JP2008128575A - Combustion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustion apparatus that can surely avoid the occurrence of overshoot even if the incoming water flow rate is reduced to increase the temperature rise at startup or the degree of increase in gas supply amount is increased.
[MEANS FOR SOLVING PROBLEMS] When switching capacity from ability 1 (characteristic line A1) for combusting only the first burner part to ability 2 (characteristic line A2) for combusting only the second burner part, gas is produced up to the maximum capacity P1max point at ability 1 Before the pressure is increased, at the P1 point corresponding to the minimum capability P2min point of the capability 2 in the number, the process starts to shift to the P3 point (relaxation ignition point) for capability switching. The gas pressure is reduced to moderate ignition and gas is supplied to both the first and second burner parts. After the fire is transferred to the second burner part, the first burner part is extinguished. At that time, the second burner portion is made to correspond to the number of the capacity 1 at the time of switching the throttle capacity up to the gas pressure of the P2min point.
[Selection] Figure 4

Description

  The present invention relates to a combustion apparatus configured to switch the combustion capacity by increasing / decreasing the amount of gas to be burned in addition to increasing / decreasing the number of burners to be burned, and in particular, avoiding occurrence of overshoot at the time of capacity switching. It relates to the technology that can be made.

  Conventionally, as a combustion apparatus capable of switching the capacity, a main burner is divided into a first burner group and a second burner group, and a small capacity control state in which only the first burner group is subjected to combustion and the gas supply amount is increased or decreased, It is known that the capacity can be switched to a large capacity control state in which both the 1 burner group and the second burner group are to be combusted and the gas supply amount is increased or decreased (see, for example, Patent Document 1). In this case, in order to reduce combustion noise, when combustion in a predetermined range where the gas supply amount is maximum is maintained in the small capacity control state, the control is forcibly switched to the large capacity control state. Combustion noise is reduced by reducing the amount of gas supplied to the burner.

  Also, as another combustion device capable of switching the capacity, three gas supply pipes are connected to a burner constituted by a large number of burner sections by a predetermined range, and gas supply by each gas supply pipe is turned ON / OFF. By doing so, there is also known one in which the number of burner portions to be burned can be switched in three stages (see, for example, Patent Document 2). In this case, in order to suppress the occurrence of fluctuations in the hot water supply temperature before and after the capacity switching, the set value set as the gas supply amount in advance at the time of switching is corrected to increase or decrease.

  As control of the combustion amount by normal capacity switching, the gas supply amount is shifted from small to large in a small capacity control state in which a relatively small number of burner regions are to be burned, and the combustion amount is shifted from small to large. The capacity is switched to the large capacity control state on the maximum side of the gas supply amount, and the gas supply amount is changed from small to large again in this large capacity control state so that the combustion amount is continuously increased. It has become.

Japanese Patent No. 2827469 JP 2002-206735 A

  By the way, in the start-up stage from the start of combustion until the hot water of the set temperature is discharged, it is necessary to raise the cold incoming water to the set temperature as quickly as possible to supply hot water. If the capacity switching control is performed from the small capacity side to the large capacity side on the side, the tapping temperature tends to fall into an overshoot tendency immediately after the capacity switching. In particular, when the incoming water flow rate is reduced in order to speed up the above temperature rise, in addition to speeding up the temperature rise, a reduction in gas consumption is also intended to increase the degree of increase in the gas supply amount in the small capacity control state. In addition, when overcapacity switching is performed, or when the temperature has already been raised near the set temperature on the maximum side of the gas supply amount in the small capacity control state before the capacity switching, the above overshoot is more likely to occur. Become.

  There are also situations in which overshoot is likely to occur due to the situation of the equipment attached to the combustion device. For example, in a combustion apparatus having a first burner part and a second burner part having a larger number than the first burner part, a small capacity control state in which only the first burner part is to be burned, and only the second burner part is burned When performing the combustion amount control in the range from the minimum to the maximum by the three-stage capacity switching between the medium capacity control state to be targeted and the large capacity control state in which both the first and second burner parts are to be burned. When the capacity is switched from the small capacity control state (only the first burner section is combusted) to the medium capacity control state (only the second burner section is combusted), ignition means (for example, an igniter) is provided only on the first burner section side. If not, the gas burner of the second burner portion is opened while the combustion state of only the first burner portion is open, the second burner portion is ignited by fire transfer from the first burner portion, and then the first burner portion is extinguished. The ignition of the second burner part It may be necessary to interpose a process order. In such a case, it is considered that overshoot is more likely to occur due to the ability switching.

  The present invention has been made in view of such circumstances. The purpose of the present invention is to reduce the incoming water flow rate or increase the gas supply amount in order to speed up the temperature rise to the set hot water temperature. An object of the present invention is to provide a combustion apparatus that can reliably avoid the occurrence of overshoot even if the degree is increased.

  In order to achieve the above object, the present invention comprises a first burner part having one or more burner numbers, and a second burner part having a larger number of burners than the first burner part. The fuel supply to the first burner part and the second burner part can be switched to open and close independently and the fuel supply amount can be changed and adjusted to select the combustion target by the fuel supply switching, and the fuel for the selected combustion target The following specific matters are provided for a combustion apparatus in which the combustion capacity is variably controlled from the minimum to the maximum according to the required heat amount by changing and adjusting the supply amount. That is, a small capacity control mode for executing combustion control in a small combustion capacity range with only the first burner section as a combustion target, and combustion control in a medium combustion capacity range with only the second burner section as a combustion target. Switch to a combustion capacity range of at least three stages: a medium capacity control mode to be executed and a high capacity control mode to execute combustion control in the large combustion capacity range with both the first and second burner parts as combustion targets. A capability switching means for controlling is provided. Then, if the combustion capacity is increased up to the setting switching value of the small capacity control mode as a switching control from the small capacity control mode to the medium capacity control mode, the fuel capacity of the fuel supply amount for moderate ignition is increased. Is supplied to the second burner unit in addition to the first burner unit, and the second burner unit is ignited and then the first burner unit is extinguished to switch to the medium capacity control mode. A combustion capacity value corresponding to a heat quantity smaller than the maximum heat quantity of the variable range of the combustion capacity in the small capacity control mode and equivalent to or greater than the minimum heat quantity of the variable range of the combustion capacity in the medium capacity control mode Is set (claim 1).

  In the case of the present invention, in the small capacity control mode, the fuel supply amount is increased from the start of combustion, the combustion capacity is increased in the small combustion capacity range, and the heat quantity (output number) is also increased, but the combustion capacity is variable. The maximum heat quantity in the range is not increased, but the capacity switching to the medium capacity control mode is executed with the fuel supply quantity for mitigation ignition being limited to the setting switching value in the heat quantity range smaller than the maximum heat quantity. . For this reason, compared with the case where the capacity is switched to the medium capacity control mode after increasing the maximum combustion capacity corresponding to the maximum heat amount in the small capacity control mode, the occurrence of overshoot is surely avoided. Therefore, even if the incoming water flow rate is reduced or the degree of increase in the fuel supply amount is increased to speed up the temperature rise to the set hot water temperature, the occurrence of overshoot can be reliably avoided.

  In the present invention, as the setting switching value, a combustion capacity value corresponding to a heat quantity equivalent to the minimum heat quantity in the variable range of the combustion capacity in the medium capacity control mode can be set. By doing so, it is possible to maximize the effect of avoiding the above-mentioned overshoot. The above-mentioned flow rate of water is considerably reduced to speed up the temperature rise or increase the amount of fuel supply. Even if it is raised, it is possible to more reliably avoid the occurrence of overshoot.

  Further, as the capacity switching means is switched to the medium capacity control mode, the combustion within the variable range of the combustion capacity in the medium capacity control mode and corresponding to the same amount of heat as the combustion capacity value set in the set switching value. It can be set as the structure which starts combustion control from a capability value (Claim 3). By doing so, it becomes possible to change the combustion capacity before and after the capacity switching from the small capacity control mode to the medium capacity control mode smoothly and continuously.

  As described above, according to any one of claims 1 to 3, when the capacity is switched from the start of combustion to the medium capacity control mode through the increase in the combustion capacity in the small capacity control mode, Capability switching to medium capability control mode by reducing the fuel supply amount for mitigation ignition at the setting switching value in the calorie range smaller than the maximum heat amount without increasing the maximum heat amount in the variable range of the combustion capacity in the capability control mode Therefore, overshooting is reliably avoided compared to when switching to the medium capacity control mode after increasing the maximum combustion capacity corresponding to the maximum heat amount in the small capacity control mode. be able to. For this reason, even if the incoming water flow rate is reduced or the degree of increase in the fuel supply amount is increased to speed up the temperature rise to the set hot water temperature, the occurrence of overshoot can be reliably avoided. .

  In particular, according to claim 2, the effect of avoiding the occurrence of the overshoot can be obtained to the maximum, the temperature of the incoming water can be considerably reduced to speed up the temperature rise, and the degree of increase in the fuel supply amount can be increased. Even if it is raised, it is possible to more reliably avoid the occurrence of overshoot.

  According to the third aspect, the combustion capacity before and after the capacity switching from the small capacity control mode to the medium capacity control mode can be changed smoothly and continuously.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a combustion apparatus taking a gas water heater as an example of the embodiment of the present invention. In the figure, reference numeral 2 denotes a can body accommodated in a housing 1. In the can body 2, a heat exchanger 3 and two or more (two groups in the illustrated example) burner portions 4 a for burning gas as fuel. 4b, and a blower fan (not shown) for supplying combustion air by rotating the fan motor 18 (see FIG. 3) is provided on the lower side. A combustion burner is constituted by the two or more burner portions 4a and 4b.

  The heat exchanger 3 includes a water inlet pipe 5 for allowing water supplied from a water pipe or an elevated water tank to enter the heat exchanger 3, and a hot water outlet pipe 6 for discharging hot water heated in the heat exchanger 3. They are connected in communication with each other. The hot water discharge pipe 6 is connected to a hot water supply pipe (not shown), and hot water is supplied to a hot water tap such as a kitchen or a washroom through the hot water supply pipe. An incoming water flow sensor 7 for detecting the incoming water flow rate and an incoming water temperature sensor 8 for detecting incoming water temperature are interposed in the incoming water pipe 5, and the outgoing hot water temperature immediately after coming out of the heat exchanger 3 is provided in the outgoing hot water pipe 6. A can body temperature sensor 9 for detecting the temperature of the can body 2 by detecting the temperature, a flow rate adjusting valve 10 for controlling the hot water supply flow rate, and a hot water temperature sensor 11 for detecting the temperature of the hot water supplied to the hot water tap. It is intervened. Each of the temperature sensors 8, 9, and 11 is constituted by a thermistor, for example.

  Further, a bypass pipe 12 is connected between the water inlet pipe 5 and the hot water outlet pipe 6, and a bypass water amount adjustment valve for adjusting the bypass flow rate of tap water branched and flowing from the water inlet pipe 5 in the middle of the bypass pipe 12. 13 is interposed. The bypass water amount adjustment valve 13 is controlled by a controller 21 described later, and temperature adjustment (temperature adjustment) of the hot water temperature is performed by mixed water.

  Each of the plurality of burner portions 4a and 4b includes a single burner (for example, a combustion tube set) having a predetermined number of one or two or more (for example, four first burner portions 4a and six second burner portions 4b, for example). Therefore, the number of the second burner portions 4b is set to be larger than that of the first burner portions 4a. A gas supply pipe 14 for supplying gas as a combustion fuel from the fuel gas supply source side is connected to each of the burner portions 4a and 4b. The gas supply pipe 14 is provided with an original gas solenoid valve 15 as an original plug and a gas proportional valve 16 for adjusting the gas supply flow rate in order from the fuel gas supply source side. The gas supply pipe 14 is branched downstream of the gas proportional valve 16, the gas is supplied to the first burner part 4a via the first capacity switching valve GV1, and the second burner part 4b is supplied with the second gas. Gas is supplied through the capacity switching valve GV2. In the present embodiment, an igniter 17 as an ignition means is provided only on the first burner portion 4a side.

  The combustion capacity is gradually and continuously controlled by the selective opening / closing switching control of the first and second capacity switching valves GV1, GV2 and the change adjustment control of the gas supply amount (fuel supply amount) of the gas proportional valve 16. The amount of hot water discharge is variable by continuously changing the combustion amount from the minimum to the maximum so that the change can be adjusted. For example, as shown in FIG. 2, only the first capacity switching valve GV1 is opened and only the first burner portion 4a is combusted to execute the combustion control in the small combustion capacity range (capability 1; FIG. 2). (See (a)), and the first capacity switching valve GV1 is closed, only the second capacity switching valve GV2 is opened, and only the second burner portion 4b is burned to execute the combustion control in the middle combustion capacity range. Mode (capacity 2; see FIG. 2 (c)), or both the first and second capacity switching valves GV1, GV2 are opened to burn both the first and second burner parts 4a, 4b and have a large combustion capacity In the large capacity control mode (capacity 3; see FIG. 2 (d)) for performing combustion control in the range, the combustion object is switched between capacity 1, capacity 2 and capacity 3, and capacity 1, capacity 2, By the capacity switching control of increasing / decreasing the gas supply amount at each capacity 3, the above-mentioned combustion amount can be reduced. It has become possible to continuously variable control of up to a maximum from.

  Note that when the ability is switched from ability 1 to ability 2, since the igniter 17 is provided only on the first burner portion 4a side as described above, the first burner portion 4a is transferred to the second burner portion 4b. A mitigation ignition process is added to make it happen. That is, as the mitigation ignition process, the second force switching valve GV2 is opened and the gas is ejected from the second burner portion 4b while the first burner portion 4a is burned, and the fire is transferred from the first burner portion 4a to the ejected gas. To ignite (ignite). And after the 2nd burner part 4b ignites, the 1st capability switching valve GV1 is closed and the 1st burner part 4a is extinguished. In this simultaneous combustion state, the gas supply amount is limited to that for moderate ignition as described later. Then, both the first capacity switching valve GV1 and the second capacity switching valve GV2 are opened, and a short time (for example, 0.3) is used as an overlapping period in which both the first and second burner portions 4a and 4b are in the simultaneous combustion state. ˜0.5 seconds), and the first capacity switching valve GV1 is closed after the minute time has elapsed since the second force switching valve GV2 was opened. That is, the first capability switching valve GV1 may be closed after the ignition of the second burner portion 4b is detected by other means (for example, a frame rod or the like). Control is simplified by setting the minimum time value at which the second burner portion 4b can ignite with certainty over time and can be ignited.

  If the maximum output number is, for example, 24 specifications as the output capacity (heat amount) after heat exchange in the heat exchanger 3 by continuous variable control of the combustion amount as described above, a predetermined minimum output In the range of the number (for example, 2.5) to 24, the hot water discharge capacity is variable. In addition, 1.0 is a hot-water discharge capacity capable of raising the temperature of 1 L / min of water by 25 ° C., and corresponds to a value obtained by multiplying a heat generation amount corresponding to a gas consumption amount by combustion by a heat exchange efficiency.

  The burner parts 4a and 4b are combusted by receiving the supply of combustion air from a blower fan, and heat exchange heat the incoming water flowing through the heat exchanger 3 with the combustion heat, while the exhaust gas passes through the exhaust passage 2a. It is discharged outside.

  The hot water supply operation by the combustion operation of the combustion system constituted by the burner portions 4a and 4b, the first and second capacity switching valves GV1 and GV2, the gas proportional valve 16, the fan motor 18 of the blower fan, etc. is performed using an MPU, a memory, etc. The controller 21 is provided with various controls based on hot water supply operation control for supplying hot water based on a set temperature (set hot water temperature). That is, as shown in FIG. 3, the controller 21 is connected to a remote controller 22 and includes a hot water supply control means 23 and a capability switching control means 24. From the remote control 22 and various sensors 7, 8, 9, 11 Based on the output signal, the valves GV1, GV2, 16, etc. of the combustion system, the flow rate adjusting valve 10 and the like are controlled to operate.

  The hot water supply control means 23 performs FF control number, FB control number, etc. for each process such as air amount control, gas supply amount control, flow rate control, etc. on the premise of FF (feed forward) control and FB (feedback) control. This is executed based on the number of control outputs (number of requests). In conjunction with the control by the hot water supply control means 23, the capacity switching control means 24 mainly controls the switching of the first and second capacity switching valves GV 1 and GV 2 as described above and the amount of gas supplied to the hot water supply control means 23. The control command output for is executed. The basic hot water supply control by the hot water supply control means 23 will be described. When the user opens the hot water tap with the desired hot water temperature (set hot water temperature) input to the remote controller 22, water enters the incoming water pipe 5 and enters the water. Hot water supply operation control is started by receiving the flow rate detection from the flow rate sensor 7 exceeding the minimum operating water amount (MOQ), and the hot water operation control is started by the user, and the detected value from the incoming water flow rate sensor 7 is the minimum operating flow rate. If it becomes lower than that, combustion by the combustion system is stopped and hot water supply operation control is ended.

  The hot water supply operation control is performed by operating the combustion system so that hot water having the set hot water temperature is discharged. In this combustion operation control, first, the combustion operation is performed based on the detected value from the incoming water flow rate sensor 7 and the incoming water temperature sensor 8 based on the FF control number corresponding to the set hot water temperature, and then the can body temperature sensor 9 or the hot water temperature. By taking into account the FB control number based on the detected temperature from the sensor 11, the combustion temperature is set to reach the set hot water temperature. The above-described combustion operation based on the target control number such as the FF control number or the FB control number is performed by the burner unit 4a that is operated by selectively opening the first and second capacity switching GV1, GV2 by the capacity switching control means 24. Or, and / or in a state where the number of 4b is set to a predetermined number, that is, in a state where either capability 1, capability 2 or capability 3 is set, this corresponds to the target control number at a predetermined air-fuel ratio. This is realized by outputting a proportional operation signal so as to obtain a gas supply amount and an air supply amount. In other words, an operation signal is output to the gas proportional valve 16 so as to achieve a predetermined gas supply amount, and an operation signal for operating at a predetermined rotation speed so as to achieve an air supply amount that realizes a predetermined air-fuel ratio is blown. This is output to the fan motor 18 of the fan, whereby a combustion state that can output a predetermined required number is made.

  The above-mentioned FF control number is the amount of combustion required to raise the incoming water to the set hot water temperature based on the incoming water flow rate from the incoming water flow rate sensor 7, the incoming water temperature from the incoming water temperature sensor 7, and the set hot water temperature. It is obtained by calculation as (amount of heat). The FB control number is set based on the temperature difference between the actual hot water temperature detected by the hot water temperature sensor 11 and the set hot water temperature, for example, so that the actual hot water becomes the set hot water temperature. Increase / decrease of number of issues for

  Next, capability switching control by the capability switching control means 24 will be described. This capability switching control is executed based on capability switching characteristics (see FIG. 4) stored and set in the controller 21 in advance. This capability switching characteristic is characterized by the output pressure and the gas pressure that realizes the output number in each of the small capability control mode at capability 1, the medium capability control mode at capability 2, and the large capability control mode at capability 3. It is represented by characteristic lines A1, A2, and A3 that define the relationship with the gas supply amount). The characteristic line A1 represents the control characteristic of the small capacity control mode (capability 1; see FIG. 2 (a)), the characteristic line A2 represents the control characteristic of the medium capacity control mode (capability 2; see FIG. 2 (c)), A characteristic line A3 represents the control characteristic of the large capacity control mode (capability 3; see FIG. 2D). In this capability switching characteristic, the rising slope of the characteristic line A2 is set stronger than the characteristic line A3, and the rising slope of the characteristic line A1 is set stronger than the characteristic line A2. A strong rising gradient means that the amount of gas supply increases greatly, so that the amount of combustion increases earlier at the start of combustion, and the temperature rises to the set hot water temperature more quickly. It is set to be realized.

When the required number (required heat) is the number corresponding to point D (for example, 12) on the characteristic line A2 of capacity 2, the capacity is switched between capacity 1 and capacity 2 from the start of combustion start. Then, the control for increasing the combustion amount up to the required number will be described. First, only the first capacity switching valve GV1 is opened and only the first burner portion 4a is burned, and the opening of the gas proportional valve 16 is reduced to the minimum heat amount. For example, the gas pressure is increased by increasing the gas pressure (gas supply amount) corresponding to No. 2.5 according to the characteristic line A1. If the gas pressure increases from the point P0 on the characteristic line A1 to the point P1 (setting switching value), the second burner portion 4b starts mitigating ignition for switching the capacity to the capacity 2, and the second capacity switching is performed. At the same time as opening the valve GV2, the opening of the gas proportional valve 16 is reduced so that the gas pressure corresponds to the point P3 (relaxation ignition point) on the characteristic line A3. The above P1 point is lower on the lower capacity side (lower on the lower gas pressure side) than the P1max point which is the maximum combustion capacity value (maximum number at maximum gas pressure, that is, maximum heat amount) within the variable range of the combustion capacity of the characteristic line A1. The same sign as the P2min point corresponding to the minimum capacity (minimum number at the minimum gas pressure, that is, minimum heat quantity) within the variable range of the capacity 2 combustion capacity in the characteristic line A2 It is a point on the characteristic line A1 that is a number (the same amount of heat). In short, P1 point is the ability point within the ability 1 range that is lower than the maximum ability of the ability 1 range, and corresponds to the same number as the minimum ability P2min point of ability 2 that can be switched to ability 2 It is set. The above-mentioned P3 point is the lowest gas pressure (20 mmH ₂ O in FIG. 4) that can be transferred without so-called explosion ignition when transferring from the flame of the first burner 4a to the second burner 4b. ) Is set. By this mild ignition processing, both the first burner portion 4a and the second burner portion 4b are in a simultaneous combustion state (see FIG. 2B).

  The timer is started simultaneously with opening the second capacity switching valve GV2, and when the set minute time (for example, 0.3 to 0.5 seconds) elapses, the first capacity switching valve GV1 is closed and at the same time proportional to gas. The opening degree of the valve 16 is narrowed to a gas pressure corresponding to the P2min point. Thereby, the capability switching from the capability 1 to the capability 2 is completed, and thereafter, combustion only in the second burner portion 4b is started. Then, the opening of the gas proportional valve 16 is increased so that the gas pressure increases along the characteristic line A2, and the combustion amount is increased to a number corresponding to the point D.

  In such a capacity switching control, the capacity switching to the capacity 2 is started at the P1 point before the combustion quantity at the capacity 1 is not increased to the P1max point of the maximum capacity. As shown in the temperature change curve of the tapping temperature shown by the solid line T1 in FIG. 5, although it becomes slightly overshooting due to the simultaneous combustion for a minute time by the above-described relaxation ignition processing, the upper tapping temperature or the set tapping temperature (for example, Overshoot exceeding 50 ° C.) is avoided. In addition, the temperature raising rate becomes higher and the time for raising the temperature to the set hot water temperature can be shortened, that is, the start-up rate can be improved.

 The effects of this embodiment will be described in comparison with the comparative example shown in FIG. 6. In this comparative example, the characteristic lines A1, A2, A3 themselves are the same as those in FIG. It is different from the form. That is, in this comparative example, after the gas pressure is increased from the point P0 to the point P1max along the characteristic line A1 in the capacity 1 in which only the first capacity switching valve GV1 is opened and only the first burner portion 4a is burned, The second capability switching valve GV2 is opened, and the opening of the gas proportional valve 16 is throttled so that the gas pressure corresponds to the relaxation ignition point P3, and the second burner portion 4b is moderately ignited. In the same manner as described above, the first ability switching valve GV1 is closed and the ability is switched to the ability 2 when the set minute time has elapsed. In this case, the opening degree of the gas proportional valve 16 is set so as to be the gas pressure at the point P2 which is the capability point on the characteristic line A2 and is the same number as the P1max point at the capability 1. Subsequently, the gas pressure is increased from the P2 point to the D point. In the case of such a comparative example, after the gas pressure is rapidly increased up to the maximum gas pressure at the P1max point with a steep slope in the capacity 1, the simultaneous combustion state of the first and second burner plates 4a and 4b by the relaxation ignition processing is further performed. Since the capacity switching to capacity 2 is performed after a while, the temperature change curve T2 of the tapping temperature (see the broken line in FIG. 5) greatly overshoots exceeding the set tapping temperature, and FB control is performed. Therefore, the required number of the next stage is calculated so as to correct it, and therefore, the temperature change of the swing back is caused until the temperature reaches the set hot water temperature.

  Such a combustion apparatus according to the present embodiment is suitable for export to, for example, Australia. That is, in Australia, a so-called star rate standard has been established, and according to this, in order to reduce the annual gas consumption, a predetermined temperature (for example, 50 ° C.) is required to start up the water at a predetermined temperature. It is demanded to increase the startup speed. And since the low-temperature hot water discharged before raising the temperature to the predetermined temperature is regarded as wasteful gas consumption as waste water, it is required to raise the temperature quickly (rapid temperature rise). As a countermeasure for this, when trying to increase the rate of temperature rise by reducing the flow rate of the water flow into the heat exchanger 3 by further reducing the opening of the flow rate control valve 10, as shown by the temperature change curve T2 described above, A large overshoot occurs when the ability is switched from ability 1 to ability 2. On the other hand, in Australia, it is required that hot water above a certain upper limit temperature (50 ° C.) is not discharged from the viewpoint of preventing burns, and if this is attempted, the above-described overshoot will be avoided. Therefore, it is necessary to weaken the measures for realizing the star rate. On the other hand, according to the present embodiment, even if the incoming water flow rate is further narrowed, that is, without sacrificing the realization of the star rate, it is possible to reliably avoid overshoot, and thereby the set hot water temperature Occurrence of hot water exceeding (the upper limit temperature) can be avoided reliably, making it suitable for export to Australia.

<Other embodiments>
In addition, this invention is not limited to the said embodiment, Various other embodiments are included. That is, in the above embodiment, the example of the ability switching in the three stages of the ability 1 of the small ability, the ability 2 of the medium ability, and the ability 3 of the large ability has been shown. You may make it apply this invention to the combustion apparatus which makes a combustion quantity continuously variable from the minimum to the maximum by multistage capacity switching.

  In the above embodiment, the P1 point of the ability 1 is set as the setting switching value Pc point from the ability 1 to the ability 2 and the switching is started from the P1 point. , Set to the lower capacity (low number / low gas pressure) side than the P1max point, and to the higher calorie side (high gas pressure side, higher number side) than the P1 point, which has the same number as the P2min point. The switching from the point Pc to P3 may be started. That is, the Pc point may be set so that Pc = P1 or Pc> P1, and P1max> Pc. When Pc = P1, the overshoot avoidance function becomes the maximum side and becomes the safest side, and the overshoot avoidance function gradually decreases as Pc approaches P1max. As in the comparative example (see FIG. 6), Pc = P1max The occurrence of overshoot can be avoided compared to the case of setting.

It is a schematic diagram which shows the example of the combustion apparatus to which embodiment of this invention is applied. FIG. 2 (a) shows the combustion state of ability 1 and FIG. 2 (b) shows the simultaneous combustion for firing and igniting when the ability is switched from ability 1 to ability 2. FIG. 2 (c) shows the combustion state of capacity 2, and FIG. 2 (d) shows the combustion state of capacity 3. It is a block diagram which shows the structure of the controller of embodiment. It is a figure which shows the capability switching characteristic in the case of this embodiment in the relationship between a request | requirement number and gas pressure. It is a figure which shows the change of the tapping temperature with time passage. FIG. 5 is a diagram corresponding to FIG. 4 for a comparative example.

Explanation of symbols

3 Heat exchanger 4a 1st burner part 4b 2nd burner part 5 Inlet pipe 6 Outlet pipe 16 Gas proportional valve 24 Capacity switching control means
GV1 1st capacity switching valve
GV2 2nd capacity switching valve

Claims (3)

A first burner part having one or more burners, and a second burner part having a larger number of burners than the first burner part, and supplying fuel to the first burner part and the second burner part Can be opened and closed independently of each other, and the fuel supply amount can be changed and adjusted, and the combustion capacity is required by selecting the combustion target by switching the fuel supply and adjusting the fuel supply amount for the selected combustion target. In the combustion device variably controlled from the minimum to the maximum according to the amount of heat,
A small capacity control mode for performing combustion control in a small combustion capacity range with only the first burner section as a combustion target, and a combustion control in a medium combustion capacity range with only the second burner section as a combustion target. The medium capacity control mode and the large capacity control mode for executing the combustion control in the large combustion capacity range with both the first and second burner parts as combustion targets are switched to at least three stages of combustion capacity ranges. With ability switching means,
As the switching control from the small capacity control mode to the medium capacity control mode, the capacity switching means, when the combustion capacity increases up to the setting switching value of the small capacity control mode, In addition to the first burner unit, the second burner unit is supplied to ignite the second burner unit, and then the first burner unit is extinguished to switch to the medium capacity control mode. A combustion capacity value corresponding to a heat quantity smaller than the maximum heat quantity of the variable range of the combustion capacity in the small capacity control mode and equivalent to or greater than the minimum heat quantity of the variable range of the combustion capacity in the medium capacity control mode Is set, the combustion apparatus characterized by the above-mentioned. The combustion device according to claim 1,
A combustion apparatus in which a combustion capacity value corresponding to a heat quantity equivalent to a minimum heat quantity in a variable range of the combustion capacity in the medium capacity control mode is set as the setting switching value. The combustion apparatus according to claim 1 or 2,
The capacity switching means, as switching to the medium capacity control mode, is within a variable range of the combustion capacity in the medium capacity control mode and corresponds to the same amount of heat as the combustion capacity value set in the setting switching value. Combustion device configured to start combustion control from.

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