FR2867012A1 - Domestic or industrial wastes inerting device, has resonance cavity in which electric field is controlled, where field control is subjected to electrical component for providing energy to material present in applicator, via wave guide - Google Patents

Abstract

The device has a resonance cavity (1) in which electric field is controlled by a controlling loop (6). The electric field control is subjected to an electrical component for providing energy to material present in an applicator (9), via a wave guide (8). An adjustable capacitor (7) is placed on the loop for restoring acceptable impedance on the loop. The capacitor is placed at the input of the wave guide.

Description

-1- 2867012

  The present invention relates to the inerting of domestic or industrial waste with a high dielectric component from a high-frequency radiation (HF) preferably supplying the component of the electric field by the conjugated set of resonance and guide cavities (s). ) wave.

  In general, industrial HF installations operate in frequency ranges of 6.78 MHz, 13.56 MHz and 27.12 MHz and generally include a high-frequency energy transmission line, an applicator, an adapter box whose function is to match the impedance of the circuit.

  The present invention relates to the realization of a device using the joint properties of the resonance cavities (1) allied to the properties of the waveguides (8) and extends the application in frequency ranges from 1 MHZ to 300 MHZ. The combined use of these elements gives the device particular properties in terms of the orientation of the electromagnetic field as well as the adaptation of the impedances brought back from the applicator (9) to the power generator HF.

  In the present state of the art, HF power generators are often designed from a self oscillator arrangement that includes an oscillating circuit as well as a fast switch and a DC high voltage source.

  The oscillating circuit is excited by pulses from a vacuum tube. In steady state, the operating frequency is stabilized around the resonant frequency of the oscillating circuit. An output coupling, analogous to a transformer, takes the power of the oscillating circuit to transmit it to the applicator.

  To limit drift in frequency and for reasons of efficiency, the oscillating circuit must have a high Q overvoltage coefficient. The values of 100 are hardly exceeded for "Q" because the reactive current increases with Q, which rapidly increases the losses. Therefore, the present invention replaces the conventional LC circuit design with localized elements, a resonant cavity design (1) whose particularity is to favor a propagation mode of the electric field that is perfectly suited to the intended application while conferring on the device ub coefficient "Q" high.

  In a conventional manner, any HF generator is characterized by four basic variables: the useful power, the efficiency, the frequency and the nominal impedance.

  La The useful power of the generator is essentially dependent on the DC high voltage source (5,000 to 20,000 V) and the operating point of the tube itself.

  É The efficiency of the generator, between RF power and mains, is mainly determined by the operating point of the tube. This efficiency depends on the impedance seen by the tube between anode and cathode, the polarization of the gate, and the coupling between the gate and the oscillating circuit.

  -2- 2867012 É The frequency of the output signal and its stability are related to the design of the oscillating circuit: resonant frequency, overvoltage.

  É The nominal impedance of the generator is equal to the impedance of the applicator which, connected to the output of the generator, allows the tube to work at the chosen operating point.

  However, in an industrial HF installation, the impedance that the applicator presents is a function of the characteristics of the material to be treated. Any variation thereof will cause a shift in the resonant frequency of the applicator because the material absorbs only a portion of the energy emitted by the generator. The unabsorbed energy is consumed partly in the assembly chokes (heating) or goes back to the generator, thus creating a stationary wave phenomenon, responsible for flashes and radiation disturbances.

  The notion of impedance matching is essential because it allows to assimilate the conditions to be respected on a high frequency or microwave mounting to ensure optimal transmission of the energy of the generator to its load and thus ensure the survival of elements of the device.

  It is said that a system is impedance matched if the reflection coefficient of the electromagnetic wave is zero. This definition is valid regardless of the type of supply line including in the present invention the use of a cavity (1) conjugated to a waveguide (8).

  When the reflection coefficient is zero, the reflected power level is zero; all the energy from the source is absorbed by the applicator and there is no standing wave phenomenon.

  The present invention overcomes this disadvantage by introducing into the mounting one or more passive elements mounted on a removable system whose variable value is adjusted by actuators according to the parameters related to the behavior of the tube itself. Thus the increase in power of the energy radiated in the applicator follows the variation of the nominal impedance of the product to be treated while ensuring the protection of the RF tube. This device ensures the gradual transfer of all the energy from the RF generator to the product located in the applicator.

  In the present invention, the impedance of the waveguide (8) is chosen such that the image of the input and output impedances is substantially equal. In particular, the applicator (9) may be mainly reactive and in this case the input impedance image will be chosen as being itself reactive. The relationship between these two impedances will condition the choice of the value of the waveguide (8).

  In the present invention, to achieve such agreement the waveguide (8) is constructed in a resonance mode equal to one quarter of the propagation wavelength of the RF wave.

  -3- 2867012 The propagation mode of the HF wave in the cavity (1) is chosen to favor the capture of the electrical component (TE) on the magnetic component TM In this way the capture of the electric field in the cavity will be mainly subjected to the electrical component thus providing the necessary energy to the material present in the applicator (9).

  The waveguide (8) serves to bring this energy into the material placed in the applicator (9).

  Domestic and industrial waste has very high dielectric components and therefore behaves like insulators.

  It is therefore imperative to subject materials with a high dielectric component to a particularly large electric field.

  The present invention offers the possibility of also adjusting the dimensions of the cavity (1) by motorizing the movable panel (3) because it is mounted on a slide panel (4). The tuning frequency of the assembly is also adjusted by sizing the capacitor (2) by motorizing one of its walls (5).

  The capture of the electric field in the cavity (1) can be done by any usual means depending on the type of cavity chosen. Depending on whether the cavity is open, semi-open, reentrant or not, the sampling mode is achievable by slot or iris articulated on a waveguide or directly by antenna, panel, self, capture loop, depending on the importance to give to the component of the radiating field.

  In the present invention a particular application is shown with an open cavity (1) in which the sensing is achieved by a sensing loop (6). In order to reduce an acceptable impedance on the sensing loop (6), an adjustable capacitor (7) is connected in parallel with the sensing loop (6).

  The waveguide (8) can be made in different ways: two-wire line, solid guide of any parallelepipedal or cylindrical or mixed geometry. The waveguide must favor the TE propagation mode, the TEIO mode being perfectly suitable.

  In the present invention, the waveguide used (8) is made with a two-wire line (8) whose length is an odd multiple of a quarter of the wavelength of the RF wave.

  In the present invention, the construction impedance of the waveguide (8) is therefore directly related to the image of the applicator (9) read at the beginning of the guide (8). To refine the impedance matching, an adjustable capacitor (7) is mounted at the input of the guide (8).

  In a particular application, the motorization of the adjustable capacitor (7) is carried out automatically by an actuator as and when the needs related to the variations in charges related to the material present in the applicator (9). This adaptation follows those at the -42867012 times of the cavity (1) by its movable panel (3) and the capacitor (2) of the output power stage of the tube by actuat its wall (5).

  In another particular application it is possible to achieve this impedance matching stubs placed on the waveguide and whose length varies depending on the desired adaptation. For any load impedances, the system with three variable elements as constituted by 3 stubs, adapts by acting on at least two of the elements.

  If the waveguide is made from a parallelepiped solid, the stubs may be constituted by screws more or less plunging into the light of the guide itself.

  This principle being established, the impedance matching technology used will be chosen according to the type of transmission line used.

  The applicator (9) can be made according to different technologies. In the case of a solid guide parallelepiped geometry, the applicator (9) may continue the geometry of the guide is provided with slots or irises giving access to the electric field in which will dive the material to be treated.

  In the present invention, the applicator (9) is made from a metric dimension inductor in which is placed a cylindrical container constructed of material with very low losses. This cylindrical container receives the waste to be inerted.

  In a particular application, the waste may be mixed with sand in order to produce a vitrified easily transportable, easily storable and reusable later. In this way the waste can be stored with great security.

Claims (8)

  i. Device for inerting domestic and industrial waste, characterized in that it comprises elements that involve dielectric heating in an applicator over a frequency range of 1 MHZ to 300 MHZ 2. Device according to claim 1 characterized in that the high frequency power circuit (HF) may be constituted either of a self-oscillating oscillator tube or of a tube controlled by a frequency stabilized power preamplifier system.   3. Device according to claims 1 and 2 characterized in that the localized constants of the HF adaptation and propagation circuits are mainly replaced by physically distributed constants represented by a resonance cavity (1) and a waveguide (8). ) comprising as input an adjustable capacitor (7).   4. Device according to claim 3 characterized in that the resonance cavity (1) is manufactured to operate in TE mode (electrical component propagation mode) 5. Device according to claim 4 characterized in that one of the walls of the resonance cavity (1) and the capacitor (2) are adjustable either fixedly or automatically by motorized actuator 6. Device according to claims 4 and 5 characterized in that the capture circuit of the electric field is formed by a capture loop (6) provided with tunable adjustable capacitor (7) to refine the impedance agreements between the applicator (9) and the electron tube supplying the electric power to the load 7. Device according to claim 4 characterized in that the waveguide (8) is made from a two-wire line (8) whose length is such that resonant in odd quarter-of-wavelength and whose the characteristic impedance is adapted to the coupling to be made between the load impedance linked to the applicator and the working impedance of the power tube.   8. Device according to any one of the preceding claims characterized in that the applicator (9) can be made from a hollow tube traversed by a coolant, the tube is wound on itself so that the geometry obtained is similar to that of a hollow cylinder of metric dimensions.