POLLUTANTS
NOx
Croll-Reynolds’ patented NOx scrubbing technology provides extremely high removal
efficiencies (90 - 99%) for total NOx (NO2 and NO) without the need for
exotic or expensive "proprietary"
chemicals. This technology is not applicable to combustion generated NOx.
Our Surface Active packing media makes these high efficiencies possible by retaining intermediate
aqueous reaction products on its surface long enough to permit their absorption. Thus preventing
these reaction products from breaking down to form NO which would otherwise be released back into the
gas stream. It is this re-release of NO into the gas stream that limits the efficiency of conventional
water or caustic scrubbing to less than 70%.
Typically a simple aqueous sodium hydroxide solution is utilized for scrubbing. The by-products formed
in the solution are sodium nitrate and sodium nitrite. Due to the construction material required for the
Surface Active Media any chlorides, fluorides, or other compounds that would attack a 300 series stainless
steel material must be pre-scrubbed from the gas stream upstream of the NOx scrubber.
There are three sets of inlet gas parameter which define the range of practical suitability for the
Croll-Reynolds’ patented technology. They are:
NO2:NO ratio > 2:1 by mole
O2:total NOx ratio > 5:1 by mole
Total NOx gas concentration > 2,000 ppmV
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Oxidizing/Reducing Technology for combustion related NOx
For applications that are not suitable for Croll Reynolds’ proprietary technology, we can generally
offer an alternative scrubbing approach. The alternate would also utilize counter current packed bed
absorbers but in a multiple staged configuration. The first stage would use an oxidizing scrubbing
solution to oxidize the NO portion of the NOx to NO2. The second stage would use
a reducing solution to reduce the NO2 to N2. This technology can be successfully
used for varied NO2/NO ratios.
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