ITRM20100361A1 - INTERMEDIATE HEAT EXCHANGE DEVICE FOR HEATING CIRCUITS. - Google Patents

Description

Intermediate heat exchange device for heating circuits

The present invention relates to an intermediate heat exchange device for heating circuits, in particular between a heat carrier fluid passing through a boiler and a heat carrier fluid passing through a user system.

The invention relates in particular to an intermediate heat exchange device of the above type, suitable for use with boilers for heating civil and industrial buildings.

It is known that it is possible to make different types of boilers for heating homes and buildings. Some of them use fuels such as natural gas; others use LPG, kerosene, diesel oil; still others use solid fuels, such as the so-called pellets.

In any case, the function of the boilers is to heat the thermal carrier fluids of one or more user circuits, such as one or more heating circuits, within suitable heat exchange zones.

In the private sector, the most widespread type of boilers is that of wall-mounted gas boilers, while the other types, with higher thermal power, are generally used for condominiums, public offices and companies.

Traditional wall-hung boilers are present on the market with predetermined thermal power values, so that they can be chosen in relation to the energy needs of the building to be heated.

In fact, however, low-power boilers have completely disappeared from the market, because it is intended to use boilers of higher power than would actually be necessary, by controlling their operation through internal and / or external temperature probes.

A particularly important problem of this type of use lies in the fact that the boiler operates between a state of quiescence and a state of work, which could be the maximum achievable by the boiler, with a low efficiency. In fact, the efficiency decreases as the temperature difference ΔΤ between the heat source and the thermal carrier fluid, typically water, increases. For this reason, maximum performance can be obtained by heating the water just enough to keep it at a constant temperature, avoiding the alternation of quiescent and work phases.

To reduce the negative consequences due to this problem, according to the known art, so-called modulating boilers have been proposed, capable of working at different power levels, gradually providing the heat necessary for heating the carrier medium, without exceeding in terms of values of ΔΤ. The boilers according to this technology have a predefined limited number of operating levels and are particularly expensive, since they have a complex system of modular burners.

However, floor-standing boilers do not have any type of modulation system for their operating conditions. Furthermore, this type of boiler is very negatively affected by cases in which the ΔΤ is very high, with the risk that the welds of the heat exchange tube bundle may jump, when a large flow of water enters the boiler at a temperature very different from that the one inside the boiler itself.

In this context, the solution according to the present invention comes to be inserted, which proposes to insert, between the boiler and the heating circuit, an intermediate heat exchange device, designed to dampen the temperature variations of the thermal carrier fluid that reaches the boiler. from the heating circuit.

The object of the present invention is therefore to provide an intermediate heat exchange device for heating circuits which allows the limits of the solutions according to the known technology to be overcome and the technical results described above to be obtained.

A further object of the invention is that said device can be produced with substantially contained costs, both as regards production costs and as regards management costs.

Not least object of the invention is to provide an intermediate heat exchange device for heating circuits which is substantially simple, safe and reliable.

A first specific object of the present invention therefore forms an intermediate heat exchange device for heating circuits, comprising a heat exchanger, a first side of which is equipped with means for connection to a heat generator device, respectively a delivery duct and a return duct on the heat generator side, and a second side of which is equipped with means for connection to the users, respectively a delivery duct and a return duct on the user side; a recirculation pump arranged alternatively on said delivery duct or said user-side return duct; and a four-way valve, interposed between said user-side return duct and said user-side delivery duct, defining portions of said ducts, respectively an inlet duct to said heat exchanger and an outlet duct from said heat exchanger .

Preferably, according to the invention, said intermediate heat exchange device can further comprise an expansion vessel, arranged alternatively on said delivery duct or said return duct on the heat generator side, and further an expansion vessel, alternatively arranged on said delivery duct or said user-side return duct.

Even more preferably, according to the invention, said heat exchanger and said expansion tank are integrated within the same structure.

Furthermore, according to the invention, said intermediate heat exchange device comprises a further recirculation pump arranged alternatively on said delivery duct or said return duct on the heat generator side.

A second specific object of the present invention also forms a heat generator comprising an intermediate heat exchange device as defined above, connected to said device through a delivery connection and a return connection.

Preferably, according to the invention, said heat generator can comprise means for activating a recirculation pump arranged on one of the user-side ducts of said intermediate heat exchange device and means for activating a recirculation pump arranged on one of the delivery-side ducts boiler or user circuit of said intermediate heat exchange device.

The intermediate heat exchange device for heating circuits of the present invention finds application in pre-existing or even new heating systems, in particular in the heating systems of a building, be it of small or even large power. In particular, an advantageous use of the intermediate heat exchange device for heating circuits according to the present invention is envisaged for condominium users with boilers with power equal to or less than 12000 kW or for domestic users of single residential units with boilers with equal or less power. to 34 kW.

Advantageously, the intermediate heat exchange device of the invention makes it possible to reduce fuel consumption by 20 - 30%, while still guaranteeing optimal heating.

The aforementioned device can be provided inside a boiler. In particular, it can also be used in systems with condensing boilers.

The present invention will now be described, for illustrative but not limitative purposes, according to some of its preferred embodiments, with particular reference to the figures of the attached drawings, in which:

Figure 1 schematically shows an intermediate heat exchange device for heating circuits according to the present invention;

Figure 2 shows a first example of insertion of the intermediate heat exchange device for heating circuits of Figure 1 in a circuit of a heating system;

Figure 3 shows a second example of insertion of the intermediate heat exchange device for heating circuits of Figure 1 in a circuit of a space heating and hot water production system for sanitary ware;

- figure 4 shows a third example of insertion, in which two intermediate heat exchange devices for heating circuits as shown with reference to figure 1 are respectively inserted in a first circuit of a hot water production plant through a solar thermal system and in a second circuit of a space heating and sanitary hot water production system through a boiler;

Figure 5 shows an example of insertion of the intermediate heat exchange device for heating circuits of Figure 1 in a circuit of a heating system;

figure 6 shows a bar diagram of the efficiency of the heating system of figure 5 with and without the intermediate heat exchange device of the present invention;

figure 7 shows a bar diagram of the consumption of the heating system of figure 5 with and without the intermediate heat exchange device of the present invention; And

Figure 8 shows a bar diagram of the thermals rendered by the heating system of Figure 5 with and without the intermediate heat exchange device of the present invention.

The present invention provides for the interposition of an intermediate heat exchange device between a heat carrier fluid of a circuit that passes through one or more users (hereinafter respectively defined as user fluid and user circuit) and a heat carrier fluid of a circuit which passes through a boiler (hereinafter referred to as fluid-boiler and circuit-boiler respectively). In particular, a boiler-circuit separated from said user-circuit is configured, which supplies radiant elements and / or the like, said boiler-circuit being significantly shorter than said user-circuit.

The method of the invention also provides for the circulation of the fluid-users to be regulated by means of an additional recirculation pump, controlled synchronously with the recirculation pump generally present in the boilers.

Furthermore, an essential feature for a more efficient control of the temperature through the device of the present invention consists in the presence of a four-way valve arranged on the return pipe of the user circuit, to divert the user fluid on the delivery pipe of the user circuit, without going through the heat exchanger. The amount of user fluid that is recirculated to the delivery duct of the user circuit instead of returning to the heat exchanger is controlled by a temperature sensor located on the delivery duct of the user circuit, which controls the four-way valve located on the return pipe of the utility circuit.

With reference to the figures, an intermediate heat exchange device according to the present invention is illustrated in Figure 11 with the numerical reference 10 and comprises a heat exchanger 11 suitable for exchanging heat between a first thermal carrier fluid, in circulation between the heat exchanger. heat 11 is a boiler (not shown) and therefore called the boiler fluid, and a second thermal carrier fluid, in circulation between the heat exchanger 11 and the users and therefore called the user fluid.

The connections or ducts 12 and 13 connect the heat exchanger 11 to the user circuit. The connections or ducts 14 and 15 connect the exchanger 11 to the boiler circuit.

The intermediate heat exchange device also comprises an expansion tank 16 connected to said exchanger 11 on the return connection 12 of the fluid-users, for example indirectly, by means of a branch pipe 17.

On the same connection 12 (but alternatively it could also be on connection 13) a connection or duct 18 is connected for supplying the user circuit, for example when the pressure in it should be insufficient or during the commissioning phase of the 'plant. The supply of said user circuit through the duct 18 can also be managed automatically by means of an automatic pressure gauge valve 19 on said duct 18. Furthermore, a ball valve 20 of the heavy type can optionally be present to interrupt the supply, to for example during system maintenance or when replacing a radiator.

A first manual relief valve 21 and a first safety relief valve 22 are connected to the delivery duct 13 of the user fluid. Furthermore, the circulation of the user fluid is ensured by a recirculation pump 23 inserted in the delivery duct 13 but which could alternatively but less preferably be inserted on the return duct 12.

On the return pipe 12 of the fluid-users there is a four-way valve 24, which is interposed between the return pipe 12 and the delivery pipe 13, defining portions of said pipes, respectively an inlet pipe 12 'in the exchanger 11 and an outlet duct 13 'from the heat exchanger 11, with the possibility of diverting the user fluid directly onto the delivery duct 13 of the user circuit, without passing through the heat exchanger 11. The entity of the user fluid which is diverted directly to the delivery duct 13 instead of returning to the heat exchanger 11 is controlled by a temperature meter 25 arranged on the delivery duct 13 of the user circuit, which controls the four-way valve 24.

Advantageously, the heat exchanger 11 and the supply duct 18 comprising the automatic pressure gauge valve 19 can be assembled together with the expansion tank 16 (as shown with reference to Figure 1), so as to create a single body provided towards the external of five hydraulic connections, indicated with the numerical references 12, 13, 14, 15 and 18, and two relief valves 21, 22, one of which is safety 22.

The operation of the recirculation pump 23 is activated in relation to the operation of a further recirculation pump, not shown, generally present in the boiler, which normally circulates the fluid-users, but which in the configuration proposed by the present invention provides for the circulation of the boiler fluid between the boiler and the intermediate heat exchange device 10. In particular, the recirculation pump 23 comprised by the intermediate heat exchange 10.

A first fitting 26 relative to the return pipe 12 of the user circuit comprises an inclined filter. Similarly, a second fitting 27 relative to the delivery duct 14 of the boiler circuit comprises an inclined filter.

Figure 2 shows the use of an intermediate heat exchange device 10, according to the invention, in cooperation with a wall-mounted boiler 30 in a heating system with two users 31.

The circulation of the boiler fluid is, as mentioned above, ensured by a recirculation pump, not shown, inside the boiler 20, whose operation is controlled by a control system by means of electrical connection means also connected to the recirculation pump 23 of the circuit-users.

Said recirculation pump 23 is preferably of the inverter type, ie able to vary the flow rate according to the quantity of fluid present in the user circuit.

A make-up duct (not shown) supplies the boiler circuit, similarly to the function performed by the duct 18 for the user circuit. Figure 2 also schematically represents the user circuit in which there are, for example, two floor radiators 31.

Figure 3 shows the use of an intermediate heat exchange device 10, according to the invention, in cooperation with a boiler 20, in a system which provides two separate user circuits, respectively dedicated to room heating, by means of the radiators 32 and for the production of hot water. In particular, the delivery duct 13 is divided into a heating circuit delivery duct 13 'and a water circuit delivery duct 13 ". Both circuits also have return ducts, 12' and 12" respectively. The heating circuit delivery duct 13 'forms the heating coil of a water heating tank 33, which supplies water to a vessel 34 through a delivery duct 35 and a return duct 36. From the vessel 34, the water is directly sent to the users 37 (taps, showers, etc.) of the hot water circuit.

With reference to Figure 4 it is shown the use of two intermediate heat exchange devices 10, according to the invention, respectively in cooperation with a boiler 20, in a first system which provides two separate user circuits, respectively dedicated to room heating, by means of the radiators 32 and for the production of hot water, by means of a water heater 33 and with a solar thermal device 40, in a further circuit for heating the water of the water heater 33. In the figure, to indicate the characteristics of the first system, are used the same numerical references as in figure 3. Furthermore, with reference to the connection with the solar thermal device 40, there is a return duct 44 to the intermediate heat exchange device 10 and a delivery duct 45.

Figure 5 shows the use of an intermediate heat exchange device 10, according to the invention, in cooperation with a system comprising two boilers 20a and 20b arranged in parallel with each other.

The circulation of the boiler fluid is, as mentioned above, ensured by the recirculation pump 41, while the duct 42 supplies the boiler circuit. On the user circuit there are, for example, three user lines with delivery pipes 51, 52, 53 and return pipes 61, 62, 63. The whole is equipped with a system of by-pass valves that allow the device to be isolated. of intermediate heat exchange 10 from the rest of the system, for example during maintenance of the device itself. Figure 5 shows a first group 71 of bypass valves arranged on the line that goes from the boiler to the users and a second group 72 of by-pass valves arranged on the line that returns from the users to the boiler.

The intermediate heat exchange device, object of the present invention, can be added to pre-existing systems by interrupting the power supply circuit of the user circuit, or it can be integrated inside a boiler or it can be supplied separately at the time of installation, both built-in and outdoor.

The heat exchanger is preferably with brazed plates, of similar dimensions to the known ones, and even more preferably with a circulation length double that of those on the market, to improve the efficiency of heat exchange between the two liquids.

Example

The intermediate heat exchange device according to the present invention, used according to the configuration shown with reference to Figure 5, made it possible to determine the efficiencies and consumption reported in the following table and in Figures 6 - 8.

In particular, the intermediate heat exchange device according to the present invention was arranged in a heating system, which was operated first in basic mode, i.e. by bypassing the device of the invention, and subsequently in optimized mode by means of the exchange device. intermediate thermal according to the present invention. In both cases, the implant was stabilized at a constant temperature and the test continued for a period of 2 hours. The heat released to the environment in kW / h was then measured with a heat counter, and the comburent consumption, subsequently converted into liters, was measured with an electronic scale. In particular, a low-polluting white diesel oil, marketed under the name Gecam, was used as comburent.

The test in basic mode was carried out with a boiler temperature equal to 65 ° C, and the temperatures of the thermal carrier fluid measured, in flow and return in the user circuit, had an average value of 61.10 ° C respectively. and 55.51 ° C. The heat returned to the environment was quantified as equal to 276.25 kW / h (figure 8) and the fuel consumed as equal to 41.2 L (figure 7). The resulting yield of the plant was 73.93 (figure 6).

The test in optimized mode by means of the intermediate heat exchange device of the present invention was carried out with a boiler temperature equal to 80 ° C, and the temperatures of the thermal carrier fluid measured, going and returning in the user circuit, had respectively an average value of 61.01 ° C and 55.93 ° C. The heat returned to the environment was quantified as equal to 288.30 kW / h (figure 8) and the fuel consumed as equal to 34.1 L (figure 7). The resulting yield of the plant was 93.22 (figure 6).

The advantages deriving from the application of the present invention are clear:

- the intermediate heat exchange device can be inserted in any pre-existing system of any potential by approaching the operation of the boiler device to that of a modular device;

- the intermediate heat exchange device inserted on boilers with adjustable burner makes it possible to set a lower power and a lower consumption while maintaining the heat input to the heated building unchanged, as the burner is induced to work at a reduced rate and enter modulation more frequently;

- the intermediate heat exchange device inserted on floor boilers, in cast iron or steel, reduces the thermal shock and the consequent breakage of the elements and / or the desoldering of the tubes that form the tube bundle, since the boiler is kept substantially at temperature constant. In fact, the temperature will vary progressively in the first part of operation and will remain constant in the second. Therefore, an excessive flow of cold liquid will never reach the boiler, which occurs in known systems equipped with a thermostat.

A further advantage is represented by the fact that the recirculation pump, the expansion tank and the heat exchanger and possibly all the other components are housed in a single container, so as to make the device of the invention ready for use. installation on an existing system. Advantageously, this container is compact and has an external profile from which the delivery connections and the return connections protrude.

The present invention has been described by way of illustration, but not of limitation, according to its preferred embodiments, but it is to be understood that variations and / or modifications may be made by those skilled in the art without thereby departing from the relative scope of protection, as defined from the attached claims.

Claims (8)

CLAIMS 1) Intermediate heat exchange device (10) for heating circuits, characterized in that it comprises a heat exchanger (11), a first side of which is equipped with means for connection to a heat generator device, respectively a delivery duct (15) and a return duct (14) on the heat generator side, and a second side of which is equipped with means for connection to the users, respectively a delivery duct (13) and a return duct (12) on the user side; a recirculation pump (23) arranged alternatively on said delivery duct (13) or said return duct (12) on the user side; and a four-way valve (24), interposed between said return duct (12) on the user side and said delivery duct (13) on the user side, defining portions of said ducts, respectively an inlet duct (12 ') to said heat exchanger (11) and an outlet duct (13 ') from said heat exchanger (11). 2) Intermediate heat exchange device (10) for heating circuits according to claim 1, characterized by the fact that it further comprises an expansion vessel, arranged alternatively on said delivery duct (15) or said return duct (14) on the generator side thermal. 3) Intermediate heat exchange device (10) for heating circuits according to claim 1 or 2, characterized in that it further comprises an expansion vessel (16), arranged alternatively on said delivery duct (13) or said return duct (12) user side. 4) Intermediate heat exchange device (10) for heating circuits according to any one of the preceding claims, characterized in that said heat exchanger (11) and said expansion tank (16) are integrated within the same structure. 5) Intermediate heat exchange device (10) for heating circuits according to any one of the preceding claims, characterized in that it comprises a further recirculation pump (41) arranged alternatively on said delivery duct (15) or said return duct ( 14) heat generator side. 6) Thermal generator (20, 40) comprising an intermediate heat exchange device (10) as defined according to any one of the preceding claims, connected to said device through a delivery connection (15) and a return connection (14). 7) Thermal generator (20, 40) according to claim 6, characterized in that it comprises means for activating a recirculation pump (23) arranged on one of the user-side ducts of said intermediate heat exchange device (10). 8) Heat generator according to claim 6 and 7, characterized in that it comprises means for activating a recirculation pump (41) arranged on one of the ducts on the boiler delivery side or user circuit of said intermediate heat exchange device (10).