Pelleting Tips

Process Optimization – Controlling non-value-added factors up to mixing

Ashwani Verma — Mon, 05 Jul 2021 09:34:42 +0000

Think Grain Think Feed organized first session of Process Optimization webinar on 28th May with Mr M. Kanagaraj – a renowned Feed Milling expert who has trained more than 1,000 feed mill professionals from integrators, commercial feed manufacturers and others in the South Asian sub-continent. Renowned experts including Mr RathanakarShetty(RS), Director, Ace Feeds; Mr Balaji Sundraraman(BS), CEO, RGS Feeds and Mr Rajiv Kr. Taneja(RT), Head of Feed & Oil, Buhler India joined the webinar as speakers. The 90-minute session was attended by 307 attendees from 19 countries. Below is the summary of the discussion.
What are the non-value-added activities in a feed mill?
RS: Converting raw material to the end product by using resources is value addition but wastage happening during the process also utilizes the same resources which brings no value and is defined as non-value-added activities in the process. Eliminating these non-value additions can bring better efficiency and product quality too.
Non-value-additions like labor, complexity in system with too much documentation, space management in the warehouse, material handling system, lack of trained labor, excess or shortage of labor, etc. would lead to poor quality of raw material and end-product and reduce the overall efficiency of the feed mill. This can be avoided with proper planning.
Inventory – If there is shortage of raw material then production is held up and capacity utilization is not up to the mark due to which all fixed and variable cost multiplies. The thumb rule for the capacity utilization is unloading capacity. It should be higher than intake capacity, which should be higher than batching, it should be higher than the grinding and mixing and that should be more than the pelleting. If the thumb rule is followed properly then the succeeding process won’t be held up because of the non-supply of flow of material from the previous system.
Over-production in hammer mills – If mixer is not able to handle the capacity of the hammer mill, then the hammer mill would run idle which would be a wastage of energy with more wear and tear to the machine, etc. This can be avoided by finetuning the hammer mill capacity.
Production scheduling – Without proper scheduling, a greater number of changeovers or number of products produced in a day would require more time gap which is again a wastage.
There are many benefits of process optimization, one of the most important is consistency. Consistency brings predictability and with predictability, planning can be done with minute details.
What are the challenges in managing the inventory in a manner that it should not exceed but also a minimum inventory level is maintained?
BS: Each feed mill has its own limitations. The inventory management system is directly proportional to the demand in the market. In case of feed, the end user i.e., the animal is not the decision maker. We have to understand with the psyche of the decision maker then create a forecast and produce the product to match the market. Another difficulty is raw materials which have their own variability in terms of their standards, production, place of production, irrigation standards, water level, temperature, etc.
Keeping the inventory to match the production is also challenging. If one can reduce the warehouse space up to 50% then inventory can be automatically managed. For inventory management, data analysis is the key. By data compilation and analysis to understand the movement of raw material in terms of its availability, quantity, and price, etc., one can understand how the market is responding to different seasons which would bring demand versus production season analysis.
Availability of raw material and demand in the market cannot be controlled hence it is important to make correct forecast and manage operations accordingly. Inventory management is crucial for any feed miller to control the price and quality of the entire feed mill.
Reducing space usage by 50% may result in shortage of raw material. How a feed miller can overcome that?
BS: In scarcity, one tends to buy more as observed in the pandemic time. If there is more space, one tends to buy more without proper planning and logistics in place which is a wastage. With more resources people become resourceless while with fewer resources they become resourceful.
We follow this in RGS Feeds. Say if per week production is 400 MT with 20% downtime then monthly production would be 10,000 or 11,000 MT. As per planning, the monthly requirement is given and the basis upon which orders are placed on weekly basis to get raw materials at exact time. There is a possibility of keeping the product in the suppliers’ godown instead of its own space while ensuring to pick it on a particular date.
How grain handling solutions can help feed manufacturers to optimize their resources in terms of money and inventory?
RT: Grain cleaning is a very important aspect in a feed mill which is accepted worldwide and can soon be adopted in India. The threat of mycotoxin makes it important than ever. A major reason for aflatoxin or other mycotoxins in end product is dust, immature grain, shriveled grain, broken grains etc. which can be removed by the cleaning section. This would further help in better animal performance hence better end-product quality.
Grain storage is again a vital aspect of a feed mill. Silos should be planned with complete engineering i.e., proper accessories, aeration, temperature control, fumigation, recleaning of material, recirculation of material etc. It can be a value-added activity for any grain processing industry.
Usually, hammer mills overproduce whereas pellet mills remain full, and hence, hammer mill is to be stopped. What is the reason?
RS: It can be due to capacity mismatch. Firstly, one produces the mash and keeps it in the pellet mill, shutting the batching system and in the meantime, one may produce mash feed (in case you produce) for capacity utilization.
Over-production in a hammer mill can be due to various factors like the kind of material proposition in the formulation when it consists of more grains it would take a longer time for grinding. Also, pushing all powder material through hammer mill increases the grinding time and also power consumption which also results in non-uniform particle size reduction. By using a sieve before the hammer mill, the finer material can bypass the hammer mill and directly come into the mixer.
The mixing cycle including wet mixing time, dry mixing time, liquid addition, the sequence of material adding to the mixer is again important. If it is decided properly at the design level itself delay can be avoided.
How does the over-production in hammer mill affect the overall efficiency?
RT: One should have proper planning in place starting from outlet of batching up to outlet of mixer. In case a feed miller still faces problem, a technique is followed while designing any type of flow diagram is Mixing Cycle Diagram. This diagram considers the conveyor capacity, conveyor discharge time, discharge time from a hopper, various scales, idle time and with detailed planning even the number of batches to be produced on an hourly basis is known. Considering all these factors, if it is a good mixing cycle diagram then the hammer mill will never over-produce or run out of production.
How to reduce the idle time in feed milling?
BS: To overcome idle time or over-production in hammer mill, firstly one should understand the hammer mill i.e., variance versus the hammer mill behavior. Secondly, people should be completely trained to understand the variation then act accordingly.
All machinery should be at the optimum level. One should proportionate sieve versus die, it is important to understand the particle size entering the hammer mill and coming out of the hammer mill. Complete information like mixing time, moisture, mixing cycle, etc. should be collected and then the production should be started. By doing so one would reduce the idle time in production. Otherwise, this idle time can be up to 7% of entire milling operations which is reduced up to 3% in our case.
The process standards will vary in a micro level from one feed mill to other due to factors such as change in environment, procurement methodology etc. Would you share your views on grinding process standardization?
RS: Standardization is specific to the unit or company or maybe even to the suppliers of the equipment. But from a larger perspective, a hammer mill is used for particle size reduction, one can standardize the speed of the hammer mill like the modern feed plants have 2800-3000 RPM which is standard followed by most of the feed equipment suppliers.
Also, selection of the sieve is important, if one is producing a 3mm pellet then one (should use sieve above the hammer mill) or tries to reduce the particle size less than 3mm. It is not a hard and fast rule but basis upon experience one can design the standard.
RT: Using sieve above the hammer mill is a very good approach which is used in all feed plants in Europe and recently has been adopted in India. This approach helps to optimize the energy consumption in hammer mill. Different kind of process adoption in a feed mill requires different kinds of hammer mill like vertical, horizontal etc. but the basic principle behind hammer mill optimization is to know particle size distribution range and D50 value. If these two inputs are given while designing the plant then hammer mill would run 100% in an optimum manner.
How much is the energy consumption in a hammer mill?
RT: In case of vertical hammer mill, coarser grinding is expected hence there is 15-20% less energy consumption is there in the hammer mill not in the whole process.
Share your experience on mixing process standardization especially in a country like ours where there is lot of similarity in the process like oil inclusion or using large quantities of molasses?
RT: Mixing Cycle Diagram is a very versatile tool to standardize the mixing operation for any particular kind of product which is to be produced. Up to the mixer it is a batch process and after mixer it is a continuous process. If the mixing cycle diagram up to the mixer is followed firmly then one can know the mixing time for different kinds of products and it can be standardized.
AUDIENCE QUESTIONS
In a humid climate, the moisture content in feed gets above 11% thereby reducing the shelf life. How to manage the moisture above the standard of 11%?
RS: The moisture level depends upon the moisture of your input raw material, if it is above 11% then one should make necessary adjustment in the post-pelleting process, particularly in the cooling process. One is adjusting the material at the bed level of the cooler there would be better cooling process. Second is the opening of the damper of the butterfly valve near the blower, by adjusting its airflow can be increased or reduced and excess moisture can be absorbed. Third is bypassing the dry air in the inlet of the cooler which is not common in feed milling but it is practiced in oil milling where hot air is passed through the cooler so that excess moisture can be removed. It can be added to the feed mill also.
Your opinion about cost optimization
BS: Firstly, a feed miller needs to understand that 85-88% of the output is raw material. The first step for cost optimization is to optimize the purchasing or the formula for the product. Secondly, there are two important factors for process cost reduction are energy and human resources. For energy, you need to look into non-value-added factors like power cost. By controlling idle running of hammer mill, pellet mill, conveyors and other parts, you may reduce the cost of energy. Human resources are most important and after some surveys, we have reduced 20% of our human resources while increasing 40% of our productivity.
For costing, one has to go as per batch or formula or product. One should be able to recognize the formula giving the best results and move in that direction. There can be a lot of variability like one formula can give 13 MT per hour while other can give 17 MT per hour. Costing is to be made with every batch.
What all seasonal precautions should be taken care by the feed industry?
RS: In India, we experience extreme kinds of climate like cold weather to severe-heat condition in summer. We should take few precautions at the time of storage. In an open storage facility, there is a lot of moisture loss happening in peak summer, one should store lesser quantities during that time.
Steam is another neglected area in feed milling, in winter the temperature is low and steam gets condensate due to which enough temperature is not maintained for the pelleting process, so to avoid such conditions one should properly insulate the steam line.
BS: Feed manufacturing operations and cost optimization does not have any seasonal precaution or activity.
Control the efficacy of the system, machine, and manpower within a set means.
Improve your production to zero defects and zero downtime.
How much losses occur in the feed milling process due to atmospheric conditions?
RS: There are two kinds of shortages, one is storage shortage – the shortage happening during storage of the raw material like handling shortage, transportation shortage; second is the process loss which starts from intake of material to bagging. If both combined would be less than 1% then it represents an efficient feed mill.
Moisture loss is the main factor affecting inventory control and moisture shrinkage results in differences between documented and actual stock especially in terms of grains. How should we control?
RS: Moisture loss during the storage is inevitable, especially when material is stored for longer period. Take utmost care while accepting the raw materials particularly high moisture materials. If it is unavoidable, better to consume the grains having high moisture at the earliest, but following FIFO (First In First Out) system is most desirable.
What are the process loss and shrinkage loss standard % for the poultry industry?
RS: Process loss and Storage loss again depend on the moisture levels of input materials. So always better to have more control on the input materials. In this time of high-cost raw materials, minimization of the loss is paramount importance. For computation of costing, we can keep a provision of maximum 1.0%. Moisture optimization systems available in the industry can minimize the shrinkage or process loss.
Factors to be considered to stock ingredients in bulk storage especially in silos with optimum quality for 3-4 months.
RS: While storing Grains in the bulk storage system, some points to be taken into consideration to keep the stock in good conditions are:

Do not load high moisture (above 12.0%) grain to the silo.
Silo should be facilitated with aeration system, and operate at least an hour every day.
To prevent mold growth, mold inhibitors may be sprayed on the material during intake.
Completely empty out the silo at least once in 3-4 months.
No leakages / water seepage in the silo wall or foundation.

In the commodity market strategic stocking is required in the feed business? What should be the concept for strategic stocking?
BS: Increasing stock level ensures availability of materials and happy customers but holding inventories can be costly and reduces operational fund.

Design a budget for your inventory to meet your availability service level.
Create a minimum quantity level for inventories to produce different product to meet your customer demand.
Measure the inventory’s usage & identify the factors that lead to over & understocking.
Analyze individual SKU’s volatility & viability in storage.

Conclusions
Process optimization is one of the key aspects that every feed miller should practice and tune the process as close as possible to the requirement. Below are the take home message from this session:

Trained labor in right quantity is the key. More labor or shortage of labor would affect the productivity of the feed plant.
Transport equipment capacity should match with the key equipment capacity rather it should be more.
Data collection and analysis would bring real results whether it is quality or any other parameter.
Reduce your warehouse space, try to bring it to 50%.
Grain cleaning is very important whether you store it in silo or bags.

Note: PART II of PROCESS OPTIMIZATION webinar is scheduled on 23rd July to register click here: https://bit.ly/3wBXOCA

The post Process Optimization – Controlling non-value-added factors up to mixing appeared first on Benison Media.

Principles of mash conditioning

Ashwani Verma — Wed, 31 Jul 2019 06:28:48 +0000

Conditioning is common to modify the physical properties of mash before it is delivered to the pellet die chamber. Most commonly, conditioning involves the addition of steam to the mash; however, conditioning may also involve the addition of liquids such as water, molasses, pellet binders or, in some cases, indirect heat (jacket heat). All of these things are done for the primary purpose of improving pellet quality and/or pellet mill throughput. The article will cover the conditioning process i.e. any addition to the mash after it leaves the mixer, but before it reaches the pellet die chamber.
Pellet quality and conditioning
In general terms, pellet quality refers to the ability of feed pellets to withstand mechanical handling without excessive breakage and fines generation. The commercial feed industry often assigns a much higher value to pellet quality (low fines) than do integrators who manufacture feeds for their own use.
Factors influencing the pellet quality according to Reimer (1992) are formulation (40%), fineness of grind (20%), steam conditioning (20%), die selection (15%) and cooling/drying (5%).
It is important to note that by combining the influences of formulation and grind, 60% of the potential pellet quality is determined before the mash even reaches the pellet mill. If true, it is obvious that quality problems can’t always be solved by modifying the conditioning process or using a thicker die.
When dealing only with the pelleting system, it is apparent that conditioning is the most important factor that influences pellet quality. If done correctly, proper conditioning allows the use of the thinnest possible die and, therefore, the greatest potential throughput. Though conditioning is far more important than die or roll selection, it is a process that is often overlooked, and certainly not well understood by many feed manufacturers.
Conditioning defined
Conditioning may include steam and/or water addition, expanding, compacting, pre-pelleting, ripening and so on. Whatever the type of conditioning employed, it should be optimized to give the best pellet quality at a reasonable rate, without significant destruction of available nutrients or feed additives.
Steam: Introduction
Steam is a commonly-used input in many feed manufacturing operations. In large or small facilities, steam generation can represent a significant part of manufacturing costs and, if left uncontrolled, can have serious implications for the bottom line.
Steam pressure
As heat is applied to the water in a closed system (i.e., a boiler) the water temperature rises. As the temperature rises above 100°C, the “vaporpressure” of the water is increased beyond atmospheric pressure. This pressure is uniformly distributed over all of the surfaces of the closed vessel. If the water level is maintained at say 80% of the vessel capacity, the “head” space will be filled with steam at the same temperature as the water. By referring to Table 1, the relationship of pressure and temperature can be determined.
In processing, pressure is typically measured in gauge rather than absolute pressure.
It is obvious that as heat is added to the system, the pressure rises directly with the temperature. It is also interesting to look at the relationship between pressure and specific volume. At 0 kPa (0 psi) gauge pressure, 0.5 kg of steam occupies 0.84 m3, but at 552 kPag (80 psi), that same 0.5 kg of steam occupies only 0.15 m3. It is this relationship that is useful in determining pipe and valve sizes, as well as insulation costs for a given installation.
Though the thermodynamic properties of saturated steam at a given temperature and pressure are well documented, the debate still continues as to what pressure results in the best pellet quality and mill performance for a given feed type. Various studies showed that the control valve, piping size and system design are sufficient to give good control, actual steam pressure is of little consequence.
Steam quality
The importance of steam quality is that it is an indication that enough heat has been lost from the system to condense 10% of the steam vapor back to a liquid phase. This heat loss represents not only a significant loss in energy costs, but can result in pelleting problems if the balance between mash moisture and the conditioning temperature is wrong.
Steam quality can have a significant impact on pelleting, particularly if it varies, it is worth considering in any discussion of conditioning. As an example, 0.5 kg of steam at 100°C has 1.2 X 106 J of total heat, while 0.5 kg of water at 100°C has only 1.9 X 105 J of total heat— or 84% less heat than the steam. If one attempts to condition to a particular temperature, say 82°C, themash can become far too wet to pellet if poorquality steam is used.
It should be the objective of every pelleting operator to use the driest steam possible. If additional moisture is needed, as is often the case, it can be added much more economically as water either in the mixer or in the conditioner. Table 1 is included to understand the thermodynamic relationship of heat, pressure and volume.
Conditioning options
Atmospheric conditioners
The typical conditioner commonly associated with a pelleting system is referred to as an “atmospheric conditioner.” These conditioners operate under atmospheric pressure and are typically exposed to ambient conditions. As a rule, the atmospheric conditioner is basically a single cylinder with an agitator shaft. The function of the conditioner is to provide for the intimate contact and mixing of steam with the pellet mash. An understanding of how steam and pellet mash interact is critical to the understanding and management of a pelleting system.
Water addition during conditioning
It is well recognized that water is a critical component in the bonding that takes place during pellet formation. In typical pelleting, the only water added is in the form of steam. In areas where local corn is the predominant grain, excess moisture may be experienced as new crop grain begins to arrive. However, as the crop year proceeds, drier grain is received as stored grain enters the market.
Depending upon formulation, optimum conditioned mash moisture is in the range of 16.0 to 17.5%, with 4 to 5% coming from conditioning. As a rule, we can expect to add 1% moisture to the pellet mash for each 12.5°C increase in mash temperature from steam. If the mash is cool, say 10°C, and we target 85°C as our mash temperature, we will be adding about 6% moisture. If the mash is already at 11- 12%, the final mash moisture will be at or above the upper level of the range of optimum moisture. Conversely, if the mash temperature is at 35°C and we target 85°C, we’ll only be adding about 4% moisture. If the initial mash moisture is 11-12%, the final mash moisture will be at or below the lower level of the optimum for pellet quality and throughput. Both of these situations (or even more extreme) can arise depending on the season of the year and ingredient moisture content.
There are times when we simply can’t reach target temperatures before the upper moisture level is met. Other times, when the grain is dry and warm, we simply can’t get enough steam into the mash without exceeding target temperatures. Late in the crop year it is often advantageous to add 1 to 2% water during conditioning to improve pellet quality and production rate. Studies at Kansas State University have shown that moisture addition at the mixer can be highly accurate and can result in substantial improvement in pellet quality (Greer and Fairchild, 1999).
Double- or triple-pass conditioner
In an effort to extend and control dwell time, double- or triple-pass conditioners are sometimes used. Basically, this can be accomplished by stacking two or three “standard” conditioners above the pellet mill. Variable speed drives, multiple steam injecting points and steam jacketing are options in various designs.
A distinct advantage of a double- or triple-pass conditioner over a single, large-volume conditioner is that some semblance of “first-in-first-out” order can be maintained. It is also a relatively economical choice compared with more exotic conditioning; however, a good deal of head room above the pellet mill is required, making installation something of a problem. As an alternative to “stacked” conditioners, either “twin-shell” or horizontal double-pass designs can be used. In either case, retention time is extended. However, the head room needed above the pellet mill is no greater than that needed for a single-pass conditioner.
Jacketed conditioners
Many attempts have been made to use jacketed conditioners, conveyors or holding vessels with varying success. The basis for this concept is that, with jacket steam, heat can be introduced without adding excessive moisture. This is certainly a good idea, but is difficult to implement practically. The typical reason for failure is that the heat is transferred to the mash only at the surface of the barrel. Most often, the surface-to-volume ratio is so low that little heat is actually transferred into the mash—particularly in large-volume conditioners.
Pressure conditioning
This concept involves the use of conditioning chambers operating at elevated pressures. By increasing the pressure in the vessel, conditioning temperatures well in excess of 100°C can be attained. The reasoning behind the concept follows the law of thermodynamics and, simply put, forces the moisture and heat into mash particles more quickly and thoroughly than is possible at atmospheric pressure.
The challenge of getting the mash into and out of a pressurized vessel is obvious. The exit problem is solved by making the die chamber and rollers part of the pressurized area. The inlet uses a spring-loaded pressure plate, forced open by the feed, to contain the pressure.
Conclusions
The conditioning process is, without doubt, the most important component of any feed pelleting system, at least as far as pellet quality is concerned. It is also, perhaps, the least understood component by pellet mill operators, many plant managers and even equipment suppliers. It was the purpose of the article to provide insight into some of the lessunderstood aspects of conditioning and to point out some of the strong points and weak points of each option available.
There is no single conditioning option that is best for all applications and situations. In most cases, replacement is not an option; therefore, steps taken to optimize a given installation will result in the best pellet quality at the best production rate possible. It must be remembered, however, that all factors involved in pellet quality are inter-related and must ultimately be addressed if the process is to be successful.
Source: Kansas State University, WattAgNet
by KEITH C. BEHNKE& ANGIE GILPIN

The post Principles of mash conditioning appeared first on Benison Media.

Cooling- A critical process for pellet durability index & feed hygiene

Ashwani Verma — Wed, 21 Nov 2018 07:27:57 +0000

The main objective of Cooling processin the pellet formationis to withdraw heat and moisture from dense mass to forms shaped mass. Theoretically, the amount of heat and moisture removal should be same as amount added during steam conditioning process. But practically, it varies based on environmental conditions. The inputs of cooling process are

hot and wet pellet feed
ambient air

The output is pellet feed with specified level of moisture (country specific), temperature and pellet durability index (PDI).
Pellets are cooled by passing ambient air through a bed of hot pellets. Though the primary function of coolers in a feed mill is to cool the pellet, it should also remove excess moisture from feed that was added through steam during conditioning process.
There are two types of coolers used in feed industry;
1. Horizontal cooler
2. Counter-flow cooler
Theworking ofhorizontal cooler is based on cross flow principle. But most of modern feed mills usecounter-flow cooler. The principle involved in this process is known as evaporative cooling. Ahigh-speed blower creates a negative pressure in upper portion of the cooling chamber. Because of negative pressure, ambient air is sucked-in through bottom of the cooler. The air passes through bed of hot pellets. Since the ambient air is at lower temperature than pellet feed, heat transfer takes place. This process cools the pellet comes from pellet press. The exhaust air is warmer than inlet air. The pellet feed moves from top to bottom direction and air moves from bottom to top. Both movements are opposite to each other. Hence, this design of cooler is called counter flow cooler. In addition to heat, moisture is also removed from pellet during the cooling process. The feed temperature at inlet of cooler will be around 85C in poultry feed and around 65C in cattle feed with molasses in ration. The feed temperature at outlet of cooler should be 5Cabove ambient temperature. The moisture of feed after cooling should be closer to that of mash feed at batch mixer in case of poultry feed and molasses mixer in case of cattle feed. Heat removal in cooler depends on the ambient air temperature and moisture removal controlled by humidity of the environment.
Challenges in Cooling
Coolers are directly influenced by climatic conditions because air present in environment is used as a medium of heat transfer. Relative Humidity (RH) plays a vital role in evaporative cooling. Humidity is explained below in pictorial representation.
For explanation per say, in 100% humid environment, air does not have capacity to observe water since 1 kg of air contains 1 kg of water in it. On the other side, in 25% humid environment, air is having only 250 g of water in 1 kg of air. The remaining 750 g capacity is available to absorb water. It has high potential to absorb water. In subtropical countries, there are different climate zones. Feed mill coolers behaves differently in different climatic zones.
Cooler Operations in Different climate zones:
Hot and humid conditions: In this climate, RH % is high and air has more water content. Therefore, innate capacity of air to absorb feed moisture is reduced. During this period, coolers will remove less moisture than standard level. This results in high moisture in finished feed, whichmay lead to mould (fungus) growth.
Hot and extreme dry conditions:In this condition, RH % is very low and ambient temperature is very high. The ambient air removes more moisture than standard level. Because, air has more capacity to absorb water. This leads to high moisture loss, which results in significant financial loss. High moisture loss leads to weight loss in feed bags. Commercial feed manufacturers add a quantum of feed to compensate this weight loss. This is an additional cost to the organization. When retention time is reduced to minimize excess evaporation, heat removal is ineffective. This will result in hot finished feed.
Cold and dry conditions: Both heat and moisture removal from feed will be faster in this weather condition.
Critical check point in Cooling
1. Weathercondition
It is recommended to monitor humidity and air temperature on daily basis. Because, this information is vital to set cooler control parameters like height of pellet bed, air flow rate
2. Specific air Volume
The specific air volume is measure in m3/Ton. This is controlled by using butterfly valve mounted in the blower line. The specific air volume should be controlled depending on moisture of feed at cooler inlet and humidity of ambient air.
3. Cleanliness of cooler
There is a risk of condensation in cooler during cold weather condition. The air temperature at upper portion of cooling chamber is hotter than ambient temperature. The colder ambient air condensate hot air inside the cooler. The condensation creates two challenges

Risk of mould (fungus) and bacterial growth and cross contamination
Corrosion in side wall and top side of cooler

Monitoring and maintaining cleanliness of cooler ensures shelf life of feed and cooler life
4. Air flow
Air flow should be measured and monitored. It is expressed in cubic feet per minute (CFM). To calculate CFM, flow velocity in feet per minute should be known. Modern coolers are having blower fan with frequency drive. With this technology, air flow can be varied depends on need.
5. Cooler retention time
The period in which, feed entersin cooler and leaves from cooler is called cooler retention time. This can be varied by adjusting position of high and low level of sensors.
Proper pellet cooling can be achieved by optimum airflow and cooler retention time. Product build-up in cooler duct affects air flow and proper functioning of cooler. Cooler ducts should be clean and free from dust. Poor cooling affects pellet durability. Cooling is one of the critical process in determining PDI and feed hygiene. By maintaining process parameters and cleanliness ofcooler, both PDI and feed hygiene can be achieved.
by M Kanagaraj, Catalyst Techvisor Private Limited

The post Cooling- A critical process for pellet durability index & feed hygiene appeared first on Benison Media.

Key steps in feed pelleting

Ashwani Verma — Mon, 29 Oct 2018 09:18:51 +0000

The basic purpose of pelleting process is to convert fine particles to larger shaped dense feed mass. The pellet press applies forces on conditioned mash feed to form a dense feed mass. Mostly, the shape of dense feed mass will be a cylinder or square and will be larger size compared with mash feed.The main aim of pelleting process is to optimizes the physical property of mash feed.The key advantages of pelleting are

Minimizes the wastage during eating process
Animal prefers pellet because it receives the total mixed nutrients in every pellet

iii. Improves storage capacity because bulk density of pellet is more compared with mash feed

Decreases transportation cost because of increases transportation capacity of same volume
Improves feed handling because of improved flowability of pellet feed

Pelleting process in feed mill is easy to understand but tough to execute. Because more than one process factor should be controlled by the operator. The pellet quality (PDI) and throughput (TPH) of pellet press are significantly affected, when those factors are not controlled properly. Modern pellet machine uses sensors and automation technology to ease this operation by controlling and maintaining those process factors. The pellet quality and throughput of pellet press are not only determined by pelleting process alone.
60% of pellet quality is decided before the mash enters the conditioner. 80% of PDI is decided before the feed enters in pellet press.It means before mash entered pellet die, the pellet quality is decided. Refer pie chart. This was studied and reported by Dr Keith C Behnke, Professor, Department of Grain Science and Industry, Kansas State University.
Pelleting process
The softened mash feed enters centre of pelleting chamber by gravity. The self-rotating rolls applies force on conditioned mash feed and pushes through pellet die. This force is caused because of

gap between rolls and die
surface characteristics of rolls

iii. physical properties of mash feed

The pellet die applies a resistive force on mash feed. This is force has a direct effect on pellet quality (PDI) and throughput (TPH) of pellet press.These two forces are opposite to each other. But, force generated by rolls should be greater than that of resistive force generated by pellet die. Otherwise, it affects the production rate (TPH). A frictional heatis generated in pelleting process and transferred to mash feed. The differential temperature of conditioned mash and hot pellet is an indication of frictional heat generated at pellet die.
It should be at optimum level to achieve better pellet quality and throughput.Excessive frictional heat is an indication of hard pellet. High friction at pellet die reduces die life and rolls life. The hot dense pellet comes out of pellet die. The knives fixed at the periphery of pellet press cuts the pellet and determines the length of pellet. Refer picture 1. As a rule of thumb, length of pellet can be two or three time of pellet diameter. It also can be decided based on animal requirements.
Pellet Quality (PDI – Pellet Durability Index) Vs Production rate(TPH – Tons Per Hour)
There is a possibility of reduction in throughput of pellet press (TPH), while improving pellet quality and vice versa. It is a big challenge to achieve both at its highest level. But it is possible to achieve optimum level of both factors. It is recommended to conduct trials scientifically and make decision statistically to arrive the best fit of critical process parameter of grinding, conditioning, pelleting and critical quality parameters like particle size, conditioned mash moisture, conditioned mash temperature, L/d ratio etc.
Specific Energy of pellet press
Pelleting process is the most capital and energy intensive process in feed manufacturing operation. Specific energy is defined as the amount of electrical energy required to push one ton of feed through pellet die and expressed in kWh/Ton. When PDI increases, the Specific energy also increases. Hence optimization is needed to minimize pelleting cost. Refer the bar chart.

Roller adjustment

Perfect roller adjustment is important for maximum productivity of pellet press and better die life. Lose roll adjustment reduces throughput (TPH). Too tight rolls adjustment reduces die life. Modern pellet machines have auto roll adjustment technology to eliminate manual errors in rolls setting. Poor roll setting leads to die breakage.

L/d ratio (Insert picture)

Pellet die is the key component of pelleting process. The die specification is vital for pellet press productivity and pellet quality. Refer picture2.

D = diameter of pellet
L = Effective length
T = Total thickness
X = Counter bore depth
D = Inlet diameter
Compression ratio = D2/d2
Performance ratio = L/d
The PDI can be enhanced by using pellet die with high L/d ratio. The die selection is key to achieve better pellet quality and production rate.

Pellet knife position

Two knives are provided in pellet machines. The upper knife cuts the pellets from left roll. Similarly, bottom knife is for right roll. Worn out knife increases fines at pellet die. It is recommended to check condition (sharpness) of knife periodically.

Pellet die retention time

Feed is retained more time in pellet die, while reducing flow rate of feed. This improves PDI. But at the same time,it reduces production rate.
Feed formulation, particle size and conditioning are critical to achieve better pellet quality and high production rate.Factors like roller adjustment, knife setting etc are operator-based skills. Hence operators are the most important factor in achieving good quality pellet and high production rate. The operators should have pellet process knowledge and able adjust process parameters like flow rate, roller adjustment, knife setting, and steam inclusion etc. based on feed type and local conditions.
References are available upon request
by M Kanagaraj, Catalyst Techvisor Private Limited

The post Key steps in feed pelleting appeared first on Benison Media.

Role of conditioning in enhancing feed quality and feed mill performance

Ashwani Verma — Sat, 22 Sep 2018 11:46:03 +0000

Conditioning
The purpose of conditioning is to optimize the nutritional quality of feed. Conditioning enhances the Pellet quality and productivity of pellet press. This is achieved in feed milling by adding or including any process to mash feed after mixing and before pelleting.
Addition methods:
1) Steam addition
2) Water addition
Processes:
1) Expanding feed molecule through Expander
2) Compacting feed molecule through Compacter
3) Pre-pelleting
Basically, the conditioning process, condition the mash feed to become pellet feed. This article covers the topic of Conditioning through Steam addition. The process of adding moisture and heat through steam to the mash feed is called Steam Conditioning. Steam adds heat and moisture to mash feed. Addition of heat and moisture leads to some starch gelatinization. Because of gelatinization, binding of raw material happens. Secondly, it improves digestibility of nutrients.
The function of a conditioner is to provide proper contact and mixing of steam with mash feed. The process flow of Conditioning process is shown in Picture 1
The mash feed with initial moisture and temperature is an input to conditioning process. Steam is another input. Understanding the nature of these two inputs are critical to achieve good quality conditioning. In practical situation, initial moisture varies due to storage practices of raw material and environment conditions. The mash temperature will be few degrees above ambient temperature. Saturated steam is recommended for conditioning purpose.Steam with 100% vapour is called Saturated steam. The other inputs are conditioner, feed type and method of conditioning. Conditioner is basically a dynamic or continuous mixer. Hence it mixes the steam with mash feed uniformly. The heat and moisture should be uniform throughout conditioned mash feed. Testing CV of conditioner is a good practice to ensure the homogeneity of moisture and heat.
Good quality steam is applied through nozzles on mash feed. When saturated steam enters conditioner, the steam vapour cools and condensation of liquid occurs on the surface of feed particle. Both moisture and heat are migrated from the surface to core of feed particle. This migration is possible because of moisture gradient between the surface and interior of feed particle.
The output of a conditioning process is the conditioned mash feed with optimum moisture with target temperature.
Challenges in Conditioning
As a rule of thumb, each 1% moisture addition to mash feed (through saturated steam), increases 12.5C temperature. Keeping thermodynamic statement in mind, the feed mills face following two major challenges in conditioning process:

The raw material moisture varies significantly over a period of a time. The variation in raw material moisture creates variation in initial moisture of mash feed.
The initial temperature of mash feed before entering conditioner is also varies significantly between summer and winter season and even between day and night in some seasons.

Further two scenarios can be visualized to understand the challenges in conditioning:

Scenario 1–When mash feed has high initial moisture and low feed temperature (during cool climate), target temperature cannot be reached. But before that optimum moisture is met.
Initial moisture = 13% (high); Ambient temperature = 20C; Target temperature = 83C
For above condition,

3% moisture addition through steam will take feed temperature to 57.5C {(12.5X3) +20}and moisture to 16%
4% moisture addition through steam will take feed temperature to 70C and 17% moisture

Target temperature cannot be reached. Less heated mash feed causes frictional heating at pellet die. It reduces pellet mill capacity and die life.
Scenario 2 – When grain moisture is low and or warm climate condition, optimum moisture cannot be achieved without exceeding target temperature
Initial moisture = 9% (low/dry); Ambient temperature = 40C; Target temperature = 83C
For above condition, target temperature is easily achieved. But the possible moisture addition through steam will be 3.44%. This will take the feed moisture to 12.44%. The optimum moisture cannot be achieved.
Initial mash feed moisture and environmental conditions are critical to conditioning process. Based on those factors, conditioning process should be optimized. Close watching of initial moisture and ambient conditions are important.
Critical check points in Conditioning
1 Particle size
To achieve optimum conditioning performance, fine grinding is recommended. The surface area of fine ground particles is more compared with coarse particles. As a result, the heat and moisture can penetrate to core of feed particles.
2 Initial mash feed moisture
This is explained in scenario 1 & 2 of above section. Since initial mash feed moisture is critical to conditioning process, it is recommended to monitor the moisture level on continuous basis and take appropriate strategy to achieve optimum moisture and target temperature.
3 Steam quality
Based on vapour content in steam, it is classified as

Saturated steam – 100% vapour held at a temperature and pressure at its vaporization point
Super-heated steam – 100% vapour held at temperature, greater than that of vaporization temperature
Wet steam – consists of both vapour and free water

Steam should be in saturated vapour state before entering to conditioner. This is achieved by Pressure Relief Valve (PRV). The PRV reduces high pressure steam to low pressure steam (1.5 to 2.5 kg/cm2). As a result, high pressure steam turns into low pressure dry steam.Steam quality is described based on dryness of steam. Steam should be as dry as possible. 80% dryness fraction is considered as good quality steam. The steam will be in super-heated state in boiler.

Residence time

Feed ingredients like grains, protein meals and other common ingredients are typically good insulators. Hence it takes longer time to transfer heat and moisture from steam to feed molecule. The time duration by which the mash feed exposed to steam, inside the conditioner is called Residence time or Retention time. Longer residence time allows better steam distribution and moisture penetration into feed particles. It improves the efficiency of conditioning. The residence time can be increased by 1) altering pick angles of conditioner paddles and 2) reducing the shaft speed of conditioner. Pellet quality and throughput (TPH) of pellet press is optimized at 30 to 90 seconds residence time

Degree of fill

Mash feed level in conditioner should be about 70% of available volume of conditioner.
The Pellet Durability Index(PDI) and Specific energy (kW/Ton) of pellet press are significantly influenced by conditioning process. Effective conditioning depends on properly designed, maintained and operated steam supply system. Research studies shows that conditioning contributes, 20% of pellet durability in overall feed milling process. So, by achieving optimum conditioning performance, the overall feed quality and feed mill performance can be enhanced.
by M Kanagaraj, Catalyst Techvisor Private Limited

The post Role of conditioning in enhancing feed quality and feed mill performance appeared first on Benison Media.

Role of Mixing in delivering balanced diet

Ashwani Verma — Tue, 21 Aug 2018 10:32:43 +0000

Mixing
The nutritionist provides a recipe to optimize growth, production and health of an animal. The recipe is a balanced diet that supplies nutrients at desired level to animal. The batching or proportioning system in a feed mill does the job of weighing raw materials accurately as per recipe. Basically, batching is a sequential process. Hence bringing homogeneity of ingredients is a key factor in animal performance. Otherwise, the animals would not get balanced diet. Secondly, the complete homogeneous mix of mash feed will produce good quality of pellet.
The batch mixer in a feed mill does the job of bringing uniformity in feed ingredients. By design, there are two types of blenders predominantly used in feed mills, namely

Ribbon type
Paddle type

The blenders use, single shaft or double shafts based on capacity of blender. Higher capacity blenders use twin shafts. The mixing time is less in case of twin shaft blenders compared with single shaft blenders. Based on mixing operation, the mixer is classified as Static mixer and Dynamic mixer. This is another type of classification. In Static mixer, one batch of material is in mixing process at any given time. During that time, inlets and outlet of blender are closed. In Dynamic mixer, mixing is continuous. In other words, both inlet and outlet of mixer are open. So that the material is continuously enters the mixer, gets mixed and discharged from the mixer.
The batch size of mixer is calculated based on working volume of blender and mash feed bulk density.
Batch size = Working volume X Bulk density of mash feed
Another important factor is mixing time. It determines the productivity of feed mill. It also influences the feed quality in the aspects of homogeneity. The variability in mixer is expressed in % of Co-efficient of Variation (CV). CV test is an important Critical-To-Quality (CTQ) factor and should be checked periodically to ensure Feed quality.
Challenges in Mixing
The performance quality of grinding, conditioning, pelleting and cooling can be judged by physical observations. The challenge in mixing process is the quality of mixing cannot be judged by physical observation. Hence the mixer performance should be monitored periodically, and the mixing equipment should be maintained in proper working condition. To ensure both CV Test should be performed periodically as per the Standard Operating Procedure (SOP).
Mixer performance test – CV Test
CV test is the common test used to study the mixer performance. The CV test reveals the amount of variation presents in the mixer. For example, when CV of a mixer is 10%, then it produces feed with 10% non-uniformity. The CV test procedure consists three steps

Sampling of feed

10 representative samples are collected from a batch covering entire volume of the mixer

Analysing the samples

Any ingredients which is less than 0.5% in recipe can be taken for analysis. Also commercial micro tracers are used for CV test, which are inert in nature.

Interpret the results

CV = [Standard deviation ()  Mean ()] X 100
10% CV is considered as a good mixing
Critical check point in Mixing
Mixing time
Mixing time is the time in which the best uniformity of ingredients achieved. As the mixing time increases, the uniformity of ingredients increases or variation in ingredients decreases. But beyond certain time, segregation of ingredients starts or variation increases. The point at which the variation is at its best minimum value, called the optimum mixing time. Refer the graph
Sequence of mixing operation
Mixing is a sequential process. All ingredients are charged into mixer sequentially. The sequence is expressed in the following flow chart and cannot be changed. The deviation from this sequence will increase variation and affect the Feed quality. The PLC programmer takes care of sequence of operation with interlocks to avoid errors. Cycle time is sum of raw material addition time and mixing time. In other words, for each cycle time, one batch will be discharged from mixer. When cycle time is more, the productivity of the plant decreases and vice versa. During pilot production, the operation team should do few trials to evaluate actual mixing time through CV tests for their own recipe. In regular operation, the QA team should check and verify the sequence, dry mix time and mixing time to ensure the quality of feed.
Residual ingredient built-up in mixer
The mixer should be clean and free from built-up of material. These materials are basically nutrients and have high moisture. Hence these locations are potential points for microbes like mould and bacteria to grow. These points are called black spots where microbial contamination starts. Picture shows potential microbial contamination points. Scrapers should be used to remove such materials. Built-ups are very high in Cattle feed mill, because the recipe contains molasses. Extra care should be taken in cleaning of mixer.
Over load or under load of mixer
Once the batch size is a derived, it should be maintained as a constant. Increase and decrease of batch size from the derived value will over load or under load the mixer. This will affect the mixing performance.
Leakage at inlet and outlet gates
The ground ingredients are stored in two or three different bins above batch mixer. There are slide gates or dosing gates or flaps at the bottom of bins. Similarly, there is a flap at the bottom of mixer to discharge the materials after mixing. Leakage at gates of bins or mixer flap leads to over load or under load the mixer. As a result, it affects the mixing performance. Leakages at gates are not visible from outside. Hence leakage should be checked critically.
Dripping of liquid at spray nozzles
The liquid ingredients in the recipe are dosed and sprayed in mixer through nozzles by liquid proportioning system. There is a possibility of dripping of liquid from the nozzles after dosing the liquid ingredients. This creates cleanliness issues inside the blender. Hence dripping of liquids should be avoided by incorporating systems like self-cleaning nozzle.
In addition to above check points, the following points should be checked to have effective mixing process

High variation in particle size
Worn-out or broken ribbon or paddles
Improper mixer installation
Incompatibility of physical characteristics of ingredients being mixed
Error in batching system
Rotational speed

In Feed milling, until mixer, the process follows batch operation. After mixer, it is a continuous process. The purpose such design is to achieve uniform compound feed for best animal performance. Hence the mixing process plays an important role in feed milling to achieve best feed quality, feed mill productivity and more importantly animal performance.
by M Kanagaraj, Catalyst Techvisor Private Limited

The post Role of Mixing in delivering balanced diet appeared first on Benison Media.

Art of Grinding-Particle size reduction

Ashwani Verma — Mon, 23 Jul 2018 06:12:57 +0000

Particle size reduction is the first engineering step in Feed manufacturing process. The objective of particle size reduction is to improve feed efficiency by increasing surface area of grains and other ingredients. This increased surface area of nutrients is exposed to animal digestive system. This leads to complete digestion of ingredients and results in better feed efficiency. Researchers are continuously studying the Effect of particle size on animal performance – especially in broiler performance. It is also recognized that size of particle and uniformity of particle size are important for pellet quality and animal performance. The research data clearly suggests that particle size is more critical in mash feed than pellet or crumbled feed. For a pellet feed manufacturing plant, the grinding is the second largest energy consumption process. Hence, the grinding process is lot more critical in terms of both animal performance and feed mill productivity. There are two types of machines used for particle size reduction-Hammer mill and Roller mill. Most of the feed mills uses hammer mills. Particularly, aqua feed manufacturing plants uses roller mill after hammer mill to achieve fine grinding.
In Hammer mill, set of moving high speed hammers breaks the grains which comes in contact by hammering effect. Whereas in roller mill, particle size is reduced by pair of rotating rolls by constant compression force. The roller mills produce more uniform particle size than hammer mill.
Challenges in Grinding
The efficiency of hammer mill depends on several factors (Martin, 1985). Some of the key factors are:

Tip speed
Hammer design
Number of hammers
Open area in screen
Hammer mill motor HP or kW
Moisture content of raw material
Gap between hammer tip and screen (sieve)
Raw material flow rate to hammer mill
Air flow through hammer mill
Raw material screening system

The first five points (Tip speed, Hammer design, number of hammers, Open area in screen and Hammer mill motor HP/ kW) are arrived by the machine manufacturer while designing the hammer mill. But the user has a main role in providing the data of raw material, tentative recipe and the local conditions etc. to choose the right machine by the supplier. These parameters should be maintained constant in hammer mill.
Maintaining minimum variations in rest of the points is a big challenge for the operation team.
Moisture content – When moisture content of grain is low, the hammer mill produces more fine particles and increases the throughput of hammer mill (TPH) and reduces the Specific energy(kW/Ton) of hammer mill. When the moisture content of raw material is high, grinding produces coarse particles. The performance of hammer mill is consuming more Specific energy and reduces the throughput.
Gap between hammer tip and screen (sieve) – The gap will increase along with wear and tear of hammers. Increased gap affects the performance of hammer mill both in productivity and quality of grinding.
Material flow rate –High flow rate of materials gives coarse grinding as well overloads hammer mill motor. Low flow rate affects the throughput of hammer mill.
Air flow through hammer mill – Air will be trapped in the grinding chamber because of high speed rotation of rotor and hammers. Air trap inside the grinding chamber leads to grinding storm and results in poor performance of hammer mill. The air trap will be avoided through proper functioning air assist system.
Raw material screening system –It is very important to screen the materials from impurities like stone, maize cob, iron and non-ferrous components, dust etc. Especially when metal components enter the grinding chamber, it brakes the hammer and damages the screen. Stone removers, jute removers and magnets are used to screen the materials.
Critical check point in Grinding

Particle Size and Distribution

Both particle size and particle size distribution are important for animal performance and feed mill productivity. The research data recommend to have particle size of 600 to 900for corn-based broiler diet to achieve the optimum animal performance. Geometric Mean Diameter (GMD) and Geometric Standard Deviation (GSD) are the key factors of interest. Another important factor in particle size analysis is the distribution of particles. A histogram is plotted with the data of particle size analysis. It is important to calculated, 68% of particles lies between what particle sizes.
The particle size and its distribution should be continuously monitored and recorded. Particle size is critical to quality factors (CTQ) to a pellet press. Because it influences both feed quality (PDI) and productivity.

Specific Energy of Hammer mill

It is a measure of the actual productivity of grinding equipment, (Hammer mill or roller mill). The Specific energy is the amount of electrical energy consumed by the equipment (hammer mill) to produce 1 ton of ground material. It is expressed in kW/Ton. To measure specific energy of hammer mill, it recommended to have a separate energy meter and a timer in the hammer mill’s electrical circuit. The timer helps to measure the running time of hammer mill. Some feed millers install the energy meter in the mash section. Modern hammer mills are having provisions to measure these metrics. Periodically, the energy consumption in kW and output of hammer mill in tons are measured. Specific energy is calculated as
Specific Energy = Hammer mill energy consumption in kW  Hammer mill output in tons
The metrics of Specific energy should be continuously monitored and recorded. By analysing this metrics, the operation team gets lot of insights about type of formulation, raw material conditions like moisture content, hammer mill conditions, wear and tear of hammers (beaters) and screens (sieves). The data isalso useful to implement Condition Based Maintenance (CBM) program to hammer mill.

Maintenance cost

The spare parts used in feed mill can be classified in two types:

Production consumable spares and
Machine spares

Hammers and screens can be accounted as production consumable spares. All other mechanical and electrical spares associated to hammer mill can be accounted as machine spares. The purpose of this classification is to analyse the cost of grinding more specifically.
Material of construction (MOC) and hardness of the hammer is critical for its wear resistance property. For sieves, hole pitch and hole pattern are important factors which influences the throughput (TPH) and specific energy of hammer mill and the particle size distribution.
On daily routine, the following check points should be checked and take appropriate action for healthy hammer mill operation
Magnets condition
Hammer condition
Sieve conditions
Leakages in hammer mill
The particle size of ground material is a critical to quality factor in a feed mill. Because, it influences the performance of every sub process of feed mill – mixing, conditioning, pelleting and cooling. In addition to that particle size influences feed quality. It has the direct connotation with digestibility of feed. Hence periodic evaluation of particle size is a critical analysis for a feed mill QA program. Periodic monitoring of hammer mill performance is an important activity as a in-process quality assurance (IPQA) program.
This is the part-II of the column contributed by M Kanagaraj who is an expert on feed milling, for any further details he can be reached at gmkraj70@gmail.com
References are available upon request.
by M Kanagaraj, Catalyst Techvisor Private Limited

The post Art of Grinding-Particle size reduction appeared first on Benison Media.

Factors influencing Feed quality and Feed mill productivity-Pelleting Tips

Ashwani Verma — Mon, 21 May 2018 12:51:11 +0000

Pelleted feed is an outcome of several sub process of feed milling process. The pellet feed quality and feed mill productivity depend on those sub process of the feed milling. True indicator of feed quality and feed mill productivity is shown in figure 1.
The mission of every feed mill should be achieving and maintaining those indicators. This article focuses on the factors influencing both Feed quality and Feed mill productivity.Before discussing the topic of Pelleting tips, a good understanding of the feed milling process is important. Feed formulation is the key planning action of feed milling process. Nutritionists around the globe constantly striving to achieve optimum nutrition with minimum cost by using modern tools and technologies. Researchers are continuously working on to find alternatives raw materials. Various feed ingredients like corn, corn gluten, soybean meal, wheat, wheat bran, rice polish, rice bran, de-oiled rice bran, peanut meal, cotton seed meal, coconut meal, fish meal, meat cum bone meal, molasses etc. are used to get the nutrient requirements of the animal. The raw materials are selected based on the animal specific,market specific and most importantly cost specific parameters. Major portion of these ingredients are bigger in particle size and some of them are of finer particle size. Hence the particle size reduction is an essential process in feed milling.The nutritionist selects the raw materials based on the nutrient requirements of the animal and the best formulation is arrived at with least cost linear programming. This recipe is transferred to feed mill as a starting point of the process. From this point onwards, the feed quality and feed mill productivity, all depends up on the proper feed mill operation.
The first step of feed milling is blending of various raw materials as per the recipe. The grinding process is necessary since some of the raw materials are of bigger particle size. The outcome of the first process is mash or meal form of feed. The purpose of second process of feed milling is to soften the mash or meal feed through heat and moisture. The output of this process is conditioned mash feed. Third process compresses the softened mash feed and form a dense mass, which is at higher temperature from ambient temperature. It is also called hot pellets. The final process in feed milling with draws the heat and moisture from the dense mass and forms shaped mass. This is called the finished pellet feed.
The following series of points focus on preparatory processes before pelleting process itself

Batching or proportioning
Grinding or particle size reduction
Mixing of ration
Conditioning of ingredients
Cooling of compound feed

Batching or proportioning
The feed plants are globally designed in two ways
pre-grinding
post grinding
In pre-grinding process flow, the grinding is done before the batching process. In this design big particles in formulation like maize and other grains only passed through Hammer mill. Theoretically, there should be less specific energy (kW/T) in Hammer mill. This should be validated in each feed mill. In post-grinding design, the grinding is done after batching. In most of the cases, all raw materials are passed through Hammer mill. Either way, the plant is designed, the accuracy and repeatability of batching system is the key to achieve optimum nutrition designed by the nutritionist. The modern batching system is a weighing system consists of load cells and signal processing unit controlled by a Programmable Logic Controller (PLC). Basically it is a Measurement System like Verniercalliper, NIR etc.Hence the system should be checked and corrected periodically. It is highly recommended to use Statistical tool to monitor the batching system performance.
Challenges in Batching
Variation or error in batching system leads to deviation of nutritional values of finished feed from formulated values. This leads to either nutrient concentration or dilution. Improper nutritional concentration causes direct financial loss to the organization. The nutritional dilution may cause poor animal performance and, in a way, financial loss to the farmer.
Critical check points in Batching
1. Calibration Periodical calibration of all batching, weighing and metering systems of the feed mill minimizes the variations in measuring system. Most importantly, the calibration should be carried out to the Maximum Scale Reading (MSR) or till the measuring range of the design. The data should be recorded in Calibration register. The variation between set quantity and actual quantity should be studied batch on batch and plot it in a Run chart. It helps to identify the abnormal variations#and presents the true random variation##
2. Malfunctioning of slide gate of bins Leakage at slide gates is a common problem and unnoticed in many feed mills.Slide gate operating conditions should be monitored periodically. Because leakage at dosing gate of raw material bins and slide gates of batching bin (bin on load cells) creates error in batching process. The air pressure of pneumatic line and wear and tear in slide gates should be checked periodically and take corrective action if necessary.
3. In-flight quantity
This is another very important factor in batching process. In-flight quantity is the amount of raw material in suspension after stopping dosing screws, before it reaches the batching bin. This amount depends on design of dosing screw pitch. The screw pitch is designed based on the bulk density of raw material. The equipment supplier designed the dosing screw pitch based on assignment of certain raw material in certain bins. In operation, interchanging of bins to be avoided because it will create variations in batching.
Note:
# – Abnormal variations – which is from external sources and indicates that the process is out of statistical control
##- True random variation – which is intrinsic to the process and will always be present.

This is the part-I of the column contributed by M Kanagaraj who is an expert on feed milling, for any further details he can be reached atgmkraj70@gmail.com.
by M Kanagaraj, Catalyst Techvisor Private Limited

The post Factors influencing Feed quality and Feed mill productivity-Pelleting Tips appeared first on Benison Media.

The importance of pre-extrusion in feed Industry

Ashwani Verma — Thu, 16 Nov 2017 05:12:34 +0000

Extrusion is the heart-beat of an aquatic feed processing plant. Still it largely depends on a well designed pre-extrusion and post-extrusion process to ensure the desired nutritional and physical outcome of the extruded final product. Knowledge and understanding of the raw materials, both dry and wet (or fresh) to be used in formulations, are of utmost importance in designing and specifying a process that will optimize extrusion performance. Pre-extrusion process design plays a key role in producing extruded aquatic feeds, which are safe and environmentally friendly.
Some critical pre-extrusion processing steps
It is difficult to accentuate only a few of the processing steps that make up a complete pre-extrusion process. Following are some pre-extrusion processes which are critical for getting the desired results:
Dry ingredient intake, cleaning and storage: The range of ingredients which are generally used for the manufacture modern-day aquatic feeds, are becoming increasingly more expensive. One should therefore take care as to how to acquire, accept, handle and store these ingredients on site. The following design criteria should be taken into consideration:
1. Intake sampling and quality control
2. Flexibility in intake & storage design allows for utilizing a wide range of raw ingredients
3. Good aspiration and dust removal from the intake pits
4. Cleaning of the raw ingredients and removing foreign plants and other materials including metals, sand and stones
5. Safe storage of raw ingredients in bulk storage silos, flat storage and dosing silos
Dry ingredient batching
Accurately combining ingredients together to create a proper formulation in order to achieve species health, species performance and production costs. All ingredients whether dry, liquid or fresh go through an accurate batching process ensuring that the final extruded product meets the species nutritional and lifecycle requirements. Process control and communicating formulation details between least cost formulation software and the field devices controlling the process play a key role in a successful feed mill design.
Size reduction
Size reduction is the first processing step where the physical and potentially nutritional characteristics of ingredients are changed. Physical ingredient size is reduced to an average particle size. Heat damage to the nutritional value of amino acids and some micro ingredients may take place when the size reduction system is not well designed or specified.
The traditional size reduction rule during extrusion is to have no particle larger than one third of the die openings in the extruder die plate. This is easily achievable using a single grinding step when producing larger extruded pellet sizes. It becomes a challenge when producing smaller pellets for shrimp and micro feed for hatcheries and ornamental fish.
Traditional hammer mill designs were in most cases inadequate for fine grinding in a single step. It was and still is common to use a course grinding hammer mill followed by a fine grinding hammer mill to achieve the required fine grinding specifications. For ultra-fine grinding, to achieve an average particle size below 300 micron, a course grinding hammer mill is used in conjunction with a pulverizer. This is a common setup for producing shrimp feed and micro feed for hatcheries or ornamental fish.A range of high efficiency hammer mills are now available in the market, capable of producing narrow particle size distribution curves with average particle size down to the 300-350 micron mark. The design of these hammer mills allow for shorter grinding chamber retention times and therefore lower grinding temperatures. Coupled with a variable frequency drive and special features in terms of breaker plate design and sieve types, these hammer mills can mill a large range of cereals and other aquatic feed ingredients at lower cost compared to traditional systems. Figure 2 shows typical application range for size reduction technology in relation to average ingredient size and feed type requirements.
In addition an attempt in design should be made to mill only the ingredients in the formulation that requires size reduction. Funneling unnecessary ingredients through the size reduction system increases operational costs through wear and could also increase capital cost through a higher capacity requirement.
More critical pre-extrusion processes
Other pre-extrusion processing steps of critical importance are:
1. Mixing: a range of single shaft ribbon mixers, single and twin shaft paddle mixers are on the market. The ultimate goal is to deliver a homogeneous mix to the extruder surge bin, representing the specific formulation to be extruded. A well-designed mixing environment makes provision for additional liquids and dry ingredients as well.
2. Vitamins & minerals addition: it is common for large feed mills to have dedicated micro ingredient dosing sections. Such capability provides more control and could limit costs when compared to pre-packed vitamins and minerals.
3. Fresh ingredient intake & preparation: the demand to include fresh meat, fish and other wet by-products into the formulations of aquatic species is increasing. Great care should be taken to ensure ingredient streams do not cause cross-contamination hazards. Keeping dry, fresh and final product separated. Fresh products could be pre-processed into slurries, hydrolysates, concentrates and other forms prior to inclusion into the feedstock stream.
Critical process design aspects
A range of operations make up the pre-extrusion process. The discussion in this article covered some aspects of the more important operations. Ultimately the process has to be engineered into a three dimensional space that will meet operational requirements and other feed milling aspects that are frequently overlooked:
1. Feed plant zoning in line with functional and feed-safety requirements Ultimately the pre-extrusion process should supply meal to the extruder that will allow the extrusion operation to be consistent, constant and easily controllable. This indeed, is a cost efficient and reliable way.
2. Layout design and transitional equipment sections that will minimize cross contamination and segregation of mixed formulations
3. A safe environment for workers
4. Dust and odor control
5. Sound insulation
by Paul Eijmberts, Ottevanger

The post The importance of pre-extrusion in feed Industry appeared first on Benison Media.

Innovations in Feed Mill Efficiency and Feed Safety

Ashwani Verma — Wed, 01 Nov 2017 10:11:31 +0000

There has been consistent increase in the demand on human food supply from farmed animals in line with increase in global human population. Animal protein supply has to be affordable and better feed efficiency of livestock and poultry will play a major role in realizing this demand. Feed cost accounts for more than 70% of poultry production cost and hence, efficient feed milling can reduce the cost of feed production. In addition to affordability, the modern agriculture has focused on feed safety as a global concern for several years now. India’s growing middle and upper social strata show strong conscience towards high food quality and safety prompting feed millers and integrators to use best feed management strategies to keep molds, bacteria and mycotoxins at bay. This article reviews recent innovations in feed mill efficiency, mold and mycotoxin management.
Feed mill challenges
Although initially, feed raw materials have an average moisture content of 12%, its hammer-mill-crushing, grinding and ingredient mixing stages let moisture evaporate and thereby decrease the initial moisture content often to below 11%.To become profitable, this loss needs to be recovered to obtain 12% moisture in the finished feed. Figure 1 illustrates a typical moisture profile during the feed manufacturing process. Inferior quality wet steam added during feed conditioning, however, condensates during the cooling stage resulting in vast breeding grounds for molds and bacteria around the feed particles. Dry steam application in the conditioner is more challenging compared to wet steam application.To avoid mold and bacterial contamination of feed during the cooling process, often finished feeds are being produced with lower moisture content than initially contained by its feed raw material ingredients, leading to a financial feed efficiency loss. Such losses have a significant impact on a commercial millers’ management by feed volume, quality and value. Poultry integrators often suffer from reduced bird’s growth performance.
Further, the Indian poultry feed industry suffers from poor pellet feed quality in terms of PDI, hardness, fines, etc. The main reason, along with many other factors, for poor pellet quality seems to stem from the use of poor quality steam.
Since the Indian modern agricultural industry is fully aware of the presence of molds, pathogenic bacteria and mycotoxins causing strong economical setbacks in feed quality, animal health condition and ultimate profitability, proper management strategies to combat these feed-efficiency impacting trilogy need to be implemented for strong animal health performance and quality assurance.
Feed mill solutions
Commonly water is added into the feed mixer to prevent moisture loss during feed production in spite of knowingtwo major risks; (i) wetting the feed dough increases the feedstuff’s surface tension (ii) potential mold growth. Surfactants reduce the surface tension and allow even moisture penetration of mixed feedstuff, thereby reducing mold formation by wet spots(Figure 2). The feed dough becomes smoother consuming less energy and higher dies throughput. Here strong production capacity improvements and energy savings can be obtained as the pelletizer accounts for about half the energy consumed during feed milling.
Activated propionates
Moldgrowth infeed raw materials and processed feeds are persistent during harvest, transportation, storage and processing periods and become a higher challenge under tropical humid and warm climate conditions. Aside from consuming the feed raw materials’ nutrients, molds produce mycotoxins or block respiratory functions – all leading to heavy impacts on animal’s health and performance. Mold control is commonly being managed with propionic acid and its salts. To more efficiently break through the mold’s cell wall, micelle-driven activated propionates can be used as they increase the cell wall’s porosity.This leads to stronger decrease in the mold’s cytoplasmic pH leading to cell death (Figure 3). The synergistic mold-inhibiting acid blend further assures a long lasting antifungal effect.
Feed moisture management through efficient dosing systems
Moisture retention times above 80% are key factors for high quality feed storage with concomitant moisture and nutritional levels prior to animal feeding. The Moisture Management System (MMS) with its real-time in line moisture determination during feed mixing guarantees optimal moisture content throughput and strong mold and bacterial inhibition during feed processing. The MMSis available as moisture measuring (i) “stand-alone” and (ii) interface-card connected application paves the way for optimal feed mill operation with high quality standards by adjusting the water-mold-inhibiting-product mix to the real-time moisture content of the raw feed materials during mixing.
The rapid mycotoxin analysis
Out of the more than 500 mycotoxins presently known, six (AF, DON, FUM, OTA, T-2/HT-2 and ZEA) are being recognized as the most harmful to livestock growth and health performance, especially considering the use of multiple feed ingredients. Thus, strong and effective quality control is needed to restrict and allow only high quality feed raw material entrance to feed mills. Here, a rapid mycotoxin analysis needs to be in place! Sophisticated analytical methods, such as HPLC and LC-MS/MS are certainly more precise; however, time-consuming to obtain acceptable results at the feed mills entrance area.
Hence, a rapid mycotoxin analysis kit is developed which can analyze the most animal-performance inhibiting six mycotoxins of present industry relevance in less than 15 min based on theanalytical lateral flow-technology. Additionally, customers analyzing their more than 50 feed raw materials and finished feeds by using this technology, can get connected to master database called “The Nutriopt Mycotoxin Advisor”. Real-time regional mycotoxin analyzed updates comparable with their own non-disclosed situation will be provided to the customers and also the respective advise on inclusion rates of mycotoxin binder into feed. This is a unique approach to assist quality assurance and animal health performance in modern feed milling of India.
Conclusions
Enhanced process moisture management and microbial risk management assist poultry producers in assuring feed safety and to further increaseprofitabilityfrom their feed sales or poultry performance.
To know more about rapid mycotoxin analysis kit, please contact Swamy.Haladi@trouwnutrition.com
by Swamy Haladi, Kai-J. Kuehlmann, Paul Koolen, Trouw Nutrition

The post Innovations in Feed Mill Efficiency and Feed Safety appeared first on Benison Media.