Production of Gaseous Fuels Pongamia Residue

P M V SubbaraoProfessor

Mechanical Engineering Department Indian Institute of Technology Delhi, New Delhi

Enhance the value of Fuel Energy ….

Pongamia Residue

• De-oiled cake – Rich Proteins

• Shells – Rich Cellulose

The Mind of Inventor Robert Boyle

•17th-century natural philosopher, chemist, physicist, and inventor, also noted for his writings in theology.• Scientific interest in the manufacturing of gas produced by the natural decomposition of organic matter, was first reported in the seventeenth century by Robert Boyle

Major Biological Events in Anaerobic Digestion

hydrolytic bacteria

Fitness De-oiled Cakes for Hydrolysis

Dry Pongamia Seed Cake

Dry Jatropha Seed Cake

Seed Cakes soaked in water

Ultimate Methane Potential of A Feed Material

CaHbOcNd + X H2O Y CH4 + Z CO2 + d NH3

X = (4a – b + 2c + 3d)/4

Y = (4a + b – 2c – 3d)/8

Z = (4a – b + 2c + 3d)/8

Buswells equation

Number of moles per

mole of ’organic matter’

8

Ultimate Methane Potential

Bult = 22.4 Nl/mol * (4a + b – 2c – 3d) mol

1000 l/m3 8 * (12a + b + 16c + 14d)g

[Nm3/g]

Bult = 22400 * (1/2a + 1/8b – 1/4c – 3/8d)

(12a + b + 16c + 14d)

[Nm3/ton]

[Nm3] = one cubic meter of gas at standard state: 1 atm and 0 oC

Proximate analysis of feed materials(As Received Basis)

Feed material

Moisture content

%

Oil content

%

Total solids

%

Volatile solids %

Non-volatile solids %

Cattle dung 81.6 Nil 18.4 14.4 4.0

Jatropha oil seed cake

7.5 8.3 92.5 86.4 07.0

Pongamia oil seed cake

10.5 7.2 89.5 85.3 05.2

Ultimate Analysis and carbon-nitrogen ratio : VM of feed materials

Sr. No.

Feed material C (%) H (%) N (%) C/N ratio

1 Cattle Dung 35.20 4.60 1.55 22.7

2 Jatropha oil seed cake

48.80 6.20 3.85 12.7

3 Pongamia oil seed cake

47.80 6.50 5.50 8.7

1. Entire VS in feed material cannot be degraded.

2. The degradable material can only be completely converted to gas if a longer Hydraulic Retention Time (HRT) is used.

3. Part of the input material is inorganic (even though it may contain H).

4. The digestion process may not be optimal (inhibition).

Practical Methane Production

The Inoculum

•Living element(s) of the parasite are able to contaminate a host feed material. •It is the "primary inoculum" that enters the host and induces the degradation.•The "secondary inoculum", resulting from the fructification of part of the contaminated host population, causes the spread in the host population

Preparation of Substrates and Determination of Their Properties

Mixing of de-oiled cake with Inoculum. Dilution ratio and solids concentration. To keep TS in between 18-22 % and to maintain

flow ability of substrates. More surface for Bacterial hydrolysis. An inoculation ratio of 1:10 used in laboratory

experimentation. With and with out cow dung. A dilution ratio of 3:1 and 4:1 for jatropha cake and, 3:1 and 3.5:1 for pongamia cake.

Preliminary Batch Biomethanation Study

5 L Aspirator Bottle[DIGESTER]

5 L Aspirator BottleFilled With Water

Gas Contituents Analysis(Biogas Analyzer)

Valve Valve

Valve

Cork Cork

Cork

Gas Volume Measurement(Measuring Cylinder)

Experimental setup for batch biomethanation study

Range of ambient temperature variation 24.5 to 35.1 °C

Range of substrate temperature variation 24 to 34.5 °C

Period of Experimental Study:15th March 2006 to 12th June 2006

Composition of prepared substrates and their C/N ratio, TS, VS and their dilution ratio [as received (live dilution ratio)

and absolute dilution ratio (dry basis)]

Sl. No.

Treatmentdesignation

Substrate constituentsDilution ratio,Water : Cake

C/Nratio

Substrate concentration

Cake, g

Water, ml

Dung, g

Inoculum, g

Live Absolute % TS % VS

1 1.0 DR [CD] 0.00 2000 2000 200 1:1 11.6:1 22.7 7.9 6.1

Jatropha Oil Cake Substrates

2 3.0 DR [5JC:0CD] 500 1500 0.00 50 3:1 3.4:1 12.7 22.8 21.2

3 3.0 DR [5JC:1CD] 500 1500 100 50 3:1 3.5:1 12.8 22.5 20.7

4 3.0 DR [5JC:2CD] 500 1500 200 50 3:1 3.5:1 12.9 22.2 20.3

5 3.0 DR [5JC:3CD] 500 1500 300 50 3:1 3.6:1 13.1 21.9 20.0

6 3.0 DR [5JC:4CD] 500 1500 400 50 3:1 3.6:1 13.2 21.6 19.7

7 3.0 DR [5JC:5CD] 500 1500 500 50 3:1 3.7:1 13.3 21.4 19.4

8 4.0 DR [5JC:0CD] 500 2000 0.00 50 4:1 4.5:1 12.7 18.2 16.9

9 4.0 DR [5JC:1CD] 500 2000 100 50 4:1 4.5:1 12.8 18.1 16.7

10 4.0 DR [5JC:2CD] 500 2000 200 50 4:1 4.5:1 12.9 18.1 16.6

11 4.0 DR [5JC:3CD] 500 2000 300 50 4:1 4.6:1 13.1 18.0 16.4

12 4.0 DR [5JC:4CD] 500 2000 400 50 4:1 4.6:1 13.2 17.9 16.3

13 4.0 DR [5JC:5CD] 500 2000 500 50 4:1 4.6:1 13.3 17.8 16.1

16

Sl. No.

Treatmentdesignation

Substrate constituentsDilution ratio,water : cake C/N

ratio

Substrate concentration

Cake, g

Water, ml

Dung, g

Inoculum, g

Live Absolute % TS % VS

Pongamia Oil Cake Substrates

143.0 DR

[5PC:0CD]500 1500 0.00 50 3:1 3.7:1 8.7 21.3 20.3

153.0 DR

[5PC:1CD]500 1500 100 50 3:1 3.7:1 8.8 21.1 19.9

163.0 DR

[5PC:2CD]500 1500 200 50 3:1 3.8:1 9.0 20.8 19.5

173.0 DR

[5PC:3CD]500 1500 300 50 3:1 3.9:1 9.1 20.6 19.2

183.0 DR

[5PC:4CD]500 1500 400 50 3:1 3.9:1 9.3 20.4 18.9

193.0 DR

[5PC:5CD]500 1500 500 50 3:1 3.9:1 9.4 20.2 18.6

203.5 DR

[5PC:0CD]500 1750 0.00 50 3.5:1 4.3:1 8.7 19.0 18.0

213.5 DR

[5PC:1CD]500 1750 100 50 3.5:1 4.3:1 8.8 18.8 17.8

223.5 DR

[5PC:2CD]500 1750 200 50 3.5:1 4.3:1 9.0 18.7 17.5

233.5 DR

[5PC:3CD]500 1750 300 50 3.5:1 4.4:1 9.1 18.6 17.3

243.5 DR

[5PC:4CD]500 1750 400 50 3.5:1 4.4:1 9.3 18.5 17.1

253.5 DR

[5PC:5CD]500 1750 500 50 3.5:1 4.4:1 9.4 18.4 16.9

Continued…

16

17 Experimental Setup used for Preliminary Batch Study

17

Conclusions from Characterization of Feed Materials and Preliminary Batch Biomethanation Study

Low yield and very poor quality of biogas was observed during the preliminary batch biomethanation study.

A major challenge in biomethanation of these deoiled cakes is lacking of inherent bacteria like cattle dung.

Lack of these inherent bacteria demands a special attention for operation of digester with cake.

Other major deficiency of cake is the presence of long chain free fatty acids, which are prone to destroy the population of bacteria.

Thus the microbes present in cattle dung inoculum could not survive in new environment.

There may be a continuous drop in population of bacteria in the inoculum.

Need for Development of New Inoculums

The microbes present in cattle dung inoculums could not survive in deoiled cake-water environment.

The substrates of jatropha and pongamia oil cakes might have created a sudden and drastic change in environment for the bacterial activity resulting in their inhibition.

There was a continuous drop in population of bacteria in the inoculums.

This is due to effect of bacterial inhibition since the substrates were new for the bacteria present in the cattle dung inoculum.

This proves that production of effective (special) inoculum in a small aspirator bottles with little amount of initial inoculum (taken from a cattle dung digester) is not feasible.

F

A

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7.523237.5All dimensions in centimetres

10 D

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Ground Level

Gas Holder Supporting Structure

Biogas plant (20 m3/d) capacity available at IIT Delhi

20

Development of Special Inoculum

20 m3/d BGP

About 12 m3 CD inoculum

Feeding of pongamia oil cake in 3:1 DR for 15 days

No feeding of CD before last 3 months

Schedule I 2 kg pongamia oil cake with 6 kg water for 5 days

1 2 3 4 5

Sta

rt of g

as

pro

du

ctio

n

Con

tinu

ed

5 kg pongamia oil cake with 15 kg water for 10 days

Schedule II

Drop in gas yield

6 7 8 9 10 11 12 13 14 15

Increase in gas yield

Constant gas yield (10-15 day) at 30 cm height

10 cm height

2121

Biogas Plant before Feeding Started

Biogas Plant After Feeding of Oil Cake Slurry

Evolution of Microbes

This shows the adaptation of bacteria to the environment offered by new substrates possibly by developing into a suitable strain.

This acclimatization is due to fact that, when the concentrations of inhibitory or toxic materials were

slowly increased within the environment, many microorganisms could rearrange their metabolic

resources, thus overcoming the metabolic blockage produced by the normally inhibitory or toxic material.

However, sufficient time should be made available for this rearrangement to take place where there is drastic change in environment (feed material).

The slurry of the biogas plant stabilized with pongamia oil seed cake was used as inoculum for further studies.