Boiler

Abstract

To provide a boiler capable of suppressing influence of wrong detection, even under a situation where it is impossible to correctly detect a flow rate of combustion air or fuel supplied actually.SOLUTION: A boiler supplies combustion air to a boiler body, detects a flow rate of the supplied combustion air, specifies first information according to the detection result, specifies second information that is a value that is independent of the detected flow rate of combustion air and that can vary depending on an operation mode of the boiler, and adjusts a flow rate of fuel to be supplied based on a plurality of pieces of information including the first information and the second information.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a boiler. [Background technology]

[0002] Conventionally, there have been boilers equipped with combustion devices that perform multi-position control (high combustion, medium combustion, low combustion, etc.) and proportional control by providing an adjustment valve on a fuel supply line that supplies fuel to a nozzle or other ejection part, and controlling a proportional valve (adjusting valve) in conjunction with the flow rate of combustion air to adjust the fuel flow rate (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-2787 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the boiler described above, the flow rate of fuel is adjusted according to the flow rate of the combustion air supplied. Specifically, an air pressure detection pipe for detecting the pressure of air flowing through the air supply passage is connected to the air supply passage, and the opening of the fuel proportional valve is adjusted based on the pressure of the air transmitted through the air pressure detection pipe to adjust the amount of fuel supplied. In such a boiler, for example, when the air pressure detection pipe or the like breaks down, when the combustion stage transitions, or when there is a transient change in temperature, the amount of fuel supplied is adjusted based on this incorrect flow rate of the combustion air. As a result, the air ratio (the ratio of the combustion air to the fuel) fluctuates, and if no countermeasure is taken, there is a risk of causing combustion abnormalities such as misfires and an increase in carbon monoxide. Even in a boiler that adjusts the flow rate of combustion air according to the flow rate of the fuel supplied, there is a risk of causing similar problems if the flow rate of the fuel actually supplied cannot be detected correctly.

[0005] The present invention has been devised in consideration of the above-mentioned situation, and its purpose is to provide a boiler that can suppress the effects of erroneous detection even in situations where the flow rate of combustion air or fuel actually supplied cannot be correctly detected. [Means for solving the problem]

[0006] In order to achieve the above object, a boiler according to one aspect of the present invention includes a supply means for supplying combustion air or fuel to a boiler body, a first information determination means for detecting a flow rate of the supplied combustion air or a flow rate of the fuel and determining first information corresponding to the detection result, and a second information determination means for determining second information which is a value independent of the detected flow rate of the combustion air or the detected flow rate of the fuel and which may vary depending on an operating state of the boiler. At least one of the boiler combustion rate, the blower frequency rate, and the target flow rate of the combustion air according to the combustion amount is selected as the combustion rate. A second information identification means for identifying the Supplement and a flow rate adjusting means for adjusting the flow rate of the fuel or the combustion air to be supplied. The flow rate adjusting means performs a combustion stage transition, controls the supplying means for supplying combustion air or fuel in a manner corresponding to the combustion stage, and thereafter adjusts the flow rate of fuel to be supplied based on a plurality of pieces of information including the first information and the second information when the first information identified by the first information identifying means is a flow rate of combustion air, and adjusts the flow rate of combustion air to be supplied based on a plurality of pieces of information including the first information and the second information when the first information identified by the first information identifying means is a supply flow rate of fuel. do.

[0007] According to the above configuration, by adjusting the supplied flow rate based on information including not only the first information but also the second information, which is a value independent of the detected flow rate and can vary depending on the operating state of the boiler, even if the first information deviates from the actually supplied flow rate, the supplied flow rate is adjusted based on information including the second information, which is not affected by the first information, thereby suppressing the effects of erroneous detection.

[0009] According to the above configuration, the flow rate to be supplied is adjusted by using, as the second information, more appropriate information according to the operating mode of the boiler.

[0010] Preferably, the second information is detectable by the first information identifying means. Values ​​related to maximum value This information is based on.

[0011] According to the above configuration, the flow rate to be supplied is adjusted by using, as the second information, more appropriate information according to the operating mode of the boiler. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a diagram for explaining a schematic configuration of a boiler. [Diagram 2] 4 is a flowchart illustrating an example of control of a boiler. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] <Overview of the configuration> A boiler 1 according to an embodiment of the present invention will be described below with reference to Fig. 1. Fig. 1 is a diagram showing a schematic configuration of a boiler 1 according to an embodiment of the present invention.

[0014] The boiler 1 includes a boiler body 2 that burns fuel to generate steam, a blower (blower means) 3 that sends air into the boiler body 2 via an air supply passage 30, a flue 4 that guides exhaust gas and the like from the boiler body 2, and a fuel supply line (fuel supply passage) 5 that supplies fuel to the boiler body 2. Note that, although an example in which the fuel is gas will be described, the fuel is not limited to a gas such as gas, and may be a liquid such as oil.

[0015] The fuel supply line 5 is connected to an air supply passage 30. The fuel supplied from the fuel supply line 5 is mixed with air blown from the blower 3 in the air supply passage 30, and is supplied to the burner 20 in the boiler body 2.

[0016] The air supplied from the blower 3 is supplied as combustion air to the burner 20 in the boiler body 2 via the air supply passage 30. The flow rate of the combustion air is adjusted by providing a damper 7 in the air supply passage 30 and adjusting the position (opening) of the damper 7, or alternatively or in addition, by using an inverter to change the rotation speed of the fan of the blower 3. In this embodiment, the flow rate of the combustion air is adjusted by controlling the opening of the damper 7 and the inverter control of the blower 3.

[0017] The fuel supply line 5 is provided with on-off valves (solenoid valves) 11, 12 for opening and closing the flow path, and a fuel supply amount adjustment valve 13. The fuel supply amount adjustment valve 13 functions as a pressure adjustment valve capable of adjusting the flow rate of fuel supplied to the boiler body 2, and also has a shutoff function. The fuel supply amount adjustment valve 13 is provided downstream of the on-off valves 11, 12, and is a motor valve whose opening is adjusted by the control device 6. Note that the fuel supply amount adjustment valve 13 is not limited to a motor valve as long as it adjusts the flow rate of fuel, and may be, for example, an air-type control valve.

[0018] The control device 6 is realized by a computer including an internal memory, a timer, and an arithmetic processing unit, and controls the fuel supply amount adjusting valve 13, the blower 3, and the damper 7 based on signals from each sensor that is electrically connected to it.

[0019] In the air supply passage 30 in this embodiment, a combustion air decompression member 8 such as a punched metal is provided downstream of the damper 7. The air flow detection unit 9 is equipped with a differential pressure sensor that detects the differential pressure before and after the combustion air decompression member 8, and outputs differential pressure information that can identify the detected differential pressure. The air flow detection unit 9 is electrically connected to the control device 6. This allows the differential pressure information from the air flow detection unit 9 to be input to the control device 6. The analog signal output from the air flow detection unit 9 is converted to a digital signal and input to the control device 6.

[0020] The control device 6 controls the combustion stage to one of a plurality of types of combustion stages with different combustion amounts, for example, a low combustion stage L, a medium combustion stage M, or a high combustion stage H. The control device 6 controls the combustion stage according to a set target steam pressure and the steam pressure of the steam header. The control device 6 controls the blower 3 so as to have a configuration (e.g., rotation speed, frequency) according to the controlled combustion stage, and supplies an amount of combustion air according to the combustion stage. The control device 6 calculates (detects) the flow rate of combustion air that will actually be supplied to the boiler body 2, based on the differential pressure information detected by the air flow detection unit 9.

[0021] The control device 6 adjusts the opening of the fuel supply amount adjusting valve 13 based on a plurality of pieces of information including differential pressure information as the first information and specific information as the second information. For example, if the flow rate of the combustion air increases, the opening of the fuel supply amount adjusting valve 13 is increased to increase the flow rate of fuel, whereas if the flow rate of the combustion air decreases, the opening of the fuel supply amount adjusting valve 13 is decreased to decrease the flow rate of fuel. The specific information will be described later.

[0022] The control device 6 includes a control unit 61 and a storage unit 62. The control unit 61 transmits an opening degree specifying signal for specifying an opening degree to the fuel supply amount adjusting valve 13 based on the opening degree adjustment information previously stored in the storage unit 62. As a result, the fuel supply amount adjusting valve 13 is controlled to an opening degree according to the opening degree adjustment information, and can adjust the flow rate of the fuel supplied to the boiler body 2. Note that the opening degree adjustment information may be, for example, a table capable of specifying the opening degree of the fuel supply amount adjusting valve 13 according to the differential pressure information or the like, or may be an arithmetic expression for specifying the opening degree of the fuel supply amount adjusting valve 13 according to the differential pressure information or the like.

[0023] In the case where the opening degree of the fuel supply amount adjustment valve 13 is adjusted based on the differential pressure information without considering the specific information, for example, when the differential pressure before and after the combustion air pressure reducing member 8 is erroneously detected due to a failure of the air flow rate detection unit 9 or the like, or when the air ratio fluctuates greatly in a transient state such as a transition of the combustion stage, and the flow rate of the combustion air actually supplied cannot be detected correctly, the fuel supply amount is adjusted based on the erroneous value (wrong flow rate of the combustion air). As a result, it becomes impossible to supply fuel according to the flow rate of the combustion air actually supplied, which leads to fluctuations in the air ratio and causes combustion abnormalities such as misfires and an increase in carbon monoxide. Therefore, in this embodiment, the opening degree of the fuel supply amount adjustment valve 13 (adjustment of the flow rate of the fuel) is adjusted based on not only the differential pressure information but also a plurality of pieces of information including specific information that is a value independent of the differential pressure (flow rate of the combustion air) detected by the air flow rate detection unit 9 and that may fluctuate depending on the operating state of the boiler 1.

[0024] A specific description will be given. In addition to the opening adjustment information, the storage unit 62 stores various information related to the boiler 1, such as specific information that is a value independent of the pressure difference (flow rate of combustion air) detected by the air flow detection unit 9 and that can vary depending on the operating state of the boiler 1. The specific information in this embodiment is, for example, a value that takes into account a value that can vary depending on the combustion rate of the boiler 1, which is the value of "combustion amount in the current combustion stage / combustion amount in the high combustion stage H", and a value that specifies a larger opening as the opening of the fuel supply amount adjustment valve 13 (a value that increases the fuel supply amount) is determined as the combustion rate becomes higher. Note that, as the specific information, for example, a predetermined table is stored in the storage unit 62, and the specific information can be specified depending on the combustion rate of the boiler 1 by referring to the table, but is not limited to this. It is also possible to store a predetermined arithmetic expression in the storage unit 62, and specify the specific information depending on the combustion rate of the boiler 1 using the arithmetic expression.

[0025] Based on the opening degree adjustment information stored in advance in the storage unit 62, the control unit 61 specifies the opening degree of the fuel supply amount adjustment valve 13 according to a plurality of pieces of information including the differential pressure information from the air flow rate detection unit 9 and the specific information corresponding to the combustion rate among the specific information specified from the table, and transmits an opening degree specification signal for specifying the opening degree to the fuel supply amount adjustment valve 13. Specifically, based on the opening degree adjustment information stored in advance in the storage unit 62, the control unit 61 specifies the opening degree of the fuel supply amount adjustment valve 13 according to a value (for example, the sum of the value of the differential pressure information and the value of the specific information) calculated using the differential pressure information from the air flow rate detection unit 9 and the specific information corresponding to the combustion rate among the specific information stored in advance in the storage unit 62. As a result, the fuel supply amount adjustment valve 13 is controlled to an opening degree corresponding to the differential pressure information and the specific information, and can adjust the flow rate of the fuel supplied to the boiler main body 2. Furthermore, even if the air flow detection unit 9 is unable to correctly detect the flow rate of the combustion air actually being supplied, the specific information is not affected, so the amount and proportion of the change in the fuel flow rate due to the influence of erroneous detection can be mitigated and reduced, and the influence of erroneous detection can be prevented from being significantly affected.

[0026] Furthermore, the specific information may be information (e.g., the product of the maximum pressure constant and the combustion rate) according to a value related to the maximum pressure value (full scale) detectable by the differential pressure sensor provided in the air flow detection unit 9 (e.g., the maximum pressure value, or a value within a range of 95% to 105% of the maximum pressure value, hereinafter also referred to as the maximum pressure constant) in addition to the combustion rate of the boiler 1. This allows the flow rate to be adjusted using more appropriate information according to the operation mode of the boiler as the specific information. As described above, the specific information is preferably information based on both the combustion rate of the boiler 1, which may vary according to the operation mode of the boiler, and the maximum pressure constant, and may be calculated by an appropriate calculation, such as the product of both, or the product of one of them (e.g., the combustion rate of the boiler 1) raised to the nth power (e.g., the square; n may be an integer equal to or greater than 2).

[0027] <Boiler control processing> 2 is a flow chart for explaining an example of boiler control according to the present invention. The control device 6 performs this control at regular intervals (for example, every second), and continues to perform this control while the boiler 1 is in operation.

[0028] In step S01, it is determined whether or not a transition in the combustion stage is necessary based on the detected steam pressure in the steam header and the target steam pressure. If it is not determined in step S01 that a transition in the combustion stage is necessary, the process proceeds to step S04. On the other hand, if it is determined in step S01 that a transition in the combustion stage is necessary, the process proceeds to step S02.

[0029] In step S02, the combustion stage is shifted. In step S03, the blower 3 is controlled in a manner (rotation speed or frequency corresponding to the combustion stage) corresponding to the combustion stage shifted in step S02. In step S04, differential pressure information (flow rate of combustion air) corresponding to the detection result of the air flow detection unit 9 is identified. In step S05, specific information corresponding to the combustion rate of the boiler 1 and the maximum pressure constant of the differential pressure sensor provided in the air flow detection unit 9, regardless of the differential pressure information (flow rate of combustion air), is identified. In step S06, the opening of the fuel supply amount adjustment valve 13 corresponding to the differential pressure information identified in step S04 and the specific information identified in step S05 is identified based on the opening adjustment information, and the flow rate of the fuel to be supplied is adjusted by controlling the opening to the specified opening.

[0030] As described above, in this embodiment, as explained in steps S04 to S06 of FIG. 2, the opening of the fuel supply amount regulating valve 13 is controlled based on a plurality of pieces of information including not only the differential pressure information (flow rate of combustion air) corresponding to the detection result of the air flow detection unit 9 but also specific information which is a value unrelated to the differential pressure information (flow rate of combustion air) and which may vary depending on the operating mode of the boiler, to adjust the supplied flow rate. Therefore, even if the air flow detection unit 9 cannot correctly detect the flow rate of the combustion air actually being supplied, the specific information is not affected, so that the amount and rate at which the fuel flow rate is changed due to the influence of erroneous detection can be mitigated or reduced, and the influence of erroneous detection can be prevented from being significantly affected.

[0031] Furthermore, in this embodiment, as shown in step S04, the second information is information corresponding to (taking into account) the combustion rate of the boiler, regardless of the differential pressure information (air flow rate of the combustion air), so the flow rate supplied is adjusted using more appropriate information corresponding to the operating mode of the boiler as the second information.

[0032] Furthermore, in this embodiment, as shown in step S04, the second information is information corresponding to (taking into account) the maximum pressure constant of the differential pressure sensor provided in the air flow detection unit 9, regardless of the differential pressure information (air flow rate of combustion air), so the flow rate to be supplied is adjusted using more appropriate information corresponding to the operating mode of the boiler as the second information.

[0033] The present invention is not limited to the above-described embodiment, and various modifications and applications are possible. Modifications of the above-described embodiment that can be applied to the present invention will be described below.

[0034] In the above embodiment, the blower 3 is controlled in a manner corresponding to the combustion stage, the air flow rate (combustion air supply flow rate) is determined based on the differential pressure information corresponding to the detection result of the air flow rate detection unit 9 as shown in step S04 of Fig. 2, and specific information corresponding to the combustion rate of the boiler 1 and the maximum pressure constant of the differential pressure sensor provided in the air flow rate detection unit 9, regardless of the differential pressure information (combustion air flow rate), is determined as shown in step S05, and the opening degree (fuel supply flow rate) of the fuel supply amount adjustment valve 13 is controlled based on the differential pressure information and the specific information as shown in step S06, thereby adjusting the air ratio. However, the process for adjusting the air ratio is not limited to this, and for example, the air ratio may be adjusted by controlling the opening degree of the fuel supply amount adjustment valve 13 so that it is an opening degree corresponding to the combustion stage, detecting the actual fuel supply flow rate, and controlling the air flow rate (combustion air supply flow rate, for example, the blower 3) based on the fuel supply flow rate and the specific information. When detecting the actual fuel supply flow rate, for example, orifices or the like may be provided at multiple locations in the fuel supply line 5 to detect differential pressure, and the fuel supply flow rate may be detected based on the differential pressure. In this case, the specific information is not information that specifies the fuel supply flow rate together with differential pressure information, but information that specifies the air flow rate (combustion air supply flow rate) together with differential pressure information. Specifically, the control device 6 controls the opening degree of the damper 7 of the blower 3 or the rotation speed of the blower 3 based on multiple pieces of information including the differential pressure information as the first information and the specific information as the second information. For example, if the fuel flow rate increases, the opening degree of the damper 7 of the blower 3 is increased to increase the air flow rate, while if the fuel flow rate decreases, the opening degree of the damper 7 of the blower 3 is decreased to decrease the air flow rate.

[0035] In the above embodiment, information based on the combustion rate of the boiler 1 and the maximum pressure constant is exemplified as the specific information, which is the second information that can vary depending on the operating mode of the boiler. However, the specific information may be information based on at least one of the combustion rate of the boiler, the frequency rate of the blower 3, the target flow rate of combustion air according to the combustion amount, and the maximum pressure constant.

[0036] For example, the specific information may be information based on the frequency rate of the blower 3 instead of or in addition to the combustion rate of the boiler 1. The frequency rate of the blower 3 is, for example, a value of "current frequency of the blower / frequency of the blower in the high combustion stage H". In this case, the specific information is preferably information based on both the frequency rate of the blower 3, which may vary depending on the operating state of the boiler, and the maximum pressure constant, and may be calculated by an appropriate calculation such as the product of both or the product of one of them (for example, the frequency rate of the blower 3) raised to the power of n (for example, the square; n may be an integer equal to or greater than 2). The specific information may also be information based on a target flow rate of the combustion air according to the combustion amount instead of or in addition to the maximum pressure constant. The target flow rate of the combustion air according to the combustion amount is a flow rate that is a target that is predetermined for each combustion amount. In this case, the specific information is preferably information based on both the combustion rate of the boiler 1 and the target flow rate of the combustion air corresponding to the amount of combustion, for example, as values ​​that can vary depending on the operating mode of the boiler, and may be calculated by an appropriate calculation such as the product of both, or the product of one of them (for example, the target flow rate of the combustion air) raised to the nth power (for example, the square; n may be an integer equal to or greater than 2).The larger the frequency rate of the blower or the target flow rate of the combustion air corresponding to the amount of combustion, the larger the opening degree of the fuel supply amount adjustment valve 13 is set to a value (a value that increases the amount of fuel supply).

[0037] In the above embodiment, the opening degree of the fuel supply amount adjustment valve 13 is specified according to the differential pressure information according to the detection result of the air flow rate detection unit 9 and the specific information not related to the differential pressure information, but the specified opening degree may be corrected by the control device 6 as needed according to the use environment and situation during the operation state. The control device 6 may, for example, detect the oxygen concentration of the exhaust gas as needed, and adjust the opening degree of the fuel supply amount adjustment valve 13 specified according to the differential pressure information and the specific information based on the detected oxygen concentration of the exhaust gas and a predetermined reference oxygen concentration, for example, so that when the oxygen concentration of the exhaust gas>the reference oxygen concentration, the fuel supply amount is high and the fuel supply amount is increased, and when the oxygen concentration of the exhaust gas<the reference oxygen concentration, the fuel supply amount is low and the fuel supply amount is decreased. Alternatively or in addition to this, the control device 6 may adjust the opening degree of the fuel supply amount adjustment valve 13 specified according to the differential pressure information and the specific information, for example, according to the temperature of the fuel, the temperature of the combustion air, etc. In addition, when the opening of fuel supply amount adjustment valve 13 is controlled to be an opening according to the combustion stage, the actual fuel supply flow rate is detected, and the air flow rate is controlled based on the fuel supply flow rate and the specific information, the opening of damper 7 of blower 3 or the rotation speed of blower 3 specified according to the differential pressure information (fuel supply flow rate) and the specific information may be corrected by control device 6 as needed according to the usage environment, situation, etc. during operation.

[0038] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0039] 1. Boiler 2 Boiler body 3 Blower (blowing means) 4 Flue 5 Fuel supply line (fuel supply passage) 6. Control device 61 Control section 62 Storage section 7 Damper 8 Combustion air pressure reducing member 9 Air flow rate detection unit (flow rate detection means) 11. On-off valve 12. On-off valve 13 Fuel supply adjustment valve 20 Burner 30 Air supply line

Claims

1. A supply means for supplying combustion air or fuel to the boiler body; a first information determination means for detecting a flow rate of the combustion air or a flow rate of the fuel to be supplied and determining first information corresponding to the detection result; a second information specifying means for specifying at least one of a combustion rate of the boiler, a frequency rate of the blower, and a target flow rate of the combustion air according to a combustion amount as second information that is a value unrelated to the detected flow rate of the combustion air or the detected flow rate of the fuel and that may vary according to an operating mode of the boiler; a flow rate adjusting means for adjusting the flow rate of the fuel to be supplied or the flow rate of the combustion air to be supplied, The flow rate adjusting means is A boiler that performs a combustion stage transition, controls the supply means that supplies combustion air or fuel in a manner corresponding to the combustion stage, and then, if the first information identified by the first information identification means is a combustion air flow rate, adjusts the flow rate of fuel to be supplied based on a plurality of information including the first information and the second information, and if the first information identified by the first information identification means is a fuel supply flow rate, adjusts the flow rate of combustion air to be supplied based on a plurality of information including the first information and the second information.

2. The boiler according to claim 1 , wherein the second information is information based on a value related to a maximum value that can be detected by the first information identifying means.

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