Device for simultaneously producing and processing a solid abrasive from water for cleaning surfaces and systems

Abstract

Device for producing a solid cryogenic abrasive from water, characterized in that the cryo-tube and loading unit form a single unit, wherein one or more spray nozzle blocks, equipped with identical or different interchangeable spray nozzles, are arranged in the cone of the cryo-tube such that the water can be sprayed from below into a cold nitrogen atmosphere of the cryo-tube, and the amount of nitrogen required for ice formation can be introduced from nitrogen nozzles attached to the tube and the lid, and the frozen water droplets immediately fall from the cryo-tube into the loading unit for absorption into the transport gas stream, assisted by the gas pressure generated during freezing.

Description

[0001] The invention relates to a device for the simultaneous production and processing of a solid abrasive from water for residue-free cleaning of surfaces and equipment, whereby water, which is sprayed from below into a cold atmosphere of a cryo-tube, freezes into small, blasting-capable water ice particles, and whereby the gas produced by the expansion of the liquid nitrogen supplied under high pressure, in addition to cooling the water and the cryo-tube, also supports the transport of the cryogenic water ice particles in the transport gas stream, which carries the water ice particles from the injector to the blasting gun.

[0002] In addition to purely mechanical blasting methods, thermally acting methods, known as cold blasting, are also used. Various cold blasting techniques are known. These thermally acting methods employ different blasting media, such as dry ice, CO2 snow, water ice, or combinations of dry ice with solid, fine-grained blasting media, which are propelled onto the surface to be cleaned using water or compressed air.

[0003] The primary blasting medium used is CO2 dry ice at a temperature of approximately -75°C, which sublimates after blasting and evaporates as a gas. The disadvantage of this cold blasting medium is its low corrosiveness.

[0004] The use of ice as an abrasive is also known. In most cases, ice with a temperature of -20°C to -40°C is used. At these temperatures, the ice does not yet have a particularly strong hardness.

[0005] From WO 2003 101667 A1, it is known that CO2 pellets are used as a solid blasting medium for cleaning surfaces. The CO2 pellets act as a soft, non-abrasive blasting medium, thus preventing damage to the surface being cleaned. The temperature of approximately -75°C of the CO2 pellets creates a thermal stress between the contaminant and the surface of the component being cleaned, which causes the contaminant to detach (cryogenic effect). However, a disadvantage of cleaning with CO2 as a blasting medium is its low abrasiveness. This low abrasiveness limits its range of applications.

[0006] German patent DE 103 09 191 A1 discloses a device for dry ice blasting using a mixture of compressed air and dry ice for cleaning surfaces. The brittleness of the CO2 pellets has proven to be a disadvantage. Due to this brittleness, approximately 70% of the CO2 pellets are partially lost unused upon impact with the surface to be cleaned. In DE 100 10 012 A1 and DE 201 15 013 U1, CO2 pellets are added to the compressed air stream, along with another abrasive that is solid at room temperature to increase its abrasiveness. However, a disadvantage of this method is that some of the added solid abrasive remains in the system, and dust generation cannot be avoided.

[0007] DE 100 36 557 A1 describes a device for adding solid blasting media as a third blasting medium to the CO2-air mixture. Disadvantages include the inconsistent ratio of CO2 pellets to the additional blasting media and the high wear in the metering unit.

[0008] US Patent 5367838 describes a device in which ice water at a temperature of approximately -30°C is blown onto a contaminated surface using compressed air for cleaning purposes. The low hardness of the ice and the formation of condensation due to the moisture in the blasted air proved to be disadvantages, leading to a reduction in cleaning effectiveness.

[0009] German patent DE 35 05 675 A1 describes a method for surface ablation in which water ice particles at a maximum temperature of -30°C are added to a water jet. The water ice can also be formed by ice-forming nuclei within the water jet. A disadvantage of this method is that no cryogenic effect occurs; only mechanical ablation takes place, and even that is minimal.

[0010] In German patent DE 34 34 163 A1, water is added to the CO2 snow produced when liquid CO2 is depressurized, creating additional water snow. This mixture is pelletized and blown onto the surface to be cleaned using a water jet or compressed air. A disadvantage of this technology is the low hardness of the abrasive, as the temperature is only around -50 °C and the lubricating effect of the water reduces the cleaning effect.

[0011] US Patent 5,785,581 describes a system in which a cryogenic liquid, preferably liquid nitrogen, is used as a coolant to generate ice particles. In this system, water droplets are introduced under pressure into a cold gas stream in a freezing tube, converted into ice, and then blown from the nozzle onto the surface to be cleaned using the pressure differential. Here, too, only a minimal mechanical effect is observed, as the ice temperature, due to the short distance in the freezing tube, is only about -25 °C.

[0012] WO 2015 / 074765 A1 describes various methods for producing water ice. A disadvantage is that the water ice must be further crushed to obtain radioactive particles, making the formation of a condensate film unavoidable. Another drawback is the relatively rigid cooling method using liquid nitrogen spraying, which simultaneously creates a cold gas atmosphere and cools the injected water droplets. This results in a relatively stationary gas atmosphere around the water droplets or water ice particles, negatively impacting further cooling. The manufacturing process itself is also problematic. The cooling time is limited to the free fall time. The required spray pressure accelerates the free fall of the water droplets, thus reducing the cooling time. This limits the size and hardness of the water ice particles.Production cannot be continuous; it must be interrupted after a certain time so that the produced ice pops can be removed. If the removal is not carried out in an airtight environment, condensation and consequently partial refreezing of the ice pop particles are unavoidable.

[0013] German patent DE 10 2020 000018 A1 describes a method in which the falling velocity of water droplets sprayed from above is slowed by a counter-current, thus extending the freezing time of the water droplet. The high structural and energy costs required for its implementation have proven to be a disadvantage.

[0014] The invention described in DE 10 2019 109 860 A1 relates to a method for the cryogenic production of water ice particles for abrasive surface treatment, comprising the following process steps: supplying water under pressure through at least one micro-orifice into the interior of a reaction vessel, generating microdroplets through the micro-orifice; impacting the microdroplets with a cold gas countercurrent, causing them to freeze into water ice particles, wherein the cold gas countercurrent is generated by introducing warm gas through a pool of low-temperature liquid gas located within the reaction vessel; and collecting the water ice particles in a collection device for conveying them to a blasting device for abrasive surface treatment. A device provided for this purpose is further described.A disadvantage of this method is the high amount of water remaining in the water-ice mixture and the incomplete freezing of the ice droplets due to the short freezing time caused by the short fall distance, resulting in low hardness.

[0015] US Patent 4,974,375 describes a process for producing small-grain water ice. Water is injected into the upper part of a cold tube through a nozzle. The coldness of the refrigerant introduced through lateral nozzles causes the water droplets to freeze into ice particles. A hopper in the lower part of the tube collects the ice particles, which are then transported via an injector line to the jet nozzle. These water ice particles are specifically intended for cleaning applications in the semiconductor industry and are not suitable for general industrial cleaning.

[0016] In German patent 10 2023 003 658.7, a process is described in which cryogenic water ice is produced in a cryo-tube mounted on a blasting machine and collected in a collecting cone belonging to the cryo-tube. At intervals, it is fed into the storage container of the blasting machine and from there metered into the transport gas stream by means of a rotary valve, or directly from the collecting cone into the transport gas stream by means of the rotary valve. A disadvantage has been found to be an uncontrolled pressure build-up in the cryo-tube when nitrogen is supplied, as the energy balance cannot be fully achieved due to the varying droplet sizes.

[0017] DE 20 2016 101 965 U1 describes a blasting device for cleaning surfaces with first and second particles of water and dry ice, comprising a first feed arrangement for the first particles and a second feed arrangement for the second particles. The two particle types differ in size, hardness, and shape. A first metering device is located below the first feed arrangement, and a second metering device is located below the second metering arrangement. Separately driven, toothed metering rollers transport the particles, metered and simultaneously crushed, into a common mixing chamber. From there, the particles are conveyed to the blast gun by the transport gas flow. The metering of the water-ice particles by the toothed metering roller has proven to be a disadvantage. The water-ice particles are compressed in the V-shaped intake area of ​​the roller.This creates a film of water which refreezes during breaks, thus blocking the dosage.

[0018] In WO 94 / 16861, a cooled roller passes through a water bath. An ice film forms on the surface of the roller, which is then removed by knives. Air jets or wire rollers crush the scraped ice sheets into irregular pieces. These ice pieces are then ground to the required size for blasting in a mill. A disadvantage of this process is that the temperature of the water ice is -15 °C and water is produced during the grinding process.

[0019] German patent DE 40 30 434 A1 specifies that fine frozen particles with a size of 0.01 to 5 mm are used to remove contaminants. These fine frozen particles are blown against the surface to be cleaned along with nitrogen-cooled air. The fine frozen particles are produced by freezing a liquid, such as water or alcohol. The hardness of the fine particles is adjusted depending on the type of liquid, the freezing temperature, and the blasting temperature to prevent damage to the surface.

[0020] German patent DE 103 60 011 A1 describes a cleaning method in which ice water at a temperature of approximately -10 °C is blown onto the surface to be cleaned, and the resulting water removes the dissolved contaminants. A disadvantage of this method is that the ice water only has a temperature of -10 °C and quickly condenses back into water, thus offering only limited cleaning performance.

[0021] German patent DE 10 2023 003 658 A1 describes a process in which cryogenic water ice is produced in a countercurrent process and introduced into the transport gas stream using a rotary valve. A disadvantage of this process is that the rotary valve compresses the water ice in the intake area, which can lead to water formation and refreezing during pauses. Furthermore, the rotary valve acts as a seal, and excess nitrogen is vented to prevent overpressure in the cold chamber.

[0022] The analysis of the state of the art in the production and processing of water ice has shown that there are numerous technologies for producing water ice, but none are suitable for general industrial use. In most examples, water ice is produced at temperatures below -50 °C, e.g., (1) company publications of ZIEGRA, or (2) company publications of Kälte Berlin. The water ice produced is mainly used for cooling in the food industry and has a temperature of up to -25 °C. The water ice is manufactured and sold in blocks, as slices, as nuggets in various sizes, or as crushed ice. Crushing by grinding, scraping, or crushing has proven unfeasible due to the water formation caused by the required operating pressure.

[0023] The addition of solid blasting media, as described in CO2 dry ice blasting in DE 100 36 557 A1 and DE 102015209994 A1 or (3) the company brochure of Cryonomic “Abrasives Dry Ice Blasting” and (4) the company brochure of DCA Deckert Anlagenbau GmbH “New Generation Dry Ice Cleaning”, does increase the aggressiveness, but is difficult to mix due to the temperature difference. A disadvantage is the retention of the solid blasting media in the system and the potential for surface damage.

[0024] From (5) A. Momber “Handbook on the Surface Treatment of Concrete” and (6) B. Karpuschewski “Basic Considerations on Deburring as a Novel Method for Deburring Complex Components”, it is known that the hardness of water ice is temperature-dependent. The hardness of water ice is inversely proportional to its temperature. This means that the hardness of water ice increases with decreasing temperature. Thus, water ice at a temperature of -10°C has a Mohs hardness of 2, comparable to gypsum. In comparison, water ice at a temperature of -120°C has a Mohs hardness of 5–6.

[0025] The processes described in US 4 974 375 and DE 689 14 657 T2 are designed as stationary plants for the production of a specific particle size and are not suitable for mass production.

[0026] It is logical to use water ice with a hardness of approximately 5 Mohs as an abrasive. The solutions presented have demonstrated that water ice at low temperatures can, in principle, be produced, but no systems for the continuous production of blasting-grade cryogenic water ice in various particle sizes are currently available on the market.

[0027] The inventor discovered during experiments with commercially available water ice that it was unsuitable as an abrasive in its standard form. On the one hand, the structure was too large, and on the other hand, the hardness was too low. To utilize the advantages of brittleness and the reusability of individual particles that water ice offers over CO2 dry ice, a small, blasting-capable particle size was required.

[0028] Further processing of the offered ice water, e.g. by further cooling and subsequent crushing, even in several stages, has not brought the desired success, since crushing, regardless of the type of crushing, exerts pressure on the ice water, which in turn leads to the formation of a water film (ice skating effect) that causes the crushed ice particles to freeze together immediately.

[0029] In (7) “Ice blasting / deburring – an innovative concept for problem-oriented deburring of components and workpieces”, a cryo-tube is described with which fine water ice particles can be produced. The inventor's experiments with this cryo-tube have shown that it is not suitable for the continuous production of water ice because, on the one hand, a balanced energy budget cannot be achieved due to the independent supply of the media water and nitrogen, and on the other hand, the produced water ice is collected in the cone, and the production process must be interrupted for removal once a certain quantity has been produced.

[0030] Another disadvantage was its size of over 3.50 m, because the only time available for freezing the water introduced from above was during free fall in a cold atmosphere.

[0031] During filling after production and transfer to the blasting device, contact with the ambient air causes condensation to form on the surface of the water ice particles, leading to the refreezing of the individual particles. In further experiments with the cryo-tube described in (7), the inventor discovered that the exposure time to the cold is reduced by the interaction of the falling and spraying velocities, as the spray pressure imparts a certain velocity to the water droplets, which increases their falling speed. Furthermore, the inventor recognized that the ratio of the volume of water introduced to the droplet surface area is crucial for ice formation. The smaller the water droplets, the larger the total surface area and thus the heat transfer surface from the interior of the water droplet to the surrounding cold gas atmosphere in the cryo-tube.

[0032] Furthermore, the inventor discovered during the experiments that the generated water ice particles were larger than the sprayed water droplets. Therefore, several water droplets must have bonded together after spraying.

[0033] Another disadvantage is that there is a spatial and temporal difference between the production and processing of the ice cream, which negatively affects the service provider's ability to handle orders, deliveries, transport, and responding to requests.

[0034] The inventor's experiments revealed that the freezing time in most known methods, which introduce the water from above, does not correspond to the pure fall time. Since the droplets are introduced into the cryo-tube under pressure and thus with a relatively high initial velocity, the freezing time is reduced.

[0035] Since the prior art has not provided a satisfactory solution for the continuous production and processing of blasting-capable cryogenic water ice, the object of the present invention is to find a transportable device for the continuous production and simultaneous processing of a solid cryogenic blasting medium made from water, in variable quantities, with a particle size of 0.1-0.8 mm.

[0036] The problem is solved with a combined device consisting of a cryo-tube with a loading unit for the continuous production and processing of the manufactured cryogenic abrasive from water, by blowing the water from one or more nozzles of the same or different geometry into a cryo-tube from below, and by injecting liquid nitrogen into the cryo-tube to generate and maintain the operating temperature and to freeze the water droplets, and by using the nitrogen gas formed when the liquid nitrogen is injected to support the transport of the abrasive and to cool the contaminant to be removed.

[0037] In subsequent experiments, the inventor discovered that the challenge of producing a water-based abrasive with varying particle sizes in a single operation could be surprisingly solved by spraying the water in small droplet form from below into the cold atmosphere of a cryo-tube connected to a loading unit, using one or more identical or different heated nozzles with varying spray angles. The cold atmosphere is generated by injecting and expanding liquid nitrogen from several identical nozzles distributed around the surface of the cryo-tube. The arrangement of the water and nitrogen nozzles creates a vortex flow within the cryo-tube, which promotes the collision of rising, partially frozen water droplets with falling, frozen water droplets, thereby influencing the size and shape of the water-ice particles.

[0038] Due to the high temperature difference, a thin layer of ice forms immediately, which, depending on its thickness, either bursts upon collision, creating angular fragments, or another film of water forms on the already frozen drops, thus forming another layer of ice.

[0039] It was further discovered that ice formation depends essentially on the freezing time and the temperature difference. The freezing time is the sum of the time during which the water droplets are in direct contact with the sprayed nitrogen droplets, which thereby transition into the gaseous state by absorbing heat from the water droplets, and the time during which the water droplets can move in a cold atmosphere, absorbing heat from the surrounding colder nitrogen gas.

[0040] If, on the other hand, the water is sprayed from below at a specific angle to the vertical, the resulting motion is upward and decreasing in speed, reversing at the turning point into a downward motion starting from zero, and thus in the opposite direction. Because the water droplets travel twice the distance and their speeds are slower, the size of the cryo-tube can be reduced.

[0041] Experiments have shown that there is a point in time after which the layer of ice surrounding each water droplet is so stable that it no longer breaks upon contact with other drops or with the inner wall of the cryo-tube, or that no layer of ice forms on the inner wall.

[0042] The experiments further showed that while the energy balance can theoretically be determined by considering the mass of the cryo-tube, the amount of water introduced, and the losses on the one hand, and the amount of liquid nitrogen to be introduced on the other, this calculation was based on the assumption that water and nitrogen droplets are the same size and that each water droplet collides with one nitrogen droplet. Practical experience has not confirmed this assumption.

[0043] Even the subsequent separate supply of nitrogen for cooling to operating temperature and for freezing the water droplets did not produce a satisfactory result.

[0044] To reliably obtain solid, radiopaque water ice, the nitrogen supply must be increased during the freezing phase. Increasing the nitrogen supply inevitably leads to a pressure increase and gas formation in the cryogenic tube.

[0045] The experiments revealed a correlation between the pressure inside the cryo-tube and the water spray pressure. It is generally known that the spray pressure must always be higher than the internal pressure. The spray nozzle opening angle specified by the manufacturer applies only to spraying against normal atmospheric pressure. If the internal pressure increases, the differential pressure decreases, the spray pattern narrows, and the opening angle narrows.

[0046] Further experiments revealed that the increased pressure in the cryogenic tube could be reduced or avoided if the blasting media could be fed directly from the cryogenic tube to the blasting gun without intermediate storage. This finding was practically implemented by the inventive solution of connecting the loading unit directly to the cryogenic tube and utilizing the excess gas for transporting the produced ice water. This solution also has the advantage that the ice water remains in the cold nitrogen atmosphere until it is introduced into the transport gas stream, where it is further cooled. Furthermore, the remaining liquid nitrogen vaporizes upon contact with the transport gas stream, thus increasing the pressure and reducing the temperature of the transport gas stream.

[0047] The experiments conducted have clearly demonstrated a complex relationship between the amount of water to be introduced, corresponding to the required amount of ice, and its pressure, the temperature inside the cryo-tube, the internal pressure building up in the cryo-tube, and the amount of nitrogen to be introduced. This complex relationship necessitates setting priorities that differ between the cooling and freezing phases.

[0048] Temperature is crucial during the cooling phase and during production interruptions. The entire system, comprising the interior of the cryogenic tube and the interior of the loading unit, forms a closed system in which a constant, limited pressure can be maintained. Liquid nitrogen is supplied intermittently from several laterally positioned nitrogen nozzles to cool and maintain the walls and interior of the cryogenic tube and the loading unit at the specified operating temperature. Once a predetermined pressure is reached, the nitrogen supply is interrupted until the nominal pressure has stabilized. This process is repeated until the operating temperature is reached.

[0049] Once the operating temperature is reached, a stable pressure is established in the closed system. This allows the production of the specified quantity of cryogenic ice to begin.

[0050] With the start of the ice pop production, the previously closed system of the interior of the cryo-tube and the interior of the injector is opened by opening a quiescent valve, thus relieving the building-up overpressure in the cryo-tube.

[0051] A further development of the solution according to the invention provides for significantly increasing the amount of nitrogen to be introduced into the cryo-tube and using the resulting excess gas either alone as a transport gas while simultaneously further cooling the water ice particles or supporting the transport gas flow.

[0052] Another solution according to the invention provides to reduce the oxygen content of the transport gas stream and / or the jet gas stream by means of appropriate devices to such an extent that, alone or in combination with the excess nitrogen, no ignitable mixture can be formed during cleaning in the explosion area.

[0053] These findings led to the development of a small, transportable device for the simultaneous production and use of a solid, cryogenically frozen water abrasive. This device is characterized by a cryo-tube with an attached loading unit and the enclosed space between them being cooled to operating temperature by spraying liquid nitrogen. Once operating temperature is reached, water is introduced from below through one or more nozzles of varying geometries and flow rates with adjustable parameters for spray pressure and quantity. Simultaneously, liquid nitrogen, in a quantity exceeding that required to freeze the introduced water, is additionally injected. When a predetermined pressure is reached in the enclosed space, a valve is opened, thus reducing the pressure while simultaneously transporting the produced ice to the blasting nozzle.

[0054] Heated spray nozzles introduce water as small droplets at an adjustable differential pressure, depending on the chosen nozzle shape. This ensures that the water droplets traverse the height of the cryo-tube twice at different speeds.

[0055] The simultaneous upward and downward movement of water droplets, partially frozen water droplets, and water ice particles leads to collisions between the individual water droplets, causing the partially frozen water droplets to burst and the water to adhere to other partially frozen water droplets, forming one or more further layers of ice, and the fragments of the ice shell support the formation of a partially angular and multi-layered cryogenic water ice blasting medium.

[0056] The main advantage of the invention is that a device is available with which a cryogenic blasting medium can be produced from water in varying quantities, and that the blasting medium can be processed immediately after production, without storage and transport.

[0057] Another significant advantage of the invention is that the service provider has access to a device with which he can execute orders at short notice, without a long lead time, and produce the blasting media himself in the required quantity.

[0058] Another significant advantage of the invention is that a device is available which selectively produces an aggressive yet gentle solid blasting medium that combines cryogenic and mechanical properties in a single operation and which can be irradiated simultaneously without intermediate storage.

[0059] Another significant advantage of the invention is that the particle size, shape and structure can be determined during manufacturing by combining different spray nozzles and spray parameters.

[0060] Another significant advantage of the invention is that the size and design of the equipment required for the manufacture and processing of the blasting medium is reduced by the double path of the water droplets or water ice particles, and can therefore be made portable.

[0061] Another significant advantage of the invention is that a gentle and low-residue blasting medium can be produced, which has the essential advantages of CO2 blasting, but is more aggressive and climate-neutral.

[0062] Another significant advantage of the invention is that a device is available which enables automated cleaning of components exposed to high thermal or mechanical stress without "hammering over" any existing microcracks or without scratching the surfaces and the scratches being interpreted as defects.

[0063] Another advantage is that the double cooling, with separate cooling for the cryo-tube and additional cooling for freezing the water droplets, allows for a lower temperature in the cryo-tube and thus a greater temperature difference.

[0064] Another advantage is that during the production of the ice pops, the water spray pressure can be regulated according to a specific program, the variable pressure parameters can be adjusted with intermittent nitrogen supply, so that the pressure difference is kept constant.

[0065] It is also advantageous that the blasting medium can be built up layer by layer by adjusting the spray parameters, thereby increasing the cleaning performance due to the angular fragments created upon impact. It is also advantageous that the introduced water droplets are slowed down by the upward movement and internal pressure, thus extending the freezing time and increasing their size through ionization with subsequent water droplets or by coating with water droplets generated by the spray mist of the spray nozzle.

[0066] Another advantage is that the continuous production and provision of the blasting media makes it possible to use it in automated manufacturing processes.

[0067] A further advantage is that the water ice particles produced in the device can be manufactured in different geometric shapes, from small almost spherical particles, to angular fragments with smooth or angular surfaces, to large spherical particles, in one production process and thus adapted to the cleaning task.

[0068] Another significant advantage is that the excessive supply of liquid nitrogen creates overpressure in the cryo-tube, which can be reduced by opening a quiescent valve and simultaneously used to transport the manufactured ice water for loading the transport gas stream.

[0069] Another significant advantage of the invention is that, when using dried compressed air, the surfaces cooled down and laden with condensate during cleaning can be heated and dried after cleaning, thus enabling immediate further processing of the surface.

[0070] Another advantage is that by increasing the supply of nitrogen during the freezing phase, so much cold nitrogen gas is produced that it can be used as a transport gas stream, thus extending the freezing time.

[0071] Another advantage is that by transporting the water ice through a nitrogen stream and reducing the oxygen content of the jet air, a high-energy cleaning jet is available which prevents the formation of explosive mixtures when used in Ex areas.

[0072] Another advantage of compact manufacturing is that the blasting media does not come into contact with the ambient air from manufacturing to the blasting process.

[0073] It is also advantageous that the use of cryogenic water ice as an abrasive does not produce any waste requiring disposal.

[0074] Another advantage of the invention is that the nitrogen gas formed when liquid nitrogen is sprayed is not blown off, but can be used to support the transport gas flow and to embrittle the contaminant to be removed.

[0075] The invention will be described using an exemplary embodiment.

[0076] In Fig. Figure 1 shows the combination of cryo tube and loading unit

[0077] The device is a combination of a small cryo-tube (1) for producing cryogenic water ice and a loading unit (2) for the immediate continuous transport and processing of the produced water ice to the blast gun (3).

[0078] The small cryogenic tube (1) consists of the tube (4) with lid (5) and the cone (6) with the cylindrical outlet (7). The entire small cryogenic tube is insulated (8). Several identical or different heated spray nozzle blocks for water injection, with a spray angle of 10° to 30°, are arranged in the cone (6). These nozzle blocks are used individually or in various combinations, depending on the quantity of cryogenic ice to be produced. The spray lines of the nozzles (9) intersect in the effective area (10), which is also the inflection point where the spray velocity transitions into a falling velocity.

[0079] The nitrogen required to cool the interior of the small cryotube (1) is introduced via nitrogen nozzles (11) arranged at different heights within the tube (4). The temperature inside the small cryotube (1) is measured by several sensors (12), which calculate an average value that determines the length and number of nitrogen injection intervals and regulates the temperature inside. In the working area (10), the nitrogen introduced from the cooling nozzle (13), which is required to freeze the water droplets, comes into contact with them. The temperature established in the working area (10) is measured by the temperature sensor (14).

[0080] The loading unit (2) is attached to the cylindrical outlet (7). The loading unit (2) has an inlet port (15) for connecting the transport gas line and an outlet port (16) to which the quiescent valve (17) is attached. A connecting hose connects the quiescent valve (17) to the blast gun (3).

[0081] The compressed air line (19) coming from the dryer is connected to port (18) and reduced to the required blasting pressure by the regulator (20). The safety valve (21) is located between port (18) and the regulator (20). Downstream of the regulator (20) is a T-piece that splits the incoming compressed air into a transport gas stream (22) and a blasting gas stream (23). The blasting gas stream (23) is directed to the blasting gun (3) via the blasting valve (24). The regulator (25) for reducing the pressure in the transport gas stream and the transport valve (26) are installed in the line for the transport gas stream (22).

[0082] The water is connected to the valve (27) via the water line and divided by a distributor for the individual spray nozzles (9). Between the valve (27) and the distributor is the flow meter (28) for determining the water flow rate of the spray nozzles (8) as a function of pressure. Each line from the distributor to the spray nozzles (8) contains a pressure regulator (29) and a control valve (30). The pressure regulator (29) adjusts the water pressure for the respective spray nozzles (8) according to the nozzle geometry. A T-fitting is located upstream of each spray nozzle (8). The water line is connected to this fitting on one side, and a dry nitrogen gas line from the nitrogen cylinder (31) is connected to the other side via the valve (32).

[0083] The nitrogen required to cool the interior of the small cryo-tube (1) and to freeze the water droplets is supplied from a portable nitrogen tank (33) to the main valve (34). Downstream of the main valve (34) are the liquid nitrogen flow meter (35) and the distributor (36). The distributor (36) divides the nitrogen line into a cooling line (37) and a freezing line (38). The cooling line (37) contains the cooling valve (39), the throttle valve (40), and the nitrogen distributor from which the individual lines lead to the nitrogen nozzles (11). The freezing line (38), running from the distributor (36) to the cooling nozzle (13), contains the cooling valve (41) and a control valve (42).

[0084] A device is disclosed for producing and immediately processing a solid abrasive from water for cleaning bodies and surfaces, which is introduced at a temperature of +1 °C to +95 °C into a nitrogen atmosphere as cold as -185 °C by spraying from the lower part of the small cryo-tube and thus passes through the height of the small cryo-tube twice at different speeds and the produced cryogenic water ice is conveyed directly to the blast gun by means of a transport gas stream.

[0085] Furthermore, a device is disclosed in which the pressure of the water to be introduced is regulated depending on the internal pressure generated by the sprayed nitrogen in the small cryo tubes in such a way that the differential pressure is kept constant at the specified value.

[0086] Furthermore, a device for producing an abrasive from water is disclosed, which has two separate control sections for the supply of liquid nitrogen, one for cooling and maintaining the temperature in the small cryogenic tube and another for freezing the introduced water, which complement each other in their effect; wherein the amount of nitrogen required for freezing the introduced water can be increased in order to support the transport of the cryogenic water ice from the small cryogenic tube to the loading unit and in the transport gas stream to the blast gun.

[0087] A further variant of the device is revealed in which the amount of nitrogen required for freezing the introduced quantity of water is increased so that the additional nitrogen gas produced replaces the transport gas flow and at the same time extends the freezing time.

[0088] A device is disclosed that dries and reheats surfaces that have been cooled and / or covered with condensation by cleaning with cryogenic ice water, thus enabling its use in production chains.

[0089] A device for the simultaneous production and processing of cryogenic water ice is disclosed, in which the manufactured cryogenic water ice is conveyed directly into the jet gas stream using the excess nitrogen gas, thereby further cooling the water ice and, together with the energetically higher transport gas stream, is blown through the appropriate jet nozzles selected for the application onto the surface to be cleaned.

[0090] Furthermore, a spray nozzle system, which can be heated depending on the temperature in the cryo-tube and can be alternately sprayed with water or nitrogen gas, is revealed. Immediately after the water spraying is complete, the nozzle is blown empty with a short pulse of dry nitrogen gas to prevent the residual water from freezing.

[0091] The preceding description has made clear numerous advantages of the present invention. Among them, the following are particularly noteworthy: Portable device for the production of cryogenic ice particles of different shapes, sizes, and quantities according to a predetermined program dependent on the cleaning task, and immediate processing of the produced ice particles.

[0092] The device is immediately ready for use, as the cryogenic water ice used as an abrasive can be produced immediately before use, thus eliminating ordering and delivery times as well as transport costs.

[0093] Production of a residue-free, aggressive, yet surface-friendly and environmentally friendly cleaning agent.

[0094] Uniform production of the cryogenic water ice, despite pressure fluctuations in the cryo-tube due to uneven nitrogen supply, is achieved through a control variant that keeps the differential pressure between internal pressure and spray pressure constant, thus ensuring a consistent spray angle.

[0095] Adjustable and separate nitrogen supply for generating a cold gas atmosphere in the cryo-tube and for freezing the water particles, whereby, in order to maintain a safe energy balance, the amount of nitrogen to be introduced for freezing the water particles is determined by the amount of water introduced at the same time.

[0096] It has become clear that the present invention provides a device that can produce cryogenic water ice particles in a novel way from water with variable cooling speed and thus with different hardness and in different sizes and layers, by extending the cooling time through opposing directions of movement of the water particles as well as through deliberate collision of the water ice particles with different ice layers.

[0097] A device is available that can produce an abrasive material which combines the advantageous mechanical effect of solid and hard water ice with the thermal advantages of temperatures down to -180 °C.

[0098] It has also proven advantageous that the nitrogen gas formed by the expansion and heating of liquid nitrogen can be used for transporting the abrasive material and for cooling the contaminant.

[0099] It has proven particularly advantageous that the device according to the invention makes it possible to clean large components in their installed state without the need for time-consuming installation and removal, since no solid components are left behind.

[0100] The multi-layered structure of the blasting medium made of solidified water according to the present invention has also proven to be very advantageous, since its special fracture behavior makes it possible to clean successive levels using the billiard effect, for example in jet engines.

[0101] A further advantage of the device is that the production of the blasting media can be adapted and automated to the requirements of the cleaning process by means of a water supply that can be regulated in quantity and by means of interval-based production. Designations 1 small cryo tube 2 loading units 3 blasting guns 4 tubes 5 lids 6 cone 7 Outlet 8 Insulation 9 spray nozzle 10 Area of ​​influence 11 Nitrogen nozzle 12 Sensor 13 Cold nozzle 14 Temperature sensor 15 entrance tubes 16 outlet nozzles 17 Resting valve 18 connection 19 Compressed air line 20 regulators 21 Safety valve 22 Transport gas flow 23 Jet gas stream 24 jet valve 25 regulators 26 Transport valve 27 valve 28 flow meters 29 pressure regulators 30 working valve 31 nitrogen cylinders 32 valve 33 Nitrogen tank 34 Main valve 35 flow meters 36 distributor hhhh6 37 Cooling line 38 Freezing line 39 Cooling valve 40 Throttle valve 41 Refrigeration valve 42 Control valve QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 2003 101667 A1

[0005] DE 103 09 191 A1

[0006] DE 100 10 012 A1

[0006] DE 201 15 013 U1

[0006] DE 100 36 557 A1 [0007, 0023] US 53 67 838

[0008] DE 35 05 675 A1

[0009] DE 34 34 163 A1

[0010] US 5 785 581

[0011] WO 2015 / 074765 A1

[0012] DE 10 2020 000018 A1

[0013] DE 10 2019 109 860 A1

[0014] US 4 974 375 [0015, 0025] DE 20 2016 101 965 U1

[0017] WO 94 / 16861

[0018] DE 40 30 434 A1

[0019] DE 103 60 011 A1

[0020] DE 10 2023 003 658 A1

[0021] DE 102015209994 A1

[0023] DE 689 14 657 T2

[0025]

Claims

Device for producing a solid cryogenic abrasive from water, characterized in that the cryo-tube and loading unit form a single unit, wherein one or more spray nozzle blocks, equipped with identical or different interchangeable spray nozzles, are arranged in the cone of the cryo-tube such that the water can be sprayed from below into a cold nitrogen atmosphere of the cryo-tube, and the amount of nitrogen required for ice formation can be introduced from nitrogen nozzles attached to the tube and the lid, and the frozen water droplets immediately fall from the cryo-tube into the loading unit for absorption into the transport gas stream, assisted by the gas pressure generated during freezing. The device according to claim 1 is characterized in that the work process is divided into two phases that alternate irregularly, wherein in the cooling and holding phase the idle valve is closed and the internal pressure and temperature are kept constant at a predetermined value, and in the manufacturing phase the idle valve is open for the transport of the abrasive material and for the reduction of the irregularly occurring pressure peaks. Device according to claim 1, characterized in that the water is introduced from several identical or different nozzles, which are used individually or in variable combinations, with a nozzle-dependent adjustable spray pressure, depending on the currently required quantity of deep-cold water ice particles, such that all reach the same spray height. Device according to claim 3, characterized in that the irregular pressure fluctuations in the interior are compensated for by correcting the spray pressure so that the differential pressure remains constant. Device according to one of the preceding claims, characterized in that the amount of nitrogen to be introduced during the freezing process is increased so that the cryogenic water ice particles pass directly through their own weight and supported by the nitrogen gas produced, through the open cylindrical outlet of the cry tube into the injector of the loading unit in order to be picked up by the transport gas stream and transported to the blast gun. Device according to one of the preceding claims characterized in that the amount of nitrogen to be introduced during the freezing process is increased to such an extent that the amount of nitrogen gas formed can be used for the transport of the manufactured cryogenic water ice and thus the freezing time is extended,

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