JP2016114329A - Operational method for gas burning burner and gas burning burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an operational method for a gas burning burner so as to put a gas burning burner capable of reducing a discharging amount of nitrogen oxide into practical use.SOLUTION: An operational method for a gas burning burner comprising: a primary burner for supplying only gas fuel for flame holding combustion to a combustion part; a secondary burner arranged at an outer periphery of the primary burner for performing lean pre-mixture of gas fuel and air for pre-mixture combustion and supplying mixture gas subjected to the lean pre-mixture to the combustion part; and a tertiary burner arranged at an outer periphery of the secondary burner, facing the combustion part, for supplying the gas fuel for reduction combustion to the combustion part. A secondary burner starting step is carried out after both the primary burner starting step and the third burner starting step.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a method for operating a gas-fired burner, and more particularly, to a method for operating a gas-fired burner that burns liquefied natural gas (LNG).

  As a means for reducing the emission amount of nitrogen oxide (NOx), a gas-fired burner that employs a premixed combustion system for a primary burner, a secondary burner, and a tertiary burner has been proposed. The primary burner supplies gas fuel for stable combustion to the combustion section, and includes a stable combustion air supply pipe and a stable combustion fuel supply pipe. The stable combustion air supply pipe is disposed in the center of the gas-burning burner, and the stable combustion fuel supply pipe is disposed in communication with the base of the stable combustion air supply pipe. Thereby, the gas fuel supplied from the fuel supply pipe for stable combustion is mixed (premixed) with the air supplied from the air supply pipe for stable combustion. And the swirl | swivel component is provided to the premixed air-fuel | gaseous mixture by a swirler, and it ejects to a combustion part from the jet outlet of a primary burner. Further, a diffuser constituting a flame holder is provided at the jet outlet of the primary burner, and the air-fuel mixture jetted to the combustion section is supplied to the diffuser to ensure a flame (flame holding). The secondary burner supplies main combustion gas fuel to the combustion section, and includes a main combustion air supply pipe and a main combustion fuel supply pipe. The main combustion air supply pipe is formed in a cylindrical shape centered on the primary burner, and air swirl vanes are provided at the base thereof. The main combustion fuel supply pipe communicates with the base of the main combustion air supply pipe. Thereby, the gas fuel supplied from the main combustion fuel supply pipe is supplied from the main combustion air supply pipe and mixed (premixed) with the air to which the swirl component is added. And the premixed air-fuel mixture is ejected from the outlet of the secondary burner to the combustion section. The tertiary burner supplies additional combustion fuel, and an air-fuel mixture in which gas fuel is premixed with air is ejected to the combustion section. Further, an additional combustion air mixing portion for mixing additional combustion air is provided in front of the outlet of the tertiary burner. Thereby, air is mixed from the mixing part into the gas fuel ejected from the jet outlet of the tertiary burner as necessary.

  In the gas-burning burner described above, the gas fuel supplied to the primary burner is mixed so that the ratio of fuel to air (air ratio) is 1 or more, and is ejected to the combustion section. Similarly, the gas combustion supplied to the secondary burner is mixed so that the air ratio becomes 1.2 to 1.5, and is ejected to the combustion section. The gas fuel jetted from the jet outlet of the tertiary burner is mixed with air supplied from the mixing section as needed, but the air ratio at this time is 0.5 or less.

  Since the gas-burning burner described above employs a premixed combustion method for the primary burner, the secondary burner, and the tertiary burner, the amount of nitrogen oxide emissions can be reduced (see, for example, Patent Document 1).

Japanese Patent No. 3434496

However, the gas-fired burner described in Patent Document 1 described above employs a premixed combustion system for the primary burner, and a throat (crater), a diffuser, It is difficult to adjust the interval. In addition, if the gap between the throat and the diffuser is not sufficiently adjusted, unstable combustion may be caused, and the practical application has not progressed.
In view of the above circumstances, at least one embodiment of the present invention provides a novel gas-burning burner operation method for practical use of a novel gas-burning burner that can reduce the emission amount of nitrogen oxides (NOx). With the goal.

  (1) In at least one embodiment of the present invention, in the method for operating a gas-burning burner, the gas-burning burner mainly includes a primary burner that supplies gas fuel for flame holding combustion to a combustion section, and the primary burner. And a secondary burner for premixed gas fuel and air for premixed combustion and supplying the lean premixed gas mixture to the combustion section, and a secondary burner provided around the primary burner. A third burner provided on the outer periphery facing the combustion section and supplying gas fuel for reduction combustion to the combustion section, and by starting supply of the gas fuel for flame holding combustion to the combustion section A primary burner start-up step of starting up the primary burner, a secondary burner start-up step of starting up the secondary burner by starting supply of the gas fuel for premixed combustion, and the gas fuel for reducing combustion The fuel A third burner starting step of starting the tertiary burner by starting supply to a section, wherein the secondary burner starting step includes the primary burner starting step and the tertiary burner starting step. It is performed later.

  According to the novel gas-burning burner, the amount of nitrogen oxide emission can be reduced by the amount of lean premixed combustion of the gas fuel by the secondary burner.

  It was confirmed that when the gas-fired burner was started up and lowered, the flame was drawn into the burner throat and reduced when the operating load passed through the low load region. If the operation is continued with this phenomenon occurring, combustion vibration may occur.

  As a cause of the flame being drawn into the burner throat in this way, in the gas-fired burner, the diffusion flame caused by the primary burner and the tertiary burner and the premixed flame caused by the secondary burner coexist. It is conceivable that a plurality of ignition positions can be formed. Because the premixed flame of the secondary burner has good ignitability and high flame propagation speed, the flame propagation speed is air at low loads (for example, when the gas-fired burner is started up and down) when the flow rate of supplied combustion air is low. Above the flow velocity, a flame may be drawn into the burner throat.

  In this regard, in the operation method of the gas-burning burner described in (1) above, the secondary burner startup process is performed after the primary burner startup process and the tertiary burner startup process. Thus, the premixed flame of the secondary burner is formed after the ignition position is stabilized at a position far from the burner throat only by the diffusion flame formed by the primary burner and the diffusion flame formed by the tertiary burner. It becomes possible.

  The premixed flame has a high flame propagation speed and is likely to cause a flame drawing into the burner throat, whereas the diffusion flame has a low flame propagation speed and is unlikely to cause a flame drawing into the burner throat. Therefore, as described above, after the ignition position is stabilized at a position far from the burner throat only by the diffusion flame formed by the primary burner and the diffusion flame formed by the tertiary burner, If the mixed flame is formed, it is possible to effectively prevent the flame from being drawn into the burner throat when the gas-fired burner is started up.

  (2) In some embodiments, in the operation method of the gas-burning burner according to (1), the secondary burner is formed in a cylindrical two-layer structure centered on the primary burner, Each of the inner layer and the outer layer in the cylindrical two-layer structure is configured such that the gas fuel for premixed combustion and the air are lean premixed, and the lean premixed mixture can be supplied to the combustion unit, In the primary burner start-up step, air supplied from at least an inner layer of the cylindrical two-layer structure to the combustion section is used for start-up of the primary burner, and in the tertiary burner start-up step, Of the cylindrical two-layer structure, air supplied from at least an outer layer to the combustion section is used for starting up the tertiary burner.

  According to the operation method of the gas burning burner described in the above (2), the primary burner and the secondary burner located on the inner peripheral side of the secondary burner are formed by forming the secondary burner with a cylindrical two-layer structure. Combustion air can be efficiently supplied to the primary burner and the tertiary burner with a simple configuration when starting up the tertiary burner located on the outer peripheral side (and during normal operation). .

  (3) In some embodiments, in the operation method of the gas-fired burner according to (1) or (2), in the secondary burner start-up step, the primary burner and the tertiary burner are in the combustion mode. No air is supplied to the part.

  As described above, since the premixed flame of the secondary burner has good ignitability and high flame propagation speed, the flow rate of the supplied combustion air is low, for example, when the gas-burning burner is started up and down. When the flame propagation speed exceeds the air flow rate, a flame may be drawn into the burner throat.

  In this regard, according to the operation method of the gas-fired burner described in (3) above, the primary burner and the tertiary burner do not supply air to the combustion section in the startup process of the secondary burner that performs premixed combustion. Therefore, after the ignition position is stabilized at a position far from the burner throat only by the diffusion flame formed by the primary burner and the diffusion flame formed by the tertiary burner, the premixed flame of the secondary burner is formed. It becomes easy. Thereby, it can suppress effectively that a flame is drawn in into a burner throat at the time of starting of a gas burning burner.

  (4) In at least one embodiment of the present invention, in the method for operating a gas-burning burner, the gas-burning burner includes a primary burner that supplies gas fuel for flame holding combustion to the combustion section, and the primary burner. A secondary burner provided at the center surrounding the primary burner, which performs lean premixing of gas fuel for premixed combustion and air, and supplies the lean premixed mixture to the combustion section; and the secondary burner And a tertiary burner that is provided on the outer periphery of the combustion chamber so as to face the combustion section and supplies gas fuel for reducing combustion to the combustion section, and stops the supply of the gas fuel for flame holding combustion to the combustion section A primary burner lowering step for lowering the primary burner, a secondary burner lowering step for lowering the secondary burner by stopping supply of the gas fuel for the premixed combustion, and the combustion Return to department A tertiary burner lowering step of lowering the tertiary burner by stopping the supply of combustion gas fuel, and the secondary burner lowering step includes the primary burner lowering step and the tertiary It is performed before the burner falling process.

  According to the novel gas-burning burner, the emission amount of nitrogen oxides can be reduced by the amount of lean premix combustion in the secondary burner.

  It was confirmed that when the gas-fired burner was started up and lowered, the flame was drawn into the burner throat and reduced when the operating load passed through the low load region. If the operation is continued with this phenomenon occurring, combustion vibration may occur.

  As a cause of the flame being drawn into the burner throat in this way, in the gas-fired burner, the diffusion flame caused by the primary burner and the tertiary burner and the premixed flame caused by the secondary burner coexist. It is conceivable that a plurality of ignition positions can be formed. Because the premixed flame of the secondary burner has good ignitability and high flame propagation speed, the flame propagation speed is air at low loads (for example, when the gas-fired burner is started up and down) when the flow rate of supplied combustion air is low. Above the flow velocity, a flame may be drawn into the burner throat.

  In this regard, in the operation method of the gas burning burner described in the above (4), the secondary burner lowering step is performed before the primary burner lowering step and the tertiary burner lowering step. Thereby, the premixed flame of the secondary burner is extinguished in a state where the ignition position is stabilized at a position far from the burner throat by the diffusion flame formed by the primary burner and the diffusion flame formed by the tertiary burner. Is possible.

  The premixed flame has a high flame propagation speed and is likely to cause a flame drawing into the burner funnel, whereas the diffusion flame has a low flame propagation speed and is unlikely to cause a flame drawing into the burner throat. Therefore, as described above, the pre-mixing of the secondary burner is performed in a state where the ignition position is stabilized at a position far from the burner throat by the diffusion flame formed by the primary burner and the diffusion flame formed by the tertiary burner. If the flame is extinguished, the premixed flame of the secondary burner can be effectively suppressed from being drawn into the burner throat until immediately before the secondary burner is extinguished.

  (5) In some embodiments, in the operation method of the gas-fired burner according to (4), the secondary burner is formed in a cylindrical two-layer structure centered on the primary burner, Each of the inner layer and the outer layer in the cylindrical two-layer structure is configured such that the gas fuel for premixed combustion and the air are lean premixed, and the lean premixed mixture can be supplied to the combustion chamber. In the primary burner lowering step, the supply of the gas fuel for flame holding combustion to the combustion section is stopped, and then the air supply to the inner layer is stopped. In the tertiary burner starting step, the combustion is performed. The supply of the gas fuel for reducing combustion to the section is stopped, and then the supply of air to the outer layer is stopped.

  According to the operation method of the gas-fired burner described in (5) above, the primary burner and the secondary burner located on the inner peripheral side of the secondary burner are formed by forming the secondary burner with a cylindrical two-layer structure. Combustion air is efficiently supplied to the primary burner and the tertiary burner with just a simple configuration when the tertiary burner located on the outer periphery of the burner is lowered (and during normal operation). can do.

  (6) In some embodiments, in the gas-fired burner operation method according to (4) or (5), in the step of lowering the secondary burner, the primary burner and the tertiary burner are It is characterized by not supplying air to the combustion part.

  As described above, since the premixed flame of the secondary burner has good ignitability and high flame propagation speed, the flow rate of the supplied combustion air is low, for example, when the gas-burning burner is started up and down. When the flame propagation speed exceeds the air flow rate, a flame may be drawn into the burner throat.

  In this regard, according to the operation method of the gas-fired burner described in (6) above, the primary burner and the tertiary burner do not supply air to the combustion section in the step of lowering the secondary burner that performs premixed combustion. Therefore, after the ignition position is stabilized at a position far from the burner throat only by the diffusion flame formed by the primary burner and the diffusion flame formed by the tertiary burner, the premixed flame of the secondary burner is formed. It becomes easy. Thereby, it can suppress effectively that a flame is drawn in into a burner throat at the time of fall of a gas burning burner.

  (7) In some embodiments, in the method for operating a gas-burning burner according to any one of (1) to (6), the primary burner and the tertiary burner are configured to supply air to the combustion unit. It is characterized by not having an air supply pipe for supplying water.

  According to the gas-burning burner described in (7) above, the air quantity of the secondary burner is adjusted while reducing the risk of flashback by making the combustion of the primary burner and the combustion of the tertiary burner into diffusion combustion. Therefore, the flame characteristics can be adjusted flexibly.

  (8) A gas-burning burner according to at least one embodiment of the present invention includes a primary burner that supplies a gas fuel for flame holding combustion to the combustion section, and surrounds the primary burner with the primary burner as a center. A secondary burner that is provided with a lean premix of gas fuel for premixed combustion and air and supplies the lean premixed mixture to the combustion section; and an outer periphery of the secondary burner facing the combustion section A gas-burning burner comprising a tertiary burner that is provided and supplies gas fuel for reducing combustion to the combustion unit, and a control unit that controls the primary burner, the secondary burner, and the tertiary burner. The control unit starts supplying the burner combustion gas fuel to the combustion unit to start the primary burner, and starts supplying the premixed combustion gas fuel. By doing so, Secondary burner start-up control for starting up the burner, and tertiary burner start-up control for starting up the tertiary burner by starting to supply the gas fuel for reducing combustion to the combustion section. The start-up control unit is configured to perform the secondary burner start-up control after the primary burner start-up control and the tertiary burner start-up control. .

  According to the novel gas-burning burner, the amount of nitrogen oxide emission can be reduced by the amount of lean premixed combustion of the gas fuel by the secondary burner.

  It was confirmed that when the gas-fired burner was started up and lowered, the flame was drawn into the burner throat and reduced when the operating load passed through the low load region. If the operation is continued with this phenomenon occurring, combustion vibration may occur.

  As a cause of the flame being drawn into the burner throat in this way, in the gas-fired burner, the diffusion flame caused by the primary burner and the tertiary burner and the premixed flame caused by the secondary burner coexist. It is conceivable that a plurality of ignition positions can be formed. Because the premixed flame of the secondary burner has good ignitability and high flame propagation speed, the flame propagation speed is air at low loads (for example, when the gas-fired burner is started up and down) when the flow rate of supplied combustion air is low. Above the flow velocity, a flame may be drawn into the burner throat.

  In this regard, in the gas-burning burner described in (8) above, the secondary burner startup control is performed after the primary burner startup control and the tertiary burner startup control. Thus, the premixed flame of the secondary burner is formed after the ignition position is stabilized at a position far from the burner throat only by the diffusion flame formed by the primary burner and the diffusion flame formed by the tertiary burner. It becomes possible.

  The premixed flame has a high flame propagation speed and is likely to cause a flame drawing into the burner throat, whereas the diffusion flame has a low flame propagation speed and is unlikely to cause a flame drawing into the burner throat. Therefore, as described above, after the ignition position is stabilized at a position far from the burner throat only by the diffusion flame formed by the primary burner and the diffusion flame formed by the tertiary burner, If the mixed flame is formed, it is possible to effectively prevent the flame from being drawn into the burner throat when the gas-fired burner is started up.

  (9) A gas-burning burner according to at least one embodiment of the present invention includes a primary burner that supplies gas fuel for flame holding combustion to the combustion section, and surrounds the primary burner with the primary burner as a center. A secondary burner that is provided with a lean premix of gas fuel for premixed combustion and air and supplies the lean premixed mixture to the combustion section; and an outer periphery of the secondary burner facing the combustion section A gas-burning burner comprising a tertiary burner that is provided and supplies gas fuel for reducing combustion to the combustion unit, and a control unit that controls the primary burner, the secondary burner, and the tertiary burner. The control unit is configured to stop the primary burner by stopping the supply of the gas fuel for flame holding combustion to the combustion unit, and to control the gas fuel for the premixed combustion. By stopping the supply Secondary burner lowering control for lowering the next burner and tertiary burner lowering control for lowering the tertiary burner by stopping the supply of the reducing combustion gas fuel to the combustion section can be executed. The fall controller is configured to perform the secondary burner fall control before the primary burner fall control and the tertiary burner fall control. It is characterized by.

  According to the novel gas-burning burner, the emission amount of nitrogen oxides can be reduced by the amount of lean premix combustion in the secondary burner.

  It was confirmed that when the gas-fired burner was started up and lowered, the flame was drawn into the burner throat and reduced when the operating load passed through the low load region. If the operation is continued with this phenomenon occurring, combustion vibration may occur.

  As a cause of the flame being drawn into the burner throat in this way, in the gas-fired burner, the diffusion flame caused by the primary burner and the tertiary burner and the premixed flame caused by the secondary burner coexist. It is conceivable that a plurality of ignition positions can be formed. Because the premixed flame of the secondary burner has good ignitability and high flame propagation speed, the flame propagation speed is air at low loads (for example, when the gas-fired burner is started up and down) when the flow rate of supplied combustion air is low. Above the flow velocity, a flame may be drawn into the burner throat.

  In this regard, in the gas-fired burner described in (9) above, the secondary burner lowering control is performed before the primary burner lowering control and the tertiary burner lowering control. Thereby, the premixed flame of the secondary burner is extinguished in a state where the ignition position is stabilized at a position far from the burner throat by the diffusion flame formed by the primary burner and the diffusion flame formed by the tertiary burner. Is possible.

  The premixed flame has a high flame propagation speed and is likely to cause a flame drawing into the burner funnel, whereas the diffusion flame has a low flame propagation speed and is unlikely to cause a flame drawing into the burner throat. Therefore, as described above, the pre-mixing of the secondary burner is performed in a state where the ignition position is stabilized at a position far from the burner throat by the diffusion flame formed by the primary burner and the diffusion flame formed by the tertiary burner. If the flame is extinguished, the premixed flame of the secondary burner can be effectively suppressed from being drawn into the burner throat until immediately before the secondary burner is extinguished.

  As described above, according to at least one embodiment of the present invention, the emission amount of nitrogen oxides can be reduced by the amount of lean premix combustion by the secondary burner. Further, it is possible to effectively suppress the flame from being drawn into the burner throat when the gas-burning burner is started up or lowered.

It is a cross-sectional schematic diagram which shows the structure of the gas burning burner which concerns on one Embodiment. It is the II-II sectional view taken on the line which shows arrangement | positioning of the nozzle of the secondary burner shown in FIG. It is the III-III arrow directional view which shows the tertiary burner shown in FIG. It is a figure which shows the relationship between the air ratio in a premixed combustion system and a diffusion combustion system, and the discharge | emission amount of a nitrogen oxide. It is a figure which shows the flow-velocity distribution of a diffuser and a swirler. It is the elements on larger scale of the gas burning burner shown in FIG. It is a figure which shows the starting flow of the gas burning burner which concerns on one Embodiment. It is a figure which shows the fall flow of the gas burning burner which concerns on one Embodiment. It is a figure which shows the starting flow of the gas burning burner which concerns on one reference form. It is a figure which shows the fall flow of the gas burning burner which concerns on one reference form. It is a figure for demonstrating the structure of the control part which concerns on one Embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail. Note that the present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are indispensable as means for solving the present invention. Not necessarily.

  FIG. 1 is a schematic cross-sectional view showing the structure of a gas burning burner according to an embodiment of the present invention. 2 is a sectional view taken along the line II-II showing the arrangement of the nozzles of the secondary burner shown in FIG. 1, and FIG. 3 is a view taken along the line III-III showing the tertiary burner shown in FIG. .

  As shown in FIG. 1, a gas-fired burner 1 according to an embodiment of the present invention includes a burner throat 21, a primary burner 3, a secondary burner 4, and a tertiary burner 7. The burner throat 21 is an opening (crater) provided in the furnace wall 2 and is formed in a trumpet shape that gradually expands outward, and a combustion part B that burns gas fuel is formed in front thereof. .

  The primary burner 3 supplies gas fuel for flame holding combustion to the combustion section B, and is disposed on an axis passing through the center of the burner throat 21. The primary burner 3 is formed in a cylindrical shape centering on an axis passing through the center of the burner throat 21. A fuel jet 31 is provided at the front end of the primary burner 3. An introduction part 32 is provided. The fuel jet 31 is suitable for diffusion combustion, and the gas fuel ejected from the fuel jet 31 is diffused in a conical shape with the fuel jet 31 as a vertex. The fuel introduction part 32 is provided in a mode orthogonal to the extending direction of the primary burner 3, and the gas fuel for flame holding combustion introduced from the fuel introduction part 32 passes through the primary burner 3 to the fuel outlet 31. Supplied and ejected from the fuel ejection port 31 to the combustion section B. The primary burner 3 does not have an air supply pipe for supplying air to the combustion section B, and is configured to supply only the gas fuel for flame holding combustion to the combustion section B.

  The secondary burner 4 performs lean premixing of gas fuel for premixed combustion and air, and supplies the lean premixed mixture to the combustion section B. The gas fuel for premixed combustion is introduced air After being mixed (premixed), it is supplied to the combustion section B. The secondary burner 4 is formed in a cylindrical two-layer structure with the primary burner 3 as the center.

  Inner inner layer 5 is for taking in primary air A1 and supplying it to combustion section B, and its outlet end surface 51 is formed by an orthogonal end surface orthogonal to an axis passing through the center of the inner layer. An air inlet (first air inlet) 52 is provided at a position outside the diameter of the inner layer. The air inlet 52 is an opening for taking the primary air A1 into the inner layer 5, and the primary air A <b> 1 taken from the air inlet 52 is introduced into the inner layer 5. A fuel supply pipe (first fuel supply pipe) 53 is provided on the air introduction side of the inner layer 5. The fuel supply pipe 53 is for supplying gas fuel (primary gas fuel) G1 for premixed combustion to the inner layer 5. The fuel supply pipe 53 is formed of a steel pipe whose tip is closed, and a plurality of fuel jets (nozzles) (not shown) are provided on the outer half of the outer periphery thereof. The plurality of fuel injection ports are equally spaced in the axial direction of the fuel supply pipe and have a phase difference of a predetermined angle in the circumferential direction of the fuel supply pipe (staggered arrangement). Thereby, the gaseous fuel G1 supplied to the fuel supply pipe 53 is ejected from the plurality of fuel ejection ports and mixed with the primary air A1 taken in from the air introduction port 52 (lean premixing).

  A swirler 54 is attached to the outlet of the inner layer 5. The swirler 54 imparts a swirl component to the lean premixed mixture, and the lean premixed mixture on the air introduction side of the inner layer 5 is given the swirl component by the swirler 54, and then the combustion section B To be supplied.

  The outer layer 6 on the outside is for taking in the secondary air A2 and supplying it to the combustion section B. An air inlet (second air inlet) 61 is provided at a position outside the diameter of the outer layer 6. Yes. The air inlet 61 is an opening for taking the secondary air A2 into the outer layer 6, and a vane 62 is attached as shown in FIG. The vane 62 is for opening and closing the air inlet 61. By tilting the vane 62, a desired opening / closing amount can be obtained. As shown in FIG. 1, a fuel supply pipe (second fuel supply pipe) 63 is provided on the air introduction side of the outer layer 6. The fuel supply pipe 63 is for supplying gas fuel (secondary gas fuel) G2 for premixed combustion to the outer layer 6. The fuel supply pipe 63 is formed of a steel pipe having a diameter larger than that of the fuel supply pipe 53 described above and closed at the tip thereof. ) (Not shown). The plurality of fuel jets are equally spaced in the axial direction of the fuel supply pipe 63 and have a phase difference of a predetermined angle in the circumferential direction of the fuel supply pipe 63 (staggered arrangement), like the fuel jets described above. As a result, the gas fuel G2 supplied to the fuel supply pipe 63 is ejected from the plurality of fuel ejection ports and mixed with the secondary air A2 introduced from the air introduction port 61 (lean premixing). The lean premixed air-fuel mixture is supplied to the combustion section B. As described above, each of the inner layer 5 and the outer layer 6 is configured to be capable of dilute premixing gas fuel for premixed combustion and air, and supplying the lean premixed mixture to the combustion chamber B.

  A valve 64 is provided between the gas supply source (not shown) and the fuel supply pipe 63. The valve 64 is an on-off valve that adjusts the supply amount of the gas fuel G2 supplied to the fuel supply pipe 63. When the valve 64 is opened, the gas fuel G2 is supplied to the fuel supply pipe 63, and when the valve 64 is closed, the gas fuel is supplied. The supply of G2 is stopped. Thereby, when the load is small, the fuel supply pipe 63 on the outer layer side is closed, the air introduction port 61 on the outer layer side is closed, and the heating power (output) of the gas burning burner 1 can be reduced.

  The tertiary burner 7 supplies gas fuel for reducing combustion to the combustion section B, and is provided on the outer periphery of the secondary burner 4 so as to face the combustion section B. As shown in FIG. 3, the tertiary burner 7 is formed in an annular shape (ring shape) centering on an axis passing through the center of the burner throat 21, and supplies gas fuel for reducing combustion to the opposite side of the burner throat 21. A supply path 71 is provided. A plurality of fuel jets (nozzles) 72 are provided on the burner throat 21 side of the tertiary burner 7. The fuel outlet 72 is provided at a position where the tertiary burner 7 is equally divided into four in the circumferential direction. The fuel outlet 72 is suitable for reductive combustion and is called a lance nozzle. The reducing combustion gas fuel supplied from the supply passage 71 passes through the tertiary burner 7, is supplied to the fuel injection port 72, and is injected from the fuel injection port 72 to the combustion part B. The tertiary burner 7 does not have an air supply pipe for supplying air to the combustion section B, and is configured to supply only the gas fuel for reducing combustion to the combustion section B.

  The gas fuel supplied to the primary burner 3 is introduced from the fuel introduction part 32. The introduced gas fuel passes through the primary burner 3, is jetted from the fuel jet 31 to the combustion section B, is diffused into the air (air mixture) supplied from the secondary burner 4, and is diffusively burned. When the gas fuel is supplied only to the primary burner 3, the gas fuel supplied to the primary burner 3 is diffused into the air supplied from the secondary burner 4 to ensure a flame in the combustion part B (flame holding). ). Thereby, the gas fuel supplied to the primary burner 3 is a gas fuel for flame holding combustion.

  Part of the gas fuel supplied to the secondary burner 4 (primary gas fuel G1) is supplied to the fuel supply pipe 53 on the inner layer side, and the remainder (secondary gas fuel G2) is supplied to the fuel supply pipe on the outer layer side. 63. The primary gas fuel G1 supplied to the fuel supply pipe 53 on the inner layer side is ejected from a plurality of ejection ports and mixed (lean premixing) with the primary air A1 taken from the air introduction port 52. Similarly, the secondary gas fuel G2 supplied to the fuel supply pipe 53 on the outer layer side is ejected from a plurality of ejection ports and mixed with the secondary air introduced from the air introduction port 61 (lean premixing).

  The air-fuel mixture premixed in the inner layer 5 is supplied with the swirl component by the swirler 54 and then supplied to the combustion part B, and the air-fuel mixture premixed in the outer layer 6 is supplied to the combustion part B as it is. As a result, the air-fuel mixture premixed in the inner layer 5 and the air-fuel mixture premixed in the outer layer 6 undergo lean premix combustion in the combustion section B.

  The gas fuel supplied to the tertiary burner 7 is introduced from the supply path 71. The introduced gaseous fuel passes through the tertiary burner 7, is jetted from the fuel jet 72 to the combustion section B, is diffused into the air-fuel mixture supplied from the secondary burner 4, and is richly diffusively burned. Note that the gas fuel supplied to the tertiary burner 7 is responsible for reducing combustion with an appropriate air ratio for the entire gas fuel supplied to the combustion section B as a whole. Thereby, the gas fuel supplied to the tertiary burner 7 is a gas fuel for reducing combustion.

  When the load is small, the fuel supply pipe 63 on the outer layer side can be closed and the air inlet 61 on the outer layer side can be closed to reduce the heating power (output) of the gas burning burner 1.

  FIG. 4 is a diagram showing the relationship between the air ratio and the nitrogen oxide emission in the premixed combustion method and the diffusion combustion method. As shown in FIG. 4, compared with the primary burner 3 and the tertiary burner 7 that perform diffusion combustion, the secondary burner 4 that performs lean premixed combustion has a small amount of nitrogen oxide emission, so the gas-burning burner 1 When the weighted average of nitrogen oxide emissions by the ratio of the amount of gas fuel in each burner 3, 4 and 7 to the total amount of gas fuel in the above, gas burned by the amount of lean premixed combustion in the secondary burner 4 The amount of nitrogen oxide discharged from the burner 1 can be reduced.

  FIG. 5 is a diagram showing the flow velocity distribution of the diffuser and the swirler. As shown in FIG. 5, in the diffuser, the flame propagation velocity distribution changes greatly. As a result, when a diffuser is used for flame holding, if the gap between the throat and the diffuser is not sufficiently adjusted, unstable combustion may occur and flashback may occur. On the other hand, since the swirler has a uniform flame propagation velocity distribution, unstable combustion due to the flame propagation velocity distribution can be avoided. Accordingly, the gas burning burner 1 according to the embodiment of the present invention can avoid unstable combustion due to the flame propagation velocity distribution.

  The gas-burning burner 1 according to the embodiment of the present invention described above can reduce the emission amount of nitrogen oxide (NOx) by performing lean premixed combustion by the secondary burner 4. In addition, since the gas fuel for flame holding combustion is diffusely burned, the possibility of backfire is reduced and the adjustment of the primary burner is facilitated. In addition, although reduction combustion (superconcentration diffusion combustion) is performed for the gas fuel for reduction combustion, the reduction effect of the nitrogen oxide emission amount is not greatly impaired.

  Further, since the flame is held by the swirler 54, the flame propagation velocity distribution becomes uniform, and unstable combustion due to the flame propagation velocity distribution is avoided.

  Further, since the secondary burner 4 is formed in a cylindrical two-layer structure with the primary burner 3 as the center, the outer layer side fuel supply pipe 63 is closed and the outer layer side air inlet 61 is closed. In addition, the heating power (output) of the gas burning burner 1 can be reduced.

  By the way, the phenomenon that the flame is drawn into the burner throat 21 and becomes small when the operation load passes through the low load region at the time of starting up and shutting down the new gas-burning burner 1 described above has been confirmed. . If the operation is continued with this phenomenon occurring, combustion vibration may occur.

  As a cause of the flame being drawn into the burner throat 21 as described above, in the gas-fired burner 1, as shown in FIG. 6, the diffusion flames F 1 and F 3 by the primary burner 3 and the tertiary burner 7 and the secondary burner 4 It is conceivable that a plurality of stable ignition positions can be formed because the premixed flame F2 due to (1) coexists (for example, the ignition position A and the ignition position B illustrated in FIG. 6). Since the premixed flame of the secondary burner has good ignitability and high flame propagation speed, if the flame propagation speed exceeds the air flow velocity at low load when the supplied combustion air flow rate is low, the flame is drawn into the burner throat 21. Sometimes.

  On the other hand, the present inventor has found out a technique for suppressing the drawing of flame into the burner throat 21 when the gas-fired burner 1 is started up and after it is lowered. First, the starting method of the gas burning burner 1 for suppressing the drawing of the flame into the burner throat 21 is demonstrated using FIG.6 and FIG.7.

FIG. 7 is a diagram showing a startup flow of the gas burning burner 1 according to one embodiment.
First, in S11 to S13, a primary burner start-up process for starting the primary burner 3 by starting supply of gas fuel for flame holding combustion from the primary burner 3 to the combustion section B is performed. Specifically, supply of primary air to the combustion section B is started via the inner layer 5 of the secondary burner 4 in S11. Next, in S12, supply of gas fuel for flame holding combustion from the primary burner 3 to the combustion section B is started. As a result, the diffusion flame F1 using the primary air and the gas fuel for flame holding combustion is formed (the primary burner is started up). In S13, it is confirmed that the diffusion flame F1 (flame holding) is formed by the primary air and the gas fuel for flame holding combustion.

  Next, in S14 to S16, a tertiary burner start-up process is performed in which the tertiary burner 7 is started by starting to supply gas fuel for reducing combustion from the tertiary burner 7 to the combustion section B. Specifically, supply of secondary air to the combustion section B is started via the outer layer 6 of the secondary burner 4 in S14. Then, in S15, supply of reducing combustion gas fuel from the tertiary burner 7 to the combustion section B is started. Thereby, the diffusion flame F3 using the primary air, the secondary air, and the gas fuel for reducing combustion is formed (the tertiary burner is started up). Further, in S16, it is confirmed that the ignition position is stable only by the diffusion flame F1 by the primary burner 3 and the diffusion flame F3 by the tertiary burner 7 (S16).

  Finally, in S17, the premixed combustion fuel F2 is formed by starting to supply the premixed combustion fuel gases G1 and G2 to the secondary burner 4 (secondary burner starting process), and the gas-burning burner 1 is started. To complete.

  As described above, in the startup flow of the gas burning burner 1 shown in FIG. 7, the secondary burner startup process is performed after the primary burner startup process and the tertiary burner startup process. Thereby, the ignition position is stabilized at a position far from the burner throat 21 (for example, the ignition position B in FIG. 6) only by the diffusion flame F1 formed by the primary burner 3 and the diffusion flame F3 formed by the tertiary burner 7. After that, the premixed flame F2 of the secondary burner 4 can be formed.

  The premixed flame has a high flame propagation speed and is likely to cause a flame drawing into the burner throat 21, whereas the diffusion flame has a low flame propagation speed and is unlikely to cause a flame drawing into the burner throat. For this reason, as described above, after the ignition position is stabilized at a position far from the burner throat 21 only by the diffusion flame F1 formed by the primary burner 3 and the diffusion flame F3 formed by the tertiary burner 7, If the premixed flame F2 of the secondary burner 4 is formed, it is possible to effectively suppress the flame from being drawn into the burner throat 21 when the gas-fired burner 1 is started up.

  Next, a method for lowering the gas burning burner 1 for suppressing the drawing of flame into the burner throat 21 will be described with reference to FIGS. 6 and 8.

  FIG. 8 is a diagram illustrating a flow of lowering the gas burning burner 1 according to an embodiment.

  First, in S21 and S22, a secondary burner lowering process for lowering the secondary burner 4 by stopping the supply of gas fuel for premixed combustion to the secondary burner 4 is performed. Specifically, the supply of gas fuel for premixed combustion to the secondary burner 4 is stopped in S21, and the extinction of the premixed flame F2 is confirmed in S22.

  Next, in S23 and S24, a tertiary burner lowering process for lowering the tertiary burner 7 by stopping the supply of gas fuel for reducing combustion from the tertiary burner 7 to the combustion section B is performed. Specifically, the supply of gas fuel for reducing combustion from the tertiary burner 7 to the combustion section B is stopped in S23, and the supply of secondary air from the secondary burner 4 is stopped in S24.

  Then, in S25 to S27, a primary burner lowering process for lowering the primary burner 3 by stopping the supply of gas fuel for flame holding combustion from the primary burner 3 to the combustion section B is performed. Specifically, the supply of gas fuel for flame holding combustion from the primary burner 3 to the combustion section B is stopped in S25, the supply of primary air from the secondary burner 4 is stopped in S26, and in S27. After confirming that the diffusion flame F1 has been extinguished, the primary burner 1 is finished being lowered.

  As described above, in the flow of lowering the gas burning burner 1 shown in FIG. 8, the secondary burner lowering step is performed before the primary burner lowering step and the tertiary burner lowering step. As a result, the secondary burner 4 is preliminarily maintained in a state where the ignition position is stabilized at a position far from the burner throat 21 by the diffusion flame F1 formed by the primary burner 3 and the diffusion flame F3 formed by the tertiary burner 7. It becomes possible to extinguish the mixed flame F2.

  The premixed flame has a high flame propagation speed and is likely to cause a flame drawing into the burner funnel 21, whereas the diffusion flame has a low flame propagation speed and is unlikely to cause a flame drawing into the burner throat. For this reason, in the state where the ignition position is stabilized at a position far from the burner throat 21 by the diffusion flame F1 formed by the primary burner 3 and the diffusion flame F3 formed by the tertiary burner as described above, If the premixed flame of the burner 4 is extinguished, the premixed flame of the secondary burner 4 can be effectively suppressed from being drawn into the burner throat 21 until just before the secondary burner 4 is extinguished.

  FIG. 9 is a diagram showing a startup flow of the gas burning burner 1 according to one reference embodiment.

  In the startup flow shown in FIG. 9, S31 to S34 are the same as S11 to 14 shown in FIG. 7, and S35 to S37 are different from S15 to S17 shown in FIG. In the startup flow shown in FIG. 9, the premixed flame F2 is formed by starting the supply of the premixed combustion fuel gas to the secondary burner 4 in S35. Next, in S36, it is confirmed that the premixed flame F2 is formed around the diffusion flame F1 (flame holding) formed by the primary burner 3. Then, in S37, gas fuel for reduction combustion is started to be supplied from the tertiary burner 7 to the combustion section B, thereby forming the diffusion flame F3 and completing the start-up of the gas burning burner 1.

  As described above, in the startup flow of the gas burning burner 1 shown in FIG. 9, the secondary burner startup process is performed after the primary burner startup process (S31 to S33) and before the tertiary burner startup process (S37). (S34 to S36) are performed. When the gas-burning burner 1 is started up in such an order, the ignition position of the tertiary burner 7 by the diffusion flame F3 is stabilized at a far position as compared with the startup flow of the gas-burning burner 1 shown in FIG. Since the effect cannot be obtained when the secondary burner 4 is started up, the premixed flame is easily drawn into the burner throat 21.

  FIG. 10 is a diagram showing a flow of the gas burning burner 1 according to one reference embodiment.

  In the startup flow shown in FIG. 10, S44 to S47 are the same as S24 to 27 shown in FIG. 8, and S41 to S43 are different from S21 to S23 shown in FIG. In the falling flow shown in FIG. 10, first, the supply of gas fuel for reducing combustion from the tertiary burner 7 to the combustion section B is stopped in S41. Next, in S42, the supply of the gas fuel for premixed combustion to the secondary burner 4 is stopped, and in S43, the extinction of the premixed flame F2 is confirmed. And the fall process of a primary burner is performed similarly to S24-27 by S44-S47.

  As described above, in the gas-burning burner 1 lowering flow shown in FIG. 10, the secondary burner lowering step is performed after the tertiary burner lowering step (S41) and before the primary burner lowering step (S44 to S47). (S42 to S43) are performed. When the gas-burning burner 1 is lowered in this order, the third-burner 7 is lowered until the secondary burner 4 is lowered as compared with the flow of the gas-burning burner 1 shown in FIG. During this period, the effect of stabilizing the ignition position of the tertiary burner 7 due to the diffusion flame at the far position cannot be obtained, so that the flame is likely to be drawn into the burner throat 21.

  As described above, when the gas-fired burner 1 is started up, it is desirable to perform the secondary burner start-up step after the primary burner start-up step and the tertiary burner start-up step. Thereby, the ignition position is stabilized at a position far from the burner throat 21 (for example, the ignition position B in FIG. 6) only by the diffusion flame F1 formed by the primary burner 3 and the diffusion flame F3 formed by the tertiary burner 7. After that, the premixed flame F2 of the secondary burner 4 can be formed. Therefore, it is possible to effectively suppress the flame from being drawn into the burner throat 21 when the gas burning burner 1 is started up.

  Further, when the gas-fired burner 1 is lowered, it is desirable to perform the secondary burner lowering step before the primary burner lowering step and the tertiary burner lowering step. As a result, the secondary burner 4 is preliminarily maintained in a state where the ignition position is stabilized at a position far from the burner throat 21 by the diffusion flame F1 formed by the primary burner 3 and the diffusion flame F3 formed by the tertiary burner 7. It becomes possible to extinguish the mixed flame F2. Therefore, it is possible to effectively suppress the flame from being drawn into the burner throat 21 until immediately before the secondary burner 4 is extinguished.

  The start-up flow and the start-down flow of the gas burning burner 1 described with reference to FIGS. 7 and 8 may be performed manually or, as shown in FIG. 11, the control unit 74 provided in the gas burning burner 1. You may control by.

  When the control unit 74 of the gas burning burner 1 performs the above-described start-up, the control unit 74 starts the primary burner 3 by starting supply of gas fuel for flame holding combustion to the combustion unit B. Burner start-up control, secondary burner start-up control for starting up the secondary burner 4 by starting the supply of gas fuel for premixed combustion to the secondary burner 4, and reducing combustion gas fuel for the combustion section B And a third burner start-up control for starting up the third burner 7 by starting the supply to the start-up controller 76. In this case, the startup control unit 76 is configured to perform the secondary burner startup control after the primary burner startup control and the tertiary burner startup control.

  When the control unit 74 of the gas burning burner 1 performs the above-described lowering, the control unit 74 lowers the primary burner 3 by stopping the supply of the gas fuel for flame holding combustion to the combustion unit B. Primary burner lowering control, secondary burner lowering control for lowering secondary burner 4 by stopping supply of gas fuel for premixed combustion to secondary burner 4, and reduction combustion to combustion section B And a third burner lowering control for lowering the third burner 7 by stopping the supply of the gas fuel. In this case, the fall controller 78 is configured to perform secondary burner fall control before the primary burner fall control and the tertiary burner fall control.

  The gas-burning burner according to the present invention can suppress the drawing of flame into the burner throat and reduce the emission of nitrogen oxides (NOx) alone. It is suitable for a gas-fired burner constituting a package boiler.

DESCRIPTION OF SYMBOLS 1 Burner 2 Furnace wall 21 Burner throat 3 Primary burner 31 Fuel outlet 32 Fuel introduction part 4 Secondary burner
5 Inner layer 51 Outlet end face 52 Air inlet (first air inlet)
53 Fuel supply pipe (first fuel supply pipe)
54 Swirler 6 Outer layer 61 Air inlet (second air inlet)
62 Vane 63 Fuel supply pipe (second fuel supply pipe)
64 Valve 7 Tertiary burner 71 Supply path 72 Fuel injection port 74 Control unit 76 Startup control unit 78 Startup control unit B Combustion unit A1 Primary air A2 Secondary air G1 Primary gas fuel G2 Secondary gas fuel

Claims (9)

A method for operating a gas-fired burner,
The gas-fired burner is
A primary burner for supplying gas fuel for flame holding combustion to the combustion section;
A secondary burner that is provided around the primary burner and surrounds the primary burner, wherein the premixed combustion gas fuel and air are lean premixed, and the lean premixed mixture is supplied to the combustion section; ,
A tertiary burner provided on the outer periphery of the secondary burner so as to face the combustion section, and supplying gas fuel for reducing combustion to the combustion section;
With
A primary burner start-up step of starting the primary burner by starting to supply the gas fuel for flame holding combustion to the combustion section;
A secondary burner start-up step of starting the secondary burner by starting to supply the premixed combustion gas fuel;
A tertiary burner startup step of starting up the tertiary burner by starting to supply the gas fuel for reducing combustion to the combustion section;
Including
The method of operating a gas-fired burner, wherein the secondary burner startup process is performed after the primary burner startup process and the tertiary burner startup process. The secondary burner is formed in a cylindrical two-layer structure centered on the primary burner,
Each of the inner layer and the outer layer in the cylindrical two-layer structure is configured such that the premixed combustion gas fuel and the air are lean premixed, and the lean premixed mixture can be supplied to the combustion unit.
In the step of starting up the primary burner, air supplied from at least an inner layer to the combustion section in the cylindrical two-layer structure is used for starting up the primary burner,
The tertiary burner start-up step uses air supplied to the combustion section from at least an outer layer of the cylindrical two-layer structure to start up the tertiary burner. The operation method of the gas burning burner described.   3. The gas-burning burner operating method according to claim 1, wherein, in the secondary burner start-up step, the primary burner and the tertiary burner do not supply air to the combustion section. A method for operating a gas-fired burner,
The gas-fired burner is
A primary burner for supplying gas fuel for flame holding combustion to the combustion section;
A secondary burner that is provided around the primary burner and surrounds the primary burner, wherein the premixed combustion gas fuel and air are lean premixed, and the lean premixed mixture is supplied to the combustion section; ,
A tertiary burner provided on the outer periphery of the secondary burner so as to face the combustion section, and supplying gas fuel for reducing combustion to the combustion section;
With
A primary burner lowering step of lowering the primary burner by stopping the supply of the gas fuel for flame holding combustion to the combustion unit;
A secondary burner lowering step of lowering the secondary burner by stopping the supply of gas fuel for premixed combustion;
A tertiary burner lowering step of lowering the tertiary burner by stopping the supply of the gaseous fuel for reducing combustion to the combustion unit;
Including
The method for operating a gas-fired burner, wherein the secondary burner lowering step is performed before the primary burner lowering step and the tertiary burner lowering step. The secondary burner is formed in a cylindrical two-layer structure centered on the primary burner,
Each of the inner layer and the outer layer in the cylindrical two-layer structure is configured such that the premixed combustion gas fuel and the air are lean premixed, and the lean premixed mixture can be supplied to the combustion chamber.
In the primary burner lowering step, the supply of the gas fuel for flame holding combustion to the combustion unit is stopped, and then the air supply to the inner layer is stopped,
5. The gas according to claim 4, wherein, in the tertiary burner startup step, the supply of the gas fuel for reducing combustion to the combustion unit is stopped, and then the air supply to the outer layer is stopped. How to operate a burning burner.   The method for operating a gas-fired burner according to claim 5, wherein, in the step of lowering the secondary burner, the primary burner and the tertiary burner do not supply air to the combustion section.   The gas-burning burner according to any one of claims 1 to 5, wherein the primary burner and the tertiary burner do not have an air supply pipe for supplying air to the combustion unit. how to drive. A primary burner for supplying gas fuel for flame holding combustion to the combustion section;
A secondary burner that is provided around the primary burner and surrounds the primary burner, wherein the premixed combustion gas fuel and air are lean premixed, and the lean premixed mixture is supplied to the combustion section; ,
A tertiary burner provided on the outer periphery of the secondary burner so as to face the combustion section, and supplying gas fuel for reducing combustion to the combustion section;
A control unit for controlling the primary burner, the secondary burner and the tertiary burner;
A gas-burning burner comprising
The control unit starts supply of the primary burner by starting supply of the gas fuel for flame holding combustion to the combustion unit, and starts supplying gas fuel for the premixed combustion. A secondary burner start-up control for starting up the secondary burner, and a tertiary burner start-up control for starting up the tertiary burner by starting to supply the gas fuel for reducing combustion to the combustion section. Including a launch controller configured to be executable,
The gas-burning burner, wherein the start-up control unit is configured to perform the secondary burner start-up control after the primary burner start-up control and the tertiary burner start-up control. A primary burner for supplying gas fuel for flame holding combustion to the combustion section;
A secondary burner that is provided around the primary burner and surrounds the primary burner, wherein the premixed combustion gas fuel and air are lean premixed, and the lean premixed mixture is supplied to the combustion section; ,
A tertiary burner provided on the outer periphery of the secondary burner so as to face the combustion section, and supplying gas fuel for reducing combustion to the combustion section;
A control unit for controlling the primary burner, the secondary burner and the tertiary burner;
A gas-burning burner comprising
The control unit is configured to stop the primary burner by stopping the supply of the gas fuel for flame holding combustion to the combustion unit, and to supply the gas fuel for the premixed combustion. The secondary burner lowering control for lowering the secondary burner by stopping the combustion, and the tertiary burner starting to lower the tertiary burner by stopping the supply of the gas fuel for reducing combustion to the combustion section And a fall control unit configured to be executable,
The gas-burning burner, wherein the lowering control unit is configured to perform the secondary burner lowering control before the primary burner lowering control and the third burner lowering control.

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