SECONDARY CIRCUIT WITH HEATING CIRCUIT MANIFOLD

Description

[0001] The invention relates to a secondary circuit with a heating circuit distributor and a method for controlling a secondary circuit with a heating circuit distributor.

[0002] In a district heating system, a heating circuit distributor is used to distribute heat to various consumer circuits on the secondary side. District heating networks consist of a primary circuit on the supplier side and a secondary circuit on the consumer side. The primary and secondary circuits are coupled in a transfer station for heat transfer, for example, via a heat exchanger.

[0003] In the primary and secondary circuits, a medium circulates to transport heat through a supply and a return line. A hot medium, comprising district heating, is delivered to the supply line of the primary circuit. At the heat exchanger of the district heating transfer station, the district heating can be fed into the supply line of the secondary circuit by raising the temperature of the secondary return line. After the heat from the secondary supply line is distributed to various consumer circuits in the building via a heating circuit distributor, the secondary return line has a correspondingly lower temperature.

[0004] When supplying district heating, the temperature of the primary return line plays a crucial role for the network operator. The lower the temperature of the primary return line, the more economical the operation of the district heating system. A low temperature in the primary return line is ensured when the energy provided in the secondary circuit is used efficiently, i.e., the return line of the secondary circuit has the lowest possible temperature.

[0005] Secondary-side heating circuit distributors are typically designed to distribute heat in the secondary circuit to various consumer circuits in parallel. A consumer circuit receives a hot medium from the secondary circuit's flow through a consumer circuit flow. The consumer extracts heat from the hot medium, causing it to cool. The cooled medium is then returned to the secondary circuit's return via a consumer circuit return. The temperature in the common return of the secondary circuit is thus the mixed temperature of the temperatures of the media discharged in parallel by the various heating circuits.

[0006] The disadvantage of a conventional heating circuit manifold is that different consumers extract different amounts of heat from the consumer circuit. This can, for example, lead to a relatively hot medium entering the return of the secondary circuit, which increases the mixed temperature of the return and thus reduces the amount of energy that the district heating supplier can feed into the secondary circuit. An increased mixed temperature reduces the operating efficiency for the district heating supplier.

[0007] DE 202 14 086 U1 and AT 10 457 U1 each show a secondary circuit according to the preamble of independent patent claim 1.

[0008] EP 2 636 958 A2 relates to a heating circuit manifold with an integrated hydraulic separator. A separator chamber is arranged in the housing of the heating circuit manifold between a flow chamber with a high heating medium temperature and a return chamber with a low heating medium temperature, as well as an intermediate chamber with a medium heating medium temperature.

[0009] Based on DE 202 14 086 U1, the object of the present invention is therefore to provide a secondary circuit with consumer circuits which ensures the most efficient distribution of the energy of the heat transfer medium to the consumer circuits and thereby achieves an even greater temperature difference between the secondary-side flow line and the secondary-side return line.

[0010] This object is achieved by the secondary circuit with a heating circuit distributor and the method for controlling a secondary circuit with a heating circuit distributor with the features of the respective claims.

[0011] Accordingly, a secondary circuit of a district heating system is provided with at least two consumer circuits and a heating circuit distributor for the hydraulic integration of at least two consumer circuits into the secondary circuit. The heating circuit distributor comprises, for each consumer circuit, a connection to a consumer circuit flow and a connection to a consumer circuit return. The secondary circuit comprises a flow and a return. The flow is the section of the secondary circuit in which heat can be provided for the at least two consumer circuits. The return is the section of the secondary circuit which follows the connection to the consumer circuit return of the last downstream consumer circuit. The connection to the consumer circuit return of at least one consumer circuit is arranged on the flow of the secondary circuit. A flow regulator is arranged in each consumer circuit flow.The flow controller can be a charging pump or a heating pump.

[0012] According to the invention, for each consumer circuit, a check valve is arranged in the supply line of the secondary circuit between the connection of the consumer circuit supply line and the connection of the consumer circuit return line. The check valve has a downstream flow direction and an upstream blocking direction. The check valve prevents the medium in the secondary-side supply line from flowing upstream between the consumer circuit return line and the consumer circuit supply line.

[0013] The secondary circuit according to the invention has the advantage that the heat from the flow in the secondary circuit can be used sequentially by at least two consumer circuits. By connecting the consumer circuit return of at least one consumer circuit to the flow of the secondary circuit, heat that was not used in the affected consumer circuit can be passed on to a second consumer circuit. In a conventional heating circuit manifold, remaining heat from one consumer circuit would be directed directly into the return of the secondary circuit. "Direct" means: without being conducted through a consumer. In contrast, in the heating circuit manifold according to the invention, the remaining heat can be fed to a downstream consumer circuit, so that the consumer circuit return of the downstream consumer circuit has a lower temperature than with a conventional connection.This allows a lower temperature to be achieved in the return flow of the secondary circuit than with a conventional heating circuit distributor, thus improving the economic efficiency of operating a district heating system for the supplier.

[0014] The inventive arrangement of the check valve prevents any possible incorrect circulation of the medium in the consumer circuit. An incorrect circulation would occur, for example, if the medium in the secondary-side supply line flows upstream between the consumer circuit return line and the consumer circuit supply line.

[0015] In an advantageous aspect of the invention, a supply setpoint temperature is assigned to the connection to the consumer circuit supply line of each consumer circuit. The at least two consumer circuits are connected downstream to the supply line of the secondary circuit in descending order of the assigned supply setpoint temperatures.

[0016] The advantage of this sorting of connections for consumer circuits in the secondary circuit is that downstream consumer circuits, even though they are heated by the cooled medium of an upstream consumer circuit, can still receive sufficient heat. This enables efficient heat distribution along a chain of consumer circuits in the secondary circuit.

[0017] It is particularly advantageous if the flow target temperatures of the consumer circuits differ significantly from one another. A significant difference exists, for example, if the flow target temperatures differ by at least 10 degrees. Typically, the flow target temperature varies within an adjustable interval. Therefore, a significant difference in the flow target temperatures also exists if the adjustable intervals of the flow target temperatures do not overlap.

[0018] Preferably, a boiler charging circuit can be connected to a first connection. A heating circuit can be connected to a second connection, and the second connection is positioned downstream of the first connection.

[0019] Further preferably, a high-temperature heating circuit, in particular a radiator circuit, can be connected to the second connection.

[0020] Alternatively, a low-temperature heating circuit, in particular an underfloor heating circuit, can be connected to the second connection.

[0021] In an advantageous embodiment of the invention, a low-temperature heating circuit, in particular an underfloor heating circuit, can be connected to a third connection. The third connection is positioned downstream of the second connection.

[0022] In another advantageous embodiment of the invention, a high-temperature heating circuit, in particular a radiator circuit, can be connected to a first connection. A low-temperature heating circuit, in particular an underfloor heating circuit, can be connected to a second connection.

[0023] Furthermore, a method for controlling a secondary circuit is provided. In a flow control step, the flow controller is controlled to serve the demands of the consumer in each consumer circuit. In a district heating control step, a primary-side valve is controlled to regulate a district heating supply.

[0024] The invention is described in more detail below with reference to exemplary embodiments and the drawings. The drawings show: Fig. 1 shows a diagram of a secondary circuit with a conventional heating circuit distributor; Fig. 2 shows a diagram of a secondary circuit according to an embodiment of the invention comprising a heating circuit distributor with two connected consumer circuits; Fig. 3 shows a diagram of a secondary circuit according to an embodiment of the invention comprising a heating circuit distributor with three connected consumer circuits.

[0025] Fig. 1 shows a diagram of a secondary circuit with a conventional heating circuit distributor.

[0026] In a conventional heating circuit manifold, consumer circuits are connected in parallel. This allows each consumer circuit to draw the hot medium from flow line 5 in the secondary circuit in parallel. This is especially true because the temperature in the various consumer circuit flows in a conventional heating circuit manifold is approximately the same. This also means that consumer circuits assigned a lower flow target temperature must draw an excessively hot medium from flow line 5 of the secondary circuit.

[0027] The connections 10 of the consumer circuit returns on a conventional heating circuit manifold are each located on the return 6 of the secondary circuit. This allows the cooled medium in the consumer circuit to flow directly into the return 6 of the secondary circuit. Depending on the consumer 4, the temperature of the cooled medium will be higher or lower. In the return 6 of the secondary circuit, the cooled media from the various consumer circuits mix, resulting in a mixed temperature of the medium in the return 6 of the secondary circuit. Depending on the heat requirements of the consumer 4, the mixed temperature in the return of the secondary circuit can fluctuate considerably.

[0028] Fig. 2 shows a diagram of a secondary circuit according to an embodiment of the invention comprising a heating circuit distributor with connections for two consumer circuits.

[0029] The heating circuit distributor 11 comprises for each consumer circuit a connection 9 to a consumer circuit flow and a connection 10 to a consumer circuit return. Fig. 1 The secondary circuit shown has a flow 5 and a return 6. The flow is the section of the secondary circuit in which heat can be provided for the connected consumer circuits. The flow is therefore the pipe section of the secondary circuit that extends from the district heating transfer station to the last downstream connection 10 of a consumer circuit return. The return 6 of the secondary circuit is accordingly the section that follows the connection 10 of the consumer circuit return of the last downstream consumer circuit. Thus, the consumer circuit return of the last downstream consumer circuit is connected to the return 6 of the secondary circuit.

[0030] According to the invention, the consumer circuit return of the downstream first consumer circuit is Fig. 2 to the flow 5 of the secondary circuit. For this purpose, a connection 10 to the consumer circuit return is arranged in the heating circuit distributor 11 on the flow 5 of the secondary circuit.

[0031] It is therefore intended to direct any heat remaining in the consumer circuit return of the first consumer circuit directly into connection 9 on the consumer circuit flow of the second, downstream consumer circuit. For this purpose, the heating circuit distributor 11 provides connections 9; 10 on the flow 5 of the secondary circuit in order to connect both the consumer circuit return of the downstream first consumer circuit and the consumer circuit flow of the second, downstream consumer circuit directly to the flow 5 of the secondary circuit. The circulation of the heat-providing medium in a consumer circuit is controlled by a flow controller 2. The flow controller 2 can, for example, be a charging pump for a boiler or a heating pump in a heating circuit. The flow controller 2 is arranged in the consumer circuit flow.When flow controller 2 is activated, a hot medium circulates from the consumer circuit flow through consumer 4 into the consumer circuit return. Consumer 4 extracts heat from the hot medium, so that the medium in the consumer circuit return has a correspondingly lower temperature than in the consumer circuit flow.

[0032] According to the invention, a check valve 1 is arranged in the supply line 5 of the secondary circuit between the connection 9 of the consumer circuit supply line and the connection 10 of the consumer circuit return line. The check valve 1 has a downstream flow direction and an upstream blocking direction. The check valve 1 thus ensures that no incorrectly directed circulation occurs in the consumer circuit.

[0033] The design of the heating circuit distributor of the Fig. 2 has connections 9 and 10 for two consumer circuits. A set flow temperature is assigned to connection 9 on the consumer circuit flow of each consumer circuit. The set flow temperature depends heavily on the specific design of the consumer circuit and varies with the heat demand of consumer 4.

[0034] According to one aspect of the invention, the two consumer circuits are connected downstream to the flow 5 of the secondary circuit in descending order of the assigned flow target temperatures. This ensures that connection 9 to a consumer circuit flow with the highest flow target temperature is served first. Connection 9 to the second, downstream consumer circuit flow with a lower flow target temperature can be at least partially supplied with remaining heat from connection 10 of the consumer circuit return of the first consumer circuit. Sorting connections 9 of the consumer circuit flows in descending order of the assigned flow target temperatures ensures that the heat requirement of the second, downstream connection does not exceed the heat requirement of the first connection.Ideally, the temperature of the medium in connection 10 of the first consumer circuit return is greater than the flow target temperature of the second connection 9. The flow target temperatures and the corresponding temperatures in the consumer circuit return depend on the selection of consumer 4.

[0035] According to one aspect of the invention, at the first terminal of the Fig. 1 A boiler charging circuit is connected to the heating circuit distributor shown, and a heating circuit is connected to a second connection. Typically, during hot water preparation or boiler charging, an elevated temperature of approximately 65 degrees Celsius occurs in the boiler charging circuit return. The inventor noticed that the temperature of the boiler charging circuit return is systematically higher than the target flow temperature of a heating circuit. A high-temperature heating circuit, such as for radiators, requires a target flow temperature of 60 degrees Celsius. A low-temperature heating circuit, such as for underfloor heating, on the other hand, requires a target flow temperature of, for example, only 38 degrees Celsius.While a boiler charging circuit disadvantageously heats the return of the secondary circuit during boiler charging in a conventional heating circuit manifold, the remaining heat from the boiler charging circuit return can be supplied to the downstream heating circuit using the heating circuit manifold 11 according to the invention when boiler charging is activated. This allows additional heat to be extracted from the medium in the heating circuit, so that the temperature in the return 6 of the secondary circuit can be significantly reduced compared to a conventional heating circuit manifold.

[0036] The heating circuit distributor 11 according to the invention is not only as in Fig. 2 The heating circuit distributor shown is not limited to connections for two consumer circuits, but can also have connections to more than two consumer circuits. Either all or only some of the consumer circuits can be connected as inventively. A heating circuit distributor with connections to consumer circuits according to the invention in combination with conventional parallel connections to other consumer circuits is also possible.

[0037] Fig. 3 shows a diagram of a secondary circuit according to an embodiment of the invention comprising a heating circuit distributor with three connections to consumer circuits.

[0038] In the embodiment of the heating circuit distributor 11 according to the invention of Fig. 3 Connections are therefore provided for three consumer circuits. Connections 10 to the consumer circuit return of the first two downstream consumer circuits are located on the secondary circuit supply line 5. Connection 10 of the last downstream consumer circuit return connects this consumer circuit return to the secondary circuit return line 6.

[0039] The first downstream consumer circuit can be, for example, a boiler charging circuit. The second and third downstream consumer circuits can each be a heating circuit. It is advantageous if the second downstream consumer circuit is a high-temperature heating circuit and the third and thus last consumer circuit is a low-temperature heating circuit. The return of the secondary circuit in the embodiment of the heating circuit distributor according to the invention of the Fig. 3has a considerably lower temperature than the mixing temperature that occurs in a return 6 of a secondary circuit with a conventional heating circuit distributor.

[0040] The secondary circuit according to the invention with a heating circuit distributor is controlled using a method according to which, in a flow control step, the flow controller 2 is controlled to serve the demands of the consumer 4 of each consumer circuit, and in a district heating control step, a primary-side valve is controlled to regulate a district heating supply. Based on the demands of the consumer 4 of each consumer circuit, a target flow temperature is assigned to the connections to the consumer circuit flow 9. List of reference symbols:

[0041] 1 Check valve 2 Flow regulator 3 Heating mixer 4 Consumer 5 Secondary circuit flow 6 Secondary circuit return 7 Primary circuit flow 8 Primary circuit return 9 Connection to consumer circuit flow 10 Connection to consumer circuit return 11 Heating circuit distributor 12 Flow direction

Claims

1. Secondary circuit of a district heating system comprising at least two consumer circuits and a heating circuit distributor (11) for the hydraulic integration of the at least two consumer circuits into the secondary circuit, wherein, for each consumer circuit, the heating circuit distributor (11) comprises a connection (9) to a consumer circuit supply line and a connection (10) to a consumer circuit return line, wherein the secondary circuit comprises a supply line (5) and a return line (6), wherein the supply line (5) is the portion of the secondary circuit in which heat can be provided for the at least two consumer circuits, and the return line (6) is the portion of the secondary circuit which follows the connection (10) of the consumer circuit return line of the last downstream consumer circuit, wherein the connection (10) to the consumer circuit return line of at least one consumer circuit is arranged on the supply line (5) of the secondary circuit, wherein a flow regulator (2) is arranged in each consumer circuit supply line, and wherein the flow regulator (2) is a loading pump or a heating pump, characterized in that, for each consumer circuit, a check valve (1) is arranged in the supply line (5) of the secondary circuit between the connection (9) of the consumer circuit supply line and the connection (10) of the consumer circuit return line, wherein the check valve (1) has a downstream flow-conducting direction and an upstream blocking direction, wherein the check valve prevents the medium in the secondary-side supply line from flowing upstream between the consumer circuit return line and the consumer circuit supply line.

2. Secondary circuit according to claim 1, wherein the connection (9) to the consumer circuit supply line of each consumer circuit is assigned a supply line target temperature, wherein the at least two consumer circuits are connected to the supply line (5) of the secondary circuit, downstream and in descending order of the assigned supply line target temperatures.

3. Secondary circuit according to claim 1 or 2, wherein a boiler loading circuit can be connected to a first connection of the heating circuit distributor, a heating circuit can be connected to a second connection of the heating circuit distributor, and the second connection is arranged downstream of the first connection.

4. Secondary circuit according to the preceding claim, wherein a high-temperature heating circuit, in particular a radiator circuit, can be connected to the second connection.

5. Secondary circuit according to claim 3, wherein a low-temperature heating circuit, in particular an underfloor heating circuit, can be connected to the second connection.

6. Secondary circuit according to claim 4 or 5, wherein a low-temperature heating circuit, in particular an underfloor heating circuit, can be connected to a third connection of the heating circuit distributor, wherein the third connection is arranged downstream of the second connection.

7. Secondary circuit according to claim 1 or 2, wherein a high-temperature heating circuit, in particular a radiator circuit, can be connected to a first connection, and a low-temperature heating circuit, in particular an underfloor heating circuit, can be connected to a second connection.

8. Method for regulating a secondary circuit according to claim 1, wherein, in a flow regulation step, the flow regulator (2) is controlled in order to serve the consumer demands of each consumer circuit, and, in a district-heating regulation step, a primary-side valve is controlled in order to regulate a district heating supply.