DE102013110078B4 - heating system - Google Patents

Abstract

Method for operating a heating system with a boiler (1) and a buffer storage tank (2), in which heat transfer medium is supplied to a consumer (3, 13) and is fed back via a return line (16) to a boiler return connection (1b) of the boiler (1) or a lower connection (2b) of a buffer tank (2), the consumer (3, 13) being connected via a mixing valve (4 , 14) that is supplied with either a mixture of heat transfer medium from the boiler flow connection (1a) and the return line (16) or a mixture of heat transfer medium from the upper connection (2a) of a buffer tank (2) and from the return line (16) to the consumer ( 3, 13), whereby if a target consumer temperature is below a buffer tank temperature at the upper connection (2a) of the buffer tank (2), the boiler (1) is switched off and the connection is closed via the mixing valve (4, 14). to the boiler flow connection (1a) is prevented and the target consumer temperature is regulated by mixing hot heat transfer medium from the upper connection (2a) of the buffer tank (2) and cold heat transfer medium from the return line (16) to the consumer (3, 13), and When a target consumer temperature is above a buffer tank temperature at the upper connection (2a) of the buffer tank (2), the boiler (1) is switched on and the connection to the boiler flow connection (1a) is opened via the mixing valve (4, 14). and the target consumer temperature is regulated by mixing hot heat transfer medium from the boiler flow connection (1a) and a cold heat transfer medium from the return line (16) to the consumer (3, 13).

Description

The invention relates to a method for operating a heating system with a boiler and a buffer storage tank, in which heat transfer medium is supplied to a consumer either from a boiler flow connection of a heating boiler or from an upper connection of a buffer storage tank and via a return line to a boiler return flow connection of the heating boiler or a lower connection of a buffer storage tank is returned.

Heating systems are increasingly being equipped with buffer storage. This is necessary for wood solid fuel boilers due to the system, but also enables the integration of alternative energy sources such as solar energy with other types of fuel or makes it easier to heat domestic water.

The advantages of charging the buffer storage tank through the boiler are that the energy available in the buffer storage tank can be better utilized, even if, for example, the temperature level is not sufficient to prepare service water or to operate the heating system. In this way it is possible to raise the temperature level in the buffer tank to the required level. The disadvantage of such a system is that the heating buffer storage is always subject to losses. During the heating period, these losses are primarily offset by the boiler. This increases the fuel requirement and reduces the system efficiency accordingly. In addition, the solar yield can be reduced because the volume that is heated by the automatic boiler is no longer available to the solar system.

From the AT 006 833 U1 a method for operating a heating system with a buffer tank is known, in which a mixing valve is used to control the temperature distribution and in particular to avoid harmful condensation phenomena in the boiler. However, the disadvantages described above cannot be significantly reduced in this way.

The DE 102 16 749 A1 discloses a four-way valve used to achieve different operating conditions in a combined heating and cooling system.

Out of DE 203 05 438 U1 a heating system is known in which a mixing valve is connected to a consumer and to a buffer storage tank.

Another known solution is in the WO 2003/010 468 A2 described in which different heat sources can be used to feed a consumer. However, it is not possible to implement stepless switching processes in a simple manner.

The object of the present invention is to specify a method and a heating boiler so that the above disadvantages are avoided and energy losses are largely minimized.

The essential aspect of the present invention is that the consumer is optionally supplied via the mixing valve via a first heating rail or a third heating rail. The line network between the boiler flow and the mixing valve is referred to as the first heat rail, while the line network between the upper connection of the buffer tank and the mixing valve is referred to as the third heat rail. In addition to this, a line network is provided as a second heating rail, which is arranged between the boiler return connection, the lower connection of the buffer tank and the consumer return connection and also has a connection to the mixing valve. The mixing valve can therefore not only provide the appropriate target temperature for the consumer in a manner known per se, by adding a variable proportion of cold heat transfer medium from the second heating rail, but also regulate the various operating modes depending on the heat supply in the buffer storage tank.

According to the invention, these objects are achieved by a method having the features of claim 1. The consumer is supplied via a mixing valve which supplies either a mixture of heat transfer medium from the boiler flow connection and the return line or a mixture of heat transfer medium from the upper connection of a storage tank and the return line to the consumer.

An important aspect of the invention is that the heating operation via the boiler can be largely decoupled from the storage tank, so that it is possible, for example, if there is a lack of solar energy, to thermally completely empty the storage tank. It is preferred if the mixing valve interrupts either the connection to the boiler flow connection of the boiler or to the upper connection of the buffer storage tank in every operating state. In this way, complete decoupling can be achieved.

Preferably, the mixing valve is also fed with heat transfer medium via a consumer return connection. As stated above As a result, the functionality of the temperature control at the consumer can also be taken over by the mixing valve.

According to the invention, the method is operated in such a way that when a target consumer temperature is below a buffer storage tank temperature at the upper connection of the buffer storage tank, the boiler is switched off and the connection to the boiler flow connection is prevented via the mixing valve and the consumer target temperature is increased by mixing hot Heat transfer medium from the top connection of the buffer tank and cold heat transfer medium from the consumer return connection.

On the other hand, the process is operated in such a way that when a target consumer temperature is above a buffer storage tank temperature at the upper connection of the buffer storage tank, the boiler is switched on and the connection to the boiler flow connection is opened via the mixing valve and the consumer target temperature is increased by mixing hot Heat transfer medium from the boiler flow connection and a cold heat transfer medium from the return line to the consumer is controlled.

In this way, the respective operating situations can be taken into account in an efficient manner.

A particular advantage of the present method is that it is possible to optimally supply different consumers. For example, underfloor or ceiling heating circuits and radiator heating circuits and, if necessary, external heat exchangers for domestic hot water preparation can be supplied with the optimal temperature level required for them without impairing the overall efficiency of the system. According to the invention, this is achieved in that the individual consumers are each assigned their own mixing valve.

A particularly favorable embodiment of the method according to the invention is given when heat transfer medium is selectively conveyed from the boiler flow connection to the upper connection of the buffer tank via a run-on extension section. The after-run extension section is used to enable the buffer storage tank to be charged by the boiler in a targeted manner in order to achieve optimum operation here, if efficient operation of the boiler is not possible with low heat requirements and there is a risk of it being switched on and off too frequently, then an improvement in the system efficiency can be achieved in this way by using the buffer storage.

Furthermore, the present invention relates to a heating system for supplying at least one consumer, with a heating boiler, which has a boiler flow connection and a boiler return connection, and with a buffer storage tank, which has an upper connection and a lower connection, the boiler flow connection of the heating boiler being connected to a mixing valve which is in connection with a consumer and further in connection both with the upper connection of the buffer tank and with a return line which connects the lower connection of the buffer tank, the boiler return connection and a consumer, wherein the mixing valve is designed so that the Consumer connection is in a variable relationship with a further connection and with the return connection in connection, wherein the further connection is either the boiler connection or the buffer connection. According to the invention it is provided that an after-run extension section is provided between the heating boiler flow connection and the upper connection of the buffer tank, and that an after-run pump is provided in the after-run extension section.

In particular, the mixing valve is optionally designed to admix a variable flow rate of the heat transfer medium from the return line to a flow rate supplied to the consumer. The mixing valve is also preferably designed to selectively interrupt the connection to the boiler flow connection or to the upper connection of the buffer tank.

It is provided that the mixing valve has a consumer connection, a boiler connection, a buffer connection and a return connection, with the consumer connection being connected in a variable ratio to a further connection and to the return connection, with the further connection being either the boiler connection or the buffer connection . The variable ratio is set by appropriate cross-sectional ratios, as is generally the case in mixing valves. The mixing valve can be designed as an actual valve, ie a seat valve, as a tap, as a slide, as a piston-cylinder arrangement or as a component made up of several components.

• 1 ein Schaltungsdiagramm einer ersten Ausführungsvariante der Erfindung; und
• 2 ein Schaltungsdiagramm einer alternativen Ausführungsvariante der Erfindung.

The present invention is explained in more detail below with reference to the exemplary embodiments illustrated in the figures. Show it:

• 1 a circuit diagram of a first embodiment of the invention; and
• 2 a circuit diagram of an alternative embodiment of the invention.

In the embodiment 1, a heating system with a boiler 1, a buffer tank 2, a first consumer 3, a second consumer 13, a first mixing valve 4 and a second mixing valve 14 is shown. During operation, the boiler 1 makes hot heat transfer medium available at a boiler flow connection 1a. This heat transfer medium is fed to the mixing valves 4, 14 via the first heat rail L1 and fed to a boiler connection 4b or 14b. The mixing valves 4, 14 make this heat transfer medium available either at consumer connections 4a or 14a, which are connected to consumer lines L4 or L14, in each of which a heating pump 5 or 15 is provided to supply the consumers 3, 13 with hot heat transfer medium . From consumers 3, 13, the heat transfer medium flows further into a return system with return lines 16, which is referred to here as the second heat rail L2. Depending on the hydraulic conditions, this second heat pipe L2 leads the heat transfer medium to a boiler return connection 1b or to a lower connection 2b of the buffer tank 2. In addition, the second heat pipe L2 is also connected to a return connection 4d or 14d of the mixing valves 4, 14.

A third heat rail L3 connects a buffer connection 4c, 14c of the mixing valves 4, 14 to an upper connection 2a of the buffer tank 2.

The heating system of 2 largely corresponds to that of 1 with the difference that an additional run-on extension section L3a branches off at the boiler flow connection 1a, which is part of the third heating rail L3. In this after-run extension section 3a, which thus produces a direct connection between the boiler flow connection 1a and the upper connection 2a of the buffer memory 2, a follow-up pump 6 is provided.

The operation of the heating system according to the invention is explained below.

Basically, a distinction must be made between an operating state in which the temperature in the buffer store 2 is sufficient to supply a consumer 3, 13 and an operating state in which this is not the case. As a further consequence, a distinction must be made between high heat demand and low heat demand.

Individual operating states for a consumer 3, 13 are now explained by way of example based on the different boundary conditions. It should be noted that due to the special design of the invention, different consumers 3, 13 can have different operating states.

In the following examples, without loss of generality, a heating boiler 1 with an output of 15 kW is assumed, which can be modulated up to a partial load of 30%.

a.) Buffer tank loaded, large heat requirement at the consumer

It is assumed that consumer 3 is to be provided with a heat transfer medium with a target temperature of 60°C. In the buffer tank 2 there is a heat transfer medium with a temperature of 80° C. in the area of the upper connection 2a. The temperature in the return system (second heat rail L2) is 40°C.

In order to meet the heat requirement of 120 kW, for example, for consumer 3, a flow rate of around 516 l/h must be routed to consumer 3 if the heat transfer medium has a heat capacity of 1.162 kWh/kgK. This flow rate of 516 l/h at a temperature of 60°C is provided in the mixing valve by mixing a flow rate of 258 l/h at 80°C via the third heat rail L3 and a flow rate of 258 l/h via the second heat rail L2 becomes. In this case, the heating boiler 1 is completely decoupled from the hydraulic system and is not in operation.

b.) Buffer tank loaded, low heat requirement at the consumer

The temperature levels here are analogous to example a. above), it is only assumed that consumer 3 has a heat requirement of 5 kW. This is supplied via a flow rate of 215 l/h in the consumer line L4, half of which is provided from the third heating rail L3 and half from the second heating rail L2.

c.) Buffer discharged, high heat requirement at consumer

It is assumed here that the temperature of the heating medium in buffer storage tank 2 is consistently 40°C. This means that the target temperature at consumer 3 cannot be reached by buffer storage 2. In this case, the heating boiler 1 supplies heat transfer medium at a temperature of 80° C. to the first heat rail L1, specifically with it a flow rate of 258 l/h. A further volume flow of 258 l/h from the second heating rail L2 at a temperature of 40°C is added in the mixing valve 4, so that the consumer 3 is provided with a volume flow of 516 l/h at a temperature of 60°C.

d.) Buffer discharged, low heat requirement at the consumer

Here, too, the temperature levels are analogous to example c.) above. A mass flow of 215 l/h is only made available to the consumer 3, half of which in turn is made up of a heat flow from the first heat rail L1 and half from the second heat rail L2.

In the case of an automatic boiler, the boiler temperature, which represents the reference variable for the modulation, is lowered to 60°C and the volume flow is increased accordingly by controlling the mixing valve.

e.) Different heating circuits with different temperature requirements

Examples c.) and d.) above can be varied insofar as, in addition to consumer 3 with a target temperature of 60.degree. C., there is another consumer 13, for example an underfloor heating circuit, with a target temperature of 35.degree. In this case, the first consumer 3 is served by the boiler 1 as in examples c.) and d.), while the second consumer 13 is supplied by the buffer tank 2 in examples a.) and b.).

f.) Operation according to FIG. 2 with runtime extension

In order to be able to operate the heating boiler 1 independently of the current heat requirement at an optimal operating point and to avoid frequent switching on and off of the boiler when the heat requirement is low, an after-run extension can be provided, as is shown in 2 is shown. The excess heat from the boiler is used to charge the buffer tank 2 via the boiler 1, in which case the run-on pump 6 is switched on, which feeds hot heat transfer medium from the boiler flow connection 1a into the third heat rail L3. As a result, the buffer tank 2 flows from top to bottom and is “loaded” with hot heat transfer medium.

The present invention makes it possible to represent different operating states of heating systems in an energy-efficient manner with simple means and to use energy optimally.

Claims (12)

Method for operating a heating system with a boiler (1) and a buffer storage tank (2), in which heat transfer medium is supplied to a consumer (3, 13) and is fed back via a return line (16) to a boiler return connection (1b) of the boiler (1) or a lower connection (2b) of a buffer tank (2), the consumer (3, 13) being connected via a mixing valve (4 , 14) that is supplied with either a mixture of heat transfer medium from the boiler flow connection (1a) and the return line (16) or a mixture of heat transfer medium from the upper connection (2a) of a buffer tank (2) and from the return line (16) to the consumer ( 3, 13), whereby if a target consumer temperature is below a buffer tank temperature at the upper connection (2a) of the buffer tank (2), the boiler (1) is switched off and the connection is closed via the mixing valve (4, 14). to the boiler flow connection (1a) is prevented and the target consumer temperature is regulated by mixing hot heat transfer medium from the upper connection (2a) of the buffer tank (2) and cold heat transfer medium from the return line (16) to the consumer (3, 13), and When a target consumer temperature is above a buffer tank temperature at the upper connection (2a) of the buffer tank (2), the boiler (1) is switched on and the connection to the boiler flow connection (1a) is opened via the mixing valve (4, 14). and the target consumer temperature is regulated by mixing hot heat transfer medium from the boiler flow connection (1a) and a cold heat transfer medium from the return line (16) to the consumer (3, 13). procedure after claim 1 , characterized in that the mixing valve (4, 14) interrupts either the connection to the boiler flow connection (1a) of the boiler (1) or to the upper connection (2a) of the buffer tank (2) in any operating state. Procedure according to one of Claims 1 or 2 , characterized in that a first consumer (3) and at least one further consumer (13) are supplied by a first mixing valve (4) and at least one further mixing valve (14). Procedure according to one of Claims 1 until 3 , characterized in that the heat transfer medium through a between the mixing valve (4, 14) and the consumer (3, 13) arranged heating pump (5, 15) is promoted. Procedure according to one of Claims 1 until 4 , characterized in that a follow-up extension section (L3a) selectively heat transfer medium from the boiler flow connection (1a) to the upper connection (2a) of the buffer tank (2) is promoted. Heating system for supplying at least one consumer (3, 13), with a boiler (1) which has a boiler flow connection (1a) and a boiler return connection (1b), and with a buffer tank (2) which has an upper connection (2a) and has a lower connection (2b), the boiler flow connection (1a) of the boiler (1) being connected to a mixing valve (4, 14) which is connected to a consumer (3, 13), the mixing valve (4, 14 ) is also connected both to the upper connection (2a) of the storage tank (2) and to a return line (16) which connects the lower connection (2b) of the storage tank (2), the boiler return connection (1b) and a consumer (3 , 13) to one another, with the mixing valve (4, 14) being designed such that a consumer port (4a, 14a) is connected in a variable ratio to a further port and to a return port (4d, 14d), the further Connection is either a boiler connection (4b, 14b) or a buffer connection (4c, 14c), with a run-on extension section (L3a) being provided between the boiler flow connection (1a) and the upper connection (2a) of the buffer tank (2), and in the run-on extension section (L3a) an after-running pump (6) is provided. heating system after claim 6 , characterized in that the mixing valve (4, 14) is designed to admix a variable flow rate of the heat transfer medium from the return line (16) to a consumer (3, 13) supplied flow rate of the heat transfer medium. heating system after claim 6 or 7 , characterized in that the mixing valve (4, 14) is designed to selectively interrupt the connection to the boiler flow connection (1a) or to the upper connection (2a) of the buffer tank (2). Heating system according to one of Claims 6 until 8th , characterized in that a heating pump (5, 15) between the mixing valve (4, 14) and the consumer (3, 13) is arranged. Heating system according to one of Claims 6 until 9 , characterized in that the after-run extension section (L3a) is a direct hydraulic connection between the boiler flow connection (1a) and the upper connection (2a) of the buffer tank (2). Heating system according to one of Claims 6 until 10 , characterized in that a first consumer (3) is connected to a first mixing valve (4) and at least one further consumer (13) is connected to at least one further mixing valve (14). heating system after claim 11 , characterized in that when the boiler connection (4b, 14b) is connected to the consumer connection (4a, 14a), the buffer connection (4c, 14c) is interrupted and that when the buffer connection is connected to the consumer connection (4a, 14a), the (4c, 14c ) Boiler connection (4b, 14b) is interrupted.

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