TEAM MEMBERS:PRACHURYA SARMAPOORNA CHANDRA PRAKASH M. NABHISHEK KUMAR SINGHHARSHITH.M  

 PROJECT GUIDE T.C.Narendra Babu

“MODIFICATION AND REFABRICATION OF MINI OIL EXPELLER”

What is OIL EXPELLER?

The Oil Expeller is a screw type machine, which presses oil seeds through a

caged barrel-like cavity. Raw materials enter one side of the press and

waste products exit the other side. The machine uses friction and

continuous pressure from the screw drives to move and compress the seed

material. The oil seeps through small openings that do not allow seed fiber

solids to pass through. Afterward, the pressed seeds are formed into a

hardened cake, which is removed from the machine. Expeller pressing (also

called oil pressing) is a mechanical method for extracting oil from raw

materials. The raw materials are squeezed under high pressure in a single

step. When used for the extraction of food oils, typical raw materials are

nuts, seeds and algae, which are supplied to the press in a continuous feed.

Oil expeller is a mechanical equipment to extract the oil from seeds the principle behind this equipment is the friction between the cylinder cage and worm shaft assembled inside the cylinder.

The seeds are feed through the hopper which connects to cylinder and worm shaft assembly, as soon as the seeds reach the rotating assembly it gets feeded to crushed and oil is extracted.

WORKING PRINCIPLE

Screw Shaft Barrel Choke

Parts

The worm shaft conveys the material inside the barrel and compresses the material against a choke. The worm shaft is a large screw, hence the name screw press. As the worm rotates the seeds move forward between the worm teeth. As they move forward they are also rubbed against the barrel walls.

Shaft

Straight Screw

Types of Shaft

Tapering of Root diameter

The root diameter of the shaft increase to facilitate increase in pressure as the seeds move forward. This also compensates for the decrease in volume of the seed as they are compresses and as oil is lost

As there is a reduction in volume as the seeds are compressed and oil is expelled, the mass flow rate has to be reduced so that the decrease in pressure due to reduction in volume is compensated.

Shafts with Decreasing Mass Flow rate

Types

Tapered Root Diameter Variable Pitch

Tapered Diameter and Variable Pitch

Choke is installed at the discharged end. This device has the function of operating pressure by changing the width of the annular space through which cake must pass. It is possible to adjust the choke by a hand-wheel on the opposite end of the screw. We are using a conical type of choke mechanism.

Choke

Types

Nozzle Type

Seeds continue to accumulate at the end of the screw until the maximum pressure has been reached. During compression, oil part of the seeds leaks from the filter and the left cake starts to extrude out from the nozzle, at the end of the screw.

Conical Type In this type the cake is pushed over the conical choke. The

maximum pressure and the cake thickness can be changed by adjusting axial displacement of the screw shaft forward and backward in order to achieve the required pressure.

Drilled Holes  In this system holes are made on the barrel so that oil flows out of

these holes. The main advantage of this system is no extra parts for oil drainage system is required. However the oil drainage openings in this system are not adjustable.

Oil Drain System

Lining Bars with Spacers In this type of oil drainage system lining bars are fixed inside surface of the vessel cage. The bars are ground at center, so that though they are closely packed there is some gap for the oil to flow out.

This kind of liquid drainage system is generally used for the substances which do not require high pressure. Since the fiber is a deformable material, high pressures would result in expansion of the fiber.

Fiber Filter Sleeves

Cylinder-Hole Press• Drilled holes oil drain system.• Nozzle type choke system.

Types of Screw Press

Strainer Press• Lining Bar Oil Draining System• Conical Type Choke

Speed  Higher screw speed means more throughput and higher

residual oil content in the press cake since less time is available for the oil to drain from the solids.

Restriction size  When the restriction size is reduced the pressure

required to overcome the restriction increases. A resulting decrease in oil content causes increased viscosity of the paste and further pressure rise.

Parameters Effecting the Process

Moisture content

• Moisture works as heat transfer medium. So the total heat generated during pressing will be fully transferred to the individual fat globules, which results in breakdown of the emulsion form of the fat and helps in releasing more oil droplets.

Temperature

• The friction inside the barrel generates heat which is passed on to the oil. Increase in temperature of oil leads to higher phosphor content. High phosphor content is an undesirable fuel property as it can cause deposits and clogging in engines.

Strainer type expellor, i.e bars are used. The screw is of tapered shaft type. The pitch is 20mm and is constant. The root diameter of the shaft increases from 16

mm at the delivery point to 26 mm at the end of the screw.

The choke used is of conical type. The power system availble is a 1 phase 1hp

electrical motor with a speed of 1420rpm with gear box and coupling arrangement. The speed is reduced to 105 rpm in the gear assembly.

Existing Model

Sectional View

Deformation of Shaft

In the old model the liner bars have no gap for oil flow, instead slots have been cut close to the delivery side of the worm. That is the oil has to travel back to the delivery side once it has been extracted to flow out of the barrel. This flow of oil is resisted by incoming fresh seeds.

Problems Noticed

The bars are ground near the center, so that the oil can escape through the bars.

 

Modifications Made

Old Liner Bar Arrangement

New Liner Bar Arrangement

Choke The taper angle of the choke is reduced. This facilitates

easy flow of cake over the cake. The old choke had larger taper angle and it was difficult for the cake to flow between the choke and barrel. Also the choke is extended towards the rear in the shape of a bolt head so that it is easier to adjust the area for the cake to pass through.

Parts have been fabricated such that the maintenance and handling is easy. Earlier the bar holder and bearing housing had full body thread, and hence it was very difficult to dissemble the machine. So we have made step in these parts so that its easier to loosen them and the threads will not be damaged too

Other Modifications

Solid steel rods of diameter 40mm and 90mm each of length 35 mm were used.

Material selected was Stainless Steel 202 as it is hard and economical. The entire fabrication was done in our college machine shop.

Fabrication

Face Turning The end surfaces were flattened and rod was

reduced to the exact required length by face turning operation using a High Cut Carbide Tip Tool.

Operations

Drilling Hole of 40 mm was drilled using drilling tool throughout the

rod. First a 20mm drill bit was used. Once the barrel was drilled with 20mm throughout a 40 mm drill tool was used. The feeding hole on the barrel was also made using the drilling tool.

BoringThe different inner diameters within the barrel was obtained by boring with boring tool. The barel was step turned to create slots to hold the lining bars.

End Milling The slots that expose the bars were made by end milling

operation using an end milling tool. The hole for feed over which the hopper is placed was finished using the end milling tool.

Thread Cutting The worm shaft was made by the thread cutting operation.

The pitch of the thread was 20mm. The root diameter of the worm increases from 16mm at the feed point to 26 mm at the end. The part which holds the lining bars and the bearing housing were also threaded.

Taperturning The choke was made by taperturning operation. The part

which is used to hold the lining bars tightly was also taperturned on the inner side.

Tapping The end of the wormshaft and the choke was first drilled

and then tapped.

Coolants A soluble coolant was used for all the operations except

cutting, where water was used.

High Cut Carbide Tip Tool End Milling Tool 20mm Boring Tool Drill Bits 20mm & 40mm Tapping Tools

Tools Used

Karanjia seeds were used. Oil started oozing as the seeds reached the

end of the shaft Cake flow was continuous once the machine

started heating up Little amount of cake came out also

between the lining bars mixed with the oil The machine could expell oil from 6.5 to 7

kg of seeds per hour

Testing and Results

The old machine could not run in the second pass, whereas in the new machine the cake flow is continuous even in the second flow.

The through put of the old machine was single pass of 6 kg per hour, but the new machine can expel oil from two passes of 6.5 to 7 kg per hour, in terms of single pass it is upto to 14 kg per hour.

From the test it can be safely concluded that there is upto 50% increase efficiency.

Comparison

Cake coming out over the choke

Oil coming out through the liner bars and Slot made in Barrel

Cake after second pass

The gap between the bars can be shifted away from the choke as the pressure is very high near the choke region and this pressure pushes a little amount of cake through the lining bars.

The gap between the lining bars and barrel wall has to be increased and the area exposing the bars can also be increased. By increasing the area exposing the bars, it is easier to clean the cake that has escaped through the liners.

Scope for Improvement

As only two phase power supply is required, it can be used in villages.

As operating the machine doesn’t require much previous experience, Self Help Groups can adopt these machines to create self employment opportunities

Even bio diesel plants and universities, these mini expellers can be used to extract oil in small quantities from different seeds for research purposes.

Conclusion

Sl No Particulars Cost(Rs)

1 Materials SS202 45Ø 33mmSS202 90 Ø 33mm

4300

2 MS Plates 350

3 Tools & Misc 1320

Total 5970

Cost Analysis

1.)Singh and Bargale, 2000 "Development of a small capacity double stage compression screw press for oil expression ", Journal of Food Engineering Vol 43 75-82

2.) Vadke V. S. and Sosulski F. W., 1988 "Mechanics of oil expression from Canola", Journal of the American Oil Chemists' Society, 65(7): 1169-1176.,

3.) Faborode MO and Favier JF,  1996.  "Identification and significance of the oil-point in seed-oil expression." Journal of Agricultural Engineering Research. 65(4):335-345.

4.) Khan L.M. and Hanna M.A., 1983. "Expression of oil from oilseeds. A review." Journal of Agricultural Engineering Research., 28(6), 495-503.

  5.) Sukumaran C.R. and Singh B.P.N., 1989. "Compression of a bed

of rape seeds: the oil point". Journal of Agricultural Engineering Research., 42(2), 77- 84.

References

THANK YOU