JP4081116B2 - Heating system - Google Patents

Description

The present invention relates to a heating apparatus using a fluid to be heated such as water as a heat medium.

  This type of heating device includes a heat exchanger that burns fuel such as methane, propane, and butane and absorbs heat from the combustion exhaust gas, heats a fluid to be heated such as water, and uses this as a heat medium as a radiator. To dissipate heat.

With respect to a heating apparatus that uses heat absorption from combustion exhaust, Patent Document 1 discloses a gas combustion apparatus that absorbs sensible heat of combustion exhaust with a main heat exchanger and absorbs latent heat from combustion exhaust with a sub-heat exchanger. It is disclosed that it is used for a machine.
JP-A-7-133958

  By the way, in the heating device, when the temperature of the fluid to be heated at the start of the heating operation is low, or when the heating load is large such as when the temperature is low, condensed water (drain water) is likely to be generated. This may cause corrosion of the heat exchanger. In order to suppress the generation of condensed water, conventionally, a method for suppressing the efficiency of the heat exchanger has been taken.

Then, this invention makes it a subject to provide the heating apparatus which improved heat exchange efficiency by installation of a some heat exchanger.

  In the heating apparatus of the present invention, the first and second heat exchangers (10, 12) are installed in the combustion exhaust (EG) generated by the combustion means (burner 8), and the object to be heated is passed through the first heat exchanger. The fluid (water W) absorbs sensible heat mainly from the combustion exhaust (EG), and through the second heat exchanger, the heated fluid absorbs sensible heat or latent heat from the combustion exhaust to enhance heat exchange efficiency and fuel consumption. The amount is reduced.

The heating device of the present invention is a heating device using a heated fluid to be heated (water W) as a heat medium, combustion means for burning fuel (burner 8), and combustion exhaust (EG) generated from the combustion means. A first heat exchanger (10) for absorbing mainly sensible heat from the combustion exhaust to the heated fluid flowing in a heat receiving pipe (water pipe 88) installed upstream of an exhaust passage (84) through which the exhaust passes, and the exhaust A second heat exchanger (12) that absorbs sensible heat or latent heat from the combustion exhaust gas that has passed through the first heat exchanger to the heated fluid flowing in a heat receiving pipe (water pipe 92) installed on the downstream side of the passage. ), A flow path (pipe lines 30 and 32) for flowing the heat medium heated by the second heat exchanger to the first heat exchanger, and a heat medium heated by the first heat exchanger A first circulation path (pipe lines 50, 52) to be circulated to a first heat radiation means for radiating heat; Branch the flow path, the second circulation path for circulating the second heat radiating means for radiating the heat medium heated by the second heat exchanger (pipe 72, 74), the set temperature of the heated fluid And a control means (control device 120) for controlling the amount of combustion of the combustion means. That is, the sensible heat is mainly recovered from the combustion exhaust by the first heat exchanger, and the sensible heat or latent heat is recovered from the combustion exhaust by the second heat exchanger. The first heat exchanger recovers sensible heat to the extent that no condensed water is generated, and the second heat exchanger recovers sensible heat or latent heat by configuring it to be acid resistant on the assumption that condensed water is generated. With the above heat exchanger, the heat exchange efficiency can be increased.

  In other words, sensible heat that cannot be recovered by the first heat exchanger can be recovered by the second heat exchanger, and the heated fluid heated by such heat recovery is mixed, so that heat recovery from the combustion exhaust is enhanced. be able to. In order to suppress the generation of condensed water, the heat exchange efficiency on the first heat exchanger side has been restricted, but as a result of recovering sensible heat with the second heat exchanger, the first and second heats are recovered. A sensible heat recovery of about 87% can be realized with the exchanger.

  By the way, in the 2nd heat exchanger, since the temperature of the to-be-heated fluid is 55 to 60 degreeC, and is higher than the dew condensation temperature, there is almost no recovery of latent heat and recovery of sensible heat is mainly performed. However, when the temperature of the fluid to be heated is lower than the dew condensation temperature, for example, when the temperature of the fluid to be heated is increased after the start of heating combustion or the outside air temperature at which the heat radiation load becomes excessive is low, the second heat On the exchanger side, latent heat is recovered from the combustion exhaust.

  And since the combustion quantity of the said combustion means is controlled by a control means with the preset temperature of the said to-be-heated fluid, the heating temperature by the side of the 1st heat exchanger can be controlled according to the combustion quantity.

  Moreover, in the heating apparatus of the present invention, the amount of heat absorption is determined by the protruding length (L), thickness, pitch, or number of heat absorbing fins (90) of the heat receiving pipe (water pipe 88) of the first heat exchanger (10). You may adjust. That is, the amount of heat absorption can be adjusted by the protrusion length, thickness, pitch, or number of the heat absorption fins, and the temperature reduction of the heat absorption fins of the heat receiving pipe of the first heat exchanger can be prevented.

  The heating apparatus of the present invention includes a bypass pipe (38) connected in parallel to the heat receiving pipe of the first heat exchanger and allowing a part of the heated fluid to flow, The fluid to be heated is flowed through the heat receiving pipe and heated, and a part thereof is heated by flowing through the heat receiving pipe of the first heat exchanger, and the other part is passed through the first bypass pipe from the first pipe. It is good also as a structure mixed with the said to-be-heated fluid of the exit side of a heat exchanger.

  That is, the combustion exhaust generated by the combustion of fuel flows from the upstream side to the downstream side of the exhaust passage. The heated fluid flowing in the heat receiving pipe of the first heat exchanger upstream of the exhaust passage absorbs sensible heat from the combustion exhaust, and the heated fluid flowing in the heat receiving pipe of the second heat exchanger downstream is latent heat or Absorbs sensible heat. In this case, the heated fluid flowing in the heat receiving pipe of the second heat exchanger may absorb sensible heat, but the heated fluid heated mainly by the absorption of latent heat on the second heat exchanger side 1 flows into the heat receiving tube of the heat exchanger 1 and is heated to a high temperature by absorbing sensible heat.

  In addition, the fluid to be heated divided on the outlet side of the second heat exchanger joins the fluid to be heated on the outlet side of the first heat exchanger through the bypass pipe. That is, the low-temperature heated fluid on the second heat exchanger side is mixed with the high-temperature heated fluid on the outlet side heated by the first heat exchanger, so that the total flow rate of the heated fluid is increased. The ratio of the flow rate of the heated fluid on the heat receiving pipe side of the first heat exchanger and the flow rate on the bypass pipe side can be arbitrarily adjusted. Therefore, the heating temperature of the fluid to be heated on the first heat exchanger side can be raised to the dew point temperature or higher, and the generation of condensed water on the first heat exchanger side can be prevented.

  Further, in the heating device of the present invention, a bypass pipe connected in parallel to the heat receiving pipes of the first heat exchanger and the second heat exchanger connected in series to flow a part of the heated fluid A passage (138) for heating a part of the heated fluid by flowing from the heat receiving tube of the second heat exchanger to the heat receiving tube of the first heat exchanger. May be mixed on the outlet side of the heat receiving pipe of the first heat exchanger from the bypass pipe.

  That is, in this case as well, the fluid to be heated heated by the absorption of latent heat on the second heat exchanger side flows into the heat receiving pipe of the first heat exchanger and is heated to a high temperature by absorption of sensible heat. .

  And the to-be-heated fluid shunted by the inlet side of the 2nd heat exchanger merges with the to-be-heated fluid of the exit side of a 1st heat exchanger through a bypass line. That is, since the fluid to be heated is passed through the bypass line with respect to the first and second heat exchangers connected in series, the pressure is higher than when only the first and second heat exchangers are passed. The loss can be greatly reduced, the flow rate of the fluid to be heated of the heat radiating means can be increased, and the heat radiation load can be increased.

  In the heating device of the present invention, the outer wall member of the second heat exchanger (12) is made of an acid-resistant material, and the condensed water (102) generated on the outer surface of the second heat exchanger. May be provided (recovery hopper 104) to neutralize the recovered condensed water. That is, condensed water is generated in the second heat exchanger due to the recovery of latent heat due to a decrease in outside air temperature, an increase in humidity, a heating demand, that is, a temperature decrease of a heated fluid due to a heating load, and the like. Therefore, by forming the outer wall member of the second heat exchanger with an acid-resistant material such as titanium or stainless steel, it is possible to prevent corrosion due to acidic condensate, deterioration of mechanical strength due to corrosion, and occurrence of damage. The condensed water can be rendered harmless by being recovered and neutralized, and can be disposed of freely.

In the heating device of the present invention, the second heat exchanger or the first heat exchanger and the heat receiving pipe (water pipe 92) of the second heat exchanger are connected to a plurality of pipe lines (94, 96, 98), and the pipe cross-sectional area may be increased. That is, if the heat receiving pipe on the second heat exchanger side is bent, latent heat or sensible heat can be efficiently recovered from the combustion exhaust, but the fluid resistance increases accordingly. Therefore, if this heat receiving pipe has a plurality of pipes arranged in parallel to increase the pipe cross-sectional area, the fluid resistance can be reduced. As a result, it is possible to secure a desired flow rate and flowing water speed, increase heat exchange efficiency, and contribute to suppression of fuel consumption.

  As described above, according to the present invention, the following effects can be obtained.

  a By using the first and second heat exchangers together, sensible heat and latent heat can be recovered from the combustion exhaust, and the heat exchange efficiency can be improved. Corrosion on the first heat exchanger side, strength reduction and damage due to corrosion And can contribute to a reduction in fuel consumption by improving heat recovery efficiency. In addition, since the heating temperature on the first heat exchanger side is controlled by controlling the combustion amount of the combustion means, the heating temperature on the first heat exchanger side can be increased, and the dew condensation on the first heat exchanger side can be reduced. Can be suppressed.

In addition, according to the present invention, since the endothermic amount is adjusted by the protruding length, thickness, pitch, or number of the heat-absorbing fins of the heat-receiving tube of the first heat exchanger, the first control coupled with the heating control of the fluid to be heated. It is possible to prevent the temperature of the heat sink fins of the heat receiving pipe of the heat exchanger from being lowered, and to suppress condensation.

  c According to the present invention, the fluid to be heated heated by the second heat exchanger is mixed with the fluid to be heated heated by the first and second heat exchangers. By increasing the heating temperature, dew condensation on the first heat exchanger side can be suppressed, and corrosion on the first heat exchanger side due to condensed water, strength reduction due to corrosion, and occurrence of damage can be prevented.

  d According to the present invention, since the heated fluid before heating and the heated fluid heated by the first and second heat exchangers are mixed, the pressure loss of the heated fluid can be suppressed, and the heated fluid The flow rate can be secured and the heat radiation load can be increased.

  e In addition, according to the present invention, the outer wall member of the second heat exchanger is made of an acid-resistant material such as titanium or stainless steel, so that damage due to acidic condensed water can be prevented, and the condensed water is Detoxification can be achieved by recovery and neutralization.

In addition, according to the present invention, the fluid resistance is reduced by parallelizing a plurality of pipes in the heat receiving pipe of the second heat exchanger, thereby reducing the fluid resistance. To increase heat exchange efficiency and contribute to the suppression of fuel consumption.

  FIG. 1 shows an embodiment of the heating device of the present invention. In this heating apparatus, water W (including both cold water and hot water) is used as a fluid to be heated as a heat medium, and the apparatus main body 2 that heats the water W is obtained by the apparatus main body 2. Single or plural indoor warm air units 4 that are first heat radiating means using high-temperature water (for example, 80 ° C.) as a heat source, and low-temperature water (for example, 60 ° C.) obtained from the apparatus main body 2 as a heat source One or a plurality of floor heating panel units 6 which are two heat dissipating means are installed.

  The apparatus main body 2 is provided with first and second heat exchangers 10 and 12 using a common burner 8 as a heating means. The heat exchanger 10 is upstream of the combustion exhaust, and the heat exchanger 12 is downstream thereof. It is installed on the side. That is, sensible heat that cannot be recovered by the heat exchanger 10 can be recovered by the heat exchanger 12, and the water W heated by such heat recovery is mixed. Fuel gas G is supplied to the burner 8 through a conduit 14, and a fuel proportional valve 16 and a fuel main valve 18 are provided in the conduit 14. Supply or release of the fuel gas G is performed by opening and closing the fuel source valve 18, and supply adjustment of the fuel gas G is performed by the fuel proportional valve 16. Combustion air is supplied to the burner 8 through an air supply fan 20, and a discharger 22 is provided in the burner 8.

  The expansion tank 24 of the apparatus main body 2 is supplied with water W as a fluid to be heated from a water source or the like through a conduit 26. An open / close valve 28 is provided in the pipe line 26, the open / close valve 28 is opened, a necessary amount of water is supplied to the expansion tank 24, and the entire pipe line is filled with water W.

  Pipe lines 30 and 32 are connected to the expansion tank 24, and a pipe line 35 is connected to the pipe line 30 via a pump 34 that circulates water W in the closed pipe line. Has been. That is, when the pump 34 is driven, the water W from the expansion tank 24 is diverted to the pipes 33 and 35 as indicated by arrows a and b, and the high-temperature water HW obtained by heating by the heat exchanger 10 is indicated by the arrow c. , D as shown by the line 36 side. A temperature sensor 37 that detects the temperature of the high-temperature water HW obtained by the heat exchanger 12 is installed in the pipe line 30. A bypass line 38 is connected between the line 35 and the line 36 on the outlet side of the heat exchanger 10 so that the high-temperature water HW in the line 36 is indicated by an arrow e through the bypass line 38. To the low temperature water LW on the pipe 35 side. A temperature sensor 39 is installed in the pipeline 35, a temperature sensor 41 for detecting the temperature on the outlet side of the heat exchanger 10 is installed in the pipeline 36, and a water W pipe from the pipeline 35 is installed in the bypass pipeline 38. A check valve 40 is provided as means for preventing backflow to the path 36 side. Further, a pipe 44 as a bypass pipe is connected between the pipe 36 and the pipe 42 connected to the inlet side of the heat exchanger 12, and the hot water HW is passed through this pipe 44 with an arrow f. As shown in FIG. The pipe 44 is provided with a heat exchanger 48 for hot water supply or recuperation that absorbs heat from the high-temperature water HW together with the on-off valve 46. The heat exchanger 48 for replenishment with the high-temperature water HW by opening the on-off valve 46. The hot water in the bathtub flowing through 48 can be heated.

  The indoor hot air unit 4 is connected between the pipes 36 and 42 via the pipes 50 and 52, and a heat exchanger 56 and an opening / closing valve are provided in the casing 54 of the indoor hot air unit 4. A heat radiating fan 62 and a temperature sensor 64 that are rotated by a fan motor 60 together with 58 are installed. That is, after the high-temperature water HW from the pipe 36 is supplied to the heat exchanger 56 through the pipe 50, it flows from the pipe 52 to the pipe 42 side and circulates to the heat exchanger 12 side as indicated by an arrow g. To do. When the heat dissipating fan 62 is rotated, air 68 is introduced into the housing 54 from the air inlet 66, and the air 68 is heated by heat dissipated by the heat exchanger 56. As a result, the hot air 70 is discharged into the room. Since the on-off valve 58 is opened to allow the high-temperature water HW to flow through the heat exchanger 56, and the amount of heat radiation can be controlled by changing the number of rotations of the heat radiation fan 62, the room temperature can be adjusted.

  In addition, a heat radiating pipe 78 of the floor heating panel unit 6 is connected between the pipe lines 35 and 42 via pipe lines 72 and 74 and an on-off valve 76. That is, the low-temperature water LW is supplied from the pipe 72 to the heat radiating pipe 78 through the pipe 72, and the low-temperature water LW flows into the heat radiating pipe 78 of the floor heating panel unit 6 according to the opening degree of the on-off valve 76. As shown by, it joins and circulates to the pipe line 42 side. As a result, the floor is warmed by heat radiation by the heat radiating pipe 78. In this case, the heat radiation amount can be adjusted by opening and closing the on-off valve 76, and the floor temperature can be adjusted.

  Next, FIG. 2 shows a configuration of the apparatus main body 2 on the heat exchangers 10 and 12 side. A body 80 is installed in the apparatus main body 2, and a combustion chamber 82 is formed inside the body 80. The combustion chamber 82 is provided with a burner 8 as combustion means, and an air supply fan 20 that takes in combustion air as an air supply portion is provided below the burner 8. An exhaust passage 84 is formed so as to extend the body portion 80, and the exhaust passage 84 is opened to the exhaust port 86. Therefore, the combustion exhaust EG generated by the combustion of the burner 8 using the supply air E and the combustion gas G from the supply air fan 20 is discharged from the exhaust port 86 to the outside air via the exhaust passage 84.

  The combustion chamber 82 is provided with the first heat exchanger 10 on the upstream side of the exhaust passage 84 and the second heat exchanger 12 on the downstream side thereof. The heat exchanger 10 is installed by winding a water pipe 88 as a heat receiving pipe around the outer wall of the combustion chamber 82, and a plurality of heat absorbing fins 90 are formed around the water pipe 88. Further, the heat exchanger 12 is provided with a water pipe 92 as a heat receiving pipe bent in the exhaust passage 84. In this embodiment, the pipe cross-sectional area is increased by providing a plurality of pipes 94, 96, and 98. An enlarged water pipe 92 is formed, and an infinite number of endothermic fins 100 are provided around it. Further, the heat absorption efficiency may be improved by making the conduits 94, 96, and 98 into wavy tubular bodies such as flexible pipes. The heat exchanger 12 installed on the downstream side of the combustion exhaust EG causes the water W flowing through the water pipe 92 to absorb mainly sensible heat from the combustion exhaust EG. In addition, latent heat can also be recovered when the hot water temperature at the start of combustion rises or when the temperature of hot water flowing through the pipe line 42 is lower than the dew condensation temperature of the heat exchanger 12 as the temperature decreases or the heating load increases. it can. In order to protect the heat exchanger 12 from the strongly acidic liquid generated at this time, the water pipe 92 and the heat-absorbing fins 100 of the heat exchanger 12 are formed of an acid-resistant material such as stainless steel or titanium.

  A recovery hopper 104 as a recovery means for receiving the condensed water 102 is provided below the water pipe 92 of the heat exchanger 12, and the condensed water 102 recovered in the recovery hopper 104 is neutralized through the pipe 106. To 108. The neutralizer 108 is filled with a neutralizing agent 110 such as alkaline to neutralize the acidic condensed water 102. The neutralized condensed water 102 is discharged outside through the pipe 112.

  Next, FIG. 3 shows an embodiment of the hot water supply control unit. In this hot water supply control unit, a control device 120 is installed as a control means constituted by a microcomputer or the like. The control device 120 includes a CPU as a calculation means, a ROM and a RAM as storage means, and the ROM includes Detection data and the like are stored in a program for controlling hot water supply and the RAM.

  A set temperature is applied from the temperature setter 122 to the control device 120, and detection outputs from various temperature sensors 37, 39, 41 and the like are taken in. The control outputs are the fuel proportional valve 16, the fuel main valve 18, and the fan motor 60. The fan motor 124 of the air supply fan 20 is added.

Next, the operation will be described. As shown in FIG. 4, when the fuel gas G is burned by the burner 8, combustion exhaust EG is generated. If the heat quantity of the combustion exhaust EG is H ₀ , the exchange heat quantity on the heat exchanger 10 side is H ₁ , the water temperature rise is Δt ₁ , the exchange heat quantity on the heat exchanger 12 side is H ₂ , and the water temperature rise is Δt ₂ , combustion The amount of heat H ₁ is absorbed on the heat exchanger 10 side from the heat amount H _{0 of the} exhaust EG, and the combustion exhaust EG of the amount of heat (H ₀ -H ₁ ) flows on the heat exchanger 12 side, and the combustion that has passed through the heat exchanger 12 The amount of heat of the exhaust EG is (H ₀ -H ₁ -H ₂ ).

Therefore, assuming a state in which the bypass line 38 side is closed, when water supply W at the water temperature t ₀ is performed on the heat exchanger 12, the water temperature t on the outlet side of the heat exchanger 12, that is, the inlet side of the heat exchanger 10. ₁ is heated to (t ₀ + Δt ₂ ), this hot water flows to the heat exchanger 10 side, and the temperature t ₂ of the high-temperature water HW becomes (t ₀ + Δt ₂ + Δt ₁ ).

  In this case, if the temperature of the combustion exhaust EG obtained by the burner 8 is 1500 ° C., the temperature of the combustion exhaust EG that has passed through the heat exchanger 10 decreases to 220 ° C., and further the combustion exhaust EG that has passed through the heat exchanger 12. The temperature will be reduced to 120 ° C.

At this time, the ratio (H ₁ / H ₀ ) of the exchange heat quantity H _{1 to} the heat quantity H ₀ is H ₁ / H ₀ = 80%, and the ratio of the exchange heat quantity H _{2 to} the heat quantity H ₀ (H ₂ / H ₀ ) is H ₂ / H ₀ = 5%, (H ₁ + H ₂ ) / H ₀ = 85%, Δt ₂ : Δt ₁ = 5: 80, and H ₁ : H ₂ = Δt ₁ : Δt ₂ .

  By the way, about heating control, in the case of heating only of the high temperature water HW, in the case of heating only of the low temperature water LW, there is a case of heating using both. When heating only the high-temperature water HW, that is, when performing an operation of supplying hot water to a device that releases the amount of heat of high-temperature hot water such as a fan convector, the fuel proportional valve is set so that the temperature detected by the temperature sensor 41 is 80 ° C. 16 is adjusted. Further, when only the low-temperature water LW is heated, that is, when the floor heating panel unit 6 is used, the fuel proportional valve 16 is operated so that the temperature detected by the temperature sensor 39 is 60 ° C., and the tapping temperature is adjusted. .

  In the heating using both the high-temperature water HW and the low-temperature water LW, the high-temperature water HW and the low-temperature water LW are merged using the bypass line 38, and the low-temperature water LW having a hot water temperature lower than the line 36 is obtained from the line 35. It is done. The amount of mixed water in the pipe 35 and the bypass pipe 38 cannot be adjusted, but this is because the amount of heat released due to fluctuations in the pump flow rate due to the number of loads on the heater, securing the amount of flowing water associated with the heating load, and fluctuations in the number of loads on the heater. Since the temperature of the hot water to be refluxed fluctuates due to fluctuations in temperature, temperature control by mixing cannot be performed. The temperature of the low-temperature water LW is lower than that of the high-temperature water HW, and the temperature of the high-temperature water HW on the pipe 36 side is adjusted to a maximum temperature of 80 ° C. using the temperature detected by the temperature sensor 41 to adjust the temperature of the low-temperature water LW. To do.

  As shown in FIG. 5 (a), the sensible heat in the combustion exhaust can be recovered to a heat exchange efficiency of 90%, and the latent heat is recovered when the heat exchange efficiency exceeds 90%. Therefore, when a heat exchanger having a heat exchange efficiency of 90% is used for the heat exchanger 10 as shown in FIG. 5 (b), all of the sensible heat can be recovered theoretically. In this case, the hot water temperature rises from the start of combustion until the hot water at a temperature exceeding the dew point temperature of the heat exchanger 12 is returned to the pipe line 42 until the latent heat is 0 to 0%. About 5% is recovered, and at that time, a part of the heat exchanger 10 is lowered to a dew point temperature (40 to 50 ° C.) or less due to endothermic heat absorption. As a result, condensed water is generated on the surface of the heat exchanger 10, and this condensed water is acidic, causing corrosion. For this reason, as shown in FIG. 5 (c), the maximum heat exchange efficiency (for example, 80% heat exchange efficiency at the time of the maximum combustion) that can recover only the sensible heat on the heat exchanger 10 side is set. The heat exchanger 12 absorbs the amount of heat in the combustion exhaust that cannot be recovered on the side of the vessel 10 to achieve high efficiency.

By the way, since the temperature of the combustion exhaust gas EG that has passed through the heat exchanger 10 is reduced to about 220 ° C., a part of the heat-absorbing fins 90 of the water pipe 88 of the heat exchanger 10 is lowered, that is, 40 ° C. to 50 ° C. There is a risk of producing condensed water by cooling to the following dew point temperature. This also occurs due to the temperature t ₀ of the water W. In order to prevent such a decrease in temperature below the dew point temperature, it is necessary to increase the temperature of the heat sink fin 90 above the dew point temperature by increasing the temperature of the hot water passing through the water pipe 88. As a countermeasure on the heat exchanger 10 side, the amount of heat absorbed from the heat sink fin 90 to the water pipe 88 is adjusted so that the heat exchange surface of the heat sink fin 90 becomes higher than the dew point temperature. That is, as shown in FIG. 6, the endothermic amount of the endothermic fin 90 can be realized by adjusting the distance L between the endothermic fin 90 and the water pipe 88, the thickness of the endothermic fin 90, the pitch of the fins, or the number of fins. As a result, condensation on the exhaust side of the heat exchanger 10, that is, the downstream side, that is, condensate water can be suppressed. In this case, when the water W is heated by receiving the upstream heat quantity H ₀ , the water temperature t _P rises to (t _P + Δt _1a ) below the water pipe 88, and the rise temperature Δt _1a is the heat quantity H Corresponds to _1a . Therefore, hot water having a water temperature (t _P + Δt ₁ ) is obtained from the heat exchanger 10 by receiving heat (H ₀ −H _1a ) on the upper side of the water pipe 88, that is, on the downstream side.

In this case, if the ratio of the amount of water on the bypass conduit 38 side and the amount of water on the heat exchanger 10 side is 1: 1, the water W that has passed through the water pipe 92 of the heat exchanger 12 absorbs the amount of heat H ₂ and The temperature can be raised by Δt ₂ . FIG. 7 shows an equivalent circuit in this case, and this hot water is diverted, for example, 1: 1 to the bypass conduit 38 and the heat exchanger 10 side, and the heat quantity H ₁ is absorbed on the heat exchanger 10 side. The hot water is further heated by Δt ₁ . In this case, the temperature ta of the hot water on the bypass line 38 side is
ta = (t ₀ + Δt ₂ ) (1)
The temperature tb of the hot water on the heat exchanger 10 side is
tb = (t ₀ + Δt ₂ + Δt ₁ ) (2)
It is. Since the mixing ratio is 1: 1, the temperature tc of the hot water HW in the pipeline 36 is
tc = (t ₀ + Δt ₂ + t ₀ + Δt ₂ + Δt ₁ ) / 2
= T ₀ + Δt ₂ + Δt _1/2 (3)
It is. Here, when there is no bypass conduit 38, the temperature td of the high-temperature water HW in the conduit 36 is
td = t ₀ + Δt ₂ + Δt _1b (4)
It becomes. Here, if it is assumed that the temperatures tc and td are the same, the amount of water on the heat exchanger 10 side is double that when the bypass conduit 38 is present when there is no bypass conduit 38, so Δt ₁ : From the relationship of Δt _1b = 2: 1,
Δt _1b = Δt _1/2 (5)
It becomes. As a result, when the hot water is diverted through the bypass pipe 38 and merged in the pipe 36, the hot water temperature of the water pipe 88 of the heat exchanger 10 can be increased, and condensation on the heat exchanger 10 side can be prevented. .

  Further, an increase in heat exchange efficiency due to an increase in the amount of water passing through the heat exchanger 10 can be expected, heat recovery efficiency is high, and fuel consumption can be reduced.

  By the way, in this heat exchange device and hot water supply device, the relationship between the bypass pipe line 38 and the heat recovery rate of the heat exchanger 10, that is, the influence of the diversion by the bypass pipe line 38 on the heat recovery rate of the heat exchanger 10 is seen. As described above, the heat exchanger 10 is heated to about 1500 ° C., while the water temperature is several tens of degrees Celsius, so that when the bypass pipe 38 is not provided, the heat exchange amount of the heat exchanger 10 increases. The temperature difference is negligible when viewed from the heating temperature 1500 ° C. of the heat exchanger 10, and the diversion by the bypass pipe 38 does not affect the heat absorption rate of the heat exchanger 10.

  Further, when the relationship between the bypass pipe 38 and the heat exchange efficiency of the heat exchanger 10, that is, the influence of the shunt flow by the bypass pipe 38 on the heat exchange efficiency of the heat exchanger 10, the bypass pipe 38 is provided. The diversion means that the temperature difference is slightly reduced before and after heating by the heat exchanger 10, and as a result, the heat transfer coefficient decreases due to the decrease in the pipe flow velocity of the water pipe 88 of the heat exchanger 10. The heat exchange efficiency of the exchanger 10 slightly decreases. However, when there is no bypass line 38, the heat exchange efficiency of the heat exchanger 10 is 80%, and when the bypass line 38 is attached, the heat exchange efficiency of the heat exchanger 10 is about 78-79%. Prevention of condensation due to the installation of the pipe line 38 is advantageous for dredging.

  Further, looking at the relationship between the amount of high-temperature water HW and the heating temperature, the amount of water in the heat exchanger 10 is suppressed by making the amount of water the same, that is, the heat exchanger 10 side and the bypass line without changing the total flow rate. If the distribution ratio with respect to the side 38 is changed and the amount of water in the heat exchanger 10 is reduced, the heat exchange efficiency of the heat exchanger 10 is lowered according to the flow rate, and the heating temperature of the heat exchanger 10 is increased. Become. Further, when the amount of the high-temperature water HW is made the same and the amount of water on the heat exchanger 10 side is increased, the heating temperature on the heat exchanger 10 side is lowered.

  In addition, the heat exchange efficiency and heat recovery rate of the heat exchanger 10 itself can be adjusted by the protruding length L and thickness of the heat sink fin 90 on the heat exchanger 10 side. There is a range, for example, a dew point temperature or higher and an oxidation temperature (250 ° C.) or lower is preferable. As for the thickness of the heat sink fin 90, when copper is used as the material, the durable element is stronger than the heat transfer element. It is necessary to increase and decrease the pitch.

By the way, the heat exchangers 10 and 12 are connected in series. When the fluid resistance on the water pipe 88 side is R ₁ and each fluid resistance on the water pipe 92 side is R ₂ , the water flow path is an equivalent circuit shown in FIG. Can be represented. When the parallel number of the pipes 94 to 98 on the water pipe 92 side is n, the total water flow resistance R is
R = R ₁ + R ₂ / n (6)
Thus, the parallel flow of the pipes 94 to 98 on the water pipe 92 side makes it possible to significantly reduce the total water flow resistance R. Therefore, it is possible to increase the heating load and contribute to the improvement of thermal efficiency.

  The amount of the high-temperature water HW obtained from the pipe 36 can be controlled by the on-off valve 58, and the flow rate on the heat exchanger 10 side can be controlled. If a large flow rate is set on the heat exchanger 10 side, the temperature of the hot water in the water pipe 88 of the heat exchanger 10 can be increased, and condensate can be prevented from being generated on the heat exchanger 10 side.

  Further, the temperature of the high-temperature water HW obtained from the pipe 36 is detected by the temperature sensor 41, and the high-temperature water HW and the low-temperature water LW having desired set temperatures are obtained by adjusting the combustion amount of the burner 8 based on the detected temperature. . In this case as well, the flow rate on the heat exchanger 10 side can be controlled according to the set temperature, and the dew condensation on the heat exchanger 10 side can be reduced by increasing the hot water temperature of the water pipe 88 of the heat exchanger 10. Can be prevented.

  Next, another embodiment of the present invention shown in FIG. 9 will be described. The heat exchanger 10 is connected between the pipe line 33 and the pipe line 36 on the outlet side of the pump 34, and the pipe line 36 is branched. A conduit 35 is provided. When the pump 34 is driven, all of the water W flows to the heat exchanger 10 side and is heated, and the high-temperature water HW flows into the pipeline 36 as indicated by the arrow c, and the pipeline 35 as indicated by the arrow i. Shunt to the side. A bypass conduit 138 is connected between the conduit 35 and the conduit 42, and a check valve 40 is provided in the bypass conduit 138 as a backflow prevention means. As shown by the arrow j through the bypass pipe 138, the recovered water W joins the pipe 35 side. That is, in this embodiment, after the water W is diverted at a ratio of 1: 1, for example, at the inlet side of the heat exchanger 12, the water W is supplied to the low-temperature water LW in the pipe line 35 on the outlet side of the heat exchanger 10. To be mixed.

FIG. 10 shows an equivalent circuit in this case. In this case, by providing the bypass conduit 138 in the heat exchangers 10 and 12 connected in series, the flow rate of the pump 34 can be secured by suppressing the pressure loss, which contributes to an increase in load that can be connected. it can. That is, the temperature of the feed water on the bypass line 138 side is t ₀ , and the temperature te of hot water heated by the heat exchangers 10 and 12 is
te = t ₀ + Δt ₂ + Δt ₁ (7)
It is. Since the mixing ratio is 1: 1, the temperature tf of the low-temperature water LW obtained from the pipe 35 is
tf = (t ₀ + t ₀ + Δt ₂ + Δt ₁ ) / 2
= T ₀ + (Δt ₂ + Δt ₁ ) / 2
= T ₀ + ΔT (8)
It becomes. Here, the temperature tg when there is no bypass conduit 138 is the same as the temperature td shown in the equation (4),
tg = t ₀ + Δt ₂ + Δt _{1 b} = t ₀ + ΔT _b (9)
Since ΔT: ΔT _b = 2: 1, the temperature of the hot water in the water pipe 88 of the heat exchanger 10 is increased by diverting the water W through the bypass pipe 138 and joining the water W through the pipe 35. Can do.

  In this case as well, an increase in heat exchange efficiency due to an increase in the amount of water passing through the heat exchanger 10 can be expected, heat recovery efficiency is high, and fuel consumption can be reduced.

As described above, the most preferable embodiment of the present invention has been described. However, the present invention is not limited to the above description, and is described in the claims or disclosed in the specification. It goes without saying that various modifications and changes can be made by those skilled in the art based on the gist, and such modifications and changes are included in the scope of the present invention.

The present invention relates to a heating apparatus using a heated fluid such as water as a heat medium, recovers sensible heat and latent heat from combustion exhaust, can improve heat exchange efficiency, and heat exchanger corrosion, strength reduction due to corrosion This is useful because it can prevent damage and damage, and can reduce fuel consumption and control condensation by improving heat recovery efficiency.

It is a piping diagram showing one embodiment of the heating device of the present invention. It is a piping diagram which shows the structure by the side of the heat exchanger of a heating apparatus. It is a block diagram which shows the structure of a control part. It is a figure which shows the amount of heat generated by the burner and heat exchange by the first and second heat exchangers. It is a figure which shows the heat exchange and heat efficiency of a heat exchanger. It is a figure which shows the dew condensation on the 1st heat exchanger side, and its prevention. It is a figure which shows warm water mixing by a bypass line. It is a circuit diagram which shows the equivalent circuit by the fluid resistance in the 1st and 2nd heat exchanger. It is a piping diagram showing other embodiments of a bypass pipeline. It is a figure which shows warm water mixing by a bypass line.

Explanation of symbols

G Fuel gas W Water HW High temperature water LW Low temperature water EG Combustion exhaust 4 Indoor warm air unit 6 Floor heating panel unit 8 Burner (combustion means)
DESCRIPTION OF SYMBOLS 10 1st heat exchanger 12 2nd heat exchanger 38,138 Bypass pipe line 41 Temperature sensor (temperature detection means)
84 Exhaust passage 88, 92 Water pipe (heat receiving pipe)
90 Endothermic fins 94, 96, 98 Pipe line 102 Condensed water 104 Recovery hopper 120 Control device (control means)

Claims (6)

A heating device using a heated fluid to be heated as a heat medium,
Combustion means for burning fuel;
A first heat exchanger that absorbs mainly sensible heat from the combustion exhaust to the heated fluid flowing in a heat receiving pipe installed upstream of an exhaust passage through which combustion exhaust generated from the combustion means passes;
A second heat exchanger that absorbs sensible heat or latent heat from the combustion exhaust gas that has passed through the first heat exchanger to the heated fluid flowing in a heat receiving pipe installed downstream of the exhaust passage;
A flow path for flowing the heat medium heated by the second heat exchanger to the first heat exchanger;
A first circulation path that circulates through a first heat radiating means that radiates heat of the heat medium heated by the first heat exchanger;
A second circulation path for branching the flow path to circulate to a second heat radiating means for radiating the heat medium heated by the second heat exchanger;
Control means for controlling the combustion amount of the combustion means according to a set temperature of the heated fluid;
A heating device comprising:   The heating apparatus according to claim 1, wherein the heat absorption amount is adjusted by a protruding length, thickness, pitch, or number of heat absorbing fins of the heat receiving pipe of the first heat exchanger.   A bypass pipe connected in parallel to the heat receiving pipe of the first heat exchanger and allowing a part of the heated fluid to flow, and flowing the heated fluid through the heat receiving pipe of the second heat exchanger; And heating a part thereof to the heat receiving pipe of the first heat exchanger and heating the other part from the bypass pipe on the outlet side of the first heat exchanger. The heating apparatus according to claim 1, wherein the heating apparatus is mixed with a fluid.   A bypass pipe connected in parallel to the heat receiving pipes of the first heat exchanger and the second heat exchanger connected in series to flow a part of the heated fluid; A part is heated by flowing from the heat receiving pipe of the second heat exchanger to the heat receiving pipe of the first heat exchanger, and another part of the heated fluid is supplied from the bypass pipe to the first The heating apparatus according to claim 1, wherein mixing is performed on the outlet side of the heat receiving pipe of the heat exchanger.   The outer wall member of the second heat exchanger is made of an acid-resistant material, and includes means for recovering condensed water generated on the outer surface of the second heat exchanger, and neutralizes the recovered condensed water The heating device according to claim 1, wherein   The heat receiving pipe of the second heat exchanger or the first heat exchanger and the second heat exchanger is constituted by a plurality of pipes, and the pipe cross-sectional area is increased. Item 2. The heating device according to Item 1.

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