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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 4, Issue 3, March 2014)

631

Design of Twin Screw Oil Expeller for Pongamia Pinnata Seeds

Amruthraj M

1

, Bharath H B

2

, Kamini S

3

, Chethan H S

4

1,2,3,4

Department of Mechanical Engineering, R V College of Engineering, Bangalore - 560059

Abstract—Biodiesel is obtained by processing edible and non-edible oils. Due to the increase in demand for fuel and stringent emission norms, biodiesel is preferred as it meets the emission norms. To meet the exponentially growing demands in developing countries, continuous production is required which can be achieved by mechanical screw presses. Currently, single screw press is being widely used for extraction of oil. The problems associated with the single screw expeller is that, it requires three or more passes to expel oil from seeds, which increases the production time and are also less efficient. In this paper, a counter rotating twin screw expeller is designed for extraction of oil from the Pongamia pinnata seeds. This paper focuses on comparison between the twin screw and single screw press technology based on both technical and economical appraisals, study is been carried out on how twin screw technology is better compared to single screw.

Keywordsbiodiesel, Pongamia pinnata seeds, single screw press, twin-screw expeller, oil extraction.

I. INTRODUCTION

The Oil extraction technology has been in use for a very long time in India and the techniques that are followed for expelling oil are very laborious and relatively inefficient. There has not been any significant improvement in the oil extraction processes and even today a century old technology such as single screw press, ghani, hydraulic presses1 are being used in various parts of the country. Mechanical screw presses are ideally preferred for oil extraction as they are economical and continuous production can be achieved. Any improvement in the technique of oil extraction tends to bridge the technological gap and increase availability of feedstock for extraction of oil.

Biodiesel is processed from edible, nonedible and animal oils. In South India, Pongamia Pinnata seeds are available in very large quantity and its trees do not require any extra care in growing them. It has been proved that the oil from Pongamia pinnata seeds can be converted to biodiesel2. The oil from Pongamia seeds is usually extracted using a single screw press oil expeller. The process is inefficient and requires a lot of labour as oil extraction takes place only after three or more passes. In order to overcome the above mentioned drawbacks and to meet the production rate of 80 – 100 kg/ hour, a twin screw oil expeller is designed.

Experiments have already been performed on twin screw expeller for extracting oil from Jathropa3 and sunflower seeds4,5. No such experiments have been conducted on Pongamia Pinnata, hence this paper focuses on designing a twin screw expeller for Pongamia Pinnata seeds

For the designs of twin screw expeller, single screw expeller design plays an important role, as many assumptions in the twin screw designs were made based on the single screw expeller design keeping the technical and economical feasibilities in consideration.

The single screw expeller is as shown in figure 1. The design of the single screw expeller consists of a forward screw shaft (powered using 5hp motor) and housing.

1.The specifications of the shaft are

The shaft has a constant outer diameter, the inner/root diameter increases as the thread progresses forward.

i. Outer diameter = 88 mm,

ii. Inner / root diameter = from 56 mm to 84 mm

iii. Length = 390 mm

iv. Length/diameter = 4.43

2.The specifications of the housing are:

Inside the housing, a pressure of 20MPa is developed, the wall thickness of the barrel is 25.4mm and 24 square bars are arranged over the inner circumference of the barrel, this arrangement is made in order to expel the oil through the gaps in between two adjacent blades when the seeds are pressed at 20MPa pressure. Inner diameter = 90 mm, Figure 2 shows the pressing region and screw profile of the shaft.

The expelling efficiency of this oil expeller is 50%. The average oil content in Pongamia pinnata seeds is 35%6, the yield efficiency of the expeller is 18%, and the cake contains 8% of oil in it. The cake after the removal of oil flows axially and comes out as shown in figure 3.

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 4, Issue 3, March 2014)

632

II. DESIGN

The design consists of two screw shafts, liner and housing.

1. Design of screw shaft:

The screw shaft is of increasing root/inner diameter, decreasing pitch and a trapezoidal screw profile with a buttress as shown in figure 2. These are incorporated in order to increase the pressure of the seeds as the seeds progress towards the crushing region. The seeds get crushed at the mating region of the screws and the crushed seeds get squeezed in the pressing region and the oil is expelled.

[image:2.612.325.563.156.404.2]

The list of formulae and minimum calculations are shown in table 1 below. The nomenclatures are shown in table 2.

Table 1

List of formulae and calculated values.

Sl no.

Parameter Formulae Value

1 Power(P) -- 10hp or 7.5

kW

2 Torque (T) P= 2πNT/60000

And T=Fts*ds /2

715Nm

3 Pressure (p) From Reference 20MPa

4 Axial load on one

thread(Fxs)8

Fxs = p*Lt*H 5200 –

10500 N

5 Tangential Load on a thread (Fts)8

Fts = Fxs[ l + πfds ]/[ πds-f l ]

3500 – 9200 N

6 Theoretical Screw Volume (Vs)

Vs = A*(l - H) = 0.25π[ ds2 –d2 ] (l - H)

1.14 E-4 m3

7 Mass flow rate (ṁ)

ṁ = Vs * n*ρ*Ψ 0.0303 kg/s

Specification of screw shafts are given below and the draft of the shafts are as shown in figure 4.

i.Outer diameter: 80 mm

ii.Inner diameter: 40mm to 56 mm

iii. Length of the shaft: 420mm iv. Length/diameter: 5.25

Table 2

List of Nomenclature and values

PARAMETER VALUE

Speed (N) 100 rpm

Crest Diameter(ds) 0.080 m

Root diameter(d) 0.045 – 0.056 m

Taper angle (α) 1.15 degrees

Pitch Variation (l ) 2.5 mm/ pitch

Thread height variation (H) 1 mm / pitch

Number of turns (n) 7

Crushing head diameter 0.056 m

Worm length (Ls ) 0.36 m

Crushing head length (Lc ) 0.06 m

Total length ( L ) 0.52m

Housing inner diameter (Di) 0.082 m

Thickness of the housing (t) 0.025 m

Density(ρ) 625kg/m3

Filling Factor(Ψ) 0.3

Length if thread(Lt) 50mm – 38mm

2.Barrel design

The barrel houses a liner and two counter rotating shafts. The counter rotating9 shafts helps in more pressure development and more retention time. The seeds are fed to the barrel through a hopper and these seeds are progressed via counter rotating shafts towards the pressing region and oil is expelled by the passage provided in the liner and flows down due to gravity. Three ports are provided in the barrel, one for air out, one for pressure relief and cleaning and one for oil collection as shown in the figure 5.

Two barrel configurations are designed. Configuration 1 is designed for mass production at a lower cost. Configuration 2 is designed for more flexibility and also for research and development purpose using different seeds.

The specification of the barrel configuration1 is mentioned below and the drafting is shown in figure 5.

i. Length of the housing: 420 mm

ii. Housing inner diameter: 84 mm

[image:2.612.52.287.347.562.2]
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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 4, Issue 3, March 2014)

633

The specification of the barrel configuration 2 is as mentioned below and the drafting is shown in figure 6.

i.Length of the barrel: 500 mm

ii.Housing inner diameter: 84mm

iii. Thickness of each plate: 10 mm

III. ANALYSIS

To validate the designs provided in the previous sections, analyses of the designs are performed. The analyses of shaft, barrel designs along with liner design are performed.

a)Shaft analysis

The expeller contains two counter rotating shafts and the material used is mild steel. The loading and boundary conditions on both the shafts are identical. Therefore, analysis is performed on one shaft. The results obtained from analysis of this shaft would be similar to that of the other shaft and is as shown in figure 7. When the shafts make one rotation, the seeds progress axially by one pitch and also gets crushed to some extent. On continuous rotation of the shafts, the seeds are transported from hopper end to the crushing end. During this movement the seeds exert axial and tangential forces on the shaft. As the seeds progress, the clearance and the volume between the shaft and barrel decreases, because of which the pressure increases. The pressure reaches a maximum of 20 MPa at the pressing region. All the loads that are developed are applied on the shaft. The shaft is mounted on bearings. In the analysis, the bearings are substituted by cylindrical supports. The shaft is also subjected to a torque of 360 Nm.

b)Barrel analysis

The barrel analysis includes barrel and liner. The pressure of 20MPa is applied on the inner region of the liner of the barrel assembly. The barrel is fixed on both the end faces. The analyses of both the barrel configurations are performed.

i. Analysis of Barrel Configuration 1.

As the barrel is meant to be used only for Pongamia pinnata seeds and not much of flexibility is required. It is manufactured using casting and is machined to the exact accuracy, the two halves are joined using bind and then the analysis is carried out by applying the pressure. The analysis is as shown in figure 8

ii. Analysis of Barrel configuration 2.

As the barrel is meant to be used for research purpose and the barrel is manufactured using the assemblage of plates and are fastened together and will be placed on a solid cast iron bed. The analysis was carried out similarly to that of the barrel configuration 1. The results are shown in figure 9.

IV. RESULTS

The results of the analysis shows that the twin screw design is safe and the deformations are negligible when the loads are applied, so in order to meet the growing demands a twin screw expeller is feasible both economically and technically by decreasing the overall cost of production and by increasing the throughput rate of seeds.

V. CONCLUSION

Twin screw expeller can be used for expelling oil from Pongamia pinnata seeds. It can also achieve a throughput rate of 80 – 100 kg/hour with single pass, unlike single screw expeller which requires three or more passes.

Hence, twin screw expeller has more potential in oil extraction process for non- edible oil extraction. Twin screw expeller also overcomes the difficulties of single screw expellers.

Acknowledgement

We would like to thank prof. Krupashankara Sethuram and prof. Chandrakumar R for guiding and supporting us throughout our work towards designing Twin Screw Expeller. We would also like to thank KSBDB for supporting us financially and we would like to thank all the faculty of the Mechanical Department of R V college of Engineering for supporting us during the work.

REFERENCES

[1] Issac Bamgboye and A.O.D Adejumo, ― Development Of Sunflower oil expeller‖, Agricultural Engineering International, the CIGRE Journal, Vol IX, September 2007.

[2] Bobade S.N and Khyade V.B, ―Detail study on the Properties of Pongamia Pinnata (Karanja) for the Production of Biofuel‖, Research journal of chemical sciences, Vol 2(7), 16 – 20, July 2012. [3] Ph. Evon, I. Amalia Kartika, et al., ―Extraction of oil from jatropha seeds using a twinscrew extruder: Feasibility study‖. Industrial Crops and Products, vol. 47, 33-42, 2013.

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 4, Issue 3, March 2014)

634

[5] Isobe S. et al., ―A new twin-screw press design for oil extraction of dehulled sunflower seeds‖ National Food Research Institute, Japan, Journal of the American Oil Chemists' Society, Volume 69, Number 9.

[6] ―Expellers in India and expelling operations‖, Department of science and technology, Government of India, Vol. 1, June 2012.

[7] Khan, L.M. and Hanna, M.A. Expression of Oil from Oilseeds-A Review. J. agric. Engg Res. (1983) 28

[8] Zhijun Zhong Theoretical and Experimental analysis of the compaction process in a tapered screw press, 1991.

[image:4.612.48.559.129.435.2]

[9] A. Shah and M. Gupta, ―Comparison of the flow in co-rotating and counter-rotating twin screw Extruders‖ Mechanical Engineerings-Engineering Mechanics Department Michigan Technological University, Houghton, 2004

FIGURE 1: Single screw press expeller picture and draft

[image:4.612.60.561.487.641.2]
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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 4, Issue 3, March 2014)

[image:5.612.66.550.133.704.2]

635

[image:5.612.86.525.137.414.2]

Figure 3: Indicating seed input, Oil output, Cake output

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 4, Issue 3, March 2014)

[image:6.612.53.564.129.629.2]

636

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 4, Issue 3, March 2014)

[image:7.612.324.563.129.592.2]

637

Figure 6: 3D View Of Configuration 2 Barrel Fastened With Blades

[image:7.612.49.288.134.316.2]

Figure 6: Plate Profile Near The Pressing End

Figure 6: plate profile near hopper end

[image:7.612.51.286.342.537.2]
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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 4, Issue 3, March 2014)

[image:8.612.53.283.136.324.2]

638

[image:8.612.326.560.136.317.2]

Figure

Table 2 List of Nomenclature and values
FIGURE 2: Pressing region (encircled) and buttress profile
Figure 3: Indicating seed input, Oil output, Cake output
Figure 5: draft of burst view of the twin screw barrel of configuration 1 and legend
+3

References

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