FR2634009A1 - LINTEAU FOR OVEN OPENING - Google Patents

Abstract

The present invention relates to a furnace lintel. According to the invention, this lintel is formed by a hollow box 3 with membrane walls, that is to say formed of tubes 4 interconnected by flat irons 5, means being provided for circulating a heat transfer fluid to the inside the tubes.

Description

- 1 -

  It is known to use ovens with a linear

  chilled water. But the kiln lintels made until

  that presently pose problems as regards the behavior and the behavior in time according to the diets. The most frequently encountered incidents are

  related to the overheating of metal parts of

  water or, on the contrary, the corrosion of these

  because of the condensation of acid fumes

  when the hot gases from the furnace chamber can

  flow between the lintel and the lining by the cracks of the materials constituting the lining, cracks generally caused by the aging of the various components of the furnace and by the variations

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  dimensions due to differential expansion between the lintel, which is in principle at a constant temperature, and its environment whose temperature

  varies with the different cases of walking and stops.

  The controlled cooling solutions of the lintels usually used involve either an air sweep of the lintel made of hollow beam or an organized circulation of water within this lintel

  same hollow beam; water can either fill the totality

  the cavity thus constituted is circulated in tubes themselves embedded in insulating materials. he

  is possible by calculating the transfers between the

  chilled water and its environment, to determine the

  heat transfer fluid flows and the temperatures

  the different elements of the lintel. Fluxes are determined for specific walking cases and resistance to transfer; the exchange coefficients are imposed by the transfer conditions between the heat transfer fluid and its enclosure: compromises must be found between the different cases of operation,

  which inevitably translates into either

  in the transitional regimes or in the case of deterioration of the

  too low temperatures causing condensation

  with the corollary corrosion and destruc-

3 -

progressive lintel.

  The present invention relates to a furnace lintel

  which, in operation, has on the contrary a tempera-

  homogeneous re maintained at a predetermined level regardless of the state of insulating or refractory materials

  protecting the lintel from radiation and convection

the furnace atmosphere.

  The lintel according to the invention is characterized in that

  it consists of a hollow box with walls

  branées, that is to say formed of tubes interconnected by flat irons, means being provided for circulating a heat transfer fluid inside the tubes.

  The inertia of this box is equivalent to or even higher than

  than that of a conventional lintel in sheet metal and

  spun while being of a lower weight. The temperature

  The walls of the box are controlled by the circulation of the heat transfer fluid inside the tubes, components of the membrane wall. Depending on the operating conditions and in particular on the oven temperature and the composition of the flue gases, the coolant can be either water or a mixed water / steam phase. Given the fact that the transfer coefficients between heat-carrying fluid

4- -

  and tubes are very much greater than the transfer coefficient between lining and membrane walls or

  same, in case of partial destruction of these

  between the chamber and the membrane wall, the temperature

  its erosion is dictated by the temperature and velocity conditions of the coolant, the thickness of the tubes and plates and the way the plates are welded to the tubes; the temperature of the coolant water or mixed phase water / steam is

  itself related to the recirculation rate and the pressure

  the lintel power loop. It is thus possible according to the risks of corrosion, due to the presence of sulfur compounds in the case of fuels or to the presence of halogenated derivatives in the fumes, to set the equilibrium temperature

  membrane walls even in case of stripping by

  tiel in order to maintain the temperature of the metal at a

  temperature always higher than the dew point

  fumes and always lower than the temperature at which the metal constituting the membrane walls

  would no longer have the desired mechanical characteristics.

  An embodiment of the lintel according to the invention is described below, by way of nonlimiting example, with reference to the appended drawing in which: FIG. 1 is a perspective view of the lintel; -

  Figure 2 is a cross section.

  In the drawing, we see the wall 1 of an oven which is provided with an access opening 2. This is surmounted by a

  lintel designated as a whole by reference 3.

  The lintel 3 is constituted by a hollow box with walls

  membranées that is to say formed of tubes 4 connected

  be they by plates 5 welded to the tubes. Means not shown in the drawing make it possible to circulate a heat transfer fluid inside the tubes 4.

  heat transfer fluid may be water or a mixed phase

  water / steam. The tubes 4 can be connected in series or in parallel and be simple tubes with direct passage of the coolant or double tubes in which the heat transfer fluid enters through the tubes.

  internal tubes and spring through the outer tubes or

payment.

  The lintel 3 is protected from radiation and

  hot fumes by refractory lining

  6-7 held in place by a metal frame 8.

  It goes without saying that the present invention should not be considered as limited to the embodiment described and shown, but covers, on the contrary,

all variants.

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Claims (1)

Claim   Oven lintel characterized in that it consists of a hollow box (3) with membranous walls, that is to say formed of tubes (4) interconnected by flat irons (5), means being provided to circulate a heat fluid carrier inside the tubes.