Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
  • B24C1/00—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods
  • B24C1/003—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods using material which dissolves or changes phase after the treatment, e.g. ice, CO2
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
  • B24C11/00—Selection of abrasive materials or additives for abrasive blasts
  • B24C11/005—Selection of abrasive materials or additives for abrasive blasts of additives, e.g. anti-corrosive or disinfecting agents in solid, liquid or gaseous form

Definitions

• Dry ice is generally used for many applications, like cooling and chilling purposes in the food and beverage industries.
• One of the latest uses is the use of dry ice in blasting applications. Dry ice blasting is similar to sandblasting, high- pressure water blasting, or steam blasting. Dry ice blasting systems may project small rice size pellets of dry ice at a temperature of about -78° C out of a jet nozzle or applicator together with compressed air onto the surface of a target material.
• the low dry ice temperature causes contaminants on the target material surface to shrink and loose adhesion to the target material.
• the warmer sub surface of the target material causes the dry ice to sublime into carbon dioxide gas which has about 800 times greater volume than the solid dry ice.
• the carbon dioxide expands behind the contaminant speeding up contaminant removal from the surface. The contaminant then typically falls to the ground, or into some receptacle. Because the dry ice evaporates, only the contaminant is left for disposal.
• Embodiments of the invention generally provide for dry ice blasting using dry ice pellets having additives.
• One embodiment of the invention provides a method for treating a surface of a target item by providing pellets which include solid carbon dioxide and one or more additives, providing a stream of pressurized gas, combining the pellets and the pressurized gas to accelerate the pellets, and exposing the surface of the target item to the accelerated pellets.
• Another embodiment of the invention provides a method for treating a surface of a target item by providing solid carbon dioxide pellets, providing a stream of pressurized gas, combining the solid carbon dioxide pellets and the stream of pressurized gas, exposing the surface of the target item to the solid carbon dioxide pellets, and using solid carbon dioxide pellets including one or more additives which are selected from at least one of antimicrobial compounds, disinfectants, detergents, odorants, and combinations thereof.
• Another embodiment of the invention provides pellets for treating surfaces of dry ice blasting target items, including dry ice and one or more additives which are releasable onto the surfaces of the target items.
• the one or more additives are selected to effect at least one of a cleaning function, a sanitizing function, disinfecting function, anti-microbial function, and an olfactory response in a human being.
• Figure 1 is a flow chart of a process for forming a dry ice product containing an additive chemical, according to one embodiment of the invention
• Figure 2 is a schematic illustration of one embodiment for forming extruded pellets of dry ice containing an additive chemical
• Figure 3 is a flow chart of a process for forming a dry ice product containing an additive chemical, according to one embodiment of the invention.
• Figure 4 is a schematic illustration of one embodiment for forming extruded pellets of dry ice containing an additive chemical. Description of Preferred Embodiments
• the term "antimicrobial” refers to a physical or chemical agent capable of causing greater than 90% reduction (1-log order reduction) in the population of bacteria or spores within 10 seconds at 60 0 C.
• the antimicrobial composition used in embodiments of the invention preferably provides greater than a 99% reduction (2-log order reduction), and more preferably greater than a 99.99% (4-log order reduction), and most preferably a 99.999% (5-log order reduction) in such a population preferably within 60 seconds at 60 0 C, and more preferably within 10 seconds at 60 0 C.
• the term "disinfectant” refers to a physical or chemical agent capable of preventing the growth and reproduction of various microorganisms (such as bacteria, fungi, protozoa, and viruses) on surfaces.
• target item or “target material” refers to equipment, devices, structures, food products, pharmaceutical products, or other items that are in need of surface treatment, sanitation, preserving, or otherwise protecting from or treated for pathogenic microorganisms.
• Dry ice blasting systems project small sized pellets of dry ice out of a jet nozzle or applicator together with compressed air onto the surface of a target material.
• Embodiments described herein incorporate additives to the dry ice pellets used in the dry ice blasting process. Dry ice blasting is well known in the art, and it is believed that any system or apparatus suitable for dry ice blasting is capable of use with embodiments of the invention.
• Dry ice for dry ice blasting may be produced by a controlled expansion of liquid CO 2 into dry ice snow.
• Additives may be added to the liquid CO 2 before the expansion of the liquid CO 2 into dry ice snow, or the additives may be sprayed onto the surfaces of dry ice snow.
• Liquid CO 2 is usually maintained at a temperature of about -60°C at a pressure of 5.11 atm, although embodiments of the invention are not limited to particular temperature or pressure values for maintaining liquid CO 2 .
• the additives used may have freezing points higher, lower, or similar to that of liquid CO 2 .
• Embodiments of the invention can involve mixing one or more additives with a carrier chemical to a final concentration without affecting the freezing point of the carrier chemical.
• a combined solution prepared using a carrier chemical and one or more additives should not have a freezing point higher than that of liquid CO 2 .
• liquid CO 2 combined with a carrier chemical and an additive is fed to an ice press to form dry ice.
• Yet another embodiment of the invention involves feeding liquid CO 2 and a carrier chemical and an additive to an ice press as separate streams, which then combine in the press to generate dry ice "snow" containing the additives.
• the additives may be selected from those listed by the U.S. Food and Drug Administration as being GRAS (Generally Recognized as Safe).
• the additive formulation can essentially contain an alcohol, a terpene, or polyethylene glycol as a carrier chemical in various embodiments.
• An alcohol is any organic compound in which a hydroxyl group (-OH) is bound to a carbon atom of an alkyl or substituted alkyl group.
• the general formula for a simple acyclic alcohol is C n H 2 n+iOH.
• Food grade alcohol, ethanol is a carrier chemical that has a very low freezing point, and can be used in one embodiment of the invention.
• Terpenes are another large group of chemical compounds found in nature that act as effective carrier chemicals with low freezing points.
• One such example is d-limonene, present in orange peel and extracted from the orange skin and provides a lemon-orange scent.
• the freezing point of c/-Limonene is suitable for liquid CO 2 storage conditions, and is also considered to be an effective carrier chemical used in formulation preparations.
• Polyethylene glycol is a non-toxic liquid with low molecular weight, and is a common ingredient of pharmaceuticals.
• additives listed as GRAS may be dissolved directly into the carrier chemical and then mixed with liquid CO 2 or CO 2 in "snow" form before being extruded as pellets or blocks.
• Another embodiment of the invention can involve mixing one or more additives with water, and then adding the solution to the carrier chemical to a final concentration without affecting the freezing point of the carrier chemical.
• GRAS chemical additives may include flavoring agents, flavor enhancers, intensifiers, emulsifiers, binders, fillers, gelling agents, plasticizers, stabilizers, suspending agents, whipping agents, sweetening agents, flavoring agents, colors, enzymes, antioxidants, sequestrants, wetting agents, surfactants, curing and pickling agents, firming agents, fumigants, humectants, leavening agents, processing aids, surface active agents, surface finishing agents, synergists, and texturizers.
• the dry ice product may be manufactured in the form of pellets, flakes, powders, and other possible forms which may be suitable for dry ice blasting. Pellets of dry ice in the range of 1/16 inch to 1 inch may be formed. In addition, powders such as snow, flakes, or chips may be formed by methods known in the art.
• the dry ice product is essentially void of water. What is meant by "essentially void of is that the dry ice product, if it contains water, will comprise less than 5%t>y weight (wt. %) water, according to one embodiment. Typically, the water content will be less than 1 wt. % in a particular embodiment. Moisture levels of up to 5,000 ppm may be helpful in maintaining the desired shape of the product.
• the carrier and additives concentrations in the dry ice may vary widely and may depend upon the end use of the product.
• the additive is incorporated into the carbon dioxide during the dry ice manufacturing process.
• the traditional first step in making dry ice is to manufacture carbon dioxide liquid. This is done by compressing CO 2 gas and removing any excess heat.
• the CO 2 is typically liquefied at pressures ranging from 200-300 pounds per square inch and at a temperature of -2O 0 F to O 0 F, respectively. It is typically stored in a pressure vessel at lower than ambient temperature.
• the liquid pressure is then reduced below the triple point pressure of 69.9 psi by sending it through an expansion valve. This can be done in a single step or, in many cases, by reducing the liquid pressure to 100 psi at a temperature of -50 0 F as a first step to allow easy recovery of the flash gases.
• the liquid CO 2 is expanded inside a dry ice pelletizer to form a mixture of dry ice snow and cold gas.
• the cold gas is vented or recycled and the remaining dry ice snow is then compacted to form high density pellets.
• Dry ice is typically compacted to a density of approximately 90 Ib/ft 3 .
• FIG. 1 is a flow diagram of a process 100 used to create a dry ice product, according to one embodiment of the present invention.
• an additive is combined with liquid carbon dioxide, at step 102.
• the additive is combined with liquid carbon dioxide at a pressure above the triple point of CO 2 (70 psi), allowing the additive to fully dissolve in the liquid CO 2 .
• a carrier chemical may be combined with the additive before the additive is introduced into the liquid CO 2 in step 102.
• the additive and the carrier may be combined with liquid carbon dioxide at a pressure above the triple point of CO 2 (70 psi), allowing the additive and the carrier to fully dissolve in the liquid CO 2 .
• step 104 the mixture of liquid CO 2 , additive, and optional carrier chemical is then allowed to flow into a pelletizer, where the mixture is expanded to generate dry ice snow and compressed into dry ice pellets (step 106).
• FIG. 2 depicts a processing environment used to form dry ice pellets according to process 100.
• Liquid CO 2 is stored in tank 2, typically at pressures of 200 to 300 psi.
• the additive in the vessel 8 is pumped through high pressure dosage pump 9 to mix with the CO 2 in the liquid CO 2 storage tank 2.
• the additive may be co-introduced with a carrier chemical into liquid CO 2 storage tank 2.
• the tank 2 contains any variety of mixing means such as agitators, stirrers, etc. to mix the liquid CO 2 with the additive and/or carrier chemical. If the additive and/or carrier are in gas form, then a sparger may be disposed in the tank 2 through which the additive (and carrier, if present) are introduced.
• the liquid carbon dioxide and additive from storage tank 2 are then passed via line 32 directly to a dry ice pelletizer 34.
• Dry ice pelletizers are well known in the art, and it is believed that any dry ice pelletizer is capable of use with this embodiment.
• the liquid CO 2 is expanded to a pressure (e.g., below 70 psi) allowing the liquid to form a mixture of gas and dry ice snow.
• the dry ice snow is then extruded into pellets, typically ranging from 1/16 inch to 1 inch in diameter.
• FIG 3 is a flow diagram of a process 200 used to create a dry ice product, according to another embodiment of the present invention.
• liquid CO 2 is flowed to a pelletizer at a pressure above the triple point of CO 2 (70 psi) (step 202).
• step 204 the liquid CO 2 is expanded in the pelletizer to generate dry ice snow.
• step 206 an additive is flowed to the pelletizer and sprayed onto the dry ice snow, which is then compressed into dry ice pellets (step 208).
• a carrier chemical may be combined with the additive before the additive is introduced into the pelletizer in step 206.
• Figure 4 depicts a processing environment used to form dry ice pellets according to process 200.
• the additive from a vessel 8 is pumped through high pressure dosage pump 9 and introduced into dry ice pelletizer 34 via a nozzle 36.
• the additive may be co-introduced with a carrier chemical via a nozzle 36 into dry ice pelletizer 34.
• High pressure dosage pump 9 may be connected to the pelletizer 34 in a manner such that when the piston of the pelletizer 34 is retracted a measured quantity of additive is distributed on the dry ice snow formed in the pelletizer 34. Additive is thus adsorbed to the dry ice snow, and as the piston is extended, the dry ice snow with adsorbed additive is pressed into pellets of dry ice and additive.
• the pellitizer 34 may produce 100 kg/hour pellets.
• the high pressure dosage pump may be set to deliver an additive flow rate of between about 1 mL/min and between about 10 ml/min.
• Figure 4 depicts only one additive source 8, high pressure dosage pump 9, and nozzle 36, it is contemplated that any number of additive sources, high pressure dosage pumps, and nozzles may be used to separately introduce a plurality of additives to the pelletizer. In one embodiment, any number of between two and ten additive sources, high pressure dosage pumps, and nozzles are provided.
• the additive may be sprayed onto the surface of ready made dry ice snow, pellets or blocks.
• the additive containing dry ice pellets embodied herein may be used in dry ice blasting systems. Such dry ice blasting systems are well known in the art, and it is believed that the additive containing dry ice may be used with any system or apparatus suitable for dry ice blasting.
• Typical dry ice blasting systems include dry ice pellet hoppers, air or other gas sources, hoses, and nozzles. Dry ice pellets may be accelerated by compressed air and passed through the hoses and nozzles, striking the target item at high velocities. A compressed air supply of about 80 psi may be used in this process. Both single-hose and dual hose systems may be used.
• Dual-hose systems flow compressed gas (such as air) through one hose to a blast applicator (or nozzle), and the Venturi effect accelerates the dry ice from a dry ice hopper through a second hose and to the blast applicator.
• the dry ice particles and compressed gas are then blasted together.
• single-hose systems there is one hose leading from the hopper to the applicator and a feeder system that feeds the dry ice particles and compressed gas into the hose and to the applicator.
• the dry ice pellets may crack and additive may be released to the target item.
• the additive may be released to the target item upon sublimation of the dry ice pellet, leaving additive and any potential carrier chemical.
• the additive may be an antimicrobial compound. Upon sublimation or cracking of the dry ice, the antimicrobial compound is released to provide an improved cleaning effect of target item. If the target item to be dry ice blasted concerns food industry, both the carrier chemical and the additive may be GRAS qualified.
• MIRENAT-N manufactured by Vedeqsa Lamirsa Group based in Barcelona, Spain and distributed in the U.S. by A & B Ingredients (Fairfield, NJ).
• MIRENAT- N is manufactured from a naturally occurring antimicrobial compound, and its active ingredient is lauric arginate (N-lauroyl-L-Arginine ethyl ester monohydrochloride).
• the formulation available for sale contains about 10% active lauric arginate and 90% food grade propylene glycol. It is possible to substitute ethanol for propylene glycol as the carrier chemical when using MIRENAT-N.
• Advantages of using MIRENAT-N include: minimal modification of original product, low application use dosage, and well known antimicrobial activity.
• MIRENAT-N can be manufactured to be lower than 11% active in ethanol.
• MIRENAT either in propylene glycol, or ethanol, when treated with meat or poultry, can lose its efficacy overtime, due to enzymatic reactions.
• Such problems can be overcome by adding other preservatives or antimicrobials to MIRENAT-N.
• antimicrobial additives used in embodiments of the invention could include natural lactic acid, ascorbic acid, benzoic acid, lactates, gluconates, and lacititol.
• the solubility of the following products manufactured by Purac (Lincolnshire, IL) was tested: potassium gluconate, ammonium lactate, potassium lactate, sodium lactate, sodium lactate powder, and sodium diacetate. Based on solubility testing, all liquid forms of these additives were found to be ethanol soluble.
• Other antimicrobial additives could include parabens, a group of chemicals which are derivatives of phenol. Parabens are widely used as preservatives in the cosmetic and pharmaceutical industries, and are also popular in the meat processing industry.
• Methyl paraben sold by The KIC Group (Vancouver, WA), is also soluble in ethanol and not soluble in water.
• methyl paraben can be a preservative or antimicrobial added in one embodiment of the composition with ethanol as the carrier chemical.
• antimicrobials that are not directly soluble in ethanol but soluble in water can be also be used in embodiments of the invention.
• examples include potassium nitrite and potassium nitrate. These salts can be dissolved in water and further mixed with ethanol.
• the final composition of ethanol can be adjusted such that it does not freeze under liquid CO 2 storage conditions.
• the ethanol composition could be adjusted by starting with an amount of high purity ethanol and diluting the ethanol with water containing antimicrobials, such that a final composition is still compatible with liquid CO 2 temperatures.
• salts of organic acids are preservatives that act by increasing the proton concentration of the cytoplasm of many microbes. Under mild conditions, they are protonated, since they are weak acids. The relative non-polarity of these salts allows the salts to penetrate the cellular membrane of bacteria and other microorganisms. Once inside the cell, these acids dissociate (releasing protons), due to the lower proton concentration of cytoplasm. Microorganisms, to maintain their proton concentration, they must compensate for these acids by discharging protons using ATP synthesis. This in turn disrupts ATP synthesis, and causes the microbes to die.
• the additive may be a disinfectant. Upon sublimation or cracking of the dry ice, the disinfectant is released to improve the disinfecting effects of the dry ice blasting of the target item.
• Suitable disinfectants may be combinations of peroxides, formic acid, performic acid, peroxygen compounds, peracetic acid, perglutaric acid, and perbenzoic acid.
• the additive may be a detergent, or surfactant.
• the detergent or surfactant Upon sublimation or cracking of the dry ice, the detergent or surfactant is released so that the dry ice and detergent simultaneously act on the surface of target item to be cleaned.
• suitable detergents or surfactants are sodium dodecyl sulfate, ammonium lauryl sulfate, sodium laureth sulfate, alkyl benzene sulfonate, soaps, or fatty acid salts, cetyl trimethylammonium bromide, cetyl pyridinium chloride, polyethoxylated tallow amine, benzalkonium chloride, dodecyl betaine, dodecyl dimethylamine oxide, cocamidopropyl betaine, coco ampho glycinate, alkyl poly(ethylene oxide), octyl glucoside, decyl maltoside, cetyl alcohol, oleyl alcohol, cocamide monoethanol
• the additive may be an odorant.
• the odorant Upon sublimation or cracking of the dry ice, the odorant is released to neutralize unpleasant odors or to provide scent producing an olfactory response in a human being.
• suitable odorants are 1-methoxy-4-(1-propenyl)benzene (licorice), methoxybenzene (anis seed), 2-methoxy-4-(2-propenyl)phenol (clove oil), (R)-2-(4-methylcyclohex-3-enyl)propane-2-thiol (grapefruit), 2,3-benzopyrrole (jasmine), methyl 2-hydroxybenzoate (oil of wintergreen), 2-ethoxynaphthalene (orange flowers), and 3-hydroxy-4,5-dimethylfuran-2(5H)-one (maple syrup, curry, fenugreek).
• alcohols may also be suitable as odorants, such as cis-3-Hexen-1- ol (fresh cut grass), 2-ethyl-3-hydroxy-pyran-4-one (sugary, cooked fruit), 4-hydroxy-2,5-dimethyl-furan-3-one (strawberry), 5-methyl-2-propan-2-yl- cyclohexan-1-ol (peppermint), and 1-hexanol (herbaceous, woody).
• odorants such as cis-3-Hexen-1- ol (fresh cut grass), 2-ethyl-3-hydroxy-pyran-4-one (sugary, cooked fruit), 4-hydroxy-2,5-dimethyl-furan-3-one (strawberry), 5-methyl-2-propan-2-yl- cyclohexan-1-ol (peppermint), and 1-hexanol (herbaceous, woody).
• aldehydes may also be suitable as odorants, such as benzaldehyde (marzipan, almond), hexanal (green, grassy), cinnamaldehyde (cinnamon), cis-3-hexenal (green tomatoes), (2E)-3,7-dimethylocta-2,6-dienal (lemongrass, lemon oil), furan-2-carbaldehyde (burnt oats), (2Z)-3,7- dimethylocta-2,6-dienal (citrus, lemongrass), and 4-hydroxy-3-methoxy- benzaldehyde (vanilla).
• benzaldehyde marzipan, almond
• hexanal green, grassy
• cinnamaldehyde cinnamon
• cis-3-hexenal green tomatoes
• (2E)-3,7-dimethylocta-2,6-dienal lemongrass, lemon oil
• esters may also be suitable as odorants, such as ethyl acetate (fruity, solvent), ethyl butanoate (fruity), methyl butanoate (apple, fruity) pentyl butanoate (pear, apricot), pentyl pentanoate (apple, pineapple), isoamyl acetate (banana), hexyl acetate (apple, floral, fruity), ethyl hexanoate (sweet, pineapple, fruity), ethyl octanoate (wine, fruity), ethyl decanoate (brandy, fruity), and ethyl 3- methyl-3-phenyl-oxirane-2-carboxylate (strawberry).
• ethyl acetate fruity, solvent
• ethyl butanoate fruity
• pear, apricot pentyl pentanoate
• isoamyl acetate ban
• terpenes may also be suitable as odorants, such as 1 ,7,7- trimethylnorboman-2-one (camphor), 3,7-dimethyloct-6-en-1-ol (rose), 3,7- dimethylocta-1 ,6-dien-3-ol (floral, citrus, coriander), (2E)-3,7-dimethylocta-2,6- dien-1-ol (rose), 3,7,11-trimethyl1 ,6,10-dodecatrien-3-ol (fresh bark), 2-(4-methyl- 1-cyclohex-3-enyl)propan-2-ol (citrus woody), (1S,4R,5R)-4-methyl-1-propan-2- yl-bicyclo[3.1.0]hexan-3-one (juniper, common sage, wormwood), and 5-methyl- 2-propan-2-yl-phenol (thyme-like).
• camphor 3,7-dimethyloct-6-
• the odorant may be d-limonene.
• D-limonene is a terpene which may be extracted from the rind of citrus fruit and is used in food manufacturing as a flavoring, and added to cleaning products such as hand cleansers to give a lemon-orange fragrance. Because d-limonene has a melting point of -95 0 C and dissolves in the liquid CO 2 , it is suitable for dry ice production. Thus, d-limonene may also be used as a carrier chemical. While not bound by any theory of operation, if the c/-limonene is added before or during CO 2 expansion, the d-limonene is believed to be trapped in the structural lattices of the dry ice.
• the odorous chemical may be vanillin. Both methyl-vanillin and ethyl-vanillin may be used. In one embodiment, the vanillin may be co-introduced to the CO2 with a carrier chemical such as ethanol or polyethylene glycol. Natural vanilla extract may also be used. As the dry ice sublimes or cracks vanillin is released from the structural lattices of the dry ice, and a pleasant vanilla scent emanates from the dry ice.
• the odorous chemical may be mint extracts or artificial mint flavoring.
• the mint flavoring may be co-introduced into the liquid CO 2 with a carrier chemical such as ethanol or polyethylene glycol. As the dry ice sublimes or cracks mint flavor is released from the structural lattices of the dry ice, and a pleasant vanilla scent emanates from the dry ice.
• the additive may consist of natural or artificial compounds having cherry odors, strawberry odors, coconut odors, chocolate odors, or any other natural of artificial odors possible.
• carrier chemicals may or may not need to be co-introduced with the additive to the CO 2 , according to different embodiments.
• the additive may be a combination of antimicrobial compounds, disinfectants, detergents, surfactants, and/or odorants.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Agricultural Chemicals And Associated Chemicals (AREA)
• Detergent Compositions (AREA)
• Cleaning In General (AREA)
• Apparatus For Disinfection Or Sterilisation (AREA)
• Carbon And Carbon Compounds (AREA)

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• 2006
  • 2006-10-19 US US11/551,057 patent/US20070178811A1/en not_active Abandoned
• 2007
  • 2007-01-25 WO PCT/IB2007/000178 patent/WO2007088437A2/en not_active Ceased
  • 2007-01-25 EP EP07705469A patent/EP1981686A2/en not_active Withdrawn
  • 2007-01-25 JP JP2008552905A patent/JP4975045B2/ja not_active Expired - Fee Related

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