TREATMENT OF INDUSTRIAL WATER SYSTEMS
FIELD OF THE INVENTION
The invention pertains to treatment of water in an industrial water system. More
particularly, the invention pertains to control of treatment of water in an industrial water system.
BACKGROUND
Many industrial water systems, e.g., cooling towers, boilers, forming section of a paper
making process, and waste treatment systems use chemical treatment products for improved
energy efficiency, waste reduction, asset protection, and improve product quality. Typical
treatment products for industrial water systems control scaling, corrosion, fouling, foaming, odor
formation, and microbiological growth. These treatment products comprise polymers and other
materials and are known to people of ordinary skill in the art of a particular type of industrial
water system.
To achieve optimum performance from the chemical treatment products introduced into
an industrial water system requires a feed strategy. For example, a typical industrial water
system as used in cooling towers will employ a control system that can be set up to feed
treatment product based on either a bleed/feed mechanism, where the action of blowdown
triggers a chemical feed pump or valve that feeds treatment product; or, in the alternative, the
control system feeds treatment product based on timers using a "feeding schedule," or flow
meters on the make-up water line trigger the pumping of treatment product based on a certain
amount of make-up water being pumped. A limitation of these control methods is that none of
these systems measure the treatment product concentration directly online, so if there is a
mechanical problem, for example, if a pump fails, a drum empties, or high, low or unknown
blowdown occurs, system volume changes or makeup water quality changes; the correct
treatment product concentration is not maintained. Because this problem is common, typically
industrial water systems are either overfed to ensure the level of treatment product in the system
does not drop too low as a result of high variability in product dosage, or the treatment product is
unknowingly underfed. Both overfeeding and underfeeding of treatment product are undesirable
due to cost and performance drawbacks.
One method of combatting these undesirable drawbacks is by blending an additive blend
that includes an inert fluorescent chemical and an active ingredient blended in known proportion
to one another, adding the additive blend to the industrial water system, and monitoring the
fluorescent signal of the inert fluorescent chemical using a fluorometer. The typical industrial
water system may require several additive blends, which would make up an additive package.
As a person of skill in the art readily recognizes, the typical additive blend or package for an
industrial water system must first be formulated, then blended and inventoried prior to its
shipment and use by the end user. Because of the endless possible design variations of industrial
water systems, there may be as many additive blends and packages as there are industrial water
systems. Furthermore, a process can exhibit dynamic variations, e.g., changes in makeup water
composition that feeds a cooling tower, seasonal changes, etc., requiring reformulation of the
blend to achieve optimum performance. The typical industrial water system may require several
of these additive blends to function properly, and each can be properly dosed into the industrial
water system using a control apparatus such as TRASAR® Technology or 3D TRASAR®
Technology, each available fromNalco Company, 1601 West Diehl Road, Naperville, Illinois
60563. All of these additive blends are typically formulated using one or more of several
common raw materials.
Those who produce additive blends encounter several issues when blending ("makedown"
or "making-down") a new additive blend or package. First, the cost of formulating a new
additive blend or package can be expensive. Several batches may need to be blended and tested
to determine the optimal ratio of additives. Not only does the industrial water system require that
formulation be done when new, but the formulation will likely need adjusting as the system ages.
Such formulation and re-formulation requires significant man-hours.
Second, the make-down of additive blends and packages at full strength can be
dangerous. Several of the additives require the use of formulation aids such as strong acids or
bases in order to get the active ingredients to dissolve. The additives, when blended at full
strength, may release heat or fumes. Additionally, because the blend will likely sit in storage for
a lengthy period of time, the blend may require the addition of costly halogen- or photo-stable
dyes as tracers.
Systems for blending and feeding liquid chemicals are generally based on one or more
sensor technologies such as load cell, level sensor, and volumetric measuring devices to measure
the amount of chemical dispensed. In some cases a characteristic measurement of the liquid is
used to determine the mixture concentration. For example, U.S. Patent No. 5,522,660, to O'
Dougherty et al., disclosed the use of a conductivity probe to monitor the concentration blend of
DI water mixed with a concentrated chemical.
Further, U.S. Patent Application Publication No. 2009/0139545, to Rowlands et al,
discusses the use of fast acting solenoid values with a control algorithm to inject superconcentrated
chemicals into a water conduit for vehicle washing. The amount of chemical feed is
controlled by the solenoid valve on/off timing sequence. Concentrated chemical is injected
directly into the conduit and diluted at the point of use, thereby eliminating the need for a dilution
step or mixing tank.
Thus, there is a long-felt but unmet need for more efficient delivery of additives used in
industrial water systems than currently exists. Ideally, a service provider would avoid off-site
formulation and blending altogether by shipping the necessary raw materials to the customer and
performing the blending at the customer's site that can provide real-time adjustment and dosage
control. More ideally, the make-down would not require the use of halogen- or photo-stable
dyes. Even more ideally, the raw materials would be directly injected into the industrial water
system at optimum levels without the need for make-down. The invention at hand satisfies this
long-felt but unmet need.
SUMMARY OF THE INVENTION
The invention is directed toward a method for controlling treatment of an industrial water
system. The method comprises the following steps: providing an apparatus for controlling
delivery of at least one treatment chemical, the apparatus comprising at least one sensor and an
electronic input/output device carrying out a protocol; measuring a parameter of the industrial
water system using the at least one sensor; relaying the measured parameter to the electronic
device; adjusting the protocol based on the measured parameter; delivering a concentrated
treatment chemical into a stream of the industrial water system according to the adjusted
protocol, the concentrated treatment chemical comprising an active ingredient, the active
ingredient traced as necessary, the active ingredient having a concentration; repeating the
measuring, the adjusting, and the delivering; and optionally repeating the steps for n-number of
parameters, n-number of active ingredients, and/or n-number of concentrated treatment
chemicals.
These and other features and advantages of the present invention will be apparent from
the following detailed description, in conjunction with the figures and appended claims.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
The benefits and advantages of the present invention will become more readily apparent
to those of ordinary skill in the relevant art after reviewing the following detailed description and
accompanying drawings, wherein:
FIG. 1 is a schematic diagram of an embodiment of a batch active blending system for ncomponents;
FIG. 2 is a schematic diagram of an embodiment of a staged dispensing system using a
load cell for high resolution dispensing control;
FIG. 3 is a plot showing the integrated fluorescence signal intensity for poly acrylic acid
tagged dispersant ("THSP") at different concentrations in water;
FIG. 4 is a schematic diagram of an embodiment of a batch active blending system for ncomponents
using dedicated mixing tanks for component isolation; and
FIG. 5 is a schematic diagram of an embodiment of an active blending system for direct
injection into the process stream.
DETAILED DESCRIPTION OF THE INVENTION/PREFERRED EMBODIMENT
While the present invention is susceptible of embodiment in various forms, there is shown
in the drawings and will hereinafter be described a presently preferred embodiment with the
understanding that the present disclosure is to be considered an exemplification of the invention
and is not intended to limit the invention to the specific embodiment illustrated.
It should be further understood that the title of this section of this specification, namely,
"Detailed Description of the Invention," relates to a requirement of the United States Patent
Office, and does not imply, nor should be inferred to limit the subject matter disclosed herein.
Definitions:
For purposes of this patent application, the following terms have the definitions set forth
below:
"Additive" is used interchangeably with the terms "active ingredient" and "active."
Additionally, the term "concentrated active ingredient" refers to a chemical that has an additive
concentration that is significantly greater than what is employed in a typical package as defined
below. A concentrated active ingredient may take the form of a solid or liquid. A concentrated
active ingredient is typically "made down" prior to its use as a treatment in an industrial water
system. A concentrated active ingredient will typically contain no more than a minimal amount
of diluent so that the chemical's cost effectiveness can be maximized.
"As necessary" means if needed. For this patent application, "as necessary" refers to
chemicals that, if detected by fluorescence, do not display fluorescent properties. If a
measurement can be taken without the need for fluorescence detection, then the chemical will not
need to be traced. If a chemical fluoresces on its own, it does not need to be traced with a
fluorescing chemical. However, if a chemical does not fluoresce and a user wants to measure the
concentration of the non-fluorescing chemical using fluorescence, then the chemical needs to be
traced with a fluorescing chemical.
"Blend" means a chemical that has been created by diluting and/or mixing an additive
with another chemical and/or water.
"Industrial water system" means any system that circulates water as its primary
ingredient. Examples of "industrial water systems" may include cooling systems, heating
systems, membrane systems, paper making process or any other system that circulates water as
defined above.
"Metering" means dispensing a known quantity of a substance. One way to "meter" a
substance is to dispense a substance that has a known concentration of a particular ingredient at a
known rate for a period of time. Another way to "meter" a substance is to use analytic
technology to determine how much of a substance or an ingredient of a substance is/has been
dispensed. Other ways of "metering" are known to those skilled in the art.
"Modular reservoir" means a portable, interchangeable container capable of containing at
least one concentrated active ingredient. Ideally, a "modular reservoir" would be easily attached
and detached to a system employed to carry out the invention at hand, providing a safe,
sustainable, and convenient way to handle the at least one concentrated active ingredient.
"Package" means a group of one or more blends that are added to an industrial water
system. An "additive package" for an industrial water system typically includes several blends
of active ingredients, tracers, water, and other ingredients.
"Parameter" means a measurable variable that can be used to determine a treatment
protocol for a water treatment system. Examples of potential "parameters" include but are not
limited to the following: temperature, concentration (including pH and/or alkalinity),
fluorescence, surface area, metallurgy, and any other measurable variable known by those skilled
in the art.
"Protocol" means a set of instructions that may include concentrations, flow rates, mixing
rates, temperatures, volumes, masses, or any number of other criteria known to those skilled in
the art. As related to this invention, a "protocol" may control the mixing and/or injection of
treatment into the water of an industrial water system. A "protocol" can be created and/or stored
using an electronic input-output device, which may be a computer, a PLC controller, or any
input-output device programmed with the appropriate software and/or firmware, which
communicates the instructions to carry out the "protocol" in an automated fashion. Additionally,
the "protocol" includes optimization methods and techniques based on physical models,
empirical models, semi-empirical models, or a combination of models to develop a set of
instructions.
"Sensor" means a measurement device that measures a parameter and is capable of
outputting the measured parameter.
"Traced" means an inert fluorescent chemical mixed in a known proportion with an active
component of an additive package so that the concentration of the active component may be
determined via the use of a fluorometer to monitor the fluorescent signal of the inert fluorescent
chemical. For example, for a dye to be "traced" with another chemical, the dye will be present at
a measurable concentration with the other chemical so that the concentration of the dye may be
measured using the dye's fluorescence, allowing the concentration of the other chemical to be
determined.
"Water" means any substance that has water as a primary ingredient. Water may include
pure water, tap water, fresh water, brine, steam, and/or any chemical, solution, or blend that is
circulated in an industrial water system.
Using a measurement and/or control device such as 3D TRASAR Technology, a user can
determine a formulation for an additive blend or package that would suit the dynamic conditions
of the user's industrial water system. For example, the user may determine that a particular
industrial water system needs an additive package that comprises an azole, a dispersant polymer,
orthophosphate, phosphonobutanetricarboxylic acid ("PBTC"; optionally a salt thereof), and
phosphinosuccinic oligomer ("PSO"). An embodiment of the invention would determine the
optimal concentration of the ingredients of the additive package and dose the following raw
materials into a vessel: water, phosphoric acid traced with a dye, PBTC traced with a second dye,
tolyltriazole ("TT"), PSO traced with a third dye, and a tagged polymer dispersant. The
ingredients would be diluted with water and/or a solvent and mixed using one or more techniques
known by those skilled in the art. The user could determine the concentrations of the ingredients
by weight measurement, by a form of fluorescence or absorption detection, volumetric or level
sensing, or by any other method known to those skilled in the art.
The blended additive package is then injected as necessary into the industrial water
system by any method known to those skilled in the art. When the vessel becomes somewhat
depleted, the process could be repeated as necessary, beginning with determining the optimum
additive package composition.
Another example of an embodiment of the invention allows the active ingredients of an
additive package to be added directly into the industrial water system rather than by blending
prior to being added to the industrial water system. The embodiment is a method for controlling
treatment of an industrial water system. The method comprises the following steps: providing
an apparatus for controlling delivery of at least one treatment chemical, the apparatus comprising
at least one sensor and an electronic input/output device carrying out a protocol; measuring a
parameter of the industrial water system using the at least one sensor; relaying the measured
parameter to the electronic device; adjusting the protocol based on the measured parameter;
delivering a concentrated treatment chemical into a stream of the industrial water system
according to the adjusted protocol, the concentrated treatment chemical comprising an active
ingredient, the active ingredient traced as necessary, the active ingredient having a concentration;
repeating the measuring, the adjusting, and the delivering; and optionally repeating the steps for
n-number of parameters, n-number of active ingredients, and/or n-number of concentrated
treatment chemicals.
The active ingredients may be injected simultaneously with one or more fluorescing dye,
providing the ability to trace the concentration of the active ingredients. Using available
analytical tools such as conductivity, corrosion, and/or deposit monitoring in combination with
fluorescent tracing technology, the concentrations of active ingredients can be measured directly
or indirectly. These measurements allow for control and adjustment of the additive package.
For example, a scale control additive could be added to the industrial water system
directly based on real-time measurements linked to the demand of a tagged polymer using
fluorescence measurement and feedback control. The scale control additive could alternately use
a different measurement scheme to determine the concentration of scaling species, e.g., calcium
carbonate and/or calcium phosphate. Yellow metal corrosion inhibitor control could be
facilitated by direct azole fluorescence monitoring and feedback control. Ferrous metal corrosion
inhibitor control could be maintained by monitoring the concentration of the active ingredients of
the additive package in the industrial water system, or these inhibitors could be predicted using
key parameters of the system itself. Such parameters could include, for example, temperature,
pH, alkalinity, etc. Typical active ingredients that would need to be monitored would include
phosphinosuccinic oligomer and phosphate.
Optimal performance of the additive blend or dosage amount for direct injection is
possible by collecting data on the process and fluid characteristics to input into an optimization
algorithm for real-time active component adjustment. The optimization algorithm can be based
on a physical model, empirical model such as multiple regression, neural network, state space,
autoregressive, etc., or the combination of both physical and empirical models. As an example,
characteristic fluid input data for a cooling tower unit operation could include various
temperature readings (ambient , inlet, outlet, and basin), pH, alkalinity, conductivity, oxidationreduction
potential ("ORP"), turbidity, etc., all of which can be measured using standard
commercially available sensors. Combining this with input on the tower operating conditions
such as capacity, number of cycles, recirculation rate, wetted material composition, makeup
water quality, etc., and using model software, e.g., thermodynamic product saturation
calculations to predict mineral scale potential, an optimal additive blend and/or dosage level is
determined.
In formulating an additive blend the starting concentrated raw material can be either a
liquid or solid. Similarly, the starting material for direct injection of the active into the process
stream can be either a concentrated liquid or a dissolved solid. Use of solid raw materials has
the advantage of being easier to handle with less risk from spills as well as decrease shipping
costs through weight reduction. The solid can be either in pellet form or powder. Actives in the
solid form require the addition of water or other solvent to dissolve the solid forming a
concentrated liquid that can then be dispensed. A chemical tracing dye can be added separately
to the liquid concentrate or integrated into the active solid and released when dissolved in water
with the active. The concentration of the liquid active made by dissolving the solid is known
based on the mass of active solid used and volume of solvent added to dissolve the solid. Other
methods to determine the concentration can also be used such as optical spectroscopic methods,
pH, conductivity, etc. Once in the liquid state, blending follows the same methodology similar to
starting with a liquid concentrated active. Furthermore, an automated dispensing device for the
active solid can be used to maintain dispensing of the concentrated liquid active over long
periods. A combination of liquid and solid active may also be used. For example, if the
consumption of an active is high relative to the others and the dispensing volume size is limited,
then it may be desirable to use solid actives for ease in handling.
In an embodiment, the industrial water system is selected from the group consisting of: a
cooling tower water system; a petroleum well, a downhole formation, a geothermal well, and any
other oil field application; a boiler system; a hot water system; mineral process waters
comprising mineral washing, flotation and benefaction; a papermaking process; a black liquor
evaporator; a gas scrubber; an air washer; a continuous casting process; an air conditioning
system; a refrigeration system; a pasteurization process; a water reclamation system; a water
purification system; a membrane filtration water system; a food processing stream; and a
wastewater treatment system.
In an embodiment, the at least one sensor is selected from the group consisting of: optical
spectroscopic measurements such as fluorometric sensor , spectrofluorometric sensor, absorption,
and Raman spectroscopic measurement system; a corrosion sensor; a conductivity sensor; a pH
sensor; a temperature sensor; a weight sensor; a flow sensor; a load cell; a level detector; a
turbidity sensor; an electrical sensor; an electrochemical sensor; an acoustic sensor; multiples
thereof; combinations thereof; and multiples and combinations thereof.
In an embodiment, the parameter is selected from the group consisting of: a corrosion rate; a
scaling rate; a deposition rate; a heat transfer rate; a cooling tower efficiency; a chemical
concentration; a cycle of concentration; a suspended solids measurement; a dissolved solids
measurement; a microbiological activity rate; a chemical activity rate; a process performance
parameter; a product performance parameter; multiples thereof; combinations thereof; and
multiples and combinations thereof.
In an embodiment, the method further comprises diluting the concentrated treatment
chemical prior to the delivering. The diluting may occur in-stream en route to the delivering.
Such in-stream dilution may be carried out using technology such as Nalco Pareto technology,
available fromNalco, an Ecolab Company, 1601 West Diehl Road, Naperville, Illinois 60563, or
by a venturi with a mixing ratio based on the venture diameter and inlet orifice sizing such as
Chem-Flex injector technology from Hydra-Flex Inc., 680 East Travelers Trail, Burnsville, MN
55337.
In an embodiment, the concentrated treatment chemical is delivered as a solid.
In an embodiment, the concentrated treatment chemical is delivered as a liquid.
In an embodiment, the concentrated treatment chemical comprises at least two active
ingredients.
In an embodiment, the concentrated treatment chemical is further comprised of a dye, the
active ingredient traced with dye.
In an embodiment, the active ingredient is a polymer tagged with a fluorescent moiety.
In an embodiment, the active ingredient is inherently fluorescent.
In an embodiment, the apparatus further comprises a modular delivery system.
In an embodiment, the protocol comprises an algorithm based on calculations selected
from the group consisting of: a first principle; an empirical observation; multiples thereof;
combinations thereof; and multiples and combinations thereof. For example, the types of
algorithms may include, but are not limited to, the group consisting of: a cooling water
algorithm; a boiler water algorithm; a corrosion algorithm; a pH algorithm; a conductivity
algorithm; a temperature dependency algorithm; a turbidity algorithm; a water hardness
algorithm; a scaling algorithm; a heat transfer rate algorithm; a microbiological activity
algorithm; a chemical activity algorithm; a chemical demand algorithm; multiples thereof;
combinations thereof; and multiples and combinations thereof.
Examples:
The following examples are meant to illustrate several embodiments and aspects of the
invention at hand to a person of skill in the art. These examples are not to be construed as
limiting beyond the scope of the allowed claims. The examples are prophetic in nature, and those
skilled in the art will recognize that the features described in any single example can be
incorporated into any of the other examples as necessary.
Example 1:
The first example illustrates injection of the additive package made up from a set of
different actives blended in a holding vessel at a predetermined composition for a given batch.
Once the additive package is made it can then be dispensed into the process stream. The
composition of the additive package is adjusted during the blending step by controlling the
individual actives dispensed to the holding vessel. A schematic layout is shown in Figure 1 for
an n-component delivery system. The concentrated actives used in formulating the blend are
isolated from one another by containers 100, 101, 102, and n-container 103. The containers can
be any suitable material either hard wall or flexible, e.g., polymer bag, that is chemically
compatible with the concentrated active. The containers can be modular allowing the user to
easily remove and replace the container with the same or different active component, thus
providing added flexibility in the composition of the additive package. A blend is made by
extracting a controlled amount of active from the container through delivery line 104 using a
fluid dispensing device 105. The fluid dispensing device 105 used can be any technology
typically used for liquids that include but not limited to mechanical pumping, venturi injector,
gravity feed, or displacement methods that such as direct pressurizing the container ,bladder
system, or progressive cavity displacement .
The active fluid dispensed is sent to mixing tank 106 equipped with a level sensing
measurement device 108 and 109 that sends a signal to the controller 112 when tank 106 reaches
a targeted set point level such as empty, full, or at a critical level to trigger a change in fluid
dispensed. The level monitoring device can be a simple float type level switch mounted at
discrete locations on mixing tank 106 or an inductive float level sensor with multiple discrete
trigger points. Alternatively, an ultrasonic or other noncontact method can be used to measure
the level over a continuous range. Additional contact sensors or alarming signals from
noncontact level measurements can be used as means to monitor and control intermediate fluid
levels during the additive blend construction step. For example, it may be desirable to add water
or solvent to mixing tank 106 after dispensing an active fluid to dilute the active before the
addition of a second active component. The addition of water, solvent, or combination of fluids
is added to tank 106 through nozzle 107. Nozzle 107 can be located above the fluid level in the
mixing tank 106 or positioned at the bottom or side of the mixing tank and may include an
educator nozzle to promote turbulence for enhanced mixing of the additive package.
Controlling the amount of additive dispensed to mixing tank 106 is regulated by
controller 112. At the lowest level controller 112 controls and tracks the sequence of values and
sensors, e.g., load cell, level sensor, flow meter, electrochemical sensor, or combination thereof;
to construct an additive blend based on a preprogramed procedure for a given blend.
Adjustment to the additive blend can be made by manually changing settings to control
dispensing devices and set-point values. Alternatively, controller 112 can operate at higher levels
of functionality to include process operating conditions and process fluid characteristics to
optimize the blend composition. Furthermore, remote access to the controller through a WIFI or
Ethernet connection allows communicating to the controller remotely to adjust settings or
download additional information, e.g., water ion composition analysis results, for use with an
optimization model to determine and adjust the additive composition.
Independent of the method used to dispense the active into the mixing tank; a method to
monitor the amount of active dispensed is required to control the desired final composition of the
additive blend. Conventional methods to monitor the amount of active dispensed include direct
weight measurement as illustrated in FIG. 1 with load cell 110 used on each active container,
volumetric flow metering of the dispensed liquid over a known period of time, or level sensor to
measure the change in liquid level. These conventional techniques are suitable provided the
dynamic response and resolution of the sensor matches the system demands. For example, if the
required amount of active dispensed is only 0.1 g from a 10.0-kg container, then monitoring and
control of the dispensed fluid requires a high precision mass or level sensor with enough
resolution to accurately measure and track the amount of active dispensed. Using high precision
instrumentation to monitor active dispensing is costly and susceptibility to higher maintenance
when exposed to industrial environments that experience temperature and humidity changes. In
addition, care is needed to isolate the load cell from neighboring vibration sources such as pumps
that can add noise to the measured signal reducing precision and accuracy.
Attaining the required measurement resolution from standard load cells is possible by
sizing the dynamic range to the application. For example, dispensing a 1 g sample from a 1000
g supply container requires a much higher performing load cell compared to dispensing 1 g from
a 10 g supply container. However, reducing the active volume available for dispensing also
increases the frequency the actives must be replaced. Frequent replenishment of the active is not
advantageous because it requires more user interaction with the system, increases the probability
of operating without the system being replenished, and can lead to higher shipping and packaging
costs due to frequent replacement.
To extend the time between replenishing concentrated actives and maintain a high
resolution measurement for dispensing small volumes a secondary dispensing stage, as shown in
FIG. 2 for a single component concentrated active subassembly, addresses this issue. Container
200 is sized accordingly with concentrated active 201 to last an acceptable period of time for a
given dosage and maintenance schedule. The concentrated active is dispensed to a second
smaller container 203 through dispensing device 202, which can be but not limited to gravity
feed, mechanical pump, or venturi type device. The signal from load cell 205 is used to monitor
when container 203 needs replenishment as well as control the amount of active dosed to the
process. Dosing is made by drawing the active through transfer line 206 using a dispensing
device 207, which can be but not limited to gravity feed, mechanical pump, or venturi type
device. The dispensed active can then be transferred to the process 208, stored in a tank for later
use, or to a mixing tank to make an additive blend.
An alternative approach to monitor the amount of active added to tank 106 is based on
monitoring the direct fluorescence of the active or an inert fluorophore that is mixed with an
active at a known proportional amount. In this case, pump 117 shown in FIG. 1 circulates the
additive from tank 106 through fluorometer 116. The circulating pump 117 also promotes
additional mixing of the blend, which can be further enhanced with the addition of a mixing
educator nozzle. A three-way solenoid valve 118 can be used to isolate the fluorometer and
additive mixing step from the process. Once the additive package is ready for dispensing, valve
118 is switched to direct the additive blend to the process.
The gain setting on fluorometer 116 can be variable with automatic adjustment to set the
fluorometer dynamic range so that the same fluorometer channel is used for both blending the
additive package, which is at high concentration compared to the actives, and monitoring
fluorescence from actives in the diluted process stream. Alternatively, a dedicated channel or
sensor with a preset gain can be used. In this case, a single excitation source is used and
fluorescence monitoring is performed with one sensor adjusted for the higher concentration range
of the additive blend and the second sensor adjusted for a lower concentration range to monitor
the additive diluted in the process.
To monitor multiple actives by fluorescence at different wavelengths, a dispersive or nondispersive
fluorometer can be used. When using a non-dispersive fluorometer, dedicated
excitation sources and detector assembles with appropriate bandpass filter is needed for each
wavelength range detected. Using a dispersive system simplifies the number of detectors needed
by monitoring the emitted fluorescence of each species on an array detector. To minimize
interference from multiple excitation sources and fluorescence from actives or inert dyes, phase
sensitive detection techniques can be applied as well as using bandpass filters. Finally,
monitoring fluorescence from highly concentrated actives can be problematic due to selfabsorption
and quenching. In this case, reflectance fluorescence monitoring is the preferred
choice with the excitation light incident on the medium with the emitted fluorescence collected in
the reflectance mode. For example, a bifurcated fiber can be used to deliver the excitation light
through one leg of the fiber and collect emitted fluorescence through the other leg directed to
either a dispersive or non-dispersive detection system.
To illustrate the concept for using an additive blend, a cooling water unit operation
example is presented. Table 1 lists the target components and concentrations for an additive
blend consisting of the following three actives: THSP and TT for corrosion control and HEDP
for scale control. In the first approach, the blend is made by monitoring the fluorescence signal
from an inert tracing fiuorophore added to the active or measuring the fluorescence of the active
directly. For this example, direct fluorescence monitoring of TT and THSP is possible; however,
for HEDP monitoring, an inert water soluble fiuorophore is needed as a tracer such as pyrene
sulfonic acids including 1,3,6,8 pyrenetetrasulfonic acid sodium salt ("PTSA"), 8-hydroxy 1,3,6-
pyrene trisulfonic acid sodium slat, and pyrenefulfonic acid (mono) sodium salt. The tracer is
added to the HEDP at a known concentration to give a fluorescence signal that is proportional to
the HEDP concentration. In cases that require the addition of tracing dye to monitor an active
component, the tracing dye can be premixed with the active during manufacturing or added at the
point-of -use. The addition of the inert dye, e.g., PTSA, with HEDP serves in both constructing
the additive blend and used to set a baseline dosing level to monitor the process, as typically done
when using Nalco 3D TRASAR technology.
Table 1. List of active components for additive package.
Concentrated Target Additive Blend
Active
Active (%) Concentration (%)
1-Hydroxyethylidene-1 , 1-diphosphonic acid (H 62 10
Tolyltriazole (TT) 35 1
Poly acrylic acid tagged dispersant (THSP) 35 7
Example 2 :
In the previous example, multiple component monitoring requires a fluorometer having
different excitation source wavelengths and detection channels. An alternative approach of the
invention is based on monitoring the fluorescence from one component during sequential steps of
adding the different active components. For example, to construct the additive package listed in
Table lthe steps listed in Table 2 can be followed to make a 1.0-liter blend. Using THSP as the
baseline fluorescence signal the additive package is constructed by measuring the change in the
THSP signal. Because THSP is initially highly concentrated the fluorescence signal is nonlinear,
as shown in FIG. 3 for the integrated intensity collected using a bifurcated fiber optic probe. For
this example, one fiber optic leg supplies the excitation light at 365 nm that propagated through
fiber and exits the probe which is submerged into the fluid. Light exiting the probe excites the
THSP molecules resulting in fluorescence emission collected at the probe tip where one fiber (or
bundle of fibers) transports the emitted radiation to a spectrometer for analysis. Because of the
quenching and self-absorption present for high concentrated solutions, the integrated
fluorescence spectra shows a non-linear behavior, as shown in FIG. 3, for a range of THSP
concentrations in water. Therefore, a concentration range must be selected where the
fluorescence response is sensitive to concentration changes.
To construct a 1.0-liter additive blend based on the THSP spectral response in water, the
sequence of steps listed in Table 2 are developed to predict the fluorescence response resulting
from the addition of each additive. First, 6 11ml of water is added to mixing tank 106 followed
by partial addition of 100 ml THSP. The amount of THSP added to the mixing tank 106 is
controlled by either the dispensing device 105 or a level sensor 108/109. Only a portion of the
THSP is added in the first step to dilute the THSP concentration thereby shifting the integrated
fluorescence response to a more concentration sensitive region.
Alternatively, if no active components in a blend fluoresce or the fluorescence is too
weak in the desired concentration range then an inert flourophore can be added and used to set a
baseline signal. In either case, the initial component added to the mixing tank sets an initial
fluorescence signal to compare against the change in signal with the addition of each active
component. Fluorometer 116 can have a dedicated channel with the gain values set to provide a
suitable dynamic range or a variable gain fiuorometer channel can be implemented to use for
both blending the additive package and monitoring the process. The addition of TT, step 3,
results in a small fluorescence signal gain of 0.04 counts because the volume added is only 28
ml. Adding 161 ml of HEDP, step 4, further dilutes the THSP causing the integrated
fluorescence signal to increase. The final addition of 100 ml THSP, step 5, reduces the
integrated fluorescence signal down to 0.49 because of self-absorption and quenching at the
higher concentration. The set-point values listed in Table 2 for the target concentration levels
can be programmed into the controller to automatically send a control signal to start and stop
dispensing of the active component.
In step 3, the amount of TT added is small resulting in only a 0.04 signal change. Small
changes in signal can be difficult to accurately monitor the blend concentration. To improve the
blend accuracy, signal enhancement by simple dilution of the concentrated TT is one approach
that will increase the detectable difference before and after addition. For example, starting with
concentrated TT of only 21% requires addition of 56 ml to achieve the final 1% target
concentration. In this case, the resulting higher dilution increases the signal by 5 %.
Table 2 : Active addition steps to construct the additive blend listed in Table 1
based on fluorescence attenuation.
Step Component Volume (ml) THSP Signal
1 H20 611
2 THSP 100 0.84
3 TT 28 0.88
4 HEDP 161 1.07
5 THSP 100 0.49
Example 3:
A third aspect of the invention is monitoring and controlling the amount of active added
to the holding tank by monitoring fluorescence of a secondary fluorophore component, e.g.,
PTSA, blended with the concentrated active. The fluorescence from the PTSA monitored by
fluorometer 116 (FIG. 1) provides a metric for the active concentration, since the proportion of
PTSA to active is known. For example, to construct the additive package in Table 1, HEDP
traced with PTSA, can be added first to the holding tank with additional dilution water to set a
baseline fluorescent signal count representing a HEDP concentration of the target 11% value for
a completed additive package. Controlling the concentration of the subsequent actives is then
made by selectively adding or not adding PTSA to concentrated actives. In this case, if the
second active added is THSP with no PTSA then the signal measured using the fluorometer
tuned for PTSA monitoring will change. The amount of attenuation or gain depending on the
concentration level is directly proportional to the amount of THSP added. Addition of the third
active, TT, with PTSA added would then result in fluoroscence signal increasing a proportional
amount. By selectively including PTSA with specific actives provides a means to increase the
measurement sensitivity to control the blend concentration. In this case, the concentration of TT
is small relative to HEDP and THSP so the addition of PTSA with TT aids in amplifying the
effect of addition and dilution to the blend. The addition of PTSA added at the different steps in
making the additive blend can be controlled so the final concentration in the additive blend is in a
working range for use as an inert tracing dye for additive dosage control to the process.
Example 4 :
A fourth aspect of the present invention is to dispense chemicals into multiple mixing
tanks as shown, for example, in FIG. 4 grouped according to compatible chemistry, e.g. , acids
and bases, or to react multiple components to generate a new active. In the example illustrated in
FIG. 4, two groups of concentrated actives are shown. However, the approach is expandable to
n-containers with n-concentrated chemical delivery devices. Chemical dispensing of the
concentrated active involves the steps of transporting the fluid to container 306 using a
dispensing device 305. The concentration of the dispensed fluid can be monitored by direct
fluorescence monitoring of the active component or of an inert fluorophore added to the
concentrated active of known concentration. A dedicated flourometer pump 314 can be used for
each mixing tank or a single fluorometer with multiple channels either non-dispersive or
dispersive can measure the active concentration, as shown in FIG. 4. Concentration monitoring
of the active blend using a single fluorometer requires switching sample flow between each
container. For the configuration shown in FIG. 4, sample switching between the two tanks 306 is
done through controlling solenoid valve 315, with several of these valves shown in the
illustration.
Example 5:
A fifth aspect of the present invention is to directly inject the concentrated active into the
process stream or basin. Configuration for direct injection is shown in FIG. 5 for an ncomponent
system. In this example, concentrated active is injected into the process stream by
withdrawing liquid simultaneously or at discrete times from the holding containers 400, 401, 402,
and n-component 403. Dosing the active to the process is made by withdrawing a controlled
amount of the active from the container through delivery line 404 using a fluid dispensing device
405 to deliver the active to a process stream 406. The fluid dispensing device 405 used can be
any technology typically used for liquids that include but not limited to mechanical pumping,
venturi injector, gravity feed, or displacement methods that such as direct pressurizing the
container, bladder system, or progressive cavity displacement. The direct injection could also be
of a solid into the liquid stream. Injection points can be on a common process stream, as
illustrated in FIG. 5, on different process streams, or at differing locations on the same process
stream. Additionally a single injection point can be shared for the addition of the different
actives using various methods such as multiport selector valve, multiple inlet venturi, or
combination manifold and solenoid valves. Additive injection control at multiple points can be
made simultaneously provided the proportion of each additive is controllable. Alternatively,
additive injection can be made in a timed sequence, e.g., injection of component 1 followed
component 2, etc., and where the sequence of actives injected can vary or be fixed. Active
injection can also be controlled based on process demand need. For example, the frequency and
amount of a particular active injected into the process can vary depending on the process
operating conditions and feed characteristics. Control of the frequency and amount of active
injected is made by coupling the dispensing system to an optimization protocol.
Monitoring the amount of active directly injected to the process can be made using a load
cell 410 if the resolution is acceptable. Weight based monitoring using load cells can be made
either by directly tracking the weight of the concentrated active or using a secondary smaller
volume holding vessel as shown, for example, in FIG. 2 to achieve higher resolution
measurements when the concentrated active supply source is a large volume container. A
fiuorometer 408 can also be used to measure direct fluorescence of the active or fluorescence of
an inert traced fiuorophore added to an active in the presences of another fluid, e.g., process
water. Any of several other sensors could theoretically be used depending on the parameter to be
monitored, and several of those other sensors are listed throughout this application. In this case,
a flow meter 407 may also be needed, where flow meter 407 and fiuorometer 408 monitor the
process fluid downstream of the injection point(s) of the active(s), allowing the user to determine
the concentration of the actives that had been added to the system based on the integrated
fluorescence signal over time. Fluorescence monitoring of the additive directly after the injection
point can also serve as an alarming monitor to insure the additive is being dispensed.
Example 6 :
A sixth aspect of the present invention is to dispense chemicals into a holding vessel to
make an additive package, transport the holding vessel containing the additive package to the
point-of-use, and dispensing the additive package from the holding vessel at the point-of-use. In
this case the holding vessel is mobile so the additive package made at the chemical dispensing
system is transported to the process or distribution system for dispensing. Any of the delivery
systems or methods described above can be used to make the additive package. This approach
can be used in cases where a manufacturing plant has multiple unit operations using a similar set
of components with the same or differing concentrations. For example, a manufacturing plant
with several water cooling towers disturbed throughout their facility may use an additive package
with common components consisting of an azole, a dispersant polymer, orthophosophate, and
phosphonobutanetricarboxylic acid. These main components can be common for each cooling
tower, but the concentration may differ. The optimal additive package can differ for each tower
because of tower age; material of construction, operating conditions, etc., as well as feed rate.
Sizing the additive package holding vessel will depend on the feed rate and variability of the
process, i.e., the frequency required to adjust the concentration of the additive package
components to maintain optimal performance. The optimal additive blend concentration can be
preprogramed into a controller for a given tower or defined set of operating conditions, manually
inputted by the user, or automated to adjust based on information collected on the process
operating conditions and feed input characteristics.
Having a blending system located onsite provides flexibility to adjust feed concentrations
and type of chemicals supplied to each unit operation, thereby maintaining optimal performance.
Use of mobile containers to transport the additive package to the point-of-use allows the user to
size the container accordingly. For example, if a frequent change in the chemical components or
concentration is required then a smaller additive holding container is desirable to avoid blending
an access volume of additive. Smaller additive holding container also has the advantage of
working with a reduced footprint, which is beneficial when space is a premium. Proper
management of the additive package holding container size and replenishment frequency also
helps in reducing potential shelf-life stability issues that can occur for certain additive
combinations. In these cases, additional chemicals are generally added as a stabilizer. However,
a properly sized container can shorten the shelf-life of the additive package reducing the needed
for stabilizers in some cases. The standard approach of supplying and additive package blended
at a manufacturing facility and shipped to the site cannot address all of these functional attributes
offered by using an onsite additive blending system.
In general all of the different system configurations described here can be used if the
active dosed to the process can be directly monitored using fluorescence or the active is traced
with an inert dye if using a TRASAR dosing methodology. When using a TRASAR method, a
dye of known amount must also be added to the additive blend or could be introduced through a
venturi with a known dilution ratio. In either case, a target set point level, e.g., 100 ppm +/- 10
ppm, with upper and lower limits is used to control the amount of additive dispensed. In cases
where TRASAR technology is not used, a bleed and feed approach may be used, or any approach
known by those skilled in the art.
In any case, blending the additives at the point of use or direct injection has the advantage
of real-time customized control of the additive composition. For example, if the makeup water
quality changed or the cooling tower is experiencing higher corrosion, then the additive blend
can be adjusted on site, tested, and readjusted if needed. This approach is not practical using the
traditional additive packages supplied as a blended drum of actives where any reformulation to
adjust the composition is both costly and time consuming.
All patents referred to herein, are hereby incorporated herein by reference, whether or not
specifically done so within the text of this disclosure.
In the present disclosure, the words "a" or "an" are to be taken to include both the
singular and the plural. Conversely, any reference to plural items shall, where appropriate,
include the singular.
From the foregoing it will be observed that numerous modifications and variations can be
effectuated without departing from the true spirit and scope of the novel concepts of the present
invention. It is to be understood that no limitation with respect to the illustrated specific
embodiments or examples is intended or should be inferred. The disclosure is intended to cover
by the appended claims all such modifications as fall within the scope of the claims.
CLAIMS
We claim:
1. A method for controlling treatment of an industrial water system, the method comprising
the following steps:
providing an apparatus for controlling delivery of at least one treatment chemical, the
apparatus comprising at least one sensor and an electronic input/output device
carrying out a protocol;
measuring a parameter of the industrial water system using the at least one sensor;
relaying the measured parameter to the electronic device;
adjusting the protocol based on the measured parameter;
delivering a concentrated treatment chemical into a stream of the industrial water system
according to the adjusted protocol, the concentrated treatment chemical comprising
an active ingredient, the active ingredient traced as necessary, the active ingredient
having a concentration;
repeating the measuring, the adjusting, and the delivering; and
optionally repeating the steps for n-number of parameters, n-number of active ingredients,
and/or n-number of concentrated treatment chemicals.
2. The method of claim 1, wherein the industrial water system is selected from the group
consisting of: a cooling tower water system; a petroleum well, a downhole formation, a
geothermal well, and any other oil field application; a boiler system; a hot water system;
mineral process waters comprising mineral washing, flotation and benefaction; a
papermaking process; a black liquor evaporator; a gas scrubber; an air washer; a
continuous casting process; an air conditioning system; a refrigeration system; a
pasteurization process; a water reclamation system; a water purification system; a
membrane filtration water system; a food processing stream; and a wastewater treatment
system.
3. The method of claim 1, wherein the at least one sensor is selected from the group
consisting of: a fluorometric sensor; a spectra fluorometric sensor; an optical absorption
spectroscopic sensor; an optical Raman spectroscopic sensor; a corrosion sensor; a
conductivity sensor; a pH sensor; a temperature sensor; a weight sensor; a flow sensor; a
load cell; a level detector; a turbidity sensor; an electrical sensor; an electrochemical
sensor; an acoustic sensor; multiples thereof; combinations thereof; and multiples and
combinations thereof.
4. The method of claim 1, wherein the parameter is selected from the group consisting of: a
corrosion rate; a scaling rate; a deposition rate; a heat transfer rate; a cooling tower
efficiency; a chemical concentration; a cycle of concentration; a suspended solids
measurement; a dissolved solids measurement; a microbiological activity rate; a chemical
activity rate; a process performance parameter; a product performance parameter;
multiples thereof; combinations thereof; and multiples and combinations thereof.
5. The method of claim 1, wherein the method further comprises automatically diluting the
concentrated treatment chemical prior to the delivering.
6. The method of claim 5, wherein the automatically diluting occurs in-stream en route to
the delivering.
7. The method of claim 1, wherein the concentrated treatment chemical is delivered as a
solid.
8. The method of claim 1, wherein the concentrated treatment chemical is delivered as a
liquid.
9. The method of claim 1, wherein the concentrated treatment chemical comprises at least
two active ingredients.
10. The method of claim 1, wherein the concentrated treatment chemical is further comprised
of a dye, the active ingredient traced with the dye.
11. The method of claim 1, wherein the active ingredient is a polymer tagged with a
fluorescent moiety.
12. The method of claim 1, wherein the active ingredient is inherently fluorescent.
13. The method of claim 1, wherein the apparatus further comprises a modular delivery
system.
14. The method of claim 1, wherein the protocol comprises an algorithm based on
calculations selected from the group consisting of: a first principle; an empirical
observation; multiples thereof; combinations thereof; and multiples and combinations
thereof.