Direct-contact type hot water heater

A direct-contact type hot water heater includes a perforated plate having a slope allowing water to flow down from its top apex toward its lower surroundings along both or all sides of the slope in the form of a water film. The perforated plate is provided with a number of apertures capable of forming the water film by surface tension. An endothermic material is arranged in a state where it does not project from the lower surface of the perforated plate.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a direct-contact type hot water heater in 
which the water, scattered and coming down from above, is designed to flow 
down along the surrounding side walls of a high-temperature gas feed 
chamber in the form of a water film without coming down into the feed 
chamber, whereby, even when fuel is burned in the feed chamber, the 
efficiency of combustion is improved and the side walls of the feed 
chamber are prevented from burning off. 
2. Statement of the Prior Art 
Hithereto, there has been known from Japanese Utility Model Publication 
Nos. 38-15983, 43-31828 and 43-31833 as well as Japanese Patent 
Publication No. 37-17440, the technology relating to the direct-contact 
type hot water heaters of the structure wherein a high-temperature gas 
feed chamber is provided above a hot water reservoir located on the 
lowermost portion and an endothermic chamber filled therein with an 
endothermic material is provided above the high-temperature gas feed 
chamber so as to bring the water, which is scattered on the endothermic 
material from above the endothermic chamber and is coming down, into 
direct contact with a combustion gas resulting from the combustion of fuel 
in the high-temperature gas feed chamber and thereby obtain hot water of a 
desired temperature in the lowermost hot water reservoir. 
Such direct-contact type hot water heaters excel extremely in thermal 
efficiency owing to their structure that the water to be heated comes into 
direct contact with the combustion gas in the course of flowing from the 
endothermic chamber located above the high-temperature gas feed chamber 
down into the lowermost hot water reservoir. Moreover, such direct-contact 
type hot water heaters-can easily be used even at home owing to the system 
in which water is heated at atmospheric pressure, unlike the conventional 
boiler system for obtaining hot water in a closed vessel. Additionally, 
they provide hot water which is free from dissolved oxygen and is thus 
effective in view of rustproofness. Morever, carbon dioxide contained in 
the combustion gas is entrapped in the hot water, which means that, when 
the hot water is used for bathing, it produces an excellent effect such as 
refreshment which is not attained with hot water obtained by heating usual 
service water by means of a bath heater. Thus, direct-contact type hot 
water heater according to the present invention is expected to find a wide 
use. 
However, the conventional direct-contact type hot water heaters are 
disadvantageous in that their structure is complicated, their installation 
cost is high, or the combustion gas generated by the combustion of fuel in 
the combustion chamber does not smoothly flow upwardly. This latter 
disadvantage can be due to the fact that a perforated plate for supporting 
the endothermic material filled above the high-temperature gas feed 
chamber is formed of a horizontally arranged flat plate, a network member 
depends from the lower end of an umbrella-like member having no vent, as 
disclosed in Japanese Utility Model Publication No. 38-15983,or 
umbrella-like members called the flame-dispersing members are supported at 
intervals in a multi-staged manner or an umbrella-like member is louvered 
into a complicated shape so as to prevent water from coming down thereon, 
as disclosed in Japanese Patent Publication No. 37-17440. 
SUMMARY OF THE INVENTION 
As a result of intensive and extensive studies made to overcome the 
problems of the perforated plate for supporting an endothermic material 
filled above the high-temperature gas feed chamber of the conventional 
direct-contact type hot water heater, it has been found that such problems 
are eliminated, if provision is made of a perforated plate which includes 
a slope allowing water to flow down from its top apex toward its lower 
surroundings along both or all sides thereof in the form of a water film 
and is provided therein with a number of apertures capable of forming the 
water film by surface tension, and an endothermic material is arranged in 
a state where it does not project from the lower surface of the perforated 
plate. 
More specifically, the present invention provides a direct-contact type hot 
water heater including the lowermost hot water reservoir, a 
high-temperature gas feed chamber located thereabove, and an endothermic 
chamber filled therein with an endothermic material and located above the 
feed chamber, whereby the water, scattered on the endothermic material and 
coming down, is brought into direct contact with a high-temperature gas 
supplied to the feed chamber to obtain hot water of a desired temperture 
in the reservoir. A perforated plate located above the hot water reservoir 
includes a slope allowing water to flow down from its top apex toward its 
lower surroundings along both or all sides of the slope in the form of a 
water film. The perforated plate has a number of apertures capable of 
forming the water film by surface tension. The endothermic material is 
arranged in a state where it does not project from the lower surface of 
the perforated plate.

DETAILED EXPLANATION OF PREFERRED EMBODIMENTS 
Referring to the drawings, a heater body generally shown at 1 is provided 
with a hot water reservoir 2 at its lowermost portion. Above the reservoir 
2 there is provided a high-temperature gas feed chamber 3. In the chamber 
3 fuel is burned. The fuel is supplied through a burner 4 such as an oil 
or gas burner mounted on the side of the heater body 1 as shown in FIG. 1, 
or a gas or oil burner (not illustrated) mounted within the 
high-temperature gas feed chamber 3, or a burner (not illustrated) mounted 
below a combustion flame injection port passing through the reservoir 2. 
Alternatively, the chamber 3 may be supplied with a combustion gas from a 
separate device designed to obtain power by burning fuel such as an engine 
or turbine (hereinafter referred to as the engine, etc.), the device being 
spaced away from the heater body 1. As will be described later, the 
high-temperature gas is then allowed to come into direct contact with 
water, and is discharged, after heating the water, from the upper portion 
of the heater body 1. 
An endotheronic chamber 5 is located above the high-temperature gas feed 
chamber 3, and it is partitioned from the high-temperature gas feed 
chamber 3 by a perforated plate 6 having a top apex 6a. The perforated 
plate can be formed, e.g., of a heat-resistant, metallic plate, on which 
an endothermic material 7 is filled. The perforated plate 6 is of a shape 
including a slope allowing water to flow down along its both or all sides 
from the top apex 6a toward the lower surroundings in the form of a water 
film (e.g., a conical or pyramidal shape of an angle of inclination, 
practically, of 10.degree. or wider. The plate 6 is provided therein with 
a number of apertures 6b capable of forming a water film 11 by surface 
tension. 
In order to cause the perforated plate 6 to form the water film 11 flowing 
down along its both or all sides and to allow the apertures 6b to form the 
water film 11 by surface tension, it is required that the surface of the 
perforated plate 6 show good affinity with respect to water and be free 
from such an inert film as that formed on the surface of an oil or 
lustrous stainless steel so as to allow water to flow down along its both 
sides in the form of the thin water film 11. It is also required that the 
endothermic material 7 be restrained from projecting from the lower 
surface of the perforated plate 6 for the purpose of preventing 
destruction of the water film 11, as shown at A in Figure 3. 
A water feed nozzle 8 is provided above the endothermic material 7 filled 
in the endothermic chamber 5 to scatter the water to be heated. A stack 9 
is provided above the endothermic chamber 5 of the heater body 1 to 
discharge the high-temperature gas which has ascended from the 
high-temperature gas feed chamber 3 and heated the water in the 
endothermic chamber 5. A hot water discharge pipe 10 is provided to feed 
the hot water stored in the hot water reservoir 2 to the end place. 
The direct-contact type hot water heater of the structure according to the 
present invention is used in the following manner. 
A combustion gas resulting from fuel burned by means of the burner 4 such 
as an oil burner or a high-temperture gas such as a combustion gas 
obtainable from the engine, etc. is supplied to the high-temperature gas 
feed chamber 3, and the water to be heated is scattered on the endothermic 
material 7 placed on the perforated plate 6 in the endothermic chamber 5 
through the water feed nozzle 8. Thereupon, the high-temperature gas in 
the feed chamber 3 passes through the endothermic chamber 5 and is 
discharged as a low-temperature gas from the stack 9. On the other hand, 
the scattered water flows down through the endothermic material 7 and 
along the slope of the perforated plate 6, during which it is heated by 
the high-temperature gas. The water is then further heated in the course 
of flowing down along both or all sides of the perforated plate 6 to the 
surroundings thereof in the form of the water film 11 and flowing down on 
the surrounding wall surface of the heater body 1 forming the 
high-temperature gas feed chamber 3 in the form of another water film 12. 
The water is finally stored in the reservoir 2, wherein it is additionally 
heated from above its surface to a desired temperature. 
In the direct-contact type hot water heater according to the present 
invention as detailed above, the perforated plate 6 includes a slope 
allowing water to flow down along its both or all sides to the lower 
surroundings in the form of the water film 11 in the course of heating the 
water. The slope is provided therein with a number of apertures 6b capable 
of forming the water film 11 by surface tension, and the endothermic 
material 7 is located in a state where it does not project from the lower 
surface of the perforated plate 6. Thus, the water, which is scattered on 
the endothermic material 7 from above the endothermic chamber 5 and is 
coming down, flows down along both or all sides of the perforated plate 6 
in the form of the water film 11 without causing any water droplet to fall 
down through the apertures 6b into the high-temperature gas feed chamber 
3. Therefore, where the high-temperature gas feed chamber 3 includes the 
built-in burner 4 for the direct combustion of fuel, it is unlikely that 
the burner 4 may not work, or the combustion of fuel may get worse. Since 
the water flowing down through the endothermic material 7 flows down along 
both or all sides of the perforated plate 6 in the form of the water film 
11 and along the surrounding entire wall surfaces of the high-temperature 
gas feed chamber 3 in the form of the water film 12, it is unlikely that 
the perforated plate 6 and the wall surfaces of the high-temperature gas 
feed chamber 3 may be overheated. The direct-contact type hot water heater 
according to the present invention provides an area of contact of the 
high-temperature gas with the water which is larger by the amount of areas 
of the water film 11 formed on both sides of the perforated plate 6 and 
the water film 12 formed along the surrounding entire wall surfaces of the 
chamber 3 as compared with the conventional direct-contact type. As a 
result, the efficiency of thermal transmission of the high-temperature gas 
is greatly improved. 
Further, the direct-contact type hot water heater according to the present 
invention can be easily and inexpensively manufactured owing to the fact 
that the perforated plate 6 used is more simplified in structure than that 
used with the conventional direct-contact type hot water heater.