JP2016020794A - Boiler system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boiler system capable of maintaining an air ratio in a permissible range by regulating the degree of opening of a flow regulating valve even if a variation in the air ratio falls in an impermissible range.SOLUTION: A boiler system 1 comprises: a control-valve setting unit 91 setting a value of a degree of opening corresponding to a flow volume of combustion air detected by an air differential pressure sensor 33; a range determination unit 96 determining whether a measurement value detected by an Osensor 81 falls in a predetermined concentration range; a correction-value setting unit 97 setting a correction value on the basis of the measurement value determined not to fall in the predetermined concentration range by the range determination unit 96; a flow control unit 99 controlling a flow regulating valve 56 on the basis of the value of the degree of opening, and controlling the flow regulating valve 56 on the basis of a control value to which the correction value is added if the correction value is set; and a correction-value update unit 98 updating the correction value on the basis of the measurement value if the range determination unit 96 determines that the measurement value does not fall in the predetermined concentration range in a state of setting the correction value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a boiler device. More specifically, the present invention relates to a boiler device that controls a flow rate adjustment valve of a fuel supply line so that fuel gas corresponding to the supply amount of combustion air is supplied.

  2. Description of the Related Art Conventionally, there has been known a boiler apparatus that generates steam by burning water-fuel mixture obtained by mixing fuel gas and combustion air at a predetermined ratio to heat water. In this type of boiler device, the flow rate of the fuel gas is adjusted by a flow rate adjustment valve in accordance with the supply amount of combustion air so that the air ratio, which is the ratio between the theoretical air amount and the air amount supplied to the boiler, is constant. It is adjusted. For example, Japanese Patent Application Laid-Open No. H10-228707 discloses such control that keeps the air ratio constant. Patent Document 1 discloses a fuel gas amount control device for a premixed gas burner that adjusts a fuel gas control valve in accordance with fluctuations in the amount of combustion air supplied to make the air ratio constant.

JP-A-11-108352

  By the way, LNG (Liquid Natural Gas) is widely spread as a fuel gas due to the increase in environmental awareness. One method of supplying LNG is so-called LNG satellite supply in which LNG is transported in a liquid state and vaporized at a supply destination that uses LNG. Although LNG satellite supply can reduce the introduction cost and is used in various fields, the fuel gas tends to be more susceptible to the external environment than the method of transporting the fuel gas through the pipeline. .

  When the flow rate of the fuel gas supplied to the boiler device fluctuates due to the external environment or the like, the air ratio may deviate from a predetermined range. For example, if the mass flow rate fluctuates due to temperature fluctuations or pressure fluctuations, or the amount of heat of the fuel gas changes due to component fluctuations that occur in the process of vaporizing LNG, the amount of air required for combustion (theoretical air amount) Changes, the air ratio fluctuates, which may cause a reduction in combustion efficiency and incomplete combustion. On the other hand, when the fluctuation of the air ratio occurs within the allowable range of the boiler device, it is not necessary to adjust the air ratio. Since the conventional boiler apparatus controls the flow rate adjustment valve based on the opening degree set according to the flow rate of the combustion air, it is difficult to say that the fluctuation of the air ratio is sufficiently considered. There was room for improvement in how to deal with fluctuations in the range that was unacceptable.

  An object of this invention is to provide the boiler apparatus which can maintain an air ratio in the range which can be accept | permitted by adjustment of the opening degree of a flow regulating valve, even when the fluctuation | variation of an air ratio becomes an unacceptable range.

  The present invention includes a boiler, a fuel supply line that supplies fuel gas to the boiler, a flow rate adjustment valve that is disposed in the fuel supply line and that can adjust the flow rate of the fuel gas, and the boiler is mixed with the fuel gas An air supply line for supplying combustion air, an air flow rate detection unit for detecting a flow rate of the combustion air flowing through the air supply line, an air ratio detection unit for detecting an air ratio, and the air flow rate detection unit A control value setting unit that sets a control value corresponding to the detected flow rate of the combustion air, and a range determination unit that determines whether or not the measurement value detected by the air ratio detection unit is in the first range. A correction value setting unit that sets a correction value based on the measured value that is determined not to be in the first range by the range determination unit, and controls the flow rate adjustment valve based on the control value, and the correction value But A flow rate control unit that controls the flow rate adjustment valve based on the control value to which the correction value is added, and the range determination unit in a state in which the correction value is set, When it determines with it not being in 1 range, it is related with a boiler apparatus provided with the correction value update part which updates the said correction value based on the said measured value.

  The boiler device further includes an exhaust gas exhaust unit that exhausts exhaust gas generated by the combustion of the fuel gas from the boiler, and the air ratio detection unit is disposed in the exhaust gas exhaust unit and detects oxygen concentration of the exhaust gas It is preferable that it is a density | concentration detection part.

  Preferably, the air ratio detection unit is disposed in the fuel supply line and detects a change in mass flow rate of the fuel gas.

  It is preferable that the air ratio detection unit is a heat amount detection unit that is disposed in the fuel supply line and detects the heat amount of the fuel gas.

  According to the boiler device of the present invention, even when the fluctuation of the air ratio is in an unacceptable range, the air ratio can be maintained in an allowable range by adjusting the opening of the flow rate adjusting valve.

It is a figure showing typically one embodiment of the boiler device of the present invention. It is a graph which shows the relationship between the mass flow rate of fuel gas, and the oxygen concentration in waste gas. It is a block diagram which shows the structure of the control part of 1st Embodiment. It is a flowchart which shows the process which controls the opening degree of the flow regulating valve of 1st Embodiment. It is a figure which shows typically the boiler apparatus of 3rd Embodiment.

  Hereinafter, preferred embodiments of the boiler device of the present invention will be described with reference to the drawings. The boiler apparatus 1 of 1st Embodiment is a steam boiler which heats water and produces | generates a vapor | steam, and supplies a vapor | steam to load equipment (illustration omitted). The “line” in the present specification is a general term for lines capable of flowing a fluid such as a flow path, a path, and a pipeline.

  As shown in FIG. 1, the boiler device 1 includes a boiler 2, a blower 20 that sends combustion air to the boiler 2, and an air supply line that connects the boiler 2 and the blower 20 and flows through the combustion air. Duct 30, damper 31 disposed in air supply duct 30, punching metal 32 as a combustion air decompression member, air differential pressure sensor 33 as an air flow rate detection unit, and combustion gas discharged from boiler 2 ( An exhaust pipe 80 serving as an exhaust gas discharge portion through which exhaust gas) circulates, a fuel supply unit 50 that supplies fuel gas to the boiler 2, a water supply passage (not shown) that supplies water to the boiler 2, fuel gas, and combustion air And a control device 70 for controlling the supply amount and the like.

  The boiler 2 is configured by a can body 10, and the can body 10 includes a boiler housing 11, a plurality of water pipes 12, a lower header 13, an upper header 14, and a burner 15.

  The boiler housing | casing 11 comprises the external shape of the can 10, and is formed in the rectangular parallelepiped shape of planar view. An air supply port 16 is formed in the first side surface 11a located on one end side in the longitudinal direction of the boiler casing 11, and a second side surface 11b located on the other end side in the longitudinal direction of the boiler casing 11 is An exhaust port 17 is formed.

  The plurality of water pipes 12 are disposed so as to extend in the vertical direction inside the boiler housing 11 and are disposed at predetermined intervals in the longitudinal direction and the width direction of the boiler housing 11.

  The lower header 13 is disposed at the lower part of the boiler casing 11. The lower header 13 is connected to the lower ends of the plurality of water pipes 12. The upper header 14 is disposed on the upper portion of the boiler casing 11. The upper header 14 is connected to the upper ends of the plurality of water pipes 12.

  The burner 15 is disposed in the air supply port 16. The mixture of fuel gas and combustion air is burned by the burner 15, and the water in the water pipe 12 is heated to generate steam.

  The blower 20 includes a blower body 21 having a fan and a motor that rotates the fan, and an inverter 22 that increases or decreases the number of rotations of the fan (motor). The blower 20 feeds combustion air into the can body 10 when the fan rotates at a predetermined rotation speed in accordance with the frequency input to the inverter 22.

  In the present embodiment, the flow rate of the combustion air is set according to a required load required from a load device (not shown). The blower 20 is controlled by the control device 70 via the inverter 22 so that the flow rate of the fuel air is set.

  The air supply duct 30 is an air supply line that supplies combustion air to be mixed with fuel gas into the boiler 2. The air supply duct 30 has an upstream end connected to the blower 20 and a downstream end connected to the air supply port 16. The air supply duct 30 supplies the combustion air sent from the blower 20 to the can body 10.

  The damper 31 is in a closed state in which the combustion air flow path inside the air supply duct 30 is closed and rotated 90 degrees from this closed state to open the combustion air flow path in the air supply duct 30. It is arranged to be rotatable between states.

  The punching metal 32 is a metal plate in which a plurality of through holes are formed, and is a combustion air pressure-reducing member that depressurizes the combustion air that circulates. The punching metal 32 is disposed on the downstream side of the damper 31 inside the air supply duct 30. The punching metal 32 decompresses the combustion air flowing through the damper 31 to the air supply duct 30.

  The air differential pressure sensor 33 is an air flow rate detection unit for detecting the flow rate of combustion air. The air differential pressure sensor 33 detects a differential pressure between the upstream pressure and the downstream pressure of the punching metal 32. The flow rate of the fuel air is calculated based on this differential pressure information. Further, the air differential pressure sensor 33 is electrically connected to the control device 70, and the control device 70 acquires air differential pressure information detected by the air differential pressure sensor 33.

  The exhaust cylinder 80 is connected to the can body 10 (exhaust port 17 formed in the boiler casing 11) on the base end side, and is formed in a cylindrical shape. Combustion gas (exhaust gas) generated in the can body 10 is discharged to the outside of the can body 10 through the exhaust cylinder 80.

An O ₂ sensor 81 serving as an air ratio detection unit is disposed inside the exhaust pipe 80 of the present embodiment. The O ₂ sensor 81 is an oxygen concentration detector that detects the oxygen concentration of the exhaust gas. The O ₂ sensor 81 is electrically connected to the control device 70, and the control device 70 acquires the oxygen concentration of the exhaust gas based on the measurement value of the O ₂ sensor 81.

  Next, the fuel supply unit 50 that supplies fuel to the boiler 2 will be described. The fuel supply unit 50 includes a fuel supply line 51, a fuel gas flow meter 52, an on-off valve 54, a governor 55, a flow rate adjustment valve 56, a fuel gas temperature sensor 57, a fuel gas pressure sensor 58, and an orifice 59. And a fuel gas differential pressure sensor 60 and a nozzle 61.

  The fuel supply line 51 has an upstream side connected to a fuel supply source (not shown) and a downstream side connected to the air supply duct 30. The downstream end of the fuel supply line 51 is connected to the downstream side of the supply duct 30 from the position where the damper 31 is disposed. In the present embodiment, the fuel gas flowing through the fuel supply line 51 is LNG. LNG vaporized from the LNG storage facility supplied by the LNG satellite is supplied to the fuel supply line 51.

  The fuel gas flow meter 52 measures the flow rate of the fuel gas flowing through the fuel supply line 51. The fuel gas flow meter 52 of the present embodiment is disposed on the most upstream side of the fuel supply line 51. The fuel gas flow meter 52 is electrically connected to the control device 70. The control device 70 acquires the flow rate of the fuel gas based on the measurement value of the fuel gas flow meter 52.

  The on-off valve 54 opens or closes the fuel supply line 51 to supply and stop the fuel gas. The on-off valve 54 of the present embodiment is disposed on the fuel supply line 51 downstream of the fuel gas flow meter 52.

  The governor 55 is pressure adjusting means for suppressing a rapid pressure fluctuation such as when the pressure of the fuel gas flowing through the fuel supply line 51 increases momentarily. The governor 55 of the present embodiment is disposed on the downstream side of the on-off valve 54 in the fuel supply line 51.

  The flow rate adjustment valve 56 adjusts the flow rate of the fuel gas flowing through the fuel supply line 51. The flow rate adjustment valve 56 is configured to be able to adjust the opening degree. The flow rate adjustment valve 56 of the present embodiment is disposed on the downstream side of the governor 55 in the fuel supply line 51. The flow rate adjustment valve 56 is electrically connected to the control device 70, and the control device 70 can adjust the opening degree of the flow rate adjustment valve 56.

  The fuel gas temperature sensor 57 measures the temperature of the fuel gas flowing through the fuel supply line 51 on the downstream side of the flow rate adjustment valve 56. The fuel gas temperature sensor 57 of the present embodiment is disposed downstream of the flow rate adjustment valve 56 in the fuel supply line 51. The fuel gas temperature sensor 57 is electrically connected to the control device 70, and the control device 70 acquires temperature information of the fuel gas temperature sensor 57.

  The fuel gas pressure sensor 58 measures the pressure of the fuel gas flowing through the fuel supply line 51 on the downstream side of the flow rate adjustment valve 56. The fuel gas pressure sensor 58 of the present embodiment is disposed downstream of the fuel gas temperature sensor 57 in the fuel supply line 51. The fuel gas pressure sensor 58 is electrically connected to the control device 70, and the control device 70 acquires pressure information of the fuel gas pressure sensor 58.

  The orifice 59 is a fuel gas decompression member that decompresses the fuel gas flowing through the fuel supply line 51. The orifice 59 of the present embodiment is disposed on the downstream side of the fuel gas pressure sensor 58 in the fuel supply line 51.

  The fuel gas differential pressure sensor 60 is a fuel gas flow rate detector for detecting the flow rate of the fuel gas. The pressure difference between the upstream side and the downstream side of the orifice 59 is detected. The flow rate of the fuel gas on the downstream side of the flow rate adjusting valve 56 is calculated based on the fuel gas differential pressure information. The fuel gas differential pressure sensor 60 is electrically connected to the control device 70, and the control device 70 acquires fuel gas differential pressure information.

  The nozzle 61 is disposed at the downstream end of the fuel supply line 51 and ejects fuel gas to the air supply duct 30. The fuel gas ejected from the nozzle 61 is mixed with the combustion air sent by the blower 20, and the mixed gas is burned by the burner 15.

  As described above, the fuel supply unit 50 can supply the fuel gas to the boiler 2 (can 10) through the fuel supply line 51 at an appropriate flow rate.

  The control device 70 will be described. The control device 70 controls the flow rate adjustment valve 56 and the blower 20 based on signals from each electrically connected sensor. The control device 70 includes a control unit 71 that performs various controls for adjusting the flow rate of combustion air and the flow rate of fuel gas, and a storage unit 72 that stores various types of information.

  The control device 70 of the first embodiment controls the flow rate adjustment valve 56 with reference to the oxygen concentration of the exhaust gas in order to maintain the air ratio within a predetermined range. First, the relationship between the change in the mass flow rate of the fuel gas and the combustion rate will be described with reference to FIG. FIG. 2 is a graph showing the relationship between the mass flow rate of the fuel gas and the oxygen concentration of the exhaust gas. In FIG. 2, trial calculation conditions are set, and a change in mass flow rate due to a change in fuel gas temperature and a ratio of oxygen concentration of exhaust gas indicating a combustion rate are calculated. The fuel gas pressure is assumed to be constant.

As shown in FIG. 2, when a temperature change occurs in the fuel gas, the volume of the fuel gas changes and the mass flow rate changes. When the temperature of the fuel gas increases, the volume of the fuel gas increases, so the mass flow rate of the fuel gas decreases. When the temperature of the fuel gas decreases, the volume decreases, so the mass flow rate of the fuel gas increases. When such a change in mass flow rate occurs, even if the volume flow rate is constant, the theoretical amount of combustion air necessary for combustion of the fuel gas changes, and the air ratio changes. As shown in FIG. 2, the air ratio increases and the O ₂ concentration in the exhaust gas increases as the mass flow rate of the fuel gas decreases, while the air ratio decreases as the mass flow rate of the fuel gas increases. The O ₂ concentration in the exhaust gas becomes low. The air ratio is a value that is set in the boiler device 1 in order to appropriately perform combustion. If the air ratio cannot be controlled to a constant value, heat loss due to excess air occurs and combustion efficiency decreases. There is a risk of energy loss due to incomplete combustion.

  Therefore, the control device 70 according to the present embodiment determines whether or not the air ratio is in an appropriate range based on the oxygen concentration of the exhaust gas, and performs normal control when the air ratio is in the appropriate range. When the ratio is out of the appropriate range, the control is performed to adjust the opening of the flow rate adjusting valve according to the air ratio. Next, the detailed structure of the control part 71 with which the boiler apparatus 1 of 1st Embodiment is provided is demonstrated. FIG. 3 is a block diagram illustrating a configuration of the control unit 71. As shown in FIG. 3, the control unit 71 of the first embodiment includes a control value setting unit 91, a range determination unit 96, a correction value setting unit 97, a correction value update unit 98, a flow rate control unit 99, Is provided.

  The control value setting unit 91 sets an opening value indicating the opening of the flow rate adjustment valve 56. The opening value is a control value of the flow rate adjusting valve 56 for determining the flow rate of the fuel gas with respect to the flow rate of the combustion air under a predetermined condition. Here, the predetermined conditions are various conditions set in advance such as a reference heat amount and an air ratio based on the composition of the fuel gas, and the opening value is set assuming that the fuel gas is in the predetermined conditions. The storage unit 72 stores a functional expression or a data table for setting an opening value corresponding to the flow rate of combustion air under a predetermined condition.

The range determination unit 96 determines whether or not to correct the opening value based on the air ratio. In the present embodiment, the oxygen concentration of the exhaust gas acquired by the O ₂ sensor 81 is used as an index for detecting the state of the air ratio. The storage unit 72 stores determination conditions for correcting the opening value. The determination condition is whether or not the oxygen concentration acquired by the O ₂ sensor 81 is within a predetermined concentration range (first range). The predetermined concentration range is set in advance based on the air ratio, and when the oxygen concentration is within the predetermined concentration range, it can be considered that the air ratio is within the assumed range. In addition, it can be said that the range in which this air ratio is assumed is a range in which fluctuation of the air ratio is allowed.

The correction value setting unit 97 sets a correction value for correcting the opening value. The correction value is set based on the oxygen concentration when the range determining unit 96 determines that the predetermined concentration range has been exceeded. For example, when it is detected that the oxygen concentration acquired by the O ₂ sensor 81 exceeds the upper limit of the predetermined concentration range, the correction value is set so that the fuel gas flow rate is corrected. Similarly, when it is detected that the value falls below the lower limit of the predetermined concentration range, the correction value is set so that the correction for reducing the flow rate of the fuel gas is performed. The storage unit 72 stores a functional expression or a data table for calculating a correction value based on the oxygen concentration when the concentration is out of the predetermined concentration range. For example, the correction value can be obtained based on the difference between the upper limit or lower limit of the predetermined concentration range and the detected oxygen concentration.

The correction value update unit 98 updates the correction value set in the correction value setting unit 97 based on the air ratio situation. In the present embodiment, the correction value is updated when the correction value is set and the oxygen concentration of the exhaust gas acquired by the O ₂ sensor 81 is not within the predetermined concentration range. The correction value is updated based on the oxygen concentration outside the predetermined concentration range. In the update process, for example, the correction value before update (the set correction value) is referred to, and the target opening degree is set based on the referred correction value and the oxygen concentration outside the predetermined concentration range. An update correction value is calculated. Similar to the correction value setting process by the correction value setting unit 97, the correction value update unit 98 updates the correction value so that the flow rate of the fuel gas increases when the oxygen concentration exceeds the upper limit of the predetermined concentration range. When the value falls below the lower limit of the predetermined concentration range, the correction value is updated so that the flow rate of the fuel gas becomes small. The storage unit 72 stores a function formula or a data table for updating the correction value based on the oxygen concentration or the like.

  The flow rate control unit 99 controls the opening degree of the flow rate adjustment valve 56 based on the opening degree value. When a correction value is set, the flow rate control unit 99 of the present embodiment controls the flow rate adjustment valve 56 based on the opening value to which the correction value is added. The addition of the correction value here includes addition / subtraction / multiplication / division, and adding or multiplying the correction value with respect to the opening degree value is also included in adding the correction value to the opening degree.

  Next, control of the opening degree of the flow rate adjustment valve 56 in the first embodiment will be described with reference to FIG. FIG. 4 is a flowchart showing a process for controlling the opening degree of the flow rate adjustment valve 56 of the first embodiment.

When the control of the flow rate adjusting valve 56 is started, the control value setting unit 91 acquires the flow rate of the combustion air calculated based on the detection signal of the air differential pressure sensor 33 (S101). The control value setting unit 91 sets an opening value corresponding to the acquired flow rate of combustion air from the storage unit 72 (S102). The range determination unit 96 acquires the oxygen concentration of the exhaust gas based on the measurement value detected by the O ₂ sensor 81 (S103), and determines whether the oxygen concentration of the exhaust gas is within a predetermined concentration range (S104).

  If it is determined in S104 that the oxygen concentration of the exhaust gas is within the predetermined concentration range, the flow control unit 99 controls the opening of the flow rate adjustment valve 56 based on the opening value set in the control value setting unit 91. (S106). In this case, no correction value is added to the opening value. If it is determined in S104 that the oxygen concentration of the exhaust gas is outside the predetermined concentration range, a correction value is set by the correction value setting unit 97 (S105). This correction value is set based on the oxygen concentration determined to be outside the predetermined concentration range in the process of S104.

  The flow rate control unit 99 controls the opening degree of the flow rate adjustment valve 56 based on the opening degree value set according to the flow rate of the combustion air by the control value setting unit 91 (S106). When the correction value is set in the process of S105, the flow rate adjustment valve 56 is controlled based on the opening value to which the correction value is added. As described above, when it is determined in step S104 that the oxygen concentration is within the predetermined concentration range, the flow rate adjustment is performed based on the opening value set by the control value setting unit 91 without adding a correction value. The opening degree of the valve 56 is controlled (S106).

The range determination unit 96 acquires the oxygen concentration based on the measurement value of the O ₂ sensor 81 even after the processing of S106, and monitors whether or not it is within the predetermined concentration range (S107, S108). The range determination unit 96 returns to the process of S106 when the acquired oxygen concentration is within the predetermined concentration range. In this case, the correction value is not updated. That is, as long as the oxygen concentration detected after the correction value is set is within the predetermined concentration range, the correction value is not updated. On the other hand, if it is determined in step S108 that the oxygen concentration is outside the predetermined concentration range, the correction value is updated to a new one (S109). This correction value is updated based on the oxygen concentration that is outside the predetermined concentration range in the process of S108, and the process proceeds to S106. In the process of S106, the opening degree of the flow rate adjustment valve 56 is controlled based on the correction value updated in the process of S109. In the present embodiment, the processing from S106 to S109 is repeated, and the correction value is updated at a timing when the oxygen concentration is outside the predetermined concentration range. When the flow rate of combustion air changes and it becomes necessary to change the opening value, the opening value is newly set, and the above processing is performed based on the newly set opening value. Thus, the opening degree of the flow rate adjusting valve 56 is controlled. Further, the series of processes described with reference to FIG. 4 ends at an appropriate timing such as operation stop of the boiler 2 and is restarted.

  Through the above processing, the opening degree of the flow rate adjustment valve 56 is controlled according to the combustion state. The fuel gas adjusted to an appropriate flow rate by the flow rate adjusting valve 56 is sent to the air supply duct 30 via the fuel supply line 51. The fuel gas supplied into the air supply duct 30 via the nozzle 61 is mixed with the combustion air sent into the air supply duct 30 by the blower 20. A mixed gas of fuel gas and combustion air is ejected from the burner 15 into the can 10 and burned. In the present embodiment, even when the air ratio deviates from the assumed range due to mass fluctuation or heat quantity fluctuation, the opening degree value is corrected by the correction value and the opening degree of the flow rate adjustment valve 56 is appropriately adjusted. Even when it is easily affected by the external environment such as LNG satellite supply, stable operation of the boiler 2 can be realized. Further, since the correction value is updated when the oxygen concentration is outside the predetermined concentration range, it is possible to respond to the actual air ratio situation with good responsiveness.

  And the water supplied with the combustion of the mixed gas by the burner 15 heats the water supplied from the lower header 13 to the inside of the plurality of water pipes 12, and generates steam. The steam generated in the plurality of water pipes 12 is collected in the upper header 14 and then led out to the outside through a steam lead pipe (not shown) and supplied to a load device (not shown). Further, the combustion gas generated by the combustion of the mixed gas is discharged from the exhaust cylinder 80 to the outside.

  According to the boiler device 1 of 1st Embodiment demonstrated above, there exist the following effects.

The boiler apparatus 1 according to the first embodiment is detected by a control value setting unit 91 that sets an opening value (control value) corresponding to the flow rate of combustion air detected by the air differential pressure sensor 33, and an O ₂ sensor 81. A range determination unit 96 that determines whether or not the measured value is within a predetermined density range (first range), and a correction value is set based on the measurement value that is determined not to be within the predetermined density range by the range determination unit 96 A flow rate control that controls the flow rate adjustment valve 56 based on a control value to which the correction value is set and the correction value is set. A correction value updating unit 98 that updates the correction value based on the measurement value when the range determination unit 96 determines that the measurement value is not within the predetermined density range with the correction value set. Is provided.

Thus, at the timing when the air ratio reaches an unacceptable range, a correction value is added to the opening value of the flow rate adjustment valve 56 based on the measured value of the O ₂ sensor 81, and the air ratio is maintained in a certain range. As a result, precise control of the flow rate adjusting valve 56 according to fluctuations in the air ratio is realized. Further, since the correction value is updated at a timing exceeding the predetermined concentration range, the air ratio can be controlled with good responsiveness even when the combustion state changes. As described above, the correction value added to the opening degree value is set and updated at the timing when the air ratio changes to an unacceptable value, so that the process for controlling the opening degree of the flow rate adjusting valve 56 is performed efficiently and accurately. be able to.

The boiler apparatus 1 of the present embodiment further includes an exhaust pipe 80 that discharges exhaust gas generated by the combustion of fuel gas from the boiler 2, and an air ratio detection unit for detecting the air ratio is disposed in the exhaust pipe 80. The O ₂ sensor 81 detects the oxygen concentration of the exhaust gas.

  As a result, the opening degree of the flow rate adjustment valve 56 is controlled based on the oxygen concentration of the exhaust gas, so that the fuel gas can be supplied to the boiler 2 at an appropriate flow rate according to the actual combustion state in the boiler 2. The air ratio can be controlled more precisely.

  Next, the boiler apparatus of 2nd Embodiment is demonstrated. In addition, about the structure similar to 1st Embodiment, the same code | symbol may be attached | subjected and the description may be abbreviate | omitted.

  The boiler device of the second embodiment is different from the configuration of the first embodiment in that it detects a change in air ratio based on a change in mass flow rate. The fuel gas flow meter 52 of the second embodiment is configured as a mass flow meter that measures a mass flow rate. As described with reference to FIG. 3, the change in the mass flow rate affects the combustion state and changes the air ratio. Therefore, the control unit of the second embodiment is configured to detect the air ratio based on the change in mass flow rate detected by the fuel gas flow meter 52.

  The control unit of the second embodiment adjusts the opening degree of the flow rate adjustment valve 56 with reference to the mass flow rate detected by the fuel gas flow meter 52. A predetermined mass flow range for determining whether or not to set a correction value is set in the storage unit 72. The predetermined mass flow range is set in association with the air ratio so that it can be determined that the air ratio has deviated from the assumed range when it deviates from the predetermined mass flow range.

  The range determination unit 96 compares the measured value (mass flow rate) of the fuel gas flow meter 52 with a predetermined mass flow range to determine whether or not to set a correction value. Then, the correction value setting unit 97 and the correction value updating unit 98 set and update the correction value based on the mass flow rate when it is out of the predetermined mass flow range. For example, when the mass flow rate acquired by the fuel gas flow meter 52 exceeds the upper limit of a predetermined mass flow rate range, the correction value is set or updated so that the flow rate (volume flow rate) of the fuel gas becomes small. Similarly, when the mass flow rate acquired by the fuel gas flow meter 52 falls below the lower limit of the predetermined mass flow range, the correction value is set or updated so that the flow rate of the fuel gas increases. Thus, in 2nd Embodiment, the condition of air ratio is judged based on mass flow, and control of the flow regulating valve 56 according to the condition of air ratio is performed. In addition, about another structure and control of 2nd Embodiment, it is the same as that of 1st Embodiment.

  According to the boiler apparatus of 2nd Embodiment demonstrated above, there exist the following effects.

  The air ratio detection part in the boiler apparatus of 2nd Embodiment is the fuel gas flowmeter 52 which is arrange | positioned at the fuel supply line 51, and detects the fluctuation | variation of the mass flow rate of fuel gas. Thereby, the influence of the fluctuation | variation of the air ratio resulting from the fluctuation | variation of mass flow rate is suppressed, and stable and efficient combustion control is realizable.

  Next, the boiler apparatus 301 of 3rd Embodiment is demonstrated. FIG. 5 is a diagram schematically illustrating a boiler device 301 according to the third embodiment. In addition, about the structure similar to 1st Embodiment, the same code | symbol may be attached | subjected and the description may be abbreviate | omitted.

  As shown in FIG. 5, the boiler apparatus 301 of 3rd Embodiment is further provided with the calorimeter 53 as a calorie | heat amount detection part in addition to the structure of 1st Embodiment. The boiler device of the third embodiment is different from the configuration of the first embodiment in that the air ratio change is detected based on the calorific value change detected by the calorimeter 53. Since the required supply amount of fuel gas with respect to the supply amount of combustion air is set based on the reference heat amount, if the heat amount fluctuates, the required supply amount of fuel gas with respect to the supply amount of combustion air also changes, and the air ratio Fluctuates. In the third embodiment, the air ratio fluctuation caused by the heat quantity fluctuation is detected based on the measured value of the calorimeter 53 and reflected in the control of the flow rate adjustment valve 56.

  The control unit 371 of the third embodiment adjusts the opening degree of the flow rate adjustment valve 56 with reference to the amount of heat detected by the calorimeter 53. In the storage unit 72, a predetermined heat amount range for determining whether or not to set a correction value is set. The predetermined heat amount range is set in association with the air ratio so that it can be determined that the air ratio has deviated from the assumed range when it deviates from the predetermined heat amount range.

  The range determination unit 96 compares the measured value (heat amount) of the calorimeter 53 with the predetermined heat amount range, and determines whether or not to set a correction value. Then, the correction value setting unit 97 and the correction value updating unit 98 set and update the correction value based on the heat amount when the heat value is outside the predetermined heat amount range. For example, when the amount of heat acquired by the calorimeter 53 exceeds the upper limit of a predetermined heat amount range, the correction value is set or updated so that the flow rate (volume flow rate) of the fuel gas is reduced. Similarly, when the amount of heat acquired by the calorimeter 53 is below the lower limit of the predetermined heat amount range, the correction value is set or updated so that the flow rate of the fuel gas is increased. Thus, in the third embodiment, the state of the air ratio is determined based on the amount of heat, and the flow rate adjustment valve 56 is controlled according to the state of the air ratio. In addition, about another structure and control of 3rd Embodiment, it is the same as that of 1st Embodiment.

  According to the boiler device 301 of 3rd Embodiment demonstrated above, there exist the following effects.

  The air ratio detection part in the boiler apparatus 301 of 3rd Embodiment is the calorimeter 53 which is arrange | positioned at the fuel supply line 51 and detects the calorie | heat amount of fuel gas. Thereby, the influence of the fluctuation | variation of the air ratio resulting from the fluctuation | variation of a calorie | heat_rate can be suppressed, and stable and efficient combustion control is realizable.

  As mentioned above, although each preferred embodiment of the boiler apparatus of the present invention was described, the present invention is not limited to the above-mentioned embodiment, and can be changed suitably. For example, the present invention can be applied to a configuration in which the opening of the flow rate adjustment valve 56 is feedback controlled based on the flow rate of the fuel gas detected by the fuel gas differential pressure sensor 60 using the control value as the target flow rate. In this case, the target to which the correction value is added is the target flow rate that is the control value. Further, the process for determining whether or not to set the correction value in the first embodiment may be a process that starts after the combustion control is stabilized after the ignition of the burner 15 is started. Moreover, in 2nd Embodiment, although it is the structure which detects the fluctuation | variation of mass flow rate with the fuel gas flowmeter 52, the structure which detects the fluctuation | variation of mass flow rate can be changed suitably according to a situation. For example, a variation in mass flow rate may be detected based on temperature information and pressure information detected by the fuel gas temperature sensor 57 and the fuel gas pressure sensor 58. Thus, the air ratio detection part should just be the structure which can detect an air ratio directly or indirectly, and can be suitably changed according to a situation. Further, the correction value calculation processing and update processing are not limited to the processing in the above embodiment, and can be appropriately changed as long as the calculation method is based on the measurement value detected by the air ratio detection unit.

  In the above embodiment, a configuration in which the fuel gas is supplied by LNG satellite supply is adopted, but the fuel gas and the fuel gas supply source can be changed as appropriate. For example, the present invention can be applied to a configuration in which fuel gas is directly supplied from a fuel supplier through a pipeline.

1 Boiler device 2 Boiler 30 Air supply duct (Air supply line)
33 Air differential pressure sensor (Air flow rate detector)
51 Fuel supply line 52 Fuel gas flow meter (Air ratio detector)
53 Calorimeter (Air ratio detector)
56 Flow control valve 80 Exhaust tube (exhaust gas discharge part)
81 O ₂ sensor (air ratio detector)
91 Control Value Setting Unit 96 Range Determination Unit 97 Correction Value Setting Unit 98 Correction Value Update Unit 99 Flow Control Unit 301 Boiler Device

Claims (4)

With a boiler,
A fuel supply line for supplying fuel gas to the boiler;
A flow rate adjusting valve disposed in the fuel supply line and capable of adjusting a flow rate of the fuel gas;
An air supply line for supplying combustion air to be mixed with the fuel gas in the boiler;
An air flow rate detector for detecting the flow rate of the combustion air flowing through the air supply line;
An air ratio detector for detecting the air ratio;
A control value setting unit for setting a control value corresponding to the flow rate of the combustion air detected by the air flow rate detection unit;
A range determination unit for determining whether or not the measurement value detected by the air ratio detection unit is in the first range;
A correction value setting unit that sets a correction value based on the measurement value determined not to be in the first range by the range determination unit;
A flow control unit that controls the flow rate adjustment valve based on the control value, and controls the flow rate adjustment valve based on the control value to which the correction value is added when the correction value is set;
A correction value update unit that updates the correction value based on the measurement value when the range determination unit determines that the measurement value is not in the first range in a state where the correction value is set;
A boiler device comprising: An exhaust gas exhaust unit that exhausts exhaust gas generated by the combustion of the fuel gas from the boiler;
The boiler apparatus according to claim 1, wherein the air ratio detection unit is an oxygen concentration detection unit that is disposed in the exhaust gas discharge unit and detects an oxygen concentration of the exhaust gas.   The boiler device according to claim 1, wherein the air ratio detection unit is disposed in the fuel supply line and detects a change in a mass flow rate of the fuel gas.   The boiler device according to claim 1, wherein the air ratio detection unit is a heat amount detection unit that is disposed in the fuel supply line and detects a heat amount of the fuel gas.

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