Apparatus for aerohydrodynamic abrasive cleaning of surfaces, sprayer for the same, and method for aerohydrodynamic abrasive cleaning of surfaces
An apparatus for mechanical spray treatment of materials has a container for preparing an abrasive suspension, the container having a stirring mechanism including a stirrer provided with at least one blade, and a sprayer for spraying the abrasive suspension connected to the container and a compressed gas supply device. The stirrer of the stirring mechanism has a comminuting cutter provided thereon in the bottom part of the container. The method for aerohydrodynamic abrasive cleaning of surfaces includes entraining the abrasive suspension flow in compressed gas to produce aerosol particles and directing the stream of aerosol particles from the sprayer nozzle to a surface. Moreover, after aerosol particles have been formed they are accelerated owing to the sprayer design within the sprayer before they are ejected from the nozzle. The method and device help improve the output, efficiency, and quality of cleaning by improving the uniformity of abrasive material grains used and imparting a high velocity to the suspension spray, expanding the area of effective cleaning, and distributing the aerosol particles therein in an optimal proportion.
Applicant claims priority under 35 U.S.C. §119 of Russian Application No. 2010110986 filed Mar. 23, 2010, the disclosure of which is incorporated by reference.
BACKGROUND OF THE INVENTIONThe group of inventions relates to mechanical spray treatment of materials and can be used in various fields for cleaning any surfaces from organic and inorganic dirt, removing coatings, including coating removal layer by layer; for imparting new adhesive properties to the surface cleaned; combining surface cleaning and passivating; and cleaning many types of items meeting specific requirements to fatigue strength and uncontrollable chemical processes in operation.
The invention can be used in the heavy and metal industries, for example, on the shop floor of metal making plants for removing scale from the surface of semi-manufactured products made of ferrous and nonferrous metals; in blank production shops of mechanical engineering plants for removing oxide films, rust, and so on; cleaning prior to painting; preparing surfaces for welding, brazing, and application of corrosion-resistant and other protective coats; dimensionless grinding preceding final polishing of components; cleaning filled floors; and so on. In power engineering, the oil and gas industries, and aviation, the invention can be used, for example, for cleaning and treating the blades of turbine rotors at cogeneration plants, hydroelectric power plants, nuclear power plants (repairs of gas turbine and steam engines, turbines, and so on), and aircraft engines; cleaning and treating the blades of turbine rotors of oil and gas piping equipment; cleaning pipeline elements and threads; deactivating radioactive contamination, and so on. In transportation and at shipyards, the invention can be used for cleaning railroad cars from dirt, including graffiti, cleaning railroad cars, wheel sets of railroad cars prior to flaw detection procedures; cleaning vehicle bodies and preparing components prior to painting; and cleaning ship hulls, components, and equipment. In housing and utilities, construction, and restoration projects, the invention can be used for cleaning various house front surfaces from atmospheric pollutants, dirt and soil, artificial pollution, and biological destructive agents.
The closest prior art of the claimed apparatus for aerohydrodynamic (AHD) abrasive cleaning of surface, its sprayers, and cleaning method are, respectively, the apparatus, sprayer, and cleaning method disclosed in U.S. Pat. No. 1,740,142 A1 published on Jun. 15, 1992 [1].
The prior art apparatus for aerohydrodynamic abrasive cleaning of surfaces comprises a container for preparing an abrasive suspension, including a stirring mechanism provided with a bladed stirrer, and a sprayer provided with a flaring nozzle to spray the abrasive suspension and connected to the container and a compressed air device.
The prior art apparatus is disadvantageous because of the low quality of cleaning by mixtures containing relatively coarse and/or nonuniform grains.
The prior art sprayer for aerohydrodynamic abrasive cleaning of surfaces comprises a hollow body provided with a flaring nozzle at the outlet, and a compressed air flow channel and a cleaning suspension flow channel, both connected to the body interior.
The prior art sprayer is disadvantageous because of its low cleaning efficiency due to improper matching of the suspension spray velocity, concentration of abrasive particles in the suspension, and the shape and effective area of the cleaning flare.
The prior art method for aerohydrodynamic abrasive cleaning of surfaces comprises injecting compressed gas into the abrasive suspension flow to produce aerosol particles and directing the stream of aerosol particles from the sprayer nozzle at the surface being cleaned.
The prior art method is disadvantageous because of its low cleaning efficiency due to improper matching of the suspension spray velocity, concentration of abrasive particles in the suspension, and the shape and effective area of the cleaning flare.
SUMMARY OF THE INVENTIONThe technical result of the claimed group of inventions consists in increasing output, efficiency, and quality of cleaning by improving the uniformity of abrasive material grains and imparting a high velocity to the suspension spray, enlarging the effective cleaning area, and achieving optimal distribution of abrasive particles and water therein.
The technical result is achieved in an apparatus for aerohydrodynamic abrasive cleaning of surfaces, said apparatus comprising a container for preparing abrasive suspension that has a stirring mechanism including a stirrer having at least one blade, and a sprayer for spraying the abrasive suspension that is connected to said container and to a compressed gas supply device, said stirrer of the stirring mechanism comprising a comminuting cutter provided thereon in the bottom part of the container.
In the specific embodiments of the invention, the stirring mechanism may comprise an air motor connected to the stirrer and to the compressed gas supply device through an air preparation unit that includes a drier and a lubricant supply device.
The suspension preparation container may be provided with a filling funnel having a locking device.
The apparatus may be provided with a washing liquid container connected to the sprayer through an air pump that is connected to the compressed air supply device through the air preparation unit including a drier and a lubricant supply device.
The apparatus units may be interconnected by hoses provided with valves, the hoses connected to the sprayer having pressure gauges.
The grain non-uniformity problem has been resolved by providing the apparatus with a comminuting cutter, a structural element that makes the mass uniform and suitable for producing an AHD mixture and helps grind larger grains to a particle size of 100 μm to 300 μm that are more effective in cleaning a larger area in square meters per hour.
The object of this invention is also achieved by the specific design of a sprayer for aerohydrodynamic cleaning of surfaces that contains a hollow body provided with a nozzle at the outlet thereof, a compressed air flow channel and a cleaning suspension flow channel, both connected to the body interior, the compressed air flow channel being connected to the cylindrical interior of the body at the side opposite to the nozzle, the sprayer being provided with an atomizer in the shape of T pipe placed within the body interior, the crosspiece of the T pipe extending along the body axis and the vertical leg thereof being connected to the cleaning suspension flow channel; the nozzle having a tapering part and a cylindrical part at the outlet thereof, and the outlet aperture of the atomizer being positioned at a distance from the inlet of the cylindrical part of the nozzle to provide a zone for accelerating the aerosol particles of the cleaning suspension.
The object of the invention is also achieved in a method for aerohydrodynamic abrasive cleaning of surfaces comprising injecting compressed air into the abrasive suspension flow to produce aerosol particles and directing the stream of aerosol particles from the sprayer nozzle at the surface, the aerosol particles produced as above being accelerated within the sprayer before they are ejected from the nozzle.
It is preferred to use a nozzle having a part that does not flare at the outlet thereof.
Furthermore, the abrasive suspension used for the purposes of this invention contains solid particles of loam and silica in water in the following proportions of solids, in mass %:
loam 25 to 90
silica 10 to 75
It is preferred for loam and silica solids to have a size ranging from 100 μm to 1.8 mm.
The idea of the invention is described below with reference to the drawings wherein;
The apparatus for aerohydrodynamic abrasive cleaning of surfaces (see:
The stirring mechanism comprises a stirrer 4 and an air motor 5 associated therewith and connected to a compressed gas supply device 3 through an air preparation unit 6 that includes a drier 7 and a lubricant supply device 8. Stirrer 4 is provided with blades 9 and a comminuting cutter 10 provided thereon in the bottom part of container 1.
Stirring container 1 is provided with a filling funnel 11 having a locking device 12.
The apparatus has a washing liquid container 13 connected to sprayer 2 through an air pump 14 connected to compressed air supply device 3 through air preparation unit 6.
The apparatus units are interconnected by hoses provided with valves 15, with pressure gauges 29 provided on the hoses connected to sprayer 2. The hose connecting air preparation unit 6 to container 1 is provided with a pressure gauge 30.
The top part of container 1 is provided with a filling aperture 31 and a 6 atm. safety valve 32.
Sprayer 2 (see:
Sprayer 2 has a clearly defined zone (Zone A) for accelerating the incoming air. It also has a Zone B for accelerating the mixture of air and cleaning suspension for mixing air with the suspension and initially accelerating the resultant mixture, and a Zone C in nozzle 24 of the accelerator for accelerating the mixture still further to produce a working flare of a large area and high cleaning efficiency.
Examples of loam and quartz dust mixtures used for cleaning purposes:
PP-MT 30: 30% of loam and 70% of powdered quartz;
PP-MT 50: 50% of loam and 50% of powdered quartz;
PP-MT 70: 70% of loam and 30% of powdered quartz; and
PP-MT 90: 90% of loam and 10% of powdered quartz.
The cleaning mixtures are dispersions of washed loam and special-purpose additives.
The above-mentioned mixtures may comprise GOST-28177-89 Standard loam of grain size down to 40 μm and GOST-9077-82 Standard powdered quartz of grain size down to 40 μm.
It is more preferred, though, to use grains ranging from 100 μm to 1.8 mm in size. Coarser grains are used for removing heavy pollution such as corrosion and aged paint and allow surfaces to be cleaned to quality Sa2 under ISO 8501-1 Standards, and finer grains (between 100 μm and 300 μm) are further comminuted as they are mixed and are suitable for AHD cleaning and treating surfaces without modifying the chemical composition of the surface layer thereof, which is a critical factor for many types of items required to have a high fatigue strength and resistance to uncontrolled chemical processes in operation, and achieve cleaning quality of Sa3 under ISO 8501-1 Standards.
The choice of a cleaning mixture depends on the extent and type of pollution of the surface to be cleaned, equipment, finishing materials, conditions of house front walls, and presence of architectural features, and is dictated by the technique adopted for a specific job.
A majority of pollutions are cleaned by a mixture of no more than 6 liters of cleaning mixture and 40 liters of water. Tap water is used for ultimately washing the cleaning products off the front wall of a house.
The PP-MT 30 mixture is used for cleaning heavy pollution, removing paint from a surface, removing rust and scale, for example, cleaning metal structures made from aluminum alloys and other nonferrous metals from atmospheric and other pollution.
The PP-MT 50 mixture is used for cleaning moderate pollutions, removing paint layer by layer, removing rust, moss, mildew, soot, graffiti from house front walls, and cleaning turbine rotors and architectural monuments.
The PP-MT 70 mixture is used for removing light pollutions, traces of salt, and dirt, soil, and atmospheric pollutions.
The PP-MT 90 mixture is used for cleaning fragile surfaces from light pollutions.
To prevent development of centers of biological destructive agents on front walls and monuments, powdered lime that conforms to the GOST-9179-77 Standards having a grain size of up to 100 μm may be used as a cleaning mixture.
The claimed method is performed during the operation of the apparatus as follows:
The apparatus can operate in the cleaning, washing/waterproofing, and drying modes. The operating modes of the sprayer are selected by opening or closing the respective valves provided on sprayer 2 and having pipes connected thereto.
The apparatus has to be operated at an ambient air temperature of or above +5° C.
Depending on the type and extent of pollution, the spacing between the surface being cleaned and the outlet aperture of nozzle 24 is preferably between 50 and 180 mm. In operation, the nozzle axis has to be directed at an angle of 60 to 80 degrees to the house front wall being cleaned.
Operation of the apparatus comprises the successive steps of:
-
- checking the air and suspension supply systems for gaps;
- connecting the air supply hoses to the compressor and checking the connection for reliability and twists of the air and suspension supply hoses;
- filling container 1 with a ready mixture or preparing the mixture in container 1 itself by pouring tap water into the container and adding the solid component of required concentration;
- turning on the mixture stirring mechanism for preliminary stirring of the mixture for at least 10 seconds; and
- turning on air and suspension flow into their respective lines and holding sprayer 2 firmly in hand and directing nozzle 24 toward the surface being cleaned.
In the cleaning mode, air flows under a pressure of 4 to 12 atm. into air supply device 3 where it is distributed to the respective systems. Air is dried in drier 7 of air preparation unit 6 and lubricant is added thereto from lubricant supply device 8.
Air flows from unit 6, through a valve/controller, to air motor 5 that transmits rotation to stirrer 4 provided with blades 9 and comminuting cutter 10 to stir the mixture of water and cleaning material or comminute dry cleaning material of soda type in container 1.
Air also flows from unit 6 to container 1 for preparing abrasive suspension and maintaining pressure therein at 1 to 1.5 atm. required for preparing a suspension and pumping it through a hose to sprayer 2.
When the cleaning material is mixed with water in the PP-MT proportions given above an abrasive suspension is produced at a pressure of 1 to 1.5 atm. it requires for displaying its AHD properties and producing the Rebinder effect.
The suspension is pumped from container 1 through channel 19 to pipe 20 or to an annular chamber 27 to be mixed at the outlet thereof with the air stream flowing under high pressure in channel 18 from device 3 and is accelerated. From that point on, the mixture of air and suspension is accelerated to high velocities. The stream effect produces the so-called hydro-abrasive aerosol consisting of abrasive particles, air, and liquid. The hydro-abrasive aerosol thus produced is used to clean surfaces. The high-velocity air stream (flowing at over 500 m/sec) is the energy agent carrying aerosol particles in the AHD method. Aerosol particles are water molecules gathered into drops under high pressure (about 1 atm.), with solid particles (abrasive dust) measuring between 300 nm and 40 μm trapped inside them. As water strikes a surface, it reduces, due to the Rebinder effect, the strength of the surface being cleaned, whereupon an abrasive particle destroys the dirt, and water flushes out the broken fragments and washes them away together with the abrasive used.
The working fluid carries abrasive particles from the supply container to the surface being treated, cleans the surface being treated continuously, removes the spent abrasive particles and particles of the material dislodged, prevents dusting, controls the heat in the treatment zone, and allows cleaning wastes to be collected and the working mixture to be used again.
In the washing/waterproofing mode, air pump 14, also operated by air supplied from device 3, forces water or waterproofing agent from washing liquid container 13 through a hose to sprayer 2.
The drying mode is turned on by closing two valves 15 on the hoses connected to containers 1 and 13 and opening valve 15 of the hose connected to air supply device 3. The air stream ejected as a result from sprayer 2 is used to dry a damp surface.
The claimed method used to treat a surface does not affect negatively the original surface of metal, which is an advantage that distinguishes it from other cleaning and deactivating methods. Treatment by the claimed method does not alter the physical and chemical composition of the surface layer of metal, which is a valuable factor for many types of components required to be resistant to fatigue strength deterioration and uncontrollable chemical processes in operation. Moreover, the claimed method helps improve the adhesive properties of metal because of reduced water absorption by the surface thereof following treatment by the claimed method.
Claims
1. An apparatus for aerohydrodynamic abrasive cleaning of surfaces comprising a container for preparing an abrasive suspension by a stirring mechanism including a stirrer having at least one blade, and a sprayer for spraying the abrasive suspension connected to said container and a compressed gas supply device, wherein the stirrer of the stirring mechanism has a comminuting cutter provided thereon in the bottom part of the container.
2. The apparatus as claimed in claim 1, wherein the stirring mechanism comprises an air motor associated with the stirrer and connected to the compressed air supply device through an air preparation unit including a drier and a lubricant supply device.
3. The apparatus as claimed in claim 1, wherein the mixing container is provided with a filling funnel having a locking device.
4. The apparatus as claimed in claim 1, further having a washing liquid container connected to the sprayer through an air pump that is connected to the compressed gas supply device through an air preparation unit having a drier and a lubricant supply device.
5. The apparatus as claimed in claim 1, wherein the units thereof are interconnected by hoses having valves provided thereon, the hoses connected to the sprayer being provided with pressure gauges.
6. A sprayer for aerohydrodynamic abrasive cleaning of surfaces comprising a hollow body provided with a nozzle at the outlet thereof, a compressed gas flow channel and a cleaning suspension flow channel, both connected to the body interior, wherein the compressed air flow channel is connected to the cylindrical interior of the body at the side thereof opposite to the nozzle, the sprayer is provided with an atomizer in the form of a T pipe received in the body interior, the crosspiece of said T pipe extending along the body axis and the vertical leg thereof being connected to the cleaning suspension flow channel, the nozzle has a tapering part and a cylindrical part at the outlet thereof, and the outlet aperture of the atomizer is spaced from the inlet of the cylindrical part of the nozzle to provide a zone for accelerating cleaning suspension aerosol particles.
7. A method for aerohydrodynamic abrasive cleaning of surfaces by entraining the abrasive suspension flow in compressed gas to produce aerosol particles and directing the stream of aerosol particles from the sprayer nozzle at the surface, wherein the aerosol particles formed are accelerated within the sprayer before they are ejected from the nozzle.
8. The method as claimed in claim 7, wherein the nozzle has a part that does not flare at the outlet thereof.
9. The method as claimed in claim 7, wherein the abrasive suspension comprises solid particles of loam and silica and water, wherein the loam and silica are used in the following proportions, in mass %:
- loam 25 to 90
- silica 10 to 75.
10. The method as claimed in claim 9, wherein the solid loam and silica particles have a size of 100 μm to 1.8 mm.
Type: Application
Filed: Mar 18, 2011
Publication Date: Sep 29, 2011
Inventor: Alexandr Viktorovich Kostevich (g. Saint-Petersburg)
Application Number: 13/065,279
International Classification: B24C 1/00 (20060101); B24C 3/00 (20060101);
