Cleaning of Porous Metal Products

摘要

Porous metal products are used in many industries because of their strength, durability and filtration efficiency. In process filtration, porous metal filters are cleaned-in-place (CIP) during backwash at the end of a filtration cycle. Changes in the sample streams or process upsets can result in filtration media that will no longer backwash effectively. When this occurs it may be necessary to remove fouling material or foulant by cleaning methods other than backwash. This presentation addresses some of the alternative methods of cleaning that can be done when backwashing is no longer effective. Sintered metal media can be cleaned in a variety of methods depending on the type of foulant and it's proximity to the media surface. However, before cleaning the user must understand the extent of the fouling of the media and the chemical components involved. Then one can address the methods used for cleaning the porous metal media. This can be determined using non-destructive test methods such as bubble point, uniform bubble and air permeability of the filter element. In some cases it is necessary to use destructive test methods to reduce samples size for evaluation purposes. Destructive testing may include using a PMI capillary flow porometer to evaluate pore size distribution and air permeability. SEM microscopy and EDAX elemental analysis are used to determine the extent of fouling of the media and chemistry of fouling components. This presentation gives examples of two different commercial filter applications where filters were subjected to many filtration campaigns before being sent to a professional cleaning company. The end user would like to determine if cleaning was effective and filter media can still be used after several years in service.