Spiral or helical counterflow heat exchanger

Abstract

Spiral or helical counterflow heat exchanger (9, 9) consisting of two adjoining chambers (10,11), in which a fluid at a high temperature flows in one chamber in one direction, and in which a fluid at a low temperature flows in the opposite direction in the other chamber, characterized in that both chambers are separated by one separating plate (6) of flat monolithic double-sided enamelled steel annealed at temperatures above 500 C., and whereby the separating plate (6) is held by its edges in a corrosion-resistant spacer (8,8) that imposes a fixed distance to two other flat monolithic double-sided enamelled steel plates that each define one chamber at the side that is opposite the separating plate (6), and which prevents corrosion of the edges of the separating plate and of the two other enamelled steel plates.

Claims

1. A helical counterflow heat exchanger, comprising: three flexible flat monolithic double-sided enameled steel bands annealed at temperatures above 500 C., that define two chambers and are wound helically around a central longitudinal axis that is parallel with and equidistant to a surface of each respective enameled steel band, the surface of each respective enameled steel band extending parallel to the longitudinal axis, the first chamber being configured to guide a first fluid therethrough, the second chamber being configured to guide a second fluid therethrough in an opposite direction with respect to a guiding direction of the first fluid; and a first corrosion-resistant helical spacer provided between windings of the heat exchanger to impose a mutual distance between the windings and a curve of the respective windings in the heat exchanger formed by the enameled steel bands, to prevent corrosion of the steel bands at edges of the steel bands and to allow successive windings of the helical heat exchanger to fit against one another in the direction of the longitudinal axis.

2. The counterflow heat exchanger according to claim 1, further comprising a second helical spacer comprising rectangular strips of chemically-inert material, the rectangular strips extending in the flow direction of the fluids between two of the enameled steel bands wound around one another, the rectangular strips being configured such that the edges of the enameled steel bands do not come into contact with the content of the two chambers.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) With the intention of better showing the characteristics of the invention, one preferred embodiment of counterflow heat exchangers according to the invention is described hereinafter by way of an example, without any limiting nature, with reference to the accompanying drawings, wherein:

(2) FIG. 1 schematically shows a cross-section of a set of corrugated double-sided enameled steel plates in a regenerative heat exchanger according to the state of the art;

(3) FIG. 2 shows a helical counterflow heat exchanger comprising three double-sided enameled flexible plates according to the invention; and

(4) FIG. 3 shows a variant of FIG. 2 with a different type of spacer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(5) FIG. 1 schematically shows a cross-section of a number of corrugated double-sided enameled steel plates, as used in cages for regenerative heat exchangers in the current state of the art. In this case, a cold-rolled corrugated steel plate 1 that is enameled on both sides is alternated with a flat double-sided enameled steel plate 2.

(6) FIG. 2 shows a helical counterflow heat exchanger 3 made up of three flexible double-sided enameled steel bands 4, 4 4 that define two chambers 5, 6 and are wound helically around a central longitudinal axis 7. A first fluid is guided through the first chamber 5 and a second fluid is guided in the opposite direction through the second chamber 6. A first helical spacer 8 imposes the mutual distance and the curve of the windings in the enameled steel plates.

(7) FIG. 3 shows a variant 3 of FIG. 2, whereby the same helical counterflow heat exchanger is shown, but is now provided with a second spacer that consists of rectangular strips 8 of Teflon or another chemically inert material, that extends in the flow direction of the fluids between the three helical double-sided enameled steel plates 4, 4, 4 wound around one another, and are so arranged that the edges of the steel plates do not come into contact with the flow chambers 5, 6 defined by the beam-shaped strips 8.

(8) The operation of the counterflow heat exchanger according to the invention is very simple and as follows.

(9) The hotter and colder fluid can consist of a gas and/or a liquid phase of the same substance or of two different substances. The high corrosion-resistance of the enameled plates also enables chemically corrosive fluids to be sent through the heat exchanger.

(10) For the helical embodiments 3,3 of the counterflow heat exchanger, three flexible double-sided enameled steel plates 4, 4, 4 are used, between which two chambers 5, 6 are created by holding the steel plates by the edges in a corrosion-resistant spacer 8, that not only ensures a constant distance between the three plates 4, 4, 4, but also keeps them in the right helical shape in order to wind up the chambers 5, 6 such that the windings lie against the overlying windings and both chambers 5, 6 run into the other end of the helical counterflow heat exchanger.

(11) The hotter fluid is guided through the first chamber 5 in a first flow direction, while the colder fluid is guided through the second chamber 6 in a flow direction opposite to the first flow direction of the hotter fluid. Both chambers 5 and 6 are only separated from one another by one single separating plate 4 of flexible double-sided enameled steel through which the hotter fluid transfers heat to the colder counterflow of the second fluid that flows into the counterflow heat exchanger at the opposite end of the helical heat exchanger to the first fluid, and flows out again at the same end where the first fluid flows in.

(12) Due to its compact construction, the helical counterflow heat exchanger 3, 3 saves space, but nonetheless provides the possibility to exchange heat over a long and smooth enamelled steel band.

(13) It goes without saying that the second fluid can also consist of the first fluid that has already been partially cooled at the bottom of the helix and flows out of the first chamber 5 and is fed back through the second chamber 6 to the top of the helix.

(14) The present invention is by no means limited to the embodiments described as an example and shown in the drawings, but a counterflow heat exchanger according to the invention can be realised in all kinds of forms and dimensions, without departing from the scope of the invention as defined in the claims.