WO2006041245A1

WO2006041245A1 - Pipe laying structure of heat exchanger for boiler and hot water supply

Info

Publication number: WO2006041245A1
Application number: PCT/KR2005/000806
Authority: WO
Inventors: Heung Min Yoo; Young Chang Baek
Original assignee: Kyungdong Boiler Co., Ltd.
Priority date: 2004-10-13
Filing date: 2005-03-19
Publication date: 2006-04-20
Also published as: KR100570292B1

Abstract

A pipe laying structure in heat exchanging tubes for both a boiler and a hot water supply is provided. The pipe laying structure is formed by subsequently laying a corrosion-resistant auxiliary heat exchanger (5) in which a heat exchange area or a heat transfer area is designed so that both latent hear and combustion heat, or only combustion heat is absorbed while combustion heat generated by combustion of a gas burner (2) located in a combustion chamber (Ia) contact a water recollection tube (6) which recollects hot water so that a heat medium such as water flows against or returning to a flow of discharging the combustion heat in the air via a gas outlet of an exhaust gas duct (3) from the combustion chamber (Ia), a main heat exchanger (4) which is connected with the auxiliary heat exchanger (5) via connection tubes (7a), and is designed to absorb only combustion heat at the lowermost limit within a proportional control range, and a water tube (7) in which one end of the water tube (7) is connected with the main heat exchanger (4) to thereby absorb heat which radiates toward an outer wall of the combustion chamber (Ia) and the other end thereof is connected with a supply tube (8), to thereby form a hot water flow path, and to thus maximize an efficiency, prevent corrosion, and allow an easy assembly.

Description

PIPE LAYING STRUCTURE OF HEAT EXCHANGER FOR BOILER AND HOT WATER SUPPLY

Technical Field

[1] The present invention relates to a pipe laying structure in heat exchanging tubes for use in both a boiler and a hot water supply, and more particularly, to a pipe laying structure in heat exchanging tubes for use in both a boiler and a hot water supply, which can easily design a compact product, and maximize a heat exchanging efficiency occurring in a heat exchanger to enhance a thermal efficiency, by sub¬ sequently altering a pipe laying structure in heat exchanging tubes so that a heat exchange is subsequently performed while a flow direction of a heat medium such as water reverses to that of a combustion heat. Background Art

[2] As is well known, there are a boiler and a hot water supply in combustion equipment having a warming or hot water supply system.

[3] That is, a boiler for use in general homes and buildings is used for heating rooms and supplying hot water, and a hot water supply is used for heating cold water up to a predetermined temperature within a short time and allowing users to use hot water con¬ veniently.

[4] Most of the boilers and hot water supplies burn oil or gas as a fuel in a main burner, then heat water using combustion heat generated in the combustion process, and supply the heated water for users as necessary.

[5] Here, an example of a conventional gas boiler using gas as a fuel is shown in FIG.

1.

[6] That is, as shown in FIG. 1, a gas boiler includes a combustion chamber cover 10 forming an outer cover and an exhaust gas duct 20 provided above the combustion chamber cover 10.

[7] The combustion chamber cover 10 is typically formed of a rectangular box shape, in which a combustion chamber 10a is formed.

[8] Here, a gas burner 22 which performs a combustion operation with a fuel such as

LNG called town gas and generating a flame is provided below the combustion chamber 10a, and a heat exchanger 24 is provided above the combustion chamber 10a.

[9] A water recollection tube 12 into which water is recollected from a warm and hot water tube (not shown) is provided in one side of the combustion chamber cover 10, and a water tube 30 and a hot water supply tube 14 which supplies hot water heated by the heat exchanger 24 again to the warm and hot water tube are also provided in one side of the combustion chamber cover 10.

[10] An exhaust gas outlet 20a through which exhaust gas generated by the gas burner

22 is discharged out is formed in the exhaust gas duct 20 provided above the combustion chamber cover 10.

[11] A connection tube 26 is connected with the heat exchanger 24 and one end of the connection tube 26 is connected with the heat exchanger 24 and the other end thereof is exposedly disposed outward from the combustion chamber cover 10.

[12] The water tube 30 whose both ends respectively communicate with the connection tube 26 and the water recollection tube 12 is provided between the connection tube 26 and the water recollection tube 12 which are exposedly disposed outward from the combustion chamber cover 10.

[13] Here, a water tube 30 is wound by a plurality of turns in the form of a ring along the circumference of the outer wall of the combustion chamber cover 10 in a conventional gas boiler, as shown in FIG. 1.

[14] Thus, since the water tube 30 closely contacts and is wound on the outer wall of the combustion chamber cover 10, the externally radiated heat is absorbed through the water tube 30. As a result, a heat transfer area with respect to the combustion heat of the gas burner 22 increases, to thereby enhance a heat exchange efficiency.

[15] That is, the water tube 30 performs a primary heat exchanging process of heating cold water into hot water by the gas burner 22.

[16] The heat exchanger 24 performs a secondary heat exchanging process of heating cold water into hot water by the gas burner 22 together with the water tube 30.

[17] In other words, in the case of the above-described boiler, when cold water goes into the combustion chamber cover 10 via the water recollection tube 12 at the state where t he gas burner 22 has operated, a primary heat exchanging process is performed due to an increased heat transfer area in the process where the inflow water flows through the water tube 30 provided on the outer wall of the combustion chamber cover 10.

[18] The water which has undergone a primary heat exchanging process goes into the heat exchanger 24 via the connection tube 26, which enables a secondary heat exchanging process to be performed.

[19] Thus, the heat exchanging efficiency can be remarkably enhanced and the temperature of the combustion chamber cover 10 is prevented from rising un¬ necessarily by the water tube 30, in comparison with a conventional gas boiler which performs a heat exchanging process with only a single heat exchanger 24.

[20] Here, the heat exchanger 24 is a device which transfers heat from high temperature fluid to low-temperature fluid by making two kinds of fluid whose temperatures differ from each other flow interposing a heat transfer plate therebetween.

[21] Meanwhile, a thermal efficiency of a conventional gas boiler is about 75%-80%, and the other 20%-25% heat is lost by exhaust gas.

[22] Thus, it is preferable in various respects to recollect heat which is lost by exhaust gas in order to enhance a thermal efficiency.

[23] One of recollecting heat which is lost by exhaust gas is a condensing heat exchanging technology. A recycling heat exchanger called a latent heat exchanger is installed on the path of the exhaust gas, in order to recollect heat by condensing the exhaust gas to thereby minimize a thermal loss.

[24] That is, FIG. 2 schematically shows a condensing gas boiler to which a condensing heat exchanging technology is applied.

[25] As shown in FIG. 2, the condensing gas boiler includes a combustion chamber cover 100 forming an outer case, a burner 200 which burns gas which goes in via a gas valve mixed with air so that combustion heat can be generated in a combustion chamber 110 provided in the combustion chamber cover 100, a combustion heat exchanger 300 which heats water directly by the combustion heat of the burner 200 in the combustion chamber 110, and a latent heat exchanger 400 which is installed above the combustion heat exchanger 300 so that water can be heated by latent heat of exhaust gas through a heat exchanging process with the exhaust gas generated in the combustion chamber 110.

[26] An exhaust gas duct 500 on which an outlet 510 for discharging exhaust gas is provided is installed above the combustion chamber 110, and a condensed water outlet (not shown) which can discharge condensed water is provided in the combustion chamber 110.

[27] Here, in the case of the conventional condensing gas boiler as shown in FIG. 2, a water recollection tube 600 is connected with the latent heat exchanger 400, and a plurality of water tubes 700 wound on the combustion chamber 110 are provided between the latent heat exchanger 400 and the combustion heat exchanger 300. Ac¬ cordingly, the conventional condensing gas boiler has a structure of supplying the combustion heat exchanger 300 with hot water having passed through the latent heat exchanger 400, in which a supply tube 800 which can supply a room warming tube for warming a room with hot water from the combustion heat exchanger 300.

[28] Thus, when the condensing gas boiler operates, water which is recollected after having performed an indoor warming operation via the unshown room warming tube goes into the latent heat exchanger 400 via the water recollection tube 600, and simul¬ taneously receives latent heat from exhaust gas, to thereby enable a primary heat exchanging process to be performed. Accordingly, water which plays a role of warming a room and has gone into the latent heat exchanger 400 is primarily heated. The thus-heated water moves along the water tube 700 surrounding the outer wall of the combustion chamber cover 100 and goes into the combustion heat exchanger 300 at the state where the water has been heated up by heat radiated through the outer wall of the combustion chamber cover 100.

[29] The room warming water is heated by the combustion heat in the combustion heat exchanger 300, and the temperature of the room warming water is increased up to a temperature for which a user requires. Then, the temperature increased water is re- circulated along the room warming tube via the supply tube 800.

[30] Meanwhile, the heat exchanger which is used in the condensing gas boiler should meet several conditions. One of the most important conditions is to prevent the components of the heat exchanger from being corroded due to sulfuric oxide and nitric oxide among the condensed water having acid radical generated at the time of condensing the exhaust gas and the exhaust gas components generated at the time of combustion of fuel gas.

[31] That is, in the case of most of the condensing gas boilers, condensation occurs at the process of recollecting latent heat from exhaust gas in the latent heat exchanger 400, to thereby create condensed water. As described above, since the condensed water contains acid radical which is caused by sulfuric oxide and nitric oxide among the exhaust gas, a corrosion problem may be highly caused in the latent heat exchanger 400.

[32] Thus, in the case of the conventional gas boilers adopting a condensing heat exchanging technology, a heat exchanger should be integrally made of stainless steel which is a corrosion resistant material in order to guarantee a corrosion resistant capability of the heat exchanger component, for the above-described reasons.

[33] However, since the heat exchanger is integrally made of stainless steel which is a corrosion resistant material as described above, size of the heat exchanger becomes large and weight thereof becomes heavy, to resultantly lower compactness of a home- use gas boiler.

[34] In addition, the stainless steel is difficult to work mechanically and requires for a highly skilled technique, to thereby cause difficulty in manufacturing heat exchangers.

[35] In particular, in the case of the conventional condensing gas boiler, the hole size of the heat exchanger becomes large since the combustion heat exchanger 300 is designed according to the maximum output capacity of the boiler.

[36] In the case of the latent heat exchanger 400, latent heat is additionally recollected from the thermal loss of 20%-25% which is lost due to the exhaust gas at the state where the combustion heat exchanger 300 has been designed according to the maximum output capacity of the boiler. That is, since the latent heat exchanger 400 is designed under the purpose of maximizing a thermal efficiency of the gas boiler, the latent heat exchanger 400 is generally fabricated in size relatively smaller than that of the combustion heat exchanger 300. [37] As described above, since the combustion heat exchanger 300 is designed according to the maximum output capacity in the condensing gas boiler, an extra capability which enables a further heat exchanging process to be performed exists although the heat exchanging process has been completely performed in the combustion heat exchanger 300 via the combustion heat due to the burning process of the burner in the case that the gas boiler is actuated while an output capacity is controlled under a proportional control no larger than the maximum output capacity. As a result, the combustion heat exchanger 300 may absorb latent heat from exhaust gas in addition to combustion heat, in order to perform an additional heat exchanging process.

[38] Thus, in this case, the combustion heat exchanger 300 may create condensed water, to accordingly be highly possibly corroded due to the created condensed water.

[39] In order to prevent corrosion due to condensed water in the combustion heat exchanger 300 in designing a pipe laying structure of the conventional heat exchanging tubes, the combustion heat exchanger 300 has been designed to have a pipe laying structure of keeping the dew point or higher as shown in FIG. 2, in which the combustion heat exchanger 300 does not perform a secondary heat exchanging process immediately after the latent heat exchanger 400 has performed a primary heat exchanging process, but performs a final heat exchanging process after the water tube 700 wound on the outer wall of the combustion chamber cover 100 heats room warming water due to an additional heat exchanging process therein. Disclosure of Invention

Technical Problem

[40] Although a corrosion problem due to condensation in the combustion heat exchanger can be solved to a degree, in the case of the pipe laying structure of the con¬ ventional heat exchanging tubes, a pipe laying structure itself has a structure not that tubes are disposed subsequently from top to bottom, but that the water tube 700 is installed from down to top reversely with respect to the combustion heat exchanger 300. As a result, the pipe laying structure becomes long and complicated.

[41] In addition, although it is the most efficient in view of the thermal efficiency that a subsequent heat exchanging process is performed taking a direction of a room warming water flow reverse to a direction where a heat exchanging process is performed by contacting the combustion heat, a thermal efficiency may be lowered relatively in comparison with a pipe laying structure that tubes are disposed from top to bottom according to a heat exchanging principle, since the above-described pipe laying structure of the heat exchanging tubes does not take a structure that tubes are disposed subsequently from top to bottom, but that the water tube 700 is disposed from top to bottom and then from bottom to top. Technical Solution

[42] To solve the above problems, it is an object of the present invention to provide a pipe laying structure in heat exchanging tubes for use in both a boiler and a hot water supply, which can easily design a compact product, and maximize a heat exchanging efficiency occurring in a heat exchanger to enhance a thermal efficiency, by sub¬ sequently altering a pipe laying structure in heat exchanging tubes so that a heat exchange is subsequently performed while a flow direction of a heat medium such as water reverses to that of a combustion heat. Advantageous Effects

[43] As described above, the present invention provides a pipe laying structure in heat exchanging tubes for use in both a boiler and a hot water supply, which can easily design a compact product, and maximize a heat exchanging efficiency occurring in a heat exchanger to enhance a thermal efficiency, by subsequently altering a pipe laying structure in heat exchanging tubes so that a heat exchange is subsequently performed while a flow direction of a heat medium such as water reverses to that of a combustion heat.

[44] The present invention provides merits of simplifying an assembly of the water tube due to the subsequent arrangement of the water tube, and reducing the length of the water tube which more preferably results in achieving an economic cost down and compactness in designing the gas boiler as well.

[45] In particular, in addition to alteration of the pipe laying structure of the heat exchanging pipe according to the present invention, the main heat exchanger which has no worry about corrosion due to condensation is made of copper of a good heat exchanging efficiency and the auxiliary heat exchanger which has a high worry about corrosion due to condensation is made of a corrosion resistant material such as stainless steel or aluminum, or a double structure of copper and aluminum, to thereby enhance a corrosion-resistant property and thus prevent corrosion due to condensed water.

[46] Further, in the present invention, the main heat exchanger can be fabricated to have a relatively smaller output capacity in comparison with the combustion heat exchanger in the conventional condensing gas boiler having an identical output capacity in view of the corrosion, and simultaneously the auxiliary heat exchanger having a detachable function is fabricated to become relatively large in size. As a result, the auxiliary heat exchanger is designed into a structure of meeting the maximum output capacity of the whole boiler.

[47] In addition, in the present invention, a pipe laying structure is designed to perform a heat exchange in sequence of the auxiliary heat exchanger, the main heat exchanger, and the water tube, and the water tube externally exposed from the combustion chamber cover is surrounded by the outer cover. As a result, the heat exchanging efficiency can be enhanced and although a user contacts the water tube carelessly a hazard of burning the skin can be reduced as well. Brief Description of the Drawings

[48] The above and other objects and advantages of the present invention will become more apparent by describing the preferred embodiment thereof in detail with reference to the accompanying drawings in which:

[49] FIG. 1 is a sectional view showing a conventional gas boiler;

[50] FIG. 2 is a sectional view showing a pipe laying structure of heat exchanging tubes in a conventional condensing gas boiler;

[51] FIG. 3 is a sectional view showing a pipe laying structure of heat exchanging tubes in a gas boiler according to the present invention;

[52] FIG. 4 is a side view schematically showing a main heat exchanger according to the present invention; and

[53] FIG. 5 is a side view schematically showing an auxiliary heat exchanger according to the present invention. Best Mode for Carrying Out the Invention

[54] To accomplish the above object of the present invention, according to the present invention, there is provided a pipe laying structure in heat exchanging tubes for use in both a boiler and a hot water supply, including an exhaust gas duct combined with a combustion chamber cover forming a combustion chamber, a gas burner installed in the combustion chamber, a main heat exchanger and an auxiliary heat exchanger which are installed in the combustion chamber to perform a heat exchange, a water tube which is wound and surrounded on the outer wall of the combustion chamber cover, and a water recollection tube and a supply tube which recollects and circulates room warming water, to thereby maximize a thermal efficiency, prevent corrosion and easily assemble a heat exchanger, characterized in that the pipe laying structure is formed by subsequently laying the corrosion-resistant auxiliary heat exchanger in which a heat exchange area or a heat transfer area is designed so that both latent hear and combustion heat, or only combustion is absorbed while combustion heat generated by combustion of the gas burner located in a combustion chamber contact the water rec¬ ollection tube which recollects hot water so that a heat medium such as water flows against or returning to a flow of discharging the combustion heat in the air via a gas outlet of the exhaust gas duct from the combustion chamber, the main heat exchanger which is connected with the auxiliary heat exchanger via connection tubes, and is designed to absorb only combustion heat at the lowermost limit within a proportional control range, and the water tube in which one end of the water tube is connected with the main heat exchanger to thereby absorb heat which radiates toward an outer wall of the combustion chamber and the other end thereof is connected with the supply tube.

[55] Preferably, the main heat exchanger is made of copper and the auxiliary heat exchanger is made of a double structure whose inner portion is made of copper and whose outer portion is made of aluminum, or the main heat exchanger is made of copper and the auxiliary heat exchanger is made of a corrosion resistant material such as stainless steel or aluminum, in order to prevent corrosion due to condensed water.

[56] The auxiliary heat exchanger has an attachable and detachable structure having a plate- shaped form.

[57] An outer cover is installed in the form of surrounding the water tube.

Mode for the Invention

[58] Hereinbelow, a pipe laying structure of heat exchanging tubes in a gas boiler according to the present invention will be in detail described with reference to the ac¬ companying drawings.

[59] FIG. 3 is a sectional view showing a pipe laying structure of heat exchanging tubes in a gas boiler according to the present invention. FIG. 4 is a side view schematically showing a main heat exchanger according to the present invention. FIG. 5 is a side view schematically showing an auxiliary heat exchanger according to the present invention.

[60] As shown in FIG. 3, the pipe laying structure of heat exchanging tubes in a gas boiler according to the present invention has a structure of performing a heat exchange while a heat medium such as water flows down subsequently from the upper portion of a combustion chamber Ia to the lower portion thereof and contacts the combustion heat, with respect to a gas burner 2 located in the lower portion of the combustion chamber Ia in the gas boiler.

[61] That is, a gas boiler having a pipe laying structure according to the present invention includes a combustion chamber cover 1 forming an outer cover and an exhaust gas duct 3 provided above the combustion chamber cover 1.

[62] The combustion chamber cover 1 is typically formed of a rectangular box shape, in which a combustion chamber Ia is formed.

[63] Here, a gas burner 2 which performs a combustion operation with a fuel such as

LNG called town gas and generating a flame is provided below the combustion chamber Ia. A main heat exchanger 4 is provided in the combustion chamber Ia, and an auxiliary heat exchanger 5 is provided above the main heat exchanger 4.

[64] Here, the reason why the heat exchangers mounted in the combustion chamber Ia are not classified into a combustion heat exchanger 300 and a latent heat exchanger 400 as described in the conventional art, but classified into the main heat exchanger 4 and the auxiliary heat exchanger 5 is because a gas boiler to which a pipe laying structure according to the present invention is applied can be applied in both a condensing gas boiler and a non-condensing gas boiler, and the main heat exchanger 4 always performs a function of a combustion heat exchanger which performs a heat exchange with combustion heat but the auxiliary heat exchanger 5 can perform a function of a latent heat exchanger as necessary as well as a function of a combustion heat exchanger according to a change in an output capacity of the gas boiler under a proportional control.

[65] In particular, the main heat exchanger 4 according to the present invention is fabricated in size relatively smaller than that of the combustion heat exchanger 300 in a conventional condensing boiler designed in an identical output range so that a heat exchange is accomplished using only combustion heat, and the auxiliary heat exchanger 5 is fabricated in size relatively larger than that of the latent heat exchanger 400, to thereby meet a balance of the maximum output capacity required in the whole boiler.

[66] In other words, in the case that a boiler operates below the maximum output capacity under a proportional control, the main heat exchanger 4 is designed to perform a heat exchange using only the combustion heat

[67] That is, in the case that a combustion heat exchanger 300 in a condensing gas boiler operates at the state where an output capacity of the boiler is reduced under a pro¬ portional control as described in the conventional art, the combustion heat exchanger 300 does not only perform a heat exchange with combustion heat but also performs a heat exchange using latent heat of exhaust gas at the portion where an extra heat exchange remains. As a result, corrosion may occur frequently. However, since the main heat exchanger 4 according to the present invention performs a heat exchange using only combustion heat even though an output capacity is reduced, condensation due to latent heat does not occur, and thus corrosion due to condensation can be solved fundamentally.

[68] In addition, in the case of a gas boiler and hot water supply according to the present invention, the main heat exchanger 4 is reduced in size and the auxiliary heat exchanger 5 is relatively enlarged in size. Accordingly, in the case that a user wishes to activate the gas boiler and hot water supply in the maximum output capacity, the main heat exchanger 4 performs a heat exchange using the combustion heat, and simul¬ taneously the auxiliary heat exchanger 5 performs a heat exchange using the combustion heat as well as latent heat due to the exhaust gas. As a result, it is possible to activate the gas boiler in accordance with the whole maximum output capacity desired by the user. [69] Here, as shown in FIGs. 4 and 5, the main heat exchanger 4 and the auxiliary heat exchanger 5 include tubular tubes 4a and 5a through which water circulates and which are disposed in a line in parallel with one another in which the tubular tubes 4a and 5a are connected with U-shaped connection tubes 7a, respectively, and a plurality of heat transfer fins 4b and 5b which are extended outwards in the radial direction from a plate surface in order to widen heat transfer areas to be formed on the outer circumferential surface of the tubes 4a and 5a.

[70] Here, since a heat exchange is performed by direct heating due to the combustion heat in the tube 4a of the main heat exchanger 4 as described above, condensed water is not produced. Thus, it is preferable to fabricate the tube 4a with copper having a heat exchanging efficiency.

[71] Meanwhile, since a heat exchange is performed by the combustion heat or the latent heat according to the situation in the tube 5a of the auxiliary heat exchanger 5, condensed water can be easily generated. Accordingly, it is preferable to fabricate the tube 5a with a corrosion resistant material such as stainless steel or aluminum, with the result that the tube 5a possesses a corrosion resistant property. In particular, it is more preferable that the tube 5 a is made of a double structure where the inner portion of the tube 5 a is made of copper having a heat conductive rate and the outer portion thereof is made of aluminum, in view of a corrosion resistant property and a thermal efficiency.

[72] The heat transfer fins 4b and 5b formed on the outer circumferential surfaces of the tubes 4a and 5 a which constitute the main heat exchanger 4 and the auxiliary heat exchanger 5, respectively, play a role of widening a heat transfer area and enhancing a heat exchanging efficiency when a heat exchange is performed by contacting the direct combustion heat and the exhaust gas, respectively. The heat transfer fins 4b and 5b can be formed on the outer circumferential surfaces of the tubes through a well-known conventional brazing weld, more preferably, through a form rolling method.

[73] Further, the auxiliary heat exchanger 5 may not only have a structure of the tube 5 a and the heat transfer fins 5b, but also may have a plate structure. The reason is because the auxiliary heat exchanger 5 has a detachable structure selectively as necessary.

[74] In addition, in the present invention, a plurality of water tubes 7 are connected with the main heat exchanger 4 and wound in a ring form along the circumference of the outer wall of the combustion chamber cover 1.

[75] Thus, the main heat exchanger 4, the auxiliary heat exchanger 5 and the water tubes

7 are connected with each other, in a subsequent direction from above to below, to thereby form a pipe laying structure by which room warming water can circulate.

[76] Here, fitting grooves (not shown) into which the main heat exchanger 4 and the auxiliary heat exchanger 5 can be fitted are provided in both sides of the upper end of the combustion chamber cover 1 and both sides of the lower end of the exhaust gas duct 3.

[77] In particular, the combustion chamber cover 1 is typically formed of a rectangular box shape. However, since the four sides of the combustion chamber cover 1 in the present invention are curved to have a semi-circular shape, the water tube 7 can be easily installed on the outer wall of the combustion chamber cover 1.

[78] In addition, on one side of the combustion chamber cover 1 is provided a water rec¬ ollection tube 6 through which water is recollected from the room warming tube and the hot water tube and which is connected with the auxiliary heat exchanger 5, and on the other side thereof is provided a supply tube 8 which supplies the room warming and hot water tubes with the hot water heated by the main heat exchanger 4 and then re-heated along the water tube 7.

[79] The exhaust gas outlet 3a in the exhaust gas duct 3 plays a role of discharging exhaust gas generated in the combustion process of a burner (not shown). A chimney (not shown) is connected with the exhaust gas duct 3a to discharge the exhaust gas.

[80] In addition, a packing material (not shown) is deposited on the surface where the combustion chamber cover 1 and the exhaust gas duct 3 contact and are assembled with each other, to thereby prevent a corrosion phenomenon at the contacting surface thereof.

[81] Meanwhile, according to the present invention, an outer cover 9 is provided on the outer wall of the combustion chamber cover 1.

[82] That is, the outer cover 9 has a structure of surrounding the whole water tube 7 wound on the outer wall of the combustion chamber cover 1.

[83] The outer cover 9 made of metal can absorb heat radiated from the combustion chamber Ia via the combustion chamber cover 1 to a degree. The outer cover 9 isolates the outer portion of the combustion chamber cover 1 from users to thereby make the users safely use the gas boiler, and to simultaneously prevent the combustion chamber cover 1 and the water tube 7 wound on the outer wall of the combustion chamber cover 1 from being exposed externally to play a role of making the outer countenance look good.

[84] In particular, the high-temperature combustion heat generated from the combustion chamber Ia during operation of the gas boiler, can be discharged externally through the combustion chamber cover 1. Here, the water tube 7 wound on the outer wall of the combustion chamber cover 1 absorbs a certain amount of the high-temperature heat generated from the combustion chamber Ia, to thereby perform a heat exchange and minimize a thermal loss. At the same time, the heat radiated from the outer cover 9 is isolated to thereby prevent a thermal loss much more effectively.

[85] Since the outer cover 9 absorbs a relatively small amount of heat, the surface temperature of the outer cover 9 is remarkably lowered. As a result, although a user contact the outer cover 9 carelessly, a hazard of burning the skin can be reduced.

[86] The function and effect of the gas boiler having the above-described structure will be described below.

[87] The gas burner 2 starts a combustion operation in the combustion chamber Ia and generates combustion heat. At the same time, water necessary for heating rooms and supplying hot water flows into the auxiliary heat exchanger 5 via the water recollection tube 6. Then, a primary heat exchange is performed by combustion heat or latent heat according to an output capacity set in the gas boiler adopting an air proportional control method, to accordingly heat water for warming rooms.

[88] Also, the water undergone the primary heat exchange process moves forward the main heat exchanger 4 connected by the connection tube 7a, to thereby perform a secondary heat exchange by the combustion heat.

[89] Here, in the process of performing the secondary heat exchange process with the combustion heat, a heat transfer area of the main heat exchanger 4 increases because of the tube 4a and a plurality of heat transfer fins 4b formed on the plate surface of the tube 4a to thus remarkably enhance a heat exchanging efficiency.

[90] Then, the room warming water undergone the main heat exchanger 4 flows into the water tube 7 which surrounds the outer wall of the combustion chamber cover 1, and the thus-flown water absorbs the heat radiated externally from the combustion chamber Ia in the process of moving along the inner portion of the water tube 7, to thereby enhance a heat exchanging efficiency at maximum. In this manner, a heat exchange process is performed.

[91] The water undergone a heat exchange while having passed through the auxiliary heat exchanger 5, the main heat exchanger 4 and the water tube 7 in sequence, moves forward the room warming tube and the hot water supply tube via the supply tube 8.

[92] In the present invention as described above, when the thermal medium such as hot water moves from top to bottom of the combustion chamber in sequence, a heat exchange is performed by the combustion heat generated from the gas burner located below the combustion chamber. Accordingly, in view of a well-known heat exchanging theory, a heat exchanging efficiency of the present invention can be relatively enhanced in comparison with a conventional thermal exchanging pipe laying structure. In particular, since the water tube laying structure has a structure of disposing the water tube from top to bottom in sequence, an assembly structure is simple and the water tube length becomes short relatively, to accordingly provide a very advantageous merit in designing a compact gas boiler.

[93] Since the present invention has a structure of surrounding the water tube by use of the outer cover, the heat exchanging efficiency can be enhanced and although a user contacts the water tube carelessly a hazard of burning the skin can be reduced as well. [94] Meanwhile, the present invention has been described with respect to the gas boiler which performs an upstream combustion in which the gas burner 2 is mounted below the combustion chamber Ia. However, the present invention is not necessarily limited thereto.

[95] That is, the technical concept of the present invention can be also applied to the gas boiler which performs a downstream combustion (not shown).

[96] In other words, the present invention provides a pipe laying structure of sub¬ sequently performing a heat exchange in sequence of the auxiliary heat exchanger 5, the main heat exchanger 4, and the water tube 7 in the process of having the combustion heat reversely flowing against the thermal medium, in both types of boilers or hot water supplies which perform an upstream or downstream combustion.

[97] As described above, the present invention has been described with respect to par¬ ticularly preferred embodiment. However, the present invention is not limited to the above embodiment, and it is possible for one who has an ordinary skill in the art to make various modifications and variations, without departing off the spirit of the present invention. Thus, the protective scope of the present invention is not defined within the detailed description thereof but is defined by the claims to be described later and the technical spirit of the present invention.

Claims

[1] A pipe laying structure in heat exchanging tubes for use in both a boiler and a hot water supply, including an exhaust gas duct (3) combined with a combustion chamber cover (1) forming a combustion chamber (Ia), a gas burner (2) installed in the combustion chamber (Ia), a main heat exchanger (4) and an auxiliary heat exchanger (5) which are installed in the combustion chamber (Ia) to perform a heat exchange, a water tube (7) which is wound and surrounded on the outer wall of the combustion chamber cover (1), and a water recollection tube (6) and a supply tube (8) which recollects and circulates room warming water, to thereby maximize a thermal efficiency, prevent corrosion and easily assemble a heat exchanger, characterized in that the pipe laying structure is formed by subsequently laying the corrosion-resistant auxiliary heat exchanger (5) in which a heat exchange area or a heat transfer area is designed so that both latent hear and combustion heat, or only combustion is absorbed while combustion heat generated by combustion of the gas burner (2) located in the combustion chamber (Ia) contact the water recollection tube (6) which recollects hot water so that a heat medium such as water flows against or returning to a flow of discharging the combustion heat in the air via a gas outlet of an exhaust gas duct (3) from the combustion chamber (Ia), the main heat exchanger (4) which is connected with the auxiliary heat exchanger (5) via connection tubes (7a), and is designed to absorb only combustion heat at the lowermost limit within a proportional control range, and the water tube (7) in which one end of the water tube (7) is connected with the main heat exchanger (4) to thereby absorb heat which radiates toward an outer wall of the combustion chamber (Ia) and the other end thereof is connected with the supply tube (8).

[2] The pipe laying structure in heat exchanging tubes according to claim 1, wherein the main heat exchanger (4) comprises a copper tubular tube (4a) through which water circulates therein and a plurality of heat transfer fins (4b) provided on the outer circumferential surface of the tube (4a), and wherein the auxiliary heat exchanger (5) is made of a double structure whose inner portion is made of copper and whose outer portion is made of aluminum, which comprises a tubular tube (5a) through which water circulates therein and a plurality of heat transfer fins (5b) provided on the outer circumferential surface of the tube (5a).

[3] The pipe laying structure in heat exchanging tubes according to claim 1, wherein the main heat exchanger (4) comprises a copper tubular tube (4a) through which water circulates therein and a plurality of heat transfer fins (4b) provided on the outer circumferential surface of the tube (4a), and wherein the auxiliary heat exchanger (5) is made of a corrosion resistant material such as stainless steel or aluminum, which comprises a tubular tube (5a) through which water circulates therein and a plurality of heat transfer fins (5b) provided on the outer circum¬ ferential surface of the tube (5 a).

[4] The pipe laying structure in heat exchanging tubes according to one of claims 1 to 3, wherein an outer cover (9) is installed in the form of surrounding the water tube (7).

[5] The pipe laying structure in heat exchanging tubes according to claim 1, wherein the auxiliary heat exchanger (5) has an attachable and detachable structure having a plate-shaped form.