Flow restrictor in a pulse cleaning system

Abstract

Particulate material is separated from high temperature gas using a number of elongated porous walled tubular filter elements. The dirty sides of the filter elements are operatively connected to a dirty gas inlet to an upright vessel, while the clean side of the filter element is in operative association with a clean gas outlet. A separated particle outlet extends from the bottom of the vessel. Cleaning of the filter elements takes place by a pulse of high pressure cleansing gas which is supplied to the clean side of the filters. In order to prevent thermal shock or mechanical damage to the filters, especially since the cleansing gas is of a lower temperature than the gas being filtered, the volume of cleansing gas is positively controlled. This is accomplished by placing a restrictor (e.g. orifice or nozzle) between the high pressure source of cleansing gas and a reservoir having a volume sufficient to effect cleansing, but insufficient to cause thermal shock. A conduit, with a quick acting valve in the conduit, extends from the reservoir to the clean side of the filter elements. Even if the valve sticks open, there is insufficient volume and/or flow rate of cleansing gas to cause thermal shock to the filters.