DE-202025003887-U1 - 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.

Assignees

• V D OHE JUERGEN

Dates

Publication Date

20260513

Application Date

20251007

Priority Date

20251007

Claims (6)

1. 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.
2. Device according to Claim 1 characterized in that the work process is divided into two phases that alternate irregularly, wherein in the cooling and holding phase the rest valve is closed and the internal pressure and temperature are kept constant at a predetermined value, while in the production phase the rest valve is open for the transport of the abrasive material and the reduction of the irregularly occurring pressure peaks
3. Device according to Claim 1 characterized in that the water is introduced from several identical or different nozzles, individually or in variable combinations, with a nozzle-dependent adjustable spray pressure, depending on the currently required quantity of deep-cold ice water particles, so that all reach the same spray height.
4. 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,
5. 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.
6. 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.

Description

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. 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. The primary material 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. 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. Out of 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, leading to the removal of the contaminant (cryogenic effect). However, a disadvantage of cleaning with CO₂ as a blasting medium is its low abrasive effect. This low abrasiveness limits its range of applications. Out of DE 103 09 191 A1 A device for dry ice blasting using a mixture of compressed air and dry ice for cleaning surfaces is known. 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. DE 100 10 012 A1 and DE 201 15 013 U1 CO₂ pellets are added to the compressed air stream, and to increase abrasiveness, another blasting medium that is solid at room temperature is added. However, a disadvantage of this method is that some of the added solid blasting medium remains in the system, and dust generation cannot be avoided. The DE 100 36 557 A1 This 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 dosing unit. In US 53 67 838 A device is described in which water ice at a temperature of approximately -30 °C is blown onto the contaminated surface for cleaning purposes using compressed air. The low hardness of the ice and the formation of condensate due to the moisture in the blasted air have proven to be disadvantages, leading to a reduction in cleaning performance. The DE 35 05 675 A1 This describes a process 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 process is that no cryogenic effect occurs; only mechanical ablation is observed, and even that is minimal. In the 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. In US 5,785,581 A system is described in which a cryogenic liquid, preferably liquid nitrogen, is used as a coolant to generate ice particles. In this process, water droplets are introduced under pressure into a freezing tube within a cold gas stream, converted into ice, and then blown from the nozzle onto the surface to be cleaned using the pressure difference. Here, too, only a slight mechanical effect is observed, as the ice temperature is limited by the short distance in the freezing tube, only at about -25 °C. In WO 2015/074765 A1 Various methods for producing water ice are described. 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 aims to simultaneously create a cold gas atmosphere and