EP3870905A1

EP3870905A1 - The present invention relates to a district heating system and methods for flow control and retrofitting of a flow regulation system in a district heating system

Info

Publication number: EP3870905A1
Application number: EP19812912.4A
Authority: EP
Inventors: Alex RØRBÆK
Original assignee: Frese AS
Current assignee: Frese AS
Priority date: 2018-10-23
Filing date: 2019-10-23
Publication date: 2021-09-01
Also published as: DK180868B1; WO2020083453A1; DK201870692A1

Abstract

District heating system, comprising a bypass situated between the inlet line and the return line from the heat exchanger and a flow valve situated in the bypass, wherein the flow valve is a flow control valve, which forms part of a flow regulation system of the district heating system, and wherein the flow regulation system comprises a first temperature sensor situated for measuring a temperature in the bypass, an electronic controller unit and a battery connected with the controller unit to power the operation of the controller unit, wherein the controller unit comprises means for wireless communication with a communication unit, wherefrom the controller unit can receive data and thereby be remote-controlled from the communication unit and can transmit data for remote logging to the communication unit, and wherein the controller unit is adapted as a slave unit, which is programmable for periodically after a first programmed time interval to prompt a command from the communication unit, which correspondingly can be adapted as a master unit, and for periodically after a second programmed time interval to transmit data to the communication unit. Methods for flow regulation and retrofitting of such a flow regulation system in a district heating system.

Description

The present invention relates to a district heating system and methods for flow control and retrofitting of a flow regulation system in a district heating system.

The invention relates to a district heating system, comprising a heat exchanger for transmission of thermal energy between a supply side and a user side of the district heating system, an inlet line towards and a return line on the supply side of the heat exchanger, a bypass situated between the inlet line and the return line from the heat exchanger and a flow valve situated in the by-pass.

In existing district heating systems, a fluid is heated, most often a liquid, but it can also be e.g. steam, typically water, in a central plant or facility e.g. a com- bined heat and power plant. The heated water is distributed via strings in the supply system for the users, who consume the heat via a heat exchanger to supply the users decentralized, internal circulation i.e. the consumer system. The consumer system can e.g. for one family housing be a simple system with few internal strings, or it can be a central heating facility, which usually form part of larger buildings and multi-storey buildings, and which can comprise a larger amount of strings. Often are both water for domestic use and the water, which circulates in the internal heating system, heated e.g. for heat supply of radiators in the building.

The distribution, in the district heating system, takes place in strings, where a significant heat loss occurs at the heat transport between the plant and the heat exchanger at the user. The heat loss occurs i.a. as a function of temperature of said inlet fluid, i.e. the inlet heat temperature, as a higher temperature result in a higher heat loss. The plant is typically oblique to deliver a certain minimum temperature at the inlet to the heat exchanger at the user, and at optimal con- ditions, i.a. the situation with the lowest possible heat loss, would be where the inlet temperature is equal to or a bit above the minimum temperature.

The heat exchanger at the user is typically a part of a heat interface unit (HIU), which establish the interface between the district heating grid and the heating system internally at the user. The heat exchanger transfers heat from the district heat system to the heating system on the user side, i.a. the consumer system. The HIU is usually situated on the user side, e.g. in an in- stallation cabinet in the user building, why the district heat plant usually does not have immediate access to the HIU. In particular at users, remote from the plant, i.a. where the string to the user is long, or where the user is close to or at the end of a string, is a by-pass often situated in the district heating system between the inlet line and the return line from the heat exchanger. The by-pass provides a flow path between the inlet line and the return line, whereby circulation of the district heat fluid even at the most remote users is ensured. Especially in the summer periods, where the heat is not used for room heating, but solely for heated domestic use water, can the user’s consumption be so limited, that the usage circulation cannot maintain a demanded minimum temperature of the district heating fluid at the heat exchanger. The by-pass can thereby help ensure a certain minimum tem- perature, e.g. 60 degrees Celsius, at remote users of the district heating sys- tem, even in periods with low consumption. The by-pass can be situated as part of the HIU and can be situated at the user, i.a. it can also be difficult to access for the district heating plant. In other cases, the by-pass is situated out- side the user side, e.g. in a well in the road.

Often is a by-pass retrofitted based on a complaint from a user related to, in particular, that the heated domestic use water is experienced to be having a to low temperature, but a by-pass can also be installed in relation to the estab- lishment of a string, especially if it is expected, that problems related to the inlet temperature can occur.

A static flow valve can be situated in the by-pass, whereby it is possible to manually regulate the flow in the by-pass and thereby the circulation to en- sure a suitable fluid temperature at the user. It is not typical to take measure- ments of the inlet temperature at the user presently, and therefore can it be difficult to ensure a suitable temperature, especially with the seasonal varia- tions. Since it is troublesome and expensive to manually adjust the static flow valve, it will often be adjusted, such that, even in the worst possible scenario (typical a hot summer day) it can still be expected that a sufficiently high inlet temperature is delivered at the user. This can imply, that the district heating system via the static flow valve often is statically over-dimensioned for the inlet temperature and moreover is not adjusted or regulated according to the de- mand. The inlet temperature at the heat exchanger will therefore, particularly in the summer period often be way above the required minimum temperature. There will in the winter period, at most, be no need for the by-pass, but the by- pass will nonetheless still be in function.

In principal, can the static flow valve situated in the by-pass, with potentially other by-passes and respectively static valves, be regulated according to the demanded minimum temperature. However, it can be troublesome and difficult to acquire an effective and efficient regulation therethrough, in particular be- cause the valve has to be adjusted manually and can be difficult to access, hereunder be placed at the user side, and it is therefore presently often corn- plicated for the supplying companies to both ensure a demanded minimum temperature at the inlet and to ensure, that the temperature is not too high. Often is the valve only adjusted at the retrofitting of the by-pass or at the fitting of a new district heating string and in such a way, that the supplying company ensures a minimum temperature regardless of variation in the demand, i.a. it often results in an over-dimensioned heating supply at the user.

In existing district heating systems there is therefore often a significant thermal energy waste in relation to said by-pass.

Approximately 64 % or approximately 1 .7 mil. of Danish households are supplied with district heating, and there is more than 60,000 km line in the Danish district heating grid. Thereby, there is already today a considerable amount of said by-passes.

An object of the invention is, with offset herein, to improve the energy- efficiency of a district heating plant as noted in the introduction.

CN 104848294 A describes a district heating system comprising a heat exchanger with a supply side and a consumer side; an inlet line and a return line on the supply side from the heat exchanger; a by-pass situated between the inlet line and the return line; a flow valve situated at the by-pass; where the flow valve is a three-way temperature controlled valve; a control cabinet wired with i.a. the flow valve and a temperature sensor on the consumer side; and a directly connected heating area connected on the return line for a better utili- zation of the excess heat in the return line.

According to the invention, the abovementioned and/or other objects in a first aspect of the invention can be met with a district heating system according to the introduction above, where the flow valve is characterized by, being a flow control valve, which forms part of a flow regulation system of a district heating system,

wherein the flow regulation system comprises:

- a first temperature sensor situated to measure a temperature in the bypass;

- an electronic controller unit;

- a battery connected with the controlling unit for powering the op- eration of the controller unit;

- wherein the controller unit can receive measured temperature data from the temperature sensor and can adjust an opening de- gree of the flow control valve;

wherein the controller unit comprises means for wireless communica- tion with a communication unit, whereby the controller unit can receive data from and thereby be remote-controlled from the communication unit and can transmit data for remote-logging to the communication unit; and

wherein the controller unit is adapted as a slave unit, which is pro- grammed for periodically after a first programmed time interval to prompt a command from the communication unit, which correspondingly can be adapted as a master unit, and for periodically after a second programmed time interval to transmit data to the communication unit.

Thereby, with the invention, is a district heating system with a bypass provided, wherein it is possible to operate the flow control valve automatically and dy- namically. This means, that it is possible to control the valve and thereby the flow through the by-pass as needed, i.e. in such a way that a temperature equal to or a bit over the demanded minimum temperature is maintained. The con- troller unit will operate the valve to a greater opening degree if the temperature is to low, whereafter the inlet temperature will increase. The controller unit will operate the valve to a smaller opening degree if the temperature is to high, whereafter the inlet temperature will decrease. The temperature can thus, be measured continuously or periodically after defined time intervals, in such a way that it will be possible to ongoingly adjust the valve and thereby the inlet temperature. The controller unit can be configured such that it performs a dy- namic regulation of the flow through the by-pass as a function of the tempera- ture measured in the by-pass.

The inventor of the present invention has realised, that regulation sys- tems with such a controller unit and a flow control valve in general is too power consuming and thus most be expected to be wired to an existing power supply, usually from the user, which can be troublesome and furthermore can imply, that the supplier does not have complete control over the operation of the sys- tem, as the power for the system can be short-circuited.

Thus, it has been realized, that there through the invention can be pro- vided a battery-powered system, that can be remotely-controlled, and that with a suitable degree of operation and with the current battery technology (e.g. four lithium AA-batteries, ER14505) can be functional for up to five years or more, before the battery needs to be replaced. It has moreover been realised, that the installation of a system according to the invention can result in savings, which often and for many existing by-passes, will have a quite short repayment period due to great savings on the heat loss on the supplier side.

A low power consumption can be achieved by; the controller unit being adapted as a slave unit, which can be programmed to periodically after a first pro- grammed time interval to prompt a command from the communication unit, which correspondingly is adapted as a master unit, and to periodically after a second programmed time interval to transmit data to the communication unit.

Thereby, the communication unit’s means for wireless communication, which otherwise normally, e.g. in a WIFI-network, will have a relatively high- power consumption, can be hibernating, when it does not transmit or receive data. The power consumption will therefore by a fraction of the consumption in a system, where these means always are active. Thus, it has also been real- ized, that periodic communication with relatively long time periods in-between beneficially can be utilized in the system according to the invention.

The district heating system can according to the invention and in particular, the flow regulation system be situated at the end of a district heat string. The district heating system can moreover include more strings and also the district heating plant, wherefrom the heated fluid is delivered.

In the interval between the prompts for a command i.e. the transmission of data can the controller unit’s means for wireless communication thus be passive or off and can thereby have a power consumption near or at zero. Thereby can the means for wireless communication be adapted such, that it is not possible to“wake” the controller unit through the help of communication from the com- munication unit, i.a. so-called push-commands are not possible.

As the controller unit does not need to be wired to an external power source, e.g. a power circuit at the user, the district heating plant can be ensured full control over the operation of the system.

With the district heating system according to the invention is a dynamic or pe- riodic operation of the flow in the by-pass through the use of a flow control valve possible. The controller unit moreover makes wireless control of the controller unit possible, whereby it is possible to adjust the controller unit to operate the flow in the by-pass e.g. based on a user profile, which the controller unit can be supplied with via the communication unit, and which can be stored in a memory of the controller unit. The periodic transmission and reception of data from the controller unit entail, that the power consumption for operation of the means for wireless control can be kept very low. The controller unit can more- over be adapted to communicate data to the communication unit, which can trigger an alarm following a deviation profile, that can be a part of the used user profile. Deviations can, in particular, be in relation to relevant measurements of pressure and temperature by sensors placed relevant places in the system. Potentially can the communication unit or the cloud (see more below) be adapted to forward an alarm to another communication unit, e.g. in shape of a text sent to a mobile phone.

Through the use of such means for wireless communication, such great sav- ings in the means’ power consumption can be provided, that it is possible to acquire a district heating system according to the invention, where in praxis it can be operated cheaply and efficiently with a regular battery or battery system of a limited capacity, and which is easy to replace, e.g. two or four AA-batteries. Calculations show, that the replacement of four AA-batteries, which forms the battery for the controller unit, thereby can be expected to last for at least five years, which is recognized as being more than acceptable for the supply com- panies. It can be an advantage to replace the batteries at regular maintenance.

Thereby can a practical applicable district heating system be achieved with the invention, with which the heat loss in relation with the by-pass in the district heating systems is reduced, as the flow through the by-pass can be regulated following a demand by the circumstances. Moreover, can it reduce the power consumption of a pump, as the pump effect usually would be reduced, when the flow control valve according to the circumstances are adjusted to a lower flow rate through the by-pass. A lower flow through the by-pass can also result in less wear on both pump and line systems on the supplier side, as the aver- age pump pressure can be reduced accordingly.

The flow regulation system can further comprise an actuator, which is con- nected with or fitted to the flow control valve to provide the change of opening degree of the flow control valve and thereby the flow through the valve and thereby the by-pass. The actuator can have a stroke length, as a stroke length of a flow control valve can be adapted to the actuator stroke length.

The actuator’s motor can with advantage be powered by the same battery as the controller unit, as there for this purpose can be provided a current-carrying connection between the battery and the actuator. Upon use of an actuator and a valve with a relatively short stroke length, it has been calculated, that a battery comprising four AA-batteries still can provide the capacity to power both the actuator and the controller unit for more than five years in most cases and in some cases for up to ten years or more. This is applicable for a reception inter- val for the controller unit of 6 hours and a transmission interval of 15 minutes, as these examples of or similar intervals are evaluated suitable for the purpose.

The life span of the batteries depends on the chosen user profile, which influ- ences, how often the actuator shall be activated. In an example of a user profile will the controller unit be programmed such, that the actuator can close the flow control valve in relation to shifts between summer and winter and only opens at the shift between winter and summer. Even with such a simple user profile a considerable amount of both thermal energy and pump energy can be saved.

Alternatively, the actuator can be powered by a separate battery, where the battery in the last-mentioned example can be placed at, in, or form part of the actuator. This can be a disadvantage, as the battery for the actuator thus would have to be replaced separately, and for some cases the flow control valve would be situated difficult accessible, e.g. in a well. On the contrary, the con- troller unit or the box with the controller unit can often be situated easier acces- sible, e.g. in an installation cabinet at the user, and the battery would therefore be easier to replace.

The controller unit can be adapted to potentially to periodically measure the life span of the battery, e.g. by measuring the capacity or the voltage, and if desired to transmit this information for the communication unit, whereby it is possible to alert the communication about the need of a battery replacement well in ad- vance, if necessary.

The controller unit can also be adjusted for adjusting the flow control valve in a prefixed adjustment, i.a. with a prefixed opening area, e.g. fully opened, when the battery life span is measured to be close to zero, where upon flow in the by-pass can be present, and a demanded minimum temperature in the inlet can be ensured, even when the battery is out of power.

The flow regulation system can also be adapted such, that the battery supplies other parts of the system with power, among these e.g. the temperature sensor and/or one or more other sensors.

The communication unit can e.g. be a PC, a smart-phone or a tablet computer, which can have an internet connection for connecting with the cloud, as the controller unit is adapted to connect with the cloud, cf. also more about the connection with the cloud below. It is preferred regardless of the circumstances, that the controller unit can be accessed via an electronic interface (e.g. web, app or API), wherein a code can be attached to the system, in particular on or at the controller unit, where the communication unit with the code can identify the system and/or in cases of retrofitting of the system can suggest a place for fitting of the system. Further, it is preferred, that there, potentially via the inter- face, can be encoded an alarm threshold value in the flow regulation system, in the communication unit, or in the cloud for one or more of the values meas- ured with one or more of the sensors in the system, and wherein an alarm can be communicated to the communication unit, when an alarm threshold has been reached.

The flow regulation system can further comprise a first pressure sensor situated for measuring of a system pressure, as the first pressure sensor is connected with the controller unit, such that the controller unit can register the system pressure. The system pressure is the system pressure on the supplier side. The first pressure sensor can with advantage be situated in the outgoing part or the return line from the flow control valve, but can alternatively be situated elsewhere, where the pressure represents the system pressure. Hereby, it can be made possible to identify a line rupture, which usually shows at relatively large pressure drop in the system pressure. Often does a suitable flow control valve comprise an access to measure the outgoing pressure in the valve itself, e.g. in the shape of a PT-port, and the first pressure sensor can with ad- vantages be a PT-plug inserted hereto. The measurement of temperature via the first temperature sensor can correspondingly take place here, as the tem- perature sensor can be a part of the PT-plug.

The temperature sensor can furthermore be fitted in the inlet to or the return from the heat exchanger, and the data from the measurements can be trans- ferred to the controller unit, whereby the temperature drop over the heat ex- changer can be monitored, and the system can be adjusted to reach an optimal or improved (typically higher) temperature drop over the heat exchanger, whereby further thermal energy can be saved. The sensor in the inlet can be the same sensor as the first temperature sensor, as the temperature in the by- pass usually would be close to identical to the temperature in the inlet for the heat exchanger.

The flow regulation system can further comprise pressure sensors situ- ated for measurement of a differential pressure over the flow control valve, these pressure sensors being connected with the controller unit, such that the controller unit can register the differential pressure and communicate this to the communication unit, whereafter the pump pressure, via the data from the com- munication unit can be used to adjust the pump pressure to a necessary mini- mum level on the supplier side. Hereby can a further reduction of used pump energy and pump wear be reached.

One or more or all said sensors in the district heating system are preferably digital and passive, when not measuring, whereby the battery lifespan can be extended further.

The controller unit can preferably via the communication unit be coded or ad- justed with a suitable or adapted user profile, which can be chosen automati- cally or manually depending on the circumstances. A profile can e.g. be sea- sonally operated for instance by summer/winter operation or can be daily op- erated, as it e.g. takes capacity limitations or similar into account, which can vary during a day.

One or more of the components in the flow regulation system and in particular the controller unit can be situated in a control box, and there can be one or more outtakes from the box to the flow control valve, sensors, battery pack, etc. The battery can alternatively be situated inside the box. The box can be provided with a display or a screen, where it can be possible to show e.g. one or more measurements from one or more sensors of the flow regulation system, and where it can be possible to adjust the controller unit. The box can make up a part of the HUI at the user and can be situated in an installation cabinet or something similar. The by-pass and/or the flow control valve can also be situated as part of the HUI or can, in particular, be situated in the by-pass e.g. in the road. The connection or the connections between the controller unit and the actuator for transferring the measured data and/or to adjust the actua- tor from the flow regulation unit can be in the shape of wires and/or can be wireless. In the last case, the flow regulation valve and/or one or more of the sensors can be powered by separate batteries and can comprise means for transmitting and receiving data wirelessly e.g. following the same intervals as in the corresponding means in the controller unit, for wireless communication with the communication unit, where these corresponding means then also can communicate with the flow control valve and/or one or more of the sensors. The flow regulation system can be retrofitted in an existing district heating sys- tem, as a static flow valve in such cases can be replaced with the flow regula- tion system.

The battery can be a lithium battery, can comprise one or more cells and can have a voltage of less than 10, 8 ,6, 5, or 4 V, such as a 3.6V USOCI2 battery. Calculations shows, that such a battery can lose less than 1 % of its capacity each year over a period of 10 years with one sensor fitted. By controlling, using one of the user profiles, the battery lifespan can be shortened, but with the user profiles, which are deemed relevant, a battery lifespan of over 5 years can be anticipated with a system according to the invention, where both the controller unit, sensors, and the actuator are supplied with power from the battery, and where the battery comprises 4 AA-batteries. The individual batteries in the bat- tery can be joint in the battery pack with a plug that is connected to the control box, or the batteries can be situated in the control box.

One or more sensors can in general be fitted in the integrated ports in the valve, e.g. can the valve comprise one or two so called PT-ports (pres- sure/temperature ports), wherein one or respective PT-plugs (pressure/temper- ature plugs) are placed.

The flow control valve can be of the type PICV (pressure independent control valve), in particular where the valve comprises an automatic and/or dynamic regulation of a differential pressure over the flow control valve, e.g. a valve as described in the applicants WO/2006/136158 A1 , in particular Frese ® Optima ® valve, or in WO 2009/135490 A2, in particular a Frese® Optima Compact® valve. The valve can be modified, such that it has a shorter stroke length.

In principal, the flow regulation system in an embodiment for the flow regulation system according to the first aspect of the invention, where a such embodiment is outside the scope of the present invention defined in the current patent claims, can be embodied without the feature, that the controller unit comprise means for wireless communication with the communication unit, whereby the controller unit can receive data from and thereby be remotely controlled from the communication unit and can transmit data for remote logging to the com- munication unit, and/or without the feature, that the controller unit us adapted as a slave unit for the communication unit, which correspondingly is adapted as a master unit. For the last mentioned feature, where the controller unit is configured as a slave unit for the communication unit, which correspondingly is configured as a master unit, can the flow regulation system also be without the feature, that the controller unit is programmed to periodically after a first pro- grammable time interval to prompt a command from the communication unit and to periodically following a different programmed time interval to transmit data to the communication unit. Here through can the controller unit as an ex- ample be controlled via a WIFI-network or via a wired connection.

A district heating system can alternatively be called a district heating installation and is, as the expression is used in this application, a system where a fluid is heated or cooled in a central plant of facility, e.g. a combined heat and power plant, and the heated fluid on the supplier side is distributed to several users, who consumes the heat (in cases of heated fluid) or release heat (in cases of cooled fluid) to the heat-supply or the heat-removal of a user system at the user. The fluid on the supplier side will therefore in general be separated from the fluid on the supplier side, as the transfer of thermal energy can take place through the help of a heat exchanger. The term district heating system thereby further comprise district cooling systems, and anywhere where there in this specification is referred to realising heat or similar, shall it be understood, that it can relate to the reception of heat, if a district cooling system is men- tioned.

A heat interface unit{ HIU), as the expression is used in this application, estab- lishes the interface with the user system at the user and typically comprises a heat exchanger, which can transfer heat from the supplier side to the user side.

A by-pass in the district heating system, as the expressions is used in this ap- plication, is situated close to or immediately before the heat exchanger between the inlet line and the return line from the heat exchanger or the HIU and thereby provides a flow path between the inlet line and the return line. A such by-pass can be applied to ensure a certain minimum inlet line temperature at e.g. 60 degrees Celsius for remote users of the district heating system.

A flow control valve is, as the expressions is used in this application, a valve, where with it is possible to automatically or non-manually, typically through the use of an actuator, to regulate a flow through the valve. In contrast to this is a static flow valve a valve, which can be adjusted manually e.g. by turning a con- trol lever.

An actuator, as the expressions is used in this application, is a unit, which corn- prises a motor, which can adjust a valve, i.e. can move a valve element, when the actuator is connected to a valve. An actuator can in usual be connected to a control to drive the motor and thereby control the adjustment of a valve ele- ment of a valve. An actuator can be a linear actuator, which is preferred ac- cording to the present invention, and where the motor can move a valve ele- ment of the valve linearly. Alternative actuators can be used, among these, actuators, where the motor can move a valve element e.g. in a circumferential direction.

The stroke length of a valve or an actuator is, as the expressions is used in this application, the length, the actuator can move a valve element of a valve be- tween two extreme positions, e.g. a fully open and a fully closed position. A short stroke length usually consumes less power for moving the valve between the two extreme positions.

A controller unit, as the expressions is used in this application, is an electronic unit, which can be used for controlling or regulating a flow control valve. The controller unit can comprise a memory, where one or more user profiles poten- tially can be stored. It can further comprise one or more PCBs (printed circuit board) and connections with the single components in the unit. The skilled per- son would know, how a suitable controller unit can be made for the purpose, and the single components such as antennas are available at the open market.

The opening degree or the opening area of a valve, as the expressions is used in this application, defines the size for a flow opening through the valve and is an expression for the flow, which will pass through the valve and thereby the by-pass at a given pump or system pressure.

A sensor, as the expressions is used in this application, can also be described as a detector, can be electronic and can measure e.g. a pressure or a temper- ature of a fluid, such as the flow in the by-pass on the supplier side or in relation to the flow control valve. There can e.g. be referred to a PT-plug, which can measure both temperature and pressure, and which can be used in relation to flow control valves, in particular situated in PT-ports of the valves.

Wireless means for communication, as the expressions is used in this applica- tion, can comprise one or more PCBs, such as network adapters, and one or more antennas, and can allow for electronic, wireless communication with an electronic receiver in the shape of a communication unit.

A battery, as the expressions is used in this application, is an electronic com- ponent, which include stored power and makes power accessible for the appa- ratuses, connected to it, electrically. A battery can comprise several part bat- teries or cells, which can be joint. A battery can alternatively be described as an element. Any suitable battery type can be used as the battery according to the present invention, here within especially electro-chemical batteries, such as lithium or Li-batteries. A battery can be rechargeable.

A slave unit and a master unit, as the expressions are used in this application, are components in the system, which follows the, by the person skilled in the art, known communication model master/slave, i.e. a model, where a master device, e.g. the communication unit, has a one-way control with one or more slave device, e.g. the controller unit. The communication unit in the district heat- ing system can according to the invention, be for control of the controller unit in the district heating system according to the invention only or can be for control of both the controller unit and one or more identical, similar or other units.

In an embodiment of the district heating system according to the invention, a change of the degree of opening of the flow control valve is provided by an actuator motor of an actuator, where the actuator motor is powered by the bat- tery.

See above for a discussion of potential advantages related herewith.

In an embodiment the means for wireless communication are adapted or programmed to receive data in a time window, which opens at a time interval of 1 -120 minutes, 2-60 minutes, 5-30 minutes or 10-20 minutes, e.g. approxi- mately 15 minutes, and/or to send data at a time interval of ½-12 hours, 2-10 hours, 3-9 hours, 4-8 hours or 5-7 hours e.g. approximately 6 hours. The time interval for reception of data can e.g. be 5, 10, 20, 30, or 60 seconds.

In an embodiment the controller unit is adapted for wireless communi- cation with the communication unit via a network of the LPWAN-type.

The network type LPWAN can also be mentioned as a low-power wide-area network, LPWA network, LPN, or low power network and is mainly of the sub-type ultra-narrow band or UNB LPWAN, in particular the Sigfox-net- work, which is widely distributed in great parts of the world, here within Den- mark.

LPWAN is a type of wireless communication network, which is designed for long-range communication at a low bit rate between things or objects, such as sensors, which is powered through the use of a battery. LPWAN differs from wireless WAN, which is designed to transfer large amounts of data between users, which consumes more power. LPWAN’s data rate varies typically be- tween 0.3 kbit/s to 50 kbit/s per channel. LPWAN is preferably supplied by a third party in the present invention i.e. neither by the supply or the user, in par- ticular as or at the Sigfox network.

Other existing UNB LPWAN-types comprises Telensa, Nwave, Weightless and the NbFi protocol. Other LPWAN-types comprises DASH7, LTE-MEC, MySen- sors, NB-loT, RPMA and Taggle Byron.

It has in relation to the present invention been realized, that LPWAN is highly suitable for use in relation to the controller unit’s communication with the com- munication unit, as the low bit rates, the low power consumption, the periodic communication of data and the master/slave-model results in a particular low power consumption in relation to the wireless communication, which allows for realizing a practical useful, battery-powered district heating system according to the invention.

In an embodiment, data from the controller unit to the communication unit and/or commands from the communication unit to the controller unit are pro- vided via a cloud service.

Hereby is a communication point added in shape of the cloud between the communication unit and the controller unit in shape of data collection in“the cloud”. When data is transferred form the controller unit, e.g. via LPWAN, to a data collection in the cloud, the communication unit will, e.g. via the internet, be able to transmit a command to the cloud anytime, and the controller unit can prompt the cloud anytime and (potentially with a delay) receive the command from the cloud. Correspondingly can the controller unit transmit data to the cloud at said time interval, and the communication unit can fetch the data on a potentially later suitable point in time, when the communication unit establish connection to the cloud.

In an embodiment, the actuator remains substantially in the same position, when applied no voltage.

Hereby can it be accomplished, that the actuator needs to be supplied with a minimal amount of power over time, as the actuator’s power consumption can be near or at zero, when the actuator is not operating for adjusting the flow control valve. Hereby can the said embodiment also be possible, where the actuator also is powered by the battery in the system, as a life span of over five years for the battery can be reached.

This can e.g. be made possible through the use of a three-way actuator, which is an actuator, that is moved by volt over time, i.e. if the actuator is supplied power in e.g. 20 seconds, the actuator moves as an example 1 .3 mm and re- main in this position without consuming power. In contrast, a 0-10 V modular actuator e.g. always has a control voltage of e.g. 4.3 V to control the actuator adjustment in relation to the stroke length of the valve.

In an embodiment, the stroke length of the valve and/or the actuator is less than 10, 5, 4, or 3 mm, e.g. 2.5 mm.

In relation to the invention it has been realized, that such a small stroke length of the valve/actuator can be used, as precise adjusting of the flow regulation system, in usual, will not be a demand at normal system operation. The smaller stroke length can thus lead to, that the actuator’s motor consumes less power when adjusting the valve, which again can prolong the battery life span, in the case where the actuator is powered by the battery.

In an embodiment the district heating system further comprises a sec- ond flow control valve fitted in the inlet line towards or the return line from a heat exchanger between a supplier side and a user side of the district heater system, wherein the second flow control valve is linked with the controller unit of the flow regulation system or a second electronic controller unit, wherein the controller unit of the second flow control valve can adjust a degree of opening of the second flow control valve and comprises means for wireless communi- cation with a communication unit, potentially the same communication unit as for the controller unit of the flow regulation system, whereby the controller unit for the second flow control valve can receive data from and thereby be remote- controlled from the communication unit.

Thus, it can be possible via the communication unit wirelessly and remotely to shut off the heat at a user, e.g. in relation to missing payments. Today it is often such, that the plant must have access to the property of the user to shut off the heat, which can be related to inconvenience and great costs, here within espe- cially in cases, where it is necessary to involve the authorities.

The second flow control valve and the associated controller unit can be a part of the flow regulation system, which is identical with or corresponds to the flow regulation system with the first flow control valve. Hereby can the same type of the flow regulation system be used for both purposes. This second flow regu- lation system can comprise one or more of the options for the first flow regula- tion system described above, just as one or more of the components within can be used in both flow regulation systems.

The second flow control valve and the associated controller unit can thereby correspondingly be retrofitted or fitted in relation to the installation of a new system.

The second flow control valve and the associated controller unit can each be according to any of said embodiments for the first flow control valve and its connected controller unit. Thus, can the second flow control valve e.g. be con- nected with an actuator that can be situated and adapted as explained above in relation to the first flow control valve.

The controller unit associated with the second flow control valve can be connected with a temperature sensor situated in the inlet line for the heat exchanger and/or a temperature sensor situated in the return line from the heat exchanger. The controller unit associated with the second flow control valve can through the use of the temperature data from these two temperature sen- sors be adapted to adjust the second flow control valve on the basis of the difference between the measured temperatures potentially compared to a cool- ing profile stored in the memory of the controller unit associated with the second flow control valve. Hereby can a suitable cooling of the district heating fluid be achieved, whereby even more thermal energy can be saved.

One or both sensors can further com prise pressure measurements and can be PT-plugs, and the controller unit associated with the second flow control valve can potentially be adapted to receive pressure measurement from one or both pressure sensors.

The controller unit associated with the second flow control valve can be adapted to monitor the pressure measurement from a pressure sensor sit- uated in the return line from the heat exchanger and can moreover be adapted to register quick and/or great drops of pressure in the return line, which corre- sponds to the system pressure in the district heating system, and potentially transmit an alarm to the communication unit. Hereby can line fractures in the system be discovered rapidly.

Alternatively, or in supplement can the system pressure be measured and/or monitored via a pressure sensor in the return line from the first flow control valve, potentially via a sensor in the valve itself, e.g. a PT-plug.

In another invention outside the scope of the present invention, can the present embodiment (that is the embodiment described right above, comprising the second control valve) in one or more of the abovementioned alternatives be embodied as part of a district heating system according to the invention, but which is embodied without the flow regulation system.

Another aspect of the invention involves a method for flow control of a flow regulation system according to any of the preceding claims, wherein the method comprises the steps of:

providing a flow regulation system according to any of the preceding claims,

a temperature sensor communicating a temperature measurement to the controller unit, and

the controller unit automatically adjusting the flow control valve based on the temperature measurement.

The controller unit’s adjustment of the flow control valve can be based on a user profile, which is stored in the memory of the controller unit, and which the controller unit can be provided with from the communication unit.

The controller unit’s adjustment of the flow control valve can be based on a signal transmitted from the controller unit to an actuator of the flow control valve, potentially via a wire.

In an embodiment of this method for flow control of a district heating system according to the embodiment above, where a second flow control valve is fitted in the inlet line towards and the return line from a heat exchanger between a supplier side and a user side of a district heating system, where the second flow control valve is connected to the controller unit of the flow regulation sys- tem or a second electronic controller unit, where the controller unit for the sec- ond flow control valve can adjust an opening degree of the second flow control valve and comprises means for wireless communication with a communication unit, potentially the same communication unit as the controller unit of the flow regulation system, whereby the controller unit for the second flow control valve can receive data from and thereby be remotely-controlled from the communi- cation unit, the method comprises, that the controller unit associated with the second flow control valve is adapted to monitor the pressure measurement from the pressure sensor situated in the return line from the heat exchanger and for registering drop in pressure in the return line, which corresponds to the system pressure in the district heating system, and potentially transmit data to the communication unit, which can trigger an alarm.

In a third aspect the invention involves a method for retrofitting of a flow regu- lation system in a district heating system, wherein said method comprises the steps of:

providing an existing district heating system, which comprises - a heat exchanger for transmission of thermal energy between a supply side and a user side of the district heating system;

- an inlet line towards and a return line on the supply side of the heat exchanger;

- a bypass situated between the inlet line and the return line from the heat exchanger; and

- a static valve situated in the bypass

where the method is characterized by further comprising the steps of: dismounting the static valve and

retrofitting a flow regulation system as a replacement for the static valve, wherein the flow regulation system comprises

- a flow control valve, which forms a part of a flow regulation sys- tem of the district heating system;

- a first temperature sensor, situated to measure a temperature in the bypass;

- an electronic controller unit, which can receive measured temper- ature data from the temperature sensor and can adjust an open- ing degree of the flow control valve, wherein the controller unit comprises means for wireless communication with a communica- tion unit, wherefrom the controller unit can receive data and thereby be remote-controlled from the communication unit and can transmit data for remote-logging to the communication unit, and wherein the controller unit is adapted as a slave unit, which is programmed for periodically after a first programmed time in- terval to prompt a command from the communication unit, which correspondingly can be adapted as a master unit, and for period- ically after a second programmed time interval to transmit data to the communication unit; and

- a battery connected with the controlling unit powering the opera- tion the controller unit,

- so that the controlling unit can adjust the opening degree of the flow control valve for controlling a flow through the bypass. The flow regulation system established with this method can be according to any of abovementioned embodiments for the flow regulation system according to the invention

A detailed embodiment of the invention will in the following be described in detail with references to the drawing, on which:

Fig. 1 depicts a flow diagram for a known district heating system, and

Fig 2 depicts a corresponding flow diagram, which is modified to an embodiment of the district heating system according to the present invention.

Fig. 1 depicts a flow diagram for a known district heating system. Only one end of a single string is depicted, and before the depicted string end, there are more strings, as pump 1 is connected to several or all of these strings.

The district heating system in fig. 1 comprises a heat exchanger (not depicted) situated in a HU I 2 for transmission of thermal energy between a supplier side (to the left of HU I 2) and a user side (not depicted, but to the right of HU I 2) of the district heating system, an inlet line 3 towards and return line 4 on the supplier side from H IU 2, a by-pass 5 situated between the inlet line 3 and the return line 4 from the H IU 2, and a flow valve 6 situated in the by-pass 5.

When operating, the water is heated at a central combined heat and power plant (not depicted) which comprises the pump 1. The heated water is distrib- uted via strings (not depicted) in the supplier system to the depicted end string, which consumes the heat via the heat exchanger in H IU 2 for supply of the users decentralized, internal circulation, i.a. the user system, which is situated at the right of the H IU in the figure.

The heat exchanger is a part of HIU 2, which thus establishes the interface between the district heat grid and the internal heating system at the user. The heat exchanger transfers the heat from the district heating system to the heat- ing system on the user side, i.e. the user system. The HIU is situated on the user side, e.g. in an installation cabinet in an installation room in the user build- ing.

The by-pass 5 provides a flow path between the inlet line 3 and the return line 4, whereby circulation of the district heat water in proximity to H IU2 is secured. The by-pass is used to secure a minimum temperature at e.g. 60 degrees Cel- sius at the user, even in periods with low consumption. The by-pass is in this situation not situated as part of the HIU but outside the user side, e.g. in a well in the road.

As mentioned, a static flow valve 6 is situated in the by-pass, whereby it is possible to manually regulate the flow in the by-pass and thereby the circulation for ensuring a suitable fluid temperature at the user. The inlet temperature at the user is not measured on a regular basis, and the valve is adjusted, such that even in the worst possible scenario (typically a warm summer day), it can still be expected to deliver a sufficiently high inlet temperature at the user.

The by-pass 5 comprises an inlet 7 towards and a return line 8 from the valve

6.

The district heating system in fig. 1 further comprises a second static valve 9 in the inlet 3, more specific in the part 3a between the inlet line 7 for the by-pass 5 and HIU 2 as well as a third static valve 10 in the return line 4, more specific in the part 4a between HIU 2 and the return line 8 from the by-pass 5. Hereby it is possible to manually adjust or close the flow in respectively the inlet line 3a and the return line 4a from the heat exchanger in HIU 2.

Fig. 2 depicts a corresponding flow diagram, which is modified into an embod- iment of the district heating system according to the present invention. The same reference numbers as in fig. 1 are used in fig. 2 for corresponding ele- ments.

In fig. 2 the static valve 6 in fig 1 is replaced with a flow regulation system 1 1 to provide a district heating system according to the invention. The flow regulation system 1 1 is thus fitted with an approach for the method accord- ing to the third aspect of the invention, as the static valve 6 in fig. 1 first have been demounted and the retrofitting of the flow regulation system replaces the static valve 6.

The flow regulation system 11 comprises a flow control valve 12, two tempera- ture and pressure sensors in the shape of PT-plugs at 13, 14 inserted in the valve 1 1 and thus situated for measuring temperature and pressure respec- tively in the inlet line 7 and the return line 8 from the by-pass 5. The flow regulation system 1 1 further comprises a controller box 16, wherein an electronic controller unit is provided (not depicted) and an internal battery (not depicted) is connected with the controller unit for supplying power to the operating of the controller unit. The controller unit can receive measured tem- perature and pressure data from the sensors via wires, respectively 16, 17 and can adjust an opening degree of the flow control valve and thereby the flow of district heating water through the valve 12, as the actual flow also depends on a differential pressure over the valve.

The controller unit comprises means (not depicted) for wireless communication with a controller unit (not depicted), whereby the controller unit can receive data from and thereby be remotely-controlled from the communication unit and can transmit data for remote logging to the communication unit. The controller unit is adapted as a slave unit, which is programmed to periodically after a first programmed time interval to prompt a command from the communication unit, that correspondingly can be adapted as a master unit, and for periodically fol- lowing a second programmed time interval to transmit data to the communica- tion unit.

Thus, it is possible via the controller unit to regulate the flow control valve 12 automatically and dynamically, and it is possible to control the valve 12 and thereby the flow through the by-pass as required, i.e. such that, a temperature in the inlet line at or a bit above the required minimum temperature, is main- tained. If the temperature is to low, the controller unit will adjust the valve to a larger degree of opening and thereby larger flow through the by-pass, where after the inlet temperature will increase. If the temperature is to high, will the controller unit adjust the valve to a smaller degree of opening and thereby a smaller flow, where after the inlet temperature will decrease. The temperature can be measured continuously or periodically after defined time intervals, such that it will be possible to ongoingly adjust the valve and thereby the inlet tem- perature. The controller unit is adapted to perform a dynamic regulation of the flow through the by-pass 5 as a function of the temperature measured in the by-pass 5.

The battery contains a battery pack with four lithium AA-batteries, 3.6 V ER145050.

In the interval between the prompting for a command, respectively the transmission of data is the controller unit’s means for wireless communication passive or turned off and has thereby a power consumption near or at zero. The means for wireless communication is moreover adapted, such, that it is not possible to‘wake up’ the controller unit through the use of communication form a communication unit i.e. so-called push-commands are not possible.

As the controller unit is not connected to an external power supply the district heating plant is secured full control of the operation of the system.

The controller unit moreover allows for wireless control of the controller unit, whereby it is possible to adjust the controller unit to control the flow in the by-pass following a user profile, which the controller unit is provided with via the communication unit, and which is stored in the memory of the controller unit. The controller unit is moreover adapted to communicate data to the com- munication unit, which can trigger an alarm following a deviation profile, which is a part of the user profile in use. The deviations are more precisely deviations in relation to the defined pressure and temperatures of the sensors 13, 14 in the valve 12.

The flow regulation system further comprises an actuator 18, which is fitted on the flow control valve 12 to further provide a, according to the circumstances, suitable change of the degree of opening of the flow control valve 12 and thereby the flow through the valve 12 and thereby the by-pass 5. The actuator 18 is a linear actuator with a stroke length, and a stroke length of the flow con- trol valve 12 is adapted to the actuator stroke length.

The actuators motor M is powered by the same battery as the controller unit, as there for the purpose is provided a current-carrying connection 19 between the battery and the actuator 18. The connection 19 further comprises wires for operation of the motor through the help of the controller unit.

The controller unit is adjusted to a reception interval of 6 hours and a transmis- sion interval of 15 minutes.

The controller unit is moreover adapted for periodically measuring the life span of the battery by measuring the battery voltage and to transmit this information to the communication unit. The controller unit is also adjusted to adjust the flow control valve in a fully open position, when the battery life span is measured to be close to zero.

The flow regulation system is also adapted such, that the battery powers the sensors 13, 14 via wires in the connections 16, 17.

The communication unit is a smart phone, which has an internet con- nection with the cloud, as the controller unit is adapted to connect with the cloud, of. also more about the connection with the cloud below. The communi- cation unit can be accessed via a mobile app and a code on the box 15, where supplying the communication unit with the code can identify the system and/or in cases of retrofitting of the system can suggest a place for fitting the system. Moreover, there can via the app be encoded an alarm threshold value in the flow regulation system for one or more of the values measured with the sensors 13, 15, where the alarm can be communicated to the communication unit, when an alarm threshold value has been reached.

The sensor 14 is situated for measuring of a system pressure in the district heating system, as the sensor 14 is connected with the controller unit, such that the controller unit can register the system pressure.

Temperature sensors will in other embodiments moreover be fitted in inlet line 3 and return line 4 from the heat exchanger in HIU 2, and the meas- urement data can be transfer to the controller unit, whereby the temperature drop over the heat exchanger can be monitored, and the system can be ad- justed to reach an optimal or improved (typically higher) temperature drop over the heat exchanger. The sensor in the inlet line 3 could here be the sensor 13, as the temperature in the by-pass 5.

The flow regulation system can further comprise pressure sensors situated for measuring of a differential pressure over the flow control valve, as these pres- sure sensors are connected with the controller unit, such that the controller unit can register the differential pressure and communicate this to the communica- tion unit, where after the pump pressure via the data from the communication unit can be used for adjusting the pump pressure to a required minimum level on the supplier side. The controller unit can via the communication unit be coded or adjusted with a suitable or customized user profile, which can be selected automatically or manually depending on the circumstances. A profile can e.g. be for seasonal operation such as summer/winter-operation or can be daily-operated, as it e.g. can take capacity limits or similar into account, which can vary during the day.

The box 15 is provided with a display, wherein it is possible to show measurements from the sensors 13, 14 of the flow regulation system, and where it is possible to adjust the controller unit, e.g. for choosing a user profile.

The individual batteries in the battery is combined in a battery pack in the box 15.

The flow control valve 12 is of the type PICV (pressure independent control valve), in particular the applicants WO 2009/135490 A2, in particular a Frese® Optima Compact® valve. The valve is modified, such that it has a shorter stroke length than usual.

The controller unit comprise a memory (not depicted), where potentially one or more user profiles and measure data can be stored. It further comprises a PCB for operation and connections with the individual components in the unit (not depicted).

The wireless means for communication further comprises one or more PCBs, a network adapter as well as an antenna for the communication with the communication unit and allows electronic, wireless communication with the communication unit.

The time interval for reception of data is 10 seconds.

The controller unit is moreover adapted for wireless communication with the communication unit via a network of the LPWAN-type, in particular the Sigfox- network. Data from the controller unit is provided for the communication unit and/or commands from the communication for the controller unit via a cloud service. When the data via the Sigfox-network transfers from the controller unit to the data collection in the sky, the communication unit can via the internet transmit commands to the sky anytime, and the controller unit can prompt the sky anytime and (potentially with a delay) receive commands from the sky. Cor- respondingly can the controller unit transmit data to the sky at said time interval, and the communication unit can gather data on a potentially later suitable point in time, when the communication unit establishes connection with the sky.

The actuator 15 remains substantially in the same position, when no power is applied. This is possible through the use of a three-way actuator.

The stroke length of the valve 12 and the actuator 15 is 2.5 mm.

The district heating system comprises in the embodiment in fig. 2 fur- ther a second flow control valve 20 fitted in the return line 4 from the heat ex- changer. The second flow control valve 20 is connected to a second electronic controller unit. The controller unit adjusts an opening degree of the second flow control valve 20 and comprises corresponding means for wireless communica- tion with the communication unit, whereby the controller unit correspondingly can receive data from and thereby be remotely-controlled from the communi- cation unit.

Thereby, it is possible via the communication unit wirelessly and remote-con- trolled to shut off the heat at a user e.g. in relation to missing payments.

The second flow control valve 20 and the associated control unit corn- prise a controller box 21 , which in its content and appearance is identical to the controller box 15. Correspondingly is there fitted a corresponding actuator 22 on the second flow control valve 20.

The second flow control valve 20 and the associated controller unit 21 is cor- respondingly retrofitted in the district heating system depicted in fig. 1 , in par- ticular is the second flow control valve 20 fitted in the return line 4 after the string-part 4a and the static valve 10.

The controller unit associated with the second flow control valve 20 is connected with the temperature sensor 23 situated in the inlet line 3 towards the heat exchanger after the inlet line 7 for the by-pass 5 and a temperature sensor 24 situated in the return line 3 from the heat exchanger before the return line 8 for the by-pass 5.

The controller unit associated with the second flow control valve 20 is adapted to through the use of temperature data from the two temperature sensors 23, 24 to adjust the second flow control valve 20 on the basis of a difference in the measured temperatures compared to the cooling profile stored in the memory of the controller unit connected to the second flow control valve 20. Hereby can a suitable cooling of the district heating fluid be reached, whereby further ther- mal energy can be saved.

The sensors 23, 24 further comprises pressure measuring and are provided in the shape of PT-plugs, as the sensor 24 more specifically is situated for meas- uring in the valve 20, in particular in an inlet hereof. The controller unit associ- ated with the second flow control valve 20 is thus also adapted to receive pres- sure measurements from one or both pressure sensors. The controller unit as- sociated with the second flow control valve 20 is thus also adapted to monitor pressure measurements from the pressure sensor 24 situated in the return line 4a from the heat exchanger, more specific in the inlet in the valve 20, and is thus adapted to register sudden and/or large drops in pressure in the return line 4, which will correspond to the system pressure in the district heating system, and for transmitting an alarm for the communication unit in such cases. Hereby could line ruptures on the district heating system be discovered rapidly.

In an embodiment of the method according to the second aspect of the inven- tion for flow control of the flow regulation system in fig. 2 the method comprises the steps of:

providing a flow regulation system comprising the first flow control valve 12 as depicted in fig. 2 by retrofitting of the system for replacing the static valve 6 in the system in fig. 1 ,

communicating temperature measurements from the temperature sen- sor 13 to the controller unit, and

the controller unit in the box 15 automatically adjusting the flow control valve 12 based on the temperature measurement.

The controller unit’s adjustment of the flow control valve 12 is based on a user profile, which is stored in the memory of the controller unit, and which the con- troller unit can be provided with from the communication unit.

The controller unit’s adjusting of the flow control valve 12 takes place via a signal transmitted from the controller unit to the actuator 18 of the flow control valve 12 via the connection 19.

In an embodiment of the method according to the third aspect of the invention for retrofitting of the flow regulation system in fig. 2 in the district heating system in fig. 1 , the method comprises the steps of:

providing an existing district heating system according to fig. 1 , demounting the static valve 6; and

retrofitting the flow regulation system according to fig. 2 comprising the flow control valve 12 as replacement for the static valve 6.

Moreover, is the system retrofitted at the right of the valve 12 in fig. 2, i.e. the system comprising the second flow control valve 20, the actuator 22, the box 21 and the components, here within the controller unit, herein also the temperature sensors 23, 24, in a way, which is depicted and described for fig. 2 above in the district heating system according to fig. 1 . Hereby is the district heating system according to fig. 2 reached.

Alternatively, can the flow regulation system depicted in fig. 2 comprising the flow control valve 12 be installed in relation to the establishment of a new dis- trict heating system as depicted in fig. 2, i.e. a first district heating system as depicted in fig 1 with a static flow valve 6, which first has to be demounted, is not provided i.e. it is not concerning a retrofitting of a flow regulation system, but solely a fitting of a flow regulation system in the district heating system in fig. 2.

A such new district heating system can within the scope of the inven- tion be fitted with or without fitting of the system associated with the second flow control valve 20, i.e. without the second flow control valve 20, the actuator 22, the box 21 and the components, here within the controller unit, herein also the temperature sensors 23, 24.

The district heating system depicted in fig. 1 could according to the invention furthermore as a general alternative to the embodiment depicted in fig. 2 be constructed without the presence of the system associated with the second flow control valve 20, i.e. without the second flow control valve 20, the actuator 22, the box 21 and the components, here within the controller unit, herein also the temperature sensors 23, 24. In this situation the district heating system would, according to the embodiment, be at the right of the flow control valve 12 the diagram in fig. 2 instead be constructed as the district heating system in fig. 1 at the right of the static valve 6.

Claims

P A T E N T C L A I M S

1 . A district heating system, comprising:

- a heat exchanger for transmission of thermal energy between a supply side and a user side of the district heating system;

- an inlet line (3, 3a) towards and a return line (4a, 4) on the supply side of the heat exchanger;

- a bypass (5) situated between the inlet line (3, 3a) and the return line (4a, 4) from the heat exchanger; and

- a flow valve (12) situated in the bypass (5),

wherein the flow valve (12) is a flow control valve (12), which forms part of a flow regulation system of the district heating system

wherein the flow regulation system comprises

- a first temperature sensor (13, 14) situated for measuring a tem- perature in the bypass (5); and

- an electronic controller unit

wherein the controller unit can receive measured temperature data from the temperature sensor (13, 14) and can adjust a degree of opening of the flow control valve (12),

c h a r a c t e r i z e d in that

- the flow regulation system further comprises a battery connected with the controller unit to power the operation of the controller unit,

wherein the controller unit comprises means for wireless communica- tion with a communication unit, wherefrom the controller unit can receive data and thereby be remote-controlled from the communication unit and can trans- mit data for remote logging to the communication unit, and

wherein the controller unit is adapted as a slave unit, which is program- mable for periodically after a first programmed time interval to prompt a com- mand from the communication unit, which correspondingly can be adapted as a master unit, and for periodically after a second programmed time interval to transmit data to the communication unit.

2. A district heating system according to claim 1 , wherein a change of the degree of opening of the flow control valve is provided by an actuator motor (M) of an actuator (18), where the actuator motor (M) is powered by the battery.

3. A district heating system according to claim 2, wherein the actuator (18) re- mains in the same position, when applied no voltage.

4. A district heating system according to claim 2 or 3, wherein the stroke length of the flow control valve (12) and/or the actuator (18) is less than 10, 5, 4, or 3 mm, e.g. 2.5 mm.

5. A district heating system according to any of the preceding claims, wherein the means for wireless communication are adapted or programmed to receive data in a time window, which opens at a time interval of 1 -120 minutes, 2-60 minutes, 5-30 minutes or 10-20 minutes, e.g. approximately 15 minutes, and/or to receive data at a time interval of ½-12 hours, 2-10 hours, 3-9 hours, 4-8 hours or 5-7 hours e.g. approximately 6 hours.

6. A district heating system according to any of the proceeding claims, wherein the controller unit is adapted to wireless communication with a communication unit via a network of the LPWAN-type.

7. A district heating system according to any of the preceding claims, wherein data from the controller unit to the communication unit and/or commands from the communication unit to the controller unit are provided via the cloud or a cloud service.

8. A district heater system according to any of the preceding claims, further comprising a second flow control valve (20) fitted in the inlet line (3, 3a) towards or the return line (4a, 4) from a heat exchanger between a supplier side and a user side of the district heater system, wherein the second flow control valve (20) is linked with the controller unit of the flow regulation system or a second electronic controller unit, wherein the controller unit of the second flow control valve (2) can adjust a degree of opening of the second flow control valve (20) and comprises means for wireless communication with a communication unit, potentially the same communication unit as for the controller unit of the flow regulation system, whereby the controller unit for the second flow control valve (20) can receive data from and thereby be remote-controlled from the commu nication unit.

9. A method for flow control of a flow regulation system according to any of the preceding claims, wherein said method comprises the steps:

- providing a flow regulation system according to any of the preceding claims,

- communicating a temperature measurement from the temperature sensor (13, 14) to the controller unit, and

- automatically adjusting the flow control valve (12) based on the tem- perature measurement.

10. A method according to claim 9 for flow control of a flow regulation system according to claim 8, wherein the controller unit associated with the second flow control valve (20) is adapted for monitoring the pressure measure- ment from a pressure sensor (24) situated in the return line (4a, 4) from the heat exchanger and to register loss of pressure in the return line (4a, 4), which corresponds to the pressure of the installation of the district heating system, and potentially transmit data to the communicating unit, which can trigger an alarm.

1 1. A method for retrofitting a flow regulation system in a district heating sys- tem, wherein said method comprises the steps:

providing an existing district heating system, which comprises

- an inlet line (3, 3a) towards and a return line (4a, a) on the supply side of the heat exchanger;

- a static valve (6) situated in the bypass

c h a r a c t e r i z e d in that the method further comprises the steps: dismounting the static valve (6) and

- a flow control valve (12), which forms a part of a flow regulation system of the district heating system;

- a first temperature sensor (13,14), situated to measure a temper- ature in the bypass (5);

- an electronic controller unit, which can receive measured temper- ature data from the temperature sensor (13, 14) and can adjust an opening degree of the flow control valve (12), wherein the con- troller unit comprises means for wireless communication with a communication unit, wherefrom the controller unit can receive data and thereby be remote-controlled from the communication unit and can transmit data for remote-logging to the communica- tion unit, and wherein the controller unit is adapted as a slave unit, which is programmed for periodically after a first pro- grammed time interval to prompt a command from the communi- cation unit, which correspondingly can be adapted as a master unit, and for periodically after a second programmed time interval to transmit data to the communication unit; and

so that the controlling unit can adjust the opening degree of the flow control valve for controlling a flow through the bypass.