JP2918375B2 - Gas water heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a means for heating a liquid using a gas or a vaporized fuel, and provides a compact water heater having a high-performance combustion and heat exchange function.

[0002]

2. Description of the Related Art A so-called hot water heater that heats a liquid such as water by burning fuel is a hot water heater that has a considerable amount of hot water storage tank and an instantaneous hot water supply that quickly heats and supplies hot water without having a hot water storage tank. Each of them had a burner for completely burning the fuel and a heat exchanger for transferring heat to the liquid in the can or the water tube. In addition, since the flame generated by the burner reaches a considerable length, if there is an obstacle such as the main heat exchanger there is a risk of incomplete combustion, so the distance between the burner and the main heat exchange must be increased. In general, a configuration is provided in which a space for fully burning the flame is formed as a combustion chamber.

[0003] In contrast to such a conventional water heater configuration,
It is also possible to improve the combustion chamber by making the combustion chamber shorter by adopting forced premixed combustion, and compact water heaters have emerged.However, in both cases, the burner and heat exchanger are separated. Thus, in the case of such a configuration in which the combustion chamber is made a little smaller, it is necessary to maintain complete combustion, and therefore, it has a complicated control mechanism for performing combustion control by forced premixing.

[0004]

The present invention firstly requires that the above-mentioned prior art water heater requires a large-volume combustion chamber space for complete combustion, and therefore the outer dimensions and weight of the water heater are reduced. The purpose is to eliminate the disadvantage of being large. Second, the burner and the combustion control device, including those of the forced premixed combustion, become complicated and costly,
It is an object of the present invention to provide a water heater with a relatively simple configuration, which is compact and has high efficiency, while preventing the disadvantage that heat utilization efficiency is not sufficient.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has the following structure.

That is, according to the first aspect of the present invention, in a water heater in which a gaseous fuel or a liquid fuel is vaporized and burned and the liquid is heated by the heat, an outer shell 1 forming a passage for a combustion chamber and a combustion exhaust gas. A multi-stage water pipe for heat exchange is provided inside, and the water pipes of each stage are connected so that the water passages are connected in series, and fuel gas previously mixed with air reaches the finned water pipe 2 in the outer shell first. In doing so, the fins are fixed to the water pipes in such a way that the finned water pipe itself has a function as a burner flame outlet, and the flame is formed in the gap between the fins or at a position slightly protruding to the discharge side. It is characterized by the following. Also, regarding claim 2, claim 1 above
In the water heater according to the invention, at least three stages of water pipes are provided in the outer shell 1 so that the first mixture in which the mixture of fuel and air first arrives.
The tier water pipe shall have fins fixed in such a way as to form the burner flame itself, the second tier water pipe shall have a reduced fin density or no fin, The water pipe of the tier has a relatively large heat transfer area for the purpose of improving heat exchange.

[0007]

The present invention has the above-mentioned structure, and operates as follows.

[0008]

The burner provided separately from the heat exchanger in the water heater of the prior art is abolished, and among the water tubes provided in the multistage in the outer shell 1, the fuel previously mixed with air reaches first. A fin for enhancing the heat exchange action is fixed to the first-stage water pipe, and the fin is configured as if it were a burner of the burner, so that the water pipe with the fin acts as a burner. . Since the flame when the fuel is burned is formed in the gap between the fins or at a position slightly discharged to the discharge side, a large-volume combustion chamber for completely performing the combustion is not required. In addition, a flashback phenomenon that often occurs with a rise in the temperature of the burner body can be prevented because the passage through which the fuel gas mixture located in front of the flame opening and the fuel mixture is constantly cooled by the water pipe can be prevented. Load combustion is realized. Further, since the gap and length of each heat absorbing fin can be freely designed, the flame is stabilized and the combustion control becomes easy. Since a flame is formed in or near the gap between the fins, a turbulence effect of the air current and a condensation effect of the water vapor in the combustion gas are simultaneously generated, which has an effect of increasing the efficiency of heat transfer from the flame.

[0009]

According to the invention of claim 2, at least three stages of water pipes are provided in the outer shell 1, and assuming that the first-stage finned water pipe according to the invention of claim 1 acts as a burner,
When the high-temperature combustion gas passes through the second-stage water pipe that arrives next, it is cooled to an appropriate temperature, and the high-temperature gas has the effect of suppressing the generation of harmful nitrogen oxides generated in the air.
That is, in general, the combustion temperature of gaseous fuel in premixed combustion is 16
Although the temperature reaches 00 ° C. to 1800 ° C., it is cooled to about 1000 ° C. to 1200 ° C. in the second stage water pipe, so that the generation of the nitrogen oxides is greatly reduced. Also,
A third-stage water pipe is provided to sufficiently exchange heat with the liquid, but the combustion gas that has passed through the second-stage water pipe contains some unburned gas such as carbon monoxide therein. Since there is a possibility that the temperature of the combustion gas is maintained at about 1000 ° C., there is an effect of completely burning in the space between the second-stage water pipe and the third-stage water pipe. In the third stage water pipe, the combustion gas slightly heated by complete combustion exchanges its heat with the liquid in the water pipe mainly through fins for heat absorption etc., and heats the liquid, and at the same time, produces low temperature and clean combustion exhaust. Released. The number of water pipes is not limited to three, but may be four or more. It is also possible to provide a large number of water passages in parallel. However, as long as the above-described stepwise combustion gas passage configuration is provided, the same effect is generated. .

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

FIG. 1 is a diagram showing an embodiment of the first aspect of the present invention. In the figure, reference numeral 1 denotes an outer shell which incorporates multi-stage water pipes 2 and 3 for heat exchange of a liquid and forms a passage for a combustion chamber 9 and exhaust gas. A large number of fins 4 are fixed to the first-stage water pipe 2 such that the gap or the tip of the fin 4 serves as a burner port of the burner. Is supplied. The gas mixture is ignited in the fin 4 by an ignition device 7 to form a flame 8. The length and shape of the fin gap and the fin serving as the flame outlet are set so that the flame is stably formed inside the gap between the fins or at a position slightly protruding from the fin. Reference numeral 9 denotes a relatively small-volume fuel chamber for complete combustion of the fuel. The hot air passing through the fin 4 passes through the heat exchange water pipe 3 and exchanges heat with the internal liquid. Will be released. In the drawing, reference numeral 11 denotes a distribution rectifying plate for improving rectification and distribution of the air-fuel mixture, which is made of a punching metal, a wire mesh, or the like. Reference numeral 12 denotes a motor for driving the blower 6. In the embodiment of the present invention, in addition to the one shown in FIG. 1, the direction of passage of the liquid may be reversed, and the combustion may be downward or sideways. Further, the water pipes 2 and 3 are not limited to one each, and a large number of water pipes can be provided in parallel. It is also conceivable to supply the mixture to the outer shell by providing all mixing methods or a separate mixer. In addition, in some cases, it is possible to provide no fins in the water pipe 3 in order to satisfy the required heat exchange. This is very important.

FIG. 2 is a diagram showing one embodiment of the second aspect of the present invention. In the figure, a first-stage water pipe 2 and a second-stage water pipe 3 are provided in an outer shell 1, and the liquid to be heated passes through the water pipes 2, 3, and 3 'and is heated. ing. The method of supplying the fuel and the air-fuel mixture to the outer shell and the means for forming the gap between the fins provided in the water pipe 2 to be a flame outlet are the same as those shown in FIG. 1 of the first embodiment and the embodiment of the present invention. is there. The flame 7 formed near the first-stage water pipe 2 becomes high-temperature combustion gas, passes through the primary combustion chamber 9, and passes through the second-stage water pipe 3.
And cooled by contact with the water pipe, thereby suppressing the generation of nitrogen oxides generated by the high-temperature gas and increasing the temperature of the liquid to be heated. The combustion gas further reaches the secondary combustion chamber 9 'to completely oxidize and burn the unburned products and reaches the water pipe 3' with a slight rise in temperature. The water pipe 3 'is desirably provided with an endothermic fin for heat exchange in order to perform sufficient heat exchange, where heat exchange between the combustor and the liquid is finally performed. Thus, the liquid is heated to the required temperature, while the combustion exhaust is cooled down and discharged out of the shell in a clean gaseous state. The embodiments of the present invention are not limited to those shown in the drawings, and there may be a case where a multi-stage water pipe exceeding three stages is provided, and a case where no fin other than the water tube 2 is provided. In addition, there are various applications similar to those described in the first embodiment.

[0013]

According to the present invention, a separate burner is abolished, and the heat exchange water pipe for heating the liquid is configured as if it were a burner. Therefore, the present invention is extremely compact as compared with a conventional water heater. A high output and high efficiency device can be obtained. In addition, since flames can be formed in the gaps between the fins, the control of combustion is simplified, and the effect of the present invention is large, such as being inexpensive and lightweight. In the case where at least three water tubes are provided in the outer shell as described in claim 2, the generation of nitrogen oxides generated during combustion is reduced, and more complete combustion action and increase in thermal efficiency are achieved. Is very effective, and its applicability and implementation effect are extremely large.

[Brief description of the drawings]

FIG. 1 is a partial sectional configuration view according to a first aspect of the present invention.

FIG. 2 is a partial sectional configuration view according to a second aspect of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer body 2 Water pipe 3 Water pipe 3 'water pipe 4 Fin 5 Fuel ejection nozzle 6 Blower 7 Ignition device 8 Flame 9 Combustion chamber 9' Combustion chamber 10 Outlet 11 Distribution rectifying plate 12 Motor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-140855 (JP, U) JP-A-62-39120 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F24H 9/00 F23D 14/02 F24H 1/14

Claims (2)

(57) [Claims] 1. A water heater in which a gaseous fuel or a liquid fuel is vaporized and burned, and the liquid is heated by the heat.
A multi-stage water pipe for heat exchange is provided in an outer shell 1 forming a passage for a combustion chamber and fuel exhaust, and the water pipes of each stage are connected so that water passages are connected in series, and a fuel mixed in advance with air is provided. When the gas first reaches the finned water pipe 2 in the outer shell,
The fins are fixed to the water pipes in such a way that the finned water pipe itself has the function of a burner flame outlet, and the flame is formed in the gap between the fins or at a position slightly protruding from the discharge side. A water heater characterized by the following. 2. A water pipe of at least three stages is provided in the outer shell 1, and a first-stage water pipe to which a mixture of fuel and air first reaches is formed so as to itself form a burner port of a burner. The fins shall be fixed, the second-stage water tubes shall be of low fin density or have no fins, and the third-stage water tubes shall be relatively conductive for better heat exchange. 2. The heat area is increased.
Water heater shown.