Technical Bulletin No. 1
4Pages

The USEPA recentlypromulgated a new set of regulations for the Pulp and Paper industry.Called the ٓCluster Rule, the EPA sought to combine both air and water regulations into one all- encompassing regulation.This action has caused engineers and scientists in the paper industry to examine plant operations in light of meeting these requirements.Of particular interest are those aspects of the ԓCluster Rule pertaining to air pollution control from the bleach plant.With proper design andapplication, ԓCluster Rule requirements can easily and economically be met on modern kraft bleaching sequences using RotaBed Process modifications away from elemental chlorine can serve to reduce such pollutants.High efficiency gas scrubbers are presently used on kraft bleach plants to control the residual gaseous Cl > 2 and ClO > 2 .Mills abandon-ing elemental chlorine and substituting chlorine dioxide in bleaching sequences become ECF or ԓElemental Chlorine Free.Other mills that have switched to a nonchloride containing bleach sequence are called TCF mills or ԓTotally Chlorine Free.A summary of ԓCluster Rulerequirements was published in TAPPI, volume 81, No.2, by Kirsten Vice and Robert Carrol in an article entitled ԓThe Cluster Rule:A Summary of Phase 1. This survey provides more details about this issue. According to the Cluster Rule, the bleach plant scrubber used must reduce the HAPs by 99% or have an aggregate chlorinated HAP loading of under 10 ppmv.Mills already using fluidized bed type bleach plant scrubbers are easily meeting these requirements.The primary reason thesescrubbers are successful is due to the fact they easily handle bleach plant emission surges.There are also many other reasons: > ԙ fluidized bed gas scrubbing technology. > In general, the Cluster RuleӔ requires that pulp bleaching processes switch from those using elemental chlorine (Cl > 2 )to those using oxidants and specialized extraction sequences that produce minimal or no amount of adsorbable organic halide (AOX) compounds.These AOX compounds, though low in concentration, are suspected of causing adverse ecological and health effects. Elemental chlorine can produce chloroform and other Hazar- dous Air Pollutants (HAPs). > RotaBed and ScrubPac ٙ are trademarks of Bionomic Industries,Inc.Patent Pending. size="-2">

Some mills currently use a mist or fog type scrubber for bleach plant emissions control.In this design, scrubbing chemical is pressurized, atomized into a fog, and then injected into a containing vessel. The fog or mist flows concurrent with the gas stream.Since every gallon of scrubbing liquid requires 1 or more scfm of air or steam to atomize the liquid, the design severely restricts the amount of liquid required to operate cost competitively.In addition, every gallon sprayed in must be removed prior to the gas leaving the scrubber.Since the gas/liquid flow pattern isconcurrent, this...