CA1270354A - Method for improving brown stock washer efficiency - Google Patents
Method for improving brown stock washer efficiencyInfo
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- CA1270354A CA1270354A CA000493656A CA493656A CA1270354A CA 1270354 A CA1270354 A CA 1270354A CA 000493656 A CA000493656 A CA 000493656A CA 493656 A CA493656 A CA 493656A CA 1270354 A CA1270354 A CA 1270354A
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- pulp
- black liquor
- washing
- polymer
- pad
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Abstract
TITLE OF THE INVENTION
A METHOD FOR IMPROVING BROWN STOCK WASHER EFFICIENCY
ABSTRACT OF THE DISCLOSURE
The instant invention is directed to an improved process for separating black liquor from pulp comprising washing a pulp pad with a washing medium and applying vacuum to said pad, after contacting the pulp and/or black liquor with an acrylamide/dimethyldiallylammonium chloride polymer or homologue thereof, thereby more efficiently separating said black liquor from said pulp pad.
A METHOD FOR IMPROVING BROWN STOCK WASHER EFFICIENCY
ABSTRACT OF THE DISCLOSURE
The instant invention is directed to an improved process for separating black liquor from pulp comprising washing a pulp pad with a washing medium and applying vacuum to said pad, after contacting the pulp and/or black liquor with an acrylamide/dimethyldiallylammonium chloride polymer or homologue thereof, thereby more efficiently separating said black liquor from said pulp pad.
Description
~L~7~3~54 TITLE OF THE INVENTION
A METHOD FOR IMPROVING BROWN STOCK WASHER EFFICIENCY
BACKGROUND OF THE INVENTION
This invention relates to an improved method of pulp washing, and to products useful as pulp washing aids.
More particularly, this invention relates to an improved method of separating "black liquor" from a cellulosic fiber mat or pad (i.e., pulp mat or pulp pad) comprising adding polymers of dimethyldiallyl-ammonium chloride and acrylamide to a brown stock slurry prior to water washing or to the wash water itself. Black liquor is the liquid fraction of a brown stock slurry after the cooking or digestion of wood chips. Thus, brown stock comprises cellulosic fibers, which form a pulp pad, and black liquor.~
In the production of paper by the sulfate process, bark and chipped wood are treated with an alkaline aqueous liquid to free cellulose ~ibers.
This treatment also removes certain organic ...
. , :., : , ' .- '~' :
'' .. : `:
03~
1529M/0817A ~ 2 - C-1396 contaminants from the wood, including lignin.
Typically, the chips are cooked in a 10 percent, by weight, solution of sodium hydroxide which contains about 20 mole percent of sodium sulfide. This reaction is usually conducted at temperatures of approximately 170 to 180C for a period of time ranging between 1 and 3 hours.
The resultant organic residues and cellulosic fibers are removed from the chips hy water washin~. Thus, the wash water contains dissolved lignin, emulsified soaps, other organic ingredients, and substantial amounts of inorganic salts and bases. This wash water is referred to as black liquor.
It is common practice in large mills to recover the inorganic components of the li~uor and to use the organic portion as fuel. As produced, the black liquor will usually contain about 12 percent by weight of solid material. Before the liquor can be used as fuel and the inorganic components recovered, it is necessary that the material be concentrated, usually to a solids content of about 45 percent by weight or higher. The concentrating of the black liquor is usually conducted in multiple-effect evaporators.
The black liquor itself will show variations in composition from mill to mill. However, in most instances, inorganic carbonates, sulfides, sulfites, sulfates and silica are present, as well as organic sulfur compounds.
Pulp mats or pads are washed to separate dissolved organic and inorganic materials (i.e., components of black liquor) from the pulp. These dissolved materials are undesirable because they .~, .
. ' ''' ~ " .
~Z7~5~
interfere with bleaching of the pulp and pose pollution problems in effluent treatment systems.
The primary objective of brown stock washing is the separation of black liquor from the pulp mat or pad. It is especially desirable to accomplish this primary objective while minimizing water consumption. Efficient separation of black liquor from pulp helps to offset rising costs of production;
for example, greater removal of organics from pulp means that more of these organics are available as h~at sources and lower water consumption lowers black liquor evaporation costs. Also, more efficient washing produces a cleaner pulp mat, which reduces bleaching costs.
Typically, rotary vacuum drum washers are used for the washing of pulp mats or pads. Wash water is sprayed onto a pad of fibers as the pad forms on the surface of the rotary drum. The black liquor and wash water is "pulledi' through the pad by vacuum, thus effectuating the separation.
Oftentimes, countercurrent multistage washers are used. The instant invention includes the use of washing aids at any stage of a multistage washing process.
Though the use of high molecular weight polyacrylamide polymers as brown stock washing aids has been suggested (see "The Detrimental Effect of Channeling on the Effectiveness of Displacement Washing of Pads of Wood Pulp Fibers and a Technique for its Reduction", by P. F. Lee of the Weyerhaeser Technology Center, Tacomal Washington) additives have not generally been used to improve the efficiency of brown stock washers. Thus, higher solids removal has been obtained by additional washingO The .. .:
'~
' ~; ' .
7()354 disadvantage of this mode of operation is that extensive washing dilutes the resulting liquor. Weak black liquor streams increase evaporation costs and may require the use of storage tanks and~or the shipment of the liquor from the generating site.
Further, extensive washing may not be a viable option where water usage is restricted or where the mill water circ~it is a "closed loop". For these reasons, the instant invention, which results in equivalent removal of dissolved solids from a fiber mat at lower water consumption or in greater removal of contaminants at equivalent consumption when compared to prior art washing methods, is a notable advance in the art.
As noted earlier, the Lee reference suggests the use of high molecular weight polyacrylamides as washing aids. The inventor has found these polymers to be unsuitable agents for the separation of black liquor from pulp mats or pads, because they tend to restrict flow of a washing medium through a pulp mat or pad too greatly. Thus, washing times become excessive, a result which makes the use of Lee's polyacrylamides impracticable.
It is necessary not only to improve washing efficiency, but to do so without greatly increasing washing time. Thus, a suitable additive improves washing efficiency without significantly lncreasing washing time.
The instant met~od constitutes a way of improving pulp washing efficiency without greatly increasing washing time. As a thick cellulosic fiber mat is formed on the drum surface of a rotary-vacuum brown stock washer, the black liquor contained within the mat is more effectively displaced by using an .
3L~7~3~
acrylamide/dimethyldiallylammonium chloride polymer as a separation aid. Thus, less wash ~ater is required for separation of the black l:iquor from the mat than is required when no polymer is added.
Alternatively, greater removal of contaminants for the same amount of wash water can be realized utilizing the polymers of the instant invention.
DESCRIPTION OF THE INVENTION
The instant invention relates to a method of separating black liquor from a pulp pad comprising:
(a) contacting the pulp pad and/or black liquor with a polymer selected from the group consisting of polymers made from:
(i) one or more cationic monomers selected from the group consisting of dimethyldiallylammonium chloride, dimethyldiallyl ammonium bromide, diethyldiallylammonium chloride and diethyldially a~,monium bromide, and ~ii) one or more nonionic monomers selected from the group consisting of acrylamide and methacrylamide, wherein the total ratio of cationic monomer to nonionic monomer is 95:5 to 5:95, by weight, and wherein said polymer is contacted at a dosage of greater than 0.1 ppm, based on the weight of the black liquor/pulp stream being treated;
(b) washing the pulp pad with a washing medium;
and (c) applying vacuum to said pad.
More particularly, the instant invention relates to an improved process for separating black liquor from pulp. Thusl in a process for separating 3~
a black liquor/pulp stream into black liguor and pulp components comprising washing a pulp mat or pad with a washing medium and applying vacuum to said pulp mat or pad, thereby dissplacing black liquor from said pad, the instant improvement comprises contacting the pulp and/or black liquor with an acrylamide/dimethyl-diallylammonium chloride polymer or homologue thereof, prior to or during said step of washing and prior to said step of applying vacuum, thereby more efficiently separating said black liquor from said pad.
The polymer can be added directly to the pulp/black liquor stream, i.e a brown stock stream, or it can be added to the washing medium. Washing mediums generally comprise water, or solutions of water and black liquor. ~he ratio of acrylamide to dimethyldiall~lammonium chloride in the polymer may range from 5:95 to 95:5, by weight, and the polymer should be added at a dosage of at least 0.1 ppM, based on the weigh~ of the black liquor/pulp stream (i.e. brown stock stream) being treated. If added to a brown stock stream, the instant polymers contact the pulp/black liquor before the washing step. If added to the washing medium, the instant polymers contact the pulp/black liquor during washing.
The most preferred polymers suitable for use in this invention are polymers of acrylamide and dimethyldiallylammonium chloride (DMDAAC). However, homologues of the DMDAAC and acrylamide polymers are also preferred. Homologues, as used herein, are defined as polymers which are structurally and functionally similar to polymers of DMDAAC and acrylamide. ~xamples of homologues include, but are not limited to, polymers of diethyldiallylammonium chloride ~DEDAAC) and acrylamide, DEDAAC and ~7(~
methacrylamide, DMDAAC and methacrylamide, dimethyldiallyl ammonium bromide (DMDAAB) and acrylamide, DMDAAB and methacrylamider diethyldiallyl ammonium bromide (DEDAAB) and acrylamide, and DEDAAB
and methacrylamide.
More generally, polymers suitable for use as black liquor washing aids comprise those made from one or more cationic monomers selected from the group consisting of DMDAAC, DMDAAB, DEDAAB and DEDAAC and from one or more nonionic polymers selected from the group consisting of acrylamide and methacrylamide.
The ratio of monomers used to produce the polymers of this invention may range from 95:5 to 5:95, on a cationic:nonionic weight basis. The preferred monomer ratio range is 25:75 to 75:25, by weight, on a cationic nonionic basis. The most preferred polymers are polymers prepared using 4S:55 to 55:45 monomer weight ratios, on a cationic:nonionic basis.
The molecular weight of the polymers used in the instant invention is not critical. However, polymers having molecular weights in excess of 100,000, as measured by light scattering techniques, are preferred.
The polymers of the instant invention can be added either to the washing medium or to a pulp/black liquor stream (i.e. brown stock). For example, the polymer can be added directly to a brown stock washer feed stream or the polymer can be added to the wash water or other washing medium. It is preferred to add the polymer directly to the brown stock, i.e. to the black liquor/pulp stream, in a manner which provides thorough mixing. The brown stock/polymer admixture can then be treated usin~ a rotary vacuum drum filter or other washing apparatus known in the ~.~7~35~
art. The polymer increases the separation of the cellulosic pulp mat from the black liquor via vacuum filtration. This improved separation lowers evaporation costs of the black liquor while increasing the solids content of the separated black liquor. The dosage of the polymer should be in excess of 0.1 ppm, based on the weight of the black liquor/pulp stream being treated. The preferred dosage range is from 1 ppm to 50 ppm. The most preferred dosage ranges from 1.0 ppm to 10 ppm. This dosage has shown a reduction of lG to 15~ in water consumption at a brown stock washing operation, without greatly increasing washing times.
If multistage washing is used, the polymers of the instant invention can be used at any stage without departing from the spirit of this invention.
In such instances, the wasing medium initially comprises water. Since this wash water is reused, it generally comprises a solution of water and black liquor at later sta~es.
EXAMPLES
rrhe following examples illustrate the present invention in greater detail. It should be understood, however, that the invention is not in any way limited by these examples.
In the following examples, a brown stock solution of 0.5~ consistency was used. Thus, the solution contained .5 g pulp/100 g black liquor.
This stock solution was obtained from an operating paper mill.
.
. . .. .
.
,~ ..
1529M/0~17A - 9 - C-1396 A 1500 ml aliquot of the 0.5~ brown stock was placed in a beaker on a hot plate. The temperature was kept constant at 140F, to simulate plant operatinq temperatures. A magnetic stirrer agitated the stock solution uniformly. 125 ml aliquots were withdrawn from the 1500 ml aliquot.
Polymer was then added to each smaller aliq~ot in the dosage indicated for each example based on the weight 1~ of brown stock. Each smaller aliquot containing the polymer was then cascaded 8 times from its beaker to another beaker to simulate mixing in the piping of an operating mill. This solution was added to a Buckner fun~el. The funnel was attached to a vacuum pump with 26.5 inches of water vacuum. The base of the funnel was attached to a graduated burette. The time needed to drain 0, 25, 75, and 110 ml of filtrate was recorded. The Buckner funnel used was 11 cm, in diameter, and Wo. 2 ~hatmann filter paper was used. The results of Examples 1-10 are shown in Table I. In this table, DMDAAC means dimethyldiallyl ammonium chloride, AM means acrylamide, META~S means methacryloyloxyethyl trimethyl ammonium methosulfate, AMPAM means amino methylated polyacrylamide and P~M
means polyacrylamide. Table I also shows the approximate molecular weights of the polymers tested.
Examples 1 through 10 screen polymers based on drainage times. An excessive drainage time indicates that use of the related polymer is impractical, because it would greatly lengthen washing time.
.. . .
: : ' 1 5 2 9M /0 8 1 7 A - 10 - C ~1 3 96 TABLE I
Total Approximate Time to Drain Example Polymer Monomer Molecular Dosage (seconds) Ho. Type Ratio Weiqht ~ pm) Z5 ml ~-75-ml----rTU ml l* None N/A N/A ~/A 2.5 8.3 12.8
A METHOD FOR IMPROVING BROWN STOCK WASHER EFFICIENCY
BACKGROUND OF THE INVENTION
This invention relates to an improved method of pulp washing, and to products useful as pulp washing aids.
More particularly, this invention relates to an improved method of separating "black liquor" from a cellulosic fiber mat or pad (i.e., pulp mat or pulp pad) comprising adding polymers of dimethyldiallyl-ammonium chloride and acrylamide to a brown stock slurry prior to water washing or to the wash water itself. Black liquor is the liquid fraction of a brown stock slurry after the cooking or digestion of wood chips. Thus, brown stock comprises cellulosic fibers, which form a pulp pad, and black liquor.~
In the production of paper by the sulfate process, bark and chipped wood are treated with an alkaline aqueous liquid to free cellulose ~ibers.
This treatment also removes certain organic ...
. , :., : , ' .- '~' :
'' .. : `:
03~
1529M/0817A ~ 2 - C-1396 contaminants from the wood, including lignin.
Typically, the chips are cooked in a 10 percent, by weight, solution of sodium hydroxide which contains about 20 mole percent of sodium sulfide. This reaction is usually conducted at temperatures of approximately 170 to 180C for a period of time ranging between 1 and 3 hours.
The resultant organic residues and cellulosic fibers are removed from the chips hy water washin~. Thus, the wash water contains dissolved lignin, emulsified soaps, other organic ingredients, and substantial amounts of inorganic salts and bases. This wash water is referred to as black liquor.
It is common practice in large mills to recover the inorganic components of the li~uor and to use the organic portion as fuel. As produced, the black liquor will usually contain about 12 percent by weight of solid material. Before the liquor can be used as fuel and the inorganic components recovered, it is necessary that the material be concentrated, usually to a solids content of about 45 percent by weight or higher. The concentrating of the black liquor is usually conducted in multiple-effect evaporators.
The black liquor itself will show variations in composition from mill to mill. However, in most instances, inorganic carbonates, sulfides, sulfites, sulfates and silica are present, as well as organic sulfur compounds.
Pulp mats or pads are washed to separate dissolved organic and inorganic materials (i.e., components of black liquor) from the pulp. These dissolved materials are undesirable because they .~, .
. ' ''' ~ " .
~Z7~5~
interfere with bleaching of the pulp and pose pollution problems in effluent treatment systems.
The primary objective of brown stock washing is the separation of black liquor from the pulp mat or pad. It is especially desirable to accomplish this primary objective while minimizing water consumption. Efficient separation of black liquor from pulp helps to offset rising costs of production;
for example, greater removal of organics from pulp means that more of these organics are available as h~at sources and lower water consumption lowers black liquor evaporation costs. Also, more efficient washing produces a cleaner pulp mat, which reduces bleaching costs.
Typically, rotary vacuum drum washers are used for the washing of pulp mats or pads. Wash water is sprayed onto a pad of fibers as the pad forms on the surface of the rotary drum. The black liquor and wash water is "pulledi' through the pad by vacuum, thus effectuating the separation.
Oftentimes, countercurrent multistage washers are used. The instant invention includes the use of washing aids at any stage of a multistage washing process.
Though the use of high molecular weight polyacrylamide polymers as brown stock washing aids has been suggested (see "The Detrimental Effect of Channeling on the Effectiveness of Displacement Washing of Pads of Wood Pulp Fibers and a Technique for its Reduction", by P. F. Lee of the Weyerhaeser Technology Center, Tacomal Washington) additives have not generally been used to improve the efficiency of brown stock washers. Thus, higher solids removal has been obtained by additional washingO The .. .:
'~
' ~; ' .
7()354 disadvantage of this mode of operation is that extensive washing dilutes the resulting liquor. Weak black liquor streams increase evaporation costs and may require the use of storage tanks and~or the shipment of the liquor from the generating site.
Further, extensive washing may not be a viable option where water usage is restricted or where the mill water circ~it is a "closed loop". For these reasons, the instant invention, which results in equivalent removal of dissolved solids from a fiber mat at lower water consumption or in greater removal of contaminants at equivalent consumption when compared to prior art washing methods, is a notable advance in the art.
As noted earlier, the Lee reference suggests the use of high molecular weight polyacrylamides as washing aids. The inventor has found these polymers to be unsuitable agents for the separation of black liquor from pulp mats or pads, because they tend to restrict flow of a washing medium through a pulp mat or pad too greatly. Thus, washing times become excessive, a result which makes the use of Lee's polyacrylamides impracticable.
It is necessary not only to improve washing efficiency, but to do so without greatly increasing washing time. Thus, a suitable additive improves washing efficiency without significantly lncreasing washing time.
The instant met~od constitutes a way of improving pulp washing efficiency without greatly increasing washing time. As a thick cellulosic fiber mat is formed on the drum surface of a rotary-vacuum brown stock washer, the black liquor contained within the mat is more effectively displaced by using an .
3L~7~3~
acrylamide/dimethyldiallylammonium chloride polymer as a separation aid. Thus, less wash ~ater is required for separation of the black l:iquor from the mat than is required when no polymer is added.
Alternatively, greater removal of contaminants for the same amount of wash water can be realized utilizing the polymers of the instant invention.
DESCRIPTION OF THE INVENTION
The instant invention relates to a method of separating black liquor from a pulp pad comprising:
(a) contacting the pulp pad and/or black liquor with a polymer selected from the group consisting of polymers made from:
(i) one or more cationic monomers selected from the group consisting of dimethyldiallylammonium chloride, dimethyldiallyl ammonium bromide, diethyldiallylammonium chloride and diethyldially a~,monium bromide, and ~ii) one or more nonionic monomers selected from the group consisting of acrylamide and methacrylamide, wherein the total ratio of cationic monomer to nonionic monomer is 95:5 to 5:95, by weight, and wherein said polymer is contacted at a dosage of greater than 0.1 ppm, based on the weight of the black liquor/pulp stream being treated;
(b) washing the pulp pad with a washing medium;
and (c) applying vacuum to said pad.
More particularly, the instant invention relates to an improved process for separating black liquor from pulp. Thusl in a process for separating 3~
a black liquor/pulp stream into black liguor and pulp components comprising washing a pulp mat or pad with a washing medium and applying vacuum to said pulp mat or pad, thereby dissplacing black liquor from said pad, the instant improvement comprises contacting the pulp and/or black liquor with an acrylamide/dimethyl-diallylammonium chloride polymer or homologue thereof, prior to or during said step of washing and prior to said step of applying vacuum, thereby more efficiently separating said black liquor from said pad.
The polymer can be added directly to the pulp/black liquor stream, i.e a brown stock stream, or it can be added to the washing medium. Washing mediums generally comprise water, or solutions of water and black liquor. ~he ratio of acrylamide to dimethyldiall~lammonium chloride in the polymer may range from 5:95 to 95:5, by weight, and the polymer should be added at a dosage of at least 0.1 ppM, based on the weigh~ of the black liquor/pulp stream (i.e. brown stock stream) being treated. If added to a brown stock stream, the instant polymers contact the pulp/black liquor before the washing step. If added to the washing medium, the instant polymers contact the pulp/black liquor during washing.
The most preferred polymers suitable for use in this invention are polymers of acrylamide and dimethyldiallylammonium chloride (DMDAAC). However, homologues of the DMDAAC and acrylamide polymers are also preferred. Homologues, as used herein, are defined as polymers which are structurally and functionally similar to polymers of DMDAAC and acrylamide. ~xamples of homologues include, but are not limited to, polymers of diethyldiallylammonium chloride ~DEDAAC) and acrylamide, DEDAAC and ~7(~
methacrylamide, DMDAAC and methacrylamide, dimethyldiallyl ammonium bromide (DMDAAB) and acrylamide, DMDAAB and methacrylamider diethyldiallyl ammonium bromide (DEDAAB) and acrylamide, and DEDAAB
and methacrylamide.
More generally, polymers suitable for use as black liquor washing aids comprise those made from one or more cationic monomers selected from the group consisting of DMDAAC, DMDAAB, DEDAAB and DEDAAC and from one or more nonionic polymers selected from the group consisting of acrylamide and methacrylamide.
The ratio of monomers used to produce the polymers of this invention may range from 95:5 to 5:95, on a cationic:nonionic weight basis. The preferred monomer ratio range is 25:75 to 75:25, by weight, on a cationic nonionic basis. The most preferred polymers are polymers prepared using 4S:55 to 55:45 monomer weight ratios, on a cationic:nonionic basis.
The molecular weight of the polymers used in the instant invention is not critical. However, polymers having molecular weights in excess of 100,000, as measured by light scattering techniques, are preferred.
The polymers of the instant invention can be added either to the washing medium or to a pulp/black liquor stream (i.e. brown stock). For example, the polymer can be added directly to a brown stock washer feed stream or the polymer can be added to the wash water or other washing medium. It is preferred to add the polymer directly to the brown stock, i.e. to the black liquor/pulp stream, in a manner which provides thorough mixing. The brown stock/polymer admixture can then be treated usin~ a rotary vacuum drum filter or other washing apparatus known in the ~.~7~35~
art. The polymer increases the separation of the cellulosic pulp mat from the black liquor via vacuum filtration. This improved separation lowers evaporation costs of the black liquor while increasing the solids content of the separated black liquor. The dosage of the polymer should be in excess of 0.1 ppm, based on the weight of the black liquor/pulp stream being treated. The preferred dosage range is from 1 ppm to 50 ppm. The most preferred dosage ranges from 1.0 ppm to 10 ppm. This dosage has shown a reduction of lG to 15~ in water consumption at a brown stock washing operation, without greatly increasing washing times.
If multistage washing is used, the polymers of the instant invention can be used at any stage without departing from the spirit of this invention.
In such instances, the wasing medium initially comprises water. Since this wash water is reused, it generally comprises a solution of water and black liquor at later sta~es.
EXAMPLES
rrhe following examples illustrate the present invention in greater detail. It should be understood, however, that the invention is not in any way limited by these examples.
In the following examples, a brown stock solution of 0.5~ consistency was used. Thus, the solution contained .5 g pulp/100 g black liquor.
This stock solution was obtained from an operating paper mill.
.
. . .. .
.
,~ ..
1529M/0~17A - 9 - C-1396 A 1500 ml aliquot of the 0.5~ brown stock was placed in a beaker on a hot plate. The temperature was kept constant at 140F, to simulate plant operatinq temperatures. A magnetic stirrer agitated the stock solution uniformly. 125 ml aliquots were withdrawn from the 1500 ml aliquot.
Polymer was then added to each smaller aliq~ot in the dosage indicated for each example based on the weight 1~ of brown stock. Each smaller aliquot containing the polymer was then cascaded 8 times from its beaker to another beaker to simulate mixing in the piping of an operating mill. This solution was added to a Buckner fun~el. The funnel was attached to a vacuum pump with 26.5 inches of water vacuum. The base of the funnel was attached to a graduated burette. The time needed to drain 0, 25, 75, and 110 ml of filtrate was recorded. The Buckner funnel used was 11 cm, in diameter, and Wo. 2 ~hatmann filter paper was used. The results of Examples 1-10 are shown in Table I. In this table, DMDAAC means dimethyldiallyl ammonium chloride, AM means acrylamide, META~S means methacryloyloxyethyl trimethyl ammonium methosulfate, AMPAM means amino methylated polyacrylamide and P~M
means polyacrylamide. Table I also shows the approximate molecular weights of the polymers tested.
Examples 1 through 10 screen polymers based on drainage times. An excessive drainage time indicates that use of the related polymer is impractical, because it would greatly lengthen washing time.
.. . .
: : ' 1 5 2 9M /0 8 1 7 A - 10 - C ~1 3 96 TABLE I
Total Approximate Time to Drain Example Polymer Monomer Molecular Dosage (seconds) Ho. Type Ratio Weiqht ~ pm) Z5 ml ~-75-ml----rTU ml l* None N/A N/A ~/A 2.5 8.3 12.8
2 DMD M C/AM 50/502,500,000 40 1.6 3.2 12.1 5.0 78.3 739.2
3 DMDAAC/AM 40l603,000,000 40 3.7 8.2 19.6
4 DMD M C/AM 75/253,000,000 40 2.1 5.9 11.1 DMDAAC/AM 95/52,000,000 40 3.6 7.3 16.5 6 DM3 M C N/A 3,500,000 40 4.1 23.5 80.0 7 METAM/AM 15/855,000,000 40 8.4 53.6 748.6 8 AMPAM N/A 6,000,000 40 32.2 762.0 --9* PAM N/A 8,000,000 40 65.2 416.2 1841.3 10* PAM N/A 6,000,000 40 235.3 758.1 1414.4 *Comparison Example Notes: 1. The DMDAAC/AM polymer of Example 2 is commercially available from Calnon Corp. as H777HS.
2- The DMDAAC/AM polymer of Example 3 is commercially available from Calgon Corp. as WT2570.
3- The DMDAAC/AM polymer of Example 4 is commercially available from Calgon Corp. as E-2000.
4- The DMDAAC/AM polymer of Example 5 is commercially available from Calgon Corp. as WT2860.
2- The DMDAAC/AM polymer of Example 3 is commercially available from Calgon Corp. as WT2570.
3- The DMDAAC/AM polymer of Example 4 is commercially available from Calgon Corp. as E-2000.
4- The DMDAAC/AM polymer of Example 5 is commercially available from Calgon Corp. as WT2860.
5- The polymer of Example 6 is com~ercially available from Calgon Corp. as Cat-Floc H7392.
S- The polymer of Example 7 is commercially available from Calgon Corp. as H5515.
7- The polymer of Example 8 is commercially available from Calgon Corp. as H-410.
8- The polymer of Example 9 i5 LOmmerCially available from Calgon Corp. as E2113.
9 The polymer of Example 10 is commercially aYailable from Calgon Corp. as L650E.
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.
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1529M/081'7A ~ C-1396 In these Examples, the procedure of Examples 1~10 was followed. However, after draining 110 ml of filtrate, the funnel was removed and the burette was rinsed with deionized water. The funnel was then placed again firmly on the top of the burette. The remaining 15 ml of stock (still on the filter pad) was spray washed with 25 ml of deionized water at 160~Fo Thus, 4G ml of filtrate were collected. ~his filtrate was measured for conductivity.
Results of Examples 11-23 are shown in Table II. The higher the conductivity, the higher the removal of impurities from the pulp pad. Thus, high conductivities indicate more thorough washing. The lS polymers used in these examples, 50/50 DMDAAC/AM and 75/25 DMDAAC/AM, were the same as those used in Examples 2 and 4, respectively.
3~
TABLE II
Total Time Conductivity Example Dosage to Drain (sec) of filtrate No. Polymer (ppm) 25 ml 75 ml 110 ml (~mhos) 11* None N/A 5.1 14.43 28.75 2337.5 12 50/SO DMDAAC/AM 1.6 7.0 24.7 41.0 2850 13 50/50 DMD M C/AM 5.0 5.2 19.6 38.1 3250 14 50/50 DMD M C/AM 10.0 6.7 23.3 47.2 2950 50/50 DMD M C/AM 20.0 5.3 24.2 54.7 3300 16 50/50 DMDAAC/AM 40.0 7.6 40.3 llD.9 3650 17 50/50 DMDAAC/AM 80.0 7~5 71.9 51D.8 3400 18 75/25 DMD M C/AM 1.6 6.2 17.8 27.5 2500 19 75/25 DMD M C/AM 5.0 6.D 18.2 35.9 2400 75/25 DMDAAC/AM 10.0 6.1 17.9 35.1 2100 21 75/25 DMDAAC/AM 20.0 6.4 20.1 37.8 3200 22 75/25 DMD M C/AM 40.0 6.5 21.8 39.6 3000 23 75/25 OMDAAC/AM 80.0 8.2 33.0 83.0 3300 *Comparison Example Notes: 1. Example 11 represents an average of 4 separate runs.
2- Example 13 represents an average of 2 separate runs.
3~ Example 14 represents an a~erage of 2 separate runs.
: ..
.
.. . ..
.
~' :
, .
These Examples were run according to the procedures for examples 1-23. However~ two (2) separate brown stock temperat~res were used in each example -- room temperature and 140F. Results of these examples are shown in Table III.
..; :. -.: .
tABLE III
Stock Total Time Example Polymer Dosage TeMp. to Drain Conductivity _ No.Added (ppm) ~F 25 ml 75 ml110 ml (~mhos) 24*None N/A Room 7.8 33.668.5 1900 140 5.1 14.528.3 2325 2550/50 DMDAAC/AM 5.0 Room 8.2 26.769.8 2750 140 6.2 19.638.1 3250 2650/50 DMD M C/AM10.0Room 6.5 31.971.7 1900 140 6.7 23.347.2 2950 2775/25 DMDAAC/AM 5.0 Room 7.8 33.367.2 2900 140 6.0 1835.9 2400 2875/25 DMDAAC/AM10.0 Room 7.2 30.96.1 2600 140 6.1 17.435.1 2100 *Comparison Example Room Temp. = 72F.
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. , , .
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These examples demonstrate the significance between testing at 140F, which approximates plant operting temperture, and room temperature.
' ,'' '~ '.
."
S- The polymer of Example 7 is commercially available from Calgon Corp. as H5515.
7- The polymer of Example 8 is commercially available from Calgon Corp. as H-410.
8- The polymer of Example 9 i5 LOmmerCially available from Calgon Corp. as E2113.
9 The polymer of Example 10 is commercially aYailable from Calgon Corp. as L650E.
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~-27~33~
1529M/081'7A ~ C-1396 In these Examples, the procedure of Examples 1~10 was followed. However, after draining 110 ml of filtrate, the funnel was removed and the burette was rinsed with deionized water. The funnel was then placed again firmly on the top of the burette. The remaining 15 ml of stock (still on the filter pad) was spray washed with 25 ml of deionized water at 160~Fo Thus, 4G ml of filtrate were collected. ~his filtrate was measured for conductivity.
Results of Examples 11-23 are shown in Table II. The higher the conductivity, the higher the removal of impurities from the pulp pad. Thus, high conductivities indicate more thorough washing. The lS polymers used in these examples, 50/50 DMDAAC/AM and 75/25 DMDAAC/AM, were the same as those used in Examples 2 and 4, respectively.
3~
TABLE II
Total Time Conductivity Example Dosage to Drain (sec) of filtrate No. Polymer (ppm) 25 ml 75 ml 110 ml (~mhos) 11* None N/A 5.1 14.43 28.75 2337.5 12 50/SO DMDAAC/AM 1.6 7.0 24.7 41.0 2850 13 50/50 DMD M C/AM 5.0 5.2 19.6 38.1 3250 14 50/50 DMD M C/AM 10.0 6.7 23.3 47.2 2950 50/50 DMD M C/AM 20.0 5.3 24.2 54.7 3300 16 50/50 DMDAAC/AM 40.0 7.6 40.3 llD.9 3650 17 50/50 DMDAAC/AM 80.0 7~5 71.9 51D.8 3400 18 75/25 DMD M C/AM 1.6 6.2 17.8 27.5 2500 19 75/25 DMD M C/AM 5.0 6.D 18.2 35.9 2400 75/25 DMDAAC/AM 10.0 6.1 17.9 35.1 2100 21 75/25 DMDAAC/AM 20.0 6.4 20.1 37.8 3200 22 75/25 DMD M C/AM 40.0 6.5 21.8 39.6 3000 23 75/25 OMDAAC/AM 80.0 8.2 33.0 83.0 3300 *Comparison Example Notes: 1. Example 11 represents an average of 4 separate runs.
2- Example 13 represents an average of 2 separate runs.
3~ Example 14 represents an a~erage of 2 separate runs.
: ..
.
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.
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These Examples were run according to the procedures for examples 1-23. However~ two (2) separate brown stock temperat~res were used in each example -- room temperature and 140F. Results of these examples are shown in Table III.
..; :. -.: .
tABLE III
Stock Total Time Example Polymer Dosage TeMp. to Drain Conductivity _ No.Added (ppm) ~F 25 ml 75 ml110 ml (~mhos) 24*None N/A Room 7.8 33.668.5 1900 140 5.1 14.528.3 2325 2550/50 DMDAAC/AM 5.0 Room 8.2 26.769.8 2750 140 6.2 19.638.1 3250 2650/50 DMD M C/AM10.0Room 6.5 31.971.7 1900 140 6.7 23.347.2 2950 2775/25 DMDAAC/AM 5.0 Room 7.8 33.367.2 2900 140 6.0 1835.9 2400 2875/25 DMDAAC/AM10.0 Room 7.2 30.96.1 2600 140 6.1 17.435.1 2100 *Comparison Example Room Temp. = 72F.
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These examples demonstrate the significance between testing at 140F, which approximates plant operting temperture, and room temperature.
' ,'' '~ '.
."
Claims (7)
1. In a process for separating a black liquor/pulp stream into black liquor and pulp components comprising washing a pulp pad with washing medium and applying vacuum to said pad, thereby displacing black liquor from said pad, the improvement comprising:
. (a) contacting the pulp pad and/or black liquor with a polymer selected from the group consisting of polymers made from:
(i) one or more cationic monomers selected from the group consisting of dimethyldiallylammonium chloride, dimethyldiallyl ammonium bromide, diethyldiallylammonium chloride and diethyldially ammonium bromide, and (ii) one or more nonionic monomers selected from the group consisting of acrylamide and methacrylamide, wherein the total ratio of cationic monomer to nonionic monomer is 95:5 to 5:95, by weight, and wherein said polymer is contacted at dosage of greater than 0.1 ppm, based on the weight of the black liquor/pulp stream being treated;
prior to or during said step of washing and prior to said step of applying vacuum.
. (a) contacting the pulp pad and/or black liquor with a polymer selected from the group consisting of polymers made from:
(i) one or more cationic monomers selected from the group consisting of dimethyldiallylammonium chloride, dimethyldiallyl ammonium bromide, diethyldiallylammonium chloride and diethyldially ammonium bromide, and (ii) one or more nonionic monomers selected from the group consisting of acrylamide and methacrylamide, wherein the total ratio of cationic monomer to nonionic monomer is 95:5 to 5:95, by weight, and wherein said polymer is contacted at dosage of greater than 0.1 ppm, based on the weight of the black liquor/pulp stream being treated;
prior to or during said step of washing and prior to said step of applying vacuum.
2. The process of Claim 1 wherein said polymer is 5 to 95 percent, by weight, dimethyldi-allylammonium chloride and 95 to 5 percent, by weight, acrylamide.
3. The process of Claim 2 wherein said polymer is 25 to 75 percent, by weight, dimethyldiallylammonium chloride and 75 to 25 percent, by weight, acrylamide.
4. The process of Claim 3, wherein the ratio of dimethyldiallylammonium chloride to acrylamide is 45:55 to 55:45.
5. The process of Claim 1 wherein said washing medium is water.
6. The process of Claim 1 wherein said polymer is added to said washing medium, thereby contacting said black liquor and/or pulp pad.
7. The process of Claim 1 wherein said polymer is added to said black liquor/pulp stream, thereby contacting said black liquor and/or pulp prior to said steps of washing and applying vacuum.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US66702484A | 1984-11-01 | 1984-11-01 | |
| US667,024 | 1984-11-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1270354A true CA1270354A (en) | 1990-06-19 |
Family
ID=24676493
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000493656A Expired - Fee Related CA1270354A (en) | 1984-11-01 | 1985-10-23 | Method for improving brown stock washer efficiency |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1270354A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5405498A (en) * | 1993-06-22 | 1995-04-11 | Betz Paperchem, Inc. | Method for improving pulp washing efficiency |
| US5464502A (en) * | 1993-10-05 | 1995-11-07 | Betz Paperchem, Inc. | Anionic sulfonate surfactants in the washing and pulping operation |
-
1985
- 1985-10-23 CA CA000493656A patent/CA1270354A/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5405498A (en) * | 1993-06-22 | 1995-04-11 | Betz Paperchem, Inc. | Method for improving pulp washing efficiency |
| US5464502A (en) * | 1993-10-05 | 1995-11-07 | Betz Paperchem, Inc. | Anionic sulfonate surfactants in the washing and pulping operation |
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