WO2010010591A2

WO2010010591A2 - A drier for compressed gas and method for producing the drier

Info

Publication number: WO2010010591A2
Application number: PCT/IT2009/000326
Authority: WO
Inventors: Stefano Bernardinello; Andrea Bottazzo
Original assignee: MTA SpA
Current assignee: MTA SpA
Priority date: 2008-07-24
Filing date: 2009-07-22
Publication date: 2010-01-28
Anticipated expiration: 2011-01-24
Also published as: WO2010010591A3; ITPD20080222A1; IT1393386B1

Abstract

A drier (1) for compressed gas comprises at least one exchange element (14) of spiral form which is produced by an extrusion profile (16) with a flattened section being wound in a flattening direction (4), the section is provided with two opposing sides (18a, b) which are parallel with the flattening direction and there extends from each of the sides at least one fin (20a, 22a) which is orthogonal to the flattening direction, the fins are of equal length in the orthogonal direction relative to the flattening direction and are spaced apart from each other in the flattening direction.

Description

A DRIER FOR COMPRESSED GAS AND METHOD FOR PRODUCING THE DRIER

Technical scope

The present invention relates to a drier for compressed gas of the type including the features set out in the preamble of the main claim and a method for producing the exchanger itself.

The present invention is particularly, though not exclusively, suitable for driers having small dimensions and low levels of power.

Technological background In the field of compressed air driers, it is known to construct heat exchange elements which have high thermal efficiency and which comprise two or more pluralities of rectilinear, mutually parallel passages, through which two or more fluids travel in thermal contact with each other.

Those passages can be, for example, of the type having mini-channels and/or micro-channels, as described in Italian patent applications PD2007A000250 and PD2007A000251 by the same applicant.

A drier of the above-described type is a solution which can readily be implemented for installed power levels in the order of 1 kW or above.

However, it is not the optimum solution for low power levels (from 300 to 500 W or less), since the necessity of keeping costs in check requires structural solutions which are simpler in those cases.

Furthermore, since driers of low power are typically used in thermal plants or machines of small dimensions, it is necessary for such driers also to have small dimensions and compact forms which are impossible to obtain with the solutions described in the two patent applications set out above since the constructions with mini-channels and/or micro-channels are characterized by a main spatial requirement in a main longitudinal direction.

Description of the invention

The main object of the present invention is to provide a drier for compressed gas and a method for producing that drier which are configured to overcome all the disadvantages set out with reference to the cited prior art, in such a manner as to provide a drier for compressed gas of low power which is simple and compact, with at least the same thermal efficiency as solutions having greater power, This object and other objects which will be appreciated from the following are addressed and achieved by the invention by means of a drier for compressed gas and a method for producing that drier which are constructed in accordance with the appended claims.

Brief description of the drawings The features and advantages of the invention will be better appreciated from the detailed description of one preferred embodiment thereof which is illustrated by way of non-limiting example with reference to the appended drawings, in which:

- Figure 1 is an axonometric view of a drier for compressed gas constructed in accordance with the invention;

- Figures 2 and 3 are two axonometric sections of two details of the drier of Figure 1, respectively;

- Figure 4 is an axonometric top view of a component of the drier of Figure 1;

- Figure 5 is an axonometric bottom view of the component of Figure 4; - Figures 6 and 7 are two views, a side view and an axonometric section, of a component of the drier of Figure 1, respectively;

- Figures 8 and 9 are two side views of two structural variants of the component of Figure 6, respectively. Preferred embodiment of the invention With reference to the Figures set out above, a drier for compressed gas, in particular compressed air, is generally designated 1.

The drier 1 comprises a housing 2 having a cylindrical outer surface 3 with an axis X and two curved ends 4a, b which are axially opposed. There are provided in the curved end 4a an intake pipe 5 for a flow 6 of moist air to be dried and a discharge pipe 7 for a flow 8 of dry air. There are provided on the curved end 4b a discharge pipe 9 for the condensate and two pipes 10, 11 for the intake and discharge of a flow 12 of coolant fluid, respectively. In the housing 2, the drier 1 comprises an exchanger 13 which includes a first exchange element 14 for pre-exchange adjacent to the curved end 4a, a second exchange element 15 which acts as an evaporator and a space 16 for collecting the condensate, adjacent to the curved end 4b. The first exchange element 14 is of double-spiral-like form obtained by winding about the axis X two extrusion profiles 16 which are positioned beside each other. The second exchange element 15 is in the form of a spiral obtained by winding about the axis X an extrusion profile 17. The extrusion profiles 16, 17 have a flattened cross-section in two flattening directions Y and Z which are arranged parallel with the axis X, respectively. The flattened sections of the extrusion profiles 16, 17 are each provided with two mutually opposing sides 18a, b and 19a, b which are parallel with the flattening directions Y and Z, respectively. In the windings of the exchange elements 14, 15, the sides 18a and 19a are directed towards the axis X and the sides 18b and 19b are directed the other way. Two fins 20a, b and 21a, b extend from the sides 18a and 19a, respectively, and are orthogonal relative to the flattening directions Y and Z and are regularly spaced-apart along the same axes Y and Z. Three fins 22a, b,c and 23a, b,c extend from the sides 18b and 19b, respectively, and are orthogonal relative to the flattening directions Y and Z and are regularly spaced apart along the same axes Y and Z. All the fins 20a,b, 21a, b and 22a, b,c, 23a, b,c are of equal length in the direction orthogonal relative to the flattening directions Y and Z and are provided in such a manner that each of the fins 20a, b and 21a, b is spaced, in accordance with the flattening directions Y and Z, apart from each of the fins 22a, b,c and 23a, b, c, respectively.

Owing to the effect of such a geometrical formation, the ends of the fins at the sides 18a and 19a are placed in contact with the sides 18b and 19b (Figure 6), respectively, so as to produce several pluralities of spiral passages which are mutually parallel and positioned side by side along the axis X, and through which the same heat exchange fluid flows.

The first exchange element 14 comprises two pluralities of passages 24, 25 which are delimited by the extrusion profiles 16 and which continue as two diametrically opposed outer ends 16a, b of the exchange element 14 having two substantially semi-cylindrical cavities 26, 27 which are positioned at the centre of the exchange element 14 and which are separated by a wall 26a. The two pluralities of passages 24, 25 receive the flow of air 6 to be dried and a flow of cold dry air from the space 16, respectively. For each section of the extrusion profiles 16, the side 18a is in contact with one or other of the fluids in the passages 24, 25 and the side 18b is in contact with the other of the two fluids in the passages 24, 25.

The exchange 13 comprises two circular plates 28, 29, an upper plate and an intermediate plate, respectively, which are orthogonal relative to the axis X and between which there are interposed the extrusion profiles 16 of the pre- exchange element 14.

The upper plate 28 is directed towards the end 4a and comprises two openings 30, 31 for connection between the intake pipe 5 and the passages 24 and between the semi-cylindrical cavity 27 and the discharge pipe 7. The intermediate plate 29 comprises a central opening 32 for connection between the semi-cylindrical cavity 26 and a cavity 15a which is positioned at the centre of the second exchange element 15.

The second exchange element 15 comprises a plurality of passages 33 which are delimited by the sides 19a, b and by the fins 21a, b and 23a, b,c and through which the cooled moist air from the passages 24 travels through the opening 32. The spiral passages 33 extend from an end 33a, which is adjacent to the cavity 15a, to an opposite end 33b which is positioned at the perimeter of the exchange element 15. The passages 33 are in thermal contact with a plurality of passages 34, of the type having mini-channels and/or micro-channels, which are formed in the section of the extrusion profile 17 and in which the coolant fluid flows from the intake pipe 10, flowing through the passages 34 from one end 34a, positioned along the perimeter of the element 15 at the end 33b, to the opposite end 34b, positioned at the centre of the element 15, at the end 33a. The drier 1 comprises two connection tubes 35, 36 which are positioned between the pipe 10 and the end 34a and between the end 34b and the discharge pipe 11, respectively.

The exchanger 13 comprises a lower circular plate 37 which is orthogonal relative to the axis X, the extrusion profile 17 of the element 15 being interposed between the plates 29 and 37.

The lower plate 37 comprises two openings 38, 39 which are connected to the connection tubes 35, 36 for the passage of the coolant fluid from and towards the exchange element 15, respectively. The lower plate 37 comprises another opening 40, in an outer connection position between the end 33b of the passages 33 and the space 16.

The dry air and the condensate pass through the opening 40, into the space 16 so that the condensate can be collected on the curved end 4b and subsequently be discharged from the drier through the pipe 9. There are provided between the space 16 and the passages 25 two additional pipes 41, 42, which are parallel with the axis X and which extend between the plates 29 and 37, for connection between the space 16 and the plurality of passages 25.

In the construction variant of Figure 8, there is received in each of the passages 33 a turbulence-inducing insert 100 which is adjacent to the sides 19a, b, which is of metal tubing or is constituted by a bundle of long and fine metal filings, for example, of steel.

The use of the insert 100 allows an increase in the turbulence inside the pipes 33, thereby increasing the efficiency of the thermal exchange at the same time. In the construction variant of Figure 9, the sides 19a, b of the extrusion profile 17 do not have fins and there is therefore provided a single spiral passage 133 which is delimited by the sides 19a, b and the plates 29 and 37 and through which the cooled moist air from the passages 24 flows. There is received in the passage 133 a turbulence-inducing insert 200 which is adjacent to the sides 19a, b, which is of metal tubing or is constituted by a bundle of long and fine metal filings, for example, of steel.

A method for producing the exchange element 14 comprises the steps of: a) extruding two extrusion profiles having a geometry corresponding to that of the extrusion profile 16; b) winding in a spiral manner the extrusion profiles of the preceding step a) about the axis X parallel with the flattening direction Y of the extrusion profile 16, so that the ends of the extrusion profiles positioned along the perimeter of the spiral are diametrically opposed. A method for producing the exchange element 15 comprises the steps of: c) extruding an extrusion profile having a geometry corresponding to that of the extrusion profile 17, in which there are formed a plurality of passages having mini-channels and/or micro-channels; d) winding in a spiral manner the extrusion profile of the preceding step c) about the axis X parallel with the flattening direction Z of the extrusion profile 17.

With reference to Figures 8 and 9, in two construction variants of the above- described method there is provision, between the steps c) and d), to position, near one of the sides 19a, b of the extrusion profile 17, the turbulence-inducing elements 100 (Figure 8) or, in the case of the extrusion profile 17 which does not have any fins, the turbulence-inducing element 200 (Figure 9). Once the above-described windings have been obtained, the exchanger 13 is simply produced by positioning the plate 28, the exchange element 14, the plate 29, the exchange element 15, the pipes 41, 42 and the plate 37 close together, in that order, so that the opening 32 is positioned at the semi- cylindrical cavity 26 and the pipes 41, 42 allow the cold dry air from the space 16 to be introduced into the exchange element 14 at the end 16b of the passages 25.

The complete drier 1 is obtained in a similarly simple manner by connecting the tubes 35, 36 to the openings 38, 39 of the plate 37, inserting the assembly obtained in this manner into the cylindrical outer surface 3 and connecting to the cylindrical outer surface 3 the curved ends 4a, 4b comprising the pipes 5, 7, 9, 10 and 11, respectively.

Therefore, the invention overcomes the problem set out with reference to the cited prior art, allowing a drier for compressed gas to be obtained having low power and compact dimensions, with a simple construction, and, at the same time, allowing production costs to be kept in check.

Claims

1. A drier (1) for compressed gas, comprising at least one exchange element (14) of spiral form which is produced by an extrusion profile (16) with a flattened section being wound in a flattening direction (Y), the section being provided with two opposing sides (18a, b) which are parallel with the flattening direction, there extending from each of the sides at least one fin (20a, 22a) which is orthogonal to the flattening direction, characterized in that the fins (20a, 22a) are of equal length in the orthogonal direction relative to the flattening direction (Y) and are spaced apart from each other in the flattening direction (Y).

2. A drier (1) for compressed gas according to claim 1, wherein a plurality of fins (20a, b, 22a, b,c) which are orthogonal relative to the flattening direction (Y) extend from each of the sides (18a, b), each of the fins of one of the sides being spaced apart, in the flattening direction (Y), from each of the fins of the other of the sides.

3. A drier (1) for compressed gas according to claim 1 or claim 2, wherein each of the sides (18a, b) is in contact with a respective heat exchange fluid.

4. A drier (1) for compressed gas according to claim 3, wherein the sides (18a,b) are in contact with two respective flows of air at different temperatures.

5. A drier (1) for compressed gas according to any one of the preceding claims, wherein a plurality of passages (34) of the type having mini-channels and/or micro-channels are formed in the flattened section.

6. A drier (1) for compressed gas according to claim 5, comprising a turbulence-inducing insert (100) of metal tubing adjacent to the sides (19a, b) of the section.

7. A drier (1) for compressed gas according to claim 5 or claim 6, wherein a heat exchange fluid travels through the passages (34).

8. A drier (1) for compressed gas according to claim 7, wherein the heat exchange fluid is a cooling fluid.

9. A method, for producing a drier (1) for compressed gas, comprising the steps of: a) extruding a profile (17) which is extruded with a flattened section in a flattening direction (Z), the section being provided with two opposing sides (19a, b) which are parallel with the flattening direction, there extending from each of the sides (19a, b) at least one fin (21a, 23a) which is orthogonal relative to the flattening direction, the fins being of equal length in the orthogonal direction relative to the flattening direction and being spaced apart from each other in the flattening direction (Z), b) winding the extrusion profile in a spiral manner about a winding axis (X) which is parallel with the flattening direction (Z) in such a manner that the end of each fin (21a, 23a) of one of the sides (19a, 19b) is positioned in contact with the other of the sides (19b, 19a), so as to obtain a plurality of channels (33), each of which is delimited by the two sides (19a, b) and by two of the fins (21a, 23a).

10. A production method according to claim 9, wherein a plurality of passages (34) of the type having mini-channels and/or micro-channels are formed in the flattened section in the extrusion step.