JPS63290321A - Combustion device - Google Patents

Abstract

PURPOSE:To restrict amount of generation of oxygen nitride and keep a stable combustion state ranging from a high amount of combustion to a low amount of combustion by a method wherein a controller has a temperature sensing part for detecting a temperature of a burner cap through a thermocouple and an air ratio controller for controlling an amount of supplied air of a fuel supplying means or an air supplying means in such a way so that an output signal of the temperature sensing part becomes a constant value. CONSTITUTION:A thermocouple 13 is made such that a temperature measuring point 14 is closely contacted with a central position of a burner cap 15, connected to a controller 16 and an electromotive force generated at the temperature measuring contact point 14 is transmitted to a temperature detector part 17 of a controller 16. A temperature retrieving part 18 outputs a signal for varying an amount of combustion to an air ratio controller part 19 in such a way so that it becomes a constant value. An air ratio controller part 19 may control a pump 6 in response to an output signal of the temperature retrieving part 18 and adjust an amount of supplied fuel. The amount of supplied fuel is controlled in such a way so that the electromotive force shows a constant value and an air ratio is controlled to show any predetermined value (lambda=approximately 1.5). The air ratio is adjusted to keep a stable combustion condition, thereby a flame temperature when ignited is lowered and an amount of generation of NOx is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a burner equipped with an iAI device for controlling air ratio in combustion equipment using oil, gas, or the like.

Conventional technology When burning oil or gas as fuel, backfires and misfires can be prevented by supplying Ljt + fuel and air in an optimal ratio.
Alternatively, stable combustion can be maintained by preventing the occurrence of incomplete combustion. This ratio of air and fuel is called the air ratio, and conventional methods have been devised to detect the smoldering condition and control the amount of fuel or air supplied so as to always maintain the optimum air ratio.

For example, a well-known method for controlling the air ratio in an oil combustor is the one described in Japanese Unexamined Patent Publication No. 61-24917. This detects the ion current in the flame with a flame iron inserted into the flame, and uses the fact that this ion current changes depending on the air ratio to optimize the air ratio! This configuration adjusts the driving frequency of the water supply pump.

FIG. 3 shows an example of the ion current 1f. In a typical smoldering range (3,000 to 1,000 kcal/I), the ion current value If is approximately equal to the air ratio λ = O, El -0
The distribution has a peak at , 9. Therefore, the pump driving frequency is set to M0, and the fuel supply amount is determined so that the ion current value If becomes the maximum value, thereby controlling the air ratio and maintaining a stable combustion state.

Problems to be Solved by the Invention However, in the above configuration, the ion current value 1f
In order to control the fuel supply amount so that λ becomes the maximum value, the air ratio is adjusted to around λ=0.8 to 0.9. This range of air ratio λ-0.8 to 0.9 is the 9 range where the combustion rate is the fastest, so the flame temperature reaches its maximum value and the amount of nitrogen oxides (NOX) produced in the combustion exhaust gas increases significantly. It was extremely harmful to the human body.

The present invention solves such conventional problems by adjusting the air ratio on the high air ratio side, that is, near λ = 1.5, suppressing the amount of nitrogen oxides (NOX) produced, and achieving high flammability. The aim is to maintain stable combustion conditions from high to low combustion levels.

Means for Solving the Problems In order to solve the above-mentioned problems, the combustion apparatus of the present invention includes a burner in which a combustion wire mesh is provided in the outer circumferential direction of a straightening tube having a plurality of small holes, and an upper end of the burner. A burner cap to be closed, a fuel supply means and an air supply means for supplying fuel and air to the burner, a thermocouple having a temperature measuring contact in close proximity to the burner cap, and a controller for controlling combustion of the burner. The controller includes a temperature detection unit that detects the temperature of the burner cap using the thermocouple, and a temperature detection unit that adjusts the force so that the output signal of the temperature detection unit becomes a constant value. This configuration includes an air ratio control section that controls the supply amount of the air supply means or the air supply means.

Function The present invention has been described above. '74, the air ratio is adjusted so that the output signal of the temperature detection section is constant 4ffi.
By constantly maintaining a stable combustion state near = 1.5, the flame temperature during combustion is lowered and the amount of NOx produced is reduced, making it possible to provide a combustion device that is not harmful to the human body. be.

Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings. In the embodiment, an indoor open combustion hot air heater (oil fan heater) using an oil vaporization burner will be explained as an example.

FIG. 1 shows a system block diagram of the present invention.

Reference numeral 1 denotes a burner, which is constructed by providing a combustion wire mesh 4 through a rectifying space 3 in the outward direction of a rectifying tube 2 having a large number of small holes. Further, fuel is supplied from the fuel tank 6 to the fuel nozzle 7 by the fuel pump 6.
The air is supplied to the vaporization cylinder 8 through the air blower, and is vaporized and mixed in the vaporization cylinder 8 together with the combined combustion air supplied from the blower fan 9 through the air port 10, and passed through the mixing plate 11 to the burner 1 as a premixed gas. is supplied to form a combustion flame 12. Reference numeral 13 denotes a thermocouple, and a temperature measuring junction 14 is installed in close proximity to the center of the burner cap 15 that closes the upper end of the burner 1.The thermocouple 13 is also connected to the controller 16, where The electromotive force generated at the temperature measuring junction 14 of the thermocouple 13 is transmitted to the temperature detection unit 17 of the controller 16. 1B is a temperature search unit which sends an output signal to the air ratio control unit 19 so that the output signal of the temperature detection unit 17 becomes a constant value. A signal for changing the combustor is output.The air ratio control section 19 controls the pump 6 based on the output signal of the temperature search section 18 to adjust the fuel supply amount.

In the above configuration, the fuel and air ejected from the fuel nozzle 7 and the air port 10 become a premixed gas in the heated vaporization cylinder 8, pass through the mixing plate 11, flow out from the rectification cylinder 2, and flow out from the rectification space a.
A flame 12 is formed on the surface of the combustion wire mesh 4 through this process. At this time, since the temperature measuring contact 14 of the thermocouple 13 is in close contact with the burner cap 15, the temperature of the burner cap 15 is measured as the temperature output signal. Here, the burner cap 15 easily receives heat conduction and heat radiation from the flame 12 and its surroundings, and on the other hand, it is also affected by the temperature of the ejected premixed gas.

Here, Fig. 2 shows the ratio of combustion air to fuel, that is, the air ratio λ
The relationship between the electromotive force Ev of the thermocouple 13 and the electromotive force Ev of the thermocouple 13 is shown.゛Flame 1
The electromotive force E due to the direct heat from the burner cap 15, which is at a high temperature, is considered to reach a peak when the air ratio λ=1.0 because the flame temperature reaches its maximum value. On the other hand, the temperature of the premixed gas tends to decrease in inverse proportion to its total amount, and exhibits a large value on the low air ratio side. Therefore, the electromotive force Ev of the thermocouple 13 peaks at the air ratio λ = 1.0, decreases rapidly on the high air ratio side (λ) 1.0), and decreases not much on the low air ratio side (λ < 1.0). do not. Therefore,
By adjusting the air ratio λ so as to set the electromotive force to an appropriate value, for example, Ey=a, λ=1.
It becomes possible to control the air ratio to around 5. Therefore, when the electromotive force Ev is larger than the set value a, it is recognized that the air ratio is small, and the fuel supply amount of the pump 6 is reduced in order to adjust the air ratio to a higher side. Further, when the electromotive force Ev is smaller than the setting ia, the air ratio is large, and the amount of fuel supplied by the pump 6 is increased in order to adjust the air ratio to a lower side. In this way, the fuel supply amount is controlled so that the electromotive force Ev always remains at a constant value, and the air ratio can be controlled to an arbitrary set value (for example, around λ=1.5). Further, in this embodiment, the air ratio control is performed by adjusting the pump 6, but the air ratio control can be similarly performed by adjusting the air supply amount of the blower fan 9.

Furthermore, in this embodiment, since the temperature measuring contact 14 is provided in close proximity to the center position of the burner cap 15, the temperature measuring contact 14 itself does not shift in position, and can be easily installed in assembly. It is also possible to suppress variations in Ev to an extremely small level. Also burner cap 15
Since the temperature is easily influenced by the flame 12 and is extremely high, the value of the electromotive force Ev becomes large and easy to detect. Furthermore, since the temperature measuring contact 14 is located on the wall surface of the cap 15, it is less affected by disturbances in the flow of the premixed gas, so the electromotive force Ev
The variation in can also be suppressed to a small level.

Effects of the Invention As described above, the combustion apparatus of the present invention provides the following effects.

1) Since the air ratio is automatically set to the optimum point, there is no need for manual adjustment means and a stable combustion state can be maintained at all times.

2) Since the air ratio λ can be adjusted to around 1.5, combustion control of a full-primary combustion burner with low NOx can be performed.

3) Since the air ratio can be controlled using only thermocouples, it becomes a simple control system, improving reliability and reducing costs.

4) Since a pair of temperature measurement contacts are provided in close proximity to the burner cap, variations in the temperature measurement contact positions are reduced, and the premixed gas flow is less susceptible to disturbances, so the air ratio can be controlled with less variation. This allows precise control from high combustion to low combustion, expanding the variable range of combustion.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a combustion device in an embodiment of the present invention;
FIG. 2 is a characteristic diagram of the air ratio and thermocouple electromotive force, and FIG. 3 is a characteristic diagram of the conventional air ratio control method. 1... Burner, 2... Rectifier tube, 13.
...Thermocouple, 14... Temperature measuring junction, 15.
...Burner cap, 16...Controller. Name of agent: Patent attorney Toshio Nakao and one other person
Some fart feeding Rei

Claims (2)

[Claims] (1) A burner in which a combustion wire gauze is provided in the outer circumferential direction of a straightening cylinder having a plurality of small holes, a burner cap that closes the upper end of the burner, a fuel supply means for supplying fuel and air to the burner, and air a temperature detection section that detects the temperature of the burner cap using the thermocouple; and an air ratio control section that controls the supply amount of the fuel supply means or the air supply means so that the output signal of the temperature detection section becomes a constant value. (2) The combustion device according to claim 1, wherein the temperature measuring contact is closely located at the center of the burner cap.