Dry ice is used wherever very low temperatures are required, but energy sources are not available. In particular, dry ice is used in the foodservice industry, and when transporting chilled and frozen food, or other goods and materials sensitive to temperature changes or requiring constant, low temperatures, such as vaccines, and other pharmaceutical formulas.
What is dry ice? Just solid carbon dioxide.
The key property of dry ice is its ability to sublimate to gas without intermediate liquid stage, leaving no residue. Dry ice is a natural, tasteless and odourless product. Thanks to these properties, dry ice can be used in many industries, such as food processing, other processing, transport, logistics, as well as pharmaceuticals and technology.
To see how dry ice is made, we visited the Włocławek plant of one of the world’s leading dry ice manufacturers, Air Products.
Liquid carbon dioxide, the material needed for the production process, is transferred to the plant via a pipeline.
The raw gas, which is required to obtain liquid carbon dioxide, is produced in various chemical processes, such as the production of bioethanol, biogas, and ammonia - we use ammonia in our installations. It is compressed, purified and liquified, and then stored in tanks at a pressure of 15 bars.
The process takes place in this installation. The tanks in which purified liquid carbon dioxide is stored have a total storage capacity of 2,600 tons. This form of the product can also be transported to customers in dedicated tank trucks.
However, we are following the production process. From the storage tanks liquid carbon dioxide is transported via pipelines to the production hall where the dry ice machines are located.
Due to the asphyxiating properties of carbon dioxide, all premises must be monitored and controlled for CO2 concentration. The premises are additionally ventilated. Employees working at the plant are equipped with glasses, gloves, and personal gas detectors. Containers in which dry ice is to be placed are thoroughly washed beforehand.
While liquid carbon dioxide in the tank is kept at a constant pressure of 14-15 bars and at a temperature of approx. -30oC, when injected into the dry ice production machines the pressure is lowered to approx. 5 bars.
These conditions allow the production of snow, which is then pressed inside the cylinder by a piston at a pressure of approx. 300 bars to obtain the final product. The ice temperature is -78.5oC.
At the Air Products plant in Włocławek dry ice is produced in three forms: pellets in two grammages, slices, and blocks. We can see here how the 16 mm pellets are poured into the insulated container.
This machine produces blocks of dry ice. The weight of each block is approx. 3 kg.
The plant is also capable of producing 3 mm pellets. This can be either a finished or semi-finished product from which dry ice slices, weighing approx. 1 kg, are made. The process takes place on this line where the pellets are pressed into slices. The product is then transported by a conveyor and is ready for packaging.
Dry ice samples undergo various laboratory tests: they are weighed, measured, with their taste and smell tested. The oil content is also analysed.
The ready dry ice is placed in sealed, isothermal containers and distributed to customers all over Poland.
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