FLUIDIZED BED GASIFICATION OF GARDEN

WASTES

BATCH : B12

S.VISHNURAJA 80106114047G.RAJARAJAN 80106114308G.SATHEESHKUMAR 80106114310S.SURESHKUMAR 80106114314

Under the Guidance of

Mr.S.VIJAJARAJ M.E.,(Ph.D.,)Asst.PROF.ESSOR, Dept of Mech

STATEMENT ABOUT PROBLEM

Generally garden waste (crushed leafs) are bio degradable, they are digested in soil without any energy conversion

The garden waste are highly available in nature The garden waste contain some amount of energy we should

burn to obtain it Our proposed idea will reduce some amount of present fuel

demand

OBJECTIVE

To utilize the agricultural waste from paddy fields like paddy straw for synthetic gas production to replace the conventional energy requirements.

To satisfy the growing energy demand

To control the CO2 emission

PROCESS

Segregating and Chopping the dried leafs from garden waste and crushing the leafs into fine particles

The crushed particle are fed into the FBG and it is gasified Air is being supplied from the other side of FBG with the

controlled valve. This is done by using a blower which supplies the required air

A amount air supplied can be varied by adjusting the valve attached blower

The gasification is controlled effectively by variation in the air supply

The combusted gas is being sent to the cyclone separator where it is purified.

INTRODUCTION

Coal is an oldest fuel and still used on large scale throughout world for power generation. Most of the power industries are shifted from oil to coal. But the availability of coal is limited amount.

So there is a need for non-conventional energy sources to over come this energy demand.

Fuel Availability

Consumption

Coal

Oil

Natural gas

80,950 million tons

1100 billion tons

350 billion tons

200 million tons/year

40 million tons/year

14 million tons/year

Bio-mass Bio mass is a organic matter produced by plants, both in land

and water. It includes forest crops and animal manure. It is an alternative source of energy in our country. It is the solar energy stored by the way of photosynthesis

Solar energy

Photosynthesis

Bio-mass

Energy generation

Method of obtaining biomass

Method of obtaining energy from BIO-MASS

combustion

Thermo chemical Combustion1.Gasification2.liquification

Bio-chemicalCombustion

1.Anerobicdigestion2.Fermentation

Gasification: Gasification is a process that convert carbonaceous material such as coal, petroleum, biofuel or biomass, into carbon-monoxide and hydrogen by reacting the raw material such as house waste or compost at high temperature with the controlled amount of O2 and stream. The resulting gas mixture is called synthesis gas.

THEORY OF GASIFICATION:

The production of generator gas (producer gas) called gasification, is partial combustion of solid fuel (biomass) and takes place at temperature of about 1000˚C. The reactor is called a gasifier.

The combustion products from complete combustion of bio mass generally contain nitrogen water vapor, carbon dioxide and surplus of oxygen. However in gasification where is a surplus of solid fuel (incomplete combustion) the products of combustion are combustible gases like carbon monoxide (CO), hydrogen (H2), and traces of methane and non useful products like tar and dust

Gasification PrincipleIn principle, gasification is the thermal

decomposition of organic matter in an oxygen deficient atmosphere producing a gas composition containing combustible gases, liquids and tars, charcoal, and air, or inert fluidizing gases.

Typically, the term "gasification" refers to the production of gaseous components, whereas pyrolysis, or pyrolization, is used to describe the production of liquid residues and charcoal. The latter, normally, occurs in the total absence of oxygen, while most gasification reactions

take place in an oxygen-starved environment.

Fluidized bed gasifier

INERT MATERIAL USED IN THE FBG SYSTEM

1.Sand 2.Lime stone or dolomite 3.Fused alumina and 4.Sintered ash

 

In the fluidised bed combustor the paddy straw is being burnt which is stocked from feed stock.

Air is being supplied from the other side of FBC with the controlled valve. This is done by using a blower which supplies the required air A amount air supplied can be varied by adjusting the valve attached blower The gasification is controlled effectively by variation in the air supply The combusted gas is being sent to the cyclone separator where it purified.

Cyclone separator It is a mechanical type of dust collector a high velocity gas stream carrying the dust particles enters at high velocity and tangential-to the conical cell

This produces a whirling motion of the gas within the chamber and throws heavier dust particles to the sides and fall out of gas stream and collected at the bottom of the collector.

Data Needed to Design the System

The ultimate analysis of fuel The proximate analysis of fuel Bed material characteristics

Size distribution of particles Porosity of the material Density of the materials Sphericity of the particle

Paddy straw is choosen as a fuel for designing a system the to choose the paddy straw is ash fusion temperature of paddy straw is high and so there is no risk of clinger formation in the bed.

Design Steps

Calculation of fuel feed Rate

Calculation of reactor dimensions Design of distributor plate

Calculation of minimum fluidization velocity

Design of duct

Design of blower

PROXIMATE

ANALYSIS

BIOMASS FUELS

NEEM LEAF BASSIA

LONGFONIA

GRASS

POWDER

Moisture % 10.33 9.01 8.41

Ash % 7.17 8.86 7.86

Volatile matter % 63.48 59.78 66.38

Fixed carbon % 19.02 22.35 17.35

Gross calorific

value in Kcals/kg

5610 5094 4698

ULTIMATE ANALYSIS BIOMASS FUELS

NEEM LEAF BASSIA LONGFONIA GRASS

POWDER

Moisture % 10.33 9.01 8.41

Mineral matter % 7.89 9.75 8.65

Carbon % 73.96 72.40 73.32

Hydrogen % 5.82 5.66 6.13

Nitrogen % 0.34 0.52 0.33

% 0.03 0.11 0.04

Oxygen by difference % 1.63 2.55 3.12

DESIGN OF FLUE GAS DUCT:

Temperature=650˚C

Amount of gas formed=fuel+air-ash = 8+6-0.199 =13.801 Kg/Kg of fuel

Exhaust Gas density =0.2279 Kg/m3

Q= 13.801/0.2279=60.55 m3/hr

CYCLONE SEPARATOR DESIGN STEPSGENERAL PURPOSE FLAT TOP DESIGNCALCULATE INLET AREAA=Q/CV CALCULATE INLET DIAMETERD=√(A/Π)BODY DIAMETER= INLET DIAMETER×4BODY HEIGHT= INLET DIAMETER×2.33CONE HEIGHT= INLET DIAMETER×4 CLEAN AIR OUTLET DIAMETER=INLET DIAMETER×2WELL LENGTH=BODY HEIGHT

CYCLONE SEPARATOR 1:Inlet area AWhere d=diameter of exhaust duct = 0.0508 mInlet area A = 2.0268*10-3 m2

Inlet diameter D = 0.0508 mBody diameter =D*4 = 0.20316 mBody height = D*2.33 = 0.1183 mCone height = D*4 = 0.20316 mClean gas outlet diameter = D*2 = 0.1016 m

CYCLONE SEPARATOR 2:Inlet area AWhere d=diameter of exhaust duct = 0.1016 mmInlet area A = 2.0268*10-3 m2

Inlet diameter D = 0.1016 mBody diameter =D*4 = 0.4064 mBody height = D*2.33 = 0.9469 mCone height = D*4 = 0.4064 mClean gas outlet diameter = D*2 = 0.2032 m

THE DESIGN STEPS:CALCULATION OF FUEL FEED RATE:

Stoichiometric air required for gasification

=100/23(8/3*C+8*H2+S -O2 )=100/23((8/3*0.39) + (8*0.048)+(1*10-3 -0.34 ))

=5 Kg of air/Kg of PS

CALCULATION OF ACTUAL AIR REQUIREDGasification is conducted at the obtained minimum fluidization velocity of 0.95 m/sFor ER=0.15 ER =Actual air required per kg=ER* stoichoimetric air required

=0.15*10.51=1.57 kg/hr

Volume flow rate of air Cd=0.63D=16.2mm Volume = Area*3600*Vf

=0.0144*3600*0.952=49.37 m3/hr

Mass=volume* density; at 40º C=49.37×1.125

Mass air supplied =55.54 kg/hrMass of fuel gasified = 55.54/1.57= 35.37 kg/hr

NEEM LEAF FUEL CALCULATION:CALCULATION OF FUEL FEED RATEStoichiometric air required for gasification

=10.51 kg/kg of air

Volume flow rate of air Cd=0.63 where d=16.2mm

Volume = Area*3600*Vf

=0.0144*3600*0.952=49.37 m3/hr

Mass=volume* density; at 40º C=49.37×1.125

Mass of air supplied =55.54 kg/hr

MASS FLOW RATE AND AIR FUEL RATE OF NEEM

FLUIDIZATION RATIO

VELOCITY

EQULIZATION RATIO- ER

0.15 0.30

0.952Mass of fuel 35.37kg/hr Mass of fuel 17.63kg/hrMass of air 55.54 kg/hr Mass of air 55.54 kg/hr

MASS FLOW RATE AND AIR FUEL RATE OF MAHUVA AND GRASS

FLUIDIZATION RATIO- FR

EQULIZATION RATIO- ER

0.15 0.30

0.952Mass of fuel 36.30kg/hr Mass of fuel 18.06 kg/hr

Mass of air 55.54 kg/hr Mass of air 55.54 kg/hr

FLUIDIZATION RATIO- FR

EQULIZATION RATIO- ER

0.15 0.30

0.952Mass of fuel 35.29 kg/hr Mass of fuel 17.64kg/hrMass of air 55.54 kg/hr Mass of air 55.54 kg/hr

DESIGN OF BLOWER:

Pressure drop in the air duct:

Pressure drop in the air duct= 4flv^2 / 2gdf=0.0036*0.26(Re)-0.4

Re=vdρ/μ

Where Re=Reynolds number=22559F=0.0083Assume the length of air duct=3 m

The pressure drop in the air duct=57.55 per mm of WC

PRESSURE DROP IN THE DISTRIBUTOR PLATE:

Pressure drop in the nozzle=(1.5v2ρ/2g)Where v=velocity of air in the nozzle outlet=48 m/s

Density (ρ) of air=1.125 Kg/m3Pressure drop=198.165 mm of WC

PRESSURE DROP IN BED:

Orifice diameter dor= 3 mmEquivalent diameter of the bed D =0.12 mMinimum distributor pressure drop

Δpo= Δpb(0.01+0.2(1-exp(-D)/2hmf))

Δpb bed pressure drop= ρs g hmf (1-εmf)

hmf –height of the expanded bed= 170 mm

εmf –sphericity = 0.4

Δpb = 2100*9.81*0.17(1-0.4)

=2101.3 mm of WC

Δpo =2101.3*(0.01+0.2(1-exp(-0.12/2*0.17)))Δpo =145.38 mm of WC

PRESSURE DROP IN CYCLONE SEPARATOR:Pressure drop in cyclone separator 1

=4.26 mm of WCPressure drop in cyclone separator 2

=1.20 mm of WCTotal pressure drop=57.55+198.165+145.38+4.26+1.20 = 407 mm of WC

D =Equivalent diameter of the bed Minimum distributor pressure drop Δpo= Δpb(0.01+0.2(1-e(-D)/2hmf))Δpb=bed pressure drop= ρs g hmf (1-εmf)hmf=height of the expanded bedεmf =sphericity Power required (P)ή =Blower efficiency = 40%P =0.067 kWTherefore the required blower capacity is 1 HP

EXPERIMENTAL SETUP

ISOMETRIC VIEW

PLANE VIEW

OBSERVATIONS

COLD TEST

S.No Bed Height

(mm)

Expanded Bed Eight

(mm)

Bed Pressure

Drop (mm)

Superficial

Velocity (m/s)

1. 100 149 75 1.32. 120 165 112 1.43. 140 180 133 1.54. 160 196 161 1.65. 180 211 175 1.76. 200 224 225 1.8

EXPERIMENTAL VALUE OF HOT TEST

S.No Fuel used Equivalence ratio

Mass Flow Rate Of Air

(Kg/hr)

Fuel

Feed rate

In

(Kg/hr)

Pr. Drop In The distributor plate

mm of WC

Pr. drop in the bed

mm of WC

1. Neem leaf 0.15 55.54 35.37

198.165 405.470.30 55.54 17.63

2. Mahuva leaf 0.15 55.54 36.30

0.30 55.54 18.06

3.

Grass

0.15 55.54 35.29

0.30 55.54 17.64

EXPERIMENTAL VALUE OF NEEM LEAF FOR EQUIVALENCE RATIO: 0.15

SNO Time

sec

Bed temperature

˚C

Free board temperature

˚C

1. 10 203 383

2. 20 234 414

3. 30 250 476

4. 40 276 502

5. 50 330 505

6. 60 342 599

7. 70 346 686

8. 80 370 723

9. 90 368 786

EXPERIMENTAL VALUE OF NEEM LEAF FOREQUIVALENCE RATIO: 0.30

SNO Time sec Bed temperature

˚C

Free board temperature

˚C

1. 10 345 523

2. 20 380 285

3. 30 460 432

4. 40 532 877

5. 50 546 756

6. 60 570 796

7. 70 638 712

8. 80 784 892

9. 90 790 923

Thank you