US 5,087,272 A · Filter and means for regeneration thereof

Abstract

Method and filter apparatus for the removal of volatilizable particulate material from gas streams containing the same, and the regeneration of the apparatus when removal efficiency has decreased to a selected value. The apparatus includes a filter element fabricated, in the preferred embodiment from silicon carbide whiskers which are capable of converting microwave energy to thermal energy, with the porosity of the filter element being about 25 microns.+-.50%. This filter element, when removal efficiency has decreased to the selected value, is heated uniformly with microwave energy, which couples to the silicon carbide whiskers to convert the microwave energy to thermal energy, for a time sufficient to raise the silicon carbide whisker temperature to a value to volatilize the volatilizable particulate matter for discharge as a gas. Typically, the microwave energy is about 2.45 GHz and 1000 to 3000 watts. In the preferred form, the filter element is surrounded with a thermal insulation formed from, for example, alumina or zirconia fibers. This insulation is provided with passageways for cooling using air flow. The apparatus is specifically directed to the removal of carbon-containing particulates from the exhaust of diesel-fueled engines.

Claims13

Dependent claims

A filter-heater structure for the removal of particulate matter from a gas stream, the particulate matter being primarily volatilizable upon the application of heat, and for the regeneration of said structure, which comprises:

a monolithic filter element fabricated from silicon carbide whiskers for removal of said particulate matter from said gas stream, said silicon carbide whiskers capable of coupling with microwave radiation for converting microwave energy to thermal energy, said filter element having a nominal porosity size of about 25 micrometers .+-.50%;
a thermal insulation means substantially surrounding said filter element, said thermal insulation means provided with means to cool said thermal insulation means;
means for introducing said gas stream into said filter element;
means for conveying said gas stream from said filter element after removal of said particulate matter;
and
means for irradiating said silicon carbide whiskers of said filter element with microwave radiation of a selected frequency to couple with said silicon carbide whiskers to uniformly raise said silicon carbide whiskers of said filter element to a temperature to volatilize said volatilizable component of said particulate matter whereby said gas stream from said filter element contains said volatilized components of said particulate matter held by said filter element.

3 more elements

Dependencies are inferred from the claim text.

Filter and means for regeneration thereof

Life of this patent

Filter and means for regeneration thereof

Life of this patent

Abstract

Claims13