JPH06221672A - Gas combustion apparatus - Google Patents

Abstract

PURPOSE:To prevent corrosion of a connecting tube of a subheat exchanger due to dewing by supplying city water from a second water tube of a second heat exchanger, and outputting hot water from a first water tube of a first heat exchanger through the tube of the subheat exchanger. CONSTITUTION:A main heat exchanger 1 in which a water tube is passed through many fins 1a is disposed separately from a gas burner 3. A subheat exchanger 2 in which a connecting tube 20 is passed through a plurality of fins 2a is disposed in or in the vicinity of a flame forming area of the burner 3. Simultaneously, the tube of the exchanger 1 is connected directly to the tube 20 of the exchanger 2 to reduce generation of harmful gas in combustion exhaust gas. In this apparatus, the exchanger 1 is divided into a first heat exchanger having a first water tube 11 and a second heat exchanger having a second water tube 12, both the first.second tubes are inserted through common fins 1a, the tube 20 is connected to the tube 12, and the tube 11 is connected to the tube 20.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a gas combustion device, in particular
The present invention relates to a gas combustor equipped with a two-stage heat exchanger for reducing the generation of harmful gases such as nitrogen oxides or carbon monoxide in combustion exhaust gas.

[0002]

2. Description of the Related Art Recently, a technique for reducing the amount of nitrogen oxides contained in the combustion exhaust gas of a gas appliance has been developed, and a gas appliance with sufficient consideration for environmental protection has appeared. Nitrogen oxides are generated by the oxidation of nitrogen contained in the air supplied to the combustion section of gas appliances under high temperature conditions (thermal NOx), but the amount of such nitrogen oxides is suppressed. As a gas combustion device to obtain,
As shown in Fig. 6, two-stage heat exchanger and gas burner (3)
A combination of (3) and is proposed.

This heat exchanger is composed of a main heat exchange section (1) and a sub heat exchange section (2) arranged below the main heat exchange section, and the main heat exchange section (1) has a large number of parts. Fins (1a) (1a) and a water pipe (10) that penetrates the fins (1a) (1a)
(2) is composed of fins (2a) and (2a) arranged at a coarser interval than the fins (1a) and (1a), and a connecting pipe (20) penetrating the fins (2a) and (2a).
The sub heat exchange section (2) is located in the flame forming region of the gas burners (3) and (3), and the water passage pipe (10) and the connection pipe (20) are connected to each other. Tap water is supplied from 20).

In this device, the water in the connecting pipe (20) and the water pipe (10) of the heat exchanger absorbs the amount of heat generated by the gas burners (3) and (3) from the fins to form hot water. Although it is taken out to the outside, the endothermic action for that purpose is mainly performed in the main heat exchange section (1), and in the sub heat exchange section (2) mainly in the gas burner.
(3) The flame of (3) is cooled, and this cooling action suppresses the generation of nitrogen oxides. Meanwhile, the sub heat exchange section
When (2) is located near the flame of the gas burners (3) and (3) to suppress the combustion exhaust gas temperature within a predetermined temperature range, the production of carbon monoxide can be reduced.

However, in these devices, the sub heat exchange section is used.
There is a problem that dew condensation occurs on the connecting pipe (20) of (2) and corrosion occurs. This is because the peripheral wall of the connecting pipe (20) is cooled by water flow in the connecting pipe (20) of the auxiliary heat exchange part (2), and the combustion exhaust gas contacting the peripheral wall of the connecting pipe (20) is cooled to a temperature below the dew point. This is because the temperature is reached and the moisture in the combustion exhaust is condensed on the peripheral wall of the communication pipe (20).

According to the present invention, such "a large number of fins (1
The main heat exchange part (1) with the water pipe penetrating through a) (1a) is placed away from the gas burners (3) (3), and the connecting pipe (20) penetrates through the multiple fins (2a) (2a). The auxiliary heat exchange part (2) is connected to the gas burner.
(3) It is located inside or near the flame formation zone of (3), and the water passage pipe of the main heat exchange part (1) and the connecting pipe (20) of the auxiliary heat exchange part (2) are connected in series. In order to reduce the generation of harmful gas in the combustion exhaust gas ",
The problem is to prevent corrosion of the connecting pipe (20) of the sub heat exchange part (2) due to the generation of dew condensation. [Invention of Claim 1]

[0007]

[Technical Means] The technical means of the present invention taken to solve the above-mentioned problem is that "the main heat exchange part (1) is connected to the first water pipe (11).
Is divided into a first heat exchange section having a second water exchange pipe (12) and a second heat exchange section having a second water exchange pipe (12), and the first and second water exchange pipes are provided on common fins (1a) (1a). Insert the second water pipe (12)
Connect the connecting pipe (20) to this connecting pipe (20) and connect the first water pipe (1
I tried to connect 1). "

[0008]

The above technical means of the present invention operates as follows. In the gas combustion apparatus of the present invention, tap water is supplied from the second water pipe (12) of the second heat exchange unit to connect the sub heat exchange unit (2).
The hot water is taken out from the first water pipe (11) of the first heat exchange section via the (20).

When tap water is supplied from the second water pipe (12) of the second heat exchange section together with the combustion of the gas burners (3) (3), the water flowing in the second water pipe (12) is changed to the gas burner (3). It is heated by absorbing the generated heat amount of (3) from a large number of fins (1a) (1a).
Next, the heated and heated hot water will flow into the communication pipe (20) of the sub heat exchange section (2), so that the degree of cooling of the peripheral wall of the communication pipe (20) will decrease and the communication pipe (20 20) The combustion exhaust gas that comes into contact with the peripheral wall does not reach the temperature below the dew point and does not dew. Further, since the auxiliary heat exchange section (2) is located inside or near the flame forming region of the gas burner (3) (3), the flame or combustion generated in the gas burner (3) (3) The exhaust gas comes into contact with the connecting pipe (20) and fins (2a) (2a) of the sub heat exchange section (2), and is absorbed by the hot water in the connecting pipe (20) to cool the flame or combustion exhaust gas. As a result, the production of nitrogen oxides or carbon monoxide can be suppressed.

The connecting pipe (20) of the sub heat exchange section (2)
The hot water that has been further heated in the inside is the first water pipe of the first heat exchange section.
It flows to (11) and absorbs the amount of heat generated by the gas burners (3) and (3) from the fins (1a) and (1a) in the first water pipe (11) to be further heated and finally heated to a predetermined temperature. Is taken out of the device as. At this time, tap water is supplied into the second water pipe (12), but the peripheral wall of the second water pipe (12) has the first water pipe (1
It is connected to the common fins (1a) (1a) through which 1) is inserted. On the other hand, since the hot water in the first water pipe (11) is heated to the hot water outlet temperature, the temperature of the fins of the second water pipe insertion portion is equal to that of the first heat pipe from the combustion exhaust gas.
Due to the conduction heat from the water flow pipe (11), the temperature is maintained at a relatively high temperature, and the combustion exhaust gas contacting the peripheral wall of the second water flow pipe (12) does not reach a temperature below the dew point.

[0011]

[Effect] The present invention having the above-mentioned structure has the following unique effects. In the connecting pipe (20) of the sub heat exchange section (2), hot water heated and heated will flow, and the combustion exhaust gas contacting the peripheral wall of the connecting pipe (20) will not have a temperature below the dew point.
Corrosion of the connecting pipe (20) due to condensation can be prevented. or,
The hot water in the first water pipe (11) has been raised to the hot water temperature,
The temperature of the fins of the second water pipe insertion portion is maintained at a relatively high temperature due to the amount of heat absorbed from the combustion exhaust gas and the conduction heat from the first water pipe (11), and tap water is supplied. Since the combustion exhaust gas that comes into contact with the peripheral wall of the second water passage pipe (12) does not fall below the dew point, dew condensation does not occur. [Invention of Claim 2] The invention of Claim 2 solves the same problem as that of the invention of Claim 1 described above, and the technical means adopted for this purpose is to provide an auxiliary heat exchange section (2 The connecting pipe (20) of () was made of stainless steel.

According to this technical means, the peripheral wall of the connecting pipe (20) is cooled by the water flow in the connecting pipe (20) of the sub heat exchange part (2) and comes into contact with the peripheral wall of the connecting pipe (20). Even if the combustion exhaust gas is cooled to a temperature below the dew point and dew condensation occurs, since the connecting pipe (20) is made of stainless steel, it is corrosion resistant to water and can prevent corrosion. .

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention described above will be explained with reference to the drawings. The embodiment shown in FIG. 1 is one in which the present invention is applied to a water heater having a two-stage heat exchanger. This is a burner box that houses the Bunsen type gas burner (3) (3)
A can body (4) equipped with a two-stage heat exchanger consisting of a main heat exchange section (1) and a sub heat exchange section (2) is connected to the upper part of (5). The main heat exchange part (1) is composed of a large number of fins (1a) (1a) arranged at intervals of about 2.6 mm and a water pipe (10) penetrating the fins (1a) (1a), and The heat exchange part (2) is composed of fins (2a) (2a) arranged at intervals of about 12 mm and a connecting pipe (20) penetrating the fins (2a) (2a). or,
As shown in FIG. 2, the connecting pipe (20) of the sub heat exchange section (2) is arranged in a meandering shape in four rows in the upper region of the gas burners (3) and (3). Fins (2a) (2a) of heat exchange part (2)
Are arranged so as to sandwich the flame openings of the gas burners (3) (3). Further, the water passage pipe (10) is composed of a first water passage pipe (11) and a second water passage pipe (12) in two upper and lower stages.
As shown in FIG. 3, (11) is arranged in a meandering manner by the upper three rows and the lower one row, and the second water pipes (12) are arranged in the lower three rows in a meandering manner. It is set up. The first water pipe (11), the second water pipe (12), and the connecting pipe (20) have a water passage of the second water pipe (12) in the second row from the lower left end in the same figure. → 3rd row → 4th row → 1st row from right end of connecting pipe (20) → 2nd row → 3rd row → 4th row → 1st water pipe (11) 1st row from left end → 1st row Connections are made from the left end to the first column → the second column → the third column. (In FIG. 3, a to k
Water in order. ) In this case, the second water passage pipe (12) is the second row → third row → fourth row (a from the left end of the lower stage).
To c) correspond to the second heat exchange section described in the technical means section of claim 1, and further, the first water pipe (11) is the first row from the lower left end to the first row from the upper left end. Eye → 2nd row → 3rd row (h
~ K) corresponds to the first heat exchange section.

In this case, as the gas burners (3) and (3) burn, the second row (a) of the second water passage pipe (12) from the left end of the lower stage.
When tap water is supplied from the gas burner (3) (3) in the route from the left end of the lower row to the second to fourth rows (a to c)
The amount of heat generated is absorbed from the fins (1a) (1a) to heat up. Next, the heated and heated hot water flows into the connecting pipe (20) and flows from the right column to the left column (d to g). At this time, the degree of cooling of the peripheral wall of the connecting pipe (20) is small. The combustion exhaust gas that comes into contact with the peripheral wall of the connecting pipe (20) does not reach a temperature below the dew point, and drain (condensation) does not occur in the connecting pipe (20). Therefore, the corrosion of this can be prevented. Further, the auxiliary heat exchange part (2) including the connecting pipe (20) is a gas burner (3).
Since it is located within the flame formation zone of (3), the gas burner (3)
The flame generated in (3) contacts the connecting pipe (20) and fins (2a) (2a), and the heat of the flame is absorbed by the hot water in the connecting pipe (20) to cool the flame. The hot water in the connecting pipe (20) is further heated. Further, the cooling action of the flame can suppress the generation of nitrogen oxides. Also, the fins (2a) (2a)
Are arranged at relatively large intervals (about 12 mm) so as to sandwich the flame openings of the gas burners (3) (3), so that the secondary gas supplied from below to the flames of the gas burners (3) (3) Since the air is smoothly supplied and the heat of the flame is not absorbed too much, generation of carbon monoxide due to incomplete combustion is suppressed.
Next, the hot water in the communication pipe (20) passes through the lowermost left column (h) which is the first water pipe (11), and then the upper left column to the right column (i.
k), and in this portion, the amount of heat generated by the gas burners (3) and (3) is absorbed from the fins (1a) and (1a) and finally taken out as hot water of a predetermined temperature. At this time, tap water having a relatively low temperature is introduced into the second water pipe (12).
The peripheral walls of (12) (a to c) are connected to common fins (1a) (1a) through which the first water pipes (11) (h to k) are inserted. On the other hand, since the hot water in the first water pipe (11) (h to k) is raised to the hot water discharge temperature, the temperature of the fins of the second water pipe insertion portion is added to the amount of heat absorbed from the combustion exhaust gas. As a result, the conduction heat from the first water pipe (11) maintains a relatively high temperature, and the combustion exhaust gas contacting the peripheral wall of the second water pipe (12) (a to c) does not fall below the dew point. , Drain does not occur in this part. The fins (1a) (1a) are arranged at relatively small intervals of about 2.6 mm, which improves the heat absorption efficiency.

In the embodiment described above, three rows out of the lower four rows of the water pipes (10) are the second water pipes (12).
Water pipe (12) may be composed of the lower row of water pipe (10),
Further, the same effect as that of the present invention can be obtained even if all the lower four rows of the water pipes (10) are used as the second water pipes (12). The second water pipe
(12) In the above embodiment, which is set in the lower stage of the water passage pipe (10), heat is absorbed from the upstream side, that is, the high temperature side of the combustion exhaust, compared with the case where the second water passage pipe (12) is provided in the upper stage. The water pipe temperature rises to a large extent, making it even more difficult for drainage to occur.

The above heat exchanger is usually made of copper, but if the connecting pipe (20) of the sub heat exchange section (2) is made of stainless steel, the stainless steel has corrosion resistance to water. Therefore, the combustion exhaust gas on the peripheral wall of the communication pipe (20) is cooled to a temperature below the dew point, and even if drainage occurs, the corrosion of the communication pipe (20) can be reliably prevented. or,
In this case, even in a conventional type water heater that supplies tap water from the connecting pipe (20) of the sub heat exchange part (2) and takes hot water from the water pipe (10) of the main heat exchange part (1), Corrosion of the connecting pipe (20) can be prevented.

Further, the connecting pipe (20) of the sub heat exchange section (2)
As shown in FIG. 4, the straight part (21) and the bend part (2
It is composed of 2) and has a meandering shape, but it is difficult to form the bend part (22) with stainless steel, so the bend part (22)
Even if it is formed of only copper, this portion is usually disposed so as to project outside the can body (4) of the heat exchanger and does not come into contact with combustion exhaust, so there is no problem.

The water pipe (10) of the main heat exchange section (1) is shown in FIG.
Alternatively, as shown in FIG. in this case,
Tap water is supplied using the lowermost water pipe (10) as the second water pipe (12) of the present invention. Further, it may be configured by one stage. In the above embodiment, the second water pipe (12) is set at the lowest stage of the water pipe (10), but the upper part where the temperature of the peripheral wall of the pipe does not fall below the dew point may be used as the second water pipe (12). good.

Further, in the above embodiment, the gas combustion apparatus for reducing the generation of nitrogen oxides by arranging the sub heat exchange section (2) in the flame forming region of the gas burners (3) and (3) has been described. A method to reduce the production of carbon monoxide by locating the heat exchange part (2) near the flame of the gas burners (3) and (3) and keeping the combustion exhaust temperature within a predetermined temperature range (1000 ° C to 1500 ° C). The present invention may be applied to this gas combustion device. In any case, the gas burners (3) and (3) are not limited to the Bunsen type burner and may be all primary air type burners.

When the heat absorption efficiency differs depending on the fin material, thickness, etc., the fins (1a) (1a) of the main heat exchange section (1)
The fins (2a) and (2a) of the sub heat exchange section (2) may have the same arrangement interval.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment.

FIG. 2 is a perspective view of the sub heat exchange section (2).

FIG. 3 is a sectional view taken along line XX.

FIG. 4 is an explanatory view of the connecting pipe (20) of the sub heat exchange part (2).

FIG. 5 is an explanatory diagram of another embodiment.

FIG. 6 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 (1) ・ ・ ・ Main heat exchange part (10) ・ ・ ・ Water pipe (11) ・ ・ ・ First water pipe (12) ・ ・ ・ Second water pipe (2) ・ ・ ・ Sub heat exchange part (20) ) ・ ・ ・ Communication pipe (3) ・ ・ ・ Gas burner (1a) (2a) ・ ・ ・ Fin

Claims (2)

[Claims] 1. A plurality of fins (2a) (2a) are provided by disposing a main heat exchange section (1) having a large number of fins (1a) (1a) penetrating water pipes away from the gas burners (3) (3). ) Is located inside or near the flame forming zone of the gas burners (3) and (3), and the auxiliary heat exchange section (2) penetrating the connecting pipe (20) is located in the main heat exchange section (1). In a gas combustion device in which the water flow pipe and the connecting pipe (20) of the auxiliary heat exchange unit (2) are connected in series to reduce the generation of harmful gas in the combustion exhaust, the main heat exchange unit (1) is , A first heat exchange part having a first water pipe (11) and a second heat exchange part having a second water pipe (12), and the first and second water pipes are common to each other. The fins (1a) (1a) are inserted, the connecting pipe (20) is connected to the second water pipe (12), and the connecting pipe (20) is connected to the first pipe.
A gas combustion device that connects the water pipe (11). 2. A plurality of fins (2a) (2a) are provided by disposing a main heat exchange section (1) having a large number of fins (1a) (1a) penetrating water pipes away from the gas burners (3) (3). ) Is located inside or near the flame forming zone of the gas burners (3) and (3), and the auxiliary heat exchange section (2) penetrating the connecting pipe (20) is located in the main heat exchange section (1). In a gas combustion device in which the water pipe and the connecting pipe (20) of the auxiliary heat exchange section (2) are connected in series to reduce the generation of harmful gas in the combustion exhaust gas, the auxiliary heat exchange section (2) Connecting pipe (2
Gas combustor made of stainless steel (0).