DE102010020619A1 - Method for cleaning metallic or non-metallic surfaces of e.g. turbine blade in steam turbine, involves loading flow of compressed air with carbon dioxide pellets, hardened pellets, water ice particles and fragmented pellets - Google Patents

Abstract

The method involves drying a hot, dry volume flow of compressed air with carbon dioxide (CO2) pellets (16) and with a fine-grained, solid abrasive (12) or the compressed air in stages to dew point of -60 degree Celsius. The hot, dry volume flow of compressed air is heated in the stages to +90 degree Celsius. The flow of compressed air is loaded with the CO2 pellets, hardened CO2 pellets, water ice particles or CO2 pellets with one-sided water ice, fragmented CO2 pellets with a closed water ice mantle, CO2-particles with one-sided or closed water ice mantle. An independent claim is also included for a device for executing a method for cleaning metallic or non-metallic surfaces by using compressed air.

Description

The The invention relates to a method and a device for cleaning of metallic or non-metallic surfaces below Use of compressed air, a cold abrasive, in combination with a solid blasting agent and / or a blasting agent mixture preferably to residue-poor to residue-free Removal of unwanted deposits in facilities such as the Energy production (steam turbines) and / or in chemical plants Industry, with the latter also explosive Areas are taken into account.

It are various methods for cleaning surfaces known. As blasting agent find it, in addition to high pressure water, too Sands, glass beads, slag or salts in a blasting medium like Water or compressed air use.

adversely with these is that residues in the plant and store the environment and the components must be removed.

Also known is cleaning with CO ₂ pellets, CO ₂ particles or CO ₂ snow with compressed air.

An advantage of this method is that no abrasion occurs on the surfaces to be cleaned. The disadvantage, however, is that only impurities that become brittle under the influence of cold, are removed. However, for the effective use of CO ₂ Strahltechnik a temperature difference is necessary. This is not a problem with heated molds. Turbine and fan blades or individual system elements, which are not heated in principle, have a relatively low heat capacity, which is rapidly reduced when exposed to CO ₂ pellets or CO ₂ snow. As a result of reducing the heat capacity, the cleaning performance decreases and condensation of ambient air on the surface occurs. Since the CO ₂ pellets have only a low hardness no 100% tig clean surface is achieved.

WO 98/36230 describes a process in which CO ₂ pellets and CO ₂ snow are used with compressed air for cleaning.

Advantageous In this method is that no abrasion to be cleaned Surfaces occurs. The disadvantage, however, is that only impurities, which become brittle when exposed to cold can be.

Effective use of CO ₂ jet technology requires a temperature difference between the contaminant to be removed and the component. The impurity is cooled by CO ₂ pellets or CO ₂ snow and there is the required temperature difference or the thermoelectric voltage. This is not a problem with heated molds. The heat capacity remains nearly constant. Thin-walled components, such as the plates in plate heat exchangers or the blades in turbines or fans, which are not heated, have a relatively low heat capacity, which is rapidly reduced when exposed to CO ₂ pellets or CO ₂ snow. As a result of reducing the heat capacity, the cleaning performance decreases and condensation of ambient air on the surface occurs. Since the CO ₂ pellets have only a low hardness, with stubborn impurities no 100% tig clean surface is reached. There are known methods in which the CO ₂ -air mixture further blasting agents are added to increase the abrasiveness.

In DE 34 29 700 A1 describes a method in which the CO ₂ -air mixture is enriched with water ice to obtain a water mist. The disadvantage here is that the entire environment is moistened by the water mist.

In DE 34 34 163 A1 Water is added to the CO ₂ snow produced during the expansion of liquid CO ₂ , so that additional water snow is produced. This mixture is pelleted and blown onto the surface to be cleaned with a jet of water. As a disadvantage, the backlog of water and the rapid formation of flash rust has proven.

In DE 100 36 557 A1 a device for mixing solid abrasive into the CO ₂ -air mixture is described. A disadvantage is the constancy of the quantitative ratio between CO ₂ pellets and additional abrasive and the high wear in the metering unit.

In DE 35 05 675 A1 Water ice is blown onto the surface to be cleaned with a jet of water or compressed air. Also in DE 43 20 410 A1 describes a method in which a water jet, a refrigerant is added to form water ice.

The font DE 10 2006 002 653 A1 describes a method in which a CO ₂ compressed air jet in the blasting gun water is mixed.

DE 199 57 526 A1 describes a method with apparatus in which water ice is generated directly in the jet device and then blown with water onto the surface to be cleaned.

In addition to the necessary for cleaning with CO ₂ particles temperature difference between the component to be cleaned and the contamination comes it also in the blasting plant to significant temperature differences. At the beginning of operation, the blasting system has room temperature. During prolonged operation the temperature of the dosing unit is approx. -30 ° C. This temperature difference must be taken into account during manufacturing by tolerating. Although the abrasiveness can be increased to produce a clean surface, the surface must not be damaged. If abrasive with a coarse grain size is used, the surface will be scratched, which can be considered a mistake. Any cracks, for example when cleaning turbine blades, could not be detected and "hammered".

In WO 03/047814 A1 this is described for smoothing the surface of a turbine blade. If a blasting medium with a low grain size is used, the metering unit gets stuck due to the toleration, which is necessary due to the temperature difference. Another major disadvantage of the CO ₂ -strahltechnik is the static charge and the associated Abreißfunke. The occurring voltage can be 60,000 V and more. Even with good grounding, the static charge can not be safely prevented. This charging is opposed to use in fire and explosion-hazard areas.

Of the State of the art shows that there are further considerations needs, especially metallic surfaces in sensitive Areas of, for example, power generation plants or installations The chemical industry is free of impurities to clean, so no mechanical damage enter.

The invention is therefore based on the object to provide a method and an apparatus for performing the method, in the commercial CO ₂ pellets in combination with, the mechanical abrasiveness increasing mineral, fine-grained particles, as well as by water ice particles and water ice, the latter being the CO ₂ pellets are replaceable, are blasted by compressed air, which is subjected to a thermal treatment in several stages, on solid surfaces, which are preferably metal-safe nature.

The The problem is solved as follows, with respect to the inventive Thoughts basically on the claims 1 and 10 is referenced. The further embodiment of the invention results from the claims 2 to 9 and 11 bis 15th

to Disclosure of the invention, further instructions are required.

According to the method, a fine-grained blasting abrasive of particle size <0.16 mm is added to the said CO ₂ pellets by metering units operating separately from one another, wherein it is taken over by a compressed-air flow thermally treated in several stages. The supercritically dried and heated compressed air reduces the temperature difference between the start and operating phase of the metering units and thus leads to a reduction in tolerances and thus allows the use of a fine-grained blasting abrasive. Furthermore, the heated compressed air prevents the reduction of the temperature difference between the contaminant and the component to be cleaned. The supercritically dried compressed air counteracts condensate formation from the ambient air on the surface of the component to be cleaned.

At 12 bar, the compressed air discharged by the compressor has approximately 12 times more moisture than the ambient air and has a temperature of approx. 55 ° C. The compressed air is cooled to room temperature. In this case, a part of the moisture is released. In an adsorption dryer, the air is dried to a temperature of -50 ° C to -60 ° C. Predrying has been found to be necessary because it improves the efficiency of the adsorption dryer. The dried air is then heated to 80 ° C in several stages. The heating takes place in a closed pipe system. The water content remains approximately constant at 2%. The CO ₂ pellets and the additional blasting agent are added to this dry and hot compressed air stream. The CO ₂ pellets are not damaged by the hot compressed air flow, as they are exposed to the high flow rate and the short distance from the CO ₂ jet system to the cleaning only a very short time at this temperature and due to the Leydenfrost phenomenon an insulating gas envelope around the Forms CO ₂ -pells.

The hot and dry compressed air stream prevents cooling of the CO ₂ jet system and counteracts condensate formation.

When blasting, an outlet air flow of approx. 8 m ³ / min is sent to the treatment plant at 12 bar. If the losses are set at 20%, a blade surface is charged with about 6.4 m ³ / min of a CO ₂ air mixture having a temperature of about 80 ° C., which is enriched with an additional blasting agent. The hot compressed air stream heats up the component to be cleaned, for example the blade of a turbine, or leads the blade back to the heat extracted by the CO ₂ particles. The extremely dry compressed air stream absorbs moisture from the environment after leaving the blasting nozzle, thus preventing condensation on the surface of the blade, in the area of selective undercooling, by the CO ₂ particles.

In the case of the use of CO ₂ pellets without admixture of a fine-grained mineral blasting agent, but in combination with pure water ice and the water ice of CO ₂ pellets, this mixture is also supplied dried in several stages of compressed air, the CO ₂ pellets and the water ice from separate reservoirs are attached via a downstream grinder this. The CO ₂ pellets and / or the water ice are not damaged by the hot compressed air flow because they are exposed to the high flow rate and the short distance from the CO ₂ jet system to the cleaning only a very short time this temperature of 80 ° C and due to the Leydenfrost phenomenon forms an insulating gas envelope around the CO ₂ pellets and the water ice.

The hot and dry compressed air stream prevents cooling of the CO ₂ jet system and counteracts the formation of condensate. The individual blasting agent components and the blasting agent mixture have a very low temperature due to the prefabrication, as a result of which an immediate formation of condensate occurs in conjunction with the ambient temperature. This condensate can lead to ice formation on the container walls or in the pipes. To avoid this formation of condensation, the entire area, from the lid of the storage container to the introduction of the blasting medium in the compressed air or protective gas stream is sealed so that only when filling the reservoir, an access of the ambient air is possible. In addition, this sealed area is filled with CO ₂ gas. The CO ₂ gas is heavier than air and thus does not escape when filling the reservoir. When blasting, an outlet air flow of approx. 8 to 10 m ³ / min is sent to the treatment plant at 12 bar. If losses are set at 20%, the component surface is exposed to a compressed air quantity of about 6.4 to 8 m ³ / min with a temperature of about 80 ° C. The normal CO ₂ pellets and water ice hardened CO ₂ pellets are added to this compressed air jet in the blasting machine. The hardened CO ₂ pellets and the water ice are brought to the desired size in the blasting plant. This can be done with the aid of a common grinder or two separate grinders operating at the same or different speeds, thus affecting the ratio of hardened CO ₂ pellets to water ice. The hot compressed air stream heats up the components to be cleaned or leads the components back to the heat extracted by the CO ₂ particles. The extremely dry compressed air stream absorbs the moisture from the environment after leaving the jet nozzle and thus prevents condensation on the surface of the component to be cleaned, in the area of selective supercooling by the CO ₂ particles.

The Apparatus for carrying out the method using a solid abrasive can be described as follows.

It consists of a holding and guiding part for, adapted to the geometric shape of turbine and fan blades, spatially trained jet nozzle and the jet itself. Due to the small distances between the blade rings on the one hand and the blades on the other hand, the jet nozzles have a relatively large curvature have. For blades with a circumferential retaining ring, the curvature is approximately 180 ° to clean the area behind the retaining ring. As a result of the curvature, an accumulation of CO ₂ particles and solid blasting agent occurs on the outer radius of the curvature. This phenomenon is taken into account insofar as the cross section is changed from, for example, 10 × 10 mm at the beginning of the curvature to 50 mm (in the vertical direction) × 2 mm. Due to the curvature of the jet nozzle return forces are effective, which are difficult to control. These restoring forces are to be intercepted by the holding and guiding part.

At the blades with a retaining ring, the holding and guiding part so attached to the retaining ring that it is at the transition of scoop to shovel by loosening a pinch roller on the Retaining ring can be moved. For blades without retaining ring is the holding and guiding part attached directly to the blade. The jet nozzle, which in its dimensions the geometric Conditions of the turbine or fan blade to be cleaned needs to be adjusted, but the basic principle is retained, is guided by the holding and guiding part so that it is movable in three planes, in the axial direction of the nozzle, around the axis and around the vertical to the axial direction.

The apparatus for carrying out the process using CO ₂ pellets, hardened CO ₂ pellets and water ice consists of a reservoir for the hardened CO ₂ pellets or two reservoirs for normal CO ₂ pellets and water ice. Each hopper has a grinder that has its own drive. Thereby, the flow rate can be controlled or when using a blasting agent mixture, the ratio of the individual components are controlled to each other. Under the grinders is a collection or mixing container, which also serves as a buffer when the decrease by the dosing unit is lower. At the collecting or mixing container, the disc-shaped dosing unit, which is composed of three individual discs, mounted. The middle of the three discs is the actual dosing disc and is driven by a controllable motor. The metering disk has overlap dende long holes that absorb the blasting agent or the blasting agent mixture, from the slightly vibrating collecting or mixing container, and bring by the rotational movement in the compressed air or inert gas stream.

In a last variant, the cleaning process can be further improved in connection with the use of commercially available CO ₂ pellets. To do this:
The CO ₂ pellets are fed directly from a reservoir through a slot and crushed by a grinder, passed into a freezer. Through the slot, the amount is limited and through the grinder, the amount can be regulated. The linear arrangement of the slot and the grinder causes the CO ₂ pellets or the CO ₂ particles fall in a plane in the positively cooled, closed freezing container. At right angles to this Fallebene are arranged in pairs sputtering nozzles, on a common axis, at the same distance from the CO ₂ plane. The water jets, which are diluted by the paired spray nozzles, with a droplet size of 10-30 μm, meet in the CO ₂ plane and thus hit the CO ₂ particles at the same time. Due to the cold in the freezer container and the low heat capacity of the water droplets, the smallest droplets freeze on their way to the CO ₂ level. In order for the atomization of the water to be effective, the water is warmed and diluted with warm air (use of the memory effect).

• – ein kleines, schon gefrorenes Wassertröpfchen trifft ein CO₂-Partikel – beide Teile bleiben unverändert
• – ein kleines, schon gefrorenes Wassertröpfchen trifft ein großes, noch nicht gefrorenes Wassertröpfchen – es entsteht ein neuer, größerer Eistropfen
• – ein kleines, schon gefrorenes Wassertröpfchen trifft ein anderes kleines, schon gefrorenes Wassertröpfchen – beide Teile bleiben unverändert
• – ein noch nicht gefrorenes Wassertröpfchen trifft ein CO₂-Partikel – das Wassertröpfchen verbindet sich einseitig mit dem CO₂-Partikel
• – ein CO₂-Partikel wird von beiden Seiten von einem kleinen, noch nicht gefrorenen Wassertröpfchen getroffen – der CO₂-Partikel wird von einem Wassereismantel umgeben

The CO ₂ particles do not fall in the CO ₂ plane as a closed smooth curtain from the reservoir to the dosing unit, but as a network with different mesh size. This leads to the coincidence and formation of different grain and droplet sizes in the CO ₂ level.

• - a small, already frozen water droplet hits a CO ₂ particle - both parts remain unchanged
• - a small, already frozen water droplet hits a large, not yet frozen water droplets - it creates a new, larger drop of ice
• - a small, already frozen water droplet meets another small, already frozen water droplet - both parts remain unchanged
• - A not yet frozen water droplets hits a CO ₂ particle - the water droplet connects on one side with the CO ₂ particle
• - A CO ₂ particle is hit from both sides by a small, not yet frozen water droplet - the CO ₂ particle is surrounded by a water ice mantle

These types of hits can be continued for a long time as the CO ₂ plane moves through a water cylinder that is also moving. It is meant to express that in the freezer the formation of a mixture of
Water ice particles of different sizes,
commercially available CO ₂ pellets,
commercially available CO ₂ pellets with one-sided water ice,
commercially available CO ₂ pellets with closed water ice mantle, comminuted CO ₂ particles,
CO ₂ particles with one-sided water ice,
CO ₂ particles with closed water ice mantle

he follows.

This mixture remains constant as long as the parameters
Temperature in the freezer unit,
Water and air pressure at the spray nozzles,
Water and air temperature at the spray nozzles,
Amount of inserted media

be respected.

The resulting blasting agent mixture is not stored, but introduced directly into the compressed air stream via the dosing unit. The compressed air flow is specially prepared. The compressor Coming compressed air is cooled in an aftercooler. Subsequently, the cooled compressed air in a Adsorption dryer to a dew point of -70 ° C dried. This dry air will be in a special heating heated to about 80 ° C. This heated and dry jet of compressed air is added.

In spite of the high temperature difference between abrasive mixture and compressed air there is no damage to the abrasive mixture. Responsible this is the Leydenfrost phenomenon, as well the high speed in the pressure line from the blasting machine to the blasting gun and the small distance between the blasting machine and the blasting gun.

With the use of extremely dry and warm compressed air will cause sub-cooling, the component to be cleaned and thus the formation of condensate, prevented. Furthermore, the dry and warm compressed air endeavors the relative humidity possible for this temperature to reach and thus takes the through the water ice particles forming moisture.

• – dem Vorratsbehälter mit dem Eintragsbereich (Schlitz und Mahlwerk)
• – der Gefriereinheit mit Kältemittelpumpe für den Kühlmittelkreislauf
• – der Sprüheinheit mit Wassertank und Regeleinrichtung
• – der Dosiereinheit mit regelbarem Antrieb
• – dem Strahlschlauch mit Strahlpistole und Strahldüsen

The device for carrying out the method consists essentially of:

• - the reservoir with the entry area (slot and grinder)
• - The freezer unit with refrigerant pump for the coolant circuit
• - The spray unit with water tank and Regelein direction
• - The dosing unit with controllable drive
• - the blasting hose with blasting gun and blasting nozzles

The Invention will be described below with reference to embodiments be explained in more detail.

It demonstrate:

1 Scheme of the method for the addition of solid abrasive

1a Image: Side view of the device

1b : Top view of the device

2 : Scheme of the procedure for the use of hardened CO ₂ pellets

3 Scheme of the process using inert gas

4 : Basic structure of a blasting system for the use of hardened CO ₂ pellets

5 : Basic structure of a blasting system for the use of CO ₂ pellets and water ice

6 : Device for Producing a Water CO ₂ Blend Mixture - Front View

7 : as 6 -Top view

example 1

The device-technical structure of the method for the addition of a solid abrasive according to 1 which z. B. may be glass flour. The in the compressor 1 compressed air is delivered via a pressure line 2 to the radiator 3 passed and cooled there to ambient temperature. The accumulated water is passed through a condensate collector 4 deposited. After the cooler 3 the compressed air passes over the pipe 5 to the adsorption dryer 6 and is dried there to a dew point of -60 ° C. Subsequently, the extremely dry compressed air in the heaters 7 . 8th and 9 , in three stages, heated to 80 ° C. After the compressed air has been heated, the volume flow in a distributor 10 , at constant pressure, divided. One part, about 2/3 of the volume flow goes to the dosing unit 11 and take the solid abrasive 12 from the reservoir 13 on. The solid abrasive 12 is in its amount from the adjustable metering disk 14 certainly. The remaining third of the volume flow goes to the CO ₂ jet system 15 and takes the CO ₂ pellets here 16 on. The solid abrasive 12 is with 2/3 of the flow through the pressure hose 17 and the CO ₂ pellets 16 with 1/3 of the volume flow through the CO ₂ tube 18 to the blasting gun 19 promoted. In the blasting gun 19 Both flow rates are brought together and through the jet nozzle 20 blown on the components to be cleaned.

Example 2 - Reference is made to this Referring to Figs. 1a and 1b,

For cleaning the blade 21 and the through the retaining ring 22 resulting undercuts 23 the device with the, on the holding part 24 fixed, fixed role 25 on the retaining ring 22 set and by pressing the loose roll 26 through the handwheel 27 and the spindle 28 fixed. The jet nozzle 20 is using a shared, by screws 29 held together, guide bushing 30 in the holding part 24 guided. Two threaded pins 31 in the holding part 24 are located, engage in corresponding holes in the guide bushing 30 one. This turns the rotation around the axis 32 that are perpendicular to the nozzle axis 33 stands, allows. A guiding example between the nozzle ear 34 and the guide bush 30 allow rotation of the nozzle around the nozzle axis 33 and moving in the direction of the nozzle axis 33 , Depending on the position of the surface to be cleaned to the holding part 24 , is the jet nozzle 20 trained accordingly. In the example, the undercuts should 23 getting cleaned. The jet nozzle 20 hereby has a curvature 35 of 170 °. The inner output cross-section of the nozzle tube 34 is 10 × 10 mm = 100 mm ² . Due to the centrifugal forces is the solid abrasive 12 and the CO ₂ pellets 16 on the outer wall of the curvature. The inner cross section of the nozzle tube 34 is uniformly changed to H × B = 50 × 1.6 = 80 mm ² and then expanded again to a cross section of H × B = 50 × 2 = 100 mm ² .

For cleaning the undercuts 23 be after the appropriate blasting nozzle 20 in the guide bush 30 was used and the compressed air has the predetermined temperature and flow, the reservoir 13 with solid abrasive 12 and the reservoir 36 for the CO ₂ pellets 16 filled and set the default beam parameters. Confirmation of the start button starts cleaning.

Example 3

It is the device technology of the process for the use of hardened CO ₂ pellets according to 2 described.

The in the compressor 1 compressed air is delivered via a pressure line 2 to the radiator 3 passed and cooled there to ambient temperature. The accumulated water is passed through a condensate collector 4 deposited. After the cooler 3 the compressed air passes over the pipe 5 to the adsorption dryer 6 and is dried there to a dew point of -60 ° C. Subsequently, the extremely dry compressed air in the heaters 7 . 8th and 9 heated to 80 ° C in three stages. The heated air is transferred via the pipe 37 the blasting machine 38 fed. From the storage container 39 become the hardened CO ₂ pellets 40 added to the compressed air flow and then through the jet hose 41 to the blasting gun 42 brought.

Example 4

Describes the device technology structure of the process when using inert gas accordingly 3 ,

From a tank 43 CO _{2 is taken} as gas and with the control unit 44 reduced to the pressure required for cleaning. Depending on the cleaning task and the CO ₂ pellets used 16 is the reduced CO ₂ gas flow through the valve 45 to the heating unit 46 or via the pressure line 47 directly to the blasting machine 48 directed. In the blasting machine 48 is the CO ₂ gas stream with normal CO ₂ pellets 16 or hardened CO ₂ pellets 40 loaded. Before dosing the CO ₂ pellets 16 into the CO ₂ gas stream are the CO ₂ pellets 16 with the help of the grinder 49 brought to the desired size. The blasting machine 48 is completely sealed and is controlled by the gas metering 50 with CO ₂ gas, with low overpressure, charged, so that all switching operations take place under protective gas. The CO ₂ gas stream with the CO ₂ pellets 16 is over the, provided with a metal mesh, blast hose 51 to the blasting gun 52 guided.

Example 5

In Example 5, the basic structure of a blasting system for the use of hardened CO ₂ pellets according to 4 described.

The hardened CO ₂ pellets 40 are delivered in special transport containers and manually in the funnel-shaped storage container 53 the blasting machine 54 filled. Under the funnel-shaped reservoir 53 there is a grinder 55 containing the hardened CO ₂ pellets 40 on the, for the upcoming cleaning task cheap size brings. Under the grinder 55 is the collection room 57 as a buffer for the crushed CO ₂ pellets 58 , between grinder 55 and the disc-shaped dosing unit is used. The disc-shaped dosing unit consists of three individual discs. The upper disc 59 is stuck with the collection room 57 connected and has a breakthrough 60 below the collection room 57 , Another hole 56 is located 180 ° offset on the upper disc 59 , This hole 56 serves to accommodate the air or protective gas connection 61 , The lower disc 62 is by threaded bolt 63 firmly with the upper writing 59 connected. In the same position to the hole 56 the upper disc 59 is the starting hole 64 in the lower disc 62 , Between the upper disc 59 and the lower disc 62 is the rotatable dosing disc 65 , This dosing disc 65 has transport bores 66 , These transport holes 66 be through the breakthrough 60 with the crushed CO ₂ pellets 58 from the collection room 57 filled and transported in position between the holes 56 and 64 , In this position, the crushed CO ₂ pellets 58 mixed with the compressed air or inert gas stream. The area between the lid 67 of the storage container 53 and the dosing disc 65 is to prevent contact of the cured CO ₂ pellets 40 and the crushed CO ₂ pellets 58 with the humidity of the ambient air, filled with CO ₂ gas. To avoid unwanted pressure losses within the compressed air or inert gas flow, the lower disc 62 over the springs 68 and nuts 69 , together with the dosing unit 65 against the upper disc 59 pressed.

Example 6

In Example 6, the basic structure of a blasting plant for the use of CO ₂ pellets and water ice according to 5 described.

The CO ₂ pellets 16 are delivered in a transport box and from there manually into the storage container 70 the blasting machine 71 given. The water ice particles 72 are manufactured in a plant, not shown, and delivered in a special transport container. The water ice particles 72 are also manually in the reservoir 73 filled. Under the storage tank 70 is the grinder 74 for the CO ₂ pellets and under the storage tank 73 is the grinder 75 for the water ice particles 72 , Both grinders are driven separately, so that is the production of a blasting medium mixture 76 with different proportions of CO ₂ pellets 16 and water ice particles 72 possible. The ground portions of the water ice particles 72 and the CO ₂ pellets 16 be in the funnel-shaped collection container 77 buffered. The disc-shaped dosing unit consists of three discs. The upper disc 59 is fixed to the collection container 77 connected and has a breakthrough 60 below the collection container 77 , Another hole 78 is located 180 ° offset on the upper disc 59 , This hole 78 serves to accommodate the air or protective gas connection 61 , The lower disc 62 is by threaded bolt 63 firmly with the upper writing 59 connected. In the same position to the hole 78 the upper disc 59 is the starting hole 64 in the lower disc 62 , Between the upper disc 59 and the lower disc 62 is the rotatable dosing disc 65 , This dosing disc 65 owns transport drilling gene 66 , These transport holes 66 be through the breakthrough 60 with the blasting agent mixture 76 from the collection room 77 fill and transport these in position between holes 78 and 64 , In this position, the blasting agent mixture 76 mixed with the compressed air or inert gas stream. The area between the lid 79 of the storage container 70 and the lid 80 of the storage container 73 on the one hand and the dosing disc 65 on the other hand, is to prevent the contact of the hardened individual blasting agents 16 and 72 , as well as the blasting agent mixture 76 with the humidity of the ambient air, filled with CO ₂ gas.

To avoid unwanted pressure losses within the compressed air or inert gas flow, the lower disc 62 over the springs 68 and nuts 69 , together with the dosing unit 65 against the upper disc 59 pressed.

Example 7

Here, the method according to the 6 and 7 continue running. The commercially available CO ₂ pellets 16 get out of the transport box into the hopper 81 given. To fill the lid 82 open for a short time. The filling opening 83 is with a hinged flap 84 consisting of several individual segments 85 exists, provided. This flap 84 regulates the supply of CO ₂ pellets 16 in the freezer 86 , Is the door 84 swung to the left, get the commercial CO ₂ pellets 16 through the slot 87 in the freezer 86 , The freezer container 86 consists of the inner container 88 and the outer container 89 , Between the two containers 88 and 89 the coolant flows 90 that by the pump 91 from the refrigeration part 92 through the pipes 93 to the freezer 84 is encouraged. Will the flap 84 swung to the right, the slot becomes 87 covered and the CO ₂ pellets 16 get over the grinder 94 that by the controllable engine 95 is driven into the freezer 86 , Will be part of the individual segments 85 to the left and the other individual segments 85 swung to the right, enters a part of commercially available CO ₂ pellets 16 directly into the freezer 86 and another part is in the grinder 94 crushed and then enters the freezer 86 , Perpendicular to the CO ₂ level 96 are water nozzles 97 arranged in pairs. With the line 98 gets the water and with the pipe 99 the compressed air to the water nozzle 97 guided. The resulting water-CO ₂ -strahlmittelgemisch 100 becomes in the funnel-shaped area 101 of the freezer 86 collected and through the hole 102 in the upper disc 59 into the recesses of the dosing disc 65 directed. The engine 103 driven dosing disc 65 transports the water CO ₂ -blendmittelgemisch 100 from the hole 102 to the area of the connecting piece 104 in the upper disc 59 , Through the connection piece 104 passes through the pressure hose 105 (not shown) supplied warm and dry compressed air to the dosing 65 and takes the water-CO ₂ blasting agent mixture 100 and leads it through the outlet nozzle 106 on the lower disc 62 in the blast hose 107 , The lower disc 62 and the spacer ring 108 are through the bolts 109 with the upper writing 59 firmly connected.

On the one hand, the advantage of the invention is that the range of application of the cold blasting technique can be extended by combining the CO ₂ blasting medium technology with a fine-grained solid blasting medium. Through the CO ₂ particles the selective cooling and embrittlement takes place of the impurities, while the solid blasting agent destroys the surface of the contamination and hence the penetration of the particles forming a _2-on impact of the fine CO CO ₂ -Grieses improved in the cracks. Another advantage of the invention is that the metering of the additional blasting agent can be independent of the type and amount of CO ₂ particles. A further advantage is that by the hot compressed air flow condensate formation when adding the CO ₂ particles, which cause cooling of the compressed air flow, is prevented. As a further advantage, as a result of the hot compressed air flow, the small temperature difference between the start of operation and the course of operation has proved in blasting system and metering unit. The lower temperature difference allows finer tolerances and thereby allows the use of a fine-grained additional abrasive.

conditioned by the hot compressed air flow, with a very low Moisture content, this airflow is after exiting the jet nozzle endeavors to absorb moisture. These Moisture is removed from the immediate ambient air. In order to is a formation of condensate on the surface of the Shovel prevents.

The advantage of the invention, on the other hand, is that by combining the CO ₂ jet technology with a fine-grained solid abrasive of the water ice, the range of application of the cold jet technique can be extended. Through the CO ₂ particles the selective cooling and embrittlement of the impurities is carried out, while the solid blasting agent destroys the surface of impurities and the penetration of the particles is ₂ forming the occurrence of the CO fine improved CO ₂ -Grieses in the cracks. The use of hardened CO ₂ pellets with and without water ice increases the aggressiveness of the cleaning jet. With a grinder in the blasting system, the water ice and hardened CO ₂ pellets can be brought to the most favorable size for the component and the impurity. A significant advantage of the invention is that with the use of the cured CO ₂ pellets the abrasiveness is increased, but nevertheless no residues remain in the system or in the area of the components.

LIST OF REFERENCE NUMBERS

1

compressor

2

pressure line

3

cooler

4

condensate collector

5

management

6

adsorption

7

stoker 1

8th

stoker 2

9

stoker 3

10

distributor

11

dosing

12

solid blasting agent

13

reservoir

14

metering

15

CO2 blasting plant

16

CO2 pellets

17

pressure hose

18

CO2 hose

19

blasting gun

20

jet

21

shovel

22

retaining ring

23

undercut

24

holding part

25

firm role

26

loose role

27

handwheel

28

spindle

29

screw

30

guide bush

31

Set screw

32

axis

33

nozzle axis

34

nozzle tube

35

curvature

36

nozzle head

37

management

38

blasting Machine

39

reservoir

40

CO2 pellets, hardened

41

ray tube

42

blasting gun

43

tank

44

control unit

45

Valve

46

heating unit

47

pressure line

48

blasting Machine

49

grinder

50

gas metering

51

ray tube

52

blasting gun

53

reservoir

54

blasting Machine

55

grinder

56

drilling

57

plenum

58

CO2 pellets, crushed

59

upper disc

60

breakthrough

61

Air- or inert gas connection

62

lower disc

63

threaded bolt

64

exit bore

65

rotatable metering

66

conveying hole

67

cover

68

feather

69

mother

70

reservoir

71

blasting Machine

72

Water ice particles

73

reservoir

74

grinder

75

grinder

76

Blasting agent mixture

77

tanks, funnel-shaped

78

drilling

79

cover

80

cover

81

hopper

82

cover

83

fill opening

84

Flap, swiveling

85

individual segments

86

freezing container

87

slot

88

internal container

89

outer container

90

coolant

91

pump

92

cold part

93

management

94

grinder

95

Engine, adjustable

96

CO2 level

97

water jets

98

management

99

management

100

Water CO2 blasting agent mixture

101

trichterfömiger Area

102

drilling

103

engine

104

spigot

105

pressure hose

106

outlet connection

107

ray tube

108

spacer

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• WO 98/36230 [0006]
• - DE 3429700 A1 [0009]
• - DE 3434163 A1 [0010]
• - DE 10036557 A1 [0011]
• - DE 3505675 A1 [0012]
• DE 4320410 A1 [0012]
• DE 102006002653 A1 [0013]
• DE 19957526 A1 [0014]
• WO 03/047814 A1 [0016]

Claims (15)

Method for cleaning metallic or non-metallic surfaces using compressed air, a cold blasting medium, in combination with a solid blasting medium and / or a blasting medium mixture, wherein a hot, dry volume flow of compressed air with CO ₂ pellets ( 16 ) and with a fine-grained, solid abrasive ( 12 ) or the compressed air is dried in several stages up to a dew point of -60 ° C, then heated in several stages up to + 90 ° C and with CO ₂ pellets ( 16 ), hardened CO ₂ pellets ( 40 ), Water ice particles ( 72 ) or the compressed air with water ice particles ( 72 ), CO ₂ pellets ( 16 ), CO ₂ pellets ( 16 ) with one-sided water ice, CO ₂ pellets ( 16 ) with a closed water ice mantle, crushed CO ₂ pellets ( 58 ), CO ₂ particles loaded with unilateral or closed water ice mantle. Method for cleaning metallic or non-metallic Surfaces according to claim 1, characterized in that the fine-grained, solid abrasive means a grain size of less than 0.16 mm. Method for cleaning metallic or non-metallic surfaces according to claim 1, characterized in that by the hot, almost dry volume flow passing through the CO ₂ pellets ( 16 ) process-dependent supercooling, in particular the cooling of not directly with CO ₂ pellets ( 16 ) acted upon surfaces before and after cleaning, is balanced so that sets a constant temperature difference between the component to be cleaned and condensate formation is prevented from the ambient air. Method for cleaning metallic or non-metallic surfaces according to claim 1, characterized in that the cold CO ₂ pellets ( 16 ) loaded, hot, dry compressed air stream in another dosing unit ( 11 ) a solid fine-grained dry abrasive ( 12 ) is added. Method for cleaning metallic or non-metallic surfaces according to Claim 1, characterized in that a blasting-agent mixture ( 76 ) of hardened CO ₂ pellets ( 40 ) and frozen water ice ( 72 ) is added, wherein the blasting agent mixture ( 76 ) either directly in the production structure or in comminuted form with respect to the comminuted CO ₂ pellets ( 58 ) is added to the hot, dry compressed air stream. A method of cleaning metallic or non-metallic surfaces according to claim 1, characterized in that the hot, dry compressed air stream, a blasting agent mixture ( 76 ) consisting of CO ₂ pellets ( 16 ) and frozen water ice ( 72 ) is added, wherein the blasting agent mixture ( 76 ) immediately before introduction into the compressed air stream by direct mixing of the two individual components or after comminution by the grinders ( 74 . 75 ) will be produced. Method for cleaning metallic and non-metallic surfaces according to claim 1, characterized in that the CO ₂ pellets ( 16 ) or the hardened CO ₂ pellets ( 40 ) or the blasting agent mixtures ( 76 ) by a protective gas flow, a tank ( 43 ) and after a reduction ( 44 ) either in a heating unit ( 46 ) or directly to the dosing unit ( 11 ), and from the latter to a blasting gun ( 19 ) to be led. Method for cleaning metallic or non-metallic surfaces according to claim 1, characterized in that the CO ₂ pellets ( 16 ) from a filling container ( 81 ) through a slot ( 87 ) and by a grinder ( 94 ) with adjustable motor ( 95 ) are crushed and by means of the line-shaped formation of the slot ( 87 ) and the grinder ( 94 ) the CO ₂ pellets ( 16 ) or the crushed CO ₂ pellets ( 58 ), the latter in particle form, in a freezing container ( 86 ), at right angles to their Fallebene water nozzles ( 97 ) - on both sides of the freezer ( 86 water, whereby water droplets are formed and the CO ₂ pellets ( 16 ) and the crushed CO ₂ pellets ( 58 ) are completely or partially covered with a water ice mantle. Method for cleaning metallic or non-metallic surfaces according to Claims 1 and 8, characterized in that the compressed air generated by a compressor is cooled in an aftercooler and the cooled compressed air is dried in an adsorption dryer to a dew point of -70 ° C, then to + Heated to 80 ° C and mixed with the blasting agent mixture ( 100 ) is loaded. Device for carrying out the method according to claim 1, characterized in that it has a fixed roller ( 25 ) on a retaining ring ( 22 ) is set and by a loose role ( 26 ), which by a holding part ( 24 ) with handwheel ( 27 ) on the retaining ring ( 22 ) is pressed through a jet nozzle ( 20 ) restoring forces and moments are intercepted, wherein the jet nozzle ( 20 ) in the split, by screws ( 29 ) held together, guide bush ( 30 ), which are replaced by setscrews ( 31 ) a rotational movement about the axis ( 32 ), is performed so that a nozzle tube ( 34 ) in the direction of a nozzle axis ( 33 ) and around the nozzle axis ( 33 ) can be rotated, that a nozzle head ( 36 ), which by in a curvature ( 35 ) from a square cross section to a vertical rectangular cross section over is, with the smallest cross-section of the then widening cross section, 80% of the nozzle tube ( 34 ) and can be guided to the areas to be cleaned. Device for carrying out the method according to claim 1, characterized in that a storage container ( 53 ) via a collecting space ( 57 ) and by a grinder ( 55 ) containing the CO ₂ pellets ( 16 ) or the hardened CO ₂ pellets ( 40 ) is comminuted to the required size, separated and the comminuted CO ₂ pellets ( 58 ) with the aid of the rotating metering disc ( 65 ) from the collection room ( 57 ) can be introduced into the compressed air or inert gas stream, wherein the entire device-technical area from the lid ( 67 ) until the crushed CO ₂ pellets ( 58 ) in the compressed air or protective gas flow, to protect against condensation, is depressurized filled with a CO ₂ gas. Device for carrying out the method according to claim 1 and 11, characterized in that two storage containers ( 70 . 73 ) or several storage containers next to each other via a common collecting container ( 77 ), through the grinders ( 74 . 75 ) are arranged separately and the grinders ( 74 . 75 ) with different speeds the CO ₂ pellets ( 16 ) and the water ice particles ( 72 ) and at the same time the desired mixing ratio of the blasting agent mixture ( 76 ) in the collecting container ( 77 ), wherein the blasting agent mixture ( 76 ) with the aid of the rotating metering disc ( 65 ) from the collecting container ( 77 ) can be introduced into the compressed air or protective gas stream and the entire device-related area from the cover ( 79 ) and lid ( 80 ) until the crushed CO ₂ pellets ( 58 ) in the compressed air or protective gas flow, to protect against condensation, depressurized filled with a CO ₂ gas. Device for carrying out the method according to Claim 1, characterized in that a cover (10) formed with a gas-tight seal ( 82 ) provided filling container ( 81 ), which runs down in a funnel shape, onto a freezing container ( 86 ) is placed, wherein between the outlet opening of the filling container ( 81 ) and the freezer ( 86 ) a grinder ( 94 ), which on one side a slot ( 87 ), the freezer ( 86 ) in its upper area - not far from the grinder ( 94 ) - Water nozzles ( 97 ) and also the funnel-shaped outlet of the freezing container ( 86 ), to a dosing unit ( 11 ), wherein the dosing unit ( 11 ) via a connection for a pressure hose ( 105 ) and a blasting hose ( 107 ). Apparatus for carrying out the method according to claim 1 and 13, characterized in that before the grinder ( 94 ) within the filling container ( 81 ) a hinged flap ( 84 ) is mounted at the lower end of its funnel-shaped outlet, the pivotable flap ( 84 ) from individual pivotable individual segments ( 85 ) is composed. Device for carrying out the method according to claim 1, characterized in that the freezing container ( 86 ) is double-walled and in its double-walled jacket, a coolant ( 90 ), which is in circulation with a pump ( 91 ) and a refrigerant ( 92 ) is located.

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