From: Childress, Jerry [mailto:jchildress@mcgillair clean.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 b aghouse 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 d ust cake, then bags with an expanded PTFE membrane coul d be used. Membrane bags usually control outlet particulate emissions to very low levels and are not cost prohibitive any more. The base fabri c 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, thi s could damage the fiberglass so scrubbing would be a good idea depending on the amount of HF present. U sually acid gases in moderate concentrations do not cause fabric degradation if the bags are contin uously 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 coolin g using a dry bottom evaporative cooler or a gas-to -air heat exchanger to reduce the gas temperature to a l evel where conventional fabrics could be used safely.

I hope this answers your questions. If you need an ything 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 emission s from brick kilns. Brick kilns are typically contr olled one of three ways: dry lime injection followed by a fab ric filter, dry limestone adsorber, or dry lime scr ubberfollowed by a fabric filter. (Other controls includ e wet scrubbers and a spray dryer followed by an ES P.)

EPA is trying to determine whether it would be feas ible for a brick plant to install just a stand-alon e fabric filter in those cases where the plant is alr eady expected to meet acid gas (HF, HCl) emission l imits. The brick industry has noted that this adaptation o f the technology is not demonstrated by any existin g 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 wou ldn’t be enough particulates in the kiln exhaust to coat the bags and get good performance from the fab ric filter. They are also concerned that the

uncontrolled acid in the exhaust stream could rot t he bags. There are also concerns about the exhaust gas temperatures from brick kilns being too high (n early 400F on average, as high as 668F) and the use of membrane bags on low inlet loadings. We wanted t o ask about the validity of these concerns and

whether a stand-alone fabric filter would be feasib le 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