U.S. patent application number 11/931893 was filed with the patent office on 2008-05-08 for methods for cleaning industrial equipment with pre-treatment.
This patent application is currently assigned to ECOLAB INC.. Invention is credited to Peter J. Fernholz, Brandon L. Herdt.
Application Number | 20080105282 11/931893 |
Document ID | / |
Family ID | 37607199 |
Filed Date | 2008-05-08 |
United States Patent
Application |
20080105282 |
Kind Code |
A1 |
Fernholz; Peter J. ; et
al. |
May 8, 2008 |
METHODS FOR CLEANING INDUSTRIAL EQUIPMENT WITH PRE-TREATMENT
Abstract
A method of cleaning equipment such as heat exchangers,
evaporators, tanks and other industrial equipment using
clean-in-place procedures and a pre-treatment solution prior to the
conventional CIP cleaning process. The pre-treatment step improves
the degree of softening of the soil, and thus facilitates its
removal. The pre-treatment solution can be a strong acidic
solution, a strong alkaline solution, or comprise a penetrant. A
preferred strong acidic solution is an acid peroxide solution. In
some embodiments, the pre-treatment may include no strong alkali or
acid ingredient; rather, the penetrant provides acceptable levels
of pre-treatment.
Inventors: |
Fernholz; Peter J.;
(Burnsville, MN) ; Herdt; Brandon L.; (Hastings,
MN) |
Correspondence
Address: |
ECOLAB INC.
MAIL STOP ESC-F7, 655 LONE OAK DRIVE
EAGAN
MN
55121
US
|
Assignee: |
ECOLAB INC.
370 North Wabasha Street
St. Paul
MN
55102
|
Family ID: |
37607199 |
Appl. No.: |
11/931893 |
Filed: |
October 31, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11257874 |
Oct 25, 2005 |
|
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|
11931893 |
Oct 31, 2007 |
|
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10928774 |
Aug 27, 2004 |
|
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11257874 |
Oct 25, 2005 |
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Current U.S.
Class: |
134/26 |
Current CPC
Class: |
C11D 1/72 20130101; A01J
7/022 20130101; A01J 25/126 20130101; C11D 3/3947 20130101; C11D
3/2003 20130101; C11D 3/2075 20130101; B08B 3/08 20130101; B08B
9/032 20130101; C11D 7/265 20130101; C11D 11/0041 20130101; B08B
9/08 20130101; C11D 3/43 20130101; B08B 3/04 20130101; C11D 3/044
20130101; C11D 3/2079 20130101; C11D 7/5004 20130101; C11D 3/042
20130101; C11D 11/0064 20130101 |
Class at
Publication: |
134/026 |
International
Class: |
B08B 3/04 20060101
B08B003/04 |
Claims
1. A method of cleaning soils from industrial equipment using a CIP
process, the method comprising: (a) applying a pre-treatment
solution to the soil, the solution comprising at least 0.10 wt-%
active ingredients, the active ingredients including a surfactant
penetrant and an oxidizer selected from the group consisting of
hydrogen peroxide, peroxygen compounds and mixtures thereof; (b)
recirculating a second solution through the equipment after the
pre-treatment solution, the second solution comprising a dilute
detergent; and then (c) rinsing the equipment.
2.-12. (canceled)
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 10/928,774 titled METHODS FOR CLEANING
INDUSTRIAL EQUIPMENT WITH PRE-TREATMENT, filed on Aug. 27, 2004,
the complete disclosure of which is incorporated herein by
reference in its entirety.
FIELD
[0002] The invention relates to cleaning of industrial equipment
such as evaporators, heat exchangers and other such equipment that
is conventionally cleaned using a CIP (clean-in-place) process.
BACKGROUND
[0003] In many industrial applications, such as the manufacture of
foods and beverages, hard surfaces commonly become contaminated
with soils such as carbohydrate, proteinaceous, and hardness soils,
food oil soils and other soils. Such soils can arise from the
manufacture of both liquid and solid foodstuffs. Carbohydrate
soils, such as cellulosics, monosaccharides, disaccharides,
oligosaccharides, starches, gums and other complex materials, when
dried, can form tough, hard to remove soils, particularly when
combined with other soil components such as proteins, fats, oils
and others. The removal of such carbohydrate soils can be a
significant problem. Similarly, other materials such as proteins,
fats and oils can also form hard to remove soil and residues.
[0004] Food and beverage soils are particularly tenacious when they
are heated during processing. Foods and beverages are heated for a
variety of reasons during processing. For example, in dairy plants,
dairy products are heated on a pasteurizer (e.g. HTST--high
temperature short time pasteurizer or UHT--ultra high temperature
pasteurizer) in order to pasteurize the dairy product. Also, many
food and beverage products are concentrated or created as a result
of evaporation.
[0005] Specific examples of food and beverage products that are
concentrated using evaporators include dairy products such as whole
and skimmed milk, condensed milk, whey and whey derivatives,
buttermilk, proteins, lactose solutions, and lactic acid; protein
solutions such as soya whey, nutrient yeast and fodder yeast, and
whole egg; fruit juices such as orange and other citrus juices,
apple juice and other pomaceous juices, red berry juice, coconut
milk, and tropical fruit juices; vegetable juices such as tomato
juice, beetroot juice, carrot juice, and grass juice; starch
products such as glucose, dextrose, fructose, isomerose, maltose,
starch syrup, and dextrine; sugars such as liquid sugar, white
refined sugar, sweetwater, and insulin; extracts such as coffee and
tea extracts, hop extract, malt extract, yeast extract, pectin, and
meat and bone extracts; hydrolyzates such as whey hydrolyzate, soup
seasonings, milk hydrolyzate, and protein hydrolyzate; beer such as
de-alcoholized beer and wort; and baby food, egg whites, bean oils,
and fermented liquors.
[0006] There are generally at least two sides to an evaporator. One
side holds the steam or vapor heat source (typically 212.degree. F.
to 350.degree. F.). The other side holds the process liquid to be
concentrated. During the evaporation process, the liquid to be
concentrated is introduced into the evaporator. The heat exchange
across the tubes or plates evaporates water off the process stream
concentrating the liquid solids. The liquid to be concentrated may
be run through an evaporator several times until it is sufficiently
concentrated.
[0007] There are many different types of evaporators including
falling film evaporators, forced circulation evaporated
evaporators, plate evaporators, circulation evaporators, fluidized
bed evaporators, falling film short path evaporators, rising film
evaporators, counterflow-trickle evaporators, stirrer evaporators,
and spiral tube evaporators. In addition to the evaporators, there
are several other pieces of equipment in an evaporation plant
including preheaters and heaters, separators, condensers,
deaeration/vacuum systems, pumps, cleaning systems, vapor
scrubbers, vapor recompression systems, and condensate polishing
systems. All of the evaporation plant equipment should be cleaned,
however, the actual evaporator typically has the most difficult
soiling problems.
[0008] When a food or beverage product contacts any surface,
soiling occurs where some part of the food or beverage product is
left behind on that surface. When that surface is a heat exchange
surface, the soil becomes thermally degraded rendering it even more
difficult to remove. Over time, the layer of soil increases in
thickness as more food or beverage product is passed over the heat
exchange surface. The layer of soil acts as an insulator between
the heat and the product being heated, thereby reducing the
efficiency of the heat exchange surface and requiring more energy
to create the same effect if the heat exchange surface were clean.
When the heat exchange surface is an evaporator, the difference
between a clean heat exchange surface and a soiled heat exchange
surface can mean the difference in millions of dollars in energy
costs for an evaporator plant. With the cost of energy increasing
significantly, as well as an increased awareness of protecting the
environment by preserving natural resources, there remains a need
for cleaning programs that can clean heat exchange surfaces and
create an efficient transfer a heat.
[0009] Clean-in-place cleaning techniques are a specific cleaning
regimen adapted for removing soils from the internal components of
tanks, lines, pumps and other process equipment used for processing
typically liquid product streams such as beverages, milk, juices,
etc. Clean-in-place cleaning involves passing cleaning solutions
through the system without dismantling any system components. The
minimum clean-in-place technique involves passing the cleaning
solution through the equipment and then resuming normal processing.
Any product contaminated by cleaner residue can be discarded. Often
clean-in-place methods involve a first rinse, the application of
the cleaning solutions, a second rinse with portable water followed
by resumed operations. The process can also include any other
contacting step in which a rinse, acidic or basic functional fluid,
solvent or other cleaning component such as hot water, cold water,
etc. can be contacted with the equipment at any step during the
process. Often the final portable water rinse is skipped in order
to prevent contamination of the equipment with bacteria following
the cleaning and/or sanitizing step.
[0010] Clean-in-place processing requires a complete or partial
shutdown of the equipment being cleaned, which results in lost
production time. Many times, the equipment is not thoroughly
cleaned, due to the large downtime needed. What is needed is an
improved method for cleaning this equipment, using the
clean-in-place process, which uses less time to thoroughly remove
the soils.
[0011] It is against this background that the present invention has
been made.
SUMMARY OF THE DISCLOSURE
[0012] Surprisingly, it has been discovered that food and beverage
soils, and especially baked-on food and beverage soils can be
removed from surfaces using a two-step method where the soil is
contacted with a pre-treatment composition in a pre-treatment step,
followed by a conventional clean-in-place process. The invention
relates to methods of cleaning equipment such as heat exchangers,
evaporators, tanks and other industrial equipment using
clean-in-place procedures. The method is suitable for organic soil
removal or, more particularly, for food or beverage soil removal.
Further, the method relates to cleaning processes for removing
carbohydrate and proteinaceous soils from food and beverage
manufacturing locations using a clean-in-place method.
[0013] In one aspect, the invention is directed to a method that
includes pre-treating the soiled surfaces with a strong acidic
solution. A conventional clean-in-place process follows this
pre-treatment step. A preferred acidic solution is an acid peroxide
solution. It has been found that a conventional clean-in-place
process using an alkaline detergent after the acidic pre-treatment
step provides particularly effective results. The concentration of
the active ingredients in an acidic pre-treatment solution for some
applications is at least 0.1% and usually at least 0.6%.
[0014] In another aspect, the invention is directed to a method
that includes pre-treating the soiled surfaces with a strong
alkaline solution. A conventional clean-in-place process follows
this pre-treatment step. It has been found that a conventional
clean-in-place process using an acidic detergent after the strong
alkaline pre-treatment step provides particularly effective
results.
[0015] Either of the pre-treatments, either acidic or alkaline, may
include a penetrant. The addition of a penetrant improves the
degree of softening of the soil, and thus facilitates the removal
of the soil. The concentration of penetrant in a pre-treatment
solution is at least 0.01 and usually at least 0.15%. A
concentration of about 1% is acceptable.
[0016] In another aspect, the invention is directed to a method
that includes pre-treating the soiled surfaces with a penetrant,
without the presence of appreciable amounts of acid or alkaline. A
conventional clean-in-place process follows this penetrant
pre-treatment step. Here, the concentration of penetrant in the
pre-treatment solution (without acid or alkalinity) is at least
0.01% and usually is at least 0.15%. In one particular embodiment,
the penetrant pre-treatment solution comprises approximately 0.9%
of solvents; other levels of solvents as penetrants are
suitable.
[0017] In one particular embodiment, the invention is a method of
cleaning soils from industrial equipment using a CIP process. The
method includes applying a pre-treatment solution to the soil, the
solution comprising at least 0.25 wt-% active ingredients, with the
active ingredients including any of an alkaline source, an acidic
source, a penetrant, an oxidizer, and a builder. The method also
includes recirculating a first CIP solution through the equipment
after the pre-treatment solution, the CIP solution comprising a
dilute detergent and then rinsing the equipment. The pre-treatment
solution can have 0.25 to 1.5 wt-% acid and/or 0.01 to 1 wt-%
oxidant, such as a peroxide. A penetrant, such as glycol ether, may
be present at 0.4 to 10 wt-%.
[0018] In another particular embodiment, the method includes
pre-treating the soil with a pre-treatment solution comprising at
least 0.5 wt-% active ingredients, the active ingredients including
any of an alkaline source, an acidic source, a penetrant, an
oxidizer, a surfactant, and a builder, removing at least a portion
of the penetrated soil with a dilute detergent solution, and
rinsing the equipment. In some embodiments, the pre-treatment
solution includes an alkaline source and the dilute detergent
includes an acid. In other embodiments, the pre-treatment solution
includes an acid source and the dilute detergent is alkaline.
[0019] The present invention includes using two different CIP
solutions.
[0020] These and other embodiments will be apparent to these of
skill in the art and others in view of the following detailed
description. It should be understood, however, that this summary
and the detailed description illustrate only some examples, and are
not intended to be limiting to the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a schematic diagram of an industrial process that
includes equipment to be cleaned, CIP process equipment, and
pre-treatment equipment.
DETAILED DESCRIPTION OF THE INVENTION
[0022] The present invention is directed to cleaning of industrial
equipment using a pre-treatment step in combination with
clean-in-place procedures. Use of a pre-treatment step, in
combination with conventional clean-in-place solutions and
processes, provides increased soil removal than the conventional
process alone. Additionally, use of a pre-treatment step, followed
by a water rinse, provided unexpected amounts of soil removal. Use
of a pre-treatment step allows the use of traditionally
incompatible chemistries and at higher concentrations then applied
in conventional cleaning programs.
[0023] As used herein, "weight percent", "wt-%", "percent by
weight", "% by weight", and variations thereof refer to the
concentration of a substance as the weight of that substance
divided by the total weight of the composition and multiplied by
100. It is understood that, as used here, "percent", "%", and the
like are intended to be synonymous with "weight percent", "wt-%",
etc.
[0024] As used herein, the term "about" refers to variation in the
numerical quantity that can occur, for example, through typical
measuring and liquid handling procedures used for making
concentrates or use solutions in the real world; through
inadvertent error in these procedures; through differences in the
manufacture, source, or purity of the ingredients used to make the
compositions or carry out the methods; and the like. The term
"about" also encompasses amounts that differ due to different
equilibrium conditions for a composition resulting from a
particular initial mixture. Whether or not modified by the term
"about", the claims include equivalents to the quantities.
[0025] It should be noted that, as used in this specification and
the appended claims, the singular forms "a," "an" and "the" include
plural referents unless the content clearly dictates otherwise.
Thus, for example, reference to a composition containing "a
compound" includes having two or more compounds. It should also be
noted that the term "or" is generally employed in its sense
including "and/or" unless the content clearly dictates
otherwise.
[0026] The method of the present invention applies to equipment
generally cleaned using clean-in-place (i.e., CIP) cleaning
procedures. Examples of such equipment include evaporators, heat
exchangers (including tube-in-tube exchangers, direct steam
injection, and plate-in-frame exchangers), heating coils (including
steam, flame or heat transfer fluid heated) re-crystallizers, pan
crystallizers, spray dryers, drum dryers, and tanks. This method
can be used in generally any application where caked on soil or
burned on soil, such as proteins or carbohydrates, needs to be
removed; applications include the food and beverage industry
(especially dairy), brewing, oil processing, industrial agriculture
and ethanol processing.
[0027] CIP processing is generally well-known. The process includes
applying a dilute solution (typically about 0.5-3%) onto the
surface to be cleaned. The solution flows across the surface (3 to
6 feet/second), slowly removing the soil. Either new solution is
re-applied to the surface, or the same solution is recirculated and
re-applied to the surface.
[0028] A typical CIP process to remove a soil (including organic,
inorganic or a mixture of the two components) includes at least
three steps: an alkaline solution wash, an acid solution wash, and
then a fresh water rinse. The alkaline solution softens the soils
and removes the organic alkaline soluble soils. The subsequent acid
solution removes mineral soils left behind by the alkaline cleaning
step. The strength of the alkaline and acid solutions and the
duration of the cleaning steps are typically dependent on the
durability of the soil. The water rinse removes any residual
solution and soils, and cleans the surface prior to the equipment
being returned on-line. The present invention provides a
pre-treatment step, prior to the CIP process, which penetrates into
the soil. The penetrating materials soften the soil, act as a
catalyst, or otherwise enhance the activity of the conventional CIP
solution when it contacts the soil. Thus, the pre-treatment
facilitates the soil removal.
[0029] Referring now to FIG. 1, a schematic diagram of process
equipment is illustrated at reference numeral 10. Process 10
includes a tank 20, which is the equipment to be cleaned. A feed
line 25 supplies the various cleaning solutions to tank 20, and a
drain line 27 removes solution from tank 20. Operably connected via
appropriate pipes, valves, pumps, etc. is equipment for a CIP
process, designated as reference numeral 30. CIP process 30
includes a tank 35 for retaining the dilute CIP chemistry. Drain
line 27 from tank 20 is used to recirculate solution from tank 20
back to CIP process 30 and tank 35. Process 10 also includes
equipment for the pre-treatment process, designated as reference
numeral 40. Pre-treatment equipment 40 includes a first tank 42 and
a second tank 44. When two tanks are used, generally one tank,
e.g., tank 42, will contain an alkaline pre-treatment and the other
tank, e.g., tank 44, will contain an acidic pre-treatment. The
appropriate pipes, valves, pumps, etc. are in place for operably
connecting tanks 42, 44 with feed line 25 into tank 20. This set-up
of process 10 allows a pre-treatment to be applied to tank 20
without the use of large amounts of additional equipment, such as
piping. Additional details regarding the method of cleaning tank 20
is described below.
[0030] The Pre-Treatment Solution
[0031] As described above, the pre-treatment solution or
pre-treatment step is applied to the soil prior to the application
of conventional CIP chemistries. The chemistry of the pre-treatment
solution is selected to facilitate removal of the soils on the
surfaces to be cleaned. The pre-treatment solution pre-coats and
penetrates into the soil, softening the soil. The specific
chemistry used can be selected based on the soil to be removed. The
chemistry used can be compatible with the CIP chemistry. In some
embodiments, it is desired to have a pre-treatment that is
incompatible with the CIP chemistry; in such instances, the
pre-treatment reacts with the CIP chemistry. It has been found that
using incompatible chemistries further increases the soil-removal
effectiveness.
[0032] The pre-treatment solution comprises 0.25% of active
ingredients, in some cases at least 0.5%, preferably at least 2%
and more preferably at least 3%. By use of the term "active
ingredients" what is intended is the non-inert ingredients that
facilitate the softening, dissolving and removal of soil. These
active ingredients include any alkaline/base, acid, penetrant
(including surfactant), builder, oxidizer, catalyst and chelant or
chelating agent. In most embodiments, water is the remainder of the
solution. Typically, the solution has no more than about 15% active
ingredients, preferably no more than about 10%. For most
applications, a concentration of about 1-10% is preferred; a
concentration of about 1-3% is suitable for most applications.
[0033] Alkaline or Acidic Ingredients
[0034] The pre-treatment solution optionally and preferably
includes alkaline or acidic ingredients. Examples of suitable
alkaline sources include basic salts, amines, alkanol amines,
carbonates and silicates. Particularly preferred alkaline sources
include NaOH (sodium hydroxide), KOH (potassium hydroxide), TEA
(triethanol amine), DEA (diethanol amine), MEA (monoethanolamine),
sodium carbonate, and morpholine, sodium metasilicate and potassium
silicate.
[0035] Examples of suitable acidic sources include mineral acids
(such as phosphoric acid, nitric acid, sulfuric acid), and organic
acids (such as lactic acid, acetic acid, hydroxyacetic acid, citric
acid, glutamic acid, glutaric acid, and gluconic acid).
[0036] The amount of alkaline or acid in the pre-treatment solution
in some cases is at least 0.25 wt-% and no greater than 10 wt-%.
Suitable levels of alkaline or acid include 2 to 5 wt-% and 0.5 to
1.5 wt-%.
[0037] Penetrants
[0038] A penetrant may be present in the pre-treatment solution.
The penetrant may be combined with an alkaline or acid source in
the solution, or, the penetrant may be used without an alkaline or
acid source. Preferably, the penetrant is water miscible.
[0039] Examples of suitable penetrants include alcohols, short
chain ethoxylated alcohols and phenol (having 1-6 ethoxylate
groups). Organic solvents are also suitable penetrants. Examples of
suitable organic solvents, for use as a penetrant, include esters,
ethers, ketones, amines, and nitrated and chlorinated
hydrocarbons.
[0040] Another preferred class of penetrants is ethoxylated
alcohols. Examples of ethoxylated alcohols include alkyl, aryl, and
alkylaryl alkloxylates. These alkloxylates can be further modified
by capping with chlorine-, bromine-, benzyl-, methyl-, ethyl-,
propyl-, butyl- and alkyl-groups. A preferred level of ethoxylated
alcohols in the solution is 1 to 20 wt-%.
[0041] Another class of penetrants is fatty acids. Some
non-limiting examples of fatty acids are C.sub.6 to C.sub.12
straight or branched fatty acids. Preferred fatty acids are liquid
at room temperature.
[0042] Another class of preferred solvents for use as penetrants is
glycol ethers, which are water soluble. Examples of glycol ethers
include dipropylene glycol methyl ether (available under the trade
designation DOWANOL DPM from Dow Chemical Co.), diethylene glycol
methyl ether (available under the trade designation DOWANOL DM from
Dow Chemical Co.), propylene glycol methyl ether (available under
the trade designation DOWANOL PM from Dow Chemical Co.), and
ethylene glycol monobutyl ether (available under the trade
designation DOWANOL EB from Dow Chemical Co.). A preferred level of
glycol ether in the solution is 0.5 to 20 wt-%.
[0043] Surfactants also are a suitable penetrant for use in the
pre-treatment solution. Examples of suitable surfactants include
nonionic, cationic, and anionic surfactants. Nonionic surfactants
are preferred. Nonionic surfactants improve soil removal and can
reduce the contact angle of the solution on the surface being
treated. Examples of suitable nonionic surfactants include alkyl-,
aryl-, and arylalkyl-, alkoxylates, alkylpolyglycosides and their
derivatives, amines and their derivatives, and amides and their
derivatives. Additional useful nonionic surfactants include those
having a polyalkylene oxide polymer as a portion of the surfactant
molecule. Such nonionic surfactants include, for example,
chlorine-, benzyl-, methyl-, ethyl-, propyl-, butyl- and other like
alkyl-capped polyoxyethylene and/or polyoxypropylene glycol ethers
of fatty alcohols; polyalkylene oxide free nonionics such as alkyl
polyglycosides; sorbitan and sucrose esters and their ethoxylates;
alkoxylated ethylene diamine; carboxylic acid esters such as
glycerol esters, polyoxyethylene esters, ethoxylated and glycol
esters of fatty acids, and the like; carboxylic amides such as
diethanolamine condensates, monoalkanolamine condensates,
polyoxyethylene fatty acid amides, and the like; and ethoxylated
amines and ether amines and other like nonionic compounds. Silicone
surfactants can also be used.
[0044] Additional suitable nonionic surfactants having a
polyalkylene oxide polymer portion include nonionic surfactants of
C.sub.6-C.sub.24 alcohol ethoxylates having 1 to about 20 ethylene
oxide groups; C.sub.6-C.sub.24 alkylphenol ethoxylates having 1 to
about 100 ethylene oxide groups; C.sub.6-C.sub.24
alkylpolyglycosides having 1 to about 20 glycoside groups;
C.sub.6-C.sub.24 fatty acid ester ethoxylates, propoxylates or
glycerides; and C.sub.4-C.sub.24 mono or dialkanolamides.
[0045] If a surfactant is used as a penetrant, the amount of
surfactant in the pre-treatment solution is typically at least
0.25%. Acceptable levels of surfactant include 0.4 to 8 wt-%, and 1
to 4 wt-%.
[0046] Overall, when an alkaline or acid source is present, the
amount of penetrant in the pre-treatment solution is at least 0.2
wt-% and no greater than 2.5 wt-%. Acceptable levels of penetrant,
when an alkaline or acid source is present, include 0.4-2 wt-%; 1-2
wt-% is preferred. The amount of penetrant, in relation to any
alkaline or acid source when present, is generally 1:1 to 1:5.
[0047] For pre-treatment solutions without an alkaline or acid
source, the amount of penetrant in the solution is at least 0.05
wt-% and no greater than 50%. Generally, the level is 0.1 to 25
wt-%. Acceptable levels of penetrant include 0.5 to 10 wt-%, and 1
to 5 wt-%.
[0048] Oxidizers
[0049] Pre-treatment solutions may include an oxidizing agent or an
oxidizer, such as a peroxide or peroxyacid. The resulting solution
is very effective against protein and starch soils. Further,
reaction of these oxygen compounds with the soil, especially when
combined with an alkaline source, creates vigorous mechanical
action on and within the soil, which enhances removal of the soil
beyond that caused by the chemical and bleaching action.
[0050] Suitable ingredients are oxidants such as chlorites,
bromine, bromates, bromine monochloride, iodine, iodine
monochloride, iodates, permanganates, nitrates, nitric acid,
borates, perborates, and gaseous oxidants such as ozone, oxygen,
chlorine dioxide, chlorine, sulfur dioxide and derivatives thereof.
Peroxygen compounds, which include peroxides and various
percarboxylic acids, including percarbonates, are suitable.
[0051] Peroxycarboxylic (or percarboxylic) acids generally have the
formula R(CO.sub.3H).sub.n, where, for example, R is an alkyl,
arylalkyl, cycloalkyl, aromatic, or heterocyclic group, and n is
one, two, or three, and named by prefixing the parent acid with
peroxy. The R group can be saturated or unsaturated as well as
substituted or unsubstituted. Medium chain peroxycarboxylic (or
percarboxylic) acids can have the formula R(CO.sub.3H).sub.n, where
R is a C.sub.5-C.sub.11 alkyl group, a C.sub.5-C.sub.11 cycloalkyl,
a C.sub.5-C.sub.11 arylalkyl group, C.sub.5-C.sub.11 aryl group, or
a C.sub.5-C.sub.11 heterocyclic group; and n is one, two, or three.
Short chain fatty acids can have the formula R(CO.sub.3H).sub.n
where R is C.sub.1-C.sub.4 and n is one, two, or three.
[0052] Some peroxycarboxylic acids include peroxypentanoic,
peroxyhexanoic, peroxyheptanoic, peroxyoctanoic, peroxynonanoic,
peroxyisononanoic, peroxydecanoic, peroxyundecanoic,
peroxydodecanoic, peroxyascorbic, peroxyadipic, peroxycitric,
peroxypimelic, or peroxysuberic acid, mixtures thereof, or the
like.
[0053] Branched chain peroxycarboxylic acid include
peroxyisopentanoic, peroxyisononanoic, peroxyisohexanoic,
peroxyisoheptanoic, peroxyisooctanoic, peroxyisonananoic,
peroxyisodecanoic, peroxyisoundecanoic, peroxyisododecanoic,
peroxyneopentanoic, peroxyneohexanoic, peroxyneoheptanoic,
peroxyneooctanoic, peroxyneononanoic, peroxyneodecanoic,
peroxyneoundecanoic, peroxyneododecanoic, mixtures thereof, or the
like.
[0054] Typical peroxygen compounds include hydrogen peroxide
(H.sub.2O.sub.2), peracetic acid, peroctanoic acid, a persulphate,
a perborate, or a percarbonate.
[0055] The amount of oxidant in the pre-treatment solution is at
least 0.01 wt-% and no greater than 1 wt-%. Acceptable levels of
oxidant are 0.01 to 0.50 wt-%; 0.3 wt-% is a particularly suitable
level. Suitable levels of oxidant, in relation to any acid source,
are generally 1:1 to 1:10, 1:3 to 1:7, or 1:20 to 1:50. Solutions
of 0.25 wt-% to 10 wt-% phosphoric acid with 50-5000 ppm (0.005
wt-% to 0.5 wt-%) hydrogen peroxide are particularly suitable. An
example pre-treatment solution includes 0.75 wt-% phosphoric acid
and 500 ppm (0.05 wt-%) hydrogen peroxide, which is a 1:15 ratio of
oxidant:acid.
[0056] Builders
[0057] The pre-treatment solution preferably includes a builder.
Builders include chelating agents (chelators), sequestering agents
(sequestrants), detergent builders, and the like. The builder often
stabilizes the composition or solution. Examples of builders
include phosphonic acids and phosphonates, phosphates,
aminocarboxylates and their derivatives, pyrophosphates,
polyphosphates, ethylenediamene and ethylenetriamene derivatives,
hydroxyacids, and mono-, di-, and tri-carboxylates and their
corresponding acids. Other builders include aluminosilicates,
nitroloacetates and their derivatives, and mixtures thereof. Still
other builders include aminocarboxylates, including salts of
ethylenediaminetetraacetic acid (EDTA),
hydroxyethylenediaminetetraacetic acid (HEDTA), and
diethylenetriaminepentaacetic acid. Preferred builders are water
soluble.
[0058] Particularly preferred builders include EDTA (including
tetra sodium EDTA), TKPP (tripotassium polyphosphate), PAA
(polyacrylic acid) and its salts, phosphonobutane carboxylic acid,
and sodium gluconate.
[0059] The amount of builder in the pre-treatment solution, if
present, is typically at least 0.25 wt-% and no greater than 5
wt-%. Acceptable levels of builder include 0.5 to 1.0 wt-% and 1
wt-% to 2.5 wt-%.
[0060] Methods of Pre-Treating
[0061] The method of the present invention is directed to applying
the pre-treatment solution to the surface to be cleaned, prior to a
conventional CIP process. The resulting CIP process requires less
steps and/or less time for each step. For example, a conventional
CIP process includes five steps after an initial water rinse: a
conventional alkaline (NaOH) wash to remove soil, an interim rinse,
a conventional acid wash to remove minerals and scale, a water
rinse, and a conventional sanitizing step. This process can be
replaced with a three-step process after the initial water rinse: A
pre-treatment step, a conventional wash, and a water rinse.
[0062] By using either of the two pre-treatment processes described
immediately above, the amount of water used in the overall cleaning
process with pre-treatment is reduced by about 30% or more compared
to the conventional five-step process. The amount of time for the
overall process with pre-treatment is reduced by about 30% or more
compared to the conventional five-step process. The specific number
of steps, the water usage, or the processing time reduced will
depend on the concentration and chemistry of the pre-treatment
solution.
[0063] Referring again to FIG. 1, pre-treatment solution is stored
at the equipment designated as 40. In this process 10, tank 42
holds an alkaline pre-treatment solution and tank 44 holds an
acidic pre-treatment solution that includes peroxide.
[0064] To clean 20, tank 20 and its connection lines are drained of
any product that may be present. A water rinse may be included to
remove any residual product. In one embodiment, alkaline
pre-treatment solution from tank 42 is pumped via piping and feed
line 25 into tank 20. Conventional CIP application equipment, such
as a spray head, applies the pre-treatment solution onto the
interior surface of tank 20. The pre-treatment solution cascades or
otherwise flows down the surface of tank 20, softening the soil. A
second application of pre-treatment solution may be applied,
although this is not generally needed.
[0065] After application and draining of the pre-treatment
solution, a conventional CIP process, using the detergent from
process 30 and tank 35, is performed. The CIP detergent may be
acidic or alkaline. Detergent from tank 35 is recirculated through
tank 20 via feed line 25, return line 27, and other appropriate
piping.
[0066] In another embodiment, a pre-treatment solution containing
hydrogen peroxide from tank 44 is pumped via piping and feed line
25 into tank 20. After application and draining of the peroxide
pre-treatment solution, a conventional CIP process, using an
alkaline detergent such as sodium hydroxide, from process 30 and
tank 35, is performed. The sodium hydroxide activates any residual
peroxide on the walls of tank 20.
[0067] When introducing the pre-treatment solution into the CIP
process, it may be beneficial to add the pre-treatment solution at
specific places depending on the piece of equipment. For example,
when treating an HTST pasteurizer, it is preferable to introduce
the pre-treatment solution at the feed balance tank. Alternatively,
the pre-treatment solution can be introduced on the suction side of
the booster pump or at the T or valve location just prior to plate
assembly. When treating a UHT pasteurizer, it is preferable to
introduce the pre-treatment solution at the water balance tank.
Alternatively, the pre-treatment solution can be introduced at the
product balance or feed tank, or the suction side of the booster
pump. When treating an evaporator, it is preferable to introduce
the pre-treatment solution on the suction side of the effect
recirculation pump. Alternatively, the pre-treatment solution can
be introduced at the CIP balance tank. Finally, when treating a
beer distillation re-boiler, it is preferable to introduce the
pre-treatment solution on the suction side of the boiler
recirculation pump. Alternatively, the pre-treatment solution can
be introduced in the valves between recirculation pump and the
distillation column, or the CIP balance tank. The pre-treatment
solution is preferably injected closer to the surface to be
cleaned. This allows for higher chemical concentrations by avoiding
dilution of the pre-treatment chemistry by the entire volume of the
CIP supply tank and distribution lines.
[0068] Various generic examples of suitable pre-treatment steps are
provided below.
[0069] In one particular example, an alkaline pre-treatment
solution of 10 wt-% NaOH is sprayed onto the interior surfaces of a
holding tank and allowed to drain. After about 20 minutes, the CIP
process, having a 1% acidic solution, is initiated.
[0070] In a second particular example, an acidic pre-treatment
solution of 1 wt-% phosphoric acid is circulated onto the interior
surfaces of a plate-in-frame heat exchanger. The solution includes
0.1 wt-% H.sub.2O.sub.2. The peroxide is also catalytically
activated by a subsequent conventional alkaline CIP solution which
causes further effervescence, formation of high oxidation potential
species, and soil removal.
[0071] In a third particular example, an acidic pre-treatment
solution, having about 1.0 wt-% mineral acids and 1.0 wt-% solvent
penetrant, is circulated onto the heat exchanging surfaces of an
evaporator and drained from the surface. After about 20 minutes,
the CIP process is initiated. A conventional alkaline wash, approx.
0.5 wt-% active NaOH, is fed into the evaporator. The alkaline
reacts with any acidic residue, generating heat and mechanical
action furthering the removal of the soil.
[0072] While the present invention has been discussed primarily in
the context of cleaning surfaces having food and beverage soils, it
is understood that the invention may be used in applications
needing cleaning in general including membranes such as
spiral-bound membranes, flat shut ceramic membranes used for water
filtration or desalinization and heat exchanges surfaces in the
chemical and pharmaceutical industries.
[0073] For a more complete understanding of the invention, the
following examples are given to illustrate some embodiments. These
examples and experiments are to be understood as illustrative and
not limiting. All parts are by weight, except where it is
contrarily indicated.
EXAMPLES
Example 1
Test Procedure
[0074] Solid milk pellets were prepared by mixing 3 grams of dry
milk power and 3 grams of soil. The resulting mix was pressed in a
die for 30 seconds at 10,000 lb, and then more pressure was added
to again apply 10,000 lb for 30 additional seconds. The pellets
were placed in screens and immersed in the pre-treatment solutions,
described below, for 5 minutes, removed, and then drained for 5
minutes. The screen and dried pellets were placed in a beaker of
0.5 wt-% NaOH at 120.degree. F. (The test designated as "None" had
no pre-treatment step; the test designated as "None *" had no
pre-treatment step and used a 3.0% NaOH cleaning at 120.degree. F.,
rather than the 0.5% NaOH). The beakers were placed on a hot plate
set to 49.degree. C. (approx. 120.degree. F.) with large stir bars
rotating at 350 rpm. After 30 minutes, the screen and pellets were
removed from the cleaning solution and gently immersed in and
removed from deionized water five times, and then dried overnight
in a 50.degree. C. oven. The results of the testing are below.
Pre-Treatment 1
[0075] A 10 wt-% solution of active NaOH was prepared and used as a
pre-treatment. The pre-treatment had 100,000 ppm sodium hydroxide
(an alkaline cleaner).
Pre-Treatment 2
[0076] A pre-treatment solution was prepared having 1360 ppm tetra
sodium EDTA (a builder and/or chelant), 3000 ppm sodium gluconate
(a builder and/or chelant), 2400 ppm potassium silicate (an
alkaline cleaner), 7000 ppm alkyl polyglycoside (a surfactant), and
4200 ppm potassium hydroxide (an alkaline cleaner). This
Pre-Treatment 2 had 3.66% alkaline, 0.43% builder/chelant, and 0.7%
surfactant, providing 4.79% active ingredients.
Pre-Treatment 3
[0077] A pre-treatment solution was prepared having 41550 ppm
polycarboxylated alcohol ethoxylate (a surfactant), 9540 ppm octyl
amine oxide (a surfactant), 25500 ppm alkyl polyglycoside (a
surfactant), and 4150 ppm 2-ethylhexanol ethoxylate (a penetrant).
This Pre-Treatment 3 had 0.4% penetrant and 7.6% surfactant,
providing 8% active ingredients.
Pre-Treatment 4
[0078] A pre-treatment solution was prepared having 1600 pm
potassium hydroxide (an alkaline cleaner), 9465 ppm sodium
hydroxide (an alkaline cleaner), 18500 ppm polyacrylic acid (a
builder and/or chelant), and 4625 ppm phosphonobutane tricarboxylic
acid (a builder and/or chelant). This Pre-Treatment 4 had 1.10%
alkaline and 2.3% builder/chelant, providing 2.9% active
ingredients. TABLE-US-00001 screen + screen + Pre- pellet wt,
pellet wt, pellet wt pellet wt % wt Treatment Screen before after
before after loss of solution wt (g) clean (g) clean (g) clean (g)
clean (g) pellet 1 18.23 23.93 22.59 5.70 4.36 23.51% 1 18.20 23.86
22.52 5.66 4.32 23.67% 2 18.23 23.91 22.54 5.68 4.31 24.12% 2 18.02
23.34 22.08 5.32 4.06 23.68% 3 19.24 24.70 22.14 5.46 2.90 46.89% 3
18.06 23.67 21.19 5.61 3.13 44.21% 4 17.95 23.50 20.09 5.55 2.14
61.44% 4 18.22 23.90 21.69 5.68 3.47 38.91% None 19.16 24.81 23.22
5.65 4.06 28.14% None 13.47 18.76 17.22 5.29 3.75 29.11% None *
19.27 25.01 24.14 5.74 4.87 15.16% None * 18.15 23.82 23.02 5.67
4.87 14.11%
[0079] The results show both consistency within the cleaning
processes and differences when comparing the methods. The results
indicate that lower levels of NaOH are better than higher levels,
and that pre-treatment solutions 3 and 4 are superior to
pre-treatment solutions 1 and 2. This difference, however, may be
due to the test procedure used. Tests 1 and 2 were done on one hot
plate whereas tests 3 and 4 were done on a second hot plate. It is
possible that these two hot plates were not equal at maintaining
the 120.degree. F. temperature.
[0080] A drastic difference was seen between the duplicate tests
(i.e., 61% and 39% for solution 4); it is possible that one of the
pellets had a crack in it, providing a weak location for the pellet
to break. The high exposed surface area would result in an increase
rate if disintegration.
[0081] The tests were rerun on the same hotplate in an attempt to
determine if there was any inconsistency between temperature
control of the hotplates. The results are provided in the table
below, under the column designated "% wt loss of pellet with
pre-treat".
[0082] As an alternative, and comparative method, 1 gram of the
Pre-treatment solution were added to 315 grams of the 0.5% NaOH
cleaning solution. Thus, rather than applying the pre-treatment
chemistry as a separate step, the pre-treatment chemistry was added
to the cleaning solution. The results are provided in the table
below, under the column designated "% wt loss of pellet without
pre-treat". TABLE-US-00002 % wt loss of pellet % wt loss of pellet
Pre-treatment with pre-treat without pre-treat 1 22.16% 36.92% 2
23.90% 37.39% 3 41.96% 34.01% 4 50.17% 31.95%
[0083] The results indicate that eliminating the separate
pre-treatment step and adding the chemicals directly to the
cleaning solution increased the performance of the two less
effective solutions (1-10% NaOH; 2-10% KX-3108) and decreased the
performance of the two more effective solutions (3-10% Quadexx 400;
4-10% Quadexx 500). All of these results were better than if no
pre-treatment was present (which provided pellet loss of about
29%).
Example 2
Test Procedure
[0084] Soiled stainless steel test panels, having soil on one side,
were prepared by drying a mixture of mashed corn solids onto one
side of the panel in an oven at 120.degree. C. for 4 hours. The
soiled panels were then cleaned as described below.
[0085] For Test (I), with the pre-treatment step, 800 grams of
Pre-Treatment solution 5 were placed in a 1000 ml beaker. It had
been determined that approximately 1 gram of the pre-treatment
solution contacted and remained on the soiled panel. After a brief
dip in the pre-treatment, the panels were hung for 5 minutes in
ambient conditions. The dried panels were then placed in a 1000 ml
beaker which had 750 g of 40.degree. C. water with the soil side
down. After 30 minutes, the panels were gently immersed in and
removed from deionized water five times, and the panels were then
dried. The results of the testing are below.
[0086] For Test (TI), the test panels were not pre-treated, but
were cleaned in 750 g of 40.degree. C. water with 1 g Pre-Treatment
5 added to the water.
[0087] For Test (III) the test panels were not pre-treated, but
were cleaned in 750 g of 40.degree. C. water.
Pre-Treatment 5
[0088] A pre-treatment solution was prepared having 400 ppm tetra
sodium EDTA (a builder and/or chelant), 4500 ppm tri potassium
polyphosphate (a builder and/or chelant), 3852 ppm potassium
hydroxide (an alkaline cleaner), 3000 ppm polyethylene phenol ether
phosphate (a surfactant), 1000 ppm sodium metasilicate (an alkaline
cleaner), 9000 ppm ethylene glycol monobutyl ether (a penetrant),
and 2400 ppm sodium xylene sulfonate (a surfactant). This
Pre-Treatment 5 had 0.5% alkaline, 0.5% builder/chelant, 0.5%
surfactant, and 0.9% penetrant, providing 2.4% active ingredients.
TABLE-US-00003 Test Method average % soil removed I 99.12% (average
of three tests) II 14.14% (average of three tests) III 14.12%
(average of two tests)
[0089] The results above show that merely adding the pre-treatment
chemistry to the wash solution, does not improve the soil removal
from the test panels. Rather, separated and step-wise application
of the pre-treatment solution and the wash solution provides
improved soil removal.
Example 3
[0090] Example 3 tested the effectiveness of various different
pre-treatment and main wash chemistries on removing corn beer thin
stillage syrup. For this test, the corn beer thin stillage syrup
soil was prepared by weighing 3 inch by 5 inch stainless steel
screens. A mixture of 85% corn beer thin stillage syrup and 15%
deionized water was prepared and the screens were dipped in the
mixture and set aside to drain the excess for 10 minutes. The
screens were then baked at 125.degree. C. for 2 hours. The screens
were re-dipped and baked another 2 times for a total of 3 times.
The final screens were weighed again. For cleaning, 1000 mL of the
chemical cleaning solutions in Table 1 were heated to 180.degree.
F. The screens were inserted into the cleaning solution. A stir bar
was in the cleaning solution and set at 400 rpm for the entire test
(30 minutes). After 30 minutes, the screens were removed and
allowed to dry before weighing. The percent soil removal was
calculated using the following formula: Soiled .times. .times. wt -
After .times. .times. wt Soiled .times. .times. wt - virgin .times.
.times. wt .times. 100 = % .times. .times. Soil .times. .times.
Removal ##EQU1##
[0091] Table 1 shows the percent soil removal of various
pre-treatment and main wash chemistries. TABLE-US-00004 TABLE 1
Pre-treatment Solution Effectiveness On Corn Beer Thin Stillage
Syrup 15 Min CIP Exp 15 Min Pre-treatment Chemistry Percent Main
Wash Percent % Soil # Chemistry Tradename % Chemistry % Removal 1
NaOH 3.00 -- -- 75.70 2 Na2CO3 2.00 -- -- 65.00 3 MEA (99%) 4.00
NaOH 3.00 75.00 4 DEA 4.00 NaOH 3.00 82.40 5 TEA 4.00 NaOH 3.00
79.50 6 Morpholine 4.00 NaOH 3.00 82.60 7 Cyclohexylamine 4.00 NaOH
3.00 84.50 8 n-Methyl Pyrolidone 4.00 NaOH 3.00 84.90 9
Monoisopropanol amine 4.00 NaOH 3.00 94.60 10 H.sub.2O.sub.2 0.50
NaOH 3.00 95.00 MEA (99%) 4.00 11 H.sub.2O.sub.2 0.50 NaOH 3.00
97.40 DEA 4.00 12 H.sub.2O.sub.2 0.50 NaOH 3.00 90.00 TEA 4.00 13
H.sub.2O.sub.2 0.50 NaOH 3.00 89.80 Morpholine 4.00 14
H.sub.2O.sub.2 0.50 NaOH 3.00 94.80 Cyclohexylamine 4.00 15
H.sub.2O.sub.2 0.50 NaOH 3.00 82.10 n-Methyl Pyrolidone 4.00 16
H.sub.2O.sub.2 0.50 NaOH 3.00 92.70 Monoisopropanol amine 4.00 17
H.sub.2O.sub.2 0.50 NaOH 3.00 94.90 18 Dowanol EB 4.00 NaOH 3.00
96.40 19 Dowanol DM 4.00 NaOH 3.00 84.60 20 Dowanol PnB 4.00 NaOH
3.00 97.00 21 Dowanol EpH 4.00 NaOH 3.00 80.20 22 Dowanol DpnP 4.00
NaOH 3.00 87.60 23 Dowanol PnP 4.00 NaOH 3.00 86.20 24 Dowanol PPh
4.00 NaOH 3.00 84.80 25 Propylene Carbonate 4.00 NaOH 3.00 71.90
Dowanol EB 4.00 26 H.sub.2O.sub.2 0.50 NaOH 3.00 92.00 Dowanol DM
4.00 27 H.sub.2O.sub.2 0.50 NaOH 3.00 96.50 Dowanol PnB 4.00 28
H.sub.2O.sub.2 0.50 NaOH 3.00 97.00 Dowanol EpH 4.00 29
H.sub.2O.sub.2 0.50 NaOH 3.00 94.20 Dowanol DpnP 4.00 30
H.sub.2O.sub.2 0.50 NaOH 3.00 99.00 Dowanol PnP 4.00 31
H.sub.2O.sub.2 0.50 NaOH 3.00 98.80 Dowanol PPh 4.00 32
H.sub.2O.sub.2 0.50 NaOH 3.00 99.20 Propylene Carbonate 4.00 33
H.sub.2O.sub.2 0.50 NaOH 3.00 88.4 34 Dequest 2000 4.00 NaOH 3.00
89.30 35 Dequest 2010 4.00 NaOH 3.00 86.20 36 EDTA 4.00 NaOH 3.00
89.20 37 STPP 4.00 NaOH 3.00 79.70 38 TKPP 4.00 NaOH 3.00 89.10 39
Sodium Gluconate 4.00 NaOH 3.00 89.50 Dequest 2000 4.00 40
H.sub.2O.sub.2 0.50 NaOH 3.00 95.30 Dequest 2010 4.00 41
H.sub.2O.sub.2 0.50 NaOH 3.00 94.10 EDTA 4.00 42 H.sub.2O.sub.2
0.50 NaOH 3.00 95.00 STPP 4.00 43 H.sub.2O.sub.2 0.50 NaOH 3.00
95.00 TKPP 4.00 44 H.sub.2O.sub.2 0.50 NaOH 3.00 97.00 Sodium
Gluconate 4.00 45 H.sub.2O.sub.2 0.50 NaOH 3.00 93.00
Example 4
[0092] Example 4 compared the ability of various oxidizers to
remove corn beer thin stillage syrup. For this example, the screens
were soiled with corn beer thin stillage syrup and cleaned as
described in Example 3. Table 2 shows the impact of various
oxidizers on soil removal. TABLE-US-00005 TABLE 2 Impact of
Oxidizers on Corn Beer Thin Stillage Syrup Removal Exp 15 Min Pre-
Percent 15 Min CIP Main Percent % Soil # treatment Chemistry % Wash
Chemistry % Removal 1 H.sub.2O.sub.2 0.50 NaOH 3.00 94.90 2 Sodium
Perborate 1.50 NaOH 3.00 96.40 3 Sodium Percarbonate 1.75 NaOH 3.00
82.80 4 Sodium Persulfate 3.38 NaOH 3.00 72.30 5 Potassium
Permanganate 1.12 NaOH 3.00 93.90
Example 5
[0093] Example 5 compared the amount of time it took to clean the
screens using the pre-treatment solutions of the present invention
compared to using only sodium hydroxide. This example tested the
time to clean on corn beer thin stillage syrup and whole milk soil.
The corn beer thin stillage syrup soil was prepared and cleaned as
described in Example 3.
[0094] For the whole milk soil, the soil was prepared by weighing
stainless steel discs to be soiled and affixing the disk to the
bottom of a 1.5 foot, 3 inch diameter stainless steel tube. A water
bath was heated to 205.degree. F. to 210.degree. F. and the tubes
with the discs were placed in the water bath. A 1/3 gallon of whole
milk was added to each tube used and allowed to sit for 4 hours.
After 4 hours, the disks were removed and allowed to dry for at
least 48 hours before weighing. When cleaning the whole milk soil,
the disc was affixed to an overhead stirrer. The desired cleaning
solution was heated to 180.degree. F. using a hot plate. The disc
was inserted into a 1 L beaker of cleaning solution for 10 minutes
and the overhead stirrer was set to 50 rpm. After 10 minutes, the
disc was removed from the cleaning solution and placed in a beaker
of deionized water. The overhead stirrer was set at 200 rpm for 30
seconds. The disc was removed and allowed to dry at least 48 hours
before weighing. The percent soil removal was calculated using the
following formula: Soiled .times. .times. wt - After .times.
.times. wt Soiled .times. .times. wt - virgin .times. .times. wt
.times. 100 = % .times. .times. Soil .times. .times. Removal
##EQU2##
[0095] Tables 3 and 4 show the time it took to remove 100% of the
soil on the screen or disc when using sodium hydroxide alone,
Stabicip Oxi pre-treatment followed by a sodium hydroxide wash, and
Formula A (74% hydrogen peroxide (35%), 9.75% sodium cumene
sulfonate (40%), 5.25% sodium octane sulfonate, 3.50%
hydroxyethylidene diphosphonic acid (60%), 3% methane sulfonic
acid, 1% n-butyl capped alcohol ethoxylate (5EO), and 3.5%
perlargonic acid) followed by a sodium hydroxide wash. Stabicip Oxi
is a hydrogen peroxide based composition commercially available
from Ecolab Inc. (St. Paul, Minn.). TABLE-US-00006 TABLE 3 Time to
Clean Corn Beer Thin Stillage Syrup Soil 15 Min Pre- 15 Min CIP
Time (Min) Exp treatment Percent Main Wash Percent to 100% Soil #
Chemistry % Chemistry % Removal 1 NaOH 2.00 -- -- 60 2 Stabicip Oxi
1.50 NaOH 2.00 30
[0096] Table 3 shows that including a hydrogen peroxide based
pre-treatment composition together with a sodium hydroxide wash
cuts the time to clean corn beer thin stillage syrup in half when
compared to a sodium hydroxide wash alone. TABLE-US-00007 TABLE 4
Time to Clean Whole Milk Soil 15 Min Pre- 15 Min CIP Time (Min) Exp
treatment Percent Main Wash Percent to 100% Soil # Chemistry %
Chemistry % Removal 1 NaOH 2.00 -- -- >60 min 2 Stabicip Oxi
1.50 NaOH 2.00 33 3 Formula A 1.50 NaOH 2.00 27
Table 4 shows that including a hydrogen peroxide based
pre-treatment composition together with a sodium hydroxide wash
cuts the time to clean whole milk soil in half when compared to a
sodium hydroxide wash alone. Using Formula A together with a sodium
hydroxide wash cuts the time to clean whole milk soil by more than
half when compared to sodium hydroxide wash alone.
Example 6
[0097] Example 6 tested the effectiveness of various different
pre-treatment and main wash chemistries on the removal of whole
milk soil. For this test, the whole milk soil was prepared and
cleaned as described in Example 5. Table 5 shows the percent
removal of the various combinations. TABLE-US-00008 TABLE 5
Pre-treatment Solution Effectiveness On Whole Milk 5 Min 5 Min CIP
Exp Pre-treatment Chemistry Percent Main Wash Percent % Soil #
Chemistry Tradename % Chemistry % Removal 1 NaOH 1.00 -- -- 37.90 2
MEA (99%) 0.50 -- -- 23.00 3 Dowanol EB 0.50 -- -- 9.70 4 HP Add 6
* 0.50 -- -- 10.80 5 Stabicip Oxi 0.50 -- -- 12.60 6 HNO.sub.3 0.50
-- -- 20.00 7 Dowanol EB 0.50 NaOH 1.00 34.50 8 Stabicip Oxi 0.50
NaOH 1.00 57.50 9 HP Add 6 * 0.50 NaOH 1.00 47.20 10 MEA (99%) 0.50
NaOH 1.00 41.80 11 HNO.sub.3 0.50 NaOH 1.00 49.20 12 MEA (99%) 0.50
H2O2 0.15 19.90
[0098] The invention has been described with reference to various
specific and preferred embodiments and techniques. However, it
should be understood that many variations and modifications may be
made while remaining within the spirit and scope of the
invention.
* * * * *