N15

Low Cost Techniques to Reduce Boiler NOx

Joseph Colannmo presents a revrew of strategies useful to the working engrneer for dealing with trghtenrng emrssron regu- lations wrthrn a reasonable budget n the February issue of Chemical Engweenng, Feb , 1993, p 105 NOx reduction strategies armed at meeting the regulations wlthout incurring excessrve costs and at the same time avoldrng fines for non-com- pliance are reviewed These include Tak- ing burners out of service, Boiler derating, Burner system modrfaatron, Oxygen and combustrbles trim, Steam and water intec- tion, Staged combustion, Use of alterna- tive fuels, Flue gas recirculation, and the use of low NOx burners Each strategy IS evaluated and quantrfied in terms of ex- pected reduction In NOxemissrons and the associated cost Finally the artrcle IS nicely illustrated by two case studies

New Process for PCB Removal

Nukem GmbH (Alzenau, Germany) de- veloped a new, calcium silicate-based de- contamination process, dubbed CTZ, which, at a 50-kg/h pilot plant, showed 99 9999% destruction of liquid polychlon- nated brphenyls (PCBs) At DM 2389/m t ($1500/m t ), treatment costs are less than half those of current tncineration routes

In the CT2 process, PCBs are injected into a rotary krln operating at 899 to 800°C, which IS also continuously fed wrth calcium silicate (CaO S102) The chlonne atoms in the PCBs react wrth calcium oxide to form calcium chloride, which IS continuously removed for disposal, or for conversion to hydrogen chloride Nukem says dioxin emrssrons are below the detection lrmd of 0 1 ng/m3

applied catalysis B Environmental

Sulphur- and Chlorine-free Paper Manufacturing

Formic acid and hydrogen peroxide re- place sulphur- and chlorine-based com- pounds in the cooking and bleaching steps of a paper-pulp process being de- veloped by Kemira Oy (Helsrnkr, Finland) The dnvrng forces behind the development have been legislative mandates in Europe and the US to reduce chlorine emissions to wastewater, and to remove sulphur compounds from waste gases Called Milox, the Kemrra process 11s now running in a 158kg/h pilot plant, and could be in a 5,089 to 10,990-m t /yr demonstration plant by 1995, says process development engineer, Jorma Koltonen

Lrgnrn, the gum that binds the cellulose frbres in wood, IS removed by reaction wrth acid (HsO+) in three stages The first and last stages are carried out at WC in a solution of 80 wt -% perox-yacetic acid, formed by the reaction of Hz02 and HCOOH, while the second stage IS an 80 wt -% solution of HCOOH at 1WC Mllox pulp produces paper of similar quality and brightnessto chlorine-bleached Kraft pulp, says Kemrra

Fuel Tax on Blodlesel?

According to a life cycle analysis by Germany’s Federal Environmental Office (UBA, Berlin), rape seed methyl ether of- fers a 85% advantage in greenhouse gas emissions - on a CO;! basrs - when compared with standard diesel However, when other gases relevant to global warm- ing, such as nrtrous oxide and methane, are included In the analysd, the study says its advantage slips to 35% Using biodiesel to cut total CO2 equrvalent emissions by between 0 58 and 078% would require

Volume 2 No 2-3 - 15 June 1993