JP2841159B2 - Heat exchange equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchange device, and more particularly to a heat exchange device having an improved durability, and can be used as a heat exchange device for a hot water supply heater.

[0002]

2. Description of the Related Art A heat exchange device having a structure as shown in FIG. 5 is provided as a heat exchange device for improving the heat exchange efficiency by condensing water vapor in combustion exhaust gas generated by a gas burner so as to absorb latent heat from the combustion exhaust gas. There is something. In this device, a gas burner (3) and a heat exchanger (1) are arranged in this order downstream of the fan (4) in the supply / exhaust flow, and downstream of the heat exchanger (1). Is connected to an exhaust passage (21).

A large number of heat absorbing fins (12) and (12) are provided on the outer periphery of a water pipe (11) constituting the heat exchanger (1).
By bending the water pipe (11) in a meandering manner, the main heat exchange portion (1a) (a portion mainly absorbing the sensible heat of the combustion exhaust) and the sub heat exchange portion (1b) located thereunder (mainly the combustion portion). A portion that absorbs latent heat from exhaust gas). And
The inflow water into the heat exchanger (1) flows from the sub heat exchange section (1b) to the main heat exchange section (1a).

In this apparatus, when a gas burner (3) is forcibly burned using a fan (4) and water is supplied to a heat exchanger (1), the sensible heat of the combustion exhaust gas generated by the gas burner (3) is mainly used. The heat exchange section (1a) is heated. Then, the combustion exhaust gas whose temperature has been lowered after heating the main heat exchange section (1a) is cooled to a dew point or lower when passing through the sub heat exchange section (1b) through which low-temperature water flows, whereby Drain is generated at the time. Then, the latent heat generated at the time of drain generation is absorbed by the sub heat exchange section (1b) to raise the temperature of the water passing therethrough. As described above, in the above-described apparatus, the heat exchange efficiency is improved by actively using the latent heat. The drain generated in the sub heat exchange section (1b) is discharged outside through a drain discharge hole (8) located below the sub heat exchange section (1b).

[0005] However, in the above-mentioned conventional apparatus, there is a problem that the heat exchanger (1) is easily deteriorated, and sufficient durability cannot be secured. The above problem will be described in more detail. Since the drain containing dissolved nitrogen oxides in the combustion exhaust gas adheres to the water pipe (11) and the heat absorbing fins (12) and (12) in the sub heat exchange section (1b), these water pipes (11) and The heat absorbing fins (12) are susceptible to corrosion due to the action of the nitrogen oxide. When the corrosion progresses, the heat absorbing fins (12) and (12) partially become defective or combustion products such as nitrogen oxides adhere to the fin surface, whereby the heat absorbing fins (12) (1
The thermal conductivity of the surface of 2) becomes poor, and this does not function properly. The water pipe in the sub heat exchange section (1b)
When (11) is corroded, small holes are formed in the wall surface, and water leaks from this portion. As described above, in this type of heat exchange device that actively generates drain, particularly, the water pipe (11) and the heat absorbing fins (12) and (12) in the sub heat exchange section (1b) are easily corroded, and the heat exchange is performed. The container (1) is deteriorated, and the sufficient durability cannot be achieved.

As shown in FIG. 6, a main heat exchange section (1a) and a sub heat exchange section (1b) are arranged in this order above a gas burner (3). The same problem as described above also occurs in the type in which the generated drain is discharged to the outside from a drain receiver (19) disposed below the drain. The present invention has been made in view of the above points, and `` A part of a water pipe (11) having a large number of heat absorbing fins (12) (12) on the outer periphery is used as a main heat exchange part (1a). The water pipe section upstream of the main heat exchange section (1a) is defined as a sub heat exchange section (1b), and the main heat exchange section (1a) and the sub heat exchange section are provided downstream of the gas burner (3) in the exhaust gas flow. A heat exchange device in which the sections (1b) are sequentially arranged in this order so that the main heat exchange section (1a) absorbs the sensible heat of the combustion exhaust and the sub heat exchange section (1b) absorbs the latent heat from the combustion exhaust. It is an object of the present invention to mitigate the deterioration with time of the heat exchanger (1) so that its durability can be improved.

[0007]

The technical means of the present invention for solving the above-mentioned problems is described in "The water pipe (11) and the heat absorbing fin in the sub heat exchange section (1b)".
(12) A shower device (B) for spraying washing water is provided on the surface of (12), and the drain device attached to the water pipe (11) and the heat absorbing fins (12) (12) is required by the shower device (B). It was made to wash according to. "

[0008]

The above technical means operates as follows. When the gas burner (3) is burned and water is supplied to the heat exchanger (1), drains that cause corrosion of the water pipe (11) and the heat absorbing fins (12) and (12) in the sub heat exchange section (1b) are generated. Adheres to the surface of However, according to the above technical means, since a shower device (B) for spraying washing water is provided on the surface of the water pipe (11) or the like in the sub heat exchange section (1b), the shower device ( By operating B) as necessary, drain adhering to the surface of the water pipe (11) or the like can be washed away, and the drain does not remain on the surface of the sub heat exchange section (1b).

[0009]

The present invention has the following specific effects. By washing the drain in which the nitrogen oxides and the like are dissolved with washing water, it is possible to prevent the drain from remaining on the surface of the water pipe (11) in the sub heat exchange section (1b). Corrosion of the component wall of 1b) can be suppressed, and the durability of the heat exchanger (1) is improved.

[0010]

Next, an embodiment of the present invention will be described. The embodiment shown in FIG. 1 and FIG. 2 is an embodiment in which the present invention is applied to a hot water heater for hot water heating.
(A) and radiator (H) are circulation channels with circulation pump (33)
(34). And the heat exchange device of this embodiment
In (A), in the order of the fan (4) → gas burner (3) → heat exchanger (1) → exhaust passage (21) in the order of The gas burner (3) is supplied with gas from a gas valve (28) inserted into a gas circuit to the gas burner (3).

The heat exchanger (1) is the same as the above-mentioned conventional one,
It is mainly composed of a main heat exchange section (1a) that absorbs the sensible heat of the combustion exhaust and a sub heat exchange section (1b) located downstream of it (a heat exchange section that mainly absorbs latent heat from the combustion exhaust). The main heat exchange section (1a) and the sub heat exchange section (1b) are configured by meandering a single water pipe (11) having a large number of heat absorbing fins (12).

A shower device (B) located between the main heat exchange section (1a) and the sub heat exchange section (1b) is provided near the inner wall of the can body (6) accommodating the heat exchanger (1). ) Is provided, and FIG.
As shown in the figure, the shower device (B) is provided with a perforated pipe (B ₁ ) provided in parallel with the water pipe (11) in the sub heat exchange section (1b), and a washing valve (B ₃ ) for supplying water thereto. ). The operation of the components such as the gas burner (3) is controlled by the control circuit shown in FIG.

The output of the operation switch (26) is a gas burner
The output of the stop switch (24) is applied to the set input terminal of the flip-flop (29) as a fire extinguishing signal generating circuit for outputting the fire extinguishing signal of (3), and the reset input terminal of the flip-flop (29). Has been applied. The output of the flip-flop (29) is the gas valve (28) inserted in the gas circuit to the gas burner (3), the circulation pump (33) inserted in the circulation flow path (34), and the gas burner (3) Igniter (32) for performing an ignition operation on the air, and a fan for forced supply and exhaust
(4), so that these gas valves (28)
Etc. are controlled to be ON / OFF. Furthermore,
The reverse output of the flip-flop (29) is applied to a mono-multi vibrator (44) via a differentiating circuit (20), and a cleaning valve (B ₃ ) is output by the output of the mono-multi vibrator (44).
Is configured to be opened for a predetermined time.

In this device, when the operation switch (26) is turned on, the flip-flop (29) is energized and the "H" signal is output from the flip-flop (29), and the circulating pump (33) is operated by the signal. Thus, the water in the circulation flow path (34) is forcibly circulated. Also the flip-flop (29)
The fan (4) and the igniter (32) start to operate according to the signal from the controller, and the gas valve (28) is opened.
(3) becomes burning. Then, the sensible heat of the combustion exhaust gas from the gas burner (3) is used to make the main heat exchange section (1) in the heat exchanger (1).
While (a) is heated, drain is generated in the water passage pipe (11) and the heat absorbing fins (12) and (12) constituting the sub heat exchange section (1b), so that latent heat is absorbed in the water passage in this portion. As a result, the circulating water in the circulation flow path (34) is heated and heated in the heat exchanger (1), and the heated high-temperature water is supplied to the radiator (H). Thereafter, the high-temperature water returns to the sub heat exchange section (1b) in the heat exchanger (1) after its temperature is lowered (usually about 40 ° C.) by the heat radiation action in the radiator (H). When the temperature-reduced water flows through the sub heat exchange section (1b), it cools the combustion exhaust to a temperature lower than the dew point (about 60 ° C.) to absorb latent heat from the combustion exhaust, and the main heat exchange section (1a) When flowing through the furnace, it absorbs the sensible heat of the combustion exhaust gas and becomes hot water, which is supplied to the radiator (H).

Next, when the stop switch (24) is operated, the flip-flop (29) is deenergized, and the gas valve (28) and the like are turned off.
The state returns to the FF state, and the heating operation stops. Then, the inverted output of the flip-flop (29) rises and the rising signal is detected by the differentiating circuit (20), whereby the monomultivibrator (44) outputs the "H" signal for a predetermined time (for example, 5 seconds). Thus, the cleaning valve (B ₃ ) is maintained in the open state for the time. Then, tap water is spouted from the perforated pipe (B ₁ ), and the spouted water flows through the water pipe (11) of the sub heat exchange section (1b).
Drains sprayed onto the surfaces of the heat absorbing fins (12) and (12) are washed away. Thereby, corrosion of the water pipe (11) and the like in the sub heat exchange section (1b) is suppressed, and the deterioration thereof is reduced. The drained water after draining is drained from the drain outlet located below the heat exchanger (1).
(8) is discharged outside.

In the above embodiment, the cleaning of the sub heat exchange section (1b) is executed immediately after the operation is stopped by the stop switch (24), but the radiator (34) is provided in the circulation flow path (34). H)
A water temperature sensor (S ₁ ) (see the imaginary line in FIG. 1) for monitoring the temperature of the water returning to the sub heat exchange section (1b) from the water temperature sensor;
When the detected water temperature of (S ₁ ) (which is substantially the same as the temperature of the combustion exhaust gas discharged from the sub heat exchange section (1b)) exceeds the dew point temperature, the cleaning valve (B ₃ ) is opened for a predetermined time. You may do it. In other words, when the number of radiators (H) and (H) to be operated is reduced under the condition that multiple radiators (H) and (H) are installed, the amount of heat radiation on the radiator (H) side The temperature of the return water to the sub heat exchange section (1b) may increase due to the decrease in the temperature of the water, which may be higher than the dew point temperature. Then, since no drain is generated in the sub heat exchange section (1b) thereafter, the washing valve (B ₃ ) is opened at this time to clean the sub heat exchange section (1b).

In this case, a control circuit as shown in FIG. 4 can be employed. That is, a temperature determination circuit (71) for monitoring the temperature of the return water to the heat exchanger (1) (which is substantially the same as the temperature of the combustion exhaust in contact with the sub heat exchange section (1b)), The inverted output of the flip-flop (29), which is the same as that of
The control circuit applied to the differentiating circuit (20) via 2) is employed. And the temperature determination circuit (71) is a heat exchanger.
It comprises a water temperature sensor (S ₁ ) for detecting the temperature of the return water to (1) and a temperature comparator (74) for comparing the output of a temperature setter (73).

In this apparatus, the dew point temperature at which the combustion exhaust is condensed is set and used by the temperature setting device (73). Then, the detected water temperature of the water temperature sensor (S ₁ ) (the temperature of the return water to the heat exchanger (1)) exceeds the dew point temperature set by the temperature setting device (73), and the output of the temperature comparator (74) Rises, the rising signal is detected by the differentiating circuit (20), and the mono-multivibrator (44) is energized for a predetermined time by the differentiated signal to open the washing valve (B ₃ ). That is, the sub heat exchange section (1b) of the heat exchanger (1) is washed. In addition, the washing valve (B
The set temperature (dew point temperature) of the temperature setter (73) which becomes the valve opening condition of ₃ ) varies depending on conditions such as exhaust gas composition based on the gas type and the like, the outside air temperature, etc., and the set temperature is 45 ° C to 60 ° C.
Is preferable, and about 56 ° C. is particularly desirable. Also, in this embodiment, when the stop switch (24) is operated, the cleaning valve (B ₃ ) is opened for a predetermined time as in the case of FIG. The exchange unit (1b) is cleaned.

In this case, when the drain is no longer generated in the sub heat exchange section (1b), that is, when the generated drain adheres to the heat absorbing fins (12) and (12) of the sub heat exchange section (1b). When this begins to dry, it can be washed away immediately, so that the inconvenience of combustion products generated by drying of the drain on the heat absorbing fins (12) and (12) can be prevented.

In the above embodiment, the cleaning operation is performed when the temperature of the water returning to the sub heat exchanger (1b) (the temperature detected by the water temperature sensor (S ₁ )) becomes higher than the dew point temperature. However, as shown by the imaginary line in FIG. 1, the exhaust gas temperature of the combustion exhaust gas flowing out of the sub heat exchange section (1b) (it is almost the same as the temperature of the water returning to the sub heat exchange section (1b)) The exhaust temperature sensor (S ₂ ) for detecting the temperature may be disposed in the exhaust passage (21), and the exhaust temperature sensor (S ₂ ) may be used in place of the water temperature sensor (S ₁ ).

In each of the above embodiments, only the auxiliary heat exchange section (1b) is cleaned by the shower apparatus (B). However, the shower apparatus (B) is connected to the main heat exchange section (1a). ), And spray water from the shower device (B) onto the main heat exchange section (1a) and the sub heat exchange section (1b) to clean the entire heat exchanger (1). You may do it. Main heat exchange section (1a)
In this case, since there is a part where the generation of drain cannot be completely prevented, the entire inside of the heat exchanger (1) including the part is cleaned to further improve the effect of preventing deterioration.

Further, in any of the above embodiments, the shower device (B) is operated for a fixed time when the sub heat exchange section (1b) is washed, but the amount of water supplied to the shower device is changed. May be provided, and after the gas burner extinguishes, the flushing valve (B ₃ ) may be opened until the amount of water supplied by the flow counter reaches a predetermined value. Further, in any of the above embodiments, the present invention is applied to a circulation type hot water heater, but the present invention may be applied to a water heater for supplying hot water to a bath or a kitchen.

Further, the fan (4) may be provided in the exhaust passage (21), and the sub heat exchange section (1b) in the heat exchanger (1) may be formed in a plurality of stages instead of a single stage. Is also good. When the sub heat exchange section (1b) has a multi-stage configuration, the sub heat exchange section
It is not necessary to supply water from the lowermost stage in (1b), and the water pipes (1
1) Water is supplied from the portion, and the water is supplied to the main heat exchange portion (1a) after passing through the entire sub heat exchange portion (1b).

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a sub heat exchange portion (1b) cut in parallel with a running direction of a water pipe (11) in the embodiment of the present invention.

FIG. 3 is a control circuit diagram

FIG. 4 is a control circuit diagram applied to another embodiment.

FIG. 5 is an explanatory view of a conventional example.

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

[Explanation of symbols]

 (1) ... heat exchanger (3) ... gas burner (4) ... fan (11) ... water pipe (21) ... exhaust passage

Continuation of front page (56) References JP-A-63-286657 (JP, A) JP-A-6-317348 (JP, A) JP-A-63-62568 (JP, A) JP-A-6-147646 (JP) , A) (58) Field surveyed (Int. Cl. ⁶ , DB name) F24H 1/10 303 F28G 9/00

Claims (4)

(57) [Claims] A part of a water pipe (11) having a large number of heat absorbing fins (12) (12) on the outer periphery is used as a main heat exchange part (1a),
The water pipe section upstream of the main heat exchange section (1a) is
(1b), the main heat exchange section (1a) and the sub heat exchange section (1b) are sequentially arranged in this order downstream of the gas burner (3) in the exhaust stream, and the main heat exchange section (1a) In a heat exchange device that absorbs the sensible heat of the combustion exhaust gas and absorbs latent heat from the combustion exhaust gas in the sub heat exchange section (1b), the water pipe (11) and heat absorption in the sub heat exchange section (1b) A shower device (B) for sprinkling washing water is provided on the surfaces of the fins (12) and (12), and the drain attached to the water pipe (11) and the heat absorbing fins (12) and (12) is provided by the shower device (B). A heat exchange device that is cleaned as needed. 2. A fire extinguisher signal generating circuit for outputting a fire extinguishing signal when the gas burner (3) stops burning, and when the fire extinguishing signal is generated, the shower device (B) is provided only for a predetermined time or until the amount of water jetted reaches a predetermined amount. The heat exchange device according to claim 1, wherein the heat exchanger is operated. 3. The temperature of the water flowing into the sub heat exchange section (1b) is detected.
Water temperature sensor (S ₁) And the water temperature sensor (S₁) Detects
Compare the water temperature with the dew point temperature at which the combustion exhaust will condense.
Signal when the former water temperature exceeds the dew point temperature.
A temperature judgment circuit (71) is provided, and when the cleaning signal is generated.
For a specified period of time or until the amount of water discharged reaches a specified amount.
2. The heat exchanger according to claim 1, wherein the heater device (B) is operated.
Exchange device. 4. An exhaust gas temperature sensor (S ₂ ) for detecting the temperature of the combustion exhaust gas discharged from the sub heat exchange section (1b), and the exhaust gas temperature sensor
(S ₂₎ provided the temperature judging circuit (71) which issues a cleaning signal when the former exhaust temperature exhaust temperature and combustion exhaust compares the dew-point temperature so that the dew condensation is equal to or higher than the dew point temperature detected, the 2. The heat exchange device according to claim 1, wherein when the washing signal is generated, the shower device (B) is operated only for a predetermined time or until the amount of the jetted water reaches the predetermined amount.