World Grain - October 2019 - 58

FEED OPERATIONS

Many companies offer automated systems to
operate and control the pelleting process.

PELLET MILL
The conditioned mash enters the inner surface of the die and
is pushed through the die by a roller that forces the mash into
the die. The amount of mash being delivered to the die is controlled by the feeder delivering mash to the conditioner.
The viscosity of the mash and the amount of force used to
push the mash through the die is directly tied to the amount of
KRUVHSRZHUQHHGHGWRPDNHWKHSHOOHW7KHGLDPHWHURIWKHGLH
KROHVDQGWKHWKLFNQHVVRIWKHGLHDOVRD൵HFWWKHKRUVHSRZHU
needed.
The pelleting horsepower required is also determined by
WKHIRUPXODWLRQRIWKHPDVKDQGWKHZRUNQHHGHGWRSXVKLW
through the die.
COOLER
Ambient room temperature air is passed through the hot pellets in the cooler to remove excess pellet heat and moisture so
¿QLVKHGSHOOHWVPD\EHVWRUHGIRUVKLSPHQW7KLVSURFHVVDOVR
KDUGHQVWKHSHOOHWVDQGPDNHVWKHPPXFKPRUHGXUDEOH
58

CRUMBLING ROLLS
,I WKH SHOOHWV DUH WR EH FUXPEOHG IRU WKH ¿QDO SURGXFW D VHW
of crumbling rolls are installed at the outlet of the cooler to
crumble the pellets.
A horizontal cooler uniformly feeds the inlet of crumbling
UROOV,IDVHWRIUROOVDUHLQVWDOOHGEHQHDWKDFRXQWHUÀRZFRROer, the rolls must have a feeder roll above them to spread the
pellets evenly to the crumbling rolls.
SCREENER
For systems producing only one diameter (size) pellet, screenLQJLVRSWLRQDO,IDIHZ¿QHVLQWKHSHOOHWVDUHRND\QRVFUHHQer is needed. If a screener is used in a mill, it may be built to
KDQGOHYDULRXVVL]HSHOOHWVRUFUXPEOHVDQGUHPRYH¿QHVIURP
the pellets.
Figure 1

Pelleting system
Screener

Mash Supply Bins

Coater (optional)

CONDITIONER
The conditioner is a critical part in preparing the mash for pelleting. The mash is fed into the conditioner where it is mixed
with steam injected into the conditioner The conditioner has
a set of paddles to agitate the mash and mix it with the condensed steam to form a wet hot mash that is then delivered to
the pellet mill.
(DFKW\SHRIPDVKKDVLWVRZQFKDUDFWHULVWLFVDQGGL൵HUHQW
PDVKHVUHTXLUHGL൵HUHQWDPRXQWVRIVWHDPLQMHFWHGWRPDNH
the best mash going to the pellet mill. The original moisture
RIWKHPDVKDQGWKHDPRXQWRIVWHDPDGGHGGHWHUPLQHWKH¿QDO
moisture and temperature of the mash delivered to the pellet
mill die.
I recommend using a variable speed drive on the conditioner to control the depth of mash in the conditioning chamber. It
needs to be deep enough to absorb the injected steam at the inlet and then blend the mash and the condensed steam together
in the length of the conditioner.
The length of time in the conditioner and the added steam
GHWHUPLQH WKH ¿QDO PRLVWXUH FRQWHQW DQG WHPSHUDWXUH RI WKH
mash as it goes to the pellet die.
A properly designed steam delivery system is a must. The
steam is delivered under high pressure and enters a regulator
to lower the pressure at the entrance to the conditioner. There
also must be a liquid separator to remove any liquid in the
steam before it enters the conditioner.

Two styles of coolers are common in the feed industry: the
KRUL]RQWDO W\SH DQG WKH FRXQWHUÀRZ W\SH7KH FRXQWHUÀRZ
FRROHULVPRUHH൶FLHQWWKDQWKHKRUL]RQWDOW\SHDVDOODLUSDVVes through the column of pellets.
The horizontal cooler receives and discharges the pellets
LQDFRQWLQXRXVXQLIRUPVWUHDP7KHFRXQWHUÀRZFRROHUGLVFKDUJHVLQEDWFKHV7KHUHIRUHWKHFRQYH\RUWDNLQJWKHFRROHG
pellets away needs to have a controlled or bypass-type inlet to
¿OOWKHFRQYH\RUXQLIRUPO\

Feeder
Conditioner
Pellet mill

Cooler

Finished pellet bins

of mash by the feeder determines the load on the pellet mill
motor and drive.

Crumbler (optional)
Transfer system

October 2019 / World Grain / www.World-Grain.com

http://www.World-Grain.com

World Grain - October 2019

Table of Contents for the Digital Edition of World Grain - October 2019