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You are here : Home > Training > EFPG Days > 9- Existing pulping alternatives to improve yield and benefits (slides 9-17)

Last update : September 05, 2003

			Second Session : The Yield Issue
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					IX - Existing pulping alternatives to improve yield and benefits Economics of Yield Increase (slides 9-17) M. Sundar, M. Muguet, M. Epiney et G. Homer (Air Liquide)

	9 - Every Mill Manager's Goal   Optimize mill as a whole   Maximize profits/cash by:     lowering fiber cost   lowering manufacturing cost The cost structure of a 500K tons/year softwood chemical pulp mill at full production is as follows: Cost Percent Production related/variable costs 50 Time related/fixed costs 13 Capital costs 36 Data from: Economics of the pulp and paper industry, Tappi papermaking & technology series - 1				10 - Cost structure In production related/variable costs, wood accounts for 31%, OMS (Operating Materials & Services) for 11%, chemicals for 7% and energy for 1%, as shown by the following figure. Data from: Economics of the pulp and paper industry, Tappi papermaking & technology series - 1

	11 - Conventional Wisdom Incremental production is extremely profitable, and incentive is always there to improve productivity, as shown by the following diagram: Why are mills reluctant to practice new yield technologies? Data from: Alkaline pulping, Tappi pulp and paper manufacture - 5				12 - Mills reluctant to practice new yield technologies? Major challenges:       can incremental pulp be produced with existing bottlenecks in the mill   incremental pulp or save on wood Desired strategy   validate yield improvment at the mill   ROI/Payback/Profit Of course, the main challenge is fiber quality.

	13 - Back to the basic: the kraft process Let us start from basic, and have a look on the kraft process flow sheet:

	14 - Technology options in various zones of the kraft process Let us examine the various technology options in the four zones of the kraft process: Zone Stage Options 1 Tree Improvement in forestry management as a whole 2 Wood Uniform chip size and improved screening 3 Digestion   Cooking additives: surfactants, AQ, polysulfides...   Cooking process: batch, continuous, super batch, lo-solids and low temp for hardwoods, process control...   Cooking conditions: increasing kappa to go up on the cooking curve in combination with 1 or 2 O2 delig stages, avoiding kappa fluctuations...   black liquor gasification 4 Bleaching   Minimize bleach plant shrinkage

	15 - Available preferences Let us examine the various available preferences based on funds available: Option Preferences Cost Little to spend Optimize what currently exists in the mill. Example: minimize kappa variations   Operating funds Chemical additives. Example: AQ, surfactants (exception of polysulfides) < 3-4 M€ Capital funds Polysulfide, minor wood yard modifications... > 3-4 M€ Modified/improved delignification opportunities. Example: super batch, two-stage oxygen...   New risk technologies Wait & see. Example: black liquor gasification, wood genetics, cloning

	16 - Additional scenarios Additional scenarios requiring yield improvement:     production limited by recovery bloiler, or     integrated mills with pulp demanding machines, or   expensive wood cost Some low cost options are:   higher UB kappa   AQ cooking (1% yield improvement)				17 - Air Liquide vision of pulp industry ROI/Payback/Profit Validate yield improvement at the mill Polysulfide Yield model with or without combination of ozone & chlorine dioxide developed by Air Liquide

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