From: HANSEN Lars [mailto:lars.hansen@fivesgroup.com] 

Sent: Tuesday, July 02, 2013 4:22 PM 

To: Holloway, Thomas C. (Tom) 

Subject: RE: Question regarding use of fabric filters for brick kilns 

Dear Mr. Holloway, 

Thank you for your inquiry. We are pleased to respond as follows: 

As you know, fabric filter baghouses effectively control particulate emissions. The capture mechanism is 

primarily the dust cake, which typically consists of process dust and a pre-coat that is applied prior to 

introduction of process gases in the case of felted fabrics. Pre-coating is not necessarily required with 

membrane-coated fabrics, however the process dust cake is still required to meet the required 

performance and to ensure a reasonable bag life. 

We agree that for applications with very little process dust, the lack of a dust cake would negatively

impact total outlet emissions. However, I have to wonder: if there is a lack of process dust from the 

kiln, why require a baghouse dust collector? 

One additional consideration regarding the dust cake on the bags: it serves an important function for

acid gas neutralization. The cake, when consisting of partially unreacted reagent, acts as a second 

scrubbing stage, contributing significantly to the system’s overall capture of acid gases. 

Selection of fabric is critical to achieve a reasonable bag life and uninterrupted compliance. Choices for 

high temperature applications are limited to fiberglass with an upper temperature limit of 500o F; 

however fiberglass degrades rapidly in the presence of HF acid gas. Pure Teflon fabric also has a limit of 

500o F and is impervious to most acid gases but carries a very significant price premium. 

Aramid, Ryton and P-84 fabrics are generally limited to 400o F operation but these fabrics are sensitive 

to degradation not only by the acid gases but also due to the relatively high oxygen concentration in 

brick kiln gases. 

We trust this information meets your requirements. 

Best wishes, 

Lars 

Lars HANSEN 

SALES DIRECTOR - MINERALS 

Solios Environment Corp. 

6860 S. Yosemite Ct., Suite 2204 

Centennial, CO 80112 USA 

303-713-0222 - office 

303-808-5838 - mobile 
Question regarding use of fabric filters for brick kilns 

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

Wed 6/26/2013 11:00 AM 

I work for RTI International, a nonprofit research institute, and we are providing technical support to the 

U.S. Environmental Protection Agency (EPA) to develop new hazardous air pollutant regulations for the 

brick manufacturing industry. 

I understand that Solios Environment is a supplier of emission control systems such as dry scrubbers and 

fabric filters for acid gas and particulate control, and I have a question I was hoping you could help me 

answer 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. 

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 assistance you could provide in this regard would be greatly appreciated. Thanks. 

Thomas C. 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