Abstract:
The invention relates to a device for cleaning the pipes of the drinking water circuit of an aircraft, in which the device is independent of the aircraft and is connected to the circuit intermittently and supplied with liquid. The device is characterized in that it comprises a mobile chassis supporting a plurality of functional sub-assemblies required to produce a hot liquid, including a closed-furnace gas condensing boiler. The invention can be used to clean the pipes of aircraft.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a 371 national stage application of International Application PCT/FR2014/051752, filed Jul. 8, 2014, and claims the priority of French Application No. 1357155, filed on Jul. 19, 2013. 
     FIELD OF APPLICATION OF THE INVENTION 
     The present invention relates to the field of aircraft and in particular adaptations for cleaning pipes in the drinking-water system of an aircraft in the best conditions. 
     DESCRIPTION OF THE PRIOR ART 
     There exist in the prior art methods for treating the drinking-water circuit of an aircraft that propose circulating, in said network, a liquid and in particular water, at high temperature. 
     Thus, for example, the document WO 2010/14924 proposes a method for treating the drinking-water circuit of an aircraft, said circuit being of the type comprising at least one storage tank, a plurality of pipes offering a plurality of inlet and outlet points for water, and filtration means comprising removable filtration cartridges equipping certain pipes, remarkable in that it consists of
         not removing the filtration cartridges,   filling said tank by means of a treatment liquid,   circulating said treatment liquid, which is water brought to high temperature, in the circuit with the cartridges installed.       

     Another document WO 2012/168645 proposes a method for the dynamic cleaning of the conduits supplying drinking water for a vehicle, consisting of creating a shock wave in the conduit to be cleaned, 
     remarkable in that it consists of:
         partially filling a space with a liquid,   filling the space not occupied by the liquid, with pressurised gas,   releasing the liquid through a contraction communicating with the end of said conduit or conduits to be cleaned, the other end of which is open, while maintaining the pressure, so as:   to create an accelerated movement of the liquid firstly and of the mixture of gas and liquid created secondly, and then   to generate a shock wave, once the space is emptied, a shock wave that propagates through the mixture.       

     According to one embodiment, said liquid is water raised to high temperature. 
     It is also known in the prior art, the condensing gas boiler technology such as that described in a fixed application for the heating of the water of a swimming pool in the document DE 20 2005 012380. 
     DESCRIPTION OF THE INVENTION 
     The applicant has carried out research on a device for producing hot liquid making it possible to implement not only the methods described above but also any cleaning method able to use a hot liquid. To do this, the applicant has identified several criteria, including the following:
         the liquid must be able to be raised to high temperature very quickly,   the volume of liquid raised to high temperature must be large,   the flow rate of liquid must also be great,   the device must have a volume enabling it to be transported in an aircraft,   the device must be able to be used in the workshop where the aircraft to be treated is situated and close to the latter,   the device must be able to move in the workshop where the aircraft to be treated is situated.       

     This research resulted in the design and production of a device for cleaning the pipes in the drinking-water system of an aircraft, said device being independent of said aircraft and being connected to said system occasionally and being supplied with liquid, 
     is remarkable in that it comprises a mobile chassis supporting a plurality of functional subassemblies necessary for the production of a hot liquid, including a condensing gas boiler with a sealed combustion chamber. 
     The use of this type of boiler is particularly original in the case of a mobile device since it is an item of equipment that is conventionally fixed. 
     Despite this, the applicant proposes using such a technology in that they propose the power necessary for the rapid heating of a large volume of liquid able to flow at high rate. 
     Another particularly advantageous feature of this boiler lies in the fact that the exhaust gases that it produces have a low temperature, which allows use thereof in a closed hangar close to an aircraft. Indeed the other technologies are likely to produce fume gases at very high temperatures, preventing them from being used in an aeronautical workshop or close by. 
     Such a boiler technology is particularly advantageous in that it allows adjustment of the flow rate as well as adjustment of the boiler output. It is then possible to heat the water for purposes of treating a drinking-water circuit on several types of aircraft. 
     According to a particularly advantageous feature, said liquid is water. 
     Given the need for a mobile configuration and the use of an operation in an aeronautical workshop, the gas supply must be portable by bottles. The standards require that each bottle does not exceed a certain volume, the device is remarkable in that it accommodates several gas bottles proposing a sufficient volume of gas able to supply the energy necessary for the production of a large quantity of heat over a very short period. 
     The presence of a plurality of gas bottles requiring a plurality of pressure-reducing valves and the requirement by the boiler for a constant supply of a large quantity of gas may have negative consequences for the device, for example:
         an offset in the pressure reduction,   frosting of the pipes,   the presence of condensation water in the pipes,   a volume of gas not always available when the boiler needs it.       

     In order to remedy this drawback, the applicant has advantageously designed an intermediate gas reservoir positioned between the boiler and the pressure-reducing valve or valves associated with one or more gas bottles for receiving the gas coming to be expanded and to supply the boiler. When there are several bottles, this reservoir thus receives the expanded gas issuing from each bottle and provides mixing thereof for greater homogeneity. It also creates a volume of gas that is always available whatever the output of the boiler. Finally, it provides decantation of the condensation created by the pressure reduction. 
     These features make it possible to use a condensing gas boiler with sealed combustion chamber in the best conditions and even makes it possible to oversize it in order to be able to use the device whatever the size of the aircraft. 
     According to a first solution for implementation, the boiler heats a liquid in a primary circuit exchanging its heat with a liquid situated in a vessel. 
     In a second solution, the boiler heats a liquid in a primary circuit that exchanges with a secondary circuit inside an exchanger. 
     In a third solution, the liquid in the secondary circuit is preheated by means of a liquid in the primary circuit emerging from the exchanger before the liquid in the secondary circuit passes into the exchanger. 
     The discharge and supply of air in this boiler have also been particularly studied in order in particular to meet the constraints of compactness and operation in an aeronautical workshop. Thus, according to another feature, said boiler is equipped with a dual-flow discharge flue allowing both discharge of the exhaust and entry of fresh air. 
     According to another particularly advantageous feature of the invention, the device also comprises a module for metering a treatment product that is injected into the heated liquid discharged from the device before it is introduced into the drinking-water system of the aircraft. 
     According to another particularly advantageous feature of the invention, the device comprises a module for connection to the drinking-water system of the aircraft equipped with a valve of which the selection of its position makes it possible:
         to drain the water or liquid present in the drinking-water system of the aircraft,   to stop the injection of hot liquid without creating an air vacuum,   to drain the liquid present in the device without sending it to the aircraft.       

     When it is supplied by the domestic water system, the device also comprises a module for accelerating water issuing from the domestic network in order to increase the filling speed of the aircraft system. It is the pressurisation means of the aircraft that drain the system once its reservoir or reservoirs have been filled with hot water. 
     The device further comprises a mobile chassis combining, in a very small volume, the various functional modules described above. This is because, in order to be able to fit in the baggage hold of an aircraft transporting passengers, the weight of the device is less than 200 kilogrammes and has a height less than or equal to 1.10 m. The functional and structural choices described above meet this requirement for compactness. The mobile chassis is equipped with damped wheels. In addition, the functional modules are fixed to the chassis with vibration-damping means, the dimensions are calculated to provide expansion clearances and the materials used are resistant to high temperature. 
     The fundamental concepts of the invention having just been disclosed above in their most elementary form, other details and features will emerge more clearly from a reading of the following description and with regard to the accompanying drawings, giving by non-limitative example several embodiments of a device according to the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic drawing of a device coming to be connected to the drinking-water network of an aircraft; 
         FIG. 2  is a functional diagram of a first embodiment; 
         FIG. 3  is a functional diagram of a second embodiment; 
         FIG. 4  is a functional diagram of a third embodiment; 
         FIG. 5  is a schematic drawing of a rear perspective view of the second embodiment of the device without its cladding walls; 
         FIG. 6  is a schematic drawing of a front perspective view of the device of  FIG. 5 ; 
         FIG. 7  is a schematic drawing of an external front view of the intermediate reservoir; 
         FIG. 8  is a functional diagram of the connection module. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     As illustrated by the drawing in  FIG. 1 , the device D of the invention is a device for producing hot water for the purpose of treating the system R of drinking-water pipes of an aircraft A. This device D, independent of said aircraft A, comprises a mobile chassis for being moved in a workshop and comes to be connected to the system R occasionally, that is to say during the maintenance operation on the aircraft A that comprises the treatment of said system. This device D is supplied with water by the domestic system S available in the workshop. In addition, it is connected to the electrical system E. 
     Such a device must provide a production of hot water on the basis of a flow rate of 1000 liters per hour. Depending on the size of the aircraft A and the number of phases in the treatment method, the flow rate, the number of thousands of liters of water and the number of hours of the operation may vary. 
     The following description of the device is common to the various embodiments illustrated. 
     The device D comprises, on the same mobile chassis C (cf.  FIG. 5 ), a plurality of functional subassemblies necessary for the rapid production of hot water in large volumes. 
     To do this, the device comprises a heating subassembly  100  comprising a condensing gas boiler with sealed combustion chamber  110 . This boiler  110  is supplied via a conduit  120  by a gas-supply subassembly  200 . 
     This gas-supply subassembly  200  accommodates two gas bottles  210  and  220  each associated with a valve  211  and  221  bringing the gas to a pressure-reducing valve  230 . 
     One particularly advantageous feature of the invention lies in the presence of an intermediate gas reservoir  240  supplied by the gas passing through the pressure-reducing valve  230  and supplying the boiler  110  by means of a flow-rate regulator  250 . By being positioned between the boiler  110  and the pressure-reducing valve  230  associated with the bottles  210  and  220 , this reservoir  240  serves as a buffer reservoir guaranteeing a good mixing of the gas and a volume of gas constantly available for the boiler  110  whatever its output. As illustrated by the drawing in  FIG. 7 , the reservoir  240  is in a substantially cylindrical form having a bottom outlet orifice  241  and a top inlet orifice  242  for the gas. It also has an orifice  243  for decanting the condensation water droplets present in the reservoir  240 . To assume this function, said reservoir  240  is positioned vertically as illustrated in the drawing in  FIG. 5 . Furthermore, according to another particularly advantageous feature, this reservoir  240  is up against a hot-water pipe increasing the temperature difference leading to condensation. 
     The boiler  110  heats water circulating in a so-called primary circuit  130  by means of a pump  131 . The pressure is monitored by a gauge  132  and the temperature is monitored by a sensor  133 . This primary circuit  130  further comprises a compensation vessel  134 , a drain  135  and a safety valve  136 . This primary circuit  130  will exchange its heat in order to provide the heating of the water to be injected into the circuit R of the aircraft A. 
     The water in this primary circuit  130  and also the water to be heated come from the same source S and pass through a water supply subassembly  300 . This subassembly is connected to the system S and comprises an inlet valve  310  allowing or not passage of water from the system S through a filter  320 . The volume of water emerging from the filter  320  is measured by a meter  330 . A valve  340  controls the supply to the primary circuit  130 . A valve  350  controls the supply of water to be heated. 
     This water to be heated exchanges with the primary water circuit  130  in the exchange subassembly  400 . 
     The treatment water thus heated emerges in a discharge subassembly  500  that comprises an inlet valve  510  allowing or not the passage of the treatment water through a meter  520 . The temperature of the water is monitored by a gauge  530 . Between the meter  520  and the gauge  530 , a module  540  for injecting treatment product alters the heated water for the purpose of optimisation of the treatment. The latter is controlled with the meter  520 . 
     A last valve  550  controls the discharge of treatment water before it is injected into the circuit R. 
     A control subassembly  600  manages the output of the boiler and the injection of the treatment product according to the requirements and information issuing from the various sensors and gauges. Great flexibility in the management of said output is made possible because of the presence of the buffer reservoir  240  described above. 
     The heat exchange technology between the primary circuit  130  and the treatment water may differ according to the embodiments illustrated by the drawings in  FIGS. 2, 3 and 4 . 
     According to the embodiment illustrated by the drawing in  FIG. 2 , the exchange subassembly  400  consists of a water vessel  410  in which the primary circuit circulates by means of a coil. A temperature sensor  411  monitors the temperature reached. A safety pressure valve  412  equips the vessel. 
     According to the embodiment illustrated by the drawing in  FIG. 3 , the boiler  100  heats a liquid in a primary circuit  130 , which exchanges with a secondary circuit  420  in an exchanger  430 . 
     According to the embodiment illustrated by the drawing in  FIG. 4 , the secondary water circuit  420  is preheated by means of the water in the primary circuit emerging from the exchanger  430  before returning to the boiler  110  at another exchanger  440 . 
     The various functional subassemblies or the majority of their constituent elements are seen on the drawings of  FIGS. 5 and 6 , which nevertheless illustrate more particularly the second embodiment. The drawings in these figures illustrate the compactness of the device D. They illustrate in particular the compactness of the flue  111  equipping the boiler  110  and which is a dual-flow discharge flue. The chassis C consists of a set of profiled members  700  forming a parallelepiped comprising two horizontal frames  710  and  720  connected by uprights  730 . The bottom frame  710  accommodates, on its bottom face, wheels  711  in contact with the ground. This set of profiled members  700  defines an internal space accommodating the various functional subassemblies of the device D. These vertical faces are protected by cladding walls, not illustrated. The frames  710  and  720  are each protected by a protective tube  712  and  721  preventing any direct impact on the chassis C. 
     As illustrated solely by the drawings in  FIGS. 1 and 8 , a connection module  800  is interposed between the device D and the drinking-water system R of the aircraft A. This device is among other things equipped with a valve  810 , selecting the position of which makes it possible to:
         drain the water already present in the system,   stop the injection of hot water without creating an air vacuum,   drain the water already present in the device.       

     This connection module also comprises inlet  820  and outlet  830  valves as well as a temperature gauge  840  and a pressure gauge  850 . 
     As illustrated solely by the drawings in  FIGS. 1 and 2 , an auxiliary unit comprising a means for accelerating (for example a pump equipped with a booster) the flow rate of the water issuing from the domestic system S provides upstream a supply to the device D enabling it to achieve accelerated filling of the drinking-water system R of the aircraft. 
     The water-pressurisation means equipping the aircraft, once the reservoir of the aircraft is filled, themselves provide passage of the hot water into the various pipes for cleaning purposes. 
     It will be understood that the device that has just been described above and depicted, was described and depicted with a view to disclosure rather than limitation. Naturally various arrangements, modifications and improvements can be made to the above example without departing from the scope of the invention.