Why steam conditioning?
Published: April 3, 2007
By: Giuseppe R. Bigliani - Feed Technology Solutions
Pellets cost money, and good pellets cost more money.
Operators are constantly challenged for maximizing production while improving product quality. Feed formulation, particle size, die selection, cooling, etc. can help them meet this challenge, but controlling the conditioning system is a pre-requisite for the production of quality pellets and optimizing production.
The conditioning process is the most important component of any feed pelleting system, as far as pellet quality is concerned. In the conditioning process, a great deal of attention must be paid to moisture content, steam quantity and control, retention time and blending action within the conditioner.
The basic objectives for conditioning are:
Operators are constantly challenged for maximizing production while improving product quality. Feed formulation, particle size, die selection, cooling, etc. can help them meet this challenge, but controlling the conditioning system is a pre-requisite for the production of quality pellets and optimizing production.
The conditioning process is the most important component of any feed pelleting system, as far as pellet quality is concerned. In the conditioning process, a great deal of attention must be paid to moisture content, steam quantity and control, retention time and blending action within the conditioner.
The basic objectives for conditioning are:
1. Blend
2. Hydrate
3. Heat
During the conditioning process, moisture and heat penetrate the surface to the core of each particle in the ingredients of the feed, disrupting the structure of starch. By altering the starch structure, the digestive enzymes can breakdown starch more effectively to be utilized straightforwardly, improving digestibility of the product. Gelatinization of starches is a function of temperature, moisture and time.
Temperature and moisture are required to activate starch and proteins (natural binders) to make high quality pellets. Another benefit of conditioning at high temperatures and for the right amount of time is to minimize pathogen and spoiling microorganisms contamination in the feed. Other benefits are to reduce power requirement (specific energy consumption) and to decrease die wear. The moisture acts as a lubricant decreasing the amount of friction (abrasion index) created by the feed passing through the die hole, doing less work to form the pellets. Production efficiency can be increased and fines are reduced.
Conditioning uses steam because of these two main reasons:
Heat
Temperature and moisture are required to activate starch and proteins (natural binders) to make high quality pellets. Another benefit of conditioning at high temperatures and for the right amount of time is to minimize pathogen and spoiling microorganisms contamination in the feed. Other benefits are to reduce power requirement (specific energy consumption) and to decrease die wear. The moisture acts as a lubricant decreasing the amount of friction (abrasion index) created by the feed passing through the die hole, doing less work to form the pellets. Production efficiency can be increased and fines are reduced.
Conditioning uses steam because of these two main reasons:
Heat
a. Gelatinization of starch
b. Plasticize protein
c. Minimize pathogen organisms
Moisture
a. Gelatinization
b. Lubrication
c. Soften
d.Overcome shrinkage
Steam can be delivered to the conditioning system in three forms (figure 1):
-
- Wet – High proportion of moisture in the form of water droples
- Saturated – All the moisture has been vaporized
- Superheated – Saturated steam heated further
- Wet – High proportion of moisture in the form of water droples
FIGURE 1
The most effective mean of moisture and heat addition to the feed is using dry saturated steam because this maximizes the relationship between feed temperature and percent of moisture. Wet steam produces less feed temperature because of moisture limits. Superheated steam maximizes feed temperature with limited amount of water addition from condensation (must cool first). Dry saturated steam is a prerequisite for proper conditioning.
Once the condensation takes place on the surface of the mash feed particles, both the heat and moisture begin to migrate inside because of the difference between the surface temperature and the interior temperature of the particle. This follows the principle of diffusion: where there is movement of heat and moisture from areas of high concentration to areas of low concentration. The heat supplied by the condensed steam provides the energy to drive the imigration.
The ingredients of the mash feeds typically have low heat transfer coefficients so the process of heat and moisture migration is relatively slow. This brings into focus issues related to mash particle size, retention times, and optimum conditioning. The smaller the particle size, the more thorough the heat and moisture can penetrate to the core of the mash feed particles in a given amount of time, resulting in a soft, moist particle
core that will elasticize for ideal conditioning and pellet formation (figure 2).
The rate that feed mash passes through the conditioner is controlled by two factors that can be adjusted to obtimize retention time. These two factors are interrelated, not independent:
- Pick (paddle) angle
- Shaft speed
FIGURE 2
Figure 3 illustrates the relationship of percent of moisture and feed temperature.
Figure 4 illustrates the rise in temperature per moisture percent.
A properly designed and functioning steam system will maximize conditioning temperatures in feeds for different moisture contents.
A properly designed and functioning steam system should have the following objectives:
- Properly sized components (pipes, valves, etc.) and adequate insulation that permit the use of low pressure saturated steam
- Components that have desired performanc caracteristics. Precise steam pressure control, flow control, and effective condensate removal are critical in the addition of heat and moisture to the feed
- A balanced system to provide a consistent steam quality and to eliminate unwanted free water from the steam flow
- Components of the steam system providing accurate information to the operator and the control system, so proper and fast adjustments can be made.
Payback comes in the form of more efficient use of the feed by the animal (better conversion rates). Improved efficiency is due in part to heat processing which reduces pathogens and makes starches more digestible.
Durable pellets reduce waste, reduce segregation, improve palatability, increase water stability, and reduce water pollution. All these factors contribute to optimized feed efficiency. It must be remembered, however, that all factors involved in pellet quality are interrelated and must ultimately be addressed if the pelleting process is to be successful.
Durable pellets reduce waste, reduce segregation, improve palatability, increase water stability, and reduce water pollution. All these factors contribute to optimized feed efficiency. It must be remembered, however, that all factors involved in pellet quality are interrelated and must ultimately be addressed if the pelleting process is to be successful.
REFERENCES
Behnke, K. C.: Factor Influencing Pellet Quality. Departament of Science and Industry, Kansas State University, Manhattan, KS
Leaver, R.H.: The Pelleting Process. Sprout-Bauer, Muncy, PA.
Lemon, B.f.: General Pelleting Principles. CPM Co. Crawfordsville, IN.
Mair, C.: A news type of conditioning System. Cormal Technology Ltd., Grantham, Lincolnshire, UK.
Schoeff, R W.: Feed Manofacturing Technology IV. Ameridan Feed Industry Asocciation. Arlington, VA.
Stevens, C.A.: Starch Gelatination and influence of Particle Size, Steam Pressure, and Die Speed on the Pelleting Process, Kansas State University, Manhattan, KS.
Tan, S.C.: Why do we use Steam? CPM Pacific Pte. Ltd. Singapore.
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21 de diciembre de 2008
Regarding to effect of pressure on pre-pelleting conditioning:
Steam pressure which can be used during conditioning is usually ranged between 20 psig=138 kPa (low pressure) to 80 psig=552 kPa (high pressure). According to some researches (Briggs et al., 1999 Maier and Briggs, 2000), steam pressure does not have a significant effect on feed quality in terms of pellet durability. The reason can be explained by small difference of the steam enthalpies at 20 and 80 psig. Enthalpy is the energy which is provided by steam to increase the feed temperature. The difference between the two pressures is less than 3 percent. So, it is better to run the conditioner at pressure between 20 and 80 psig, such as 40 psig. Using higher pressure rates is not economical due to wasting boiler energy.
4 de septiembre de 2008
After developing Sugar syrup for animal feeds it is found that the the mash sprayed with sugar syrup at 70ºC coats the feed particles uniformally which soothens it to extrude through the pellet die holes faster. The solid to solid character of sugar creates hard pellets while cooling. The above process reduces the usage of steaming the mash for pelletisation.
Dr. George Kunju John
Javaneh khorasan
5 de abril de 2008
For a good conditioning we need to adjust space betweeen of paddle tip and body conditioner in specific period.
18 de noviembre de 2018
I am making wood sawdust pellet, but I am not successful to make pellet, please suggest me how can I make 6 mm, pellet.
13 de marzo de 2012
hello, please help me to solve a big problem that i have at my factory pellet mill. in process of pelleting mill, at the inventory, rezult that are a lots lack of inventory. i dont have p[rocedures that specifing technological losses. i supose that are loss of moisture at the grinding grain process, cooling pellets, are losses at the grain transport and pellet transport. please help me if you have materials that establish procedures and studying the pellet mill process.
Thanks and regards!!!!
13 de marzo de 2012
i want to specify that this damage is not due to theft, because the factory is equipped with cameras surveillance.
please help me to discover process problems.
Jordache
9 de septiembre de 2011
Because steam power and influence of fast food and animal feed and poultry is the same target technology
21 de diciembre de 2008
We do not really need much moisture in our finished products as feed. Moisture content of the finished products should be as low as possible. Most farmers using fish feed would prefer to buy feed with lowest moisture content. The moisture serves as avenues for microbes and microbial attacks on the feed. If the feed are to be stored you need to have them as dry as possible. However for feed that are frozen or fed immediately we could afford to have some moisture. Nevertheless proper conditioning at high temperature would ensure ease of loss of moisture. When the feed comes from the die under high pressure and temperature there is tendency to loose the moisture and quick dryness. This is also aided by passage of the feed through the drying chamber where they are subjected to dry air from a central blower. Resultant feed within minutes are vey dry depending on settings of the blower.
20 de diciembre de 2008
The article Why steam conditioning? Very good. And just a question: How to minimize the loss of our feed moisture in finish product with the improvement in our steaming?
19 de diciembre de 2008
Conditioning is necessary in feed production based on extrusion. It is also needful for pelletization. Conditioning blends and gelatinizes starch. Nevertheless the extent of conditioning efect on blending is also dependent on the extent of milling. Coarse particle may not be homogenous enough even under conditioning. Conditioning also serves to reduce microbes that could be sources o spoilage to the feed. However I would recommend hot and semi wet system vapour. The semi wet system is better from experience compared to the dry. This has to do actually actually with the type starch and binders utilized. Starch gelatinizes very well for aqua feed. Corn does too but a mixture of the two based on feed optimization could give a good blend. Conditioning produces homogenous mixtures this homogenisation serves as preamble for proper distribution of nutrients mixture. It also help in the extrusion through the die. However conditioning chamber should not be too hot so as to reduce denaturation of the proteins.
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