WO2002014599A9 - Steaming process - Google Patents
Steaming processInfo
- Publication number
- WO2002014599A9 WO2002014599A9 PCT/FI2001/000703 FI0100703W WO0214599A9 WO 2002014599 A9 WO2002014599 A9 WO 2002014599A9 FI 0100703 W FI0100703 W FI 0100703W WO 0214599 A9 WO0214599 A9 WO 0214599A9
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- fibre
- lignocellulosic material
- steam
- steaming
- chemicals
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims abstract description 30
- 238000010025 steaming Methods 0.000 title claims abstract description 27
- 230000008569 process Effects 0.000 title claims description 16
- 239000000835 fiber Substances 0.000 claims abstract description 67
- 239000000463 material Substances 0.000 claims abstract description 58
- 239000012978 lignocellulosic material Substances 0.000 claims abstract description 28
- 239000000126 substance Substances 0.000 claims abstract description 28
- 238000004537 pulping Methods 0.000 claims abstract description 11
- 238000005470 impregnation Methods 0.000 claims description 17
- 238000010411 cooking Methods 0.000 claims description 4
- 238000010521 absorption reaction Methods 0.000 abstract description 5
- 229920006395 saturated elastomer Polymers 0.000 description 10
- 239000011148 porous material Substances 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 6
- 230000035515 penetration Effects 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 229920005610 lignin Polymers 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 238000009833 condensation Methods 0.000 description 3
- 230000005494 condensation Effects 0.000 description 3
- 230000001627 detrimental effect Effects 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 239000002023 wood Substances 0.000 description 3
- 238000004061 bleaching Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 241000609240 Ambelania acida Species 0.000 description 1
- 239000002028 Biomass Substances 0.000 description 1
- 244000025254 Cannabis sativa Species 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- 229920001131 Pulp (paper) Polymers 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000010905 bagasse Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006482 condensation reaction Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000010902 straw Substances 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical compound [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 description 1
- 229910021653 sulphate ion Inorganic materials 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
- D21B1/00—Fibrous raw materials or their mechanical treatment
- D21B1/02—Pretreatment of the raw materials by chemical or physical means
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C1/00—Pretreatment of the finely-divided materials before digesting
- D21C1/02—Pretreatment of the finely-divided materials before digesting with water or steam
Definitions
- the present invention relates to a method of steaming lignocellulosic material to change the structure of the material and/or to impregnate the lignocellulosic material to be pulped with delignifying chemicals.
- lignocellulosic material is steamed before it is impregnated with a delignifying chemical solution.
- Lignocellulosic material means in this connection all material of plant origin used as raw material in a chemical pulp cook, such as wood, straw, grass, bagasse, etc.
- the lignocellulosic material used in the method is, when needed, in a form cut in a conventional manner for delignification, for example, wood material as chips or sawdust.
- pulping refers to the pulping of lignocellulosic material, which includes some degree of delignification of the lignocellulosic material which takes place by means of chemicals and heat.
- the delignification accomplished with chemicals and heat may be supplemented with mechanical defibring to achieve the desired degree of defibring.
- the treatment of lignocellulosic material in a superheated steam atmosphere included in the invention can also be applied to the loosening up of the structure of lignocellulosic material for mechanical pulping.
- a similar procedure has been used in state-of-the-art applications, for example, in the so-called TMP process, but under saturated steam treatment conditions. If, on the other hand, steaming is carried out by using superheated steam, there arises in the fibre material a situation in which the moisture within it tends to vaporise and force its way out of the fibre because of the drying effect produced by the superheated steaming conditions.
- the lignin contained in the fibre softens and, at the same time, the internal structure of the fibre opens and loosens up, which in itself is helpful to the subsequent mechanical pulping stage.
- the treatment within the fibre (if it has not been overdried) there prevails a situation where there is steam in a saturated state within the fibre. If the fibre in this state is brought under conditions in which steam is condensed, and in addition relatively quickly, this gives rise to a collapse phenomenon in the fibre structure, which further loosens up the structure. This assists defibring to a substantial extent in subsequent mechanical pulping. The defibring process requires less energy, and harmful breakages are reduced.
- delignifying chemicals are meant in this connection all chemicals commonly used for the purpose in question, which chemicals are absorbed into lignocellulosic material and which dissolve or soften the lignin contained in the material and by which delignification is accomplished at a temperature higher than ambient temperature.
- sulphate and sulphite pulp cooking liquors may be mentioned.
- the reactions of the lignin contained in fibre material with dissolving and/or softening chemicals take place in the desired manner only if the chemicals have penetrated uniformly and thoroughly into the material which is being pulped.
- the absorption of chemicals is influenced by two mechanisms, penetration and diffusion.
- cooking chemical liquor penetrates into fibre material through its capillary structure by the action of capillary forces.
- the penetration process may be assisted by providing a pressure difference across the capillary structure.
- the speed and thorough accomplishment of the penetration process is greatly dependent on the air which is contained in fibre material and which should be removed before treating the material with delignifying chemicals.
- One method used is the deaeration of fibre material by steaming. During steaming, the air contained in fibre material expands through heating, and partly escapes from the pore spaces of fibre material. The steam used in the treatment penetrates, in turn, into the pore spaces of fibre material where it contributes to the exit of air from the pores of fibre material through condensation and vaporisation processes.
- Prior art steaming processes have used saturated steam.
- the upper limit of the temperature of steam has been considered to be 120 - 126 °C and, at temperatures higher than this, the hydrolysis of fibre materials has been considered to accelerate to a detrimental extent.
- the condensation of lignin at higher temperatures has also been considered to be a problem.
- steaming of Hgnocellulose based fibre material is carried out in a steam atmosphere under superheated conditions, and the lignocellulosic material is maintained substantially at the steaming pressure up to at least an impregnation stage.
- the steaming is advantageously accomplished by passing superheated steam into contact with the fibre material.
- other means of introducing energy such as indirect heating or an inert energy carrier (such as fluidised bed material), are feasible enabling a steam atmosphere under superheated conditions to be maintained during steaming.
- the inlet and the final temperatures of steam are determined according to the material of the fibre material being processed.
- the temperature of incoming steam has varied in a range of from 270 °C to 350 °C and the temperature of exiting steam has been determined according to saturated steam pressure corresponding to operating pressure (max. 23 bar(abs)) such that its superheating has been by about 15 °C - 25 °C higher than the saturated state.
- Superheated steam has a strong effect on the fibre material to be treated. Firstly, superheated steam binds into itself water from the fibre material and, secondly, causes an increase in the temperature of the fibre material. The water present in the fibre material vaporises, passes to the surface of the material and exits with superheated steam out of connection with the fibre material. At the same time, vaporising water drives the air present in the fibre structure out of the fibre. An essential factor is also that the vaporising water most evidently opens the capillary and pore structure of the fibre.
- the fibre is maintained under conditions where this open space of capillaries and pores is preserved as far as possible into the absorption process of delignifying chemicals.
- the residual moisture of fibre material and the ambient atmosphere are crucial.
- Said arrangement has been found to allow rapid absorption of delignifying solutions uniformly through the entire fibre material.
- the arrangement also makes it possible that the impregnated fibre material is substantially at delignification temperature after impregnation. The detrimental reactions of fibre raw material and delignifying chemicals associated with slow absorption and with slow heating to delignification temperature can thus be eliminated.
- the contact time between the material and steam is substantially short, of course, depending on the particle size of the material.
- an appropriate dwell time is of the order of seconds.
- the steaming stage of the invention can be accomplished in a processing apparatus of the so-called flash type in which fine lignocellulosic material is supplied to be carried with a superheated steam flow, and is separated from this flow after an appropriate dwell time.
- the apparatus is illustrated in the accompanying drawing, in which Figure 1 shows one embodiment of the steaming and impregnation apparatus in accordance with the invention, and
- Figure 2 shows an apparatus used for a similar purpose, as an alternative embodiment in respect of the impregnation apparatus.
- the steaming apparatus comprises a steam flow circulation 1 which includes a fan 3 maintaining the circulation, a superheating device 2 (boiler), a steaming stage 4 situated after the superheating device and having at its lower end feed devices 5 for feeding lignocellulosic material, a steam separator 6, excess steam exhaust 7, as well as a seal type feeder 8 for lignocellulosic material.
- the apparatus also includes a return circulation 10 for steamed lignocellulosic material.
- the steamed lignocellulosic material is shown to be fed through the seal type feeder 8 into an impregnation device 11, into which a solution containing delignifying chemicals is fed from a tank 9.
- the impregnation device may have a structure nown in the art. Inside it there is usually a screw feeder with a gentle pitch, which conveys Hgnocellulose containing fibre material through the impregnation device along an obliquely upwards rising path.
- the delignifying solution is usually maintained at a level that extends to about half the length of the impregnation device. Impregnation takes place in the lower part of the device and discharge of excess solution takes place in the upper part by draining. The excess solution can be passed into the solution tank 9, possibly monitored in respect of the chemical content.
- a seal type feeder 12 by means of which an independently adjustable pressure can be maintained in the impregnation device 11.
- the lignocellulosic fibre material is fed from the seal type feeder 12 to a delignification vessel 13 proper, in which delignification reactions are performed to the desired delignification degree.
- a suitable pressure and a corresponding temperature of saturated steam are maintained at which delignification reactions have been found to occur most advantageously from the point of view of fibre material.
- Temperature can be maintained, for example, in a known manner by means of a liquid circulation provided with heating 15.
- the impregnation after steaming can be alternatively accomplished by operating as shown in Fig. 2.
- a press can serve as the seal type feeder 8.
- a solution containing delignifying chemicals can be fed into the fibre material in connection with the press and excess solution can be squeezed out in the press.
- the impregnated fibre material is passed to the delignification vessel 13, in which the fibre material is/is maintained at delignification temperature in the ambient steam phase.
- the temperature is maintained by passing direct steam into the vessel from a conduit 16.
- the temperature can be maintained by indirect heat transfer by means of steam passed from the conduit 16. This apparatus arrangement allows the liquid volume of the process to be minimised.
- the fibre material is passed from the delignification vessel 13 through a seal type feeder 14 to possible mechanical defibring, and further to conventional washing and bleaching stages.
- Figs. 1 and 2 make it possible to use different conditions in different process stages. From the point of view of the total flow of the process it is advantageous that the fibre material is maintained throughout the entire process substantially at a pressure that corresponds to the pressure of the saturated steam of the temperature used in the delignification stage. As a variant of this operation model, it is also possible to operate so that the pressure drops slightly during transition from steaming to impregnation and further during transition from impregnation to the delignification stage. Also other alternatives of pressure and corresponding temperature conditions are feasible when carrying out the invention taking into account the fibre material (the source of material as such, the particle size, moisture content), the chemicals used and the desired delignification degree.
- the fibre material the source of material as such, the particle size, moisture content
- the moisture escaping from the lignocellulosic material which is in contact with superheated steam in the steaming stage 4 is carried with steam into the separator device 6, from which excess circulation steam is discharged through the conduit 7.
- the energy level of this steam is high, and it can be utilised in later stages of the pulping process, for example, in heating delignifying chemicals, in regeneration stages of the chemicals circulation, in bleaching, in washing, etc.
- Control of the exhaust steam 7 can also be used for regulating the heating stage 2 of the superheating circulation so that there should prevail an inert gas state in the circulation 1.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Paper (AREA)
- Dry Formation Of Fiberboard And The Like (AREA)
- Chemical And Physical Treatments For Wood And The Like (AREA)
- Manufacture, Treatment Of Glass Fibers (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
- Medicines That Contain Protein Lipid Enzymes And Other Medicines (AREA)
- Meat, Egg Or Seafood Products (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2001282184A AU2001282184A1 (en) | 2000-08-14 | 2001-08-09 | Steaming process |
DE60137856T DE60137856D1 (en) | 2000-08-14 | 2001-08-09 | LOSS METHOD |
EP01960785A EP1320640B1 (en) | 2000-08-14 | 2001-08-09 | Steaming process |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI20001787 | 2000-08-14 | ||
FI20001787A FI117560B (en) | 2000-08-14 | 2000-08-14 | Steaming |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2002014599A1 WO2002014599A1 (en) | 2002-02-21 |
WO2002014599A9 true WO2002014599A9 (en) | 2003-06-19 |
Family
ID=8558881
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/FI2001/000703 WO2002014599A1 (en) | 2000-08-14 | 2001-08-09 | Steaming process |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP1320640B1 (en) |
AT (1) | ATE424474T1 (en) |
AU (1) | AU2001282184A1 (en) |
DE (1) | DE60137856D1 (en) |
FI (1) | FI117560B (en) |
WO (1) | WO2002014599A1 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
AU2006202424A1 (en) * | 2006-06-07 | 2008-01-03 | Kristevefourspace Ussy Pty Ltd | Manufacture of Bagasse Powder |
DE102017222748B3 (en) | 2017-12-14 | 2019-05-29 | Hope Tree International Gmbh | PROCESS FOR FIBER CLOSURE OF BAOBAB FIBERS |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3619348A (en) | 1969-09-05 | 1971-11-09 | Defibrator Ab | Process for continuous cellulose cooking |
SE340036B (en) * | 1970-08-31 | 1971-11-01 | Karlstad Mekaniska Ab | |
SE7317565L (en) * | 1973-12-28 | 1975-06-30 | Selander Stig Daniel | |
SE420224B (en) * | 1979-08-17 | 1981-09-21 | Sunds Defibrator | Process and device for heating fibrous materials in the preparation of pulp obtained by defibrating wood chips |
-
2000
- 2000-08-14 FI FI20001787A patent/FI117560B/en not_active IP Right Cessation
-
2001
- 2001-08-09 DE DE60137856T patent/DE60137856D1/en not_active Expired - Fee Related
- 2001-08-09 AU AU2001282184A patent/AU2001282184A1/en not_active Abandoned
- 2001-08-09 EP EP01960785A patent/EP1320640B1/en not_active Expired - Lifetime
- 2001-08-09 WO PCT/FI2001/000703 patent/WO2002014599A1/en active Application Filing
- 2001-08-09 AT AT01960785T patent/ATE424474T1/en not_active IP Right Cessation
Also Published As
Publication number | Publication date |
---|---|
WO2002014599A1 (en) | 2002-02-21 |
DE60137856D1 (en) | 2009-04-16 |
EP1320640B1 (en) | 2009-03-04 |
AU2001282184A1 (en) | 2002-02-25 |
FI117560B (en) | 2006-11-30 |
EP1320640A1 (en) | 2003-06-25 |
FI20001787A0 (en) | 2000-08-14 |
ATE424474T1 (en) | 2009-03-15 |
FI20001787L (en) | 2002-02-15 |
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