SE1651285A1 - Train anti-icing system and method of anti-icing a vehicle on tracks - Google Patents

Abstract

A train anti-icing system comprises an anti-icing liquid storage tank (32); a spray nozzle arrangement (16) for spraying anti-icing liquid onto a vehicle on tracks; an anti-icing liquid supply line (34) connected between the anti-icing liquid storage tank (32) and the spray nozzle arrangement (16); a supply valve arrangement (17) for controlling the flow of anti-icing liquid through the spray nozzle arrangement (16); an anti-icing liquid moving arrangement (36) configured to move anti-icing liquid from the storage tank (32), along the anti-icing liquid supply line (34), to the spray nozzle arrangement (16); and a hydropneumatic tank (44) connected to the anti-icing liquid supply line (34) upstream of the supply valve arrangement (17), and configured to be pressurized by the anti-icing liquid moving arrangement (36), so as to allow boosting a flow of anti-icing liquid to the spray nozzle arrangement (16).

Description

TRAIN ANTI-ICING SYSTEM Field of the inventionThe present invention relates to a train anti-icing system and a method of anti-icing a vehicle on tracks.

Backqround of the inventionln cold climate, ice build-up on trains is a safety risk, and therefore trains frequently need to be anti-iced. WO 2013/043090 discloses a fast and efficient trainanti-icing system for reducing the icing of a vehicle on tracks. The anti-icing systemof WO 2013/043090 has a valve arrangement co-located with the spray nozzles, soas to permit spraying trains passing through the anti-icing system at a relatively highspeed. However, there is a need to permit an even further increase the speed of thetrain, so as to reduce the time required to treat the train with anti-icing liquid.

Summarv of the invention lt is an object of the present invention to solve, or at least mitigate, parts or allof the above mentioned problems. To this end, there is provided a train anti-icingsystem comprising an anti-icing liquid storage tank; a spray nozzle arrangement forspraying anti-icing liquid onto a vehicle on tracks; an anti-icing liquid supply lineconnected between the anti-icing liquid storage tank and the spray nozzlearrangement; a supply valve arrangement for controlling the flow of anti-icing liquidthrough the spray nozzle arrangement; an anti-icing liquid moving arrangementconfigured to move anti-icing liquid from the storage tank, along the anti-icing liquidsupply line, to the spray nozzle arrangement; and a hydropneumatic tank connectedto the anti-icing liquid supply line upstream of the supply valve arrangement, andconfigured to be pressurized by the anti-icing liquid moving arrangement, so as toallow boosting a flow of anti-icing liquid to the spray nozzle arrangement. Whenpressurized by the anti-icing liquid moving arrangement, the hydropneumatic tank iscapable of delivering a high flow of anti-icing liquid to the spray nozzle arrangement,thereby permitting a high speed of the vehicle on tracks while it is treated by the anti-icing system. The hydropneumatic tank may be hermetically tight and should have asufficient mechanical strength so as to permit being pressurized.

According to an embodiment, the train anti-icing system may further comprisean anti-icing liquid return line connected between the anti-icing liquid supply line, at a point downstream of the hydropneumatic tank, and the storage tank, wherein theanti-icing liquid return line may comprise a return valve for controlling a return flow ofanti-icing liquid from the hydropneumatic tank to the storage tank. The return linefacilitates maintaining the anti-icing liquid of the hydropneumatic tank at treatmenttemperature by allowing returning the anti-icing liquid to the storage tank forsubsequent re-heating. The anti-icing liquid return line may be connected to the anti-icing liquid supply line at the supply valve arrangement, such that substantially allanti-icing liquid in the anti-icing liquid supply line may be re-circulated. According toan embodiment, the return valve may be temperature controlled, and configured toopen when a temperature of the anti-icing liquid falls below a lower limit temperature.Such an arrangement facilitates maintaining the anti-icing liquid at treatmenttemperature. The return valve may be configured to close when a temperature of theanti-icing liquid exceeds an upper limit temperature, which may be higher than saidlower limit temperature. The temperature controlled return valve may be controlledbased on a temperature detected along the anti-icing liquid supply line, preferably atthe supply valve arrangement. As an alternative or complement to an anti-icing liquidreturn line, the hydropneumatic tank may be provided with a heater.

According to an embodiment, the hydropneumatic tank may be configured tobe pre-loaded with a gas pressure of between 3 and 8 bar, and more typicallybetween 4 and 6 bar. The pre-load pressure defines a minimum supply pressure inthe anti-icing liquid supply line. A supply pressure in this range has been found toresult in a suitable spray pattern.

According to an embodiment, the supply line may be provided with a pressureregulator, downstream of the hydropneumatic tank, configured to limit the anti-icingliquid pressure downstream of the pressure regulator to a working pressure between3 and 8 bar, and more typically between 4 and 6 bar. The working pressure may besubstantially constant. lt may be substantially the same as a pre-load pressure of thehydropneumatic tank.

According to an embodiment, the anti-icing liquid moving arrangement maycomprise a supply pump connected to the anti-icing liquid supply line and configuredto pump anti-icing liquid from the storage tank, along the anti-icing liquid supply line,to the spray nozzle arrangement, wherein the hydropneumatic tank may beconnected to the anti-icing liquid supply line downstream of the supply pump andupstream of the supply valve arrangement. Alternatively, the storage tank may itselfdefine said hydropneumatic tank, which may be pressurized by a source of 2 compressed gas, such as an air Compressor or a gas cylinder, connected to thestorage tank. According to an embodiment, the supply pump may be controlledbased on a detected pressure downstream of the supply pump. The supply pumpmay be configured to start when said detected pressure falls below a lower limitpressure, and to stop when said detected pressure exceeds an upper limit pressure.By way of example, the lower limit pressure may be between 3 and 8 bar, and moretypically between 4 and 6 bar. lt may be substantially the same as a pre-loadpressure of the hydropneumatic tank. An exemplary upper limit pressure may bebetween 7 and 15 bar, and more typically between 8 and 12 bar.

According to an embodiment, the hydropneumatic tank may comprise amembrane dividing the hydropneumatic tank into a gas space and an anti-icing liquidspace. The membrane allows the pressure in the liquid and gas spaces to beequalized, while it prevents gas from leaking out from the hydropneumatic tank,which might otherwise happen in the event that the pressure in the anti-icing liquidsupply line would fall below a limit pressure.

According to an embodiment, the train anti-icing system may further comprisea collection tray for collecting spent anti-icing liquid falling from the vehicle, and areturn line for anti-icing liquid that has been collected by the collection tray.

According to an embodiment, the train anti-icing system may further comprisea heater system configured to heat the anti-icing liquid of the storage tank to atreatment temperature, the heater system comprising a heater and a heaterrecirculation line configured to transfer anti-icing liquid from the storage tank to theheater and back to the storage tank. As exemplary alternatives, the heater may bearranged inside the storage tank or inside the hydropneumatic tank.

According to another aspect of the invention, parts or all of the abovementioned problems are solved, or at least mitigated, by a method of anti-icing avehicle on tracks, the method comprising moving anti-icing liquid into ahydropneumatic tank; detecting the arrival of a vehicle on tracks to be treated; andbased on the position of the vehicle on tracks, operating a supply valve arrangementdownstream of the hydropneumatic tank so as to spray anti-icing liquid onto thevehicle. Such a method allows obtaining a high spray flow of anti-icing liquid, therebypermitting a high speed of the vehicle on tracks while it is treated by the anti-icingsystem.

According to an embodiment, the hydropneumatic tank may be pressurized bymoving anti-icing liquid into the hydropneumatic tank. As an alternative or 3 supplementary method of pressurizing the hydropneumatic tank, the hydropneumatictank may pressurized by a source of compressed gas, such as an air Compressor ora gas cylinder.

According to an embodiment, the method may further comprise maintaininganti-icing liquid at a treatment temperature in a storage tank upstream of thehydropneumatic tank; detecting a temperature of the anti-icing liquid downstream ofthe hydropneumatic tank; and based on the detected temperature, operating a returnvalve downstream of the hydropneumatic tank so as to return anti-icing liquid to thestorage tank for re-heating.

Brief description of the drawinqs The above, as well as additional objects, features and advantages of thepresent invention, will be better understood through the following illustrative and non-limiting detailed description of preferred embodiments of the present invention, withreference to the appended drawings, where the same reference numerals will beused for similar elements, wherein: Fig. 1 is a diagrammatic view in perspective of a train anti-icing system; Fig. 2a is a functional block diagram illustrating the interrelation betweenvarious components of the anti-icing system of Fig. 1 according to a firstembodiment; Fig. 2b is a detail view ofa portion of system illustrated in Fig. 2a; and Fig. 3 is a functional block diagram illustrating the interrelation betweenvarious components of the anti-icing system of Fig. 1 according to a secondembodiment.

Detailed description of the exemplarv embodimentsFig. 1 schematically illustrates a train anti-icing system 10 for reducing thebuild-up of ice on trains. The anti-icing system 10 may be used for de- icing as wellas for anti-icing a train, i.e. leaving an ice-repellent coating of anti-icing liquid on thesurface of the train during or after de-icing, or without prior de-icing. The system 10 isconfigured as a drive-through system, i.e. a train 12, arriving on tracks 14 from theupper left corner of Fig. 1, passes through the system 10 without having to stopduring the de-/anti-icing process. The anti-icing system 10 comprises a spray nozzlearrangement 16 for spraying an anti-icing liquid onto the train 12, and a collectiontray arrangement 18 for collecting spent anti-icing liquid dripping from the train 12.The system 10 may also be provided with a sensor (not shown) for determining4 locations, relative to the spray nozzle arrangement 16, of portions of the train 12 tobe selectively sprayed, e.g. in the manner described in WO 2013/043090. Thereby,spraying may be focussed onto the train portions the most sensitive to icing, such aswheel units. Typically, an anti-icing liquid would be a liquid having a freezing pointsufficiently below the freezing point of water, such that any anti- icing liquid residuesremaining on the train after de-icing will remain in liquid or slush form when the train12 is again exposed to cold climate. Thereby, anti-icing liquid residues remaining onthe surface of the train 12 will prevent snow and ice from attaching to the train 12.Even though not necessary, the anti-icing liquid may optionally be heated whensprayed to the train 12, so as to increase the de-icing efficiency of the liquid whensprayed onto the train 12. Moreover, it may be preferred to use an anti-icing liquidhaving a high viscosity when cold, so as to make the anti-icing liquid less prone to beblown off the train 12 as the train 12 moves at high speed. Ethylene glycol, propyleneglycol, other alcohols, salt, and sugar are the most common anti-icing liquidingredients in the art, and may be used for preparing serviceable anti-icing liquid, e.g.by mixing with water.

The spent anti-icing liquid may comprise a slush of anti-icing liquid, rain, dirt,ice, and melted ice in the form of water. The collection tray arrangement 18 extendsalong a relatively short spray zone 20, at which the spray nozzle arrangement 16 islocated, and a somewhat longer collection zone 22, along which no substantivespraying of anti-icing liquid occurs. The collection tray arrangement 18 comprisesthree collection trays 18a, 18b, 18c extending along the rails 14. Two collection trays18a, 18b extend along the sides of the tracks 14, while a third collection tray 18cextends between the tracks 14. A drain arrangement 26 comprises a set ofdrains26a-c located at the bottoms of the respective collection trays 18a-c. The drainarrangement 26 allows spent anti-icing liquid to be collected from the collection trayarrangement 18 and transferred to a re-circulation plant 28, which may be locatedwithin a housing formed by e.g. a cargo container 30. Thereby, the anti-icing system10 may be prepared or assembled at a central site, and quickly transported to andinstalled at a de-icing site when needed.

Turning now to Fig. 2a, the anti-icing system comprises an anti-icing liquidstorage tank 32, which may be housed inside the container 30 (Fig. 1). The storagetank 32 may be any type of pressurized or unpressurized liquid container. An anti-icing liquid supply line 34, connected between the anti-icing liquid storage tank 32and the spray nozzle arrangement 16, allows anti-icing liquid to be transferred from 5 the storage tank 32 to the spray nozzle arrangement 16. A supply valve arrangement17 is co-located with the spray nozzle arrangement 16 outside the cargo container 30(Fig. 1), and controls the flow of anti-icing liquid to the spray nozzle arrangement 16.An anti-icing liquid moving arrangement is configured to move anti-icing liquid fromthe storage tank 32, along the anti-icing liquid supply line 34, to the spray nozzlearrangement 16. ln the illustrated embodiment of Fig. 2a, the anti-icing liquid movingarrangement is embodied by a supply pump 36, which pressurizes the anti-icingliquid in the supply line 34 downstream of the supply pump 36. The pressure ismaintained by a check valve 38 when the supply pump 36 stops. A pressure sensor40 detects the anti-icing liquid pressure in the supply line 34 downstream of thecheck valve 38. The supply pump 36 is operationally coupled to the pressure sensor40 so as to stop when the detected pressure exceeds an upper limit pressure ofabout 10 bar, and to start when the detected pressure falls below a lower limitpressure of about 5 bar. Downstream of the check valve 38, a pressure regulator 42reduces the operating pressure to about 4 bar, such that the pressure downstream ofthe pressure regulator 42 will be maintained substantially constant. Ahydropneumatic tank 44 is connected to the anti-icing liquid supply line 34downstream of the check valve 38 and upstream of the pressure regulator 42. Thehydropneumatic tank 44 is divided into a lower anti-icing liquid space 44a, which is influid communication with the supply line 34, and an upper gas space 44b, which isfluidly isolated from, but in pressure communication with, the lower space 44a. Theupper and lower spaces 44b, 44a are separated by a flexible membrane 46. Theupper space 44b is filled with compressed air to a pressure of about 5 bar via acompressed air inlet (not shown), such that when the pressure in the supply line 34 isat 5 bar, the gas space 44b will take up substantially the entire inner volume of thehydropneumatic tank 44. When the supply pump 36 has raised the pressure in thesupply line 34 to 10 bar, the hydropneumatic tank will be almost filled with anti-icingliquid. Thereby, when the sprayer valves 19 of the supply valve arrangement 17 areopened, the hydropneumatic tank 44 will act as a boost flow generator, maintainingthe pressure in the supply line 34 at the location of the hydropneumatic tank 44above 5 bar until all anti-icing liquid has been pressed out of the hydropneumatictank 44. Thanks to the boost flow made available by the hydropneumatic tank 44, it ispossible to obtain a very high flow through the spray nozzle arrangement 16 with amaintained operating pressure of the anti-icing liquid at the location of the spray nozzle arrangement 16. Thereby, a high speed of the vehicle 12 (Fig. 1) to be treatedmay be permitted.

The supply valve arrangement 17 comprises a plurality of individuallycontrolled sprayer valves 19, and each sprayer valve 19 is connected to one orseveral spray nozzles 48 (Fig. 2b). Similar to what is disclosed in WO 2013/043090,the sprayer valves 19 are controlled based on the position and speed of the vehicle12 to be treated, the type of vehicle 12, and what portions of the vehicle 12 should besprayed. Anti-icing liquid falling off the vehicle 12 is collected by tray 18 and entersreturn line 64 for re-use or disposal in a manner which will not be further elaboratedupon in this disclosure.

Typically, the anti-icing liquid may be sprayed onto the vehicle 12 at atreatment temperature, which may be elevated relative to the outdoor, ambienttemperature. A typical treatment temperature may be between 10 °C and 40 °C. lnorder to maintain the anti-icing liquid at treatment temperature, the storage tank 32 isconnected via a heater recirculation line 50 to a heater 52. A heater circuit pump 54is activated based on the temperature of the anti-icing liquid in the storage tank 32falling below a limit temperature; for the purpose, the storage tank 32 is provided witha temperature sensor 56. The anti-icing liquid used in the system 10 may be tailored,using viscosity modifiers, such that it has a low viscosity at the treatmenttemperature, i.e. at the temperature it holds when sprayed onto the train 12, and ahigh viscosity at temperatures below 0 °C. Thereby, the anti-icing liquid may be easilysprayed through the spray nozzle arrangement 16, and it will immediately raise itsviscosity when it hits the cold surface of the vehicle 12. Such viscosity modified anti-icing liquid is less prone to be blown off the vehicle 12 when the vehicle 12 is inoperational service, i.e. between consecutive anti-icing treatments. By way ofexample, glycol, such as ethylene or propylene glycol, may be used as a base, andviscosity modifier additives may be added to give the anti-icing liquid a kinematicviscosity of more than 4000 mm2/s at temperatures below -10 °C, while maintaining arelatively low viscosity of less than 300 mm2/s at temperatures above 30 °C. ln orderto facilitate keeping the anti-icing liquid at the treatment temperature all the way outto the nozzle arrangement 16, an anti-icing liquid return line 58 is connected betweenthe anti-icing liquid supply line 34, at a point immediately upstream of the sprayervalves 19, and the storage tank 32. A return valve 60 is co-located with the sprayervalves 19 of the supply valve arrangement 17, and controls the return flow from thesupply valve arrangement 17 to the storage tank 32. Thanks to the return line 58, the 7 anti-icing liquid of the entire supply line 34, including the hydropneumatic tank 44,may be returned to the storage tank for subsequent re-heating. The return valve 60 istemperature controlled, and configured to open when the temperature of the anti-icing liquid falls below a lower limit temperature, and/or to close when a temperatureof the anti-icing liquid exceeds an upper limit temperature. For the purpose, atemperature sensor 62 is connected to the supply line 34 at the supply valvearrangement 17, and provides its reading to the return valve 60. By way of example,the lower limit temperature may be between 15 °C and 50 °C, and the upper limittemperature may be between 3 °C and 30 °C higher than the lower limit temperature.

Similar to what is disclosed in WO 2013/043090, a control system (notillustrated) controls all sensors, valves and pumps according to the teachings herein.

Fig. 3 illustrates an alternative embodiment of a train anti-icing system 110.The system 110 comprises a pressurized anti-icing liquid storage tank 132, whichthereby also has the added function of acting as a hydropneumatic tank forgenerating a high flow rate. The storage tank 132 is pressurized by a high-pressuregas cylinder 136 which, via a gas pressure regulator 137, maintains a substantiallyconstant pressure in the storage tank 132. Thereby, the gas cylinder 136 operates asan anti-icing liquid moving arrangement for moving the anti-icing liquid from thestorage tank 132, along the anti-icing liquid supply line 134, to the spray nozzlearrangement 16. An exemplary pressure provided by the gas pressure regulator 137may be between 3 bar and 8 bar, or between 4 bar and 6 bar. The storage tank 132may, similar to the hydropneumatic tank 44 of Fig. 2a, be divided into separate airand liquid spaces by means of e.g. a membrane. However, this is not necessary.Hence, the storage tank 132 of Fig. 3 is illustrated without such a division betweengas and liquid. Whenever the storage tank 132 is to be filled, the storage tank maybe de-pressurized prior to filling. The storage tank maintains a substantially constantpressure in the supply line 134, which is configured to supply anti-icing liquid to thespray nozzle arrangement 16 via a supply valve arrangement 17 in a manner similarto that of Fig. 2. The anti-icing system of Fig. 3 is not provided with a return line or aheater recirculation line.

The present disclosure describes several different inventive concepts, each ofwhich may be implemented independently of, or in combination with, the others.Each separate inventive concept described herein may also form the basis of adivisional application. By way of example, according to a second inventive conceptand again with reference to Fig. 2a, there is provided a train anti-icing system 10 8 comprising an anti-icing liquid storage tank 32; a spray nozzle arrangement 16 forspraying anti-icing liquid onto a vehicle 12 on tracks; an anti-icing liquid supply line34 for transferring anti-icing liquid from the storage tank 32 to the spray nozzlearrangement 16; a supply valve arrangement 17 for controlling the flow of anti-icingliquid through the spray nozzle arrangement 16; and an anti-icing liquid return line 58connected between the anti-icing liquid supply line 43 and the storage tank, whereinthe anti-icing liquid return line 58 comprises a return valve 60 for controlling a returnflow from the anti-icing liquid supply line 34 to the storage tank 32. Such anarrangement allows maintaining the anti-icing liquid in the supply line 34 at a stable,elevated treatment temperature at all times, thereby rendering the anti-icing processmore reproducible and predictable. This allows for an increased precision of the anti-icing spray pattern, which may reduce the consumption of anti-icing liquid. Moreover,maintaining the anti-icing liquid in the supply line 34 at a stable, elevated treatmenttemperature may be particularly desirable in combination with the use of an anti-icingliquid which, using a viscosity modifier additive, has been given a high viscosity attemperatures below treatment temperature. According to an embodiment, the anti-icing liquid return line may be connected to the anti-icing liquid supply line 32 at thesupply valve arrangement 17. The return valve 60 may be temperature controlled,and may be configured to open when a temperature of the anti-icing liquid falls belowa lower limit temperature, and/or to close when the temperature of the anti-icing liquidexceeds an upper limit temperature. The controlled return valve 60 may be controlledbased on a temperature detected along the anti-icing liquid supply line 34, such as atthe supply valve arrangement 17.

According to a third inventive concept, there is provided a train anti-icing liquidcomprising a base liquid, such as propylene glycol, and viscosity modifying additives.The viscosity modifying additives may be selected so as to raise the kinematicviscosity of the anti-icing liquid at temperatures below -10C° to e.g. more than 700mm2/s, more than 1000 mm2/s, more than 2000 mm2/s, or more than 4000 mm2/s.Moreover, the viscosity modifying additives may at the same time be selected so asto maintain a kinematic viscosity of the anti-icing liquid, at temperatures above 30 °C,of e.g. less than 600 mm2/s, less than 400 mm2/s, less than 200 mm2/s, or less than100 mm2/s. Again with reference to Fig. 2a, there is also provided a train anti-icingsystem 10 comprising a container 32 containing such train anti-icing liquid, and aspray nozzle arrangement 16 operatively connected so as to receive anti-icing liquidfrom said container 32. There is also provided a method of anti-icing a train, the 9 method comprising spraying such anti-icing liquid onto the train. The method mayfurther comprise maintaining and spraying the anti-icing liquid at an elevatedtreatment temperature, as described with reference to Fig. 2a, and allowing the liquidto be immediately cooled down below -10 °C by the train.

The inventions have mainly been described above with reference to a fewembodiments. However, as is readily appreciated by a person skilled in the art, otherembodiments than the ones disclosed above are equally possible within the scope ofthe invention, as defined by the appended patent claims. For example, a spraynozzle arrangement 16 comprising multiple spray nozzles has been illustrated. As analternative, the spray nozzle arrangement may comprise only one single spraynozzle. The invention may be used for many different types of vehicles on tracks,such as trams, and is not limited to trains only.

Claims (1)

1. i A train anti-icing system comprising an anti-icing liquid storage tank (32; 132); a spray nozzle arrangement (16) for spraying anti-icing liquid onto avehicle on tracks (12); an anti-icing liquid supply line (34; 134) connected between the anti-icingliquid storage tank (32; 132) and the spray nozzle arrangement (16); a supply valve arrangement (17) for controlling the flow of anti-icing liquidthrough the spray nozzle arrangement (16); and an anti-icing liquid moving arrangement (36; 136) configured to moveanti-icing liquid from the storage tank (32; 132), along the anti-icing liquidsupply line (34; 134), to the spray nozzle arrangement (16), the anti-icingsystem (10; 110) being characterized in a hydropneumatic tank (44) connected to the anti-icing liquid supply line(34; 134) upstream of the supply valve arrangement (17), and configured tobe pressurized by the anti-icing liquid moving arrangement (36; 136), so as toallow boosting a flow of anti-icing liquid to the spray nozzle arrangement (16). The train anti-icing system according to claim 1, further comprising an anti-icing liquid return line (58) connected between the anti-icing liquid supply line(34), at a point downstream of the hydropneumatic tank, and the storage tank(32), wherein the anti-icing liquid return line comprises a return valve (60) forcontrolling a return flow of anti-icing liquid from the hydropneumatic tank (44)to the storage tank (32). The train anti-icing system according to claim 2, wherein the return valve (60)is temperature controlled, and configured to open when a temperature of theanti-icing liquid falls below a lower limit temperature. The train anti-icing system according to any of the previous claims, whereinthe hydropneumatic tank (44) is configured to be pre-loaded with a gaspressure of between 3 and 8 bar, and more preferably between 4 and 6 bar. The train anti-icing system according to any of the previous claims, whereinthe supply line (34) is provided with a pressure regulator (42), downstream ofthe hydropneumatic tank (44), configured to limit the anti-icing liquid pressure 11 10. 11. downstream of the pressure regulator (42) to a working pressure between 3and 8 bar, and preferably between 4 and 6 bar. The train anti-icing system according to any of the previous claims, whereinthe anti-icing liquid moving arrangement comprises a supply pump (36)connected to the anti-icing liquid supply line (34) and configured to pumpanti-icing liquid from the storage tank (32), along the anti-icing liquid supplyline (34), to the spray nozzle arrangement (16), wherein the hydropneumatictank (44) is connected to the anti-icing liquid supply line (34) downstream ofthe supply pump (36) and upstream of the supply valve arrangement (17). The train anti-icing system according to claim 6, wherein the supply pump(36) is controlled based on a detected pressure downstream of the supplypump (36). The train anti-icing system according to any of the previous claims, whereinthe hydropneumatic tank (44) comprises a membrane (46) dividing thehydropneumatic tank (44) into a gas space (44b) and an anti-icing liquidspace (44a). The train anti-icing system according to any of the previous claims, furthercomprising a collection tray (18) for collecting spent anti-icing liquid fallingfrom the vehicle (12), and a return line (64) for anti-icing liquid that has beencollected by the collection tray (18). The train anti-icing system according to any of the previous claims, furthercomprising a heater system configured to heat the anti-icing liquid of thestorage tank (32) to a treatment temperature, the heater system comprising aheater (52) and a heater recirculation line (50) configured to transfer anti-icing liquid from the storage tank (32) to the heater (52) and back to thestorage tank (32). A method of anti-icing a vehicle on tracks, comprisingmoving anti-icing liquid into a hydropneumatic tank (44; 132);detecting the arrival of a vehicle on tracks (12) to be treated; andbased on the position of the vehicle on tracks (12), operating a supply 12 12. valve arrangement (17) downstream of the hydropneumatic tank (44; 132) soas to spray anti-icing liquid onto the vehicle (12). The method according to ciaim 11, further comprising maintaining anti-icing liquid at a treatment temperature in a storage tank(32) upstream of the hydropneumatic tank (44); detecting a temperature of the anti-icing liquid downstream of thehydropneumatic tank (44); and based on the detected temperature, operating a return valve (60)downstream of the hydropneumatic tank (44) so as to return anti-icing liquidto the storage tank (32) for re-heating. 13