DISCRETE DOUBLE HEAT EXCHANGE TYPE HOT WATER

BOILER

Technical Field

[1] The present invention relates, in general, to hot water boilers and, more particularly, to a discrete double heat exchange type hot water boiler in which a water chamber, which is provided around a sidewall of a firebox and is nonresistant to the high pressure of service water, is not affected by the pressure of service water, thus preventing a lower part of a main body of the boiler from being damaged by the high pressure of service water, and in which an exhaust hood, a heat exchange unit and the firebox are manufactured apart so as to be separable from each other, so that their packing and carrying processes are easy, and they can be easily assembled together on site. Background Art

[2] Boilers are devices which generate heat water by exchanging heat between water and hot burners. Generally, according to the intended purpose, such boilers are classified into heating boilers, hot water boilers and heating and hot water-combined boilers.

[3] The hot water boilers are mainly used in places where a large amount of hot water is used, for example, public bathhouses, saunas, factories, etc. FIG. 1 is a sectional view showing a conventional hot water boiler. As shown in Fig. 1, in the conventional hot water boiler, a main body 1 is formed in a single body, and a water chamber 2, into which fire tubes 6 are inserted, is defined in the main body 1. Furthermore, a firebox 5 is provided at a lower position in the main body 1, and an exhaust hood 9 is provided on the upper end of the main body 1.

[4] An inlet 3 and an outlet 4, which communicate with the water chamber 2 that is provided in the main body 1 to contain water therein, are formed in the main body 1 such that running water is drawn through the inlet 3 and is discharged through the outlet 4 after being processed through a heat exchange process. The fire tubes 6 are vertically provided through the water chamber 2, so that combustion gas of a burner 10 transfers heat to water, which is in the water chamber 2 surrounding the fire tubes 6, while passing through the fire tubes 6.

[5] In the conventional hot water boiler having the above-mentioned construction, the water chamber 2, having the fire tubes therein, extends to the lower end of the main body 1 and surrounds the firebox 5, which is provided at the lower position in the main body 1. The surface 7 of the water chamber at the junction with the firebox 5 has a

corrugated shape. Furthermore, a lower support plate 8 made of a refractory material is coupled to the lower end of the water chamber.

[6] The burner 10 is mounted at a predetermined position through the lower part of the main body 2. Combustion gas of the burner 10 flows through the firebox 5 to the fire tubes 6, then is exhausted outside through a gas duct after getting together in the exhaust hood 9 provided on the upper end of the main body.

[7] The conventional hot water boiler having the above-mentioned construction has the following differences from a heating boiler with respect to manufacturing process.

[8] The heating boiler uses water, which is heated by combustion gas, as heating water.

The term heating water means heated water that circulates in a pipeline to heat a room. On the other hand, the hot water boiler uses water that is heated by combustion gas, as hot water. The term hot water means heated water, which is discharged through for example a water tap so as to be used in a bath or the like.

[9] Therefore, heating water of the heating boiler is not necessary to be clean, but the cleanliness of hot water of the hot water boiler must be maintained so that it can be used in a bath or the like. For this reason, the main body of the conventional heating boiler can be made of iron material which is inexpensive and has superior strength. However, in the case of the hot water boiler, if the main body thereof is made of iron material, because there is the likelihood of the occurrence of rust, the main body of the conventional hot water boiler must be made of metal, such as copper or stainless steel, or must be manufactured by using zinc-galvanized iron material.

[10] Furthermore, in the case that a hot water coil, which is connected to a running water pipe, is provided in the heating boiler so as to make it possible to use hot water, the hot water coil is made of copper, differently from the material of the main body of the heating boiler.

[11] Meanwhile, the main body of the conventional hot water boiler is formed in an single structure. The water chamber, which contains therein water for the supply of hot water, extends to the lower end of the sidewall of the firebox. The water chamber is constructed such that it sustains the pressure of service water, the pressure of a water tank which is placed on the top of a house or the pressure of a water supply pump, as well as expansion pressure of its own water when hot water is generated. However, the part of the water chamber disposed around the firebox in the lower part of the main body and the part of the water chamber around the burner seating hole, to which heat from the burner is directly applied, are directly affected both by flames of the burner and by the pressure of running water to be supplied. Accordingly, these parts are structurally fragile, so that they can not bear up against expansion pressure of heated water and pressure of exterior water service, thus be easily ruptured by excessive high pressure of running water and the pressure difference between their inside and outside.

[12] To prevent these problems, regulators or safety pins have been used. However, the regulator has a disadvantageous effect on mass water supply, in which a large amount of hot water is discharged in a short time. The safety pin wastes energy by draining hot water when the hot water boiler is not in service to control pressure in the boiler.

[13] Furthermore, a large amount of material is required to ensure sufficient thickness of the sidewall of the main body of the boiler, and the surface of the water chamber which is around the sidewall of the firebox is corrugated to form a pressure-resistant structure. Therefore, the conventional hot water boiler has disadvantages in that the workability is reduced and the manufacturing cost thereof is increased.

[14] As well, unlike the heating boilers for home use, almost all of mass storage-hot water boilers, which have capacities from 50,000 kcal to 500,000 kcal and are used in public bathhouses, saunas and factories that require a large amount of hot water, are installed in basements of buildings. Accordingly, in the case of the conventional hot water boiler having an single structure, it is difficult to carry it to a basement, so that it may be required to hire a professional company for transport and installation. Disclosure of Invention Technical Problem

[15] The present invention has been made to solve the above problems occurring in the prior art. An object of the present invention is to provide a discrete double heat exchange type hot water boiler, in which an exhaust hood, a heat exchange unit and a firebox constituting a main body are manufactured apart so as to be separable from each other, so that their packing and carrying processes are easy, and so that they can be easily assembled together on site, and in which a water chamber defined in the firebox is not damaged by water pressure. Technical Solution

[16] In order to accomplish the above object, the present invention provides a discrete double heat exchange type hot water boiler comprising a heat exchange unit having a hot water chamber defined in a cylindrical outer casing and containing hot water therein, a plurality of fire tubes formed through the hot water chamber, and an inlet and an outlet formed through the outer casing to communicate the hot water chamber with an outside; a firebox coupled to a lower end of the heat exchange unit and having a heat exchange water chamber defined in a cylindrical outer casing, with a burner mounted to the firebox through a burner seating hole formed at a predetermined position through a sidewall of the firebox; an exhaust hood coupled to an upper end of the heat exchange unit and having a gas duct through which combustion gas from the fire tubes is exhausted outside; and a heat exchange coil installed in the hot water chamber of the heat exchange unit, the heat exchange coil having an inlet end and an

outlet end respectively connected to the outlet and the inlet of the heat exchange water chamber of the firebox through a circulation pipe, whereby when heat exchange water circulates in the heat exchange coil, heat is transferred between heat exchange water and the hot water in the hot water chamber,.

[17] Preferably, the exhaust hood, the heat exchange unit and the firebox may be manufactured separately to be transportable, and are assembled together using brackets. The discrete double heat exchange type hot water boiler may further comprise a circulation pump provided on the circulation pipe, which connects the heat exchange water chamber of the firebox with the heat exchange coil, whereby forcibly circulating the heat exchange water; and an expansion tank connected to the heat exchange water chamber through a running water pipe.

[18] Preferably, a plurality of heat exchange coils may be installed in the hot water chamber of the heat exchange unit, inlet ends and outlet ends of the heat exchange coils being respectively connected to outlets and inlets formed in the heat exchange water chamber through circulation pipes and circulation pumps are respectively provided on the circulation pipes, so that the heat exchange water transfers heat from the heat exchange water chamber to the hot water chamber while forming a plurality of flow streams.

Advantageous Effects

[19] In the hot water boiler according to the present invention, an exhaust hood, a heat exchange unit and a firebox constituting a main body are manufactured apart so as to be separable from each other. Particularly, because the heat exchange unit and the firebox with relatively large sizes are separably provided, their packing and carrying processes become easy, thus making it easy to carry them in a basement, in which the hot water boiler is mainly installed. Furthermore, the elements of the hot water boiler can be easily assembled together on site. As such, the present invention has advantages of ease of transport and installation. As well, when repair is required, it is possible to separate only the related element from the main body to repair or replace it with a new one. Therefore, after-sales service is simplified.

[20] Furthermore, according to the present invention, because the firebox is not in contact with hot water, it is possible to manufacture the firebox from iron material, which is inexpensive and has superior strength but has been limitedly used due to the probability of occurrence of rust. The iron material has a superior pressure-proof feature and superior workability, for example, superior welding process. Therefore, the present invention reduces manufacturing costs and simplifies the structure thereof. In addition, the present invention is constructed such that the water chamber of the firebox is not dependent on the pressure of service water. Accordingly, unlike the con-

ventional art where the lower part of the boiler is structurally fragile, the present invention has a structure such that the lower part of the main body of the boiler is not affected by the pressure of service water, thus preventing the lower part of the main body from being damaged. Furthermore, because the firebox does not require high pressure resistance and the probability of damage to the firebox is low, processes of machining and manufacturing the boiler are simplified. Moreover, the present invention has an advantage in that the stability of the main body of the boiler is ensured even without a safety pin or a regulator.

[21] In addition, according to the present invention, hot water is heated by both combustion gas flowing in fire tubes and heat exchange water rapidly heated at a position adjacent to the flames. Therefore, the hot water can be rapidly heated as well as can be maintained in a clean state, so that the heat exchange efficiency and the performance of the boiler are markedly enhanced. Brief Description of the Drawings

[22] Fig. 1 is a sectional view showing a conventional hot water boiler;

[23] FIG. 2 is an exploded sectional view showing a main body of a discrete double heat exchange type hot water boiler according to a first embodiment of the present invention;

[24] Fig. 3 is a view showing the construction of the assembled discrete double heat exchange type hot water boiler according to the present invention;

[25] Fig. 4 is a sectional view showing a firebox of a discrete double heat exchange type hot water boiler according to a second embodiment of the present invention; and

[26] Fig. 5 is a view showing the assembled discrete double heat exchange type hot water boiler according to the second embodiment of the present invention. Best Mode for Carrying Out the Invention

[27] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[28] Fig. 2 is an exploded sectional view showing a main body of a discrete double heat exchange type hot water boiler according to a first embodiment of the present invention. Fig. 3 is a view showing the construction of the assembled discrete double heat exchange type hot water boiler of the present invention.

[29] As shown in Fig. 2 and Fig. 3, the first embodiment of the present invention comprises an exhaust hood 20, a heat exchange unit 30 and a firebox 50 which are manufactured apart so as to be assembled together. The first embodiment further comprises a heat exchange coil 60 provided in the heat exchange unit 30.

[30] The heat exchange unit 30 includes a hot water chamber 35 which is an upper water chamber that is defined by a cylindrical outer casing 32 and by upper and lower plates

34, 36 respectively coupled to the upper and lower ends of the outer casing. The heat exchange unit 30 further includes a plurality of fire tubes 38 vertically arranged through the hot water chamber 35, and combustion gas flows in the fire tubes 38. Heat is transferred between combustion gas flowing in the fire tubes 38, and water, that is, hot water, which is in the hot water chamber 35 and surrounds the fire tubes 38.

[31] Furthermore, the heat exchange unit 30 includes an inlet 42 and an outlet 44 which are formed at predetermined positions through the outer casing 32 and communicate with the hot water chamber 35. The inlet 42 is connected to a water supply pipe and serves as a passage which receives water to be used for hot water. The outlet 44 serves as a passage which discharges water, which has been heated in the hot water chamber

35, towards a water tap of a bathroom or the like.

[32] Meanwhile, the heat exchange coil 60, which is wound in a spiral shape, is installed in the hot water chamber 35 of the heat exchange unit 30. An inlet end 62 and an outlet end 64 of the heat exchange coil 60 extend outside through the outer casing 32 of the heat exchange unit 30 and are connected to circulation pipes 65.

[33] The firebox 50 is manufactured separately from the heat exchange unit 30, and is attached to the lower end of the heat exchange unit 30. The firebox 50 includes a heat exchange water chamber 55, which is a lower water chamber defined in a cylindrical outer casing 52 and is formed separately from the hot water chamber 35 of the heat exchange unit 30. Heat exchange water is not discharged outside, unlike hot water, but is used as a heat exchange medium, which circulates to realize heat exchange. The heat exchange water chamber 55 has an outlet 58, which is formed through a sidewall at a position adjacent to a burner seating hole 11, and an inlet 57, which is formed through the sidewall at a position opposite the burner seating hole 11 and adjacent to an upper end plate 56. The outlet 58 and the inlet 57 are respectively connected to the inlet end 62 of the heat exchange coil 60 and to the outlet end 64 through the circulation pipes 65, such that heat exchange water circulates in the heat exchange coil 60 provided in the hot water chamber 35 of the heat exchange unit 30. The burner seating hole 11 is formed at a predetermined position through the sidewall of the heat exchange water chamber 55.

[34] Furthermore, a circulation pump 70 is provided on one of the circulation pipes 65, which connects the heat exchange water chamber 55 to the heat exchange coil 60 to circulate heat exchange water. Preferably, the circulation pump 70 is provided on the circulation pipe 65, which is disposed between the outlet 58 of the heat exchange chamber 55 and the inlet end 62 of the heat exchange coil 60, so that heat exchange water, which is discharged through the outlet of the heat exchange water chamber 55 by pumping pressure of the circulation pump 70, is pumped into the heat exchange coil 60, thus the heat exchange water forcibly circulates between the heat exchange water

chamber 55 and the heat exchange coil 60.

[35] The heat exchange water chamber 55 is connected to an expansion tank 80. The heat exchange water chamber 55 and the heat exchange coil 60 define a heat exchange water circulation path. Here, because the heat exchange water chamber 55 is connected to the expansion tank 80, the heat exchange water, which circulates in the heat exchange water chamber 55 and the heat exchange coil 60, is maintained at atmospheric pressure, thus preventing the boiler from being affected by expansion pressure generated when heating water. Furthermore, the expansion tank 80 is connected to the water supply pipe and is constructed such that water is automatically supplied into the expansion tank 80 using a float valve 82. Thus, even if some heat exchange water is lost through, for example, evaporation, in a circulation process, an amount of water corresponding to the lost amount is automatically supplemented. Furthermore, the expansion tank 80 may be coupled to an extension line of the circulation pipe 65 through a branch pipe. In this case, because the circulation pipe 65 is connected to the heat exchange water chamber 55, it is substantially equal to the case in which the expansion tank 80 is directly connected to the heat exchange water chamber 55 through a branch pipe, in that the heat exchange water is open to the atmosphere.

[36] Meanwhile, the heat exchange unit 30 is installed on the upper surface of the upper end plate 56, which has a U-shaped cross-section and is bolted to the upper end of the heat exchange water chamber 55 of the firebox 50 using brackets 31 and 51. In other words, the upper end plate 56 serves as a support for the heat exchange unit 30.

[37] A burner 10 is mounted to the firebox 50 through the burner seating hole 11 formed through the sidewall of the firebox 50. Combustion heat of the burner 10 heats the heat exchange water chamber 55 defined at the side of the firebox 50 and heats the hot water chamber 35 while moving along the fire tubes 38 of the heat exchange unit 30. Furthermore, an overheat detecting sensor 59 is installed in the heat exchange water chamber 55 so that, when the heat exchange water chamber 55 is overheated, the operation of the burner 10 is automatically stopped.

[38] The exhaust hood 20 is placed on the upper end of the heat exchange unit 30 and is bolted together using brackets 21 and 31. In the exhaust hood 20, combustion gas, which has passed through the fire tubes 38, is exhausted outside through a gas duct 25.

[39] Fig. 4 and Fig. 5 illustrate a discrete double heat exchange type hot water boiler having a plurality of heat exchange coils according to a second embodiment of the present invention. Fig. 4 is a sectional view of a firebox of the hot water boiler. Fig. 5 is a view showing the assembled hot water boiler.

[40] Referring to the drawings, Fig. 4 shows one set of two pairs of pipe holes, that is, two outlets 58a, 58b and two inlets 57a, 57b which are provided in a heat exchange

chamber 55 of the firebox. The two outlets 58a, 58b are provided in a sidewall of the firebox at positions adjacent to a burner seating hole 11. The two inlets 57a, 57b are provided in the sidewall of the firebox at positions opposite the burner seating hole 11. Fig. 5 shows the two heat exchange coils 60a, 60b installed in a hot water chamber 35 of a heat exchange unit 30.

[41] In the hot water boiler, as the capacity thereof is increased, the size of the main body of the boiler is increased. The increase in size of the boiler results in an increase of the amount of hot water contained in the hot water chamber 35. Thereby, the capacity of hot water supply is increased, and, in addition, the capacity of the heat exchange chamber 55 is increased so that the amount of heat exchange water is increased. Of course, an increase in the capacity of a burner 10 results in increased combustion heat. Due to the increase of combustion heat of the burner 10, an increase in the flow rate of heat exchange water is required to prevent the firebox 50 from overheating, and to reduce heat loss. In this case, a method of increasing the flow rate of heat exchange water by increasing both the capacity of a circulation pump and the diameter of the heat exchange coil 60 may be considered. However, it is more efficient to install a plurality of exchange coils 60a, 60b in the hot water chamber 35 of the heat exchange unit 30 such that heat exchange water circulates in the plurality of exchange coils 60a, 60b.

[42] In detail, the first heat exchange coil 60a and the second heat exchange coil 60b are separately disposed at upper and lower positions in the hot water chamber 35 of the heat exchange unit 30. Their inlet ends 62a, 62b and outlet ends 64a, 64b are respectively connected to the outlets 58a, 58b and the inlets 57a, 57b, which are provided in the heat exchange water chamber 55, through circulation pipes 65a, 65b. Furthermore, circulation pumps 70a, 70b are respectively provided on the circulation pipes 65a, 65b, which respectively connect the outlets 58a, 58b of the heat exchange water chamber 55 with the inlet ends 62a, 62b of the heat exchange coils 60a, 60b.

[43] The operation and effect of the discrete double heat exchange type hot water boiler of the present invention with the above-mentioned construction will be explained with reference to Fig. 2 and Fig. 3.

[44] In the present invention, the exhaust hood 20, the heat exchange unit 30 and the firebox 30 are manufactured separately and bolted together using the brackets 21, 31 and 51. Particularly, the heat exchange chamber 55, which is provided on the sidewall of the firebox 50, does not contain hot water to be used for bathing or the like. Therefore, while the heat exchange unit 30 and the heat exchange coil 60, which must maintain superior cleanliness, should be made of copper or stainless steel without possibility of rust, as in the conventional art, the firebox 50 may be made of iron material, which is relatively inexpensive and ensures sufficient strength. Furthermore,

because the heat exchange water chamber 55 of the firebox 50 is not dependent on the pressure of service water supply, it is not required to form an inner casing 54 of the heat exchange water chamber 55 in a corrugated shape to deal with excessive water pressure. Therefore, it is possible to make the inner casing relatively thin, so it is easy to machine and manufacture it.

[45] In addition, in the present invention, the heat exchange unit 30 is mounted onto the upper surface of the upper end plate 56 of the firebox 50. Therefore, the firebox 50 serves as a support for the heat exchange unit 50, thus making it easy to conduct the assembly work. After the heat exchange unit 30 is placed on the upper end plate 56 of the firebox 50, the junction therebetween is sealed, and the brackets 31 and 51, which are respectively attached to the sidewall of the heat exchange unit 30 and the firebox 50, are fastened to each other by bolting, thus completing the assembly process.

[46] Fuel supplied from a fuel supply device (not shown) is injected into the firebox 50 through the burner 10 and is ignited to generate combustion heat. Combustion gas first heats the heat exchange water chamber 55 of the firebox 50 to warm the heat exchange water. Because the heat exchange water chamber 55 has a volume smaller than the hot water chamber 35 and is disposed at a position that is directly affected by the flames, the heat exchange water chamber 55 is heated relatively rapidly.

[47] Thereafter, the combustion gas flows upwards and heats the fire tubes 38 while passing through the fire tubes 38, so that hot water in the hot water chamber 35 surrounding the fire tubes 38 is heated.

[48] At this time, the heat exchange water heated in the firebox 50 is circulated in the heat exchange coils 60, which are in the heat exchange water chamber 35 of the heat exchange unit 30, by the circulation pump 70. As a result, the hot water in the hot water chamber 35 of the heat exchange unit 30 is heated by double heat exchange both with the combustion gas which flows in the fire tubes 38, and with the heat exchange water which flows through the heat exchange coil 60.

[49] Meanwhile, the heat exchange water maintains the state of being open to the atmosphere through the expansion tank 80, and water is automatically supplemented by the expansion tank 80, thus preventing the heat exchange water chamber 55 from being damaged by the expansion pressure of water. Furthermore, even if some heat exchange water is lost by some causes, for example, by cold evaporation, an amount of water corresponding to the shortage is automatically supplemented.

[50] As well, to prepare for when the boiler is overheated by the accumulation of combustion heat by the burner 10, the overheat detecting sensor 59 is provided in the heat exchange water chamber 55, so that, when the boiler is overheated, the operation of the burner 10 is automatically stopped, thus increasing the safety thereof. That is, when the overheat detecting sensor 59 detects an overheat condition, the operation of

the burner 10 is stopped while heat exchange water is circulated by the circulation pump 70 and transfers heat from the firebox 50 to the heat exchange unit 30. Meanwhile, the circulation pump 70 is controlled such that it is operated only when the temperature of heat exchange water is increased above a preset temperature.