EP1892480B1 - Continuous flow-heater for fluid, use of said continuos-flow heater and method of heating a workfluid in such a hydraulic circuit - Google Patents

Abstract

The heater has a storage tank (1) accommodating heating liquid e.g. industrial water. A coaxial pipe-heat exchanger (2) is arranged in the storage tank and exhibits a coiled external pipe and an internal pipe. The liquid contained in the storage tank flows through the internal pipe. The liquid flows through a ring cross section between the internal pipe and the external pipe, and the internal pipe and external pipe are completely separated after liquid guide and connections.

Description

The invention relates to a continuous heater for a Nutzflüssigkeit with a storage container which receives a heat-emitting liquid.

Such continuous heaters are known. The term means that the use liquid is heated by flowing inside through the tubes of a heat exchanger, which is heated from the outside. The useful liquid is therefore not heated by the fact that a larger reservoir of the liquid is constantly heated. A practical application for the continuous heater according to the invention is the provision of utility or service water in residential buildings. The service water is needed there for the purposes of the household, the kitchen and in the bath for bathing or showering. The special feature of domestic water abstraction is that at irregular intervals highly fluctuating amounts of hot water are to be taken. The available amount of removable liquid is often insufficient.

An example of a prior art continuous-flow heater is shown in FIG DE 41 42 488 A1 , In this continuous-flow heater, the heating of the useful liquid is combined with the heating of the heating water. The exhaust gases of a gas burner flow through a coiled tube, which is formed from a coaxial tube. Through the inner tube of the coaxial tube flows during removal of the useful liquid, while the heating water is guided in the annular space between the inner and the outer tube. So that a sufficient amount of useful liquid can be made available at all times, a storage container for the useful liquid is connected downstream of the coaxial tube heat exchanger. This storage container is a working according to the displacement principle stratified storage; the useful liquid is conveyed by a charge pump in circulation through the coaxial heat exchanger and the stratified storage. The removal of the useful liquid takes place from the stratified storage.

Another embodiment shows a continuous-flow heater according to the DE 198 07 657 C1 , In this known embodiment, a heat exchanger made of coiled tubes is arranged in a storage container. The storage container is filled with water, which is heated by various means. For this purpose, a built-in or adjacent boiler can serve. In addition, a solar system or a heat pump can be used to heat the storage water. No own storage is provided for the useful liquid. In order for the heat capacity of the storage water is sufficient to always heat a sufficient amount of liquid, the storage tank must be sufficiently large, and it must be possible to heat it up briefly strong.

Another possibility shows the DE 38 27 585 C2 , This document deals with a service water storage heater. A large-sized storage heater is used to hold the service or use liquid. In the storage container, a heat exchanger made of coiled pipes is also installed. The tubes are arranged in the manner of a cylindrical thread. A first section of the heat exchanger is provided with coaxial tubes, wherein an inner tube is arranged in an outer tube. In the inner tube enters the cold liquid and enters the inside of the storage container at the end of the inner tube. In the outer tube, a heat-emitting liquid is performed, which initially fills the entire cross-section of the outer tube and is then guided in the annular space between the outer and inner tube. In the area of the coaxial tube, the heat-emitting liquid flows in countercurrent to the use liquid. In this arrangement, the incoming heat-emitting liquid thus first heats the already in the storage container used useful liquid and then in heat exchange with the inner tube of the coaxial also directly the incoming cold liquid. The heat-releasing liquid becomes thereby already well utilized; but it is still a very large storage tank for the liquid used required.

DE 20 2004 009559 U1 shows a heat exchanger with an upwardly open, pressure-free container, which surrounds an interior space (2). The interior (2) is filled with a carrier medium (18). In an upper part of the interior (2) is a co-axial heat exchanger in the inner tube, a refrigerant flows. The coaxial heat exchanger is surrounded by the carrier medium (18) located in the interior. Fresh water is heated in the coaxial annular tube of the heat exchanger.

Due to the separate guidance of the refrigerant in the inner tube and the carrier medium in the interior, a temperature influencing of the respective other heat-emitting medium is achieved via the fresh water flowing in the annular space of the co-axial heat exchanger. It may happen that an overheated coolant by heat transfer to the fresh water, which further warms the carrier medium in the interior.

DE 195 35 265 C1 shows a located in a container of a hot water heater two-chamber heat exchanger, which is formed of two co-axial helical coiled tubes. In this case, a useful liquid is displaced into an inner tube of the two-chamber heat exchanger by supplying fresh water in the container, and flows through an outflow, which is connected to the inner tube, from the hot water heater. In the annular outer region of the two-chamber heat exchanger fresh water flows countercurrently into the container. A disadvantage of this device is that the entire water in the container must be kept at a certain temperature level, so that water can be removed from the container a certain temperature.

The invention has for its object to provide a continuous flow heater for a Nutzflüssigkeit with a storage container which receives a heat-emitting liquid, which can be dispensed by improving the heat transfer to a storage for the Nutzflüssigkeit.

The solution of this object is achieved by the entirety of the features of claim 1.

It thus consists in a continuous flow heater for a Nutzflüssigkeit, with a storage container which receives a heat-releasing liquid, and with a Koaxialrohr heat exchanger, which is arranged in the storage container and consists of a coiled outer tube and an inner tube located therein, wherein the inner tube is flowed through by the same heat-emitting liquid contained in the storage container, while the ring cross-section between the inner and outer tube is flowed through by the Nutzflüssigkeit and the inner and outer tube after liquid management and connections are completely separated.

In the continuous-flow heater according to the invention, the useful liquid flowing through the coaxial-tube heat exchanger is simultaneously heated from the inside and from the outside. The heating from inside is done by the heat-emitting liquid flowing through the inner tube of the coaxial tube. The heating from the outside is carried out by the heat-releasing liquid in the storage container. As a result, the heat transfer can make very cheap, and also the storage container for the heat-emitting liquid must not be excessively large. The embodiment of the invention also has the advantage that not a storage container for the useful liquid (service water), in which the liquid is more often, must be kept clean and germ-free, but only the annulus of the coaxial heat exchanger, which is easier to accomplish with the usual technical and chemical means.

Advantageous embodiments of the continuous-flow heater according to the invention are specified in claims 2 to 10.

Claim 11 is directed to a use of the continuous heater according to the invention for the hygienic heating of domestic water in buildings. The claims 12 to 14 relate to a hydraulic circuit of a heater for a Nutzflüssigkeit, wherein by a prior art according to the DE 38 27 585 C2 is assumed.

According to the invention is thus also the method for heating a Nutzflüssigkeit by a heat-emitting liquid in a hydraulic circuit with a storage container in which a Koaxialrohr heat exchanger consisting of a coiled outer tube and an inner tube located therein, is arranged, with separate liquid guide and separate terminals inner and outer tube and with the mouth of one end of the inner tube in the interior of the storage container, wherein the hydraulic circuit is such that the Nutzflüssigkeit is passed through the annular cross-section between the outer tube and the inner tube, while the heat-emitting liquid through the inner tube flows and is contained in the storage container for charging the Koaxialrohr heat exchanger from the outside.

Thanks to the method according to claim 12 is thus from the hot water storage heater according to the DE 38 27 585 C2 a continuous flow heater for the service or use liquid with the advantages, as have already been enumerated for the claim 1.

Advantageous embodiments of the hydraulic circuit are specified in claims 13 and 14.

• Fig. 1 ist ein Längsschnitt durch einen Durchlauf-Erhitzer gemäß der Erfindung.
• Fig. 2 zeigt in einem Querschnitt das Prinzip des Koaxialrohr-Wärmeaustauschers bei dem erfindungsgemäßen Durchlauf-Erhitzer.
• Fig. 3 verdeutlicht das Detail 1 der Fig. 1 in vergrößerter Darstellung.
• Fig. 4 zeigt den Schnitt gemäß der Linie A-A in Fig.1.

The invention will be explained in more detail with reference to an embodiment shown in the drawing. In the figures, the following is shown:

• Fig. 1 is a longitudinal section through a flow heater according to the invention.
• Fig. 2 shows in a cross section the principle of the coaxial tube heat exchanger in the inventive flow heater.
• Fig. 3 clarifies the detail 1 of the Fig. 1 in an enlarged view.
• Fig. 4 shows the section along the line AA in Fig.1 ,

FIG. 1 shows the continuous heater according to the invention in a longitudinal section. It consists of a storage container 1, which is shown in the embodiment chosen here as a standing container with a vertical longitudinal axis. The storage container 1 can be designed as a pressureless or pressure-resistant container and have a divided or closed insulation 17.

In the storage container 1, various heat exchangers are housed. In its upper part is the coaxial heat exchanger 2. It extends only over part of the height of the storage container 1 down, in the illustrated embodiment, up to the section line AA. The coaxial tube heat exchanger 2 consists of coiled tubes. In the exemplary embodiment, a spiraling in the manner of a cylindrical screw thread, as in a coil spring shown. However, the coaxial tube heat exchanger 2 could also be spiral-shaped or spiral-shaped (as in a conical spring). The coiled tubes of the coaxial tube heat exchanger 2 are formed as coaxial tubes, as a cross section through a single tube according to the FIG. 2 shows. There is an inner tube 3 in an outer tube 4, wherein between the inner tube 3 and the outer tube 4, a ring cross-section 6 is formed. The solid cross section of the Inner tube 3 is designated by the reference numeral 5. Inner and outer tubes 3, 4 may be rigid or flexible.

The inner tube 3 and the outer tube 4 are guided completely separated after liquid management and connections. For connection, an upper T-piece 7 and two lower T-pieces 8a and 8b are provided. The upper T-piece 7 is provided at the top of the storage container 1 and in FIG. 3 shown enlarged. In the context of Figures 1 and 2 shows that via the upper T-piece 7, the inner tube 3 is guided to a first switching valve 14a and the outer tube 4 to a second switching valve 14b.

The lower tees 8a and 8b are located at the lower end of the coaxial tube heat exchanger 2 and are in FIG. 4 shown enlarged. The continuing connections are in FIG. 4 also indicated. The inner tube 3 of the coaxial tube heat exchanger 2 is thus sealed out through the first lower T-piece 8 a and the second lower T-piece 8 b. It is brought into contact with the interior of the storage container 1 at a location, not shown. However, it can also be fed directly to the interior of the storage container 1 via the first lower T-piece 8a.

The outer tube 4 of the coaxial tube heat exchanger 2 communicates via the two tees 8 a and 8 b with a circulation line 15, which is guided to the second switching valve 14 b, but is also in communication with a pump 16. Out FIG. 4 does not immediately indicate that there is also a downwardly opening at the first lower tee 8a; The first lower T-piece thus forms a spatial or double tee. About this additional opening, the outer tube 4 is connected to a normal pipe heat exchanger 9 in connection.

It consists of normal tubes, for example made of stainless steel, with a solid cross-section and is connected in series via the first lower T-piece 8a with the annular cross-section of the coaxial tube heat exchanger 2. In the illustrated Embodiment, it extends into the bottom area of the storage container 1. Its terminal 9a is guided out there.

Concentrically surrounding the coaxial tube heat exchanger 2 and the normal tube heat exchanger 9, three additional heat exchangers 10, 11 and 12 with separate own connections are also provided in the storage container 1. The auxiliary heat exchangers 10, 11, 12 may for example be connected to solar registers or to a system for heat recovery.

In its intended use, the heat-emitting liquid is supplied by means of a pump 13 to the hitherto described flow heater via the connecting line 20. Via the first switching valve 14a and the upper T-piece 7, the heat-releasing liquid passes into the solid cross section 5 of the inner tube 3, which is located in the coaxial tube heat exchanger 2. By way of the first switching valve 14a and the lower tees 8a and 8b, however, there is also a connection to the interior of the storage container 1. By means of thermal circulation or forced delivery by means of the pump 13, the heat-releasing liquid can pass through the storage container 1 and the solid cross-section 5 the inner tube 3 are promoted. In this case, a cycle through the inner tube 3 is possible without that heat-emitting liquid is supplied from the outside. It is essential, above all, that the same heat-emitting liquid acts on the ring cross-section 6 of the coaxial tube heat exchanger 2 both from the inside and from the outside. The respectively desired and required flow state of the heat-emitting liquid can be controlled in accordance with a first temperature sensor 18 (measuring point) which monitors the temperature of the useful liquid.

The useful liquid is fed via the connection 9a to the normal-tube heat exchanger 9 and arrives at the transition point at the first lower T-piece 8a in the annular cross-section 6 of the coaxial heat exchanger 2. It then flows as needed on the upper T-piece 7 and second switching valve 14b to the consumer. The Nutzfiüssigkeit but can also be performed in the circulation through the circulation line 15.

The desired flow guidance can be adjusted automatically or manually in accordance with a second temperature sensor 19. The two liquids can basically be conducted in countercurrent or direct current within the coaxial tube heat exchanger.

The preferred field of application of the described continuous-flow heater is the hygienic heating of domestic water in buildings. Therefore, as the working water is usually supplied cold water. This heats up as it flows through the normal-pipe heat exchanger 9, because it is acted upon from the outside by the heat-emitting liquid, which is located in the storage container 1. When flowing through the coaxial heat exchanger 2 is still the heating from the inside is added, because the located in the inner tube 3 heat-emitting liquid also heats the Nutzflüssigkeit.

The additional heat exchangers 10, 11, 12 can additionally heat the heat-releasing liquid present in the storage container 1, which acts on the normal-tube heat exchanger 9 and the coaxial-tube heat exchanger 2 from the outside. These additional heat exchangers 10, 11, 12 can be arranged individually or together. They are particularly advantageous when additional heat sources such as solar registers or systems for heat recovery are available, which are independent of the heat source through which the heat-dissipating liquid supplied to the water heater has received its heat at the beginning.

The purpose of the described arrangement is the heating of industrial water. If there is a cooled liquid in the storage container 1 and the solid cross-section of the inner tube 3, a cooling effect naturally results for the use liquid.

The useful liquid is withdrawn as needed via the second switching valve 14b. The outlet temperature is monitored via the second temperature sensor (measuring point) 19. If the outlet temperature is too high, the Useful liquid also be passed completely or as a partial flow through the circulation line 15 in the circuit through the coaxial heat exchanger.

The circulation line 15 can also be used to clean by means of the pump 16, the lines of water of the continuous flow heater, for example, also for the control of Legionella.

References list

1

storage container

2

Coaxial tube heat exchanger

3

inner tube

4

outer tube

5

Full cross section

6

Ring cross section

7

upper tee

8a

first lower tee

8b

second lower tee

9

Normal tube heat exchanger

9a

Connection of the standard pipe heat exchanger

10

first additional heat exchanger (top)

11

second additional heat exchanger (middle)

12

third auxiliary heat exchanger (below)

13

pump

14a

first changeover valve

14b

second changeover valve

15

circulation line

16

pump

17

insulation

18

first temperature sensor (measuring point)

19

second temperature sensor (measuring point)

20

connecting cable

Claims (14)

1. Continuous flow heater for a work fluid,
   with a storage tank (1) which receives a heat-dispensing liquid,
   and with a coaxial tube heat exchanger (2) which is arranged in the storage tank (1) and consists of a coiled outer tube (4) and an inner tube (3) located in the latter, while the work fluid flows through the annular cross section (6) between the inner and outer tube (3, 4), and the inner and outer tube (3, 4) are completely separated in terms of guiding of liquid and connections, characterized in that the same heat-dispensing liquid which is contained in the storage tank (1) flows through the inner tube (3),
2. Continuous flow heater according to Claim 1, in which the storage tank (1) is designed as an upright-type tank with a vertical longitudinal axis, and the coiled outer tube (4) and inner tube of the coaxial tube heat exchanger (2) are coiled in the manner of spirally arranged or cylindrical screw threads, the central line of which approximately corresponds to that of the storage tank (1).
3. Continuous flow heater according to Claim 1 or 2, in which the inner tube of the coaxial tube heat exchanger (2) is in each case guided through the outer tube (4) of the coaxial tube heat exchanger (2) in a manner sealed at the entry and exit point of the heat-dispensing liquid by means of T-shaped connecting pieces (7, 8).
4. Continuous flow heater according to Claim 2 or 3, in which the coaxial tube heat exchanger (2) is located at the top of the storage tank (1) and extends only over part of the height of said storage tank, and a standard tube heat exchanger (9) is arranged in the storage tank (1) below the coaxial tube heat exchanger (2), wherein the arrangement is provided in such a manner that the work fluid passes successively from the bottom to the top through the circular cross section of the standard tube heat exchanger (9) and the annular cross section (6) of the coaxial heat exchanger (2), i.e. the standard tube heat exchanger (9) is connected upstream of the coaxial tube heat exchanger (2).
5. Continuous flow heater according to Claim 4, in which the standard tube heat exchanger (9) consists of a coiled stainless steel tube which is wound in the manner of cylindrical screw threads.
6. Continuous flow heater according to one of Claims 3 to 5, in which the entry point for the heat-dispensing liquid is located at the top of the coaxial tube heat exchanger (2) and the exit point is arranged in the transition region between the coaxial tube heat exchanger (2) and the standard tube heat exchanger (9).
7. Continuous flow heater according to Claim 6, in which the inner tube (3) of the coaxial tube heat exchanger (2) leads at the exit point into the storage tank (1).
8. Continuous flow heater according to Claim 6, in which the inner tube (3) of the coaxial tube heat exchanger (2) is guided through the storage tank (1) to the outside in a manner sealed at the exit point.
9. Continuous flow heater according to one of Claims 4 to 8, with one or more additional heat exchangers (10, 11, 12) which, as standard tubes in the form of cylindrical screw threads, surround sections of the standard tube heat exchanger (9) and through which a heat-dispensing liquid flows, said liquid being guided and heated separately from that heat-dispensing liquid which is located in the inner tube (3) of the coaxial tube heat exchanger (2) and the storage tank (1).
10. Continuous flow heater according to Claim 9, in which the additional heat exchangers (10, 11, 12) are connected to a solar register or to a system for recovering heat.
11. Use of a continuous flow heater according to Claims 1 to 10 for the hygienic heating of service water in buildings.
12. Method of heating a work fluid by means of a heat-dispensing liquid in a hydraulic circuit with a storage tank (1) in which a coaxial tube heat exchanger (2), consisting of a coiled outer tube (4) and an inner tube (3) located in the latter, is arranged, with separate guiding of liquid and separate connections of inner and outer tubes (3, 4), wherein the hydraulic circuit is effected in such a manner that the work fluid is conducted through the annular cross section (6) between the outer tube (4) and the inner tube (3) while said heat-dispensing liquid flows through the inner tube (3) and is contained in the storage tank (1) so as to act upon the coaxial tube heat exchanger from the outside.
13. Method according to Claim 12, in which, according to the position of a first switchover valve (14a), the heat-dispensing liquid in the inner tube (3) of the coaxial tube heat exchanger (2) is either circulated thermally in the circuit or, if the work fluid drops below a certain temperature, is operated at the output of the coaxial tube heat exchanger (2) as a heated feed stream.
14. Method according to Claim 12 or 13, in which the work fluid, according to the temperature thereof at the exit from the coaxial tube heat exchanger (2), is either supplied directly to the consumption point or is entirely or partially conveyed in the circuit to the coaxial tube heat exchanger (2), wherein the circulation line (15) serving for this purpose can also be switched over for cleaning and disinfecting the coaxial tube heat exchanger (2).

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