JP2006349312A - Safety confirmation method and combustion system for combustion facility - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a safety confirmation method capable of acquiring exactly respective operation functions of an air supply system and a fuel gas supply system respectively to confirm safety, in advance to ignition of a combustion facility. <P>SOLUTION: When conducting purge treatment in advance to the ignition of the combustion facility, and when inspecting respectively the respective operation functions of a controller such as a damper and a flow regulating valve provided respectively in the air supply system and the fuel gas supply system to a combustor, during the purge treatment, a fuel gas cut-off valve provided in the fuel gas supply system is opened only for a short time just before starting the purge treatment, or concurrently with the start of the purge treatment, respective flow rates of air and fuel gas supplied respectively to the combustor therein are detected by flowmeters provided respectively in the air supply system and the fuel gas supply system, and normalities of the respective supply systems are inspected respectively based on the flow rates (air flow rate and gas flow rate). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a combustion suitable for confirming the operation function of the air supply system and the fuel gas supply system before supplying the air and the fuel gas to the combustor incorporated in the combustion facility and combusting the fuel gas. The present invention relates to a facility safety confirmation method and a combustion system having a safety confirmation function.

  When fuel gas and air are supplied to a combustor (for example, a gas burner) incorporated in a combustion facility such as a boiler to burn the fuel gas, the inside of the combustion facility and the smoke exhausting facility are pre-purged prior to ignition. It is important to ensure the safety. Incidentally, if fuel gas remains in the combustion facility, abnormal combustion (for example, explosion) may occur when the combustor is ignited. Further, even when pre-purge is insufficient due to an insufficient air volume, abnormal combustion may occur during ignition.

  Therefore, conventionally, during the pre-purge, the normality of the pre-purge function is confirmed by checking whether or not the minimum air volume necessary for the pre-purge is secured from the wind pressure. Also, whether or not the air flow regulator (air flow adjustment damper) provided in the air supply system can operate normally using this pre-purge period, that is, the damper operates normally between the maximum opening and the minimum opening. Checking whether or not to do so. At the same time, with respect to the gas flow rate regulator (flow rate regulation damper) mechanically linked to the air volume regulator, an operation check is performed to determine whether or not the damper can operate normally.

  After confirming that the pre-purge function operates normally and that the air flow adjustment damper and gas flow rate (gas supply amount) adjustment damper provided in the air supply system and fuel gas supply system operate normally (safety check) ), The supply of combustion gas is started after the completion of the pre-purge, and combustion is started by igniting the combustor (burner).

  However, the control system of the combustion system configured by mechanically linking the gas flow rate control damper and the air volume adjustment damper is mechanically complicated, and it cannot be denied that it takes time to confirm the mechanical operation. Therefore, it is strongly desired to make it possible to individually control the gas flow rate control damper and the air volume adjustment damper and to simplify the configuration. However, in that case, it becomes a big problem how to check the safety of the combustion system including the operation check of each damper.

The present invention has been made in view of such circumstances, and its purpose is to supply air and fuel gas to a combustor incorporated in a combustion facility and burn the fuel gas before the air is supplied. It is an object of the present invention to provide a combustion facility safety confirmation method capable of accurately grasping each operation function of the fuel system and the fuel gas supply system and confirming safety.
Another object of the present invention is to provide the above-described safety confirmation function, which is simple and practical for performing combustion control safely and accurately depending on the operating function states of the air supply system and the fuel gas supply system. An object of the present invention is to provide a combustion system having a high configuration.

  In order to achieve the above-described object, the safety confirmation method and combustion system for a combustion facility according to the present invention, when pre-purging the combustion facility and its smoke exhaust facility, instantaneously generates a small amount of fuel gas via the fuel gas supply system. Supplying to the combustion facility has almost no effect on the pre-purge of the combustion facility, and if the flow rate of the fuel gas supplied at this time is detected, the operating characteristics of the fuel gas supply system (gas flow rate control function, etc.) It is made paying attention to what can be grasped.

In view of this, the safety confirmation method for a combustion facility according to the present invention provides a method for confirming the inside of the combustion facility and its smoke exhausting device before supplying the air and the fuel gas to the combustor incorporated in the combustion facility and combusting the fuel gas. When purging the inside, and inspecting each operation function of a controller such as a damper and a flow rate adjusting valve respectively provided in the air supply system and the fuel gas supply system to the combustor during the purge process,
The fuel gas shut-off valve provided in the fuel gas supply system is opened for a short time immediately before the start of the purge process or simultaneously with the start of the purge process, and the air and the fuel gas respectively supplied to the combustor at this time Each flow rate is detected by a flow meter provided in each of the air supply system and the fuel gas supply system, and the normality of each supply system is inspected from the flow rates (air volume and gas flow rate).

  Specifically, as described in claim 2, the controller provided in the air supply system is an air volume regulator (for example, an air volume adjustment damper), and the controller provided in the fuel gas supply system is the fuel. It is preferable to use a thermal microflow sensor as a flow meter including a gas shut-off valve and a gas flow regulator (for example, a flow regulating valve or a flow regulating damper) and provided in each of the supply systems. According to a third aspect of the present invention, the maximum flow rate and / or the minimum flow rate when the fuel gas shut-off valve provided in the fuel gas supply system is opened for a short time is obtained by using each flow meter. It ’s fine. At this time, it is also useful to obtain a time constant (response characteristic) of the flow rate change.

A combustion system according to the present invention includes a combustor incorporated in a combustion facility, an air supply system that supplies air to the combustor, and a fuel that supplies fuel gas to the combustor. A gas supply system,
In particular, a flow meter that is incorporated in the air supply system and the fuel gas supply system, respectively, and detects each flow rate of air and fuel gas, and
When purging the inside of the combustion facility and the smoke exhausting facility, at least immediately before the purge process or simultaneously with the start of the purge process, the fuel gas shut-off valve provided in the fuel gas supply system is opened for a short time, and this And safety confirmation means for detecting the flow rates of air and fuel gas supplied to the combustor from time to time by the flow meters and checking the normality of the supply systems, respectively. .

  Preferably, the flow meter provided in each of the supply systems includes a thermal microflow sensor. Further, according to a sixth aspect of the present invention, the safety check means checks each operation function of a plurality of controllers incorporated in each supply system after checking the normality of each supply system. It is preferable to realize the function.

  According to the safety check method for combustion equipment described above, the fuel gas shut-off valve provided in the fuel gas supply system is opened for a short time (for example, about 1 second) immediately before the start of the purge process or simultaneously with the start of the purge process. At this time, if the flow rate of the fuel gas to the combustor is detected by a flow meter provided in the fuel gas supply system, the supply amount of the fuel gas (gas flow rate) supplied through the fuel gas supply system thereby Can be detected. In particular, the shut-off characteristics and maximum gas supply amount can be determined from the gas flow rate when the fuel gas supply system is closed (fully closed) and the gas flow rate when the fuel gas supply system is opened (fully open). The control characteristic of the controller (for example, a shut-off valve) of the fuel gas supply system can be grasped from the change characteristic of the flow rate (change time constant).

  As for the amount of air supplied to the combustor via the air supply system, since the rise of the air supply source such as a blow motor is slow, a flow meter provided in the air supply system is used during the purge processing execution period. Detection is sufficient. Thus, if the air volume detected using the flow meter provided in the air supply system is detected, it can be accurately determined whether or not the pre-purge function works normally from the air volume. Further, as described above, from the maximum gas supply amount (gas flow rate) detected using the flow meter provided in the fuel gas supply system, for example, the shutoff characteristic at the shutoff valve for the fuel gas supply is accurately grasped, and further It is possible to confirm the normality by performing failure prediction for the slow operation of the shutoff valve caused by rubbing or the like. As a result, it is determined whether or not each operation function of the air supply system and the fuel gas supply system is normal without adopting a configuration in which the air volume adjustment mechanism and the gas flow rate adjustment mechanism are mechanically linked. Safety confirmation can be performed effectively. In particular, the air volume and gas flow rate can be detected directly to check the functions of the blower (blower motor), air volume adjustment damper, fuel shut-off valve, fuel supply volume control valve, etc. Reliability can be made sufficiently high.

  Further, according to the combustion system of the present invention, each of the air supply system and the fuel gas supply system is provided with a flow meter, and the fuel gas is instantaneously supplied just before or simultaneously with the pre-purge. Since the operation function of the fuel gas supply system can be confirmed from the detected gas flow rate, combined with the normality of the pre-barge function confirmed from the air volume detected by the flow meter provided in the air supply system, The operational safety of the combustion facility can be confirmed with high reliability.

  In particular, if a thermal micro flow meter is used as a flow meter, its operation response is high (fast), so the operation function of the fuel gas supply system can be confirmed in a short time by supplying a small amount of fuel gas instantaneously. be able to. In addition, the thermal microflow meter is small in size and can be easily incorporated into existing combustion equipment, so its practical advantage is very high. Furthermore, it is also possible to feed back the air volume and gas flow detected by a flow meter (thermal micro flow meter) and use them as combustion control information, so that the configuration of the combustion system can be greatly simplified. Played.

Hereinafter, a combustion system according to an embodiment of the present invention and a combustion facility safety confirmation method applied to the combustion system will be described with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a combustion system according to this embodiment. 1 is a gas burner (main burner) as a combustor incorporated in combustion equipment such as a boiler, 2 is a pilot burner, and 3 is a blower (blower motor). ). Further, 4 is a control device (controller) for executing combustion control and safety confirmation processing, and 5 is a flame detector. Incidentally, the gas burner 1 and the pilot burner 2 are each supplied with air A from the blower 3 through the air supply system 10, and the gas burner 1 and the pilot burner 2 are supplied with the first and second air burners. The fuel gas G is supplied through the fuel gas supply systems 20 and 30, respectively.

  The air supply system 10 is provided with a pressure gauge 11 and a pressure switch 12 for detecting the wind pressure of the air supplied through the air supply system 10, and is inserted in series in the supply path to provide an air volume adjusting damper. (Butterfly valve with control motor) 13 is provided. The pressure switch 12 is for detecting a lower limit value that is turned off when the pressure (wind pressure) of the air A sent out from the blower 3 is equal to or lower than a preset pressure. A pressure gauge 21 and a pressure switch 22 for detecting the pressure (supply pressure) of the fuel gas G supplied from a fuel gas source (not shown) are provided upstream of the first and second fuel gas supply systems 20 and 30. It has been. The pressure switch 22 is also configured for detecting a lower limit value that is turned off when the supply pressure of the fuel gas G is equal to or lower than a preset pressure.

  The first fuel gas supply system 20 that supplies the fuel gas G to the gas burner (main burner) 1 is inserted with safety shut-off valves 23 and 24 in series over two stages. A pressure regulator (governor) 25 and a flow rate adjustment damper (butterfly valve with control motor) 26 are sequentially inserted in series at the downstream side of 23 and 24. A pressure gauge 27 and a pressure switch 28 are provided in a flow path (fuel gas pipe line) between the pressure regulator (governor) 25 and the flow rate adjusting damper 26. The pressure switch 28 is for detecting an upper limit value that is turned on when the pressure of the fuel gas G is equal to or higher than a preset pressure.

  Similarly to the first fuel gas supply system 20, safety shutoff valves 33 and 34 are inserted in series in the second fuel gas supply system 30 that supplies the fuel gas G to the pilot burner 2. A pressure regulator (zero governor) 35 is inserted in series at the downstream side of these safety shut-off valves 33 and 34. In the figure, reference numeral 36 denotes a venturi mixer which is provided in the front stage of the pilot burner 2 and premixes fuel gas and air.

  In the combustion system according to this embodiment in addition to the air volume and fuel gas amount adjusting mechanism, the gas burner (main burner) 1 is supplied to the downstream side of the air supply system 10 via the air supply system 10. A flow meter for detecting the flow rate (air volume) of the air A, specifically, a thermal micro flow meter 14 is provided. The first and second fuel gas supply systems 20 and 30 also have a flow rate (gas supply amount) of the fuel gas G supplied to the gas burner 1 and the pilot burner 2 through the fuel gas supply systems 20 and 30, respectively. ) Are respectively provided for detection of flow meters (thermal micro flow meters) 29 and 37.

  These thermal microflow meters 14, 29, and 37 are, for example, a pair of temperature sensors (temperature sensitive resistors) with a heating element Rh sandwiched on a semiconductor substrate as disclosed in Japanese Patent Application Laid-Open No. 2004-170113. By providing Ru and Rd, the change in temperature distribution caused by the fluid flowing along the surface of the semiconductor substrate is regarded as the temperature difference along the fluid flow detected by the temperature sensors Ru and Rd, thereby allowing the flow of the fluid. The direction and the mass flow rate are obtained. Incidentally, the response speed of this type of microflow sensor is as high as about 20 milliseconds, for example. Accordingly, even if the safety gas shutoff valves 23 and 24 of the first fuel gas supply system 20 are opened and closed for about 1 second from the fully closed state to the fully open state and further to the fully closed state, Accordingly, the flow rate of the fuel gas G flowing through the first fuel gas supply system 20 can be reliably detected. Moreover, it is possible to monitor the change of the flow rate and the operational response characteristics of the safety shut-off valves 23 and 24 by monitoring the change of the flow rate every moment.

  For example, the control device (controller) 4 constituted by a microprocessor is basically used for the above-described operation of the blower 11, opening / closing control of the safety shut-off valves 23, 24, and flow rate adjustment based on a command from a console (not shown). Control of the gas supply amount in the damper 26 and ignition / digestion control of the gas burner (main burner) 1 and the pilot burner 2 are executed to control the combustion in the combustion facility. In particular, when the combustion instruction by the gas burner 1 is given, the control device 4 keeps the safety shut-off valves 23, 24, etc. in a fully closed state before the gas burner 1 is ignited and shuts off the supply of the fuel gas G. 3 is operated, and the inside of the combustion equipment (combustion chamber) in which the gas burner 1 is provided and the function of pre-purging the inside of the flue equipment are provided. Note that this pre-purge may be performed in combination with a flue gas facility (not shown) incorporated in the flue facility.

  Then, the control device 4 makes use of the period required for the pre-purge process, for example, confirms whether or not the air volume adjusting damper (butterfly valve with control motor) 13 operates normally, and also controls the flow rate adjusting damper ( Confirm the operation of the controller (damper, etc.) incorporated in each of the air supply system 10 and the fuel gas supply systems 20 and 30, such as confirming whether or not the butterfly valve with control motor 26 operates normally. Execute.

  Particularly in this combustion control system, the control device 4 changes the safety shut-off valves 23 and 24 in the first fuel gas supply system 20 from a fully closed state to a fully opened state immediately before executing pre-purge or simultaneously with the start of pre-purge. Further, the fuel gas G is instantaneously supplied to the gas burner 1 by opening and closing for about one second from the fully open state to the fully closed state. Simultaneously with the opening / closing control of the safety shut-off valves 23, 24, the safety shut-off valves 33, 34 in the second fuel gas supply system 30 are similarly opened / closed, whereby the fuel gas G is instantaneously supplied to the pilot burner 2. It has become. At this time, the flow rates of the fuel gas G flowing in the first and second fuel gas supply systems 20 and 30 are detected by the flow meters (thermal micro flow meters) 29 and 37, respectively, and the detected gas is detected. The operation function of the safety shut-off valves 23, 24, 33, 34 is confirmed from the flow rate.

  Specifically, the control device 4 obtains the minimum flow rate and the maximum flow rate when the safety shut-off valves 23, 24, 33, and 34 are opened and closed instantaneously, and examines the change characteristics of the flow rates. Then, the fuel gas supply is surely shut off when the minimum flow rate is zero (0), and whether the maximum flow rate is the maximum gas supply amount required for each of the gas burner 1 and the pilot burner 2 is confirmed. Thus, it is confirmed whether or not the safety shut-off valves 23, 24, 33, and 34 operate normally. Furthermore, from the above flow rate change characteristics, that is, the time lapse (time constant) until the gas flow rate changes from the minimum flow rate to the maximum flow rate, and the time lapse (time constant) until the gas flow rate changes from the maximum flow rate to the minimum flow rate. The operation response characteristics of the safety shut-off valves 23, 24, 33, and 34 are obtained. Thereafter, the control device 4 uses the pre-purge process execution period to confirm the operation of whether or not the flow rate adjusting damper (butterfly valve with control motor) 26 operates normally, as described above. Yes.

  That is, FIG. 2 shows a schematic control flow for confirming the operational safety of the air supply system 10 and the fuel gas supply systems 20 and 30 in the combustion system, and FIG. 3 shows a schematic timing chart of the control operation. Thus, in the control device 4, when the combustion start instruction is given, the blower motor (blower) 3 is first started [step S1]. Then, after the operation of the blower motor 3, before the start of the pre-purge or simultaneously with the start of the pre-purge, the supply amount (gas flow rate) of the fuel gas G supplied through the combustion gas supply systems 20 and 30 is checked [Step S2 ]. As described above, the fuel gas supply amount (gas flow rate) is checked by opening and closing the safety shut-off valves 23, 24, 33, and 34 instantaneously [Step S2a], thereby detecting the flow rate of gas flowing through [Step S2a]. S2b], it is confirmed whether or not the safety shut-off valves 23, 24, 33, and 34 are normally opened and closed to reliably exhibit the fuel gas G supply shut-off function [step S2c].

  When the pre-purge is started [step S3], first, the supply amount (air volume) of the air A supplied via the air supply system 10 is checked to confirm the function of the blower motor 3, and thus the normality of the pre-purge function [ Step S4]. Until the pre-purge process is completed [step S5], each controller such as the above-described flow rate adjusting damper 26 incorporated in the air supply system 10 and the fuel gas supply systems 20 and 30, respectively, using this pre-purge period. Each operation is confirmed [step S6]. The operation of the flow adjusting damper 26 and the like is confirmed by examining whether or not the damper valve is variably controlled from the minimum opening to the maximum opening by operating the drive motor. After the normality of the operation of each controller is confirmed, the burner 1 is ignited and combustion control is executed [step S6]. For this combustion control, it is sufficient to use a control method proposed in, for example, Japanese Patent Laid-Open No. 10-19253. Further, at this time, as disclosed in, for example, Japanese Patent Laid-Open No. 10-19253, the function of the flow meters 29 and 34 themselves is self-diagnosed by monitoring the relationship between the valve opening degree and the detected gas flow rate, and the normality thereof. It is also useful to confirm.

  Thus, according to the combustion system configured as described above, the safety shut-off valves 23, 24, 33, 34 are opened for a short time immediately before the pre-purge or simultaneously with the start of the pre-purge, and the fuel gas G is supplied to the fuel gas supply systems 20, 30. , And the flow rate of the fuel gas G at this time is detected by flow meters 29 and 37 provided in the fuel gas supply systems 20 and 30, respectively, so that the fuel gas supply system 20 and 30 operational safety can be confirmed. Therefore, it is possible to reliably and accurately check the operational safety prior to the start of combustion without adopting a configuration in which the gas flow rate control damper and the air volume adjustment damper are mechanically linked as in the prior art. For this reason, effects such as significant simplification of the configuration of the combustion system can be achieved.

  Further, as described above, even if the fuel gas G is supplied just for a short time immediately before the pre-purge or simultaneously with the start of the pre-purge, the minute amount of the fuel gas G is exhausted by the pre-purge. There is no risk of danger. In addition, since a small amount of fuel gas G is actually allowed to flow through the fuel gas supply systems 20 and 30 for a very short time, the operation can be confirmed directly, so that a highly reliable safety check can be performed. Can have effects you can't expect at all. In particular, it is possible to easily detect a state where the flow of the fuel gas G is deteriorated due to a flow path failure or the like, and it is possible to predict the occurrence of a failure.

  As described above, if the air supply system 10 and the fuel gas supply systems 20 and 30 are respectively incorporated with the flow meters 14, 29 and 37 to detect the air amount (air amount) and the gas supply amount, respectively, the detection is performed. Using the result, it is possible to stably perform combustion control in which the amount of air and the amount of gas after ignition are proportionally controlled. If the detection data obtained at the time of the safety confirmation operation at the start of ignition (ignition) is totaled, it becomes possible to monitor the supply pressure fluctuation of the fuel gas G supplied from the fuel gas source, and this information is used for combustion control. It is possible to use it as calibration data for the above. Furthermore, since each of the plurality of fuel gas supply systems can be individually confirmed for safety, it can be easily applied to the safety confirmation of a combustion system including a plurality of main burners.

  The present invention is not limited to the embodiment described above. For example, it is possible to use a flow meter other than a thermal micro flow meter. However, since the fuel gas G is allowed to flow for only a short time, the maximum flow rate and the minimum flow rate can be measured in that time. It is desirable to use a high-speed type. In addition to the control valve linkage type combustion facility exemplified as the embodiment, the Bunsen burner type combustion facility, the venturi type combustion facility, and the pressure equalizing valve type as shown in FIGS. 4 (a), (b) and (c), respectively. The same applies to combustion equipment. In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

1 is a schematic configuration diagram of a combustion system according to an embodiment of the present invention. The figure which shows the rough process sequence of the safety confirmation method of the combustion installation implemented by applying to the combustion system shown in FIG. The timing diagram which shows specific embodiment of the safety confirmation method of the combustion equipment shown in FIG. The figure which shows the example of the other combustion equipment which can apply this invention.

Explanation of symbols

1 Main burner 2 Pilot burner 3 Blower (blower motor)
4 Controller (Controller)
5 Flame detector 10 Air supply system 20 First fuel gas supply system (for main burner)
30 Second fuel gas supply system (for pilot burner)
13,26 Damper for flow adjustment 23,24,33,34 Safety shut-off valve 14,29,37 Flow meter (micro flow meter)

Claims (6)

Prior to supplying air and fuel gas to a combustor incorporated in a combustion facility to burn the fuel gas, the inside of the combustion facility and the inside of the flue gas facility are purged. When inspecting each operation function of the controller respectively provided in the air supply system and the fuel gas supply system to the combustor,
The fuel gas shut-off valve provided in the fuel gas supply system is opened for a short time immediately before the start of the purge process or simultaneously with the start of the purge process, and the air and the fuel gas respectively supplied to the combustor at this time A method for confirming safety of a combustion facility, wherein each flow rate is detected by a flow meter provided in each of the air supply system and the fuel gas supply system, and the normality of each supply system is checked. The controller provided in the air supply system is an air flow regulator, and the controller provided in the fuel gas supply system includes the fuel gas cutoff valve and a gas flow rate regulator,
The method for confirming safety of a combustion facility according to claim 1, wherein the flow meters provided in the respective supply systems are each composed of a thermal microflow sensor.   2. The combustion facility safety check according to claim 1, wherein each of the flow meters obtains a maximum flow rate and / or a minimum flow rate when a fuel gas shut-off valve provided in the fuel gas supply system is opened for only a short time. Method. A combustion system comprising a combustor incorporated in a combustion facility, an air supply system for supplying air to the combustor, and a fuel gas supply system for supplying fuel gas to the combustor,
A flow meter that is incorporated in the air supply system and the fuel gas supply system, respectively, and detects each flow rate of air and fuel gas;
When purging the inside of the combustion facility and the smoke exhausting facility, at least immediately before the purge process or simultaneously with the start of the purge process, the fuel gas shut-off valve provided in the fuel gas supply system is opened for a short time, and this And safety confirmation means for detecting the flow rates of air and fuel gas supplied to the combustor from time to time by the flow meters and checking the normality of the supply systems, respectively. Combustion system.   The combustion system according to claim 4, wherein each of the flow meters provided in each of the supply systems includes a thermal microflow sensor.   The safety check means includes an operation check function for checking each operation function of a plurality of controllers incorporated in each supply system after checking the normality of each supply system. 5. The combustion system according to 4.

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