JPH0490416A - Method and device for monitoring burner - Google Patents

Abstract

PURPOSE:To prevent the variation of sensitivity with the change of a gas composition, and to improve response by detecting the ignition or flame failure of a burner by measuring the relationship of the flow rate of a burner supply gas line or a supply air line and back pressure. CONSTITUTION:When the combustion port 1 of a burner is supplied with a gas from a gas supply pipe and the flow rate or the gas is kept contant, the indication pressure of a pressure(back pressure) gage 3 is lowered when flame failure (a) is generated, and ignition/flame failure can be detected because the indication pressure is made higher than that at the time of flame failure when ignition (b) is generated. The indicated values of the pressure gage 3 and a flowmeter 4 are reduced when the gas is brought to the state of ignition and the flow rate is small (a'), and the indicated values of the pressure gage 3 and the flowmeter 4 are increased when the gas is brought to the state of ignition and the flow rate is large (b)', but the inclinations of the indications of the pressure gage and the flowmeter coincide and the indicated values are lowered in either case. When flame failure (c)' is generated on ignition, on the contrary, the value of the pressure gage 3 is lowered, but the indication of the flowmeter 4 is remains high, and the indication difference of the flowmeter and back pressure is increased and frame failure and ignition are detected. The pressure detecting end of the pressure gage may be fitted to either of a gas supply line or an air supply line.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a monitoring system for various types of burners ranging from household to industrial use, such as heaters, boilers, water heaters, and even reheaters.

(Prior Art) Conventionally, in order to detect ignition or misfire (herein referred to as extinguishing of fire) of various burners, ■method using a flame eye that detects ignition or misfire with infrared or ultraviolet light, ■heat-sensitive method. How to detect with frame rod by formula,
The following methods are used: ■Method of detecting by electric current using the rectifying effect of flame, ■Method of using thermometer (thermocouple), ■Method of sonic analysis.

(Problems to be Solved by the Invention) However, each of the above items (1) to (2) has the following problems or difficulties.

In the methods (1) and (2) above, there is a fluctuation in sensitivity due to changes in gas composition, and false signals for misfire detection are likely to be generated. ■,
The temperature detection method (2) has problems with response and longevity, and (2) can only be used with loud burners (relatively large ones).

The present invention was developed in view of the difficulties and problems of these conventional methods, and there is no change in sensitivity due to changes in gas composition.
The purpose of the present invention is to provide a highly responsive burner ignition/misfire detection system.

(Means for Solving the Problems) The above-mentioned object of the present invention is to provide burner monitoring characterized in that burner ignition or misfire is detected by measuring the relationship between the flow rate and back pressure of a burner supply gas line or a supply air line. achieved by the method.

In the method of the present invention, the relationship between the flow rate of supply gas or air, the time of burner ignition or misfire, and the back pressure of the supply gas line or air line is investigated in advance, and the detected actual back pressure fluctuation is compared and calculated. to detect misfires and ignitions. This can be automated where appropriate.

In the present invention, the flow signal is used to cancel the flow dependent portion of the backpressure change when the flow rate of the supply gas or air is changed. That is, for those with load fluctuations, the signal generated by the flow rate detection mechanism and the back pressure signal are compared and calculated, and a misfire is determined by detecting that the difference between them is large during normal times and when a misfire occurs. If the burner has a constant load (flow rate), such as a pilot burner, only a mechanism (such as a pressure switch) that detects the difference in back pressure between ignition and misfire is required.

When the flow rate changes, the back pressure changes, so a method of changing the back pressure alarm setting depending on the flow rate may be used.

Further, the pressure gauge, that is, the pressure detection end may be provided in either the gas supply line or the air supply line.

The setting position of the pressure detection end is, for example, several centimeters to several tens of centimeters upstream from the combustion port of the burner, generally 5 to six centimeters.
1 to 50 to 60 cm is preferable.

Next, the present invention will be explained according to one embodiment shown in the drawings.

FIG. 1 shows a case where the flow rate of the burner is constant. In the figure, 1 indicates the combustion port of the burner, 2 indicates a gas supply pipe, and 3 and 4 indicate a pressure (back pressure) gauge and a flow meter, respectively.

Here, Fig. 1(a) shows the case of misfire, and Fig. 1(b) shows the case of misfire.
is in a state of ignition, and when ignition occurs, the indicated pressure on the pressure gauge becomes higher than when there is a misfire, so that ignition/misfire can be detected. The pressure increase at the time of ignition is, for example, several mmHa.
o ~ 10-odd mm) 120, generally 5-6 mmHao
None) L 15-16 mmHzO.

FIG. 2 shows a case where the burner has load fluctuations (flow rate fluctuations), and the same symbols as in FIG. 1 indicate the same things.

Figures 2 (a) and (b) are both in the ignition state, but the gas flow rate has been changed; in (a) the flow rate is small, and in (b)
has a large flow rate. (C) shows a state of misfire. To explain this, the flow rate in (a) is different from that in (b), but the difference in indication between the pressure gauge and the flow meter is small. That is (a)
Although the flow rate is small, the back pressure is also small. In (b), the flow rate is large, but the back pressure is also large. Therefore, in both cases, the indications of the pressure gauge and the flowmeter tend to match, and the difference in indications becomes small. On the other hand, in case C), due to a misfire, the pressure gauge value (back pressure) decreases, but the flow meter reading remains high, and the difference between the back pressure and flow meter reading becomes large, and a misfire or ignition is detected. .

The above explanation has been simplified, but specifically, a correction circuit and an arithmetic circuit are separately provided for the measured values of the pressure gauge and flow meter, and the relationship between the fixed values on both sides is established as a standard for the time of ignition and the time of misfire. Ignition or misfire can be detected by inputting and storing the information, comparing it with the actual measured value, and calculating whether or not the indicated difference is large.

FIG. 3 shows one embodiment in this case. In the figure, 11 is the combustion port of the burner, 12 is the gas supply pipe, 13 is the pressure gauge, 1
4 is a flow meter. 15 is a non-linear correction circuit that corrects the back pressure output of the pressure gauge, and the back pressure output that has passed through this is sent to the calculation circuit 16, where it is compared with the flow rate output from the flow meter 14 and its judgment is used to set alarms. It is sent to the device 17.

The components used in these embodiments may generally be a combination of commercially available instruments, or may be an integrated unit incorporating a dedicated measuring instrument and computing device.

Furthermore, as another method, it is also possible to employ a method that utilizes the back pressure of the exhaust gas flue. In this case as well, looking at the difference from the flow meter reading is the same as in the previous case.

(Effects of the Invention) Since the present invention detects pressure and flow rate, the response is so fast that it corresponds to the conventional flame eye method. Furthermore, the method and apparatus of the present invention have the advantageous effect that the influence of differences in combustion fluids is small and a relatively inexpensive and highly reliable system can be constructed.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of one embodiment of the burner monitoring system used in the method of the present invention, in which (a) is a misfire, (b)
indicates the time of ignition. FIG. 2 shows another embodiment of the burner monitoring system, in which (a) and (b) show the state at the time of ignition, and (c) show the state at the time of misfire. FIG. 3 is an explanatory diagram of yet another embodiment of the burner monitoring device used in the present invention. 1.11...Burner combustion port 2.12...Gas supply pipe 3.13...Pressure gauge 4.14...Flow meter 15...Nonlinear correction circuit 16...Arithmetic circuit diagram ↓ Figure Figure

Claims (2)

[Claims] (1) A burner monitoring method characterized by detecting burner ignition or misfire by measuring the relationship between the flow rate and back pressure of a burner supply gas line or supply air line. (2) A burner monitoring device characterized in that a flow meter and a pressure gauge are provided in a burner supply gas line or a supply air line, and burner ignition or misfire is detected from a change in the relationship between flow rate and back pressure.