JPH05256408A - Hot water supplier - Google Patents

Abstract

PURPOSE:To enable decrease of exhaustion of NOx without any disadvantage such as increase of exhaustion of CO by A method wherein a water supply passage is passed through an upper half of a space surrounded by a wall member and apart from the wall member. CONSTITUTION:In an upper half of a space surrounded by a wall member 11, where combustion reaction is proceeding, flame temperature rises up relatively high. On the other hand, in a lower half of the space, where the combustion reaction is not proceeding, the flame temperature is relatively low. Accordingly, by passing a water supply passage 20 through the upper half of the space, the flame in the low temperature part is not robbed of heat, while the flame temperature in the high temperature part is lowered, whereby exhaustion of NOx can be reduced. Also, as the flame is formed along the wall member 11, if the water supply passage 20 is placed apart from the wall member 11, formation of the flame is not be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided with a heat exchanger for heating water and a burner for heating the heat exchanger, and the burner includes a pair of opposed wall members for forming combustion surfaces. A plurality of flame openings for ejecting an air-fuel mixture of fuel gas and primary air for combustion are provided upward along the facing surface of the wall body, and the wall body faces the facing surface side from the back side of the facing surface of the wall body. The present invention relates to a hot water supply device in which an air supply hole for supplying secondary air for combustion is formed in a slit shape along the jet direction of the air-fuel mixture.

[0002]

2. Description of the Related Art The hot water supply apparatus as described above is used for an instantaneous water heater or the like, and a large turndown ratio can be obtained by increasing or decreasing the combustion area according to the combustion load. By the way, in the burner, the combustion reaction is relatively slowly progressed by gradually supplying the secondary air for combustion. Therefore, the temperature of the flame does not become extremely high, and the amount of NOx emitted is smaller than that of the Bunsen burner.

[0003]

The smaller the NOx emission, the better. In the above-mentioned conventional technique, although NOx emission is certainly smaller than that of the Bunsen burner, it is desirable to further reduce it. An object of the present invention is to obtain a hot water supply device that emits less NOx than the above-mentioned prior art.

[0004]

In order to achieve this object, the first characteristic configuration of the hot water supply apparatus according to the present invention is the upper half of the space in which the water supply passage to the heat exchanger is surrounded by the wall body. It is configured so as to pass through a position that is a part and is separated from the wall body.

In the second characteristic configuration, the water supply passage is branched into a cooling passage that passes through the space and a bypass passage that does not pass through the space, and passes through the cooling passage as the burner combustion amount increases. That is, a control means for controlling the amount of water to a large extent is provided.

[0006]

The operation of the first characteristic configuration is as follows. It is considered that the combustion reaction is progressing in the upper half of the space surrounded by the wall and the flame temperature becomes relatively high.
On the other hand, in the lower half, the combustion reaction does not proceed, and the flame temperature is considered to be relatively low. That is, by passing the water supply passage through the upper half of the space, the flame temperature of the high temperature portion is lowered without taking heat from the flame of the low temperature portion. Also, the flame is formed along the wall. Therefore, the water supply passage is separated from the wall body so as not to hinder the formation of flame.

The operation of the second characteristic configuration is as follows. If the burner burns less than the amount of water passing through the cooling passage, the flame temperature may drop too much.
Therefore, by controlling the amount of water passing through the cooling passage according to the amount of combustion of the burner, the amount of heat taken from the flame of the burner is controlled according to the amount of combustion of the burner. Therefore, the flame temperature near the cooling passage can be maintained within an appropriate range.

[0008]

The effects of the first characteristic structure are as follows. Generally, when flame temperature is lowered, NOx
Emissions are reduced. However, if the heat of the low-temperature flame portion where the combustion reaction is not progressing is taken away, the combustion reaction is remarkably hindered, resulting in an increase in CO emission. That is, without lowering the flame temperature of the low temperature part,
Since the flame temperature of the high temperature portion is lowered, it is possible to obtain a hot water supply device in which NOx emission is further reduced without causing a problem such as an increase in CO emission.

In the second characteristic configuration, the flame temperature can be maintained within an appropriate range even when the burner combustion amount or the water supply amount to the heat exchanger changes, so that a hot water supply device having excellent practicability can be obtained. I can.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 3, a hot water supply device including a heat exchanger 6 for heating water and a burner unit U heating the heat exchanger 6 is connected to a hot water tap 4 via a hot water supply passage W4. Has been done. The water supply path W1 to the heat exchanger 6 is branched into a cooling path W2 that passes through the burner unit U and a bypass path W3 that does not pass through the burner unit U. A mixing valve 3 that adjusts a distribution rate k of the amount of water between the cooling passage W2 and the bypass passage W3 is provided at the confluence of the cooling passage W2 and the bypass passage W3.

The structure of the burner unit U will be described. As shown in FIGS. 1 and 2, a box-shaped case 7 is internally provided with an air passage 9 for pressurized air supplied from a fan 8 and a pair of burners 1. Each burner 1 is provided with a pair of combustion surface forming wall bodies 11 facing each other in the front-rear direction. Plural flame openings 12 for ejecting an air-fuel mixture of fuel gas and primary air for combustion are juxtaposed on the left and right sides of each of the two wall bodies 11 along the facing surface (surface). Wall 1
Below 1 is a mixture chamber 1 for supplying a mixture to the flame outlet 12.
3 is provided. Further, the combustion surface forming wall 11
Slit-shaped air supply holes 14 that supply secondary air for combustion from the back side of the facing surface of the wall body 11 to the facing surface side are formed in an alternating arrangement with the flame openings 12.

The structure of the cooling passage W2 will be described. Figure 2
As shown in, headers 5a and 5b for relaying the cooling passage W2 are provided on both sides of the burner unit U, respectively. That is, the flow path branched into the four water pipes 20 in the first header 5a is configured to merge into one flow path in the second header 5b. The water pipes 20 pass through the side plate 16 of each burner 1 in pairs and pass through the space surrounded by the wall 11. As shown in FIG. 1, the passage position of the water pipe 20 is a position (3 mm) apart from the wall 11 in the upper half part of the space (20 mm below the upper end of the burner 1).

As shown in FIG. 3, in the fuel gas supply passage G1 for the burner 1, two on-off valves 22 and 23 for connecting and disconnecting the fuel gas supply, and an electromagnetic gas amount adjusting valve 24 for adjusting the fuel gas supply are provided. Is installed. In the water supply passage W1,
Water quantity sensor S1 for detecting water supply quantity Q0 to heat exchanger 6
And an incoming water temperature sensor S2 for detecting the incoming water temperature Ti. A cooling water temperature sensor S for detecting the water temperature Tr of the cooling passage W2 is provided downstream of the second header 5b of the cooling passage W2.
3 is interposed. A hot water temperature sensor S4 for detecting a hot water outlet temperature Tm of the heat exchanger 6 is provided in the hot water supply passage W4. In the figure, 26 is an igniter, and 27 is a frame rod for detecting whether or not the burner 1 is ignited. And
These are connected to the control device H, respectively.

Further, a remote controller R for instructing control information to the control device H is provided, and the remote controller R includes an operation switch 30 for instructing start / stop of hot water supply operation, an operation lamp 31, and a burner 1. A combustion lamp 32 that is turned on during combustion and a target temperature setting device 33 that sets a target hot water temperature Ts on the outlet side of the heat exchanger 6 are provided.

The controller H actuates the gas amount adjusting valve 24 and the mixing valve 3 based on preset information stored in advance and various input information to burn the combustion amount Ip of the burner 1, the cooling passage W2 and the bypass passage W3. Is configured to control the water distribution ratio k. That is, the control device 100 is configured to utilize the control device H to control the amount Q2 of water passing through the cooling passage W2.

First, the control of the combustion amount Ip of the burner 1 (combustion control) will be described. Burner 1 combustion amount Ip
Is the number 1 so that the outlet heated water temperature Tm becomes the target heated water outlet temperature Ts.
Is calculated based on.

[0017]

## EQU1 ## Ip = K1 × (Ts-Ti) × Q0 + K2 × Δ1 + K3 × ∫Δ1dt

Here, K1, K2 and K3 are constants, and Δ1 is a deviation between the target hot water outlet temperature Ts and the hot water outlet temperature Tm.

Next, the control of the distribution rate k of the water amount between the cooling passage W2 and the bypass passage W3 (water amount control) will be described. First, the amount Q2 of water passing through the cooling passage W2 and the heat exchanger 6
The ratio k1 to the water supply amount Q0 to the water is calculated based on the equation 2.

[0020]

(2) k1 = Q2 / Q0 = K4 × Ip / Q0 + K5 × Δ2 + K6 × ∫Δ2dt

Here, K4, K5, and K6 are constants, and Δ2 is a value determined by the equation 3.

[0022]

Δ2 = Tr−90 (when Tr is 90 degrees or more) = 0 (when Tr is between 40 degrees and 90 degrees) = 40−Tr (when Tr is 40 degrees or less)

The distribution rate k of the amount of water in the cooling passage W2 and the bypass passage W3 is calculated based on the equation (4).

## EQU00004 ## k = Q2 / (Q0-Q2) = k1 / (1-k1)

That is, the distribution rate k is basically determined so that the larger the combustion amount Ip, the larger the amount Q2 of water passing through the cooling passage W2. However, the amount Q2 of water passing through the cooling passage W2 is corrected so that the water temperature Tr is maintained within a predetermined range (here, 40 degrees to 90 degrees). Each constant is experimentally determined so that the amount of heat taken by the cooling passage W2 is about 1/6 of the combustion amount Ip.

Next, the operation of the control device H will be described with reference to the flow chart shown in FIG. First, the necessity of hot water supply is determined based on the information of the operation switch 30, and when hot water supply is not required, it is determined whether or not hot water supply is currently being performed. If the hot water is not being supplied until now, it returns as it is. If the hot water is being supplied up to the present, the process returns after executing the fire extinguishing process. When it is determined that hot water supply is necessary, it is determined whether or not the hot water tap 4 is open based on the information from the water amount sensor S1. If the hot water tap 4 is closed,
It is determined whether or not the hot water is being supplied up to the present time. If the hot water is not being supplied up to the present, the process returns as it is. If the hot water is being supplied up to now, the fire extinguishing process is executed and then the process returns.
When it is determined that the hot water tap 4 is open in the above determination,
It is determined whether or not the ignition is being performed, and the ignition process for igniting the burner 1 is executed only when the ignition is not being performed. Next, as described above, the combustion amount Ip of the burner 1 is obtained based on the equation 1, and the distribution rate k is obtained based on the equations 2 to 4. Then, the gas amount adjusting valve 24 and the mixing valve 3 are controlled so that the combustion amount Ip and the distribution rate k are obtained. The above operation is repeated every elapse of a predetermined time.

[Other Embodiment] In the above embodiment, the mixing valve 3 was used to change the amount of water Q2 passing through the cooling passage W2. However, as shown in FIG. 5, a flow rate control valve 40 is provided in the cooling passage W2. The amount of water Q2 may be changed.
The operation of the control device H in this case will be briefly described based on the flowchart shown in FIG. The steps up to the ignition processing are the same as those in FIG. The combustion amount Ip of the burner 1 is calculated based on the equation 1, and the gas amount adjusting valve 24 is controlled so that the combustion amount Ip becomes the combustion amount Ip. Then, the water temperature Tr of the cooling passage W2 is compared with the sum of the incoming water temperature Ti and the predetermined temperature ΔT. When the water temperature Tr is higher, the opening degree of the flow rate adjusting valve 40 is increased, and when the water temperature Tr is lower, the opening degree of the flow rate adjusting valve 40 is decreased.

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 side view of a main portion of a burner unit.

FIG. 2 is an exploded perspective view of a burner

FIG. 3 is a block diagram of a control configuration.

FIG. 4 is a flowchart of control operation.

FIG. 5 is a block diagram of a control configuration according to another embodiment.

FIG. 6 is a flowchart of control operation of another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 burner 6 heat exchanger 11 wall body 12 flame mouth 14 air supply hole 100 control means W1 water supply passage W2 cooling passage W3 bypass passage

Claims (2)

[Claims] 1. A heat exchanger (6) for heating water and a burner (1) for heating the heat exchanger (6) are provided, and the burner (1) forms a pair of opposed combustion surfaces. And a plurality of flame openings (12) for ejecting a mixture of fuel gas and primary air for combustion upward along the facing surface of the wall (11). An air supply hole (14) for supplying secondary air for combustion from the back side of the facing surface of the wall body (11) to the facing surface side of the wall body (11) is formed in a slit shape along the jet direction of the air-fuel mixture. In the hot water supply device, the water supply passage (W1) to the heat exchanger (6) is the upper half of the space surrounded by the wall body (11) and the wall body (1).
A hot water supply device configured to pass through a position separated from 1). 2. The water supply passage (W1) is branched into a cooling passage (W2) that passes through the space and a bypass passage (W3) that does not pass through the space, so that the combustion amount of the burner (1) is large. The water heater according to claim 1, further comprising control means (100) for controlling the amount of water passing through the cooling passage (W2) to a large extent.