JPS60235915A - Burning safety device - Google Patents

Abstract

PURPOSE:To make steadier the safety for burning of the titled device by a method wherein a flame detecting element is provided at the upper position of flame hole where a mixed gas flow rate of a surface burning burner is highest, or where a primary air quantity is least. CONSTITUTION:A mixed gas is jetted from a flame hole part of the top end of a surface burning burner 1. The jetted gas has a larger flow rate, that is, a larger burning quantity compared with the mixed gas jetted from other flame hole group, and the primary air ratio thereof is rather less. A flame rod 6 is formed at the top end of said surface burning burner. When a flame is unsteady, a flame information is sent to a comparing circuit 8 from the flame rod 6 and an oxygen concentration sensor 7, compared with a presetting value under the steady burning condition. If the presetting value is not satisfied, a solenoid valve 10 is closed with a driving circuit 9. Under the condition of oxygen deficiency or primary air shortage, the oxygen concentration sensor 7 mainly sent the rapid information to the comparing circuit 8. Thereby, the steady and safe burning can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the safety of surface combustion burners whose flame holes are wire mesh, punched plates or ceramic plates.

2. Description of the Related Art Structures of Conventional Examples and Their Problems In recent years, gas and oil fan heaters have been widely used as home heating appliances due to their economic efficiency and safety. Since these fan heaters release combustion exhaust gas into the room, they are required to ensure safety against combustion as well as cleanliness of the combustion exhaust gas.

One conventional hot air heating system has extremely excellent performance in terms of cleanliness and eliminates nitrogen oxides (hereinafter referred to as NOx).
) rarely occurs.

Also, regarding safety, with the installation of an oxygen concentration sensor,
Combustion can be stopped before incomplete combustion occurs. However, although the oxygen concentration sensor has excellent responsiveness to changes in oxygen partial pressure, the responsiveness to temperature changes is not necessarily good because the heat capacity of the ceramic or the like that protects the sensor is large. For this reason, using the oxygen concentration sensor not only to detect the oxygen concentration in exhaust gas but also to detect the presence or absence of flame above the flame hole, that is, to detect ignition misfire, will increase the flow of raw gas into the room. This is not desirable in terms of health and safety. On the other hand, flame rods and thermocouples, which are widely used as flame detection elements, are faster in detecting ignition and misfire than oxygen concentration sensors. However, all 1
For secondary surface combustion, it is difficult to indirectly estimate the oxygen concentration in the room or atmosphere by detecting the ion density and flame temperature in the flame for the following reasons. Equivalence ratio φ
The characteristics of ion density and flame temperature for ion density and flame temperature are upwardly convex characteristics that show a peak when the equivalence ratio φ is around 1. Therefore, except for the peak value, the two equivalence ratios for a certain ion density or flame temperature are It will exist. This fact also applies to the oxygen concentration in the atmosphere.

Normally, in total primary combustion, the equivalence ratio is set to 1.0 when the indoor oxygen concentration is around 18%, so the relationship between the equivalence ratio and ion density or flame temperature described above is This also holds true for concentration, ion density, etc. That is, 1
There are two oxygen concentrations for a certain material density, with 8% as the boundary, and complicated control software is required to estimate the indoor oxygen concentration based on the ion density, etc. To summarize the above, in an all-primary surface combustion device, if an oxygen concentration sensor or a flame detection element is used alone, it is difficult to ensure combustion safety.

OBJECTS OF THE INVENTION The present invention solves such conventional problems and aims to further ensure combustion safety in a combustion apparatus that performs all primary surface combustion.

Structure of the Invention In order to achieve this object, the present invention provides a flame detection element above the flame hole in which the air-fuel mixture flow rate is highest or the amount of primary air is the least, and an oxygen concentration sensor is installed on the surface of the surface combustion vanina. It is installed above the flame hole of the combustion burner. Further, a comparison circuit section for comparing the output signals of the oxygen concentration sensor and the flame detection element, a solenoid valve to which the output signal of the comparison circuit is input, and a drive circuit for driving the solenoid valve are provided.

According to this configuration, the presence or absence of flame on the flame hole group can be quickly determined by the following process. The flame detection element installed above the flame hole sends an output signal depending on the presence or absence of flame to the comparison circuit section, and the comparison circuit section compares this input signal with a reference signal and then detects the presence or absence of flame. That is, it determines ignition or misfire, and sends a signal to the drive circuit that drives the solenoid valve to hold or close the solenoid. The output signal from the flame detection element in a conventional combustion apparatus that performs all primary surface combustion becomes so weak that it can hardly be detected on the comparison circuit when the combustion amount is reduced. In this configuration, the flame distribution of the surface combustion burner is used, and the flame detection element is installed above the flame hole where the air-fuel mixture flow rate is the fastest or the amount of primary air is the smallest, so flame detection is possible. The ion density and flame temperature near the element become the highest, and the output signal from the flame detection element shows a value that can be sufficiently processed by the comparator circuit even when the combustion amount is reduced.

Next, we will discuss detection of incomplete combustion due to lack of primary air due to lack of oxygen or clogging of the primary air port.

The oxygen concentration sensor installed above the flame hole sends an output signal corresponding to the oxygen concentration in the combustion exhaust gas to the comparison circuit section, and the comparison circuit section compares this input signal with a reference signal before starting the drive. Sends a signal to hold/close the solenoid valve to the circuit,
Combustion status can be monitored. By using a flame detection element and an oxygen concentration sensor in parallel, ignition, misfire, and incomplete combustion can be detected instantly, and since both can complement each other, it also leads to double safety. Description of an Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. In the figure, a surface combustion burner 1 is composed of a semi-cylindrical wire gauze flame hole group 2, a cylindrical mixing tube 3, a primary air port 4, and a nozzle 5 facing the air port 4. A flame rod 6 is arranged above the flame hole group 2 at the tip of the surface combustion burner 1, and an oxygen concentration sensor 7 is provided above the flame hole group 2 at the other end. Terminals of the frame rod 6 and the oxygen concentration sensor 7 are connected to a comparison circuit 8 and continue to a drive circuit 9 and a solenoid valve 10.

According to the above configuration, the fuel ejected from the nozzle 5 is mixed with the air flowing in from the primary air port 4 in the mixing pipe 3, and 1.
Form a mixture. After the mixture collides with the wall of the mixing tube 3 at the tip of the surface combustion burner 1, it diffuses into the mixing tube 3 and is ejected from the flame hole group 2. The air-fuel mixture ejected from the burner has a larger flow rate, that is, the amount of combustion, compared to the air-fuel mixture ejected from other flame hole groups.
The primary air ratio will be low. As a result, the flame formed at the tip of the surface combustion burner stabilizes much faster than the flame formed at other flame hole groups, and ignition detection by the flame rod 6 can be instantaneously performed.

As is clear from the above explanation, since the flame hole load of the flame hole group near the flame rod 6 is higher than that of other flame hole groups, the ion density is also high, and the combustion amount is reduced by 1/2 to 1/2. 1/3
Ignition detection can be carried out satisfactorily even if the

If for some reason the flame misfires or is ignited but the flame is unstable, that information is sent from the flame rod 6 and oxygen concentration sensor 7 to the comparison circuit 8, where it is compared with the setting value for stable combustion. If the set value is not satisfied, the drive circuit 9 will cause the solenoid valve 10 to close.

Under conditions of oxygen deficiency and primary air deficiency, the oxygen concentration sensor 7 promptly transmits its information to the comparator circuit 8, thereby ensuring safety against combustion.

Effects of the invention (1) By installing the flame detection element at the position of the present invention, ignition/misfire detection can be performed quickly, and at the same time,
Ignition and misfire detection can be performed depending on the combustion amount.

(2) Ignition Combustion can be monitored more reliably and safely by using a flame detection element to detect misfires, etc., and an oxygen concentration sensor to detect primary air shortages, etc.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a combustion safety device according to an embodiment of the present invention, and FIG. 2 is a front view of the same. 1... Surface combustion burner, 2... Flame hole group, 6...
...Flame detection element, 7...Oxygen concentration sensor, 8.
... Comparison circuit section, 9 ... Drive circuit, 10.
···solenoid valve.

Claims (1)

[Claims] A surface combustion burner whose flame hole group is composed of a wire mesh, a punched plate, or a ceramic plate having small holes;
Compare the output signals of the flame detection element and the oxygen concentration sensor with the flame detection element installed above the flame hole with the smallest amount of air, and the oxygen concentration sensor installed above the flame hole of the surface combustion burner. A combustion safety device comprising a comparator circuit unit that performs the operation, a solenoid valve to which an output signal of the comparator circuit unit is input, and a drive circuit that drives the solenoid valve.