WO2008084217A1

WO2008084217A1 - Boiler performance indicator

Info

Publication number: WO2008084217A1
Application number: PCT/GB2008/000052
Authority: WO
Inventors: Stephen D. Marchant
Original assignee: Marchant, Gordon
Priority date: 2007-01-09
Filing date: 2008-01-09
Publication date: 2008-07-17
Also published as: GB0700316D0

Abstract

A system, device and method for indicating the performance of a combustion boiler(l) used for heating water, the boiler comprising a burner(2), an air intake for the burner, a flue (3) for exhaust gas from the burner, and a water heating circuit having a flow heating water outlet(4) and heating water inlet (5), the water flowing within the boiler from the water inlet to water outlet past the burner. The system comprises a temperature sensor for obtaining a measurement of combustion air intake temperature (Ta) in the air intake for the burner; a temperature sensor for obtaining a measurement of flue gas temperature (Tg) in the flue for exhaust gas from the burner,- a temperature sensor for obtaining a measurement of heating flow water temperature (Tf ); and a temperature sensor for obtaining a measurement of heating inlet water temperature (Tr). A processor receives inputs from the temperature sensors and provides an output based on the obtained temperature measurements. An indicator (6) receives the output from the processor and provides an indication to a user relating to the performance of the combustion boiler.

Description

BOILER PERFORMANCE INDICATOR

Field of the Invention

The present invention relates to a device for indicating the change in performance (e.g. efficiency) of a combustion boiler.

Background

A typical domestic or small commercial combustion boiler can have an operational life of twenty years during which time its performance could degrade substantially from that when it was new. Generally no attempt is made, however, to measure or monitor the performance of such boilers in terms of operational efficiency. Instead, users rely on a regular service interval to maintain their boiler in good working order.

Larger industrial combustion boilers, on the other hand, are tested on a regular basis for efficiency. The testing process is, however, complex, requiring flue gas analysis, flow measurements and temperature monitoring in order to determine combustion efficiency and overall boiler efficiency. These testing methods require technicians with much expertise and expensive monitoring equipment that would be uneconomic for use on smaller combustion boilers.

Summary of the Invention

In general terms, embodiments of the present invention provide a device and a method for alerting a user to any degradation in the performance of a boiler based on measured temperature characteristics of the boiler.

In one aspect the invention provides a system for indicating the performance of a combustion boiler used for heating water, the boiler comprising a burner, an air intake for the burner, a flue for exhaust gas from the burner, and a water heating circuit having a flow heating water outlet and heating water inlet, the water flowing within the boiler from the water inlet to water outlet past the burner, the system comprising: a temperature sensor for obtaining a measurement of combustion air intake temperature in the air intake for the burner; a temperature sensor for obtaining a measurement of flue gas temperature in the flue for exhaust gas from the burner; a temperature sensor for obtaining a measurement of heating flow water temperature; a temperature sensor for obtaining a measurement of heating inlet water temperature; a processor for receiving inputs from the temperature sensors and to provide an output based on the obtained temperature measurements; and an indicator for receiving the output from the processor and providing an indication to a user relating to the performance of the combustion boiler. In another aspect the invention provides a boiler performance indicator for indicating the performance of a combustion boiler used for heating water, the boiler comprising a burner, an air intake for the burner, a flue for exhaust gas from the burner, and a water heating circuit having a flow heating water outlet and heating water inlet, the water flowing within the boiler from the water inlet to water outlet past the burner, the boiler performance indicator comprising: a processor for receiving temperature measurement inputs from a set of temperature sensors and to provide an output based on the obtained temperature measurements; and an indicator for receiving the output from the processor and providing an indication to a user relating to the performance of the combustion boiler, the set of temperature sensors comprising: a temperature sensor for obtaining a measurement of combustion air intake temperature in the air intake for the burner; a temperature sensor for obtaining a measurement of flue gas temperature in the flue for exhaust gas from the burner; a temperature sensor for obtaining a measurement of heating flow water temperature; and a temperature sensor for obtaining a measurement of heating inlet water temperature.

In another aspect the invention provides a method for indicating the performance of a combustion boiler used for heating water, the boiler comprising a burner, an air intake for the burner, a flue for exhaust gas from the burner, and a water heating circuit having a flow heating water outlet and heating water inlet, the water flowing within the boiler from the water inlet to water outlet past the burner, the method comprising: obtaining a measurement of combustion air intake temperature in the air intake for the burner; obtaining a measurement of flue gas temperature in the flue for exhaust gas from the burner; obtaining a measurement of heating flow water temperature; obtaining a measurement of heating inlet water temperature; and processing the temperature measurements to provide an indication to a user relating to the performance of the combustion boiler.

A number of optional and preferred features of the various aspects of the invention are apparent from the description below and are set out in the dependent claims further below.

The BPI (Boiler Performance Indicator) of the various aspects of the invention provides a relatively inexpensive way of measuring any degradation in boiler performance by monitoring the temperature characteristics of a boiler with an indicator to warn the user of any degradation in performance allowing more timely corrective action. The BPI, with its indicator, will alert the user to its current performance state. A device capable of displaying text and numerals may be used, for example on larger boilers, to give more detailed temperature and performance information.

The concepts of the invention can be applied to a variety of different types of boiler, including central heating boilers and hot water boilers. In the case of hot water boilers, the heating water inlet will typically be an inlet for cold water, e.g. from a mains supply, the water heating circuit being an open circuit (the hot water flowing out through taps, showers, etc). In the case of central heating boilers, the water heating circuit will typically be a closed circuit, wherein the heating water inlet is a return heating water inlet (the heating water circulating from the boiler outlet, through the central heating - i.e. radiator - system, and back to the return heating water inlet of the boiler).

In some cases it may be possible to use only a single water temperature sensor (e.g. only a water outlet temperature sensor) but generally this will provide much less accurate results.

Brief Description of the Drawings

The invention is described below by way of example with reference to the accompanying drawings, in which:

Fig 1 shows a schematic of a combustion boiler and the associated temperature measurements and a boiler performance indicator (BPI) in accordance with an embodiment of the present invention;

Fig 2 shows the inputs and outputs to a BPI microprocessor based device of an embodiment of the present invention; and

Fig 3 shows a three-dimensional lookup table where temperature data is stored in non-volatile memory of the BPI microprocessor based device of fig. 2.

Detailed Description

In figure 1 , a schematic shows a combustion boiler 1 , a single or multi-stage burner 2, the flue 3, the flow heating water 4, the return heating water 5, and a BPI indicator device 6. The following temperature sensor inputs are indicated:

Ta Combustion air intake temperature

Tg Flue gas temperature or adjacent point via a heat sink

Tf Heating flow water temperature

Tr Heating return water temperature If available, the BPI will also have a digital input to sense the boiler firing and further inputs for a boiler with a multi-stage burner.

As the boiler is fired up, the heat of combustion is transferred through a heat exchanger to the heating circuit, with any remaining heat lost through the flue. Measurement of the flue gas temperature in relation to the air intake temperature (Ta) and flow (Tf) and return (Tr) water temperature gives an indication of boiler performance.

In figure 2, The microprocessor based device 1, has a power input 2, temperature sensor inputs (Ta , Tg , Tf , Tr ), optional boiler firing rate input 3, performance indicator or display output 4, and an optional output for remote data acquisition 5. The device and sensors can be fitted within the boiler at manufacture or retro-fitted externally.

In figure 3, as the boiler is first installed and fired up, the BPI non-volatile lookup table is filled with the following corresponding temperature data: Tw which is the average of Tf and Tr ; Tg or near heat sink point temperature; and Ta.. The heat sink can be a point near the flue which is a relative but lower temperature measurement. If there is a multi-stage burner (i.e. different firing-rate modes) there would be a corresponding lookup table for each firing rate.

There is sufficient non-volatile memory to store the above temperature data in one or more of these three-dimensional lookup tables. As temperature data is built up in the lookup table it will form a reference against which to measure any future performance. The temperature data may be built up, for instance, over a single heating season (e.g. winter). Alternatively, the data could be developed over a longer period of time, e.g. as the boiler experiences different climatic and heating demand conditions, to more fully populate the lookup table(s).

In order to ensure the data in the lookup table(s) is valid there will preferably be an algorithm for averaging the temperature readings and rejecting any readings that are outside of any required tolerance. The algorithm could, for example be a smoothing algorithm (i.e. adjustable number for moving average) for real time temperature readings. In some cases, data points might only be accepted for entry in a lookup table when there were a number of (e.g. two or three) consecutive readings for the same or very similar values over a period of operation.

In some embodiments, the lookup table(s) can be pre-populated (i.e. before operational use) with reference temperature data, derived for example from factory / laboratory tests. In this case the pre-populated data can be maintained for the life of the system or, alternatively, reference values measured whilst the boiler is in service can be used to supplement or even replace (partially or fully) the pre-populated data. Any degradation in performance is determined by measuring the relative change in flue gas (Tg) temperature corresponding to the air intake (Ta) and average of flow and return water (Tw) temperatures in the lookup table. The particular point shown is one of many stored in the reference table. For example, a lookup table with a resolution of 10C and temperature ranges of 500C would have a maximum of 125000 (i.e. 50x50x50) such reference points. Where a measured temperature falls between points stored in the lookup table, the device can interpolate between those points or, for example, pick the closest actual point. In other cases, as generally the temperature rise is being measured 'on the rise' the system can latch on to an exact reference point in the lookup table to make the comparison.

On the simplest display a green LED will indicate that the boiler is operating near its original performance. An amber LED will indicate that it is slightly off its original performance (e.g. 2% change in flue gas temperature). A red LED would indicate that it is further away from its original performance (e.g. >5% change in flue gas temperature). A more elaborate display (e.g. LCD) can be used to numerically indicate performance degradation. It could also display the temperature sensor readings and boiler operation hours.

Various modifications to the specifically described embodiment are possible within the scope of the invention. For instance, although the description above is most applicable to a central heating boiler, in which outlet water from the boiler is pumped around a central heating circuit and returns to the boiler water inlet, the concepts of the invention are equally applicable to a hot water boiler in which the water inlet of the boiler is a cold water inlet, e.g. connected to a mains water supply.

Claims

Claims:

1. A system for indicating the performance of a combustion boiler used for heating water, the boiler comprising a burner, an air intake for the burner, a flue for exhaust gas from the burner, and a water heating circuit having a flow heating water outlet and heating water inlet, the water flowing within the boiler from the water inlet to water outlet past the burner, the system comprising: a temperature sensor for obtaining a measurement of combustion air intake temperature in the air intake for the burner; a temperature sensor for obtaining a measurement of flue gas temperature in the flue for exhaust gas from the burner; a temperature sensor for obtaining a measurement of heating flow water temperature; a temperature sensor for obtaining a measurement of heating inlet water temperature; a processor for receiving inputs from the temperature sensors and to provide an output based on the obtained temperature measurements; and an indicator for receiving the output from the processor and providing an indication to a user relating to the performance of the combustion boiler.

2. A system according to claim 1 , further comprising a memory for storing one or more reference temperature values and wherein the processor output is determined by comparing the obtained temperature measurements and / or temperature values derived from those measurements with the stored reference temperature values.

3. A system according to claim 2, wherein the stored reference temperature values comprise values in a lookup table relating flue gas temperature to combustion air intake temperature and an average water temperature, the average water temperature being an average of heating flow water temperature and heating inlet water temperature, and wherein the processor output is determined by comparing obtained measurements of flue gas temperature and combustion air intake temperature, and an average of the obtained measurements of heating flow water temperature and heating inlet water temperature, with the stored reference temperature values.

4. A system according to claim 2 or claim 3, wherein the processor output causes the indicator to indicate to the user a degradation in performance of the boiler when, for any given air intake temperature and average water temperature, the obtained measurement of flue gas temperature differs from the stored reference value for the flue gas temperature by more than a predetermined threshold.

5. A system according to claim 4, wherein the predetermined threshold is a change in flue gas temperature from the stored reference value of 2% or more.

6. A system according to claim 4 or claim 5, wherein the processor output causes the indicator to indicate to the user a more serious degradation in performance of the boiler when, for any given air intake temperature and average water temperature, the obtained measurement of flue gas temperature differs from the stored reference value for the flue gas temperature by more than a second predetermined threshold, the second threshold being greater than the first threshold.

7. A system according to claim 6, wherein the predetermined threshold is a change in flue gas temperature from the stored reference value of 5% or more.

8. A system according to any one of claims 2 to 7, wherein the reference values are obtained from measurements taken using the temperature sensors during an initial period of boiler use after it is first installed.

9. A system according to any one of the preceding claims, wherein the burner is a multistage burner.

10. A system according to any one of the preceding claims, further comprising one or more sensors to sense boiler firing and to provide an input to the processor from which a burner firing rate can be determined.

11. A system according to claim 10, wherein the reference temperature values are stored in a plurality of lookup tables corresponding to different boiler firing rates.

12. A system according to any one of the preceding claims, wherein the indicator provides a visual indication of boiler performance.

13. A system according to claim 12, wherein the indicator is adapted to selectively display three visual signs to indicate acceptable, degraded and seriously degraded boiler performance respectively.

14. A system according to claim 12 or claim 13, wherein the indicator is adapted to display a numerical indication of performance degradation.

15. A system according to any one of claims 12 to 14, wherein the indicator is adapted to display one or more of the obtained temperature measurements and / or the boiler operation hours.

16. A system according to any one of the preceding claims, wherein the flue gas temperature is the temperature of a heat sink adjacent and in thermal contact with the flue.

17. A boiler performance indicator for indicating the performance of a combustion boiler used for heating water, the boiler comprising a burner, an air intake for the burner, a flue for exhaust gas from the burner, and a water heating circuit having a flow heating water outlet and heating water inlet, the water flowing within the boiler from the water inlet to water outlet past the burner, the boiler performance indicator comprising: a processor for receiving temperature measurement inputs from a set of temperature sensors and to provide an output based on the obtained temperature measurements; and an indicator for receiving the output from the processor and providing an indication to a user relating to the performance of the combustion boiler, the set of temperature sensors comprising: a temperature sensor for obtaining a measurement of combustion air intake temperature in the air intake for the burner; a temperature sensor for obtaining a measurement of flue gas temperature in the flue for exhaust gas from the burner; a temperature sensor for obtaining a measurement of heating flow water temperature; and a temperature sensor for obtaining a measurement of heating inlet water temperature.

18. A boiler performance indicator according to claim 17, further comprising a memory for storing one or more reference temperature values and wherein the processor output is determined by comparing the obtained temperature measurements and / or temperature values derived from those measurements with the stored reference temperature values.

19. A boiler performance indicator according to claim 18, wherein the stored reference temperature values comprise values in a lookup table relating flue gas temperature to combustion air intake temperature and an average water temperature, the average water temperature being an average of heating flow water temperature and heating inlet water temperature, and wherein the processor output is determined by comparing obtained measurements of flue gas temperature and combustion air intake temperature, and an average of the obtained measurements of heating flow water temperature and heating inlet water temperature, with the stored reference temperature values.

20. A boiler performance indicator according to claim 18 or claim 19, wherein the processor output causes the indicator to indicate to the user a degradation in performance of the boiler when, for any given air intake temperature and average water temperature, the obtained measurement of flue gas temperature differs from the stored reference value for the flue gas temperature by more than a predetermined threshold.

21. A boiler performance indicator according to claim 20, wherein the predetermined threshold is a change in flue gas temperature from the stored reference value of 2% or more.

22. A boiler performance indicator according to claim 20 or claim 21 , wherein the processor output causes the indicator to indicate to the user a more serious degradation in performance of the boiler when, for any given air intake temperature and average water temperature, the obtained measurement of flue gas temperature differs from the stored reference value for the flue gas temperature by more than a second predetermined threshold, the second threshold being greater than the first threshold.

23. A boiler performance indicator according to claim 22, wherein the predetermined threshold is a change in flue gas temperature from the stored reference value of 5% or more.

24. A boiler performance indicator according to any one of claims 18 to 23, wherein the reference values are obtained from measurements taken using the temperature sensors during an initial period of boiler use after it is first installed.

25. A boiler performance indicator according to any one of claims 18 to 24, wherein the reference temperature values are stored in a plurality of lookup tables corresponding to different boiler firing rates.

26. A boiler performance indicator according to any one of claims 17 to 25, wherein the indicator provides a visual indication of boiler performance.

27. A boiler performance indicator according to claim 26, wherein the indicator is adapted to selectively display three visual signs to indicate acceptable, degraded and seriously degraded boiler performance respectively.

28. A boiler performance indicator according to claim 26 or claim 27, wherein the indicator is adapted to display a numerical indication of performance degradation.

29. A boiler performance indicator according to any one of claims 26 to 28, wherein the indicator is adapted to display one or more of the obtained temperature measurements and / or the boiler operation hours.

30. A boiler performance indicator according to any one of claims 17 to 29, wherein the flue gas temperature is the temperature of a heat sink adjacent and in thermal contact with the flue.

31. A method for indicating the performance of a combustion boiler used for heating water, the boiler comprising a burner, an air intake for the burner, a flue for exhaust gas from the burner, and a water heating circuit having a flow heating water outlet and heating water inlet, the water flowing within the boiler from the water inlet to water outlet past the burner, the method comprising: obtaining a measurement of combustion air intake temperature in the air intake for the burner; obtaining a measurement of flue gas temperature in the flue for exhaust gas from the burner; obtaining a measurement of heating flow water temperature; obtaining a measurement of heating inlet water temperature; and processing the temperature measurements to provide an indication to a user relating to the performance of the combustion boiler.

32. A method according to claim 30, further comprising storing one or more reference temperature values and wherein the processing step comprises comparing the obtained temperature measurements and / or temperature values derived from those measurements with the stored reference temperature values.

33. A method according to claim 32, wherein the stored reference temperature values comprise values in a lookup table relating flue gas temperature to combustion air intake temperature and an average water temperature, the average water temperature being an average of heating flow water temperature and heating inlet water temperature, and wherein the processing step comprises comparing obtained measurements of flue gas temperature and combustion air intake temperature, and an average of the obtained measurements of heating flow water temperature and heating inlet water temperature, with the stored reference temperature values.

34. A method according to claim 32 or claim 33, comprising indicating to the user a degradation in performance of the boiler when, for any given air intake temperature and average water temperature, the obtained measurement of flue gas temperature differs from the stored reference value for the flue gas temperature by more than a predetermined threshold.

35. A method according to claim 34, wherein the predetermined threshold is a change in flue gas temperature from the stored reference value of 2% or more.

36. A method according to claim 34 or claim 35, comprising indicating to the user a more serious degradation in performance of the boiler when, for any given air intake temperature and average water temperature, the obtained measurement of flue gas temperature differs from the stored reference value for the flue gas temperature by more than a second predetermined threshold, the second threshold being greater than the first threshold.

37. A method according to claim 36, wherein the predetermined threshold is a change in flue gas temperature from the stored reference value of 5% or more.

38. A method according to any one of claims 32 to 37, wherein the reference values are obtained from measurements taken during an initial period of boiler use after it is first installed.

39. A method according to any one of the claims 31 to 38, wherein the burner is a multi-stage burner.

40. A method according to any one of claims 31 to 39, further comprising sensing boiler firing to provide an input to the processing step from which a burner firing rate can be determined.

41. A method according to any one of claims 32 to 240, wherein the reference temperature values are stored in a plurality of lookup tables corresponding to different boiler firing rates.

42. A method according to any one of claims 31 to 41 , wherein the indication is a visual indication of boiler performance.

43. A method according to claim 43, wherein the indication is given on an indicator that is adapted to selectively display three visual signs to indicate acceptable, degraded and seriously degraded boiler performance respectively.

44. A method according to claim 42 or claim 43, wherein the indication is given on an indicator that is adapted to display a numerical indication of performance degradation.

45. A method according to any one of claims 42 to 44, wherein the indication includes one or more of the obtained temperature measurements and / or the boiler operation hours.

46. A method according to any one of claims 31 to 45, wherein the flue gas temperature is the temperature of a heat sink adjacent and in thermal contact with the flue.