CA1138769A - Process for stripping volatile material from aqueous latex - Google Patents
Process for stripping volatile material from aqueous latexInfo
- Publication number
- CA1138769A CA1138769A CA000329076A CA329076A CA1138769A CA 1138769 A CA1138769 A CA 1138769A CA 000329076 A CA000329076 A CA 000329076A CA 329076 A CA329076 A CA 329076A CA 1138769 A CA1138769 A CA 1138769A
- Authority
- CA
- Canada
- Prior art keywords
- tray
- latex
- column
- downcomer
- trays
- 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.)
- Expired
Links
Classifications
-
- 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
- B01D3/22—Fractionating columns in which vapour bubbles through liquid with horizontal sieve plates or grids; Construction of sieve plates or grids
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08C—TREATMENT OR CHEMICAL MODIFICATION OF RUBBERS
- C08C1/00—Treatment of rubber latex
- C08C1/02—Chemical or physical treatment of rubber latex before or during concentration
- C08C1/04—Purifying; Deproteinising
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Dispersion Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
Abstract
"IMPROVED PROCESS FOR STRIPPING VOLATILE
MATERIAL FROM AQUEOUS LATEX"
Abstract of the Disclosure An improved process is provided for stripping volatile material from an aqueous latex by a steam stripping type operation in a column equipped with trays, the latex passing downwardly through said column over the trays and steam passing upwardly through apertures in the trays and through the layer of latex on the trays, the improvement being that certain of the downcomers for passage of the latex from one tray to the next lower tray terminate at least 5 cm from the surface of the tray, each tray being equipped with weirs of at least 15 cm height. Less fouling of the column occurs using the present process
MATERIAL FROM AQUEOUS LATEX"
Abstract of the Disclosure An improved process is provided for stripping volatile material from an aqueous latex by a steam stripping type operation in a column equipped with trays, the latex passing downwardly through said column over the trays and steam passing upwardly through apertures in the trays and through the layer of latex on the trays, the improvement being that certain of the downcomers for passage of the latex from one tray to the next lower tray terminate at least 5 cm from the surface of the tray, each tray being equipped with weirs of at least 15 cm height. Less fouling of the column occurs using the present process
Description
~3~69 This invention is directed to an improved process for the removal of a volatile material from an aqueous latex.
The art is well known for the removal of a volat~le material, such as for example, styrene or acrylonitrile, from an aqueous latex by means of a steam stripping type operation whereby the aqueous latex flows downward through a column opersting at sub-atmospheric pressure containing a series of trays and steam is passed countercurrently upward through the column passing through apertures in the trays and then through the aqueous latex on each tray and the volatile material is removed together with the steam from the top of the column.
Such stripping columns are well known for the high steam consumption necessary to achieve the low residual monomer levels necessary in the latex and for the propensity to foul or plug-up, necessitating extensive cleaning and the concurrent downtime.
It is an ob~ective of our invention to provide an improved process for the removal of volatile material from an aqueous latex, said process comprising passing said latex downwardly through a column and passing steam upwardly through said column, said column being equipped with trays having perforations thereon and a downcomer attached to each tray whereby said latex flows across each tray and downward from one tray to the next lower tray by said downcomer and said steam passes through said trays and the latex thereon by said perforations, the improvement being that, in combination, at least the top one-fourth of the trays are equipped with weirs of at least 15 cm in height and the downcomers from at least the top tray to the second tray and from the second tray to the third tray terminate at least 5 cm above the surface of *
the tray to which they are supplying the latex.
According to our invention, there is provided an improved process for the removal of volatile material from an aqueous latex which process comprises passing said latex downwardly through a column and passing steam upwardly through said column, said column being equipped with from eight to fourteen trays having perforations thereon and a downcomer attached to each tray whereby said latex flows across each tray and from one tray to the next lower tray by said town-comer and said steam passes through said apertures on said trays and the latex thereon, said column being operated at a pressure at the upper end thereof of about 5 to about 20 cm of mercury, the improvement being that, in combination, at least the top one-fourth of said trays in said column are equipped with weirs of at least 15 cm and up to 25 cm height and the downcomers from at least the top tray to the second tray and from the second tray to the third tray terminate at a point at least 5 cm but not more than 15 cm above the surface of the tray to which they are supplying latex, such that there i8 at least 7.5 cm but not more than 15 cm between the lowest point of said downcomer and the uppermost point of the weir on the tray being supplied by said downcomer.
Aqueous latices which may be used in our invention are prepared by emulsion-free radical polymerization of C4-C6 conjugated diolefins and vinyl or vinylidene aromatic hydro-carbon monomers or vinyl or vinylidene nitrile group con-taining monomers. Suitable vinyl or vinylidene aromatic hydrocarbon monomers include styrene, alpha-methylstyrene, vinyl toluene and divinyl benzene. Suitable vinyl or vinyli-dene nitrile group containing monomers include acrylonitrile, --;
methacrylonitrile and ethacrylonitrile. The polymers of such latices are high molecular weight, solid, normally rubbery materials. Subsequent to the polymerization in a reactor chain, the aqueous latex containing unreacted monomers is transferred optionally to a storage tank and then to one or more flash tanks which are operated at reduced pressure and serve to flash off the unreacted volatile C4-C6 conjugated diolefin, e.g. butadiene or isoprene. The latex is then transferred to a column for removal of the last traces of the volatile conjugated diolefin and for removal of the unreacted vinyl or vinylidene monomers, especially for removal of unreacted styrene and acrylonitrile and small residual amounts of butadiene. Because this stripping column i8 operated at a slightly elevated temperature there is a tendency for the latex to coagulate and deposit on the surfaces within the column thereby causing fouling of the column. When the extent of fouling has reached the point that the latex flow rate or the stripping efficiency i8 too low, the column has to be taken out of service for cleaning.
Within the column, w~ich is a vertical elongated tubular shell, there are from eight to fourteen, preferably from ten to twelve, substantially horizontal trays spaced vertically apart and each tray i8 equipped with a weir and a downcomer. The latex is fed to the top tray by a suitable distributor system and the stripped latex is removed from the bottom tray for subsequent passage to the coagulation facilities or to facilities for storage of the latex. Each tray contains a number of perforations, usually about 0.4 to 1.3 cm diameter on a 1.5 to 4 cm triangular pitch. The weir is located at one side of the tray with the downcomer 1~3Z~
from that tray to the next lower tray being attached to the tray at a point below the weir. Diametrically opposite to the weir is where the downcomer from the next upper tray directs the flow of latex onto the tray. Preferably, each tray is equipped with a weir which is from 15 to 25 cm high.
For a better understanding of the invention, reference is now made to the drawings.
Figure 1 is a schematic outline of a tray, weir and downcomer according to the prior art.
Figure 2 is a schematic outline of a tray, weir and downcomer according to improvements in the prior art.
Figure 3 is a schematic outline of a tray, weir and downcomer as one embodiment of the present invention.
In Figure 1, 1 represents the tray, the perforations not being shown. A weir 2 controls the level of liquid on ' the tray. Attached to the tray at a point below the weir is the downcomer 3 leading to the next lower tray. A foam baffle 4 prevents excessive foam from flowing back into the downcomer 5 from the next upper tray and assists in achieving uniform distribution of the latex flow to the tray. Sump 6 provides a limited reservoir for latex flowing down the downcomer from the next upper tray. The shell of the column is generally shown at 9. The weir 1 is generally from about 2 to about 8 cm in height. The foam baffle is about 5 to about 8 cm in vertical height from the tray, although it is slanted at an angle of about 20 from the vertical. The depth of the sump 6 is shown at 7 and is generally about 20 to about 25 cm. The distance between the bottom of downcomer 5 and the bottom of sump 6, shown at 8, is about 15 to about 17 cm. The downcomer terminates at a point from ~bout 3 to about 10 cm below the ~.3E~
level of the tray.
An improved form of a tray is shown in Figure 2, in which 21 represents the tray, equipped with a weir 22 and having a downcomer 23 attached to the tray below the weir.
The downcomer from the next upper tray 24 allows the latex to flow into the sump 25. The shell of the column is generally show~ at 28. The weir 22 is at least 15 cm and up to 25 cm in height thereby providing a greater depth of latex on the tray. The depth of the sump 25 is shown at 26 and is generally about 20 to about 25 cm. The distance between the bottom of the downcomer 24 and the bottom of the sump 25, shown at 27, is about 15 to about 17 cm. The downcomer terminates at a point from about 3 to about 10 cm below the level of the tray.
Figure 3 shows one embodiment of the present invention, the tray 41 being equipped with a weir 42 and an associated downcomer 43. The downcomer 44 from the next upper tray provides for the flow of latex onto the tray. The sump 45 is as found in the prior art. The shell of the column is generally shown at 48. The depth of the sump is shown at 46 and is generally about 20 to about 25 cm. The weir 42 i8 at least 15 cm and up to 25 cm in height. The distance between the bottom of downcomer 44 and the bottom of the sump 45, shown at 47, is from about 30 to about 35 cm and the distance between the bottom of downcomer 44 and the top of weir 42 (the top of weir 42 being above the bottom of downcomer 44) is from about 7.5 to about 15 cm.
~he process of the present invention is applicable to the removal of a range of volatile materials from an aqueous latex. To illustrate an operation of the present process, there will now be described the removal of styrene 1~3~7d~9 ant butadiene from a styrene-butadiene polymer in aqueous latex. Such description does not limit the scope of the invention and only serves to illustrate the same.
A styrene-butadiene polymer was prepared by a con-ventional free radical emulsion polymerization process. The polymerization was stopped, for quality control reasons, at a total monomer conversion of about 65 to 67 per cent. The latex from the reactor thus contained a high level of unreacted butadiene and unreacted styrene. The latex was fed to the first of two flash tanks connected in series in which the pressure is finally reduced to about 20 cm of mercury and a major propor-tion of the butadiene is vaporized therein and removed.
The latex from which the majority of the unreacted butadiene had been removed was then fed to the top of a styrene stripping column. The stripping column comprised a vertical elongated tubular shell having twelve substantially horizontal trays spaced vertically apart, each tray having a plurality of apertures. Each of the trays was equipped with a weir and a downcomer communicating with said weir in order that the aqueous latex may flow downwardly from one tray to the next lower tray. The downcomer was directed to and in contact with the aqueous latex on the next lower tray so that upward flow of steam does not pass through the downcomer.
The downcomer was eccentrically located with respect to the tray to which it was attached and the downcomer on one tray was located at an essentially diametrically opposite position to the location of the downcomers of both the next upper tray and the next lower tray. The top tray of the column was equipped with a downcomer directed to the second tray from the top. The outline of the tray may be appreciated by reference ~.3 ~
to Figure 3, the downcomer 44 from the top tray being directed to the second tray from the top 41 and terminating 10 cm below the top of weir 42 which was 15 cm high. Sump 45 was 25 cm deep, the downcomer terminating 30 cm above the bottom of the sump and therefore 5 cm above the level of tray 41. The second tray from the top 41 was similarly equipped with a downcomer directed to the third tray from the top, said downcomer terminating 5 cm above the level of said third tray. The weir and sump on the third tray were of the same dimensions as - 10 those of the second tray from the top. The remaining trays of the column were as shown in Figure 2, the weir 22 being 15 cm high, the sump 25 being 25 cm deep and the downcomer 24 terminating 16.5 cm above the bottom of the sump and therefore below the level of the tray. The stripping fluid used was desuperheated steam at about 1 kg/cm2 gage supplied to the bottom of the column and passed upwardly through the column by passing through the apertures in the trays and thereby stripping the styrene, residual butadiene and any other volatile hydrocarbon impurities from the latex as it flowed over the ~rays. The steam and stripped hydrocarbons were removed from the top of the column and the s~ripped latex was removed from the bottom of the column. The pressure in the column was about 20 to about 40 cm of mercury at the lower end of the column and about 5 to about 20, preferably from about 7 to about 15, cm of mercury at the upper end of the column.
Residual styrene in the stripped latex removed from the bottom of the column was found to be from about 0.03 to about 0.07 weight per cent based on the latex.
Operating the process in this manner, it was found that the column could be used for times from 30 per cent to ~ 7 ~
50 per cent longer, without having to be shut down because of fouling, than when the prior art processes were used.
Using the process of the present invention, it was - found that when fouling of the columns did occur, it was as balls of agglomerated polymer which collected mainly on the trays and in the æump. Using the present process, the fouling on the trays finally becomes sufficient to prevent the flow of the steam through the perforations of the trays, thereby necessitating cleaning of the column. It appears that the time for the build-up of such a state of fouling is much longer than when using processes of the prior art. Accumula-tion of fouling material in the sump does not appear to be of large enough magnitude to cause blockage of the flow of latex therethrough. In the prior art processes, accumulation of fouling material in the sump caused about 50~/O of the column shut downs for cleaning and accumulation of fouling material on the tray~ accounted for about 50% of the column shut downs for cleaning.
In a similar manner, a stripping column may be used in which from three to all twelve trays may be equipped in the manner described herein and the process may be operated using such a column for further im~rovement in the operating time before a shut down becomes necessary due to fouling.
_ g _
The art is well known for the removal of a volat~le material, such as for example, styrene or acrylonitrile, from an aqueous latex by means of a steam stripping type operation whereby the aqueous latex flows downward through a column opersting at sub-atmospheric pressure containing a series of trays and steam is passed countercurrently upward through the column passing through apertures in the trays and then through the aqueous latex on each tray and the volatile material is removed together with the steam from the top of the column.
Such stripping columns are well known for the high steam consumption necessary to achieve the low residual monomer levels necessary in the latex and for the propensity to foul or plug-up, necessitating extensive cleaning and the concurrent downtime.
It is an ob~ective of our invention to provide an improved process for the removal of volatile material from an aqueous latex, said process comprising passing said latex downwardly through a column and passing steam upwardly through said column, said column being equipped with trays having perforations thereon and a downcomer attached to each tray whereby said latex flows across each tray and downward from one tray to the next lower tray by said downcomer and said steam passes through said trays and the latex thereon by said perforations, the improvement being that, in combination, at least the top one-fourth of the trays are equipped with weirs of at least 15 cm in height and the downcomers from at least the top tray to the second tray and from the second tray to the third tray terminate at least 5 cm above the surface of *
the tray to which they are supplying the latex.
According to our invention, there is provided an improved process for the removal of volatile material from an aqueous latex which process comprises passing said latex downwardly through a column and passing steam upwardly through said column, said column being equipped with from eight to fourteen trays having perforations thereon and a downcomer attached to each tray whereby said latex flows across each tray and from one tray to the next lower tray by said town-comer and said steam passes through said apertures on said trays and the latex thereon, said column being operated at a pressure at the upper end thereof of about 5 to about 20 cm of mercury, the improvement being that, in combination, at least the top one-fourth of said trays in said column are equipped with weirs of at least 15 cm and up to 25 cm height and the downcomers from at least the top tray to the second tray and from the second tray to the third tray terminate at a point at least 5 cm but not more than 15 cm above the surface of the tray to which they are supplying latex, such that there i8 at least 7.5 cm but not more than 15 cm between the lowest point of said downcomer and the uppermost point of the weir on the tray being supplied by said downcomer.
Aqueous latices which may be used in our invention are prepared by emulsion-free radical polymerization of C4-C6 conjugated diolefins and vinyl or vinylidene aromatic hydro-carbon monomers or vinyl or vinylidene nitrile group con-taining monomers. Suitable vinyl or vinylidene aromatic hydrocarbon monomers include styrene, alpha-methylstyrene, vinyl toluene and divinyl benzene. Suitable vinyl or vinyli-dene nitrile group containing monomers include acrylonitrile, --;
methacrylonitrile and ethacrylonitrile. The polymers of such latices are high molecular weight, solid, normally rubbery materials. Subsequent to the polymerization in a reactor chain, the aqueous latex containing unreacted monomers is transferred optionally to a storage tank and then to one or more flash tanks which are operated at reduced pressure and serve to flash off the unreacted volatile C4-C6 conjugated diolefin, e.g. butadiene or isoprene. The latex is then transferred to a column for removal of the last traces of the volatile conjugated diolefin and for removal of the unreacted vinyl or vinylidene monomers, especially for removal of unreacted styrene and acrylonitrile and small residual amounts of butadiene. Because this stripping column i8 operated at a slightly elevated temperature there is a tendency for the latex to coagulate and deposit on the surfaces within the column thereby causing fouling of the column. When the extent of fouling has reached the point that the latex flow rate or the stripping efficiency i8 too low, the column has to be taken out of service for cleaning.
Within the column, w~ich is a vertical elongated tubular shell, there are from eight to fourteen, preferably from ten to twelve, substantially horizontal trays spaced vertically apart and each tray i8 equipped with a weir and a downcomer. The latex is fed to the top tray by a suitable distributor system and the stripped latex is removed from the bottom tray for subsequent passage to the coagulation facilities or to facilities for storage of the latex. Each tray contains a number of perforations, usually about 0.4 to 1.3 cm diameter on a 1.5 to 4 cm triangular pitch. The weir is located at one side of the tray with the downcomer 1~3Z~
from that tray to the next lower tray being attached to the tray at a point below the weir. Diametrically opposite to the weir is where the downcomer from the next upper tray directs the flow of latex onto the tray. Preferably, each tray is equipped with a weir which is from 15 to 25 cm high.
For a better understanding of the invention, reference is now made to the drawings.
Figure 1 is a schematic outline of a tray, weir and downcomer according to the prior art.
Figure 2 is a schematic outline of a tray, weir and downcomer according to improvements in the prior art.
Figure 3 is a schematic outline of a tray, weir and downcomer as one embodiment of the present invention.
In Figure 1, 1 represents the tray, the perforations not being shown. A weir 2 controls the level of liquid on ' the tray. Attached to the tray at a point below the weir is the downcomer 3 leading to the next lower tray. A foam baffle 4 prevents excessive foam from flowing back into the downcomer 5 from the next upper tray and assists in achieving uniform distribution of the latex flow to the tray. Sump 6 provides a limited reservoir for latex flowing down the downcomer from the next upper tray. The shell of the column is generally shown at 9. The weir 1 is generally from about 2 to about 8 cm in height. The foam baffle is about 5 to about 8 cm in vertical height from the tray, although it is slanted at an angle of about 20 from the vertical. The depth of the sump 6 is shown at 7 and is generally about 20 to about 25 cm. The distance between the bottom of downcomer 5 and the bottom of sump 6, shown at 8, is about 15 to about 17 cm. The downcomer terminates at a point from ~bout 3 to about 10 cm below the ~.3E~
level of the tray.
An improved form of a tray is shown in Figure 2, in which 21 represents the tray, equipped with a weir 22 and having a downcomer 23 attached to the tray below the weir.
The downcomer from the next upper tray 24 allows the latex to flow into the sump 25. The shell of the column is generally show~ at 28. The weir 22 is at least 15 cm and up to 25 cm in height thereby providing a greater depth of latex on the tray. The depth of the sump 25 is shown at 26 and is generally about 20 to about 25 cm. The distance between the bottom of the downcomer 24 and the bottom of the sump 25, shown at 27, is about 15 to about 17 cm. The downcomer terminates at a point from about 3 to about 10 cm below the level of the tray.
Figure 3 shows one embodiment of the present invention, the tray 41 being equipped with a weir 42 and an associated downcomer 43. The downcomer 44 from the next upper tray provides for the flow of latex onto the tray. The sump 45 is as found in the prior art. The shell of the column is generally shown at 48. The depth of the sump is shown at 46 and is generally about 20 to about 25 cm. The weir 42 i8 at least 15 cm and up to 25 cm in height. The distance between the bottom of downcomer 44 and the bottom of the sump 45, shown at 47, is from about 30 to about 35 cm and the distance between the bottom of downcomer 44 and the top of weir 42 (the top of weir 42 being above the bottom of downcomer 44) is from about 7.5 to about 15 cm.
~he process of the present invention is applicable to the removal of a range of volatile materials from an aqueous latex. To illustrate an operation of the present process, there will now be described the removal of styrene 1~3~7d~9 ant butadiene from a styrene-butadiene polymer in aqueous latex. Such description does not limit the scope of the invention and only serves to illustrate the same.
A styrene-butadiene polymer was prepared by a con-ventional free radical emulsion polymerization process. The polymerization was stopped, for quality control reasons, at a total monomer conversion of about 65 to 67 per cent. The latex from the reactor thus contained a high level of unreacted butadiene and unreacted styrene. The latex was fed to the first of two flash tanks connected in series in which the pressure is finally reduced to about 20 cm of mercury and a major propor-tion of the butadiene is vaporized therein and removed.
The latex from which the majority of the unreacted butadiene had been removed was then fed to the top of a styrene stripping column. The stripping column comprised a vertical elongated tubular shell having twelve substantially horizontal trays spaced vertically apart, each tray having a plurality of apertures. Each of the trays was equipped with a weir and a downcomer communicating with said weir in order that the aqueous latex may flow downwardly from one tray to the next lower tray. The downcomer was directed to and in contact with the aqueous latex on the next lower tray so that upward flow of steam does not pass through the downcomer.
The downcomer was eccentrically located with respect to the tray to which it was attached and the downcomer on one tray was located at an essentially diametrically opposite position to the location of the downcomers of both the next upper tray and the next lower tray. The top tray of the column was equipped with a downcomer directed to the second tray from the top. The outline of the tray may be appreciated by reference ~.3 ~
to Figure 3, the downcomer 44 from the top tray being directed to the second tray from the top 41 and terminating 10 cm below the top of weir 42 which was 15 cm high. Sump 45 was 25 cm deep, the downcomer terminating 30 cm above the bottom of the sump and therefore 5 cm above the level of tray 41. The second tray from the top 41 was similarly equipped with a downcomer directed to the third tray from the top, said downcomer terminating 5 cm above the level of said third tray. The weir and sump on the third tray were of the same dimensions as - 10 those of the second tray from the top. The remaining trays of the column were as shown in Figure 2, the weir 22 being 15 cm high, the sump 25 being 25 cm deep and the downcomer 24 terminating 16.5 cm above the bottom of the sump and therefore below the level of the tray. The stripping fluid used was desuperheated steam at about 1 kg/cm2 gage supplied to the bottom of the column and passed upwardly through the column by passing through the apertures in the trays and thereby stripping the styrene, residual butadiene and any other volatile hydrocarbon impurities from the latex as it flowed over the ~rays. The steam and stripped hydrocarbons were removed from the top of the column and the s~ripped latex was removed from the bottom of the column. The pressure in the column was about 20 to about 40 cm of mercury at the lower end of the column and about 5 to about 20, preferably from about 7 to about 15, cm of mercury at the upper end of the column.
Residual styrene in the stripped latex removed from the bottom of the column was found to be from about 0.03 to about 0.07 weight per cent based on the latex.
Operating the process in this manner, it was found that the column could be used for times from 30 per cent to ~ 7 ~
50 per cent longer, without having to be shut down because of fouling, than when the prior art processes were used.
Using the process of the present invention, it was - found that when fouling of the columns did occur, it was as balls of agglomerated polymer which collected mainly on the trays and in the æump. Using the present process, the fouling on the trays finally becomes sufficient to prevent the flow of the steam through the perforations of the trays, thereby necessitating cleaning of the column. It appears that the time for the build-up of such a state of fouling is much longer than when using processes of the prior art. Accumula-tion of fouling material in the sump does not appear to be of large enough magnitude to cause blockage of the flow of latex therethrough. In the prior art processes, accumulation of fouling material in the sump caused about 50~/O of the column shut downs for cleaning and accumulation of fouling material on the tray~ accounted for about 50% of the column shut downs for cleaning.
In a similar manner, a stripping column may be used in which from three to all twelve trays may be equipped in the manner described herein and the process may be operated using such a column for further im~rovement in the operating time before a shut down becomes necessary due to fouling.
_ g _
Claims (2)
1. A column for stripping volatile material from an aqueous latex which column comprises:
a vertical elongated tubular shell, from eight to fourteen substantially horizontal trays spaced vertically apart within said shell, distributor system to feed latex to the top tray, means at the bottom of the column for removal of stripped latex, said trays being equipped with a weir, a downcomer communicating with said weir and a sump to which the downcomer from the next above tray is directed, and having a plurality of apertures, wherein at least the top one-fourth of said trays are equipped with weirs of at least 15 cm and up to 25 cm height and the downcomers from at least the top tray to the second tray and from the second tray to the third tray terminate at a point at least 5 cm but not more than 15 cm above the surface of the tray to which they are supplying latex such that there is at least 7.5 cm but not more than 15 cm between the lowest point of the downcomer and the uppermost point of the weir on the tray being supplied by the downcomer, the remaining trays being equipped with weirs of at least 15 cm and up to 25 cm height and with downcomers which terminate at a point of from about 3 cm to about 10 cm below the level of the tray being supplied by the downcomer.
a vertical elongated tubular shell, from eight to fourteen substantially horizontal trays spaced vertically apart within said shell, distributor system to feed latex to the top tray, means at the bottom of the column for removal of stripped latex, said trays being equipped with a weir, a downcomer communicating with said weir and a sump to which the downcomer from the next above tray is directed, and having a plurality of apertures, wherein at least the top one-fourth of said trays are equipped with weirs of at least 15 cm and up to 25 cm height and the downcomers from at least the top tray to the second tray and from the second tray to the third tray terminate at a point at least 5 cm but not more than 15 cm above the surface of the tray to which they are supplying latex such that there is at least 7.5 cm but not more than 15 cm between the lowest point of the downcomer and the uppermost point of the weir on the tray being supplied by the downcomer, the remaining trays being equipped with weirs of at least 15 cm and up to 25 cm height and with downcomers which terminate at a point of from about 3 cm to about 10 cm below the level of the tray being supplied by the downcomer.
2. The column of Claim 1 wherein the sump on each tray is at a point diametrically opposite to the weir for that tray and has a depth of from about 20 cm to about 25 cm.
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000329076A CA1138769A (en) | 1979-06-06 | 1979-06-06 | Process for stripping volatile material from aqueous latex |
| TR21474A TR21474A (en) | 1979-06-06 | 1979-11-04 | PROHIBITED PROCEDURE FOR STRIPPING FROM WATERLESS LATEX. |
| AU52930/79A AU524577B2 (en) | 1979-06-06 | 1979-11-19 | Monomer removal from latex |
| GB7940601A GB2051086B (en) | 1979-06-06 | 1979-11-23 | Stripping volatile material from an aqueous latex |
| MX798526U MX7333E (en) | 1979-06-06 | 1979-12-06 | IMPROVED PROCEDURE FOR THE SEPARATION OF VOLATILE MATERIAL IN AN AQUEOUS LATEX |
| ZA00796934A ZA796934B (en) | 1979-06-06 | 1979-12-20 | Stripping |
| FR7932068A FR2458559B1 (en) | 1979-06-06 | 1979-12-28 | PROCESS FOR REMOVAL OF VOLATILE SUBSTANCES FROM AN AQUEOUS LATEX |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000329076A CA1138769A (en) | 1979-06-06 | 1979-06-06 | Process for stripping volatile material from aqueous latex |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1138769A true CA1138769A (en) | 1983-01-04 |
Family
ID=4114357
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000329076A Expired CA1138769A (en) | 1979-06-06 | 1979-06-06 | Process for stripping volatile material from aqueous latex |
Country Status (7)
| Country | Link |
|---|---|
| AU (1) | AU524577B2 (en) |
| CA (1) | CA1138769A (en) |
| FR (1) | FR2458559B1 (en) |
| GB (1) | GB2051086B (en) |
| MX (1) | MX7333E (en) |
| TR (1) | TR21474A (en) |
| ZA (1) | ZA796934B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3200413A1 (en) * | 1982-01-09 | 1983-07-21 | Bayer Ag, 5090 Leverkusen | METHOD FOR DEMONOMERIZING POLYMER SLURRIES |
| DE102005013855A1 (en) * | 2005-03-24 | 2006-09-28 | Linde Ag | Mass transfer column with exchange trays |
| EP1935925A1 (en) | 2006-12-21 | 2008-06-25 | Kraton Polymers Research B.V. | Process for the preparation of an artificial latex |
| NL2001776C2 (en) | 2008-07-07 | 2010-01-11 | Kraton Polymers Us Llc | Process for the preparation of an artificial latex. |
| CN102784489B (en) * | 2012-07-02 | 2014-08-20 | 魏治中 | Gas-liquid mass transfer structure of tower tray of floating valve tower |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB802148A (en) * | 1954-07-15 | 1958-10-01 | Dunlop Rubber Co | Process and apparatus for distillation |
| FR1306650A (en) * | 1960-08-02 | 1962-10-19 | Shell Int Research | Process for separating mixtures by means of distillation or absorption |
| BE709965A (en) * | 1967-01-27 | 1968-05-30 | ||
| GB1221391A (en) * | 1969-03-11 | 1971-02-03 | Irvin Earl Nutter | Improvements in or relating to gas or vapor/liquid contact trays |
| US3647192A (en) * | 1969-03-31 | 1972-03-07 | Shell Oil Co | Gas-liquid contacting tray |
| TR20121A (en) * | 1978-04-24 | 1980-09-01 | Polysar Ltd | WORKING OF STRIPPING SUEDE |
-
1979
- 1979-06-06 CA CA000329076A patent/CA1138769A/en not_active Expired
- 1979-11-04 TR TR21474A patent/TR21474A/en unknown
- 1979-11-19 AU AU52930/79A patent/AU524577B2/en not_active Ceased
- 1979-11-23 GB GB7940601A patent/GB2051086B/en not_active Expired
- 1979-12-06 MX MX798526U patent/MX7333E/en unknown
- 1979-12-20 ZA ZA00796934A patent/ZA796934B/en unknown
- 1979-12-28 FR FR7932068A patent/FR2458559B1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| MX7333E (en) | 1988-06-16 |
| FR2458559B1 (en) | 1986-05-02 |
| AU5293079A (en) | 1980-12-11 |
| TR21474A (en) | 1984-07-04 |
| GB2051086B (en) | 1983-04-13 |
| FR2458559A1 (en) | 1981-01-02 |
| GB2051086A (en) | 1981-01-14 |
| ZA796934B (en) | 1981-07-29 |
| AU524577B2 (en) | 1982-09-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |