Combustion device and hot water device equipped therewith

Abstract

The present invention provides a combustion device that can rationally and appropriately suppress issues such as flashback and overheating of the gas burner in accordance with the type of fuel gas. [Solution] The combustion device C is equipped with a gas type determination means 50. When the gas type determination means 50 determines that the fuel gas is a specific type of fuel gas, the control means 5 performs a specific control that shifts the combustion stage of the gas burner 2 to a combustion stage with lower combustion power than the predetermined combustion stage and increases the drive speed of the fan 4 compared to when it is in the specific combustion state.

Description

Technical Field

[0001] The present invention relates to a combustion device of a type having a gas burner, and a hot water device such as a hot water supply device provided with the same.

Background Art

[0002] As specific examples of the combustion device constituting the hot water device, there are those described in Patent Documents 1 to 3. In the combustion devices described in these documents, a gas burner and a fan for supplying combustion air to the gas burner are provided. The gas burner is divided into a plurality of combustion areas, and a plurality of combustion stages with different combustion heat powers can be set by combinations of these plurality of combustion areas. Also, the combustion heat power can be changed in each of the plurality of combustion stages, and this combustion heat power is controlled to a combustion heat power corresponding to a desired required calorific value. According to such a configuration, it is possible to perform fine combustion heat power control while widening the range of change of the combustion heat power.

[0003] However, in the above prior art, as described below, there was still room for improvement.

[0004] That is, as fuel gas, natural gas (main component: methane CH4) and LP gas (main component: propane C3H8) are generally often used. However, different from these, for example, there is a mixed gas in which hydrogen is mixed with natural gas. Here, the mixed gas has a higher combustion speed compared to natural gas and LP gas. For this reason, when exhaust blockage or the like occurs and the ejection speed of the mixed gas and combustion air in the gas burner becomes lower than normal, if the gas burner drives and burns on the small combustion heat power side of a specific combustion stage, flashback occurs, and the flame hole surface of the gas burner becomes in an overheated state (flame hole burning state), which may cause accidents such as equipment damage. Therefore, it is required that such a situation be appropriately prevented.

[0005] Furthermore, the applicant previously proposed the means described in Patent Document 4 as a means to prevent flashback and partial overheating of gas burners in combustion devices. In the method described in the document, if the combustion state of the gas burner remains below a certain level in a low combustion heat state for a certain period of time or longer, control is executed to shift the combustion stage to the low combustion side at that point. Since flashback is more likely to occur in the low combustion heat side of the combustion stage, the above method is effective in suppressing flashback. However, with the above method, the control is executed regardless of the type of fuel gas, so even when the combustion speed of the fuel gas is low and there is little or no possibility of flashback, the control is executed unnecessarily. This results in wasted control operation, and the combustion heat fluctuates frequently with the control, causing the combustion heat to become unstable and the hot water temperature of the hot water supply system to become unstable, among other problems. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2017-150714 [Patent Document 2] Japanese Patent Publication No. 2017-155996 [Patent Document 3] Japanese Patent Publication No. 2024-160429 [Patent Document 4] Japanese Patent Publication No. 2001-4134 [Patent Document 5] Japanese Patent Publication No. 2014-85081 [Patent Document 6] Patent No. 6281357 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] This invention was conceived under the circumstances described above, and its objective is to provide a combustion device and a hot water system equipped therewith that can rationally and appropriately prevent or suppress flashbacks and overheating of gas burners in accordance with the type of fuel gas. [Means for solving the problem]

[0008] To solve the above problems, the present invention employs the following technical measures.

[0009] A combustion device provided by a first aspect of the present invention is a combustion device comprising: a gas burner divided into a plurality of combustion areas capable of individually burning a fuel gas; a fan capable of supplying combustion air to the gas burner; a control means capable of setting a plurality of combustion stages in which the combustion heat output differs depending on the combination of the plurality of combustion areas, and being able to change the combustion heat output in each of these plurality of combustion stages, and being able to control the drive of the gas burner and the fan so that the combustion heat output corresponds to the required heat output, wherein the combustion device further comprises a gas type determination means for determining whether the fuel gas is a specific type of fuel gas whose combustion speed is faster than a predetermined rate, and the control means is configured to perform a specific control when the gas type determination means determines that the fuel gas is the specific type of fuel gas, the gas burner enters a specific combustion state which is a low combustion heat output in a predetermined combustion stage, and when this specific combustion state continues for a predetermined time or longer, the control means is configured to shift the combustion stage of the gas burner to a combustion stage with a lower combustion rate than the predetermined combustion stage and increase the drive speed of the fan compared to when it is in the specific combustion state. In the present invention, if the gas type determination means determines that the fuel gas is not of the specified type, the specific control may not be performed.

[0010] This configuration yields the following effects: In other words, when the fuel gas is of a specific type with a high combustion speed, flashback is more likely to occur when the gas burner enters the aforementioned specific combustion state. However, with the above configuration, if such a specific combustion state continues for a predetermined time or longer, a specific control is executed, the combustion stage shifts to the low-combustion side, and the fan drive speed increases. Therefore, the gas burner enters a drive combustion state that is less likely to cause flashback, and flashback and the resulting overheating of the gas burner are appropriately prevented or suppressed, making it possible to suitably avoid thermal damage to each part. Furthermore, even if the combustion stage of the gas burner is shifted to the low-combustion side, the fan drive speed is increased, so the combustion heat of the gas burner is appropriately maintained, and problems such as a sudden decrease in combustion heat do not occur. On the other hand, the aforementioned specific control can be configured to be executed only when the fuel gas is of a specific type, and not otherwise. Therefore, it is possible to eliminate the waste of frequently executing the aforementioned specific control when the fuel gas is not of a specific type and flashback is unlikely to occur.

[0011] In the present invention, preferably, the gas type determination means is capable of data processing that determines whether the fuel gas is a specific type of fuel gas based on the heat output information when the gas burner is driven and combusted, and determines whether the fuel gas is a specific type of fuel gas based on the obtained data.

[0012] With this configuration, it is possible to automatically determine whether the fuel gas is a specific type of fuel gas based on predetermined information obtained by actually operating and burning the gas burner. This eliminates erroneous judgments regarding the type of fuel gas and also addresses the issue of the type of fuel gas. This eliminates the need to manually input data into a gas type determination system, making it convenient. It is particularly preferable when operating a combustion device in an area where the type of fuel gas is not yet determined.

[0013] In the present invention, preferably, once the gas type determination means determines that the fuel gas is of the specified type, the specific control is executed when the specified combustion state continues for a predetermined time or longer, regardless of whether the type of fuel gas has been changed thereafter.

[0014] This configuration yields the following effects: In other words, when the fuel gas is a specific type of fuel gas with a high combustion rate, the combustion device may become partially blocked at the exhaust, reducing the thermal efficiency of the gas burner during combustion. In this case, if the gas type determination means incorrectly determines that the fuel gas is not a specific type of fuel gas, the specific control will not be executed even if the gas burner reaches a specific combustion state, potentially leading to flashback. However, the above configuration makes it possible to appropriately eliminate such risks.

[0015] In the present invention, preferably, the gas type determination means includes a storage means capable of writing data on whether or not the fuel gas is a specific type of fuel gas through a predetermined operation.

[0016] With this configuration, if the type of fuel gas is known in advance, it is sufficient to write that data to the storage device through a predetermined operation, which is rational. Since it is possible to eliminate the need for data processing to determine the type of fuel gas by actually driving and burning the gas burner to obtain heat output information, control can be simplified.

[0017] A hot water device provided by a second aspect of the present invention is a hot water device comprising a combustion device and a heat exchanger capable of heating hot water using the heat generated by the combustion device, characterized in that the combustion device is the combustion device provided by a first aspect of the present invention.

[0018] According to such a configuration, the same effects as those extended for the combustion device provided by the first aspect of the present invention can be obtained.

[0019] Other features and advantages of the present invention will become more apparent from the following description of the embodiments of the invention with reference to the accompanying drawings.

Brief Description of the Drawings

[0020] [Figure 1] It is an explanatory drawing showing an example of a hot water device provided with a combustion device according to the present invention. [Figure 2] It is a diagram showing an example of the content related to the combustion stage of the gas burner of the combustion device shown in FIG. 1. [Figure 3] It is a diagram showing an example of a plurality of combustion stages of the gas burner of the combustion device shown in FIG. 1. [Figure 4] It is a flowchart showing an example of the operation control executed in the hot water device shown in FIG. 1. [Figure 5] It is a flowchart showing an example of the process related to the gas type determination executed in the hot water device shown in FIG. 1.

Embodiments for Carrying Out the Invention

[0021] Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

[0022] The hot water device WH shown in FIG. 1 is a hot water supply device, and includes a combustion device C, a heat exchanger 11, and a control unit 5 arranged inside an outer case 19.

[0023] The combustion device C forms a combustion chamber 30 inside which a gas burner 2 is arranged, and a can body 3 having an exhaust port 31 formed at the upper part. The combustion device C includes a fan 4 that can supply external air from below to the combustion chamber 30 to supply combustion air to the gas burner 2. In the figure, 18 and 17 indicate an ignition plug and a flame detection sensor, respectively. The flame detection sensor 17 is arranged so that it can detect a flame in any of the combustion stages described later. The heat exchanger 11 is a heat exchanger for heating hot water, for example, constructed using finned tubes, and is located inside the boiler body 3. Hot water flowing into the heat exchanger 11 from the inlet 11a is heated by heat recovery from the combustion gas generated by the driving combustion of the gas burner 2, and this heated hot water reaches the outlet 11b, from which it is supplied to the desired hot water destination via a hot water pipe (not shown). After passing through the heat exchanger 11, the combustion gas is discharged to the outside as exhaust gas from the exhaust port 31.

[0024] The gas burner 2 is composed of multiple burner bodies 20 (combustion tubes) arranged horizontally. Each burner body 20 is, for example, flat and hollow, and although a detailed illustration is omitted, it is configured to have a fuel gas inlet at the bottom and a flame hole at the top for the fuel gas to flow out and burn. This gas burner 2 is divided into multiple combustion areas Aa to Ac, which allow for the individual combustion of fuel gas. For example, the number of burner bodies 20 constituting these combustion areas Aa to Ac are 3, 5, and 9, respectively. The gas pipe 6 for supplying fuel gas to the gas burner 2 from the outside is equipped with a main gas valve V0 and a gas proportional valve V1, which are on / off valves. Furthermore, capacity switching valves Va to Vc are also provided, which are on / off valves that allow for the individual switching of the supply and cessation of fuel gas to each of the combustion areas Aa to Ac.

[0025] In the gas burner 2, multiple combustion stages with different combustion powers can be set by changing the combination of multiple combustion areas Aa to Ac. Specific examples of these multiple combustion stages include stages 1 to 5, as shown in Figure 2. The number of burner bodies 20 that are driven and the combustion areas in each of these stages are as shown in the figure. These switching operations are performed by the control unit 5 opening and closing the capacity switching valves Va to Vc. Furthermore, the combustion power can be further changed in each of the stages 1 to 5 (for example, in Figure 2, when the combustion stage is stage 5, the combustion power can be changed within the range of combustion numbers 15 to 18). This operation is performed by the control unit 5 changing the drive speed of the fan 4 and the valve opening of the gas proportional valve V1.

[0026] As previously mentioned, in the fifth stage, the combustion power can be changed within the range of 15 to 18, while in the fourth stage, the combustion power can be changed within the range of 11 to 16. In both the fifth and fourth stages, the combustion power ranges of 15 to 16 overlap. Similarly, in other combustion stages, those that are one number apart have a partial overlap in their combustion power.

[0027] L1 to L5 in Figure 3 show an example of the multiple combustion stages (stages 1 to 5) described above. The drive speed of fan 4 is not shown in the figure, but it approximates the lines L1 to L5 that represent stages 1 to 5, respectively. If the combustion stages are the same, the greater the combustion heat, the faster the drive speed of fan 4.

[0028] The control unit 5 is configured using a microcomputer or the like, and corresponds to a specific example of the "control means" as defined in this invention. It also has a gas type determination unit 50 including a storage unit 51, and corresponds to a specific example of the "gas type determination means" as defined in this invention. This control unit 5 is connected to the hot water system including the combustion device C. This system controls the overall operation of the WH (warehouse) and performs various data processing tasks; details of these will be described later. The control unit 5 communicates with a remote control 7 installed in a bathroom or kitchen. This remote control 7 has an operation unit 70 with multiple operation switches and a data display unit 71, and can transmit predetermined data to and from the control unit 5. The target hot water temperature of the hot water supply unit WH is set by operating the operation unit 70 of the remote control 7. The hot water system WH is also equipped with temperature sensors Sa and Sb for detecting the inlet and outlet temperatures of the heat exchanger 11, and a flow sensor (not shown) for detecting the hot water flow rate of the heat exchanger 11.

[0029] Next, an example of the operation procedure for the hot water system WH described above will be explained with reference to the flowchart shown in Figure 4, and its function will also be explained.

[0030] First, when the gas burner 2 is driven to perform hot water supply, the gas type determination unit 50 of the control unit 5 performs gas type determination (S1: YES, S2). Here, this gas type determination is a process to determine whether the fuel gas used in this hot water system WH is a specific type of fuel gas with a combustion speed faster than a predetermined rate. A specific type of fuel gas is, for example, a fuel gas with a combustion speed faster than natural gas or LPG, and a mixed gas obtained by mixing hydrogen with natural gas is a concrete example of this.

[0031] Various methods are known for determining the type of gas, and any of these methods may be adopted. However, in this embodiment, the thermal efficiency is determined by comparing the target combustion power (target number) with the actual combustion power (actual number, which corresponds to an example of "thermal output information" in this invention). If this thermal efficiency is equal to or greater than a predetermined standard value, the fuel gas is determined to be of a specific type; otherwise, the fuel gas is determined to be of a different type. When controlling the operation of the gas burner 2, the target combustion power is determined based on the target hot water temperature, the water inlet temperature to the heat exchanger 11, and the hot water flow rate of the heat exchanger 11. The combustion stage of the gas burner 2 is selected, the opening degree of the gas proportional valve V1 is controlled, and the drive speed of the fan 4 is controlled so that this power is achieved. In addition, the actual combustion amount and combustion power when the gas burner 2 is driven and combusted under such conditions are also determined, and the thermal efficiency for hot water combustion is determined. Here, if the fuel gas is of a specific type, its calorific value is higher than that of natural gas or LP gas, so the thermal efficiency will also be higher than that of natural gas or LP gas, and will be above a predetermined standard value. Therefore, it is possible to appropriately determine the type of gas based on the thermal efficiency described above.

[0032] The data resulting from the gas type determination is stored in the storage unit 51 (S3). However, if the fuel gas is determined to be a specific type of fuel gas, the contents of the data stored in the storage unit 51 are maintained, and it is prohibited to change it to not be a specific type thereafter. This is because, regardless of whether the type of fuel gas is changed thereafter, once the fuel gas has been determined to be a specific type, the specific control in step S6 will be executed when the conditions in step S4 described later are met. With this configuration, even if the hot water system WH experiences exhaust blockage and its thermal efficiency decreases, and a situation occurs where a specific type of fuel gas is incorrectly determined to not be a specific type, the specific control in step S6 can be executed appropriately. In principle, the gas type determination is to be performed repeatedly each time the gas burner 2 is driven and combustion occurs. However, once it has been determined that the fuel gas is a specific type of fuel gas, subsequent determination processes may be omitted.

[0033] When gas burner 2 enters a specific combustion state, which is a low combustion heat at a predetermined combustion stage, and this specific combustion state continues for a predetermined time or longer, the condition is that the fuel gas is of a specific type. As a result, specific control is executed (S4:YES, S5:YES, S6). Here, the "specified combustion stages" are, for example, stages 2 through 5. "Specific combustion state" refers, for example, to the driving combustion in the range R2 to R5 of the small combustion heat ranges in the second to fifth stages of Figure 3. "Specific control" is a control that shifts the combustion stage of the gas burner 2 to the low-combustion side combustion stage and increases the drive speed of the fan 4. For example, if the gas burner 2 is in a specific combustion state where it is operating at point Pa in the low-combustion heat range R5 of the 5th stage in Figure 3 for a predetermined time, this control shifts it from point Pa to point Pb of the 4th stage at that point and increases the drive speed of the fan 4. In this case, preferably, the combustion heat (combustion number) is maintained at the same level.

[0034] According to the aforementioned operation control, if the fuel gas is a specific type with a fast combustion rate and conditions are such that the gas burner 2 is prone to flashback, the specific control is executed, and the gas burner 2 enters a driving combustion state that is less prone to flashback, thus preventing flashback. Therefore, overheating of the flame holes of the gas burner 2 caused by flashback is appropriately prevented or suppressed, and thermal damage to each part of the combustion device C can be suitably avoided. In addition, although the combustion stage of the gas burner 2 is shifted to the low combustion side, the driving speed of the fan 4 increases, and the combustion heat of the gas burner 2 is appropriately maintained, so there are no problems such as a sudden decrease in combustion heat and a large drop in the hot water temperature. After the aforementioned specific control is completed, normal combustion control is performed (S7).

[0035] On the other hand, unlike above, even if the conditions of step S4 are met, if the fuel gas is not determined to be of a specific type, the specific control is not executed (S4: YES, S5: NO, S7). With this configuration, it is possible to simplify the control by eliminating the unnecessary execution of the specific control when the fuel gas is not of a specific type but is a type that is unlikely to cause flashback.

[0036] In the hot water system WH of this embodiment, the following configuration is also possible for determining the gas type (see the flowchart in Figure 5). In other words, the memory unit 51 of the control unit 5 can be programmed with data regarding whether the fuel gas belongs to a specific type, for example, by operating the remote control 7. This programming can be done, for example, by the manufacturer's workers when the manufacturer ships the hot water heater WH, or by installers or users during the installation of the hot water heater WH. When programming is done, the control unit 5 refers to the data stored in the memory unit 51 and determines the type of fuel gas (S21: YES, S22). In this case, the subsequent gas type determination process can be omitted.

[0037] On the other hand, if no writing is performed, the gas type is determined (automatically) based on the thermal efficiency of the combustion drive of the gas burner 2 (S21:NO, S23). The gas type determination in step S23 is the same as the gas type determination (automatically) in step S2 of Figure 4. Such control is preferable because it allows for appropriate responses depending on whether the type of fuel gas is known in advance before actually operating the hot water heater (WH).

[0038] The present invention is not limited to the embodiments described above. The specific configurations of each part of the combustion device and hot water device according to the present invention can be modified in various ways within the scope intended by the present invention.

[0039] The specific type of fuel gas referred to in this invention is not limited to a mixture of hydrogen and natural gas; other fuel gases can also be designated as the specific type. The "specific control" of the present invention is performed when a specific combustion state continues for a predetermined time or longer. This "predetermined time" may be constant, but instead, for example, the type of fuel gas (combustion rate) may be used. It can also be modified to accommodate (for example, the faster the fuel gas combustion rate, the shorter the specified time). The combustion device of the present invention is not limited to hot water systems, but can be configured as a combustion device for other applications. The hot water device of the present invention refers to a device capable of generating hot water for use in applications such as general hot water supply, bath water supply, hot water heating, or snow melting. [Explanation of Symbols]

[0040] C Combustion device WH water heater Aa~Ac Combustion Area 2 gas burners 4 Fans 5. Control Unit (Control means, Gas type determination means) 50 Gas type determination unit (gas type determination means) 51 Storage unit (storage means)

Claims

1. A gas burner divided into multiple combustion areas capable of burning fuel gases individually, This gas burner is equipped with a fan capable of supplying combustion air, A control means is provided that allows setting multiple combustion stages with different combustion powers by combining the multiple combustion areas, and that the combustion power can be changed in each of these multiple combustion stages, and that the drive control of the gas burner and the fan can be controlled so that the combustion power corresponds to the required heat quantity. A combustion device equipped with, The system further includes a gas type determination means for determining whether the fuel gas is a specific type of fuel gas whose combustion speed is faster than a predetermined rate. The combustion apparatus is characterized in that, when the gas type determination means determines that the fuel gas is of a specific type, the gas burner enters a specific combustion state which is a low combustion heat at a predetermined combustion stage, and when this specific combustion state continues for a predetermined time or longer, the control means is configured to perform a specific control which shifts the combustion stage of the gas burner to a combustion stage with lower combustion than the predetermined combustion stage and increases the drive speed of the fan compared to when it is in the specific combustion state.

2. A combustion apparatus according to claim 1, A combustion device in which, if the gas type determination means determines that the fuel gas is not of the specified type, the specified control is not performed.

3. A combustion apparatus according to claim 1, The gas type determination means is capable of data processing that determines whether the fuel gas is a specific type of fuel gas based on the heat output information when the gas burner is driven and combusted, and determines whether the fuel gas is a specific type of fuel gas based on the determined data.

4. A combustion apparatus according to claim 3, A combustion device configured such that, once the gas type determination means determines that the fuel gas is of a specific type, the specific control is executed when the specific combustion state continues for a predetermined time or longer, regardless of whether the type of fuel gas is changed thereafter.

5. A combustion apparatus according to claim 1, The gas type determination means includes a storage means capable of writing data on whether or not the fuel gas is a specific type of fuel gas through a predetermined operation, in a combustion device.

6. Combustion device and A heat exchanger capable of heating hot water using the heat generated by this combustion device, A hot water system equipped with, A hot water system characterized in that the combustion device is the combustion device described in any one of claims 1 to 5.

Images