U.S. patent application number 12/405797 was filed with the patent office on 2010-09-23 for use of fluorescence to monitor hydrophobic contaminants in a papermaking process.
Invention is credited to Alessandra Gerli, Michael J. Murcia, Laura M. Sherman.
Application Number | 20100236732 12/405797 |
Document ID | / |
Family ID | 42216853 |
Filed Date | 2010-09-23 |
United States Patent
Application |
20100236732 |
Kind Code |
A1 |
Gerli; Alessandra ; et
al. |
September 23, 2010 |
USE OF FLUORESCENCE TO MONITOR HYDROPHOBIC CONTAMINANTS IN A
PAPERMAKING PROCESS
Abstract
A method of monitoring and controlling one or more types of
hydrophobic contaminants in a papermaking process is disclosed. The
methodology utilizes the measurement of dyes, which are capable of
fluorescing and interacting with the hydrophobic contaminants.
Inventors: |
Gerli; Alessandra; (Leiden,
NL) ; Sherman; Laura M.; (Naperville, IL) ;
Murcia; Michael J.; (DeKalb, IL) |
Correspondence
Address: |
NALCO COMPANY
1601 W. DIEHL ROAD
NAPERVILLE
IL
60563-1198
US
|
Family ID: |
42216853 |
Appl. No.: |
12/405797 |
Filed: |
March 17, 2009 |
Current U.S.
Class: |
162/49 |
Current CPC
Class: |
G01N 2021/6439 20130101;
G01N 21/643 20130101; G01N 33/343 20130101 |
Class at
Publication: |
162/49 |
International
Class: |
D21H 21/30 20060101
D21H021/30 |
Claims
1. A method of monitoring one or more types of hydrophobic
contaminants in a papermaking process comprising: a. obtaining a
bulk sample of fluid from said papermaking process; b. selecting a
hydrophobic dye that is capable of interacting with said
contaminants in said fluid and fluorescing in said fluid; c. adding
said dye to said fluid and allowing a sufficient amount of time for
said dye to interact with said contaminants in said fluid; d.
measuring the fluorescence of the dye in said fluid; e. correlating
the fluorescence of the dye with the concentration of said
contaminants; and f. optionally controlling the amount of one or
more chemicals that reduce or inactivate said contaminants which
are added to said papermaking process.
2. The method of claim 1 further comprising: measuring the
turbidity of said fluid.
3. The method of claim 2 wherein said turbidity of said fluid is
measured before and after the addition said chemicals.
4. The method of claim 1, wherein said fluid is filtered or diluted
or a combination thereof prior to said addition of said dye or said
fluorescent measurement of said dye.
5. The method of claim 1, wherein said dye does not include
N-(n-butyl)-4-(n-butylamino)-naphthalimide.
6. The method of claim 1 wherein said fluid is obtained from a wet
end of said papermaking process.
7. The method of claim 1 wherein said dye is mixed with a solvent
prior to its addition to said fluid.
8. The method of claim 1, wherein said contaminants are selected
from the group consisting of: pitch, fiber, filler, fines, coated
broke, mill broke, recycle, groundwood, thermal mechanical pulp,
deinked pulp furnish, chemi-thermal mechanical pulp, chemical pulp,
ink, adhesives, stickies, tackies, waxes, binders and dissolved
and/or colloidal substances, and a combination thereof.
9. The method of claim 1, wherein said method is an on-line method
and/or batch sample method.
10. The method of claim 1, wherein said fluorometric measurement is
performed at a pre-set basis, intermittent basis, and/or continuous
basis.
11. The method of claim 1, wherein said fluorometric measurement is
performed with a handheld fluorometer.
12. The method of claim 1, wherein said fluid is an aqueous
filtrate of a pulp slurry.
13. A method for measuring the effectiveness of one or more
chemicals that decrease the amount of one or more hydrophobic
contaminants in a papermaking process: a. monitoring one or more
types of contaminants in a papermaking process comprising:
obtaining a bulk sample of fluid from said papermaking process;
selecting a hydrophobic dye that is capable of interacting with
said contaminants in said fluid and fluorescing in said fluid;
adding said dye to said fluid and allowing a sufficient amount of
time for said dye to interact with said contaminants in said fluid;
measuring the fluorescence of the dye in said fluid; and
correlating the fluorescence of the dye with the concentration of
said contaminants; b. adding one or more chemicals to said
papermaking process that decrease the amount of said hydrophobic
contaminants; and c. re-measuring the amount of contaminants in
said papermaking process by performing step (a) at least one more
time; and d. optionally controlling the amount of said chemicals
that are added to said papermaking process.
14. The method of claim 13, wherein said chemicals are at least one
of the following: a fixative; a detackifier; a dispersant; a
surfactant; and a retention aid.
15. A method of monitoring one or more types of hydrophobic
contaminants in a papermaking process consisting essentially of: a.
obtaining a bulk sample of fluid from said papermaking process; b.
selecting a hydrophobic dye that is capable of interacting with
said contaminants in said fluid and fluorescing in said fluid; c.
adding said dye to said fluid and allowing a sufficient amount of
time for said dye to interact with said contaminants in said fluid;
d. measuring the fluorescence of the dye in said fluid; e.
correlating the fluorescence of the dye with the concentration of
said contaminants; and f. optionally controlling the amount of one
or more chemicals that reduce or inactivate said contaminants which
are added to said papermaking process.
Description
FIELD OF THE INVENTION
[0001] This invention pertains to the measurement and control of
hydrophobic contaminants.
BACKGROUND OF THE INVENTION
[0002] Hydrophobic/organic contaminants, such as natural pitch,
stickies, tackies and white pitch are major obstacles in paper
manufacturing because these materials when liberated during a
papermaking process can become both undesirable components of
papermaking furnishes and troublesome to the mill equipment by
preventing proper operation of mechanical parts when these
materials deposit.
[0003] Increased use of secondary fiber, coated broke and
mechanical pulp in the papermaking process contributes to the
accumulation of organic contaminants. These contaminants can form
deposits that affect machine runability and final product quality.
Control of the contaminants is typically managed through chemical
fixation, and its effectiveness is therefore dependent on the
ability to determine the proper program and application.
Historically, a common method used to assess program performance
has been filtrate turbidity reduction. This method, however, is not
entirely adequate because it often yields an incomplete picture of
the furnish demands from hydrophobic particles. More recently, flow
cytometry has been used in the industry for monitoring hydrophobic
contaminants. Disadvantages of this method are that it is both
labor and capital intensive.
[0004] A rapid and accurate method of measuring organic
contaminants is therefore desired. Chemical control programs are
often used to passivate or remove deposit-forming contaminants. For
that reason, a method of screening the efficacy of chemical
treatments that reduce the overall content of hydrophobic
contaminants in a papermaking process is also desired.
SUMMARY OF THE INVENTION
[0005] The present invention provides for a method of monitoring
one or more types of hydrophobic contaminants in a papermaking
process comprising: (a) obtaining a bulk sample of fluid from said
papermaking process; (b) selecting a hydrophobic dye that is
capable of interacting with said contaminants in said fluid and
fluorescing in said fluid; (c) adding said dye to said fluid and
allowing a sufficient amount of time for said dye to interact with
said contaminants in said fluid; (d) measuring the fluorescence of
the dye in said fluid; (e) correlating the fluorescence of the dye
with the concentration of said contaminants; and (f) optionally
controlling the amount of one or more chemicals that reduce or
inactivate said contaminants which are added to said papermaking
process.
[0006] The present invention also provides for a method for
measuring the effectiveness of one or more chemicals that decrease
the amount of one or more hydrophobic contaminants in a papermaking
process: (a) monitoring one or more types of contaminants in a
papermaking process comprising: obtaining a bulk sample of fluid
from said papermaking process; selecting a hydrophobic dye that is
capable of interacting with said contaminants in said fluid and
fluorescing in said fluid; adding said dye to said fluid and
allowing a sufficient amount of time for said dye to interact with
said contaminants in said fluid; measuring the fluorescence of the
dye in said fluid; and correlating the fluorescence of the dye with
the concentration of said contaminants; (b) adding one or more
chemicals to said papermaking process that decrease the amount of
said hydrophobic contaminants; and (c) re-measuring the amount of
contaminants in said papermaking process by performing step (a) at
least one more time; and (d) optionally controlling the amount of
said chemicals that are added to said papermaking process.
[0007] The present invention also provides for a method of
monitoring one or more types of hydrophobic contaminants in a
papermaking process consisting essentially of: (a) obtaining a bulk
sample of fluid from said papermaking process; (b) selecting a
hydrophobic dye that is capable of interacting with said
contaminants in said fluid and fluorescing in said fluid; (c)
adding said dye to said fluid and allowing a sufficient amount of
time for said dye to interact with said contaminants in said fluid;
(d) measuring the fluorescence of the dye in said fluid; (e)
correlating the fluorescence of the dye with the concentration of
said contaminants; and (f) optionally controlling the amount of one
or more chemicals that reduce or inactivate said contaminants which
are added to said papermaking process.
DETAILED DESCRIPTION OF THE INVENTION
[0008] "Papermaking process" means a method of making any kind of
paper products (e.g. paper, tissue, board, etc.) from pulp
comprising forming an aqueous cellulosic papermaking furnish,
draining the furnish to form a sheet and drying the sheet The steps
of forming the papermaking furnish, draining and drying may be
carried out in any manner generally known to those skilled in the
art. The papermaking process may include a pulping stage, e.g.
making pulp from woody raw material and bleaching stage, e.g.
chemical treatment of the pulp for brightness improvement.
Furnishes can contain fillers and/or other contaminants.
[0009] "Bulk sample" means a sample whose constituents have not
been specifically separated, except bulk sample may include, a
separation based upon size. For example, bulk sample does not
include separating e.g. a resin particle from a suspension.
[0010] "Fluid" includes an aqueous papermaking suspension from a
papermaking process, e.g. a fluid containing fibers in a pulping
stage, a thin stock, a thick stock, aqueous suspensions drawn from
the papermaking process, e.g. various locations from a papermaking
machine or pulping process, aqueous fluid in a uhl box, press
dewatering section, and/or any part of the papermaking process that
one of ordinary skill in the art can think of where one would need
to monitor hydrophobic contaminants.
[0011] As stated above, the present invention provides for a method
of monitoring one or more types of hydrophobic contaminants in a
papermaking process via the use of fluorescence.
[0012] The dyes, which are added to the sample must be able to
stain or interact with the hydrophobic contaminants, e.g. pitch
particles.
[0013] In another embodiment, the turbidity of the fluid is also
measured. In a further embodiment, the turbidity of said fluid is
measured before and after the addition of said chemicals.
[0014] In another embodiment, the fluid is filtered or diluted or a
combination thereof prior to said addition of said dye or said
fluorescent measurement of said dye, wherein said filtering or
dilution of said fluid permits said fluid to be fluorometrically
monitored.
[0015] In another embodiment, the sample is taken from a dilute
sample point off a papermaking process, e.g. a paper machine. In a
further embodiment, the sample point is the white water of a
papermaking process. The reasoning postulated for this
collection/sample point is that there is no long fiber
present/substantially any fiber present, and filtration may not be
necessary.
[0016] In another embodiment, one or more samples undergo a
sieving/separation step to separate the long fiber from the
suspended contaminants in a sample solution. For example, the
degree of dilution that the filtrate/aqueous fraction undergoes
from the separation process relies on two main factors, both
relating to turbidity. If the filtrate/aqueous fraction is too
turbid for the turbidimeter, dilution is required to bring the
turbidity into a measurable range for the meter. This is the case
unless you want a less accurate and "quick and dirty" test, which
is one embodiment of the claimed invention.
[0017] In another embodiment, if the turbidity is above 2000 NTU
(nephelometric turbidity units), then it is a preferred embodiment
that a sample from a papermaking process is diluted/further
separated prior to the addition of a dye and fluorescent
measurement. The value of 2000 NTU may be instrument or measurement
technique dependent.
[0018] In another embodiment, the fluid is an aqueous filtrate of a
pulp slurry.
[0019] In another embodiment, the dye does not include
N-(n-butyl)4-(n-butylamino)-naphthalimide.
[0020] In another embodiment, the fluid is obtained from a wet end
of said papermaking process.
[0021] As stated above, the dye added to a sample must have a
sufficient amount of time for said dye to interact with said
contaminants in said fluid prior to its fluorescent measurement.
One of ordinary skill in the art could determine a sufficient
amount of time for said interaction without undue
experimentation.
[0022] In one embodiment, the dye is mixed with a solvent prior to
its addition to said fluid. One of ordinary skill in the art could
determine an adequate time for mixing without undue
experimentation.
[0023] In another embodiment, the contaminants are selected from
the group consisting of: pitch, fiber, filler, fines, coated broke,
mill broke, recycle, groundwood, thermal mechanical pulp,
chemi-thermal mechanical pulp, chemical pulp, deinked pulp, ink,
adhesives, stickies, tackies, waxes, binders and dissolved and/or
colloidal substances, and a combination thereof.
[0024] In another embodiment, the method is an on-line method
and/or batch sample method.
[0025] In another embodiment, the fluorometric measurement is
performed at a pre-set basis, intermittent basis, and/or continuous
basis. For example, a flow cell can be utilized as a means for
measuring the fluorescence of said hydrophobic contaminants. More
specifically, in one embodiment, a process for measurement
comprises: the addition of one or more fluorescent tracers to a
sample obtained from a papermaking process prior to its fluorescent
measurement in said flow cell. One of ordinary skill in the art
would be able to carry out this process without undue
experimentation. For example, one could utilize flow injection
analysis and/or sequence injection analysis techniques to carry out
the above-referenced measurement protocol.
[0026] In another embodiment, the fluorometric measurement is
performed with a handheld fluorometer. A fluorescent measurement
may be carried out with other types of fluorometers.
[0027] The present invention also provides for a method of
measuring the effectiveness of one or more chemicals that decrease
the amount of one or more hydrophobic contaminants in a papermaking
process. The information on the amount of hydrophobic contaminants
in a fluid can be utilized to form a control loop for the addition
of one or more chemicals, which can be used to control the amount
of hydrophobic contaminants.
[0028] In one embodiment, the methodology for monitoring the
hydrophobic contaminants can be measured by the above-stated
fluorescence methodology and its various embodiments.
[0029] In another embodiment, a determination of the amount of
fluorescence is measured by the above-mentioned protocol, then
subsequent to this step, an addition of one or more chemicals to
the papermaking process to treat the hydrophobic contaminants, e.g.
increase/decrease in the same chemistry for hydrophobic contaminant
inhibition or change in the chemistry treatment program for
hydrophobic contaminant inhibition, and then subsequent to the
treatment step, a re-measurement of the amount of contaminants in
said papermaking process by the above-mentioned protocol.
[0030] In another embodiment, the chemicals are at least one of the
following: a fixative; a detackifier; a dispersant; a surfactant;
and a retention aid.
* * * * *