JP7458792B2 - Pulverized coal burner device and its combustion method - Google Patents

Description

The present invention relates to a pulverized coal burner device that uses pulverized coal obtained by carbonizing general waste such as municipal waste as fuel, and a combustion method thereof.

The use of fossil fuels is achieved by carbonizing general waste (municipal garbage, etc.), which was conventionally incinerated, in low oxygen or no oxygen conditions to obtain char, and replacing some of the fossil fuel with the char. Efforts are being made to reduce the amount and reduce the environmental impact.

However, the charred material, which is made from general waste, contains chlorine, and there is a concern that it may generate dioxins when burned as a fuel. Desalination treatment is performed by washing with water to remove chlorine. Then, after being dehydrated to a certain degree (for example, about 30% water content) in a dehydrator (filter press, etc.), it is dried to an absolutely dry state in a dryer.

The carbide that has undergone the desalination treatment is, for example, made into pellets and put into an incinerator or the like to be used as auxiliary fuel, or pulverized in a pulverizer (mill, etc.) and carbonized to be used as burner fuel. There is.

However, after the desalination treatment and dehydration, if the product is kept in a moist state with some moisture remaining without drying, problems such as dust explosions and spontaneous combustion may be prevented and handling properties may be improved. .

Therefore, after desalinating pulverized coal derived from general waste, the applicants decided to use it as is without drying it, since it could prevent problems such as dust explosions and improve handling. In order to make this possible, we are researching a pulverized coal burner device in which an outside air introduction nozzle is connected near the injection port of the pulverized coal nozzle, and the mixture in the pulverized coal nozzle is blown into the flame in a dispersed state as a swirling flow. As a result, even when the pulverized coal is in a wet state, it can be blown into the flame in a dispersed state without problems of adhesion to or clogging of the inner wall of the nozzle, and can be properly combusted.

Patent application No. 2019-091157

However, because pulverized coal is in a wet state (moisture content: about 30%), even if it improves dispersion by creating a swirling flow, the combustion efficiency is inferior to that in a normal dry state (absolutely dry state). In some cases, the pulverized coal may not burn out in the burner flame, resulting in unburned coal.

Combustion efficiency can be improved by increasing the burner flame temperature, and a common method for increasing the burner flame temperature is, for example, to lower the air ratio.

However, in that case, the amount of secondary combustion air supplied to the throat for flame formation at the tip of the burner also decreases. The secondary combustion air also has the function of cooling and protecting the inner wall of the throat, which is exposed to high temperatures due to radiant heat from the burner flame, so if the amount of air supplied decreases, the throat may become overheated, causing its surface to become red-hot. This may cause thermal deformation such as distortion or cracking.

Therefore, in order to improve the dispersibility of wet pulverized coal and burn it properly, outside air is introduced into the pulverized coal nozzle to create a swirling flow of the mixture, and combustion occurs without any problems even when the air ratio is lowered. The challenge was to make it possible.

In view of the above points, and in order to solve the above problems, the present invention provides a pulverized coal burner in which wet pulverized coal is injected from a pulverized coal nozzle as burner fuel as claimed in claim 1. , a throat is connected to the tip of the burner body of the pulverized coal burner, and a pulverized coal nozzle that injects pulverized coal is connected to the center of the throat, and a straight tube is formed from the pulverized coal cutting and feeding section behind the throat to the nozzle tip. A heavy oil nozzle is arranged in parallel on the side of the pulverized coal nozzle, and an annular flame-holding plate with a diameter larger than the inner diameter of the burner body is provided in the throat in front of the nozzle. An outside air introduction nozzle that generates a swirling flow is connected to the outside air introduction nozzle, and the flow rate of the outside air from the outside air introduction nozzle is introduced so as to be adjustable, so that the mixture in the pulverized coal nozzle is dispersed as a desired swirling flow from the pulverized coal nozzle. The pulverized coal pressurized air is blown into the flame in the flame region formed at the throat in front of the flame stabilizing plate, and a suction duct for pulverized coal pressurized air is provided around the outer periphery of the throat, and the pulverized coal pressurized air is sucked from the suction duct. It is an object of the present invention to provide a pulverized coal burner device, characterized in that the pulverized coal is arranged in a straight tube shape from the pulverized coal cutting and feeding section to the nozzle tip.

Further, as claimed in claim 2, the outside air introduction nozzle is connected tangentially to both sides of the pulverized coal nozzle, and the outside air introduction nozzle is provided with an outside air flow rate adjustment device to freely adjust the flow rate of the outside air. To provide a pulverized coal burner device characterized in that pulverized coal is stably burned by increasing or decreasing the flow velocity of introduced outside air according to the temperature.

Further, as described in claim 3, a suction duct for pulverized coal pressurized air is disposed around the entire width of the outer peripheral portion of the throat so that the throat surface can be cooled, and preheating is performed by exchanging heat through the suction duct. It is an object of the present invention to provide a pulverized coal burner device, characterized in that the pulverized coal burner device is connected to a suction port of a pressure fan of the pulverized coal nozzle through piping so as to be able to supply pulverized coal air.

Furthermore, as claimed in claim 4, a pulverized coal burner in which pulverized coal obtained by carbonizing general waste is desalinated and undried wet pulverized coal is injected from a pulverized coal nozzle to serve as burner fuel. In the combustion method, a throat is connected to the tip of the burner body of the pulverized coal burner, and a pulverized coal nozzle that injects pulverized coal into the center of the throat is connected to the pulverized coal cutting and feeding section behind the throat to the tip of the nozzle. The pulverized coal is arranged in a straight tube shape, with heavy oil nozzles arranged in parallel on the side thereof, and an annular flame holding plate with a diameter larger than the inner diameter of the burner body is provided in the throat in front of the nozzle. An outside air introduction nozzle that generates a swirling flow is connected near the injection port of the nozzle, and the flow rate of the outside air from the outside air introduction nozzle is introduced in an adjustable manner to disperse the air-fuel mixture in the pulverized coal nozzle as a desired swirling flow. The pulverized coal is blown from the pulverized coal nozzle into the flame in the flame area formed at the throat in front of the flame stabilizing plate, and a pulverized coal pressure air suction duct is provided around the outer periphery of the throat so that the throat surface is The pulverized coal is sucked through the suction port of the pressure fan of the pulverized coal nozzle through heat exchange and preheated pulverized coal air through the suction duct provided to be coolable, and the pulverized coal is cut out and sent from the feeding section to the tip of the nozzle. It is an object of the present invention to provide a combustion method for a pulverized coal burner, characterized in that the pulverized coal is supplied to a pulverized coal nozzle disposed in a straight tube across the pulverized coal for injection.

A pulverized coal burner device according to the present invention is a pulverized coal burner in which moist pulverized coal is injected from a pulverized coal nozzle as burner fuel as claimed in claim 1, wherein the pulverized coal burner has a burner main body. A pulverized coal nozzle that injects pulverized coal is connected to the tip of the throat, and a pulverized coal nozzle that injects pulverized coal is arranged in a straight tube from the pulverized coal cutting and feeding section behind it to the nozzle tip. A heavy oil nozzle is arranged in parallel with the pulverized coal nozzle, and an annular flame-holding plate with a diameter larger than the inner diameter of the burner body is provided in the throat in front of the nozzle, and an outside air introduction nozzle generates a swirling flow near the injection port of the pulverized coal nozzle. The air-fuel mixture in the pulverized coal nozzle is formed in a dispersed state as a required swirl flow from the pulverized coal nozzle to the throat in front of the flame stabilizing plate by adjusting the flow rate of the outside air from the outside air introduction nozzle. A suction duct for pulverized coal pressurized air is provided around the outer periphery of the throat, and the pulverized coal pressurized air sucked from the suction duct is supplied to the pulverized coal cutting and feeding section. The pulverized coal nozzle is arranged in a straight tube shape from the tip of the nozzle to the tip of the nozzle, making it possible to use the pulverized coal nozzle even if the pulverized coal is wet and undried after desalting the carbide obtained by carbonizing general waste. Since the tube is straight from the pulverized coal cutting and feeding section to the nozzle tip, the pulverized coal nozzle does not adhere to or block the pulverized coal nozzle. By adjusting the amount, the fuel can be appropriately blown in a dispersed state into the flame in the flame region formed at the throat in front of the flame-holding plate formed in front of the heavy oil nozzle, and can be properly combusted in the pulverized coal burner.
For example, the faster the outside air flow rate is, the more swirling force is applied to the air-fuel mixture in the pulverized coal nozzle, which increases the dispersibility and widens the injection angle during pulverized coal injection.On the other hand, when the outside air flow rate is slow, the dispersion force decreases. The injection angle when injecting pulverized coal becomes narrower, and by adjusting the flow rate of the introduced outside air to increase or decrease the pulverized coal injection angle, pulverized coal can always be properly injected into the flame, resulting in stable pulverized coal without any unburned particles. It can be gasified and burned.
Further, if the pulverized coal is in a wet state, problems peculiar to pulverized coal such as dust explosion and spontaneous combustion can be solved, and handling properties can be improved, and the combustion treatment can be performed as described above.
Then, the air passing through the suction duct exchanges heat with the surface of the throat section, which receives radiant heat from the combustion of the pulverized coal flame burner, cooling and protecting the throat section, reducing the air ratio. It is now possible to burn pulverized coal under high flame temperatures, preheating the air for pulverized coal, and heat drying wet pulverized coal, suppressing adhesion of pulverized coal and improving dispersion during injection. can be burned properly.

Moreover, as described in claim 2, the pulverized coal burner device has the outside air introduction nozzle connected tangentially to both sides of the pulverized coal nozzle, so that the outside air flow rate can be freely adjusted to the outside air introduction nozzle. By installing a device to increase or decrease the flow rate of introduced outside air according to the burner combustion amount to ensure stable combustion of pulverized coal, it is possible to freely adjust the flow rate of outside air with the outside air introduction nozzle from the tangential direction on both sides of the pulverized coal nozzle. By introducing the air-fuel mixture in the pulverized coal nozzle into a swirling flow, the pulverized coal injection angle can be adjusted appropriately, and the pulverized coal can be properly injected into the flame according to the burner combustion amount, thereby stabilizing the pulverized coal as described above. can be burned.

Further, in the pulverized coal burner device according to claim 3, a suction duct for pulverized coal pressurized air is provided around the entire width of the outer circumference of the throat so that the throat surface can be cooled, and the throat surface is cooled. By connecting the pulverized coal nozzle to the suction port of the pressure fan of the pulverized coal nozzle so that the pulverized coal air that has been preheated through heat exchange is connected to the suction port of the pulverized coal nozzle, the throat section is cooled and protected by the air passing through the suction duct as described above. This makes it possible to supply preheated pulverized coal air from the pressure feeding fan to the pulverized coal nozzle, allowing wet pulverized coal to be heated and dried, thereby suppressing the adhesion of pulverized coal and improving dispersion during injection. , it is possible to stably burn pulverized coal.

Furthermore, the pulverized coal burner combustion method includes desalting the carbide obtained by carbonizing general waste as described in claim 4, and then injecting undried wet pulverized coal from a pulverized coal nozzle. In this pulverized coal burner combustion method, a throat is connected to the tip of the burner body of the pulverized coal burner, and a pulverized coal nozzle that injects pulverized coal into the center of the throat is connected to the pulverized coal nozzle behind the throat. The pulverized coal nozzle is arranged in a straight tube from the cutting feed section to the tip of the nozzle, with heavy oil nozzles arranged in parallel on the side thereof, and an annular pipe with a diameter larger than the inner diameter of the burner body is installed in the throat in front of the pulverized coal nozzle. A flame stabilizing plate is provided, and an outside air introduction nozzle is connected so as to be able to adjust the flow rate of the outside air in order to generate a swirling flow near the injection port of the pulverized coal nozzle, and the air-fuel mixture in the pulverized coal nozzle is dispersed as a swirling flow. In this state, the pulverized coal is blown from the pulverized coal nozzle into the flame in the flame region formed at the throat in front of the flame stabilizing plate, and a pulverized coal pressure air suction duct is provided around the outer periphery of the throat. The pulverized coal is sucked through the suction port of the pressure fan of the pulverized coal nozzle through heat exchange and preheated pulverized coal air through the suction duct, which is provided to cool the surface of the pulverized coal. The pulverized coal is pulverized coal in an undried, wet state after desalination of the carbide obtained by carbonizing municipal waste by supplying it to a pulverized coal nozzle arranged in a straight pipe over the area and injecting it. Also, as mentioned above, the pulverized coal can be properly blown into the flame formed in front of the heavy oil nozzle in a dispersed state by adjusting the required flow rate of outside air without adhering to or clogging the pulverized coal nozzle. It can be burned properly with a pulverized coal burner. Further, if the pulverized coal is in a wet state, problems peculiar to pulverized coal such as dust explosion and spontaneous combustion can be solved, and handling properties can be improved, and the combustion treatment can be performed as described above.
Then, the air passing through the suction duct exchanges heat with the surface of the throat section, which receives radiant heat from the combustion of the pulverized coal flame burner, cooling and protecting the throat section, reducing the air ratio. It is now possible to burn pulverized coal under high flame temperatures, preheating the air for pulverized coal, and heat drying wet pulverized coal, suppressing adhesion of pulverized coal and improving dispersion during injection. can be burned properly.

A schematic system diagram of an embodiment of the present invention, An enlarged cross-sectional view of the burner body as above, A-A sectional view of the pulverized coal burner section as above, BB sectional view of the throat part same as above, A partially cutaway perspective sectional view of the same as above, A schematic diagram of the test equipment for the same; Explanation diagram of injection angle measurement same as above, The relationship between the flow velocity of the introduced outside air and the injection angle as above, Explanatory diagrams (a), (b) of the state of adhesion inside the pipe of the pulverized coal nozzle as above, Particle size distribution diagram after pulverized coal injection as above, An explanatory diagram of a cooling test of the burner throat portion same as above.

The pulverized coal burner device and its combustion method of the present invention are a pulverized coal burner that uses moist pulverized coal as burner fuel by injecting it from a pulverized coal nozzle, a throat is connected to the tip of a burner body of the pulverized coal burner, a pulverized coal nozzle for injecting pulverized coal in the center is arranged in a straight tube shape from a pulverized coal cut-out and delivery section behind it to the nozzle tip , a heavy oil nozzle is arranged in parallel to the side, and an annular flame stabilizing plate with a diameter larger than the inner diameter of the burner body is provided in the throat in front of the nozzle, and a swirling flow is generated near the injection port of the pulverized coal nozzle. an external air introduction nozzle that generates a swirling flow is connected to the external air introduction nozzle, the flow rate of external air from the external air introduction nozzle is adjustable to make the mixture in the pulverized coal nozzle a required swirling flow and dispersed, and the mixture is blown from the pulverized coal nozzle into the flame in a flame region formed in the throat in front of the flame stabilizing plate; a suction duct for pulverized coal compression air is provided around the outer periphery of the throat, and the pulverized coal compression air sucked through the suction duct is supplied to the pulverized coal nozzle side that is arranged in a straight tube shape from the pulverized coal cut-out and delivery section to the nozzle tip, and injected.

As shown in FIG. 1, the pulverized coal burner device 1 includes a truncated conical throat 4 connected to the tip of a cylindrical burner body 3 of a pulverized coal burner 2, and a throat 4 of a predetermined diameter that injects pulverized coal into the center of the throat 4. The pulverized coal nozzle 5 is arranged in the form of a straight tube, and heavy oil nozzles 6 are provided on both sides of the pulverized coal nozzle 5 to enable combustion with the required thermal power.

Inside the throat 4 in front of these nozzles 5 and 6, as shown in FIG. The flame can be blown into the flame region formed inside the throat 4 in front of the flame holding plate 7.

A rotary valve 9 is connected to the base end of the rear end of the pulverized coal nozzle 5, as shown in FIG. A pulverized coal blower 10 is provided, and the pulverized coal cut out by the rotary valve 9 is forcedly fed by air from the pulverized coal blower 10 to the pulverized coal nozzle 5, which has a straight tube shape extending from the pulverized coal cutting and feeding section to the nozzle tip. We are trying to supply the same.

In the vicinity of the injection port at the front of the pulverized coal nozzle 5, which has a reversely tapered tip, a swirling flow is generated in a symmetrical manner horizontally or vertically from the tangential direction on both sides of the pulverized coal nozzle 5, as shown in FIGS. 2 and 3. In order to generate this, the outside air introduction nozzles 11 are connected to each other, and by introducing the outside air, the air-fuel mixture in the pulverized coal nozzle 5 is swirled so that it can be blown into the flame in a dispersed state at the time of injection. Reference numeral 12 denotes an air flow rate adjusting device of an inverter, which allows the air flow rate of the pulverized coal blower 10 to be adjusted in accordance with the amount of pulverized coal cut out from the pulverized coal storage bin 8.

Note that the connecting position of the outside air introduction nozzle 11 should be determined at a distance of approximately 100 to 200 mm from the nozzle tip, as the turning force will attenuate as the distance from the nozzle tip increases, and conversely, if it is too close, sufficient turning effect will not be obtained. Location is preferred. In addition, the outside air inflow speed from the outside air introduction nozzle 11 is about 70 to 120 m/s, and the flow rate of the mixture in the pulverized coal nozzle 5 is set to about 10 to 20 m/s so that it can be blown into the flame in a swirling state. .

When the outside air introduction nozzle 11 is connected to the pulverized coal nozzle 5 so that it can be connected tangentially to these inner peripheral surfaces without any steps, the outside air swirls smoothly along the inner wall surface inside the pulverized coal nozzle 5 as shown in Figure 3, and the pulverized coal being pumped can be sprayed as a swirling flow in an effectively dispersed state when sprayed, which is preferable because it creates an appropriate flame. Note that the outside air introduction nozzle 11 is preferably connected in a state that is approximately perpendicular to the longitudinal direction of the pulverized coal nozzle 5 as shown in Figures 1 to 3, which is preferable because it can most efficiently impart a swirling force to the air-fuel mixture, but it can also be connected in a state that is inclined by several tens of degrees in the forward and backward directions as long as a swirling flow can be generated.

As shown in Figures 1 to 4, the heavy oil nozzles 6 provided on both sides of the pulverized coal nozzle 5 are supplied with the required amount of heavy oil fuel from a heavy oil tank by a heavy oil supply pump 13 and a flow rate control valve 14, and the pulverized coal sprayed from the pulverized coal nozzle 5 is injected into the flame area formed in front of each heavy oil nozzle 6 as described above, where it is gasified and ignited.

As shown in FIGS. 1, 2, 4, and 5, a suction duct 15 for suctioning pulverized coal pressure air is provided around the outer periphery of the throat 4 portion on the tip side of the pulverized coal nozzle 5. An air suction pipe 17 is connected so that the pulverized coal pressurized air sucked through the duct 15 is sucked from the suction port 16 of the pulverized coal blower 10, and is supplied to the pulverized coal nozzle 5.

As shown in FIGS. 4 and 5, the suction duct 15 has a width that spans almost the entire width of the outer periphery of the throat 4, and has a required height so that it can suck in the required amount of air. An opening 18 is provided, a closing plate 19 is provided at approximately three quarters of the circumference of the throat 4, and the air suction pipe 17 is connected to the suction port 20.

The air passing through the suction duct 15 exchanges heat with the surface of the throat 4, which receives radiant heat from the combustion of the pulverized coal flame burner, heating the throat 4 and causing the surface to become red hot, distorted, etc. It is designed to prevent overheating and protect it from deformation such as cracking, and allows pulverized coal to be burned at high flame temperatures with a reduced air ratio. In addition, at the same time, the pulverized coal can be preheated and fed to the pulverized coal nozzle 5, and the wet pulverized coal can be heated and dried, thereby suppressing adhesion of pulverized coal and improving dispersion during injection. ing.

A combustion air blower 22 for supplying combustion air is disposed at the rear end of the burner main body 3 through a blower duct 21 as shown in FIG. The amount of air blown by the air blower 21 is adjusted so that the amount of combustion air commensurate with the burner combustion amount can be supplied to the burner body 3. 24 is an outside air blower that supplies outside air to the outside air introduction nozzle 11, and 25 is an air volume adjusting device for the inverter.

Incidentally, when the burner combustion rate is at full throttle, the airflow rate from the combustion air blower 22 increases, increasing the back pressure on the rear side of the flame stabilizing plate 7, so that the flame formed in front of the heavy oil nozzle 6 is strongly drawn toward the flame stabilizing plate 7 and approaches the flame stabilizing plate 7 (f1 in FIG. 2). On the other hand, when the burner combustion rate drops, the airflow rate from the combustion air blower 22 decreases, decreasing the back pressure on the rear side of the flame stabilizing plate 7, so that the position of the flame in front of the heavy oil nozzle 6 moves away from the flame stabilizing plate 7 (f2 in FIG. 2).

Further, as the outside air flow rate is faster, a swirling force is applied to the air-fuel mixture in the pulverized coal nozzle 5, the dispersibility increases, and the injection angle at the time of pulverized coal injection becomes wider (α1 in FIG. 2). Conversely, when the outside air flow rate is slow, the dispersion force decreases and the injection angle during pulverized coal injection becomes narrow (α2 in FIG. 2). In this way, there is a correlation between the outside air flow velocity and the pulverized coal injection angle, and the flame that moves back and forth (left and right in FIG. 2) inside the throat 4 depending on the burner combustion amount is By increasing or decreasing the flow rate of outside air and adjusting the pulverized coal injection angle, pulverized coal can always be properly injected into the flame, and pulverized coal can be stably gasified and burned without any unburned material. In this embodiment, the pulverized coal injection angle can be adjusted within a range of about 45 to 75 degrees.

The pulverized coal burner device 1 is also provided with a combustion controller 26 and the like to control the operation and output of the rotary valve 9, pulverized coal blower 10, heavy oil supply pump 13, combustion air blower 22, outside air blower 24, etc. When operating the device, it is possible to appropriately adjust and control increases and decreases in response to the required burner combustion.

The pulverized coal is heated by introducing the high temperature gas discharged from the pulverized coal burner 2 into the base end on the rear end side of the pulverized coal nozzle 5, and the pulverized coal in a moist state is heated by the high temperature gas discharged from the pulverized coal nozzle 5. It can also be dried by heating.

In the present invention, in particular, it is possible to target pulverized coal in an undried wet state (for example, moisture content of about 30%) after desalinating the carbonized material obtained by carbonizing general waste such as municipal waste, and dehydrating it. can. By maintaining the water content at around 30% without drying after desalination treatment, problems such as dust explosions and spontaneous combustion can be prevented, and handling properties can be improved, and it can be used as burner fuel without any problems. It can be used, has a wide range of uses, and is effective.

FIG. 1 and subsequent figures show an embodiment of the present invention. As shown in FIGS. 1 and 2, the pulverized coal burner device 1 has a truncated conical throat 4 connected to the tip of a cylindrical burner body 3 of a pulverized coal burner 2, and injects pulverized coal into the center of the throat 4. A pulverized coal nozzle 5 of a predetermined diameter is arranged in the form of a straight tube extending from the pulverized coal cutting and feeding part to the nozzle tip, and as shown in FIGS. 3 and 4, heavy oil nozzles 6 are provided on both sides of the nozzle. , 6 into the flame region formed in the throat 4 in front of the flame holding plate 7.

The tip of the pulverized coal nozzle 5 is made into a reverse tapered shape, and the pulverized coal nozzle 5 is symmetrically placed from the tangential direction on both sides of the pulverized coal nozzle 5 at a position of about 100 to 200 mm from the nozzle tip near the injection port in the front part, as shown in FIGS. 1 to 3. Outside air introduction nozzles 11 for generating a swirling flow are connected perpendicularly to the longitudinal direction of the pulverized coal nozzle 5, and the air-fuel mixture in the pulverized coal nozzle 5 is brought into a swirling state by introducing the outside air, thereby increasing the burner combustion amount. Depending on the situation, the flame can be blown into the flame in the required dispersed state during injection.

Then, as shown in FIGS. 1, 2, 4, and 5, a required height is placed on the outer circumference of the throat 4 portion on the tip side of the pulverized coal nozzle 5, with a width that spans approximately the entire width of the outer circumference of the throat 4. A suction duct 15 is provided around the pulverized coal, and an air suction pipe 17 is connected so that the pulverized coal pressurized air sucked through the suction duct 15 is sucked from the suction port 16 of the pulverized coal blower 10, and the air is supplied to the pulverized coal nozzle 5. The surface of the throat 4, which receives radiant heat etc. due to the combustion of the flame burner, is cooled by the air passing through the suction duct 15, thereby preventing and protecting the throat 4 from overheating. The pulverized coal is preheated and fed to the pulverized coal nozzle 5.

The pulverized coal burner device 1 was tested using the test equipment shown in Figure 6. In Figure 6, 101 is the test device, 105 is a pulverized coal nozzle, 108 is a hopper for charging pulverized coal, 109 is a rotary valve, 110 is a pulverized coal blower, 111 is an outside air introduction nozzle, 118 is an outside air blower, 121 is a screw conveyor, 122 and 123 are air volume sensors, 124 is a temperature sensor, and 125 is a camera.

In this test device 101, in order to confirm the injection state of pulverized coal, only a pulverized coal injection test was performed without actually performing combustion. In the test, the air flow rate from the pulverized coal blower 110 and the outside air blower 118 is detected by the air flow rate sensors 122 and 123 to calculate each flow velocity. ) was detected, the injection state of the pulverized coal was photographed using the camera 125, and the injection angle was measured based on the image data. The pulverized coal injection angle α was an angle connecting the outer edge of the injection area at a point 250 mm from the center of the tip of the pulverized coal nozzle 105, as shown in FIG.

Wet pulverized coal carbonized fuel (moisture content approximately 31-33%) was cut from the input hopper 108 via the screw conveyor 121 by the rotary valve 109 and fed into the straight pulverized coal nozzle 105, where it was compressed with the required amount of compressed air by the pulverized coal blower 110, and the pulverized coal was sprayed under the following conditions.

The connection position of the outside air introduction nozzle 111 is 150 mm from the nozzle tip, the pulverized coal supply amount is 90 kg/h, the pulverized coal pressure air flow rate is 15 m/s, and the introduced outside air flow rate is 50 m/s (low speed) or 100 m/s (high speed). ), and two patterns in which the outlet air temperature of the pulverized coal nozzle 105 was 10°C (normal temperature) or 90°C (high temperature) were tested. The results are shown in FIG.

When the outlet air temperature of the pulverized coal nozzle 105 is 10°C, the injection angle of pulverized coal is approximately 38° (No. 1) when the flow velocity of the introduced outside air is 50 m/s, and when the flow velocity of the introduced outside air is 100 m/s. At times, the injection angle of pulverized coal was approximately 61° (No. 2), and it was confirmed that the injection angle of pulverized coal increased as the flow rate of introduced outside air increased.

Furthermore, when the outlet air temperature is 90°C, when the wind speed of introduced outside air is 50 m/s, the injection angle of pulverized coal is approximately 49° (No. 3), and when the wind speed of introduced outside air is 100 m/s, the pulverized coal injection angle is approximately 49° (No. 3). The injection angle was approximately 72° (No. 4), and it was confirmed that the injection angle of pulverized coal became slightly larger by increasing the outlet air temperature. At this time, when we checked the moisture content of the pulverized coal injected from the pulverized coal nozzle 105, it was about 29-30% when the outlet air temperature was 10°C, but about 21-23% when the outlet air temperature was 90°C. The moisture content decreased by about 7 to 8%, which is expected to be due to improved dispersibility of the pulverized coal as a result of heating and drying with high-temperature compressed air.

Moreover, FIG. 9 shows the adhesion state of pulverized coal inside the pulverized coal nozzle 105 pipe. When the outlet air temperature of the pulverized coal nozzle 105 is 10°C, the area near the outside air inlet as shown in FIG. 9(a) A slight amount of pulverized coal deposits was observed, and when the outlet air temperature was set to 90° C., no deposits were observed as shown in FIG. 9(b). This is also expected to be due to the fact that the adhesion of the pulverized coal was reduced due to heating and drying using high-temperature compressed air.

Moreover, FIG. 10 is a distribution diagram of the particle size of pulverized coal immediately after being injected from the pulverized coal nozzle 105, and shows that when the outlet air temperature of the pulverized coal nozzle 105 is 90°C (No. 4) and 10°C (No. Compared to case 2), the peak at 500 to 600 μm disappears. This is also expected to be due to the fact that the adhesion force (surface tension) between the pulverized coals decreased due to heating and drying using high-temperature compressed air, and the particle size became finer, as described above.

Table 1 Burner throat cooling test table

In addition, based on the above injection test, changes in the surface temperature of the throat 4 section and the presence or absence of a red-hot state were confirmed before and after installing the cooling means for the suction duct 15 in the throat 4 section of a separately prepared combustion test machine. Under operating conditions with approximately the same burner combustion amount (150L/h), if no cooling means is installed in the throat 4 section (data 1)), even if the air ratio is relatively high (2.1 in the test) Adjustment), as shown in Table 1 and Figure 11, the surface temperature of the 4th part of the throat exceeded 500°C (increased to 855°C in the test), producing red heat. However, when a cooling means for the suction duct is installed (data 2), 4) to 7)), the surface temperature of the throat section drops significantly as shown in Table 1 and Figure 11 (approximately 400 to 500 degrees Celsius in tests). ), no red heat occurred. Note that as the air ratio is lowered, the throat surface temperature tends to rise, and the combustion efficiency increases.

However, even if a cooling means is installed, if the air ratio is lowered to less than approximately 1.4 (data 3), the throat surface temperature will exceed 500°C (up to 570°C in the test) as shown in Table 1 and Figure 11. ), producing red heat.
From the results of this test, we found that even if a cooling means is installed and the air ratio is set at the lower limit of about 1.4 (while maintaining the air ratio at about 1.4 or higher), combustion of pulverized coal in a wet state is not possible. In order to increase efficiency, it is preferable to keep the air ratio as low as possible (closer to 1.4).

INDUSTRIAL APPLICABILITY The present invention can be widely used for pulverized coal burners that use pulverized coal obtained by carbonizing general waste such as municipal waste, particularly pulverized coal that is desalinated and undried in a wet state as fuel.

1... Pulverized coal burner device 2... Pulverized coal burner 4... Throat 5... Pulverized coal nozzle 10... Pulverized coal blower 15... Suction duct

Claims (4)

A pulverized coal burner that uses wet pulverized coal as burner fuel by injecting it from a pulverized coal nozzle, wherein a throat is connected to the tip of a burner body of the pulverized coal burner, and pulverized coal is injected into the center of the throat. A pulverized coal nozzle is arranged in a straight tube from the pulverized coal cutting/feeding part behind it to the nozzle tip, and heavy oil nozzles are arranged in parallel on the side of the pulverized coal nozzle.
An annular flame stabilizing plate having a larger diameter than the inner diameter of the burner body is provided in the front throat of the nozzle, and an outside air introduction nozzle that generates a swirling flow is connected to the vicinity of the injection port of the pulverized coal nozzle, and the outside air introduction nozzle is connected to the outside air introduction nozzle. The air-fuel mixture in the pulverized coal nozzle is dispersed as a desired swirl flow by adjusting the flow rate of outside air from the pulverized coal nozzle into the flame in the flame region formed at the throat in front of the flame stabilizing plate. Let it blow in,
A suction duct for pulverized coal pressurized air is provided around the outer periphery of the throat, and the pulverized coal pressurized air sucked from the suction duct is arranged in a straight pipe shape from the pulverized coal cutting and feeding section to the nozzle tip. A pulverized coal burner device characterized by having piping connected to a pulverized coal nozzle side so that the pulverized coal can be supplied. The outside air introduction nozzle is connected tangentially to both sides of the pulverized coal nozzle, and an outside air flow rate adjustment device is installed on the outside air introduction nozzle to freely adjust the flow rate of outside air, and the flow rate of the introduced outside air is adjusted to increase or decrease according to the burner combustion amount. The pulverized coal burner device according to claim 1, wherein the pulverized coal is stably burned. A suction duct for pulverized coal pressurized air is disposed around the entire width of the outer periphery of the throat so that the throat surface can be cooled, and the pulverized coal pressurized air that has been preheated by heat exchange through the suction duct can be sucked. The pulverized coal burner device according to claim 1 or 2, characterized in that the pulverized coal burner device is connected to a suction port of a pressure feeding fan of a pulverized coal nozzle. A pulverized coal burner combustion method comprising the steps of: carbonizing municipal waste, desalting the carbonized material; and injecting wet pulverized coal from a pulverized coal nozzle as burner fuel,
A throat is connected to the tip of the burner body of the pulverized coal burner, and a pulverized coal nozzle for injecting pulverized coal is disposed in the center of the throat in a straight pipe shape from a pulverized coal cut-out and delivery section behind the throat to the nozzle tip, and a heavy oil nozzle is disposed in parallel to the side of the throat,
A ring-shaped flame stabilizing plate having a diameter larger than the inner diameter of the burner body is provided in the throat in front of the nozzle, an outside air introduction nozzle that generates a swirling flow is connected near the nozzle outlet of the pulverized coal nozzle, and the flow rate of outside air from the outside air introduction nozzle is adjusted to make the air-fuel mixture in the pulverized coal nozzle a required swirling flow and to inject it into the flame in the flame region formed in the throat in front of the flame stabilizing plate from the pulverized coal nozzle in a dispersed state.
A combustion method for a pulverized coal burner, characterized in that a suction duct for pulverized coal compressed air is provided around the outer periphery of the throat, and preheated pulverized coal compressed air is heat exchanged through the suction duct which is provided so as to be able to cool the throat surface, and is sucked in through the suction port of the compression fan of the pulverized coal nozzle, and supplied to and injected into the pulverized coal nozzle which is arranged in a straight tube shape from the pulverized coal cut-out and delivery section to the nozzle tip.

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