SE503419C2

SE503419C2 - Methods and apparatus for continuous venting of particulate free liquid

Info

Publication number: SE503419C2
Application number: SE9402435A
Authority: SE
Inventors: Ebbe Larsson
Original assignee: Tetra Laval Holdings & Finance
Priority date: 1994-07-11
Filing date: 1994-07-11
Publication date: 1996-06-10
Also published as: AU2995595A; SE9402435D0; WO1996001789A1; SE9402435L

Abstract

Particle free liquid as water is continuously deaerated in a vacuum vessel. The liquid is divided into thin films in the upper part of the vacuum vessel over a packing material which completely fills the cross section of the vessel to the largest part of its extension vertically. The formed liquid films are diverted and reformed during the passage through the packing material in such a way that there is available an incessantly newly shaped exposure area towards the surrounding vapour space in the vessel during a necessary contact time. The deaerated liquid is withdrawn from the lower part of the vessel. The vessel is during the deaeration keept at or close to absolute vacuum.

Description

503 419 10 15 20 25 30 De vid fördelningen bildade vätskefilmerna omlänkas och omformas under passagen genom packmaterialet så att ständigt nyformad kontaktyta mot omgivande atmosfär i kärlet föreligger under en erforderlig kontakttid. Avluftad vätska uttas vid kärlets nedre del. Under avluftningen hålles kärlet vid eller i närheten av absolut vakuum. The liquid films formed during the distribution are deflected and reshaped during the passage through the packing material so that a constantly newly formed contact surface with the surrounding atmosphere in the vessel is present during a required contact time. Deaerated liquid is taken out at the lower part of the vessel. During venting, the vessel is kept at or near absolute vacuum.

Sättet enligt uppfinningen genomföres med fördel så att vätskans temperatur understiger l5°C. Om vätskans tempera- tur är högre kan avluftningen naturligtvis genomföras vid denna temperatur, men enligt uppfinningen kan en effektiv avluftning erhållas även vid så relativt låg temperatur som under l5°C. Denna temperatur 10-l5°C motsvarar ofta den temperatur som t.ex. vatten har när det tappas från någon vattentäkt.The process according to the invention is advantageously carried out so that the temperature of the liquid is less than 15 ° C. If the temperature of the liquid is higher, the deaeration can of course be carried out at this temperature, but according to the invention an effective deaeration can be obtained even at such a relatively low temperature as below 15 ° C. This temperature 10-155 ° C often corresponds to the temperature that e.g. water has when it is drained from any water source.

Med sättet enligt uppfinningen kan en vätska vars ingående lufthalt är 8-10 ppm efter genomförd avluftning endast ha en lufthalt av 0,5 ppm.With the method according to the invention, a liquid whose constituent air content is 8-10 ppm after completed deaeration can only have an air content of 0.5 ppm.

En anordning för avluftning av vätska på sättet enligt uppfinningen omfattar ett vakuumkärl, vilket i sin övre del har en anslutning till ett förråd av vätska och i sin undre del en anslutning för borttransport av avluftad vätska.A device for venting liquid in the method according to the invention comprises a vacuum vessel, which in its upper part has a connection to a supply of liquid and in its lower part a connection for transporting away deaerated liquid.

Vakuumkärlet har vidare en anslutning till organ som åstadkommer vakuum i kärlet. I dess övre del finns anordnat medel för att fördela vätska i kärlet och för att skapa ett antal tunna vätskefilmer. Till sin största del är kärlet fyllt med ett inert packmaterial av tunna korrugerade hàlförsedda skivor som skapar en stor kontaktyta mellan vätskan och atmosfären i kärlet.The vacuum vessel further has a connection to means which provide a vacuum in the vessel. In its upper part there are arranged means for distributing liquid in the vessel and for creating a number of thin liquid films. For the most part, the vessel is filled with an inert packing material of thin corrugated hollow discs which create a large contact surface between the liquid and the atmosphere in the vessel.

Anordningen enligt uppfinningen utformas med fördel så att kärlen har en viss höjd, vilket säkerställer en viss 10 15 20 25 30 503 419 kontakttid, medan kärlets volym (diameter) anpassas till önskad kapacitet hos avluftningsanordningen.The device according to the invention is advantageously designed so that the vessels have a certain height, which ensures a certain contact time, while the volume (diameter) of the vessel is adapted to the desired capacity of the deaeration device.

Den föreliggande uppfinningen beskrivs med hänvisning till bifogade ritning som schematiskt visar en som exempel vald utföringsform av anordningen.The present invention is described with reference to the accompanying drawing which schematically shows an exemplary embodiment of the device.

Pá ritningen visas ett vakuumkärl 1. I övre delen av kärlet finns en anslutning till en ledning för vätska 2. Vid kärlets botten finns en anslutning till en ledning 3 genom vilken avluftad vätska transporteras bort frán kärlet. I kärlets övre del finns vidare en anslutning till en vakuumpump 4 anordnad att evakuera kärlet till ett tryck i närheten av absolut vakuum. Kärlet är till huvuddelen av sin höjd fylld med ett packmaterial 5. Kärlets bottendel är avsedd att fyllas av avluftad vätska till en viss nivå. I omedelbar anslutning till packmaterialets övre avgränsning finns en fördelare som sprider vätskan över packmaterialet i form av tunna filmer.The drawing shows a vacuum vessel 1. In the upper part of the vessel there is a connection to a line for liquid 2. At the bottom of the vessel there is a connection to a line 3 through which deaerated liquid is transported away from the vessel. In the upper part of the vessel there is furthermore a connection to a vacuum pump 4 arranged to evacuate the vessel to a pressure in the vicinity of absolute vacuum. The vessel is for the most part of its height filled with a packing material 5. The bottom part of the vessel is intended to be filled with vented liquid to a certain level. In the immediate vicinity of the upper boundary of the packing material, there is a distributor which spreads the liquid over the packing material in the form of thin films.

Packmaterialet utgörs av pá marknaden förekommande fyllmaterial, tunna korrugerade hálförsedda skivor eller plåtar som tvingar vätskefilmerna att oupphörligt ändra strömningsriktning vid passagen genom packmaterialet. Till följd av denna omlänkning och omformning erhålles en stor och ständigt nybildad kontaktyta mot den omgivande atmosfären i kärlet, viket gör att lufthalten hos vätskan snabbt sjunker. Packmaterialet som är inert mot vätskan kan utgöras av rostfritt stàl, lämplig plast eller keram.The packing material consists of filling materials available on the market, thin corrugated semi-finished discs or plates which force the liquid films to constantly change the flow direction during the passage through the packing material. As a result of this deflection and reshaping, a large and constantly newly formed contact surface is obtained with the surrounding atmosphere in the vessel, which causes the air content of the liquid to fall rapidly. The packing material which is inert to the liquid can be made of stainless steel, suitable plastic or ceramic.

Vid avluftningen tillföres vätska genom ledningen 2 till kärlet 1 vilket evakuerats av vakuumpumpen 4 till ett tryck i närheten av absolut vakuum. Vätskan som uppdelats i ett antal tunna vätskefilmer av fördelaren 6 faller under 503 419 10 tyngdkraftens páverkan genom packmaterialet mot kärlets botten och lufthalten i vätskan faller snabbt. I botten pà kärlet samlas den avluftade vätskan och transporteras ut fràn kärlet av en pump 7. Pumpen styrs av en icke visad nivàavkännare i kärlet l.During venting, liquid is supplied through line 2 to the vessel 1 which has been evacuated by the vacuum pump 4 to a pressure close to absolute vacuum. The liquid divided into a number of thin liquid films by the distributor 6 falls under the influence of gravity through the packing material towards the bottom of the vessel and the air content in the liquid falls rapidly. At the bottom of the vessel, the vented liquid is collected and transported out of the vessel by a pump 7. The pump is controlled by a level sensor (not shown) in the vessel 1.

Genom avluftningen kan lufthalten i vätskan sänkas med upp mot 95%. Vakuumkärlens höjd bestäms av den önskade kontakttiden mellan vätskefilmen och den evakuerade atmosfären i kärlet. Enligt uppfinningen kan en tillfredsställande avluftning uppnås med vakuumkärl med under 4 m höjd.Through the deaeration, the air content in the liquid can be reduced by up to 95%. The height of the vacuum vessels is determined by the desired contact time between the liquid film and the evacuated atmosphere in the vessel. According to the invention, a satisfactory deaeration can be achieved with vacuum vessels with a height of less than 4 m.

Claims

10 15 20 25 30 503 419 Patent claims

1. A method of continuously venting particle-free liquid such as water, characterized in that the liquid is distributed into thin films over a packing material in an upper part of a vessel with a height of less than 4 m connected to a vacuum source, that the liquid is passed through a pack material which completely fills the cross-section of the vessel to the greater part of its extent in height, whereby during the distribution liquid films formed during the passage through the packing material are deflected and reshaped so that a constantly newly formed contact surface with the surrounding atmosphere in the vessel is present during a required contact time and vented liquid is taken out at the lower part of the vessel, whereby during venting the vessel is kept at or near absolute vacuum.

2. A method according to claim 1, characterized in that the temperature of the liquid during deaeration is less than 15 ° C.

3. A method according to claims 1-2, characterized in that liquid whose constituent air content is 8-10 ppm after deaeration has an air content of 0.5 ppm.

Device for venting liquid in the manner according to claim 1, characterized by a vacuum vessel (1) with a height of less than 4 m, which vessel in its upper part has a connection (2) to a supply of liquid and in its lower part a connection (3) for transporting deaerated liquid and a connection to means which provides vacuum in the vessel and means for distributing the liquid and for creating a number of thin liquid films in the vessel, the vessel being for the most part filled with an inert packing. material (5) of thin corrugated hollow discs intended 503 419 to create a large contact surface between the liquid and the atmosphere in the room.

Device according to claim 4, characterized in that the height of the vessel is kept constant while the volume (diameter) of the vessel is adapted to the desired capacity.