JP4261401B2 - Burner, fuel combustion method and boiler remodeling method - Google Patents

Description

  The present invention relates to a burner and a fuel combustion method using the burner. The present invention also relates to a method for remodeling a boiler having an existing burner into a boiler having a burner according to the present invention.

  Burners used in boilers, etc. are required to respond to load changes, support multiple coal types, reduce nitrogen oxide (NOx) concentration, reduce unburned components, etc., and control the combustion state to meet these requirements. Various methods have been developed. For example, the distribution of secondary and tertiary air flow by the air register, the swirl number change, and the like.

  As one of the methods for controlling the combustion state, a method has been proposed in which the partition wall separating the secondary air and the tertiary air is movable so as to adjust the secondary air flow rate and adjust the air ejection direction (for example, (See Reference 1).

Japanese Patent Publication No. 60-26922 (Claims)

  In Patent Document 1, since the flow of the secondary air can be controlled by moving the partition back and forth, the combustion of the secondary flame can be performed under the best conditions in terms of low NOx and combustion efficiency. Are listed.

  An object of the present invention is to further cool the burner while reducing NOx.

  The present invention has a tubular secondary nozzle so as to surround or contact the primary nozzle outside the primary nozzle that supplies fuel and primary air, and the outside of the secondary nozzle. A burner having a tubular tertiary nozzle so as to surround the secondary nozzle or in contact with the secondary nozzle, and having a tubular partition wall separating the nozzles between the secondary nozzle and the tertiary nozzle. The partition wall is provided with a flow path changing member that allows the fluid flowing through the tertiary nozzle to be ejected outward, and the partition wall can be moved in parallel with the burner axis. Secondary air is supplied to the secondary nozzle, and tertiary air is supplied to the tertiary nozzle. In the present invention, the burner axis means the central axis of the tubular primary nozzle.

  By moving the partition provided with the flow path changing member in the direction parallel to the burner axis, the tertiary air ejection cross-sectional area of the tertiary nozzle changes, and the flow rate and flow velocity of the tertiary air change. If the flow rate of the tertiary air changes, the flow rate and flow rate of the secondary air change accordingly. The combustion state changes as the flow rate of the tertiary air or the flow rate of the secondary air changes, and the heating temperature of the burner tip also changes accordingly. As a result, the temperature of the burner component can be lowered.

  The triple tube structure burner targeted by the present invention ignites fuel with primary air to form a reducing flame to reduce NOx, and this reducing flame is mixed with secondary air and tertiary air for reduction. The unburned portion contained in the flame is burned and is known as a two-stage combustion burner in the flame. In this burner, if the mixing of the tertiary air is delayed, the area of the reducing flame becomes larger, and the reduction of NOx is promoted. As seen in Patent Document 1, many burners having this structure are provided with a flame holder at the outlet of the tubular primary nozzle. In the present invention, a flame holder is also provided at the outlet of the primary nozzle. it can. The flame holder is provided with an internal flame holder in which a ring-shaped protrusion is formed on the inner side of the outlet of the tubular primary nozzle, and a cylindrical protrusion so as to protrude in the burner axial direction on the outer side of the outlet of the tubular primary nozzle. There is an external flame holder, and it is desirable to have both of these. When the flame holder is provided, a circulation flow region by turbulent vortices is formed in the subsequent flow, and fuel, for example, pulverized coal particles is entrained to become a high-temperature gas fire type and ignition of the pulverized coal is promoted. Here, the secondary air plays a role of cooling the flame holder and adjusting the mixing ratio of fuel and air.

  As the flow path changing member, a member having a tapered slope so that the tertiary air flows from the flow parallel to the burner axis to the outside gradually changes. Further, it is desirable that the back surface side of the flow path changing member, that is, the side in contact with the secondary air is formed so as to be inclined along the inclined surface on the tertiary nozzle side. In this way, when the flow path changing member is moved so that the ejection cross-sectional area of the tertiary air is reduced, the ejection cross-sectional area of the secondary air is increased accordingly.

  In order to make it easy to move the partition without complicating the structure of the burner, the partition is composed of a fixed wall and a movable wall, and the movable wall slides and moves on the surface of the fixed wall. It is desirable to do. Specifically, the part where the tertiary air flows parallel to the burner axis is a fixed wall, and the part whose direction is changed from the flow parallel to the burner axis to the outside, that is, the part provided with the flow path changing member Is preferably a movable wall. The fixed wall is preferably provided with a guide roller to assist the movement of the movable wall. Moreover, it is desirable to provide a stopper for stopping the movement of the movable wall on one or both of the fixed wall and the movable wall. Furthermore, since the flow path changing member and the partition wall in the vicinity thereof are easily heated to a high temperature, it is desirable to provide a cooling fin there. Further, as a means for moving the movable wall, it is preferable to attach a rod-shaped member to the movable wall and move it back and forth manually or automatically. At this time, if the tip of the rod-like member is extended so as to go out of the burner's wind box, maintenance is easy and failure is unlikely. The tip of the rod-shaped member can be moved manually by pulling or pushing. Furthermore, if a gear is installed at the end of the rod-shaped member and moved to the front and rear using a gear that fits the gear and a handle attached to the gear, it can be easily moved. Further, if a motor is provided instead of the handle, the movement can be saved, and automation by control becomes possible.

  The burner of the present invention can be used for fuels that use oil, gas, pulverized coal, etc., but is particularly suitable for those that use pulverized coal. In the pulverized coal burner, an oil burner for assisting combustion is provided in the primary nozzle to assist combustion when the load is low, but the oil burner can also be provided in this manner in the burner of the present invention.

  The burner of the present invention can be added with a tertiary air bypass mechanism in which a part of the tertiary air is bypassed to other nozzles. This tertiary air bypass mechanism is formed such that when the partition wall that partitions the secondary nozzle and the tertiary nozzle moves to a predetermined position, the tertiary air bypasses and flows to the other nozzles. If a hole is made in the movable wall, and a hole is made in the fixed wall so as to communicate with the hole when the movable wall moves to a predetermined position, a part of the tertiary air is bypassed and the secondary nozzle is bypassed. To flow into. Although the number of holes in the movable wall or the fixed wall may be one, it is desirable to provide a plurality of holes along the circumferential direction in order to increase the flow rate of the tertiary air.

  If a hole is formed in the primary nozzle and the hole and the hole provided in the fixed wall are connected by a bypass pipe, the tertiary air can be flowed to the primary nozzle. If the bypass pipe is configured such that the tertiary air is ejected from the inner wall of the primary nozzle along the fuel flow direction, the flame holder can be cooled by the tertiary air flowing through the primary nozzle.

  In the present invention, when the fuel is burned using the burner, if the temperature of the flow path changing member becomes higher than the set temperature, the partition partitioning the secondary nozzle and the tertiary nozzle is moved to move the tertiary. Provided is a combustion method for reducing the tertiary air ejection cross-sectional area of a nozzle and increasing the flow rate of the tertiary air. Further, the present invention provides a combustion method in which when ash comes to adhere to the burner during combustion, the partition wall is moved to increase the tertiary air ejection cross-sectional area of the tertiary nozzle to slow the tertiary air flow rate. Further, a method is provided in which the partition wall is moved to reduce the tertiary air ejection cross-sectional area of the tertiary nozzle and to increase the flow rate of the secondary air when the fuel is not supplied to the burner. Further, there is provided a method of bypassing a part of the tertiary air supplied to the tertiary nozzle and flowing it to the secondary nozzle or the primary nozzle when the fuel supply to the burner is stopped. In addition, when the NOx concentration is high or fuel with poor flammability is used, an operation for increasing the tertiary air amount is performed by reducing the cross-sectional area of the tertiary air in order to increase the momentum of the tertiary air. Provide a method.

  Furthermore, the present invention provides a boiler having an existing burner in which a tubular partition wall that separates the secondary nozzle and the tertiary nozzle is fixed. Provided is a boiler remodeling method in which a tubular partition wall provided with a changing member is movably installed.

  The burner of the present invention is a two-stage combustion system in a flame and is excellent in reducing NOx. According to the present invention, it is possible to cool the burner while reducing NOx, and to suppress burner damage due to ash adhesion or heat on the burner. In the present invention, the direction of the tertiary air ejection is constant outward and the momentum of the tertiary air is changed, so that the size of the circulating flow can be optimized within a range that does not become small and the combustion state is good. It becomes possible to keep on. Moreover, even if the tertiary air flow rate is constant, the guide sleeve can be cooled because the flow velocity at the tip of the guide sleeve can be increased. Furthermore, by controlling the momentum and flow rate of the tertiary air independently, the size of the flame, which is mainly determined by the momentum, the size of the circulating flow, and the size of the reduction zone, which is determined by the flow rate, can be controlled independently. Can keep the state.

  Hereinafter, a burner of the present invention and a method of using the same will be described with reference to the drawings.

  1, 2, 3, and 4 are cross-sectional views showing an embodiment of a burner according to the present invention. This burner has a triple pipe structure comprising a primary nozzle 4, a secondary nozzle 8 and a tertiary nozzle 9. From the primary nozzle 4, primary air and pulverized coal flow as indicated by an arrow 11. In the present embodiment, the case where pulverized coal is used as the fuel is shown, but the same applies to oil, gas, and the like. The primary nozzle 4 is tubular and has a circular or square cross section. There is a partition between the secondary nozzle 8 and the tertiary nozzle 9, and this partition is composed of a fixed wall 1 and a movable wall 2. A guide sleeve 3 is attached to the tip of the movable wall 2. The guide sleeve 3 serves to change the flow of tertiary air outward. Secondary air flows from the secondary nozzle 8 as indicated by an arrow 12. Further, tertiary air flows from the tertiary nozzle 9 as indicated by an arrow 13. The movable wall 2 is connected to the movement control rod 5 at the connection portion 14, and a handle 33 for operation is attached to the outside of the wall 28 of the wind box.

  A cylindrical flame holder 10 is provided at the tip of the primary nozzle 4. An air register 7 is provided upstream of the tertiary nozzle 9. Further, a tertiary damper 35 is attached upstream of the tertiary nozzle, and a secondary damper 34 is attached upstream of the secondary nozzle.

  The movable wall 2 and the guide sleeve 3 installed at the tip thereof move in the front-rear direction, that is, in a direction parallel to the burner axis, so that the flow rate and flow rate of the tertiary air, the flow rate and flow rate of the secondary air, and the tertiary air flow rate. It is possible to control the combustion state by changing the ratio of the secondary air flow rate. This is the same as changing the ratio of the momentum of the tertiary air and the secondary air. In the present invention, the flow rate and momentum of the tertiary air can be changed by keeping the ejection angle of the tertiary air constant and changing the outlet cross-sectional area of the tertiary air. By always directing the tertiary air to the outside, the size of the circulating flow formed downstream of the flame stabilizer 10 and the guide sleeve 3 can always be increased, so that the combustion state can be kept good. The momentum of the tertiary air is the main factor that determines the size of the flame and the size of the circulating flow, and the flow rate of the tertiary air is the main factor that determines the size of the reduction zone. Since the momentum and flow rate of the tertiary air can be controlled independently, it is possible to achieve a combustion state suitable for improving flame holding properties and reducing NOx. Furthermore, the momentum of the tertiary air and the secondary air flow rate can be changed independently. Thereby, the secondary air can be used for other purposes such as cooling the flame holder 10 and supplying air to the fuel flowing through the primary nozzle 4.

  FIG. 3 is a cross-sectional view taken along the line AA in FIG. FIG. 4 is a cross-sectional view taken along the line BB in FIG. A tire 23 is attached so that the movable wall 2 moves smoothly. In this example, four movement control rods 5 are provided, which is suitable for moving in parallel with the burner axis. The tire 23 is installed on the fixed wall 1, but may be installed on the movable wall 2.

  The movable wall 2 may increase in temperature when the flow rate of the tertiary air is small. When the temperature of the member is equal to or higher than the heat resistance temperature of the material, burning and deformation are likely to occur. Therefore, it is preferable to use a material having a high heat resistance temperature for the movable wall.

Below, the adjustment method at the time of the test run of a burner is demonstrated first. Immediately after installing the burner in the boiler, the expected flow rate may not flow. This may be due to burner manufacturing errors, asymmetry of the upstream duct, setting errors of the resistors and dampers installed in the burner, and the like. Also, it may be necessary to set the air flow rate according to the fuel bias for each burner. Therefore, by adjusting the air register 7, the tertiary damper 35, the secondary damper 34, and the movable wall 2 of the tertiary nozzle, it is suitable for reducing NOx, CO, unburned matter, soot and corrosion, and reducing the metal temperature of the burner section. Set to a burning state. Below, the example of the adjustment method is shown.
(Example 1) When the flame holding property is poor, the following operation is performed to improve the flame holding property.
(1.1) When the momentum of the tertiary air is low: The movable wall 2 is moved to the near side (the left side in FIG. 1) to narrow the channel area of the tertiary nozzle. If this is the case, the pressure loss of the tertiary air increases, so the tertiary air flow rate decreases and the secondary air flow rate increases. In order not to change the flow rate, the air register 7 or the tertiary damper 35 of the tertiary nozzle is opened. Alternatively, the secondary damper 34 is closed so that the secondary air does not flow. By increasing the momentum of the tertiary air, the circulation region of the wake flow of the flame holder 10 is increased and the flame holding performance is improved.
(1.2) When the secondary air momentum is low: When the secondary air amount may be increased, close the air register 7 of the tertiary nozzle to strengthen the turning, or move the movable wall 2 toward you. The tertiary air flow rate should be increased. By increasing the flow rate and momentum of the secondary air, the circulation region downstream of the flame holder 10 is increased and the flame holding property is improved. However, if the secondary air is excessively increased, the circulating flow may be reduced. There is an optimal flow rate in the secondary air. In FIG. 2, the movement of the movable wall 2 increases the minimum flow path area between the flame holder 10 and the guide sleeve 3. For this reason, the ejection flow rate of secondary air may be lowered. If the flow velocity is low, the cooling effect of the flame holder 10 is reduced. Therefore, even if the movable wall 2 moves, the flame holder 10 is lengthened in the moving direction of the movable wall 2 so that the minimum flow path area does not change. It is good to keep.
(Example 2) When the NOx concentration is high, adjustment is made by the following method.
(2.1) Since the NOx concentration decreases when the flame holding property is increased, the above flame holding property is set to be improved.
(2.2) Although the flame is sufficiently retained, if it is desired to further reduce the NOx concentration, it is effective to delay the mixing of air. In order to delay the mixing, it is effective to lower the secondary air and increase the flow rate of the tertiary air. For this purpose, it is conceivable to close the secondary damper 34 or open the movable wall 2. Further, the momentum of the tertiary air may be increased. Mixing can also be delayed by closing the air register 7 of the tertiary nozzle to strengthen the swirling of the tertiary air. In this case, it is necessary to close the secondary damper 34 so that the flow rate of the tertiary air does not decrease.
(Example 3) If the unburned content is high, adjust by the following method.
(3.1) If the flame is not held, there is a possibility that the unburned content will be high. Therefore, it is effective to make the same setting as that for improving the flame holding property.
(3.2) Although the flame is sufficiently retained, it is effective to increase the secondary air when it is desired to further reduce the unburned amount. In this case, if the secondary damper 34 is opened, there is a possibility that the momentum of the tertiary air is lowered and the flame holding property is lowered. Therefore, it is effective to increase the tertiary air flow rate by moving the movable wall 2 to the front or to close the air register 7 of the tertiary nozzle to strengthen the turning.
(3.3) Increasing the burner air ratio is effective in reducing the unburned content. Increasing the burner air ratio increases the air flow rate, improves the mixing of fuel and air, and increases the NOx concentration. In order to reduce the NOx concentration, the method shown in Example 2 is applied.
(Example 4) In order to reduce corrosion, the following method is used.
(4.1) If the air near the wall is insufficient, the concentration of the reducing gas increases and the corrosion rate increases. To supply air near the wall, it is effective to increase the tertiary air flow rate. Therefore, it is effective to open the movable wall 2 to increase the flow area of the tertiary nozzle and increase the tertiary air flow rate. Further, the secondary damper 34 may be closed to increase the momentum of the tertiary air so that the air reaches the vicinity of the wall.
(4.2) Since the flame holding may be deteriorated to reduce the reducing gas, the operation reverse to that in Example 1 may be performed.
(4.3) Reducing gas can be reduced and corrosion can be reduced even if the amount of air in the burner close to the corrosive wall is increased. Therefore, it is effective to adjust the air distribution by adjusting the movable wall 2, the resistor, and the damper for each burner so as to reduce the pressure loss of the burner, which is better to increase the air.
(Example 5) If the type of fuel is to be changed significantly, adjustment is made by the following method.
(5.1) When the type of fuel changes drastically, the pulverization and the amount of volatile components in the fuel change, so the damper opening, the position of the movable wall 2, the air register to maintain flame holding and reduce NOx Change the setting of 7. If the fuel is changed from a fuel having good combustibility to a fuel having poor combustibility, the flame holding ability may be lowered. In this case, it is better to perform an operation to improve flame holding properties.
(5.2) Since fuel with poor flammability is highly likely to have a high NOx concentration, an operation for reducing NOx may be performed.
(Example 6) When ash in the fuel adheres, the following method is used.
(6.1) The flame holding property is good, and when the ash in the fuel melts and adheres to the vicinity of the burner, the movable wall 2 is moved forward to increase the outlet cross-sectional area of the tertiary air. The flow rate of the secondary air is reduced to reduce the flame holding property. In this way, the combustion temperature is lowered, so ash adhesion is reduced. At the same time, the secondary air also increases, the temperature in the vicinity of the flame holder decreases, and the ash can be prevented from melting.
(6.2) When molten ash adheres to the boiler wall, it is preferable to supply air near the wall. For this purpose, it is preferable to move the movable wall 2 to the front, change the ejection direction of the tertiary air to the outside, and supply air near the wall.
(Example 7) When the temperature of the flame holder is high, the following operation is performed.

When the temperature of the flame holder 10 is high, it is effective to increase the flow rate of the secondary air. In order to increase the flow rate of the secondary air, the tertiary damper 35 or the air register 7 is closed. In this case, there is a possibility that the momentum of the tertiary air is lowered and the flame holding property is lowered. Therefore, instead of closing the tertiary damper 35 and the air register 7, the movable wall 2 is moved forward. Thereby, the flame holding property and the decrease in the flame holder temperature can both be achieved.
(Example 8) The boiler minimum load is reduced as follows.

  The boiler load is not always 100%, but is changed according to the power demand. If it can be operated at a very low load, the operability of the boiler will be improved. Normal burners are designed to improve performance at 100% load. When the load is low, the flow rate of fuel entering from the burner and the flow rate of air are reduced, and the balance of momentum is lost, which may cause a decrease in flame holding properties. For example, when the momentum of the tertiary air is low, it is effective to increase the momentum of the tertiary air by moving the movable wall 2 forward. This operation is the same as the method for improving the flame holding property shown in Example 1. However, when the flame holding property is improved at a low load, the combustibility may deteriorate at a high load. It is good to set in the range where the combustion state does not deteriorate even at high load.

  FIG. 5 is a cross-sectional view showing an example of an embodiment of a burner according to the present invention. The difference from the first embodiment is that the motor box 6 is installed and the movable wall 2 is moved electrically. In FIG. 5, the motor box is installed in the window box, but it may be outside the window box. An air register 15 is installed in the secondary nozzle 8. By combining the air register 15 and the secondary damper 34, the flow rate and the turning force can be controlled.

  The merit of moving the movable wall 2 by electric power is that the movable wall 2 can be controlled according to the combustion adjustment algorithm shown in the first embodiment, and can always be kept in an optimal combustion state. In addition, as shown below, a suitable operation state can be obtained by changing the flow rate condition.

  The burner may enter a dormant state where no fuel is supplied. In such a state, the rest burner is heated by the radiant heat from the other ignition burners, and there is a possibility that the temperature of the guide sleeve 3 and the flame holder 10 will rise. In order to prevent this, it is necessary to supply air to the burner even during a pause. If the flow rate of air supplied to the burner during the pause is large, the amount of air adjustment to the other ignition burners decreases. Therefore, it is necessary to reduce the air flow rate of the pause burner. If the flow rate is reduced while the movable wall 2 is fixed, the flow rates of the secondary air and the tertiary air are lowered, and the guide sleeve 3 and the flame stabilizer 10 cannot be sufficiently cooled.

  Therefore, in the present invention, the state shown in FIG. 6 is set when the burner is in a resting state. That is, the movable wall 2 is moved forward, and the area of the tertiary air ejection portion is made almost zero. Since the flow velocity at the tip of the guide sleeve 3 is fast, the guide sleeve can be cooled even with a small amount of tertiary air. Further, by increasing the flow rate of the secondary air, the flow rate of the secondary air can be increased and the flame holder 10 can be efficiently cooled. Since the secondary air has a smaller flow rate than the tertiary air, the overall flow rate can be reduced even if the secondary air is increased.

  In the examples so far, the air register 7 is provided in the tertiary nozzle, but the air register 7 may be omitted. The air register 7 is for controlling the combustion field by turning the tertiary air. This is because the same effect can be obtained by moving the movable wall 2 back and forth in the present invention. Further, the air register 15 of the secondary nozzle is not essential. In this case, the secondary damper 34 is necessary because there is no method for adjusting the flow rate of the secondary air.

  FIG. 7 shows the structure of the control device used in the case of the second embodiment. The control device 101 receives a signal from the measurement device and transmits a signal for moving the movable part of the burner 102. For example, it is a signal for driving the movable wall moving motor 111, the movable motor 112 of the air register 7, the tertiary damper movable motor 113, the secondary damper movable motor 114, the movable motor 115 of the air register 15, or the like. The control device 101 incorporates software that implements the algorithm shown in the first embodiment. Measuring devices installed in the burner 102 include a frame detector 107, a burner metal thermometer 108, a combustion air pressure gauge 109, a burner air flow meter 110, and the like. The measurement device installed in the boiler 116 includes a steam thermometer 103, an ash adhesion sensor 104, a NOx sensor 105, an unburned sensor 106 for measuring CO concentration and solid unburned residue, and the like. For example, the frame detector 107 may be used to check the flame holding property. Among frame detectors, those that can measure the light emission intensity of the flame are good. It is possible to evaluate the good flame-holding property by the intensity of light emission, and if the flame-holding property is lowered, the operation conditions can be changed to improve the flame-holding property. The NOx sensor 105 may be installed on the downstream side of the boiler 116 that has finished the reaction. It is preferable to install a plurality of NOx sensors 105 and adjust the movable wall 2, register, and damper for each burner while examining the concentration distribution. The unburned component sensor 105 may be installed downstream of the boiler 116, similarly to the NOx sensor.

  8, 9, 10 and 11 are sectional views showing other embodiments of the burner according to the present invention. In the example of FIG. 8, holes 16 and 32 for tertiary air bypass are respectively provided in the fixed wall 1 and the movable wall 2 of the partition wall that partitions the secondary nozzle and the tertiary nozzle, and 3 through these holes. The secondary air flows as indicated by an arrow 17 and bypasses to the secondary nozzle 8. In this case, the tertiary air is not always bypassed, and the movable wall 2 is preferably allowed to flow in a state where the fuel supply is stopped as shown in FIG. In this way, even when the movable wall 2 is pulled forward and the secondary air is squeezed, the air is automatically supplied to the secondary nozzle 8 and the temperature of the flame holder 10 rises. Can be prevented. The number of tertiary air bypass holes 16 and 32 is not one, but a plurality of holes can be used to increase the flow rate.

  FIG. 9 shows an example in which the bypassed tertiary air is supplied to the primary nozzle. In this example, a hole is provided in the pipe wall of the primary nozzle 4, and a bypass pipe 18 connects the hole provided in the fixed wall and the hole provided in the primary nozzle. When the burner is at rest, almost no air is supplied into the primary nozzle. For this reason, the inside of the flame holder cannot be cooled. Therefore, as shown in FIG. 9, tertiary air is supplied along the wall of the primary nozzle in a resting state.

  When the oxygen concentration of the primary air transporting the fuel is low, the bypass air flow rate increases as the movable wall 2 comes to the front and the tertiary air ejection cross-sectional area of the tertiary nozzle is smaller. good. In brown coal and the like, the fuel is easily ignited, so the fuel is transported by exhaust gas. When the load of the burner is high, even if the oxygen concentration of the primary air is low, the combustion apparatus, for example, the gas temperature in the boiler is high, so that stable combustion is possible. However, when the load decreases, the gas temperature in the combustion device decreases, and if the oxygen concentration of the primary air is not high, the unburned content increases and misfires occur. When such a load is low, the tertiary air flows to the primary nozzle, so that stable combustion can be achieved. A structure in which tertiary air is always bypassed to the primary nozzle 4 is also conceivable, but combustion is accelerated when the load is high, and the possibility of explosion and ash adhesion increases, so the air flow rate increases as the load decreases. The mechanism to let you do is better.

  FIG. 10 shows an example in which the bypassed secondary air is supplied to the primary nozzle. In this example, a hole is provided in the tube wall of the primary nozzle 4 so that air can be supplied from the secondary nozzle to the primary nozzle by the bypass tube 18. When the burner is at rest, the movable wall 2 is moved forward and the air register 15 is closed to supply secondary air along the wall of the primary nozzle.

  Similarly to the example of FIG. 9, when the oxygen concentration of the primary air is low, it can be stably burned by increasing the amount of air to be bypassed. If it is desired to reduce the combustion rate, the pressure at the intake of bypass air may be reduced. For example, the movable wall 2 may be moved to widen the tertiary air ejection area, or the air register 15 may be opened.

  FIG. 11 shows an example in which bypass tertiary air is used for cooling the pulverized coal concentrator 20 provided in the primary nozzle 4. The pulverized coal concentrator 20 is configured to widen the flow path again after temporarily narrowing the flow path of the primary nozzle, and acts to increase the pulverized coal concentration on the wall surface side of the primary nozzle. In the rest state, since the primary air flow rate is small, it is difficult to cool the pulverized coal concentrator 20. Therefore, the tertiary air is allowed to flow to the pulverized coal concentrator 20 in the resting state. For this purpose, in FIG. 11, a bypass pipe 19 is provided which connects the hole of the fixed wall 1 and the hole of the primary nozzle and further extends to the pulverized coal concentrator 20. The air used for cooling the pulverized coal concentrator is input to the furnace from the tip of the pulverized coal concentrator 20.

  The pulverized coal burner may be provided with an oil burner 30 that sprays the auxiliary combustion oil 21 from the atomizer 31. FIG. 11 shows such an example. By moving the movable wall 2, the ratio between the air flow rate flowing outside and the air flow rate flowing through the center of the burner can be changed. As a result, generation of NOx and soot can be controlled.

  FIG. 12 shows a cross-sectional view of a burner according to another embodiment. In this example, the motor box 6 is installed outside the wall 28 of the wind box. The secondary air and the tertiary air may have a high temperature of 300 ° C. or higher and may contain ash. If the motor box 6 is installed in such a place, there is a possibility of failure, and if it fails, repair is difficult. In this embodiment, the fixed wall 1 is shorter than that in the case of FIG. In this way, even if the portion near the top of the movable wall 2 is deformed by heat, the portion in contact with the fixed wall 1 is in the back of the burner, so that the possibility of hindering movement is reduced.

  Further, it is preferable to provide a stopper 24 on the movable wall 2. It is possible to prevent the movable wall 2 from protruding too far forward due to a sensor failure or the like. Although not shown in FIG. 12, it is also effective to provide a stopper so as not to pull the movable wall 2 by a similar method.

  Further, in FIG. 12, the cooling efficiency is enhanced by installing the cooling fins 22 on the movable wall 2 and the guide sleeve 3. This cooling fin also has the function of increasing the strength.

  In FIG. 12, a temperature sensor 29 is attached to the guide sleeve 3 and the flame holder 10. Based on the value of the temperature sensor, the position of the movable wall 2 can be controlled. In this case, when the temperature at the tip of the guide sleeve is higher than the limit value, the flow rate of the tertiary air is low, and therefore, it is preferable to reduce the secondary air and increase the flow rate of the tertiary air. Further, when the temperature of the flame holder is higher than the limit value, the operation state of Example 7 of Example 1 may be set. When the temperature of the guide sleeve and the flame holder are both higher than the limit value, the entire air flow rate may be increased.

  13, 14, and 15 show various examples in the CC cross section of FIG. 12. The structure of FIGS. 13 to 15 can be applied not only to the burner of FIG. 12 but also to the burner having the structure of FIG. FIG. 13 shows an example in which one motor 25 is used and four movement control rods 5 are moved by the gear 26 and the power transmission shaft 27. There is an advantage that the number of motors can be reduced and the movement amount of the movement control rod 5 can always be the same. FIG. 14 shows an example in which the movement control rod 5 is moved by the handwheel handle 37 without using the motor 25 shown in FIG. FIG. 15 shows an example in which four motors 25 are used and operation is possible with the remaining motors even if one motor fails.

  16, 17, and 18 are sectional views showing other embodiments of the burner according to the present invention. 17 is a DD cross-sectional view of FIG. 16, and FIG. 18 is a EE cross-sectional view of FIG. The difference from FIG. 1 is that the burner is not a triple pipe, the primary nozzle 4 and the secondary nozzle 8 are square pipes, and the tertiary nozzle 9 is divided into two places at the top and bottom of the burner. That is. Even in this case, as in the first embodiment, the movable wall 2 having the guide sleeve 3 can be moved back and forth to achieve an optimum operation state. In the present embodiment, since the movable wall 2 is divided into upper and lower parts, there is a possibility that the movable wall 2 does not move back and forth in conjunction. Therefore, as shown in FIG. 17, the movable wall 2 may be connected by a connecting plate 36. In the present embodiment, as shown in FIG. 18, the handle 33 is installed at four places and the movable wall 2 is moved manually, but it may be moved electrically as in the second embodiment.

  Another example of use of the burner according to the present invention will be described. The horizontal axis in FIG. 19 indicates the burner load. Even if the burner load is 0%, cooling air is allowed to flow. In this case, the movable wall 2 is in a state where the tertiary air outlet is almost fully closed in order to cool the flame holder. Coal-burning burners are supplemented with oil when the load is low, and oil and coal are input. When reaching a load that can be burned only with coal, the oil flow is reduced to zero. If you are burning oil, it is better to increase the air near the center where the oil is being injected, so move the movable wall 2 toward you and make the tertiary air outlet close to full closure. ing. As the coal flow rate increases, the supplied air flow rate increases. Even if the momentum of the tertiary air is low, stable combustion is possible. Therefore, the movable wall 2 is moved to the front, and the tertiary air outlet is enlarged and brought close to full opening.

  According to the present invention, it is possible to cool the burner while controlling the combustion state to an optimum state and reducing NOx. In order to reduce the thermal damage of the burner, the applicability of the burner of the present invention is great.

It is sectional drawing of the burner by one Example of this invention. It is sectional drawing which shows the usage example of the burner by this invention. It is AA sectional drawing of the burner of FIG. It is BB sectional drawing of the burner of FIG. It is sectional drawing which shows the other usage example of the burner by this invention. It is sectional drawing which shows the further another usage example of the burner by this invention. It is a figure which shows the structure of the control apparatus of the burner by this invention. It is sectional drawing which shows the other example of the burner by this invention. It is sectional drawing which shows the other example of the burner by this invention. It is sectional drawing which shows the other example of the burner by this invention. It is sectional drawing which shows the other example of the burner by this invention. It is sectional drawing which shows the other example of the burner by this invention. It is a figure which shows one form in CC cross section of the burner of FIG. It is a figure which shows the other form in CC cross section of the burner of FIG. It is a figure which shows the further another form in CC cross section of the burner of FIG. It is sectional drawing which shows the other example of the burner by this invention. It is DD sectional drawing of the burner of FIG. It is EE sectional drawing of the burner of FIG. It is a line graph which shows a mode that the fuel and air flow supplied from a burner change with burner loads.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fixed wall, 2 ... Movable wall, 3 ... Guide sleeve, 4 ... Primary nozzle, 5 ... Movement control rod, 6 ... Motor box, 7 ... Air register, 8 ... Secondary nozzle, 9 ... Tertiary nozzle, 10 ... Flame holder, 15 ... Air register, 16 ... Hole, 18 ... Bypass pipe, 19 ... Bypass pipe, 20 ... Pulverized coal concentrator, 22 ... Cooling fin, 23 ... Tire, 24 ... Stopper, 25 ... Motor, 26 ... Gear, 29 ... temperature sensor, 30 ... oil burner, 31 ... atomizer, 32 ... hole, 33 ... handle, 34 ... secondary damper, 35 ... tertiary damper, 101 ... control device, 102 ... burner, 116 ... boiler.

Claims (19)

  A primary nozzle for supplying fuel and primary air, a secondary nozzle for supplying secondary air provided outside the primary nozzle, and tertiary air provided in contact with the outside of the secondary nozzle A burner having a tertiary nozzle for supply, wherein the secondary nozzle and the tertiary nozzle are partitioned by a partition wall, and the tertiary air flows outwardly from the flow along the burner axial direction in the partition wall A fuel combustion burner, characterized in that a flow path changing member for changing the gas flow rate is provided, and the partition wall can be moved in the burner axial direction.   The fuel combustion burner according to claim 1, wherein a guide sleeve is provided as the flow path changing member at a tip of the partition wall.   2. The burner for fuel combustion according to claim 1, wherein the primary nozzle is a nozzle that conveys pulverized coal by air flow using primary air.   In Claim 1, when the said partition moves to a predetermined position, the mechanism which bypasses a part of tertiary air is provided in the said partition so that tertiary air may bypass to another nozzle. Characteristic fuel combustion burner.   2. The fuel combustion burner according to claim 1, wherein the partition wall includes a fixed wall and a movable wall, and the flow path changing member is provided on the movable wall.   6. The fuel combustion according to claim 5, wherein a hole for bypassing tertiary air is provided in each of the movable wall and the fixed wall, and the holes communicate with each other when the movable wall moves to a predetermined position. Burner.   7. The fixed wall according to claim 6, wherein a hole is provided in an outer wall of the primary nozzle, and tertiary air that has passed through the hole formed in the movable wall and the fixed wall flows to the primary nozzle. A burner for fuel combustion, wherein a bypass pipe is provided between the hole and the hole of the primary nozzle.   8. The fuel combustion burner according to claim 7, wherein a jet outlet of the bypass pipe is formed so that the tertiary air flowing into the primary nozzle flows along the inner wall of the primary nozzle.   In Claim 7, The said primary nozzle is a nozzle which supplies pulverized coal, The pulverized coal concentrator which reduces a flow-path cross-sectional area inside the said primary nozzle and concentrates pulverized coal is provided, The said primary The burner for fuel combustion, wherein the bypass pipe is extended to the pulverized coal concentrator so that the tertiary air flowing to the nozzle flows along the surface of the pulverized coal concentrator.   2. The fuel combustion burner according to claim 1, wherein fins for cooling the flow path changing member and the partition wall in the vicinity thereof are provided in the flow path changing member and the partition wall in the vicinity thereof.   6. The fuel combustion burner according to claim 5, wherein the movable wall is configured to slide on a surface of the fixed wall, and a guide roller for guiding the movable wall is provided on the fixed wall. .   6. The fuel combustion burner according to claim 5, wherein a stopper for stopping movement of the movable wall is provided on at least one of the movable wall and the fixed wall.   2. The fuel combustion burner according to claim 1, further comprising a wind box for supplying secondary air and tertiary air, and a mechanism for moving the partition wall is provided outside the wind box.   A secondary nozzle for supplying secondary air is provided outside the primary nozzle for supplying fuel and primary air, and the tertiary for supplying tertiary air is in contact with the secondary nozzle outside the secondary nozzle. Having a nozzle, partitioning the secondary nozzle and the tertiary nozzle by a partition, and having a flow path changing member for changing the flow of tertiary air from the flow along the burner axis to the partition. A fuel combustion method using a burner configured to be movable in the axial direction of the burner, and any one of load fluctuation, burner tip temperature, fuel properties, nitrogen oxide concentration, unburned component concentration, and fuel supply stoppage The fuel combustion method characterized by adjusting the flow rate of the tertiary air supplied from the tertiary nozzle by moving the partition wall according to the state of.   15. The fuel cell according to claim 14, wherein when the fuel supply to the burner is stopped, the partition wall is moved so that the tertiary air ejection cross-sectional area of the tertiary nozzle is reduced, and the secondary air flow velocity of the secondary nozzle is increased. A fuel combustion method.   15. The tertiary air according to claim 14, wherein if the temperature of the flow path changing member becomes higher than a set temperature during fuel combustion by the burner, the partition air is moved so that the cross-sectional area of the tertiary air is reduced, and the tertiary air is moved. A fuel combustion method characterized by increasing the flow rate of the fuel.   15. The fuel combustion method according to claim 14, wherein when the fuel supply to the burner is stopped, a part of the tertiary air supplied to the tertiary nozzle is bypassed and allowed to flow to the secondary nozzle.   15. The method according to claim 14, wherein when the fuel supply to the burner is stopped, a part of the tertiary air supplied to the tertiary nozzle is bypassed and flows along the inner wall of the primary nozzle. To burn fuel. A tubular secondary air supply secondary nozzle is provided outside the primary nozzle for supplying fuel and primary air so as to surround the primary nozzle, and the tubular air for supplying tertiary air to the outside is provided. A boiler remodeling method comprising a tertiary nozzle, a tubular partition wall between the secondary nozzle and the tertiary nozzle, and a burner to which the partition wall is fixed. A tubular partition wall provided with a flow path changing member that removes at least the tip portion and changes the flow of tertiary air from the flow along the burner axis to the outside is installed so as to be movable in the burner axis direction. How to remodel the boiler.

Images