EP1862878B1

EP1862878B1 - Control system for a fluid tube network such as a central heating system

Info

Publication number: EP1862878B1
Application number: EP07108634A
Authority: EP
Inventors: Mads Lildholdt
Original assignee: Broen AS
Current assignee: Broen AS
Priority date: 2006-05-30
Filing date: 2007-05-22
Publication date: 2013-01-23
Anticipated expiration: 2027-05-22
Also published as: EP1862878A2; DK200600734A; DK1862878T3; EP1862878A3

Description

FIELD OF THE INVENTION

The present invention relates to a system for controlling the flow of fluid in a tube network, preferably flow balancing of central heating systems

BACKGROUND OF THE INVENTION

When central heating systems are installed, it is necessary to balance the different branches in the heating systems with respect to flow. The flow resistance will typically be largest for the valves that are the farthest away from the water pump due to the friction in the tubing system.
Typically, the flow is measured in the valve farthest away, typically called the reference valve, and the flow is balanced with the flow in the valve next to the reference valve. This procedure is tedious and lengthy and is even further difficult if there are general errors in the network such as closed valves or missing throughput through certain tubes. Such errors have to be corrected before flow balancing of the system. This implies a manual control that all valves are fully opened and a check that there is a flow through all valves. Such a check takes typically half an hour for each valve and up to an hour for difficult accessible valves. Thus, the initial check for proper throughput in the tubes of the system and the following balancing method is lengthy and tedious.
Furthermore, it is often necessary to employ two persons for the check. One person controls one valve, whereas the other person reads the flow change in the other valve, for example the reference valve. As a consequence, existing methods for initial check and balancing are expensive to perform.
A system for adjustment of valves is disclosed in German open laid script DE 102576211 by Schmitt. The valves are configured for mutual wireless communication. However, there is not given any advice for how to perform the initial check for finding errors in the tubing system.
A system for controlling systems distributing flowing medium is disclosed in WO 03/001312 . This system relates to a basic control for measurements at a reference valve and measurements at a site to be adjusted. There is no disclosure of a valve provided with a unit comprising a flow gauge, a transmitter and an electric actuator for automated valve setting as a demountable add-on unit.

DESCRIPTION / SUMMARY OF THE INVENTION

The invention is defined by independent claim 1. It is the object of the invention to provide an improved system, where the initial check and the balancing of a tube network, such as a central heating system, can be performed in a faster and less expensive way.
This object is achieved by a system for controlling the flow of fluid in a tube network, for example a central heating system, the network comprising a fluid forward tube and a fluid return tube, between which there are provided a number of parallel tube strings to constitute parallel fluid circuits,

each string having a flow regulation valve for regulating the flow through the string,
each valve having a flow gauge for measuring the flow through the valve,
the system comprising a number of transmitters, wherein each of the flow gauges is connected to a transmitter and configured for transmission of measurement data from the transmitter, wherein the transmitter is configured for wireless transmission of the measured flow data together with a unique ID to a central computer for relating the received flow measurement to the corresponding valve,
the central computer being configured for receiving the measured flow data from the transmitters through wireless transmission,
wherein the central computer, preferably a handheld device, has a display for displaying data for control of the flow measurements and a keypad for receiving user commands for the flow adjustment,
wherein the computer is a handheld device,
wherein the valves are provided from a manufacturer or distributor with a unit comprising a flow gauge and a transmitter as a demountable add-on unit on the valve, and
wherein the unit also comprises an electric actuator for automated valve setting.

In such a system, a single person can perform the initial check for errors in the tubing system in a fast way, because all valves can be checked simultaneously with computer, especially as the computer is a handheld device. The tedious procedure, where one person is checking flow through one valve and another person is adjusting a valve in a neighbouring string is not necessary, because a single person can read the flow from one valve while adjusting another valve. In fact, the person may follow the flow not only to a single valve but may during the valve adjustment follow the flow through all other valves in a branch.
In order to provide the facilities as described above without large costs, the valves are in accordance with a further development provided from a manufacturer or distributor with a flow gauge and a transmitter as a demountable add-on unit on the valve. In addition the unit also comprises an electric actuator for automated valve setting. The unit is demounted after a flow balancing procedure and sent back to the manufacturer or distributor for recirculation with new valves.
In a practical embodiment, the unique ID is comprised by an electronic circuit of the corresponding valve and wherein the electronic circuit is functionally connected to the transmitter, in order for the transmitter to receive this ID for further transmission of the ID to the central computer. For example, the transmitters may be identified by the ID from the corresponding valves, in other words, the transmitters take over the ID of the valve to which the transmitters are connected. Alternatively, the transmitters may have an own ID which, optionally, may be combined with the valve ID. Several solutions may be chosen, however, important is that the valves can be identified and distinguished in order for an adjustment to be performed correctly.
In order to control the flow data only for those valves that are influenced by the adjustment, the computer is configured for pre-selection of the IDs of a number of valves and for programming through the keypad to only receive or display measurements from the pre-selected valves. This feature allows a grouping of valves, for example in the same or in a number of buildings. The central computer can thus identify those valves that belong to a certain group and may even combine different groups or part a group into subgroups, if desired. For example, subgroups may belong to different floors in a building, which are combined in the end to form a large group for one building. These large groups for a building may again be part of a balancing method comprising a number of buildings. This way, the grouping according to the invention of the valve IDs may result in a tree-like structure of the balancing method, where subgroups are balanced first and then in steps combined to larger parallel groups, which again are compared mutually for balancing.
For example, all transmitters may be programmed to send the measurement data in a steady manner. However, in order to reduce the amount of data to be handled in the computer, it may be programmed to discard or disregard those measurements that are not relevant for the actual adjustment. In addition only relevant, pre-selected measurements may be indicated on the display.
An advantage of the above mentioned subgrouping is the possible reduced power consumption because the transmitters may be programmed only to use power for the transmission in case that the valve connected to the transmitter belongs to a selected subgroup.
Part or all of the above mentioned procedure may be automated in the computer in the system according to the invention as will become more apparent in the following. For example, in order to facilitate the initial check for errors in the network, the central computer may be configured to indicate alerts on the display and the IDs of those valves for which the flow through the valves is below a predetermined threshold value. Thus, the computer may be started and receive measurements and may automatically indicate those valves for which there are expected errors due to the predetermined parameter values.
In a further embodiment, the transmission unit, called transmitter in the foregoing, is also able to receive data. This transceiver may additionally be configured for receiving a trigger signal from the central computer for initiating transmission of flow data to the computer. It may be inconvenient that all transceivers are sending measurement data repeatedly as long as there is no computer to receive the signals or as long as these measurement data are not needed. In order to reduce the electricity consumption and in order to reduce the transmission of unnecessary data, the data transmission may be triggered by a trigger signal from the computer.
For example, the transceivers may be configured to transmit a sequence of polling signals with a predetermined time delay between consecutive polling signals as requests for receiving a trigger signal from the central computer. The transceivers may in addition be programmed to await a trigger signal before transmission of flow data. This way, a transmission of measurement data is only performed after receiving such a trigger signal. Also, the combination of the flow gauge and the transceiver may optionally be programmed to only perform the flow measurement after having received such a trigger signal.
In order to restrict the data to receive, the computer can be configured for selection of a number of valve IDs and configured for only sending a trigger signal to these selected valves. This implies that the different transceivers select between signals received that are not addressing the transceiver and trigger signals that are addressing the specific transceiver and gauge.
The transceivers may be programmed to only perform one transmission of measurement data after having received a trigger signal from the computer. Alternatively, the flow gauges together with the transceiver may be configured for performing and transmitting measurements until a second trigger signal is received.
The transceivers may also be configured to send data to the functionally connected electronic circuit of the valve. These data may be received from the central computer for a proper programming of the valves, for example for change of the ID of the valve. However, normally, each valve is provided with a unique ID that cannot be changed. The central computer may be provided with information from a database about the valves, for example the size and capacity of a valve, such that relevant data are available as soon as the ID of a valve is received by the central computer.
A different option are flow gauges with transceivers that are configured for performing and transmitting further measurements only if the flow through a valve changes more than a predetermined value. This reduces the number of data sent such that only transmissions are performed if there are measured pronounced changes in the flow through the valve. For example, there may be no need for a new data transmission unless the flow changes by more than a certain percentage of the flow value.
In order to avoid the necessity of accessing and adjusting each valve manually, the valves may be equipped with an automated electric actuator for regulation of the valve. In a further embodiment, the actuator may be connected to a receiver that is configured for receiving a wireless data signal from the central computer indicating the desired valve setting and configured for automatically adjusting the valve in response to the signal. The receiver may identical to the same transceiver as mentioned before.
For example, the computer may be configured to transmit a valve setting for continuous flow reduction of the valve until a valve setting stop signal is received. Thus, the actuator may be set to reduce or increase the valve opening in a steady manner at a predetermined speed, until a stop signal is received by the actuator. This way, the central computer may set a number of valves to change the valve opening steadily while measurements of a number of valves - the same and/or other valves - are performed in order to study the influence of the changes and in order to find an optimum final balance.
One of the difficulties in such systems is the precision with which the actual flow through the valves is measured. In prior art systems, a reading of the data from the flow gauge has to be transformed into some kind of actual flow data. However, often the indications from the gauges do not work linearly with the actual flow, and a variation in the reading does not reflect the actual flow very precisely. In order to improve these systems, the valves according to the invention may optionally be provided with venturis for the flow measurements. Venturi valves are described in International patent applications WO O1/71289 by Lildholdt or WO 2005/88263 by Engelbrektsson. As alternatives to venturis, fixed or variable orifices may be employed.
In a typical central heating system, the regulation of a valve in a string influences the flow through other valves in other strings as described above. In order to further ease installation and balancing, the computer may be configured for calculating an optimal flow in the tube network in accordance with predetermined flow parameters, and configured for calculating a setting of the flow through each valve to achieve the optimal flow. The computer may in addition be programmed to perform the entire initial check automatically and indicate where errors are to be expected. If there are no errors detected or if errors may be neglected or if errors have been corrected, the entire balancing process may be performed with programmed software routines by the computer. Service personnel or technicians may follow the process by means of the display.
In the most advanced version of the invention, the technician enters a building with a central heating system and initiates the triggering process after which the computer with the data transmission capabilities performs the entire check automatically while the technician surveys the process by means of the display. Thus, only little or no human interfere is necessary for the process. The result is a fast, reliable and cost reducing process. For reduction of calculation time, the computer may be configured to await receipt of flow measurement data only from selected transmitters before calculation is initiated of the setting for the first valve to be set in accordance with the predetermined scheme.
For example, the central computer can be configured for calculating the regulation of the valves in accordance with a predetermined proportional balancing model for a sequential regulation of the valves in dependence on a valve position in the network. This method has proved to be advantageous due to its simplicity and reliability. However, due to the aforementioned automatic process, a readjustment of the valves is possible without much additional work. Thus, also other processes may be used for balancing, even those processes that are tedious and difficult according to prior art techniques but which due to the automatic process according to the invention can be performed quickly and reliable without the necessity of substantive human interference.
In the foregoing, the tube system according to the invention has been described as a central heating system. However, it should be noted that the invention may be used for other tube systems where a control of the flow through a number of parallel strings is desired, for example where a likewise balancing technique is necessary or desired.
The data transmission from a transmitter or transceiver may be directly to the central computer of through other transceivers or through special external unit designed for forwarding signals from the different transmitters or transceivers.

SHORT DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail with reference to the drawing, where

FIG. 1 illustrates a branch in a central heating network,
FIG. 2 illustrates a valve unit according to the invention.

DETAILED DESCRIPTION / PREFERRED EMBODIMENT

FIG. 1 illustrates a branch 1 in a fluid network 2. A supply tube 3 delivers heating water to the branch 1 and a network return tube 4 receives the heating water after heat has been delivered to the branch 1. The branch comprises a forward fluid tube 5 and a return fluid tube 6, between which there are provided a number of parallel tube strings 7, 7', 7" to constitute parallel fluid circuits. A circuit implies transport of heating water from supply tube 3 through forward fluid tube 5, string 7, 7', 7", return fluid tube 6 and return tube 4. Each string 7, 7', 7"comprises a heat exchange system 8, 8', 8" and a adjustment valve 9, 9', 9" in each string 7, 7', 7". The branch itself, as well, comprises an overall adjustment valve 10 for adjustment of the total flow through the branch 1.
When a heating system is built up, a first check is performed, whether any of the valves 9, 9', 9", 10 or strings 7, 7', 7" should be blocked for proper heating flow through it. This is done by checking the flow though each valve. For this sake, each valve - as illustrated in more detail in FIG. 2 - is equipped with a flow gauge 11 connected to a transceiver 12 for transmission of flow data to a central handheld computer 13 by wireless transmission 14, for example Bluetooth or radio transmission. The actual flow data are transmitted with an ID unique for the corresponding valve 9 and are preferably shown on a display 15 of the handheld computer. A service person may control, whether the flow through the valves are higher than a predetermined value in order to be acceptable. This check may be performed by comparison with a list containing the position of the valves with a corresponding identification code (ID) and the expected flows through the valves. Such a list may be provided manually or may be programmed into the handheld computer. Alternatively, the handheld computer may give an alarm, if the flow through any of the valves is below a predetermined threshold value. Such an alarm would indicate that either the adjustment of the valve is incorrect or that there are obstacles or damages in the tubes preventing a proper functioning of the system. Thus, an alarm would require a subsequent check of valves and tubes.
Normally, a valve is delivered form the factory fully open to provide maximum flow through the valve when installed. However, during installation, the valve may have been adjusted by mistake which may be checked manually. However, in order to ease the adjustment, the valve 9 according to the invention is provided with an adjustment system 16 in combination with an actuator 17. The actuator 17 may report the actual position through the transceiver 12 and to the computer. On the other hand, the computer may be used for transmission of a desired valve setting from the computer 13 to the actuator 17, such that an automated valve adjustment is possible from a remote location. This is an important facilitation for the person performing the check in as much as the valves not always are easily accessible.
Once the initial check for obstacles, closed valves or other damages and malfunctions has been done, a balancing adjustment of the valves is performed. This balancing method may be performed in different ways. The problem for a new system is the fact that an adjustment of one valve changes the flow through all the other connected tubes and valves. For example, if one valve is adjusted to a reduced flow, the pressure increases for the other valves, such that the setting is no longer correct. This implies a steady readjustment, until satisfactory system has been found. Adjusting many valves several times requires substantial labour. Doing this with manual labour requires many hours of working in prior art systems.
One of the principles that have proven to be very versatile is the proportional balancing system, or the compensated method. In this balancing method, the flow is only adjusted once, possible with a final check and a single further adjustment. This method assumes the possibility to measure the flow disturbance due to the adjustment of a balancing valve and assumes that the disturbance can be compensated for. As a first step, a reference valve 7 is selected, which is typically the valve that is farthest away from the fluid supplying pump. This valve may be adjusted until the flow through the valve 7 reaches its design value. If the design value is larger than the actual value, the valve flow is not reduced but kept fully open and the flow through the other valves is reduced in order to increase the flow through the reference valve.
Once the correct flow has been achieved in the reference valve, the flow through heat exchange system 1 is correct. Next, the valve 7' is adjusted to its design setting. However, the reduction of flow through valve 7' may cause a slight increase in the first valve 7. This is then reduced by adjustment of the branch valve 10, which also is termed partner valve. The adjustment of the remaining valves 7" in the branch is then performed accordingly with readjustment of the branch valve 10.
Typically, the flow balancing of the valves in a network is only performed once, such that the valve settings remain stationary for the rest of the lifetime of the valve. This implies that the flow gauge 11, the adjustment system 16 actuator 17 and the transceiver 12 only is used once, namely for the balancing procedure. Although these components are rather expensive, the saved working time by the person checking and adjusting the valves may balance the costs for these additional components. However, preferably, the flow gauge 11, the adjustment system 16 actuator 17 and the transceiver 12 is provided as a complete add on unit, which is mounted on the valve during fabrication of the valve but in a demountable way, such that the unit may be demounted from the valve after the balancing method and sent back to the manufacturer in order to be mounted on the next valve.
The handheld computer is provided with a display for displaying the settings and the flow measurements from the different valves. The computer is also provided with a keypad in order to enter commands such as scrolling through the menus and the results and for input of valve settings in accordance with a list. Alternatively, the list may be stored inside the computer memory already, and the balancing method may be performed automatically by the computer. The personnel may in this case only be involved, if there are design settings for the flow cannot be achieved during the initial check or during the balancing method. The display may inform the user about the status of the balancing method. This implies that the initial check as well as the balancing can be performed with a minimum of man power required.
The initial check and balancing may be performed in a typical large system with a number of branches. Once all branches have been adjusted individually, the different branches may be adjusted mutually in the same way in which the different strings were adjusted such that the branch valve 10 of the branch farthest away from the pump is adjusted to its design value, after which the remaining branches are correspondingly adjusted.
When a large heating system is installed in a building, the time from installation of the first valve until all other branches are installed may be substantial. The question then arises, at which point of time, the valves flow gauges in combination with the transceiver should start transmitting flow measurements to the computer. If the transceivers start transmitting measurements from the moment of installation, the power source may not be strong enough to continue the transmission until the last valve has been installed and the balancing method is performed. In order to take account for that, in a further embodiment, the transceiver 12 awaits a trigger signal from the computer 13. Furthermore, the transceiver may only be open for receiving such a trigger signal in repeatedly small time spans in order to further mimimise consumption of electricity. These small time spans may be repeated with certain intervals, for example for each half hour. In order to synchronise the time span where the transceiver is ready to receive a trigger signal and the computer to send the trigger signal, the transceiver sends a polling signal periodically, for example for each half hour. Once, the computer is ready for performing the initial check of the balancing, the computer sends the trigger signal immediately after having received a polling signal. The trigger signal arrives within the receiving time span of the transceiver, which activates the flow gauge to submit flow measurement data to the transceiver for further transmission to the computer. This set up minimises the current consumption in the measuring and adjusting unit.
Once having received the trigger signal, the transceiver 12, the flow gauge 11 and the adjustment actuator 16, 17 may stay activated and alert for a certain time such as some hours in order for being capable to receive the adjustment commands and commands for transmission of flow data during the balancing method.

Claims

A system for controlling the flow of fluid in a tube network, the network comprising a fluid forward tube (5) and a fluid return tube (6), between which there are provided a number of parallel tube strings (7, 7', 7") to constitute parallel fluid circuits,
- each string having a flow regulation valve (9, 9', 9") for regulating the flow through the string,

- each valve having a flow gauge (11) for measuring the flow through the valve,

- the system comprising a number of transmitters (12), wherein each of the flow gauges (11) is connected to a transmitter (12) and configured for transmission of measurement data from the transmitter, wherein the transmitter (12) is configured for wireless transmission of the measured flow data together with a unique ID to a central computer (13) for relating the received flow measurement to the corresponding valve,

- the central computer (13) being configured for receiving the measured flow data from the transmitters (12) through wireless transmission,

- wherein the central computer (13) has a display (15) for displaying data for control of the flow measurements and with a keypad for receiving user commands for the flow adjustment,

- wherein the central computer (13) is a handheld device,

- wherein the valves are provided from a manufacturer or distributor with a unit comprising the flow gauge and the transmitter as a demountable add-on unit on the valve, and

- wherein the unit also comprises an electric actuator for automated valve setting.
A system according to claim 1, wherein the unique ID is comprised by an electronic circuit of the corresponding valve and wherein the electronic circuit is functionally connected to the transmitter for transmission of the ID.
A system according to any preceding claim, wherein the computer is configured for pre-selection of the IDs of a number of valves and for programming through the keypad to only receive or display measurements from the pre-selected transmitters.
A system according to claim 3, wherein the central computer is configured to indicate on the display the flow of the pre-selected valves.
A system according to any preceding claim, wherein the central computer is configured to indicate an alert on the display, the alert comprising the ID of a valve for which the flow through the valve is below a predetermined threshold value.
A system according to any preceding claim, wherein the transmitter is a transceiver configured for receiving a trigger signal from the central computer for initiating transmission of flow data to the computer.
A system according to claim 6, wherein the transceivers are configured to transmit a sequence of polling signals with a predetermined time delay between consecutive polling signals as requests for receiving a trigger signal from the central computer, wherein the transceivers are programmed to await a trigger signal before transmission of flow data.
A system according to claim 7, wherein the computer is configured for selection of a number of valve IDs and configured for only sending a trigger signal to these selected valves.
A system according to claim 7 or 8, wherein the flow gauges are configured for performing and transmitting measurements until a second trigger signal is received.
A system according to claim 7 or 8, wherein the flow gauges are configured for performing and transmitting further measurements only if the flow through a valve changes more than a predetermined value.
A system according to any preceding claim, wherein the central computer is configured for transmission of desired valve setting signals to each valve, wherein each valve comprises an automated electric actuator for regulation of the valve, the actuator being connected to a receiver configured for receiving a wireless data signal from the central computer indicating the desired valve setting and configured for automatically adjusting the valve in response to the signal.
A system according to claim 11, wherein the computer is configured to transmit a valve setting for continuous flow reduction of the valve until a valve setting stop signal is received.
A system according to any preceding claim, wherein the fluid network is a central heating system.
A system according to any preceding claim, wherein each flow regulation valves has a venturi inside the valve for flow measurements.
A system according to any preceding claim, wherein the regulation of a valve in a string influences the flow through other valves in other strings, wherein the computer is configured for calculating an optimal flow in the tube network in accordance with predetermined flow parameters, and configured for calculating a setting of the flow through each valve to achieve the optimal flow.
A system according to claim 14, wherein the central computer is configured for calculating the regulation of the valves in accordance with a predetermined proportional balancing model for a sequential regulation of the valves in dependence on a valve position in the network.
A system according to claim 14 or 15, wherein the computer is configured to await receipt of flow measurement data from selected transmitters before calculation is initiated of the setting for the first valve to be set in accordance with the predetermined scheme.