Pelleting
Handbook
A Guide for
Production Staff
in the Compound Feed
Industry
John Payne, Wolter Rattink,
Ted Smith and Tom Winowiski
The
SECTION Page No.
1 INTRODUCTION
1.1 Why do we Condition and Pellet? 5
1.2 Terminology 6
1.2.1 Definitions of animal feedstuffs 6 1.3 History and Principles of Pelleting 8
2 OBJECTIVES IN PELLETING
2.1 Pellet Quality 11
2.2 Pelleting Efficiency 11
3 PELLETING ADVICE
3.1 Meal Conditioning (short term) 13
3.1.1 Horizontal barrel type conditioner 13
3.2 Meal Conditioning (long term) 14
3.2.1 Double pelleting 15
3.2.2 Expander systems 15
3.3 Pellet Press 17
3.3.1 Pre-start-up procedure 17
3.3.2 Start-up procedure (conventional barrel type) 17
3.3.3 To stop pelleting operations 18
3.3.4 Greasing of bearings 19
3.3.5 Die selection 19
3.3.6 Starting new dies 19
3.3.7 Die care 20
3.3.8 Die changing 20
3.3.9 Roll design 21
3.3.10 Roller setting (manual) 21
3.3.11 Roller adjustment (remote) 22
3.3.12 Knife setting 22
3.3.13 Fat application 23
3.4 Pellet Cooler 25
3.4.1 Vertical coolers 25
3.4.2 Horizontal belt coolers 26
3.4.3 Counterflow-bunker coolers 27 3.5 Crumblers 28 3.6 Sifters 29 4 MEAL CONDITIONING 4.1 Grist Spectrum 30 4.2 Steam Conditioning 30
4.3 Pipe Sizes and Steam Velocity 30
5 PRODUCTION GUIDELINES
5.1 Ruminant Feeds 33
5.2 Concentrates 34
This Handbook is dedicated to everyone who is involved in managing or operating a plant for the manufacture of pelleted feeds, anywhere in the world. It is no substitute for your own experience and knowledge, and those of your colleagues, but it can perhaps add to it.
The material contained in the Pelleting Handbook is based on the experience of the authors and their colleagues at
Borregaard LignoTech. This is a team which has many years’ experience of pelleting many different kinds of feeds in many different kinds of feedmills – both old and new – in many different countries. The Handbook is therefore part of Borregaard LignoTech’s strategy of helping their customers through "expertise, service and partnership".
This Handbook was first published under the Borregaard name in 1991. The aim of this new edition is to help feed producers in all five continents. This is an ambitious objective, because of the wide variation in processing conditions and raw materials which might be encountered, but we feel the task is fulfilled in a systematic and practical way. We therefore believe this Handbook will succeed in filling a real need, and prove itself to be of immense value worldwide.
The authors wish to acknowledge the help of colleagues, associates and friends in the industry, whose advice and assistance have proved invaluable in the preparation of this handbook, in particular Mr. Ian Buick for illustrations.
Acknowledgement
Contents
Foreword
World production of pelleted compound feeds continues to expand in order to satisfy an industry of great and growing importance, supplying balanced rations so essential for the production of meat, milk, fish and eggs.
The need for efficient and hygienic feed production demands the vast majority of compound feed to be pelleted.
Conditioning of the mixed meal prior to pelleting is an essential part of the process.
1.1
Why do we Condition and Pellet?
Reasons for conditioning and pelleting are many; the chart below shows the most generally recognised advantages.5.3 Pig Feeds 34
5.4 Poultry Feeds 35
6 RAW MATERIAL CHARACTERISTICS
6.1 Why Raw Materials Affect Pelleting 37 6.2 Raw Materials – Physical and Nutritional Factors 37
7 BORREGAARD’S LIGNIN PELLETING PERFORMANCE ENHANCERS
7.1 Advantages of Borregaard’s Lignin PPEs 43
7.2 Pelleting Trial Procedures 43
7.3 Problem Solving from Trial Format 48
7.3.1 Broken steam regulator 48
7.3.2 Incorrect set-up of steam system 48
7.3.3 Overtaxed boiler 49
7.3.4 Mill supplied by surge bin 49
7.3.5 Oversized feeder screws 49
7.4 Borregaard Lignin PPEs 50
7.4.1 Packaging 50
7.4.2 Mill intake and storage 50
7.4.3 Application in the mill 50
7.4.4 Accidental spillages at the mill 51
8 TROUBLE SHOOTING 8.1 Production 52 8.1.1 Conditioning 52 8.1.2 Pellet press 53 8.1.3 Dies 55 8.1.4 Cooling 55 8.2 Problem Pellets 56
8.2.1 Cracks at one end or down one side 56
8.2.2 Horizontal cracks 56
8.2.3 Vertical cracks while cooling 57
8.2.4 Cracks from a single point 58
8.2.5 Mis-shapen pellets 58
8.2.6 Short ends 59
8.2.7 Whiskery pellets 59
9 QUALITY CONTROL METHODS
9.1 Durability (Pneumatic) Pellet Testers 60
9.1.1 The Borregaard LT 60
9.1.2 The Borregaard LTA 60
9.1.3 The Borregaard LTOL 61
9.2 Durability (Mechanical) Pellet Testers 62
9.2.1 Tumbling can (ASAE) method 62
9.3 Hardness 62
9.4 Evenness of Length 63
9.5 Percentage of Dust 63
9.6 Guideline Recommendations 63
10 CONVERSION TABLES
10.1 General Conversion Factors 64
10.2 Steam Pressures 65 10.3 Temperatures 66 Effects of conditoning Effects of pelleting Benefits for compounder and farmer Increased bulk density Prevents 'de-mixing' of ingredients Increased feed intake Improved digestibility Improved nutritional quality of ration and increased profitability for farmer More cost efficient food production therefore increased profitability for compounder Improved efficiency of food production Reduces waste on farm Easier formulation changes without rejection Stock cannot 'select' ingredients Allows drug additions without risk of inaccurate dosage Improved flow and metering characteristics Reduces transport costs Facilitates bulk transport and storage
Kills bacteria e.g. salmonella
Introduction
1
1.2
Terminology
For the purposes of this Handbook you will see that we have used the term pellets for all compressed compound feeds of whatever size. Compound feed producers use a variety of names, including pellets, cubes, pencils, cake, cobs, shilfers, nuts, slabs and rolls.
1.2.1 Definitions of Animal Feedstuffs
(Courtesy HGM Publications, "Digest of Feed Facts and Figures") The following are not intended to be legal definitions but simply an indication as to what is meant by various terms in the compound feed industry.
Roughages. Fibrous ingredients suitable for ruminants, generally produced on the farm, eg. silage, hay, grass. Compound Feeds. A number of different ingredients (including major minerals, trace elements, vitamins and other additives) mixed and blended in appropriate proportions, to provide properly balanced diets for all types of stock at every stage of growth and development.
In some cases, eg. ruminants, compound feeds are technically designed, when fed without further mixing with cereals, to supplement natural foods (eg. grass or roughages) available on the farm. In such cases the compound feed is frequently given a name defining its purpose, such as for balancing straw, grass, kale, silage, etc.
Protein Concentrates. Products specially designed for further mixing before feeding, at an inclusion rate of 5% or more, with planned proportions of cereals and other feeding stuffs either on the farm or by a feeding stuffs compounder. Since the aim is that the final diet mixed in this way should be balanced for a particular feeding purpose, protein concentrates contain blended protein rich ingredients fortified with such essential nutrients as the major and trace minerals, vitamins, etc.
Where the rate at which protein concentrates are designed to be used in the mix is high, eg. 50%, they will contain some cereal or cereal by-products.
Some protein concentrates are specially designed so that, after further mixing with the appropriate quantities of cereals, the resultant product is then suitable for balancing farm roughages.
Coarse Mixes. A number of different ingredients of different physical form, eg. rolled, flaked and cracked, mixed together with protein concentrate pellets.
Straights. Single feeding stuffs of animal or vegetable origin, which may or may not have undergone some form of processing before purchase.
Straights rarely provide, in their own right, the complete nutritional requirements of livestock. Some examples of straights are wheat, barley, flaked maize, field beans, groundnut cake and meal, soybean meal and fish meal, etc. Straights form the basis of all forms of technically formulated feeds whether mixed on the farm or manufactured.
Additives. Substances added to a compound or a protein concentrate in the course of manufacture for some specific purpose other than as a direct source of nutrient.
These substances include coccidiostats and anti-blackhead drugs for mass prophylaxis or treatment on veterinary prescription, anti-oxidants, colouring agents, binders, flavourings, lignin pelleting performance enhancers etc. Supplements. Technical products for use at less than 5% of the total ration in which they are included, and designed to supply planned proportions of vitamins, trace minerals, one or more non-nutrient additives and other special ingredients.
Roughages
Silage, Hay, By-Products
Cereal By-products
Bran, Midds, Corn Gluten Feed, Hulls
Cereal / Starches
Corn, Wheat, Triticale, Barley, Oats, Manioc
Vegetable proteins
Soybean, Cottonseed and Sunflower Meals, Distillers and Brewer's Grains, Corn Gluten Meal
Trace Minerals Vitamins Additives
Antibiotics, Probiotics, Mould Inhibitors, Flavours, Colourants, Lignin Pelleting Performance Enhancers
Macro Minerals
Salt, Magnesium, Dicalcium Phosphate, Limestone, Potassium Animal Proteins Fish meal Examples of Ingredient use in Feeds See also Physical Factors Page 38
Vitamin Mineral Supp
Premix
Total Mixed Ration/Complete Feed Ruminant
Compound Feed
was pressed before being cut off by the stationary knives inside each wheel. More popular than the "Scheuler" presses were the flat-die machines currently used in many European feed mills and grass-drying plants. Here there are horizontal rolls which revolve around a vertical axis while forcing meal down through a stationary horizontal die. However the ring die principle of 1920 continu-ed, in various forms, to dominate the industry. Either the die or the roller assembly could rotate, and die or rollers
(or both) were driven. The process depends initially on friction between the rol-ler and the layer of meal between roller and die.
High-tech single/twin extruders entered the compound feed production industry with conviction during the late 1970’s. Initially they were used to produce feeds mainly for pets but soon progressed into production of pelleted feed for fish and other specialised feeds.
The energy/output ratio of these extruders can be as much as four times that required by a conventional pellet press. However, following the introduction of double-pelleting in the early 1980’s a further method of pre-compression i.e, Expanders (see 3.2.2) was introduced prior to the pellet press in an effort to improve pellet quality and make better use of nutritionally good but difficult to pellet raw materials. To facilitate adequate mixing into the total ration, planned levels
of the active materials are normally present in supplements in an appropriate diluent carrier. Most supplements are available to the farmer as well as to the feeding stuffs manufacturer.
1.3
History and Principles of Pelleting
The forerunner of the modern pelleting press was based not on extrusion, but on a moulding process. It consisted of two indented rollers which rotated in opposite directions, the meal was forced into the indentations and moulded into a variety of shapes. These included triangles, diamonds, ovals or buttons. This type of press is no longer seen in feed mills, but similar briquetting presses, as they usually are known, are still to be found in use in some other industries.The first press to work on the extrusion process and pro-duce a cylindrical pellet was developed in 1910. It was also the first to use what we would call a die: in this case the die was vertical, flat and stationary. Meal was forced through holes in the die by a worm, and the pellets cut off by revolving knives fixed to the worm shaft.
1920 saw the development of the first press to work on the ring die principle most widely used nowadays. Meal is forced outward through holes in a cylindrical die by the action of a single roller. Later versions had either one, two or three rollers.
A more short-lived variation on the extrusion process was also developed in the 1920’s. The "Scheuler" press consisted of two spur-toothed gear wheels which ran in opposite directions. The rims of both wheels had holes at the roots of the teeth, through which meal
Scheuler Press
Flat Die Press
Ring Die Press Early Press Meal in Pellets out Die Rotating knife Material In Pellets Out Meal Flow Knife Knives Material Flow Material Flow Die Rotation Roller Rotation
First Extrusion Press
The objectives to be followed when running a press manually or by computer are second nature to the experienced operator. However, it might still be helpful to re-state what we consider as the two main objectives, both of which should be achieved.
• To produce saleable pellets i.e. to achieve and maintain good Pellet Quality.
• To achieve desired tonnage of product, at minimum energy cost, and to maximise Pelleting Efficiency.
2.1
Pellet Quality (physical)
Pellets must present the following characteristics. • Good appearance
• Dust free • Without cracks • Uniform length
• Hard – sufficient only to withstand pressures during storage. • Durable – the most important characteristic of all. It must be
durable enough to withstand the handling it will receive between manufacture and feeding to stock.
See Section 9 (Quality control methods) for details of how to measure hardness and durability.
2.2
Pelleting Efficiency
Efficiency of pelleting means producing pellets of good physical quality at the optimum ratio of output to energy consumption by the press. This does not necessarily mean running the press at the lowest possible amps or at the maxi-mum possible output, but achieving the most economical combination of the two factors while still maintaining pellet quality.
Pelleting efficiency is defined as the amount of energy (kWh) used to produce one tonne of pellets (kWh/T).
Overleaf we show how you can calculate the pelleting efficiency of your pellet press.
Expander Extruder
Objectives in pelleting
2
Steam
Steam and Molasses Meal In Meal In Meal Out Meal Out Die Rotating Knife Steam Adjustable Gap
Information given in this section is intended to supplement the instructions available from your equipment supplier. Observe recognised safety procedures.
3.1
Meal Conditioning (short term)
3.1.1 Horizontal barrel type conditioner
Generally single or dual barrel arrangements. Each barrel contains paddles revolving at speed, blending steam, molasses or other additives into the meal. Duration time varies between 10 and 60 seconds. It can sometimes be controlled by the angle of the paddles, which should be checked frequent-ly for wear.
Best results can be obtained if the conditioner runs as full as is practical. In this way the paddles rub and blend steam, liquid additives and meal together, persuading rather than beating them into a mixture. The resulting meal texture will be more conducive to efficient production of good quality pellets and reduced likelihood of die blockage. The angle at which the paddles are set in relation to r.p.m. determines the volume of meal in the conditioner during production. Steam can be injected into this conditioner either
independently or with molasses. Generally a combination is used, in which case you should direct steam at 4 bar into the molasses pipe just before entry into the conditioner. The steam injection raises the temperature of the molasses, thus helping to disperse it more evenly.
Ensure that the steam entry ports into the conditioner remain clear of meal build-up. Check frequently that meal has not built up on the shaft, paddles, barrel and outlet, by removing inspection doors. Clean if required, as meal build-up can seriously affect efficiency of conditioning. Cleaning is made easier by first steaming the inside of the barrel, thus softening the deposits. Check also the outlet end of the meal feeder The efficiency of your pellet press can be calculated as
follows:
• Determine pelleting production rate (T/h). • Determine average press motor amperage. • Determine plant voltage.
• Apply the following formulas to find the press power in kW and the pelleting efficiency.
• Power (kW) = A x voltage x √3 x power factor T/h 1000
(Assume a power factor of 0.93 unless known) • Pelleting efficiency (kWh/T) = kW
T/h Practical example
A pellet press took 1.25 hrs to convert 10 tonnes of meal into pellets. The average amperage was recorded at 128.3 and the voltage was 415. The power factor is 0.9. What was the pelleting efficiency?
• Power = 128.3 x 415 x 1.73 x 0.9 = 82.9 kW 1000
• Pellet press production rate = 10 = 82 T/h 1.25
• Pelleting efficiency = 82.9 = 10.4 kWh/T 8
Note. When double pelleting or expanding, the combined amperage of both presses/pre-densifier must be used. It is acknowledged that total pelleting plant efficiency will incorporate ancillary plant, electric motors and steam generation.
Pelleting advice
3
Steam and Molasses
Meal in
Paddles Meal Out
optimised at the bottom. A ripener full of over wet meal presents a difficult disposal problem!
Addition of steam (4 bar pressure) at the bottom conditioner is strongly recommended in order to provide meal particles with surface moisture, which aids extrusion through the die and reduces the electrical energy consumption of the press motor.
3.2.1 Double pelleting
Conditioned meal enters the top press, where it is
precompressed through a "thin" die. The pre-formed pellets then pass to the bottom press fitted with a die of specification required for the finished product.
However, some feeds do not require double pelleting and therefore pass only through the bottom press.
If an excessive amount of short ends are found in finished pelleted product when double pelleting, then it is possible that the die specification of the top press is too severe. For efficient production when double pelleting, it is important to use optimum die specifications. Consultation with your die/press supplier is recommended in order to select a die compatible with your formulations and the physical characteristics of your pellet presses.
3.2.2 Expander systems
Meal is first conditioned, using a horizontal type barrel conditioner, prior to entry into a high compression chamber that creates a high meal temperature just before it is extruded through an adjustable annular gap. The expanded material is passed through a "Breaker" then pelleted by means of a conventional press.
There are several types of Expander in use. All are designed to create shear, which ruptures the cell structure of feed ingredients, resulting in increased temperature and gelatinisation of starch.
Expanders lend themselves best to long production runs because of the time required to optimise conditions. When pelleting expanded material, die specification is critical. Too much compression and the soft expandate squeezes out between rollers and die face, causing a blockage.
Insufficient compression results in poor pellet quality. Note that with some feed types, mainly low oil/high fibre, the above the conditioner as steam rising from the conditioner
can cause meal to build up here.
Barrel conditioners are fitted with a meal temperature gauge, the probe of which is generally located in the outlet. (See section 5 for recommended temperatures).
Note. If you are raising meal to a certain temperature, either by manual or automatic control, be sure that the end of the probe is clean. If heavily coated with meal, gauges will read around 10 ºC low. Conversely, the gauge will read too high if too much uncondensed steam is passing over a clean probe. Automatic self-cleaning temperature probes are recommended.
3.2
Meal Conditioning (long term)
Long term conditioningsystems comprise various configurations, but generally combine two horizontal barrel type conditioners. One feeds into a holding vessel, generally called a ripener. The other takes meal from the ripener and delivers it to the press. The ripener generally has a holding time 20 – 30 minutes. None use steam (other than for jacket heat) and none provide for the addition of liquid
additives, which are added at the top barrel conditioner. However, these restrictions do not apply to pasteurising con-ditioners which operate as continuous flow heat exchangers. Long term conditioning permits higher levels of liquid ingredients to be added. Time in the ripener is the important element. However, some ripeners are fitted with stirring arms to aid dispersion.
Difficulty can be experienced with blocked dies if the meal is allowed to become too wet at the entry to the ripener. Hence steam addition is generally limited at the top conditioner and
Long Term Conditioner
Meal in: Feeder Worm Conditioner Steam out from Jacket Feeder Worm Conditioner Steam in to Jacket Steam and Molasses Steam and Molasses
expandate can cause the amperage of the pellet press motor to fluctuate excessively making it difficult to control the process.
3.3
Pellet Press
Pellet presses are controlled manually or by computer. Either way, it is essential to understand the requirements for effective operation and control, in order to optimise production rate and pellet quality.
A computer continually monitors press conditions and optimises output, whilst safeguarding against die blockage. However, as and when required, the plant operator must be able to run the press manually.
The following points outline start-up, running and stopping procedures for a conventional pelleting press.
3.3.1 Pre-start-up procedure
It’s more than just pressing the start button
• Ensure pelleting system is empty of meal and pellets from previous production run, particularly if starting a new formulation i.e. to prevent cross contamination.
• Ensure die chamber, feed chutes and magnets are clean and that temperature probes and other monitoring equipment are also clean.
• The roller setting should be adjusted if necessary (see 3.3.10). • Ensure transport elements are running and that the route for
product flow has been selected.
3.3.2 Start-up procedure
(conventional barrel type conditioner) • Ensure meal is in the pre press bin. • Start press motor and conditioning plant.
• It is recommended to circulate initial production of pellets back to the pre press bin until optimum conditions are satisfied. • Start meal feeder and slowly increase speed allowing a
small flow of meal into the die. Watch amperage meter of press motor until it indicates about 50% of maximum. • Check to ensure that the die is pelleting.
Meal In
Bottom Press Conditioner
Top Press
To Cooler Steam And Molasses
Feeder Worm
Steam And Molasses Pre-Press Bin Dump Chute and By-Pass Dump Chute and By-Pass Double Pelleting Press Conditioner To Cooler Adjustable Gap Pre-Press Bin Dump Chute and By-Pass Pre-Compression Expansion Equipment
2) Ensure that meal is not allowed to build up in the feed chute, a build-up which then breaks away can block the die. Also, ensure that the feed cone (if there is one) ploughs, rollers, dies and knives are in good condition. If badly worn, pelleting efficiency and pellet quality will suffer. Be alert for vibrations or changes in sound, as these can be indications of a badly adjusted machine or imminent breakdown.
3.3.4 Greasing of bearings
It is vitally important that mainshaft and roller bearings are regularly and adequately greased. Fully automatic systems are recommended.
3.3.5 Die selection
Selecting the right die is clearly one of the most important decisions in pelleting. Depending on the formulation and the raw materials, there is a wide range available from low compression (thin dies with counter-bored parallel holes) up to high compression (thick dies with well or taper bored holes). A comprehensive treatment of this subject would fill another book, so we suggest that you should consult your die/press supplier to find the exact specification to meet your needs.
3.3.6 Starting new dies
• Check bores and track for scoring, burring and poor machining before fitting die to press.
• Some dies are supplied "pre run-in" and the holes are thus plugged with an oily material. This is removed by hand feeding the press with whole cereal (i.e. maize) after the die has been fitted and while the press is running. • If the holes of the new die are empty, then it is preferable
to plug them prior to commencing production by hand feeding whole pellets.
• Care should be taken when starting production not to "over feed" the die i.e. run the die in gently.
• After running for approximately one hour, stop the press and inspect the die track and rollers to ensure all holes are running.
• Some dies can be troublesome to start because patches of the track initially remain blocked. The recommended procedure is to remove the die and punch out all holes before refitting. If, after carrying out this procedure three times, there is still a problem, consult the die supplier. • Open steam valve and add liquid additives that may be
required. This action will cause a reduction in the press motor amperage.
• Increase feeder screw speed and then increase opening of steam valve. This procedure should continue until either the required meal temperature is reached (see section 5) or the point where the addition of steam does not reduce the amperage any more, when operating close to maximum production rate.
• Now check pellet quality (see section 9). If it is not up to requirement, adjust feeder screw speed and/or adjust steam addition according to feed type (see section 5).
• If the press has been started from cold, then after approximately 15 to 20 minutes, the die will be hot. Re-adjust meal feeder speed and steam in order to find new optimum operating conditions.
• For optimum pelleting performance see Borregaard’s Applied Lignin Technology and Pelleting Technique concept in section 7.
3.3.3 To stop pelleting operations
• On signal from low-level sensor in the pre press bin, prepare to stop pelleting.
• Reduce speed of feeder screw and addition of liquid additives, together with a reduction in steam.
• Close steam valve and stop liquid additives. Allow press to continue pelleting until the pre press bin is completely empty i.e. that fines returns have also stopped, thus allo-wing the plant to be clear of all materials, thereby nega-ting any possibility of cross contamination with follo-wing production.
• If production is not to continue, then the die should be filled with a non-corrosive oily meal before stopping the press (see 3.3.7 Die care).
General notes
1) When starting a die from cold or if it has been idle for a while, then the first pellets produced will be either oily from meal used to flush out the die, or very hard and dark, resulting from meal cooking in the hot die. These pellets must not be allowed into the finished product.
This flushing procedure also removes harmful fats or acids which may be present. Some raw materials are corrosive under pelleting conditions, thus eats into the surface of the die holes, reducing efficiency, pellet quality and die life. • Ideally, once a die and set of rollers have been "mated" and
formed the same wear pattern, they should only operate together. Many mills don’t stick to this because it takes so long to change both die and rolls. However, it is important to ensure that new rolls are not used with a badly worn die, or vice versa. Otherwise poor pellet quality will result, together with excessive wear. Some mills machine worn dies before fitting new rollers.
3.3.9 Roll design
• Fluted rolls tend to wear more at the corners where meal can be squeezed out rather than be forced through the holes in the die.
• Dimpled rolls tend to have greater grip and form a more even wear pattern.
• Textured rolls have a harder surface and generally have a longer life, but care should be taken with roller adjustment i.e. avoid metal to metal contact.
Some feed producers use a combination of roller design.
3.3.10 Roller setting (manual)
Correct roller setting is essential for optimum pellet quality, press capacity and die/roller life.
• If the rolls are set too tight, the die will flex excessively and may finally crack. It also increases the possibility of metal-to-metal
contact, thus rolling over the ends of the holes on the die and creating excessive wear and splitting of roller shells. Close fitting rolls generally maximise press capacity.
• Under-adjusted rolls create excessive roller slip, heat and possible
3.3.7 Die care
• Avoid "face to face" roller/die contact.
• If blocked solid: soak in oil, then try to re-start. If
unsuccessful, punch out. Drilling out should be a last resort (see also section 8.1.3).
• Never strike a die with a steel tool.
• Protect die from metal objects by fitting magnets.
• Punch out any tramp metal which manages to enter the die. • Log the use of your die.
• Check that die holes are not rolled over by feeling edge with wire or fine screw driver. Holes only slightly rolled over will drastically reduce press production rate. A recognised practice to overcome this is to remove the die and machine the track face.
3.3.8 Die changing
The exact procedure will be given in the press manual issued by the manufacturer. We list below some supplementary tips:
• Cover entry to cooler. This stops dirty meal – and maintenance tools etc. – getting into the system. • Always fill die with non-corrosive oily meal before
stopping press for die removal or other stoppages. Otherwise, heat of the die can sometimes bake hard the meal remaining in the holes. This can mean
-• Re-starting impossible.
• Die experiences excessive stress during start up, which weakens it.
• All holes may not "go", thus reducing output and efficiency of press.
Photograph from Felleskjøpet ØV, Norway.
The latter can result in a high percentage of very long pellets entering the cooler. However, further processing, i.e. sifting, elevating, conveying etc., usually breaks pellets to an acceptable length.
The shearing or tearing action of the knives on the soft pellets as they leave the die creates fines. Generally, the sharper the knife, the less fines. Rations containing a lignin PPE will also produce less fines at the die.
3.3.13 Fat application
Liquid fat added to the meal before pelleting is deterimental to physical pellet quality. It coats the meal particles which prevents binding during pelleting. Fat lubricates the die which reduces compression required to form the pellet.
For these reasons it is recommended to add no more than 1% fat prior to pelleting. Additional amounts should be added after the pellet has formed i.e. at the die and/or after the cooler. Fatspray at the die
Fat or oil is more readily absorbed into hot pellets. This overcomes the "greasy pellet" syndrome, i.e.
• Reduces palatability problems. • Improves pellet
handling and storage and facilitates the use of all types of fats and oils. Operation Fat or oil is atomized by the spray head which is designed to cater for maximum and minimum flow
rate according to pelleting production rate. The spray nozzles are designed to provide the correct angle of spray according to the width of the die and the distance from its outer face. It is important that fat/oil does not spray beyond the die surface as this can cause a build up of fatty meal on internal surfaces of the press door and cooler entry. consequent die blockage, thus seriously affecting
production output. However, pellet durability generally improves as rolls are moved away from the die face, but press capacity is sacrificed and pellet length is more varied. To manually adjust rolls refer to pellet press manufacturers operating manual.
3.3.11 Roller adjustment (remote)
Pellet presses can be supplied with, or can be modified to include, remote roller adjustment. By this means rollers can be positioned at the touch of a button or completely
automatically by computer. Rollers can be adjusted while the press is running during production, or when stationary. • At start-up, in order to reduce load on the press motor and
unnecessary wear and tear on the die, rollers should first be moved completely away from the die face. The press is then started and, on reaching full die speed, the rolls are adjusted to their required working position.
• With press control computers this procedure takes place automatically, as does overcoming problems such as blockages caused by scrap metal or other extraneous matter entering the die. In combination with a Borregaard online pellet tester and press control computer, auto roller
adjustment can be used to facilitate automatic control of pellet quality within required preset limits.
3.3.12 Knife setting
Knives are used to control the length of pellets as they leave the die. The setting position will depend on the required pellet length.
Generally, for pellets smaller in diameter than 6mm, one knife per roll should be used. Some 6 mm or larger pellets may require the action of only one knife or may dispense with the knives completely – the pellets simply knocked from the die by a breaker bar or, naturally, by centrifugal force.
Fatspraying at the Die
Door of Press Spray Head Roller Die Knife
Remote controlled roller gap adjustment essembly. Photograph courtesy California Pellet Mill Europe Limited.
flow indication signals from the fat/oil flow meter. The accuracy of this method is dependent on knowing meal density, thus it is important to make regular checks to update the controller, as changes in formulation occur. • Do not allow air to be drawn into the cooler via the feed
spout from the press as this can cause fat to build up inside the cooler, air ducting and cyclone.
• Fat coated fines entering the cooler can also be “picked up” by the cooling air inside the cooler, again causing build ups in air ducting and cyclone. In many situations, the only remedy is to ensure fines produced at the die are at an absolute mini-mum. This can be achieved by correct grist spectrum, proper conditioning, correct die specification and the use of a Borregaard Lignin Pelleting Performance Enhancer.
Alternatively, a routine cleaning operation must be carried out.
3.4
Pellet Cooler
Coolers are designed to extract heat and surplus moisture created during pelleting, thereby increasing the strength of the pellet.
The temperature of pellets leaving a cooler should be no more than 4 to 5 ºC above ambient.
Almost all coolers are based on either crossflow or counterflow principles or a combination of both. Vertical coolers are of the crossflow type. Most horizontal and carousel coolers are a combination of the crossflow and counterflow types. Bunker or bin type coolers are usually based on counterflow principles.
3.4.1 Vertical coolers
With this type of cooler it is important to set the rate of discharge so as to obtain long and even discharge periods, i.e. to suit the production rate of the press and the pellet size. A smooth discharge helps prevent "hang ups" in the cooler by keeping the pellets on the move it also provides better con-trol if you are crumbing (see also section 3.5). Atomised fat/oil from the spray head coats pellets in three ways.
• It coats the ends of pellets emerging from the die. • Fat/oil which lands on the die face is drawn into pellets by
capillary action as they emerge from holes in the die • Pellets are cut/broken from the die and tumble through the
spray.
Up to 6% fat/oil addition can be achieved with some rations. Between 2% and 4% has been found to be the norm. Fat coating after cooler
Fat applied to cooled pellets tends to remain on the surface and the affect of this is to reduce dust. Palatability, however, may be adversely affected.
High levels of fat/oil applied to cold pellets may create flow problems from storage silos, particularly when fines are present. Heating of associated equipment prevents build up of fat. Other liquids can be added to cold pellets, e.g. enzymes, probiotics and flavours.
Operational hints
• Ensure clean fat/oil lines – always incorporate a filter to prevent nozzle blockage.
• Ensure pipe lines are heated and insulated to prevent fat solidifying.
• It is preferable to incorporate automatic steam purging of the spray head, i.e. steam purge before start and after a production run. Ensure that on/off valves and non-return valves are located such that fat/oil is prevented from getting to the steam boiler.
• Fines are always produced at the die and these too are sprayed with fat/oil which are returned for pelleting. It is recommended that these fines should be directed to the feeder screw above the press. On production runs of 20 tonnes and over, the build up of "fatty fines" in the meal entering the press can cause pellet quality to deteriorate. If faced with this situation, it is advisable to allow the pre press bin to completely empty and then continue using "fresh meal".
• Most control systems are based on volumetric
Ensure that the bed of the cooler is completely covered with an even depth of pellets, in this way cooling air is evenly dispersed and drying/cooling is uniform.
Air curtains (usually plastic sheet) must also be regularly checked in order to ensure cooling air is drawn through the bed of pellets. Damaged curtains seriously affect the efficiency of the cooler, particularly when spraying fat at the die.
Regular inspection of cooler tray perforations should be made.
3.4.3 Counterflow-bunker coolers
In the counterflow type of cooler, the pellets and cooling air flow in opposite directions. The coolest pellets contact the coldest air and the hottest pellets contact the warmest air. This design principle is "more kind" to pellets, because it eliminates thermal shock and brings about gradual cooling of the pellets.
In general, these coolers use less electrical energy, are physically smaller, low in maintenance and are ideal for control by computer. They provide constant retention and an even flow over the entire discharge surface area. They can also provide a very When there is a formulation change, the cooler must be
emptied and this is time consuming, particularly when there are frequent changes. Some coolers, however, are fitted with doors so that the top half of the cooler can be filled while the bottom half is discharging. If you use this method, it is essen-tial that the fines returning from the pellets in the bottom of the cooler are not mixed with the batch being pelleted. This procedure also reduces problems of pellets "hanging up" in the cooler – a common feature, particularly with very moist, heavy molassed or urea-containing pellets. If a "hang up" in a cooler is not spotted in time (and remember, the automatic control system may not prevent this happening), the cooler will continue to fill and pellets may back-up into the pellet press causing considerable damage.
3.4.2 Horizontal belt coolers
This type gives much more flexibility to help achieve correct cooling and drying by controlling the speed at which the pellets travel through the cooler, i.e. the retention or "dwell" time. Bed depth and air flow can be controlled manually or automatically. Details of bed depth and retention time for various pellet sizes can be provided by your cooler supplier.
Counterflow cooler 1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 4 5 5 5 5 Crossflow cooler Horizontal cooler Airflow Airflow Carousel cooler Combinations of crossflow and counterflow coolers
Pr
oduct flow Product flow Product flow
Diagrams courtesy Van Aarsen.
Horizontal cooler.
Photograph courtesy Sprout-Matador.
Counterflow cooler. Photograph courtesy Geelen.
effective means of trapping fat droplets which would otherwi-se be drawn into the aspiration system when fat-spraying at the die.
The formation of product peaking towards the centre of the cooler produces a detrimental effect with regard to cooling efficiency. By incorporating a well designed product distributor, this problem is eliminated.
3.5
Crumblers
For very young poultry, even small pellets may be too large, thus intake is reduced. Crumbs overcome this problem and still provide a nutritionally balanced diet. However, the crumbs must be of good quality, i.e. dust free, and good quality pellets will make the best crumbs. The use of a lignin PPE will improve pellet quality before crumbing.
4 mm pellets are generally used and a constant and even feed into the crumbler is essential. Discharge from a horizontal or carousel cooler tends to be in surges, making crumbing difficult, therefore some form of control should be fitted between the cooler exit and the inlet to the crumbler in order to smooth the flow.
Setting the rolls too close results in mashing the pellets rather than breaking them. The meal created is then returned for re-pelleting, consequently production efficiency is reduced. It is also important that the rolls are well maintained, ensuring that the flutes are sharp.
3.6
Sifters
Fines produced during the manufacture of pelleted feed must be removed in order to provide your customer with a meal-free product. Sifters are generally located immediately after the cooler and before discharge into bulk road tanker. The screens in the sifter should be checked periodically to see that the perforations are not blind, worn or damaged.
Crumbler.
Photograph courtesy Sprout-Matador.
The tables overleaf enable you to check whether your pipe-work can cope with the quantity of steam you require. We recommend that the steam velocity after the pressure reducing valve should be around 20 m/sec. Knowing that no more than 45 kg of steam are generally required per hour per tonne of pellets produced, you can check the size of pipe being used in your mill, by referring to the lowest steam pressure you will need. (See our pressure recommendations, section 5).
For example, if your press can produce a maximum of 8 tonnes per hour of pellets, then it could be demanding up to 360 kg per hour of steam, and the table shows that when using at, say, 1 bar downstream of the reducing valve (our
recommended pressure for high starch rations), then a pipe bore of 80 mm will be required. This bore will be more than adequate for the higher pressure steam needed for less starchy rations. Note
• All steam pipes must be lagged.
• Ensure all steam traps are working (a sight glass after the trap shows if condensate is returning). Remember there will always be condensate which must be returned to the boiler. • Be prepared to change steam pressure to suit rations. • Consult your steam plant supplier if experiencing
difficulties achieving the desired amount of steam. Efficient pelleting depends upon adequate conditioning of
raw materials and the first pre-requisite is a good distribution of particle size.
4.1.
Grist Spectrum
Our general recommendation is as follows:
On 3 mm – up to 1% on 500µ – around 30% On 2 mm – up to 5% on 250µ – around 24% On 1 mm – around 20% "throughs" – not less than 20%
4.2
Steam Conditioning
Although water conditioning can be used, particularly on small units, it is not recommended. Steam is much more efficient and avoids creation of wet spots in the pelleted product. We therefore concentrate on this method, as it is used by virtually all commercial feed mills. When using a
conventional barrel conditioner the "quality" of steam must be as dry as possible. For high temperature/steralizing
conditioners, a certain amount of super-heated steam may be required.
Steam pressure must remain constant and this is achieved by a pressure reducing valve (see diagram). It allows for pressure fluctuations upstream (caused by the firing of the boiler) but keeps pressure constant downstream. This valve, which you can use to change pressure according to the ration being processed, should be located approximately 20 ft (6 metres) upstream from the conditioner and in a position where it can easily be adjusted. It is considered that this distance is necessary so that the steam can stabilise after pressure reduction. In some cases, where the reducing valve is too close to the conditioner, The result is a mixture of superheated and wet steam, with the superheated steam being carried through (particularly in the barrel type) without giving up its heat and moisture.
4.3
Pipe Sizes and Steam Velocity
Velocity of steam entering the conditioner can also affect the efficiency of mixing with the meal. Steam velocity and quantity determine the pipe bore size which should be used. However, we have noticed in a number of plants that full benefit is not obtained from the steam (particularly low pressure steam) because the bore of the steam pipe after the reducing valve is too small.
Meal conditioning
4
General note (for barrel conditioners). To get hot moist meal – use low pressure steam To get hot dry meal – use high pressure steam
Steam Installation prior to Conditioner
High Pressure Steam
Pressure Reducing
Valve ReducedPressure
Steam Safety Valve By-Pass Valve Sight Glass Valve Strainer Steam Trap Separator
Pipe bore (mm)
Suggested operating conditions for pelleting various feed types. Note: These are guidelines only. Raw material variations might make it necessary to vary operating conditions (see section 6). Steam pressure relates only to barrel type conditioner.
Re Meal Temperature: Ensure that your operating temperature complies with your Companies requirement for hygiene and nutrition.
Re Energy Input: This is an indication of the amount needed to produce pellets of durability around 95 Holmen (1 min. test, 4 – 5 mm pellets. 0.5 min test, 3 mm pellets) when pelleting a feed formulation with a FPQF equal to 4.7.
5.1
Ruminant Feeds
Notes on Ruminant Feeds
• These feeds tend to be fibrous and bulky. The more fibrous a feed, the more difficult it is to add steam. Too much steam causes the pellets to expand and crack, particularly on large diameter pellets.
• High fibre materials will tend to help pellet quality but reduce production rate.
• Processed starch by-products (e.g. maize gluten feed) will tend not to absorb moisture, therefore you may have difficulty applying steam when using these materials – a lignin PPE helps tremendously.
• With some combinations of raw materials, which tend not to accept steam, benefit may be gained by adding up to 1% water at the blending mixer. However, this can cause wet spots, which lead to vitamin degradation.
• If using a barrel type conditioner inject part, if not all, the steam with the molasses.
Capacity of pipes passing dry saturated steam
IMPERIAL Gauge steam pressures (lb/sq. in)
15 20 30 45 50 65 Capacity in lb/hr at 60 ft/sec. 1 85 98 125 164 176 214 1 1/4 133 153 195 256 276 335 1 1/2 191 221 281 368 397 482 2 340 393 499 655 706 857 2 1/2 531 613 780 1023 1102 1339 3 764 883 1123 1473 1587 1927 4 1359 1571 1996 2619 2822 3427 5 2123 2454 3119 4091 4408 5354
METRIC Gauge steam pressures (bar)
1 1.5 2 3 4 5 Capacity in kg/hr at 20 m/sec 20 25 31 37 48 60 71 25 39 49 58 76 93 111 32 65 80 95 125 153 183 40 102 125 149 195 240 286 50 159 196 233 305 375 447 80 408 503 597 782 961 1146 100 638 786 933 1222 1502 1790 150 1435 1769 2099 2751 3380 4029
Production guidelines
5
Pipe bore (in.)
Steam Meal Energy Input Borregaard Pressure Temperature pellet press PPE
at exit of motor inclusion at conditioner guideline 2.5 – 4 bar 75 – 85 ºC 20 – 24 kWh/T 1 – 2%
that the pellet press rollers are set correctly in order to minimise rollers slip, thus reducing heat generated by friction. This type of feed cuts press output and die blockages can be frequent. However, adding 1% of a Borregaard Lignin PPE will increase traction between rollers, meal and die thereby helping you to increase production rate.
Correct die specification is very important for this type of feed – consult your die supplier.
• Pig feeds generally contain a relatively high level of cereals. Best operating procedure depends on the proportions of wheat, barley, maize etc., but in general, high temperature high moisture meal using low pressure steam produces the best pellets.
• Sow rolls (10 – 12 mm pellets), particularly when fed outdoors, must be very durable. They must also be large enough i.e., no "short ends" to prevent birds from carrying them away. They are best produced using a slow-revolving die at relatively low production rate, in order to maximise dwell time in the die. If meal passes through the holes in the die without forming, the practice of plugging the holes should be tried. This is done by hand feeding hard pellets into the die chamber. Molasses, if well dispersed, will help formation.
Excess use of steam can cause vertical cracking in the pellets on leaving the die.
5.4
Poultry feeds
Notes on poultry Feeds
• Poultry feeds generally contain high levels of cereals, mainly wheat or maize, and fibre is relatively low. Therefore pellet structure and strength depend on good conditioning, i.e. heat and moisture to soften the meal particles so they can mould easily together. There is some gelatinisation of the starches, which then act as a natural binder.
• With some formulations, in order to maintain pellet quality, it may be found necessary to run the press under capacity in order to increase meal dwell time in the die. If you need to do this it may indicate that you need a higher compression die. • With a multi-speed gearbox, a slow speed is generally
found to provide best results.
• Some dairy feeds are produced using high cereal, low fibre raw materials. In this case, refer to Poultry Feed
conditioning, section 5.4.
5.2
Concentrates
Notes on concentrates
• To produce good pellets from high protein feeds heat is required to plasticise the protein, which in turn acts as a natural binder. Moreover, the meal particles will soften and mould easily together during formation of pellets in the die. • Heat is more important than moisture in the production of
concentrates. The amount of moisture added at the conditi-oner should be sufficient for lubrication through the die. • It is particulary important that holes in the die are flushed
out if you have to stop production or remove the die. • For feed containing urea ensure the steam is very dry.
5.3
Pig feeds
Notes on pig Feeds.
• Pig weaner feeds containing milk powder and sugar are heat sensitive due to caramelization that occurs at relatively low temperature. Therefore, it is imperative
Steam Meal Energy Input Borregaard Pressure Temperature pellet press PPE
at exit of motor inclusion at conditioner guideline 4 – 5 bar 75 – 85 ºC 20 – 24 kWh/T 1 – 2%
Steam Meal Energy Input Borregaard Pressure Temperature pellet press PPE
at exit of motor inclusion at conditioner guideline 1 – 3 bar 75 – 85 ºC 15 – 17 kWh/T 1 – 2%
(3% in rolls for sows)
Steam Meal Energy Input Borregaard Pressure Temperature pellet press PPE
at exit of motor inclusion at conditioner guideline 1 – 1.5 bar 85 – 95 ºC 10 – 12 kWh/T 1 – 1.5%
In section 5 we have suggested operating conditions for a range of basic feed types. However, we have also stressed that these are only guidelines. It is well known that different raw materials behave differently in their effect both on pellet quality and output, and thus changes in formulations might dictate changes in these guideline recommendations.
6.1
Why Raw Materials Affect Pelleting
There are many characteristics of raw materials which affect production, but the main factors are:The relationship between these factors and pellet quality is not straightforward, but we hope the chart overleaf will help. Most feed raw materials are variable in character. All the factors listed above affect pellet production, so when any or all of them change, pelleting is affected. These variations are the main reason why pellet quality can suddenly alter without any change in formulation or production method.
Ideally, it should be possible to devise a mathematical relationship between the factors listed above and the production characteristics of a raw material, so that simple chemical analysis could give a pellet quality prediction.
6.2
Raw Materials – physical and
Nutritional Factors
Clearly it is important to try and anticipate problems due to the use of certain raw materials, or to a change in the character of those raw materials. We have therefore prepared the chart overleaf, which we hope may be of assistance. In addition to the usual chemical or nutritional values, which are in every compounder’s computer matrix, we have also given figures for three important physical values, on a scale from 0-10.
• When using a barrel type conditioner low pressure steam must be used. This type of steam starts to give up its heat and moisture more rapidly.
• The addition of a Borregaard lignin PPE will allow you to use more steam, while improving pellet quality. It also maintains "traction" between roller, meal and die – this is very important with high moisture meals.
• Too much fat added at the mixer causes mealy pellets. Fat coating helps solve this problem, but it is still useful to add the first 0.5 to 1% fat at the mixer. This will aid press capacity and extend die life.
• The requirement to produce poultry feed free of all pathogens, in particular Salmonella, puts great importance on effective heat conditioning. Temperature and dwell time are the most important factors, but because of the many other parameters which can influence this, it is difficult to give hard and fast guidelines in this handbook. Most existing pelleting plants, if using a barrel type conditioner and pellet press, will be required to extend their present temperature and dwell time.
Depending on production capacity requirements, it may be necessary to use a pasteurisation process of conditioning, whereby a specially designed steam unit and mixing/-holding vessel is used. Whatever process is adopted, it is absolutely essential that the plant is equipped with a means of monitoring production such that any meal which has not been subjected to the required temperature and time, is cir-culated for reprocessing.
Raw materials
characteristics
6
• Natural or processed • Starch content • Protein content • Moisture content • Particle size, distributionand shape
• Oil content • Fibre content
• Mineral matter content • Moisture absorbency • Abrasiveness
Physical Factors • Pellet Quality
The raw material’s contribution to physical quality. (The higher the number, the better the quality). • Press capacity
Its effect upon output. (The higher the number, the higher the production rate). • Abrasiveness
A key to die life (The higher the number, the more abrasive the raw material).
These values are based on our experience and practical observations, supported by those of customers and friends in the industry. We hope the chart will be of assistance to you. Notes on the Chart • The three "physical
factors" are designed so that virtually all raw materials fall between 0 and 10.
• The exceptions are fat and Borregaard’s range of lignin Pelleting Performance Enhancers. As these affect pellet quality significantly at very low inclusion rates, they have "pellet quality factors" outside the normal scale.
factor factor factor per cent Ib/ft3 kg/m3
0 – 10 0 – 10 0 – 10 Mill by-product Barley meal 5.0 6.0 5.0 10.5 2.0 4.5 2.2 30 480 Maize meal 5.0 7.0 6.0 9.0 3.5 1.9 1.2 38 610 Milo meal 4.0 6.0 7.0 10.0 3.0 2.5 5.0 34 540 Oat meal 2.0 3.0 7.0 10.5 4.5 10.5 3.2 32 520 Rice (rough) 5.0 5.0 4.0 8.0 1.5 9.0 12.0 30 480 Screenings (grain) 2.0 2.0 8.0 12.0 4.0 12.0 8.0 27 480 Wheat meal 8.0 6.0 3.0 11.0 1.5 2.5 ---- 34 540 Wheatfeed 6.0 5.0 4.0 15.0 3.5 8.0 4.7 23 370 Wheat pollards 5.0 5.0 4.0 14.0 4.0 9.0 ---- 30 400 Oilseeds and derivatives
Coconut cake 5.0 8.0 6.0 21.0 8.0 11.5 6.5 30 480
Cotton dec. 7.0 8.0 6.0 40.0 6.0 11.5 6.0 40 640
Cotton meal ext. 8.0 6.0 7.0 39.0 1.0 12.0 6.0 38 610 Groundnut cake dec. 7.0 8.0 4.0 47.0 5.5 6.0 6.0 39 620 Groundnut meal ext. 8.0 6.0 5.0 54.0 1.0 9.5 6.0 42 670
Guar meal 7.0 7.0 5.0 42.0 4.0 11.0 5.5 35 560
Linseed meal ext. 7.0 6.0 5.0 35.0 1.5 9.0 5.5 30 400
Linseed cake 6.0 7.0 4.0 32.0 6.5 8.5 5.0 34 540
Palm kernel cake exp. 6.0 7.0 4.0 19.0 6.5 12.0 3.8 28 480 Palm kernel meal ext. 6.0 5.0 5.0 20.0 1.0 15.0 3.7 47 700 Palm kernel (whole) 3.0 8.0 3.0 13.9 49.0 7.3 1.8 47 750 Rapeseed meal ext. 6.0 6.0 6.0 36.0 1.0 11.0 ---- 32 510 Sesame meal exp. 7.0 7.0 4.0 45.0 10.0 6.0 11.5 35 560 Soyabean meal HIPRO 4.0 5.0 4.0 48.0 1.6 3.1 6.5 36 500
SoyPass 5.0 5.0 4.0 45.0 1.5 3.1 ---- 36 500
Soya full fat 4.0 8.0 3.0 35.0 18.0 4.5 5.8 30 480 Sunflower cake exp. 6.0 6.0 4.0 39.0 8.0 16.2 7.0 35 560 Sunflower meal ext. 6.0 5.0 5.0 39.0 1.0 18.0 7.0 33 530 By-products
Vegetable oil (added before die) -40.0 50.0 0.0 ---- 100.0 ---- 0.0 56 900 Vegetable oil (added after die) -5.0 0.0 0.0 ---- 100.0 ---- 0.0 56 900 Fish meal white 4.0 7.0 5.0 67.0 8.3 ---- 20.0 40 640 Fish meal Peruvian 4.0 7.0 5.0 65.0 10.3 ---- 15.0 40 640 Herring meal 4.0 7.0 5.0 72.0 9.0 1.0 10.5 37 590 Legumes Field beans 7.0 5.0 5.0 27.4 1.3 6.2 3.4 43 690 Peas 6.0 5.0 5.0 23.0 1.2 6.3 2.9 45 720 Lentils 4.0 4.0 5.0 25.5 1.3 4.5 3.0 50 800 Locust beans 4.0 4.0 6.0 4.0 ---- 6.9 3.0 25 400 Others Biscuit meal 2.0 8.0 3.0 8.0 10.0 1.0 ---- 30 480 Brewers grains 3.0 4.0 5.0 13.8 8.0 14.0 ---- 20 320 Cereal replacer pellets 3.5 4.0 7.0 8.0 1.5 8.0 ---- 35 560 Chinese leaf meal 7.0 2.0 8.0 16.0 4.0 15.0 ---- 20 320
Citrus pulp 7.0 3.0 6.0 6.0 3.0 12.5 6.0 21 330
Coffee residue 2.0 8.0 3.0 10.0 25.0 36.0 1.9 25 400 Distillers' grains - barley 4.0 5.0 5.0 22.0 4.0 17.0 ---- 20 320 Distillers' grains - maize 3.0 4.0 5.0 27.0 8.0 13.0 ---- 20 320 Distillers' grains + solubles 5.0 6.0 5.0 27.0 7.5 8.5 ---- 30 480 Distillers' solubles (maize) 7.0 6.0 0.0 27.0 9.0 5.0 ---- 38 600
Grass meal 7.0 2.0 8.0 15.0 3.0 20.0 9.0 20 320
Maize germ meal 5.0 8.0 3.0 11.0 10.0 3.5 3.0 30 480 Maize gluten feed 3.0 4.0 6.0 23.0 2.0 8.0 6.3 34 540 Maize gluten meal 4.0 5.0 5.0 60.0 2.0 1.3 6.3 30 480
Malt culms 6.0 2.0 7.0 22.0 1.5 14.0 6.0 15 240
Manioc 5.0 3.0 7.0 2.5 ---- 4.0 4.0 40 640
Minerals 2.0 4.0 10.0 ---- ---- ---- 95.0 61 1000
Molasses 7.0 6.0 0.0 3.6 ---- ---- 11.0 77 1230
Nutritionally improved straw 4.0 4.0 6.0 3.5 1.0 38.5 11.0 8 130
Olive pulp 7.0 3.0 6.0 10.0 3.0 29.0 7.4 45 720
Rice bran 2.0 3.0 9.0 13.0 14.0 12.0 ---- 20 320
Skim milk powder 9.0 2.0 5.0 34.0 0.5 ---- 8.5 40 640 Sugar beat pulp (molassed) 7.0 3.0 6.0 9.0 0.5 16.0 7.1 15 240 Borregaard Lignin PPE 50.0 30.0 0.0 ---- ---- ---- 14.0 31 500
Experience and practical trials have shown that when combining the expertise of a Feed Company’s Production and Nutrition personnel with Borregaard’s Lignin Technology and Applied Pelleting Technique, massive improvements in overall pelleting performance can be achieved.
• Raw materials in combination can behave unpredictably (the "synergy effect"). This is why pellet quality may sometimes differ from the value calculated from our figures, which are based on experience of raw materials within the range of inclusion levels common in European compound feeds. • Our table refers to average samples. Feed raw materials,
being natural products, may vary from batch to batch. If you see a change in your production without a formulation change, it may be that the specification of one of your raw materials has changed.
• We won’t be surprised if you disagree with some figures. Results depend on plant factors as well as raw material factors. There is no such thing as a standard feed mill, so the same raw material will behave differently in different mills. Remember, these are average figures; this subject is beset with many variations and complications.
• The "physical factors" in the chart may help you to anticipate any problems before they occur. We also hope that this handbook in general will help you to make perfect pellets from any formulation.
Please remember that formulations are devised to provide the required nutrients in the most economical combination of the raw materials available, not to cause headaches for production! Raw material cost accounts for 85% of the feed’s selling price, and this exceeds production cost by a factor of between 15:1 and 20:1. That’s why a formulation change for
production purposes, which might well increase overall costs significantly, is generally viewed as a last resort.
However, with the advent of computer control of the entire feed mill and the production data which can be generated, actual production costs for each feed formulation can be determined, thus enabling an "optimum" cost ration to be produced. FPQF (Feed Pellet Quality Factor)
Calculation of the FPQF indicates how well a particular feed formulation will pellet (see following examples). The level of acceptability is your decision depending on factors such as market area, production constraints and feed type. As a guideline we take 4.7 as the minimum. Values below this suggest pellet quality problems unless a higher than normal amount of electrical energy is used in pelleting. Higher values indicate that production rate can be maximised.
CALCULATION OF FEED PELLET QUALITY FACTOR Typical Examples
Table No. 1, Dairy Feed
% PQF FPQF Gluten 13.0 3.00 0.39 Citrus 22.5 7.00 1.57 Distillers 6.0 3.50 0.21 Barley 20.0 5.00 1.00 Palm kernal 10.0 6.00 0.60 oo-Rape 6.0 6.00 0.36 Veg. oil -40.00 Minerals 2.5 2.00 0.05 Wheat 20.0 8.00 1.60 Beet Pulp 7.00 Total FPQF 5.78
Table No. 2, Pig Feed
% PQF FPQF Barley 23.0 5.00 1.15 Oat Meal 37.2 2.00 0.74 Wheat Meal 13.0 8.00 1.04 Veg. oil 2.0 -40.00 -0.80 Fish Meal 3.0 4.00 0.12 Protein Meal 6.0 4.00 0.24 Grass Meal 1.6 7.00 0.11 Mins on carrier 7.0 2.00 0.14 Vitamins 2.2 3.00 0.07 Returns 5.0 5.00 0.25 Total FPQF 3.06
PQF = Pellet Quality Factor FPQF = Feed Pellet Quality Factor
7.1
Advantages of Borregaard’s Lignin PPEs
A lignin PPE is an important production tool that enables pelleting plant operators to:Increase
• Pellet quality (Durability Holmen value) • Pelleting production rate (T/h)
• Pelleting efficiency (kWh/T) • Die and roller life
• The ability to add more steam and fat Decrease • Production costs • Fines returns • Power consumption • Roller slip • Die blockages • Feed rejections!
The effects are best illustrated by practical example of a pelleting trial carried out in a commercial feed mill, which is outlined in the following pages.
7.2
Pelleting Trial Procedures
These trials are based on a procedure we have developed during several year’s experience and can easily be adopted by you. Basically a trial consists of pelleting three consecutive production runs.
Under trial conditions it is necessary to explore the full benefits, beyond that of improvements to physical quality, that can be achieved by the incorporation of a PPE. These may be improvements in productivity (pelleting throughput), pelleting efficiency and power consumption. All leading to improved profitability for the business.
With this in mind the following protocol is used: • A suitable formulation is selected. Preferably one that is
not currently meeting your pelleting performance/quality criteria. Its FPQF (see page 38 – 39) is first calculated. This is done initially to provide an indication of pellet quality and later in relation to energy input (kWh/T).
Table No. 4, Talapia Feed
% PQF FPQF Protein Meal 3.00 4.00 0.12 Fish Meal 2.00 4.00 0.08 Distillers grain 1.90 3.00 0.06 Veg. oil 1.15 -40.00 -0.46 Minerals 2.51 2.00 0.05 Rape Meal 5.00 6.00 0.30 Wheat Pollard 15.00 5.00 0.75 Wheat 27.00 8.00 2.16 Soya 25.60 4.00 1.02 Sunflower Meal 16.80 6.00 1.00 100 % Total FPQF 5.08
PQF = Pellet Quality Factor FPQF = Feed Pellet Quality Factor
Borregaard’s lignin pelleting
performance enhancers
7
Table No. 3, Duck Feed
% PQF FPQF Maize Meal 16.0 5.00 0.80 Rice Broken 35.0 5.00 1.75 Soya 30.0 4.00 1.20 Veg. oil 0.5 -40.00 -0.20 Fish Meal 5.0 4.00 0.20 Mins + Vits 3.5 2.00 0.07 Rice Bran 10.0 2.00 0.20 Wheat 8.00 100 % Total FPQF 4.02
is also taken from the cooler exit approximately 20 minutes later i.e., a time period equal to the dwell time of pellets in the cooler. Period of sampling is every 15 minutes. The pellet samples are used for durability measurement using the Borregaard LT portable pellet tester (successor to the Holmen Tester) and also your own method if different. Pellet hardness is also measured if required. Both hardness and durability tests are completed in the same time frame for each production run.
The option of average pellet weight may be determined by taking a random quantity from the composite sample, weighing and then counting their number. Adding a Borregaard PPE such as LignoBond DD, can be demonstrated to increase pellet density and length resulting from a more positive pelleting action and increased production rate.
A composite of the samples taken from each production run is retained for chemical analysis. This will check that the ingredients and their proportions are similar for the formulations used in each production run.
• A fully documented report should always be prepared immediately following the trial. This is standard procedure for a Borregaard Feed Production Technologist.
7.2.1 Typical pelleting trial
The following data was obtained when monitoring production of a dairy feed that contained 1.6% LignoBond. By increasing LignoBond to 2% and using Applied Lignin Technology and Pelleting Technique, production rate was increased in steps until maximum power of the pellet press motor was reached. Production rate was normally around 8 T/h corresponding to a power consumption of 17 kWh/T and pellet durability (ex-plant cooler) of 91 Holmen, although a level of 92 to 95 was sought. As can be seen, it was possible to increase production rate 34.6% to 10.7 T/h, reduce power consumption 10.5% to 15.4 kWh/T, whilst increasing pellet durability to around 94/95. At 10.7 T/h the pellet press had very positive pelleting action with little amperage fluctuation. Had more steam been available production rate could have increased further. Modifications to steam supply were later made whereupon it was found possible to run the plant with confidence at 12 T/h (50% increase) whist maintaining power consumption and pellet durability around 15 kWh/T and 92/93 Holmen respectively.
• The quantity of feed required for a single production run, of a minimum one-hour duration under normal operating conditions, is established.
• Production Run 1. The "control". Consisting of around one hours pelleting production of the standard formulation. • Production Run 2. As per the "control" but with the
addition of 1 – 2% of the PPE.
• Production Run 3. As per Production Run 2, but using the properties of the PPE to increased meal temperature (if required) and production rate whilst maintaining the required level of pellet quality.
• During each production run use data loggers or your plant equipment to monitor and record: production run duration, press motor voltage (measured between two phases), pellet press motor amperage (one phase only), meal feeder speed (r.p.m) and meal temperature at exit of the conditioner.
The pellet press voltage, amperage and production rate (T/h) data is used to calculate energy input (kWh/T) for each production run. The conditioned meal temperature data is used to confirm that the meal conditioning is the same for Run 1 and Run 2, and that changes made during Run 3 are documented. Meal feeder speed data is used to calculate production rate per revolution. By doing so, any step-up in production rate during Run 3 can be calculated precisely. The collated information should provide a comparison of the following and in so doing provide a means of assessing the Pelleting Performance of any pelleting line:
• Production rate (T/h) • Energy Input (kWh/T) • Conditioned meal temperature • Pellet durability (Holmen)
Moreover, the character of amperage, meal feeder speed and temperature traces, if using dedicated data loggers, provides an insight to the mechanical operation of the pellet press and effectiveness of control systems. • A sample of pellets is taken direct from the die at a
precise time so that the event can be marked on the loggers and/or readings taken from your plant display monitors, gauges and meters. This enables the exact production conditions to be related to the sample. A sample
