DE1928575A1 - Process for regulating heating systems working with liquid heat carriers and heating systems for carrying out the process - Google Patents

Description

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Dr. Hans Alfred Troesch 8103 Unterengstringen, Germany

(Zuri ch, S ci> 7c Lζ)

Method of regulating with liquid Heat carrier working heating systems and heating systems for the execution of the Procedure

The present invention relates to a method for regulating heating systems that operate with liquid heat transfer media with at least one circulation pump in the heat transfer system as well as a device for admixing backflowing, cooled liquid into the flow stream to achieve this and maintaining a controlled variable, in particular the ■ Flow or room temperature, with the adjustment of the return admixing device with the help of a pressure difference generated by the circulation pump takes place as well as a heating system to carry out the procedure.

In central heating systems with liquid heat carriers and a constant temperature in the heat accumulator (e.g. in the form a boiler, heat converter or the like.) is usually a line bridging the heat accumulator or heat dispenser,

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a so-called bypass line is provided, which via a three-way mixing element opens into the flow line. This three-way mixing organ can be operated e.g. by means of a servomotor that is controlled by a control device. The control device in turn receives its signals from e.g. temperature sensors located in the heating medium flow and in a room. That ensures Control device for the fact that the radiators of the heat transfer medium with the appropriate position of the mixer from the flow the corresponding temperature flows in, so that the heat dissipation this heating element runs stationary at the intended or predetermined temperature or the setpoint temperatures. If the outside temperature changes, the flow temperature is then regulated via the control device. This scheme will referred to as weather-dependent regulation, whereby the outside temperature is the FühüHgßgrosse and "the flow temperature is the Represents the controlled variable.

Temperature controls could only be based on room temperature or after a constant flow temperature. Instead of the motor drive of the three-way mixing element, a thermal drive, e.g. a bimetal operated drive, which moves the mixing element into the ' Position.

There are also very simple temperature controls on central heating systems are known, in which by means of a thermostat-controlled, servomotor-operated throttle

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flap the flow is opened or closed

The disadvantage of these types of regulation is on the one hand their complicated structure and therefore their high price or in the intermittent charging of the radiators hot boiler water, which results in large fluctuations in room temperature and a very uncomfortable climate, in that in such regulated rooms there is always either a feeling of coldness or the feeling of being too hot

Also the obvious idea, the flow rate of the circulation pump in a constant way by an i-controller Controlling according to the heat demand of the heating system fails in general, because when there is little heat demand, i.e. when there is a small flow rate, the heat distribution in the heating system becomes very bad

The present invention aims to provide a method which bypasses the aforementioned disadvantages and enables the construction of a heating system that allows the to keeps the heating tube at practically constant temperatures.

This procedure is characterized by the fact that at least one? part of this ^v 'pressure difference changed in the sense of a control effect -

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The heating system for carrying out this process, in which between the heat dispenser and the confluence the Bvpassleitung in the flow on the one hand and in the Bypass line, on the other hand, a pressure-difference-controlled volume regulating element for generating a predetermined one Flow mixing temperature is arranged Tgekindicated by means of the means for changing the pressure difference controlling regulator

The invention is then for example based on Figures explained It show:

1 shows a system diagram of a central heating system according to the invention

Fig. 2 and 3 are schematic representations of regulating organs . in the flow and in the bypass line of the heating system with a schematically drawn circulating pump.

Fig. H is a circuit diagram of an automatic control device for a mixed water pump heating system

5 shows a switching system of a heating system, according to an embodiment within the meaning of the invention

6 shows a variant of a circuit of a heating system analogous to that according to FIG.

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FIG. 7 shows a characteristic with the operating point of the circulation pump in the diagram according to FIG. 4

8 shows a pump characteristic with a fixed total resistance of the system and a variable speed of the circulating pump and

9 shows a variable speed pump characteristic the pump and variable resistance of the system.

A boiler flow line 3 leads from a heat source, for example a boiler 1, via a pump flow line 5 to a circulating pump 7. From this a supply line 9 leads the heat transfer medium to a radiator 11 When part of its heat is released, the heat transfer medium flows back through a return line 13 into the boiler. A bypass line 15 enables boiler 1 to be short-circuited or to bridge and the hot heating medium in the boiler flow line Mix in 3 colder return water. For the purpose of controlling the temperature of the in the pump supply line 5 arriving heat transfer medium is in the boiler flow line 3 and in the bypass line 15 an actuator of known type with a servomotor 17 and a 19 installed, the design of which is explained in more detail below. The valve 19 has a valve disk 20 on the valve stem 22

on, which in the closed positions either on the seat of a valve seat plate 18 or on the one designed as a valve seat The end of the bypass pipe 15 rests. The connection of the Purapen-

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suction line 5 with one side of the control diaphragm 27 takes place via a line 24, that of the Purapendruclcleitung or Supply line 9 with the other side of the membrane 27 via a line 26. An outside temperature sensor 21 and a flow water temperature sensor 23 act on a control device 25, which in turn influences the speed of the circulating pump 7, whereby the heat medium flow circulating in the heating system can be increased and also the delivery head of the P circulation pump, due to the increasing resistances in the system, increases according to the pump characteristics, the diaphragm 27 is clamped on its circumference and its restoring force is based on their elasticity and if necessary with an adjustable return spring (not shown).

The system is coordinated in such a way that when the outside temperature falls and the temperature in the room of the radiator 11 falls, the setpoint of the temperature of the flow water rises and the required flow water temperature is achieved by changing the pump speed. When the outside temperature falls, i.e. when the water flow temperature setpoint increases, the control device 25 increases the speed of the circulating pump 7, which on the one hand increases the pressure difference created by the pump, the delivery head, between the suction and pressure sides and, on the other hand, increases the throughput. This increase in the differential _{pressure is used to} control the actuator 16 in the sense that it is used. Flow line 3 accordingly opened: open and the. Bypass line 15 closed accordingly, maW against the

Closed position is adjusted. Of the

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Valve plate 20 moves against the mouth of the bypass line 15. The flow temperature increases and with it the heat dissipation of the radiator 11, whereby the decrease in the outside temperature by regulating the heating system accordingly is worn and the temperature of the room with the radiator 11 remains in the intended temperature range. It is of course also possible to use instead of the outside thermometer To install room thermometer, which acts accordingly on the control device 25.

The control device 25 is with respect to its output signal or control command the needs of the circulation pump 7 and the Drive motor of the pump 7 adapted. The actuator 16 is dimensioned and arranged so that it is in extreme operating conditions the flow line 3 releases fully open or the bypass line 15 keeps completely closed or vice versa.

In Fig. 2, a section is shown in a schematic representation from the heating system in the area of the circulation pump 7 and the flow line 3 and the bypass line 15. The supply line 3 and the bypass line 15 are connected to the side of the valve housing 50. The discharge takes place via the circulation pump suction line 5, which the circulation pump 7 follows. Two cages 52 and 54 are arranged in the valve housing 50. On a Valve rod 56 is for the flow line 3 and for the bypass line 15 each a valve plate 59 or 60 is provided. A spring 63 supported on the cage 54 generates the corresponding spring

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Restoring force on the valve rod 56. At one end of the valve rod 56, facing the pump 7, there is a Floating piston 65. Due to the arrangement of the valve disks 59 and 60 shown, pressure equalization occurs on the displaceable one Part of the valve. The forces on the valve disks 59 and 60 caused by the fluid pressure are balanced. Therefore, in this design, the actuating force is dependent on the pump speed or the delivery rate the pump and the delivery pressure are changed with the help of the floating piston. With increasing throughput, due to the larger drag forces on the floating piston 65, this moves towards the pump 7, wherein it moves the valve disk 59 of the mixing valve for the boiler flow line 3 opens and the valve disk 60 against the seat of the cage 54, i.e. closing, emotional. The flow mix temperature is increased as this is done by the aim was to increase the speed of the circulation pump 7. The spring 63 takes over the counterforce of the drag force on Floating piston 65. This spring 63 is a return spring.

In the embodiment according to FIG. 3, there are again two cages 72 and 72 in a valve housing 70, as well as a valve rod 74 provided with the valve plates 77 and 78. The free end the valve rod 74 is on a membrane 81, which the actuating ' represents motor attached. It divides, together with the circulation pump 7, the valve housing 70 into a suction and a Printing room. This occurs because the pressure forces on the valve

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plates 77 and 78 compensate for the displacement of the valve rod 74 and the plates 77 and 78 duroh those on the membrane 81 effective difference of the pressure-related forces. This results also the necessary restoring force * According to the change the delivery head of the pump, the membrane is pushed to the left as the values increase. The opening of the mixing valve for the boiler flow line 3 opens when the Valve plate 77 removed from its seat in cage 71. The opening of the mixing valve for the bypass line 15 closes by placing the valve disk 78 against the seat of its cage 72 is moved out. If the pump speed of the circulation pump is reduced, the pressure difference between the right one drops and the left side of the membrane 81, which is preferably adjustable in terms of hardness, and this slides out of it to the left bulging position against its stretched rest position, whereby the valve disc 77 of the boiler * flow line 3 slackens and that 78 in the bypass line 15 opens.

As ^ circulation pumps, positive displacement pumps, propeller or Centrifugal pumps can be used. A speed-controllable electric rotor is advantageously used to drive them used, which may be gfsjpiesen from the control device as a power source »

Other means can also be used for resetting the valves as springs, e.g. pneumatic elements, whose

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Adjustment is also made possible by appropriate means, e.g. diaphragms, etc. If necessary, the reset elements can be operated centrally. It is also possible to have several volume regulating members rigid, as explained, or elastic, e.g. via a spring to connect with each other.

By setting the spring forces and their relationship to one another, the heating characteristics of the heating system can be related can be set to the object to be heated ^ (building, part of a building, room, etc.). Likewise, by the choice of spring forces the performance range, m, a.W. the work area in which the circulation pump is controlled, determined.

The relationship between the outside temperature and the flow temperature, ie their quotient, is called the slope. The control device with all its .. _; Setting and operating means and, where required, .with a x ... ^ o'clock for the time program, with the circulation pump and the regulating organs.

In order to be able to adapt the circulation pump to the heating system in which it is installed, the simplest thing to do is to use the pump with a changeable one to be determined when assembling the system and the throttle to be set is provided, with whose " Help the resistance parabola of the whole system for one

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Pump type is adjusted to the setpoint parabola. For this purpose, the throttle is more or less closed. This makes possible, that 'the' pump with a predetermined speed range of variation can be delivered regardless "of the system, since it is always the resistance parabola runs on the same part of the curve.

Another, but more complicated, possibly but- im Operation cheaper solution consists in adjusting the variation speed range by setting the appropriate pump speed to achieve a predetermined normal flow rate per radiator. This speed setting can be switched on done by electrical resistances. However, this solution requires the control pressure difference due to the changed setpoint for the mixing element also a respective coordination of this mixing element.

An essential thought, as explained with the aid of the exemplary embodiments has been explained, consists in the fact that a primary control intervention mainly affects the interception ratio and a secondary control intervention derived therefrom takes place mainly on the circulating quantity. It arises with it two mutually supporting actuating actions on the controlled system.

Fig. 4 shows the scheme of a known system, with a boiler 85, one or more radiators 87 and one Mixing valve 89 and a circulation pump 90 with a pump motor 91. A boiler flow line 93 leads from the boiler

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85 to mixing valve 89, while a supply line 95-from Coming from the circulation pump 90, the radiator or radiators are supplied with pre-flow heating water. A return line 97 leads the cooled water from the radiator 87 either the Boiler 85 or through a bypass line 98 to the mixing valve 89.

The mixing valve 89 is controlled by a room thermostat 103, which controls a solenoid valve 101 in a pressure line 100 such that it is either in its open position brings the full pressure from the pressure side of the pump 90 to the mixing valve 89 into effect or this valve 89 by closing the solenoid valve 101 keeps pressureless. In this way, it is ensured that the mixing valve 89 occupies two positions: In one The hot water arrives from the boiler 85 via the flow line 93 and the mixing valve 89 to the circulation pump and from there through the supply line 95 into the radiator 87, from where it is through the return line 97 to the boiler 85 returns ·. In the other position of the mixing valve the boiler flow line 93 is closed and the water flowing back via the return line 97 is The mixing valve 89 is supplied via the bypass line 98.

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In this known arrangement, the heating elements 87 are supplied either with water circulating through the boiler 85 Water or with the water through the bypass line 98, in which case the boiler 85 is completely switched off. By this measure ^ the temperature and the flow rate of the heating medium in the system is kept essentially constant because of the resistance ratios in the system are approximately the same when passing and when passing through the boiler, i.e. are made.

Since this known system is an open-close regulation for the bypass and the normal flow 'flow and the resistances in the system are matched accordingly appears in the associated pump characteristic according to FIG. 7 with a fixed resistance W of the system, and at a fixed speed η, the operating point P of the pump as an invariant, which point P does not change even when switching from the flow to the bypass. It there is no regulation with a change in the operating point and the pressure difference generated by the circulation pump 90 plays no role whatsoever with regard to the amount for the regulation of this investment. Incidentally, it cannot be changed will.

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In Pig 5, the circuit diagram according to the system of FIG. 1 is shown in detail. Here, the flow water temperature sensor 23 acts on the control device 25, which in turn controls the drive motor SM of the circulating pump 7 in this variant and adjusts its speed. As a result, according to the pump characteristic (Pig. 8) _5, the pressure difference Δ ρ that prevails in the lines 24 and 26 and by which the actuator 16 is adjusted accordingly changes. This regulates the proportions of the hot water coming from the boiler flow line 3 and the colder return water flowing in from the return line 13 via the bypass line 15 Normal speed n _Q to n- ^ , or ng, the operating point O changes to 0- or Oq because in the sense of the resistance _{parabola W Q of} the entire heating system with a larger flow rate Qx there is a correspondingly larger pressure drop -'- ρχ, the analogous considerations apply for the operating point O ₂ »

The purpose of this regulation is to change the control variable of the mixing valve by changing the value of ^ - \ ρ l6 and thus the ratio of the quantities of hot water to change to recirculated water- This creates oil

change according to pump characteristics _v

the total flow rate Q, as shown in Fig. 8

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is visible. This change in i-length has a positive effect in the sense that it supports the initiated control process. If, for example, the flow water quantity is to be increased with a corresponding throttling of the added return water quantity and if the speed n _{Q is increased} to n, then in addition to the change in the mixing ratio in the sense of increasing temperature of the flow water, a change in the total flow quantity Q is simultaneously associated by increasing it from the value Qo to the value Q-. An analogous behavior occurs ₃ if the temperature in the heating system is to be reduced. The process is favored here in terms of control technology, in that not only does the mixing temperature drop, but at the same time the throughput rate decreases from Q_ to Q-.

In principle, however, it is also possible, for example by means of a bypass line 110 bridging the pump 7 and a control valve 111 which is actuated by the controller 25, in the sense of the dash-dotted lines in FIG. 5, to bring about a control at a constant speed (n * constant). In the sense of the parallel connection, the total resistance W decreases and _{the total flow rate Q increases accordingly along the curve for n Q} while ^ p decreases «Despite the increased total flow rate of the pump, a smaller amount of water flows through the heating system, since a part is continuously withdrawn after the pump And it is fed back to the pump suction side via the bypass line 110, with which, as far as the heating side is concerned, this side

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Regulation the same can be achieved as with a speed control according to lower speeds n ₂ «The bypass control is bought with a poor degree of efficiency, since the total circulation rate increases and consequently the power consumption of the pump increases, despite the lower amount of water pumped through the heating system.

In Fig. 6 a circuit according to the invention is shown in which the speed of the circulating pump 7 is constant. A throttle 114 in the form of a flap or a regulating valve is installed in the supply line 9, the position of which is influenced by the flow water temperature sensor 23 via the control device 25. By installing such a throttle 114, the total resistance W of the heating system is made variable, which is expressed in the position of the resistance parabolas, for example according to FIG Represents the total resistance of the system with strong throttling. By regulating the throttle 114 accordingly, the differential pressure Aj> generated by the pump 7 and used to regulate the mixing valve 116 is changed. In this case, the entire circuit can be provided in such a way that the total flow rate, which changes as a result, changes in the sense of the desired change, that is, in such a way that the total flow rate increases with increased heat supply to the consumer

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by opening the throttle Il4, the mixing valve increases Opening the boiler flow line 3 and the return flow line 15 ultimately influenced.

It can be seen from this that the adaptation of a heating system to the overall flow system is advantageously carried out with a speed control of the pump or with the aid of a throttle device in the sense of FIGS. 5 and 6. The idea of the invention can also be implemented in the sense that the pressure difference acting on the return admixing device, generated by the circulation pump, is controlled, e.g. continuously controllable, by means of a throttle valve 118 in a connection line 119 between the pressure extraction lines 24 and 26. This means that part of the pressure difference of the circulating pump rotating at a constant speed is used for regulation. The dimensioning of the lines 2 ¹ I-, 26 and 119 is important. Between the valve II8 and the line 9 a throttle 120 is installed and the line II9 is provided with a large flow cross-section opposite the lines 24 and 26. When valve II8 is closed, the full differential pressure prevails at the actuator l6 (without a flow prevailing in these two lines 24 and 26). By opening the valve 118, the two lines 24 and 26 are short-circuited via the line II9 in the sense that the pressure difference

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receiver, e.g. the membrane 27, only a small im In extreme cases, no pressure difference can build up in everyone However, if the amount of water flowing through the line 119 is much less than that produced by the pump 7 isfe so small, even with fully open valve 118, that the delivery rate and the pressure difference at the pump 7 - -, practically not be changed. .

The subject of the invention brings eo ipso ei »e another \ Simplification of the electrical installation with itself: =.

The usual practice when parked heating the _{circulation:;} To switch off the pump, an additional switch or a contact in the device for the program selection and its electrical connection line to the circulating pump is required for an automatic system, In the case of the control system described, the circulating pump is switched off to switch off the heating, the pump pressure is - zero, the valve in the boiler flow closes and the one in the bypass opens. "'■" ■ ' -

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Claims (14)

Patent a. claims 1) j Procedure for regulating those working with liquid heat transfer media Heating systems with at least one circulation pump in the heat carrier circulation system as well as a device for admixing backflowing, cooled liquid into the forward flow, to achieve and maintain a controlled variable, in particular the advance or clearing equipment, the adjustment the return admixture with the help of a through the Circulation pump generated pressure difference takes place, characterized in that at least part of this pressure difference changed in the sense of a control effect. 2) Method according to claim 1, characterized in that one the circulation pump speed changes. 3) Process according to claims 1 and 2, characterized in that a temperature controller is primarily set to the pressure difference influencing device, e.g. on the speed of the circulation pump, can act to the return admixture to change the mixing ratio and that a secondary intervention is made on the circulating quantity, the whole thing in such a way that with increased heat demand in the flow stream both the temperature and the amount of circulation is increased. "19'- 909886/0995 4) Method according to claim. 1, characterized in that one the pressure difference wholly or partially by means of controlled bypasses (110, 111) of the circulation pump (7), by means of controlled throttles (114) of the supply line (9) or by means of a controlled short. "close (118, 119) the differential pressure line leading to the control element (16) (24, 26) designed to be changeable. . 5) The method according to claim 4, characterized in that the control of the short-circuit line (119) by means of a steady controllable solenoid valve (118) takes place. 6) heating system for performing the method according to claim 1, in which between the heat dispenser and the confluence of the bypass line in the flow on the one hand and in the bypass line on the other hand, a pressure-difference-controlled volume regulating element arranged to generate a predetermined flow mixing temperature eft is characterized by a control device (25) controlling the means for changing the pressure difference. · " 7) Heating system according to claim 6, characterized in that the control device (25) in the supply network for the circulation pump drive is arranged and controls this supply. 8) Heating system according to claim 6, characterized in that at least one volume regulating element is static during operation 9 0 9 8 8 6/099 5 - 20 - BAD OR! Gjj \! _AL and / or is dynamically relieved of pressure. 9) heating system according to claim 6, characterized in that that two rigidly or elastically connected volume regulating organs are provided. 10) Heating system according to claim 6, characterized by a float controlling the volume regulating elements. 11) Heating system according to claim 6, characterized in that return means, e.g. a pneumatic or hydraulic Element for which the volume regulator is intended. 12) Heating system according to claim 6, characterized in that the volume regulating organs in a common housing are preferably arranged together with the circulation pump. 13) Heating system according to claim 6, characterized in that the Wärraeferäger-MengenregBlmng in the flow and in the bypass takes place by means of a single control member (16). 14) Heating system according to claim 6, characterized in that to adapt the circulation pump to the heating system adjustable throttle is provided. - 21 - 9 0 9 886/0995 ^BA0 ORi 15-) heating system according to claim 6, characterized gekennzelehnet that the control device (25) a flow control element fill) a bypass line (HO) bridging the circulation pump (7) or a throttle element (ll4) in the supply line ($}} od & v the flow of a die Pressure lines (24,26) short-circuiting controllable connecting line (119) controls. IfS. ) Heating system according to claim 15, characterized in that that a throttle point (120) with a variable cross-section, for example, is arranged upstream of the solenoid valve (118) in the direction of flow is. - 22 - 909886/099 5