SE1350548A1

SE1350548A1 - Tow Display System

Info

Publication number: SE1350548A1
Application number: SE1350548A
Authority: SE
Inventors: Anders Larsson
Original assignee: Nordic Ground Support Equipment Ip Ab
Priority date: 2013-05-06
Filing date: 2013-05-06
Publication date: 2014-11-07
Also published as: EP2994354A4; EP2994354A1; CN205327022U; WO2014182226A1

Abstract

16 Abstract A train anti-icing system (10) comprises a spray nozzle arrangement(16) for spraying serviceable anti-icing liquid at a treatment temperature ontoa vehicle on tracks; a collection tray (18) for collecting spent anti-icing liquidfalling from the vehicle; a preparation vessel (62) for preparing serviceableanti-icing liquid to be sprayed onto the vehicle; a spent anti-icing liquid tank(44) for receiving and storing spent anti-icing liquid collected by the collectiontray (18); an ingredient tank (54) for storing anti-icing liquid concentrate; aspent anti-icing liquid supply line (66) for supplying spent anti-icing liquid fromthe spent anti-icing liquid tank (44) to the preparation vessel (62); and aningredient supply line (64) for supplying anti-icing liquid concentrate from theingredient tank (54) to the preparation vessel (62). Suggested figure for publication: Fig. 2

Description

AWAPATENT AB Nordic Ground Support Equipment IPABKontor/Handläggare Ansökningsnr Vår referens Växjö/Ola Gunnarsson/OGN SE-210630231 TRAIN ANTI-ICING SYSTEM Field of the invention The present invention relates to a train anti-icing system comprising aspray nozzle arrangement for spraying anti-icing liquid onto a vehicle ontracks and a collection tray for collecting spent anti-icing liquid falling from thevehicle.

Backqround of the invention ln cold climate, ice build-up on trains is a safety risk, and thereforetrains frequently need to be anti-iced. WO 2013/043090 discloses a train anti-icing system for reducing the icing of a vehicle on tracks.

There is a need for a train anti-icing system with reduced operation and maintenance costs.

Summarv of the inventionlt 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 atrain anti-icing system comprising a spray nozzle arrangement for sprayingserviceable anti-icing liquid at a treatment temperature onto a vehicle ontracks; a collection tray for collecting spent anti-icing liquid falling from thevehicle; a preparation vessel for preparing serviceable anti-icing liquid to besprayed onto the vehicle; a spent anti-icing liquid tank for receiving andstoring spent anti-icing liquid collected by the collection tray; an ingredienttank for storing anti-icing liquid concentrate; a spent anti-icing liquid supplyline for supplying spent anti-icing liquid from the spent anti-icing liquid tank tothe preparation vessel; and an ingredient supply line for supplying anti-icingliquid concentrate from the ingredient tank to the preparation vessel. ln such asystem, energy consumption may be reduced, since de-watering of collected,spent anti-icing liquid to be re-used will not be necessary. This reduces theoperating cost. Moreover, compared to prior systems, the interval for re-filling the system may be significantly increased, such that the maintenance cost isreduced.

According to an embodiment, the treatment temperature is betweenabout 10°C and 50°C.

According to an embodiment, the train anti-icing system furthercomprises a heater configured to heat the serviceable anti-icing liquid of thepreparation vesse| to the treatment temperature. Heating may be performedinside or outside the preparation vesse|, and the serviceable anti-icing liquidmay be maintained at an e|evated temperature inside the preparation vesse|.

According to an embodiment, the train anti-icing system furthercomprises a heater configured to heat the spent anti-icing liquid of the spentanti-icing liquid tank to a temperature lower than the treatment temperature.By keeping the spent anti-icing liquid at a lower temperature than thatrequired for performing anti-icing, energy is saved. According to anembodiment, said lower temperature is between -10°C and 0°C. Preferably,said lower temperature is a freeze-preventing temperature. More preferred,said lower temperature is less than 10°C above the freezing point of the spentanti-icing liquid. Heating may be performed inside or outside the spent anti-icing liquid tank.

According to an embodiment, the preparation vesse| is smaller than thespent anti-icing liquid tank. By keeping a large portion of the liquid stored inthe system at a temperature below the treatment temperature, energy issaved.

According to an embodiment, the train anti-icing system is configuredto store the anti-icing liquid concentrate in the ingredient tank at atemperature lower than the treatment temperature, and preferably unheated.By storing the anti-icing liquid concentrate unheated, or at least at a lowertemperature than that required for performing anti-icing, energy is saved.

According to an embodiment, the preparation vesse| is smaller than theingredient tank. Again, by maintaining a large portion of the liquid stored inthe system at a temperature below the treatment temperature, energy issaved.

According to an embodiment, the train anti-icing system furthercomprises a controller configured to, if the amount of serviceable anti-icingliquid in the preparation vessel falls below a threshold value, initiate a transferof a first selected volume of spent anti-icing liquid from the spent anti-icingliquid tank to the preparation vessel; and initiate a transfer of a secondselected volume of anti-icing liquid concentrate from the ingredient tank to thepreparation vessel. Thereby, the amount and concentration of serviceableanti-icing liquid in the preparation vessel may be maintained within selectedboundaries at all times.

According to an embodiment, the train anti-icing system furthercomprises a glycol concentration sensor configured for sensing theconcentration ofglycol of the spent anti-icing liquid in the spent anti-icingliquid tank. Thereby, information from the glycol concentration sensor may beused for determining suitable amounts of liquid to be added to the preparationvessel from the spent anti-icing liquid tank and the ingredient tank,respectively.

According to an embodiment, the glycol concentration sensor islocated outside the spent anti-icing liquid tank, and the train anti-icing systemfurther comprises a spent anti-icing liquid sampling line for transferring asample of spent anti-icing liquid from the spent anti-icing liquid tank to theglycol concentration sensor; and a serviceable anti-icing liquid sampling linefor transferring a sample of serviceable anti-icing liquid from the preparationvessel to the glycol concentration sensor. This facilitates measuring the glycolconcentration in each of the preparation vessel and the spent anti-icing liquidtank. Thereby, it is possible to more accurately optimize the mixing of spentanti-icing liquid and anti-icing liquid concentrate into the preparation vessel,and to verify the quality of the serviceable anti-icing liquid in the preparationvessel before spraying onto a vehicle. The anti-icing system may alsocomprise an anti-icing liquid concentrate sampling line for transferring asample of anti-icing liquid concentrate from the ingredient tank to the glycolconcentration sensor. Thereby, the quality of the anti-icing liquid concentratemay be verified.

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 a vehicle on tracks, the method comprising collecting spent anti-icingliquid and storing it in a spent anti-icing liquid tank; preparing serviceable anti-icing liquid by transferring collected, spent anti-icing liquid from the spent anti-icing liquid tank to a preparation vessel and transferring anti-icing liquidconcentrate from an ingredient tank to the preparation vessel; and sprayingserviceable anti-icing liquid at a treatment temperature onto the vehicle.

According to an embodiment, the serviceable anti-icing liquid inside thepreparation vessel is maintained at the treatment temperature, and the spentanti-icing liquid inside the spent anti-icing liquid tank is maintained at atemperature below the treatment temperature.

According to an embodiment, the method further comprisesmaintaining a relatively smaller amount of serviceable anti-icing liquid attreatment temperature in the preparation vessel; and maintaining a relativelylarger amount of spent anti-icing liquid below treatment temperature in thespent anti-icing liquid tank.

According to an embodiment, the method further comprisesdetermining the amount of serviceable anti-icing liquid in the preparationvessel; and based on said determination, initiating a transfer of a first selectedvolume of spent anti-icing liquid from the spent anti-icing liquid tank to thepreparation vessel and initiating a transfer of a second selected volume ofanti-icing liquid concentrate from the ingredient tank to the preparation vessel.

According to an embodiment, said first and second selected volumesare selected based on the concentration of glycol of the spent anti-icing liquidin the spent anti-icing liquid tank.

According to an embodiment, the method further comprisesalternatingly sampling the spent anti-icing liquid and the serviceable anti-icingliquid for determining their respective glycol concentrations using a singleglycol concentration sensor.

Brief description of the drawinqs The above, as well as additional objects, features and advantages ofthe present invention, will be better understood through the followingillustrative and non-limiting detailed description of preferred embodiments ofthe present invention, with reference to the appended drawings, where thesame reference numerals will be used for similar elements, wherein: Fig. 1 is a diagrammatic view in perspective of an train anti-icingsystem; and Fig. 2 is a diagrammatic view of a re-circulation plant of the train anti-icing system of Fig. 1.

Detailed description of the exemplarv embodiments Fig. 1 schematically illustrates a train anti-icing system 10 for reducingthe 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 ofanti-icing liquid on the surface of the train during or after de-icing, or withoutprior de-icing. The system 10 is configured as a drive-through system, i.e. atrain 12, arriving on tracks 14 from the upper left corner of Fig. 1, passesthrough the system 10 without having to stop during the de-/anti-icingprocess.

The anti-icing system 10 comprises a spray nozzle arrangement 16 forspraying an anti-icing liquid onto the train 12, and a collection trayarrangement 18 for collecting spent anti-icing liquid dripping from the train 12.The system 10 may also be provided with a sensor (not shown) fordetermining locations, relative to the spray nozzle arrangement 16, of portionsof the train 12 to be selectively sprayed, e.g. in the manner described in WO2013/043090. Thereby, spraying may be focussed onto the train portionsmost sensitive to icing, such as wheel units.

Typically, a serviceable anti-icing liquid would be a liquid having afreezing 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 liquidor 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, theanti-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.

Ethylene glycol, propylene glycol, other alcohols, salt, and sugar are the mostcommon anti-icing liquid ingredients in the art, and may be used for preparingserviceable 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 trayarrangement 18 extends along a relatively short spray zone 20, at which thespray nozzle arrangement 16 is located, and a somewhat longer collectionzone 22, along which no substantive spraying of anti-icing liquid occurs. Thecollection tray arrangement 18 comprises three collection trays 18a, 18b, 18cextending along the rails 14. Two collection trays 18a, 18b extend along thesides of the tracks 14, while a third collection tray 18c extends between thetracks 14. A drain arrangement 26 comprises a set of drains 26a-c located atthe bottoms of the respective collection trays 18a-c. The drain arrangement26 allows spent anti-icing liquid to be collected from the collection trayarrangement 18 and transferred to a re-circulation plant 28, which may belocated within a housing formed by e.g. a cargo container 30. Thereby, theanti-icing system 10 may be prepared or assembled at a central site, andquickly transported to and installed at a de-icing site when needed.

Turning now to Fig. 2, only a single tray 18 and a single drain 26 areillustrated. The spray nozzle arrangement 16 comprises a plurality of spraynozzles 36. A valve arrangement 38, comprising a plurality of valves (notillustrated), is operated by a controller 40. The controller 40 controls, via thevalve arrangement 38, the flow of anti-icing liquid to different portions of thespray nozzle arrangement 16 in such a manner that different spray patternsmay be selectively obtained.

The re-circulation plant 28 (Fig. 1) will now be described in more detail.

Collected, spent anti-icing liquid is pumped from the drain arrangement 26,via a filter 42 for removing solid dirt particles, to a spent anti-icing liquid tank44 for storing spent anti-icing liquid. The spent anti-icing liquid tank 44 is provided with a spent anti-icing liquid temperature sensor 46, for sensing thetemperature of the spent anti-icing liquid in the tank 44, and a spent anti-icingliquid tank level sensor 48, for sensing the amount of spent anti-icing liquid inthe tank 44. Temperature and level signals from the sensors 46, 48 aretransmitted to the controller 40. The controller 40 also controls a spent anti-icing liquid heater 50, which is located outside the spent anti-icing liquid tank44. Based on the temperature of the spent anti-icing liquid in the spent anti-icing liquid tank 44, spent anti-icing liquid is pumped from the tank 44 to theheater 50, heated by the heater 50, and then returned to the tank 44.Thereby, the temperature of the spent anti-icing liquid in the spent anti-icingliquid tank 44 may be kept at a freeze-preventing temperature, i.e. above thefreezing point of the spent anti-icing liquid, even if the ambient temperatureoutside the tank 44 falls below the freezing point. By way of example, a spentanti-icing liquid comprising about 75% - 85% water and 15% - 25% propyleneglycol has a typical freezing point of between about -5°C and -10°C; for sucha spent anti-icing liquid, the controller 40 may be configured to operate theheater 50 when the temperature falls below a lower spent anti-icing liquid limittemperature, which may be between about -10°C and 0°C. A discharge line52 allows emptying the spent anti-icing liquid tank 44. As an alternative orcomplement to heating spent anti-icing liquid in a separate heater 50 outsidethe tank 44, a heater may be located in the tank 44.

The re-circulation plant 28 further comprises an ingredient tank 54 forstoring anti-icing liquid concentrate, such as concentrated propylene glycol orhighly concentrated salt brine. The ingredient tank 54 is provided with an anti-icing liquid concentrate temperature sensor 56, for sensing the temperature ofthe anti-icing liquid concentrate in the tank 54, and an ingredient tank levelsensor 58, for sensing the amount of anti-icing liquid concentrate in theingredient tank 54. Again, temperature and level signals from the sensors 56,58 are transmitted to the controller 40. A refilling line 60 allows topping up theingredient tank 54 with anti-icing liquid concentrate.

A preparation vessel 62 allows for preparing serviceable anti-icingliquid to be sprayed onto the train 12. The preparation vessel 62 is connectedto the ingredient tank 54 via an ingredient supply line 64, which allows pumping anti-icing liquid concentrate from the ingredient tank 54 to thepreparation vessel 62. The preparation vessel 62 is also connected to thespent anti-icing liquid tank 44 via a spent anti-icing liquid supply line 66, whichallows pumping spent anti-icing liquid from the spent anti-icing liquid tank 44to the preparation vessel 62. The preparation vessel 62 is provided with aserviceable anti-icing liquid temperature sensor 68, for sensing thetemperature of the serviceable anti-icing liquid in the preparation vessel 62,and a preparation vessel level sensor 70, for sensing the amount ofserviceable anti-icing liquid in the preparation vessel 62. Again, temperatureand level signals from the sensors 68, 70 are transmitted to the controller 40.lf the amount of serviceable anti-icing liquid in the preparation vessel 62 reaches a lower limit, serviceable anti-icing liquid is prepared in thepreparation vessel 62 by pumping selected amounts of liquid to thepreparation vessel 62 from the ingredient tank 54 and the spent anti-icingliquid tank 44, respectively. The respective amounts of anti-icing liquidconcentrate and spent anti-icing liquid are selected by the controller 40 suchthat the resulting mixture in the preparation vessel 62 will hold the desiredanti-icing ingredient concentration to form a serviceable anti-icing liquid.Thereby, anti-icing liquid may be regenerated in a non-evaporative manner.The amounts transferred from the respective tanks 44, 54 may be calculatedby the controller 40 based on the signals from the respective level sensors48, 58. Non-evaporative regeneration may be particularly beneficial in anti-icing systems 10 configured to focus spraying on selected portions along atrain 12 which are particularly prone to icing, such as wheel units. This is dueto such selective anti-icing systems consuming particularly small amounts ofserviceable anti-icing liquid, such that the collected, spent anti-icing liquid willbe particularly highly diluted by melt water.

The controller 40 also controls a serviceable anti-icing liquid heater 72,which is located outside the preparation vessel 62. Based on the temperatureof the serviceable anti-icing liquid in the preparation vessel 62, serviceableanti-icing liquid is pumped from the preparation vessel 62 to the heater 72,heated, and then returned to the preparation vessel 62. Thereby, thetemperature of the serviceable anti-icing liquid in the preparation vessel 62 may be kept at a treatment temperature, i.e. at a temperature suitable for de-icing a train 12, even if the ambient temperature outside the preparationvessel is low. By way of example, a suitable treatment temperature may bebetween about 10°C and 50°C, and preferably above 20°C. The controller 40may be configured to operate the heater 72 when the temperature falls belowa lower treatment temperature limit, which may be between about 10°C and50°C. As an alternative or complement to heating serviceable anti-icing liquidin a separate heater 72 outside the preparation vessel 62, a heater may belocated in the preparation vessel. Maintaining only the serviceable anti-icingliquid heated to an elevated treatment temperature, while maintaining anti-icing liquid concentrate and spent anti-icing liquid at a lower temperature,saves heating energy. Alternatively, the serviceable anti-icing liquid may bekept at ambient temperature in the preparation vessel, and may be heatedelsewhere by a separate heater when it is to be sprayed onto a train 12. Stillalternatively, the serviceable anti-icing liquid may be sprayed onto the train 12without having been heated, i.e. at ambient temperature, for merely formingan ice-repellent coating on the surface of the vehicle. lt may be the case that not all spent anti-icing liquid collected by thecollection tray 18 is needed for preparing serviceable anti-icing liquid.Therefore, from time to time, it may be desired to tap off some spent anti-icingliquid from the spent anti-icing liquid tank 44 via the discharge line 52, toprevent overfilling of the spent anti-icing liquid tank 44. The spent anti-icingliquid tank 44 preferably has a capacity of at least 4 m3 to allow performing anumber of anti-icing operations between tapping off. The preparation vessel62 preferably has a capacity of at least 0,5 m3, which is typically more thansufficient for anti-icing a train. Preferably, the preparation vessel 62 has acapacity of less than 3 m3 in order to limit the heating power required formaintaining the serviceable anti-icing liquid at treatment temperature.Preferably, the spent anti-icing liquid tank 44 and the preparation vessel 62are thermally insulated to minimize heat dissipation therefrom. The ingredienttank 54 typically does not need to be substantially heated.

After an anti-icing operation, about 10 - 100 liters of serviceable anti-icing liquid typically remains on the train 12, and is lost from the anti-icing system 10 as the train 12 leaves the anti-icing system 10. Hence, preferably,the ingredient tank has a capacity of at least 1 m3 to allow performing anumber of anti-icing operations between refillings via the refilling line 60.

An ingredient concentration sensor 74, for determining theconcentration of an anti-icing ingredient, is connected to the spent anti-icingliquid tank 44 via a spent anti-icing liquid sampling line 76. By way ofexample, the ingredient concentration sensor 74 may be a propylene glycolconcentration sensor. The concentration value determined by the ingredientsensor 74 is transmitted to the controller 40, and may be used by thecontroller 40 for calculating the ratio of spent anti-icing liquid and anti-icingliquid concentrate to be transferred to the preparation tank 62 for obtainingserviceable anti-icing liquid of the desired ingredient concentration. lf usingpropylene glycol as the anti-icing ingredient, a propylene glycol concentrationof the serviceable anti-icing liquid of between 40% and 60% may typically bedesked.

The ability to measure the ingredient concentration of the spent anti-icing liquid in the spent anti-icing liquid tank 44 also makes it possible todetermine the freezing point of the spent anti-icing liquid in the tank 44.Thereby, the controller 40 may select the lower limit temperature of the spentanti-icing liquid based on the ingredient concentration of the spent anti-icingliquid. This makes it possible to even further lower the temperature at whichthe spent anti-icing liquid is stored to a temperature just above the freezingpoint. The ingredient concentration sensor 74 is also connected to thepreparation vessel via a serviceable anti-icing liquid sampling line 76.Thereby, the ingredient concentration of the serviceable anti-icing liquid insidethe preparation vessel may also be determined by the controller 40, e.g. byalternatingly transferring liquid from the preparation vessel 62 and the spentanti-icing liquid tank, respectively, to the ingredient concentration sensor 74.This permits fine-tuning the ingredient concentration of the serviceable anti-icing liquid. The ingredient concentration sensor 74 may also be connected tothe ingredient tank 54 via an anti-icing liquid concentrate sampling line (notshown). Thereby, it is possible to verify the quality of the anti-icing liquidconcentrate in the tank 54. 11 The invention has mainly been described above with reference to a fewembodiments. However, as is readily appreciated by a person skilled in theart, other embodiments than the ones disclosed above are equally possiblewithin the scope of the invention, as defined by the appended patent claims.For example, a single controller 40, performing several different functions,has been disclosed. Clearly, separate controllers may be used for thosedifferent functions, such as for operating different heaters. Moreover, a spraynozzle arrangement 16 comprising multiple spray nozzles has beenillustrated. As an alternative, the spray nozzle arrangement may compriseonly one single spray nozzle. Even though each of the containers 44, 54, 62has been illustrated as a closed container, any of them could alternatively bean open container. The invention may be used for many different types ofvehicles on tracks, such as trams, and is not limited to trains only.

Claims

12 i

1. A train anti-icing system comprising a spray nozzle arrangement (16) for spraying serviceable anti-icingliquid at a treatment temperature onto a vehicle on tracks (12); and a collection tray (18) for collecting spent anti-icing liquid falling from thevehicle (12), the train anti-icing system being characterized in comprising a preparation vessel (62) for preparing serviceable anti-icing liquid tobe sprayed onto the vehicle (12); a spent anti-icing liquid tank (44) for receiving and storing spent anti-icing liquid collected by the collection tray (18); an ingredient tank (54) for storing anti-icing liquid concentrate; a spent anti-icing liquid supply line (66) for supplying spent anti-icingliquid from the spent anti-icing liquid tank (44) to the preparation vessel (62);and an ingredient supply line (64) for supplying anti-icing liquid concentratefrom the ingredient tank (54) to the preparation vessel (62).

2. The train anti-icing system according to claim 1, further comprising aheater (72) configured to heat the serviceable anti-icing liquid of thepreparation vessel (62) to the treatment temperature.

3. The train anti-icing system according to any of the previous claims,further comprising a heater (50) configured to heat the spent anti-icing liquidof the spent anti-icing liquid tank (44) to a temperature lower than thetreatment temperature.

4. The train anti-icing system according to claim 3, wherein thepreparation vessel (62) is smaller than the spent anti-icing liquid tank (44).

5. The train anti-icing system according to any of the previous claims,wherein the system (10) is configured to store the anti-icing liquid concentrate 13 in the ingredient tank (54) at a temperature lower than the treatmenttemperature, and preferably unheated.

6. The train anti-icing system according to claim 5, wherein thepreparation vessel (62) is smaller than the ingredient tank (54).

7. The train anti-icing system according to any of the previous claims,further comprising a controller (40) configured to, if the amount of serviceableanti-icing liquid in the preparation vessel (62) falls below a threshold value,initiate a transfer of a first selected volume of spent anti-icing liquidfrom the spent anti-icing liquid tank (44) to the preparation vessel (62); andinitiate a transfer of a second selected volume of anti-icing liquidconcentrate from the ingredient tank (54) to the preparation vessel (62).

8. The train anti-icing system according to any of the previous claims,further comprising a glycol concentration sensor (74) configured for sensingthe concentration of glycol of the spent anti-icing liquid in the spent anti-icingliquid tank (44).

9. The train anti-icing system according to claim 8, wherein the glycolconcentration sensor (74) is located outside the spent anti-icing liquid tank(44), the system further comprising a spent anti-icing liquid sampling line (76) for transferring a sample ofspent anti-icing liquid from the spent anti-icing liquid tank (44) to the glycolconcentration sensor (74); and a serviceable anti-icing liquid sampling line (78) for transferring asample of serviceable anti-icing liquid from the preparation vessel (62) to theglycol concentration sensor (74).

10. A method of anti-icing a vehicle on tracks, comprising collecting spent anti-icing liquid and storing it in a spent anti-icing liquidtank (44);preparing serviceable anti-icing liquid by 14 transferring collected, spent anti-icing liquid from the spent anti-icing liquid tank (44) to a preparation vessel (62) and transferring anti-icing liquid concentrate from an ingredient tank(54) to the preparation vessel (62); and spraying serviceable anti-icing liquid at a treatment temperature onto the vehicle (12).

11. The method according to claim 10, wherein the serviceable anti-icingliquid inside the preparation vessel (62) is maintained at the treatmenttemperature, and the spent anti-icing liquid inside the spent anti-icing liquidtank (44) is maintained at a temperature below the treatment temperature.

12. The method according to claim 11, further comprising maintaining a relatively smaller amount of serviceable anti-icing liquidat treatment temperature in the preparation vessel (62); and maintaining a relatively larger amount of spent anti-icing liquid belowtreatment temperature in the spent anti-icing liquid tank (44).

13. The method according to any of the claims 10-12, further comprisingdetermining the amount of serviceable anti-icing liquid in thepreparation vessel (62); andbased on said determination,initiating a transfer of a first selected volume of spent anti-icingliquid from the spent anti-icing liquid tank (44) to the preparation vessel (62);andinitiating a transfer of a second selected volume of anti-icing liquid concentrate from the ingredient tank (54) to the preparation vessel (62).

14.and second selected volumes are selected based on the concentration of The method according to any of the claims 10-13, wherein said first glycol of the spent anti-icing liquid in the spent anti-icing liquid tank (44).

15. The method according to ciaim 14, further comprising alternatinglysampling the spent anti-icing liquid and the serviceable anti-icing liquid fordetermining their respective giycoi concentrations using a single giycoi concentration sensor (74).