FR2476808A1 - HEAT EXCHANGER FORMING ANTI-DEFLAGRATION BARRIER FOR DOMESTIC CENTRAL HEATING BOILERS - Google Patents

Abstract

THE INVENTION RELATES TO A HEAT EXCHANGER FORMING ANTI-EXPLOSION BARRIER. THE HEAT EXCHANGER INCLUDES A TABLE OF 4 LONGITUDINAL TUBES WITH EXTENDED SECTION, ARRANGED FOLLOWING THE GENERATOR OF A CYLINDER TO FORM A CYLINDRICAL INTERIOR COMBUSTION CHAMBER IN SUCH A WAY THAT THE LATERAL FACES 11 OF THE SUITABLE 12 TUBES INTERCHANGELY INTERCHANGE BETWEEN 12 TUBES AND OF LOW THICKNESS, THE DIMENSION OF WHICH CORRESPONDING TO THE LENGTH OF THE SENSITIVELY RECTILINE PART OF THE PROFILE OF THE TUBES 4 IN RELATION TO THE GAP IS GREATER OR EQUAL TO THE FLAME STAMPING DISTANCE. APPLICATION TO DOMESTIC CENTRAL HEATING BOILERS WITH HOT WATER BY GAS OF THE SEALED TYPE.

Description

The present invention relates to domestic heating boilers

  central hot water by gas tight type forced draft and more specifically relates to a heat exchanger which

anti-explosion barrier form.

  In a known embodiment of forced draft boilers, the combustion chamber consists of a sheet of longitudinal water tubes arranged all around a central burner whose combustion gases are emitted radially and passing through this sheet of tubes. , the best conditions of exchange between water and gas being obviously sought for example by the shape and the

positioning of the tubes.

  These longitudinal water tubes may have a circular cross-section

  re or elliptical or have different contours on the upstream face and the downstream face such as section tubes

  so-called orange-shaped, or drop-shaped.

  In addition, in this type of device, the fuel mixture is provided by a fan arranged upstream of the combustion chamber.

  which is therefore in a sealed enclosure vis-à-vis the 'at-

  mosphere of the room in which the appliance is installed. We see by

  Consequently, it is necessary to plan a pre-scan of the

  burned before any ignition operation inside this circuit. This pre-purge is to operate the fan to evacuate any accumulations of mixture

  fuel and thus avoid the risk of explosion.

  But in the case where the pre-purge does not take place as a result of a false operation or a malfunction or if the rate of the gas mixture is outside the flammability limits, there is therefore a gas accumulation fuel in the

  combustion chamber and, at the start of the ignition

  die, an explosion with the risks that entails.

  The subject of the invention is a new type of elongate section water tube exchanger, concentrically arranged with a radial burner, which avoids these risks of explosions by providing additional safety, if there is an accumulation of

  combustible mixture in the apparatus.

  According to the invention, the heat exchanger comprises a sheet of longitudinal tubes with an elongate section, arranged along the generatrix of a cylinder to form a cylindrical internal combustion chamber in such a way that the lateral faces of said tubes form between they have a constant and thin gap whose dimension corresponding to the length of the substantially rectilinear portion of the profile of the tubes relative to the spacing is greater than or equal to the distance of

  jamming the flames to establish an explosion-proof barrier.

  Other particular features and advantages of the invention

  will emerge from the following description of a form of

  embodiment with reference to the accompanying drawings which represent

  - Figure 1: a partially green side elevation view

the exchanger.

  FIG. 2: a half-view in section of the exchanger in which only part of the water tubes for

clarify the figure.

  - Figure 3: a larger scale view of the water tubes.

  As shown in the figures, the heat exchanger comprises inside an enclosure 1 which collects the flue gases and discharges them through the chimney 2, a radial burner 3 disposed in the center and a ply of water tubes 4 arranged vertically and concentrically at

  burner. Water admitted through an inlet duct 5 into a collection

  6 is circulated in a bundle of tubes 4 to gain the upper collector 7 and then again by another bundle of tubes returns to the lower collector and so on before reaching the outlet conduit 8. Between the inlet conduit 5 and the outlet duct 8 the water has traveled, in bundles of

  successive tubes, the turn of the exchanger.

  The sheet of tubes 4 forms in the enclosure 1 two chambers concentrating

  separate, the first, the combustion chamber 9 pro-

  which is located inside the burner 3 and the

  conde, the combustion products evacuation chamber 10 -3 -

  between the downstream face of the tubes 4 and the outer walls of the

encircled 1.

  The tubes 4 have an elongated section so that the lateral faces 11 of each tube are substantially parallel to the lateral faces of the adjacent tubes in order to provide each of them with a substantially constant interval 12 of low

  thickness and nevertheless delimited by two large

  smoothly facilitating the laminar flow of gases from the

  combustion chamber 9 to the evacuation chamber 10.

  The gap 12 (FIG. 3) between each tube 4 is defined by a spacing "a" of less than or equal to 1.5 mm, extending over the entire length "b" of the substantially rectilinear part of the profile.

  tubes, length greater than or equal to 3 mm. We thus have a

  tervalle whose section is greater than or equal to the distance

jamming flames.

  If for any reason, the fuel mixture arrives through the burner 3 in the combustion chamber 9 without ignition, it passes through the sheet of tubes 4 by the intervals 12. This passage is easily made since the pressure drops between the chamber 9 and the evacuation chamber 10 are very small. The fuel mixture therefore tends to accumulate

in said evacuation chamber.

  As soon as the igniter is started, the fuel mixture in the combustion chamber 9 ignites. But the flames can not cross the sheet of tubes 4 because the length "b" intervals

  12 with respect to the spacing "a" is greater than or equal to

  so that the combustible mixture accumulated in the exhaust chamber 10 does not ignite and the reaction

  chemical caused by inflammation stops at the level of the tubes 4.

  This exchanger therefore forms an anti-explosion barrier and avoids

  the risk of explosion if there is an accumulation of

fuel in the appliance.

  The invention is not limited to the embodiment shown

  but encompasses all the constructive variants.

-4-

Claims (2)

R E V E N D I C A T I N S   / Heat exchanger for domestic heating boilers   central hot-water firing by the gas of the tight type with   forced rage comprising a ply of longitudinal tubes with   elongate section in which circulates the warming fluid.   iron, arranged along the generatrix of a cylinder to form a cylindrical interior combustion chamber characterized in that the lateral faces (11) of the   tubes (4) provide a plane gap (12) between them.   siblement constant and of small thickness whose dimension "b" corresponding to the length of the substantially rectilinear portion of the profile of the tubes relative to the spacing "a" is greater than or equal to the jamming distance   flames to establish a deflagration barrier.   2 / exchanger according to claim 1 characterized by.faith that the length "b" of the profile of the tubes (4) defining the   intervals (12) is greater than or equal to 3 mm.   / Exchanger according to claim 1 characterized in that the spacing "a" between the tubes (4) defining the   intervals (12) is less than or equal to 1.5 mm.