Abstract:
The invention is directed to a system for cleaning an apparatus like a paper making apparatus. The system sprays a thickened liquid composition that has a soil treating agent, and the system may be used at pressures which do not exceed 100 psi.

Description:
FIELD OF THE INVENTION 
     This invention is directed to a system for cleaning an apparatus. More particularly, the invention is directed to a system for cleaning an apparatus whereby the system comprises a nozzle assembly with the capacity to spray a thickened liquid composition. The thickened liquid composition may comprise a soil treating agent and surfactant and can be used to clean a variety of apparatuses, including paper making machines. 
     BACKGROUND OF THE INVENTION 
     The deposition of contaminants in and on equipment such as boilers, cooling towers, food and beverage equipment, and pulp and paper processing equipment, can be detrimental to the efficiency of the various processes being conducted in the equipment. Moreover, the desired products generated from contaminated equipment typically display properties and characteristics that are inferior to products made in a contaminant-free environment. 
     In the pulp and paper industries, for example, internal and external components of equipment, such as equipment used during the dry-and wet-ends of the paper making process, are subjected to various inorganics as part of the processing steps to convert pulp into paper. During such a process, diluted pulp (i.e., pulp which is about 99% water) is distributed onto fast-moving screens where it begins to take the form of paper. Subsequent to distribution on the screens, water is removed from the pulp via gravity and vacuum pumps strategically placed about the apparatus. The resulting damp paper sheets are then pressed between felt blankets to remove additional moisture. The dried paper then moves from the felt blankets to heated cylinders of the paper making pulping apparatus so that the final paper product does not exceed about 6.0% water. Finally, the resulting final paper product may be subjected to a smoothing step before being rolled and shipped to customers. 
     As can be understood, the paper making process, like many other processes, is complicated. This is true because precursor paper raw materials are typically subjected to harsh environments that comprise many chemical and physical processing steps. Such chemical processing steps are known to generate a fair amount of waste and contaminants, and the apparatuses involved with these steps require cleaning to ensure that superior and contaminant-free product is being generated. 
     Conventional methods for cleaning internal and external portions of equipment, such as those described above, typically employ high volumes of solution and active that dissolve the contaminants associated with the equipment. The solution method, however, has many disadvantages, including the generation of excess environmentally unfriendly waste that typically has to be removed to off-site hazardous waste plants. Other conventional methods for removing contaminants from the internal and external portions of equipment include the use of high pressure water blasting (e.g., blasting at pressures that exceed at least 400 psi). Such a water blasting method, unfortunately, requires the expensive and labor-intensive steps of disconnecting the parts of the equipment prior to cleaning. Moreover, water blasting techniques are not very safe because the chemical solutions employed often splash onto the individuals conducting the high pressure water blasting. 
     In addition to the vast deficiencies of the conventional methods outlined above, such conventional methods require that the cleaning solutions be mixed and/or processed at a job site prior to use. Also, such conventional methods typically use cleaning solutions having about 50% by weight more active than the thickened liquid composition of the present invention. 
     It is of increasing interest to develop a system for cleaning apparatuses. More particularly, it is of increasing interests to develop a system that does not generate excess hazardous waste, can be conducted at low pressures and is safe to use. This invention, therefore, is directed to a system for cleaning an apparatus that does not generate excess hazardous waste, is conducted at pressures under about 100 psi is safe, and does not require processing of a chemical solution before use at job sites. 
     BACKGROUND REFERENCES 
     Efforts have been disclosed for cleaning in U.S. Pat. Nos. 5,977,050 and 5,705,470 cleaning gels that are dispensed from a hand held trigger or aerosol spray applicator. 
     Other efforts have been disclosed for inhibiting contaminant deposition in papermaking systems. In U.S. Pat. No. 5,885,419, the deposition of organic contaminants in a paper making system is minimized by adding albumins, globulins and spray-dried animal cells to the pulp, or by spraying deposition prone surfaces of the paper making system with the same. 
     Still additional efforts have been disclosed that convert inorganic materials in Kraft pulping liquor into pulping chemicals. In U.S. Pat. No. 5,034,094, pulp recovery is increased by separating organics and inorganics wherein the former is recycled to a process loop and the latter is converted into pulping chemicals without the need of a recovery furnace. 
     SUMMARY OF THE INVENTION 
     In a first aspect, the present invention is directed to a system for cleaning apparatus, the system comprising: 
     (i) a thickened liquid composition comprising a viscosity from about 50.0 cps to about 1,000 cps; 
     (ii) a spraying device comprising at least one orifice having a diameter from about 2.0×10 −2  cm at about 6.5×10 −1  cm; and 
     (iii) a pressure source supplying less than about 100 psi of pressure 
     wherein the thickened liquid composition comprises components that clean soil on the apparatus. 
     In a second aspect the present invention is directed to a kit comprising: 
     (a) a thickened liquid composition comprising a viscosity from about 50.0 cps to about 1,000 cps, the liquid composition comprising components that clean soil on the apparatus; 
     (b) a spraying device comprising at least one orifice having a diameter from about 2.0×10 −2  cm at about 6.5×10 −1  cm; and 
     (c) a pressure source supplying less than about 100 psi of pressure; and 
     (d) instructions to use the liquid composition supplied is and at a pressure that does not exceed about 100 psi. 
     In a third aspect, this invention is directed to a method for cleaning an apparatus with the system described in the first aspect of this invention. 
     Thickened liquid composition, as used herein, is defined to mean a liquid having a viscosity of greater than about 50 cps and less than about 1000 cps (at ambient temperature and taken with a Brookfield Viscometer, spindle No. 2), and soil treating agent is defined to mean a substance that can react with, neutralize and/or dissolve soil. Pressure less than about 100 psi generally means pressures from about 5 psi to about 99.99 psi, and preferably, form about 40 psi to about 80 psi, including all ranges subsumed therein. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which: 
     FIG. 1 represents a type of spray nozzle that may be used in the system of this invention. 
     FIG. 2 is represents a type of spray wand which may be used in the system of this invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     There is no limitation with respect to the type of thickened liquid composition that may be used in this invention as long as the thickened liquid composition can be used to remove a particular soil targeted for disposal. In the present invention, the thickened liquid composition typically has a viscosity of greater than about 50 cps and less than about 1000 cps; and preferably, greater than about 65 cps and less than about 700 cps; and most preferably, greater than about 75 cps and less than about 450 cps, including all ranges subsumed therein. 
     An illustrative example of the type of thickened liquid which may be used in this invention includes one comprising water, surfactant, a thickening agent and a soil treating agent like an acid or a base. 
     The surfactants which may be used in the thickened liquid composition that may be used in this invention include anionic, cationic, nonionic, zwitterionic, and amphoteric surfactants or a mixture thereof. The surfactants are known in the art and commercially available from suppliers like Shell Chemical, Witco Chemical Company, Dow Chemical, BASF and ICI Surfactants. Such surfactants are only limited to the extent that they are capable of being added to the composition for use in the system of this invention. The anionic surfactant which may be used in this invention includes at least one surfactant selected from the group consisting of a carboxylic acid salt, like a sodium and potassium salt of a straight-chain fatty acid, and a sulfonic acid salt, like a linear alkylbenzene sulfonate, and an α-olefin sulfonate, and a sulfuric acid ester salt, like a sulfated polyoxyethylenated straight-chain alcohol, and phosphoric and polyphosphoric acid esters, like a phosphated polyoxyethylenated alcohol or phenol. In such anionic surfactants, the carbon chain lengths may vary but often contain from about 5 to about 50 carbon atoms, and preferably, from about 5 to about 25 carbon atoms. A most preferred anionic surfactant which may be used in this invention includes, however, disodium laurimino dipropionate. 
     The cationic surfactant which may be used in the thickened liquid composition employed in this invention includes at least one surfactant selected from the group consisting of a quarternary ammonium compound with, for example, a halogen as the counterion. Examples include dodecyl trimethyl ammonium bromide, octadecyl trimethylammonium chloride (e.g., Arquad 18/50) and polyoxyethylenated long-chain amines. 
     The nonionic surfactant which may be used in the thickened liquid composition employed in the system of this invention include those selected from the group consisting of a polyoxyalkylenated alkylphenol, polyoxyalkylenated straight chain alcohol, amine oxide, polyoxyalkylenated polyoxyalkylene glycol, polyoxyalkylenated mercaptan, long-chain carboxylic acid ester, alkanolamine condensate and polyoxyalkylenated silicone. When the nonionic surfactants are derived from the condensation of ethyleneoxide with the product resulting from the reaction of propylene oxide and ethylene diamine products, they usually have about 40% to about 80% by weight polyoxyethylene and a molecular weight from about 5,000 to about 11,000. Others include amine oxides (cationic in a composition that is at a pH&gt;7) such as bis-(2-hydroxyethyl) C 12-15  alkoxypropylamine oxide, sold under the name Tomah AO 728. 
     Regarding the zwitterionic surfactant which may be used in the thickened liquid composition employed in this invention, such a surfactant includes at least one surfactant selected from the group consisting of a β-N-alkylaminopropionic acid, N-alkyl-β-iminodipropionic acid, imidazoline carboxylate and betaines, like sulfobetaine. 
     The amphoteric surfactant which may be used in this invention includes those which are classified as derivatives of aliphatic secondary and tertiary amines in which the aliphatic radical can be straight or branched, and wherein one of the aliphatic substituents contains from about 8 to about 18 carbon atoms and one contains an anionic water solubilizing group, like a sulfonate. Illustrative examples of such amphoteric surfactants include sodium lauryl sarconsinate, dodecylamine and isethionate. 
     A more detailed description of the types of surfactants which may be used in this invention may be found in U.S. Pat. No. 5,120,532, the disclosure of which is incorporated herein by reference. 
     The thickening agent which may be used in this invention includes those which can be classified as cross-linked anionic polymers. Illustrative examples of these agents include Carbopol as made commercially available by B.F. Goodrich. Especially preferred thickening agents are Carbopol Aqua-30, as well as Carbopol 934 and 940. In addition to Carbopol, Accusol 820 is another thickening agent, classified as an acrylic acid, which may be used in the thickened liquid compositions of this invention. It is also within the scope of this invention for the surfactants themselves to act as thickening agents within the thickened liquid composition employed in the system of this invention. It is particularly noted that in a most preferred embodiment, the thickened liquid composition of the present invention does not comprise gum in order to ensure excellent cleaning results and minimal residue formation. Gum, as used herein, is defined to include natural and synthetic gums like those typically referred to as alginates, carrageenans, cellulose gels, and synthetic celluloses. 
     Regarding the surfactants, the thickened liquid composition that may be employed in the system of this invention typically comprise from about 0.01% to about 15.0% by weight surfactant, based on total weight of the composition and including all ranges subsumed therein. As to the thickening agent which may be used in the thickened liquid composition of this invention, such an agent typically make up from about 0.0 to about 10.0% by weight of the total weight of the thickened liquid composition, including all range subsumed therein. 
     The soil treating agent which may be used in the thickened liquid composition of the present invention includes acids like citric acid, hydrochloric acid, nitric sulfuric acid, sulfamic acid, glycolic acid, hydroxyethylene diphosphonic acid, and mixtures thereof. The bases which may be used typically include ammonia as well as any of the conventionally available metal hydroxides, like sodium hydroxide. The amount of soil treating agent that may be used in the thickened liquid compositions of the present invention is typically from about 0.1% to about 25.0%, and most preferably, from about 1.0% to about 10.0% by weight soil treating agent, based on total weight of the thickened liquid composition and including all ranges subsumed therein. Thus, it is within the scope of the invention for the thickened liquid composition to have a pH which is acidic, basic, or neutral. 
     It is also within the scope of the present invention to include within the thickened liquid composition of this invention an optional additive selected from the group consisting of a colorant, fragrance, organic solvent, builder hydrotrope, or chelator. 
     The colorant which may be used in this invention includes dyes and pigments. Such dyes and pigments are well known in the art and generally classified as azo- or diazo-colorants. As to the fragrance that may be used in this invention, such a fragrance includes any of the art recognized fragrances which may be used in a cleaning composition. The organic solvent which may be used typically includes ethers such as dipropylene glycol methyl ether which is sold by Dow Chemical under the name Dowanol DPM. 
     Within the thickened liquid composition employable in the present invention, it is not uncommon to use a hydrotrope such as sodium xylene sulfonate, calcium and ammonium xylene sulfonates, p-toluene sulfonate, and the like. The builder which may be used in this invention includes tetra sodium pyrophosphate, as well as sodium tripolyphosphate. The chelator which may be used in this invention includes EDTA and NTA. 
     The amount of each optional additive used in the thickened liquid composition of the present invention is typically from about 0.0 to about 10.0%, and preferably, from about 0.001% to about 8.0%, and most preferably, from about 0.002% to about 6.0% by weight, based on total weight of the thickened liquid composition and including all ranges subsumed therein. 
     Turning to FIG. 1, the components of spray nozzle assembly  10 , not assembled, are shown. The spray nozzle assembly  10  has an exit piece  12  with exit orifice  14  which allows the thickened liquid composition (not shown) of the system of this invention to exit from the spray nozzle assembly  10 . The thickened liquid composition preferably exits at about 0.5 gallons per minute to about 6 gallons per minute, and preferably, from about 1.0 gallons per minute to about 3.0 gallons per minute, including all ranges subsumed therein. Retainer coupling 16 is the housing for orifice plate  18  having an orifice  20 . The diameter of the orifice plate  18  is constant, but the diameter of the orifice  20  may vary, As previously mentioned, the orifice may have a diameter from about 2.0×10 −2  cm to about 6.5×10 −1  cm, and preferably, from about 7×10 −2  cm to about 5.0×10 −1  cm, and most preferably, from about 1.0×10 −1  cm to about 3.0×10 −1  cm, including all ranges subsumed therein. The spray nozzle assembly  10  also comprises a nozzle body  22  which is operayively connected to the retainer coupling  16  and wand  24  (i.e., spraying device) at wand rod  26  as shown in FIG. 2 so that the spray nozzle assembly  10  can be attached thereto. 
     The wand  24  may further comprise a hand grip  28 , a shut off  30 , as wello as a coupling means  32  to attach the wand  24  to a supply tube  34 . Supply tube  34  is associated with pump  36  (e.g., pneumatic pump such as those made available by Aro, Benz Engineering, Inc; Yamada, and the Wilden Corporation) which pumps thickened liquid composition  38  out from container  40  via intake  42  and through wand  24 . 
     When operating the system of the present invention, pump  36  supplies less than about 100 psi of pressure so that thickened liquid composition may be driven through exit orifice  14  to clean a soiled surface, not shown. 
     The following examples are provided to facilltate an understanding of the present invention. The examples are not intended to nlimit the scope of the claims. 
     EXAMPLE 1 
     
       
         
               
               
               
             
               
               
               
             
           
               
                   
                   
               
               
                   
                 Thickened Alkaline Liquid 
                 Weight Percent 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Water 
                 76.995 
               
               
                   
                 Sodium Gluconate granules 
                 1.00 
               
               
                   
                 Liquid sodium hydroxide (50%) 
                 15.00 
               
               
                   
                 Fluorescein Dye 
                 00.005 
               
               
                   
                 Sodium Lauryl Ether Sulfate (60%) 1   
                 3.00 
               
               
                   
                 Tomah AO 728 special 2   
                 4.00 
               
               
                   
                   
               
               
                   
                   1 commercial sold as Steol CS-460, Witcolate SE-5, Sulfotex LMSE they are C12-14 sulfate ethoxylated with 3 moles EO.  
               
               
                   
                   2 bis-(2-hydroxyethyl) C12-15 alkyloxypropylamine oxide  
               
             
          
         
       
     
     EXAMPLE 2 
     
       
         
               
               
               
             
               
               
               
             
           
               
                   
                   
               
               
                   
                 Thickened Acid Liquid 
                 Weight Percent 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Water 
                 75.00 
               
               
                   
                 Sulfamic acid 
                 12.00 
               
               
                   
                 Glycolic acid 
                 3.00 
               
               
                   
                 Monateric 1188M (30%) 
                 3.00 
               
               
                   
                 Arquad 18/50 (50%) 3   
                 4.00 
               
               
                   
                 Sodium xylene sulfonate (45%) 4   
                 3.00 
               
               
                   
                   
               
               
                   
                   3 Arquad 18/50 is octadecyl trimethylammonium chloride (40-52%)  
               
               
                   
                   4 Monateric 1188M is disodium laurimino dipropiionate (30%)  
               
             
          
         
       
     
     EXAMPLE 3 
     
       
         
               
               
               
             
               
               
               
             
           
               
                   
                   
               
               
                   
                 Thickened (Non Caustic) Liquid 
                 Weight Percent 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Water 
                 65.55 
               
               
                   
                 EDTA liquid (40%) 
                 5.00 
               
               
                   
                 Accusol 445 (polyacrylic acid 47-50%) 
                 0.50 
               
               
                   
                 TKPP liquid (30%) 
                 4.00 
               
               
                   
                 Triethanolamine 99% 
                 5.00 
               
               
                   
                 m-pyrol 0.95 
               
               
                   
                 Dowanol DPM 
                 8.00 
               
               
                   
                 Monateric 1188M 
                 2.50 
               
               
                   
                 Neodol 91-6 2.50 
               
               
                   
                 Carbopol Aqua-30 Polymer 5   
                 6.00 
               
               
                   
                   
               
               
                   
                   5 Carbopol Aqua 30 polymer is Aqueous Acrylate polymer emulsion.  
               
             
          
         
       
     
     The thickened liquid composition described in Examples 1-3 were made at room temperature with conventional stirring techniques. The thickened liquid compositions described in the examples all had a viscosity of about 150 cps at room temperature. 
     EXAMPLE 4 
     The soil was a mix of paper fibers, organic and inorganic fillers. 
     Cleaning Procedure: 
     An alkaline thickened liquid composition (as described in Example 1) was sprayed with the want and spray nozzle assembly described herein and powered by a conventional pneumatic pump on to a paper making machine. The spraying was accomplished with a nozzle design as described in the Figures and a thickened liquid composition was applied at 2 gpm at 60 psi delivery pressure. The exit orifice plate used for the trial was 2.8×10 −1  cm. The superior design of this system allowed for a consistent straight stream of thickened liquid composition with a fanning effect at the exit. 
     The thickened liquid composition was sprayed at the beginning from the section where the operator stood and moving towards the far end of the machine being cleaned (about 32 ft. away). The nozzle was oscillated by hand while aiming towards the machine. Thickened liquid composition was sprayed on the surface with two to three passes of the want. The entire surface (about 3,000 sq. ft.) was coated with the thickened liquid composition. 
     Immediately after the whole paper making machine was covered with the thickened liquid composition, the machine was rinsed with cold water sprayed via a conventional hose. An initial rinse with water created the machine foam that enhanced cleaning and removing of soil deposits on the machine. 
     The alkaline thickened liquid composition used was provided ready to use, and the composition had a viscosity of about 140 cps at room temperature. The soil targeted was paper making waste (e.g., paper fibers, organic and inorganic fillers). After about two (2) hours the surface was clean with at least 50.0% by weight less active than the amount of active used in conventional systems.