies
Downloaded from CivilDigital.com
(1) 2 62.5 MLD Capacity DELWAS STP
in JAIPUR
(2) Welissa Farms -- Bantayan, Cebu
(3) Anaerobic co-digestion of sewage and brewery sludge for
biogas :Thammasat University, Thailand
(4) Biogas from Sewage Treatment used to
Energy Generation, by a 30 kW (ISO) Micro turbine
(5) Bio Gas Production In Indian Perspective
(6)Power Generation from gases at STP(Germany)
(7)Some case studies to reduce H2s and increase CH4
contents in Bio Gas
Downloaded from CivilDigital.com
POWER GENERATION AT A GLANCE IN WORLD(2009)
Country
Total
electricity
generated
(GWhE) [1
Electricity
generated
from sewage
biogas
(GWhE)
[3]
Electricity
from sewage
biogas per
capita
(kWhE)
Percent of
total
electricity
from sewage
biogas
(%)
Population [1]
Luxembourg
6,500
6
497,500
12.1
0.09
United States
345,000
638
60,587,000
10.5
0.18
Netherlands
124,000
150
16,639,800
9
0.12
Czech Republic
62,000
83
10,256,700
8.1
0.13
United States
3,873,000
2,400
310,232,800
7.7
0.06
Denmark
34,300
38
5,515,500
6.8
0.11
Australia
222,000
125
21,515,000
5.8
0.06
Austria
68,300
39
8,214,100
4.7
0.06
Poland
129,300
123
38,463,700
3.2
0.1
Sweden
134,500
19
9,074,100
2.1
0.01
France
447,000
45
63,601,000
0.7
0.01
Downloaded from CivilDigital.com
Basics of Anaerobic digestion process
Stage of Anaerobic digestion
Factors affecting production of Methane
Power generation units
Bio gas improvement..\power generation\Biomethane
power.pdf
Scrubber
Chiller
Gas engine
How to increase methane
Case studies to increase Methane quantity
(reduction of Hydrogen Sulphide methods in various
case studies )
Case studies referred
Comments on Delawas Power Plant
Downloaded from CivilDigital.com
FROM WHERE CH4 COME FROM………?
During Anaerobic treatment process of sewage (carried out in the
absence of O2) for the stabilization of organic materials CH4 ,CO2,
NH3, H2O, H2S are end product .
Organic materials + Nutrients
Anaerobic microorganisms
CH4 + CO2 +NH3 + Biomass
Anaerobic processes
Anaerobic fermentation
Anaerobic respiration
Downloaded from CivilDigital.com
COD Balance
Aerobic
Biodegradation
COD Balance
Anaerobic
Biodegradation
Downloaded from CivilDigital.com
Anaerobic digester microbiology
1: Extracellular hydrolysis (e.g. cellulose)
(page 1)
(
2: Fermentation leading to organic acids (VFAs),
acetate, CO2 and H2
(page 7-8)
3: Fermentation leading to acetic acid (CH3COOH),
H2 and O2
4: Methanogenesis leading to CH4,CO2 and H2O
Downloaded from CivilDigital.com
STEPS IN ANAEROBIC DIGESTION
H2 and CO2
COMPLEX
ORGANICS
HIGHER
ORGANIC
ACIDS
CH4
Insoluble organic material and high molecular
weight compounds (lipids, polysaccharides,
proteins and nucleic acids) into soluble
organic substances e.g. amino acids and fatty
acids .Further split during acidogenesis,
ACETIC ACID
Overview Anaerobic Biodegradation
Downloaded from CivilDigital.com
hydrolysis
Carbohydrates
Proteins
Lipids
Amino Acids, Sugars
Fatty Acids, Alcohols
INTERMEDIARY PRODUCTS
(C>2; Propionate, Butyrate etc)
acetogenesis
methanogenesis
acidogenesis
COMPLEX ORGANIC MATTERS
Acetate
Hydrogen, Carbon dioxide
Methane
Carbon dioxide
FACTORS AFFECTING
CH4
Downloaded
from CivilDigital.com
PRODUCTION IN ASD
• PH (6.6 TO 7.6) (page 11)
• NUTRIENTS AVAILABLITY.
• TEMPERATURE (35C TO 55 C) (Page 10)
• SOLIDS RETENTION TIME (SRT), (Page 8-9)
•
VOLATILE FATTY ACIDS (VFA) (page 12,18 -23)
• MIXING OF SLUDGE
• TOXIC AND INHIBITORY COMPOUNDS ( viz sulphide, light metal
cations, ammonia, and heavy metals )
Downloaded from CivilDigital.com
FACTORS AFFECTING CH4 PRODUCTION IN ASD ……...
• PRE-TREATMENT PRIOR TO ANAEROBIC DIGESTION : (During
•
hydrolysis, cell walls are ruptured and extracellular polymeric substances are degraded resulting in the release of readily
available organic material for the acidogenic micro-organisms. By means of efficient pre-treatment ,the suspended substrate
can be made more accessible for the anaerobic bacteria, optimizing the methanogenic potential of the waste to be treated.
Various sludge disintegration pre-treatment: include mechanical grinding, ultrasonic disintegration, chemical methods,
thermal pre-treatment, enzymatic and microbial pre-treatments. )
Downloaded from CivilDigital.com
BIO GAS PROPERTIES ……………
S.N.
1
2
3
4
5
6
7
8
9
Properties of Bio Gas
55-70%methane, 30-45%carbon
dioxide, .5 TO 2 % H2S , H2O,NH3
Composition
and traces of other gases
Energy content
6.0-6.5kWm-3
Fuel equivalent
0.6-0.65L oil/m3 biogas
Explosion limits
6-12%biogas in air
Lgnition temperature
650-750 ºC
Critical pressure
75-89 bar
Critical temperature
-82.5 ºC
Normal density
1.2kgm-3
Bad eggs (the smell of hydrogen
Odour
sulphide)
BIO GAS PROPERTIES………
Formula
Molecular weight
Molecular weight
Density (S.T.P.)
Boiling/sublimation
point
Water solubility 20°C
Downloaded from CivilDigital.com
Methane
CH4
16.043 g/mole
4Å
0.7174 kg/m3
Carbon dioxide
CO2
44.010 g/mole
5.1-3.5 Å
1.977 kg/m3
-161.52°C
-78.5°C
0.035
0.8704
Downloaded
from CivilDigital.com
POWER GENERATION FROM BIOGAS
PRODUCED
AT
DELAWAS PLANT
•
CAPACITY STP
•
AMOUNT OF GAS GENERATED
FROM ONE 62.5 MLD PLANT
62.5 MLD UNIT I.
: 6000 M3/DAY 250 M3/hr
•
CALORIFIC VALUE OF GAS
•
TOTAL HEAT ENERGY OF GAS
: 1300000 KCAL/hr
•
TOTAL ENERGY IN KW HOUR
: 1509.3
•
EFFICIENCY OF POWER
GENERATION UNIT INCLUDING
ENGINE AND GENERATOR
: 28 %
•
ELECTRICAL ENERGY PRODUCTION
: 422.60 KWH
: 5000 TO 5600 KCAL/M3
EXISTING PLANT PRODUCING BIO GAS CONTINUOUSLY AND EXCESS GAS IS FLARED.
Data made available from Delawas plant
LAYOUT OF 62.5 MLD STP AT DELAWAS
Downloaded from CivilDigital.com
MAIN GATE
PLANTION AROUND THE BOUNDRY WALL
FUTURE SPACE FOR 62.5 MLD (II PHASE)
ROAD
GRIT
SEPERATOR
MCC
4 NOS.
COARSE SCREENS
INLET CHEMBER
LAB& OFFICE
BUILDING
RAW SEWAGE
SUMP
FINE MH
SCREENS
PLANTION AROUND
THE BOUNDRY WALL
PRIMARY
SLUDGE SUMP
GAS
FLARING
TRANSFORMER
SYSTEM
2 NOS
PRIMARY
ROAD
SLUDGE
BLOWERS
THICKNER
PMCC CUM
CONTROL ROOM
SECONDARY
AERATION
DIGESTERS
CLARIFIER
TANK
2 NOS.
2 NOS
RETURN
PRIMRY
SLUDGE SUMP
CLARIFIER
UNTREATED SEWAGE
FALLING IN NALAH
OUTLET PIPE
FOR TREATED
WATER
OUTLET
CHEMBER CENTRIFUGE
UNIT
Downloaded from CivilDigital.com
Malabar STP process flow diagram ( page 17)
REQUIRED FOR ONE
Downloaded from CivilDigital.com
Downloaded from CivilDigital.com
ENGINE
•
UNITS REQUIRED FOR POWER GENERATION SYSTEM
•
GAS HOLDER
•
INTER CONNECTING PIPING
•
GAS ENGINES
•
GAS SCRUBBER FOR REMOVAL OF H2 S (By NaOH at Delawas)
•
CHILLER UNIT : To remove moisture from gas coming gas from the Scrubber through the
Blower, by cooling the gas to low temperature by condensing the moisture. A shell and tube type
Heat Exchanger will be used for this purpose.
Downloaded from CivilDigital.com
Gas Holders at Delawas
(Double membrane type)
Downloaded from CivilDigital.com
H2S Scrubber
Downloaded from CivilDigital.com
Biogas upgrading (H2S Scrubbing)
H2S Removal is needed to
• reduce air pollution As it is toxic and odorous
and gives sulfur dioxide on burning
• protect power generation equipment from
corrosion
• increase safety of the operations
Downloaded from CivilDigital.com
How to minimize H2S in bio Gas
1. By reducing H2S by Process Control
(a) bio scrubber; bio filter; and bio trickling filter.( H2s is absorbed by Chemotrophic bacteria and elemental sulfur is produced)
•
2. By Scrubbing, carbon adsorption, and chemical and thermal (page 2)
• Oxidation from Bio Gas
Scrubing is being done at DelawasUsing NaoH
•
•
•
•
H2S gets absorbed in water,
The gas from the bottom of the Scrubber enters the packed Column while liquid is collected in the
Tank for recalculation.
In the II stage of scrubbing, gas is scrubbed with caustic solution in a packed Column. The Column is
provided with ceramic rings to have enhanced surface area for mass transfer. This is a counter
current scrubber and provides high scrubbing efficiency.
caustic solution ensures effective reaction of H2S and CO2 and their removal.
Downloaded from CivilDigital.com
Gas Engine
Downloaded from CivilDigital.com
Flaring of excess Gas
Downloaded from CivilDigital.com
SELECTION OF TYPE OF ENGINE
POWER CAN BE GENERATED FROM BIO GAS FROM
FOLLOWING MACHINES.
A)
B)
C)
DUAL FUEL ENGINE
GAS TURBINE
GAS ENGINE
•
GAS ENGINE IS MOST SUITABLE AND EFFICIENT FOR PRESENT APPLICATION.
•
AMONG THE THREE TYPES OF ENGINE GAS TURBINE IS NOT USED FOR BIO GAS
FUEL SINCE IT IS NOT SUITABLE FOR LOW CAPACITY.
•
DUAL FUEL ENGINE IS USED IN REMOTE AREA WHERE NORMAL POWER SUPPLY IS
NOT AVAILABLE OR ERRATIC. THIS ENGINE CAN BE RUN EITHER WITH DIESEL OR
WITH BIOGAS & DIESEL COMBINATION.
•
DUAL FUELENGINE NEEDS MORE MAINTENANCE AND DIESEL STORAGE.
Downloaded from CivilDigital.com
CAPACITY OF GAS HOLDER
•
TOTAL GAS GENERATION
:
6000 M3/DAY
•
STORAGE CAPACITY IS
NORMALLY MAINTAINED
IN POWER GENERATION
:
25 % OF TOTAL
•
STORAGE VOLUME REQUIRED
:
1500 M3
•
NO OF GAS HOLDER
PLANT
:
2 FOR EACH 62.5 MLD
•
CAPACITY OF EACH GAS HOLDER
:
750 M3
Downloaded from CivilDigital.com
•
CAPITAL COST
:
750 LAKHS
•
•
•
PER KW RUNNING COST
PURCHESE COST OF POWER
PAY BACK PERIOD
:
:
:
3.32/KW hr
Rs 6/- KWhr.
7.5 YEARS
HOW OPTIMISE GAS PRODUCTION
Downloaded fromAND
CivilDigital.com
OPTIMUM USE OF ENERGY AT STPs
•
•
•
•
•
•
•
BY EFECTIVE CONTROL OF PROCESS
AMONIA STRIPPING
THERMAL PRETREATMENT OF SLUDGE BY UTILIZING HEAT OF
EXHAUST GASES
SCUM AND GREASE CAN BE FED IN DIGESTER
USE THERMOPHILIC STAGE FOR MORE GAS PRODUCTION BUT THIS
NEED EFFECTIVE CONTROL
BIOLOGICAL REMOVAL OF SULPHER SO THAT H2S PRODUCTION CAN
BE MINIMISED
IN WINTER DUE TO LOW ATMOSPHERIC TEMPERATURE GAS
GENERATION IN DIGESTER IS REDUCED.
OTHER COST EFFECTIVE TECHNOLOGIES CAN BE USED TO REDUCE
HYDROLYSIS TIME AND OVER ALL SRT OF ANAEROBIC PROCESS,
MINIMIZATION OF TOXICANTS AND INHIBITION FACTORS TO
INCREASE QUALITY AND QUANTITY OF BIO GAS.
Downloaded from CivilDigital.com
THANK YOU
QUESTIONS ?
Overall process of anoxic decomposition, showing the
manner in which various groups of fermentative
Downloaded
from CivilDigital.com
anaerobes cooperate
in the conversion
of complex
organic materials ultimately to methane 1 CH42 and
CO2. Acetate and H2 + CO2 from primary
fermentations can be directly converted to methane,
although H2 + CO2 can also be consumed by
homoacetogens. But note how the syntrophs play a
key role in anoxic decomposition by consuming highly
reduced fermentation products in a secondary
fermentation. By activities of the
syntrophs, fatty acids and alcohols are converted to the
substrates for methanogenesis and acetogenesis. This
picture holds for environments in which sulfatereducing bacteria play only a minor role, for example,
in freshwater lake sediments, sewage sludge
bioreactors, or the rumen. If alternative electron
acceptors are abundant, as for example, sulfate in
marine sediments, anaerobic respiration prevails, as
syntrophs cannot compete for fatty acids/alcohols with
sulfate-reducing bacteria or bacteria carrying out other
forms of anaerobic respiration.