EP1641836A1 - Plate column for the separation of monomeric vinyl chloride (vcm) from polyvinyl chloride (pvc) in the suspension process - Google Patents

Plate column for the separation of monomeric vinyl chloride (vcm) from polyvinyl chloride (pvc) in the suspension process

Info

Publication number
EP1641836A1
EP1641836A1 EP04739520A EP04739520A EP1641836A1 EP 1641836 A1 EP1641836 A1 EP 1641836A1 EP 04739520 A EP04739520 A EP 04739520A EP 04739520 A EP04739520 A EP 04739520A EP 1641836 A1 EP1641836 A1 EP 1641836A1
Authority
EP
European Patent Office
Prior art keywords
plate column
suspension
nozzle
sprayed
plate
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Withdrawn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
EP04739520A
Other languages
German (de)
French (fr)
Inventor
Christian Bauer
Detlev Keil
Klaus Röder
Alfred Striebich
Ulrich Woike
Ingolf Mielke
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.)
ThyssenKrupp Industrial Solutions AG
Westlake Vinnolit GmbH and Co KG
Original Assignee
Uhde GmbH
Vinnolit GmbH and Co KG
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 Uhde GmbH, Vinnolit GmbH and Co KG filed Critical Uhde GmbH
Publication of EP1641836A1 publication Critical patent/EP1641836A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • C02F1/042—Prevention of deposits
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/008—Liquid distribution
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/14—Fractional distillation or use of a fractionation or rectification column
    • B01D3/16—Fractionating columns in which vapour bubbles through liquid
    • B01D3/18—Fractionating columns in which vapour bubbles through liquid with horizontal bubble plates
    • B01D3/20—Bubble caps; Risers for vapour; Discharge pipes for liquid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/34—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping with one or more auxiliary substances
    • B01D3/38—Steam distillation
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F6/00—Post-polymerisation treatments
    • C08F6/001—Removal of residual monomers by physical means
    • C08F6/003—Removal of residual monomers by physical means from polymer solutions, suspensions, dispersions or emulsions without recovery of the polymer therefrom

Definitions

  • the invention relates to a plate column used in the manufacture of PVC by the suspension process to separate the PVC from unreacted VCM.
  • the invention furthermore relates to a method of preventing the formation of or removing a deposit in'a " plate column and, finally, the invention relates to a novel use of tangential cone nozzles, especially commercially available tangential cone nozzles.
  • the monomeric starting material VCM
  • VCM the monomeric starting material
  • the reaction mixture is worked up, for example in so-called plate columns in which usually the reaction mixture is introduced at the top an. ' d flushing is carried out from the bottom by a stream of steam so that the sump material containing the polymeric product can be separated from the monomeric starting material.
  • the polymeric product is then in the form of an aqueous suspension with a solids content whereas the monomeric starting material leaves the plate column at the top with the stream of steam.
  • the reaction mixture that is to say, the suspension
  • deposits form on the inside of the column wall and on the underside of the column plates.
  • the deposited material either remains on the column wall and/or the column plate for the entire operating time (also referred to as the "service life") (and thereby impedes the stream of steam and/or interferes with temperature gradients in the plate column, for example) or becomes detached from the column wall and/or the column plate after a certain time, during which it has been exposed to the elevated temperature, and is entrained by the suspension stream.
  • the deposited material has a dark discoloration and is clearly discernible as a contaminant in the white product. Since that contamination would reduce the value of the product, the plate column has to be shut down and cleaned at relatively short intervals. That measure is laborious, means product losses and generates costs.
  • US 4 369 092 describes a device for preventing plate and/or wall deposits which is installed beneath each plate of the column and is operated with hot water. Considerable quantities of water are consumed and the injected water has to be heated in each case to the temperature of the stream of steam in order to maintain the operability of the plate column. The specified temperature must be maintained since, if the temperature exceeds or falls below that specified value, there is the risk that evaporation of water or condensation of steam, respectively, will interfere with the operation of the plate column. Furthermore, it requires a large clearance between the plates of the column so that the flushing device can be accommodated. The plate column can no longer be as densely packed and becomes less economic.
  • the object of the invention's therefore to provide an economic apparatus and a method by which the formation of deposits in a plate column for working up an aqueous PVC • suspension is reduced, a long service life of the plate column is ensured and the proportion of solids having a dark discoloration is minimised, it also being an object of the invention to give a new use for tangential cone nozzles, including commercially available tangential cone nozzles.
  • the invention relates especially to a plate column for the separation of an aqueous PVC/VCM suspension, in which the PVC/VCM suspension introduced, for example, from the top at the inlet of the plate column has hot steam passed through it, preferably in counter-current, in which the monomeric VCM leaves the suspension with the stream of steam through a line arranged in the plate column preferably at the top, and the suspension containing the polymeric PVC product collects in the sump portion of the plate column arranged at the bottom, wherein at least one line is ' so arranged that suspension from the sump portion is able to flow through it to at least one nozzle which, in accordance with this embodiment, is provided in the plate column between the inlet and the sump portion (that is to say, in the middle portion of the plate column), so that suspension from the sump portion is sprayed into the interior of the plate column and prevents deposition and/or the formation of undesirable deposits therein.
  • the invention also relates to a method for the removal and/or for the prevention of the formation of a deposit in the interior of a plate column for the separation of an aqueous PVC/VCM suspension, in which method suspension from the sump portion of the plate column is sprayed by at least one nozzle into the interior of the plate column in such a manner that it serves therein to clean the sprayed areas and/or to prevent deposits.
  • the invention relates to the use of cone nozzles, especially commercially available tangential cone nozzles, for spraying suspension from the sump portion of a plate column.
  • cone nozzles may be obtained, for example, from Lechler, D-72544 Metzingen, as type series 422.
  • the line(s) conveying suspension from the sump portion of the plate column to the nozzle(s) may be connected directly to the sump portion and/or to a line leading away from the sump portion.
  • At least one tangential full cone nozzle is used.
  • the nozzles have, for example, a jet angle of 90 - 140°, especially about 120°.
  • the suspension is sprayed at a coverage density of 100 - 500 l/(m 2 min), preferably 250 - 350 l/(m 2 min) and especially about 300 l/(m 2 min).
  • the suspension from the sump portion is sprayed against the lower face of at least one plate of the plate column and/or against the inside wall.
  • at least the lowermost plate or the inside wall especially below the lowermost plate is sprayed.
  • the suspension from the surrip portion is sprayed against the lower faces of a plurality of plates of the plate column and/or against the inside wall.
  • the suspension from the sump portion of the plate column is sprayed against the lower faces of all the plates of the plate column and/or against the inside wall.
  • the suspension from the sump portion of the plate column is sprayed continuously into the middle portion of the plate column.
  • the suspension is sprayed with a flushing time in the range of 15 - 120 seconds and with a flushing interval of 15 - 90 minutes.
  • the suspension line to the nozzle(s) branches off the feed line to the next process stage on the pressure side of the suspension pump.
  • the system is so configured that a pressure drop sufficient to maintain the flow rate required to obtain the coverage density, according to the characteristic of the nozzle type employed, still occurs at the nozzle(s).
  • a tangential full cone nozzle having a jet angle of 120° and a smallest diameter of 8 mm was installed 150 mm below the lowermost plate in a plate column having a column diameter of 300 mm.
  • Suspension coming from a line that conveys the PVC-containing suspension away from the sump portion of the plate column was continuously sprayed from that nozzle at a pressure of 1.6 bar, that is to say, at a flow rate of about 22 l/min, against the underside of the lowermost plate of the plate column and against a portion of the inside wall of the plate column.
  • the tangential full cone nozzle for removing and preventing deposits was operated continuously, and the suspension used for the purpose was taken from a line that conveys the medium out of the sump.
  • the pressure, which was relieved at the nozzle, was about 1.6 bar, which corresponds to a sprayed suspension volume of about 22 l/min.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Chemistry (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Hydrology & Water Resources (AREA)
  • Dispersion Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

Abstract

The invention relates to a plate column used in the manufacture of PVC by the suspension process to separate the PVC from unreacted VCM. The invention furthermore relates to a method of preventing the formation of a deposit in a plate column and the invention also relates to a novel use of commercially available tangential cone nozzles. To clean the interior of the plate column and/or to prevent the formation of deposits, suspension from the sump portion of the plate column is sprayed into the middle portion thereof.

Description

Description
Plate column for the separation of monome c vinyl chloride (VCM) from polyvinyl chloride (PVC) in the suspension process
The invention relates to a plate column used in the manufacture of PVC by the suspension process to separate the PVC from unreacted VCM. The invention furthermore relates to a method of preventing the formation of or removing a deposit in'a "plate column and, finally, the invention relates to a novel use of tangential cone nozzles, especially commercially available tangential cone nozzles.
In suspension processes for the manufacture of PVC, the monomeric starting material, VCM, is polymerised in the presence of water, initiator(s), dispersing agent(s) and other additives, usually in at least one pressure vessel. After reaction, the reaction mixture is worked up, for example in so-called plate columns in which usually the reaction mixture is introduced at the top an.'d flushing is carried out from the bottom by a stream of steam so that the sump material containing the polymeric product can be separated from the monomeric starting material. In the sump material, the polymeric product is then in the form of an aqueous suspension with a solids content whereas the monomeric starting material leaves the plate column at the top with the stream of steam.
In the plate columns, in which the reaction mixture, that is to say, the suspension, is treated with steam, deposits form on the inside of the column wall and on the underside of the column plates. The deposited material either remains on the column wall and/or the column plate for the entire operating time (also referred to as the "service life") (and thereby impedes the stream of steam and/or interferes with temperature gradients in the plate column, for example) or becomes detached from the column wall and/or the column plate after a certain time, during which it has been exposed to the elevated temperature, and is entrained by the suspension stream. Owing to the effect of heat the deposited material has a dark discoloration and is clearly discernible as a contaminant in the white product. Since that contamination would reduce the value of the product, the plate column has to be shut down and cleaned at relatively short intervals. That measure is laborious, means product losses and generates costs.
US 4 369 092 describes a device for preventing plate and/or wall deposits which is installed beneath each plate of the column and is operated with hot water. Considerable quantities of water are consumed and the injected water has to be heated in each case to the temperature of the stream of steam in order to maintain the operability of the plate column. The specified temperature must be maintained since, if the temperature exceeds or falls below that specified value, there is the risk that evaporation of water or condensation of steam, respectively, will interfere with the operation of the plate column. Furthermore, it requires a large clearance between the plates of the column so that the flushing device can be accommodated. The plate column can no longer be as densely packed and becomes less economic.
The main disadvantage of the known cleaning device, apart from increased water consumption, the space required for installation of the water-heating system and the energy consumption of the latter, is the problem that the flushing water added has to be separated from the solids again.
The object of the invention's therefore to provide an economic apparatus and a method by which the formation of deposits in a plate column for working up an aqueous PVC • suspension is reduced, a long service life of the plate column is ensured and the proportion of solids having a dark discoloration is minimised, it also being an object of the invention to give a new use for tangential cone nozzles, including commercially available tangential cone nozzles.
That object is achieved by the subject-matter of the main claim and of the two other independent claims and by the advantageous embodiments disclosed in the subsidiary claims and the description.
The invention relates especially to a plate column for the separation of an aqueous PVC/VCM suspension, in which the PVC/VCM suspension introduced, for example, from the top at the inlet of the plate column has hot steam passed through it, preferably in counter-current, in which the monomeric VCM leaves the suspension with the stream of steam through a line arranged in the plate column preferably at the top, and the suspension containing the polymeric PVC product collects in the sump portion of the plate column arranged at the bottom, wherein at least one line is'so arranged that suspension from the sump portion is able to flow through it to at least one nozzle which, in accordance with this embodiment, is provided in the plate column between the inlet and the sump portion (that is to say, in the middle portion of the plate column), so that suspension from the sump portion is sprayed into the interior of the plate column and prevents deposition and/or the formation of undesirable deposits therein.
The invention also relates to a method for the removal and/or for the prevention of the formation of a deposit in the interior of a plate column for the separation of an aqueous PVC/VCM suspension, in which method suspension from the sump portion of the plate column is sprayed by at least one nozzle into the interior of the plate column in such a manner that it serves therein to clean the sprayed areas and/or to prevent deposits.
Finally, the invention relates to the use of cone nozzles, especially commercially available tangential cone nozzles, for spraying suspension from the sump portion of a plate column. Such cone nozzles may be obtained, for example, from Lechler, D-72544 Metzingen, as type series 422.
The successful use of tangential cone nozzles, and especially the use of tangential full cone nozzles, when cleaning by spraying a suspension containing solids is surprisingly possible here without the nozzle becoming clogged by the solids content, despite the fine droplets formed by the nozzle. Even after prolonged operation, there was no abrasion by the solids content of the suspension.
According to the invention, the line(s) conveying suspension from the sump portion of the plate column to the nozzle(s) may be connected directly to the sump portion and/or to a line leading away from the sump portion.
Advantageously, at least one tangential full cone nozzle is used. Especially preferred is the use of at least one tangential full cone nozzle having a front, i.e. smallest, diameter of from 5 to 20 mm, preferably from 7 to 9 mm, and especially of about 8 mm.
The nozzles have, for example, a jet angle of 90 - 140°, especially about 120°.
It is also possible -to use 2, 3, 4 or more nozzles arranged, for example, almost in one plane or in several planes, beneath one plate or beneath several plates.
Advantageously, the suspension is sprayed at a coverage density of 100 - 500 l/(m2 min), preferably 250 - 350 l/(m2 min) and especially about 300 l/(m2 min).
According to one embodiment of the invention, the suspension from the sump portion is sprayed against the lower face of at least one plate of the plate column and/or against the inside wall. Preferably, at least the lowermost plate or the inside wall especially below the lowermost plate is sprayed.
According to another embodiment, the suspension from the surrip portion is sprayed against the lower faces of a plurality of plates of the plate column and/or against the inside wall.
According to a further embodiment, the suspension from the sump portion of the plate column is sprayed against the lower faces of all the plates of the plate column and/or against the inside wall.
According to one embodiment of the invention, the suspension from the sump portion of the plate column is sprayed continuously into the middle portion of the plate column.
According to one embodiment of the invention, the suspension is sprayed with a flushing time in the range of 15 - 120 seconds and with a flushing interval of 15 - 90 minutes.
According to the invention, the suspension line to the nozzle(s) branches off the feed line to the next process stage on the pressure side of the suspension pump. The system is so configured that a pressure drop sufficient to maintain the flow rate required to obtain the coverage density, according to the characteristic of the nozzle type employed, still occurs at the nozzle(s).
Implementation Example:
A tangential full cone nozzle having a jet angle of 120° and a smallest diameter of 8 mm was installed 150 mm below the lowermost plate in a plate column having a column diameter of 300 mm. Suspension coming from a line that conveys the PVC-containing suspension away from the sump portion of the plate column was continuously sprayed from that nozzle at a pressure of 1.6 bar, that is to say, at a flow rate of about 22 l/min, against the underside of the lowermost plate of the plate column and against a portion of the inside wall of the plate column.
Further data of the system are: perforation ratio of the plate: 1.8 % weir height: 120 mm number of downcomers 3 diameter of downcomers 44.3 mm diameter of holes 2.5 mm width of peripheral gap 1 mm
The tangential full cone nozzle for removing and preventing deposits was operated continuously, and the suspension used for the purpose was taken from a line that conveys the medium out of the sump. The pressure, which was relieved at the nozzle, was about 1.6 bar, which corresponds to a sprayed suspension volume of about 22 l/min.
After a test period of 24 hours, no deposits were to be observed on the wall or on the underside of the lowermost plate where, however, they occurred on a massive scale without the use of said continuous cleaning device under otherwise identical conditions. The full cone nozzle used to spray the suspension also did not clog, nor did it show any sign of abrasion by the solids content of the suspension.

Claims

Patent Claims
1. A plate column for the separation of an aqueous PVC/VCM suspension, in which the PVC/VCM suspension is treated with steam, the VCM is separated off via a line arranged in the plate column and the suspension containing the PVC product collects in the sump portion of the plate column, wherein at least one line is so arranged that suspension from the sump portion is able to flow through it to at least one nozzle which is so arranged that suspension from the sump portion can be sprayed into the interior of the plate column in order to remove and/or prevent deposits therein.
2. A plate column according to claim 1 , in which at least one nozzle is a tangential cone nozzle.
3. A plate column according to either claim 1 or claim 2, in which the nozzle has a smallest diameter of from 5 to 20 mm.
4. A plate column according to any one of the preceding claims, in which at least one nozzle is arranged directly beneath at least one plate of the plate column.
5. A plate column according to any one of the preceding claims, in which a pump is integrated and/or connected in at least the line through which suspension is able to flow from the sump portion to at least one nozzle.
6. A method of removing and/or preventing the formation of a deposit in the interior of a plate column for the separation of an aqueous PVCΛ/CM suspension, in which method suspension from the sump portion of the plate column is sprayed into the interior of the plate column through at least one nozzle in such a manner that it serves therein to clean the sprayed areas and/or to prevent deposits.
7. A method according to claim 6, in which the suspension is sprayed at such a rate that the sprayed surface receives 100 - 500 l/(m2 min).
8. A method according to either claim 6 or claim 7, in which the suspension from the sump portion of the plate column is sprayed continuously into the interior of the plate column.
9. A method according to either claim 6 or claim 7, in which the suspension is sprayed with a flushing time in the range of 15 - 120 seconds and with a flushing interval of 15 - 90 minutes.
10. A method according to any one of claims 6 to 10, in which the nozzle is a tangential cone nozzle.
11. The use of commercially available tangential full cone nozzles for spraying suspension from the sump portion of a plate column.
EP04739520A 2003-07-03 2004-06-02 Plate column for the separation of monomeric vinyl chloride (vcm) from polyvinyl chloride (pvc) in the suspension process Withdrawn EP1641836A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10330105 2003-07-03
PCT/EP2004/005940 WO2005003187A1 (en) 2003-07-03 2004-06-02 Plate column for the separation of monomeric vinyl chloride (vcm) from polyvinyl chloride (pvc) in the suspension process

Publications (1)

Publication Number Publication Date
EP1641836A1 true EP1641836A1 (en) 2006-04-05

Family

ID=33559854

Family Applications (1)

Application Number Title Priority Date Filing Date
EP04739520A Withdrawn EP1641836A1 (en) 2003-07-03 2004-06-02 Plate column for the separation of monomeric vinyl chloride (vcm) from polyvinyl chloride (pvc) in the suspension process

Country Status (2)

Country Link
EP (1) EP1641836A1 (en)
WO (1) WO2005003187A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TW201823189A (en) * 2011-12-06 2018-07-01 比利時商首威公司 Process for the manufacture of vinyl chloride monomer (vcm) and of polyvinyl chloride (pvc)

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NZ184661A (en) * 1976-07-27 1979-08-31 Ici Australia Ltd Removing monomer from vinyl chloride polymers
GB1593377A (en) * 1976-12-10 1981-07-15 Emi Ltd Security document and system
DE2759097A1 (en) * 1977-12-30 1979-07-12 Norsk Hydro As METHOD FOR REMOVING VINYL CHLORIDE FROM POLYVINYL CHLORIDE DISPERSIONS AND A COLUMN FOR CARRYING OUT THE METHOD
US6277954B2 (en) * 1999-09-14 2001-08-21 Kaneka Corporation Method of stripping for latex of vinyl chloride paste resin, stripping apparatus, and vinyl chloride paste resin latex having low concentration of residual monomer

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2005003187A1 *

Also Published As

Publication number Publication date
WO2005003187A1 (en) 2005-01-13

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