Introduction
We are pleased that you have chosen the Pelletizer PE50 by Triventek for your company.
This technology is the subject of several pending patent applications worldwide, including US patent application No.
10/363,762 and European patent application No. 01960192.1.
To obtain long and trouble-free operation of the equipment we recommend reading this manual carefully. All new opera-
tors of the equipment should also familiarize themselves with the content of this document.
1.1
What is Dry Ice?
Carbon dioxide is a chemical compound formed by combining one atom of carbon with two atoms of oxygen and is
expressed by the chemical symbol CO
2
. It can exist in three states: a gas, a liquid or as a solid.
Dry ice is solid carbon dioxide (CO
2
). The unique property of carbon dioxide is that at normal, atmospheric pressure
and temperature, it changes state directly from solid to gas without going through a liquid phase. This process, called
sublimation, makes the ice ‘dry’.
Dry ice is stable at (minus) -7ºC 9/-109ºF, at atmospheric pressure. It expands up to 800 times by volume when it subli-
mes, and this property is exploited for instant cooling of food and pharmaceutical products during processing, trans-
portation and storage. The properties of dry ice are also used for other industrial applications, such as dry ice blasting
(cleaning of machinery through thermal shock).
1.2
The Dry Ice Pelletizing Process
The Pelletizer takes liquid carbon dioxide from the carbon dioxide storage vessel and feeds it into the main pelletisati-
on chamber. Within the main chamber three injection valves are located to allow the liquid into the three compressing
chambers.
The volume of liquid CO
2
injected into the compressing chambers, and consequently the rate of dry ice production, is
determined by varying the valve opening time.
A sudden pressure and temperature drop occurs when the liquid enters the compression chambers, by which approxi-
mately 50% transforms into ’carbonic snow’ and about 50% transforms into gas (known as ´revert´ gas).
The revert gas is vented to the atmosphere.
An electrical motor with a gearbox drives a crank shaft and 3 mechanical pistons in order to compress the carbonic
snow that has been retained in the compression chambers. The snow becomes a block of dry ice which is subsequently
pressed through extrusion plates to form ‘spaghetti’ strings. The strings will tend to break at the break line formed by
each compression stroke to make the characteristic ‘pellets’
.
