JPH06117624A - Combustion control device - Google Patents

Abstract

PURPOSE:To prevent the combustion speed from being lowered at the time of starting combustion and stabilize the combustion by selecting a stage which minimizes the number of burners when an instructed objective fuel supply stands between a maximum fuel supply and a minimum fuel supply and changing over the number of burners. CONSTITUTION:In steady combustion mode, a first operating state which turns only one party of a burner U1 into a fuel supply state is changed over to a second operating state which turns both burners U1 and U2 into a fuel supply state at the same time. When an objective fuel supply stays between a maximum objective fuel supply G1 and a minimum objective fuel supply G2, the first state is selected. More specifically, a stage whose number of burners is minimum is selected so as to change over the number of the burners. This constitution makes it possible to inhibit a lowering of combustion speed and stabilize the combustion by selecting a stage with a less number of burners at the starting of combustion or when the temperatures of the burners themselves are lower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel for switching the number of combustion burners among a plurality of burners into a fuel supply state in a plurality of stages and adjusting the amount of fuel supply to the burner switched to the fuel supply state. Supply state adjusting means, ignition means for igniting the burner, ignition detecting means for detecting ignition of the burner, combustion control means for controlling the operation of the fuel supply state adjusting means and the ignition means, The combustion control means operates the fuel supply state adjusting means based on an ignition command so that a preset number of combustion burners for ignition and a preset fuel supply amount for ignition are set, and
The ignition mode for operating the ignition means is executed, and after the ignition is detected by the ignition detection means after the execution of the ignition mode, the target fuel supply amount is commanded.
Further, it is configured to execute a steady combustion mode in which the fuel supply state adjusting means is operated so as to increase the number of the combustion burners as the target fuel supply amount increases.
In the switching of the number of combustion burners in the steady combustion mode, the maximum target fuel supply amount for maintaining the stage is higher than the minimum target fuel supply amount for maintaining the stage in the next stage on the combustion burner number increasing side from the stage. The present invention relates to a combustion control device configured to be set to a large value to execute switching of the number of combustion burners.

[0002]

2. Description of the Related Art Switching the number of combustion burners in a plurality of stages in a steady combustion mode is an effective means for widening a variable range of a target fuel supply amount. When the number of combustion burners is switched to the increasing side, noise due to fire transfer occurs. On the other hand, if the number of combustion burners is switched to the decreasing side, there is a risk that the fuel will be released to the outside as unburned when extinguishing. Therefore, it is desirable that the number of switching of the number of combustion burners is small. Therefore, in the steady combustion mode, an overlapping part is provided at each stage of the number of combustion burners,
The number of combustion burners is not switched until the target fuel supply amount exceeds the maximum target fuel supply amount of the stage or falls below the minimum target fuel supply amount of the stage.

[0003]

At the start of combustion, that is,
At the beginning of the transition from the ignition mode to the steady combustion mode, the temperature of the burner itself is low. When the temperature of the burner itself is low,
When the fuel supply amount per burner is small, that is,
When the target fuel supply amount is close to the minimum target fuel supply amount that maintains the target stage, the fuel concentration becomes lean, so that the combustion speed decreases, and as a result, combustion may become unstable. An object of the present invention is to eliminate the above-mentioned conventional drawbacks, suppress a decrease in the combustion speed at the start of combustion, and stabilize the combustion.

[0004]

To achieve this object, the combustion control device according to the present invention is characterized in that the combustion control device has a preset time after ignition is detected by the ignition detection device. In the steady combustion mode up to, when the commanded target fuel supply amount is between the maximum target fuel supply amount and the minimum target fuel supply amount, a stage with a small number of combustion burners is selected. , The combustion burner number is switched.

[0005]

When the target fuel supply amount is between the maximum target fuel supply amount and the minimum target fuel supply amount, the fuel supply amount per burner is selected by selecting the stage having the smaller number of combustion burners. Can be made bigger. That is, it is possible to prevent the fuel concentration from becoming lean when the temperature of the burner itself is low.
By the way, the set time is set to a time required for the temperature of the burner itself to rise to such an extent that stable combustion can be performed even when the fuel concentration is low. After the temperature of the burner itself has risen, the combustion burner is operated until the target fuel supply amount exceeds the maximum target fuel supply amount of the stage or falls below the minimum target fuel supply amount of the stage, as in the conventional case. The number of combustion burners is not changed so that the number of times the combustion burners are changed is reduced.

[0006]

EFFECTS OF THE INVENTION At the beginning of combustion, that is, when the temperature of the burner itself is low, a stage with a small number of combustion burners is selected,
It suppresses the decrease of the burning speed. Combustion at the beginning of combustion can be stabilized.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the burner unit U of the rich / lean combustion type, the heat exchanger 1 for heating the water heated by the burner unit U, the fan 4 for supplying combustion air to the burner unit U, and the controller H The water heater is provided with. In the figure, 5 is a spark plug as an ignition means, 6 is a frame rod as an ignition detection means, and R is a remote controller for instructing control information to the controller H.

The burner unit U will be further described.
As shown in FIG. 5, a light mixing unit 3 that generates a light air-fuel mixture having a large suction ratio of primary air in a casing K having a bottomed rectangular tube shape.
The burner unit U is configured by alternately arranging the above and the rich mixing section 2 that generates a rich air-fuel mixture having a small primary air suction ratio. Here, the rich mixing sections 2 are arranged at both ends of the burner unit U, but between the rich mixing sections 2 at both ends and the side plates 11 of the casing K, the ventilation passages 7 for promoting combustion are provided. Are formed. Further, the bottom plate 15 of the casing K is notched with an opening 17 for supplying the fuel gas and the combustion air to the rich mixing portion 2 and the light mixing portion 3. The opening 17 is formed so that the portion corresponding to the light mixing portion 3 is wider than the portion corresponding to the deep mixing portion 2. Further, an engaging body 16a that engages with a lower opening 22 of the rich mixing portion 2 and an engaging body 16b that engages with a lower opening 32 of the light mixing portion 3 projecting upward from the front-rear end of the opening 17 are provided. Has been done.

When the individual rich mixing sections 2 are further described, as shown in FIG. 6, a space having a T-shaped cross section is formed by adhering the facing surfaces of the plate member 20 bent in a symmetrical shape. Has been done. A plurality of flame holes 24 for the rich mixture are formed in a row on the upper surface of the rich mixing portion 2.

The individual light mixing sections 3 will be further described. As shown in FIG. 7, a pair of plate members 30 bent in a symmetrical shape are opposed to each other and adhered to each other, whereby a cross section Y is formed.
A letter-shaped space is formed. A division plate 35 for dividing and forming the flame holes 34 is attached to the upper portion of the light mixing portion 3. That is, the flame holes 34 are divided into three rows in the longitudinal direction.

The structure for supplying the fuel gas to the burner unit U will be described. As shown in FIGS. 1 and 5,
The gas supply pipe G is branched into a first supply pipe G1 and a second supply pipe G2. The first supply pipe G1 and the second supply pipe G2 are respectively provided with open / close valves V1 and V2 for intermittently supplying fuel and gas amount adjusting valves V10 and V20 for adjusting the fuel supply amount. In addition, V0 is a safety valve. First supply pipe G1
Supplies gas to the right half of the burner unit U,
The second supply pipe G2 supplies gas to the left half of the burner unit U. That is, the burner unit U is divided into two burners U1 and U2, and the fuel of the two burners U1 and U2 is controlled by controlling the operation of the opening / closing valves V1 and V2 and the gas amount adjusting valves V10 and V20. The number of combustion burners to be supplied is switched between two stages, and the fuel supply amount to the burners U1 and U2 switched to the fuel supply state is adjusted. That is, the on-off valves V1, V
2 and the gas amount adjusting valves V10 and V20 correspond to the fuel supply state adjusting means V. The first supply pipe G1 and the second supply pipe G2
Is further branched into three. Central supply pipe G1
1, G21 are nozzles 29 for injecting gas for the rich mixing section 2.
Gas supply pipes G12, G13, G at both ends
Nozzles 39 for the light mixing unit 3 are attached to the G22 and G23.

The structure for controlling the combustion of the burner unit U will be described. As shown in FIG. 1, the controller H includes a water amount sensor S1 for detecting the amount of water supplied to the heat exchanger 1.
And an incoming water temperature sensor S2 for detecting the incoming water temperature to the heat exchanger 1.
And a hot water temperature sensor S3 for detecting the outlet temperature of the heat exchanger 1.
, The frame rod 6 and the remote controller R for instructing control information are connected to each other. And the controller H
Are open / close valves V1 and V2 and gas amount adjusting valves V10 and V2 based on preset and stored information and various input information.
0, the safety valve V0, the fan 4, and the operation of the spark plug 5 are controlled. That is, the combustion control means 1 using the controller H
00 is configured.

The control modes of the controller H include an ignition mode and a steady combustion mode. Hereinafter, each mode will be described with reference to FIG. The horizontal axis in FIG. 4 represents the fuel supply amount Gp, and the vertical axis represents the fan rotation speed Ns.

In the steady combustion mode, the number of combustion burners is switched to two stages. That is, the first state in which only one burner U1 is in the fuel supply state is switched to the second state in which both burners U1 and U2 are in the fuel supply state. In the first state,
The fuel supply amount Gp and the fan rotation speed Ns are controlled on the first line L1. In the second state, the fuel supply amount Gp and the fan rotation speed Ns are controlled on the second line L2.
When the fuel supply amount Gp is commanded, each line L is adjusted so that the air-fuel ratio becomes a steady target value corresponding to the fuel supply amount Gp.
The fan rotation speeds Ns at 1 and L2 are determined. First
Switching between the state and the second state will be described. Basically, in order to reduce the number of switching of combustion burner number,
The maximum target fuel supply amount G1 for maintaining the first state is set to be larger than the minimum target fuel supply amount G2 for maintaining the second state, and the number of combustion burners is switched. However, the commanded target fuel supply amount Gp is equal to the maximum target fuel supply amount G during the set time (for example, 30 seconds) after the ignition is detected by the flame rod 6.
When it is between 1 and the minimum target fuel supply amount G2, the first state is selected. That is, the stage with the smaller number of combustion burners is selected and the number of combustion burners is switched.

In the ignition mode, both burners U1, U2
Is set as the fuel supply state, and the spark plug 5 is operated. The fuel supply amount Gp is set to Gt and the fan rotation speed Ns is set to Nt so that the air-fuel ratio at this time becomes larger than the steady target value.

Next, the operation of the controller H will be described with reference to the flow charts shown in FIGS. First, it is determined whether or not hot water supply is necessary, and if hot water supply is not required, then it is determined whether or not hot water supply is currently being performed. If the hot water is not being supplied up to now, it returns as it is. If the hot water is being supplied up to the present time, the fire extinguishing process is executed and then the process returns. When it is determined that the hot water supply is necessary, it is determined whether or not the ignition is being performed. When the hot water supply is not required, the ignition mode is executed. Then, the steady combustion mode is entered. When the ignition is being performed, the combustion mode directly shifts to the steady combustion mode. In the steady combustion mode, first, it is determined whether or not a set time has elapsed since ignition was detected. When it has not elapsed, it is determined whether the target fuel supply amount Gp is larger than the maximum target fuel supply amount G1. If it is larger, the second state is selected, and if not, the first state is selected. After the set time has elapsed, first, the flag F is checked. The flag F indicates the state at that time, and indicates a first state when it is “0” and a second state when it is “1”. When the flag F is "0", it is determined whether the target fuel supply amount Gp is larger than the maximum target fuel supply amount G1. When it is larger, the state is shifted to the second state and the flag F is set to "1". On the other hand, when the target fuel supply amount Gp is smaller than the maximum target fuel supply amount G1, the first state is continued. When the flag F is "1", it is determined whether the target fuel supply amount Gp is larger than the minimum target fuel supply amount G2. If it is larger, the second state is continued. On the other hand, when the target fuel supply amount Gp is smaller than the minimum target fuel supply amount G2, the state is shifted to the first state and the flag F is set to "0". The above operation is repeated every elapse of a predetermined time.

[Other Embodiments] In the above embodiment, the number of combustion burners was switched to two stages, but it may be switched to three or more stages. In the above embodiment, the application example to the burner of the rich-lean burn type is shown, but in the practice of the present invention, the type of each of the plurality of burners is not limited to the rich-lean burn type, and various types including the Bunsen type are used. It can be the target burner. In the above-mentioned embodiment, the embodiment in which the present invention is applied to the water heater is shown, but it is also applicable to a fan heater or the like.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a block diagram of the overall configuration

FIG. 2 is a flowchart of control operation.

FIG. 3 is a flowchart of control operation.

FIG. 4 is an explanatory diagram showing a relationship between a fuel supply amount and a fan rotation speed.

FIG. 5 is a partially cutaway plan view of the burner unit.

FIG. 6 is a perspective view of a dense mixing section.

FIG. 7 is a perspective view of a light mixing unit.

[Explanation of symbols]

 5 Ignition means 6 Ignition detection means 100 Combustion control means U1, U2 Burner V Fuel supply state adjustment means Gp Target fuel supply amount G1 Maximum target fuel supply amount G2 Minimum target fuel supply amount

Claims (1)

[Claims] 1. A plurality of burner burners (U1, U2) are switched to a fuel supply state among a plurality of stages, and the amount of fuel supplied to the burner (U1, U2) switched to a fuel supply state. Fuel supply state adjusting means (V) for adjusting
And ignition means (5) for igniting the burners (U1, U2)
An ignition detecting means (6) for detecting ignition of the burners (U1, U2), the fuel supply state adjusting means (V) and the ignition means (5)
And a combustion control means (100) for controlling the operation of the combustion control means, the combustion control means (100) is configured to set a preset number of combustion burners for ignition and a preset fuel for ignition based on an ignition command. The fuel supply state adjusting means (V) is operated so as to achieve the supply amount, and
An ignition mode for operating the ignition means (5) is executed, and a commanded target fuel supply amount (Gp) is issued when ignition is detected by the ignition detection means (6) after execution of the ignition mode. And a steady combustion mode for operating the fuel supply state adjusting means (100) so as to increase the number of combustion burners as the target fuel supply amount (Gp) increases. When switching the number of combustion burners in the steady combustion mode, the maximum target fuel supply amount (G1) that maintains that stage
Is set to be larger than the minimum target fuel supply amount (G2) for maintaining the stage in the next stage on the combustion burner number increasing side from that stage, and the combustion burner number is switched. In the control device, the combustion control means (100) sets the commanded target in the steady combustion mode from when ignition is detected by the ignition detection means (6) until a set time elapses. When the fuel supply amount (Gp) is between the maximum target fuel supply amount (G1) and the minimum target fuel supply amount (G2), the stage having the smaller number of combustion burners is selected to switch the number of combustion burners. A combustion control device configured to perform.