Patent Application
20050255762
The invention concerns ships propelled by thermodynamic machines, such as, inter alia, gas turbines and internal combustion engines discharging high-temperature gases. A particularly advantageous application is provided for aircraft carriers.
On ships of average and high tonnage, exhaust gases from thermodynamic propulsion machines, such as gas turbines and internal combustion engines, are evacuated by means of large-sized chimneys surmounting the entire upper structure of the ship. The gases thus evacuated are, at the level of these chimneys, several hundred degrees C. in temperature, approximately 500° C. This presents disadvantages common to all types of ships, such as creation of one or more hot points, risk of fire, loss of space in the upper part of the structure of the ship. For warships, there is the added disadvantage due to the loss of stealth associated with the emission of infrared waves due to temperature. Finally, for aircraft carriers, evacuation via these chimneys causes generation of currents of ascending warm air, in turn generating dangerous turbulence for planes in the landing phase and possibly in the takeoff phase.
The aim of the invention is to rectify these disadvantages by proposing another way of evacuating exhaust gases from such thermodynamic machines on ships.
To this end a first principal object of the invention is a process for exhaust and cooling of exhaust gases from thermodynamic machines provided for propelling a ship, the process consisting of cooling the exhaust gas by mixing in water on which the ship manoeuvres.
The principal embodiment provides creating natural circulation of water inside the ship, from the prow to the stern, for cool processing by mixing gases in water which is injected into the gases, such injection taking place in an inlet chamber by means of several nozzles to homogenise the mixture, this mixture being advantageously made by means of a mixing tube where the mixing pipes emerge, in the aim of lowering the pressure and thus recovering energy, and evacuation of the mixture thus obtained takes place just above the water line.
This process can be improved by using forced injection of water, for example using a circulation pump.
For the purpose of improving this mixture, it is advantageous to prolong the latter over a certain distance prior to evacuation of the mixture.
It is likewise provided to be able to extract a portion of the heat from the exhaust gases, at the outlet of the thermodynamic machines, by means of a heat exchanger, with the aim of supplying auxiliary operating power to the ship.
A second principal object of the invention is a system for exhausting and cooling exhaust gases from thermodynamic propulsion machines of a ship, mainly comprising:
The principal embodiment provides utilising a circulation pump in the water inlet pipe to force the admission of water.
It is advantageous to use a mixer head at the outlet of the inlet chamber, at the level of at least one nozzle.
According to the present invention several water nozzles are placed in the inlet chamber, the mixing pipe has a length equal to approximately six times its diameter at the outlet of the inlet chamber, a mixing tube is used at the outlet of the mixing pipe with the aim of lowering the pressure of the mixture at this level, and the mixture exits at the stern of the ship, below the water line, in such a way as not to cause rising air movements.
The invention and its technical characteristics will be better understood from reading the detailed description of an embodiment of the invention, accompanied by three figures, where respectively:
In reference to
On the other hand, exhaust gases from thermodynamic machines for propelling the ship, namely diesel or gas turbine motors are collected in a gases exhaust collector 11. The latter terminates in an inlet chamber 6, in which water nozzles 12 are also installed where the water inlet pipe 5 terminates. The inlet chamber 6 is advantageously equipped with a mixer head 13 which helps accelerate the exhaust gases. This mixer head 13 terminates in a radial plane of the inlet chamber 6 in which the water nozzles 12 terminate.
The velocity of water in the internal water inlet pipe 5 produces low pressure in the inlet chamber 6, which favours the escape of exhaust gases from the machines.
At the exit to this inlet chamber 6 is an internal mixing pipe 7 in which the double-phase mixing of exhaust gases and trapped water takes place over a certain length. In effect, to this end, this mixing pipe 7 has a length approximately six times greater than its diameter. In order to diminish the force dissipated by such a process, by means of this system, a mixing tube 8 is placed at the outlet of the mixing pipe 7 to slow down the double-phase mixing and to recover maximum pressure. During this slow-down phase, exhaust gases whose temperature at the outlet of the machines can reach 500° C., are cooled by contact to a temperature approaching that of the trapped water. It is thus envisaged to trap water at 15° and to reject double-phase mixing at 25°.
In reference to
It is notes that a system according to the invention has been installed on each side of the aircraft carrier 1. The mixing pipe 7 and the mixing tube 8 are placed outside the hull of the ship. This is only one possible embodiment of the invention, the process capable of being adapted to the power of each of the ships on which it is to be utilised, especially by adapting the number of systems to the number of machines.
With the process according to the invention it is conceivable that the effects of turbulence due to exhaust from chimneys on traditional aircraft carriers are eliminated. This offers an enormous advantage for pilots when landing on aircraft carriers. In addition, the infrared signature of the ship is considerably reduced.
| Number | Date | Country | Kind |
|---|---|---|---|
| 04 50700 | Apr 2004 | FR | national |
