Researchpaper Development of a Screw Press for Palm Oil Extraction

Development of a Screw Press for PalmOil Extraction

O. A. Adetola, J. O. Olajide and A. P. Olalusi

Abstract- A palm oil screw press was designed, fabricated and evaluated for small and medium scale palm fruit processors inorder to mechanize the extraction process and increase production output. The major components of the machine are standing

frame, threaded shaft, speed reduction gear motor, driving & driven pulley and discharge outlet. The highest oil extraction ratio

(OER) of 17.90% and oil extraction efficiency (OEE) of 79.56% were obtained at the sterilization time of 60 min, digestion time of 10

min and screw speed of 10 rpm. The production cost of the press is $650 and it is powered by a three- phase 5hp electric motor.

Index Terms: Design, extraction, fabrication, palm oil, screw press, fruit processors, efficiency

1. INTRODUCTION

The oil palm (Elaeis guineensis) is animportant economic tree that is grown inAsia, Africa and South America [1]. It is theprincipal source of palm oil which is anedible vegetable oil. About 90 percent of thepalm oil produced ends in food products,while the remaining 10 percent is used forindustrial production [2].Because of itsmany uses demand is growing fast as theworlds population increases and standardsof living rise. Palm oil accounts for 34percent of the worlds annual production ofvegetable oil and 63 percent of the globalexports of vegetable oils. It is produced intropical climates and in 42 countries acrossthe world [3]. Nigeria is currently the thirdlargest producer of palm oil in the worldafter Indonesia and Malaysia; however itremains a net importer. Palm oil and palmoil manufacturing represents one of the most

effective methods of raising Nigerians frompoverty and ensuring food security. Itprovides employment for millions ofunskilled and semi-skilled workers [4-5].The traditional method of palm oilprocessing is time consuming, laborious,hazardous and inefficient resulting in theproduction of low quality oil. Oil extractionstill remains a critical bottleneck particularlythe level of small and medium scaleprocessors in Nigeria [5]. Nigeria has lost itspremier position on the list of world majorpalm oil producers for the past few decades[6]. This has been traced to lack of improvedvariety of palm fruit, land tenure system,and lack of appropriate processingtechnologies. Lack of appropriate processingtechnologies constitutes the major obstacleto palm oil production in Nigeria [5].

Adetola Olufemi Adeyemi is currently pursuing his PhD in Agricultural and Environmental Engineering Department, Federal University ofTechnology Akure, Nigeria. Email: [email protected] Olajide O. J. is currently working as a Professor in Food Engineering Department, Ladoke Akintola University of Technology, Ogbomoso,Nigeria. Email: [email protected] A.P. is currently working as a Senior Lecturer in Agricultural and Environmental Engineering Department, Federal University ofTechnology, Akure, Nigeria. Email: [email protected]

International Journal of Scientific & Engineering Research, Volume 5, Issue 7, July-2014 ISSN 2229-5518 1416

IJSER 2014 http://www.ijser.org

IJSER

Over the years attempts have been made tomechanize the various operations involvedin palm oil processing. Extraction (pressing)has received the greatest attention formechanization. Presses developed over theyears have included models such as: Manualvertical screw-press, Stork hydraulic handpress, Motor-jack press, Motor-jack/cantilever press, NIFOR hydraulic handpress, combined screw/hydraulic hand press,mechanical screw-press [6]. Existingimported screw press machines for oil palmare very expensive and not readilyaffordable by small and medium scaleprocessors who form the majority of theprocessors. Industries established withimported technology do not function for along period of time because of lack of spareparts, inadequate maintenance and inabilityto satisfy some local factors [7]. It isessential to evolve indigenous technology toaddress the issue of food processing inNigeria. Many authors have reported on theneed to develop indigenous technology inthe various aspect of agricultural and foodprocessing operations [8-10]. SeveralAfrican nations including Nigeria arecurrently developing oil palm plantations soas to produce palm oil on a commercialscale in order to eradicate poverty anddiversify the economy. Production ofindigenous machinery to process theexpected boom in palm fruits to palm oil isimperative. The objective of this worktherefore is to design, construct anindigenous palm oil screw press toeffectively extract crude oil from oil palm.

2. MATERIALS AND METHODS

2.1.1. Machine Description and WorkingPrinciple

The screw press consists of the followingcomponents: worm shaft, cylindrical barrel,feeding hopper, electric motor, pulley, cakeoutlet, oil outlet and main frame. The

cylindrical barrel was made from a mildsteel pipe of length 650 mm, inside diameterof 166 mm and thickness of 10 mm. Theworm shaft was made from a mild steel solidrod of diameter 80 mm and length 900 mm,which was machine on their lathe at adecreasing screw pitch and decreasing screwdepth. The worm shaft is housed in thecylindrical barrel at a clearance of 1.5 mmbetween the screw diameter and insidediameter of the barrel. In operation, thedigested palm fruit is introduced into themachine through the feeding hopper; themachine convey sand presses the digestedpalm fruit inside the cylindrical barrel withthe aid of the worm shaft until crude oil ispressed out of the mash. The crude oilextracted is drained through the oil channelinto the oil tray where it is collected, theresidual cake is discharged at the cake outletand collected at the cake tray. The machineis powered by a 5hp three phase electricmotor and has production cost of $650 withthe construction materials being locallyavailable at affordable costs.

Figure 1: Exploded view of the palm oil screw press showingthe component parts



IJSER

Figure 2: Palm oil screw press developed

2.2. Design Considerations andCalculation Procedures

2.2.1. Design considerationsWhile designing the machine considerationincluded: high oil yield, high oil extractionefficiency and ratio, low extraction loss,quality of oil, availability and cost ofconstruction materials. Other considerationsincluded the desire to design the cylindricalbarrel to accommodate the require quantityof raw material (digested palm fruit). Alsoconsidered is to design the worm shaft toensure maximum conveyance and pressingof the crude oil. Other considerationsincluded the simplicity in design and easy tofabricate the machine, be usable by anybodyeven without any previous technical trainingand a strong main frame to ensure structuralstability and strong support for the machine.2.3. Design Calculations2.3.1. Design of worm shaft of the

expellerThe worm shaft is the main component ofthe screw press and is acted upon by weightsof material being processed, pulley andscrew thread. In operation, the worm shaft

conveys, presses and squeezes the material(digested palm fruit) for oil extraction.Therefore, in other to safeguard againstbending and tensional stresses, the diameterof the shaft was determined from theequation given by [11-12] as:

ds = 16T (1)0.27O

Where, ds is diameter of the screw shaft, T isthe torque transmitted by the shaft and O isthe yield stress for mild steel. Given that T =628.471Nm and O = 432.33N/mm2; hence,ds = 28.00 mm. Therefore, a mild steel rodof diameter 30 mm was used for the wormshaft.2.3.2. Design of the screw threadThe worm shaft is essentially a tapered

screw conveyor with the volumetricdisplacement being decreased from thefeed end of the barrel to the discharge end.The screw treading system was design as astep up shaft diameter and decreasingscrew depth using the expression in theequation below as:

Un = a+(n-1)d (2)

Where, Un is the screw depth at thedischarge end, a is the screw depth at thefeed end, n is the number of screw turns, andd is the common difference between nextsuccessive screw depths. Given that Un=5mm, a = 25 mm, and n = 9; hence d= -2.5mm. Therefore, the screw depth would bedecreased consistently by 2.5 mm from thefeed end to the discharge end of the barrel.2.3.3. Design of the load that can be

lifted by the screwThe load that can be lifted by the screw wasdetermined from the equations given by [13]

as; = ( ) (3)= () (4)



IJSER

Where, We is the load that can be lifted bythe screw, T is the Torque transmitted by thescrew shaft, Dm is the mean thread diameter, is the coefficient of friction, n is thethread (lift) angle, and is the taperingangle. Substituting T = 628.471 Nm, Dm =55 mm, = 3, = 0.15 and n = 15o, hence,

= 14.98o and we = 52.88KN. Therefore,5.40kg of mash can be processed at a time.

2.3.4. Design of the pressure to bedeveloped by the screw thread

The pressing area [13] and the pressuredeveloped by the screw thread weredetermined by equations 5 & 6 respectivelyas:

= (5) = (6)

Where, Pr is the pressure developed by thescrew thread, Ap is the pressing area and h isthe screw depth maximum pressure(discharge end). Substituting = 3.142, Dm= 55mm, n = 9, h = 5 mm, and We = 52.88KN, hence Ap =7776.45mm2 and Pr = 6.80N/mm2. Therefore, a pressure of 6.80Mpawould be available for pressing andsqueezing oil from the mash duringoperation.

2.3.5. Design for the pressure of the barrel

The pressure that can be withstood by thebarrel was determined by the equation givenby [12, 14] as;

= (7)Where Pb is the pressure to be withstood bythe barrel, t is thickness of the barrel, a isallowed stress = 0.27 0 , 0 is the yieldstress of mild steel, and Di is the insidediameter of the barrel. Substituting t= 10mm, o = 423.33N/mm2 , and Di = 166

mm, hence a = 114.30N/mm2 and Pb =13.77N/mm2 or 13.77Mpa. This means thatthe pressure that the barrel can withstand(13.77Mpa) is greater than the pressuredeveloped by the screw thread for oilextraction (6.80Mpa). Therefore, the barrelwill withstand the extraction pressurewithout bursting.

2.3.6 Designed for the capacity of theexpeller

The theoretical capacity of the expeller wasdetermined using a modified form of theequation given by [15] as:

= 60 ( ) (8)Where, Qe is the theoretical capacity of theexpeller, Ds is the diameter of the screwthread, ds is the base diameter of thescrew shaft, Ps is the screw pitch, Ns is therotational speed of the screw (worm) shaft,is filling factor, and is the bulk densityof palm fruit. Substituting Ds = 60mm, ds= 30mm, Ps = 50mm, Ns = 150 rpm, =0.8 and = 913kg/m3 into Equation 8;hence Qe= 697.081Kg/h.

2.3.7 Design for the power requirement ofthe screw press

The power required to drive the screw presswas calculated using a modified from [15]as:P = 4.5QF (9)Where, Pe is the power required to drive thescrew press, Qv is the volumetric capacity ofthe worm shaft, Is is length of worm shaft, is the acceleration due to gravity, and F isthe material factor. Substituting Qv =0.3965m3/h, Is = 440mm, =9.81m/s2, =913kg/m3, and F =0.4 into equation 9, hencePe=2.8125kw.



IJSER

The power of the electric motor to drive thescrew press was estimated using theequation given by [15] below as:P = (10)where,Pm is the power of the electric motorand is the drive efficiency. Given that=75% or 0.75, hence, Pm=3.75kw or 5hp.Therefore, a 5hp three-phase electric motorwas selected was to drive the screw press.

2.4. Material Selection and Fabrication ofthe Machines Components

The hopper was fabricated from a standardlength of 1.5 mm thick mild steel sheet. Fourpiece of dimension 340x330x350mm were cutfrom the mild and welded together to formhopper. The worm shaft was fabricated from amild steel rod of diameter 50 mm and length900 mm which was machine on the lathe to30mm base (shaft)diameter. Thereafter, thescrew thread was machined at a decreasingscrew depth from 25 mm to 5 mm therebyforming a tapered screw conveyor of nine screwturns. The barrel was fabricated from a mildsteel pipe of 166 mm internal diameter, 10 mmthickness and 850 mm long which was cut andmachined to 650 mm length. Usingoxyacetylene flame, a slot of 50x50 mm wasmade on the upper side of the barrel for thehopper base. Holes were made on the lowerportion of the barrel to serve as drainagechannels for the expelled oil. The main framewas made from an angle iron of dimension50x50x40 mm which was cut to the requireddimensions and welded together. Fabricationprocess included: marking out, machining,cutting, joining, drilling and fitting. Theworkshop tools and machines used included:scriber, steel rule, and compass, Centre punch,grinding machine, lathe machine, oxy-acetylenegas, saw frame and blade for cutting andwelding machine for joining. The specificationof construction materials is in table 1.TABLE 1: Materials for construction of thescrew press and their specifications

2.5. Materials and Methods Used forTesting

Palm fruit bunches of tenera variety wereobtained from teaching and research farm,FUTA. The fresh palm fruit were cleaned,weighed and prepared for oil extraction. Thescrew press was set into operation andknown weights of each were fed into themachine through the feeding hopper. Theworm shaft conveyed, squeezed and pressedthe mash in order to extract the oil. Thefresh fruit bundles, the oil extracted and theresidual cake (kernel and fiber mixture)were collected and weighed separately.From the values obtained, oil extracted ratio(oil yield), oil extracted efficiency, materialdischarge efficiency and machines capacitywere calculated according [1] as :

=

% (11)

=

% (12)

Materials Specifications Quantity

Mild steelsheet

1.5 mm thickness,standard size

2

Mild steelrod

100mm, length900mm

1

Mild steelpipe

166m, thickness 10 mm,length 650 mm

1

Screw bolt 45 mm x 320 mm 1Mild steelangle iron

38 mm x 4 mm standardlength

1

Roller bearing 30 mm 2Cast ironpulley

50 mm,125 mm 2

Cast ironpulley

200 mm 2

V-belt B 65 3Bolts & nuts 24 mm x 50 mm

30 mm x 50 mm19 mm x 30 mm

4412

Weldingelectrode

Guage 12 mild steel 2 packets



IJSER

=

% (13)

=

(14)

Where, OER, OEE, MDE AND MCP are oilextraction ratio (oil yield),oil extractionefficiency, material discharge efficiency in% and machine capacity in tons ofbunches/hr, WOE, WFFB, AEO, WCO, WRCand T are weights of oil extracted, fresh fruitbunches, amount of oil expected, crude oil,residual cake and time in hours. Each testwas carried out in triplicates.

3. RESULTS AND DISCUSSION OFTESTING

The average oil extraction ratio, oilextraction efficiency, material dischargeefficiency and machine capacity were17.90,79.56, 96.92% and 0.532 tons of bunches/hrrespectively. The machine operatessmoothly during testing without frequentjamming. The result obtained from the testsshows that the oil palm screw presseffectively extract the crude oil from thedigested palm fruit (mash).

4. CONCLUSION

An oil palm screw press was designed,constructed and tested for palm fruitextraction. The screw press was simpleenough for local fabrication, operation,repair and maintenance. Powered by a 5hpthree-phase electric motor, the screw presshas average oil extraction ratio and oilextraction efficiency of 17.90 and 79.56%respectively from palm fruit with aproduction cost of USD650. The screwpress can be used for small scale palmfruit oil extraction in the rural and urbancommunities. A palm fruit oil processingplant based on this technology can provideemployment for at least two persons at thesame time provide palm oil at affordablecosts for rural and urban communities.

APPENDIX A: Isometric Drawing of theOil Palm Screw Press Developed

Isometric drawing (front view).

Isometric drawing (plan view).

Isometric drawing (side view).



IJSER

5. REFERENCES [1]. PORIM in Palm Oil Factory ProcessHandbook Part 1, General Description of thePalm Oil Research Institute of Malaysia,1985; p. 39, 55.

[2]. Babatunde O. O. Ph.D Thesis,Sterilization and mechanical digestion of oilpalm fruit, Obafemi Awolowo University,Ile-Ife, Nigeria,1987.

[3].USDA in Palm Oil Production byCountry in 1000 MT, available athttp://www.usda.gov/ , 2011 retrieved 4thApril, 2010.

[4]. Taiwo K. A., Owolarafe O. K., Sanni L.A., Jeje J. O., Adeloye K., and Ajibola O.O.Technological assessment of palm oilproduction in Osun and Ondo States ofNigeria, 2000; Technovation, 20, 215-223.

[5]. Owolarafe O. K., Faborode M. O., &Ajibola O. O. Comparative evaluation ofthe digester-screw press and hand-operatedhydraulic press for oil palm fruitprocessing, Journal of Food Engineering,U. K., Vol. 52, PP. 249255, 2002.

[6]. Owolarafe O.K., Olabige M.T., andFaborode M.O. Macro-structuralcharacterization of palm fruit at differentprocessing conditions J. Food Eng., Vol.79, PP. 31-36, 2007.

[7]. Ademosun O. C. The challenges ofDevelopment of Agricultural Engineeringpractice within a democratic system inNigeria, Proceedings of COREN 11thEngineering Assembly held at theInternational Conference center, Abuja,Nigeria, PP. 36-50, 2002.

[8]. Olukunle O. J. Ph.D. Thesis,Development of an Indigenous Combine

Harvester, Federal University OfTechnology, Akure, Nigeria, 2002.

[9]. Ademosun O. C., Adewumi B. A.,Olukunle O. J. and Adesina A. A.Development of Indigenous Machines forWeeding and Grain Harvesting, FUTAJournal of Engineering and EngineeringTechnology, Vol. 3 No. 2, PP. 77-84, 2003.

[10]. Agbetoye L. A. S. The UnsolvedProblem of Cassava HarvestingMechanization: Why and How? An InvitedPaper Presented at the technical session ofthe Bi Monthly Meeting of the Ondo StateBranch of the Nigerian Institution ofAgricultural Engineers, held at the RufusGiwa Polytechnic, Owo, Ondo State, 11thJanuary, 2004.

[11]. Shigley, J. E., & Mischke, C. R.Mechanical engineering design, 6th edition,New York: McGraw-Hill Companies, Inc.,Chapter 18, 2001.

[12]. Khurmi, R. S., & Gupta, J. K. Atextbook of machine design, 14th edition,New Delhi: Eurasia Publishing House(PVT) Ltd., Chapters 7 & 14, 2008.

[13]. Hall A.S, Holowenko A.R. andLaughlin H.G. Theory and problems ofmachine design, 51 metric edition, schaumsoutline series, McGraw-Hill book company,New-York, America PP. 113-130, 1980.

[14]. Ryder G. H. Strength of materials, 3rdedition, London: Macmillan Publishers Ltd.,Chapter 15, 1985.

[15]. Onwualu A. P., Akubuo C. O., &Ahaneku I. E. Fundamentals ofengineering in agriculture, 1st editionLagos: Immaculate Publications Ltd., 2006.



IJSER

Documents

Researchpaper Development of a Screw Press for Palm Oil Extraction