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PAPERMAKING PROCESSES AND RELATED TECHNIQUES

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Sizing, coating, dyeing and addition of chemicals. Sizing Starch or synthetic sizing agents ... Dyeing coloured papers. Addition of chemicals: ... – PowerPoint PPT presentation

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Title: PAPERMAKING PROCESSES AND RELATED TECHNIQUES


1
PAPERMAKING PROCESSES AND RELATED TECHNIQUES
  • Group 3
  • Pablo Izquierdo Devesa
  • Alba López Díaz
  • Estefanía Marcos Puertas

2
APPLIED PROCESSES AND TECHNIQUES
3
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).

4
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)

5
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6
Water circuits and fibre recovery
  • Primary circuit
  • (short circulation)
  • Secondary circuit
  • (long circulation)
  • Tertiary circuit
  • (excess water)

7
Broke system
  • Wet broke ? normal operation at the wire section.
  • Dry broke ?finishing operations.

8
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)

9
Calendering
  • smooth paper surface
  • two or more chilled cast-iron rolls with very
    smooth surfaces.

10
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

11
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)

12
Techniques to consider in the determination of BAT
13
Techniques to consider in the determination of
BAT
  • The main technical options for environmental
    protection and energy saving.

14
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.

15
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)

16
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.

17
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.

18
Techniques to consider in the determination of BAT
19
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

20
Techniques to consider in the determination of BAT
  • Air-to-water heat exchangers heating of
    circulation water and process water respectively.

21
Techniques to consider in the determination of BAT
22
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

23
BEST AVAILABLE TECHNIQUES
24
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.

25
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.

26
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.

27
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).

28
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.

29
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.

30
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.

31
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.

32
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.

33
EMERGING TECHNIQUES
34
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.

35
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.

36
Emerging Techniques
37
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.

38
Thank you for your attention!
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