EP1447626A1 - Multi-layered storage tank with return flow temperature control - Google Patents

Abstract

The hot water storage tank (6) has a cold water inlet (12), a hot water outlet (13) and a lower cold water outlet (4) with a circulating pump (7). The circuit also has a heat exchanger (9) to which a hot water pipe (5) in the upper area of the tank opens. The heat exchanger has a heating circuit (H) with a heater (10), pump (8) and in and return pipes (11,14). The return connection is controlled dependent on the storage tank temperature.

Description

The invention relates to a hot water tank according to the preamble of the claim 1 and a method for storing hot water in a storage according to the preambles of claims 13 to 15.

Hot water storage tanks currently available on the market, in particular stratified storage tanks, are built relatively complex, especially for regulating a hot water temperature (Storage tank charging temperature) at least two sensors in the storage tank and two more are arranged in an associated heating circuit via which such stratified storage are usually supplied with energy. As an energy source for the heating circuit gas or oil burners and solar modules are usually used. For calmed flow Water supply and drainage to and from the stratified storage constructively complex measures are suggested, but leave anyway turbulence or false currents cannot be avoided with standard devices, that destroy the stratification of the storage, especially under load.

Since the storage tank charging temperature at the hot water outlet on the hot water outlet Plate heat exchanger of the desired or set hot water temperature Known systems must use a temperature sensor at the hot water outlet of the plate heat exchanger. With this the storage tank charging temperature recorded and regulated. At least one other temperature sensor is in the stratified storage necessary to register a drop in the storage temperature and one Initiate reloading. There is at least one in the heating circuit for common heat generators Flow temperature sensor, but usually also a return temperature sensor.

Currently, they are primarily suitable for use in single and two-family houses Layer storage modules are known, which can be combined with condensing heaters. The problem with all these devices, however, is the temperature-accurate provision of process water. One reason for this is that there Stratification storage loading and unloading devices the stratification of the already in the Layered warmed hot water contained destroy and thus a temperature-precise stratification or maintenance of the stratification almost impossible is. On the other hand, the temperature control is optimized to achieve Storage tank charging temperature of the domestic water is only very complex for devices there, i.e. only possible with the help of complex temperature sensors.

The invention is therefore based on the object, avoiding the above disadvantages Hot water storage and a temperature control for the same are available to provide, which is simple and inexpensive to set up and suitable, quickly to changes in temperature to react in the stratified storage and a desired temperature to provide the process water.

This object is achieved by a hot water tank according to claim 1 and solved by a method according to claims 13 to 15.

In particular, the task is solved by a hot water storage tank, in particular stratified storage tanks, with a cold water inlet, a process water extraction line and a cold water outlet leading away from the lower area thereof, in the course of which a circulation pump is arranged and which leads to a heat exchanger, from which a hot water line leads to the upper one region joins the stratified storage, wherein the heat exchanger is associated with a heating circuit (H) with heating device, a heating circuit pump and a supply and return line, and wherein a predetermined desired temperature (T _soll) of the stratified storage the set point for the return temperature (T _RL) of the heating circuit ( H) determined.

Here, it was recognized according to the invention that taking into account predeterminable volume flows the amount of circulating water in the hot water circuit and in the heating circuit the primary side Heating return temperature of the heat exchanger is approximately the same as the hot water outlet temperature in the secondary circuit, i.e. corresponds to the process water circuit. by virtue of it is this correlation of the return temperature and the hot water temperature thus possible in the heat generator according to the invention only one return temperature sensor to use; further temperature sensors, as required in the prior art, are therefore no longer necessary according to the invention. Because of the use of a stratified storage device according to the invention, in which, as described below, this prevents a disturbance of the stratification within the reservoir is that the inlet of which opens into the upper region of the stratified storage Hot water pipe and / or the inlet from the lower area of the stratified storage tank leading cold water drain an upper and a lower water guide and distribution device are assigned, thus corresponds to the hot water inlet temperature in the stratified storage tank the hot water outlet temperature from the stratified storage tank. These two temperatures correlate with the return temperature and are in accordance with a preferred embodiment identical to this or at least approximately identical.

According to the invention, it is provided that the heat exchanger can be operated in cocurrent or, in particular in countercurrent, and is designed so that the heating circuit-side return temperature (T _RL ) corresponds approximately to the hot water temperature (T _WW ) in the hot water line between the heat exchanger and stratified storage tank.

It is preferred if the circulating volume flows in the heating circuit and the domestic water circuit are designed such that an average temperature difference dT _WT of approximately -50 K is achieved across the heat exchanger.

It is further preferred that the average temperature difference dT _{WT can be varied} by a power rating on the circulation pump and / or the heating circuit pump. This means that the full device performance can be used for reloading the store, particularly at low store temperatures.

The circulating volume flow in the process water circuit is preferably between approximately 200 l / h to 1000 l / h, in particular 400 l / h to 800 l / h and the circulating volume flow in the heating water circuit between about 400 l / h to 1400 l / h, especially 600 l / h up to 1200 I / h. This relationship offers a good approximation that the heating circuit return temperature of the heat exchanger approximately the hot water temperature in the process water circuit. Of course, instead of in the heating circuit of water also another heat-emitting medium with a comparable heat capacity be used. When using a medium with a lower heat capacity the volume flow would have to be increased accordingly and vice versa.

A further advantage is that if a predetermined switch-on temperature _difference dT _{Eln is exceeded} between the measured storage _temperature T _SP and / or return _temperature T _RL and the predetermined storage _target temperature T _Soll, a charging process can be triggered in which the circulation pump and / or the heater are switched on or over ,

Accordingly, if the measured storage tank temperature T _SP falls by 10 K below the storage tank _target temperature T _Soll , the temperature sensor in the stratified storage tank requests heat. The storage tank charging pump and burner are then switched on and the return temperature T _{RL of} the plate heat exchanger is regulated to the storage tank temperature T _Soll . Cold drinking water is sucked in or supplied from the bottom area of the stratified storage tank or, at the same time, tapped via the cold water inlet, heated in the plate heat exchanger to the set tank temperature T _setpoint and stratified via the hot water line between the heat exchanger and stratified storage tank. The stratified storage tank is thereby heated from the top down to the storage tank _set temperature T _set .

The switch-on temperature difference dT _On is preferably the difference between the actual storage temperature minus the desired storage temperature in the range between -0.5 K and -15 K, preferably in the range between -1 K and -12 K and particularly preferably in the range between -2 K and -10 K. With the adjustable control hysteresis, the runtime or service life of the burner can be increased at a maximum switch-on temperature difference dT _On of -10 K. With a small hysteresis of -2 K, convenience is gained by immediately reloading the memory.

Another advantage of the invention is that when the temperature falls below a predetermined switch-off temperature difference dT _Aus between the measured storage temperature T _SP and / or return temperature T _RL and the predetermined storage _target temperature T _Soll, the charging process can be canceled and the circulation pump and / or the heater can be switched off or on can be switched. When the hot domestic or drinking water stratified from above reaches a temperature sensor in the lower area of the stratified storage tank with a predetermined temperature, the storage tank charging is terminated. The switch-off point is below the _{set cylinder} temperature T _Soll , in order to guarantee a safe switch-off even with tolerances of the hot water temperature (cylinder charging temperature). The circulation pump and / or the heater are switched off or switched over from a running operating state.

The switch-off temperature difference dT _Aus , that is to say the difference between the actual storage temperature and the desired storage temperature, is preferably in the range between -0.5 K and -15 K, preferably in the range between -1 K and -12 K, and particularly preferably in the range between -2 K and -10 K, especially at -5 K.

It is preferred if the temperature sensor is arranged approximately at the level of the mouth of the cold water drain in the lower region of the stratified storage tank. The positioning of the temperature sensor for measuring the storage tank temperature T _SP is particularly important for the performance data of the hot water storage tank. A quick response when drawing off hot water is ensured by positioning the temperature sensor near the bottom of the stratified storage tank at approximately the level of the mouth of the cold water drain. By means of rapid reactions during reloading which are possible according to the invention, maximum performance indicators of the hot water storage tank are achieved, so that with a storage water content of, for example, 90 liters, a performance level is achieved that is achieved by a conventional storage tank with a content of 160 to 200 liters.

The temperature sensor is preferably arranged between 1 cm and 12 cm, and particularly preferably between 2.5 cm and 4 cm, above the floor level of the stratified storage tank. The temperature level, which drops from top to bottom, is thus completely recorded and rapid storage charging is ensured if the switch-on temperature difference dT _{On is} undershot.

According to the invention, the hot water tank, in particular stratified tanks, has upper area of the stratified storage tank opens into the stratified storage tank Hot water pipe and a cold water drain in the lower area of the stratified storage tank with an upper or a lower water pipe and distribution device are assigned.

An essential point is that by means of the water supply and distribution device Disturbances in the temperature profile in the bottom and top area of the stratified storage tank of the water contained in the stratified storage is reduced to a minimum can be. Advantageously, in the store loading mode, i.e. when feeding of hot water, a temperature-precise stratification of the hot water from guaranteed top down. In addition, it is ensured that the Discharge of cold water has no effect on the main volume of the stratified storage tank Flow showing the temperature stratification within the stratified storage would disturb, is caused. In addition, using the invention Water supply and distribution device ensures that heating from the cold Condition triggers no noticeable temperature fluctuations during the tap, so that withdrawn drinking or industrial water up to high tap volumes of, for example 15 l / min to 25 l / min essentially always has the same temperature.

It should be emphasized that the water supply and distribution device according to the invention both in Bottom as well as in the lid area of the stratified storage tank individually or in combination with each other, depending on the desired and / or predetermined geometry of the layered storage are provided.

According to one embodiment, the upper water guiding and distributing device has a about horizontally extending, acting as a baffle plate on which Hot water to be stored is directed so that there is upstream of the distribution plate forms a substantially horizontal flow. In a preferred way This ensures that what is to be stored and flows into the stratified storage Hot water does not flow in a jet into the main volume of the stratified storage tank and a mixing of the layers and a concomitant Disruption of the temperature stratification of that already contained in the stratified storage Water leads.

The inflowing hot water becomes above the baffle plate deflected the level of the distribution plate so that it was essentially horizontal flows and forms an essentially annular flow above the distribution plate, which only gradually spreads towards cold water and the latter practically sieves downwards, but without causing any mixing with the cold water.

It is advantageous if the control and distribution system according to the invention has a relative large dimensioning of the distribution plate provides for an optimized flow guidance to ensure.

According to one embodiment of the invention, one is a wall of the stratified storage angled end of the distribution plate in the direction of an inflow side, that a flow acting in the direction of the inflow side is formed there.

In this way it is ensured that a uniform homogeneous on the distribution plate Flow in an essentially horizontal plane with a small proportion upwards arises. Currents flowing into the stratified storage are thus the water guiding and distribution device according to the invention deflected in an advantageous manner, that this is limited to the uppermost volume area of the stratified storage are. Temperature fluctuations, even at the start of the charging process, are thus balanced, because a mix of the stratified storage content from the outset is excluded.

According to the invention, there is a hot water tap in the lid area of the stratified storage tank instead of. The fact that incoming hot water is redirected in terms of flow is that it is initially only in the uppermost volume area of the stratified storage there is a hot water tap even when the storage tank is completely empty practically immediately possible because the inflowing hot water cools down with a cold water layer below it does not take place.

The object underlying the invention is furthermore, as mentioned, also solved by a process which, depending on the hot water withdrawal and the amount of the same provides for various operational steps.

In the event of no hot water extraction, a predetermined switch-on temperature difference dT _Ein between a predetermined storage tank _target temperature T _Soll and a measured storage tank temperature T _{SP is} initially monitored. If this switch-on temperature difference dT _{On is} exceeded, the circulation pump and / or the heater is switched on or switched over to draw off a volume flow of cold water from the cold water fume cupboard, heat it in the heat exchanger and store the volume flow as hot water via the hot water line in the stratified storage tank. When a predetermined switch-off temperature difference dT _Aus between the storage tank temperature T _SP and a return temperature T _RL in the heating circuit-side return line is reached, the circulation pump and / or the heater is switched off or on.

If hot water is withdrawn that is less than the maximum volume of hot water that can be pumped, the step of monitoring a specified switch-on temperature difference dT _{On is followed} by switching on or switching over the circulation pump and / or the heater if the switch-on temperature difference dT _{On is} exceeded. A volume flow of cold water is withdrawn from the cold water inlet, heated in the heat exchanger and stored again as hot water in the stratified tank via the hot water pipe. Finally, the circulation pump and / or the heater are switched off or switched over when a predetermined switch-off temperature difference dT _off between the storage target temperature T _SP and the actual storage temperature has been reached.

In another operating state, which is larger is made as the maximum recoverable flow einzuspeichernden hot water as a result of monitoring a predetermined switch-dT _A switching or switching over the circulating pump and / or the heater in case of a hot water outlet when the switch-dT is exceeded _A , A partial volume flow of cold water is drawn off from the cold water inlet, heated in the heat exchanger and stored as hot water via the hot water line in the stratified tank, and another partial volume flow of cold water from the cold water inlet is fed into the stratified tank via the cold water drain. The circulation pump and / or the heater are switched off or switched over when a predetermined switch-off temperature difference dT _off between the storage tank target temperature T _SP and the actual storage tank temperature has been reached.

Further embodiments of the invention result from the subclaims.

Fig. 1

eine Ausführungsform der Erfindung, bei der ein Brauchwasserkreislauf und ein Heizkreislauf über einen im Gleichstrom betriebenen Plattenwärmetauscher miteinander gekoppelt sind.

The invention is described below using an exemplary embodiment which is explained in more detail with reference to the figure. Here shows:

Fig. 1

an embodiment of the invention, in which a process water circuit and a heating circuit are coupled to one another via a plate heat exchanger operated in direct current.

In the following description, the same parts have the same effect Reference numbers used.

The single figure shows a process water circuit B and a heating circuit H, which are coupled to one another via a plate heat exchanger 9 operated in direct current. The process water circuit B comprises a cold water inlet 12 which is connected to a cold water drain 4 of a stratified storage tank 6. A circulation pump 7 is arranged in the cold water drain 4, which transports cold water to the plate heat exchanger 9, where it is heated and fed as hot water via an hot water pipe 5 to an upper region of the stratified storage tank 6. The heated water can be removed via a process water extraction line 13, the mouth 2 of which is also arranged in the upper region of the stratified storage tank 6. Furthermore, a temperature sensor 1 for measuring a storage temperature T _{SP is arranged} at the mouth 3 of the cold water drain 4.

The heating circuit H comprises a burner heating water heat exchanger 10, which can be gas-operated, for example. From this heating water heat exchanger 10 runs a flow line 11 to the heating circuit water inlet of the plate heat exchanger 9 and a return line 14 with an associated return temperature sensor 15 and a heating circuit pump 8 from the heating circuit water outlet back to the heating water heat exchanger 10. The plate heat exchanger 9 is designed so that the hot water temperature T _WW in the hot water line 5 between plate heat exchanger 9 and stratified storage tank 6 corresponds to the return temperature T _RL . In this case, the target temperature T _{Soll of} the stratified storage device 6 serves as a reference variable for the return temperature T _RL . This makes a - usually necessary - additional temperature sensor in the area of the hot water outlet to the hot water pipe 5 or in the same superfluous. The temperature sensor for the return temperature T _{RL, which} is usually already provided in the heating circuit, is therefore sufficient to couple a stratified storage tank such as the stratified storage tank 6 shown to existing heating circuits. Furthermore, only the temperature sensor 1 for measuring the actual storage temperature T _{SP is} necessary for regulation in order to be able to assess the temperature profile in the layer structure and to be able to use it for regulation. Depending on the amount of hot water withdrawal via the hot water withdrawal line 13, the circulating volume flows in the hot water circuit and in the heating circuit can be adjusted by means of the circulation pump 7 or the heating circuit pump 8 so that the return temperature T _RL always corresponds approximately to the hot water temperature (storage tank charging temperature) T _WW . The positioning of the temperature sensor 1 at the level of the mouth 3 of the cold water fume cupboard 4 ensures a quick reaction when reloading the stratified storage tank 6, as a result of which maximum performance indicators are achieved. If, for example, a switch-on temperature difference dT _Ein between a predetermined storage tank _target temperature T _Soll and a storage tank temperature T _SP measured at temperature sensor 1 of -5 K is specified, then when this switch-on temperature difference dT _On is exceeded, the circulation pump 7 and / or the heating water heat exchanger 10 is switched on or switched over. The heating circuit-side return temperature T _RL is then regulated to the _target cylinder temperature T _target . Cold drinking water is heated in the plate heat exchanger 9 and stratified in the stratified storage tank 6 via the hot water line 5. This finally happens until a predetermined switch-off temperature difference dT _Aus between the actual cylinder temperature T _RL and the _target cylinder temperature T _Soll of, for example, -2 K is reached. In this case, the circulation pump 7 and / or the heating water heat exchanger 10 are switched off or on.

At this point it should be noted that all the parts described above by themselves seen and in any combination, especially those shown in the drawings Details are claimed as essential to the invention. Changes from this are familiar to the expert.

LIST OF REFERENCE NUMBERS

B

Hot water circuit

H

heating circuit

T _RL

Return temperature or actual cylinder temperature

T _SP

storage temperature

T _VL

flow temperature

T _WW

Hot water temperature

T _target

Stratified storage target temperature

dT _WT

Water temperature difference

T _A

Switch-on

T _off

Switch-off

1

temperature sensor

2

Brauchwasserauslass

3

Mouth of the cold water drain

4

Cold water withdrawal

5

Hot water pipe

6

stratified storage

7

circulating pump

8th

Heating circuit

9

Plate heat exchanger

10

Heating water heat exchanger

11

supply line

12

Cold water supply

13

Water extraction line

14

Return line

15

Return temperature sensor

Claims (12)

Hot water storage tank, in particular stratified storage tank (6), with a cold water inlet (12), a process water extraction line (13) and a cold water outlet (4) leading from the lower area of the same, in the course of which a circulation pump (7) is arranged and which leads to a heat exchanger (9 ) leads from which a hot water pipe (5) opens into the upper area of the stratified storage tank (6),
characterized in that
the heat exchanger (9) is assigned to a heating circuit (H) with a heater (10), heating circuit pump (8) and supply line (11) and return line (14), and that a predetermined target temperature (T _target ) of the stratified storage tank (6) corresponds to the target value determined for the return temperature (T _RL ) of the heating circuit (H). Hot water tank according to claim 1,
characterized in that
the heat exchanger (9) can be operated in cocurrent or, in particular in countercurrent, and is designed such that the heating circuit-side return temperature (T _RL ) is approximately the same as the hot water temperature (T _WW ) in the hot water line (5) between the heat exchanger (9) and stratified storage tank ( 6) corresponds. Hot water tank according to claim 1 or 2,
characterized in that
an average temperature difference (dT _WT ) can be varied by means of a power rating on the circulating pump (7) and / or the heating circuit pump (8). Hot water tank according to one of the preceding claims,
characterized in that
If a predetermined switch-on temperature difference (dT _On ) between the measured storage tank temperature (T _SP ) and the predetermined storage tank temperature (T _target ) is exceeded, a charging process can be triggered in which the circulation pump (7) and / or the heater (10) are switched on or over , Hot water tank according to claim 4,
characterized in that
the switch (dT _ON) in the range between -0.5 K and -15 K, preferably in the range between -1 K and -12 K and especially in the range between -2 K and -10 K. Hot water tank according to one of the preceding claims,
characterized in that
_{if the} temperature falls below a predetermined switch-off temperature difference (dT _Aus ) between the measured cylinder temperature (T _SP ) and the predetermined cylinder temperature (T _Soll ), the charging process can be stopped and the circulation pump (7) and / or the heater (10) can be switched off or on. Hot water tank according to one of the preceding claims,
characterized in that
only one temperature sensor (1) in the stratified storage tank (6) and one return temperature sensor (15) in the area of the return line (14) of the heating circuit (H) is provided, in particular required, for temperature control. Hot water tank according to claim 7,
characterized in that
the temperature sensor (1) is arranged approximately at the level of the mouth (3) of the cold water drain (4) in the lower region of the stratified storage tank (6). Hot water tank according to claim 7 or 8,
characterized in that
the temperature sensor (1) is arranged between 2.0 cm and 10 cm above the floor level of the stratified storage tank (6). Method for storing hot water in a storage tank, in particular in a stratified storage tank (6), with a cold water inlet (12), a process water extraction line (13) and a cold water outlet (4) leading from the lower area of the same, in the course of which a circulation pump (7) is arranged and which leads to a heat exchanger (9), from which a hot water pipe (5) opens into the upper region of the stratified storage tank (6), in particular with a heat exchanger (9) which connects a heating circuit (H) with a heater (10) , Heating circuit pump (8) and supply (11) and return line (14) is assigned,
marked by
the following steps if no hot water is drawn: A) monitoring a predetermined switch-on (dT _ON) between a predetermined cylinder temperature (T _Soll) and a measured storage tank temperature (T _SP); B) Switching on or switching over the circulation pump (7) and / or the heater (10) for withdrawing a volume flow of cold water from the cold water fume cupboard (4), heating the same in the heat exchanger (9) and storing the volume flow as hot water via the hot water line (5 ) in the stratified storage tank (6) when the switch-on temperature difference (dT _On ) is exceeded; and C) Switching off or switching over the circulation pump (7) and / or the heater (10) when a predetermined switch-off temperature difference (dT _Off ) between the storage tank temperature (T _SP ) and the storage tank target temperature has been reached. Method for storing hot water in a storage tank, in particular in a stratified storage tank (6), with a cold water inlet (12), a process water extraction line (13) and a cold water outlet (4) leading from the lower area of the same, in the course of which a circulation pump (7) is arranged and which leads to a heat exchanger (9), from which a hot water pipe (5) opens into the upper region of the stratified storage tank (6), in particular with a heat exchanger (9) which connects a heating circuit (H) with a heater (10) , Heating circuit pump (8) and supply (11) and return line (14) is assigned,
marked by
the following steps in the case of hot water extraction, if this is less than the maximum volume flow of hot water to be stored: A) monitoring a predetermined switch-on (dT _ON) between a predetermined cylinder temperature (T _Soll) and a measured storage tank temperature (T _SP); B) Switching on or switching over the circulation pump (7) and / or the heater (10) for withdrawing a volume flow of cold water from the cold water inlet (12), heating the same in the heat exchanger (9) and storing the volume flow as hot water via the hot water line (5 ) in the stratified storage tank (6) when the switch-on temperature difference (dT _On ) is exceeded; and C) Switching off or switching over the circulation pump (7) and / or the heater (10) when a predetermined switch-off temperature difference (dT _Off ) between the storage tank temperature (T _SP ) and the storage tank target temperature has been reached. Method for storing hot water in a storage tank, in particular in a stratified storage tank (6), with a cold water inlet (12), a process water extraction line (13) and a cold water outlet (4) leading from the lower area of the same, in the course of which a circulation pump (7) is arranged and which leads to a heat exchanger (9), from which a hot water pipe (5) opens into the upper region of the stratified storage tank (6), in particular with a heat exchanger (9) which connects a heating circuit (H) with a heater (10) , Heating circuit pump (8) and supply (11) and return line (14) is assigned,
marked by
the following steps in the case of hot water extraction, if this is greater than the maximum volume flow of hot water to be stored: A) monitoring a predetermined switch-on (dT _ON) between a predetermined cylinder temperature (T _Soll) and a measured storage tank temperature (T _SP); B) Switching on or switching over the circulation pump (7) and / or the heater (10) to withdraw a partial volume flow of cold water from the cold water inlet (12), heating the same in the heat exchanger (9) and storing the volume flow as hot water via the hot water line (5 ) in the stratified storage tank (6), as well as supplying another partial volume flow of cold water from the cold water inlet (12) via the cold water outlet into the stratified storage tank (6) if the switch-on temperature difference (dT _On ) is exceeded; and C) Switching off or switching over the circulation pump (7) and / or the heater (10) when a predetermined switch-off temperature difference (dT _Off ) between the storage tank temperature (T _SP ) and the storage tank target temperature has been reached.

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