JPH0118324B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an improvement in a combustion device for a hot water boiler that enables reliable ignition operation even in a low-temperature environment.

(B) Background Art In conventional hot water boilers, regardless of whether they are used for heating or hot water supply, the combustion device is generally equipped with the combustion system shown in FIG. 1. Such a combustion system includes a fuel oil supply pipe 2 with a spray nozzle 1 attached to its tip, a control valve 3 and a hydraulic pump 4 interposed therein, and an air supply pipe 6 that supplies combustion air from the spray nozzle 1 to a combustion chamber 5. The spark plug 7 is arranged near the spray nozzle 1, and the fuel oil is pressurized to a high pressure of 7 to 13 kg/cm ² and sprayed from the spray nozzle 1. The mixed gas is mixed with combustion air, and the mixed gas is ignited by the high-voltage spark of the ignition plug 7, causing combustion.

The amount of fuel oil sprayed from the spray nozzle 1 is determined by the pressure of the hydraulic pump 4 and the size of the nozzle 1, and the amount of combustion air is adjusted to suit the amount of fuel oil supplied to ensure efficient combustion. Determined by the theoretical air volume. By the way, the ratio of the amount of fuel oil supplied to the amount of combustion air (air-fuel ratio) is normally determined based on steady combustion, and when igniting at low temperatures, the amount of fuel oil supplied is often insufficient. . For this reason, when a hot water boiler is placed outside in a cold region, the fuel becomes diluted with respect to the combustion air when the ambient temperature is low, resulting in ignition failure.

Conventionally, countermeasures for cold regions include increasing the fuel ratio or increasing the energy of the ignition spark. In the former case, ignition performance improves, but there are drawbacks such as combustion in an oxygen-deficient state during steady combustion, causing incomplete combustion, generating soot, and reducing combustion efficiency.In the latter case, sparks cause noise. This caused problems with noise on TVs, radios, etc. In addition, a method has been proposed in which the fuel ratio is increased for a certain period of time during ignition to improve ignitability, but even this method can be used when the ambient temperature is high or there is hot water left in the hot water boiler. When the hot water boiler is sufficiently warm, even though there is no need to change the air-fuel ratio, the fuel ratio increases at the time of ignition, resulting in the generation of soot and loud ignition noise.

(c) Purpose of the Invention The present invention has been made to solve the above-mentioned drawbacks of the prior art.
In addition, only when the temperature of the hot water boiler is low and the air-fuel ratio needs to be changed, the fuel ratio is increased to ensure ignition, and when the air-fuel ratio does not need to be changed, the air-fuel ratio is changed to steady combustion. The purpose is to achieve complete combustion at a value appropriate to the conditions.

(d) Main points of the invention The present invention has a burner that mixes fuel oil and combustion air, ignites and burns this mixed gas, and uses the combustion heat of this burner to heat water flowing through a heat exchanger. This is an improvement to the combustion equipment for hot water boilers.

In this invention, a temperature sensing device is provided at a position that can detect the temperature on the burner side and the temperature of hot water raised in the heat exchanger, and a mechanism for adjusting the fuel oil supply amount is provided in the fuel oil supply pipe of the burner. The operation of the time adjustment mechanism is such that when the temperature sensed by the temperature sensing device is higher than a predetermined temperature, the fuel oil supply amount is set to a constant amount, and when the sensed temperature is lower than the predetermined temperature, the fuel oil supply amount is increased from the steady amount, and the fuel oil supply amount is increased. The fuel oil supply amount is returned to a steady amount when the temperature sensed by the temperature sensing device exceeds a predetermined temperature. When the heating device senses a temperature lower than a predetermined temperature, the adjustment mechanism increases the amount of combustion supplied to the burner from the steady amount to adjust the air-fuel ratio and eliminate ignition failure. In addition, if the ambient temperature is high at the time of ignition, or if there is hot water left in the hot water boiler, or if combustion is stable, the temperature detected by the temperature sensing device will be higher than the predetermined temperature, so the amount of fuel supplied will be reduced. The air-fuel ratio will not be increased, and the air-fuel ratio will be at a value suitable for a steady combustion state, resulting in complete combustion.

(E) Embodiment of the Invention An embodiment of the invention will be described below with reference to FIGS. 2 to 5. FIG. 2 shows a hot water boiler for heating to which the present invention is applied, and 8 indicates a combustion chamber 5 inside.
9 is an outer can surrounding the inner cylinder 8 and forming a water chamber 10 between it and the inner cylinder 8; 11 is a burner disposed at the lower part of the combustion chamber 5; 12 is the upper part of the combustion chamber 5. 13 is an exhaust hood that shields the upper part of the heat exchanger 12, 14 is a chimney connected to the exhaust hood 13, 15 is a hot water return pipe connected to the lower part of the water chamber 10, 16 is a heat exchanger The hot water outgoing pipe TH led out from the exchanger 12 is a temperature sensing device attached to the joint between the heat exchanger 12 and the exhaust hood 13. In addition, water chamber 10
The upper part of the water chamber 10 is connected to the heat exchanger 12, and the water that enters the water chamber 10 from the hot water return pipe 15 is preheated while cooling the inner cylinder 8, and is further heated sufficiently when passing through the heat exchanger 12. The heated water is supplied to the hot water outgoing pipe 16 and sent to the usage section. Further, the combustion gas from the burner 11 passes through the heat exchanger 12, collects in the exhaust hood 13, and is discharged from the chimney 14.

The burner 11 consists of a combustion system shown in FIG. 3, which differs from the one shown in FIG. The mechanism 20 is attached to the fuel oil supply pipe 2.

FIG. 4 shows an electric circuit of the hydraulic pump 4 and the control valves 3, 17, in which the hydraulic pump 4 and the control valve 3 are connected between the power sources via the prepurge timer contact 21, and are connected in parallel with the control valve 3. Temperature sensing mechanism TH
The output switch 22 and control valve 17 are connected in series. As shown in FIG. 5, the output switch 22 has a temperature characteristic in which it opens when the temperature sensed by the temperature sensing device TH becomes lower than -5°C, and closes when it becomes 0°C or higher. The control valves 3 and 17 are normally closed type solenoid valves that are open when energized and closed when de-energized.

Next, the operation of the above-described embodiment will be explained. When the pre-purge in the combustion chamber 5 is completed and the conditions for combustion air and spark from the ignition plug 7 are established, the pre-purge timer contact 21 is closed. Therefore, the hydraulic pump 4 is energized and starts operating, and the control valve 3 is energized and opened. At this time, the temperature sensing device
When the sensed temperature of TH is lower than -5°C, the output switch 22 is open, so the control valve 17 is not energized and is closed. In this case, the fuel oil in the fuel oil supply pipe 2 is pressurized to the maximum pressure of the hydraulic pump 4 and is sprayed from the spray nozzle 1, so the fuel oil supply amount F _M becomes the maximum and the ignition operation is performed reliably. .

After about one minute has passed after ignition, when the combustion becomes stable, the temperature of the exhaust hood 13 will rapidly rise due to the combustion heat from the burner 11, so the temperature sensing device will be activated.
When the temperature sensed by TH becomes 0° C. or higher, the output switch 22 is closed. Therefore, the control valve 17 is energized and opened, and the discharge side and suction side of the hydraulic pump 4 are communicated through the bypass pipe 19.
The hydraulic pressure regulating valve 18 provided therein reduces the pressure to a predetermined pressure and pressurizes the fuel oil.
At this time, the fuel oil supply amount F _S (F _S < F _M ) sprayed from the spray nozzle 1 is maintained at the optimum air-fuel ratio in a steady combustion state with respect to the combustion air amount (constant) in the air supply pipe 6. By designing the fuel so that it sag, the combustion will proceed to complete combustion.

At the time of ignition, if the ambient temperature is high or if there is hot water remaining in the water chamber 10 and heat exchanger 12, the temperature detected by the temperature sensing device TH is 0°C or higher and the output switch 22 is closed from the beginning. . In such a case, the temperature of the combustion chamber 5 is high and there is no risk of ignition failure, so the fuel oil supply amount remains at F _S and combustion is started from the beginning at an air-fuel ratio suitable for a steady combustion state.

Therefore, in this embodiment, the combustion chamber 5 is closed at the time of ignition.
Only when the temperature is low and there is a risk of ignition failure, the amount of fuel oil supplied to the burner 11 (the amount of spray from the spray nozzle 1) is increased compared to the steady state to adjust the air-fuel ratio. The ignition operation is performed reliably. Also, if the temperature of the combustion chamber 5 is high due to the ambient temperature or residual hot water at the time of ignition, or if the temperature of the burner 11 is high after ignition,
When the combustion chamber 5 is warmed up by the combustion heat of At the same time, the noise at the time of ignition can be minimized. Moreover, the temperature sensing device
Since the TH is attached to the joint between the heat exchanger 12 and the exhaust hood 13, it can quickly sense not only the ambient temperature but also the combustion heat of the burner 11 via the exhaust hood 13, which has a small heat capacity. The large heat exchanger 12 allows it to react sensitively to residual hot water. Furthermore, the present invention was realized with an extremely simple configuration in which the temperature sensing device TH was attached to the hot water boiler and the oil pressure adjustment mechanism 20 was provided to the combustion system of the burner 11.

(F) Effects of the Invention As explained above, in the present invention, the temperature sensing device senses the temperature on the burner side and the temperature of the hot water that has been raised in the heat exchanger, and the temperature sensed by the temperature sensing device is low at the time of ignition. Sometimes, the amount of fuel oil supplied is made larger than normal to ensure ignition, and at the time of ignition, the ambient temperature,
If the temperature detected by the temperature sensing device is high due to the temperature of the combustion section or hot water remaining in the heat exchanger, or if the combustion section is warmed by the combustion heat of the burner after ignition, the temperature detected by the temperature sensing device becomes high. In this case, complete combustion is carried out at a steady air-fuel ratio, so the combustion control at the beginning of ignition can be controlled accurately depending on the temperature of the combustion section, which has a small heat capacity, and the temperature of the heat exchanger, which has a large heat capacity. Compared to systems that control combustion by sensing only the ambient temperature, it can reduce noise such as soot and ignition noise, increase combustion efficiency, and significantly reduce noise from TVs, radios, etc. Furthermore, only one temperature sensing element is required, and the structure can be constructed at low cost.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing an example of a combustion system used in a conventional combustion device, Figs. 2 to 5 are related to an embodiment of the device of the present invention, and Fig. 2 is a system diagram showing an example of a combustion system used in a conventional combustion device. Schematic structural diagram of hot water boiler, Part 3
4 is a system diagram of the combustion system used in the present invention, FIG. 4 is an electric circuit diagram of the combustion system, and FIG. 5 is an explanatory diagram of the temperature characteristics of the output switch shown in FIG. 4. 2...Fuel oil supply pipe, 11...Burner, 12...Heat exchanger, 20...Hydraulic pressure adjustment mechanism (adjustment mechanism), TH...
Temperature sensing device.

Claims (1)

[Claims] 1. A combustion device for a hot water boiler that has a burner that mixes fuel oil and combustion air, ignites and burns this mixed gas, and heats water to be heated flowing through a heat exchanger with the combustion heat of this burner, A temperature sensing device is installed at a position that can detect the temperature on the burner side and the temperature of the hot water raised in the heat exchanger, and a mechanism for adjusting the fuel oil supply amount is installed in the fuel oil supply pipe of the burner to adjust the ignition time. The mechanism operates by increasing the fuel oil supply amount to a constant amount when the temperature sensed by the temperature sensing device is higher than a predetermined temperature, and increasing the fuel oil supply amount from the steady amount when the sensing temperature is lower than the predetermined temperature. A combustion device for a hot water boiler, characterized in that the supply amount is returned to a steady amount when a temperature sensed by a temperature sensing device exceeds a predetermined temperature.