Reprinted from Pollution Equipment News, October 2005

STICKY/WET FINE PARTICULATE CONTROL – CASE STUDY

Background
Sticky and/or wet particulate emissions are common to many industries, including those from combustion and other processes.  The size of these particles can be quite small, including many applications with a majority of submicron size particulate. 

These particles may be problematic from an emissions compliance standpoint (e.g., mass emissions rate or opacity), or problematic from standpoint of performance of a downstream control device.  For example, a common application seen is of an activated carbon bed experiencing excessive plugging, carbon replacement cost, and process downtime requirements because of fine particulate plugging the carbon bed.

Alternatives
Control of sticky and/or wet fine particulate has been a long-standing challenge for industry.  Alternatives for sticky or wet fine particulate control include the following control technologies:

• Baghouse/fabric filters
• Venturi scrubbers;
• Wet ESP and related devices;
• APC Technologies’ Ultra-High Efficiency Filter (UHF™TM) system.

Comparison of Alternatives
Cartridge collectors/baghouses have the primary issue that the sticky particulate will quickly blind the filters, and cannot be pulsed or shaken from the filter surface through the typical dust removal means.  Pre-coating the filter media, where technically feasible, can be excessively expensive from a material and disposal standpoint.

The venturi scrubber presents multiple problems as discussed previously, including lower control efficiency; an impractical pressure drop for one micron particles and below; a wastewater disposal issue; and overall much higher operating and maintenance cost.

Wet ESPs (and similar technology units) are typically extremely costly and often not considered as a result.

The UHF™TM system offers control efficiency of up to 99.9%, simultaneous high-efficiency removal of solid and liquid-phase particulate matter, simple operation and extremely low maintenance costs, and no process downtime required for filter replacement.

Results
In a compliance test for control of very fine, sticky particulate of a sticky nature, with particle size distribution predominantly submicron and 30% less than 0.5 micron, the UHF™ system provided 95% control efficiency, with no opacity, and no process downtime.

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