From: Childress, Jerry [mailto:jchildress@mcgillairclean.com] 

Sent: Thursday, June 27, 2013 10:58 AM 

To: Holloway, Thomas C. (Tom) 

Subject: RE: From McGill AirClean Web Site 

Tom, 

A brick plant should be able to use a stand-alone baghouse to control just filterable particulate 

emissions from a brick kiln. If the concern is low dust load and not being able to establish a good dust 

cake, then bags with an expanded PTFE membrane could be used. Membrane bags usually control 

outlet particulate emissions to very low levels and are not cost prohibitive any more. The base fabric for 

the membrane can be a woven fiberglass fabric which is good for 500 deg F continuous operating 

temperature. If there is HF in the gas stream, this could damage the fiberglass so scrubbing would be a 

good idea depending on the amount of HF present. Usually acid gases in moderate concentrations do 

not cause fabric degradation if the bags are continuously operated above the acid gas dewpoint(s). 

Regarding operating temperatures above 500 deg. F, there are some fabrics that are available for 

continuous operation at these temperatures but none with a membrane, at least none that I am aware 

of. Also, the plant could consider flue gas cooling using a dry bottom evaporative cooler or a gas-to-air 

heat exchanger to reduce the gas temperature to a level where conventional fabrics could be used 

safely. 

I hope this answers your questions. If you need anything else, let me know. 

Regards, 

Jerry 

Gerald J. Childress, National Sales Manager McGill AirClean LLC 

1777 Refugee Road 

Columbus, Ohio 43207-2119 

614/829-1350, Cell: 614/937-1816 

Fax: 614/445-8759 

 

-----Original Message----- 

From: Holloway, Thomas C. (Tom) [mailto:tcholloway@rti.org] 

Sent: Wednesday, June 26, 2013 1:00 PM 

To: Childress, Jerry 

Subject: RE: From McGill AirClean Web Site 

Hi Jerry, 

I have another question I was hoping you could help me answer, this one regarding the applicability of

stand-alone fabric filters for controlling emissions from brick kilns. Brick kilns are typically controlled one 

of three ways: dry lime injection followed by a fabric filter, dry limestone adsorber, or dry lime scrubber 
followed by a fabric filter. (Other controls include wet scrubbers and a spray dryer followed by an ESP.) 

EPA is trying to determine whether it would be feasible for a brick plant to install just a stand-alone 

fabric filter in those cases where the plant is already expected to meet acid gas (HF, HCl) emission limits. 

The brick industry has noted that this adaptation of the technology is not demonstrated by any existing 

kilns, so it is unclear what the performance would be. The industry is concerned that without the dry 

lime injection that reduces the acid gas, there wouldn’t be enough particulates in the kiln exhaust to

coat the bags and get good performance from the fabric filter. They are also concerned that the 

uncontrolled acid in the exhaust stream could rot the bags. There are also concerns about the exhaust 

gas temperatures from brick kilns being too high (nearly 400F on average, as high as 668F) and the use

of membrane bags on low inlet loadings. We wanted to ask about the validity of these concerns and 

whether a stand-alone fabric filter would be feasible for the brick industry. Any help you could give us in 

this regard would be greatly appreciated. Thanks. 

Tom Holloway 

RTI International 

3040 Cornwallis Rd., P.O. Box 12194 

Research Triangle Park, NC 27709 

Phone: (919) 316-3733 

Fax: (919) 541-7155 

E-mail: tcholloway@rti.org