FR2547905A1 - Improvements to plate heat exchangers - Google Patents

Abstract

Plate heat exchanger whose plates 2 are pleated (corrugated, folded) perpendicularly to the main flows 3 and 4 of the fluids. The high-pressure fluid 3 flows in a straight line between the manifolds 8 and 9, whilst the low-pressure fluid arrives and leaves at 10 and 11 perpendicularly to the main flow 4. The edge walls 6 and 5 of the high-pressure circuits 3 and the end walls 7 of the circuits 3 connect in a leaktight manner to the manifolds 8 and 9. The struts 6 in the circuit 3 are fixed to the pleated metal sheets 2 to allow them to withstand the internal pressure.

Description

 It is known to carry out heat exchanges between two fluids, mainly between two gases, by means of flat surfaces, one fluid circulating on one face, the other fluid circulating on the other face. These exchangers have the advantage of being compact and of generating low pressure drops.

 However, they have the disadvantage of becoming impracticable when the pressure difference between the fluids is large.

 The object of the invention is to eliminate this major drawback while reducing the exchange surfaces by increasing convection.

 It is characterized in that the exchange surfaces are not flat but are folded perpendicular to the direction of flow. The regular folding of the sheet metal constituting the surface of the angel has the effect on the one hand of considerably increasing the inertia with equal thickness to resist the pressure difference, - on the other hand of passing the coefficient convection from the flat surface to that of the cross tubes, which is several times higher, in the case of opposing folds.

 The invention thus makes it possible to reduce the dimensions and the weight while allowing pressure differences greater than those of conventional arrangements.

 Other characteristics of the invention will be specified during the description which follows, given only by way of example of embodiment.

 The single plate shows an exchanger for a gas turbine.

 Figure 1 is an elevational view of the exchanger.

 Figure 3 is the side view and Figure 2 the plan view.

 Figure 4 is a partial section along A.A of Figure 1 or A.A of Figure 3 enlarged to clarify the details.

 Figure 5 is a section through B.B of Figures 2 and 3.

 FIG. 6 represents a different arrangement of the pleated sheets making it possible to have a larger exchange surface per unit of volume.

 In FIGS. 1, 2, 3, 4 and 5, the exchanger 1 is formed by vertical pleated sheets 2 with opposite undulations.

These sheets 2 form by their opposite faces two by two the high pressure circuits 3 and the low pressure circuits 4.

 The high pressure circuits 3 are closed on their banks at 5 by longitudinal walls 6 conforming to the shape of the corrugations and welded or brazed to the sheets 2. Longitudinal walls 6 are welded or brazed to the sheets 2 at a step such as the pressure internal can be supported by the wavy t81e; they serve as spacers between the opposite walls.

 The low pressure circuits 4 are closed at their ends, that is to say parallel to the folds, by partitions 7.

 These end partitions 7 of the low pressure channels 4 and the longitudinal walls 6 of the edges at 5 of the high pressure channels 3 are connected in a sealed manner by welding or soldering to the high pressure collectors 8 and 9.

 All the sheets 2, the walls 6 of the edges 5, the partitions 7 and the collectors 8 and 9 thus form a closed space leading to the opposite flanges 12 and 13 through which the pressurized fluid enters and leaves.

 The pressureless fluid enters through the rectangular opening 10 open over the entire width of the exchanger and exits through the rectangular opening 11 also open over the entire width of the exchanger.

 Between the opening 10 and the manifold 8 is mounted in a sealed but removable manner the plate 14. Similarly between the opening 11 and the manifold 9 is mounted the sealed plate 15 on its perimeter but removable.

 The exchanger 1 is designed for a gas turbine whose turbine exhaust manifold is connected at 10 and the exhaust duct is connected at 11. The panels 14 and 15 are removable to allow easy and total periodic cleaning circuits 4 which conventionally become fouled by accumulation of unburnt materials.

 The outlet of the compressor is connected to the flange 12 of the manifold 8 and the departure to the combustion chambers is made by the flange 13 of the manifold 9.

 Thus the hot exhaust gases arrive laterally through 10 into the exchanger 1 from which they pass longitudinally through the channels 4 perpendicular to the folds of the sheets 2 and they exit laterally cooled through 11 opposite 10 to enter the duct d 'exhaust.

 The compressed gases arrive via 12 at the manifold 8 from where they pass longitudinally through the channels 3 perpendicular to the folds of the sheets 2 in the direction opposite to the path of the burnt gases in 4 to reach the manifold 9 which opens into 13.

 If the folds of the sheet are formed by half cylinders in opposition, as is clearly shown in FIG. 4, the exchange coefficient is that of cross cylinders distant longitudinally and laterally from the diameter, which is much greater than that flat sheets.

 FIG. 6 represents a different assembly of the pleated sheets which have folds of sinusoidal shape and are parallel.

 The sheets 2 are replaced by the parallel sheets 16.

 The pressure channels 17 are open at their ends, but carry partitions 18 parallel to the flow, having the same effect as the partitions 6 previously described.

 Likewise, the pressure-free channels 19 are closed at their ends by partitions 20 similar to partitions 7.

 These end partitions 20 and the edge partitions 18 are connected in a sealed manner to the collectors 8 and 9 like the edge partitions 6 and the partitions 7 previously described.

 This arrangement makes it possible to increase the exchange surface per unit volume while having an exchange coefficient greater than the flat surfaces 9 because of the turbulence induced by alternating curvatures.

Claims (10)

Claims 1. Plate heat exchanger characterized in that the exchange walls consist of pleated or corrugated sheets perpendicular to the main direction of the flow of exchange fluids. 2. Plate heat exchanger according to claim 1 characterized in that spacer partitions connecting the two opposite walls are placed parallel to the flow in the high pressure circuits at the necessary pitch so that the pleated sheet can withstand the internal pressure. 3. Plate heat exchanger according to claims 1 or 2 characterized in that the banks of the high pressure channels parallel to the flow are closed by partitions similar to those of the spacers according to claim 2. 4. Plate heat exchanger according to claims 1 or 2 characterized in that the banks of the high pressure channels parallel to the flow are produced by bringing together the two sheets forming walls suitably deformed for this purpose. 5. Plate heat exchanger according to any one of claims 1 to 4 characterized in that the low pressure channels are closed at their ends by walls substantially perpendicular to the main flow. 6. Plate heat exchanger according to any one of claims 1 to 5 characterized in that the side panels of the high pressure circuits according to claim 3 and the closure walls according to claim 5 are connected at their ends by a tight to collectors of pressurized fluid. 7. Plate heat exchanger according to any one of claims 1 to 6 characterized in that the high pressure collectors are at each end of the exchanger printing a direct path to the high pressure fluid.  8. Plate heat exchanger according to any one of claims 1 to 7 characterized in that the inputs and  low pressure fluid outlets are rectangular on  the entire width of the exchanger and are placed diagonally opposite. 9. Plate heat exchanger according to any one of claims 1 to 8 characterized in that the edge walls of the low pressure channels are constituted by plates occupying all of the upper surfaces and  of the exchanger except for the inputs and  outputs according to claim 8. 10. Plate heat exchanger according to any one of  claims 1 to 9 characterized in that the plates  edge according to claim 9 are removable to allow  total and rapid cleaning of all low pressure circuits.