JPS584035Y2 - Combustion safety device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a combustion safety device that is configured to detect that a burner combustion flame has become unstable due to a decrease in indoor oxygen concentration and activate a required mechanism. We have made it possible to provide sensitive lift characteristics during oxygen depletion even to fuel gas with a high burning rate, and to be able to detect this reliably and quickly, thereby achieving the desired degree of safety reliability. The aim is to provide a combustion safety device that can be improved.

For example, if an open combustion appliance such as a water heater is burned in a room with insufficient ventilation (for example, by forgetting to open a window), the oxygen concentration in the room will gradually decrease, and eventually the entire room will be destroyed. This results in a state of oxygen deficiency, leading to problems such as the generation of carbon monoxide due to incomplete combustion.

For this reason, various safety technologies have been proposed to detect unstable combustion in burners (lifting of the combustion flame) due to a decrease in indoor oxygen concentration, but all of them involve lifting the entire combustion flame. However, the reliability of safety was insufficient.

For example, compared to the main burner, the pilot burner originally suffers from an oxygen deficiency (hereinafter simply referred to as oxygen deficiency) due to input factors.

) is a combustion safety device that uses a thermocouple to detect when the pilot flame lifts and closes a solenoid valve installed in the fuel gas supply path. is better known than before.

However, since this device attempts to lift the entire combustion flame when oxygen is lacking, it is not effective for fuel gases such as LPG and natural gas, which have a slow combustion rate and are easy to lift. However, for fuel gases such as coal-based gas, which have a high combustion rate and are inherently difficult to lift, the reaction to oxygen deficiency may lag behind the point at which safe operation is actually required, making it difficult to achieve the desired level of safety. There is a lack of reliability.

As a means to eliminate this inconvenience, a part of the combustion exhaust gas is sucked and circulated into the burner to lower the oxygen concentration in the combustion air in advance, thereby creating combustion conditions that make it easier for the combustion flame to lift. However, in this case, a structure is needed to suck and circulate the combustion exhaust gas, which becomes a high-temperature updraft, against the rising force, or a structure that sucks and circulates the combustion exhaust gas, which becomes a high-temperature rising air, or a structure that sucks and circulates the combustion exhaust gas, which is a high-temperature rising air, and whose rising force has decreased due to heat radiation. Long exhaust gas suction pipes are required for suction circulation, which not only tends to complicate the structure, but also puts the entire combustion flame under conditions where it is easy to lift, making it difficult to ventilate the room indoors. It is difficult to stabilize the combustion flame so that it does not lift unexpectedly when the oxygen temperature is normal at 34 degrees, and there is a risk that the function as a pilot burner may be impaired.

The inventor of the present invention recognizes that the above-mentioned disadvantages are more or less unavoidable as long as the technical idea is to lift the entire combustion flame in the event of oxygen deficiency, and based on this recognition, As a result of research, we found that the primary flame (inner flame) and the two major flames (outer flame) of combustion flames have been used in combustion experiments since ancient times.
If we apply the principle of a flame separator that separates oxygen to oxygen deficiency safety measures, we will discover that large flames respond sensitively to decreases in oxygen concentration, and that large flame lifts can detect this. By devising a way to avoid interference by thermocouples, they were able to develop a combustion safety device that could increase the reliability of the desired safety, as in the official journal.

Detailing an embodiment of the present invention based on the drawings, FIG. 1 shows a water heater equipped with a combustion safety device to which the present invention is applied;
The combustion safety device includes a thermocouple 2 that is heated by the combustion flame of the pilot burner 1, an electromagnet M that is excited by the thermoelectromotive force of the thermocouple, and an electromagnet M that is attracted to the main burner 3 when the electromagnet M is excited. It consists of a solenoid valve MV that keeps the fuel gas supply path 4 open, and the combustion flame unexpectedly blows out, or, as described later, becomes unstable due to a decrease in the indoor oxygen concentration and the primary flame lifts. When,
It is configured to release the adsorption by the electromagnet M as the temperature of the thermocouple 2 decreases, and to shut off the fuel gas supply path 4 via the electromagnetic valve MV.

The pilot burner 1 is constructed as follows.

That is, as shown in FIG. 2, the supply amount of secondary air is controlled through a small hole 8a at the tip of an abbreviated mixing tube 7 which has a fuel gas jet nozzle 5 and a secondary air suction port 6 at its end. By limiting the combustion flame to the primary flame a and the two major flames, the cylinders 8 are connected in series, and when the indoor oxygen concentration is above the set value, the mixing tube A primary flame a is placed at the tip of the tube 7, and two large flames are formed at the tip of the cylinder 8. When the indoor oxygen concentration falls below the set value, the large flame a matches the two large flames. The air-fuel ratio of the secondary air and the fuel gas, the fuel gas flow rate, and the small hole 8a are adjusted so that the small hole 8a is lifted to the position.
. . . While setting the amount of secondary air supplied by the The thermocouple 2 is provided concentrically with the cylindrical body 8.

In the figure, 9 is a heat insulating material that prevents the mixing tube 7 from overheating, and 10 is a lock nut.

Next, the operation of the above configuration will be explained based on FIG. 3A and FIG. 4.

For example, when the fuel gas is coal-based gas, the flammability range of the air-fuel gas system is about 5 to 38%. is indicated by the cut point of the explosion limit line.

Fuel gas-air mixture ratio and small hole 8a...
If the amount of secondary air supplied is set to an appropriate value within this flammable range, for example, as shown at point A in FIG. The mixture is in the flammable range, and if the flow rate is set appropriately,
As shown in FIG. 3A, the large flame a and the two large flames can be formed separately at the tip of the mixing tube 7 and the tip of the cylindrical body 8.

This is the same principle as a flame separator, but unlike a flame separator, the oxygen concentration in the air decreases without changing the air-fuel ratio, resulting in large flame a as shown in Figure 3. It is possible to lift the condition.

That is, the pilot burner 1 is a Bunsen burner type and supplies primary air by ejecting fuel gas, so the volume ratio of air to fuel gas is kept almost constant, but when the oxygen concentration decreases, , as shown below, the same effect as when the -order air is squeezed is obtained.

When the indoor oxygen concentration decreases, that is, when combustion exhaust gas mixes into the air, the tip of the mixing tube 7 (i.e. -
The air-fuel mixture at the point where the large flame forms is A-A' in Figure 4.
Move along the line from A to A'.

Due to the characteristics of the Bunsen burner, the mixing ratio of air and fuel gas is approximately constant, so the line AA' is approximately parallel to the left side of FIG. 4 (the air-combustion exhaust gas side).

When the oxygen concentration falls below the set value, the operating point exceeds point B in Figure 4, and the air-fuel mixture at the tip of the mixing tube 7 cannot be combusted. The primary flame a is no longer formed at the cylindrical body 8, and the large flame a lifts to the tip of the cylindrical body 8.

At this time, the air/exhaust gas ratio is represented by point C in FIG.

In addition, in the actual pilot burner 1, due to the balance between the flow of the air-fuel mixture and the combustion speed, the formation region of the large flame a is narrower than the flammable range, for example, as shown by the dashed line in Fig. 4. Therefore, the change from the state in FIG. 3A to the state in FIG. 3A occurs at point B', and the air/exhaust gas ratio at this time becomes C'.

Therefore, when the indoor oxygen concentration is above the set value, the thermocouple 2 heated by the primary flame a excites the electromagnet M, as shown in Figure 3A, and the indoor oxygen concentration rises to the set value. If the temperature falls below, the thermocouple 2 will be exposed to the unburned air-fuel mixture, as shown in the opening of FIG. 3, so the temperature will drop and the electromagnet M will be demagnetized to ensure safety.

In this case, since the thermocouple 2 is installed concentrically inside the cylindrical body 8 as shown in the figure, the primary flame a, which is one foot from the tip of the mixing tube 7, is not obstructed by the thermocouple 2. It lifts to a position that matches the flame.

That is, when placing the thermocouple 2 at a predetermined detection point within the cylinder 8, a small hole may be provided in the peripheral wall of the cylinder 8 and the thermocouple 2 may be inserted from a direction perpendicular to the axis of the cylinder 8. However, if this is done, there is a risk that the primary flame a, which is separated from the tip of the mixing tube 7, may catch the thermocouple 2 on the way to the position of the primary flame, causing false detection. If they are arranged concentrically as shown in the figure, such a risk can be eliminated.

In summary, the combustion safety device according to the present invention detects that the combustion flame of the burner has become unstable due to a decrease in the indoor oxygen concentration and activates the required mechanism. In the safety device, a cylindrical body that separates the combustion flame into a primary flame and a primary flame by restricting secondary air is connected to the tip of the mixing tube of the burner, and
In order to use only the large flame as a flame for detecting a state of decreased oxygen concentration, a thermocouple for detecting the lift of the large flame is provided in the cylinder concentrically with the cylinder. It is something to do.

Due to this characteristic structure, various excellent effects as described below have been achieved.

In other words, (a) the secondary air is restricted and the combustion flame is separated into primary flames by simply installing a cylinder, which is an extremely simple and inexpensive structural addition; therefore, large flames are extremely flammable; Even if the fuel gas has a narrow range and is easy to lift, even if it is a fuel gas such as coal-based gas, which has a high combustion rate and is difficult to lift, only large flames will react sensitively to a decrease in indoor oxygen concentration. However, it can be easily lifted before reaching the oxygen concentration that actually requires safe operation, and (a)
Since the thermocouple is installed concentrically within the cylinder, disturbance of the air-fuel mixture flow can be suppressed as much as possible, and the formation of a large flame will not be inhibited. (1) For example, when a thermocouple is inserted from the side in the middle of a cylinder, the lifted primary flame does not get caught on the thermocouple on its way to the primary flame, causing a delay in detection. Furthermore, (1) Since the thermocouple is located along the longitudinal direction of the primary flame, - the troublesome work of accurately determining the maximum temperature point of the large flame and arranging the thermocouple can be eliminated. This assembly also has some advantages.

In addition, although this embodiment has been explained based on the ignition pilot burner 1 for the main burner 3, the ignition technology, pilot fire extinguishing safety device, and safety measures due to oxygen deficiency are as follows.
Since this is originally a different technology, the present invention is not limited to this.

[Brief explanation of drawings]

The drawings illustrate embodiments of the combustion safety device according to the present invention, and FIG. 1 is a schematic sectional view showing an example of use, FIG. 2 is a sectional view of the main parts, FIG. FIG. 4 is a triangular diagram of a three-component system of fuel gas, air, and combustion exhaust gas, showing the principle of the present invention. 1... Burner, 2... Thermocouple, 7...
...Mixing tube, 8...Cylinder, a...
-Major flame, b...Primary flame.

Claims (1)

[Scope of utility model registration request] A combustion safety device configured to detect that the combustion flame of the burner 1 has become unstable due to a decrease in indoor oxygen concentration and operate a necessary mechanism, the mixing pipe 7 of the burner 1
A cylindrical body 8 that separates the combustion flame into a primary flame a and a secondary flame by restricting secondary air is installed at the tip of the cylinder 8, and only the secondary flame a is used to detect a state of decreased oxygen concentration. A combustion safety device characterized in that a thermocouple 2 for detecting the lift of the secondary flame a is provided in the cylindrical body 8 concentrically with the cylindrical body 8 to be used as a flame.