Carbon infrared oven for jam production
Jam jars are filled in a continuous process with hot jam on a bottling line. Before filling, jars need to be rinsed and this was previously carried out by a hot water rinsing process. Heat was necessary to prevent thermal shock and possible breakage of the glass, as jars are stored at temperatures as low as –5°C and jam is at temperatures up to 97°C during filling. The glass manufacturers recommends a maximum temperature difference of 84°C. With the hot water rinse, the jars were pre-heated. However, the hot water rinsing plant was becoming increasingly inefficient.
Consequently, the choice fell on a modern air-rinsing plant, bearing in mind that this would require a separate jar-heating system. It was decided to investigate the potential of infrared heating. Finally, a 50.4 kW carbon medium-shaft furnace was installed that fits over an existing conveyor belt and comprises two 25.2 kW zones, each fitted with three carbon medium wave emitters. Two emitters per zone can be switched on for jars up to 100 mm height and three emitters per zone for jars of a height exceeding 100 mm.
An optical pyrometer measures the temperature of the jars as they leave the oven. The furnace can be operated manually or automatically.