WO2004001297A1

WO2004001297A1 - Boiler control unit

Info

Publication number: WO2004001297A1
Application number: PCT/NO2003/000194
Authority: WO
Inventors: Karl-Erik Lindberg
Original assignee: Energy Control Systems International As
Priority date: 2002-06-22
Filing date: 2003-06-12
Publication date: 2003-12-31
Also published as: GB2389891A; GB0214476D0; AU2003237721A1

Abstract

The invention relates to a boiler control unit (20) for controlling a burner (2) in a heating boiler (1). The control unit (20) includes a delayed cycle controller (21) and a monitoring controller (27), which is arranged to set the delayed cycle controller (21) in a first, conventional on-off-mode of operation and a second delayed cycle mode of operation, at predetermined points of time. The control unit (20) is further arranged to acquire data indicating the energy consumption and the outdoor temperature associated with time intervals corresponding to each of the two operation modes, and to transfer the acquired data to an external computer (13) at a subsequent point of time.

Description

BOILER CONTROL UNIT

Technical field

The invention relates in general to monitoring and control of temperature controlled heating processes, in particular heating boilers. More specifically, the invention relates to a boiler control unit which includes a delayed cycle controller and a monitoring function for providing information about the energy efficiency obtained by the delayed cycle controller.

Background of the invention

Heating boilers for heating the rooms of a building and/or for providing tap hot- water are usually dimensioned in such a way that they are able to manage conditions, in which an extremely high heating demand exists, i.e. during the coldest winter days. This means that the capacity of the heating boilers is utilised to the greatest extent during the cold periods of the year. During the remaining parts of the year, the boilers are over-dimensioned, and consequently, the overall efficiency is not optimal. A solution to this problem is presented in EP-651 873, which discloses a delayed cycle controller for a heating boiler equipped with an on-off controllable burner. The use of such a controller results in an improved overall energy efficiency, particularly in periods with low loads, i.e. during moderate and warm seasons.

Although such a delayed cycle controller provides an improved energy efficiency, there is still a need for providing information, e.g. to the power consumer, about the energy savings actually obtained by the controller. It is thus not possible to assess the real savings provided by the controller and to compare them with the investment necessary to equip the boiler with such a controller.

For a modern company, it is essential that energy savings obtained as a result of the investment may be reliably documented. This has an impact on the company's capabilities of delivering a valid environmental account, as well as on the company's environmental profile towards its clients, its suppliers and relevant public authorities.

Related background art

EP-651 873 discloses a controller for a heating boiler equipped with an on-off controllable burner. The boiler is provided with a thermal relay, which provides a temperature responsive signal which is switched on when the temperature in the boiler underpasses a lower temperature level and switched off when the temperature in the boiler exceeds a higher temperature level. When the high temperature limit is reached, the burner is switched off, as also would be the case if the thermal relay controlled the burner directly. However, when the low temperature limit is reached, the burner is not switched on immediately, as would be the case if the thermal relay controlled the burner directly. Instead, the controller is arranged to measure the cooling time of the boiler, by measuring the time that has elapsed between the on- to-off transition and the off-to-on transition of the signal provided by the thermal relay. The controller is further arranged to add a certain percentage to this cooling time, resulting in a time delay, and to switch on the burner when this time delay has elapsed.

This prior art controller provides an improved energy efficiency, but it does not provide information about the energy savings actually obtained by the controller, compared with the mere use of a conventional on-off control without a delay, such as the thermal relay.

A further development of the controller disclosed in EP-651 873 is available on the market under the brand "MicroTherm" (cf. www.energy-control-systems.no). The "MicroTherm" controller also includes an interface for connection of an external computer such as a notebook or hand-held computer. Certain parameters, such as the delay percentage (denoted "E-factor") may be set by means of a program executed by the external computer. Also, certain values may be output from the controller to the computer, such as the accumulated on-time of the burner. However, the controller is not able to accomplish comparative test procedures autonomously, i.e. off-line.

Summary of the invention

An object of the present invention is to provide a boiler control unit which may provide information about the energy efficiency obtained by the delayed cycle controller, compared to the use of a conventional on-off controller without a proportional delay, such as a thermal relay.

A further object of the invention is to provide such a control unit which provides information about the energy efficiency corresponding to certain time intervals.

Still another object of the invention is to provide such a control unit adapted to provide information about the outdoor temperature, and in particular, to provide such information related to said certain time intervals.

Still another object of the invention is to provide such a control unit which may communicate with and be programmed by an external computer.

The above stated objects and further advantages are achieved with a boiler control unit as set forth in the accompanying set of claims.

Brief description of the drawings

Fig 1 is a schematic diagram illustrating a heating boiler controlled by a control unit according to prior art, Fig 2 is a schematic diagram illustrating a heating boiler controlled by a control unit according to the invention,

Fig 3 is a schematic diagram illustrating further details of the control unit according to the invention.

In the figures, identical elements are identified with the same reference numerals.

Detailed description of the invention

Fig 1 is a schematic diagram illustrating a heating boiler 1 controlled by a control unit 10 according to the prior art, and more particularly the "MicroTherm" controller mentioned above.

The boiler 1 comprises a burner 2 controlled in an on-off manner by a delayed cycle controller 11 in the control unit 10. A thermal relay 6 provides a temperature responsive signal 7 which is switched on when the temperature in the boiler underpasses a lower temperature level. The signal 7 is further switched off when the temperature in the boiler exceeds a higher temperature level.

The delayed cycle controller 11 is further arranged to produce a control signal for input to the burner 2, in order to switch the burner 2 on and off as a function of the thermal relay signal and the time. More specifically, the control signal is switched off immediately when the thermal relay signal 7 is switched off, and the control signal is switched on at a delayed point of time after the thermal relay signal 7 is switched on. The delay is calculated by the controller 11 as a certain percentage of the boiler's cooling time, i.e. the time elapsed from the on-off transition to the off- on transition of the signal provided by the thermal relay 6. The control unit 10 is further adapted to communicate with an external computer 13.

This prior art solution does not provide means for monitoring and revealing the improved efficiency obtained by the delayed-cycle mode operation of the control unit.

Fig. 2 is a schematic diagram illustrating a heating boiler controlled by a control unit 20 according to the invention, and fig. 3 is a schematic diagram illustrating further details of the control unit 20 shown in fig. 2.

A boiler 1 comprises an oil burner 2 and a water tank 3 containing water heated by the burner 2. The heating plant further comprises a hot- water conduit 5 which may be further connected to a number of taps (not shown) and/or a room heating system (not shown) provided with a shunt valve, circulation pump and radiators. The heating plant further comprises an incoming conduit 4 for supply of cold water as well as a chimney (not shown) for discharging fluid gases resulting from the combustion of oil. With reference to fig. 2, the control unit 20 comprises a delayed cycle controller 21, a time delay register 22, a monitoring controller 27 and a real time clock 28.

The delayed cycle controller 21 is arranged to input a temperature responsive signal 7 provided by a thermal relay 6 which is arranged to sense the temperature of the water present in the water tank 3. The thermal relay 6 causes the temperature responsive signal 7 to be switched on when the temperature in the boiler underpasses a lower temperature level and to be switched off when the temperature in the boiler exceeds a higher temperature level.

The delayed cycle controller 21 is further arranged to perform a delayed cycle control function which is described in the following.

When the thermal relay signal 7 is switched off, the controller 21 deactivates the burner control signal 8, which leads to that the burner 2 is turned off. This occurs substantially immediately, such as within a couple of seconds, i.e. with no essential or intentional delay.

The delayed cycle controller 21 is further arranged to calculate the cooling time, i.e. the time of the temperature decay from the high temperature level to a low temperature level. This is performed by measuring the time elapsing between the on-to-off transition and the off-to-on transition of the signal provided by the thermal relay.

The delayed cycle controller 21 is further arranged to read a percentage value from the time delay percentage register 22, and to calculate a time delay, which equals the cooling time multiplied by this percentage value.

When the water temperature indicated by the temperature signal 7 falls below the low temperature level, the signal provided by the thermal relay is switched on. This off-to-on transition of the thermal relay signal does not lead to that the burner is switched on immediately. Instead, the controller is arranged to switch on the burner when the calculated time delay has elapsed. In this way, an extension of the off-time of the heating boiler is obtained, which leads to a reduction in the total consumption of energy, i.e., oil, by the burner 2.

If the percentage value is set to zero, the delayed cycle controller will act as a conventional on-off controller, i.e. with the same function as if the thermal relay controlled the burner directly.

The delayed cycle controller 21 is arranged to operate in a first, delayed-cycle mode of operation, wherein the control signal 8 is switched on at a delayed point of time after the temperature has decreased to the low temperature level. The delayed cycle controller 21 is also arranged to operate in a second, conventional mode of operation, wherein the control signal 8 is switched on essentially immediately when the temperature has decreased to the low temperature level, i.e. upon the detection of an off-to-on transition in the thermal relay signal 7.

The monitoring controller 27, not present in the prior art solution, is arranged to set the delayed cycle controller 21 in the first and second modes of operation at predetermined points of time. This provides for the possibility of acquiring information about the energy efficiency connected with operating the control unit in the delayed cycle operation mode.

The boiler control unit 20 preferably further comprises a real time clock 28, providing current time and date information to the monitoring controller 27.

Advantageously, the control unit 20 is further arranged to calculate the accumulated activated time of the heater control signal 8 through an interval. The accumulated activated time represents, i.e. is proportional with, the total energy consumption of the burner through this interval.

The temperature control unit 20 is further arranged to communicate with an external computer 13 via a communication connection 14 and an interface 26. The communication connection 14 may be based on a wired connection, such as a serial communication, or a local, wireless connection such as an infrared or a radio based (e.g., Bluetooth) connection. Alternatively, the communication connection 14 may include a telecommunication network such as the public switched network or a cellular network.

The predetermined points of time for setting the delayed cycle controller 21 in the first and second modes of operation are advantageously included in a data file that may be input from the external computer 13 during an on-line session. When the session is completed, the boiler control unit 20 operates autonomously, altering between the two modes of operation based on the time data contained in the data file.

Advantageously, the monitoring controller 27 is arranged to generate an output data file indicating the accumulated activated time of the heater control signal 8 through intervals corresponding to the intervals in which the delayed cycle controller is set in the first and second modes of operation, respectively.

The monitoring controller 27 is preferably arranged to generate and store in a memory an output data file, which indicates the accumulated on-time of the heater control signal 8 through intervals which correspond to the intervals in which the delayed cycle controller is set in the first and second modes of operation, respectively. This data file is downloadable to the computer 13 on request. An outdoor temperature sensor 24 is preferably provided to input a further measurement signal 25 to the monitoring controller 27. This outdoor temperature is not intended to be utilized in the boiler control process, but it is advantageously stored in a memory included in the output data file, in order to provide to the external computer 13 information about the outdoor temperature in periods corresponding to the intervals in which the delayed cycle controller is set in the first and second modes of operation, respectively.

The monitoring controller 27 is preferably arranged to acquire outdoor temperatures at a sampling rate that may be set from the external computer, e.g., every 10 seconds. The monitoring controller 27 is further arranged to calculate an average outdoor temperature for each period corresponding to the intervals in which the delayed cycle controller is set in the first and second modes of operation, respectively. The calculated average value of accumulated on-time of the burner through the interval is also stored in the output file.

The percentage value may be set and/or read out by the external computer 13 via the interface 26.

In a preferred implementation, the defayed cycle controller 21 and the monitoring controller 27 are functional modules implemented as software modules, for concurrently execution by a microcontroller employed in the control unit 20. The time delay register 22 and the memory for storing the input data file and the output data file are parts of a memory connected to the microcontroller. The memory comprises a random access memory for variable data and a non-volatile memory containing fixed data and program instructions. The implementation of the program instructions is an ordinary task for a person skilled in the art, based on the description given in this specification.

Although the heating device mention in the detailed description is an oil burner, the skilled person will also realize that the invention is applicable with other heating devices as well, e.g. an electrical heater or a gas heater.

Further variations and alternative embodiments will be evident for the person skilled in the art.

Claims

PATENT CLAIMS

1. Boiler control unit (20) for controlling a heating device (2) in a boiler (1), comprising a delayed cycle controller (21) for activating and deactivating said heating device (2), wherein

- said delayed cycle controller is operated by a thermal relay (6), providing a temperature responsive signal (7) which is switched on when the temperature in the boiler underpasses a lower temperature level and switched off when the temperature in the boiler exceeds a higher temperature level, and wherein

- said delayed cycle controller (21) is arranged to determine the cooling time of the boiler by measuring the time elapsing between the on-to-off transition and the off-to-on transition of the signal provided by the thermal relay, to deactivate the heating device (2) essentially at the point of time when the thermal relay signal is switched off, and in a first mode of operation, to activate the heating device (2) at a delay after the thermal relay signal is switched on, characterized in that the delayed cycle controller is further arranged to, in a second mode of operation , to activate the heating device (2) essentially at the point of time when the thermal relay signal is switched on, and that the control unit further comprises a monitoring controller (27), arranged to set the delayed cycle controller in said first and second modes of operation at predetermined points of time.

2. Boiler control unit (20) in accordance with claim 1, wherein the controller (21) is arranged to determine the delay as a certain percentage of the cooling time of the boiler.

3. Boiler control unit (20) in accordance with claim 1 or 2, further comprising a real time clock (28), providing current time and date information to the monitoring controller (27).

4. Boiler control unit (20) in accordance with one of the preceding claims, further arranged to calculate the accumulated activated time of the heater control signal (8) through an interval, indicating the total energy consumption of the heating process through said interval.

5. Boiler control unit (20) in accordance with claim 4, wherein said monitoring controller is arranged to generate a data file indicating the accumulated activated time of the heater control signal (8) through intervals corresponding to the intervals in which the delayed cycle controller is set in the first and second modes of operation, respectively.

6. Boiler control unit (20) in accordance with claim 5, wherein the monitoring controller (27) is further arranged to input a measurement signal (24) from an outdoor temperature sensor.

7. Boiler control unit (20) in accordance with claim 6, wherein the monitoring controller (27) is further arranged to calculate the average outdoor temperature value through an interval.

8. Boiler control unit (20) in accordance with claim 6, wherein said data file produced by the monitoring controller (27) further comprises average outdoor temperature values through intervals corresponding to the intervals in which the delayed cycle controller is set in the first and second modes of operation, respectively.

9. Boiler control unit (20) in accordance with one of the preceding claims, further arranged to communicate with an external computer (13) via a communication connection (14) and an mterface (26).

10. Boiler control unit (20) in accordance with claim 9, wherein said predetermined points of time for setting the delayed cycle controller in the first and second modes of operation are included in a data file input from the external computer (13).

11. Boiler control unit (20) in accordance with one of the claims 9-10, wherein the control unit (20) is further arranged to input and set by the external computer at least one of the following measures:

- time and date of said real time clock (28),

- said percentage,

- a point of time indicating a start of a monitoring period,

- a duration of each monitoring interval in the monitoring period, and

- a number of monitoring intervals included in the monitoring period.

12. Boiler control unit (20) in accordance with claim 11, wherein the control unit (20) is further arranged to calculate said predetermined points of time for setting the delayed cycle controller in the first and second modes of operation, respectively, by utilizing the point of time indicating the start of a monitoring period, the duration of each monitoring interval in the monitoring period, and the number of monitoring intervals included in the monitoring period.