A new production process for the formation of block dry ice from pellet dry ice is available, providing a reduction in the loss through evaporation that is so common to present techniques.

Eradicating the need for cutting, the pellets are solidified and shaped when making the desired dry ice block, with a reduction in loss through evaporation from 30% to around 10%.

At present, when thinking of dry ice thoughts of the pellet type dry ice are most likely to spring to mind, having been the market choice for a number of years now. Since Iwatani pioneered with its ‘Bead Dry’ product, this pelletised version has been firmly rooted in the dry ice market. The new method makes advantageous use of these pellets.

Production processes
When liquid carbon dioxide, which is in a saturated state with a pressure of 2 MPa and a temperature of -20°C, is emitted into the air, dry ice is produced based on the principle whereby 60% becomes gas due to the latent heat and 40% becomes snow.

With the conventional dry ice production method currently in use, the snow made in this way is pressed into shape using a hydraulic piston and the first rectangular solid is produced. This is then cut into square shapes and may even undergo further cutting at plants called slicing centres, where the block dry ice product is cut using devices such as band saws and circular saws.

In contrast, the new technique makes pellets out of the snow with the pellet production devices pushing out snow and forming it into fine rods. These are broken into a uniform length and made into pellets, which are shaped by a press or reformer and shaped into finished products. The new process therefore completely removes the need for cutting.

This in turn leads to a reduction in evaporation loss and improvement in working environment, as the atmosphere of billowing carbon dioxide smoke from cutting is no longer an issue.