JP2010117100A - Latent heat recovery type heat source machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a latent heat recovery type heat source machine capable of properly preventing dew condensation in an exhaust tube while minimizing the deterioration of heat efficiency. <P>SOLUTION: The latent heat recovery type heat source machine includes a burner unit 5 in which a plurality of burners producing combustion exhaust gas are arranged, a primary heat exchanger 23 mainly collecting sensible heat from the combustion exhaust gas, a secondary heat exchanger 24 mainly collecting latent heat by the condensation of water vapor from the combustion exhaust gas, and a control means for controlling the combustion of the burner unit 5. The control means 7 controls fixed combustion by variably controlling the output of burner combustion in a state of fixing a combustion area of the burner unit 5 in a wide range (S1). An intermittent operation for on/off-controlling the burner combustion is executed during the fixed combustion control (S2), and a dew condensation drying mode operation for controlling the output of the burner combustion in a state of setting the combustion area of the burner unit 5 to a minimum range is performed for a prescribed time (S4, S5) when the intermittent operation is continued for a specific time (S3). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a latent heat recovery type heat source device used for a heating device, a hot water heater, a hot water heater, a bath water heater, and the like.

Conventionally, in a heat source device used for a heating device or the like, by increasing the burner combustion amount when a certain amount of time has elapsed after the burner combustion amount falls below the critical combustion amount, the exhaust temperature becomes low for a long time. Avoiding dew condensation in the exhaust pipe by avoiding it (Patent Document 1).
JP-A-6-347094

By the way, in the latent heat recovery type heat source machine, it is conceivable to increase the burner combustion amount when the burner combustion amount falls below the critical combustion amount in order to prevent dew condensation in the exhaust pipe as in the conventional case.
However, the latent heat recovery type heat source machine includes a primary heat exchanger that mainly recovers sensible heat from combustion exhaust gas, and a secondary heat exchanger that recovers latent heat by condensing water vapor in the combustion exhaust gas, The exhaust temperature is considerably lower than that without a secondary heat exchanger. Also, in the latent heat recovery type heat source machine, the combustion area of the burner unit in which a plurality of burners are arranged is fixed to a large area, such as a large area and a middle area, and a large amount of water vapor is included in the combustion exhaust gas. Combustion control may be performed to further improve the thermal efficiency in the secondary heat exchanger. Therefore, even if the burner combustion amount is increased, the exhaust temperature rises slowly, and the amount of water vapor in the combustion exhaust gas increases as the burner combustion amount increases, so that the combustion exhaust gas with high humidity is sent to the exhaust stack. It was difficult to well prevent condensation in the exhaust stack. In particular, in a long exhaust pipe of the extended exhaust type, it is difficult to keep the exhaust temperature high over the entire length of the exhaust pipe, and it takes a considerably long time to dry the condensation generated in the exhaust pipe. On the other hand, if the excessive burner combustion state is continued for a long time in order to sufficiently raise the exhaust gas temperature, it may be difficult to maintain high thermal efficiency in the latent heat recovery type heat source machine.

  This invention is made | formed in view of the said situation, and makes it a subject to prevent dew condensation in an exhaust pipe favorably, without reducing thermal efficiency as much as possible in a latent heat recovery type heat source machine.

The latent heat recovery type heat source machine according to the present invention is:
A burner unit in which a plurality of burners are arranged in order to generate combustion exhaust gas;
A primary heat exchanger that mainly recovers sensible heat from the flue gas,
A secondary heat exchanger that mainly recovers the latent heat due to the condensation of water vapor from the flue gas,
Control means for performing combustion control of the burner unit,
The control means performs fixed combustion control in which the burner unit combustion range is fixed over a wide range and the output of the burner combustion amount is variably controlled. During this fixed combustion control, the low output state of the burner combustion amount is condensed in the exhaust stack. If it continues for a certain period of time, the control region is configured to perform a condensation drying mode operation for controlling the output of the burner combustion amount for a predetermined time by setting the combustion region of the burner unit to a range narrower than the wide range.

According to the above configuration, in the condensation drying mode operation, by setting the combustion region of the burner unit to the narrow range, the generation of water vapor due to combustion is reduced, and the air that has passed through the unburned burner is contained in the combustion exhaust gas. To be mixed. As a result, since the combustion exhaust gas diluted with air (combustion exhaust gas having a reduced water vapor partial pressure) that contains water vapor is sent into the exhaust pipe, the dew condensation temperature in the exhaust pipe decreases. Therefore, even in a long exhaust cylinder, condensation in the exhaust cylinder is prevented, and condensation generated in the exhaust cylinder can be dried.
Also, usually, by the fixed combustion control described above, a large amount of water vapor is generated and contained in the combustion exhaust gas by fixing the combustion area of the burner unit in a wide range and performing burner combustion. The heat efficiency in the secondary heat exchanger that collects the heat is improved.
Therefore, even if the condensation drying mode operation is executed, it is possible to prevent the thermal efficiency from being greatly lowered.

It is desirable that the control means has a control configuration that maximizes the burner combustion amount in the condensation drying mode operation.
According to this, the exhaust temperature can be further raised, and condensation prevention in the exhaust cylinder and drying of the condensation generated in the exhaust cylinder can be further improved.

The control means is configured to perform an intermittent operation in which the burner combustion is turned on / off as a low output state of the burner combustion amount during the fixed combustion control, and when the intermittent operation continues for a certain period of time, the control unit shifts to the condensation drying mode operation. Is desirable.
When intermittent operation for on / off control of burner combustion is executed, the temperature in the exhaust stack decreases while burner combustion is off. When the temperature in the exhaust stack falls below the dew point of the flue gas, the next time burner combustion is turned on, the flue gas is cooled to below the dew point in the exhaust stack, causing water vapor to condense and the May corrode.
However, according to the present invention, when the intermittent operation for controlling on / off of the burner combustion continues for a certain period of time, the burner combustion time is increased by shifting to the dew condensation drying mode operation, and the opportunity for the dew condensation generated in the exhaust stack to dry is increased. Therefore, the condensation generated in the exhaust pipe can be satisfactorily dried.

The control means is configured to perform intermittent operation for on / off control of burner combustion with a low output state of the burner combustion amount during the fixed combustion control, and shift to the condensation drying mode operation when the on / off frequency continues for a certain number of times. Is desirable.
As described above, if intermittent operation for on / off control of burner combustion is performed, condensation may occur in the exhaust stack. However, if the number of on / off operations of burner combustion in intermittent operation continues for a certain number of times, the above-described condensation drying mode operation is performed. By making the transition, the burner combustion time becomes longer, and the chances of condensation drying in the exhaust stacks increase. Therefore, the condensation generated in the exhaust pipe can be satisfactorily dried.

  As described above, according to the latent heat recovery type heat source apparatus according to the present invention, it is possible to satisfactorily prevent dew condensation in the exhaust pipe without reducing the thermal efficiency as much as possible. As a result, it is possible to reliably prevent the exhaust pipe from being corroded by the condensed water containing acidic components, and the exhaust blockage from being frozen by the condensed water.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1: shows the block diagram of the heating apparatus using the latent heat recovery type heat source machine which concerns on one Embodiment of this invention. A heating apparatus 1 shown in FIG. 1 includes a latent heat recovery type heat source machine 2 and a hot water mat 3 interposed between an outward pipe 31 and a return pipe 32 connected to the latent heat recovery type heat source machine 2 and collects latent heat. The warm water generated by the mold heat source unit 2 is circulated through the warm water mat 3 to perform floor heating.

  The latent heat recovery type heat source unit 2 includes a combustion chamber 22 in which a burner unit 5 is installed, a primary heat exchanger 23 that mainly recovers sensible heat from combustion exhaust gas, and condensation of water vapor from the combustion exhaust gas. A secondary heat exchanger 24 that mainly recovers latent heat is provided. An air supply fan 25 is connected to the lower surface of the combustion can body 21, an exhaust port 26 is opened at the upper portion of the combustion can body 21, and the exhaust cylinder 4 is connected to the exhaust port 26. Then, fresh air is supplied into the combustion chamber 22 by the air supply fan 25 and the combustion exhaust gas generated by the burner combustion in the combustion chamber 22 passes through the primary heat exchanger 23 and the secondary heat exchanger 24, and the exhaust port 26. Is discharged to the outside through the exhaust pipe 4. Reference numeral 40 denotes an exterior case of the latent heat recovery type heat source unit 2.

  An outgoing pipe 31 is connected to one end of the primary heat exchanger 23, a return pipe 32 is connected to one end of the secondary heat exchanger 24, and the other end of the secondary heat exchanger 24 and the other primary heat exchanger 23 are connected. The ends are connected to each other via a connecting pipe 33. The return pipe 32 is provided with a pump P, and by driving the pump P, the hot water generated by the latent heat recovery heat source device 2 is circulated and supplied to the hot water mat 3 through the forward pipe 31 and the return pipe 32.

  The burner unit 5 is supplied with fuel gas from a gas supply source through a gas pipe 6. The gas pipe 6 is provided with an original gas on-off valve 61 and a gas proportional valve 62 from the upstream side. The original gas on-off valve 61 is opened and closed to supply and shut off the fuel gas to the burner unit 5. The gas proportional valve 62 is adjusted in opening to adjust the output amount of burner combustion in the burner unit 5. The burner unit 5 is provided with three (plural) burner sets 51 to 53 in which a plurality of burners are arranged in a line. Each burner set 51-53 is provided with ability switching on-off valves 54-56 for supplying and shutting off fuel gas. Accordingly, the burner sets 51 to 53 where the capacity switching on / off valves 54 to 56 are opened are burned.

  The original gas on-off valve 61, the gas proportional valve 62, and the capacity switching on-off valves 54 to 56 are controlled by the control unit 7 (control means). Further, the control unit 7 performs operation control of the heating device 1 including drive control of the air supply fan 25 and the pump P. Operation start and stop of the heating device 1 and setting of a desired temperature for floor heating are performed by a remote controller 8 connected to the control unit 7. The remote controller 8 is installed in a room where the hot water mat 3 is laid.

  Since the heating apparatus 1 has the above-described configuration, when the operation switch of the remote controller 8 is turned on to start the operation of the heating apparatus 1, the control unit 7 drives the pump P to move the forward pipe 31, the backward pipe 32, and The water inside the connection pipe 33 is circulated between the hot water mat 3 and the burner is ignited and the air supply fan 25 is rotated to send the combustion exhaust gas to the heat exchangers 23 and 24. Then, the return water that enters the secondary heat exchanger 24 from the hot water mat 3 through the return pipe 32 first recovers mainly the latent heat due to the condensation of water vapor from the combustion exhaust gas by the secondary heat exchanger 24 and heat exchange heating. Thus, the water temperature is raised to a certain degree and becomes low temperature water. Next, the low-temperature water entering the primary heat exchanger 23 from the secondary heat exchanger 24 through the connecting pipe 33 is mainly heat-exchanged by the sensible heat recovered from the combustion exhaust gas by the primary heat exchanger 23, Is further heated and supplied to the forward pipe 31. This hot water is circulated and supplied to the hot water mat 3 to perform floor heating.

  When latent heat is recovered from the combustion exhaust gas by the secondary heat exchanger 24, water vapor in the combustion exhaust gas is condensed and drainage is generated. This drain contains an acidic component such as NOx and is in an acidic state. Therefore, the drain generated in the secondary heat exchanger 24 is transferred to the inclined bottom plate 27 below the secondary heat exchanger 24 and neutralized by the neutralizer 9 through the pipe 91 and discharged to the outside. The combustion exhaust gas that has passed through the secondary heat exchanger 24 is exhausted to the outside through the exhaust cylinder 4.

  Then, referring to the flowchart of FIG. 2, during the heating operation, the control unit 7 performs fixed combustion control in which the combustion region of the burner unit 5 is fixed over a wide range and the output amount of the burner combustion is variably controlled ( S1). In this fixed combustion control, large-area combustion is set in which all three burner sets 51 to 53 are burned, but when the hot water mat 3 does not require a large heating capacity with a small area, It may be set to the middle range combustion which burns two.

Here, when the burner combustion amount is variably controlled with the burner combustion region fixed, the flame may disappear if the burner combustion amount is reduced too much. Therefore, normally, combustion / non-combustion of each of the burner groups 51 to 53 is performed. Combustion control for changing the burner combustion region of the burner unit 5 by sequentially switching is performed.
However, in the present embodiment, the combustion region of the burner unit 5 is set over a wide range to control the combustion. As a result, a large amount of water vapor can be generated by burning the burner unit 5 over a wide range in the combustion region, and a large amount of water vapor can be included in the combustion exhaust gas. As a result, the combustion in the latent heat recovery type heat source unit 2 can be performed. The thermal efficiency in the secondary heat exchanger 24 that condenses water vapor in the exhaust gas and recovers latent heat can be further improved.

  And the control part 7 adjusts the opening degree of the gas proportional valve 62 so that the floor temperature detected by the temperature sensor (not shown) installed in the hot water mat 3 becomes the set temperature set by the remote controller 8. Variable control of burner combustion output. At this time, if the floor room temperature exceeds the set temperature even if the opening of the gas proportional valve 62 is minimized and the output amount of burner combustion is the lower limit, the control unit 7 opens and closes the original gas on-off valve 61 to open and close the burner. An intermittent operation for on / off control of combustion is performed (S2), and combustion control is performed so that the bed temperature becomes the set temperature.

  When such intermittent operation for controlling on / off of the burner combustion (low output state of burner combustion amount) is executed, the temperature in the exhaust stack 4 decreases while the burner combustion is turned off. When the temperature in the exhaust pipe 4 becomes lower than the dew point of the combustion exhaust gas, the next time burner combustion is turned on, the combustion exhaust gas is cooled to the dew point or lower in the exhaust pipe 4 to cause water vapor to condense and be discharged by acidic dew condensation water. There is a risk of corroding the cylinder 4.

  Therefore, when the duration of the intermittent operation during the fixed combustion control is longer than a certain time (eg, 1 hour) (S3), it is considered that there is a possibility that condensation is generated in the exhaust pipe 4, and the condensation drying is performed. The mode operation is executed (S4). Specifically, in this condensation drying mode operation, the opening / closing control of the capacity switching on / off valves 54 to 56 is performed so that only one of the three burner groups 51 to 53 is burned to reduce the combustion region of the burner unit 5 to the minimum range ( The range is narrower than that in the fixed combustion control), and the opening of the gas proportional valve 62 is set to the maximum to burn the burner combustion at the maximum output amount.

  By this condensation drying mode operation, by setting the combustion region of the burner unit 5 to the minimum range, water vapor generated by combustion is reduced, and two burner sets that are not burned in the combustion exhaust gas (for example, the burner set) 52, 53) is mixed. Therefore, since the combustion exhaust gas (combustion exhaust gas in which the water vapor partial pressure is reduced) that is low in the ratio containing water vapor and diluted with short-circuit air is sent into the exhaust cylinder 4, the dew condensation temperature in the exhaust cylinder 4 is lowered. In the condensation drying mode operation, the combustion range of the burner unit 5 is set to the minimum range, but the burner combustion amount is set to the maximum output, so that the exhaust gas temperature is raised more than in the low output state of the burner combustion amount by the on / off control. Can be made. As a result, even in the long exhaust cylinder 4, condensation in the exhaust cylinder 4 can be prevented, and condensation generated in the exhaust cylinder 4 can be dried at an early stage.

  When the condensation drying mode operation is performed for a predetermined time (for example, 1 hour) (S5), the control returns to the fixed combustion control again (S5 → S1). Although the thermal efficiency in the secondary heat exchanger 24 is lowered by the condensation drying mode operation, as described above, the thermal efficiency in the secondary heat exchanger 24 is improved by performing the fixed combustion control (S1, S2). Therefore, relatively large reduction in thermal efficiency can be prevented.

  Therefore, according to the above embodiment, it is possible to satisfactorily prevent condensation in the exhaust tube 4 without reducing the thermal efficiency as much as possible. As a result, it is possible to reliably prevent corrosion of the exhaust cylinder 4 due to acidic dew condensation water, exhaust blockage due to freezing of dew condensation water, and the like.

(Other embodiments)
In another embodiment, as shown in the flowchart of FIG. 3, when an intermittent operation for on / off control of burner combustion is performed during the heating operation (S2), the combustion time is short (eg, 2 minutes or less). ), When the burner combustion is turned on and off for a certain number of times (for example, 10 times) (S30), it is considered that condensation may occur in the exhaust pipe 4, and the above-mentioned condensation drying mode operation is executed ( S4). When the condensation drying mode operation is performed for a predetermined time (eg, 1 hour) (S5), the operation returns to the fixed combustion control again (S5 → S1).

Also in the other embodiments, the dew condensation mode operation allows the flue gas that does not contain much water vapor (the flue gas whose vapor partial pressure has been reduced) to be sent into the exhaust tube 4. The exhaust gas temperature can be lowered and the exhaust gas temperature can be raised more than in the low output state of the burner combustion amount by the on / off control. Therefore, condensation in the exhaust cylinder 4 is prevented, and condensation generated in the exhaust cylinder 4 can be dried quickly. Moreover, since the fixed combustion control is usually performed and the thermal efficiency in the secondary heat exchanger 24 is improved, even if the condensation drying mode operation is executed, a relatively large reduction in thermal efficiency can be suppressed. Therefore, also in other embodiments, it is possible to satisfactorily prevent dew condensation in the exhaust tube 4 without reducing the thermal efficiency as much as possible. As a result, the exhaust tube 4 is corroded or dewed by acidic condensed water. Exhaust blockage and the like due to water freezing can be reliably prevented. Other configurations and operational effects are the same as in the above embodiment.
As a condition for shifting to the condensation drying mode operation, the above embodiment is combined with another embodiment, and the duration of intermittent operation is a certain time or more (S3 in FIG. 2), or the combustion time. The burner combustion may be turned on / off for a short time continuously (S30 in FIG. 3). Thereby, the condensation drying mode operation is reliably executed, and the condensation in the exhaust pipe 4 can be more reliably prevented.
Moreover, in the said embodiment, although the heating apparatus 1 is illustrated, the latent-heat-recovery type heat source machine 2 which concerns on this invention may be used not only for the heating apparatus 1 but for a hot water supply heating apparatus, a hot water heater, a bath water heater, etc. Good.

It is a block diagram which shows schematic structure of the heating apparatus by embodiment. It is a flowchart which shows the combustion control of the burner in the heating apparatus of embodiment. It is a flowchart which shows the combustion control of the burner in the heating apparatus of other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heating device 2 Latent heat recovery type heat source machine 3 Hot water mat 4 Exhaust pipe 5 Burner unit 7 Control part (control means)
22 Combustion chamber 23 Primary heat exchanger 24 Secondary heat exchanger 26 Exhaust port 31 Outward pipe 32 Return pipe 51-53 Burner set

Claims (4)

A burner unit in which a plurality of burners are arranged in order to generate combustion exhaust gas;
A primary heat exchanger that mainly recovers sensible heat from the flue gas,
A secondary heat exchanger that mainly recovers the latent heat due to the condensation of water vapor from the flue gas,
Control means for performing combustion control of the burner unit,
The control means performs fixed combustion control in which the burner unit combustion range is fixed over a wide range and the output of the burner combustion amount is variably controlled. During this fixed combustion control, the low output state of the burner combustion amount is condensed in the exhaust stack. A latent heat recovery type heat source unit having a control configuration in which a dew-drying mode operation for controlling the output of the burner combustion amount is performed for a predetermined time by setting the combustion region of the burner unit to a range narrower than the above wide range after continuing for a certain period of time . In the latent heat recovery type heat source machine according to claim 1,
The control means is a latent heat recovery type heat source unit having a control configuration in which the burner combustion amount in the condensation drying mode operation is a maximum output. In the latent heat recovery type heat source machine according to claim 1 or 2,
The control means is configured to perform an intermittent operation in which the burner combustion is turned on / off as a low output state of the burner combustion amount during the fixed combustion control, and when the intermittent operation continues for a certain period of time, the control unit shifts to the condensation drying mode operation. Latent heat recovery type heat source machine. In the latent heat recovery type heat source machine according to claim 1 or 2,
The control means is configured to perform intermittent operation for on / off control of burner combustion with a low output state of the burner combustion amount during the fixed combustion control, and shift to the condensation drying mode operation when the on / off frequency continues for a certain number of times. Latent heat recovery type heat source machine.

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