This invention relates to a technique for controlling fouling in high efficiency cooling tower fill, particularly in evaporative film media such as Munters fill, comprising including to cooling water vulnerable to cause fouling which contacts mentioned fill an efficient quantity of a low molecular weight, water-soluble 2-acrylamido-2-methylpropyl sulfonic acid/acrylic acid-kind polymer.
Such polymers are commercially obtainable from Calgon Company, Pittsburgh, Pa., as TRC-233.RTM. and TRC-271.RTM..
Using such polymers is well known in the water remedy art. For instance:
U.S. Pat. No. Three,928,196 discloses the usage of copolymers of two-acrylamido-2-methylpropyl sulfonic acid and acrylic acid as scale inhibitors.
U.S. Pat. No. Four,640,793 discloses the usage of admixtures containing carboxylic acid/sulfonic acid polymers and phosphonates as scale and corrosion inhibitors.
U.S. Pat. No. 4,618,448 discloses the usage of polymers comprising an unsaturated carboxylic acid, an unsaturated sulfonic acid and an unsaturated polyalkylene oxide as scale inhibitors.
Japanese No. 57-084794 discloses the usage of copolymers of acrylic acid and allyl polyethylene glycol as scale inhibitors.
European patent software 84301450.7 discloses carboxylic acid/sulfonic acid copolymers together with natural phosphonates as scale inhibitors.
U.S. Pat. No. Four,510,059 discloses the use of carboxylic functional polyampholytes to scale back silica deposits in aqueous systems.
U.S. Pat. No. Four,936,987 discloses acrylic acid/2-acrylamido-2-methyl propyl sulfonic acid-kind polymer compositions and the use thereof as scale and corrosion inhibitors in water therapy.
U.S. Pat. No. Three,709,816 discloses the use of 2-acrylamido methylpropyl sulfonic acid polymers to fluidize and disperse alluvial deposits in aqueous systems, including cooling towers. This reference doesn’t, nevertheless, disclose the efficacy of the instant low molecular weight polymers to manage fouling, including biofouling, in high efficiency evaporative film fills.
U.S. Pat. No. 3,709,815 discloses the use of 2-acrylamido-2-methylpropyl sulfonic acid polymers as boiler water dispersives and conditioners.
Whereas varied uses of the instant polymers are widely known in the artwork, the instant inventors do not believe that the use of low molecular weight, water soluble acrylic acid/acrylamido-2-methylpropyl sulfonic acid-type polymers to manage fouling, including biofouling, in high efficiency cooling tower fill is known or prompt within the art.
In high effectivity hyperbolic natural draft towers, fouling is especially troublesome. As used herein, the time period “fouling” refers to the buildup on or in cooling tower fill media of one or more biofouling agents, alone or together with insoluble supplies chosen from the group consisting of alluvial solids, clays, muds, silts, insoluble metallic scales and metallic salts or oxides. Biological growth, including however not limited to that caused by algae and micro organism, comprises biofouling solids. Such fouling/biofouling adversely impacts the efficiency of the fill used in cooling towers by plugging the fill, impeding flow through the fill and/or disrupting film formation, thereby diminishing heat transfer.
Evaporative film-forming fills are generally used in right now’s cooling towers. These fills comprise flat or formed sheets that are usually fabricated from a plastic materials reminiscent of polypropylene or PVC. Water movies form on these plastic sheets, which facilitates heat transfer between the water movie and air passing by means of the cooling tower. As used herein, “high effectivity cooling tower fill” refers to evaporative film media used in high efficiency cooling towers. This sort of fill (for instance, Munter’s fill) is especially inclined to fouling generally and biofouling specifically.
Transient DESCRIPTION OF THE DRAWINGS
FIGS. 1 and 2 demonstrate the impact of an acrylic acid/2-acrylamido-2-methylpropyl sulfonic acid polymer on cooling tower suspended solids. Application of the polymer raised the level of suspended solids in the blowdown above make-up suspended solids levels, which signifies that clean-up of cooling tower fill occurred.
DESCRIPTION OF THE INVENTION
The moment invention is directed to a method for controlling fouling, together with biofouling, in high efficiency cooling tower fill comprising adding to water having a tendency to foul said high effectivity cooling tower fill an efficient quantity for the purpose of a water-soluble polymer comprising:
a) acrylic acid or methacrylic acid; and
b) 2-acrylamido-2-methylpropyl sulfonic acid or 2-methyacrylamido-2-methylpropyl sulfonic acid; whereby the load ratio of a):b), on an active basis, ranges from about 4:1 to about 1:1; and wherein the molecular weight of the polymer ranges from about 1,000 to about 12,000.
Whereas the instant polymers may include additional mer units, the preferred polymers are copolymers of acrylic acid and a pair of-acrylamido-2-methylpropyl sulfonic acid, hereinafter known as AA/SA polymers. Probably the most most well-liked polymers are 60/forty w/w copolymers of acrylic acid and 2-acrylamido-2-methylpropyl sulfonic acid having a molecular weight of about 7500-9500. Such polymers are commercially obtainable from Calgon Company, Pittsburgh, Pa., as TRC-233.RTM.. One other most popular polymer is a terpolymer comprising acrylic acid, 2-acrylamido-2-methylpropyl sulfonic acid and a polyalkylene oxide which is commercially available from Calgon as TRC-271.RTM..
While the instant polymers are believed to be efficient on all sorts of excessive efficiency, evaporative film media, they’re believed to be particularly efficient on plastic high efficiency fill materials resembling “Munters” fill, which is commercially available from the Munters Corporation. Thus, the moment inventors have discovered that these polymers considerably cut back fouling, together with biofouling, in cooling towers, together with hyperbolic cooling towers containing Munters fill the place conventional water treatment scale inhibitors comparable to acrylic acid/hydroxy propylacrylate (AA/HPA) copolymers are believed to be largely ineffective.
The moment polymers might be added to cooling water which tends to cause fouling and biofouling issues in or on high efficiency fill material by any handy means. Addition of the moment polymers to cooling tower water is believed by the inventors to be effectively within the talent of those aware of cooling tower operations.
An efficient amount of the moment polymer must be added to cooling water vulnerable to trigger fouling and biofouling in or on excessive performance fill. Preferably, the dosage of the moment polymers, on an energetic basis, should range from about 0.1 to about 500 ppm, based on the weight of water within the system being treated. More preferably, the dosage ought to range from about 0.1 to about 50 ppm. While there isn’t a identified higher dosage limitation, based on the efficiency, the higher restrict is generally dictated by economic issues or discharge permits.
The moment polymers can be used along side other cooling tower additives, including but not limited to corrosion inhibitors, biocides, and many others.
In summary, it has been discovered that low molecular weight, water soluble polymers of two-acrylamido-2-methylpropyl sulfonic acid and acrylic acid are efficient in controlling the fouling, including biofouling, of excessive efficiency fill materials present in cooling towers. These polymers are particularly effective in treating natural draft hyperbolic cooling towers which contain Munters fill.
As such, the invention constitutes an enchancment over the disclosure of U.S. Pat. No. 3,709,816, which is silent regarding the power of low molecular weight, water soluble, acrylic acid/2-acrylamido-2-methylpropyl sulfonic acid acid-sort polymers to manage fouling, significantly biofouling, on high efficiency fill equivalent to Munter’s fill.
The following instance further demonstrates the instant invention. The instance will not be, nonetheless, supposed to limit the invention in any method.
A pure draft hyperbolic cooling tower containing high performance evaporative movie fill (Munter’s fill) experienced severe fouling. The fouling deposits contained large quantities of insoluble scale and silt and average amounts of aerobic bacteria and algae.
0.28 active ppm, primarily based on complete cooling water weight, of a copolymer of acrylic acid 2-acrylamido-2-methylpropyl sulfonic acid (TRC-233.RTM., commercially obtainable from Calgon Company, Pittsburgh, Pa.) was added to the tower makeup. The polymer effectively managed fouling in the Munter’s fill.
Additional, a gradual cleanup of the fouled cooling tower fill occurred as is proven in FIG. 1. That is evidenced by the truth that the suspended solids stage in the blowdown was greater than in the makeup.
FIG. 2 shows the same cooling tower which was not handled with the AA/SA copolymer. On this figure, the suspended solids level is decrease in the blowdown than in the make-up. This signifies that fouling occurred in the absence of the AA/SA polymer.