EP1499457A1 - Procede de nettoyage et de desinfection simultanes de systemes d'approvisionnement en eau industrielle - Google Patents

Procede de nettoyage et de desinfection simultanes de systemes d'approvisionnement en eau industrielle

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Publication number
EP1499457A1
EP1499457A1 EP03719966A EP03719966A EP1499457A1 EP 1499457 A1 EP1499457 A1 EP 1499457A1 EP 03719966 A EP03719966 A EP 03719966A EP 03719966 A EP03719966 A EP 03719966A EP 1499457 A1 EP1499457 A1 EP 1499457A1
Authority
EP
European Patent Office
Prior art keywords
water
acid
water system
industrial water
added
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP03719966A
Other languages
German (de)
English (en)
Other versions
EP1499457A4 (fr
Inventor
Andrew J. Cooper
Jasbir S. Gill
Amit Gupta
Robert F. Kelly
Douglas G. Kelly
Eric R. Myers
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ChampionX LLC
Original Assignee
Nalco Co LLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US10/135,317 external-priority patent/US8668779B2/en
Application filed by Nalco Co LLC filed Critical Nalco Co LLC
Priority to EP09158817A priority Critical patent/EP2077163A1/fr
Publication of EP1499457A1 publication Critical patent/EP1499457A1/fr
Publication of EP1499457A4 publication Critical patent/EP1499457A4/fr
Withdrawn legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L2/00—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor
    • A61L2/16—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor using chemical substances
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L2/00—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor
    • A61L2/16—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor using chemical substances
    • A61L2/18—Liquid substances or solutions comprising solids or dissolved gases
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L2/00—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor
    • A61L2/16—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor using chemical substances
    • A61L2/20—Gaseous substances, e.g. vapours
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L9/00—Disinfection, sterilisation or deodorisation of air
    • A61L9/14—Disinfection, sterilisation or deodorisation of air using sprayed or atomised substances including air-liquid contact processes
    • A61L9/145—Disinfection, sterilisation or deodorisation of air using sprayed or atomised substances including air-liquid contact processes air-liquid contact processes, e.g. scrubbing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B08—CLEANING
    • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B9/00—Cleaning hollow articles by methods or apparatus specially adapted thereto 
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B08—CLEANING
    • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B9/00—Cleaning hollow articles by methods or apparatus specially adapted thereto 
    • B08B9/02—Cleaning pipes or tubes or systems of pipes or tubes
    • B08B9/027—Cleaning the internal surfaces; Removal of blockages
    • B08B9/032—Cleaning the internal surfaces; Removal of blockages by the mechanical action of a moving fluid, e.g. by flushing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B08—CLEANING
    • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B9/00—Cleaning hollow articles by methods or apparatus specially adapted thereto 
    • B08B9/08—Cleaning containers, e.g. tanks
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/50—Treatment of water, waste water, or sewage by addition or application of a germicide or by oligodynamic treatment
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
    • C09K8/52—Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning
    • C—CHEMISTRY; METALLURGY
    • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
    • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
    • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
    • C11D3/395—Bleaching agents
    • C11D3/3956—Liquid compositions
    • C—CHEMISTRY; METALLURGY
    • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
    • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
    • C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
    • C11D7/02—Inorganic compounds
    • C11D7/04—Water-soluble compounds
    • C11D7/08—Acids
    • C—CHEMISTRY; METALLURGY
    • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
    • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
    • C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
    • C11D7/22—Organic compounds
    • C11D7/26—Organic compounds containing oxygen
    • C11D7/265—Carboxylic acids or salts thereof
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28G—CLEANING OF INTERNAL OR EXTERNAL SURFACES OF HEAT-EXCHANGE OR HEAT-TRANSFER CONDUITS, e.g. WATER TUBES OR BOILERS
    • F28G9/00—Cleaning by flushing or washing, e.g. with chemical solvents
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L2202/00—Aspects relating to methods or apparatus for disinfecting or sterilising materials or objects
    • A61L2202/10—Apparatus features
    • A61L2202/17—Combination with washing or cleaning means
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/02—Non-contaminated water, e.g. for industrial water supply
    • C02F2103/023—Water in cooling circuits
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00—Specific treatment goals
    • C02F2303/04—Disinfection
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00—Specific treatment goals
    • C02F2303/08—Corrosion inhibition
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water or sewage
    • C—CHEMISTRY; METALLURGY
    • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
    • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
    • C11D2111/00—Cleaning compositions characterised by the objects to be cleaned; Cleaning compositions characterised by non-standard cleaning or washing processes
    • C11D2111/10—Objects to be cleaned
    • C11D2111/14—Hard surfaces
    • C11D2111/20—Industrial or commercial equipment, e.g. reactors, tubes or engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F2265/00—Safety or protection arrangements; Arrangements for preventing malfunction
    • F28F2265/20—Safety or protection arrangements; Arrangements for preventing malfunction for preventing development of microorganisms

Definitions

  • This invention is in the field of industrial water systems. Specifically, this invention is in the field of cleaning and disinfection of industrial water systems.
  • Fouling is defined as "the deposition of any organic or inorganic material on a surface". If these industrial water systems are not periodically cleaned, then they will become heavily fouled. Fouling has a negative impact on the industrial water system. For example, severe mineral scale (inorganic material) will buildup on the water contact surfaces and anywhere there is scale, there is an ideal environment for the growth of microorganisms. Evaporative cooling water systems are particularly prone to fouling.
  • This fouling occurs by a variety of mechanisms including deposition of air-borne and water- borne and water-formed contaminants, water stagnation, process leaks, and other factors. If allowed to progress, the system can suffer from decreased operational efficiency, premature equipment failure, and increased health-related risks associated with microbial fouling. Fouling can also occur due to microbiological contamination. Sources of microbial contamination in industrial water systems are numerous and may include, but are not limited to, air-borne contamination, water make-up, process leaks and improperly cleaned equipment. These microorganisms can establish microbial communities on any wetable or semi-wetable surface of the water system. Once these microbial populations are present in the bulk water more than 99% of the microbes present in the water will be present on all surfaces.
  • biofilms are complex ecosystems that establish a means for concentrating nutrients and offer protection for growth, and biofilms can accelerate scale, corrosion, and other fouling processes. Not only do biofilms contribute to reduction of system efficiencies, but they also provide an excellent environment for microbial proliferation that can include Legionella bacteria. It is therefore important that biofilms and other fouling processes be reduced to the greatest extent possible to minimize the health-related risk associated with Legionella and other water-borne pathogens.
  • a simple mechanical cleaning program consists of "power washing” and “scrubbing".
  • Power washing refers to the use of high-pressure water directed at equipment surfaces such that the impact of the water on the surface removes deposits from those surfaces that can be reached.
  • Mechanical cleaning strategies do not always remove all heavily adhering deposits such as deposited scale and biological slime from equipment surfaces. Further limitations on the use of mechanical cleaning include the fact that such methods are effective at removing only loose deposits, and not for removing deposits from within the fill (in the case of a cooling tower). For systems such as domestic water distribution pipes, power washing is completely ineffective. Mechanical cleaning methods also do not provide a means of disinfection, which is crucial to maintaining clean and safe equipment.
  • Hyperhalogenation Protocol One standard procedure that uses hyperhalogenation and surfactant is commonly known as the "Wisconsin Protocol", see “CONTROL OF LEGIONELLA IN COOLING TOWERS", Summary Guidelines, Section of Acute and Communicable Disease Epidemiology, Bureau of Community Health and Prevention, Division of Health, Wisconsin Department of Health and Social Services, August 1987.
  • the Wisconsin Protocol is used to disinfect an industrial water system following a Legionellosis outbreak. Even in the absence of an outbreak, hyperhalogenation is commonly used to reduce microbial fouling in water systems. Hyperhalogenation protocols do not remove mineral scale, thereby limiting their ability to remove or reduce biological foulants. In addition, the hyperhalogenation procedures that require a biodispersant have limited effectiveness within the period the protocol is implemented.
  • Chlorine dioxide must be generated on-site where it is applied.
  • One of these methods uses acid in combination with sodium chlorite (acid activation).
  • the chlorine dioxide is generated using sodium chlorite and hydrochloric acid as follows:
  • the reactants sodium chlorite and hydrochloric acid
  • the products chlorine dioxide, sodium chloride, water, some remaining unreacted sodium chlorite, and hydrochloric acid
  • chlorine dioxide is diluted and either lost through volatility or is reduced by substances within the water system.
  • chlorine dioxide must be constantly generated outside the water system, and injected into the system to maintain a chlorine dioxide residual.
  • Patent Cooperation Treaty Patent Application WO 02/12130 Al describes and claims a method of treating water in a water distribution system, comprising: admixing a sodium chlorite solution with a second solution containing an acid to make a reacted mixture; and introducing a predetermined amount of the reacted mixture into a water system.
  • the preferred method of treating water includes the addition of a catalyst, wherein the catalyst is sodium molybdate.
  • United Kingdom Patent Application No. 2,313,369 describes and claims an aqueous composition having a pH of more than 9 consists of a stabilized chlorine dioxide precursor, an alkali metal polyphosphate and an alkali metal hydroxide. It also describes and claims a method of treating water in a water distribution system comprising the addition of an acid activator to the aqueous composition to reduce the pH to less than 7 and injecting the aqueous solution in to the water system. It would be desirable to have a method for simultaneously cleaning and disinfecting an industrial water system.
  • the first aspect of the instant claimed invention is a method of simultaneously cleaning and disinfecting an industrial water system comprising the steps of : a) providing an industrial water system; b) adding to the water of said industrial water system i) a Compound, wherein said Compound is selected from the group consisting of the alkali salts of chlorite and chlorate, or a mixture thereof; and ii) an acid; wherein said acid is added before the Compound is added; and c) allowing the water to circulate through the industrial water system for at least from about one to about 72 hours; and d) draining the water from the industrial water system.
  • the second aspect of the instant claimed invention is a method of simultaneously cleaning and disinfecting an industrial water system comprising the steps of : a) providing an industrial water system; b) adding to the water of said industrial water system i) a Compound, wherein said Compound is selected from the group consisting of the alkali salts of chlorite and chlorate, or a mixture thereof; and ii) an acid; wherein said Compound is added before the acid is added; and c) allowing the water to circulate through the industrial water system for at least from about one to about 72 hours; and d) draining the water from the industrial water system.
  • the third aspect of the instant claimed invention is an on-line method of simultaneously cleaning and disinfecting an industrial water system comprising the steps of : a) providing an industrial water system; wherein said industrial water system is selected from the group consisting of cooling water systems and boiler water systems; b) optionally reducing the cycles of said industrial water system to single cycles and halting the feeding of the routine water maintenance chemicals to the water of the industrial water system; c) adding a Compound selected from the group consisting of the alkali salts of chlorite and chlorate, or a mixture thereof, and optionally adding a corrosion inhibitor and optionally adding a dispersant to the water of said industrial water system; wherein enough Compound is added to reach a concentration of from about 1 ppm to about 1000 ppm; wherein if a corrosion inhibitor is added enough corrosion inhibitor is added to reach a concentration of from about 50 ppm to about 500 ppm and wherein if a dispersant is added enough dispersant is added to reach a concentration of from about 1 ppm to about 500
  • the fourth aspect of the instant claimed invention is: an on-line method of simultaneously cleaning and disinfecting an industrial water system comprising the steps of : a) providing an industrial water system; wherein said industrial water system is selected from the group consisting of cooling water systems and boiler water systems; b) optionally reducing the cycles of said industrial water system to single cycles and halting the feeding of the routine water maintenance chemicals to the water of the industrial water system.
  • a chelating agent added to the water of the industrial water system, wherein enough chelating agent is added to maintain the concentration of the chelating agent at from about 10 ppm to about 500 ppm in the water of the industrial water system; wherein said chelating agent is added either before or after the optional next step of maintaining the pH; d) optionally maintaining the pH of the water in the industrial water system from about 5.5 to about 11 by either adding caustic or stopping the addition of acid or by a combination of both of these methods; e) adding a biocide to the water of the industrial water system; wherein if the chelating agent is added after the optional step of maintaining the pH, then the chelating agent and the biocide from step e) may be added simultaneously to the water or the chelating agent may be added first followed by the biocide or the biocide may be added first, followed by the chelating agent; wherein the amount of biocide added is that amount sufficient to have a concentration of from about 1 ppm to about 500 ppm in
  • fouling refers to the deposition of any organic or inorganic material on a surface. These deposits impede water flow and/or heat transfer, and harbor microorganisms that cause increased deposition, enhance corrosion and increase health-related risks.
  • “Cleaning” means reducing the overall quantity of deposits, which is desirable because reducing the overall quantity of deposits improves the overall efficiency of the industrial water system.
  • “Disinfection” is typically used to describe a method for killing microorganisms. As used herein, the goal of disinfection is to cause an overall significant reduction in the number or viability of microorganisms within the water system.
  • “ONC” refers to Ondeo Nalco Company, Ondeo Nalco Center, 1601 W. Diehl Road, Naperville, IL 60563, telephone (630) 305-1000.
  • the first and second aspects of the instant claimed invention are a method of simultaneously cleaning and disinfecting an industrial water system comprising the steps of : a) providing an industrial water system; b) adding to the water of said industrial water system i) a Compound selected from the group consisting of the alkali salts of chlorite and chlorate or a mixture thereof; and ii) an acid; and wherein said acid is added before the Compound is added, or the acid is added after the Compound is added; c) allowing the water to circulate through the industrial water system for at least from about one to about 72 hours ; and d) draining the water from the industrial water system.
  • the method of the instant claimed invention can be used to simultaneously clean and disinfect industrial water systems that are being installed, those that are currently in operation, are temporarily not operating, or have been inactive for extended periods and are being restored to service.
  • the method of the instant claimed invention can be used to clean and disinfect many industrial water systems.
  • These industrial water systems include, but are not limited to cooling water systems, including open recirculating, closed and once-through cooling water systems; boilers and boiler water systems; petroleum wells, downhole formations, geothermal wells and other oil field applications; mineral process waters including mineral washing, flotation and benefaction; paper mill digesters, washers, bleach plants, stock chests, and white water systems, and paper machine surfaces; black liquor evaporators in the pulp industry; gas scrubbers and air washers; continuous casting processes in the metallurgical industry; air conditioning and refrigeration systems; industrial and petroleum process water; indirect contact cooling and heating water, such as pasteurization water; water reclamation systems, water purification systems; membrane filtration water systems; food processing streams (meat, vegetable, sugar beets, sugar cane, grain, poultry, fruit and soybean); and waste treatment systems as well as in clarifiers, liquid-solid applications, municipal sewage treatment, municipal water systems, potable water systems, aquifers, water tanks, sprinkler systems and water heaters.
  • cooling water systems including open re
  • the preferred industrial water systems to be simultaneously cleaned and disinfected by the method of the instant claimed invention are cooling water systems, including open recirculating, closed and once-through cooling water systems, paper machine surfaces, food processing streams, waste treatment systems and potable water systems.
  • the most preferred industrial water systems to be simultaneously cleaned and disinfected by the method of the instant claimed invention are cooling water systems, including open recirculating, closed and once-through cooling water systems.
  • the Compound is selected from the alkali salts of chlorite and chlorate and mixtures thereof. These alkali salts include sodium chlorite, potassium chlorite, sodium chlorate and potassium chlorate. The preferred alkali salts are sodium chlorite and sodium chlorate.
  • the most preferred alkali salt is sodium chlorite
  • the alkali salts of chlorite and chlorate are commodity chemicals that can be obtained from most chemical supply companies.
  • Sodium chlorite can be obtained either at its normal pH or in its colloquially referred to "stabilized form" at an elevated pH.
  • the preferred sodium chlorite is a 25% solution of sodium chlorite in water. This material is available as HYG-25 from ONC.
  • Sodium chlorate is a commodity chemical that can be obtained from most chemical supply companies.
  • the preferred sodium chlorate is from about a 20 to about a 50 Wt/Wt % solution of sodium chlorate in water. This preferred sodium chlorate is available from Eka Chemicals, Inc., 1775 West Oak Commons Court, Marietta, GA 30062-2254 USA, telephone number 1-770-578-0858. Potassium chlorite and potassium chlorate are both available from most chemical supply companies.
  • the amount of sodium chlorite or potassium chlorite added to the water of the industrial water system depends upon what type of industrial water system is being cleaned and disinfected. If the method of the instant claimed invention is applied to a cooling water system, then the amount of sodium chlorite or potassium chlorite added is from about 1 ppm to about 1000 ppm, preferably from about 10 ppm to about 500 ppm and most preferably from about 50 ppm to about 250 ppm.
  • the amount of sodium chlorate or potassium chlorate added to the water of the industrial water system depends upon what type of industrial water system is being cleaned and disinfected. If the method of the instant claimed invention is applied to a cooling water system, then the amount of sodium chlorate added is from about 1 ppm to about 1000 ppm, preferably from about 10 ppm to about 500 ppm and most preferably from about 50 ppm to about 250 ppm. If sodium chlorite or potassium chlorite and sodium chlorate or potassium chlorate are both used then the ratio of chlorite to chlorate, expressed in weight percent, is from about 1:99 to about 99:1, preferably from about 10:90 to about 90:10, and most preferably about 50:50.
  • the total amount of both chlorite and chlorate together is the same as that for either chlorite or chlorate used separately.
  • the acid is selected from the group consisting of mineral acids and organic acids wherein said mineral acids are selected from the group consisting of hydrochloric acid, sulfuric acid, amido sulfuric acid (98%), nitric acid, phosphoric acid, hydrofluoric acid and sulfamic acid; and said organic acids are selected from the group consisting of citric acid and its salts, formic acid, acetic acid, peracids including peracetic acid, peroxyacetic acid and peroxyformic acid, glycolic acid (hydroxyacetic acid), oxalic acid, propionic acid, lactic acid (hydroxypropionic acid) and butyric acid.
  • the choice of acid depends primarily upon metallurgy within the system.
  • the preferred acids are hydrochloric acid, sulfamic acid, formic acid and glycolic acid.
  • the most preferred acid, for most metals, is hydrochloric acid.
  • These acids are commercial chemicals available from a chemical supply company. These acids can be purchased in dry or in liquid form or in formulations that contain other functional chemicals which also can be in dry or liquid form. For instance, most of these acids can be obtained in formulation with corrosion inhibitors. Hydrochloric acid formulated with a corrosion inhibitor made of diethyl urea is sold as Nalco®2560 Inhibited HC1 by ONC.
  • the amount of acid added to the water of the industrial water system depends upon what type of industrial water system is being cleaned and disinfected. If the method of the instant claimed invention is applied to a cooling water system, then the amount of acid added is that required to achieve and maintain a pH from about 1 to about 5, preferably from about 1 to about 3 and most preferably from about 2 to about 2.5. People of ordinary skill in the art know how to calculate how much of each acid would be required in order to achieve the desired pH by taking into account the system volume and the alkalinity within the system.
  • the Compound that is selected from the group consisting of the alkali salts of chlorite and chlorate and mixtures thereof and the acid are added directly to the water of the industrial water system, without being premixed prior to addition. Either the acid is added before the Compound or the Compound is added before the acid. It is possible, although not prefened, to add the acid and Compound simultaneously to the water.
  • the advantage of the instant claimed method is that it is possible to obtain continuous generation of chlorine dioxide disinfectant throughout the water system while also achieving simultaneous acid cleaning. Adding the Compound and the acid separately allows a certain amount of circulation of the Compound and acid prior to their reaction to create chlorine dioxide. This means more chlorine dioxide is created farther away from the point of addition of the Compound and the acid.
  • the water is allowed to circulate throughout the industrial water system.
  • This circulation of water allows the cleaning and disinfection of the "water-contact" surfaces of equipment in the industrial water system.
  • volatile chlorine dioxide is also capable of reaching surfaces that are not continuously in contact with water.
  • the water in the industrial water system is allowed to circulate for a time period of from about 1 hour to about 72 hours, preferably from about 1 hour to about 24 hours and most preferably from about 1 hour to about 8 hours.
  • the inorganic deposits are typically calcium salts, magnesium salts, iron oxide, copper oxide and manganese salts.
  • the inorganic deposits are typically calcium salts, magnesium salts, iron oxide, copper oxide and manganese salts.
  • the inorganic deposits are typically calcium salts, magnesium salts, iron oxide, copper oxide and manganese salts.
  • the water in the industrial water system must be drained and sent for appropriate treatment so that it can be discharged in compliance with state and local regulations.
  • These nooks and crannys can include the fill used in most cooling towers.
  • After mechanical cleaning is over it is possible to refill the water and begin operation of the industrial water system.
  • For heavily contaminated industrial water systems it is also possible to fill the industrial water system with water and conduct the method of the instant claimed invention again.
  • additional functional chemicals include additional biocides, corrosion inhibitors, dispersants, surfactants, reducing agents and chemicals added for pH adjustment.
  • Biocides suitable for use in the instant claimed invention are selected from the group consisting of oxidizing or non-oxidizing biocides.
  • Oxidizing biocides include, but are not limited to, chlorine bleach, chlorine, bromine and materials capable of releasing chlorine and bromine.
  • the prefened oxidizing biocide is chlorine bleach.
  • Non- oxidizing biocides include, but are not limited to, glutaraldehyde, isothiazolin, 2,2- dibromo-3-nitrilopropionamide, 2-bromo-2-nitropropane-l,3 diol, 1-bromo-l- (bromomethyl)- 1 ,3-propanedicarbonitrile, tetrachloroisophthalonitrile, alkyldimethylbenzylammomum chloride, dimethyl dialkyl ammonium chloride, didecyl dimethyl ammonium chloride, poly(oxyethylene(dimethyliminio)ethylene(dimethyliminio)ethylene dichloride, methylene bisthiocyanate, 2-decylthioethanamine, tetrakishydroxymethyl phosphonium sulfate, dithiocarbamate, cyanodithioimidocarbonate, 2-methyl-5-nitroimidazole-l- ethanol, 2-(2-bromo-2
  • l]heptane-2,3-dicarboxylic acid 4,5-dichloro-2-n-octyl-4-isothiazoline- 3-one, 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one.
  • the preferred non-oxidizing biocide is 2,2-dibromo-3-nitrilopropionamide and is available from ONC.
  • the amount of oxidizing biocide added is from about 0.1 ppm to about 200 ppm, preferably from about 1 ppm to about 100 ppm, more preferably from about 5 to about 50 ppm and most preferably from about 5 ppm to about 20 ppm.
  • Conosion inhibitors can be added when needed to reduce conosion of the metal in the industrial water system.
  • Conosion inhibitors for multi-metal protection are typically triazoles, such as, but not limited to, benzotriazole, halogenated triazoles, nitro-substituted azoles, and other triazoles as listed in United States Patent No. 5,874,026, which is incorporated by reference in its entirety.
  • the prefened triazole is benzotriazole.
  • Triazoles are commercially available from most chemical supply companies.
  • the prefened benzotriazole is Nalco ® 73199, which is available from Ondeo Nalco Company.
  • a conosion inhibitor is used depends upon the industrial water system and the composition of the water contact surfaces in the industrial water system. For example, if all the water contact surfaces in the industrial water system are wood, noble metals, glass, titanium or plastic, then the use of conosion inhibitor in those systems is not indicated. However, when the water contact surfaces are non-titanium metal, such as, but not limited to, stainless steel, carbon steel, galvanized steel, and yellow metals such as copper, admiralty and brass, then the use of a conosion inhibitor is prefened.
  • the amount of conosion inhibitor added to the water of the industrial water system depends upon what type of industrial water system is being cleaned and disinfected. If the method of the instant claimed invention is applied to a cooling water system, then the amount of conosion inhibitor added is from about 1 ppm to about 2000 ppm, preferably from about 10 ppm to about 1000 ppm and most preferably from about 50 ppm to about 600 ppm.
  • the conosion inhibitor may be added before, after or during the addition of the Compound and the acid.
  • the conosion inhibitor is preferably added prior to the addition of acid.
  • the conosion inhibitor can be added immediately before the acid and Compound are added. However, it is prefened that the conosion inhibitor be added sufficiently in advance of the addition of acid that the conosion inhibitor can circulate throughout the system. Thus it is prefened that the conosion inhibitor be added from about 1 hour to about 24 hours prior to addition of the Compound and acid.
  • conosion inhibitor could also be preformulated with other ingredients being added to the water.
  • conosion inhibitor can be formulated with acid to create an "inhibited acid”.
  • Dispersants are added when needed to keep particulate matter present in the water of an industrial water system dispersed, so that it does not agglomerate and cause fouling during the cleaning and disinfecting process.
  • Dispersants are typically low molecular weight anionic polymers, with "low” referring to a weight average molecular weight of from about 500 to about 20,000. These polymers are typically, but not limited to acrylic acid, polymaleic acid, copolymers of acrylic acid with sulfonated monomers and alkyl esters thereof. These polymers can include terpolymers of acrylic acid, acrylamide and sulfonated monomers. These polymers can also include quad- polymers consisting of acrylic acid and three other monomers.
  • Dispersant polymers are commercially available from most chemical supply companies.
  • the prefened dispersant polymer is a High Stress Polymer such as High Stress Polymer PR 4832 which is available from Ondeo Nalco Company. Whether a dispersant is used depends upon the industrial water system, the deposits present in the system and the foulants present in the water and the composition of the water contact surfaces in the industrial water system.
  • the amount of dispersant added to the water of the industrial water system depends upon what type of industrial water system is being cleaned and disinfected. If the method of the instant claimed invention is applied to a cooling water system then the amount of dispersant added is from about 1 ppm to about 500 ppm, preferably from about 5 ppm to about 200 ppm and most preferably from about 10 ppm to about 100 ppm.
  • the dispersant may be added before, after or during the addition of the Compound and the acid.
  • the dispersant could also be preformulated with other ingredients being added to the water.
  • One or more surfactants may be added when and where needed to enhance the cleaning and disinfection process.
  • Surfactants useful in industrial water systems include, but are not limited to, ethylene oxide propylene oxide copolymers, linear alkylbenzene sulfonates ("LAS"), ethoxylated phosphate esters, and alkyl polyglycosides, and other surfactants described in United States Patent No. 6,139,830, U.S. Patent No. 5,670,055 and U.S. Patent No. 6,080,323, which are all incorporated by reference. Surfactants are commercially available from most chemical supply companies.
  • LAS linear alkylbenzene sulfonates
  • the prefened surfactants are ethylene oxide propylene oxide copolymers and alkyl polyglycosides. These surfactants CL-103, CL-361, CL-362, Nalco®73550, and Nalco®7348 are available from ONC.
  • Whether a surfactant is used depends upon the industrial water system, the deposit or foulant, and the composition of the water contact surfaces in the industrial water system.
  • the amount of surfactant added to the water of the industrial water system depends upon what type of industrial water system is being cleaned and disinfected. If the method of the instant claimed invention is applied to a cooling water system, then the amount of surfactant added is from about 0.1 ppm to about 1000 ppm, preferably from about 1 ppm to about 500 ppm and most preferably from about 5 ppm to about 100 ppm.
  • Surfactant could be added at any time during the method of simultaneous cleaning and disinfection, but surfactant would preferably be added after chlorine dioxide generation has started ⁇ in order to reduce any potential aerosolization of viable microbial foulants ⁇ .
  • One or more reducing agents may be added when and where needed to react with oxidants present in order to prepare the water for discharge in compliance with state and local environmental regulations.
  • Reducing agents suitable for use in the method of the instant claimed invention include, but are not limited to, sodium thiosulfate, sodium bisulfite, sodium metabisulfite and sodium sulfite.
  • Reducing agents such as these are commercially available from most chemical supply companies.
  • the prefened reducing agent is sodium bisulfite which is available from Ondeo Nalco Company.
  • Whether a reducing agent is used depends upon the industrial water system and the amount of oxidants present therein.
  • the amount of reducing agent added to the water of the industrial water system depends upon what type of industrial water system is being cleaned and disinfected. If the method of the instant claimed invention is applied to a cooling water system, then the amount of reducing agent added is equimolar to the amount of oxidant present. Another way of determining the amount of reducing agent that is required is to add reducing agent until there is no residual halogen present.
  • the reducing agent is typically added at the conclusion of the cleaning and disinfection process just before the water is to be discharged or may be added to the discharge pipe or reservoir.
  • a pH adjusting chemical may be added when needed to adjust the pH of the water being discharged from the industrial water system.
  • Typical pH adjusting chemicals include, but are not limited to, NaOH (aka “caustic"), KOH, Ca(OH) 2 , Na 2 CO 3 and K 2 CO 3 .
  • the prefened pH adjusting chemical is caustic, specifically a 50% solution of NaOH in water.
  • Caustic is commercially available from most chemical supply companies.
  • the amount of pH adjusting chemical added to the water of the industrial water system depends upon what type of industrial water system is being cleaned and disinfected, what the pH of the water typically is and what are the pH requirements for the water being discharged from the industrial water system.
  • the amount of pH adjusting chemical added is that required to achieve a pH from about 2 to about 8, preferably from about 3 to about 7 and most preferably from about 4 to about 6.
  • the pH adjusting chemical is typically added at the conclusion of the cleaning and disinfection process just before the water is to be discharged or it may be added to the discharge pipe or reservoir.
  • a prefened formulation would include conosion inhibitor, dispersant and surfactant blended together in a single product.
  • the water containing the cleaning and disinfection chemicals and residual material removed from the water is drained from the industrial water system. Then, the system can be refilled with water and returned to service right away or not, depending on the needs of the system operators. It is of course possible to fill the tower with fresh water and conduct the method of the instant claimed invention again, in order to clean heavily contaminated industrial water systems.
  • any of the following actions can take place at the conclusion of the method. 1) fill the cooling tower using fresh make-up water, and begin dosing a "normal" treatment program of inhibitors and biocides;
  • the advantages of the first and second aspects of the instant claimed invention include the fact that this cleaning and disinfection procedure removes deposits from virtually all wetable surfaces, and simultaneously disinfects bulk water and all wetable surfaces, and some surfaces not continually in contact with the water, by in-situ generation of ClO 2 .
  • the method of the instant claimed invention is designed to minimize conosion while cleaning and disinfection are taking place, can be completed in less than eight hours, effectively removes microbial deposits and significantly extends the period for microbial re-colonization. The procedure works well to clean heavily fouled industrial water systems.
  • the third aspect of the instant claimed invention is an on-line method of simultaneously cleaning and disinfecting an industrial water system comprising the steps of : a) providing an industrial water system; wherein said industrial water system is selected from the group consisting of cooling water systems and boiler water systems; b) optionally reducing the cycles of said industrial water system to single cycles and halting the feeding of the routine water maintenance chemicals to the water of the industrial water system; c) adding a Compound selected from the group consisting of the alkali salts of chlorite and chlorate, or a mixture thereof, and optionally adding a conosion inhibitor and optionally adding a dispersant to the water of said industrial water system; wherein enough Compound is added to reach a concentration of from about 1 ppm to about 1000 ppm; wherein if a conosion inhibitor is added enough conosion inhibitor is added to reach a concentration of from about 50 ppm to about 500 ppm and wherein if a dispersant is added enough dispersant is added to reach a concentration of from about 1
  • the third aspect of the instant claimed invention is a method applicable to cooling water systems and boiler water systems.
  • These industrial water systems consist of evaporative cooling towers, open re-circulating, closed and once-through cooling water systems; boilers and boiler water systems and industrial water systems including cooling water equipment and boiler equipment.
  • the Compound is selected from the alkali salts of chlorite and chlorate and mixtures thereof.
  • These alkali salts include sodium chlorite, potassium chlorite, sodium chlorate and potassium chlorate.
  • the prefened alkali salts are sodium chlorite and sodium chlorate.
  • the most prefened alkali salt is sodium chlorite.
  • the alkali salts of chlorite and chlorate are commodity chemicals that can be obtained from most chemical supply companies.
  • Sodium chlorite can be obtained either at its normal pH or in its colloquially refened to "stabilized form" at an elevated pH.
  • the prefened sodium chlorite is a 25% solution of sodium chlorite in water. This material is available as HYG-25 from ONC.
  • Sodium chlorate is a commodity chemical that can be obtained from most chemical supply companies.
  • the prefened sodium chlorate is from about a 20 to about a 50 Wt/Wt % solution of sodium chlorate in water. This prefened sodium chlorate is available from Eka Chemicals, Inc., 1775 West Oak Commons Court, Marietta, GA 30062-2254 USA, telephone number 1-770-578-0858.
  • Potassium chlorite and potassium chlorate are both available from most chemical supply companies.
  • the amount of sodium chlorite or potassium chlorite added to the water of the industrial water system depends upon what type of industrial water system is being cleaned and disinfected. If the method of the instant claimed invention is applied to a cooling water system, then the amount of sodium chlorite or potassium chlorite added is from about 1 ppm to about 1000 ppm, preferably from about 10 ppm to about 500 ppm, most preferably from about 50 ppm to about 250 ppm and most highly preferably about 100 ppm.
  • the ratio of chlorite to chlorate is from about 1:99 to about 99:1, preferably from about 10:90 to about 90:10, and most preferably about 50:50.
  • the total amount of both chlorite and chlorate together is the same as that for either chlorite or chlorate used separately.
  • the conosion inhibitor optionally used in the third aspect of the instant claimed invention is selected from the group consisting of benzotriazole, halogenated triazoles, nitro-substituted azole, and the triazoles listed in United States Patent No. 5,874,026, which is incorporated by reference in its entirety.
  • the prefened triazole is benzotriazole.
  • Benzotriazole is available from ONC as Nalco 73199.
  • the amount of azole added is that amount sufficient to reach a concentration of about 50 to about 500 ppm in the water of the industrial water system.
  • the prefened concentration of azole is about 100 ppm in the water of the industrial water system.
  • the dispersant optionally used in the third aspect of the instant claimed invention is selected from the group consisting of, but not limited to, High Stress Polymer (as previously described), acrylic acid, polymaleic acid, copolymers of acrylic acid with sulfonated monomers and alkyl esters thereof.
  • These polymeric dispersants can include terpolymers of acrylic acid, acrylamide and sulfonated monomers.
  • These polymeric dispersants can also include quad-polymers consisting of acrylic acid and three other monomers.
  • the prefened dispersant is a terpolymer comprising from about 30-70 mol % acrylic acid, from about 10-30 mol % Acrylamide and from about 20-40 mol % aminomethylsulfonic acid.
  • a terpolymer with such composition is available from ONC as High Stress Polymer PR 4382.
  • the amount of dispersant added is that amount sufficient to reach a concentration of from about 1 ppm to about 500ppm.
  • the prefened amount of dispersant is about 100 ppm.
  • the acid used in the third aspect of the instant claimed invention is either a mineral acid or an organic acid selected from the group consisting of hydrochloric acid, sulfuric acid, amido sulfuric acid (98%), nitric acid, phosphoric acid, hydrofluoric acid and sulfamic acid; and said organic acids are selected from the group consisting of citric acid and its salts, formic acid, acetic acid, peracids including peracetic acid, peroxyacetic acid and peroxyformic acid, glycolic acid (hydroxyacetic acid), oxalic acid, propionic acid, lactic acid (hydroxypropionic acid) and butyric acid.
  • the preferred acid is glycolic acid, which is available as Nalco R3076 from ONC.
  • the amount of acid added is that amount sufficient to lower the pH of the water to about 4.0 and subsequently to maintain the pH at about 4.0.
  • the chelating agent useful in the third aspect of the instant claimed invention is selected from the group consisting of sodium hexametaphosphate, sodium polyphosphate, phosphonates, and polycarboxylates (homopolymers and copolymers).
  • the prefened chelating agent is sodium hexametaphosphate. It is available as Glassy Calgon from ONC. Sufficient chelating agent is added such that the concentration of the chelating agent at from about 10 ppm to about 500 ppm in the water of the industrial water system.
  • the biocide useful in the third aspect of the instant claimed invention can be an oxidizing biocide or a non-oxidizing biocide.
  • Oxidizing biocides are selected from the group consisting of chlorine bleach, chlorine, bromine and materials capable of releasing chlorine and bromine.
  • the prefened oxidizing biocide is chlorine bleach..
  • Non-oxidizing biocides are selected from the group consisting of glutaraldehyde, isothiazolin, 2,2-dibromo-3-nitrilopropionamide, 2-bromo-2-nitropropane-l,3 diol, 1- bromo-l-(bromomethyl)-l,3-propanedicarbonitrile, tetrachloroisophthalonitrile, alkyldimethylbenzylammonium chloride, dimethyl dialkyl ammonium chloride, didecyl dimethyl ammonium chloride, poly(oxyethylene(dimethyliminio)ethylene(dimethyliminio)ethylene dichloride, methylene bisthiocyanate, 2-decylthioethanamine, tetrakishydroxymethyl phosphonium sulfate, dithiocarbamate, cyanodithioimidocarbonate, 2-methyl-5-nitroimidazole-l- ethanol, 2-(2-bromo-2-nitro
  • the prefened non-oxidizing biocide is 2,2-dibromo-3-nitrilopropionamide, which is available as Nalco N7649 from ONC.
  • the amount of biocide added is that amount sufficient to have a concentration of from about 1 ppm to about 20 ppm in the water of the industrial water system.
  • the on-line method of cleaning and disinfection of industrial water systems allows for cleaning of inorganic and organic deposits initially through lowered pH, using an acid for a short period of time and subsequently for a prolonged period of time using a chelating agent at a near neutral pH.
  • the disinfection takes place initially through the in-situ generation of chlorine dioxide when the pH is about 4.0, followed by addition of a chelating agent and a biocide when the pH is near neutral.
  • the fourth aspect of the instant claimed invention is: an on-line method of simultaneously cleaning and disinfecting an industrial water system comprising the steps of : a) providing an industrial water system; wherein said industrial water system is selected from the group consisting of cooling water systems and boiler water systems; b) optionally reducing the cycles of said industrial water system to single cycles and halting the feeding of the routine water maintenance chemicals to the water of the industrial water system.
  • a chelating agent added to the water of the industrial water system, wherein enough chelating agent is added to maintain the concentration of the chelating agent at from about 10 ppm to about 500 ppm in the water of the industrial water system; wherein said chelating agent is added either before or after the optional next step of maintaining the pH; d) optionally maintaining the pH of the water in the industrial water system from about 5.5 to about 11 by either adding caustic or stopping the addition of acid or by a combination of both of these methods; e) adding a biocide to the water of the industrial water system; wherein if the chelating agent is added after the optional step of maintaining the pH, then the chelating agent and the biocide from step e) may be added simultaneously to the water or the chelating agent may be added first followed by the biocide or the biocide may be added first, followed by the chelating agent; wherein the amount of biocide added is that amount sufficient to have a concentration of from about 1 ppm to about 500 ppm in
  • the chelating agent useful in the fourth aspect of the instant claimed invention is selected from the group consisting of sodium hexametaphosphate, sodium polyphosphate, phosphonates, and polycarboxylates (homopolymers and copolymers).
  • the prefened chelating agent is sodium hexametaphosphate. It is available as Glassy Calgon from ONC. Sufficient chelating agent is added such that the concentration of the chelating agent at from about 10 ppm to about 500 ppm in the water of the industrial water system.
  • the biocide useful in the fourth aspect of the instant claimed invention can be an oxidizing biocide or a non-oxidizing biocide.
  • Oxidizing biocides are selected from the group consisting of chlorine bleach, chlorine, bromine and materials capable of releasing chlorine and bromine.
  • the prefened oxidizing biocide is chlorine bleach.
  • Non-oxidizing biocides are selected from the group consisting of glutaraldehyde, isothiazolin, 2,2-dibromo-3-nitrilopropionamide, 2-bromo-2- nitropropane- 1 ,3 diol, 1 -bromo- 1 -(bromomethyl)- 1 ,3 -propanedicarbonitrile, tetrachloroisophthalonitrile, alkyldimethylbenzylammonium chloride, dimethyl dialkyl ammonium chloride, didecyl dimethyl ammonium chloride, poly(oxyethylene(dimethyliminio)ethylene(dimethyliminio)ethylene dichloride, methylene bisthiocyanate, 2-decylthioethanamine, tetra
  • the prefened non-oxidizing biocide is 2,2-dibromo-3-nitrilopropionamide, which is available as Nalco N7649 from ONC.
  • the amount of biocide added is that amount sufficient to have a concentration of from about 1 ppm to about 500 ppm in the water of the industrial water system.
  • a plastic Pilot Cooling Tower with titanium metal heat exchangers and a plastic sump is chosen as a test site for the method of the second aspect of the instant claimed invention.
  • the Pilot Cooling Tower is in almost continuous use for over one year so there is severe contamination present.
  • the contamination is believed to be both inorganic scale as well as microbiological sessile populations.
  • the cooling system heat load is removed.
  • the cooling system fans are turned-off and the blowdown valve is closed.
  • the addition of water treatment program chemicals are discontinued, such that the water circulating through the Pilot Cooling Tower has only residual water treatment chemicals present.
  • Pilot Cooling Tower water recirculation remains on.
  • Benzotriazole and the dispersant which is High Stress Polymer PR 4832 from ONC are added to the water of the Pilot Cooling Tower.
  • Enough benzotriazole is added to achieve a concentration of about 100 ppm.
  • Enough High Stress Polymer is added to achieve a concentration of about 100 ppm.
  • NaClO 2 sodium chlorite
  • Inhibited hydrochloric acid is then added to the water.
  • Sufficient hydrochloric acid is added such that the pH of the water is from about 2.0 to about 3.0, preferably about 2.5.
  • the water is circulated for 6 hours while continuing to add whatever acid is required in order to maintain a pH of from about 2.0 to about 2.5.
  • samples are periodically collected and monitored for chlorine dioxide using standard analytical technique to determine chlorine dioxide ⁇ such as the diethyl- p-phenylene diamine test ("the DPD test”) for free residual chlorine dioxide, expressed "as chlorine" ⁇ as well as determining the level of hardness present by complexometric titration.
  • chlorine dioxide concentrations are found to be in the range of from about 0.5 to about 1.0 ppm, expressed as free chlorine.
  • Hardness values increase from 600 to 2000 ppm over a 5 hour period. After 5 hours, the hardness value increases are minimal and acid addition is stopped. The system water is recirculated for one additional hour. The system is drained. The system is flushed with fresh makeup water and drained a second time.
  • Example 2 This is an example of the third aspect of the instant claimed invention.
  • a plastic Pilot Cooling Tower with titanium metal heat exchangers and a plastic sump is chosen as a test site for the method of the third aspect of the instant claimed invention.
  • the Pilot Cooling Tower is in almost continuous use so there is severe contamination present.
  • the contamination is believed to be both inorganic scale as well as microbiological sessile populations.
  • the cooling system water is blown-down to reduce system water to single cycle.
  • the heat load and the cooling system fans is maintained in operation.
  • the addition of water treatment program chemicals is discontinued, such that the water circulating through the Pilot Cooling Tower has only residual water treatment chemicals present.
  • Pilot Cooling Tower water re-circulation remains on. Benzotriazole and the dispersant, which is High Stress Polymer PR 4832 from ONC are added to the water of the Pilot Cooling Tower.
  • Enough benzotriazole is added to achieve a concentration of about 100 ppm.
  • Enough High Stress Polymer is added to achieve a concentration of about 100 ppm.
  • Sufficient sodium chlorite (NaClO 2 ), taken from the chemical stockroom, is added to the system water such that its concentration in the water is 100 ppm. The sodium chlorite is circulated in the system for 30 minutes.
  • Glycolic acid is then added to the water.
  • Sufficient glycolic acid is added such that the pH of the water is from about 3.5 to about 5.5, preferably about 4.0.
  • the water is circulated for about 1.0 to about 4.0 hours, preferably about 2.0, while continuing to add whatever acid is required in order to maintain a pH of from about 4.0 to about 4.25.
  • samples are periodically collected and monitored for chlorine dioxide using standard analytical technique to determine chlorine dioxide ⁇ such as the diethyl-p-phenylene diamine test ("the DPD test”) for free residual chlorine dioxide, expressed "as chlorine" ⁇ as well as determining the level of hardness present by complexometric titration.
  • chlorine dioxide concentrations are found to be in the range of from about 0.5 to about 1.0 ppm, expressed as free chlorine. Hardness values increase from 400 to 1600 ppm over a 2 hour period.
  • the acid feed is stopped and the system water pH is allowed to rise due to the increasing alkalinity within the system. A rapid rise in the pH is also achieved by the addition of enough caustic solution to bring the pH to about 5.0 to 6.5, preferably 5.5.
  • the system water pH is maintained at 5.5 with intermittent addition of glycolic acid, as needed.
  • the system water blow-down was maintained per normal operational program and loss of chemical (sodium hexametaphosphate and 2,2-dibromo-3- nitrilopropionamide) following blow down was replenished by slug doses of the chemicals.
  • the system water is recirculated for a period of about 48 hours.
  • the total hardness levels are monitored periodically and when hardness level increases are minimal, the acid and biocide feed is stopped and the cleaning process is deemed completed.
  • the system water is blown down to single cycles, and the routine water treatment program is reinstated.
  • the industrial water system is returned to normal service.

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Abstract

L'invention concerne des procédés en ligne ou hors ligne de nettoyage et de désinfection simultanés d'un système d'approvisionnement en eau industrielle. Le procédé consiste à ajouter à l'eau du système d'approvisionnement un composé sélectionné dans le groupe constitué par des sels alcalins de chlorite et de chlorate et leurs mélanges, et un acide; puis à laisser l'eau du système d'approvisionnement circuler pendant plusieurs heures. La réaction des sels alcalins de chlorite et de chlorate et de l'acide produit un dioxyde de chlore, in situ, dans l'eau du système d'approvisionnement. Le dioxyde de chlore tue les micro-organismes et l'acide agit pour éliminer les dépôts présents sur les surfaces de l'installation en contact avec l'eau. Un procédé de substitution consiste à utiliser un agent de chélation et un biocide. D'autres réactifs de nettoyage et de désinfection éventuels pouvant être ajoutés, si besoin est, comprennent des inhibiteurs de corrosion, des agents de chélation, des biocides, des tensioactifs et des réducteurs. Les procédés de nettoyage et de désinfection de l'invention fonctionnent dans divers systèmes d'approvisionnement en eau industrielle, dont des systèmes d'alimentation en eau de refroidissement ou en eau de chaudière.
EP03719966A 2002-04-30 2003-04-29 Procede de nettoyage et de desinfection simultanes de systemes d'approvisionnement en eau industrielle Withdrawn EP1499457A4 (fr)

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US135317 1987-12-21
US409220 1989-09-19
US10/135,317 US8668779B2 (en) 2002-04-30 2002-04-30 Method of simultaneously cleaning and disinfecting industrial water systems
US10/409,220 US6840251B2 (en) 2002-04-30 2003-04-08 Methods of simultaneously cleaning and disinfecting industrial water systems
PCT/US2003/013219 WO2003092919A1 (fr) 2002-04-30 2003-04-29 Procede de nettoyage et de desinfection simultanes de systemes d'approvisionnement en eau industrielle

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MXPA04010730A (es) 2005-03-07
CA2484029A1 (fr) 2003-11-13
NZ536168A (en) 2007-11-30
WO2003092919A1 (fr) 2003-11-13
BR0309652A (pt) 2005-03-01
EP1499457A4 (fr) 2005-12-28
AU2003223762A1 (en) 2003-11-17
AU2003223762B2 (en) 2008-12-04

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