We have been using the heated filter
concept for many years as an efficient way to extract a dusty gas sample and
filter it prior to transportation to a gas analyzer. One of the reasons why we
filter dusty applications at the extraction point is to avoid development of a
dust / condensate slurry which would plug the sample tubing in and after the
filter.
Our customers have had various combinations
of conditions that have given rise to different configurations of heated
filters as follows:
- The standard heated filter is attached to a flue gas duct using a mounting flange. This configuration is suitable for samples at basically atmospheric pressure. The installation must be in a non-hazardous area. The cabinet requires a supply of instrument air or nitrogen to allow a blowback of the filter and the probe. This pushes the accumulated dust back into the flue gas duct.
- The standard heated filter is also available in a hazardous area configuration. The heater is rated for hazardous areas and the electrical contacts are sealed in a small explosion-proof junction box.
- Some high pressure processes, such as Direct Reduction of Iron (DRI), also require dust removal before gas analysis. We can provide a high pressure configuration of the heated filter system. However, this system does not allow blowback because of the high pressure in the process.
- A version of the high pressure configuration is available that is suitable for hazardous areas.
- Some sample points on a DRI process are also quite hot. It may be necessary to cool the sample slightly before it enters the filter. We can provide water-cooled spool pieces that are mounted between the probe and the filter valve.
- We have also developed a vertical design which can be mounted on a duct or silo where the extraction probe is required to point downward into the gas atmosphere.
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| NOVA Heated filter system mounted vertically on a process application at one of the US National Labs. (Not our standard configuration, but worked very well for this project.) |
For information on these and other gas
analyzer systems, give Mike or Dave at Nova a call, or send us an e-mail.
1-800-295-3771
sales at nova-gas dot com
websales at nova-gas dot com
http://www.nova-gas.com/
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