| Method and apparatus for providing bubble-free liquid carbon dioxide -> Monitor Keywords |
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Method and apparatus for providing bubble-free liquid carbon dioxideRelated Patent Categories: Refrigeration, Cryogenic Treatment Of Gas Or Gas Mixture, LiquefactionMethod and apparatus for providing bubble-free liquid carbon dioxide description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070028648, Method and apparatus for providing bubble-free liquid carbon dioxide. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] This application claims the priority of German Patent Document No. 10 2005 035 432.7, filed Jul. 28, 2005, the disclosure of which is expressly incorporated by reference herein. BACKGROUND AND SUMMARY OF THE INVENTION [0002] The invention relates to a method and to a device for providing bubble-free liquid carbon dioxide. [0003] While it is sometimes desirable to draw fluids with bubbles from a tank (beer, whipped cream), it is frequently desirable to provide the fluid bubble-free at the removal site or at the user's location. For example, when dosing or metering, it is important to keep the fluid pure in its liquid phase. The bubble-free drawing of gasoline allows exact metering. Likewise, when milk or other foaming foodstuffs are filled, care must be taken at all times that the desired filling amount is in fact put in the container. Inasmuch as, in most cases, dispensing is connected with a reduction in pressure, the risk of bubble formation increases as the liquid-gas phase boundary is approached. [0004] Problems are posed by liquefied and/or cooled gases that, under normal conditions, always occur only in gaseous state. If, in addition, abnormal situations--as is the case with carbon dioxide, which, besides being known in the standard aggregate states of gas, liquid and solid, can exist in the states of super-critical and snow-shaped--are considered, there is currently no supply system that permits the reliable supply of only bubble-free liquid CO.sub.2 at all times. Currently known supply systems consisting of a liquid CO.sub.2 tank, a removal line for the liquid CO.sub.2 and a valve upstream of the user, indeed supply liquid CO.sub.2 but, when the stop valves are frequently opened and closed, a certain relaxation or warming upstream of the valve result in gas bubbles that could disrupt the operation by the user or the metering operation. In particular, considering expansion nozzles for the production of carbon dioxide snow or for cooling, liquid CO.sub.2 should at all times be bubble-free upstream of the nozzle. [0005] It has already been suggested (German Patent Application No. 10 2004 043912) to remove liquid CO.sub.2 from a tank, to slightly heat the CO.sub.2, cool it again and transport it in liquid state to the user. This form of supply has the disadvantage that it does not work at high external temperatures (above the critical point of the CO.sub.2). [0006] Considering the direct removal of fluid from a CO.sub.2 bottle with a submerged pipe or from a cluster of CO.sub.2 bottles with submerged pipes in the bottles, a portion of the fluid evaporates already in the removal hose or in the removal line, thus reducing the cleaning effect. Considering removal lines carrying liquid CO.sub.2, each and every line segment that is separated by stop valves must be provided with safety valves. The gas must be safely exhausted to the outside. Large amounts of exhaust must be expected because the CO.sub.2 in the line is present as a liquid. Therefore, this type of design is relatively complex and expensive. [0007] Therefore, the object of the invention is to provide a supply device and a supply method that always provide bubble-free CO.sub.2 in a more cost-effective manner. [0008] Embodiments of the invention and devices for performing the method are disclosed herein. [0009] It is characteristic of the invention that gaseous CO.sub.2 is used to supply the user. This gas is transported through normal supply lines to the point of use. At the point of use or just before, the gaseous CO.sub.2 is liquefied or condensed in accordance with the invention by cooling in a condenser. Then, the liquefied CO.sub.2 is supplied to the user through a short feed line. As a result of the complete condensation and the subsequent sub-cooling of the CO.sub.2, large amounts of CO.sub.2 are produced during relaxation at the user end. Consequently, if the CO.sub.2 snow is used for cleaning, the cleaning effect is increased significantly. It has been found that, in this way, the supply pressure may be below the normal CO.sub.2 bottle pressure. Instead of a bottle pressure of approximately 50 bar, a line pressure of 10-30 bar is sufficient to achieve a good cleaning result. [0010] In one embodiment of the invention, the CO.sub.2 is sub-cooled in the condenser in order to avoid re-evaporation. In this case, sub-cooling may be minimal, i.e., 4-15.degree. C., to reliably avoid re-evaporation before reaching the user. [0011] The invention has the following advantages. [0012] Complex and expensive fluid lines for the CO.sub.2 supply are unnecessary. Existing CO.sub.2 line systems with a gaseous product can be used. As a result of this, the costs for the condenser unit are more than offset and potential sub-cooling just upstream of the cleaning device ensures a reliable CO.sub.2 reserve just prior to the "point of use." [0013] Safety is increased because the supply lines do not carry liquid CO.sub.2. [0014] The line between the condenser and the user should be as short as possible. Preferably, the line length is in the range between 100 and 300 cm. Also, the line may be insulated; however, this is not necessary when the flow rate is relatively high and the temperature difference is relatively minimal. [0015] The method is particularly suitable when the user is a relaxation nozzle, because now, with the supply of always liquid carbon dioxide, a controlled operation of the relaxation nozzle is possible. [0016] This is particularly advantageous when the relaxation nozzle is used for cleaning objects such as, for example, for cleaning welding nozzles such as MIG (metal inert gas) or MAG (metal active gas) burners. Splatters, particles or condensates, which need to be removed as quickly as possible in order not to seriously impair manufacturing cycle times, frequently adhere to these nozzles. Inasmuch as the cleaning process at times takes less than one second (0.5 second is recommended by the manufacturer), it is important to be able to provide the liquid phase from the start. [0017] The current state of the art is described in the article "Schweissbrenner werden beruhrungslos gereinigt [Welding Burners are Cleaned in a Contactless Manner]," in Schweissen und Schneiden 56, issue 6/2004, p. 270. Indeed, this article mentions that CO.sub.2 in ascending pipe bottles or tanks can be stored in liquid state under pressure; however, there is no description of any solution regarding how the CO.sub.2 remains a bubble-free liquid from the tank to the device. [0018] Similar methods have been known, for example, from International Publication No. WO 02/49794 A1; however, in this case the process does not use liquid CO.sub.2 but CO.sub.2 pellets and air. [0019] Another application is the cooling of powders or substrates in thermal spraying (Linde brochure "Thermal spraying-controlled cooling with CO.sub.2"). [0020] A device for performing the inventive method comprises a supply container from which gaseous CO.sub.2 is removed. By way of the supply line, the gaseous CO.sub.2 is transported to a condenser that is located just upstream of the user and that liquefies and potentially sub-cools the CO.sub.2. [0021] The distance between the condenser and the user is as small as possible. Preferably, it is at 100 to 300 cm in order to ensure the mobility of the user, without requiring that the condenser must also be moved. [0022] The CO.sub.2 may be supplied either in a CO.sub.2 bottle, by means of a cluster of CO.sub.2 bottles or by means of a CO.sub.2 tank, which contains the gas in liquid form, the gas then being brought into its gaseous phase by means of a separate evaporator. The gas can also be taken from an existing CO.sub.2 line as is already available in many welding businesses. Considering all storage options, a pressure controller may be provided between the storage container and the supply line, should this be desirable. [0023] Any common liquefier for CO.sub.2 can be used as the condenser. Preferred is a condenser with an electrically operated refrigeration unit, because electrical current is available at virtually any workplace. Continue reading about Method and apparatus for providing bubble-free liquid carbon dioxide... Full patent description for Method and apparatus for providing bubble-free liquid carbon dioxide Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Method and apparatus for providing bubble-free liquid carbon dioxide patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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