Method and apparatus for treatment of articles in a fluidized bed

A method of operating a bed of gas-fluidised particulate material, comprising extracting gas from the particles of the particulate material at a localised region of the bed adjacent an opening communicating with the bed below the top of the bed, which gas extraction takes place across said opening and at an extraction rate sufficient to defluidise the particulate material in that region of the bed to an extent which provides adjacent that opening a wall of packed particulate material which is effective to obturate that opening whilst permitting the passage of an article through that opening and the packed particulate material constituting that wall into the gas-fluidised particulate material of the bed.

A method of treating an article which is advanced along a path in a bed of gas-fluidised particulate material, comprising extracting gas from the particles of the particulate material at a plurality of localised regions of the bed in said path, which regions are spaced apart and extend substantially vertically within the bed across said path, the rate of gas-extraction from each said regions being sufficient to defluidise the particulate material to an extent which provides in the gas-fluidised bed a wall of packed particulate material, which wall is effective to obturate said path, whereby the bed is divided into a plurality of separate parts.

Apparatus for treating an article in a gas-fluidised bed of particulate material, comprising a container for the gas-fluidised bed, which container is formed with an opening for passage of an article into and through the bed, and gas-extraction means mounted in the container adjacent the opening for extracting gas from the particles of the particulate material across said opening at a rate sufficient to produce a wall of packed particulate material which is effective to obturate the opening and prevent escape of particulate material while permitting an article to pass through the opening.

Apparatus for treating an article in a gas-fluidised bed of particulate material, comprising a container for the gas-fluidised bed, and a pair of vertical gasextraction ducts mounted in the container, and spaced apart to define a path for movement of an article from one part of the container to another for extracting gas from the particles of the particulate material across said path at a rate to produce a wall of packed particulate material between the ducts which wall is effective to divide the bed into separate parts.