SE540360C2

SE540360C2 - Train anti-icing system and method of anti-icing a vehicle on tracks

Info

Publication number: SE540360C2
Application number: SE1651285A
Authority: SE
Inventors: Anders Larsson
Original assignee: Nordic Ground Support Equipment Ip Ab
Priority date: 2016-09-30
Filing date: 2016-09-30
Publication date: 2018-08-07
Also published as: WO2018063060A1; SE1651285A1

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 AND METHOD OF ANTI-ICING A VEHICLE ON TRACKS Field of the invention The present invention relates to a train anti-icing system and a method of antiicing a vehicle on tracks.

Background of the invention In 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 train anti-icing system for reducing the icing of a vehicle on tracks. The anti-icing system of WO 2013/043090 has a valve arrangement co-located with the spray nozzles, so as to permit spraying trains passing through the anti-icing system at a relatively high speed. However, there is a need to permit an even further increase the speed of the train, so as to reduce the time required to treat the train with anti-icing liquid.

Summary of the invention It is an object of the present invention to solve, or at least mitigate, parts or all of the above mentioned problems. To this end, there is provided a train anti-icing system comprising an anti-icing liquid storage tank; a spray nozzle arrangement for spraying anti-icing liquid onto a vehicle on tracks; an anti-icing liquid supply line connected between the anti-icing liquid storage tank and the spray nozzle arrangement; a supply valve arrangement for controlling the flow of anti-icing liquid through the spray nozzle arrangement; an anti-icing liquid moving arrangement configured to move anti-icing liquid from the storage tank, along the anti-icing liquid supply line, to the spray nozzle arrangement; and a hydropneumatic tank connected to the anti-icing liquid supply line upstream of the supply valve arrangement, and configured to be pressurized by the anti-icing liquid moving arrangement, so as to allow boosting a flow of anti-icing liquid to the spray nozzle arrangement. When pressurized by the anti-icing liquid moving arrangement, the hydropneumatic tank is capable 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 antiicing system. The hydropneumatic tank may be hermetically tight and should have a sufficient mechanical strength so as to permit being pressurized.

According to an embodiment, the train anti-icing system may further comprise an 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 the anti-icing liquid return line may comprise a return valve for controlling a return flow of anti-icing liquid from the hydropneumatic tank to the storage tank. The return line facilitates maintaining the anti-icing liquid of the hydropneumatic tank at treatment temperature by allowing returning the anti-icing liquid to the storage tank for subsequent re-heating. The anti-icing liquid return line may be connected to the antiicing liquid supply line at the supply valve arrangement, such that substantially all anti-icing liquid in the anti-icing liquid supply line may be re-circulated. According to an embodiment, the return valve may be temperature controlled, and configured to open when a temperature of the anti-icing liquid falls below a lower limit temperature. Such an arrangement facilitates maintaining the anti-icing liquid at treatment temperature. The return valve may be configured to close when a temperature of the anti-icing liquid exceeds an upper limit temperature, which may be higher than said lower limit temperature. The temperature controlled return valve may be controlled based on a temperature detected along the anti-icing liquid supply line, preferably at the supply valve arrangement. As an alternative or complement to an anti-icing liquid return line, the hydropneumatic tank may be provided with a heater.

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

According to an embodiment, the supply line may be provided with a pressure regulator, downstream of the hydropneumatic tank, configured to limit the anti-icing liquid pressure downstream of the pressure regulator to a working pressure between 3 and 8 bar, and more typically between 4 and 6 bar. The working pressure may be substantially constant. It may be substantially the same as a pre-load pressure of the hydropneumatic tank.

According to an embodiment, the anti-icing liquid moving arrangement may comprise a supply pump connected to the anti-icing liquid supply line and configured to 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 be connected to the anti-icing liquid supply line downstream of the supply pump and upstream of the supply valve arrangement. Alternatively, the storage tank may itself define said hydropneumatic tank, which may be pressurized by a source of compressed gas, such as an air compressor or a gas cylinder, connected to the storage tank. According to an embodiment, the supply pump may be controlled based on a detected pressure downstream of the supply pump. The supply pump may be configured to start when said detected pressure falls below a lower limit pressure, 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 more typically between 4 and 6 bar. It may be substantially the same as a pre-load pressure of the hydropneumatic tank. An exemplary upper limit pressure may be between 7 and 15 bar, and more typically between 8 and 12 bar.

According to an embodiment, the hydropneumatic tank may comprise a membrane dividing the hydropneumatic tank into a gas space and an anti-icing liquid space. The membrane allows the pressure in the liquid and gas spaces to be equalized, 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 liquid supply line would fall below a limit pressure.

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

According to an embodiment, the train anti-icing system may further comprise a heater system configured to heat the anti-icing liquid of the storage tank to a treatment temperature, the heater system comprising a heater and a heater recirculation line configured to transfer anti-icing liquid from the storage tank to the heater and back to the storage tank. As exemplary alternatives, the heater may be arranged inside the storage tank or inside the hydropneumatic tank.

According to another aspect of the invention, parts or all of the above mentioned problems are solved, or at least mitigated, by a method of anti-icing a vehicle on tracks, the method comprising moving anti-icing liquid into a hydropneumatic tank; detecting the arrival of a vehicle on tracks to be treated; and based on the position of the vehicle on tracks, operating a supply valve arrangement downstream of the hydropneumatic tank so as to spray anti-icing liquid onto the vehicle. Such a method allows obtaining a high spray flow of anti-icing liquid, thereby permitting a high speed of the vehicle on tracks while it is treated by the anti-icing system.

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

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

Brief description of the drawings The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and nonlimiting detailed description of preferred embodiments of the present invention, with reference to the appended drawings, where the same reference numerals will be used 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 between various components of the anti-icing system of Fig. 1 according to a first embodiment; Fig. 2b is a detail view of a portion of system illustrated in Fig. 2a; and Fig. 3 is a functional block diagram illustrating the interrelation between various components of the anti-icing system of Fig. 1 according to a second embodiment.

Detailed description of the exemplary embodiments Fig. 1 schematically illustrates a train anti-icing system 10 for reducing the build-up of ice on trains. The anti-icing system 10 may be used for de- icing as well as for anti-icing a train, i.e. leaving an ice-repellent coating of anti-icing liquid on the surface of the train during or after de-icing, or without prior de-icing. The system 10 is configured as a drive-through system, i.e. a train 12, arriving on tracks 14 from the upper left corner of Fig. 1, passes through the system 10 without having to stop during the de-/anti-icing process. The anti-icing system 10 comprises a spray nozzle arrangement 16 for spraying an anti-icing liquid onto the train 12, and a collection tray 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 determining locations, relative to the spray nozzle arrangement 16, of portions of the train 12 to be 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 as wheel units. Typically, an anti-icing liquid would be a liquid having a freezing point sufficiently below the freezing point of water, such that any anti- icing liquid residues remaining on the train after de-icing will remain in liquid or slush form when the train 12 is again exposed to cold climate. Thereby, anti-icing liquid residues remaining on the 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 when sprayed to the train 12, so as to increase the de-icing efficiency of the liquid when sprayed onto the train 12. Moreover, it may be preferred to use an anti-icing liquid having a high viscosity when cold, so as to make the anti-icing liquid less prone to be blown off the train 12 as the train 12 moves at high speed. Ethylene glycol, propylene glycol, other alcohols, salt, and sugar are the most common anti-icing liquid ingredients 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 extends along a relatively short spray zone 20, at which the spray nozzle arrangement 16 is located, and a somewhat longer collection zone 22, along which no substantive spraying of anti-icing liquid occurs. The collection tray arrangement 18 comprises three collection trays 18a, 18b, 18c extending along the rails 14. Two collection trays 18a, 18b extend along the sides of the tracks 14, while a third collection tray 18c extends between the tracks 14. A drain arrangement 26 comprises a set of drains 26a-c located at the bottoms of the respective collection trays 18a-c. The drain arrangement 26 allows spent anti-icing liquid to be collected from the collection tray arrangement 18 and transferred to a re-circulation plant 28, which may be located within a housing formed by e.g. a cargo container 30. Thereby, the anti-icing system 10 may be prepared or assembled at a central site, and quickly transported to and installed at a de-icing site when needed.

Turning now to Fig. 2a, the anti-icing system comprises an anti-icing liquid storage tank 32, which may be housed inside the container 30 (Fig. 1). The storage tank 32 may be any type of pressurized or unpressurized liquid container. An antiicing liquid supply line 34, connected between the anti-icing liquid storage tank 32 and the spray nozzle arrangement 16, allows anti-icing liquid to be transferred from the storage tank 32 to the spray nozzle arrangement 16. A supply valve arrangement 17 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 from the storage tank 32, along the anti-icing liquid supply line 34, to the spray nozzle arrangement 16. In the illustrated embodiment of Fig. 2a, the anti-icing liquid moving arrangement is embodied by a supply pump 36, which pressurizes the anti-icing liquid in the supply line 34 downstream of the supply pump 36. The pressure is maintained by a check valve 38 when the supply pump 36 stops. A pressure sensor 40 detects the anti-icing liquid pressure in the supply line 34 downstream of the check valve 38. The supply pump 36 is operationally coupled to the pressure sensor 40 so as to stop when the detected pressure exceeds an upper limit pressure of about 10 bar, and to start when the detected pressure falls below a lower limit pressure of about 5 bar. Downstream of the check valve 38, a pressure regulator 42 reduces the operating pressure to about 4 bar, such that the pressure downstream of the pressure regulator 42 will be maintained substantially constant. A hydropneumatic tank 44 is connected to the anti-icing liquid supply line 34 downstream of the check valve 38 and upstream of the pressure regulator 42. The hydropneumatic tank 44 is divided into a lower anti-icing liquid space 44a, which is in fluid communication with the supply line 34, and an upper gas space 44b, which is fluidly isolated from, but in pressure communication with, the lower space 44a. The upper and lower spaces 44b, 44a are separated by a flexible membrane 46. The upper space 44b is filled with compressed air to a pressure of about 5 bar via a compressed air inlet (not shown), such that when the pressure in the supply line 34 is at 5 bar, the gas space 44b will take up substantially the entire inner volume of the hydropneumatic tank 44. When the supply pump 36 has raised the pressure in the supply line 34 to 10 bar, the hydropneumatic tank will be almost filled with anti-icing liquid. Thereby, when the sprayer valves 19 of the supply valve arrangement 17 are opened, the hydropneumatic tank 44 will act as a boost flow generator, maintaining the pressure in the supply line 34 at the location of the hydropneumatic tank 44 above 5 bar until all anti-icing liquid has been pressed out of the hydropneumatic tank 44. Thanks to the boost flow made available by the hydropneumatic tank 44, it is possible to obtain a very high flow through the spray nozzle arrangement 16 with a maintained 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 treated may be permitted.

The supply valve arrangement 17 comprises a plurality of individually controlled sprayer valves 19, and each sprayer valve 19 is connected to one or several 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 vehicle 12 to be treated, the type of vehicle 12, and what portions of the vehicle 12 should be sprayed. Anti-icing liquid falling off the vehicle 12 is collected by tray 18 and enters return line 64 for re-use or disposal in a manner which will not be further elaborated upon in this disclosure.

Typically, the anti-icing liquid may be sprayed onto the vehicle 12 at a treatment temperature, which may be elevated relative to the outdoor, ambient temperature. A typical treatment temperature may be between 10<º>C and 40<º>C. In order to maintain the anti-icing liquid at treatment temperature, the storage tank 32 is connected via a heater recirculation line 50 to a heater 52. A heater circuit pump 54 is activated based on the temperature of the anti-icing liquid in the storage tank 32 falling below a limit temperature; for the purpose, the storage tank 32 is provided with a 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 treatment temperature, i.e. at the temperature it holds when sprayed onto the train 12, and a high viscosity at temperatures below 0<º>C. Thereby, the anti-icing liquid may be easily sprayed through the spray nozzle arrangement 16, and it will immediately raise its viscosity when it hits the cold surface of the vehicle 12. Such viscosity modified antiicing liquid is less prone to be blown off the vehicle 12 when the vehicle 12 is in operational service, i.e. between consecutive anti-icing treatments. By way of example, glycol, such as ethylene or propylene glycol, may be used as a base, and viscosity modifier additives may be added to give the anti-icing liquid a kinematic viscosity of more than 4000 mm<2>/s at temperatures below -10<º>C, while maintaining a relatively low viscosity of less than 300 mm<2>/s at temperatures above 30<º>C. In order to facilitate keeping the anti-icing liquid at the treatment temperature all the way out to the nozzle arrangement 16, an anti-icing liquid return line 58 is connected between the anti-icing liquid supply line 34, at a point immediately upstream of the sprayer valves 19, and the storage tank 32. A return valve 60 is co-located with the sprayer valves 19 of the supply valve arrangement 17, and controls the return flow from the supply valve arrangement 17 to the storage tank 32. Thanks to the return line 58, the 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 is temperature controlled, and configured to open when the temperature of the antiicing liquid falls below a lower limit temperature, and/or to close when a temperature of the anti-icing liquid exceeds an upper limit temperature. For the purpose, a temperature sensor 62 is connected to the supply line 34 at the supply valve arrangement 17, and provides its reading to the return valve 60. By way of example, the lower limit temperature may be between 15<º>C and 50<º>C, and the upper limit temperature may be between 3<º>C and 30<º>C higher than the lower limit temperature.

Similar to what is disclosed in WO 2013/043090, a control system (not illustrated) 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, which thereby also has the added function of acting as a hydropneumatic tank for generating a high flow rate. The storage tank 132 is pressurized by a high-pressure gas cylinder 136 which, via a gas pressure regulator 137, maintains a substantially constant pressure in the storage tank 132. Thereby, the gas cylinder 136 operates as an anti-icing liquid moving arrangement for moving the anti-icing liquid from the storage tank 132, along the anti-icing liquid supply line 134, to the spray nozzle arrangement 16. An exemplary pressure provided by the gas pressure regulator 137 may be between 3 bar and 8 bar, or between 4 bar and 6 bar. The storage tank 132 may, similar to the hydropneumatic tank 44 of Fig. 2a, be divided into separate air and liquid spaces by means of e.g. a membrane. Flowever, this is not necessary. Flence, the storage tank 132 of Fig. 3 is illustrated without such a division between gas and liquid. Whenever the storage tank 132 is to be filled, the storage tank may be de-pressurized prior to filling. The storage tank maintains a substantially constant pressure in the supply line 134, which is configured to supply anti-icing liquid to the spray nozzle arrangement 16 via a supply valve arrangement 17 in a manner similar to that of Fig. 2. The anti-icing system of Fig. 3 is not provided with a return line or a heater recirculation line.

The present disclosure describes several different inventive concepts, each of which may be implemented independently of, or in combination with, the others. Each separate inventive concept described herein may also form the basis of a divisional application. By way of example, according to a second inventive concept and again with reference to Fig. 2a, there is provided a train anti-icing system 10 comprising an anti-icing liquid storage tank 32; a spray nozzle arrangement 16 for spraying anti-icing liquid onto a vehicle 12 on tracks; an anti-icing liquid supply line 34 for transferring anti-icing liquid from the storage tank 32 to the spray nozzle arrangement 16; a supply valve arrangement 17 for controlling the flow of anti-icing liquid through the spray nozzle arrangement 16; and an anti-icing liquid return line 58 connected between the anti-icing liquid supply line 43 and the storage tank, wherein the anti-icing liquid return line 58 comprises a return valve 60 for controlling a return flow from the anti-icing liquid supply line 34 to the storage tank 32. Such an arrangement 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 process more reproducible and predictable. This allows for an increased precision of the antiicing 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 treatment temperature may be particularly desirable in combination with the use of an anti-icing liquid which, using a viscosity modifier additive, has been given a high viscosity at temperatures below treatment temperature. According to an embodiment, the antiicing liquid return line may be connected to the anti-icing liquid supply line 32 at the supply 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 below a lower limit temperature, and/or to close when the temperature of the anti-icing liquid exceeds an upper limit temperature. The controlled return valve 60 may be controlled based on a temperature detected along the anti-icing liquid supply line 34, such as at the supply valve arrangement 17.

According to a third inventive concept, there is provided a train anti-icing liquid comprising a base liquid, such as propylene glycol, and viscosity modifying additives. The viscosity modifying additives may be selected so as to raise the kinematic viscosity of the anti-icing liquid at temperatures below -10C<º>to e.g. more than 700 mm<2>/s, more than 1000 mm<2>/s, more than 2000 mm<2>/s, or more than 4000 mm<2>/s. Moreover, the viscosity modifying additives may at the same time be selected so as to maintain a kinematic viscosity of the anti-icing liquid, at temperatures above 30<º>C, of e.g. less than 600 mm<2>/s, less than 400 mm<2>/s, less than 200 mm<2>/s, or less than 100 mm<2>/s. Again with reference to Fig. 2a, there is also provided a train anti-icing system 10 comprising a container 32 containing such train anti-icing liquid, and a spray nozzle arrangement 16 operatively connected so as to receive anti-icing liquid from said container 32. There is also provided a method of anti-icing a train, the method comprising spraying such anti-icing liquid onto the train. The method may further comprise maintaining and spraying the anti-icing liquid at an elevated treatment temperature, as described with reference to Fig. 2a, and allowing the liquid to be immediately cooled down below -10<º>C by the train.

The inventions have mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims. For example, a spray nozzle arrangement 16 comprising multiple spray nozzles has been illustrated. As an alternative, the spray nozzle arrangement may comprise only one single spray nozzle. 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. 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 a vehicle on tracks (12); an anti-icing liquid supply line (34; 134) connected between the anti-icing liquid storage tank (32; 132) 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); and an anti-icing liquid moving arrangement (36; 136) configured to move anti-icing liquid from the storage tank (32; 132), along the anti-icing liquid supply line (34; 134), to the spray nozzle arrangement (16), the anti-icing system (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 to be pressurized by the anti-icing liquid moving arrangement (36; 136), so as to allow boosting a flow of anti-icing liquid to the spray nozzle arrangement (16); and 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) for controlling a return flow of anti-icing liquid from the hydropneumatic tank (44) to the storage tank (32).

2. The train anti-icing system according to claim 1 , wherein the return valve (60) is temperature controlled, and configured to open when a temperature of the anti-icing liquid falls below a lower limit temperature.

3. The train anti-icing system according to any of the previous claims, wherein the hydropneumatic tank (44) is configured to be pre-loaded with a gas pressure of between 3 and 8 bar, and more preferably between 4 and 6 bar.

4. The train anti-icing system according to any of the previous claims, wherein the supply line (34) is provided with a pressure regulator (42), downstream of the hydropneumatic tank (44), configured to limit the anti-icing liquid pressure downstream of the pressure regulator (42) to a working pressure between 3 and 8 bar, and preferably between 4 and 6 bar.

5. The train anti-icing system according to any of the previous claims, wherein the anti-icing liquid moving arrangement comprises a supply pump (36) connected to the anti-icing liquid supply line (34) and configured to pump anti-icing liquid from the storage tank (32), along the anti-icing liquid supply line (34), to the spray nozzle arrangement (16), wherein the hydropneumatic tank (44) is connected to the anti-icing liquid supply line (34) downstream of the supply pump (36) and upstream of the supply valve arrangement (17).

6. The train anti-icing system according to claim 5, wherein the supply pump (36) is controlled based on a detected pressure downstream of the supply pump (36).

7. The train anti-icing system according to any of the previous claims, wherein the hydropneumatic tank (44) comprises a membrane (46) dividing the hydropneumatic tank (44) into a gas space (44b) and an anti-icing liquid space (44a).

8. The train anti-icing system according to any of the previous claims, further comprising a collection tray (18) for collecting spent anti-icing liquid falling from the vehicle (12), and a return line (64) for anti-icing liquid that has been collected by the collection tray (18).

9. The train anti-icing system according to any of the previous claims, further comprising a heater system configured to heat the anti-icing liquid of the storage tank (32) to a treatment temperature, the heater system comprising a heater (52) and a heater recirculation line (50) configured to transfer antiicing liquid from the storage tank (32) to the heater (52) and back to the storage tank (32).

10. A method of anti-icing a vehicle on tracks, comprising moving anti-icing liquid into a hydropneumatic tank (44; 132); detecting the arrival of a vehicle on tracks (12) to be treated; based on the position of the vehicle on tracks (12), operating a supply valve arrangement (17) downstream of the hydropneumatic tank (44; 132) so as to spray anti-icing liquid onto the vehicle (12); and operating a return valve (60) downstream of the hydropneumatic tank (44) so as to return anti-icing liquid to a storage tank (32) upstream of the hydropneumatic tank (44; 132) for re-heating.

11. The method according to claim 10, 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 the hydropneumatic tank (44); and operating the return valve (60) based on the detected temperature.