DEPARTMENT OF CHEMICAL ENGINEERING,AHMADU BELLO UNIVERSITY, ZARIA

EFFECT OF SIZE REDUCTION ON THE EXTRACTION OF PALM KERNEL OIL

AN INDUSTRIAL PROJECT

PRESENTED

TO

THE DEPARTMENT OF CHEMICAL ENGINEERING

BY

JOY OBOMANU

U09CE1002

MARCH, 2014EFFECT OF SIZE REDUCTION ON THE EXTRACTION OF PALM KERNEL OIL

AN INDUSTRIAL PROJECT

BY

JOY OBOMANU

U09CE1002

IN PARTIAL FULFILMENT OF THE REQUIRMENTFOR THE AWARD OF BACHELOR OF ENGINEERING (B.ENG) IN CHEMICAL ENGINEERING,

AHMADU BELLO UNIVERSITY, ZARIA.

MARCH, 2014.ABSTRACTRaw materials often occur in sizes that are too large to be used and, therefore, they must be reduced in size. The objective of this paper is to investigate the effect of size reduction on the extraction of palm kernel oil. The work involved 3 unit operational machines vis-viz: hammer mill, breaker and flakers. In addition to the unit operations, laboratory analysis was carried out to evaluate the particle size, flake thickness and oil content of the raw material from the various machines. Results of analysis showed particle size distribution based on the over size (using a 3mm sieve size) for the hammer mill in the range of 18 - 22%, the breaker 14 - 16% and the flakers 2-4%;flake thickness 0.25 -0.40mm; % oil content was 30- 33, 33-35 and 37- 41% respectively for hammer mill ,breakers and flakers. It was established that the amount of extractable oil increases with decreasing particle size of the feed stock as a result of an increase in surface area. The results of this study suggest that proper size reduction is necessary in order to achieve optimum yield from the extraction process.

CHAPTER ONE

INTRODUCTION

The pharmaceutical, chemical, and food industries all depend on particle size reduction. Its uses and facilitate the separation of oil from grain components. There are a number of reasons why particle size and particle size distribution is so important in today processing plants. Particle size reduction and distribution improves flow-ability of the material (Adrianna Norton 2012). Weight control is another reason why particle size reduction and distribution is so important. Particle size reduction and distribution is important because smaller particles are more sensitive to over-compression. The small particles are less able to lock together during the compaction process. Compressibility improves with an increased particle size and decreases as particles become smaller. As well, higher percentages of small particles require increased quantities of lubricant. Small particles decrease disintegration time and increase dissolution. Larger particles normally are able to better lock together causing friability. Particle size reduction is an aspect that is of major importance and the economic impact of particle size can be significant. Fortunately, innovations in particle size reduction technology has led to extremely efficient methods of particle size reduction and distribution using technologically advanced grinding equipment such as fine grinding. The advanced devices take up minimal space in the plant, reduces particle dust, decreases wear on the machines, increases yields, and improves quality of the final product. The overall result is an improvement in production, productivity, and a more efficient and cost effective manufacturing process. However, shortcomings of conventional size reductions were obtained by flaking and the effect of flaking on the yield and quality of volatile oil was comparatively evaluated by scientists at Central Food Technological Research Institute (CFTRI), Mysuru, India for small batch size (200g) oil yield was found to be same (3.4%) for both ground and flaked samples. Many drawbacks associated with conventional method of grinding using hammer mill or plate such as clogging, rise in the temperature of the ground material and loss of volatile oil could be overcome by flaking pre-cooling of cumin seeds prior to flaking further improved the oil yield (Sowbhagya HB, Sathyandra Rao BV and Krishnamurthy N.J.Food Eng.2008,84(4),595-600. Size-reduction operation can be divided into two major categories depending on whether the material is a solid or a liquid. If it is solid, the operations are called grinding and cutting, if it is liquid, emulsification or atomization. All depend on the reaction to shearing forces within solids and liquids. The purpose of solvent plant extraction is to remove most of the oil contained in a seed. Extraction is conducted on prepared seeds or, generally in the case of high oil content seeds, the cakes obtained by the pre-pressing. An efficient extraction would need that every oil bearing cell of the material is in contact with the solvent. Hence an optimum size is absolutely essential for efficient extraction. The method of material preparation does vary from material to material depending upon its oil content and physical properties. In case of high oil content seeds like palm kernel it passes through, the well proven hammer mill, breaker, cooking & flaking before extraction. The most common equipment used in oil extracting industries include grinders and crushers. These equipment are of many types and classes and are discussed in detail in chapter two.1.1 PROBLEMS STATEMENTAn efficient Extraction would need that every oil bearing cell of the material is in contact with the solvent. In other words, the smooth preparation prior to main extraction is very vital to comply with this contact, the smaller the material size, the better the penetration of the solvent into the oil bearing cells, but too fine a size will prevent the solvent from percolation through the mass. Hence an optimum size is absolutely essential for efficient extraction.

1.2 OBJECTIVES To grind the palm kernel to a smaller size using the hammermill, breakers and flakers to obtain the size distribution of approximate proportion. To estimate the energy required for the grinding operation.

1.3 JUSTIFICATIONReduction of particle size is an important operation in many chemical and other industries. The important reasons for size reduction among others are: Easy handling Increase in surface area per unit volume Separation of entrapped components

1.4 SCOPE To determine particle size distribution in the Hammer mill To determine the particle size distribution in the breakers To determine the flakers thickness and particle size in the flakers

CHAPTER 2

2.0 LITERATURE REVIEW2.1 EXTRACTIONExtraction is a process whereby a mixture of several substances in the liquid phase is at least partially separated upon addition of a liquid solvent in which the original substances have different solubility.When some of the original substances are solids, the process is called leaching. In a sense, the role of solvent in extraction is analogous to the role of enthalpy in distillation. The solvent rich phase is called the extract, and the solvent poor phase is called the raffinate. The high degree of separation may be achieved with several extraction stages in series, particularly in the counter current flow. The simplest separation by extraction involves two substances and a solvent.2.1.1 Mechanisms of ExtractionIf the solute is uniformly distributed through the solid phase the material near the surface dissolves first to leave a porous structure in the solid residue. In order to reach further solute the solvent has to penetrate this outer porous region; the process becomes progressively more difficult and the rate of extraction decreases. If the solute forms a large proportion of the volume of the original particle, its removal can destroy the structure of the particle which may crumble away, and further solute may be easily accessed by solvent. In such cases the extraction rate does not fall as rapidly.In general, the following steps can occur in an overall liquid-solid extraction process; solvent transfer from the bulk of the solution to the solid; penetration or diffusion of the solvent into the pores of solid: dissolution of the solvent into the solute; solute diffusion to the surface of the particle; and solute transfer to the bulk of the solution. The various fundamental mechanisms and processes involved in these steps make it impracticable or impossible to describe leaching by any rigorous theory.Any one of the five basic processes may be responsible for limiting the extraction rate. The rate of transfer of solvent from the bulk solution to the surface and the rate into the solid are usually rapid and are not rate limiting steps, and the solution is usually so rapidly that it has only a small effect on the overall rate. However, knowledge of dissolution rates is sparse and the mechanism may be different in each solid. The overall extraction process is sometimes subdivided into general categories according to the main mechanisms responsible for the dissolution stages: (1) those operations that occur because of the solubility of the solute or its miscibility with the solvent, e.g., oilseed extraction, and (2) extraction where the solvent must react with a constituent of the solid material in order to produce a compound soluble in the solvent, e.g. the extraction of metals from metaliferous ores. In the former case the rate of extraction is most likely to be controlled by diffusion phenomena, but in the latter the kinetics of the reaction producing the solute may play a dominant role. (Martinez et al, 1968).2.1.2 Classification of ExtractionExtraction could be classified into two broad groups namely; expression and solvent extraction.Expression ExtractionIt could be carried out in oil expeller or hydraulic press. The oil expellers use uncooked meal whereas the hydraulic press use cooked meal. The expeller consists of a screw revolving inside a body, the clearance between the two adjustable roll. Stem connections are provided for heating the meal. In the hydraulic press the cooked meal is subject to a pressure of 35kg/m.s and as the oil starts flow it are gradually increased to 350kg/m.s. The oil cake contains 5-6 percents oil.Solvent ExtractionRecovery of oil from oil bearing materials by the use of suitable volatile solvent is a very advantageous method because of high yield compared with those obtained with mechanical process and the protein in the residual cake are not denatured.During the solvent extraction process oil bearing material after some preliminary operation are brought in contact with some suitable solvent. The solvent dissolves the oil present in cell of the material. Solvent is stripped off the miscella (solution of oil and solvent) and recycled. The de-oiled caked known as marc contains a very small quantity of oil but considerably amount of solvent which is recovery through dryer in vapor form is condensed for recycling. These solvent losses during the process become practically negligible.2.2 SOLVENTSolvent choice is determined by the chemical structure of the material to be extracted, and the rule that like dissolves like provides useful guidance. Thus vegetable oils consisting of triglycerides of fatty acids are normally extracted with hexane, where for free fatty acids, which are more polar than the triglycerides, more polar alcohols are used. Halogenated hydrocarbons and hexane are both widely used as solvents, and liquid carbon dioxide appears to be suitable for extracting flavor components from plants. Where a choice of solvent other than water exists on the ground of comparable solubility of the solute, the following criteria are likely to be considered.Solvent selectivity is intimately linked to the purity of the recovered extract, and obtaining a purer extract can reduce the number and cost of subsequent separation and purification operations. In aqueous extractions pH give only limited control over selectivity; greater control can be exercised using organic solvents. Use of mixed solvents, for example short- chain alcohols admixed with water to give a wide range of compositions, can be beneficial in this respect.2.3 EXTRACTORS2.3.1 Liquid-Solid ExtractorsExtractors are devices used in solid-liquid extraction to provide the compartments required for the contact between the oil bearing material and the solvent. They are broadly classified into two; batch and continuous extractors.2.3.2 Batch ExtractorsThe pot extractor is a batch extraction plant that offers the small scale processor the advantage of carrying out extraction and solvent recovery in one vessel. They are normally provided with agitation. They range from two to ten cubic meters in capacity.Another batch extractor type consists of a large horizontal drum mounted on rollers by means of which the drum can be rotated on its longitudinal axis. Inside the drum is a horizontal, perforated, metal strainer covered with filter mat, which extends the length of the drum and divides it into two compartments of different sizes. The larger compartment receives the charge of the material containing the oil through which solvent is percolated through the drain into smaller compartments by gravity, from which it is continuously pumped during drainage period until the oil content of the solid material is reduced to the barest minimum.2.3.3 The Diffuser BatteryThis is a semi batch extractor operating on a cyclical basis. The individual units in the battery are charged sequentially with solids to be extracted and the extracting liquor flow designed to provide apparent counter-current flow. The size of the individual units depends on factors related to mass balance, the contact time and the hydrodynamic behavior of the bed of the solid.2.3.4 Continuous ExtractorsThe continuous extraction process can be operated both counter-currently and co-currently. The counter-current is more widely used and its devices may operate on either percolation or the immersion principle, with the percolation rate of the solvent through the solid mass playing an important part in determining the choice.1. Percolation principle (the Rotocel extractor)In the rotocel extractor, the material to be extracted is fed continuously as slurry in the extracting solvent or as a dry feed to secto-shaped cells arranged round in horizontal rotor. The cells have perforated base to allow drainage of the solvent into stage from which it is pumped to the next cell on the counter-current principle. In the last cell, where fresh solvent is supplied, an extended discharge period is provided and thereafter the extracted solids are dumped.

Figure 2.1: Rotocol Extractor (Perry et al, 1997)2. Immersion PrincipleThe main advantage of immersion extraction is the ability to handle finely ground material since only the drainage rate must be considered, the operation is simpler. Immersion extraction may be used where percolation rate of the material to be extracted is too great for effective diffusion within the bed.2.3.5 The Bollman-Type ExtractorA typical Bollman-type extractor is shown in the diagram below which is a bucket elevator unit. Buckets with perforated bottoms are held on an endless moving belt. Dry flakes, fed into the descending buckets, are sprayed with partially enriched solvent (half miscella) pumped from the bottom of the column of ascending buckets. As the buckets rise on the other side of the unit, the solids are sprayed with a counter-current stream of the pure solvent. Exhausted flakes are dumped from the buckets at the top of the unit into a paddle conveyor; enriched solvent, the full miscella, is pumped from the bottom of the casing. Because the solids are unagitated and because the final miscella moves co-currently, the Bollman extractor permits the use of thin flakes while producing extract of good clarity. It is only partially a counter current device, however, and it sometimes permits channeling and consequent low stage efficiency. Perhaps for this reason, it is being replaced in the oil extraction industry.

Figure 2.2: Bollman-type extractor (Perry et al, 1997).

2.3.6 The Kennedy ExtractorThis type of extractor operates substantially as a percolator that moves the bed of solids through the solvent rather than the conventionally opposite. It comprises a nearly horizontal line of chambers through each of which in succession the solids being leached are moved by a small impeller enclosed in a section. There is an opportunity for drainage between stages when the impeller lifts solids above the liquid level before dumping them into the next chamber. Solvent flows counter currently from chamber to chamber. Because the solid are subjected to mechanical action somewhat more intense than in other types of continuous percolator, the Kennedy extractor is now little used for fragile materials such as flaked oil seeds.

Figure 2.3: Kennnedy extractor (Perry et al, 1997).2.3.7 The Bonotto ExtractorThis is a continuous dispersed-solids vertical-plate extractor which consists of a column divided into cylindrical compartments by equal-spaced horizontal plates. Each plate has a radial opening staggered 1800 from the openings of the plates immediately above and below it, and each is wiped by rotating radial blade. Alternatively, the plates may be mounted on a coaxial shaft and rotated past stationery blades. The solids, fed to the top plate, thus are caused to fall to each lower plate in succession. The solids fall as a curtain into solvent this flows upwards through the tower. They are discharged by a screw conveyor and compactor. Like the Bollman extractor, the Bonotto extractor has been virtually displaced by horizontal belt or tray percolators for the extraction of oil seeds.Figure 2.4: Bonotto extractor (Perry et al, 1997).

2.3.8 Hildebrandt Total-Immersion ExtractorHildebrandt total-immersion extractoris shown schematically in Figure2.5. The helix surface is perforated so that solvent can pass through counter currently. The screws are so designed to compact the solids during their passage through the unit. The design offers the obvious advantages of countercurrent action and continuous solids compaction, but there are possibilities of some solvent loss and feed overflow, and successful operation is limited to light, permeable solids. A somewhat similar but simpler design uses a horizontal screw section for leaching and a second screw in an inclined section for washing, draining, and discharging the extracted solids.

Figure 2.5: Hildebrandt total-immersion extractor (Perry et al, 1997).2.4 FACTORS AFFECTING THE EXTRACTABILITY OF OILSThe extraction of oils from oil bearing seeds is affected by various factors, some of which are discussed below.2.4.1 Temperature of ExtractionThe temperature of the extraction should be chosen for the best balance of solubility, solvent-vapor pressure, solute diffusivity, solvent selectivity, and sensitivity of product. Higher temperature favors the extraction of oils from the oil bearing materials. The solubility of the solvent increases drastically at higher temperatures, and consequently higher ultimate concentrations in the leached liquor is possible. The viscosity of the solvent is low and the diffusivity is higher at very high temperatures. This consequently gives higher diffusion coefficient and hence increase rate of extraction. However as the boiling point of the solvent is approached, oil yield tend to decrease since there will not be efficient diffusion of solvent into the oil cells and solubility of oil decreases due to loss of solvent as a result of higher evaporation and volatility (Treybal,1980). But higher temperatures have some effects on the quality of the oil, it reduces some of its vital component and it is easily oxidized.2.4.2 Particle SizeWhatever the mechanism, however, it is clear that the extraction process is favored by increased surface per unit volume of solid to be extracted and by decreased radial distances that must be traversed within the solids, both of which are favored by decreased particle size. The smaller the particle size, the larger is the surface to volume ratio. Fine solids on the other hand cause mechanical operating problems during extraction, slow filtration and drying rates and possible poor quality of solid product. The basis for an optimum particle size is established by these characteristics. Therefore crushing and grinding the material will greatly accelerate the extraction process since the soluble portions are made more accessible to the solvent. The efficiency of solvent extraction is a function of the contactable surface area of the oil bearing material (U.S. Patent, 4008210).2.4.3 Choice of SolventThe solvent selected will offer the best balance of a number of desirable characteristics: high saturation limit and selectivity for the solute to be extracted, capability to produce extracted material of quality unimpaired by the solvent, chemical stability under process conditions, low viscosity, low vapor pressure, low toxicity and flammability, low density, low surface tension, ease and economy of recovery from the extract stream, and price. These factors are listed in an approximate order of decreasing importance, but the specifics of each application determine their interaction and relative significance, and anyone can control the decision under the right combination of process conditions2.4.4 Moisture ContentThough it has not been very clear how moisture content of oil bearing materials affect extraction, very dry seeds or pulps cannot be effectively freed of their oil. Conditioning, that is drying the material to a certain moisture content may serve to make the material surface relatively lipophobic there by easing the transfer of oil from the material to the solvent. Also conditioning increases the void space. Preconditioning the material before the extraction process to about 6-9% helps to increase the surface to volume ratio to maximize the mass transfer of oil and solvent (U.S. Patent, 4008210).

2.4.5 Time of ExtractionSince the extraction of oil is a diffusion process, the longer the time, the more would be extracted, since the diffusion time is increased. The length of time that the extraction is carried out is dependent upon a number of factors, but principally is dependent upon the length of time necessary to extract the maximum amount of oil from the vegetable material. Therefore the longer this time, the more oil extracted since the diffusing time is increased as given by the equation below:

...........................................(2.1)

2.5 GRINDING AND CUTTING Grinding and Cutting reduce the size of solid materials by mechanical action, dividing them into smaller particles. Perhaps the most extensive application of grinding in the food industry is in the milling of grains to make flour, but it is used in many other processes, such as in the grinding of corn for manufacture of corn starch, the grinding of sugar and the milling of dried foods, such as vegetables.Cutting is used to break down large pieces of food into smaller pieces suitable for further processing, such as in the preparation of meat for retail sales and in the preparation of processed meats and processed vegetables. In the grinding process, materials are reduced in size by fracturing them. The mechanism of fracture is not fully understood, but in the process, the material is stressed by the action of mechanical moving parts in the grinding machine and initially the stress is absorbed internally by the material as strain energy. When the local strain energy exceeds a critical level, which is a function of the material, fracture occurs along lines of weakness and the stored energy is released. Some of the energy is taken up in the creation of new surface, but the greater part of it is dissipated as heat. Time also plays a part in the fracturing process and it appears that material will fracture at lower stress concentrations if these can be maintained for longer periods. Grinding is, therefore, achieved by mechanical stress followed by rupture and the energy required depends upon the hardness of the material and also upon the tendency of the material to crack - its friability. The force applied may be compression, impact, or shear, and both the magnitude of the force and the time of application affect the extent of grinding achieved. For efficient grinding, the energy applied to the material should exceed, by as small a margin as possible, the minimum energy needed to rupture the material. Excess energy is lost as heat and this loss should be kept as low as practicable.The important factors to be studied in the grinding process are the amount of energy used and the amount of new surface formed by grinding.2.5.1Energy Used in GrindingGrinding is a very inefficient process and it is important to use energy as efficiently as possible. Unfortunately, it is not easy to calculate the minimum energy required for a given reduction process, but some theories have been advanced which are useful.These theories depend upon the basic assumption that the energy required to produce a change dL in a particle of a typical size dimension L is a simple power function of L:dE/dL = KLn .(2.2)Where dE is the differential energy required, dL is the change in a typical dimension, L is the magnitude of a typical length dimension and K, n, are constants.Kick assumed that the energy required to reduce a material in size was directly proportional to the size reduction ratio dL/L. This implies that n in eqn. (2.2) is equal to -1. IfK = KKfcwhere KK is called Kick's constant and fc is called the crushing strength of the material, we have:dE/dL = KKfcL-1which, on integration gives:E = KKfc loge(L1/L2) (2.3) Equation (2.3) is a statement of Kick's Law. It implies that the specific energy required to crush a material, for example from 10 cm down to 5 cm, is the same as the energy required to crush the same material from 5 mm to 2.5 mm.Rittinger, on the other hand, assumed that the energy required for size reduction is directly proportional, not to the change in length dimensions, but to the change in surface area. This leads to a value of -2 for n in eqn. (2.2) as area is proportional to length squared. If we put:K = KRfc SodE/dL = KRfcL-2Where KR is called Rittinger's constant, and integrate the resulting form of eqn. (2.2), we obtain:E = KRfc(1/L2 1/L1) ..(2.4)Equation (2.4) is known as Rittinger's Law. As the specific surface of a particle, the surface area per unit mass, is proportional to 1/L, eqn. (2.4) postulates that the energy required to reduce L for a mass of particles from 10 cm to 5 cm would be the same as that required to reduce, for example, the same mass of 5 mm particles down to 4.7 mm. This is a very much smaller reduction, in terms of energy per unit mass for the smaller particles, than that predicted by Kick's Law.It has been found, experimentally, that for the grinding of coarse particles in which the increase in surface area per unit mass is relatively small, Kick's Law is a reasonable approximation. For the size reduction of fine powders, on the other hand, in which large areas of new surface are being created, Rittinger's Law fits the experimental data better.Bond has suggested an intermediate course, in which he postulates that n is -3/2 and this leads to E = Ei (100/L2)1/2[1 - (1/q1/2)] . (2.5)Bond defines the quantity Ei by this equation: L is measured in microns in eqn. (2.5) and so Ei is the amount of energy required to reduce unit mass of the material from an infinitely large particle size down to a particle size of 100 mm. It is expressed in terms of q, the reduction ratio where q = L1/L2.Note that all of these equations [eqns. (2.3), (2.4), and (2.5)] are dimensional equations and so if quoted values are to be used for the various constants, the dimensions must be expressed in appropriate units. In Bond's equation, if L is expressed in microns, this defines Ei and Bond calls this the Work Index.The greatest use of these equations is in making comparisons between power requirements for various degrees of reduction.

So the motor would be expected to have insufficient power to pass the 50% increased throughput, though it should be able to handle an increase of 40%.

2.5.2 New Surface Formed by GrindingWhen a uniform particle is crushed, after the first crushing the size of the particles produced will vary a great deal from relatively coarse to fine and even to dust. As the grinding continues, the coarser particles will be further reduced but there will be less change in the size of the fine particles. Careful analysis has shown that there tends to be a certain size that increases in its relative proportions in the mixture and which soon becomes the predominant size fraction. For example, wheat after first crushing gives a wide range of particle sizes in the coarse flour, but after further grinding the predominant fraction soon becomes that passing a 250 mm sieve and being retained on a 125 mm sieve. This fraction tends to build up, however long the grinding continues, so long as the same type of machinery, rolls in this case, is employed.The surface area of a fine particulate material is large and can be important. Most reactions are related to the surface area available, so the surface area can have a considerable bearing on the properties of the material. For example, wheat in the form of grains is relatively stable so long as it is kept dry, but if ground to a fine flour has such a large surface per unit mass that it becomes liable to explosive oxidation, as is all too well known in the milling industry. The surface area per unit mass is called the specific surface. To calculate this in a known mass of material it is necessary to know the particle-size distribution and, also the shape factor of the particles. The particle size gives one dimension that can be called the typical dimension, Dp, of a particle. This has now to be related to the surface area.We can write, arbitrarily:Vp = pDp3andAp= 6qDp2.where Vp is the volume of the particle, Ap is the area of the particle surface, Dp is the typical dimension of the particle and p, q are factors which connect the particle geometries.(Note subscript p and factor p)For example, for a cube, the volume is Dp3 and the surface area is 6Dp2; for a sphere the volume is (p/6)Dp3 and the surface area is pDp2 In each case the ratio of surface area to volume is 6/Dp.A shape factor is now defined as q/p = L (lambda), so that for a cube or a sphere L = 1. It has been found, experimentally, that for many materials when ground, the shape factor of the resulting particles is approximately 1.75, which means that their surface area to volume ratio is nearly twice that for a cube or a sphere.

The ratio of surface area to volume is:Ap/Vp =( 6q/p)Dp = 6L/Dp .. (2.6)

and so Ap= 6q Vp/pDp = 6l(VP/DP) If there is a mass m of particles of density rp, the number of particles is m/rpVPeach of area Ap.So total area At = (m/rpVP) x ( 6qVp/pDP) = 6qm/rppDp= 6Lm/rDp(2.7)Where At is the total area of the mass of particles. Equation (2.7) can be combined with the results of sieve analysis to estimate the total surface area of a material.2.6 HAMMER MILLHammer crusher is used for crushing medium hard materials with weak abrasiveness, and the compression strength of the materials to be crushed should not exceed 100MPa, and the water content should be lower than 10%. The materials that can be crushed by hammer crusher include: palm kernel, hard nut, coal, salt, chalk, gypsum Features: Wear resistance Easy maintenance Compact structure Hammer crusher, which is also called hammer mill or hammer crusher machine, is widely used for crushing the medium hard and crisp materials in mine, cement, coal, metallurgy, building material, highway and chemical industry among others. Hammer crusher is composed of machine box, rotor, hammer, impacting lining board and screen board. According to the requirement of the customers, this equipment can adjust the gap between the grating bars to change the discharging granularity.2.6.1Characteristics of Hammer mill 1. The working hammer adopts new technology for casting, so that it is wear resistant and impact resistant. 2. The granularity can be adjusted according to the requirement of the customers. 3. Hammer crusher has a sealed structure which solves the problems of powder dust pollution in the crushing workshop and ash leakage of the machine. 4. This crusher has the advantages of attractive appearance, compact structure and few easy-wearing parts and convenient maintenance. In a hammer mill, swinging hammerheads are attached to a rotor that rotates at high speed inside a hardened casing.

2.6.2 Working PrincipleThe electromotor drives the rotor to rotate with high speed in the crushing chamber. The materials are fed into the machine from the upper feeding mouth and are crushed under the hitting, impacting, cutting and grinding of the hammer which is moving with high speed. On the bottom of the rotor, there is sieve plate and the crushed materials that is smaller than the screen size are discharged from the sieve plate, and the coarse particles bigger than the screen size are retained on the sieve plate to be hit and ground again by the hammer and finally be discharged from the machine from the sieve plate

2.7 BREAKERSIn the grinding process, materials are reduced in size by fracturing them. The mechanism of fracture is not fully understood, but in the process, the material is stressed by the action of mechanical moving parts in the grinding machine and initially the stress is absorbed internally by the material as strain energy. When the local strain energy exceeds a critical level, which is a function of the material, fracture occurs along lines of weakness and the stored energy is released. Some of the energy is taken up in the creation of new surface, but the greater part of it is dissipated as heat. Time also plays a part in the fracturing process and it appears that material will fracture at lower stress concentrations if these can be maintained for longer periods. Grinding is, therefore, achieved by mechanical stress followed by rupture and the energy required depends upon the hardness of the material and also upon the tendency of the material to crack - its friability. The force applied may be compression, impact, or shear, and both the magnitude of the force and the time of application affect the extent of grinding achieved. For efficient grinding, the energy applied to the material should exceed, by as small a margin as possible, the minimum energy needed to rupture the material. Excess energy is lost as heat and this loss should be kept as low as practicable.

2.8 FLAKERSProper kernel pre-treatment is necessary to efficiently extract the oil from the kernels. The feed kernels must first be cleaned of foreign materials that may cause damage to the screw-presses, increasing maintenance costs and down time, and contamination of products. Magnetic separators commonly are installed to remove metal debris, while vibrating screens are used to sieve sand, stones or other undesirable materials.A swinging hammer grinder, breaker rolls or a combination of both then breaks the kernels into small fragments. This process increases the surface area of the kernels, thus facilitating flaking. The kernel fragments subsequently are subjected to flaking in a roller mill. Roller mills are similar to roller crushers, but they have smooth or finely fluted rolls, and rotate at differential speeds. They are used very widely to grind flour. Because of their simple geometry, the maximum size of the particle that can pass between the rolls can be regulated. If the friction coefficient between the rolls and the feed material is known, the largest particle that will be nipped between the rolls can be calculated, knowing the geometry of the particles.A large roller mill can consist of up to five rollers mounted vertically above one another, each revolving at 200-300 rpm. The thickness of kernel cakes is progressively reduced as it travels from the top roller to the bottom. This progressive rolling initiates rupturing of cell walls. The flakes that leave the bottom nip are from 0.25 to 0.4 mm thick.The kernel flakes are then conveyed to a stack cooker for steam conditioning, the purpose of which is to:i. Adjust the moisture content of the meal to an optimum levelii. Rupture cell walls (initiated by rolling) iii. Reduce viscosity of oiliv. Coagulate the protein in the meal to facilitate separation of the oil from protein materials

CHAPTER THREE3.1 INTRODUCTIONThis chapter contains the list of materials, apparatuses and equipment used to carry out the experiments.

3.2 MATERIALS Palm kernel Petroleum

3.3 EQUIPMENT

Figure 1. Grinders: (a) hammer mill, (b) plate mill

Figure 2. Crushers: (a) jaw, (b) gyratory

CHAPTER FOURMETHODOLOGY4.1 INTRODUCTIONThis chapter consists of procedures employed in the work and comprises of the following;4.2 PARTICLE SIZE DISTRIBUTION (%)Five samples of crushed palm kernel were drawn over eight hours from the three machines (hammer mill, breakers and flakers) and kept separately in a clean stainless vessel after which it was properly mixed together.500g each of the mixed samples were weighed and sieved through a 3mm sieve. The Weight of particles retained and those that passed through the sieve were recorded and used in calculating % particle size distribution.Calculation:(a) Particle size retained (%), = Particles abovex 100 Wt of sample (b) Particle size gain (%) = Particle belowx 100Wt of sample

4.3 FLAKE THICKNESS (mm)From the samples drawn over eight hours, flaked samples were taken out and analyzed for thickness using a micrometer screw gauge. Results were recorded in mm.

4.4 OIL CONTENT DETERMINATION (%)The AOCS official method Ab 3-49 was followed. This method determines the substance extracted by petroleum ether under the condition of the test. Apparatus and reagent include soxhlet extraction unit, thimble, cotton wool and petroleum ether.Procedure.Various samples of the palm kernel drawn from the machines were dried in a forced draft oven for 20min to achieve a moisture content of 10%. Drying time depends on the original moisture in the kernel. Ideally the moisture should be from 6-9%. Dried sample should be cooled to room temperature before use.2-5g each of the sample was weighed in to an extraction thimble after which a piece of absorbent cotton is placed on top of the thimble to distribute the solvent as it drops on the sample.About 100g petroleum ether was put into a weighed receiving flask and the apparatus set for four hours. At the end of time, the extraction thimble is removed from the butt tube and petroleum ether evaporated.The receiving flask and oil extracted were further dried in an air oven to remove any residual solvent left. It was then cooled in a desiccator and weighed to obtain the oil content.

Calculations. oil content,% = wt of oil.g x 100wt of sample.g

PARTICLE SIZE RETAINED (%)

FLAKE THICKNESS (mm)

OIL CONTENT DETERMINATION (%)Figure 4.1 Block Diagram Of The Prcocedure.

CHAPTER 5 RESULT AND DISCUSSION5.1 INTRODUCTION In this chapter the results obtained after following the procedure detailed in chapter four are displayed and discussed in depth.5.2 RESULTSTable 5.1: Particle Size Retained (%), Flake Thickness And Oil Content DeterminationSampleHAMMER MILLBEAKERsFLAKERS

% RetainedFlake ThicknessOil Content% RetainedFlake ThicknessOil Content% RetainedFlake ThicknessOil Content

118.00.3330.013.6 0.2233.03.30.2037.0

217.90.2832.414.00.2434.82.00.2437.8

321.60.3933.014.50.3835.04.20.2439.4

422.00.4133.016.20.4034.74.00.2041.0

515.30.4532.915.20.4535.03.30.2040.6

Table 5.1 present the particle size distribution of the three different unit operations involved with size reduction process in percentage based on the over-size, the thickness of the flakes from the three different unit operations and the oil content determination of the various samples from the three different unit.

Figure 5.1 present the particle size distribution of the three different unit operations involved with size reduction in percentage, while Figure 5.2 present the thickness of the flakes from the three different unit operations and Figure 5.3 present the oil content of the various samples from the three different unit.

Particle Size RetainedFigure 5.1: A Bar Chart representation of the Particle DistributionFigure 5.1 shows the particle size distribution of five samples collected during the size reduction process from the three units. As expected, the sample from the Hammer Mill had the largest size, followed by the sample from the Breaker while the sample from the Flakers was the smallest.

Figure 5.2: A Bar Chart representation of the Flake ThicknessFigure 5.2 shows the Flake thickness of the five samples collected. As expected, the sample from the Hammer Mill had the largest thickness, followed by the sample from the Breaker while the sample from the Flakers was the thinnest.

Figure 5.3: A Bar Chart representation of the Oil ContentFigure 5.3 present the oil content of the five samples collected. As expected the sample from the Hammer Mill had the least amount of oil extracted while the Flaker had the highest amount of oil extracted.

Figure 5.4: A graph representation on particle size distributionPlot of oil content against corresponding particle size distribution shown in Figure 5.4 shows that as the particle size distribution decreases the amount of oil extracted increases, this is as a result of increase in surface area with decrease in particle size distribution.

Figure 5.5: A Graph representation on flake thickness on oil extractionSimilarly Figure 5.5 shows the effect of flake thickness on the extraction process of oil. As expected with decreasing flake thickness the total effective surface area increases, hence, the amount of extracted oil increases.Generally with decreasing particle size, the effective surface area exposed for the extraction process increases thereby increasing the relative yield of extracted oil from the feed stock. Flaking is a promising alternate to conventional size reduction method. Flaking resulted to increase in the yield of oil.

CHAPTER 66.1CONCLUSIONParticle size reduction is an aspect that is of major importance and the economic impact of particle size can be significant. Fortunately, innovations in particle size reduction technology has lead to extremely efficient methods of particle size reduction and distribution using technologically advanced grinding equipment such as fine grinding. The advanced devices take up minimal space in the plant, reduces particle dust, decreases wear on the machines, increases efficient yields, and improves quality of the final product. The overall result is an improvement in production, productivity, and a more and cost effective manufacturing process.

6.2 RECOMMENDATIONThe amount of oil extracted from oilseeds is dependent to a large extent on the particle size to which the oilseeds are ground. In this case, the grinding procedure should be strictly followed as specified. It is therefore, recommended that proper size reduction be carried out before oil extraction from any oil bearing seed.

CERTIFICATION

This is to certify that this research work titled EFFECT OF SIZE REDUCTIONON THE EXTRACTION OF PALM KERNEL OIL has been read and approved having satisfied the partial requirement for award of Bachelor of Engineering in Chemical Engineering in Ahmadu Bello University, Zaria.

DR.JAJU.MUHAMMED DateProject Supervisor

. DR.I.A.MOHAMMED-DABO DateHead Of Department

DECLARATIONThis is to certify that this research work titled EFFECT OF SIZE REDUCTIONON THE EXTRACTION OF PALM KERNEL OIL was carried out by Obomanu Joy Titi under the supervision of Dr.Jaju.Muhammed, for partial fulfillment of the award of Bachelor of Engineering (B.Eng) Chemical Engineering in Ahmadu Bello University, Zaria and has not been presented anywhere else for award of degree and all literature cited have been dully acknowledged.

Obomanu Joy Titi

DEDICATIONI delicate this project to the Almighty God, my sweet mum and her beloved sister Mrs.Racheal Kalio