WO1995012549A1 - Method of purifying waste water - Google Patents

Method of purifying waste water Download PDF

Info

Publication number
WO1995012549A1
WO1995012549A1 PCT/SE1994/000990 SE9400990W WO9512549A1 WO 1995012549 A1 WO1995012549 A1 WO 1995012549A1 SE 9400990 W SE9400990 W SE 9400990W WO 9512549 A1 WO9512549 A1 WO 9512549A1
Authority
WO
WIPO (PCT)
Prior art keywords
steam
waste water
evaporator
condensate
converter
Prior art date
Application number
PCT/SE1994/000990
Other languages
French (fr)
Inventor
Christer Säfström
Göran Lundgren
Original Assignee
Sunds Defibrator Industries Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sunds Defibrator Industries Ab filed Critical Sunds Defibrator Industries Ab
Priority to AU10368/95A priority Critical patent/AU678081B2/en
Priority to EP95900961A priority patent/EP0726879A1/en
Priority to JP7513160A priority patent/JPH09504473A/en
Publication of WO1995012549A1 publication Critical patent/WO1995012549A1/en
Priority to FI961883A priority patent/FI961883A0/en

Links

Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/66—Pulp catching, de-watering, or recovering; Re-use of pulp-water
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0033—Other features
    • B01D5/0054—General arrangements, e.g. flow sheets
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • C02F1/10—Treatment of water, waste water, or sewage by heating by distillation or evaporation by direct contact with a particulate solid or with a fluid, as a heat transfer medium

Definitions

  • This invention relates to a method of purifying and recovering waste water from a fiberboard manufacturing process.
  • the starting material is lignocellulose-containing fiber material, for example wood chips which are washed, defibered, dried, glued, formed to a fiber mat and pressed in a hot press.
  • waste water is produced, which was separated from the fiber material, for example at chip washing, dewatering screw, gas scrubber a.o.
  • This waste water contains im ⁇ purities in the form of fiber fragments and other organic matter.
  • an evaporator For purifying waste water, an evaporator can be used which con ⁇ centrates the impurities by evaporation of the waste water. The im ⁇ purities can thereafter be separated mechanically from the eva ⁇ porator. The waste water thus purified partially could be re-used in the process, while a large proportion was emitted. The requirements on the purity of waste water have become increasingly severe and, therefore, the purification costs have increased and thereby have deteriorated the profitability of the entire fiberboard manuf ⁇ acturing process.
  • the present invention offers a solution of the aforesaid problem by using the contaminated waste water after purification for steam generation.
  • Contaminated waste water from chip washing, press water from the feed screw to the defibering process and scrubber water from the fiber drier is fed through a supply line 10 to an evaporator 11.
  • This eve- porator is designed as a heat exchanger where heating medium in the form of steam of high pressure is directed in a counterflow.
  • the steam used as heating medium is generated in a steam generator 12 and can have a pressure of 12-25 bar, suitably about 16 bar.
  • the waste water is evaporated and at the same time the heating steam is condensed whereby the impurities are con ⁇ centrated and mechanically separated.
  • These impurities are dis ⁇ charged from the evaporator 11 through an outlet 13 in the form of a thickened sludge, the dry matter content of which is sufficient for yielding a positive heat value, which makes its combustion, for example in a roasting boiler, possible.
  • the waste water evaporated in the evaporator 11 is directed to a steam converter 14, which is designed as a heat exchanger where the evaporated waste water in a counterflow heats the condensate from the evaporator 11, so that it is restored to steam at the same time as the evaporated waste water is condensed.
  • This condensed waste water which still contains water-soluble impurities, is directed to a purification unit 15 where these solved substances are separated, for example by inverted osmosis.
  • the waste water is purified by this treatment to such a quality, that it can be used as feed water in the steam generator 12.
  • the steam generated in the steam converter 14 is discharged through a line 16 for being used as consumption steam in the fiberboard manufacturing process.
  • the steam pressure is slightly lower than the steam pressure from the steam generator 12.
  • the outgoing steam pressure thus, can be 10-20 bar.
  • the steam pressure after the steam converter can be about 12 bar.
  • Part of the steam generated in the steam generator 12 is returned via a passageway 17 with a reducing valve 18 directly to the process, together with the steam in the line 16 generated in the steam converter 14.
  • the evaporator 11 as well as the steam converter 14 preferably are designed so that in operation contaminated heating surfaces are continuously cleaned mechanically.
  • waste water amounts obtained in the process which is supplied through the line 10 normally is of the same magnitude as the demand of feed water for generating steam in the steam generator 12.
  • the supplied amount of waste water substantially corresponds to the demand of feed water for generating consumption steam, in the entire system for purifying and recovering waste water balance is obtained.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Water Supply & Treatment (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Heat Treatment Of Water, Waste Water Or Sewage (AREA)
  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
  • Water Treatment By Electricity Or Magnetism (AREA)

Abstract

A method of purifying and recovering waste water from a fiberboard manufacturing process. The waste water is supplied to an evaporator (11), in which steam from a steam generator (12) is used as heating medium for evaporating the waste water and concentrating impurities. These impurities are thereafter separated mechanically from the evaporator (11). The steam generated in the evaporator (11) is used in a steam converter (14) for restoring the heating medium used in the evaporator (11) from condensate to steam phase. The condensate formed in the steam converter (14) is purified from solved substances in a purifying unit (15). The condensate thus purified is used as feed water in the steam generator (12), from which steam is supplied to the evaporator (11).

Description

Method of purifying waste water
This invention relates to a method of purifying and recovering waste water from a fiberboard manufacturing process.
At the manufacture of fiberboard according to the dry method, for example MDF (Medium Density Fiberboard) , the starting material is lignocellulose-containing fiber material, for example wood chips which are washed, defibered, dried, glued, formed to a fiber mat and pressed in a hot press.
At this process a large amount of waste water is produced, which was separated from the fiber material, for example at chip washing, dewatering screw, gas scrubber a.o. This waste water contains im¬ purities in the form of fiber fragments and other organic matter.
For purifying waste water, an evaporator can be used which con¬ centrates the impurities by evaporation of the waste water. The im¬ purities can thereafter be separated mechanically from the eva¬ porator. The waste water thus purified partially could be re-used in the process, while a large proportion was emitted. The requirements on the purity of waste water have become increasingly severe and, therefore, the purification costs have increased and thereby have deteriorated the profitability of the entire fiberboard manuf¬ acturing process.
The present invention offers a solution of the aforesaid problem by using the contaminated waste water after purification for steam generation.
The characterizing features of the invention are apparent from the attached claims:
The invention is described in greater detail in the following, with reference to the accompanying Figure, which by way of a flow chart illustrates an embodiment of the method according to the invention. Contaminated waste water from chip washing, press water from the feed screw to the defibering process and scrubber water from the fiber drier is fed through a supply line 10 to an evaporator 11. This eve- porator is designed as a heat exchanger where heating medium in the form of steam of high pressure is directed in a counterflow. The steam used as heating medium is generated in a steam generator 12 and can have a pressure of 12-25 bar, suitably about 16 bar.
In the evaporator 11 the waste water is evaporated and at the same time the heating steam is condensed whereby the impurities are con¬ centrated and mechanically separated. These impurities are dis¬ charged from the evaporator 11 through an outlet 13 in the form of a thickened sludge, the dry matter content of which is sufficient for yielding a positive heat value, which makes its combustion, for example in a roasting boiler, possible.
The waste water evaporated in the evaporator 11 is directed to a steam converter 14, which is designed as a heat exchanger where the evaporated waste water in a counterflow heats the condensate from the evaporator 11, so that it is restored to steam at the same time as the evaporated waste water is condensed. This condensed waste water, which still contains water-soluble impurities, is directed to a purification unit 15 where these solved substances are separated, for example by inverted osmosis. The waste water is purified by this treatment to such a quality, that it can be used as feed water in the steam generator 12.
The steam generated in the steam converter 14 is discharged through a line 16 for being used as consumption steam in the fiberboard manufacturing process. The steam pressure is slightly lower than the steam pressure from the steam generator 12. The outgoing steam pressure, thus, can be 10-20 bar. At a steam pressure of about 16 bar after the steam generator 12, the steam pressure after the steam converter can be about 12 bar. Part of the steam generated in the steam generator 12 is returned via a passageway 17 with a reducing valve 18 directly to the process, together with the steam in the line 16 generated in the steam converter 14.
The evaporator 11 as well as the steam converter 14 preferably are designed so that in operation contaminated heating surfaces are continuously cleaned mechanically.
The waste water amounts obtained in the process which is supplied through the line 10, normally is of the same magnitude as the demand of feed water for generating steam in the steam generator 12. When the supplied amount of waste water substantially corresponds to the demand of feed water for generating consumption steam, in the entire system for purifying and recovering waste water balance is obtained.
The invention, of course, is not rot restricted to the embodiment described and shown, but can be varied within the scope of the invention idea.

Claims

Claims
1. A method of purifying and recovering waste water from a fiber- board manufacturing process, where the waste water is supplied to an evaporator (11), in which steam from a steam generator (12) is used as heating medium for evaporating the waste water and concentrating impurities, which thereafter are separated mechanically from the evaporator (11) . c h a r a c t e r i z e d i n that the steam generated in the evaporator (11) is used in a steam converter (14) for restoring the heating medium used in the evaporator (11) from condensate to steam phase, that the condensate formed in the steam converter (14) is purified in a purification unit (15) from solved substances, whereafter the condensate thus purified is used as feed water in the steam generator (12) , from which steam is supplied to the evaporator (11) .
2. A method as defined in claim 1, c a r a c t e r i z e d i n that the condensate restored in the steam converter (14) to steam phase is used as consumption steam in the process.
3. A method as defined in claim 1 or 2, c h a r a c t e r i z e d i n that part of the steam generated in the steam generator (12) is used directly as consumption steam in the process.
4. A method as defined in any one of the preceding claims, c h a r a c t e r i z e d i n that the supplied amount of waste water substantially corresponds to the demand of feed water for generating consumption steam in the process.
PCT/SE1994/000990 1993-11-05 1994-10-20 Method of purifying waste water WO1995012549A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
AU10368/95A AU678081B2 (en) 1993-11-05 1994-10-20 Method of purifying waste water
EP95900961A EP0726879A1 (en) 1993-11-05 1994-10-20 Method of purifying waste water
JP7513160A JPH09504473A (en) 1993-11-05 1994-10-20 Wastewater purification method
FI961883A FI961883A0 (en) 1993-11-05 1996-05-03 Wastewater treatment method

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9303645-7 1993-11-05
SE9303645A SE502916C2 (en) 1993-11-05 1993-11-05 Ways to purify and recycle wastewater from a fiberboard production process

Publications (1)

Publication Number Publication Date
WO1995012549A1 true WO1995012549A1 (en) 1995-05-11

Family

ID=20391643

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1994/000990 WO1995012549A1 (en) 1993-11-05 1994-10-20 Method of purifying waste water

Country Status (7)

Country Link
EP (1) EP0726879A1 (en)
JP (1) JPH09504473A (en)
AU (1) AU678081B2 (en)
CA (1) CA2171838A1 (en)
FI (1) FI961883A0 (en)
SE (1) SE502916C2 (en)
WO (1) WO1995012549A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000035588A1 (en) * 1998-12-17 2000-06-22 Metso Paper, Inc. Method and production plant for the manufacture of fibrous material
CN101851041A (en) * 2010-04-27 2010-10-06 中国海诚工程科技股份有限公司 Method and device for realizing zero release in desulfuration wastewater deepening treatment

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111701265A (en) * 2020-06-28 2020-09-25 宜宾丝丽雅股份有限公司 Evaporation system and method for acid bath treatment

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3242970A (en) * 1963-03-06 1966-03-29 Buckau Wolf Maschf R Multiple-effect vertical-tube evaporator
US4379734A (en) * 1980-04-29 1983-04-12 Fa. Maschinenfabrik Buckau R. Wolf Ag Multistage evaporator
WO1990013342A1 (en) * 1989-05-10 1990-11-15 Inventio Oy Method of evaporating warm liquid
WO1993016004A1 (en) * 1992-02-10 1993-08-19 Adolf Schiestl Thermal method for cleaning waste water

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3242970A (en) * 1963-03-06 1966-03-29 Buckau Wolf Maschf R Multiple-effect vertical-tube evaporator
US4379734A (en) * 1980-04-29 1983-04-12 Fa. Maschinenfabrik Buckau R. Wolf Ag Multistage evaporator
WO1990013342A1 (en) * 1989-05-10 1990-11-15 Inventio Oy Method of evaporating warm liquid
WO1993016004A1 (en) * 1992-02-10 1993-08-19 Adolf Schiestl Thermal method for cleaning waste water

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000035588A1 (en) * 1998-12-17 2000-06-22 Metso Paper, Inc. Method and production plant for the manufacture of fibrous material
CN101851041A (en) * 2010-04-27 2010-10-06 中国海诚工程科技股份有限公司 Method and device for realizing zero release in desulfuration wastewater deepening treatment
CN101851041B (en) * 2010-04-27 2012-02-08 中国海诚工程科技股份有限公司 Method and device for realizing zero release in desulfuration wastewater deepening treatment

Also Published As

Publication number Publication date
SE9303645D0 (en) 1993-11-05
AU678081B2 (en) 1997-05-15
EP0726879A1 (en) 1996-08-21
FI961883A (en) 1996-05-03
JPH09504473A (en) 1997-05-06
AU1036895A (en) 1995-05-23
SE502916C2 (en) 1996-02-19
CA2171838A1 (en) 1995-05-11
FI961883A0 (en) 1996-05-03
SE9303645L (en) 1995-05-06

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