WO2023245197A2 - Tagged polymers as phosphonate replacements in water treatment applications - Google Patents

Abstract

The present invention relates to water treatment formulations tailored for different water treatment systems and to the use of the water treatment formulations to treat water.

Description

Tagged Polymers as phosphonate replacements in water treatment applications

PRIORITY CLAIM

[0001] This application claims priority of U.S. Provisional Patent Application Serial No. 63/352,848, filed June 16, 2022, the entire contents of which patent application are hereby incorporated herein by reference.

FIELD OF THE DISCLOSURE

[0002] The present invention relates to water treatment polymers and water treatment processes using the water treatment polymers.

BACKGROUND OF THE DISCLOSURE

[0003] The statements in this section merely provide background information related to the present disclosure and do not constitute prior art.

[0004] There is a shortage of phosphonates in the marketplace. There is a need to replace phosphonates in water treatment systems. There is also a need to give the water treater the ability to monitor active ingredients. To understand a possible solution to replacing phosphonates, we need to delve into the types of formulations and systems typically used in cooling tower systems. Cooling tower systems typically operate in the range of pH 7- 9. We can broadly divide these formulations and systems into two areas.

[0005] Stabilized phosphate treatments or neutral pH treatments typically operate in pH range 7-7.8 (lower end of the pH range) and have a corrosive tendency and a milder calcium carbonate scaling tendency. Under these corrosive conditions, relatively high levels of phosphate (5-10 ppm) are often used to inhibit corrosion. In these systems, calcium phosphate deposit control or stabilizing phosphate is generally of greater importance. We will refer to these systems as stabilized phosphate or neutral pH programs. In these systems, phosphonates can be removed from the formulation and a good calcium carbonate poly mer should be good enough to control carbonate scale.

[0006] Zero phosphate or alkaline treatments operate at the higher end of the pH range of 7.8-9+, where conditions are less corrosive, and lower levels of phosphate or zero phosphate formulations are often used. Calcium carbonate scale control tends to be of greater importance in the higher pH, “alkaline” treatment programs. Even in these systems, phosphate can be present at low levels in makeup water, and as the water is cycled up, 1-3 ppm phosphate in makeup water can easily become 10-20 ppm phosphate in the cooling tower without any addition from the formulation. These systems may have both calcium carbonate and calcium phosphate scaling tendencies, especially as pH is increased. However, in these systems calcium carbonate scale is the bigger issue with calcium phosphate scale the lesser issue.

[0007] It is an object of the present invention to help with replacing phosphonates in water treatment systems. A secondary object is to give the water treater the ability to monitor active ingredients.

SUMMARY OF THE DISCLOSURE

[0008] This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

[0009] The present invention relates in one embodiment to a water treatment formulation for stabilized phosphate systems operating in a neutral pH, comprising:

(a) at least one corrosion inhibitor; and

(b) a Tagged Polymer A; wherein the formulation is substantially free of phosphonate.

[0010] The present invention relates in another embodiment to a water treatment formulation for low or zero phosphate or alkaline pH systems, comprising:

(a) phosphonate; and

(b) a Tagged Polymer B; wherein the formulation is substantially free of a scale control polymer other than said Tagged Polymer B.

[0011] The present invention relates in a third embodiment to a method of treating water susceptible to forming phosphate scale in a stabilized phosphate systems operating in a neutral pH, said method comprising:

(a) treating the water with the inventive water treatment formulation comprising Tagged Polymer A;

(b) detecting the level of Tagged Polymer A that inhibits the formation of phosphate scale; and

(c) adjusting the level of Tagged Polymer A as necessary to inhibit the formation of phosphate scale. [0012] The present invention relates in a fourth embodiment to a method of treating water susceptible to forming carbonate scale in a low or zero phosphate or alkaline pH system, said method comprising:

(a) treating the water with the above-mentioned water treatment formulation comprising the Tagged Polymer B;

(b) detecting the level of Tagged Polymer B that inhibits the formation of carbonate scale; and

(c) adjusting the level of Tagged Polymer B as necessary to inhibit the formation of carbonate scale.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present disclosure is best understood from the following detailed description when read with the accompanying Figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

[0014] FIG. la (left): Polymer with PTSA, FIG. lb (center): Polymer with PTSA as measured by fluorescence (initially), FIG. 1c (right): Polymer with PTSA as measured by fluorescence (at equilibrium).

[0015] FIG. 2a (left): Illustration of Tagged Polymer A controlled by a polymer signal band with an upper and lower limit. FIG. 2b (right): Illustration of Tagged Polymer B controlled by delta with the signal between Tagged Polymer B and PTSA.

[0016] FIG. 3: Illustration of system disruptions and their effect on polymer signal and polymer consumption.

[0017] FIG. 4: Effect of calcium carbonate precipitation on the measured tagged polymer concentration. The pilot study used 7.5 ppm active polymer tagged with monomer B and 100 ppb PTSA.

[0018] FIG. 5: Tagged Polymer and PTSA signal over 24 weeks in a large cooling tower in an alkaline pH system of Case Study 1 .

[0019] FIG. 6: Tagged Polymer and PTSA signal over 7 days in week 18 (weeks 4 to 24 look similar) in a large cooling tower in an alkaline pH system of Case Study 1.

[0020] FIG. 7: pH of the cooling tower in Case Study 1 over weeks [0021] FIG. 8: Conductivity (pmho/cm) of the cooling tower in Case Study 1 over 24 weeks

[0022] FIG. 9: Iron/Fe (ppm) levels in make-up and cooling tower in Case Study 1 over 24 weeks

[0023] FIG. 10: Free chlorine (ppm) levels in cooling tower in Case Study 1 over 24 weeks

[0024] FIG. 11 : Conductivity and polymer signal for Tagged Polymer A using a stabilized phosphate system in a mid-size cooling tower.

[0025] FIG. 12: Percent phosphate inhibition (blue columns) calculated by dividing fdtered phosphate by unfiltered phosphate. Fluorometer readings (gray line) show Tagged Polymer levels in the cooling tower at the beginning and after month 1, 2, and 5 of the trial.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Illustrative examples of the subject matter claimed below will now be disclosed. In the interest of clarity, not all features of an actual implementation are described in this specification. It will be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions may be made to achieve the developers’ specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort, even if complex and time-consuming, would be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

[0027] The term “Tagged Polymer A” as used herein means a water soluble pyranine polymer as described in WO 2019/025305, the entire contents of which are hereby incorporated herein by reference.

[0028] In one preferred embodiment, the Tagged Polymer A is a fluorescent polymer composition comprising fluorescent pyranine monomers and non-fluorescent monomers, said fluorescent polymer composition being substantially free of pyranine, said fluorescent pyranine monomers being selected from monomers of formula (Ila)

and/or formula (Tib)

wherein

Ri is selected from optionally substituted Ci-Cioalkyl, aryl-C2-Cioalkyl, , -C(O)-, -

CH₂NH-C(O)-, -C(CH₃)2-NH-C(O)-,

R is optionally substituted Ci-Cioalkyl, and

M is selected from the group consisting of hydrogen, sodium, potassium, cesium, rubidium, lithium, ammonium, and tetralkylammonium, and wherein said non-fluorescent monomers are selected from one or more of the group consisting of acrylic acid and salts, methacrylic acid and salts, maleic acid and salts, maleic anhydride, acrylamide, crotonic acid and salts; itaconic acid and salts, methacrylamide, 2- acrylamido-2 -methylpropanesulfonic acid and salts, sodium (meth)allyl sulfonate, allyloxybenzene sulfonic acid and its salts, polyethylene glycol monomethacrylate, vinyl phosphonic acid and salts, styrene sulfonic acid and salts, vinyl sulfonic acid and salts, 3- allyloxy -2 -hydroxypropane sulfonic acid and salts, N-alkyl (meth)acrylamide, t-butyl (meth)acrylate, N-alkyl (meth)acrylate, N-alkanol-N-alkyl(meth)acrylate, vinyl acetate, 2- Hydroxy N-alkyl(meth)acrylate, alkyl vinyl ether, alkoxyethyl acrylate, N-alkanol (meth)acrylamide, N,N-dialkyl(meth)acrylamide and l-vinyl-2-pyrrolidinone; sulfomethylacrylamide and sulfoethylacrylamide.

[0029] In an especially preferred embodiment, in such polymers, the sum of the mole percent of unfunctionalized pyranine compound and the mole percent of unpolymerized pyranine monomer is less than 5 mole percent o the total pyranine in the polymer composition.

[0030] The term “Tagged Polymer B” as used herein means a fluorescent polymer as described in U.S. Patent No. 11,208,408, the entire contents of which are hereby incorporated herein by reference.

[0031] In one preferred embodiment, the Tagged Polymer B is a water treatment polymer formed from polymerizing a polymerization mixture comprising:

(i) at least one water-soluble carboxylic acid monomer, or salt or anhydride thereof, present in an amount of 10-99.999 mol% based on 100 mol% of the polymer;

(ii) the quatemized fluorescent monomer of claim 29; and wherein the polymer chains of the water treatment polymer formed comprise 0.001 mol% to less than or equal to 10 mol% of the quatemized fluorescent monomer of claim 29 as unreacted monomer unincorporated into the polymer chains thereby indicating that said quatemized fluorescent monomer of claim 29 has been incorporated into said water treatment polymer to an extent equal to or greater than 90 mol%.

[0032] In another preferred embodiment, the Tagged Polymer B comprises a quatemized fluorescent monomer comprising the structure:

wherein

Rr is selected from H, hydroxy, alkoxy or Ci-C4alk-O-(CHR5CH2O-)_n;

Rs is selected from H and Ci-C4-alkyl; n is 1-10; and

X" is an anionic counter ion; and comprising less than 8 mol%, based on 100 mol% of total naphthalimide fluorescent monomer of the structure:

wherein R4 is as defined above.

[0033] In a more preferred embodiment, the Tagged Polymer B comprises (a) N- (3-dimethylaminopropyl)-4-methoxy-l,8-naphthalimide, 2-hydroxy-3-(meth)allyl oxypropyl quaternary salt comprising less than 5 mol% of (b) N-(3-dimethylaminopropyl)-4-methoxy- 1,8-naphthahmide, based on 100 mol% of (a). [0034] Polymers control scale by threshold inhibition as well as crystal growth modification. Polymers also provide dispersancy for scale, silt, dirt and other insoluble material in cooling systems. In contrast, phosphonates provide threshold inhibition for carbonate scale and do not provide dispersancy or phosphate scale control.

[0035] Threshold inhibition is the best mechanism for scale control since it completely prevents scale from being formed. Crystal growth modification typically occurs after the threshold inhibition mechanism has been overcome and is a secondary and not preferred mechanism for scale control, since the scale have already started to form, and it is a gamble whether they will adhere to the heat transfer surfaces or not. There are certain studies showing the efficacy of a polymer system using longer induction time. However, the residence time in the cooling systems is hours to days which are orders of magnitude longer than induction time experiments which are measured in minutes in the lab. The true measure of efficacy of any polymer is whether the filtered Ca (soluble calcium) is greater than 80-90% of the unfiltered Ca (total calcium) showing that scale (both calcium carbonate and calcium phosphate) is being controlled and not deposited on the cooling surfaces.

Tagged Polymers:

[0036] Conventional systems use a combination of inert tracers such as PTSA (1,3, 6, 8 pyrenetetrasulfonic acid, sodium salt) and untagged polymers. See, Sawada K. (1997), The mechanisms of crystallization and transformation of calcium carbonates, Pure & Appl. Chem. Vol. 69, No. 5, 921-928; and Dominique J Tobler, J. D. (2016), Effect of pH on Amorphous Calcium Carbonate Structure and Transformation, Cryst. Grow th Des., 16, 4500 - 4508. The inert tracers monitor the dosing of formulations into water treatment systems and the untagged polymers are used for scale control. While inert tracers can help water treaters monitor how much formulation is being added and maintained in their systems, these tracers do not indicate how much of the untagged polymer is being used up. Different components in the formulation are depleted at different rates, and the use of an inert tracer does not provide an accurate picture of how much active polymer is available to provide scale control and dispersancy in the system. Initially, PTSA (represented by the diamond) indicates the amount of untagged polymer (represented by the squiggly lines) or formulation as it is dosed in (FIG. la and lb). However, as the untagged polymer is used up, PTSA remains at the same level (or concentration) and gives the same fluorescent signal, and it cannot account for untagged polymer consumption as illustrated in FIG. 1c. Therefore, inert tracers do not indicate true untagged polymer consumption in the treated water.

[0037] There are two main types of tagged polymers that are designed to minimize scale which contain two different types of fluorescent monomers. For the purposes of this disclosure, as discussed above, they will be referred to as Tagged Polymer A and Tagged Polymer B. The Tagged Polymer B is based on a hydrophobically modified untagged polymer detailed in previous papers. See, Rodrigues, K.A.; Sanders, J. (Sept. 26-29, 2018), “The Role of Hydrophobic Modifications of Polymers for Scale Control,” AWT 2018 Conference, Orlando, Florida, Association of Water Technologies, Rockville, Maryland; and Rodrigues, K.A.; Vanderhoof, M.; Sanders, J. (Sept. 11-14, 2019), “Non-phosphorus/non-P based scale inhibitors for calcium carbonate scale control,” AWT 2019 Conference, Palm Springs, California, Association of Water Technologies, Rockville, Maryland. Additional information on Tagged Polymer A and B were described in previous presentations and accompanying papers. See, Rodrigues, K.A.; Sanders, J. (Sept 30-Oct 2, 2020), Fluorescent Tagged Polymers for Scale Control and Dispersancy, Association of Water Technologies, Rockville, Maryland; and Rodrigues, K.A.; Sanders, J. (Sept. 23-25, 2021), “Fluorescent Tagged Polymers in Water Treatment Applications”, AWT 2021 Conference, Providence, Rhode Island, Association of Water Technologies, Rockville, Maryland. The relative efficacy of these polymers for carbonate scales and dispersancy is listed in the Table 1 below. The detectors needed to use these polymers in the field are also listed in Table 1 below.

Table 1: Performance of polymers for different scales; ++++ best, +++ good, ++ acceptable, + poor. [0038] Tagged Polymers A and B are different in a number of ways. The comparisons of these two types of tagged polymers are detailed in Table 2:

Table 2: Comprehensive comparison of Tagged Polymer A and Tagged Polymer B and systems that they can be used in.

[0039] The main difference between Tagged Polymer A and Tagged Polymer B is that Tagged Polymer A is used by itself (without PTSA) and uses the same fluorometers as PTS A and therefore does not need new detectors.

[0040] In the experiments reported below, Tagged Polymer A is a copolymer of acrylic acid and 2-acrylamido-2-methyl propane sulfonic acid and methallyloxy pyranine as a partial sodium salt. In the experiments reported below, Tagged Polymer B is a copolymer of acrylic acid, methyl methacrylate, maleic acid, 2-acrylamido-2 -methyl propane sulfonic acid and 4-methoxy -N-(3 -dimethylaminopropyl)- 1,8-naphthalimi de, 1 or 2-hydroxy-3 -allyloxy propyl, quaternary salt as a partial sodium salt.

[0041] Tagged Polymer A is better suited for light industrial systems. Tagged Polymer B is used in conjunction with PTSA and therefore does need an additional fluorometer. Tagged Polymer B is better suited for heavy industrial systems.

[0042] Note: In this disclosure, all polymer concentrations are as active polymer and not polymer product. In addition, ppm and mg/L may be used interchangeably. Upsets, disruptions and interferences:

[0043] One of the main reasons to use tagged polymers is upsets or disruptions that frequently occur in most water treatment systems. This is exemplified in Case Study 1 where numerous albeit small mechanical issues occurred over the space of several months. These issues caused an increase in polymer demand. However, since the polymer signal was being measured, additional polymer/formulation was fed during these disruptions to get the operator through the disruption until the corrective action was implemented.

[0044] This is illustrated in the FIG. 3 above where the disruption starts to cause an increased polymer demand (teal) leading to a drop in polymer signal (green). However, the controller starts to feed more polymer than normally used until the disruption is taken care of. At that point the polymer consumption returns to normal levels.

Upsets, Disruptions, interferences and other factors affecting polymer consumption

[0045] Upsets or disruptions will occur in most systems mainly due to equipment failures or other reasons and are hard to predict and therefore control. The upsets or disruptions to the system can be:

[0046] Hardness and phosphate levels can fluctuate widely in city water sources leading to increased polymer demand that cannot be predicted. Tagged polymer systems can prevent underdosing or overfeeding polymer.

[0047] Effect of iron: Polymer performance can decrease in the presence of iron especially in its soluble form. Cavano states that this is especially true of polymaleic acid (PMA) type polymers. See, Cavano, R., “Developing cooling water treatments, parts 1-4”, The Analyst 2008.

[0048] pH of the system starts to increase due to pump failure or other reasons leading to an increase in scaling tendency and polymer demand. If a tagged polymer is used, the control system will feed additional polymer.

[0049] Hot spots - Most systems have hot spots that have increased scaling potential. Tagged polymer systems can account for the additional polymer demand.

[0050] Chlorine or hypochlorite is the most effective biocide and is widely used. Unfortunately, it can lower the scale control performance of polymers especially at higher levels (2-8 ppm as free chlorine). [0051] Polymer dosing Scatolini et al., point out that both under dosing and overdosing of the polymers used as deposit control agents is bad. See, Scattolini, J.L.; Zhang, E; and Buentello, K.E.; “A quantitative polymer method for cooling water applications”, Paper Number: NACE-01447, CORROSION 2001, Houston, Texas, March 11 2001. It is important not to underdose the polymers since this can cause scale formation resulting in failure of critical equipment. However, overdosing leads to increased costs but also unwanted side reactions such as precipitation of other ingredients like phosphonates in the system.

[0052] Moriarty and coworkers point out that there are many other variables that can affect the amount of polymer being used up in the system at any point in time. See, Moriarty, B.E; RasimasJ.P; Young, P.R.;and Hoots, J.E.;” methods to monitor and control scale in cooling water systems”, Paper Number: NACE-01450, CORROSION 2001, Houston, Texas, March 11 2001. For example, there are different heat loads and different times of the day or night or in different seasons or even weather changes from day to day. Furthermore, they point out that it is nearly impossible to predict the polymer demand a prion and therefore upset conditions may occur without any prior indications. If you dose enough polymer to respond to a worst-case scenario, it will result in overdosing of the polymer. Therefore, it is a must to measure the active amount of polymer in the system, especially in systems with severe and variable stresses. Most importantly, they point out that system stresses resulting in increased polymer consumption precede significant performance losses. This gives the operator a chance to respond to the lower amount of polymer and prevent system failures using proper corrective actions. These corrective actions could include a change in polymer dosage, and/or a change in operating conditions such as reduced cycles of concentration or changes in pH.

LSI and pH

[0053] If you are operating at high LSI, which is the edge of the polymer's ability to control scale, any upset (small or large) in the system can take the system over the scaling boundary and cause precipitation. Examples of these upsets could include an increase in iron, increase in load in the system, change in the make-up water as regards to Fe or phosphate, drift in the system pH higher by even 0. 1-0.2 units etc. It is well known that polymers are susceptible to higher levels of iron. See, again, Moriarty, B.E; Rasimas .P; Young, P.R.;and Hoots, J.E.;” methods to monitor and control scale in cooling water systems”, Paper Number: NACE-01450, CORROSION 2001, Houston, Texas, March 11 2001. Therefore, even small (ppm levels of Fe) from corrosion products can cause this upset or disruption.

[0054] Similarly, an increase in system pH by 0.1 -0.2 can cause an increase in LSI say from 2.3 (normal operating LSI) to 2.5. Since LSI is logarithmic; times calcite saturation/calcium carbonate = 10LSI, this means that the system has gone from 200 times calcite saturation at LSI 2.3 to 316 times calcium carbonate saturation at LSI 2.5. This minor change in pH will cause a large upset in the system. If the polymer is untagged, the upset will not be detected, and the system will crash due to bulk precipitation of scale.

LSI and phosphate scale

[0055] Another issue with the relying on LSI is the interferences from phosphate scale. See, again, Cavano, R., “Developing cooling water treatments, parts 1-4”, The Analyst 2008. Even in a zero P system, phosphate can be introduced into the cooling systems from the make-up water since many municipalities use it. Calcium phosphate is several orders of magnitude less soluble than calcium carbonate and therefore will form scale first, making the LSI calculation meaningless and more importantly dangerous since it may lull the operator into a false sense of security. See, https://www.process-cooling.com/articles/89674- predicting-calcium-carbonate-scaling-accurately.

[0056] The tagged polymers overcome these issues because one is measuring the active polymer whose signal decreases when an LSI is reached that the polymer does not perform at. Therefore, these tagged polymers have an inbuilt security system that raises an alarm at the appropriate time.

LSI claims and comparisons between different studies

[0057] Frayne has cautioned about exaggerated and misleading LSI claims in product literature and brochures. See, Frayne, C., “Organic Water Treatment Inhibitors: Expansion of current guidelines, myths, misinformation, and the next generation of novel chemistries”- Part I, The Analyst, Volume 16, Number 3, 2009. Most suppliers will claim that their polymer is the best polymer as a replacement for phosphonate in water treatment formulations. Data will be presented showing the polymers working at high LSI. There are different equations to estimate LSI and these equations can give different LSI numbers. Therefore, LSI numbers are not absolute but depend on the method or equation used to calculate them. Unfortunately, most LSI numbers reported in literature, presentations and outputs from software programs do not detail the equations used for their estimation. Therefore, it is difficult to compare LSI’s between different studies even though most people do it. Furthermore, these LSI numbers may not account for issues that occur in real life, some of which are described above.

Shortages of raw materials

[0058] Shortages and delays in procurement of raw materials has become the norm lately, leading to unexpected changes in formulations. It is important to measure the active ingredients like polymers in the system because this can compensate for these changes in formulations which could have unexpected consequences. Using a tagged polymer allows the water treater to be assured that the scaling aspect of the system is still working well since the polymer signal would drop if it were not. This is powerful evidence not only for the water treater but for their customers.

Customers and Influencers

[0059] Finally, the customers and influencers are demanding that active ingredients be constantly monitored. This is certainly the case with biocides; where the water treater could not get away with just monitoring total chlorine and needs to measure free chlorine which is the active ingredient. Similarly, the water treater really needs to measure the active polymer in this system. This assures customers that their system is operating under control from a scaling point of view at every moment of the day and gives the water treater the same kind of security .

[0060] In summary, it is imperative that the system use a tagged polymer especially in formulations that do not use phosphonates since any or all of the above issues will result in increased polymer consumption and a decrease in polymer signal, allow ing the operator to take corrective action.

Effect of system stress on Tagged Polymer signal

[0061] Kalakodimi et. al, studied Tagged Polymer B as a deposit control agent (DCA) in a zero-phosphate system in combination with PTSA as an inert tracer. See, Kalakodimi and Post, CTI, Paper No: TP20-14, Advances in monitoring and control of cooling systems chemistry. In their pilot cooling tower study, the pH of the system was steadily increased to cause calcium carbonate precipitation (see Figure 16 in the article). As the pH is increased, the tagged polymer and the PTSA signal was measured. In addition, the filtered (F) and unfiltered (UF) calcium levels was also measured. The UF is the total calcium in the system and the higher the ratio of F and UF the better the carbonate scale control.

[0062] These data (FIG. 4) indicate that the tagged polymer and PTSA signal deviates from each other as calcium carbonate scale is formed at approximately pH 9.6 under these conditions. One will note that the tagged polymer and PTSA signal starts to deviate from each other around pH 9.4 giving an early warning that scale formation is about to start. This deviation is a clear indication of an upset in the system and corrective action needs to be taken to prevent scale formation. In addition, this disclosure demonstrated that Tagged Polymer B can be used up to a LSI of 2.9. Finally, the authors point out that the relying on the PTSA reading only (as is the current practice) would not have alerted the water treater that carbonate scaling was occurring.

Field data:

[0063] A large water treatment company has been using tagged polymers for over 20 years and this has been the subject of an AWT paper. See, Reggiani, G., and Young, P., “TRASAR® Technology- A review and comparison”, AWT document. There have been many field studies published by this company especially in stabilized phosphate systems which can be obtained using a simple Google search. Recently, another large company has started to utilize this technology. See https://www.chemtreat.com/detecting-system-stress- and-scale-at-a-chemical-plant-with-quaddetect-tagged-polymer/.

[0064] There is a new generation of this tagged polymer technology that is available to the general marketplace. See, WO 2019025305A1; US 11,208,408 B2; Rodrigues, K.A.; Sanders, J. (Sept 30-Oct 2, 2020), Fluorescent Tagged Polymers for Scale Control and Dispersancy, Association of Water Technologies, Rockville, Maryland; and Rodrigues, K.A.; Sanders, J. (Sept. 23-25, 2021), “Fluorescent Tagged Polymers in Water Treatment Applications”, AWT 2021 Conference, Providence, Rhode Island, Association of Water Technologies, Rockville, Maryland. These new generation tagged polymers are being used in several process cooling towers at small to large industrial facilities in the United States as well as in smaller comfort cooling systems. The field data presented below is a portion of the data available, with some information omitted to protect confidentiality. The included case studies illustrate the point that it is necessary to measure the active polymer in the system and that the change in polymer concentration can give additional information on the scaling stress on the system. Minor disruptions can be taken care of by the controller adding more polymer to the system until the disruption can be taken care of. However, a lowering in the polymer concentration indicates an upset in the system and immediate corrective action needs to be taken to prevent bulk scale precipitation. Even if the system does not have an interference or upset, the steady polymer signal is assurance that the cooling system is under control and everything is proceeding smoothly.

[0065] The disclosure will now be described in greater detail with reference to the following non-limiting examples.

Examples

Example 1: Case Study 1:

[0066] The first case study was conducted in a large facility which has a relatively large cooling tower with 6 bays. The system was an alkaline pH system that incorporated Tagged Polymer B in the formulation.

[0067] The details of the cooling tower are in Table 3 below:

Table 3 : Details of the cooling tower

[0068] For purposes of this case study, the first week after the switch over from the old formulation will be designated week 1 and the subsequent weeks will be weeks 2, 3, 4 etc. The field engineer was on site once a week to monitor the cooling systems. A plant employee from the customer was supposed to take samples during the week but due to other pressures the sampling was infrequent.

[0069] The conductivity, pH, ORP, PTSA, and Tagged polymer was measured continuously by the controller. Other parameters such as iron, total chlorine as well as free chlorine and micro counts were measured once a week when the field engineer was on site. In addition, the make-up water was analyzed once a week at the same time. The towers are fed off well water (treated through pre-filters) directly to the tower basin.

[0070] The original formulation presumably contained PMA (untagged) which was then switched to a formulation containing Tagged Polymer B at week 1 . Initially the Tagged Polymer B signal was low and not within the control band of 45-55. The polymer signal started to increase and eventually came up to the midpoint of the control band at week 4 (FIG. 5).

[0071] It appears that there was fouling due to the relatively poor scale control performance of the previously used PMA based formulation. This fouling was cleaned up by the Tagged Polymer B formulation leading to the lower than expected polymer signal initially (orange line in weeks 1-4 in FIG. 5). After the cleanup was complete, the Tagged Polymer B signal (orange) started to track the PTSA signal (blue) and was around the midpoint of the 45-55 control band (weeks 5 to 24 in FIG. 5). This was supplemented by the polymer signal in the weekly reports of weeks 5-24, with week 18 data shown in FIG. 6. While FIG. 6 shows week 18 data, data for weeks 4-24 all looked similar and did not have any major blips in the polymer signal. This shows that the tagged polymer level was high enough on a daily basis and was continuously maintained at that level to take care of unexpected issues or disruptions as detailed below.

System disruptions/Equipment issues:

[0072] The make-up water pH, iron and conductivity after the pre-filtration step is detailed in the Table below. The pH of the make-up water was fairly consistent as was the hardness and total dissolved solids as measured by conductivity.

Table 4: Make-up water pH, iron and conductivity.

[0073] The pH of the cooling tower for several weeks is charted in FIG. 6.

[0074] As one can see the pH is in the 8.5 to 9 range during these weeks. While this does not seem like a large difference in pH, it is really a large difference in scaling tendency. Assuming that the LSI at pH 8.5 is 2, this indicates that the LSI at pH 9 (weeks 5 and 6 for example) is 2.5. Since LSI is a logarithmic scale at pH 8.5, the system is 100 times the calcite (calcium carbonate) saturation whereas at pH 9 the system is 316 times the calcite saturation (Table 5).

Table 5: Relationship between pH, LSI and scaling tendency

[0075] Thus, small increases in pH can increase the scaling tendency by a large amount and increase the polymer consumption. While using PTSA only, this increase in polymer demand would not be detected by the system. However, the tagged polymer system detects the increased polymer demand, and the controller adds more polymer as depicted by the amount of polymer being in the control band (see FIG. 5 weeks 4-24).

[0076] The make-up water conductivity was very consistent from week to week and varied between 123-132 pmhos/cm (Table 4). The conductively target for this tower was set to the 650-800 pmho/cm range. The tower operated in this range for most of time (FIG. 7). This translated to 5.0 - 6.5 cycles of concentration.

[0077] However, the conductivity during week 18 was 1000 pmho/cm (FIG. 8) which was higher than the 800 pmho/cm set point due to malfunctioning of the blow down system. The issue was not noticed till the weekly field visit by the engineer. The issue was that the solenoid valve in the blow down was malfunctioning increasing the cycles of concentration and the polymer load on system. However, the controller probably did feed extra polymer during that time even though the polymer signal was fairly stable and consistently in the middle of the control band (FIG. 6). The problem was temporarily fixed by manual blow down till the valve could be replaced. This illustrates the point that the tagged polymer buys time to take care of system malfunctions that cause disruptions. Nevertheless, it is not a panacea, and the root cause of the issue needs to determined and corrective action needs to be taken to bring the system back to normal operating conditions.

[0078] The iron (Fe) in the make-up was targeted to be less than 0.25 ppm after filtration and the iron in the cooling towers was targeted to be less than 2 ppm. As mentioned above, Fe may precipitate out polymers from the system increasing the polymer demand. However even if some precipitation occurs, the tagged polymers allow for increased polymer usage and can increase the amount of polymer in the system to account for this.

[0079] The iron levels in the make-up water and the cooling tower are depicted in

FIG. 9. [0080] The Fe levels in the make-up water was 0.8 during week 20 (FIG. 9). It was determined at the next weekly visit by the field engineer that Fe removal prefilter not working during that the previous week. As a result, the Fe levels in the cooling towers were abnormally high and in the 2.7-2.8 ppm range (FIG. 9) during week 20. However, the controller probably fed in extra polymer due to the increased load on the system and the tagged polymer level during week 20 was well within the targeted level or band (FIG. 6).

[0081] The free chlorine for the various towers during this time is depicted in the FIG. 10 below. The goal was to maintain at least a 0.2 ppm of free chlorine and ideally between 0.2 and 1 ppm. However, as this chart shows the free chlorine levels are in the 4-7 ppm range (see for example weeks 5, 7, 10, 14, 18, 20 and 23) mainly due to chronic issues with the chlorine addition system.

[0082] In spite of these spikes in free chlorine levels (FIG. 10), the controller data showed a steady polymer signal (FIG. 6) for weeks 5 -24 even when the chlorine levels were high in weeks 5, 7, 10, 14, 18 (see weekly data in FIG. 6), 20 and 23. This indicated that the polymer signal during these time periods (see FIG. 6 for weeks 4 to 24 and FIG. 5 for week 18) was consistent and did not go down when high levels of chlorine were in the system. This is critical since if the polymer signal were to decrease in the presence of unusually high levels of chlorine, the system would unnecessarily have more polymer pumped in than needed just due to the deficiency of the tag.

[0083] Finally, the customer is happy with this system that contains Tagged Polymer B in the formulation since the weekly reports show a steady polymer signal within the control limits band. This is a clear indication that the scaling issues they had encountered in the past have been remedied. The trial per se is complete and the water treater is continuing to use this formulation containing Tagged Polymer B in this large tower.

Example 2: Case Study 2:

[0084] Tagged Polymer A was used in a mid-sized evaporative tower used for comfort cooling using a stabilized phosphate. The cycles of concentration were controlled by conductivity in the range 1150-1200 pmho/cm.

[0085] This tower has a history of significant variability of phosphate levels in the makeup water from the city, which combined with the phosphate from the formulation had caused calcium phosphate scaling issues in the past. The trial used existing monitoring and feed equipment. The formulation for the trial did not contain any phosphate since there was enough phosphate in the system from the make-up water. Tagged Polymer A replaced PTSA and a premium untagged (phosphate inhibiting) polymer in the new stabilized phosphate formulation. The PTSA fluorometer was calibrated with 10 ppm polymer solution and was used to monitor the polymer. Stabilized bromine was added to the system as a slug every day.

[0086] The fluorometer (polymer signal) reading for a period of time from the controller in the cooling tower is shown in FIG. 10. The steady polymer signal shows that the change in phosphate levels in the make-up water was not leading to a decrease in polymer level. This indicates that the polymer levels were high enough (15-17 ppm) to take care of this level of disruption in the phosphate make-up levels.

[0087] Samples of the make-up water and the cooling tower water were taken at intermediate times during the trial. Several parameters were measured on the samples, including fluorescence (to monitor active polymer) and filtered and unfiltered phosphate to determine the level of phosphate scale control.

Table 6: Makeup water and tower readings in Case Study 2.

[0088] Analysis of the make-up water show that the phosphate in the make-up water varied between 1 to 2.8 ppm over the five months (Table 6). The cycles of concentration were 8 and therefore the total phosphate in the system varied between 8 and 22 ppm just from the make-up water, which is a large amount.

[0089] The pH of the make-up varied between 7.3-7.9. However, the pH in the tower varied between 7.5 to 9.2 in these samples (Table 6) which is a large variation in pH. Therefore, it appears that the pH was not well controlled and the periods where the pH was high (8-9.2) would lead to increased scaling tendencies.

[0090] The large amount of phosphate and large variability in pH explains the reasons why this tower was fouling up with scale in the past. [0091] The phosphate inhibition numbers (calculated by dividing filtered phosphate by unfiltered phosphate of Table 6) were above 90% (FIG. 12). This clearly demonstrates that tower was running well, and the scale was controlled. This was significant because the scaling tendency of the system fluctuated widely and increased drastically due to the fluctuations in make-up water phosphate and high pH levels in the tower which led to scale formation and fouling of the tower in the past. Nevertheless, the amount of polymer added was enough to control the phosphate scale as shown by the steady level of polymer as read by the controller in FIG. 11 (blue dots) and in spot checked samples FIG. 12 (gray line). If the polymer was not in control of the scale, the polymer signal would have decreased (which it did not, see blue dots in FIG. 11, and the gray line in FIG. 12). The combination of steady and constant polymer signal supplemented with the phosphate inhibition data clearly shows that the system is in control under conditions of failure in the past.

Example 3: Case Study 3:

[0092] Trace Blackmore has conducted field tnals for both Tagged Polymers A and B in small facilities. See Blackmore, T., (Sept. 22-25, 2021), “Field Trials and Observations of Tagged Polymers”, AWT 2021 Conference, Providence, Rhode Island, Association of Water Technologies, Providence, Rhode Island. These facilities were 300-ton cooling towers or less (lower system volumes). The trials were conducted over a period of 22 weeks. The formulations used in these trials were proprietary and it is not clear if a phosphonate was present in these formulations. It is presumed that the system was a stabilized phosphate or neutral pH system since sulfonated copolymers that are typically used in these systems were used in this study and the study reported phosphate levels of 7-19 ppm of total inorganic phosphate. See Blackmore, T , (Sept. 22-25, 2021), “Field Trials and Observations of Tagged Polymers”, AWT 2021 Conference, Providence, Rhode Island, Association of Water Technologies, Providence, Rhode Island.

[0093] This study confirmed that when the stress on the system was increased by increasing the iron to 1. 1 ppm, the PTS A signal was constant but the tagged polymer signal decreased. Furthermore, the corrosion rates for both mild steel and copper were found to be acceptable. Blackmore’s data indicate that both types of polymers perform well in the field and found no difference between the tagged polymers compared to the original untagged polymer in the areas of scale control, corrosion control, stability and blendability. It is up to the operator to decide which type of polymer they need to use in their formulations. The conclusions of this study were:

[0094] “The ability to test both product addition (PTSA signal) and active polymer can provide more data about the treated system allowing the water treater to make better decisions”. See Standish, M., (Sept. 22-25, 2021), “Proper Use of fluorescent tagged polymers -Do’s and Don’ts”, AWT 2021 Conference, Providence, Rhode Island, Association of Water Technologies, Providence, Rhode Island.

Formulations:

[0095] Formulation changes for formulations stabilized phosphate or neutral pH programs:

[0096] For stabilized phosphate formulations operating in a neutral pH, the phosphonate will be removed from the formulation. The untagged phosphate inhibiting polymer (normally AA-AMPS) and PTSA in the formulation is replaced by the Tagged Polymer A (Table 7 below). Phosphate scale is the major issue in these systems, and therefore it is important to detect the level of the tagged polymer that inhibits phosphate scale which can be done using Tagged Polymer A. Tagged Polymer A is a good calcium carbonate scale control polymer and should take care of any carbonate scale if it is formed. Since this uses Tagged Polymer A, the same detectors used to detect PTSA can be used, and it is important that PTSA be removed from the formulation. This will potentially reduce the blending complexity of using PTSA and possibly cost of the formulation.

Table 7: Product formulation for using phosphate as a corrosion inhibitor.

[0097] This type of simplified approach was recommended by Frayne who was prescient in predicting this as a way of the future: “When formulating for any particular problem, it is often useful to mix a primary and backup inhibitor together. This does not mean, however, that the formulation package must, of necessity, contain a great many chemistries, as a specific chemistry may be pnmary in one effect secondary' in a minor effect, and tertiary in still another effect. Thus, by careful selection and mixing of vendor blends, we can provide synergistic inhibitor effects with only a very limited number of chemistries. This age simplicity, reduces inventory costs, and is likely to be the way of the future.” See Frayne, C., “Organic Water Treatment Inhibitors: Expansion of current guidelines, myths, misinformation, and the next generation of novel chemistries”- Part II, The Analyst, Volume 16, Number 4, 2009. The primary benefit of Tagged Polymer A is phosphate, iron and zinc stabilization as well as dispersancy with the secondary' benefit being calcium carbonate scale control. The polymer signal would decrease if the polymer was consumed by either the primary' or secondary' benefit or mixture of the two. Therefore, it makes this polymer very suitable for phosphonate replacement in these stabilized phosphate or neutral pH systems. Finally, these changes make the formulation simpler while giving the water treater to track multiple actives such as carbonate (PMA and phosphonate) control agents and phosphate scale control agent and dispersant (AA-AMPS or terpolymer) by simply tracking one active.

[0098] As described in WO 2019/025305, the Tagged Polymer A can in some embodiments be prepared by functionalizing a pyranine compound with a polymenzable moiety, typically a moiety with a carbon-carbon double bond, to form a fluorescent monomer. Because the unfunctionalized fluorescent compound and the functionalized fluorescent monomer are chemically very similar, it can be difficult to separate any unfunctionalized fluorescent compound starting material remaining from the monomer reaction product. If this monomer reaction product containing both the desired monomer and the undesirable unfunctionalized fluorescent compound is then added to a polymerization reaction mixture in the polymerization of a water soluble fluorescent tagged polymer, then the unfunctionalized fluorescent compound can also be present in the polymerization reaction product composition. The unfunctionahzed fluorescent compound will likewise be difficult to separate from the polymerization reaction product composition. Accordingly, in a preferred embodiment, steps will be taken to ensure the Tagged Polymer A is substantially free of unfunctionalized and unpolymerized pyranine. In a preferred embodiment, the Tagged Polymer A comprises less than 5 mol%, or less than 4 mol%, or less than 3 mol%, or less than 2 mol%, or less than 1 mol%, or less than 0.5 mol%, or is even completely free of total unfunctionalized and unpolymerized pyranine, based on the moles of total pyranine in the composition.

Formulation changes for low or zero phosphate or alkaline pH:

[0099] For formulations used in low or zero phosphate systems, the carbonate scale control polymer (typically some version of PMA) in the formulation is replaced by the Tagged Polymer B (Table 8 below). Carbonate scale is the major issue in these systems, and therefore it is important to detect the level of the tagged polymer that inhibits carbonate scale. Tagged Polymer B is a much superior carbonate inhibitor to most PMA’s and the formulator should see a boost in carbonate inhibition performance. This assertion is verified in actual field conditions by Case Study 1 above.

Table 8: Product formulation for low or zero phosphate systems.

[00100] If phosphonates are available, then one could leave it in these formulations since the calcium carbonate scaling tendency is high. Nevertheless, a Tagged Polymer B is strongly recommended because of the advantage of monitoring a key active component in the system.

[00101] As described in US 11,208,408, known processes for preparing polymers like Tagged Polymer B may lead to the tagged polymers containing relatively large amounts of precursor non-quatemized amines. The presence of these non-quatemized amine moieties in the polymer will lead to the fluorescent signal becoming unreliable as remainders of these non-quatemized amines also will give a fluorescent signal in unexpectedly the same wavelength region, while they will not have any role in scale prevention and reduction. Accordingly, in a preferred embodiment, steps will be taken to ensure the Tagged Polymer B is substantially free of unfunctionalized and unpolymerized non-quatemized amines. In a preferred embodiment, the Tagged Polymer B comprises less than 8 mol %, preferably less than 7 mol %, more preferably less than 6 mol %, more preferably less than 5 mol %, more preferably less than 3 mol %, more preferably less than 2 mol %, and most preferably less than 1.5 mol % or is even completely free of the unfunctionalized and unpolymerized non- quatemized amines relative to the total molar amount of Tagged Polymer B in the composition.

[00102] Tagged Polymer A was tested in a stabilized phosphate system that did not contain phosphonate. All test samples contained 2 ppm iron and 5 ppm orthophosphate. Varying levels of hardness (calcium and magnesium) and alkalinity (bicarbonate) were added to evaluate the effect on the polymer performance. Calcium Carbonate Static Test Conditions at 1 cycle of

Table 9

Table 10

[00103] In this test, >90% inhibition for calcium indicates that the polymer is effective against calcium carbonate scale, and >80% phosphate indicates that the polymer is effective against calcium phosphate scale. 20 ppm polymer is effective for controlling both calcium carbonate and calcium phosphate scales at all COC levels. 10 ppm polymer is effective at COC of 2.0 and 2.2. The ppm tagged polymer detected indicates the level of stress that the system has on the polymer. In general, when the polymer is not working well, the detected polymer is significantly lower than the amount added. When the polymer is working well (scale is not being formed), the amount of polymer detected by the fluorometer is close to the amount added. In this system, the tagged polymer replaced phosphonate, untagged calcium carbonate control polymer and untagged calcium phosphate control polymer and demonstrates that tagged polymer can replace these components in a formulation. Conclusions

[00104] Tagged polymers allow the water treater to measure the active polymer in the system. An additional benefit is the polymer signal decreases as the scaling stress increases. This gives the water treater and their customer a clear picture of how the system is operating. Due to the shortage of phosphonates, cooling systems are stressed because polymers alone need to carry out the bulk of the deposit control load. This makes it even more imperative to measure the active ingredient, namely the polymer in these systems. We have presented case studies that clearly demonstrate that tagged polymers can be used in the field in these systems for both low or zero phosphate or alkaline pH treatments as well as stabilized phosphate or neutral pH programs. In addition, we have recommended the necessary' formulation changes for both stabilized phosphate/neutral pH treatments and alkaline pH treatments. It is likely that all customers and consultants will mandate that active components in the formulation need to be measured whenever possible. This technology gives the AWT market a tool that was not previously available to them and allows them to be on par with the bigger companies in this area.

[00105] The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the disclosure. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the systems and methods described herein. The foregoing descriptions of specific examples are presented for purposes of illustration and description. The examples are not intended to be exhaustive of or to limit this disclosure to the precise forms described. Obviously, many modifications and variations are possible in view of the above teachings. The examples are shown and described in order to best explain the principles of this disclosure and practical applications, to thereby enable others skilled in the art to best utilize this disclosure and various examples with various modifications as are suited to the particular use contemplated. It is intended that the scope of this disclosure be defined by the claims and their equivalents below.

Claims

We claim:

1. A water treatment formulation for stabilized phosphate systems operating in a neutral pH, comprising:

(a) at least one corrosion inhibitor; and

(b) a T agged Polymer A; wherein the formulation is substantially free of phosphonate.

2. The water treatment formulation according to claim 1, which is substantially free of PTSA (1,3, 6, 8 pyrenetetrasulfonic acid, sodium salt).

3. The water treatment formulation according to claim 1 or claim 2, which is substantially free of PMA (polymaleic anhydride).

4. The water treatment formulation according to any of the previous claims, which is completely free of phosphonate.

5. The water treatment formulation according to any of the previous claims, which:

(a) comprises at least one corrosion inhibitor;

(b) comprises a Tagged Polymer A;

(c) is completely free of phosphonate;

(d) is completely free of PTSA (1,3, 6, 8 pyrenetetrasulfonic acid, sodium salt); and

(e) is completely free of PMA (polymaleic anhydride).

6. The water treatment formulation according to any of the previous claims, wherein the Tagged Polymer A is a copolymer of acrylic acid, 2-acrylamido-2-methyl propane sulfonic acid, and methalyloxy pyranine as a partial sodium salt.

7. A water treatment formulation for low or zero phosphate or alkaline pH systems, comprising:

(a) phosphonate; and (b) a Tagged Polymer B; wherein the formulation is substantially free of a scale control polymer other than said Tagged Polymer B.

8. The water treatment formulation according to claim 7, which is substantially free of PMA (polymaleic anhydride).

9. The water treatment formulation according to claim 7 or claim 8, which is completely free of PMA (polymaleic anhydride).

10. The water treatment formulation according to any of claims 7-9, which:

(a) comprises phosphonate;

(b) comprises a Tagged Polymer B;

(c) comprises PTSA (1,3, 6, 8 pyrenetetrasulfonic acid, sodium salt);

(d) is completely free of PMA (polymaleic anhydride); and

(e) is completely free of a scale control polymer other than said Tagged Polymer B.

11. The water treatment formulation according to any one of claims 7-10, wherein the Tagged Polymer B is a copolymer of acrylic acid, methyl methacrylate, maleic acid, 2-acrylamido- 2 -methyl propane sulfonic acid and 4-methoxy-N-(3-dimethylaminopropyl)-l,8-naphthalimide, 1 or 2 -hydroxy-3 -allyloxy propyl, quaternary salt as a partial sodium salt.

12. The water treatment formulation according to claim 11, wherein the Tagged Polymer B is substantially free of unfunctionalized and unpolymerized non-quatemized amines.

13. A method of treating water susceptible to forming phosphate scale in a stabilized phosphate systems operating in a neutral pH, said method comprising:

(a) treating the water with a water treatment formulation according to any one of claims

1-6;

(b) detecting the level of Tagged Polymer A that inhibits the formation of phosphate scale; and (c) adjusting the level of Tagged Polymer A as necessary to inhibit the formation of phosphate scale.

14. A method of treating water susceptible to forming carbonate scale in a low or zero phosphate or alkaline pH system, said method comprising:

(a) treating the water with a water treatment formulation according to any one of claims 7-12; (b) detecting the level of Tagged Polymer B that inhibits the formation of carbonate scale; and

(c) adjusting the level of Tagged Polymer B as necessary to inhibit the formation of carbonate scale.