JP2013108711A - Heat medium boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat medium boiler which performs pre-heating at a maximum pre-heating temperature according to the type of heat so that an NOconcentration in an exhaust gas does not exceed a regulation value while maintaining high efficiency of a heat medium boiler.SOLUTION: The heat medium boiler includes: a recuperator 11 which pre-heats combustion air by performing heat-exchange between the exhaust gas emitted from the boiler for combusting gas fuel and the combustion air set tt a burner 2 using a blower 8; and a heat transfer area adjusting means 14 for adjusting a heat transfer are of the recuperator 11 according to the type of fuel.

Description

  The present invention relates to a heat medium boiler including a recuperator that preheats combustion air by exchanging heat between exhaust gas discharged from a boiler that burns gaseous fuel and combustion air that is sent to a burner using a blower.

  The heat-medium boiler is widely used as one that heats the heat-medium oil to a high temperature (250 ° C. to 300 ° C.) and indirectly uses the heat-medium oil as a heat source. Since the temperature of the heated heat transfer oil is as high as 250 ° C. to 300 ° C., the exhaust gas temperature is 300 ° C. to 350 ° C., and the energy taken away is large. For this reason, for example, compared with the boiler efficiency of a small once-through boiler being 92% or more, the boiler efficiency of a heat-medium boiler is about 80%, and thermal efficiency is bad. In order to increase the efficiency of the heat medium boiler, preheating the combustion air is a common method. As a method for preheating the combustion air, heat exchange is performed between the exhaust gas discharged from the boiler and the combustion air. The method is used (for example, refer patent document 1).

  However, increasing the preheating temperature of the combustion air also increases the nitrogen oxide concentration (hereinafter referred to as NOx concentration) in the exhaust gas, which may exceed 150 ppm regulated by the Air Pollution Control Law. is there. In order not to exceed the regulation value while maintaining the high efficiency of the heat medium boiler, it is necessary to obtain the upper limit of the preheating temperature and preheat the combustion air within a range not exceeding the preheating upper limit temperature. Since this preheating upper limit temperature changes with the calorific value of a fuel, it is necessary to determine for every fuel types, such as city gas (13A) and liquefied petroleum gas (LPG), for example.

Conventionally, in order to suppress a large release of NOx in exhaust gas due to preheating of combustion air, a bypass duct that does not pass through the heat exchanger is provided in one of the air duct and the exhaust gas duct, and the bypass duct is provided in the duct. There is an exhaust heat recovery system provided with a switching damper that controls the amount of fluid flowing (see, for example, Patent Document 2).
According to the exhaust heat recovery system described in Patent Document 2, the switching damper provided in the duct is switched to control the amount of fluid flowing through the bypass duct, and the amount of NOx in the exhaust gas is suppressed to a predetermined amount or less. Can do.

Japanese Patent Laid-Open No. 7-243605 JP 58-158416 A

  However, as described above, the preheating upper limit temperature provided in order not to exceed the regulation value of the Air Pollution Control Law differs depending on the fuel type, so that the regulation value is not exceeded while maintaining high efficiency of the heat medium boiler. In order to do so, it is desirable to preheat at a preheating upper limit temperature corresponding to the fuel type, but the exhaust heat recovery system described in Patent Document 2 preheats at a preheating upper limit temperature corresponding to the fuel type. There is no description, so depending on the fuel type, preheating at a temperature that does not reach the preheating upper limit temperature cannot be achieved, the boiler efficiency cannot be increased, and preheating is performed at a temperature exceeding the preheating upper limit temperature. There is a problem that the concentration may exceed the regulation value.

  An object of the present invention is to provide a heat medium boiler that is preheated at a preheating upper limit temperature corresponding to the fuel type, so that the NOx concentration in the exhaust gas does not exceed the regulation value while maintaining high efficiency of the heat medium boiler. It is in.

  In order to achieve the above object, the invention described in claim 1 is configured to exchange heat between exhaust gas discharged from a boiler that burns gaseous fuel and combustion air that is sent to a burner using a blower. A heating medium boiler including a recuperator that preheats, characterized by comprising heat transfer area adjusting means for adjusting the heat transfer area of the recuperator in accordance with the fuel type.

  According to the first aspect of the present invention, the preheat temperature of the combustion air can be adjusted by adjusting the heat transfer area of the recuperator to be larger or smaller by the heat transfer area adjusting means. By adjusting the area, it is possible to preheat at a preheating upper limit temperature corresponding to the fuel type, and to keep the efficiency of the heat medium boiler high, so that the NOx concentration in the exhaust gas does not exceed the regulation value. it can.

  The invention described in claim 2 is characterized in that the heat transfer area adjusting means described in claim 1 is provided in an exhaust gas inlet of a recuperator.

  According to the second aspect of the present invention, the heat exchange area between the exhaust gas flowing through the recuperator and the combustion air is adjusted by adjusting the cross-sectional area of the exhaust gas inlet passage of the recuperator, and the preheating temperature of the combustion air is adjusted. Therefore, the combustion air can be preheated at the preheating upper limit temperature corresponding to the fuel type, and the NOx concentration in the exhaust gas does not exceed the regulation value while maintaining high efficiency of the heat medium boiler. Can be

  According to a third aspect of the present invention, the heat transfer area adjusting means according to the second aspect includes a flow path adjusting partition plate that adjusts an opening amount of an exhaust gas inlet of the recuperator by driving a motor, and a combustion air supply A temperature sensor for detecting the temperature of combustion air on the outlet side of the recuperator in the line, storing the preheating upper limit temperature of combustion air according to the fuel type, and depending on the fuel type according to the temperature detected by the temperature sensor And a control unit that controls the motor so that the temperature of the combustion air does not exceed the preheating upper limit temperature and adjusts the opening amount of the exhaust gas inlet of the recuperator.

  According to the third aspect of the present invention, the temperature of the combustion air on the outlet side of the recuperator detected by the temperature sensor is input, and the temperature of the combustion air on the outlet side of the recuperator is a preheating upper limit temperature corresponding to the fuel type. If it is lower than that, the motor is driven and the flow path adjusting partition plate is adjusted so that the opening amount of the exhaust gas inlet of the recuperator is increased to increase the heat transfer area of the recuperator, thereby increasing the temperature of the combustion air. When the temperature of the combustion air on the outlet side of the recuperator exceeds the preheating upper limit temperature, the motor is driven so that the opening amount of the exhaust gas inlet of the recuperator is reduced by the flow path adjusting partition plate. It is possible to reduce the heat transfer area of the recuperator to suppress the rise in the temperature of the combustion air so that the preheating upper limit temperature is not exceeded. That. Therefore, it is possible to always perform preheating at the preheating upper limit temperature corresponding to the fuel type, and it is possible to prevent the NOx concentration in the exhaust gas from exceeding the regulation value while maintaining high efficiency of the heat medium boiler.

  The invention according to claim 4 is characterized in that the heat transfer area adjusting means according to claim 1 is provided at a combustion air inlet of a recuperator.

  According to the invention described in claim 4, by adjusting the combustion air inlet channel cross-sectional area of the recuperator, the heat exchange area between the exhaust gas flowing through the recuperator and the combustion air is adjusted, and the combustion air Since the preheating temperature can be adjusted, the combustion air can be preheated at the preheating upper limit temperature corresponding to the fuel type by adjusting the combustion air inlet channel cross-sectional area of the recuperator, and the efficiency of the heat medium boiler The NOx concentration in the exhaust gas can be prevented from exceeding the regulation value while maintaining high

  According to a fifth aspect of the present invention, the heat transfer area adjusting means according to the fourth aspect includes a flow path adjusting partition plate for adjusting an opening amount of a combustion air inlet of the recuperator by driving a motor, and combustion air. A temperature sensor that detects the temperature of the combustion air on the outlet side of the recuperator in the supply line, stores the preheating upper limit temperature of the combustion air according to the fuel type, and depends on the fuel type according to the temperature detected by the temperature sensor And a controller that controls the motor so that the temperature of the combustion air does not exceed the preheating upper limit temperature and adjusts the opening amount of the combustion air inlet of the recuperator.

  According to the fifth aspect of the present invention, the temperature of the combustion air on the outlet side of the recuperator detected by the temperature sensor is input, and the temperature of the combustion air on the outlet side of the recuperator is a preheating upper limit temperature corresponding to the fuel type. If the temperature is lower than that, the temperature of the combustion air is increased by driving the motor and adjusting the flow passage adjusting partition plate so that the opening amount of the combustion air inlet of the recuperator is increased to increase the heat transfer area of the recuperator. When the temperature of the combustion air on the outlet side of the recuperator exceeds the preheating upper limit temperature, the motor is driven and the opening amount of the combustion air inlet of the recuperator is set by the flow path adjusting partition plate. Adjusting to reduce the heat transfer area of the recuperator to suppress the temperature rise of combustion air so that the preheating upper limit temperature is not exceeded Door can be. Therefore, it is possible to always perform preheating at the preheating upper limit temperature corresponding to the fuel type, and it is possible to prevent the NOx concentration in the exhaust gas from exceeding the regulation value while maintaining high efficiency of the heat medium boiler.

  According to the present invention, by adjusting the heat transfer area of the recuperator, each fuel type can be preheated at a preheating upper limit temperature corresponding to the fuel type, and while maintaining high efficiency of the heat medium boiler, It is possible to prevent the NOx concentration from exceeding the regulation value.

It is a schematic block diagram which shows the 1st example of embodiment of the heat medium boiler which concerns on this invention. It is a schematic structure perspective view showing an example of a recuperator used in the 1st example. It is a schematic structure perspective view which shows an example of the flow-path adjustment partition plate which adjusts the opening amount of the exhaust gas inlet_port | entrance of the recuperator used in the 1st example. It is a schematic structure perspective view which shows the other example of the flow-path adjustment partition plate which adjusts the opening amount of the waste gas inlet_port | entrance of the recuperator used in the 1st example. It is a schematic block diagram which shows the 2nd example of embodiment of the heat medium boiler which concerns on this invention.

Hereinafter, the form for implementing the heat-medium boiler which concerns on this invention is demonstrated in detail with reference to the Example shown on drawing.
FIG. 1 is a schematic configuration diagram showing a first example of an embodiment of a heat medium boiler according to the present invention, FIG. 2 is a schematic configuration perspective view showing an example of a recuperator used in the first example, and FIG. 3 is a first example. FIG. 4 is a schematic configuration perspective view showing an example of a flow path adjusting partition plate for adjusting the opening amount of the exhaust gas inlet of the recuperator used in FIG. 4, and FIG. 4 is a flow path for adjusting the opening amount of the exhaust gas inlet of the recuperator used in the first example. It is a schematic structure perspective view which shows the other example of an adjustment partition plate.

  In the heat medium boiler 1 of this example, a burner 2 is disposed at the top, and a combustion chamber 5 is formed inside a can body 4 in which a heat medium oil heating tube 3 through which the heat medium oil passes is formed in a double coil shape. Yes. The burner 2 is attached to a wind box 6 provided on the upper portion of the can 4, and includes a blower 8 that sends combustion air to the wind box 6 via a combustion air supply line 7. The blower 8 is provided with an inverter 9, and by controlling the frequency of the inverter 9, the rotational speed of the blower 8 can be controlled to adjust the air volume. The combustion gas combusted in the combustion chamber 5 flows between the inner row and the outer row through a gap below the inner row of the heat transfer oil heating tube 3 formed in a double coil shape constituting the can body 4. And rise between the outer rows. The combustion gas rising between the inner row and the outer row of the heat transfer oil heating tube 3 flows to the exhaust gas line 10.

  Further, a recuperator 11 connected to the exhaust gas line 10 and the combustion air supply line 7 is provided, and heat is exchanged between the exhaust gas flowing through the exhaust gas line 10 and the combustion air flowing through the combustion air supply line 7 for combustion. Preheat the working air. A fuel gas supply line 12 for supplying fuel gas is connected to the burner 2. The fuel gas supply line 12 is provided with a fuel gas flow rate adjustment valve 13 for supplying fuel gas to the burner 2.

FIG. 2 is a schematic configuration perspective view showing an example of the recuperator 11 used in this example. 11a is an exhaust gas inlet, 11b is an exhaust gas outlet, 11c is a combustion air inlet, and 11d is a combustion air outlet.
In this example, the heat transfer area adjusting means 14 for adjusting the heat transfer area of the recuperator 11 according to the fuel type is provided at the exhaust gas inlet 11a of the recuperator 11. The heat transfer area adjusting means 14 adjusts the opening amount of the exhaust gas inlet 11 a of the recuperator 11 in order to adjust the heat transfer area of the recuperator 11. The opening amount is set for each fuel type so that the heat transfer area of the recuperator 11 can be a heat transfer area where the combustion air can be preheated at a preheating upper limit temperature corresponding to the fuel type. In addition, the preheating upper limit temperature is set as city gas (13A) 300 degreeC, liquefied petroleum gas (LPG) 200 degreeC, etc.

In this example, the flow path adjustment partition plate 15 is used as the heat transfer area adjusting means 14, and the heat transfer area of the recuperator 11 is adjusted by closing a part of the exhaust gas inlet 11 a and adjusting the opening amount.
In this example, as shown in FIG. 3, the flow path adjustment partition plate 15 is slidably disposed at the exhaust gas inlet 11 a of the recuperator 11, and a rack 25 provided on the flow path adjustment partition plate 15 and a drive shaft of the motor 16. The amount of opening of the exhaust gas inlet 11a is adjusted by engaging the pinion 26 provided on the motor and sliding the flow path adjusting partition plate 15 by driving the motor 16 so as to close part of the exhaust gas inlet 11a. ing.
Instead of this sliding method, as shown in FIG. 4 as another example of the flow path adjustment partition plate 15, a rotary shaft 27 is provided across the exhaust gas inlet 11a of the recuperator 11, and the flow path adjustment partition plate 15 is provided on the rotary shaft 27. And the opening amount of the exhaust gas inlet 11a is adjusted by rotating the flow path adjusting partition plate 15 via the rotating shaft 27 by driving the motor 16 so as to close and close part of the exhaust gas inlet 11a. Also good.
The opening / closing operation of the flow path adjusting partition plate 15 is performed by driving the motor 16, but may be performed manually.
Note that the heat transfer area adjusting means 14 is not limited to the flow path adjusting partition plate 15, but may be anything that can adjust the opening amount of the exhaust gas inlet 11 a of the recuperator 11.

  In this example, a temperature sensor 17 for detecting the temperature of combustion air on the outlet side of the recuperator 11 in the combustion air supply line 7 is provided, and the temperature of the combustion air detected by the temperature sensor 17 is controlled. 18 is sent.

  The combustion air supply line 7 between the blower 8 and the recuperator 11 is provided with a pressure loss unit 19 that applies pressure loss to the combustion air flowing through the combustion air supply line 7. Further, a differential pressure detecting means 20 for detecting the pressure on the inlet side and the outlet side of the pressure loss part 19 to obtain a differential pressure is provided, and the inlet side and the outlet of the pressure loss part 19 obtained by the differential pressure detection means 20 are provided. The differential pressure on the side is transmitted to the control unit 18.

  In the heat medium boiler 1 of this example, the heat medium oil is circulated between the load device (not shown) and the can body 4 by the operation of the circulation pump 21, and the heat medium oil whose temperature has decreased in the load device can It returns to the heat-medium oil heating tube 3 of the body 4, is heated by the can body 4, and is again sent to a load apparatus. A temperature sensor 22 is provided at the outlet of the heat transfer oil heating tube 3 of the can body 4.

  The control unit 18 determines the required combustion amount according to the temperature detected by the temperature sensor 22 provided at the outlet of the heat transfer oil heating pipe 3, and adjusts the fuel gas flow rate adjustment valve 13 so as to become the combustion amount. In addition, the function of adjusting the air volume by controlling the rotation speed of the blower 8 by controlling the frequency of the inverter 9 so that the combustion air quantity corresponding to the determined combustion quantity is obtained, and for the combustion corresponding to the fuel type The preheating upper limit temperature of the air is stored, the temperature data of the combustion air on the outlet side of the recuperator 11 detected by the temperature sensor 17 is taken in, and the temperature of the combustion air on the outlet side of the recuperator 11 is determined for each fuel type. The function of adjusting the opening amount of the exhaust gas inlet 11a of the recuperator 11 by controlling the motor 16 so as not to exceed the preheating upper limit temperature and opening and closing the flow path adjusting partition plate 15 and the amount of combustion of the fuel type The differential value between the inlet side and the outlet side of the pressure loss portion 19 provided in the combustion air supply line 7 and the numerical value of the frequency of the inverter 9 corresponding to the differential pressure are stored, and the frequency of the inverter 9 is converted into the detected differential pressure. It has a function to control to the corresponding frequency.

The heat medium boiler 1 of this example configured as described above is operated as follows.
Prior to the start of operation, first, the setting on the operation program or the switch such as the operation panel is turned on, and the fuel type or the preheating upper limit temperature of the combustion air is input to the control unit 18 to start the operation. At this time, the opening amount of the exhaust gas inlet 11a of the recuperator 11 is in the maximum state, and the heat transfer area of the recuperator 11 is maximum.
When the operation of the heat medium boiler 1 is started, the heat medium oil is heated by the can body 4 and circulated between the load device and the can body 4 by the operation of the circulation pump 21.

  During operation, the combustion air sent to the wind box 6 is preheated by exchanging heat with the exhaust gas in the recuperator 11 and preheated, the temperature of the combustion air rises, and the fuel type in which the temperature of the combustion air on the outlet side of the recuperator 11 is input. If the preheating upper limit temperature is exceeded, the control unit 18 drives the motor 16 and adjusts the opening amount of the exhaust gas inlet 11a of the recuperator 11 by the flow path adjusting partition plate 15 so as to reduce the heat transfer area of the recuperator 11. To reduce the temperature rise of the combustion air so that the preheating upper limit temperature is not exceeded. Further, when the temperature of the combustion air becomes lower than the preheating upper limit temperature, the motor 16 is driven to adjust the opening amount of the exhaust gas inlet 11a of the recuperator 11 by the flow path adjusting partition plate 15 to increase the recuperator. The temperature of the combustion air is increased by increasing the heat transfer area of 11.

In this way, during operation, the opening amount of the exhaust gas inlet 11a of the recuperator 11 is automatically adjusted by the control unit 18 so as to have a heat transfer area capable of preheating combustion air at a preheating upper limit temperature corresponding to the fuel type.
Further, although the pressure loss of the combustion air flowing through the combustion air supply line 7 increases due to the adjustment of the opening amount of the exhaust gas inlet 11a of the recuperator 11, the pressure loss unit 19 provided in the combustion air supply line 7 by the control unit 18 is increased. On the basis of the differential pressure between the inlet side and the outlet side, the inverter 9 is controlled to control the amount of air blown from the blower 8.

By adjusting the flow passage cross-sectional area of the exhaust gas inlet 11a of the recuperator 11 in this way, the combustion air can be preheated at the preheating upper limit temperature corresponding to the fuel type, while maintaining the efficiency of the heat medium boiler high. It is possible to prevent the NOx concentration inside from exceeding the regulation value.
Although the pressure loss of the combustion air flowing through the combustion air supply line 7 increases due to the adjustment of the opening amount of the exhaust gas inlet 11a of the recuperator 11, the inlet of the pressure loss unit 19 provided in the combustion air supply line 7 by the control unit 18 Since the inverter 9 is controlled based on the pressure difference between the outlet side and the outlet side to control the amount of air blown from the blower 8, a constant air-fuel ratio can be maintained even if the flow passage cross-sectional area is adjusted, and the air flow is stable. Combustibility can be maintained.

FIG. 5 is a schematic configuration diagram showing a second example of the embodiment of the heat medium boiler according to the present invention.
About the heat medium boiler of this example, about the same structure as the said 1st example, the same code | symbol is attached | subjected, the description is abbreviate | omitted, and only a different structure from a 1st example is demonstrated.

  The heat medium boiler 1 of this example is provided with a heat transfer area adjusting means 23 for adjusting the heat transfer area of the recuperator 11 in accordance with the fuel type at the combustion air inlet 11 c of the recuperator 11. The heat transfer area adjusting means 23 adjusts the opening amount of the combustion air inlet 11 c of the recuperator 11 in order to adjust the heat transfer area of the recuperator 11. The opening amount is set for each fuel type so that the heat transfer area of the recuperator 11 can be a heat transfer area where the combustion air can be preheated at a preheating upper limit temperature corresponding to the fuel type. In addition, the preheating upper limit temperature is set as city gas (13A) 300 degreeC, liquefied petroleum gas (LPG) 200 degreeC, etc.

In this example, the flow path adjusting partition plate 24 is used as the heat transfer area adjusting means 23, and the heat transfer area of the recuperator 11 is adjusted by closing a part of the combustion air inlet 11c and adjusting the opening amount. Yes.
In this example, the flow path adjustment partition plate 24 is configured to adjust the opening amount of the combustion air inlet 11c by opening and closing the combustion air inlet 11c of the recuperator 11 so as to slide and close a part thereof. Although this configuration is not shown, a mechanism similar to the slide mechanism (see FIG. 3) of the flow path adjusting partition plate 15 that slides and adjusts the opening amount of the exhaust gas inlet 11a of the recuperator 11 of the first example is adopted. Yes.
Instead of this sliding method, as another example of the flow path adjustment partition plate 24, the flow path adjustment partition plate 24 is attached to a rotating shaft provided across the combustion air inlet 11c, and the opening amount is adjusted by rotating this. It is also possible to use this method. Although this configuration is not shown, a mechanism similar to the rotation mechanism (see FIG. 4) of the flow path adjustment partition plate 15 that rotates and adjusts the opening amount of the exhaust gas inlet 11a of the recuperator 11 of the first example is employed. .
The opening / closing operation of the flow path adjusting partition plate 24 is performed by driving the motor 16, but may be performed manually.
The heat transfer area adjusting means 23 is not limited to the flow path adjusting partition plate 24, and any means can be used as long as the opening amount of the combustion air inlet 11c of the recuperator 11 can be adjusted.
Since the other configuration is the same as that of the first example, the description of the first example is cited and the description thereof is omitted.

The heat medium boiler 1 of this example configured as described above is operated as follows.
As in the first example, the heat medium boiler 1 of this example is operated by first setting the operation program or turning on a switch such as an operation panel and inputting the fuel type to the control unit 18 before starting the operation. To start. At this time, the opening amount of the combustion air inlet 11c of the recuperator 11 is in the maximum state, and the heat transfer area of the recuperator 11 is maximum.
When the operation of the heat medium boiler 1 is started, the heat medium oil is heated by the can body 4 and circulated between the load device and the can body 4 by the operation of the circulation pump 21.

  During operation, the combustion air sent to the wind box 6 is preheated by exchanging heat with the exhaust gas in the recuperator 11 and preheated, the temperature of the combustion air rises, and the fuel type in which the temperature of the combustion air on the outlet side of the recuperator 11 is input. If the preheating upper limit temperature is exceeded, the control unit 18 drives the motor 16 to adjust the opening amount of the combustion air inlet 11c of the recuperator 11 by the flow path adjusting partition plate 24 so as to reduce the transmission of the recuperator 11. Reduce the heat area to prevent the combustion air temperature from rising and not to exceed the preheat upper limit temperature. Further, when the temperature of the combustion air becomes lower than the preheating upper limit temperature, the motor 16 is driven and adjusted by the flow path adjustment partition plate 24 so that the opening amount of the combustion air inlet 11c of the recuperator 11 is increased. The temperature of the combustion air is increased by increasing the heat transfer area of the recuperator 11.

Thus, during operation, the opening amount of the combustion air inlet 11c of the recuperator 11 is automatically adjusted by the control unit 18 so as to have a heat transfer area capable of preheating the combustion air at the preheating upper limit temperature corresponding to the fuel type. .
Further, the pressure loss of the combustion air flowing through the combustion air supply line 7 is increased by adjusting the opening amount of the combustion air inlet 11c of the recuperator 11, but the pressure loss provided by the control unit 18 in the combustion air supply line 7 is increased. Based on the differential pressure between the inlet side and the outlet side of the part 19, the inverter 9 is controlled to control the amount of air blown from the blower 8.

In this way, by adjusting the flow passage cross-sectional area of the combustion air inlet 11c of the recuperator 11, the combustion air can be preheated at the preheating upper limit temperature corresponding to the fuel type, while maintaining the efficiency of the heat medium boiler high. The NOx concentration in the exhaust gas can be prevented from exceeding the regulation value.
The pressure loss of the combustion air flowing through the combustion air supply line 7 increases due to the adjustment of the opening amount of the combustion air inlet 11c of the recuperator 11, but the pressure loss part provided in the combustion air supply line 7 by the control unit 18 Since the air flow rate from the blower 8 is controlled by controlling the inverter 9 on the basis of the differential pressure between the inlet side and the outlet side of 19, a constant air-fuel ratio can be maintained even if the flow path cross-sectional area is adjusted. , Stable combustibility can be maintained.

1 Heat medium boiler 2 Burner 3 Heat medium oil heating tube 4 Can body 5 Combustion chamber 6 Wind box 7 Combustion air supply line 8 Blower 9 Inverter 10 Exhaust gas line 11 Recuperator 11a Exhaust gas inlet 11b Exhaust gas outlet 11c Combustion air inlet 11d For combustion Air outlet 12 Fuel gas supply line 13 Fuel gas flow rate adjustment valve 14 Heat transfer area adjustment means 15 Flow path adjustment partition plate 16 Motor 17 Temperature sensor 18 Control part 19 Pressure loss part 20 Differential pressure detection means 21 Circulation pump 22 Temperature sensor 23 Thermal area adjusting means 24 Flow path adjusting partition plate 25 Rack 26 Pinion 27 Rotating shaft

Claims (5)

A heat medium boiler including a recuperator that preheats combustion air by exchanging heat between exhaust gas discharged from a boiler that burns gaseous fuel and combustion air that is sent to a burner using a blower,
A heat medium boiler comprising a heat transfer area adjusting means for adjusting a heat transfer area of a recuperator according to a fuel type.   The heating medium boiler according to claim 1, wherein the heat transfer area adjusting means is provided at an exhaust gas inlet of a recuperator.   The heat transfer area adjusting means includes a flow path adjusting partition plate that adjusts an opening amount of an exhaust gas inlet of the recuperator by driving a motor, and a temperature that detects the temperature of combustion air on the outlet side of the recuperator in the combustion air supply line A sensor for storing a preheating upper limit temperature of the combustion air according to the fuel type, and the temperature detected by the temperature sensor so that the temperature of the combustion air does not exceed the preheating upper limit temperature according to the fuel type. The heating medium boiler according to claim 2, further comprising: a control unit that controls the amount of opening of an exhaust gas inlet of the recuperator by controlling   The heating medium boiler according to claim 1, wherein the heat transfer area adjusting means is provided at a combustion air inlet of a recuperator.   The heat transfer area adjusting means detects the temperature of the combustion air on the outlet side of the recuperator in the combustion air supply line, and the flow path adjusting partition plate for adjusting the opening amount of the combustion air inlet of the recuperator by driving the motor. A temperature sensor, and stores a preheating upper limit temperature of the combustion air according to the fuel type, and the temperature detected by the temperature sensor so that the temperature of the combustion air does not exceed the preheating upper limit temperature according to the fuel type. The heating medium boiler according to claim 4, further comprising a control unit that controls a motor to adjust an opening amount of a combustion air inlet of the recuperator.

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