FAIR-CT96-1360 Separation Methods for Closed-Loop Technology in Bleached Kraft Pulp Manufacture

Contacts
Further Information



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FAIR Area 1.3 - Forestry-Wood Chain : Paper/Pulp : Process Engineering : Pulping : Separation/Fractionation

	Type of Project	Shared Cost
	Contract No	FAIR-CT96-1360
	Total Cost	2 011 900 ECU
	EC Contribution	950 000 ECU
	Start Date	01/12/1996
	Duration	36 months

Separation methods for closed-loop technology in bleached kraft pulp manufacture

Objectives

Technical Approach

Striving towards closed-loop technology in bleached kraft pulp manufacture involves many in-process measures along the production line. Recent publications, our own and other's show that some critical technical problems exists. The most important is the need for "kidneys", e.g. the need for separation methods for organic and inorganic substances in order to operate the process without negative impact on the process or the product. This project will strengthen the scientific and technological base needed to develop and use separation methods, "kidneys". The overall objective is to use separation methods to find solutions to some of the earlier identified critical technical problems in closed-loop production. This means methods for cleaning and reuse of condensates from black liquor evaporation, handling of acid, neutral and alkaline bleach plant filtrates.

Expected Results

I. Direct Results

Identify possible solutions to earlier identified critical technical problems in closed-loop production of bleached kraft pulp by:

• cleaning condensates from the black liquor evaporation to a purity level where it can be reused in the final bleaching stages without any negative effect on the product quality, e.g. odour in pulp and paper
• removing non-process elements in a crystallisation/precipitation-step which is integrated with a separate evaporation for acid and/or neutral bleach plant filtrates
• removing organic and inorganic substances, by using new mineral membranes for nanofiltration or a combination of membrane filtration and bioreactors, in order to increase the degree of closure in a final bleaching stage where hydrogen peroxide is used
• removing organic and inorganic substances, by using new mineral membranes for ultrafiltration/nanofiltration, in order to minimise negative effects from the carry-over when alkaline bleach plant filtrates is reused on the brown stock washing and in a final hydrogen peroxide stage
• using steady-state process simulation to determine the consequences for the water, chemical and in some respects also the energy balances, when the separation methods above are integrated into the process

II. Indirect Results

• strengthening the scientific and technological base needed to develop and use necessary separation methods in a closed-loop process for production of bleached kraft pulp
• a further developed technology for low energy consuming separate evaporation, giving final concentrations above the solubility level for critical compounds in the filtrates
• development of ceramic nanofiltration membranes for applications in the bleach plant
• mathematical models for the separation characteristics of the different "kidneys" developed, which can be used in simulation programs such as WinGEMS, Pulpsim, Extend, etc.

Applications

Other processes that are operating at high degree of closure, where the driving force to purge accumulated substances also is high, can use and learn from technology developed in this project. One example is the process for paper production, but it can also be extended to other industrial sectors requiring advanced separation processes. The part in this project where steady-state process simulation is used will among other things give useful information about the general principles for each "kidney" when it is integrated in a process system.

Nanofiltration pilot plant at Cellurhône (Tarascon, France).

KERASEP ceramic membranes

KERASEP nanofiltration module

Wood fibre in an ecologically balanced cycle

Contacts

Coordinator

• Mr Per TOMANI / STFI SWEDEN

EC Scientific Officer

• Ignacio SEOANE / European Commission DG Research Theme 1 Key Action 5.3 / BELGIUM

Participant

• MRS. S NIVELON / CENTRE TECHNIQUE DE L'INDUSTRIE DES PA ENVIRONMENT, ENERGY AND ANALYSIS / FRANCE
• Mr. Jacques NYS / TECH-SEP SA FRANCE
• Klaus NIEMELÄ / The Finnish Pulp and Paper Research Institute / FINLAND

Subcontractor

• DR. E KIISKILÄ / A. AHLSTROM MACHINERY CORPORATION R &D / FINLAND