EP0807790B1 - Method and system for prepairing sanitary hot water - Google Patents

Abstract

The device comprises a primary circuit (10) which has a heater (1) producing warm or hot fluid and a conveyor (14) with a regulator for the fluid. A secondary circuit (20) is for the service water to be heated up. A heat exchanger (5) transfers heat from the fluid in the primary circuit to the service water in the secondary circuit. The primary circuit in the heat exchanger or the output side pipe (13) has a first temperature sensor (17). The secondary circuit in the heat exchanger or the output side pipe (23) has a second temperature sensor (27). The regulator has a circuit which switches on the conveyor when the temperature drops below a nominal value and or exceeds a nominal value on the second temperature sensor, and switches off the conveyor when the temperature exceeds a nominal value and or exceeds an amount on the first temperature sensor.

Description

The invention relates to an arrangement and a method for providing hot domestic water with a primary circuit with a fluid, a warm or hot fluid providing means and a conveyor for the fluid, a secondary circuit for the domestic water to be heated, a heat exchanger for heat transfer from the fluid of the primary circuit to the process water in the secondary circuit, a control device for the Conveyor and one temperature sensor each in the primary circuit and in the secondary circuit.

The hot domestic water is conventionally provided by means of a Heat source in a domestic hot water tank, a so-called boiler, which is included also takes on the task of intermediate energy storage.

In many cases it makes sense and is also proven to separate the process water here on the one hand and the actually heated fluid on the other hand. This fluid is usually also water, but for example that Water from a heating system that is not for normal consumption or Use is intended.

DE 295 19 473 U1 proposes a flow water heater. With this, a process water queue runs through a heating water tank, afterheating during hot water extraction an associated heating device is to take place. To realize that a Hot water is withdrawn from the mouth of the hot water snake in the heating water tank a temperature sensor with good thermal conductivity Contact with the service water snake arranged. After the start of the tap cool fresh water flows through exactly this junction area, and the resulting small temperature drop is transferred to the temperature sensor, which can thus be used to control the heating device.

In other cases, the process water is heated using an external heat exchanger heated as a continuous flow heater. The fluid or heating water pumped in a primary circuit through the heat exchanger, which contains the process water warmed in the secondary circuit. So there is cold water in the secondary circuit fed to the heat exchanger and there to the desired temperature brought by the heat from the heating water from the heat generator is transferred to the domestic water by the heat exchanger. After passing through the heat exchanger, the process water is heated Form available.

Particularly suitable as a source or storage for the hot fluid or heating water are so-called stratified loaders, such as those from the EP 0 384 423 B1 are known. They are in a storage vessel at the top hotter, the cooler water or fluid amounts are stacked on top of each other. The primary circuit draws hot fluid from the top of the storage vessel flows through the heat exchanger mentioned and then becomes corresponding cooled down again in a range corresponding to the temperature Storage vessel between the amounts of water or fluid located there sandwiched.

To maintain a reasonably constant water temperature in the process water To be able to provide a control device can be provided.

Such a control device is known for example from CH-PS 285 708; there is a temperature sensor provided, either in the primary circuit or but is also provided in the secondary circuit and on a three-way valve acts and so on a change in the mixing ratio of the heating water in the primary circuit the primary temperature in the heat exchanger regulates.

If the way of functioning is otherwise the same, for example, in DE 40 35 115 C2 a speed control controlled by a flow switch the pump in the primary circuit. A disadvantage, however the use of a flow switch in the hot water pipe proved. Flow monitors require considerable purchase and installation costs and are extremely prone to errors. As such, the flow monitors are supposed to because of a flow rate recognize whether water flows, therefore Domestic water is withdrawn, and depending on this, circulation pumps turn off.

EP 0 226 246 A1 describes a control device for the hot water supply known, each with a temperature sensor in the primary circuit and in the secondary circuit is equipped. The proposed temperature control seems however not being optimal yet.

The object of the invention is to provide an arrangement and a method of hot domestic water to propose that without the mentioned such Flow monitor manages and at the same time an inexpensive control option creates.

With an arrangement, this object is achieved in that in the primary circuit in the heat exchanger or in the outlet side with respect to the heat exchanger Line of the first temperature sensor is arranged that in the secondary circuit in Heat exchanger or in the output side with respect to the heat exchanger Line of the second temperature sensor is arranged, and that the control device has a circuit that the circuit at below a setpoint falling temperature and / or a positive setpoint Temperature gradients and / or a falling below a negative setpoint Temperature gradients on the second temperature sensor the conveyor switches on and that the circuit when the temperature rises above a setpoint and / or a temperature gradient on a setpoint exceeding the first temperature sensor switches off the conveyor.

In one method, the object is achieved in that both in the primary circuit in the heat exchanger or in the outlet side with respect to the heat exchanger Pipe the temperature that is measured in the secondary circuit in the heat exchanger or in the outlet side with respect to the heat exchanger Line the temperature is measured, and that at below a set point falling temperature and / or rising above a positive setpoint Temperature gradients and / or temperature gradients falling below a negative setpoint in the heat exchanger or in the one leading away from the heat exchanger Line in the secondary circuit, the conveyor, the fluid in the primary circuit begins to promote, and that when the temperature rises above a setpoint and / or increasing the temperature gradient in the heat exchanger via a setpoint or in the line away from the heat exchanger in the primary circuit Promotion of the fluid in the primary circuit is ended.

Through this consistent use of temperature sensors and the determination of temperatures and / or temperature gradients can completely affect all Flow monitors are dispensed with.

Nevertheless, it is possible to always maintain the desired hot water temperature (Hot water temperature).

First consider the switch-on criterion for the funding facility of the Fluid, so this is essentially from the temperature sensor in the hot water circuit certainly. This temperature sensor is particularly preferred arranged directly at the outlet of the heat exchanger in the secondary circuit. Now, after the water has stopped, the tap in the hot water pipe opened and hot water is requested, the process water begins in the secondary circuit to pour. The temperature that was initially on the stand of the heat exchanger, i.e. at a relatively high level, starts quite spontaneously to drop when the water comes from the cold water supply of the domestic water the heat exchanger is running, whose heat reserve naturally decreases.

This falling temperature is immediately recognized by the temperature sensor. This can happen in a variant that this temperature below a Desired value falls, in a preferred variant this is simply due to the temperature gradient detected. The latter also has the advantage that with one Commissioning of the control with cold storage (initial commissioning) of the conveyor is not switched on, although a setpoint is undershot.

One of these two criteria immediately leads to the activation of the conveyor in the primary circuit, the now hot fluid of the primary circuit Feeds heat exchanger and so a heat transfer within the heat exchanger from this fluid to the process water.

The conveyor does not switch off yet, as there is still hot water is removed and thus there is still a need for heat supply. Although is the temperature gradient at this second temperature sensor in the secondary circuit now very low or fluctuates around a zero value and the temperature is therefore constant and also above the setpoint, but it is just fine here not a switch-on criterion: the conveyor is still running.

However, if the process water withdrawal is now stopped, the primary circuit the thermal energy of the hot fluid no longer reaches the domestic water given because this is already at the appropriate temperature and none additional feed needed. As a result, the fluid flows in the primary circuit through the heat exchanger without losing its heat entirely have, resulting in a very rapid rise in temperature in the area of the first Temperature sensor on the output side of the heat exchanger in the primary circuit leads. This rising temperature can either be exceeded a setpoint or also by recognizing a temperature gradient as Switch-off criterion are used and thus stops the conveyor.

A particularly quick response is guaranteed if the respective Temperature sensor provided on the output side of the heat exchanger are. In certain applications, it may even be useful to use the temperature sensor to be provided within the heat exchanger. The denser the Temperature sensors on the heat exchanger, the faster they can be Detect temperature changes and thus the emergence of unwanted Prevent cold water areas in the hot water delivery.

The conveyor, especially a pump, in the primary circuit should follow Possibility in the one leading away from the heat exchanger, that is, in its outlet side Line be arranged. This leads to the conveyor colder primary fluid flows through, especially when stationary, which is cheaper for their durability and ease of maintenance. It is special useful if the first temperature sensor between the heat exchanger and the conveyor is arranged.

The arrangement and the method can be used particularly well if the warm or hot fluid is provided by a buffer, but The flow of a boiler, a district heating network or the like are also suitable.

When used in connection with a buffer memory, it is preferred if a third temperature sensor is also provided, which is either in the buffer memory or is in the line from the buffer tank to the heat exchanger. The control device has a further circuit with which the temperature determined by the third temperature sensor when determining the Setpoint of the temperature at the second temperature sensor is used. In this way, the case can be taken into account that possibly there is not enough warm or hot fluid in the buffer storage, for example when starting up the system for the very first time or simply afterwards previous considerable consumption. It can then be lowered the setpoints of the temperatures on the second temperature sensor prevented be that the buffer continuously releases more content without it is possible at all, the otherwise desired by the control device To reach target values.

Furthermore, it is possible through the invention by observing the storage temperature in relation to the desired water temperature, a thorough mixing of the memory due to an excessive flow rate of the primary circuit prevent and maintain standby. For that a diagram of the temperature profile at various measuring points on Heat exchangers and storage tanks with regard to typical user behavior, i.e. there were different water quantities and the Aufund Simulated turning off the tap. If the heat storage is not the has the necessary temperature for the hot water target temperature, the Target hot water temperature from the storage tank temperature minus one adjustable difference is calculated. The hot water target temperature is therefore not an absolute value, but - if the storage tank temperature is too low - also dependent on this.

If the storage tank temperature during operation falls below that for the hot water setpoint control required temperature level falls, but would Run the pump full to get as close as possible with the maximum available energy to get to the set hot water setpoint. By the maximum primary flow, the primary return temperature rises unnecessarily high on. This can lead to rapid disintegration or temperature stratification come in the store, causing a further drop in the store temperature Consequence. Therefore, the actual hot water setpoint can be taken from the Storage temperature minus the set difference can be calculated. As a result, the primary flow is exceeded above a desired one Limit value avoided and the storage stratification remains under all operating conditions receive.

A pump runtime is useful to after switching on Temperature fluctuations that are regarded as a switch-off criterion could bridge. Furthermore, it is normally chosen so that enough heat energy is pumped into the system to the heat exchanger and thus the hot water outlet to the required temperature bring.

It is also particularly preferred if the conveyor device has a speed-controlled pump and the control device has a circuit, which depend on the temperature gradient at the second temperature sensor also the conveyor speed of the conveyor, for example the speed, regulates.

It is also particularly preferred if one or both temperature sensors, preferably together with the heat exchanger within the insulation of the Buffer memory are arranged. This allows the heat exchanger to reach the target temperature be kept, simply by heat conduction automatically from the buffer memory.

The control device can also be a special combination of different Use process stages. So for a limited period of time For example, a startup control program can be run for 30 seconds provides a constant predetermined speed of the pump, or else one special P-I-D setting that react very quickly to changes in temperature can. This is precisely the reason why the The target temperature is maintained and cold water holes avoided.

The use of the temperature gradient amount as a switch-on criterion also proved to be useful for the following reason: After the Turning on the hot water tap is in the heat exchanger Process water at a slightly higher level than this a short one Continue the thermal sensor on the output side of the heat exchanger can determine. This effect is, among other things, that due to convection currents on the primary side in the heat exchanger there is a whole sets a slightly higher temperature than when the secondary circuit is not running can be the case in industrial water. This is usually hardly an effect measurable. However, it has the consequence that after turning on the tap for a brief moment the temperature at the second thermal sensor in the secondary circuit increases, and very slightly, because the slightly hotter amount of hot water flows from the heat exchanger past the thermal sensor. This determines a temperature gradient; that this is positive plays for the amount of the temperature gradient is irrelevant and thus leads in the control device that the conveyor is turned on. This happens at a time when there is a risk of a cold water hole has not yet arisen, so that it is much faster than falling below the setpoint of the temperature (the second switch-on criterion) already the conveyor runs and hot fluid in the primary circuit in the heat exchanger brings.

If this effect does not occur, perhaps because there is still no effect of convection slightly higher temperature level in the heat exchanger has set, the control device also sets it in the case of the temperature gradient, its amount is fixed due to its falling and can react accordingly.

Figur 1 eine Schema-Darstellung der Erfindung.

In the following an embodiment of the invention will be described with reference to the drawing. It shows:

Figure 1 is a schematic representation of the invention.

The purely schematic, only the most essential parts of the entire arrangement The illustration in the left half shows a primary circuit 10 in which right half a secondary circuit 20.

The primary circuit 10 begins on the left with a device that is warm or hot Provides fluid, here a buffer store 11. From this buffer store 11 leads a line 12 to a heat exchanger 5. After passing through of the heat exchanger 5 and the delivery of thermal energy in the same leads the fluid in the primary circuit 10 back via an outlet line 13 to the buffer store 11. In the outlet-side line 13 there is a conveying device, here a pump 14 is provided between the heat exchanger 5 and the pump 14 a first temperature sensor 17 is arranged.

Usually the hot fluid comes from the upper area of the buffer storage 11 removed, fed to the heat exchanger 5 and by the pump 14 conveyed returned to the lower area of the buffer memory 11.

One can be used to layer the cooled fluid in the buffer store 11 fluid single-layer device 18 indicated here only very schematically are provided, for example a stratified charger according to the EP 0 384 423 B1. In the buffer memory 11, hot fluid thus remains undisturbed upper area, where the line 12 also pulls it off. extra hot fluid or thermal energy for heating existing fluids can by layering fluids heated by solar collectors and / or by Installation of burners (each not shown) or in another way to be provided.

The secondary circuit 20 on the right begins with a cold water supply 22, with the cold process water (drinking water, wash water etc.) the Heat exchanger 5 is supplied. The heat energy is in the heat exchanger 5 of the primary circuit 10 running in counterflow. To Passing through the heat exchanger 5, the process water in turn leaves it and flows through an outlet-side line 23 to the hot water withdrawal point. Funding in the secondary cycle can, for example take place that the cold water supply takes place under pressure and the hot water withdrawal point This pressure is blocked by a tap if necessary.

Located in line 23 for the hot water or actual service water a temperature sensor 27. The temperature sensor 27 thus sets the hot water temperature as close as possible to the heat exchanger 5.

The temperature sensors 17 and 27 report their values to a control device, not shown.

The same is done by a third temperature sensor 37, which is the temperature of the hot one Receives fluids in the upper region of the buffer memory 11.

The control device then controls the pump 14, on the one hand that Switching on and off and, on the other hand, the speed or Conveying speed.

LIST OF REFERENCE NUMBERS

5

heat exchangers

10

Primary circuit

11

buffer memory

12

management

13

management

14

pump

17

temperature sensor

18

Fluideinschichtvorrichtung

20

Secondary circuit

22

Cold water supply line

23

Pipe to the hot water withdrawal point

27

temperature sensor

37

temperature sensor

Claims (12)

1. System for preparing warm service water, with

   a primary circuit (10) with a fluid, a device (11) preparing warm or hot fluid and a delivery device (14) for the fluid,

   a secondary circuit (20) for the service water which is to be heated,

   a heat exchanger (5) for transferring heat from the fluid of the primary circuit (10) to the service water in the secondary circuit (20),

   a regulating device for the delivery device (14) and

   a respective temperature sensor (17, 27) in the primary circuit (10) and in the secondary circuit (20),

   characterised in that the first temperature sensor (17) is disposed in the primary circuit (10) in the heat exchanger (5) or in the line (13) on the outlet side relative to the heat exchanger (5),
   that the second temperature sensor (27) is disposed in the secondary circuit (20) in the heat exchanger (5) or in the line (23) on the outlet side relative to.the heat exchanger (5),
   that the regulating device comprises a circuit,
   that the circuit turns on the delivery device (14) when the temperature drops below a set value and/or the temperature gradient exceeds a positive set value and/or the temperature gradient falls below a negative set value at the second temperature sensor (27) and
   that the circuit turns off the delivery device (14) when the temperature exceeds a set value and/or the temperature gradient exceeds a set value at the first temperature sensor (17).
2. System according to Claim 1,
   characterised in that the delivery device (14) is disposed in the primary circuit (10) in the line (13) leading away from the heat exchanger (5), wherein the first temperature sensor (17) is disposed between the heat exchanger (5) and the delivery device (14).
3. System according to Claim 1 or 2,
   characterised in that the first and the second temperature sensors (17, 27) are disposed closely adjacent to the respective outlets of the heat exchanger (5).
4. System according to any one of the preceding Claims,
   characterised in that the device (11) preparing warm or hot fluid comprises a buffer store,
   that a third temperature sensor (37) is provided in the buffer store (11) or in the line from the buffer store (11) to the heat exchanger (5), and
   that the regulating device has a further circuit by way of which the temperature which is determined by the third temperature sensor (37) is used when fixing the set value of the temperature.at the second temperature sensor (27).
5. System according to any one of the preceding Claims,
   characterised in that the regulating device comprises delay elements which bridge fluctuating determined temperature values at the temperature sensors.
6. System according to any one of the preceding Claims,
   characterised in that the regulating device comprises a circuit which regulates the delivery speed of the delivery device (14) for the fluid in dependence on the speed of the temperature value decrease or the temperature gradient at the second temperature sensor (27).
7. System according to Claim 6,
   characterised in that the delivery speed of the delivery device (14) is regulated by varying the rotational pump speed of a speed-regulated pump.
8. System according to any one of the preceding Claims 4 to 7,
   characterised in that the first and/or the second temperature sensor(s) (17, 27), preferably both, is/are disposed, preferably with the heat exchanger (5), inside the insulation of the buffer store (11).
9. Method for preparing warm service water,

   wherein a fluid runs in a primary circuit, a device (11) prepares warm or hot fluid and a delivery device (14) delivers the fluid

   wherein the service water which is to be heated runs in a secondary circuit,

   the heat is transferred in a heat exchanger (5) from the fluid of the primary circuit (10) to the service water in the secondary circuit (20),

   the delivery device (14) is regulated, and

   a respective temperature sensor (17, 27) is provided in the primary circuit and in the secondary circuit,

   characterised in that the temperature is measured in the primary circuit (10) in the heat exchanger (5) or in the line (13) on the outlet side relative to the heat exchanger (5),
   that the temperature is measured in the secondary circuit (20) in the heat exchanger (5) or in the line (23) on the outlet side relative to the heat exchanger (5), that the delivery device (14) starts to deliver the fluid in the primary circuit (10) when the temperature drops below a set value and/or the temperature gradient exceeds a positive set value and/or the temperature gradient falls below a negative set value in the heat exchanger (5) or in the line (23) leading away from the heat exchanger in the secondary circuit (20), and
   that the delivery of the fluid in the primary circuit is terminated when the temperature exceeds a set value and/or the temperature gradient exceeds a set value in the heat exchanger or in the line leading away from the heat exchanger (5) in the primary circuit (10).
10. Method according to Claim 9,
    characterised in that the temperature of the warm or hot fluid in the primary circuit (10) is used when determining one or more of the set values.
11. Method according to Claim 9 or 10,
    characterised in that the value of the temperature gradient is used to regulate the delivery speed of the delivery device.
12. Method according to any one of Claims 9 to 11,
    characterised in that the temperature gradient value is used in the regulation process irrespective of the sign of the actual temperature gradient.

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