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The Effect of the Steam Harness on Pellet Mill Production

By Phil Wellhausen, Applications Manager

When pelleting animal feeds, the steam harness is critical in achieving consistent results.

The desire of any pellet mill operator is to run the pellet mill from the beginning to the end of each batch of feed without stopping the pellet mill. Steam (moisture) issues—too much, too little or poor-quality steam—are the cause of 90% of all pellet mill chokes (downtime). Adequate steam and quality steam have a tremendous effect on the pellet mill throughput, pellet quality, die and roll cost per ton and animal/bird feed performance.

The main components of a steam harness begin with the boiler. The boiler must be sized to deliver up to a 6% steam addition. It’s ideal to have 3.5 to 5 boiler horsepower for each ton per hour of feed that the pellet mill will handle.

For example, if the boiler is supplying steam for two pelleting lines and each line will pellet 20 tons per hour, then 40 tons per hour X 5 boiler horsepower per ton = 200 boiler horsepower required. Always check with your boiler manufacturer to determine the exact sizing or output of their boiler. Remember, steam may be used for heaters or to warm fat or molasses tanks, so all steam requirements must be considered.

Steam pressure from the boiler to the plant is generally between 75 to 125 psi. There is not much need to provide steam above 100 psi, as it will generally be regulated down to under 40 psi prior to the conditioner, where it will be introduced and mixed with the mash feed just ahead of the pellet mill.

Other components of the steam harness (steam header, pressure reducing valve, shut-off valve(s), flow control valve and pipe sizes) will be addressed in another segment. Steam quantity and steam quality begin with the boiler.

To learn more about the importance of steam in pellet mills, or to contact a salesperson, visit: http://www.cpm.net/industries/animal-feed.