EP1814820A2 - Procede et dispositif pour produire des particules solides a partir de liquides, notamment de dioxyde de carbone liquide - Google Patents

Procede et dispositif pour produire des particules solides a partir de liquides, notamment de dioxyde de carbone liquide

Info

Publication number
EP1814820A2
EP1814820A2 EP05815724A EP05815724A EP1814820A2 EP 1814820 A2 EP1814820 A2 EP 1814820A2 EP 05815724 A EP05815724 A EP 05815724A EP 05815724 A EP05815724 A EP 05815724A EP 1814820 A2 EP1814820 A2 EP 1814820A2
Authority
EP
European Patent Office
Prior art keywords
liquid
solid particles
carbon dioxide
gas stream
container
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP05815724A
Other languages
German (de)
English (en)
Inventor
Hans Quack
David Kirsten
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Technische Universitaet Dresden
Original Assignee
Technische Universitaet Dresden
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Technische Universitaet Dresden filed Critical Technische Universitaet Dresden
Publication of EP1814820A2 publication Critical patent/EP1814820A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
    • B01J2/02—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops
    • B01J2/04—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops in a gaseous medium
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/50—Carbon dioxide
    • C01B32/55—Solidifying

Definitions

  • the invention relates to a method and an apparatus for producing solid particles from liquids.
  • the invention relates to a method and apparatus for producing carbon dioxide particles from liquid carbon dioxide.
  • carbon dioxide particles are blasting methods for abrasive surface treatment to call.
  • Carbon dioxide is particularly suitable for the production of solid particles of liquid carbon dioxide.
  • the carbon dioxide differs from most other substances in that its triple point pressure is higher than 1 bar (0.1 Mpa), namely 5.2 bar.
  • the associated triple point temperature is - 56 0 C.
  • At atmospheric pressure carbon dioxide is thus only in solid and in gaseous, but not in liquid form.
  • the associated saturation temperature at 1 bar is about minus 80 0 C.
  • the boiling pressure is about 58 bar.
  • thermodynamic properties of the carbon dioxide allow a relatively simple production of solid particles of liquid carbon dioxide.
  • the gas is stored and transported in pressure tanks or larger pressure tanks in which the liquid is in equilibrium with steam at 58 bar. Removing liquid carbon dioxide from such a storage tank and throttling it to atmospheric pressure, creates much vapor during the throttling process in the liquid and tears the liquid into very small droplets. After passing through the triple point pressure, these droplets transform into tiny ice crystals. The resulting fine crystalline product looks like snow and is also called dry ice designated. In order to be able to use dry ice for the abrasive blast treatment of surfaces, a special type of further treatment of the dry ice is required. This consists in the compression and subsequent extrusion.
  • the end product is carbon dioxide snow pellets, hereafter referred to as pellets.
  • the pellets have a diameter of 2 to 5 millimeters and are transported and stored in insulated containers of 200 to 700 kilograms.
  • FIG. 1 A known process for the preparation of the dry ice pellets is shown in Fig. 1 by means of a conventional device. This is the liquid
  • Precooling heat exchanger 3 is passed to the throttle valve 4, where it is relaxed and is introduced via spray nozzles 6 in the container 5 in drop form.
  • Particle generation takes place in the particle-generating zone / freezer compartment 7 of the container 5.
  • the resulting dry ice snow or the solid particles 8 accumulate in the lower part due to gravity and are over a
  • Transport container 10 stored or used directly without intermediate storage for dry ice blasting using a propulsion jet.
  • the pellets are usually introduced in compressed air.
  • the mixture is expanded in a nozzle to atmospheric pressure and thereby accelerated to a high speed.
  • the pellets transfer a locally high impact energy and, in addition, by their sublimation, cause a local strong decrease in temperature, whereby the contamination becomes brittle and can be easily removed mechanically.
  • One advantage of dry ice blasting is that the carbon dioxide goes into the vapor state and thus disappears. There are no., Blasting agent residues that would have to be disposed of.
  • DE 37 20 992 C2 discloses a method for cleaning radioactively contaminated workpiece surfaces and a system for carrying out the method, wherein CO 2 ice particles are directed by means of a propulsion jet against a workpiece surface and the CO 2 ice particles are formed by liquid CO 2 with liquid air or liquid nitrogen is cooled below the solidification point, so that in the liquid CO 2 crystal formation begins.
  • the object of the present invention is to provide a method and a device in which solid particles of liquids can be produced in a simpler manner and that the resulting particles have better properties for the blasting of surfaces.
  • the invention is achieved by a method for producing solid particles from liquids, comprising the following steps: a) the liquid is removed from a storage container and b) cooled to the triple point temperature and throttled to the desired freezing pressure and then c) drops from the Liquid generated and these d) introduced into a gas stream, which consists at least in part of the substance of the liquid, whereby e) freeze the drops to solid particles by a partial evaporation of the liquid droplets, after which the solid particles f) are then collected and discharged.
  • the concept of the invention is that not snow-like smallest crystals are produced and then compressed, but that drops of the desired size are generated and frozen. This process occurs at a pressure that is in the order of magnitude of the triple point pressure. Essential to the invention is that needed for freezing the drops
  • Cold is generated by partial evaporation of a portion of the droplet or the already formed solid carbon dioxide.
  • the solid particles produced can be supplied for immediate use in a blasting device, whereby the pressure reduction to ambient pressure is eliminated.
  • the method is energetically efficient and that a blasting agent with special, previously unavailable properties can be generated. Furthermore, it is possible by the method to obtain a very high yield of solid particles from a given initial amount of liquid, with as little gas as possible, which is ultimately difficult to recover materially and energetically.
  • a further advantageous embodiment of the invention is that in step b) is throttled in two stages, wherein the liquid is separated after the first throttling of the resulting vapor and then throttled again.
  • the resulting vapor is used for pre-cooling the liquid.
  • a preferred field of application of the method according to the invention is the production of carbon dioxide grains from liquid carbon dioxide.
  • this method is also advantageous for the production of methane grains, which are needed for example as a neutron brake in cold neutron sources.
  • the gas stream used in this case is helium, hydrogen, neon or pure nitrogen.
  • Another field of application is the production of hydrogen grains, which are required for the production of a hydrogen-solid-liquid-mixture ("slush-hydrogen"), in which case helium is used as the gas stream.
  • the object of the invention is further achieved by a device for the production of solid particles from liquids, wherein a storage tank for the Liquid, a withdrawal line, a throttle valve and a container with spray nozzles and means for generating a gas stream are provided such that liquid droplets in free fall evaporate a portion of their mass into the gas stream and thereby freeze to solid particles and that the container a lock for pressure holding Delivery of the solid particles is provided.
  • the device according to the invention is preferably configured by providing a precooling heat exchanger and a separator / collector for the liquid-gas mixture produced after throttling.
  • a means for generating a pre-cooled gas stream is a compressor, a dryer and a heat exchanger, wherein a distributor and a collector for the gas stream are arranged in the container.
  • the object of the invention to produce harder particles is achieved in that solid particles in the form of frozen grains can be produced by the method according to the invention.
  • FIG. 1 state of the art of pellet production of dry ice
  • FIG. 2 flow diagram for the production according to the invention of solid particles from liquids
  • FIG. 3 shows a flow chart for the production according to the invention of solid particles with direct use of the particles for the abrasive blast treatment of surfaces
  • Fig. 4 Flowchart for the efficient design of the pre-cooling and relaxation of the liquid by use of an Expander- Komp_res_sors "and Fig. 5: Fiiefibild for two-stage throttling and recompression with condensation to improve the process in the pre-cooling and throttle stage.
  • a storage tank 1 for example, liquid carbon dioxide is shown, from which the liquid carbon dioxide is passed via a withdrawal line 2 and a Vorkühlskaschreibtrager 3 to the throttle valve 4.
  • the throttle valve 4 In the throttle valve 4 there is a relaxation of the liquid.
  • the liquid, vapor mixture then passes into the separator / collector 14.
  • the steam produced in the separator / collector 14 leaves the system after it has cooled the liquid CO 2 in the pre-cooling heat exchanger 3.
  • a pressure-holding valve 15 is provided.
  • the liquid expanded carbon dioxide now passes to the container 5 and is introduced into the container 5 via droplets 6 provided there in the form of droplets.
  • the droplets fall down through the freezing zone 7 of the container 5.
  • a gas stream which is introduced via a distributor 19 into the container 5, in which a part of each carbon dioxide droplet evaporates in the freezing zone 7, whereby the cooling and solidification of the remaining droplet takes place.
  • the carbon dioxide-enriched gas mixture is taken up by the collector 20 and passed to the heat exchanger 18. There, the carbon dioxide-enriched cold gas mixture is used for precooling the container 5 to be supplied gas stream.
  • the heated gas-CO 2 mixture leaves the system via a pressure-maintaining valve 15.
  • the gas stream itself is generated by means of a compressor 16 and processed in a dryer 17 before it is pre-cooled in the heat exchanger 18 and introduced into the manifold 19 in the container 5.
  • the diagram shows the use of air as gas into which the carbon dioxide evaporates.
  • the frozen grains or solid particles 8 collect in the lower part of the container 5 and are pressure-maintaining via a lock 9, for example, in an insulated transport container 10, introduced.
  • a further advantageous embodiment of the invention is shown, in which the solid particles 8 produced are fed directly to a jet nozzle 22.
  • the propellant used is, for example, the carbon dioxide gas deposited in the separator / collector 14 - for example in conjunction with air which, after compression in the compressor 16 and drying in the dryer 17, are used as carrier gas for the solid particles 8.
  • FIG. 1 Such an increase in the efficiency of precooling and throttling is shown, for example, in FIG.
  • extracts the extraction line 2 is shown for the liquid carbon dioxide, to which an expander 23 connects.
  • the liquid carbon dioxide is working expanded and in the separator / collector 14 a, the vapor, liquid mixture is separated.
  • the gaseous fraction is withdrawn at the top end and compressed in a compressor 25, the compressor 25 being at least partially driven by the working-up of the liquid carbon dioxide.
  • the condensed To supply carbon dioxide to an intercooler 24, after which the recooled and liquefied, high pressure carbon dioxide is fed back into the extraction line 2 before the first expansion stage.
  • the liquid part of the carbon dioxide passes from the first separator / collector 14a in a second expansion stage, in turn, a work expander 23 is used.
  • the expanded liquid then passes into the second separator / collector 14b, which has a pressure-holding valve 15, after which the liquid CO 2 is then sprayed into the container 5 with the spray nozzles 6 for generating drops.
  • a two-stage throttling makes sense, so that a part of the resulting vapor is present at a higher pressure and thus has more driving force when using the steam in the jet nozzle 22 according to FIG. 3. It can be used in the way three propellant streams, on the one hand carbon dioxide from triple point pressure, the second carbon dioxide from the medium pressure and third compressed air.
  • FIG. 5 Another alternative advantageous embodiment of the pre-cooling and throttling is shown in Fig. 5 as a flow chart.
  • the drying of the air as a gas stream is useful because otherwise water in the heat exchanger 18 freezes and clogged.
  • Freezing zone 7 of the pressure vessel 5 is introduced, comes alternatively or cumulatively from the gas / carbon dioxide mixture, which evaporates in the
  • Particle production / freezing zone 7 is formed and leaves the system via the collector 20 and a heat exchanger 18 and a pressure-maintaining valve 15, provided that the CO 2 is not supplied for reuse.
  • the gas-carbon dioxide mixture produced during the evaporation process can alternatively also be used to assist the cooling of the starting liquid and, in the direct use of the solid particles in a blasting unit, the heated gas mixture can subsequently be used as propellant gas in the blasting nozzle 22.
  • the evaporation freezing process is characterized in that the precooled and throttled carbon dioxide is sprayed directly or after intermediate storage in a separator / collector 14 in drop form into the gas stream of, for example, air. Contact with the gas stream causes part of the liquid to evaporate on the surface. This cools the
  • Evaporation is not associated with the formation of ice on the surface but it continues to evaporate from already frozen solid carbon dioxide until all the liquid is frozen.
  • This method of evaporative freezing is characterized in that the heat transfer takes place by evaporation, wherein the temperature difference between the droplet and gas flow is irrelevant.
  • the drop generation can be realized in various ways.
  • Known devices for producing drops are rotary plates, perforated baskets, spray nozzles, spray tubes and perforated plates. So that the formation of the droplets is not already superimposed and influenced by the onset of freezing, a carbon dioxide atmosphere as pure as possible should be present in this area directly around the droplet formation point.
  • the freezing of the grains takes a certain amount of time. This time is the longer, the larger the original drop and the lower the amount of gas flow, that is, the greater the partial pressure of the carbon dioxide in the gas mixture.
  • the required height of the pressure vessel 5 results from the required freezing time and the falling speed of the drops.
  • internals are preferably arranged in the container 5, which prevent the drops or the already formed grains from falling free. However, it is necessary to prevent the remaining liquid in or on the grains from wetting the internals, since otherwise the internals are surrounded by an ice layer, which over time adds the container 5. Wetting is prevented by the surface of the internals is formed poorly wettable.
  • Another advantageous possibility is to design a part of the surface of a gas-permeable material, for example a sintered material, via which at least part of the gas flow enters the pressure vessel 5.
  • the inventive method is advantageously designed particularly efficient when the carbon dioxide is recovered from this mixture by the mixture is compressed and then cooled. Part of the carbon dioxide condenses, depending on pressure and temperature, after compression and cooling. The more carbon dioxide you can recover the less air that evaporates.
  • advantageously designed is a process in which the evaporation takes place with a mixture of, for example, 10% air and 90% carbon dioxide.
  • methane grains are produced as solid particles by the process according to the invention.
  • gases such as helium, hydrogen, neon or pure nitrogen are used.
  • hydrogen atoms are produced as solid particles by the process according to the invention.
  • the gas helium is used as the gas stream into which parts of the liquid droplets evaporate.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Carbon And Carbon Compounds (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

L'invention concerne un procédé servant à produire des particules solides à partir de liquides et comprenant les étapes suivantes : a) le liquide est prélevé d'un contenant de stockage, b) est refroidi à la température de point triple et est étranglé à la pression de congélation désirée, puis c) des gouttes sont produites à partir du liquide et d) sont introduites dans un courant gazeux qui, au moins en partie, n'est pas constitué de la substance du liquide. Puis, e) les gouttes gèlent en particules solides par évaporation partielle des gouttes de liquide, f) les particules solides étant ensuite collectées et évacuées. L'invention concerne également un dispositif servant à exécuter ce procédé.
EP05815724A 2004-10-29 2005-10-27 Procede et dispositif pour produire des particules solides a partir de liquides, notamment de dioxyde de carbone liquide Withdrawn EP1814820A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102004053239A DE102004053239A1 (de) 2004-10-29 2004-10-29 Verfahren und Vorrichtung zur Erzeugung von festen Partikeln aus Flüssigkeiten, insbesondere aus flüssigem Kohlendioxid
PCT/DE2005/001979 WO2006045305A2 (fr) 2004-10-29 2005-10-27 Procede et dispositif pour produire des particules solides a partir de liquides, notamment de dioxyde de carbone liquide

Publications (1)

Publication Number Publication Date
EP1814820A2 true EP1814820A2 (fr) 2007-08-08

Family

ID=36165402

Family Applications (1)

Application Number Title Priority Date Filing Date
EP05815724A Withdrawn EP1814820A2 (fr) 2004-10-29 2005-10-27 Procede et dispositif pour produire des particules solides a partir de liquides, notamment de dioxyde de carbone liquide

Country Status (3)

Country Link
EP (1) EP1814820A2 (fr)
DE (1) DE102004053239A1 (fr)
WO (1) WO2006045305A2 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102009040498A1 (de) * 2009-09-08 2011-03-10 Messer Group Gmbh Verfahren und Vorrichtung zum Herstellen fester Kohlendioxid-Partikel
DE102022109526A1 (de) 2022-04-20 2023-10-26 Alfred Kärcher SE & Co. KG Reinigungsgerät

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB314371A (en) * 1928-06-26 1929-10-24 Midden Europ Octrooimij Nv A method of, and apparatus for, producing dense carbon dioxide snow from liquid carbon dioxide
US2608838A (en) * 1949-06-30 1952-09-02 Standard Oil Dev Co Dry ice manufacture
DE102004011194A1 (de) * 2004-03-04 2005-09-22 Messer Austria Gmbh Verfahren und Vorrichtung zur Erzeugung fester Kohlendioxidpartikel

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2006045305A2 *

Also Published As

Publication number Publication date
WO2006045305A3 (fr) 2006-07-06
WO2006045305A2 (fr) 2006-05-04
DE102004053239A1 (de) 2006-05-04

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