JPS5880421A - Combustion stabilizing device in full primary air type combustion apparatus - Google Patents

Abstract

PURPOSE:To prevent a trouble of oxygen starvation from occurring by setting an excess air ratio of a pilot burner at a value lower than that of a main burner, and controlling combustion by a comparator comparing flame current values of both burners. CONSTITUTION:The pilot burner 2 is made into a full primary air type burner, and its excess air ratio is set to a value lower than that of the main burner 1, and the flame current value of the pilot burner 2 begins to reduce its early stages by the lowering of the oxygen content within air. This flame current value is compared with the flame current value of the main burner 1 which increases by the lowering of the oxygen concentration in the air. By these operations, even when the variation characteristic of the flame current value of the main burner 1 varies slightly, the variation characteristic of the flame current value of the pilot burner 2 varies similarly. The relative relationship between both flame current values become substantially equal, and hence it is possible to stop the combustion at substantially equal oxygen concentrations in which no oxygen starvation trouble occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion safety device for preventing oxygen deficiency in an all-primary air combustion device.

Conventional Bunsen burners have a flame rond II near the burner's flame opening! l! KeSgII! It is known that combustion is stopped by detecting the lift of the combustion flame due to complete combustion based on the presence or absence of flame current (for example, Utility Model Application No. 55-175774).

In all primary air type burners, it is difficult to detect oxygen deficient combustion by the presence or absence of flame current because the combustion flame does not reach an extreme level when oxygen is deficient. When the flame current value is detected by facing the flame rod, the absolute value of the flame current value changes depending on the burner input, but the change characteristics with the excess air ratio (supplied air amount / required combustion air amount) It is known that, as shown in the M2 diagram, the flame current shows a mountain-shaped characteristic that peaks in the range of 1.0 to 1.1, and oxygen-deficient combustion can be detected by utilizing this change characteristic of the flame current value. Attempts have been made. To explain this in detail, the excess air ratio of a primary air burner is generally set to about 1.5, and the actual excess ratio decreases as the oxygen concentration in the air decreases. Since the flame current value increases as the flame current increases, oxygen deficiency accidents can be prevented by stopping combustion when the flame current increases to a predetermined value.

The ai in Figure 93 is 13 stipulated by the Japan Gas Appliance Inspection Association.
Using the first test gas of A gas (the gas used to measure the generation of soot and the 00 concentration), this shows the change characteristics of the flame current value with respect to the oxygen concentration in the air when the excess air ratio is set to 1.5. However, in this case, even if the gases belong to the same type, there may be slight differences in their composition, such as the second test gas (gas for testing flashback) or the $5 test gas (gas for testing flashback and proof-off). gas), the change characteristic is from & line to &
'41, and when the first test gas is used, the flame current setting value is determined so that combustion is stopped when the oxygen concentration in the air drops to, for example, 18%. A problem arises in that combustion cannot be stopped until the oxygen concentration in the fuel is reduced to approximately 17%.

An object of the present invention is to provide a device that solves the problem of am, and in an all-primary air type combustion device in which a pilot burner is installed in parallel with an all-primary air type main burner, the pilot burner is An all-primary air type burner (configured with an excess air ratio set lower than that of the main burner, with separate flame rods facing each combustion surface of the main burner and the pilot burner, respectively) A comparator is provided to detect the flame current value of the main burner and the flame current value of the pilot burner and compare the #i7 flame current value, and the combustion is controlled by the comparator. .

Next, one example of implementing the present invention will be explained with reference to attached drawings.

+1 in the drawing (2) indicates the main burner and the pilot burner, each burner (11 (21 is the gas distribution chamber (21))
1 m) (2 ri) and the combustion surface (1b) (2 ri) surrounded by wire mesh.
11), and each gas distribution chamber (Ia) (2m) is equipped with gas from each gas nozzle +31 (41) and a supply air of 7 amps (
5) and primary air from the combustion surfaces (1) and (5) respectively.
2b), but in this case, the control board (6) controls each gas distribution chamber (1m) (2m
) to control the supply amount of primary air to the main burner (1).
The excess air ratio of the pilot burner (2) should be set to the usual 1.5 or so, and the excess air ratio of the pilot burner (2) should be lower than that, for example 1.1.
Set to a certain degree.

In the drawing (71 (81 is the combustion surface (1) of the main burner (1)
b) shows the first flame rondo facing the combustion surface (2b) of the pilot burner (2), and the flame current value detected at each flame rod (7) +81. Current-voltage conversion circuit +9
101 and an amplifying circuit aυα2 to a comparator (13), and the output of the comparator Q3 controls the opening and closing of the original solenoid valve α interposed in the gas supply pipe a4.

In FIG. 1, Qe indicates a temperature control control valve that cuts off the gas supply to the main burner (1).

Next, to explain its operation, the first frame rond (7
) The flame current value of the main burner (1) detected by, for example, when using the first test gas of 15 μm, changes as shown by the & line in Fig. 5 according to changes in the oxygen concentration in the air.
In addition, in the second and fifth test gases of the 15th frame, the & line is shifted slightly parallel to the lower current side, as shown in the a' line in the figure, and this point is as explained earlier, but the 27th frame rod ( The 7 frame current value of the pilot burner (2) detected in step 8) has an excess air ratio set to a low value in advance. The peak value of the main burner (1) is 5 because the input of the pilot burner (2) is small.
．． 5 μm, but it becomes small to about 1.5 μA), and a decrease in the flame current occurs as the oxygen concentration decreases. In the case of the second and fifth test gases, the change characteristic is as shown in the figure '' line, which is slightly shifted in parallel to resemble a low current compared to bs.

Fig. 4 shows the input potential to the comparator a3 corresponding to the frame current, and in the figure M*A'&l is on the 1°1' line in Fig. 5.
Lines B and B' correspond to silver in Figure 5, but in this case, the amplification rate of the amplification circuit a2 on the $27 frame rod (8) side is set high, and the pilot burner ( 2) Corresponding to the flame current The electric potential on the high rot burner (2) side is higher than the electric potential on the main burner (1) side, and as the oxygen concentration in the air decreases, the pilot burner (2)
When the potential on the side becomes lower than the potential on the main burner 11), a low level output is generated from the comparator αJ,
As a result, the original solenoid valve α is closed and combustion is stopped.

Oxygen enrichment depletion where combustion is stopped, case A for the first test gas
, the concentration is at the intersection of both lines B, and in the case of the 1st, 2nd, and 5th test gas, the concentration is at the intersection of both lines A/, 17, but A
Each line I and B' has a lower potential @ (transferred in parallel to each line A and B, so the concentration at the intersection of both human and B lines and AI,
The concentration at the intersection of the 17 lines is the same, and therefore combustion is stopped at approximately the same oxygen concentration for both gases.

In this way, according to the present invention, all pilot burners are
As a second pneumatic burner, its excess air ratio is set lower than that of the main burner, so that the flame current value of the pilot burner starts to decrease early due to the decrease in oxygen concentration in the air. The combustion is controlled by comparing the flame current value of the main burner, which increases with As a result, the relative relationship between the two flame current values becomes approximately equal, which has the effect of making it possible to stop combustion at approximately the same oxygen concentration.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of an example of the device of the present invention, Fig. 2 is Fig. 11 showing the relationship between the excess air ratio and the 7 rheme current value, and Fig. 5 is the 7 rheme current value for oxygen in the air. The mtv and g4 diagrams show the change characteristics of the lem current value.
It is an ii diagram. +11・・・・・・・・・ Main burner (2;・
・・・・・・・・・・・・Pilot burner (1b) (2
b)... Combustion surface (7) (8)... Flame rod 0...
・・・・・・・・・・Comparison Exceeded 2 people outside the vessel ↑ Jin 3rd figure 181 summer cell during the empty firing) 4th figure 9 Kikume Sameto 1v Tadasu Cmu)

Claims (1)

[Claims] In an all-primary air type combustion device in which a pilot burner is installed in parallel with an all-primary air type main burner, the pilot burner is configured as an all-primary air type burner, and its excess air ratio is lower than that of the main burner. Set 1. Place different flame ronds facing each combustion surface of the main burner and the pilot burner, and detect the flame current value of the main burner and the flame current value of the pilot burner.
1. A combustion safety device for an all-primary air type combustion apparatus, characterized in that a comparator is provided to compare flame current values, and combustion is controlled by the comparator.