JPH05312315A - Forced air blowing type combustion device - Google Patents

Abstract

PURPOSE:To provide a forced air blowing type combustion device having a full premixing burner therein in which a superior combustion state can be attained even if any type of gas in a predetermined gas group is used. CONSTITUTION:The device is provided with a full premixing burner 1, an air blowing means 2 for supplying combustion air to the full premixing burner 1, a main gas passage 3 having a zero-governor 5 arranged therein, a sub-gas passage 4 having a proportional valve 6 arranged therein, an oxygen sensor 7 for sensing an excessive oxygen rate, and a combustion control device 8 for feed-back controlling the proportional valve 6 in such a manner that the air excessive rate becomes within a predetermined range. Adjustment of the zero-governor 5 is carried out in such a manner that gas having the highest Wobbe index in the predetermined gas groups is used and the minimum degree of opening of the proportional valve 6 is set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forced draft combustion device having a fully premixed burner.

[0002]

2. Description of the Related Art Based on the recent demand for compactness,
When the size of the combustion device is reduced, the combustion load per unit volume increases, so a full premix burner that performs forced ventilation or forced exhaust is often used. However, this all-premix burner has a narrower range of the excess air ratio m for stable combustion than the Bunsen burner. Therefore, there is a solution in which a zero governor that can always keep the ratio of gas and air constant is provided in the gas supply path.

[0003]

However, even in a certain gas group specification, if the type of gas actually used is different, the Woppe index WI (Woppe index WI = heat generation amount H ₀ / √specific gravity d) of the gas is different. , The smaller the Woppe index WI, the smaller the input to the burner. Therefore, if the gas used is different from the gas for which the zero governor is adjusted, the excess air ratio m may deviate from the predetermined range (for example, m = 1.2 to 1.4), and stable combustion may be hindered. An object of the present invention is to provide a compulsory blower combustor having a full premixing burner that can obtain a good combustion state regardless of which gas in a predetermined gas group is used.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a total premixing burner for premixing and burning all the required combustion air, and a required combustion air to the total premixing burner. A blower for supplying the fuel, a main fuel passage and a sub fuel passage for supplying fuel to the all-premix burner, a zero governor arranged in the main fuel passage for adjusting fuel supply pressure to zero, and the sub fuel passage. A proportional valve disposed therein, an air-fuel ratio sensor for detecting an excess air ratio of the total premixing burner, and a control means for feedback controlling the opening of the proportional valve so that the excess air ratio falls within a predetermined range. The configuration that includes and is adopted.

[0005]

[Function] No matter which fuel in a given gas group is used,
The zero governor is adjusted in advance so that the excess air ratio can be set within a predetermined range within the adjustable range of the proportional valve opening. When using a gas with a Wope index that is larger than the Wope index of the gas when the zero governor is adjusted, the excess air ratio shifts toward a smaller direction, so the control means reduces the proportional valve current so that the opening of the proportional valve decreases. To return the excess air ratio to within a predetermined range. If a gas with a Wope index smaller than that of the gas when the zero governor is adjusted is used, the excess air ratio shifts toward an increase, so the control means increases the proportional valve current so that the opening of the proportional valve increases. To return the excess air ratio to within a predetermined range.

[0006]

As described above, the forced air blowing type combustion apparatus of the present invention can maintain a good combustion state of the all premixing type burner regardless of which gas in the predetermined gas group is used.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. The forced combustion type water heater A is a fully premixed burner 1
A blower means 2 for supplying combustion air to the all-premix burner 1, a main gas passage 3 and an auxiliary gas passage 4 for supplying gas to the all-premix burner 1, and a main gas passage 3 A zero governor 5 and a proportional valve 6 arranged in the auxiliary gas passage 4,
An oxygen sensor 7 and a combustion controller 8 that controls the proportional valve 6 and the like are provided.

The all-premix burner 1 is a housing 1 which forms a premix chamber 111 in which gas and combustion air are mixed.
1, a combustion plate 12 having a large number of small flame openings and arranged so as to cover the upper surface of the housing 11, a straightening plate 13, and the like. A combustion cylinder 14 having a combustion chamber 141 inside is connected to the upper end of the housing 11, and an exhaust collecting cylinder 15 is connected to the upper end of the combustion cylinder 14. still,
142 is a heat exchanger laterally installed in the combustion cylinder 14, 143,
144 are flame rods for detecting misfires and ignition electrodes for ignition, and are provided near the upper surface of the combustion plate 12, respectively. The heat exchanger 142 includes a water quantity control valve 14
Tap water is supplied by the water supply pipe 146 in which the water is arranged, and hot water is supplied through the hot water supply pipe 147 connected to the outlet of the heat exchanger 142.

The blower means 2 has a casing 21 in which a blowout portion 211 is connected to a mixture gas ejection hole 110 formed in the bottom surface of the housing 11, and a scroll portion 21 of the casing 21.
2 and a centrifugal fan 22 installed in the inside. The centrifugal fan 22 is proportionally controlled so as to rotate at a low speed when the required combustion amount described later is small and to rotate at a high speed when the required combustion amount is large.

The main gas passage 3 is a gas pipe for supplying gas to the gas ejection nozzle 30 located in the blowout portion 211 of the casing 21, and an electromagnetic valve 31 which is closed at the time of misfire is provided upstream of the zero governor 5. It is arranged.

The gas amount is determined based on the absolute value of the negative pressure generated at the outlet side of the zero governor 5. The zero governor 5 is adjusted by the test gas (for example, 13A-1,
Gas having the highest Woppe index WI (2, 3, CH4, 12A-3) (13A-1 in this case) is used, and the proportional valve 6 is set to the minimum opening degree.

The sub gas passage 4 is a gas pipe that bypasses the upstream side of the solenoid valve 31 and the downstream side of the zero governor 5, and the solenoid valve 41 that is closed at the time of misfire is disposed upstream of the proportional valve 6. There is. If a guide plate (not shown) that guides the gas flow in the sub gas passage 4 toward the gas ejection nozzle 30 is provided at the confluence of the outlets of the sub gas passage 4, when the gas flows in the sub gas passage 4, The generated influence on the zero governor 5 can be reduced.

The oxygen sensor 7 attached to the upper part of the exhaust collecting cylinder 15 is a solid electrolyte zirconia with a platinum electrode attached to the film, and delivers an electric output corresponding to the oxygen concentration in the exhaust gas. The excess air ratio m is calculated based on the value of this electric output.

The combustion controller 8 is installed in a flat box-shaped water heater case 80, and has an oxygen sensor 7 and a frame rod 14.
3, the ignition electrode 144, the solenoid valves 31, 41, the proportional valve 6, the centrifugal fan 22 and the like are electrically connected. When the ignition is confirmed, the combustion controller 8 determines the required combustion amount of the total premix burner 1 based on the outputs from the hot water temperature setting device, the water amount sensor, and the incoming water temperature sensor (none of which are shown). The current is supplied to the centrifugal fan 22 by calculation so that the blower rotation speed corresponding to the required combustion amount can be obtained. Further, in the combustion controller 8, when ignition is confirmed, the excess air ratio m falls within a predetermined range (m = 1.2 to
The proportional valve current flowing through the proportional valve 6 is controlled so as to be 1.4), the opening of the proportional valve 6 is adjusted, and the Wope index WI value of the gas to be used and the Wope index W of the gas when the zero governor 5 is adjusted.
The deviation of the excess air ratio m due to the difference from the I value is corrected.

Next, the advantages of this embodiment will be described. (A) Test gas in the gas group (in this embodiment,
13A-1, 2, 3, CH4, 12A-3) using the gas with the highest Woppe index WI (13A-1),
Moreover, the proportional valve 6 is set to the minimum opening degree, and the zero governor 5 is adjusted (excess air ratio m = 1.2). Therefore, when another gas in the gas group is used, the excess air ratio m deviates in the direction of increasing, but by increasing the opening of the proportional valve 6, the excess air ratio m falls within a predetermined range (m = 1.2-
It can be set to 1.4), and it does not fall into combustion failure such as incomplete combustion or flashback. In addition, since the proportional valve 6 is set to the minimum opening degree and the zero governor 5 is adjusted (the excess air ratio m = 1.2) with the gas having the highest Woppe index WI, the gas having the low Wappe index WI (12A-3) is used. Even when using, the excess air ratio m can be adjusted within a predetermined range with a margin. (A) Since the forced combustion hot water heater A uses the all-premix burner 1, it can be made much smaller than the one using the Bunsen burner. (C) In the forced combustion water heater A, the opening of the proportional valve 6 is increased at the time of ignition to make the inside of the premixing burner 1 gas-rich due to the existence of the auxiliary gas passage 4 in which the proportional valve 6 is arranged. This ensures ignition.

The present invention includes the following embodiments in addition to the above embodiments. a. In addition to the oxygen sensor 7, the air-fuel ratio sensor includes a rectifying plate 13
It may be a thermocouple arranged near the upper surface of the. In this case, in response to the combustion load (from high-load combustion to low-load combustion), the related data of the excess air ratio m and the output of the thermocouple are measured in advance and stored in the memory for actual use. When
The excess air ratio m may be obtained from the output of the thermocouple and the combustion load. b. In the above embodiment, the blowing means 2 is used as the full premixing burner 1.
Although the forced-combustion water heater A arranged on the lower side of the above is shown, the configuration of the present invention may be adopted in a forced-exhaust type combustion device in which the blower is provided on the combustion side of the all-premix burner. c. The zero governor 5 may be adjusted (excess air ratio m = 1.4) by using the gas having the lowest Woppe index WI in the predetermined gas group and setting the proportional valve 6 to the maximum opening. Also, in the predetermined gas group, a gas having a medium Woppe index WI is used, and the opening of the proportional valve 6 is set to the intermediate opening to adjust the zero governor 5 (air excess ratio m = 1.3). Is also good. d. Although the sub gas passage 4 is bypassed to the main gas passage 3 in the above embodiment, the sub gas passage 4 is bypassed to the solenoid valve 3.
1 may be branched on the upstream side, and the tip may be projected into the casing 21. In this way, the zero governor 5 is not affected by the gas flow rate in the sub gas passage 4.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of a forced combustion type water heater according to an embodiment of the present invention.

FIG. 2 is a flow chart illustrating a procedure for adjusting the zero governor in the forced combustion type water heater.

[Explanation of symbols]

 1 All-premix burner 2 Blower means (blower) 3 Main gas passage (main fuel passage) 4 Sub gas passage (sub fuel passage) 5 Zero governor 6 Proportional valve 7 Oxygen sensor (air-fuel ratio sensor) 8 Combustion controller (control means) ) A Forced air blow type combustion device (forced combustion type water heater)

Claims (1)

[Claims] 1. A total premixing burner for premixing and burning all the required combustion air, a blower for supplying the required combustion air to the total premixing burner, and a fuel supply for the total premixing burner. A main fuel passage and a sub fuel passage, a zero governor arranged in the main fuel passage to adjust the fuel supply pressure to zero, a proportional valve arranged in the sub fuel passage, and a full premix burner The air-fuel ratio sensor for detecting the excess air ratio of 1. and a control unit for feedback-controlling the opening of the proportional valve so that the excess air ratio falls within a predetermined range.