WO2001051159A1 - Method for cleaning stripping columns - Google Patents

Method for cleaning stripping columns Download PDF

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Publication number
WO2001051159A1
WO2001051159A1 PCT/EP2001/000154 EP0100154W WO0151159A1 WO 2001051159 A1 WO2001051159 A1 WO 2001051159A1 EP 0100154 W EP0100154 W EP 0100154W WO 0151159 A1 WO0151159 A1 WO 0151159A1
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Prior art keywords
cleaning
column
aqueous
weight
basic compound
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PCT/EP2001/000154
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German (de)
French (fr)
Inventor
Josef Neutzner
Wolfgang HÜBINGER
Original Assignee
Basf Aktiengesellschaft
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Publication date
Application filed by Basf Aktiengesellschaft filed Critical Basf Aktiengesellschaft
Priority to AU2001240500A priority Critical patent/AU2001240500A1/en
Publication of WO2001051159A1 publication Critical patent/WO2001051159A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
    • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
    • C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
    • C11D7/02—Inorganic compounds
    • C11D7/04—Water-soluble compounds
    • C11D7/06—Hydroxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D19/00—Degasification of liquids
    • B01D19/0005—Degasification of liquids with one or more auxiliary substances
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B08—CLEANING
    • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B9/00—Cleaning hollow articles by methods or apparatus specially adapted thereto
    • B08B9/08—Cleaning containers, e.g. tanks
    • C—CHEMISTRY; METALLURGY
    • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
    • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
    • C11D2111/00—Cleaning compositions characterised by the objects to be cleaned; Cleaning compositions characterised by non-standard cleaning or washing processes
    • C11D2111/10—Objects to be cleaned
    • C11D2111/14—Hard surfaces
    • C11D2111/20—Industrial or commercial equipment, e.g. reactors, tubes or engines

Definitions

  • the present invention relates to a process for cleaning separation columns through which aqueous polymer dispersions or polymer suspensions were passed following the polymerization reactions in order to remove volatile constituents.
  • aqueous polymer dispersions and polymer suspensions by so-called radically initiated aqueous emulsion or suspension polymerizations.
  • the products often also contain volatile constituents, such as residual monomers resulting from incomplete monomer conversion, impurities from the feedstocks, decomposition products of the initiators or low molecular weight products from side reactions.
  • aqueous polymer dispersions and polymer suspensions are used before or after an optional radical postpolymerization to remove these volatile components of a so-called inert gas - and / or steam stripping supplied (deodorization).
  • inert gas - and / or steam stripping supplied deodorization
  • Separation columns are frequently used for deodorization of large amounts of aqueous polymer dispersions and polymer suspensions, in which the aqueous polymer systems flow continuously from top to bottom and an inert gas and / or water vapor stream is directed towards them from bottom to top.
  • the volatile constituents are removed from the aqueous polymer systems and continuously discharged from the separation column via the inert gas and / or water vapor.
  • the separation columns In order to enable the volatile constituents from the aqueous polymer systems to transition as quickly and completely as possible into the inert gas and / or water vapor flow during the deodorization, the separation columns must have internals which ensure a large surface area of the aqueous polymer systems.
  • aqueous polymer systems form polymer films on the inner surfaces of the separation columns, which can also grow to form larger caking. These lead to a drop in performance and, in extreme cases, to complete blockage of the separation column. These caking can also partially detach again and lead to undesired particles in the product of value, which would interfere with the formation of the desired homogeneous polymer films in the corresponding end uses.
  • the aqueous polymer systems are therefore usually subjected to filtration.
  • these separation columns are regularly cleaned manually with a high-pressure water jet in complex work steps.
  • the resulting downtimes of the separation columns are up to two weeks.
  • a process for cleaning separation columns by which aqueous polymer dispersions or polymer suspensions were passed following the polymerization reactions to remove volatile constituents was found, which is characterized in that the cleaning comprises contacting the inner surfaces of the separation columns with an aqueous solution of a includes basic compound.
  • Suitable separation columns to be cleaned are generally customary columns, such as, for example, tray columns, packed columns and packed columns.
  • Commercially available shelves, packing elements or packings such as bell bottoms, tunnel bottoms, valve bottoms, sieve bottoms, dual flow bottoms and mesh shelves, Pall-Rings ® , Berl ® saddle bodies, mesh wire rings, Raschig-Rings ® , Intalox ® saddles, Interpak ® fillers can be installed and Intos ® rings, but also ordered packings such as Sulzer-Mellapak ® or Sulzer-Optiflow ® , kuhni-Rombopak ® and Montz-Pak ® as well as tissue packs are used.
  • the inner surfaces of the separation columns are understood to mean all surfaces within the separation columns, such as, for example, the inner surfaces of the separation columns themselves and all surfaces of the internals located in the separation columns.
  • the inner surfaces of a separation column are brought into contact with an aqueous solution of a basic compound (basic washing solution).
  • the contacting of the inner surfaces with the basic washing solution can be carried out, for example, in such a way that the separation column is completely filled with this solution.
  • the basic washing solution of the separation column can either be via feed lines in the column head or in the
  • Suitable basic compounds are alkali metal and alkaline earth metal hydroxides, such as sodium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide and calcium hydroxide, ammonium hydroxide, alkali metal and alkaline earth metal salts of weak acids, such as carbonic acid, organic carboxylic acids or phosphoric acids, such as sodium carbonate, potassium carbonate and their hydrogen carbonates - Carbonate and potassium bicarbonate, sodium acetate, potassium acetate, calcium acetate, magnesium acetate, sodium propionate, potassium propionate, calcium propionate, magnesium propionate, trisodium phosphate, tripotassium phosphate and organic nitrogen compounds, such as C ⁇ ⁇ to C -alkylamine, such as methylamine, ethylamine, n-propylamine iso-propylamine, n-butylamine, 2-butylamine, tert.
  • weak acids such as carbonic acid, organic carboxylic acids or phosphoric acids, such
  • C ⁇ ⁇ to C 4 -dialkylamines such as dimethylamine, diethylamine, di-n-propylamine, di-iso-propylamine, di-n-butylamine, dibutylamine-2, di-tert.
  • -butylamine C ⁇ ⁇ to C 4 ⁇ trialkylamines, such as trimethylamine, triethylamine, tri-n-propylamine, tri-iso-propylamine, tri-n-butylamine, tributylamine-2, tri-tert-butylamine but also amino group-containing organic hydroxy - Compounds such as monoethanolamine, diethanolamine, triethanolamine, 2-aminopropanol, 3-aminopropanol, 2-aminobutanol, 3-aminobutanol, 4-aminobutanol, 2-amino-2-methylpropanol, 2-amino-2-hydroxymethyl-l, 3 propanediol and 2-amino-2-ethyl-l, 3-propanediol.
  • an aqueous solution which contains two or more of the aforementioned basic compounds.
  • Aqueous solutions of sodium hydroxide and / or potassium hydroxide are preferably used
  • basic washing solutions are used whose proportion by weight of the basic compound is generally> 0.1% by weight,> 1% by weight,> 2% by weight,> 3% by weight,> 5% by weight % and
  • Basic washing solutions are frequently used, the basic compounds of which have a proportion by weight of between 1 and 20% by weight, often between 1.5 and 15% by weight or between 2 and 10% by weight, in each case based on the total weight of the basic washing solution.
  • the basic washing solution has a temperature of> 0 to 150 ° C during cleaning. However, it is also possible to set even higher temperatures. For practical reasons, temperatures between 20 and 150 ° C are preferred.
  • the basic washing solution often has temperatures between 30 and 120 ° C or between 40 and 110 ° C.
  • the way in which the basic washing solution is heated is in principle irrelevant; for example, internal or external heat exchangers attached to the separating column or a separate electric heater can be used for this.
  • it has proven to be advantageous if the basic washing solution flowing down within the separating column is heated by steam which is introduced at the bottom of the column. This also leads to the basic washing solution being agitated vigorously within the separation column.
  • the steam temperature is usually> 100 ° C and can have values of> 110 ° C,> 120 ° C,> 130 ° C,> 140 ° C,> 150 ° C or> 160 ° C.
  • Water vapor is often fed in in the form of water vapor under pressure. The water vapor often has a pressure of 4 or 16 bar. The steam flow is adjusted so that on the one hand the desired cleaning temperature can be reached and maintained and on the other hand the basic washing solution can flow down and be pumped around.
  • cleaning takes place at an internal column pressure corresponding to the external atmospheric pressure (1 bar absolute), at negative pressure ( ⁇ 1 bar absolute) or at excess pressure (> 1 bar absolute), each measured in the column head.
  • cleaning can be carried out at pressures of ⁇ 950 mbar, ⁇ 900 mbar, ⁇ 850 bar, ⁇ 800 mbar or even lower pressures.
  • cleaning is often carried out at atmospheric pressure or at pressures> 1.5 bar,> 2 bar,> 3 bar,> 4 bar,> 5 bar (absolute values in each case) or even higher pressures, each measured in the column top.
  • volume quantities are used which are> 0.1 vol.%,> 1 vol.%,> 3 vol.%,> 5 vol.%,> 10 vol.%,> 20 vol.% ,> 30 vol.%,> 50 vol.%,> 70 vol.%,> 100 vol. -% or even higher values, based in each case on the total internal volume of the separation column.
  • volume quantities are used which are> 0.1 vol.%,> 1 vol.%,> 3 vol.%,> 5 vol.%,> 10 vol.%,> 20 vol.% ,> 30 vol.%,> 50 vol.%,> 70 vol.%,> 100 vol. -% or even higher values, based in each case on the total internal volume of the separation column.
  • the cleaning according to the invention can in principle take place in the case of polymer films or caking adhering to the inner surfaces, which were formed from polymer particles whose homo- or copolymers are composed of at least one of the following ethylenically unsaturated monomers: vinyl-aromatic monomers such as styrene, ⁇ -methylstyrene, o-chlorostyrene or vinyl toluenes, esters of vinyl alcohol and monocarboxylic acids containing 1 to 18 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl laurate and vinyl stearate, esters of ⁇ -, ß- preferably having 3 to 6 carbon atoms monoethylenically unsaturated mono- and dicarboxylic acids, such as, in particular, acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid, with alkanols which generally have 1 to 12, preferably 1 to 8 and in
  • the monomers mentioned In the case of aqueous polymer systems produced by the free-radical aqueous emulsion or suspension polymerization method, the monomers mentioned generally form the main monomers, which, based on the total amount of the monomers to be polymerized by the free-radically initiated aqueous emulsion or suspension polymerization process, normally combine a share of more than 50 wt .-%.
  • the following monomers are usually used in free-radical aqueous emulsion or suspension polymerization only as modifying monomers in amounts, based on the total amount of the monomers to be polymerized, of less than 50% by weight, generally 0.5 to 20, preferably 1 to 10% by weight polymerized: ⁇ , ß-monoethylenically unsaturated mono- and dicarboxylic acids and their amides, such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, acrylamide and methacrylamide, furthermore monoethylenically unsaturated sulfonic acids and their water-soluble salts, such as vinylsulfonic acid and N vinylpyrrolidone.
  • ß-monoethylenically unsaturated mono- and dicarboxylic acids and their amides such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, acrylamide and methacrylamide, furthermore monoethy
  • Monomers which usually increase the internal strength of the films of the aqueous polymer dispersions or suspensions normally have at least one epoxy, hydroxyl, N-methylol or carbonyl group, or at least two non-conjugated ethylenically unsaturated double bonds.
  • these are N-alkylolamides of ⁇ , ⁇ -monoethylenically unsaturated carboxylic acids having 3 to 10 C atoms, among which the N-methylolacrylamide and the N-methylolmethacrylamide are very particularly preferred and their esters having 1 to 4 C atoms alkanols.
  • two monomers having vinyl radicals two monomers having vinylidene radicals and two monomers having alkenyl radicals are also suitable.
  • Particularly advantageous are the di-esters of dihydric alcohols with ⁇ , ⁇ -mono-ethylenically unsaturated monocarboxylic acids, among which acrylic and methacrylic acid are preferred.
  • alkylene glycol diacrylates and dimethacrylates such as ethylene glycol diacrylate, 1, 2-propylene glycol diacrylate, 1, 3-propylene glycol diacrylate, 1, 3-butylene glycol diacrylate and 1, 4-methylene diacrylate -Propylene glycol dimethacrylate, 1, 3-propylene glycol dimethacrylate, 1, 3-butylene glycol dimethacrylate, 1, 4-butylene glycol dimethacrylate as well as divinylbenzene, vinyl methacrylate, vinyl acrylate, allyl methacrylate, allyla acrylate, dially maleate, diallyl bisyl acrylate, diallyl bisacrylate, Of particular importance in this context are the methacrylic acid and acrylic acid Ci-Cs-hydroxyalkyl esters such as n-hydroxyethyl, n-hydroxypropyl or n-hydroxybutyl acrylate, Of particular importance in this context are the methacrylic acid and acrylic acid Ci-Cs-hydroxyal
  • the abovementioned monomers are generally polymerized in amounts of up to 10% by weight.
  • the cleaning method according to the invention can advantageously be used in the case of polymer filming or caking which have been formed from polymer systems whose homo- or copolymers are at least partially composed of an ethylenically unsaturated Monomers of the following monomer classes are constructed: esters of vinyl alcohol and monocarboxylic acids having 1 to 18 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl laurate and vinyl stearate, esters of ⁇ having preferably 3 to 6 carbon atoms , ß-monoethylenically unsaturated mono- and dicarboxylic acids, such as in particular acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid, with alkanols generally having 1 to 12, preferably 1 to 8 and in particular 1 to 4 carbon atoms, such as, in particular, acrylic acid and Methacrylic acid methyl, ethyl, n-butyl, tert.
  • -butyl-, -iso-butyl and -2-ethylhexyl esters dimethyl maleate or di-n-butyl maleate, ⁇ , ß-monoethylenically unsaturated mono- and dicarboxylic acids and their amides such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid , Acrylamide and methacrylamide, and also ethylenically unsaturated sulfonic acids, such as vinyl sulfonic acid.
  • the cleaning process according to the invention can be used for polymer films or caking formed from polymer systems whose homo- or copolymers are> 10% by weight,> 20% by weight,> 30% by weight,> 40 % By weight,> 50% by weight,> 60% by weight,> 70% by weight,> 80% by weight,> 90% by weight or even 100% by weight, in each case based based on the total amount of ethylenically unsaturated monomers used for the polymerization, composed of at least one ethylenically unsaturated monomer of the following monomer classes: esters of ⁇ , ⁇ -monoethylenically unsaturated mono- and dicarboxylic acids, preferably having 3 to 6 C atoms, such as in particular acrylic acid, Methacrylic acid, maleic acid, fumaric acid and itaconic acid, with alkanols generally having 1 to 12, preferably 1 to 8 and in particular 1 to 4 carbon atoms, such as, in particular, methyl, ethyl,
  • -butyl-, -isobutyl and -2-ethylhexyl ester maleic acid dimethyl ester or maleic acid di-n-butyl ester
  • ⁇ ß-monoethylenically unsaturated mono- and dicarboxylic acids and their amides such as e.g. Acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, acrylamide and methacrylamide, and also ethylenically unsaturated sulfonic acids, such as vinylsulfonic acid.
  • the mechanical detachment for example with a high-pressure water jet, facilitates and thus the cleaning time compared to the purely mechanical cleaning is significantly shortened.
  • the period of contacting is strongly dependent, for example, on the volume and type of internals of the separation column, the nature and thickness of the polymer films and caking, the type and amount of the basic compound used, their concentration in aqueous solution, and the one chosen for the cleaning process Temperature and the selected pressure.
  • the contact time can be from a few minutes to several hours. The optimal time period can easily be determined in routine tests that are easy to carry out.
  • the heat exchanger and / or filtration devices upstream or downstream of the separation column can also be cleaned of their adhering polymer films or caking. This is possible by simply contacting the inner surfaces of the separation column with basic washing solution in accordance with the invention by contacting the inner surfaces of the upstream or downstream heat exchangers and / or filtration devices, for example by integrating these apparatuses into the pumping line of the basic Wash solution, expands.
  • the basic washing solution is usually completely emptied from the separation column and any apparatuses connected upstream or downstream.
  • the separation column and any upstream or downstream apparatus are then rinsed with deionized water until the rinsing water has a pH ⁇ 8 or often ⁇ 7.5.
  • the devices After the devices have been completely emptied, they are again available for removing volatile constituents from aqueous polymer suspensions or polymer dispersions.
  • aqueous polymer dispersions In a 9.3 m high separation column with an inner diameter of approx. 50 cm and a total of 10 so-called rain sieve trays, aqueous polymer dispersions, the polymer particles of which were copolymers of tert. -Butyl acrylate, ethyl acrylate and methacrylic acid were built, freed of volatile constituents by introducing 4 bar water vapor. After treating a total of approx. 240 t of aqueous polymer dispersions, the column had heavy deposits, caking and coagulum precipitates with a thickness of up to 5 mm, so that they only had to a throughput reduced compared to the nominal power could be operated.
  • Caking can be determined more.
  • the separation column could again be operated at 100% of its performance.
  • the column had severe filming, deposits and coagulum precipitates with a thickness of up to 5 mm, so that they are only operated at significantly reduced throughputs, in each case based on the corresponding nominal outputs could.
  • aqueous sodium hydroxide solution About 4000 kg of a 2% strength by weight aqueous sodium hydroxide solution at about 25 ° C. were placed in a stirred tank serving as a template. With a volume flow of approx. 12 m 3 per hour, the aqueous sodium hydroxide solution was pumped through one in the feed line Bag filter and a feed device on the top of the column. The aqueous sodium hydroxide solution was heated to about 100 ° C. in the feed line using a steam injector. At the same time, approximately 500 kg of 4 bar water vapor were metered into the separation column at the bottom of the column. The feed of fresh aqueous sodium hydroxide solution was terminated after about 20 minutes.
  • the sodium hydroxide solution collected in the column sump was then pumped back through the feed pump to the top of the column, from where it continuously flowed down over all the trays.
  • the volume flow of the circulation was also approximately 12 m 3 per hour.
  • the amount of 4 bar steam fed in at the bottom of the column was gradually increased to about 1700 kg per hour within 6 hours. After a total of 6 hours, the steam supply and the pumping over of the aqueous sodium hydroxide solution were stopped.
  • the separation column was then completely emptied.
  • the separating column with its feed and discharge lines was then rinsed five times with 200 l of deionized water from the sodium hydroxide solution and in each case completely emptied. In the end, the rinse water had a pH of 7.5.
  • the separation column could again be operated at 100% of its performance.

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Abstract

The invention relates to a method for cleaning stripping columns through which aqueous polymer dispersions or polymer suspensions are guided following polymerisation reactions, in order to remove more volatile constituents. The method is characterised in that the cleaning process comprises the inner surfaces of the stripping columns being brought into contact with an aqueous solution of a basic compound.

Description

Verfahren zum Reinigen von TrennkolonnenProcess for cleaning separation columns
Beschreibungdescription
Die vorliegende Erfindung betrifft ein Verfahren zum Reinigen von Trennkolonnen, durch die wässrige Polymerisatdispersionen oder Polymerisatsuspensionen im Anschluß an die Polymerisationsreak- tionen zum Entfernen von leichtflüchtigen Bestandteilen geleitet wurden.The present invention relates to a process for cleaning separation columns through which aqueous polymer dispersions or polymer suspensions were passed following the polymerization reactions in order to remove volatile constituents.
Es ist bekannt, wässrige Polymerisatdispersionen und Polymerisatsuspensionen durch sogenannte radikalisch initiierte wässrige Emulsions- oder Suspensionspolymerisationen herzustellen. Die Produkte enthalten im Anschluß an die Haupt- und gegebenenfalls Nachpolymerisation häufig noch leichtflüchtige Bestandteile, wie beispielsweise Rest onomere resultierend aus einem nicht vollständigen Monomerenumsatz , Verunreinigungen aus den Einsatz - Stoffen, Zerfallsprodukte der Initiatoren oder niedermolekulare Produkte aus Nebenreaktionen. Da die leichtflüchtigen Bestandteile bei vielen Anwendungen von wässrigen Dispersions- und Suspensionssystemen unerwünscht sind, so zum Beispiel im Lebensmittel- oder Kosmetikbereich oder bei Innenraumanwendungen, werden die wässrigen Polymerisatdispersionen und Polymerisatsuspensionen vor oder nach einer gegebenenfalls durchgeführten radikalischen Nachpolymerisation zur Entfernung dieser leichtflüchtigen Komponenten einer sogenannten Inertgas- und/oder Wasserdampfstrippung zugeführt (Desodorierung) . Entsprechende Verfahren sind seit langem allgemein bekannt und beispielsweise in den Schriften DE-A 25 50 023, DE-C 27 59 097, DE-C 28 55 146 oder DE-C 25 21 780 beschrieben. Häufig werden zur Desodorierung großer Mengen wässriger Polymerisatdispersionen und Polymerisatsuspensionen Trennkolonnen, sogenannte Strippkolonnen, eingesetzt, in welchen die wässrigen Polymerisatsysteme kontinuierlich von oben nach un- ten herabfließen und ihnen von unten nach oben ein Inertgas- und/ oder ein Wasserdampfström entgegengeleitet wird. Dadurch werden die leichtflüchtigen Bestandteile aus den wässrigen Polymerisat - Systemen entfernt und über den Inertgas- und/oder Wasserdampf - ström kontinuierlich aus der Trennkolonne ausgetragen. Um während der Desodorierung einen möglichst raschen und vollständigen Übergang der leichtflüchtigen Bestandteile aus den wässrigen Polyme- risatsystemen in den Inertgas- und/oder Wasserdampfström zu ermöglichen, müssen die Trennkolonnen Einbauten aufweisen, die eine große Oberfläche der wässrigen Polymerisatsysteme sicherstellen. Ein solches Verfahren ist beispielsweise in der Internationalen Patentanmeldung WO 97/45184 der Anmelderin beschrieben. Dabei wird beispielsweise ein wässriges Polymerisatsystem zur Desodorierung in einer mit Regensiebböden und/oder Querstromsieb - böden bestückten Gegenstromkolonne mit Wasserdampf behandelt. Mit der in dieser Anmeldung beschriebenen speziellen Gegenstromkolonne können die Siebböden der Kolonne vereinfacht und der spezifische Durchsatz erhöht werden. Diese Gegenstromkolonnen sind konstruktiv aufwendig aus einem Stück gefertigt, wobei die Sieb- böden nachträglich auf eingeschweißten Tragringen aufgeschraubt wurden.It is known to produce aqueous polymer dispersions and polymer suspensions by so-called radically initiated aqueous emulsion or suspension polymerizations. Following the main and optionally postpolymerization, the products often also contain volatile constituents, such as residual monomers resulting from incomplete monomer conversion, impurities from the feedstocks, decomposition products of the initiators or low molecular weight products from side reactions. Since the volatile constituents are undesirable in many applications of aqueous dispersion and suspension systems, for example in the food or cosmetics sector or in interior applications, the aqueous polymer dispersions and polymer suspensions are used before or after an optional radical postpolymerization to remove these volatile components of a so-called inert gas - and / or steam stripping supplied (deodorization). Corresponding methods have long been known and are described, for example, in DE-A 25 50 023, DE-C 27 59 097, DE-C 28 55 146 or DE-C 25 21 780. Separation columns, so-called stripping columns, are frequently used for deodorization of large amounts of aqueous polymer dispersions and polymer suspensions, in which the aqueous polymer systems flow continuously from top to bottom and an inert gas and / or water vapor stream is directed towards them from bottom to top. As a result, the volatile constituents are removed from the aqueous polymer systems and continuously discharged from the separation column via the inert gas and / or water vapor. In order to enable the volatile constituents from the aqueous polymer systems to transition as quickly and completely as possible into the inert gas and / or water vapor flow during the deodorization, the separation columns must have internals which ensure a large surface area of the aqueous polymer systems. Such a method is described, for example, in the applicant's international patent application WO 97/45184. For example, an aqueous polymer system for deodorization is treated with steam in a counterflow column equipped with rain sieve trays and / or crossflow sieve trays. With the special countercurrent column described in this application, the sieve plates of the column can be simplified and the specific throughput can be increased. These countercurrent columns are complex, one-piece designs, with the sieve trays subsequently screwed onto welded-on support rings.
Derartige Konstruktionen sind jedoch mit Nachteilen behaftet. Wässrige Polymerisatsysteme bilden unter Trennbedingungen auf den inneren Oberflächen der Trennkolonnen Polymerisatfilme, welche auch zu größeren Anbackungen aufwachsen können. Diese führen zu einem Leistungsabfall und im Extremfall sogar zur vollständigen Verstopfung der Trennkolonne. Auch können sich diese Anbackungen teilweise wieder ablösen und im Wertprodukt zu unerwünschten Par- tikeln führen, welche in den entsprechenden Endanwendungen die Ausbildung der gewünschten homogenen Polymerisatfilme stören würden. Die wässrigen Polymerisatsysteme werden daher im Regelfall einer Filtration unterzogen.However, such constructions have disadvantages. Under separation conditions, aqueous polymer systems form polymer films on the inner surfaces of the separation columns, which can also grow to form larger caking. These lead to a drop in performance and, in extreme cases, to complete blockage of the separation column. These caking can also partially detach again and lead to undesired particles in the product of value, which would interfere with the formation of the desired homogeneous polymer films in the corresponding end uses. The aqueous polymer systems are therefore usually subjected to filtration.
Zur Vermeidung von Störungen infolge solcher unerwünschter Verfilmungen und Anbackungen werden diese Trennkolonnen in aufwendigen Arbeitsschritten regelmäßig manuell mit einem Hochdruckwasserstrahl gereinigt. Die dadurch bedingten Stillstandszeiten der Trennkolonnen betragen bis zu zwei Wochen.To avoid malfunctions due to such undesirable filming and caking, these separation columns are regularly cleaned manually with a high-pressure water jet in complex work steps. The resulting downtimes of the separation columns are up to two weeks.
In einer beim Deutschen Patent- und Markenamt unter der Nummer DE 19847115.7-09 eingereichten Anmeldung wurde von der Anmelderin vorgeschlagen, die Einbauten innerhalb der Trennkolonne so zu gestalten, daß sie zu Reinigungszwecken aus der Trennkolonne her- ausgenommen und so in einfacher Weise gereinigt oder durch bereits gereinigte Einbauten ersetzt werden können. Durch diese Verfahrensvariante lassen sich die Stillstandszeiten auf etwa drei Tage reduzieren.In an application filed with the German Patent and Trademark Office under number DE 19847115.7-09, the applicant proposed to design the internals within the separation column in such a way that they were removed from the separation column for cleaning purposes and thus cleaned or cleaned in a simple manner already cleaned internals can be replaced. With this process variant, downtimes can be reduced to around three days.
Aufgabe der vorliegenden Erfindung war es, ein einfacheres Verfahren zum Reinigen von Trennkolonnen, durch die wässrige Polymerisatdispersionen oder Polymerisatsuspensionen im Anschluß an die Polymerisationsreaktionen zum Entfernen von leichtflüchtigen Bestandteilen geleitet wurden, zur Verfügung zu stel- len, das ohne größere Demontagearbeiten auskommt und so die erforderlichen Stillstandszeiten der Trennkolonnen weiter reduziert.It was an object of the present invention to provide a simpler process for cleaning separation columns through which aqueous polymer dispersions or polymer suspensions were passed following the polymerization reactions to remove volatile constituents, and which does not require any major dismantling work, and so on required downtimes of the separation columns are further reduced.
Demgemäß wurde ein Verfahren zum Reinigen von Trennkolonnen, durch die wässrige Polymerisatdispersionen oder Polymerisatsuspensionen im Anschluß an die Polymerisationsreaktionen zum Entfernen von leichtflüchtigen Bestandteilen geleitet wurden, gefunden, das dadurch gekennzeichnet ist, daß das Reinigen ein Inkontaktbringen der inneren Oberflächen der Trennkolonnen mit einer wässrigen Lösung einer basischen Verbindung umfaßt.Accordingly, a process for cleaning separation columns by which aqueous polymer dispersions or polymer suspensions were passed following the polymerization reactions to remove volatile constituents was found, which is characterized in that the cleaning comprises contacting the inner surfaces of the separation columns with an aqueous solution of a includes basic compound.
Als zu reinigende Trennkolonnen eignen sich allgemein übliche Kolonnen, wie beispielsweise Bodenkolonnen, Füllkörperkolonnen und Packungskolonnen. Als Einbauten können handelsübliche Böden, Füllkörper oder Packungen, wie beispielsweise Glockenböden, Tunnelböden, Ventilböden, Siebböden, Dualflowböden und Gitterböden, Pall-Ringe®, Berl®-Sattelkörper, Netzdrahtringe, Raschig-Ringe®, Intalox®-Sättel, Interpak®-Füllkörper und Intos®-Ringe aber auch geordnete Packungen, wie beispielsweise Sulzer-Mellapak® oder Sulzer-Optiflow®, Kühni-Rombopak® und Montz-Pak® sowie Gewebepackungen Verwendung finden. Als innere Oberflächen der Trennkolonnen werden alle Oberflächen innerhalb der Trennkolonnen, wie beispielsweise die Innenflächen der Trennkolonnen selbst sowie alle Oberflächen der sich in den Trennkolonnen befindlichen Ein- bauten, verstanden.Suitable separation columns to be cleaned are generally customary columns, such as, for example, tray columns, packed columns and packed columns. Commercially available shelves, packing elements or packings such as bell bottoms, tunnel bottoms, valve bottoms, sieve bottoms, dual flow bottoms and mesh shelves, Pall-Rings ® , Berl ® saddle bodies, mesh wire rings, Raschig-Rings ® , Intalox ® saddles, Interpak ® fillers can be installed and Intos ® rings, but also ordered packings such as Sulzer-Mellapak ® or Sulzer-Optiflow ® , Kühni-Rombopak ® and Montz-Pak ® as well as tissue packs are used. The inner surfaces of the separation columns are understood to mean all surfaces within the separation columns, such as, for example, the inner surfaces of the separation columns themselves and all surfaces of the internals located in the separation columns.
Vor dem erfindungsgemäßen Reinigen empfiehlt es sich, die Trennkolonnen vollständig zu entleeren. Zur Reinigung werden die inneren Oberflächen einer Trennkolonne mit einer wässrigen Lösung einer basischen Verbindung (basische Waschlösung) in Kontakt gebracht. Das Inkontaktbringen der inneren Oberflächen mit der basischen Waschlösung kann beispielsweise derart durchgeführt werden, daß die Trennkolonne vollständig mit dieser Lösung gefüllt wird. Dabei kann die basische Waschlösung der Trennko- lonne sowohl über Zulauf1eitungen im Kolonnenkopf oder imBefore cleaning according to the invention, it is advisable to completely empty the separation columns. For cleaning, the inner surfaces of a separation column are brought into contact with an aqueous solution of a basic compound (basic washing solution). The contacting of the inner surfaces with the basic washing solution can be carried out, for example, in such a way that the separation column is completely filled with this solution. The basic washing solution of the separation column can either be via feed lines in the column head or in the
Kolonnensumpf oder an jeder beliebigen Stelle durch die seitliche Kolonnenwand zugeführt werden. Günstig ist es, wenn die Wasch- lösung innerhalb der Trennkolonne bewegt wird. Dies kann beispielsweise durch Umpumpen der Lösung sowie durch Einblasen von Inertgas, beispielsweise Stickstoff oder Luft, oder Wasser- dampf erfolgen. Das Inkontaktbringen ist beispielsweise aber auch dergestalt möglich, daß man die basische Waschlösung vom Kolonnenkopf über die inneren Oberflächen der Trennkolonne herabfließen oder herabrieseln läßt, diese im Kolonnensumpf sammelt und über eine Pumpe wieder in die Zulaufleitung zum Kolonnenkopf einspeist. Zur Erhöhung der Reinigungswirkung kann der herabfliesenden basischen Waschlösung vom Kolonnensumpf vorteilhaft ein Wasserdampfström entgegengeleitet werden. Dieser Wasserdampfström begünstigt das Inkontaktbringen durch eine gleichmäßige Verteilung der basischen Waschlösung über alle inneren Oberflächen der Trennkolonne. Diese Fahrweise hat gegenüber dem vollständigem Füllen der Kolonne den Vorteil, daß im Regelfall zur Reinigung deutlich weniger basische Waschlösung benötigt wird.Column sump or can be fed at any point through the side column wall. It is advantageous if the washing solution is moved within the separation column. This can be done, for example, by pumping around the solution and by blowing in inert gas, for example nitrogen or air, or water vapor. The contacting is also possible, for example, in such a way that the basic washing solution flows down or trickles down from the top of the column over the inner surfaces of the separating column, collects it in the bottom of the column and feeds it back into the feed line to the top of the column via a pump. In order to increase the cleaning effect, the flowing down basic washing solution from the column bottom can advantageously be used Steam flow can be directed. This water vapor flow favors the contacting by a uniform distribution of the basic washing solution over all inner surfaces of the separation column. This procedure has the advantage over completely filling the column that, as a rule, significantly less basic washing solution is required for cleaning.
Als basische Verbindung werden alle die Verbindungen verstanden, die in pH-neutralem Wasser (pH = 7) einen pH-Wert > 7 aufweisen. Zweckmäßig werden jedoch solche basischen Verbindungen eingesetzt, die in Wasser bei 20°C und 1 bar (absolut) eine Löslichkeit > 0,1 g/1 zeigen. Als basische Verbindungen geeignet sind Alkali - metall- und Erdalkalimetallhydroxide, wie beispielsweise Natriumhydroxid, Kaliumhydroxid, Lithiumhydroxid, Magnesiumhydroxid und Calciumhydroxid, Ammoniumhydroxid, Alkalimetall- und Erdalkalimetallsalze schwacher Säuren, wie Kohlensäure, organische Carbonsäuren oder Phosphorsäuren, wie beispielsweise Natriumcarbonat, Kaliumcarbonat sowie deren Hydrogencarbonate Natriumhydrogen- carbonat und Kaliumhydrogencarbonat, Natriumacetat, Kaliumacetat, Calciumacetat, Magnesiumacetat, Natriumpropionat, Kaliumpropio- nat, Calciumpropionat, Magnesiumpropionat, Trinatriumphosphat, Trikaliumphosphat sowie organische Stickstoffverbindungen, wie Cι~ bis C -Alkylamin, wie beispielsweise Methylamin, Ethylamin, n-Pro- pylamin, iso-Propylamin, n-Butylamin, 2-Butylamin, tert . -Butyla- min, Cι~ bis C4-Dialkylamine, wie beispielsweise Dimethylamin, Diethylamin, Di-n-propylamin, Di-iso-propylamin, Di-n-butylamin, Dibutylamin-2, Di-tert . -butylamin, Cι~ bis C4~Trialkylamine, wie beispielsweise Trimethylamin, Triethylamin, Tri-n-propylamin, Tri-iso-propylamin, Tri-n-butylamin, Tributylamin-2 , Tri-tert.- butylamin aber auch aminogruppenhaltige organische Hydroxy- verbindungen, wie beispielsweise Monoethanolamin, Diethanolamin, Triethanolamin, 2-Aminopropanol, 3-Aminopropanol , 2-Aminobutanol , 3-Aminobutanol, 4-Aminobutanol , 2-Amino-2-methylpropanol, 2-Amino-2-hydroxymethyl-l, 3-propandiol sowie 2-Amino-2-ethyl-l, 3- propandiol. Erfindungsgemäß kann auch eine wässrige Lösung eingesetzt werden, die zwei oder mehrere der vorgenannten basischen Verbindungen enthält. Bevorzugt werden wässrige Lösungen von Natriumhydroxid und/oder Kaliumhydroxid eingesetzt.A basic compound is understood to be all those compounds which have a pH> 7 in pH-neutral water (pH = 7). However, those basic compounds are expediently used which have a solubility> 0.1 g / l in water at 20 ° C. and 1 bar (absolute). Suitable basic compounds are alkali metal and alkaline earth metal hydroxides, such as sodium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide and calcium hydroxide, ammonium hydroxide, alkali metal and alkaline earth metal salts of weak acids, such as carbonic acid, organic carboxylic acids or phosphoric acids, such as sodium carbonate, potassium carbonate and their hydrogen carbonates - Carbonate and potassium bicarbonate, sodium acetate, potassium acetate, calcium acetate, magnesium acetate, sodium propionate, potassium propionate, calcium propionate, magnesium propionate, trisodium phosphate, tripotassium phosphate and organic nitrogen compounds, such as Cι ~ to C -alkylamine, such as methylamine, ethylamine, n-propylamine iso-propylamine, n-butylamine, 2-butylamine, tert. -Butyla- min, Cι ~ to C 4 -dialkylamines, such as dimethylamine, diethylamine, di-n-propylamine, di-iso-propylamine, di-n-butylamine, dibutylamine-2, di-tert. -butylamine, Cι ~ to C 4 ~ trialkylamines, such as trimethylamine, triethylamine, tri-n-propylamine, tri-iso-propylamine, tri-n-butylamine, tributylamine-2, tri-tert-butylamine but also amino group-containing organic hydroxy - Compounds such as monoethanolamine, diethanolamine, triethanolamine, 2-aminopropanol, 3-aminopropanol, 2-aminobutanol, 3-aminobutanol, 4-aminobutanol, 2-amino-2-methylpropanol, 2-amino-2-hydroxymethyl-l, 3 propanediol and 2-amino-2-ethyl-l, 3-propanediol. According to the invention it is also possible to use an aqueous solution which contains two or more of the aforementioned basic compounds. Aqueous solutions of sodium hydroxide and / or potassium hydroxide are preferably used.
Erfindungsgemäß werden basische Waschlösungen verwendet, deren Gewichtsanteil an der basischen Verbindung in der Regel > 0,1 Gew.-%, > 1 Gew.-%, > 2 Gew.-%, > 3 Gew.-%, > 5 Gew.-% undAccording to the invention, basic washing solutions are used whose proportion by weight of the basic compound is generally> 0.1% by weight,> 1% by weight,> 2% by weight,> 3% by weight,> 5% by weight % and
< 20 Gew.-%, < 30 Gew.-%, < 40 Gew.-%, < 50 Gew.-%, < 60 Gew.-%,<20% by weight, <30% by weight, <40% by weight, <50% by weight, <60% by weight,
< 70 Gew.-% und alle Werte dazwischen, jeweils bezogen auf das Gesamtgewicht der basischen Waschlösung, beträgt. Häufig werden basische Waschlösungen eingesetzt, deren basischen Verbindungen einen Gewichtsanteil zwischen 1 und 20 Gew.-%, oft zwischen 1,5 und 15 Gew.-% oder zwischen 2 und 10 Gew.-%, jeweils bezogen auf das Gesamtgewicht der basischen Waschlösung, aufweisen.<70% by weight and all values in between, in each case based on the total weight of the basic washing solution. Basic washing solutions are frequently used, the basic compounds of which have a proportion by weight of between 1 and 20% by weight, often between 1.5 and 15% by weight or between 2 and 10% by weight, in each case based on the total weight of the basic washing solution.
Günstig ist es, wenn die basische Waschlösung während der Reini - gung eine Temperatur von > 0 bis 150°C aufweist. Es ist jedoch auch möglich, noch höhere Temperaturen einzustellen. Aus praktischen Erwägungen werden Temperaturen zwischen 20 und 150 °C bevorzugt. Häufig weist die basische Waschlösung Temperaturen zwischen 30 und 120°C oder zwischen 40 bis 110°C auf. Die Art, wie die ba- sische Waschlösung aufgeheizt wird, ist prinzipiell unerheblich, beispielsweise können hierfür an der Trennkolonne angebrachte innen- oder außenliegende Wärmetauscher oder eine separat angebrachte elektrische Heizung verwendet werden. Als vorteilhaft hat es sich jedoch erwiesen, wenn das Aufheizen der innerhalb der Trennkolonne herabfließenden basischen Waschlösung durch Wasserdampf erfolgt, welcher am Kolonnensumpf eingeleitet wird. Dies führt auch dazu, daß die basische Waschlösung innerhalb der Trennkolonne heftig bewegt wird. Durch die Kombination der Schritte Umpumpen/Herabfließen der basischen Waschlösung und Ein- leiten von Wasserdampf erfolgt die Reinigung effektiver, was sich in der Regel auch in kürzeren Reinigungszeiten und in einer geringeren Menge der benötigten basischen Waschlösung niederschlägt. Die Wasserdampftemperatur beträgt üblicherweise > 100°C und kann Werte von > 110°C, > 120°C, > 130°C, > 140°C, > 150°C oder > 160°C aufweisen. Häufig wird der Wasserdampf in Form von unter Druck stehendem Wasserdampf eingespeist. Oft weist der Wasser - dampf einen Druck von 4 oder 16 bar auf. Der Dampfström wird so eingestellt, daß einerseits die angestrebte Reinigungstemperatur erreicht und gehalten werden kann und andererseits ein Herabflie- ßen und Umpumpen der basischen Waschlösung möglich ist.It is advantageous if the basic washing solution has a temperature of> 0 to 150 ° C during cleaning. However, it is also possible to set even higher temperatures. For practical reasons, temperatures between 20 and 150 ° C are preferred. The basic washing solution often has temperatures between 30 and 120 ° C or between 40 and 110 ° C. The way in which the basic washing solution is heated is in principle irrelevant; for example, internal or external heat exchangers attached to the separating column or a separate electric heater can be used for this. However, it has proven to be advantageous if the basic washing solution flowing down within the separating column is heated by steam which is introduced at the bottom of the column. This also leads to the basic washing solution being agitated vigorously within the separation column. By combining the steps of pumping over / flowing down the basic washing solution and introducing water vapor, cleaning is more effective, which is usually also reflected in shorter cleaning times and in a smaller amount of the basic washing solution required. The steam temperature is usually> 100 ° C and can have values of> 110 ° C,> 120 ° C,> 130 ° C,> 140 ° C,> 150 ° C or> 160 ° C. Water vapor is often fed in in the form of water vapor under pressure. The water vapor often has a pressure of 4 or 16 bar. The steam flow is adjusted so that on the one hand the desired cleaning temperature can be reached and maintained and on the other hand the basic washing solution can flow down and be pumped around.
Das Reinigen erfolgt erfindungsgemäß bei einem Kolonneninnendruck entsprechend dem äußeren Atmosphärendruck (1 bar absolut) , bei Unterdruck (< 1 bar absolut) oder bei Überdruck (> 1 bar abso- lut) , jeweils gemessen im Kolonnenkopf. Abhängig von der Art der basischen Komponente und deren Konzentration in der wässrigen Waschlösung sowie der für die Reinigung gewählten Temperatur kann die Reinigung bei Drücken von < 950 mbar, < 900 mbar, < 850 bar, < 800 mbar oder noch niedrigeren Drücken erfolgen. Häufig wird die Reinigung jedoch bei Atmosphärendruck oder bei Drücken > 1,5 bar, > 2 bar, > 3 bar, > 4 bar, > 5 bar (jeweils Absolutwerte) oder noch höheren Drücken, jeweils gemessen im Kolonnenkopf, durchgeführt. Aus wirtschaftlichen Gründen erfolgt die Reinigung jedoch häufig bei Drücken < 5 bar (absolut) . Oft erfolgt die Rei - nigung bei Atmosphärendruck. Die Menge der einzusetzenden basischen Waschlösung richtet sich nach vielen Faktoren, beispielsweise dem Volumen der Kolonne, der Art der Kolonneneinbauten, der Art der basischen Verbindung und deren Konzentration in der wässrigen Waschlösung, der Temperatur, der Umpumprate, der Art und dem Grad der Verfilmung usw.. Eine spezifische Mengenangabe ist daher im Rahmen dieser Anmeldung nicht möglich. Üblicherweise werden jedoch Volumenmengen eingesetzt, die > 0,1 Vol.-%, > 1 Vol.-%, > 3 Vol.-%, > 5 Vol.-%, > 10 Vol.-%, > 20 Vol.-%, > 30 Vol.-%, > 50 Vol.-%, > 70 Vol.-%, > 100 Vol . -% oder noch höhere Werte, jeweils bezogen auf das Gesamtinnenvolumen der Trennkolonne, betragen. Abhängig vom Verschmutzungsgrad der Kolonne kann es vorteilhaft sein, die Reinigung mehrmals mit kleinen Portionen an frischer basischer Waschlösung durchzuführen .According to the invention, cleaning takes place at an internal column pressure corresponding to the external atmospheric pressure (1 bar absolute), at negative pressure (<1 bar absolute) or at excess pressure (> 1 bar absolute), each measured in the column head. Depending on the type of basic component and its concentration in the aqueous washing solution and the temperature selected for cleaning, cleaning can be carried out at pressures of <950 mbar, <900 mbar, <850 bar, <800 mbar or even lower pressures. However, cleaning is often carried out at atmospheric pressure or at pressures> 1.5 bar,> 2 bar,> 3 bar,> 4 bar,> 5 bar (absolute values in each case) or even higher pressures, each measured in the column top. For economic reasons, however, cleaning is often carried out at pressures <5 bar (absolute). Cleaning often takes place at atmospheric pressure. The amount of the basic washing solution to be used depends on many factors, for example the volume of the column, the type of column internals, the type of basic compound and its concentration in the aqueous washing solution, the temperature, the pump rate, the type and degree of film formation, etc .. A specific quantity is therefore not possible within the scope of this application. Usually, however, volume quantities are used which are> 0.1 vol.%,> 1 vol.%,> 3 vol.%,> 5 vol.%,> 10 vol.%,> 20 vol.% ,> 30 vol.%,> 50 vol.%,> 70 vol.%,> 100 vol. -% or even higher values, based in each case on the total internal volume of the separation column. Depending on the degree of contamination of the column, it can be advantageous to carry out the cleaning several times with small portions of fresh basic washing solution.
Die erfindungsgemäße Reinigung kann prinzipiell bei auf den inneren Oberflächen anhaftenden Polymerisatfilmen oder -anbackungen erfolgen, welche aus Polymerisatpartikeln gebildet wurden, deren Homo- oder Copolymerisate aus wenigstens einem der folgenden ethylenisch ungesättigten Monomeren aufgebaut sind: Vinyl- aromatische Monomere wie Styrol, α-Methylstyrol, o-Chlorstyrol oder Vinyltoluole, Ester aus Vinylalkohol und 1 bis 18 C-Atome aufweisenden Monocarbonsäuren, wie Vinylacetat, Vinylpropionat, Vinyl-n-butyrat, Vinyllaurat und Vinylstearat, Ester aus Vorzugs - weise 3 bis 6 C-Atome aufweisenden α, ß-monoethylenisch ungesättigten Mono- und Dicarbonsäuren, wie insbesondere Acryl - säure, Methacrylsäure, Maleinsäure, Fumarsäure und Itaconsäure, mit im allgemeinen 1 bis 12, vorzugsweise 1 bis 8 und insbesondere 1 bis 4 C-Atome aufweisenden Alkanolen wie besonders Acrylsäure- und Methacrylsäuremethyl- , -ethyl-, -n-butyl-, tert.- butyl-, -iso-butyl und -2-ethylhexylester, Maleinsäuredimethyl - ester oder Maleinsäure-di-n-butylester, Nitrile α, ß-monoethylenisch ungesättigter Carbonsäuren, wie Acrylnitril sowie C4-8-konjugierte Diene wie 1,3-Butadien und Isopren. Die genannten Monomere bilden im Fall von nach der Methode der radikalisehen wässrigen Emulsions- oder Suspensionspolymerisation erzeugten wässrigen Polymerisatsystemen in der Regel die Hauptmonomeren, die, bezogen auf die Gesamtmenge der nach dem Verfahren der radikalisch initiierten wässrigen Emulsions- oder Suspensions - Polymerisation zu polymerisierenden Monomeren normalerweise einen Anteil von mehr als 50 Gew.-% auf sich vereinen.The cleaning according to the invention can in principle take place in the case of polymer films or caking adhering to the inner surfaces, which were formed from polymer particles whose homo- or copolymers are composed of at least one of the following ethylenically unsaturated monomers: vinyl-aromatic monomers such as styrene, α-methylstyrene, o-chlorostyrene or vinyl toluenes, esters of vinyl alcohol and monocarboxylic acids containing 1 to 18 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl laurate and vinyl stearate, esters of α -, ß- preferably having 3 to 6 carbon atoms monoethylenically unsaturated mono- and dicarboxylic acids, such as, in particular, acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid, with alkanols which generally have 1 to 12, preferably 1 to 8 and in particular 1 to 4, carbon atoms, such as, in particular, acrylic acid and methyl methacrylate, ethyl, n-butyl, tert-butyl, isobutyl and -2-ethylhexyl ester , Maleic acid dimethyl ester or maleic acid di-n-butyl ester, nitriles α, β-monoethylenically unsaturated carboxylic acids, such as acrylonitrile and C 4 - 8 conjugated dienes such as 1,3-butadiene and isoprene. In the case of aqueous polymer systems produced by the free-radical aqueous emulsion or suspension polymerization method, the monomers mentioned generally form the main monomers, which, based on the total amount of the monomers to be polymerized by the free-radically initiated aqueous emulsion or suspension polymerization process, normally combine a share of more than 50 wt .-%.
Folgende Monomere werden bei der radikalischen wässrigen Emulsions- oder Suspensionspolymerisation im Normalfall lediglich als modifizierende Monomere in Mengen, bezogen auf die Gesamtmenge der zu polymerisierenden Monomeren, von weniger als 50 Gew.-%, in der Regel 0,5 bis 20, vorzugsweise 1 bis 10 Gew.-% einpolymerisiert : α, ß-monoethylenisch ungesättigte Mono- und Dicarbonsäuren und deren Amide, wie z.B. Acrylsäure, Methacryl - säure, Maleinsäure, Fumarsäure, Itaconsäure, Acrylamid und Meth- acrylamid, ferner monoethylenisch ungesättigte Sulfonsäuren und deren wasserlösliche Salze, wie beispielsweise Vinylsulfonsäure sowie N-Vinylpyrrolidon.The following monomers are usually used in free-radical aqueous emulsion or suspension polymerization only as modifying monomers in amounts, based on the total amount of the monomers to be polymerized, of less than 50% by weight, generally 0.5 to 20, preferably 1 to 10% by weight polymerized: α, ß-monoethylenically unsaturated mono- and dicarboxylic acids and their amides, such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, acrylamide and methacrylamide, furthermore monoethylenically unsaturated sulfonic acids and their water-soluble salts, such as vinylsulfonic acid and N vinylpyrrolidone.
Monomere, die üblicherweise die innere Festigkeit der Verfilmungen der wässrigen Polymerisatdispersionen oder -Suspensionen erhöhen, weisen normalerweise wenigstens eine Epoxy-, Hydroxy-, N-Methylol- oder Carbonylgruppe, oder wenigstens zwei nicht konjugierte ethylenisch ungesättigte Doppelbindungen auf. Beispiele hierfür sind N-Alkylolamide von 3 bis 10 C-Atome aufweisenden α,ß— monoethylenisch ungesättigten Carbonsäuren, unter denen das N-Me- thylolacrylamid und das N-Methylolmethacrylamid ganz besonders bevorzugt sind sowie deren Ester mit 1 bis 4 C-Atomen aufweisenden Alkanolen. Daneben kommen auch zwei Vinylreste aufweisende Monomere, zwei Vinylidenreste aufweisende Monomere sowie zwei Alkenylreste aufweisende Monomere in Betracht. Besonders vorteil - haft sind dabei die Di-Ester zweiwertiger Alkohole mitα,ß-mono- ethylenisch ungesättigten Monocarbonsäuren unter denen die Acryl- und Methacrylsäure bevorzugt sind. Beispiele für derartige zwei nicht konjugierte ethylenisch ungesättigte Doppelbindungen aufweisende Monomere sind Alkylenglykoldiacrylate und -dimeth- acrylate wie Ethylenglykoldiacrylat, 1, 2-Propylenglykoldiacrylat, 1, 3-Propylenglykoldiacrylat, 1, 3-Butylenglykoldiacrylat, 1, 4-Butylenglykoldiacrylate und Ethylenglykoldimethacrylat, 1, 2-Propylenglykoldimethacrylat, 1, 3-Propylenglykoldimethacrylat, 1, 3-Butylenglykoldimethacrylat, 1, 4-Butylenglykoldimethacrylate sowie Divinylbenzol, Vinylmethacrylat, Vinylacrylat, Allylmeth- acrylat, Allylacrylat, Diallymaleat, Diallylfumarat, Methylenbis- acrylamid, Cyclopentadienylacrylat, Triallylcyanurat oder Tri- allylisocyanurat . In diesem Zusammenhang von besonderer Bedeutung sind auch die Methacrylsäure- und Acrylsäure-Ci-Cs-Hydroxyalkyl- ester wie n-Hydroxyethyl-, n-Hydroxypropyl- oder n-Hydroxybutyla- crylat und -methacrylat sowie Verbindungen, wie Diacetonacrylamid und Acetylacetoxyethylacrylat bzw. -methacrylat. Die vorgenannten Monomeren werden im Fall von ausschließlich nach der Methode der radikalischen wässrigen Suspensions- und Emulsionspolymerisation erzeugten wässrigen Polymerisatsysteme, bezogen auf die Gesamtmenge der zu polymerisierenden Monomeren, meist in Mengen von bis zu 10 Gew.-% einpolymerisiert.Monomers which usually increase the internal strength of the films of the aqueous polymer dispersions or suspensions normally have at least one epoxy, hydroxyl, N-methylol or carbonyl group, or at least two non-conjugated ethylenically unsaturated double bonds. Examples of these are N-alkylolamides of α, β-monoethylenically unsaturated carboxylic acids having 3 to 10 C atoms, among which the N-methylolacrylamide and the N-methylolmethacrylamide are very particularly preferred and their esters having 1 to 4 C atoms alkanols. In addition, two monomers having vinyl radicals, two monomers having vinylidene radicals and two monomers having alkenyl radicals are also suitable. Particularly advantageous are the di-esters of dihydric alcohols with α, β-mono-ethylenically unsaturated monocarboxylic acids, among which acrylic and methacrylic acid are preferred. Examples of such monomers having two non-conjugated ethylenically unsaturated double bonds are alkylene glycol diacrylates and dimethacrylates such as ethylene glycol diacrylate, 1, 2-propylene glycol diacrylate, 1, 3-propylene glycol diacrylate, 1, 3-butylene glycol diacrylate and 1, 4-methylene diacrylate -Propylene glycol dimethacrylate, 1, 3-propylene glycol dimethacrylate, 1, 3-butylene glycol dimethacrylate, 1, 4-butylene glycol dimethacrylate as well as divinylbenzene, vinyl methacrylate, vinyl acrylate, allyl methacrylate, allyla acrylate, dially maleate, diallyl bisyl acrylate, diallyl bisacrylate, Of particular importance in this context are the methacrylic acid and acrylic acid Ci-Cs-hydroxyalkyl esters such as n-hydroxyethyl, n-hydroxypropyl or n-hydroxybutyl acrylate and methacrylate as well as compounds such as diacetone acrylamide and acetylacetoxyethyl acrylate or - methacrylate. In the case of aqueous polymer systems produced exclusively by the free radical aqueous suspension and emulsion polymerization method, the abovementioned monomers, based on the total amount of the monomers to be polymerized, are generally polymerized in amounts of up to 10% by weight.
Vorteilhaft läßt sich das erfindungsgemäße Reinigungsverfahren bei Polymerisatverfilmungen oder -anbackungen anwenden, welche aus Polymerisatsystemen gebildet wurden, deren Homo- oder Copoly- merisate wenigstens teilweise aus einem ethylenisch ungesättigten Monomeren der folgenden Monomerenklassen aufgebaut sind: Ester aus Vinylalkohol und 1 bis 18 C-Atome aufweisenden Monocarbon- säuren, wie Vinylacetat, Vinylpropionat , Vinyl-n-butyrat , Vinyl - laurat und Vinylstearat, Ester aus vorzugsweise 3 bis 6 C-Atome aufweisenden α, ß-monoethylenisch ungesättigten Mono- und Dicarbon- säuren, wie insbesondere Acrylsäure, Methacrylsäure, Maleinsäure, Fumarsäure und Itaconsäure, mit im allgemeinen 1 bis 12, vorzugsweise 1 bis 8 und insbesondere 1 bis 4 C-Atome aufweisenden Alkanolen wie besonders Acrylsäure- und Methacrylsäuremethyl-, -ethyl-, -n-butyl-, -tert . -butyl-, -iso-butyl und -2-ethylhexyl - ester, Maleinsäuredimethylester oder Maleinsäure-di-n-butylester, α, ß-monoethylenisch ungesättigte Mono- und Dicarbonsäuren und deren Amide wie z.B. Acrylsäure, Methacrylsäure, Maleinsäure, Fumarsäure, Itaconsäure, Acrylamid und Methacrylamid, sowie ethylenisch ungesättigte Sulfonsäuren, wie beispielsweise Vinyl - sulfonsäure.The cleaning method according to the invention can advantageously be used in the case of polymer filming or caking which have been formed from polymer systems whose homo- or copolymers are at least partially composed of an ethylenically unsaturated Monomers of the following monomer classes are constructed: esters of vinyl alcohol and monocarboxylic acids having 1 to 18 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl laurate and vinyl stearate, esters of α having preferably 3 to 6 carbon atoms , ß-monoethylenically unsaturated mono- and dicarboxylic acids, such as in particular acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid, with alkanols generally having 1 to 12, preferably 1 to 8 and in particular 1 to 4 carbon atoms, such as, in particular, acrylic acid and Methacrylic acid methyl, ethyl, n-butyl, tert. -butyl-, -iso-butyl and -2-ethylhexyl esters, dimethyl maleate or di-n-butyl maleate, α, ß-monoethylenically unsaturated mono- and dicarboxylic acids and their amides such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid , Acrylamide and methacrylamide, and also ethylenically unsaturated sulfonic acids, such as vinyl sulfonic acid.
Insbesondere läßt sich das erfindungsgemäße Reinigungsverfahren bei Polymerisatverfilmungen oder -anbackungen anwenden, welche aus Polymerisatsystemen gebildet wurden, deren Homo- oder Copoly- merisate zu > 10 Gew.-%, > 20 Gew.-%, > 30 Gew.-%, > 40 Gew.-%, > 50 Gew.-%, > 60 Gew.-%, > 70 Gew.-%, > 80 Gew.-%, > 90 Gew.-% oder sogar zu 100 Gew.-%, jeweils bezogen auf die Gesamtmenge der zur Polymerisation eingesetzten ethylenisch ungesättigten Monome- ren, aus wenigstens einem ethylenisch ungesättigten Monomeren der folgenden Monomerenklassen aufgebaut sind: Ester aus vorzugsweise 3 bis 6 C-Atome aufweisenden α, ß-monoethylenisch ungesättigten Mono- und Dicarbonsäuren, wie insbesondere Acrylsäure, Methacrylsäure, Maleinsäure, Fumarsäure und Itaconsäure, mit im allge- meinen 1 bis 12, vorzugsweise 1 bis 8 und insbesondere 1 bis 4 C-Atome aufweisenden Alkanolen, wie besonders Acrylsäure- und Methacrylsäuremethyl-, -ethyl-, -n-butyl-, -tert . -butyl- , -iso- butyl und -2-ethylhexylester, Maleinsäuredimethylester oder Maleinsäure-di-n-butylester, α, ß-monoethylenisch ungesättigte Mono- und Dicarbonsäuren und deren Amide wie z.B. Acrylsäure, Methacrylsäure, Maleinsäure, Fumarsäure, Itaconsäure, Acrylamid und Methacrylamid, sowie ethylenisch ungesättigte Sulfonsäuren, wie beispielsweise Vinylsulfonsäure.In particular, the cleaning process according to the invention can be used for polymer films or caking formed from polymer systems whose homo- or copolymers are> 10% by weight,> 20% by weight,> 30% by weight,> 40 % By weight,> 50% by weight,> 60% by weight,> 70% by weight,> 80% by weight,> 90% by weight or even 100% by weight, in each case based based on the total amount of ethylenically unsaturated monomers used for the polymerization, composed of at least one ethylenically unsaturated monomer of the following monomer classes: esters of α, β-monoethylenically unsaturated mono- and dicarboxylic acids, preferably having 3 to 6 C atoms, such as in particular acrylic acid, Methacrylic acid, maleic acid, fumaric acid and itaconic acid, with alkanols generally having 1 to 12, preferably 1 to 8 and in particular 1 to 4 carbon atoms, such as, in particular, methyl, ethyl, n-butyl acrylic acid and methacrylic acid, -ter. -butyl-, -isobutyl and -2-ethylhexyl ester, maleic acid dimethyl ester or maleic acid di-n-butyl ester, α, ß-monoethylenically unsaturated mono- and dicarboxylic acids and their amides such as e.g. Acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, acrylamide and methacrylamide, and also ethylenically unsaturated sulfonic acids, such as vinylsulfonic acid.
Bei Polymerisatfilmen und -anbackungen, welche sich nicht durch das erfindungsgemäße Inkontaktbringen mit einer basischen Waschlösung auf- oder wenigstens ablösen, hat sich gezeigt, daß zumindest die mechanische Ablösung, beispielsweise mit einem Hochdruckwasserstrahl, erleichtert und so die Reinigungszeit gegen - über der reinen mechanischen Reinigung deutlich verkürzt wird. Die Zeitdauer des Inkontaktbringens ist beispielsweise stark abhängig vom Volumen und der Art der Einbauten der Trennkolonne, der Beschaffenheit und der Dicke der Polymerisatfilme und -anbackungen, der Art und der Menge der eingesetzten basischen Verbindung, deren Konzentration in wässriger Lösung, der für den Reinigungsprozeß gewählten Temperatur sowie des gewählten Drucks. Abhängig von den vorgenannten Bedingungen kann die Zeitdauer des Inkontaktbringens lediglich wenige Minuten aber auch bis zu mehreren Stunden betragen. Die optimale Zeitdauer läßt sich einfach in leicht durchzuführenden Routineversuchen ermitteln.In the case of polymer films and caking which do not dissolve or at least dissolve as a result of being brought into contact with a basic washing solution according to the invention, it has been shown that at least the mechanical detachment, for example with a high-pressure water jet, facilitates and thus the cleaning time compared to the purely mechanical cleaning is significantly shortened. The period of contacting is strongly dependent, for example, on the volume and type of internals of the separation column, the nature and thickness of the polymer films and caking, the type and amount of the basic compound used, their concentration in aqueous solution, and the one chosen for the cleaning process Temperature and the selected pressure. Depending on the aforementioned conditions, the contact time can be from a few minutes to several hours. The optimal time period can easily be determined in routine tests that are easy to carry out.
Von Bedeutung ist, daß sich nach dem vorgenannten Reinigungsverfahren auch der Trennkolonne vor- oder nachgeschaltete Wärmetauscher und/oder Filtrationseinrichtungen von deren anhaftenden Polymerisatfilmen oder -anbackungen reinigen lassen. Dies ist dadurch möglich, daß man das erfindungsgemäße Inkontaktbringen der inneren Oberflächen der Trennkolonne mit basischer Waschlösung in einfacher Weise auf das Inkontaktbringen der inneren Oberflächen der vor- oder nachgeschalteten Wärmetauscher und/oder Filtra- tionseinrichtungen, beispielsweise durch Integration dieser Apparate in die Umpumpleitung der basischen Waschlösung, ausdehnt.It is important that, after the aforementioned cleaning process, the heat exchanger and / or filtration devices upstream or downstream of the separation column can also be cleaned of their adhering polymer films or caking. This is possible by simply contacting the inner surfaces of the separation column with basic washing solution in accordance with the invention by contacting the inner surfaces of the upstream or downstream heat exchangers and / or filtration devices, for example by integrating these apparatuses into the pumping line of the basic Wash solution, expands.
Nach dem Reinigungsprozeß wird die basische Waschlösung üblicherweise vollständig aus der Trennkolonne und den eventuell vor- oder nachgeschalteten Apparaten entleert. In der Regel werden die Trennkolonne und die eventuell vor- oder nachgeschalteten Apparate anschließend solange mit vollentsalztem Wasser gespült, bis das Spülwasser einen pH-Wert < 8 oder oft < 7,5 aufweist. Nach vollständigem Entleeren der Apparate stehen diese erneut zum Ent- fernen von leichtflüchtigen Bestandteilen aus wässrigen Polymerisatsuspensionen oder Polymerisatdispersionen zur Verfügung.After the cleaning process, the basic washing solution is usually completely emptied from the separation column and any apparatuses connected upstream or downstream. As a rule, the separation column and any upstream or downstream apparatus are then rinsed with deionized water until the rinsing water has a pH <8 or often <7.5. After the devices have been completely emptied, they are again available for removing volatile constituents from aqueous polymer suspensions or polymer dispersions.
Beispiele:Examples:
1. Beispiel1st example
In einer 9,3 m hohen Trennkolonne mit einem Innendurchmesser von ca. 50 cm und insgesamt 10 sogenannten Regensiebböden wurden wässrige Polymerisatdispersionen, deren Polymerisatpartikel aus Copolymerisaten von tert . -Butylacrylat, Ethylacrylat und Methacrylsäure aufgebaut waren, durch Einleiten von 4-bar-Wasserdampf von leichtflüchtigen Bestandteilen befreit. Nach Behandlung von insgesamt ca. 240 t wässriger Polymerisatdispersionen wies die Kolonne starke Ablagerungen, Anbackungen und Koagulatausfällungen mit einer Dicke von bis zu 5 mm auf, so daß sie nur noch mit einem gegenüber der Nennleistung verminderten Durchsatz betrieben werden konnte.In a 9.3 m high separation column with an inner diameter of approx. 50 cm and a total of 10 so-called rain sieve trays, aqueous polymer dispersions, the polymer particles of which were copolymers of tert. -Butyl acrylate, ethyl acrylate and methacrylic acid were built, freed of volatile constituents by introducing 4 bar water vapor. After treating a total of approx. 240 t of aqueous polymer dispersions, the column had heavy deposits, caking and coagulum precipitates with a thickness of up to 5 mm, so that they only had to a throughput reduced compared to the nominal power could be operated.
Nach vollständiger Entleerung wurde die Trennkolonne wie folgt gereinigt.After complete emptying, the separation column was cleaned as follows.
In einem als Vorlage dienenden Rührkessel wurden 2 m3 einer 3 gew.-%igen wässrigen Natronlauge vorgelegt und auf ca. 85°C aufgeheizt. Mit einem Volumenstrom von 2 m3 pro Stunde pumpte man die ca. 85°C heiße Natronlauge über einen in der Zulaufleitung befindlichen Beutelfilter und eine Aufgabeeinrichtung auf den obersten Boden der Kolonne, so daß die heiße Natronlauge über die Regen - siebböden im Inneren der Trennkolonne herabfließen konnte. Gleichzeitig wurde der Trennkolonne am Kolonnensumpf 400 kg 4 bar-Wasserdampf pro Stunde zudosiert. Nach einer Stunde beendete man die Zuläufe und entleerte die Trennkolonne sowie die entsprechenden Zulaufleitungen vollständig. Anschließend wurde die Anlage kontinuierlich mit 600 Liter entionisiertem Wasser gespült. Am Ende hatte das Spülwasser einen pH-Wert von 7,5. Nach Entleerung der Kolonne konnten keine Ablagerungen oder2 m 3 of a 3% strength by weight aqueous sodium hydroxide solution were placed in a stirred tank serving as a template and heated to about 85.degree. With a volume flow of 2 m 3 per hour, the caustic soda solution, at approx. 85 ° C, was pumped through a bag filter in the feed line and a feed device to the top of the column, so that the hot caustic soda was poured over the rain sieve trays inside the separation column could flow down. At the same time, 400 kg of 4 bar steam per hour were metered into the separation column at the bottom of the column. After one hour, the feeds were stopped and the separation column and the corresponding feed lines were emptied completely. The system was then continuously rinsed with 600 liters of deionized water. In the end, the rinse water had a pH of 7.5. After the column had been emptied, no deposits or
Anbackungen mehr festgestellt werden. Die Trennkolonne ließ sich wieder mit 100 % ihrer Leistung betreiben.Caking can be determined more. The separation column could again be operated at 100% of its performance.
Beispielexample
In einer 13 m hohen Trennkolonne mit einem Innendurchmesser von ca. 80 cm und insgesamt 20 sogenannten Regensiebböden wurden wässrige Polymerisatdispersionen mit unterschiedlichsten Zusammensetzungen durch Einleiten von 4 bar-Wasserdampf von leicht - flüchtigen Bestandteilen befreit. Zur Herstellung der jeweiligen wässrigen Polymerisatdispersionen wurden Monomerenmischungen verwendet, die als Hauptmonomere n-Butylacrylat, Styrol, 2-Ethyl- hexylacrylat, Acrylnitril oder Vinylacetat enthielten. Nach Behandlung von insgesamt ca. 2000 t wässriger Polymerisatdisper- sionen wies die Kolonne starke Verfilmungen, Ablagerungen und Koagulatausfällungen mit einer Dicke von bis zu 5 mm auf, so daß sie nur noch mit deutlich verminderten Durchsätzen, jeweils bezogen auf die entsprechenden Nennleistungen, betrieben werden konnte.In a 13 m high separation column with an inner diameter of approx. 80 cm and a total of 20 so-called rain screen trays, volatile constituents were removed from aqueous polymer dispersions with a wide variety of compositions by introducing 4 bar water vapor. Monomer mixtures which contained n-butyl acrylate, styrene, 2-ethylhexyl acrylate, acrylonitrile or vinyl acetate as main monomers were used to prepare the respective aqueous polymer dispersions. After treating a total of approx. 2000 t of aqueous polymer dispersions, the column had severe filming, deposits and coagulum precipitates with a thickness of up to 5 mm, so that they are only operated at significantly reduced throughputs, in each case based on the corresponding nominal outputs could.
Nach vollständiger Entleerung wurde die Trennkolonne wie folgt gereinigt.After complete emptying, the separation column was cleaned as follows.
In einem als Vorlage dienenden Rührkessel wurden ca. 4000 kg einer 2 gew.-%igen wässrigen Natronlauge bei etwa 25°C vorgelegt. Mit einem Volumenstrom von ca. 12 m3 pro Stunde pumpte man die wässrige Natronlauge über einen in der Zulaufleitung befindlichen Beutelfilter und eine Aufgabeeinrichtung auf den obersten Boden der Kolonne. Dabei wurde die wässrige Natronlauge mittels eines Dampfinj ektors in der Zulaufleitung auf ca. 100°C aufgeheizt. Gleichzeitig wurden der Trennkolonne am Kolonnensumpf pro Stunde ca. 500 kg 4 bar-Wasserdampf zudosiert. Nach ca. 20 Minuten wurde der Zulauf an frischer wässriger Natronlauge beendet. Anschließend pumpte man die im Kolonnensumpf angesammelte Natronlauge über die Eintragspumpe auf den obersten Boden der Kolonne zurück, von wo sie kontinuierlich über alle Regensiebböden herab - floß. Der Volumenstrom der Umwälzung betrug ebenfalls ca. 12 m3 pro Stunde. Dabei erhöhte man innerhalb von 6 Stunden die Menge des am Kolonnensumpf eingespeisten 4 bar-Wasserdampfes sukzessive auf ca. 1700 kg pro Stunde. Nach insgesamt 6 Stunden wurde die Dampfzufuhr und das Umpumpen der wässrigen Natronlauge beendet. Anschließend entleerte man die Trennkolonne vollständig. Danach wurde die Trennkolonne mit ihren Zu- und Ableitungen fünfmal mit je 200 1 entionisiertem Wasser von der Natronlauge freigespült und jeweils vollständig entleert. Am Ende hatte das Spülwasser einen pH-Wert von 7,5. Die Trennkolonne konnte wieder mit 100 % ihrer Leistung betrieben werden. About 4000 kg of a 2% strength by weight aqueous sodium hydroxide solution at about 25 ° C. were placed in a stirred tank serving as a template. With a volume flow of approx. 12 m 3 per hour, the aqueous sodium hydroxide solution was pumped through one in the feed line Bag filter and a feed device on the top of the column. The aqueous sodium hydroxide solution was heated to about 100 ° C. in the feed line using a steam injector. At the same time, approximately 500 kg of 4 bar water vapor were metered into the separation column at the bottom of the column. The feed of fresh aqueous sodium hydroxide solution was terminated after about 20 minutes. The sodium hydroxide solution collected in the column sump was then pumped back through the feed pump to the top of the column, from where it continuously flowed down over all the trays. The volume flow of the circulation was also approximately 12 m 3 per hour. The amount of 4 bar steam fed in at the bottom of the column was gradually increased to about 1700 kg per hour within 6 hours. After a total of 6 hours, the steam supply and the pumping over of the aqueous sodium hydroxide solution were stopped. The separation column was then completely emptied. The separating column with its feed and discharge lines was then rinsed five times with 200 l of deionized water from the sodium hydroxide solution and in each case completely emptied. In the end, the rinse water had a pH of 7.5. The separation column could again be operated at 100% of its performance.

Claims

Patentansprüche claims
1. Verfahren zum Reinigen von Trennkolonnen, durch die wässrige Polymerisatdispersionen oder Polymerisatsuspensionen im1. Process for cleaning separation columns by which aqueous polymer dispersions or polymer suspensions in
Anschluß an die Polymerisationsreaktionen zum Entfernen von leichtflüchtigen Bestandteilen geleitet wurden, dadurch gekennzeichnet, daß das Reinigen ein Inkontaktbringen der inneren Oberflächen der Trennkolonnen mit einer wässrigen Lösung einer basischen Verbindung umfaßt.Subsequent to the polymerization reactions to remove volatile components, characterized in that the cleaning comprises contacting the inner surfaces of the separation columns with an aqueous solution of a basic compound.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß der Gewichtsanteil der basischen Verbindung in der wässrigen Lösung > 0 und < 70 Gew.-% beträgt.2. The method according to claim 1, characterized in that the proportion by weight of the basic compound in the aqueous solution is> 0 and <70 wt .-%.
3. Verfahren nach einem der Ansprüche 1 oder 2, dadurch gekennzeichnet, daß die wässrige Lösung einer basischen Verbindung eine Temperatur von > 0 bis 150°C aufweist.3. The method according to any one of claims 1 or 2, characterized in that the aqueous solution of a basic compound has a temperature of> 0 to 150 ° C.
4. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß das Reinigen bei einem Druck von bis zu 5 bar (absolut), gemessen im Kopf der Kolonne, erfolgt.4. The method according to any one of claims 1 to 3, characterized in that the cleaning takes place at a pressure of up to 5 bar (absolute), measured in the top of the column.
5. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekenn- zeichnet, daß als basische Verbindung Natriumhydroxid und/ oder Kaliumhydroxid eingesetzt wird.5. The method according to any one of claims 1 to 4, characterized in that sodium hydroxide and / or potassium hydroxide is used as the basic compound.
6. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß die auf den inneren Oberflächen der Trenn- kolonnen anhaftenden Polymerisatverfilmungen und -anbackungen aus wässrigen Polymerisatdispersionen und Polymerisatsuspensionen gebildet wurden, deren Homo- oder Copolymerisate wenigstens teilweise aus einem ethylenisch ungesättigten Monomeren der folgenden Monomerenklassen aufgebaut waren: Ester aus Vinylalkohol und 1 bis 18 C-Atome aufweisenden6. The method according to any one of claims 1 to 5, characterized in that the polymer films and caking adhering to the inner surfaces of the separating columns were formed from aqueous polymer dispersions and polymer suspensions, the homo- or copolymers of which at least partially consist of an ethylenically unsaturated monomer following monomer classes were built up: esters of vinyl alcohol and 1 to 18 carbon atoms
Monocarbonsäuren, Ester aus 3 bis 6 C-Atome aufweisenden α,ß- monoethylenisch ungesättigten Mono- und Dicarbonsäuren, mit 1 bis 12 C-Atome aufweisenden Alkanolen, α,ß-H_nonoethylenisch ungesättigten Mono- und Dicarbonsäuren und deren Amide sowie monoethylenisch ungesättigte Sulfonsäuren. Monocarboxylic acids, esters of 3 to 6 carbon atoms containing α, β-monoethylenically unsaturated mono- and dicarboxylic acids, with 1 to 12 carbon atoms-containing alkanols, α, β-H_nonoethylenically unsaturated mono- and dicarboxylic acids and their amides as well as monoethylenically unsaturated sulfonic acids.
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003076385A1 (en) * 2002-03-13 2003-09-18 Basf Aktiengesellschaft Method for cleaning plate columns used for rectifying liquids containing (meth)acrylic acid and/or the esters thereof
WO2004020116A1 (en) * 2002-08-09 2004-03-11 Basf Aktiengesellschaft Method for cleaning apparatus in which organic solvents containing (meth)acrylic acid have been treated and/or produced
EP1787972A3 (en) * 2001-10-09 2007-12-26 Mitsubishi Chemical Corporation Process for washing a distillation column used for the purification of (meth)acrylic acids

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112325698A (en) * 2020-09-27 2021-02-05 河南省科学院能源研究所有限公司 Industrial circulating water cooling tower cleaning device and method

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1368393A (en) * 1972-06-29 1974-09-25 Sumitomo Chemical Co Removal of deposits from surfaces of polymerization equipment
US3865628A (en) * 1973-02-26 1975-02-11 Cesco Inc Removal of polymer residue from surfaces of processing equipment
SU539065A1 (en) * 1974-09-30 1976-12-15 Предприятие П/Я А-7827 Composition for cleaning the surface of adhering low molecular weight polymer
US4904309A (en) * 1986-06-06 1990-02-27 Kanegafuchi Chemical Industry Co., Ltd. Chemical cleaning method of the interior of polymerization reactor
US5728272A (en) * 1995-09-28 1998-03-17 Basf Aktiengesellschaft Separation by rectification of unsaturated carboxylic acids from solvents

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1368393A (en) * 1972-06-29 1974-09-25 Sumitomo Chemical Co Removal of deposits from surfaces of polymerization equipment
US3865628A (en) * 1973-02-26 1975-02-11 Cesco Inc Removal of polymer residue from surfaces of processing equipment
SU539065A1 (en) * 1974-09-30 1976-12-15 Предприятие П/Я А-7827 Composition for cleaning the surface of adhering low molecular weight polymer
US4904309A (en) * 1986-06-06 1990-02-27 Kanegafuchi Chemical Industry Co., Ltd. Chemical cleaning method of the interior of polymerization reactor
US5728272A (en) * 1995-09-28 1998-03-17 Basf Aktiengesellschaft Separation by rectification of unsaturated carboxylic acids from solvents

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Section Ch Week 17729, Derwent World Patents Index; Class A35, AN 1977-51661y, XP002167113 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1787972A3 (en) * 2001-10-09 2007-12-26 Mitsubishi Chemical Corporation Process for washing a distillation column used for the purification of (meth)acrylic acids
WO2003076385A1 (en) * 2002-03-13 2003-09-18 Basf Aktiengesellschaft Method for cleaning plate columns used for rectifying liquids containing (meth)acrylic acid and/or the esters thereof
US7331354B2 (en) 2002-03-13 2008-02-19 Basf Aktiengesellschaft Cleaning of tray columns which have been used for rectificatively treating liquids comprising (meth)acrylic acid and/or esters thereof
WO2004020116A1 (en) * 2002-08-09 2004-03-11 Basf Aktiengesellschaft Method for cleaning apparatus in which organic solvents containing (meth)acrylic acid have been treated and/or produced
CN100335184C (en) * 2002-08-09 2007-09-05 巴斯福股份公司 Method for cleaning apparatus in which organic solvents containing (meth)acrylic acid have been treated and/or produced
US7287534B2 (en) 2002-08-09 2007-10-30 Basf Aktiengesellschaft Cleaning of apparatus in which meth(acrylic) acid-containing organic solvents have been treated and/or generated

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