ENERGY GENERATION FROM BIO GAS PRODUCED AT STP

ENERGY GENERATION FROM BIO GAS PRODUCED AT STP

A PRESENTATION

ON

GUIDED BY:

Dr A.B. Gupta

Professor

Civil Department

Presented By:

K M Jaiswal

M.Tech. Ist Sem.

ID-2012 PCE5237

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http://civildigital.com/energy-generation-biogas-produced-stp/

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



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 SUSTAININGBY REDUCING GHGs WE CAN EARN CARBON CREDITS



Case studies

(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



POWER GENERATION AT A GLANCE IN WORLD(2009)

Country

Totalelectricitygenerated(GWhE) [1

Electricitygenerated

from sewagebiogas

(GWhE)[3]

Population [1]

Electricityfrom sewage

biogas percapita

(kWhE)

Percent oftotal

electricityfrom sewage

biogas(%)

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

Italy 315,000 20 59,715,600 0.3 0.01



Basics of Anaerobic digestion process Stage of Anaerobic digestionFactors affecting production of MethanePower generation unitsBio gas improvement..\power generation\Biomethane power.pdfScrubberChiller Gas engineHow to increase methaneCase studies to increase Methane quantity(reduction of Hydrogen Sulphide methods in various case studies )

Comments on Delawas Power Plant

Case studies referred



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 CH4 + CO2 +NH3 + Biomass

Anaerobic microorganisms

Anaerobic processes

Anaerobic fermentation Anaerobic respiration

FROM WHERE CH4 COME FROM………?FROM WHERE CH4 COME FROM………?Downloaded from CivilDigital.com


COD Balance Aerobic

Biodegradation

COD Balance Anaerobic

Biodegradation



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



STEPS IN ANAEROBIC DIGESTION

COMPLEX ORGANICS

HIGHER ORGANIC ACIDS

ACETIC ACID

H2 and CO2

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,



COMPLEX ORGANIC MATTERS

Proteins Carbohydrates Lipids

Amino Acids, Sugars Fatty Acids, Alcoholshyd

roly

sis

Acetate Hydrogen, Carbon dioxide

ace

tog

en

esi

s INTERMEDIARY PRODUCTS(C>2; Propionate, Butyrate etc)

aci

dog

en

esi

s

MethaneCarbon dioxide

Overview Anaerobic Biodegradation

methanogenesis



FACTORS AFFECTING CH4 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 )



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. )



BIO GAS PROPERTIES ……………

S.N. Properties of Bio Gas

1 Composition

55-70%methane, 30-45%carbon dioxide, .5 TO 2 % H2S , H2O,NH3

and traces of other gases2 Energy content 6.0-6.5kWm-33 Fuel equivalent 0.6-0.65L oil/m3 biogas4 Explosion limits 6-12%biogas in air5 Lgnition temperature 650-750 ºC6 Critical pressure 75-89 bar7 Critical temperature -82.5 ºC8 Normal density 1.2kgm-3

9 OdourBad eggs (the smell of hydrogen

sulphide)



BIO GAS PROPERTIES……… Methane Carbon dioxide

Formula CH4 CO2Molecular weight 16.043 g/mole 44.010 g/moleMolecular weight 4 Å 5.1-3.5 Å

Density (S.T.P.) 0.7174 kg/m3 1.977 kg/m3Boiling/sublimation

point -161.52°C -78.5°C

Water solubility 20°C 0.035 0.8704



POWER GENERATION FROM BIOGAS PRODUCED ATDELAWAS PLANT

• CAPACITY STP 62.5 MLD UNIT I.

• AMOUNT OF GAS GENERATED FROM ONE 62.5 MLD PLANT : 6000 M3/DAY 250 M3/hr

• CALORIFIC VALUE OF GAS : 5000 TO 5600 KCAL/M3

• TOTAL HEAT ENERGY OF GAS : 1300000 KCAL/hr

• TOTAL ENERGY IN KW HOUR : 1509.3

• EFFICIENCY OF POWER : 28 %GENERATION UNIT INCLUDING ENGINE AND GENERATOR

• ELECTRICAL ENERGY PRODUCTION : 422.60 KWH

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

PLANTION AROUND THE BOUNDRY WALL

FUTURE SPACE FOR 62.5 MLD (II PHASE)

INLET CHEMBER

PLANTION AROUND THE BOUNDRY WALL

COARSE SCREENS

RAW SEWAGE SUMP

LAB& OFFICEBUILDING

UNTREATED SEWAGE FALLING IN NALAH

PRIMRY CLARIFIER

AERATION TANK

SECONDARYCLARIFIER2 NOS.

OUTLET CHEMBER

OUTLET PIPEFOR TREATED WATER

MCC

PMCC CUM CONTROL ROOM

TRANSFORMER2 NOS

BLOWERS

FINE MH SCREENS

GRITSEPERATOR 4 NOS.

ROAD

ROAD

MAIN GATE

PRIMARYSLUDGETHICKNER

DIGESTERS

2 NOS

GAS FLARINGSYSTEM

RETURNSLUDGE SUMP

PRIMARYSLUDGE SUMP

CENTRIFUGE UNIT



Malabar STP process flow diagram ( page 17)



REQUIRED FOR ONE 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.

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Gas Holders at Delawas (Double membrane type)


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


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.


Gas EngineDownloaded 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) DUAL FUEL ENGINEB) GAS TURBINEC) 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.


CAPACITY OF GAS HOLDER

• TOTAL GAS GENERATION : 6000 M3/DAY

• STORAGE CAPACITY IS NORMALLY MAINTAINED : 25 % OF TOTAL IN POWER GENERATION

• STORAGE VOLUME REQUIRED : 1500 M3

• NO OF GAS HOLDER : 2 FOR EACH 62.5 MLD PLANT

• CAPACITY OF EACH GAS HOLDER : 750 M3


• CAPITAL COST : 750 LAKHS

• PER KW RUNNING COST : 3.32/KW hr• PURCHESE COST OF POWER : Rs 6/- KWhr. • PAY BACK PERIOD : 7.5 YEARS


HOW OPTIMISE GAS PRODUCTION AND 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.


THANK YOU

QUESTIONS ?


Overall process of anoxic decomposition, showing the manner in which various groups of fermentative 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 sulfate-reducing 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.


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ENERGY GENERATION FROM BIO GAS PRODUCED AT STP