JP2644415B2 - Forced air combustion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In response to recent demands for compactness,
When the size of the combustion apparatus is reduced, the combustion load per unit volume increases. Therefore, all premix burners that perform forced air blowing or forced exhaust are frequently used. However, this premixed burner has a narrower range of the excess air ratio m for stable combustion than the Bunsen burner. In order to solve the problem, a zero governor capable of keeping the ratio of gas and air constant at all times is provided in a gas supply path.

[0003]

However, even with a certain gas group specification, if the type of gas actually used is different, the Woppe index WI (Woppe index WI = heat value H ₀ / √specific gravity d) differs. , The smaller the Woppe index WI, the lower the input to the burner. For this reason, if the gas used is different from the gas whose zero governor is adjusted, the excess air ratio m may be out of a 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 forced blast-type combustion apparatus having a full premixed-type burner that can obtain a good combustion state even when any gas in a predetermined gas group is used.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an all premix burner for premixing and burning the entire amount of air required for combustion, and the air required for combustion to the all premix burner. A supply blower, a main fuel passage and a sub-fuel passage for supplying fuel to the all premix burners, a zero governor disposed in the main fuel passage to adjust 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 full premix burner, and control means for feedback-controlling the opening of the proportional valve so that the excess air ratio falls within a predetermined range. 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. If a gas having a Woppe index larger than that of the gas when the zero governor is adjusted is used, the excess air ratio shifts in a direction to decrease, so the control means reduces the proportional valve current so that the opening of the proportional valve decreases. To return the excess air ratio within a predetermined range. If a gas having a Woppe index smaller than that of the gas when the zero governor is adjusted is used, the excess air ratio will shift in a direction to increase. To return the excess air ratio within a predetermined range.

[0006]

According to the forced blast type combustion apparatus of the present invention, all the premixed type burners can maintain a good combustion state irrespective of the use of any gas in a predetermined gas group.

[0007]

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

The all-premix burner 1 includes a housing 1 that forms a premix chamber 111 in which gas and combustion air are mixed.
1. Composed of a combustion plate 12 formed with a large number of small flame openings and disposed so as to cover the upper surface of the housing 11, a rectifying plate 13, and the like. A combustion cylinder 14 having an internal combustion chamber 141 is connected to an upper end of the housing 11, and an exhaust collecting cylinder 15 is connected to an upper end of the combustion cylinder 14. still,
142 is a heat exchanger laterally installed in the combustion tube 14, 143,
Reference numerals 144 denote flame rods for detecting misfire and ignition electrodes for ignition, respectively, all of which are provided near the upper surface of the combustion plate 12. The heat exchanger 142 includes a water amount control valve 14.
Tap water is supplied through a water supply pipe 146 provided with the hot water supply 5, and hot water is supplied through a hot water supply pipe 147 connected to an outlet of the heat exchanger 142.

The air blowing means 2 includes a casing 21 having a blow-off portion 211 connected to an air-fuel mixture blow-out 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 to rotate at a low speed when the required combustion amount 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 blow-out portion 211 of the casing 21, and a solenoid valve 31 that closes when a misfire occurs is located upstream of the zero governor 5. It is arranged.

The amount of gas is determined based on the absolute value of the negative pressure generated at the outlet of the zero governor 5. Incidentally, the adjustment of the zero governor 5 is performed as shown in steps s1 to s4 of FIG. 2 by using test gas (for example, 13A-1, 13A-1,
2, 3, CH4, 12A-3), using the gas having the highest Woppe index WI (in this case, 13A-1) and setting the proportional valve 6 to the minimum opening.

The auxiliary 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 has a solenoid valve 41 that closes in the event of a misfire disposed upstream of the proportional valve 6. I have. If a guide plate (not shown) for guiding the gas flow of the auxiliary gas passage 4 toward the gas ejection nozzle 30 is provided at the junction of the outlets of the auxiliary gas passages 4, when the gas flows through the auxiliary gas passage 4, The resulting influence on the zero governor 5 can be reduced.

The oxygen sensor 7 mounted on the upper part of the exhaust collecting tube 15 is formed by coating a platinum electrode on zirconia, which is a solid electrolyte, and sends out an electric output corresponding to the oxygen concentration in the exhaust gas. The excess air ratio m is calculated based on the value of the electric output.

The combustion controller 8 is installed in a flat box-shaped water heater case 80, and includes the oxygen sensor 7, the 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 all-premix burner 1 based on the outputs from the tap water temperature setting device, the water amount sensor, and the incoming water temperature sensor (all not shown). Calculation is performed, and the current flowing to the centrifugal fan 22 is controlled so as to obtain the fan rotation speed corresponding to the required combustion amount. When the ignition is confirmed, the combustion controller 8 controls the excess air ratio m within a predetermined range (m = 1.2 to
The opening degree of the proportional valve 6 is adjusted by controlling the proportional valve current flowing through the proportional valve 6 so as to satisfy 1.4), and the Woppe index WI value of the gas to be used and the Woppe 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, advantages of this embodiment will be described. (A) Test gas in the gas group (in this embodiment,
13A-1, 2, 3, CH4, 12A-3), the gas having the highest Woppe index WI (13A-1) is used,
Further, the zero governor 5 is adjusted (excess air ratio m = 1.2) by setting the proportional valve 6 to the minimum opening. For this reason, when another gas in the gas group is used, the excess air ratio m shifts in a direction to increase. However, by increasing the opening degree of the proportional valve 6, the excess air ratio m falls within a predetermined range (m = 1.2 ~
1.4), and there is no occurrence of poor combustion such as incomplete combustion or flashback. Since the zero governor 5 is adjusted (excess air ratio m = 1.2) with the gas having the highest Woppe index WI by setting the proportional valve 6 to the minimum opening degree, the gas having the low Woppe index WI (12A-3) is used. Can be used to adjust the excess air ratio m within a predetermined range. (A) Since the forced-combustion water heater A uses the all-premix burner 1, it can be made much smaller than that using a Bunsen-type burner. (C) In the forced combustion type water heater A, the opening of the proportional valve 6 is increased at the time of ignition to make the inside of the all premix burner 1 gas-rich due to the presence of the auxiliary gas passage 4 in which the proportional valve 6 is disposed. This ensures ignition.

The present invention includes the following embodiments in addition to the above embodiment. a. The air-fuel ratio sensor includes a rectifying plate 13 in addition to the oxygen sensor 7.
May be a thermocouple disposed in the vicinity of the upper surface. In this case, the data related to the excess air ratio m and the output of the thermocouple is measured in advance and stored in a memory corresponding to the combustion load (from high load combustion to low load combustion), and used for actual use. At that time,
The excess air ratio m may be determined from the output of the thermocouple and the combustion load. b. In the above-described embodiment, the blowing means 2 is replaced with the all-premix burner 1
Although the forced-combustion water heater A disposed on the lower side is shown, the configuration of the present invention may be applied to a forced-exhaust combustion device in which a blower is provided on the combustion side of a full premix burner. c. Adjustment of the zero governor 5 (excess air ratio m = 1.4) may be performed 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. Further, a gas having a medium Woppe index WI in the predetermined gas group is used, and the zero governor 5 is adjusted (excess air ratio m = 1.3) by setting the opening of the proportional valve 6 to the medium opening. Is also good. d. In the above embodiment, the auxiliary gas passage 4 is bypassed to the main gas passage 3, but the auxiliary gas passage 4 is connected to the solenoid valve 3.
1 may be branched on the upstream side, and the tip may protrude into the casing 21. By doing so, the zero governor 5 is not affected by the gas flow rate in the auxiliary gas passage 4.

[Brief description of the drawings]

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

FIG. 2 is a flowchart illustrating a procedure for adjusting a zero governor in the forced-fired water heater.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pre-mixing type burner 2 Blowing 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-fired combustion device (forced-fired water heater)

Claims (1)

(57) [Claims] 1. An all-premix burner for premixing and burning the entire amount of air required for combustion, a blower for supplying air required for combustion to the premix burner, and a fuel supply to the all-mix burner A main fuel passage and a sub fuel passage, a zero governor disposed in the main fuel passage to adjust a fuel supply pressure to zero, a proportional valve disposed in the sub fuel passage, and the full premix burner. A forced-air combustion device comprising: an air-fuel ratio sensor for detecting an excess air ratio of the air-fuel ratio; and control means for feedback-controlling the opening of the proportional valve so that the excess air ratio falls within a predetermined range.