Patent ID: 7445935

Claim:
A process in which an elastic fluid is contacted with a particulate solid, which process comprises the steps of: (a) providing a substantially vertical elongate tubular containment zone containing a charge of the particulate solid, the volume of the containment zone being greater than the settled volume of the charge of the particulate solid; (b) providing upper retainer means mounted at the upper end of the containment zone, the upper retainer means being permeable to the fluid but adapted to retain particulate solid in the containment zone, and follower means movably mounted in the containment zone beneath the charge of particulate solid for movement upwardly from the lower end of the containment zone upon upward flow of elastic fluid through the containment zone at a rate beyond a threshold rate; and (c) causing the elastic fluid to flow upwardly through the containment zone at a rate which is sufficient to cause particulate solid to rise up towards the upper end of the containment zone and form a cushion of particulate solid against the underside of the upper retainer means and which is in excess of the threshold rate so as to cause the follower means to move upwardly until it abuts against the underside of the cushion of particulate solid.