WO2016135764A1

WO2016135764A1 - Heat exchanger

Info

Publication number: WO2016135764A1
Application number: PCT/IT2016/000044
Authority: WO
Inventors: Francesco BARBAGLI
Original assignee: Barbagli Francesco
Priority date: 2015-02-27
Filing date: 2016-02-22
Publication date: 2016-09-01

Abstract

Heat exchanger, comprising a casing (1) adapted to delimit an internal volume of predetermined capacity, with an input (2) for hot combustion fumes or gases (FC), an outlet (3) for the cold fumes (FF), at least one input (4) for a secondary fluid (SF) which receives heat from a primary fluid (FP), an output (5) for the secondary fluid, a heat exchange unit (6) in which the secondary fluid (SF) circulates while receiving heat from the primary fluid (FP) and an aspirator (7) for the extraction of the cold fumes (FF) through said outlet (3). The heat exchanger comprises condensing means placed in the casing (1) above the said inlet (2) for the hot gases or fumes (FC) and adapted to cause the condensation of vapors produced by the hot gases or fumes (FC) investing the primary fluid inside the casing (1).

Description

TITLE

Heat exchanger.

DESCRIPTION

The present invention relates to a heat exchanger. More particularly, the present invention relates to a heat exchanger fed by combustion fumes.

It is known that a heat exchanger is an apparatus wherein heat transmission from a first fluid to a second fluid takes place. Generally, a heat exchanger can be of the type in which two fluids are mixed with each other, or of the type in which two fluids, that can have a different nature, exchange thermal energy with each other without being mixed.

The main purpose of the present invention is to propose a heat exchanger of the second type offering a different structure and functioning compared to those available on the market.

This result is achieved, according to the present invention, by providing a heat exchanger having the features indicated in claim 1. Further features of the invention are the subject of the dependent claims.

A heat exchanger according to the present invention is apt to receive combustion fumes of any nature, i.e. combustion fumes coming from combustion processes of any kind, is particularly simple form a structural point of view, is efficient, is apt to operate as a filter for filtering the combustion fumes, thus combining the heat exchange function with the filtering function, and is not expensive in relation to the advantages it offers.

These and further advantages and features of the present invention will be best understood by anyone skilled in the art thanks to the following description and the attached drawings, given by way of example but not to be considered in a limitative sense, where : - Fig.l is a schematic longitudinal section view of a heat exchanger according to the present invention ;

- Fig.2 is a schematic longitudinal section view ;

- Fig.3 schematically show two heat exchangers according to the present invention connected in series to each other ;

- Fig. is an enlarged detail of Fig.3 ;

-Fig.5 shows another embodiemnt of a heat exchanger according to the present invention ;

- Fig.6 shows a further possible use of a heat exchanger according to the present invention.

Seen in its basic structure and with reference to the attached drawings, a heat exchanger according to the present invention comprise a thermally insulated casing (1) having a predtermined height that, for example has a circular cross-section, apt to delimit an internal volume having a given capacity, with an inlet (2) for the hot gas or fumes (FC) produced by a combustion process of any nature, an output (3) for the cold fumes (FF), at least an inlet (4) for a secondary fluid (SF) that receives heat from a primary fluid (FP) , an output (5) for the heated secondary fluid (SC) with a fitting connection for connecting a heat distribution system with the heat exchanger, a heat exchange unit (6) comprising, for example, a plurality of metal plates, wherein the secondary fluid circulates while receiving heat from the primary fluid (F) , and an aspiration unit (7) for extracting the cold fumes (FF) out of the casing (1) . In practice, within the heat exchange unit (6) positioned inside said volume, the primary fluid (FP) transmits thermal energy to the secondary fluid (FS).

For example, the primary fluid (FP) is water collected on the bottom of the casing (1) ; the primary fluid receives thermal energy from the hot fumes (FC) that enter through the inlet (2) and are deviated downwards by a curved surface (8) provided in front of the inlet (2) inside the casing (1). The primary fluid (FP) can be of any type, not only water. In practice, the hot fumes (FC) entering the casing (1) are directed towards the primary fluid (FP) collected on the bottom of the latter by the curved surface (8) . In this way, the primary fluid (FP) is heated by the hot fumes (FC). The heating of the primary fluid also produces a partial vaporization of the latter.

The primary fluid (FP) is made to circulate through the heat exchange unit (6) by a pump (9) that is fed through an inlet conduit (10) and supplies the primary fluid (FP) to the heat exchange unit (6) through an output conduit (11) .

According to the examples shown in the drawings, said pump (9) is external to the casing (1). Therefore, said conduits (10) and (11) are partially internal and partially external to the casing (1) that is crossed by the same conduits at points (A) and (B) .

A replenishing inlet (12) is provided on the lower part of the casing (1) to allow the replenishment of the primary fluid (FP) . Furthermore, on the bottom of the casing (1) there is a discharge conduit (13) allowing the discharge of the primary fluid (FP) when needed, for example for maintenance or repair operations .

Several horizontal condensing perforated plates (14), whose function is explained below, are provided at a predetermined distance from the upper base of casing (1) -

The primary fluid (FP) circulates through the heat exchange unit (6) and, through a respective conduit (15), feeds two circular series of nozzles (16, 17) positioned above and respectively below said plates The plates (14) and the nozzles (16, 17) are above said inlet (2) for the combustion fumes (2). According a simplified embodiment, only the upper nozzles (16) are provided, i.e. Only the nozzles positioned above the plates (14).

The hot combustion fumes (FS) entering the casing (1) are also aspirated upwards and, therefore, they are obliged to cross the plates (14) that are cooled by the primary fluid exiting from the nozzles (16, 17) (here the primary fluid is cold because it has released thermal energy to the secondary fluid in the unit 6) . The vapors produced by the hot fumes directed aginst the primary fluid lying on the bottom of the casing cross the plates (14), thus being subject to condensation and, falling down, create a rain that drags the solid pollutant particles of the fumes towards the bottom of the casing (1). In Fig.5 the condensed vapor falling as a rain towards the bottom of the casing is denoted by the arrows « C ».

Therefore, before exiting the casing (1), the hot combustion fumes have released thermal energy to the primary fluid and are also filtered.

Reference being made to Fig.2, inside the casing (1) there are two heat exchange units (6), each of which is connected with respective in/out conduits for the secondary fluid in order to supply heat to two different heat distribution sustems. In this case, the heated primary fluid crosses the two units (6) one after the other before reaching the nozzles (16, 17). A sensing device (18) can be positioned in correspondence of the cold fumes exit to sense the temperature of the cold fumes (FF) .

According to the example shown in Fig.3, two heat exchangers according to the present invention are connected with each other, such that the fumes exiting the heat exchanger on the left enter the heat exchanger on the right, i.e. The fumes exit of the first heat exchanger is connected with the inlet of the second heat exchanger. In this example, the primary fluid of the first heat exchanger is diathermic oil while the primary fluid of the second heat exchanger is water. According to this example, the first heat exchanger is provided with a single heat exchange unit (6) as in the example shown in Fig.l, while the second heat exchanger is provided with two heat exchange units as in the example shown in Fig.2. The arrows « FR » represent the gaseous fluids that, in each heat exchanger, move upwards and pass through the plates (14). The reference « CM » denotes a burner. More in general, the reference « CM » denotes a combustion apparatus. Fig.4 particularly shows the flows (arrows « FR ») of the gaseous fluids passing through the plates (14) that delimit labirinth paths, thus facilitating their cooling .

The hot combustion fumes (FC) entering the heat exchanger (or the first of the two heat exchanger in the configuration of Fig.3) can be combustion fumes that, for example, come from gas or hydrocarbon or biomass burners or from a turbogas power unit.

The water discharged through the duct (13) can be conveyed to the sewer system, or it can be conveyed to a purification system if this is not possible or is not permitted to enter it into the sewer.

With an experimental plant made by the inventor, the temperaure of the fumes exiting the heat exchanger was about 70 °C, and the temperature of the secondary fluid exiting the heat exchange unit was about 70°C which denotes a very fast and efficient heat exchange. The following table shows the values of several parameters obtained experimentally with fumes (FC) produced by an internal combustion engine (content of oxygen in the gaseous effluent equal to 5%) and conveyed into the heat exchanger described above.

The values shown in the table above are to be intended as values relating to possible operative conditions. For example, a further reduction of the powders and the Nox can be obtained by increasing the flow rate of the pump (9) to increase the rain effect. For example, a further reduction of the CO content can be obtained by applying an oxydation catalyst upstream of the inlet (8) .

Fig.5 shows a further preferred embodiment of a heat exchanger according to the present invention : compared to the examples shown in Fig.l and Fig.2, the cooled primary fluid exiting the heat exchange unit

(6) is directed between the penultimate and the last plate (14) as shown by reference « K ». This solution permits to reduce the amount of vapor aspirated by the aspirator (7), thus increasing the thermal efficiency of the system.

In a further possible configuration, the cooled primary fluid can be directed both to the point « K » between the plates (14) and to the nozzles (16) provided above the same plates (14).

According to the example schematically shown in Fig.6, a heat recovery unit (100), known per se, is mounted at the exit (3) , said heat recovery unit being invested by external air (AA) that, as consequence, is heated and can be conveyed to the combustion apparatus (CM) , thus increasing the efficiency thereof. To this end, a corresponding aspirator (102) can be provided along a pipe (102) for conveying the thus heated air to the combustion apparatus (CM) . By making use of the heat recovery unit (100), at least a part of the vapors that otherwise escape from the exit (3) is condensed and falls down to the heat exchanger, so that the consumption of primary fluid is reduced.

The apparatus described above can be used also for treating water coming from industrial processes. In this case, the inlet (4) of the unit (6) receives water or another fluid heated up to a predetermined temperature, the fluid exting the same unit through the output (5) . The waste water to be treated is directed into the casing (1) and it is heated by the unit (6) and therefore evaporates, the evaporation being facilitated by the aspiration on top of the apparatus. The steam thus produced is aspirated with the pollutants contained in the waste water.

In practice, the details of execution may vary in any equivalent way as in the shape, size, nature, type and arrangement of the elements indicated, without leaving the scope of the adopted solution and thus remaining within the limits of the protection granted to the present patent.

Claims

1) Heat exchanger, comprising a casing (1) adapted to delimit an internal volume of predetermined capacity, with an input (2) for hot combustion fumes or gases (FC), an outlet (3) for the cold fumes (FF), at least one input (4) for a secondary fluid (SF) which receives heat from a primary fluid (FP), an output (5) for the secondary fluid, a heat exchange unit (6) in which the secondary fluid (SF) circulates while receiving heat from the primary fluid (FP) and an aspirator (7) for the extraction of the cold fumes (FF) through said outlet (3) , characterized in that it comprises condensing means placed in the casing (1) above the said inlet (2) for the hot gases or fumes (FC) and adapted to cause the condensation of vapors produced by the hot gases or fumes (FC) investing the primary fluid inside the casing (1).

2) Heat exchanger according to claim 1 characterized in that said condensing means comprise a plurality of perforated plates (14).

3) Heat exchanger according to claims 2 and 3, characterized in that said plates (14) are positioned horizontally.

4) Heat exchanger according to claim 1 characterized in that said condensing means are cooled by the primary fluid (FP) exiting from the heat exchange unit (6) .

5) Heat exchanger according to claims 1 and 4 characterized in that the primary fluid exiting from the heat exchange unit (6) is delivered to the condensing means through a plurality of nozzles (16, 17) .

6) Heat exchanger according to claim 5 characterized in that said nozzles (16, 17) are placed above the condensing means. 7) Heat exchanger according to claim 5 characterized in that said nozzles (16, 17) are placed above and below the condensing means.

8) Heat exchanger according to claim 5 characterized in that said nozzles (16, 17) are placed between the condensing means.

9) Heat exchanger according to one or more of the preceding claims characterized in that it comprises a recirculation pump (9) for the circulation of the primary fluid (FP) through the heat exchange unit (6).

10) Heat exchanger according to one or more of the preceding claims characterized in that the fumes (FF) that pass through said outlet (3) provoke the heating of air (AA) drawn from the outside and then sent to a combustion apparatus (CM) .