PAPERMAKING PROCESSES AND RELATED TECHNIQUES

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PAPERMAKING PROCESSES AND RELATED TECHNIQUES

• Group 3
• Pablo Izquierdo Devesa
• Alba López Díaz
• Estefanía Marcos Puertas

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APPLIED PROCESSES AND TECHNIQUES
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Stock Preparation

• Raw stock? Finished stock
• blending of different pulps
• dilution
• addition of chemicals
• Fibres received dry ? suspended in a pulper
  (pumped)
• Undissolved impurities
• removed by screening (screens)
• cleaning (centrifugal cleaners).

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Paper Machine

• De-watering device
• head box
• wire section
• press section
• dryer section steam heated cylinders
• Fourdrinier process
• The fibre suspension (dyes and other chemicals)
  from the headbox ?Continuous fabric.
• Two wires (same speed) drained (one/both sides)

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Water circuits and fibre recovery

• Primary circuit
• (short circulation)
• Secondary circuit
• (long circulation)
• Tertiary circuit
• (excess water)

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Broke system

• Wet broke ? normal operation at the wire section.
• Dry broke ?finishing operations.

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Sizing, coating, dyeing and addition of chemicals

• Sizing?Starch or synthetic sizing agents
• Coating?smooth surface
• Dyeing? coloured papers
• Addition of chemicals
• - achieve certain paper properties (e.g. sizing
  agents)
• - improves operations in the production process
  (e.g. retention agents)

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Calendering

• smooth paper surface
• two or more chilled cast-iron rolls with very
  smooth surfaces.

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Consumption and emission levels

• Consumption of major raw material
• Fibres, water and chemical additives
• Water use
• Cleaning water, solvent, cooling
• Use of additives
• Energy demand
• Wastewater emissions
• Rejects from stock cleaning
• Temporary and accidental discharges
• Cooling and sealing waters

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Consumption and emission levels

• Solid waste generation wastewater
• Rejects from stock preparation
• Sludge from water treatment
• Atmospheric emissions
• - Air emissions from paper machines
• - Air emission from energy generation
• - Odour from vapours and from wastewater
  treatment
• Noise from paper machines (local)

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Techniques to consider in the determination of BAT
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Techniques to consider in the determination of
BAT

• The main technical options for environmental
  protection and energy saving.

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Techniques to consider in the determination of BAT

• 1.- Water management and minimising the use of
  water for different paper grades
• Efficient separation of cooling waters from
  process water.
• The shower water system is usually the biggest
  consumer of fresh water most of the fresh water
  must be replaced by clarified white water.
• Recycling part of the vacuum pump sealing water.
• Design and maintenance of piping and storage
  chests.

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Techniques to consider in the determination of BAT

• 2.- Internal treatment of white water by use of
  membrane filtration and recycling of treated
  process water
• Micro-filtration
• Ultra-filtration
• Nano-filtration (NF) or reverse osmosis (RO)

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Techniques to consider in the determination of BAT

• 3.- Reduction of fibre and filler losses
• Tuning of the pulp refining
• Efficient control of paper machine
• Sufficient use of paper chemicals to reach
  improved fibre retention in order to get a good
  paper web formation.

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Techniques to consider in the determination of BAT

• 4.-Recovery and recycling of coating-colour-contai
  ning effluent
• The pigments are expensive, so the recovery of a
  part of the coating colour for reapplication and
  minimisation is cost-effective
• One method is ultra-filtration water and
  chemicals are separated from each other by using
  a semi-permeable membrane.

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Techniques to consider in the determination of BAT
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Techniques to consider in the determination of BAT

• 5.- Energy savings through energy efficient
  technologies
• There are opportunities for energy saving in
  many stages of the process.
• Example Energy savings through heat recovery
  systems
• The purpose to lower the mill' s consumption of
  primary energy by using waste energy from the
  process

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Techniques to consider in the determination of BAT

• Air-to-water heat exchangers heating of
  circulation water and process water respectively.

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Techniques to consider in the determination of BAT
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Techniques to consider in the determination of BAT

• Other techniques are
• Water management and minimising water usage for
  different paper grades
• Control of potential disadvantage of closing up
  the water systems
• Separate Pre-treatment of Coating Wastewaters
• Measures to reduce the frequency and effects of
  accidental discharges
• Measurement and automation
• Installation of an equalisation basin and
  primary treatment of wastewater
• Secondary or Biological Treatment - Aerobic
  Methods
• Chemical precipitation of wastewater from paper
  mills
• Substitution of potentially harmful substances by
  use of less harmful alternatives
• Pre-treatment of sludge (de-watering) before
  final disposal or incineration
• Options for waste treatment.
• Installation of low NOx technology in auxiliary
  boilers (oil, gas, coal)
• Use of combined heat and power generation
• Optimisation of de-watering in the press section
  of the paper machine
• Measures for noise reduction

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BEST AVAILABLE TECHNIQUES
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Best Available Techniques

• GENERAL MEASURES
• Training, education and motivation of staff and
  operators.
• Process control optimisation.
• Sufficient maintenance has to be ensured.
• Environmental management system which clearly
  defines the responsibilities for environmentally
  relevant aspects.

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Best Available Techniques

• MEASURES FOR REDUCING EMISSIONS TO WATER
• Minimising water usage for different paper grades
  by increased recycling of process waters and
  water management.
• Control of potential disadvantages of closing up
  the water systems.
• Construction of a balanced white water, filtrate
  and broke storage system and use of
  constructions, design and machinery with reduced
  water consumption when practicable.
• Measures to reduce frequency and effects of
  accidental discharge.

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Best Available Techniques

• MEASURES FOR REDUCING EMISSIONS TO WATER
• Collection and reuse of clean cooling and sealing
  waters or separate discharge.
• Separate pre-treatment of coating wastewaters.
• Substitution of potentially harmful substances by
  use of less harmful alternatives.
• Effluent treatment of wastewater by installation
  of an equalisation basin and primary treatment.
• Secondary or biological treatment of wastewater,
  and/or in some cases, secondary chemical
  precipitation or flocculation of wastewater.

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Best Available Techniques

• MEASURES FOR REDUCING EMISSIONS TO AIR
• Installation of low NOx technology in auxiliary
  boilers.
• Reducing SO2 emissions from steam boilers by
  using low sulphur oil and coal or controlling S
  emissions.
• Use of combined heat and power generation.
• Using renewable sources like wood or wood waste
  to reduce the emissions of fossil CO2 (only
  applicable if papermaking is integrated with
  virgin pulp production).

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Best Available Techniques

• MEASURES FOR REDUCING EMISSIONS TO AIR
• - Where a natural gas supply is accessible and
  where economic conditions permit the use of
  natural gas, it is considered to represent BAT.
• - Where fuel oil is used then a sulphur content
  of 1 or less is considered to represent BAT.

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Best Available Techniques

• MEASURES FOR REDUCING SOLID WASTE
• Minimizing the generation of solid waste and
  recovery, re-use and re-cycling of materials
  as far as possible.
• Separate collection of waste fractions at source
  and, if necessary, intermediate storage of
  residuals/waste.
• Reduction of fibre and filler losses.
• Recovery and recycling of coating wastewaters.
• Pre-treatment of sludge (de-watering) before
  further utilisation or final disposal.
• Reduction of the amount of waste to be
  landfilled.

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Best Available Techniques

• ENERGY SAVING MEASURES
• Implementation of a system for monitoring energy
  usage and performance.
• More effective dewatering of the paper web in the
  press section of the paper machine.
• Use of energy efficient technologies.
• Reduction of direct use of steam by careful
  process integration by using pinch analysis.

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Best Available Techniques

• NOISE ATTENUATION
• BAT is the reduction of noise levels audible in
  the vicinity of paper mills.
• The measures applied will depend to a large
  extent on the specific noise problem of a mill
  and the targets set. Usually they will be much
  stricter when the mill is located adjacent to a
  residential area.

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Best Available Techniques

• CHEMICAL USAGE
• Ensure the availability of a database for all
  used chemicals and additives .
• Application of the principle of substitution
  less hazardous products are used when available.
• Measures to avoid accidental discharges to soil
  and water from handling and storage of chemicals.
  Design and operation of facilities in such a way
  that dangerous substances cannot escape.

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EMERGING TECHNIQUES
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Emerging Techniques

• Minimum effluent paper mills - optimised design
  of water loops and advanced wastewater treatment
  technologies.
• Impulse technology for dewatering of paper.
• Condebelt process.
• Internal heat pumps.
• Total site integration tools.

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Emerging Techniques

• CONDEBELT PROCESS
• The Condebelt drying process is a new way to
  dry paper and board.
• Initially, the process was simply intended to
  improve drying of paper and board and it was only
  later that the big increases in strength
  properties became evident.
• In the Condebelt drying process, the paper web
  coming from the press section is dried between
  two steel belts instead of traditional steam
  cylinders.

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Emerging Techniques
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Emerging Techniques

• CONDEBELT PROCESS
• The use of this new drying technology does not
  result in significant direct energy savings.
• Main advantages
• more square meters from the same amount of fibres
  can be manufactured without loosing product
  quality.
• higher potential for energy recovery.

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Thank you for your attention!