Light-ECF Bleaching Why implementing Green Bleaching Practices is a real Plus for Pulp Production Alexis Métais Alexis.Metais@itt.com 20/10/2010
Green Bleaching Practices Green Bleaching consists in implementing technology to: 1. Lower as much as possible effluents amount and their AOX, COD and color loads. 2. Guarantee a pulp quality better or similar to quality of other ECF-pulps. 3. Favor on-site chemicals production, by-products reuse and reduce the carbon footprint. 4. Reduce operating costs. 2
Bleaching Efficiency and Ecology Significantly lowering AOX can be done only by reducing the use of chlorinated compounds. Only 3 chemicals are able to efficiently remove lignin after oxygen delignification: - Chlorine Cl 2 - Chlorine Dioxide ClO 2 - Ozone O 3 Comparing bleaching lines such as D(EOP)DD and (Ze)DD, ozone bleaching reduces: - the COD discharge by 30-40 % - the AOX load by 50-65 % - effluents colour by 65 % 3
4 Ozone Bleaching Worldwide
Mondi SCP Ruzomberok mill in Slovakia D PO PO Pulp production: 480,000 adt/y from HW and SW pulps PFI 28 SR - HW: Breaking length (km) 7.8-8.5 Tear index (mnm 2 /g) 5.8-6.5 Stiffness (mn) 125-135 Viscosity (cm 3 /g) 650-700 Brightness: 89+ % ISO PFI 28 SR - SW: Breaking length (km) 11-12 Tear index (mnm 2 /g) 9.5-10.5 Stiffness (mn) 125-135 Viscosity (cm 3 /g) 550-600 Pulp strength properties slightly improved with the use of ozone bleaching. In 2005, the mill set a new world record for copy paper production at 1500 m/min. 5
Fibria Jacarei mill in Brazil Eucalyptus pulp production: - 1,200 adt/d on line B - 2,400 adt/d on line C Brightness: 90+ % ISO Ozone charge: 5 kg/adt Efficiency: 1.2 kappa/kgo 3 Producing 1,300,000 adt/y, Fibria Jacarei is the biggest mill using ozone bleaching 6
ITC Bhadrachalam mill in India Eucalyptus pulp production: 700 adt/d Brightness: 89+ % ISO ITC s feedback concerning ozone bleaching is the following (Paperex 2009): 1. better strength properties 2. about Rs 450 per MT saving in bleached pulp cost of production Savings of 7.25 /adt 3. 1 kg of Ozone replaces 5-6 kg ClO 2 as active Cl 2 7
Green Bleaching Z-Compact System Ozone production requires only Oxygen & Energy. It is a pure on-site technology needing neither delivery nor storage Producing 1 kg ozone requires: - 10 kwh - 8.3 kg of pure oxygen At the generator s outlet, the gas mixture contains 7.3 kg oxygen and 1 kg ozone (concentration of 12 % by weight) 8
Green Bleaching Example of Celtejo mill in Portugal Eucalyptus and Pine pulp production: 520 adt/d Brightness: 90 % ISO Flexible bleaching process: (OO)ZeDD, (OO)ZeDP & (OO)ZePP Total bleach plant effluent volume: 6-8 m 3 /adt for light-ecf 4-6 m 3 /adt for TCF 9
Green Bleaching Total Oxygen Reuse 34 t/day O2 30 t/day O2 + 4 t/day O3 Oxygen Applications Ozone Generator Gas scrubber 30 t/day 02 available Compressor 17.5 t/day 02 Oxygen Delignif. Oxygen Back-up Oxygen Plant Pulp in Z-Stage 12.5 t/day 02 TOWL LOX tank Pulp out ambient air Ozone Destruction System 10
Carbon Footprint Considering a pulp mill producing 500,000 adt/y of hardwood bleached kraft pulp. Conventional ECF bleaching (OO)DEopDnD is compared with a Green Bleaching sequence (OO)ZeDP. Bleaching chemicals consumption and energy requirements are taken into account in the calculation. Carbon emissions are calculated according to the following criteria: - Type of energy required by the pulp mill for operation and for on-site production of bleaching chemicals (oxygen, ozone, chlorine dioxide ). - External production, transportation and delivery of bleaching chemicals or precursors (sodium chlorate, sodium hydroxide, peroxide, sulphuric acids ). 11
Energy from the National Network Carbon emission, tons per year 60000 50000 40000 30000 20000 10000-39% 20516 12470 37959-48% 19804 45804-27% 33257 50426-51% 24910 0 Pulp mill in France NaClO3 from France DEopDnD ZeDP DEopDnD ZeDP DEopDnD ZeDP DEopDnD ZeDP Total Bleaching chemicals Transportation Energy from Electrical Netw ork Pulp mill in France NaClO3 from Spain Pulp mill in Spain NaClO3 from Spain Pulp mill in Brazil NaClO3 from US 12
Energy from Biomass 50000-56% - 56% 48028 Carbon emission, tons per year 45000 40000 35000 30000 25000 20000 15000 10000 5000-55% 18000 8155 35443 15489 35443 15489-57% 20798 Pulp mill in France NaClO3 from France 0 DEopDnD ZeDP DEopDnD ZeDP DEopDnD ZeDP DEopDnD ZeDP Total Bleaching chem icals Transportation Local Energy from biom ass Pulp mill in France NaClO3 from Spain Pulp mill in Spain NaClO3 from Spain Pulp mill in Brazil NaClO3 from US 13
Carbon Footprint Implementing ozone bleaching is an easy and efficient way to sharply decrease the carbon footprint. Moreover: Today, one carbon credit (equal to one ton of carbon dioxide) costs around 15. Reducing its carbon footprint by 20,000-30,000 tco 2 /y, a mill would earn 300,000-450,000 /y during the 10 years following the ozone bleaching start-up. 14
Economics ITC decreased its bleaching costs by 7.25 /adt by using ozone. It was possible only because 1 kg ozone replaces around 2 kg of pure chlorine dioxide. Average Costs: Oxygen, /kg: 0.06 Energy, /kwh: 0.04 Production of 1 kg ozone requires 10 kwh and 8.3 kg oxygen. Then 1 kg ozone would cost: oxygen: 0.5 energy: 0.4 0.9 15
Economics The cost of 1 kg of chlorine dioxide varies from 0.8 to 1.5 (depending on sodium chlorate production on site or its delivery to the mill). Considering 1 kg ozone replaces around 2 kg of pure chlorine dioxide (actually up to 3.4 on birch pulp in Domtar s Espanola mill, Canada), using 5 kgo 3 /adt would result in saving 3.5 10.5 /adt on bleaching chemical costs. Moreover, applying Green Bleaching practices allows the use of free oxygen from the ozone bleaching stage in oxygen delignification. Roughly 20 kgo 2 /adt are required, it would result in additional savings of 1.2 /adt. Then a mill producing 500,000 adt/y would save 2.35 5.85 M /y. With such savings the ROI would be between 1.5 year and 4 years. 16
Conclusion Environmental constraints, process efficiency and cost performance are usually seen to be in opposition to each other But by adopting Green Bleaching practices, it is now possible to reach those 3 targets at once: 1. Reduce the carbon footprint and improve effluents quality by reducing - the COD discharge by 30-40 %, - the AOX load by 50-65 %, - effluents colour by 65 %. 2. Get pulp with similar or better strength properties, low refining requirements, very high brightness and less brightness reversion. 3. Lower bleaching chemical costs by 20-30 % while investing with a ROI of 1.5-4 years. 17
Sustainable development is your ambition Green Bleaching is our solution! Fibria Jacarei, Brazil ca. 40 Minuten Thank you for your attention. 18