JPS60162123A - Combustion safety device for burner - Google Patents

Abstract

PURPOSE:To enable quick stop of combustion when oxygen concentration is decreased, by a method wherein poor combustion of a burner is made easy to occur through intermittent decrease in the excess rate of a primary air. CONSTITUTION:Switching of a blower 3 to an intermittent low rotation is controlled by an interval timer circuit 28, a time required for counting made the specified number of times is reduced to, for example, 1.5min, and the output of an output terminal 29a is switched to a high level again 1.5min later. Switching of the blower 3 from high rotation to low rotation results in a decrease in the excess rate of a primary air of an auxiliary burner 6 to, for example, 0.7. If oxygen concentration is reduced to 16-18%, poor combustion occurs to the auxiliary burner 6 to detect such poor combustion by means of a second thermocouple 18, and with an electromagnetic safety valve 7 closed, combustion is brought to a stop. As noted above, by means of signals from sensors 17 and 18 which detect poor combustion during intermittent combustion by which a decrease in the excess rate of the primary air is caused, combustion is brought to a stop, resulting in ensurance of safety.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion safety device for a combustor, and more specifically, the present invention relates to a combustion safety device for a combustor. The present invention relates to a combustion safety device in a combustor having a combustion region in which the burner is operated by maintaining the total amount of air at a relatively high value of 1 or more or around 1.

Conventionally, there are sensors that detect oxygen-deficient combustion in the burner, and there are combustion safety devices that completely stop combustion in the burner based on the detection signal from the sensor, but one that is known is that the primary air excess ratio is 1.
If the burner is operated at a relatively high value above or near 1, poor combustion of the burner will occur when the oxygen concentration of the guide air decreases. When set to about 16 to 1 of the oxygen concentration
A drop to 8% will cause a lift-up phenomenon due to oxygen deficiency, whereas if the N primary air excess ratio is set to about 0.9, the lift-up phenomenon will occur unless the oxygen concentration falls to about 15% below the allowable level. This is accompanied by the inconvenience of a delay in stopping the combustion of the burner in the event of oxygen deficiency.

In order to eliminate all such inconveniences, the present invention provides a system in which the primary excess air ratio is constantly reduced, which tends to cause poor combustion in the burner.
The object of the present invention is to provide a device that can quickly stop combustion in a burner when the oxygen concentration decreases, and will be described below with reference to fully illustrated embodiments of the present invention.

Figures 1 and 2 show the hot air gas heater in its entirety, with Vc inside the heater body (1) having an inlet (1aJ) on the back and a hot air outlet (1b) on the front. and the outlet (1b
An inner case +2J is provided to communicate with the inner case (2J).
) houses a blower (3) and a combustion case (4) above it, and a pair of main and sub burners (5) (6) are housed in the combustion case (4).
), and according to the operation of the blower (3), the suction port (
As indoor air is sucked in from 1a), the combustion chamber (4)
The combustion hot air is sucked and exhausted from the upper exhaust port (4aJ).
1Ii1 people are mixed in the inner coove (2) so that warm air is blown into the room from the outlet (1bJ),
At this time, each burner (51 (61 has its combustion surface (5a)
(6aJ) The suction force of the cough blower (3) acting on the inside of each flame hole opens the primary air hole (5b) (6b) at the end of the mixing pipe of each burner f51 (61) into the combustion Next, air was forced to be supplied.

Referring to FIG. 2, the gas circuit is connected to the cough sub-burner (6) via the electromagnetic safety valve (7), gas cock (8), and governor (9).
) A configuration is configured to supply henogas and further gas from the governor (9) to the cough main burner (5) via the temperature control solenoid valve (00), and a signal from the temperature control circuit Uυ to be described later. Switch between weak combustion in which the solenoid valve 00) is closed and only the auxiliary burner (6) is operated for combustion, and strong combustion in which the solenoid valve 00) is opened and both the main and auxiliary burners f5+16)'e are combusted. In addition to being freely controllable, the rotation of the blower (3) is also controlled to be switched between strong and weak directions in synchronization with this switching of the strong and weak directions.

Then, the opening degree of each of the primary air holes (51) (6D) is set appropriately so that the primary air excess ratio is 1 in the main burner (5).
．． 2, and hold it at about 0.9 with the auxiliary burner (6). Here, the primary air excess ratio of the main burner (5) is set to 1 or more in order to reduce the Hox concentration in the exhaust gas, as known from Japanese Patent Application Laid-Open No. 1157-192740, and ) is set to 0.9 in order to prevent combustion from becoming unstable when switching between strengths and weaknesses.

That is, the suction force of the primary air by the blower (3) changes depending on the internal pressure of the combustion case (4), and when switching from weak to strong, the internal pressure of the combustion case (4) changes from the level of weak combustion to strong. In the transient state until the level increases to the level during twisting, excessive suction force due to the strong rotation of the blower (3) acts on the secondary burner (6), causing
The primary excess air ratio temporarily increases by VC, and when switching from strong to weak, the primary excess air ratio temporarily decreases, contrary to this phenomenon. In order to keep the amount within the range of 0.5 to 1.4 necessary for stable combustion, the range of increase and decrease is estimated in advance, and VC is set at about 0.9, which is in the middle.

FIG. 5 shows a control circuit equipped with the above-mentioned temperature control circuit 0υ.The temperature control circuit (11J) is connected to the output side of the constant voltage circuit - which is energized when the main switch (12+) is closed. The first output terminal (1
The temperature control solenoid valve (10) is configured to output a high-level strong twist firing signal and a low-level weak combustion signal to 1aJ.
The base of the first transistor Q41 is connected to the base of the first transistor Q41 which intervenes in common in the energization (b) path between the first relay R1 for opening/closing control of the first relay R1 and the second relay R1 for controlling the rotation of the transmitter M and the machine (3). When the output terminal (111) is connected, according to the output of the strong twist signal, the first transistor circle is turned on, and the first and second relay R1
The relay switch of the first relay R1 is energized.
l is turned on and the solenoid valve 00) is opened, and the relay switch r of the second relay R2 is switched to the strong rotation terminal a side of the drive motor (3aJ) of the blower (3), and the blower (3) is turned on. ) is rotated strongly and a weak combustion signal is output.
The first transistor Q41 is turned off, and the first and second relays R, R, are de-energized, and the f'LNIJ race switch r1 is turned off, and the solenoid valve QOI is closed, and the relay switch r2 is turned off. Air is blown by switching to the rotating terminal side.
(3) Made it rotate weakly. In the drawing, country 0 shows all the bimetal switches in parallel with the main switch a'aVC, which is closed in conjunction with the main switch a'aVC, and a61, which is connected to the main switch.

In addition, the drawing shows a thermocouple as a defective combustion detection sensor installed in the main burner (5) and the sub burner (6) at 071 (1119). The first thermocouple α7) facing the eye side burner (6) and the second thermocouple facing the eye side burner (6)
When the electromotive force of some thermocouples drops below the standard level, or during weak combustion, the electromotive force of the second thermocouple (181) increases regardless of the electromotive force of the first thermocouple Q7). When the temperature drops below the standard level, the electromagnetic safety valves (7) are activated (U).To explain this in more detail, the electromotive force of the first and second thermocouples (1, 7) as is Amplifying circuit (1) connects the first comparator CD for the first thermocouple αη and the second thermocouple a
The third comparator on the input side of the comparator (goods) turns on and off the second transistor (c) connected in series to the safety valve +71i and its solenoid.
When the transistor (2) is turned off, the output from the comparator (to) becomes low level, so that when the second transistor (24) is turned off, the valve is closed, and the third transistor (C) is turned off. The output terminal of the second comparator Q is connected to the voltage application circuit (2) connected to the base, and the output terminal of the first comparator (Q) is connected to the output terminal of the second comparator (Q) through the fourth transistor (@) which is turned on by the strong combustion signal from the temperature control circuit (aυ). During strong twist firing, one of the main and sub burners f51 +61 may lift up due to misfire or poor combustion, causing the first and second thermocouples QηQa to
When the electromotive voltage of some of the l is completely below the reference value, and correspondingly, the output of the first and second comparators Cυ (either one of the two becomes low level, it is applied to the it pressure applying circuit through its internal circuit). C26
1 is grounded, the third transistor (C) is turned off, and the electromagnetic safety valve (7) is closed.In addition, during weak combustion, the fourth transistor (5) is turned off, and the second comparator (C) is turned off. ) The fifth transistor (c) is now controlled on and off by the mini of the solenoid safety valve (c) when its output reaches low 17 bells.
7) is closed.

Combustion safety measures are taken with the above configuration, but when the primary air excess ratio is set to a value of 1 or more or a value close to 1 of about 0.9 as described above, due to a decrease in the oxygen concentration of the guide air. In this case, it is difficult to completely stop combustion before the oxygen concentration drops below the permissible level.

Therefore, in the present invention, the primary excess air ratio is intermittently reduced during the combustion operation in the region where the primary nitrogen excess ratio is maintained at a relatively high value as described above, and this reduction causes the oxidation This makes it easier to generate defective combustion noises during interruptions, so that combustion can be stopped early.

There are two ways to completely reduce the primary air excess ratio: one is to increase the amount of gas without changing the amount of primary air supplied, and the other is to reduce the amount of primary air supplied without changing the amount of gas. ,
In the illustrated example, the latter method is followed and a blower (
3) Use a weak rotation system for all songs, reduce the primary air supply amount, and intermittently set the primary air excess rate to 0 using the sub burner (6).
．． It was reduced from 9 to about 0.7.

In addition, the primary excess air ratio of the main burner (6) is also 1.
．． At this level, poor combustion will not occur unless the oxygen concentration drops to 15% or less, and the sub burner (6) will be effective in preventing oxygen deficiency. .

The intermittent switching of the blower (3) to low rotation is controlled by an interval timer circuit (c).To explain in full detail, the cough timer circuit @ is the 2
The main burner output terminal (11bJ) is operated by the ignition signal of the main burner (51) to count the number of oscillations of the built-in oscillation circuit. The output terminal of the timer 0 @ (the fifth transistor whose base is all connected to 29aJ) is inserted into the energizing circuit of the relay R2, and all capacitors 6 of the OR circuit are connected.
υ and a first and second resistor 02 (c) connected thereto in parallel, and connected to the collector side of the fifth transistor via the second resistor (2) and all diodes. When connected to the high level output from the output terminal (29-), the fifth transistor □□□ is turned on and the second relay R1 is turned on.
The fifth transistor (c) and the first transistor (alpha) are fully energized and the blower (3) is strongly rotated.
7) It is grounded via Q41, and the capacitor 0υ and the first resistor 02. It is set to a relatively long period determined by - After counting the number of steps,
For example, after 15 minutes, the output of the output terminal (29) becomes low level, and according to this low level output, K
5 transistor (to) is turned off and the second relay R is de-energized, the blower (3) is switched to weak rotation, and at this time, the capacitor 01) and the first and second resistor 020J are connected to each other during the oscillation period by the OR circuit. For example, the time required to count a certain number of times can be set to a relatively short cycle determined by n.
5 minutes, and after 1.5 minutes the output terminal (29a
The output of J was switched to a high level, and after 1, the above operation was repeated so that the blower (3) was switched to low rotation for 1.5 minutes at 15 minute intervals.

Therefore, when the blower (3) is switched from strong rotation to weak rotation, the primary air excess ratio of the auxiliary burner (6) decreases from 0.9 to approximately 0.7.1 In this state, oxygen concentration is 15
Even if it does not drop below 16%, if it drops to 16-18%, a bad combustion sound will occur in the auxiliary burner (6), which can be detected by the second thermocouple, and the electromagnetic safety valve (7) will be closed. Combustion is stopped.

In the illustrated example, the primary air excess ratio of the auxiliary burner (6) is maintained at a relatively high value of about 0.8 to 0.9 even during weak combustion; The rotation of the blower (3) may be further reduced from low rotation to reduce the primary air flow rate all the time;
) When the combustion amount of Changed the rotation speed to low speed.

As described above, according to the present invention, the primary air excess ratio is maintained at a relatively high value of 1 or more or around 1, and the primary air excess ratio is intermittently reduced during combustion operation. So, is there poor combustion during intermittent combustion when the oxygen concentration decreases and the primary air excess rate is reduced? Combustion is stopped by a signal from a sensor that detects one defective combustion, which has the effect of providing safety by preventing early combustion stop in the event of oxygen deficiency.

[Brief explanation of drawings]

Fig. 1 is a cutaway side view of an example of a combustor to which the present invention is applied, Fig. 2 is a front view taken along the line ■-■ in Fig. 1, and Fig.
The figure is a diagram showing the control circuit.

Claims (1)

[Claims] A combustor in which all of the primary air for combustion is forcibly supplied to the burner, the 11th air excess ratio is maintained at a relatively high value of 1 or more or around 1, and the burner is operated for full combustion in the combustion region. In a device equipped with a sensor that detects poor combustion and completely stops combustion in the burner based on a detection signal from a cough sensor, the primary air excess ratio is intermittently reduced during combustion operation in the combustion region. A combustion safety device for a combustor that provides a warning sign that something has happened.