Method for cleaning porous metallic filters using a steam-ultrasonic technique

A method for cleaning plugged or dirty porous sintered metal filter coupon to regain filter activity comprising the following steps in sequence:

• i. arranging a filter coupon to be held at an angle between 10° to 40° from horizontal;
• ii. steaming said filter coupon for a first period of time by blasting about 100 psig steam against the filter coupon in a back flushing orientation for about 10 to 20 minutes so as to dislodge fine particles from pores within the filter coupon;
• iii. drying the filter coupon for about three hours with a device selected from the group consisting of:
• an oven, a dehumidifier, a heater or combinations thereof and where the filter coupon is heated to about 150° C.;
• iv. submerging the filter coupon in a first solution at a depth of about 1 to 1.5 inches below the surface of the first solution wherein the first solution comprises at least water and citric acid;
• v. exposing the filter coupon to ultrasound waves within the first solution for a second period of time of about 15 to 90 minutes wherein the ultrasound waves are applied to the filter coupon at a range of about 50 to 60 Hz;
• and
• vi. soaking the filter coupon in a second solution for a third period of time being about one hour wherein the second solution is about 10 wt % citric acid in water.