EP1351993A1 - Dispositif et procede de synthese en continu du carbamate de cellulose - Google Patents

Dispositif et procede de synthese en continu du carbamate de cellulose

Info

Publication number
EP1351993A1
EP1351993A1 EP02718029A EP02718029A EP1351993A1 EP 1351993 A1 EP1351993 A1 EP 1351993A1 EP 02718029 A EP02718029 A EP 02718029A EP 02718029 A EP02718029 A EP 02718029A EP 1351993 A1 EP1351993 A1 EP 1351993A1
Authority
EP
European Patent Office
Prior art keywords
conveyor
conveying
cellulose
reaction
conveying device
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP02718029A
Other languages
German (de)
English (en)
Inventor
Joachim Seelig
Rudolf KÄMPF
Reinhard Wolf
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
LL Plant Engineering AG
Original Assignee
ZiAG Plant Engineering GmbH
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 ZiAG Plant Engineering GmbH filed Critical ZiAG Plant Engineering GmbH
Publication of EP1351993A1 publication Critical patent/EP1351993A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
    • C08B15/00—Preparation of other cellulose derivatives or modified cellulose, e.g. complexes
    • C08B15/05—Derivatives containing elements other than carbon, hydrogen, oxygen, halogens or sulfur
    • C08B15/06—Derivatives containing elements other than carbon, hydrogen, oxygen, halogens or sulfur containing nitrogen, e.g. carbamates

Definitions

  • the invention relates to a conveying device for conveying a cellulose slurry dissolved in an organic reaction carrier, in which a synthesis of cellulose carbamate takes place, and a method for the synthesis of cellulose carbamate.
  • Cellulose carbamate is currently synthesized from a cellulose slurry in stirred tank cascades in accordance with the process described in DE 42 42 437 C2 and DE 44 17 140 C2.
  • the cellulose delivered in plates is swollen and activated in a dipping press or other device in 10% to 25% sodium hydroxide solution for several hours. After this phase, the excess liquor is pressed off, compressing to a ratio of 2: 1 to 3: 1. This material then gets into a shredder and is broken up into small pieces, on which the molecular chain length is shortened either statically in a traveling grate apparatus or dynamically in a rotary tube in a decomposition process that takes several hours and takes place at elevated temperatures.
  • the cellulose is mixed with 50 ° C, aqueous urea solution in a concentration of 40% by mass.
  • the agitated, urea-containing cellulose suspension passes through a screw press, in which the excess urea solution is pressed, into a comminution and loosening apparatus, in which the preheated liquid organic reaction medium is also added.
  • This mixture passes into a first evaporator operated under excess pressure, in which part of the water and part of the organic reaction medium are evaporated off overhead, while the residual water is removed in a second evaporator operating under reduced pressure.
  • the suspension consisting of cellulose and urea in the reaction carrier passes through a heat exchanger, in which it is brought to the reaction temperature, into a cascade of stirred tanks.
  • the reaction takes place at the temperature of the boiling reaction support and at residence times in the individual vessels, which are determined on the one hand by the boiling point of the reaction support and on the other hand by the individual size of the stirred tank volume.
  • the mixture is drawn off from the last stirring vessel through an outlet line, cooled in a heat exchanger and then reaches a rotary drum pressure filter on which the reaction carrier is filtered off and returns to the reaction circuit.
  • the filter cake consisting of cellulose carbamate, excess urea and adhering reaction carrier is washed with alcohol and water in the process of DE 44 17 140 C2.
  • An additional step with suspending the filter cake and filtering is mentioned as expedient.
  • the washed, moist cellulose carbamate is removed from the rotary pressure filter and sent for drying or direct processing.
  • the carbamate is largely freed from the heat exchanger by decanting and filtering.
  • the outflowing first washing filter Rat which consists of reaction support, alcohol and part of the excess urea, is combined with the second washing filtrate and fed to an extraction column into which so much water is fed that a separation in the reaction support phase and into a urea-containing alcoholic aqueous phase takes place.
  • Low urea water originating from the bottom of an ammonia stripper is preferably fed into the extraction together with fresh water.
  • the urea-containing alcoholic aqueous phase is fed to a rectification column in which the methanol or ethanol is driven off overhead.
  • the alcohol is sent for in-process recycling.
  • the aqueous urea solution flowing off at the bottom of the rectification column returns to the circuit of the urea solution.
  • the boiling reaction medium in the reaction vessels expels the ammonia formed during the formation of carbamate from the reaction mixture and flows through the condenser together with the vapors.
  • the major part of the reaction carrier vapor is condensed there and the condensate is returned to the first reaction vessel.
  • the vapors passing through the condenser which essentially consist of ammonia, carbon dioxide and reaction carrier, are washed in a scrubber with a circulated, cooled aqueous solution.
  • the washing liquid removed from the circuit is separated in a separation vessel and the organic reaction carrier is returned directly to the process.
  • water, ammonia and residual amounts of reaction carrier vapor are stripped off overhead and sent for disposal, while the sump, which is loaded with only little urea, is used in the extraction of the washing filtrates.
  • the vapor mixture is deposited in the condenser and separated into two phases in the separation vessel.
  • the organic, light phase goes back into the reaction medium circuit, while the aqueous condensate is fed into the washing circuit around the scrubber.
  • the outlet from the evaporator consists of cellulose carbamate and urea and goes into a relaxation pot, in which it cools down strongly by evaporative cooling.
  • the water vapor is condensed and used as wash water on a filter.
  • the wet product passes onto a belt filter, in which a concentrated urea solution is drawn off in the first zone and the carbamate is washed free of urea in the subsequent countercurrent washing stages using fresh water.
  • the wash water and the concentrated urea solution are combined and go into the circulation of the urea solution.
  • the moist cellulose carbamate which is free of urea, leaves the plant and is either dried or directly dissolved for further processing.
  • the main disadvantage of the stirred kettle cascade, as used in the processes of DE 42 42 437 C2 and DE 44 17 140 C2, is that the cellulose dwell time in the stirred kettle cascade shows considerable variations. The scatter increases with the number of stages in the cascade of stirred tanks.
  • the object of the present invention is to provide a method and an apparatus with which cellulose carbamate of constant quality can be produced inexpensively without great design effort.
  • the above-mentioned object is achieved in that the conveying device is designed as a reactor system for the continuous synthesis of cellulose carbamate and with a conveying means by means of which the dissolved cellulose slurry can be conveyed continuously along a conveying path from a feeding area to a dispensing area and with a heating device by means of which the conveyor line can be heated at least in sections.
  • the above-mentioned object is achieved according to the invention in that the synthesis of cellulose carbamate takes place continuously, in that a cellulose slurry suspended in an inert organic reaction medium is first heated in a continuously conveying conveying device and during conveying in the conveying device along a conveying path to im Main reaction temperature is maintained.
  • This improvement according to the invention of the conventional stirred kettle cascades and of the process for the synthesis of cellulose carbamate leads to a constant residence time of the cellulose due to the continuously conveying conveying device. loose slurries in the conveyor so that a constant quality of the cellulose carbamate is achieved.
  • the reaction system as a conveying device, the elaborate stirred kettles and their associated peripheral devices can be dispensed with, since the synthesis of cellulose carbamate now takes place while the cellulose slurry is being conveyed.
  • the solution according to the invention is thus structurally simpler and overall less expensive than the conventional stirred tank cascades.
  • the conveyor is provided with a heating device according to the invention, so that while the dissolved cellulose slurry is conveyed along the conveyor line, the cellulose slurry is kept at the reaction temperature or at the boil and the cellulose carrbamate can be synthesized ,
  • the reaction carrier remains permanently in the conveyor. This can happen, for example, in that excess reaction carriers are derived from the conveyor device or from the conveyor section, processed again and fed back to the conveyor device.
  • This principle makes it possible to save heating energy, since the reaction carrier can always be kept at almost the same temperature and does not have to be constantly re-heated.
  • a further advantage of this principle is that only a small part of the reaction carrier remaining in the conveying device has to be discharged for processing, in particular for cleaning, since practically only intercalated cellulose is introduced and cellulose carbamate is discharged.
  • the reaction carrier heated at the beginning of the conveying section its temperature is at least in the range of the reaction temperature to which cellulose slurry is fed.
  • a particularly efficient heating is possible if, in a further advantageous embodiment, the reaction carrier fed in at the beginning of the conveyor line is blown into the conveyor line in vapor form.
  • the reaction carrier can also be slightly overheated. With this configuration, very rapid heating to the reaction temperature is possible.
  • at least one corresponding nozzle can be provided in the conveying path of the conveying device, preferably at the bottom of the conveying path.
  • the heating and evaporation of the reaction carrier can be carried out in a particularly energy-saving manner if, in a further advantageous embodiment, the reaction carrier fed in at the beginning of the conveying path was previously derived from the conveying device or from the conveying path in accordance with the principle set out above. In this case, only a slight reheating of the reaction carrier is necessary.
  • the conveying device can be rinsed with a detergent.
  • Cellulose or cellulose carbamate remaining in the conveying device or in the conveying section is to be rinsed off by the detergent.
  • the rinsing with the detergent can take place intermittently in a further embodiment.
  • Reaction carrier which has previously been derived from the conveyor, for example, can be used as the detergent.
  • the conveyor line In normal operation, the conveyor line will not be completely filled with reaction carriers and cellulose slurry, but will have an adjustable fill level.
  • the area of the conveyor line filled with suspended cellulose slurry is referred to as the reaction space.
  • cellulose slurry can be continuously rinsed from the conveyor by the rinsing agent during operation of the conveyor.
  • a so-called vapor space is formed above the reaction space, in which vapor vapor collects.
  • this vapor can be discharged from the conveying device and a vapor condenser gate be forwarded.
  • the vapor condensate generated from the vapor vapor in the vapor condenser can be mixed with reaction carrier, in particular with reaction carrier derived from the conveying device, and fed back to the method for cellulose carbamate synthesis.
  • the principle of a closed reactor and conveyor system in which the reaction carrier circulates with as little loss as possible and with only a few temperature differences, is improved in that, in a further advantageous embodiment, the cellulose slurry enters the conveyor device or the reactor system essentially without reaction carriers and - in another Design - can be removed from the conveyor essentially without reaction carriers.
  • the cellulose slurry in a delivery area of the conveying device can be removed from the conveying device by means of a discharge device in such a way that the reaction medium remains essentially in the delivery area during transport with the discharge device.
  • an overflow can be provided at one or both ends of the conveyor line.
  • the reaction carrier flowing out of the overflow can be returned to the conveyor device or the conveyor line in accordance with the above principle.
  • the conveying device can be designed as a screw conveyor and the conveying means can be essentially helical, for example as a conveying screw.
  • the conveying means can be essentially helical, for example as a conveying screw.
  • the measures on which the invention is based are not limited to screw conveyors. Instead of a screw conveyor, trough or scraper chain conveyors can also be used. On the one hand, it is important that the conveyor is closed, so that the reaction carrier can circulate with as little loss as possible.
  • Figure 1 shows a first embodiment of a conveyor device according to the invention, by which a method for the continuous synthesis of cellulose carbamate can be carried out.
  • Fig. 2 is a section along the line II-II of Fig. 1;
  • FIG. 3 shows a second exemplary embodiment of a conveyor device according to the invention, by means of which a method for the continuous synthesis of cellulose carbamate can be carried out;
  • FIG. 4 shows a section along the line IV-IV of FIG. 3rd
  • the conveyor 1 is a continuous conveyor and has a conveyor 2, which is designed as a screw in the embodiment of FIG. 1.
  • the screw 2 is driven in rotation by a motor 3 and, when rotating, conveys a cellulose slurry 4 slurried in an organic reaction carrier continuously along a conveyor path 5.
  • the conveyor section 5 extends from a feed area 6 at the beginning of the conveyor section, where the cellulose slurry is introduced into the conveyor device 1 designed as a reactor system, to a discharge area 7 at the end of the conveyor section 5, from where the cellulose slurry or the cellulose carbamate is discharged from the conveyor device 1 becomes.
  • the cellulose slurry can be supplied to the application area 6 essentially free of reaction carriers or together with reaction carriers via a feed line 8.
  • the feed area 6 is equipped with an adjustable overflow weir 9, by means of which the fill level 10 of the dissolved cellulose slurry in the conveying device 1 can be adjusted.
  • the reaction carrier 9a running over the front weir 9 enters an overflow chamber 11, from where it is discharged via a discharge line 12 from the conveying path 5 or the conveying device.
  • the reaction carrier is derived from the conveyor section 5 by means of a discharge line 15.
  • the two weirs 9, 13 are preferably always set to the same height.
  • the excess reaction carrier from the front overflow chamber 9 and the rear overflow chamber 13, which was in each case derived via the discharge lines 12 and 15, is brought together in a collecting line 16 and by means of a filter and a pump, not shown in FIG. 1 17 distributed over a line 18 of a heating device 19, via a line 20 to a rinsing system 21 and via a line 22 to a cooling vessel, not shown.
  • the heating device 19 is designed as an evaporator or superheater and heats up the filtered reaction carrier derived from the conveyor section. From the heating device 19, the overheated reaction carrier is conducted via a line 23, preferably in vapor form, to a plurality of nozzles 25 attached to the bottom 24 of the conveying device 1. The nozzles 25 are all arranged in a front section of the conveyor section 5 facing the task area. The superheated steam is blown into the dissolved cellulose slurry through the nozzles 25 in the inlet region of the conveying section, so that it is quickly heated to the reaction temperature. The cellulose slurry is usually introduced into the feed area at a temperature of 60 ° C. to 90 ° C.
  • the dissolved cellulose slurry 4 is kept essentially at this reaction temperature during the transport along the conveyor path 5.
  • the residence time of the dissolved cellulose slurry in the conveyor is approximately 40 to 120 minutes. During this time, the cellulose slurry is conveyed from the delivery area to the discharge area.
  • the reaction temperature of the cellulose slurry 4 is maintained by a plurality of heating devices: on the one hand, the jacket 26, which at least in sections surrounds the conveying section 5 — preferably in the region of the reaction space 4 — is essentially tubular.
  • the jacket 26 can be flowed through by a heating fluid or else have electrical or otherwise operated heating elements.
  • the conveying means, in the exemplary embodiment of FIG. 1, the screw 2 can be heated via a heating device 27.
  • a heating medium can flow through the screw for heating, or it can be electrically heated.
  • the synthesized cellulose carbamate is conveyed out of the discharge area 7 by means of a discharge device 28.
  • the size of the reaction space 4 of the conveyor 1, in which the cellulose carbamate is synthesized, is essentially determined by the fill level 10.
  • the filling level 10 is in turn set by the position of the overflow weirs 9 and 13 at the two ends of the conveyor.
  • An essentially cellulose-free vapor space is formed above the reaction space, in which the vapor vapor is collected and fed to an vapor condenser 31 via vapor lines 30.
  • heat is drawn from the vapor vapor in the vapor condenser 31 via a cooling line 32 and the vapor condensate is mixed with the reaction medium 18 from the overflow chambers 11 and 14 via a line 33 in the evaporator or superheater and supplied to the heating device 25. Exhaust air purification can take place via a line 34.
  • the flushing device 21 is arranged, which is provided with a multiplicity of flushing nozzles 35, through which filtered reaction carriers are directed from the line 20 onto the conveying means 2.
  • a multiplicity of flushing nozzles 35 through which filtered reaction carriers are directed from the line 20 onto the conveying means 2.
  • the flushing device 21 is preferably operated intermittently. In this way, the conveyor 2 is cleaned during the operation of the conveyor and while carbamate synthesis is in progress.
  • Fig. 2 a section along the line II-II of Fig. 1 is shown schematically.
  • the heating jacket 26 essentially only surrounds the reaction space 4.
  • the vapor space 29 has a vapor dome 36 which forms a bulge upward in relation to the casing 37 of the conveying path.
  • bulging is produced in that a tubular segment 38 is placed on the tubular jacket 37, which at least partially surrounds the conveyor section 5, the jacket of the tube 37 being omitted in the region of the tubular segment 38.
  • the vapor lines 30 end in the vapor dome 36 and derive the vapor accumulating there from the vapor dome 36.
  • the spray nozzles 35 are sunk in the conversion of the conveying path.
  • the spray nozzles 35 can be arranged in the vapor dome 36 or in the vicinity of its lower edge. An arrangement in the upper part of the conveying device is preferred, so that the conveying means can be flushed out well.
  • FIG. 3 shows a further exemplary embodiment of the conveyor device according to the invention, which is designed as a reactor system.
  • the embodiment of FIG. 3 has a large number of correspondences with the embodiment of FIG.
  • the cellulose slurry 42 coming from the stripping is transported on the sieve belt 41 into the feed area 6 of the conveying device 1.
  • the cellulose slurry is separated from most of the reaction carrier during transport on the screen belt.
  • the separated reaction carrier is passed through a line 43 for mashing.
  • the conveying, heating of the cellulose slurry dissolved in the reaction carrier and the reprocessing of the reaction carrier in the conveying device 1 take place in the embodiment of FIG. 3 in the same way as in the embodiment of FIG. 2.
  • Another difference from the embodiment of FIG. 2 in the embodiment of FIG. 3 lies in the different configuration of the discharge device 28.
  • the discharge device is not designed as a screw pump, but rather is designed so that it only contains the cellulose carbamate promotes the discharge area 7 and thereby leaves most of the reaction carrier in the discharge area except for the part adhering to the cellulose carbamate.
  • the cellulose carbamate is fed from the discharge device 28 to a next process step for further processing.
  • FIG. 4 schematically shows a section along the line IV-IV.
  • the cross section of the exemplary embodiment of FIG. 3 largely corresponds to the cross section of the exemplary embodiment of FIG. 1 as shown in FIG. 2. Therefore, only the differences are discussed below.
  • the cross section is elliptical or oval.
  • the arrangement of the conveying means 2 in the lower region of the conveying path 5 leaves sufficient vapor space in this configuration in the upper region of the conveying path 5.
  • the flushing device 21 is attached in the upper part of the conveyor line. If the dimensions are large enough, the conveyor line can also be designed as a normal pipe. Only the fill level 10 has to be dimensioned such that sufficient vapor space 29 is available. In this case, the conveyor 2 can protrude into the vapor space 29. Then the nozzles 21 - like the nozzles 25 - are to be designed so that they do not collide with the conveying means. Likewise, the mouth of the vapor line 30 is then to be recessed.
  • the conveying device designed as a reaction system, conveys the cellulose slurry arriving in the feed area 6 evenly without scattering the dwell times through the conveying path 5, so that a uniform quality of the cellulose slurry is achieved. Another positive effect is achieved by the constant recirculation of part of the reaction carrier. The recirculation of the reaction carrier saves energy and material.
  • Further devices, such as the rinsing device and a device 25 for quickly heating the cellulose slurry at the entry area of the conveyor line represent further advantageous configurations of the conveyor device, as does the possibility of heating the conveyor means 2 and casing 26 of the conveyor line 5, at least in the area of the reaction space 4.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Biochemistry (AREA)
  • Materials Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Polysaccharides And Polysaccharide Derivatives (AREA)

Abstract

L'invention concerne un procédé de synthèse du carbamate de cellulose et un dispositif de transport (1) pour transporter une bouillie cellulosique (4) dissoute dans un support de réaction organique. Jusqu'à présent, on utilise des mélangeurs disposés en cascades pour faire la synthèse du carbamate de cellulose. Ces mélangeurs en cascades sont complexes et produisent un carbamate de cellulose de qualité irrégulière, en raison d'une grande amplitude du temps de séjour de la bouillie cellulosique dans les mélangeurs. Selon l'invention, un dispositif de transport (1) est conçu comme système de réacteur pour réaliser ou pour permettre de réaliser la synthèse en continu du carbamate de cellulose. La bouillie cellulosique (4) en suspension dans un support de réaction organique inerte est d'abord chauffée au moyen d'un dispositif de chauffage (25, 26, 27) dans le dispositif de transport en continu (1), pour être maintenue sensiblement à température de réaction pendant ce transport le long d'une voie de transport (5) dudit dispositif de transport (1).
EP02718029A 2001-01-18 2002-01-16 Dispositif et procede de synthese en continu du carbamate de cellulose Withdrawn EP1351993A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10102172 2001-01-18
DE2001102172 DE10102172A1 (de) 2001-01-18 2001-01-18 Verfahren und Vorrichtung zur kontinuierlichen Synthese von Cellulosecarbamat
PCT/EP2002/000418 WO2002060956A1 (fr) 2001-01-18 2002-01-16 Dispositif et procede de synthese en continu du carbamate de cellulose

Publications (1)

Publication Number Publication Date
EP1351993A1 true EP1351993A1 (fr) 2003-10-15

Family

ID=7670995

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02718029A Withdrawn EP1351993A1 (fr) 2001-01-18 2002-01-16 Dispositif et procede de synthese en continu du carbamate de cellulose

Country Status (3)

Country Link
EP (1) EP1351993A1 (fr)
DE (1) DE10102172A1 (fr)
WO (1) WO2002060956A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10223172B4 (de) * 2002-05-24 2004-05-06 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Verfahren zur Herstellung von Cellulosecarbamat mittels reaktiver Extrusion und die Verwendung der Verfahrensprodukte zur Herstellung von Formkörpern
DE102004007616B4 (de) * 2004-02-17 2005-12-22 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Verfahren zur Herstellung von Fasern und anderen Formkörpern aus Cellulosecarbamat und/oder regenerierter Cellulose
FI129395B (en) 2020-04-06 2022-01-31 Andritz Oy PROCESS FOR THE PREPARATION OF CELLULOSACARBAMATE

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB830985A (en) * 1957-07-05 1960-03-23 Emil Glauber Improved apparatus for the treatment of particulate solid material, in particular for ageing comminuted alkali cellulose
DE2924330A1 (de) * 1979-06-15 1980-12-18 Hoechst Ag Kontinuierliches verfahren und vorrichtung zur herstellung von wasserloeslicher hydroxyalkylcellulose oder deren mischethern
US5378827A (en) * 1992-12-16 1995-01-03 Zimmer Aktiengesellschaft Process for the production of cellulose carbamate
JPH08224735A (ja) * 1995-02-21 1996-09-03 Tonen Chem Corp 高分子物質と液体との混練方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO02060956A1 *

Also Published As

Publication number Publication date
DE10102172A1 (de) 2002-08-01
WO2002060956A1 (fr) 2002-08-08

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