JP6487614B2 - Grate cooling method, grate cooling mechanism, and stoker-type incinerator equipped with the cooling mechanism - Google Patents

Description

  The invention of the present application relates to a stoker type incinerator, a cooling method for air-cooling a grate by blowing a gas such as air onto the bottom side of a grate (rooster), a grate cooling mechanism, and a stoker equipped with the cooling mechanism It relates to a type incinerator.

  Generally, in a garbage incineration facility, a stair-type stoker-type incinerator is used to sequentially burn combusted waste that is fed in sequence while supplying combustible waste thrown in from a hopper onto the grate rooster hardware. Often used. In general operation of a stoker-type incinerator, first, garbage collected in the garbage pit is held by a crane or the like, and provided with stalkers arranged in multiple stages from the upper hopper in a staircase-type incinerator. It is thrown into the upstream side of the furnace. Garbage that has been “dried” by the heat in the furnace moves on the stoker, eventually “burns” in the combustion section in the center of the furnace, and “post-combustes” on the downstream stoker side, so that the ash It is discharged from the downstream by the conveyor for ash removal. Garbage and incinerated ash in the furnace are sent sequentially from upstream to downstream by, for example, making part or all of the stoker movable, and mechanically swinging the stoker back and forth or left and right. It has become.

The combustion temperature in the furnace is used in a temperature range of 800 ° C to 950 ° C because it is useful to operate in an appropriate temperature range from the viewpoint of decomposition of dioxins and suppression of NO _x , and Since the stoker furnace is used not in batch processing but in continuous operation, the combustion temperature is easily maintained stably. Moreover, the production | generation of the dioxins which are easy to occur under low temperature combustion can be avoided as much as possible by operating continuously. Furthermore, the operation of further high-temperature incineration at 1000 ° C. or higher has been attempted from the viewpoint of dioxin suppression. In a normal combustion furnace, a combustion chamber is provided above the stoker, and combustion air is introduced from the outside into a space provided below the stoker. The combustion air is preheated to about 150 to 200 ° C., for example, and is blown from the outside through a blower and a duct and is supplied into the furnace.

  Recently, energy-saving incineration facilities have also been aimed at incineration facilities, and by reducing the amount of exhaust gas discharged from incinerators, further downsizing and downsizing of dust collectors and ventilation equipment on the downstream side Attempts have been made. For example, a low air ratio combustion furnace that reduces the amount of combustion gas generated by reducing excess combustion air has attracted attention as a next-generation stoker furnace.

  Surely, if the low air ratio operation is performed, the amount of combustion gas generated decreases, but the furnace interior during incineration tends to become high temperature, and the grate and refractory are subject to thermal wear compared to the conventional method. And become painful. Therefore, a countermeasure not to burn the grate is a particularly urgent issue. That is, when the surface temperature of the stoker type incinerator grate (rooster hardware) reaches 500 ° C. or more, the wear of the tip portion is remarkably easily advanced.

  In consideration of dioxin generation and combustion efficiency, it is desirable to keep the inside of the combustion furnace at a high temperature. On the one hand, while keeping the combustion part in the furnace at a high temperature, on the other hand, the metal surface temperature of the grate is less than 450 ° C. It is desirable to hold on. Conventionally, the heat radiation of such a grate has been radiated by the combustion air supplied into the furnace by providing fins on the upper surface side of the grate. However, the temperature of the grate in the combustion chamber in the incinerator varies depending on the location where the grate is used, so the degree of thermal wear also varies. There is also a difference in the degree to be done. If these were only air-cooled with primary combustion air for an incinerator introduced from a duct at the bottom of the furnace, it was not suitable for efficient local and concentrated cooling.

  Therefore, conventionally, methods for air-cooling the grate or liquid-cooling have been tried as follows. For example, one of them is a method for forcibly cooling a grate by guiding cooling air from the outside downward to the inside of the furnace exclusively for cooling and ventilating the hardware of the grate provided with an air passage. Specifically, it is a stoker-type incinerator in which a grate is placed on a movable frame and a fixed frame, and a wind box is placed below it, and the grate, movable frame, fixed frame, and wind box have a hollow structure. The gas flow path for introducing the cooling gas to the lower side of the grate via the window box and the nozzle is configured, and in the case of the grate having the hollow structure and the inner side of the scraper, or in the case of the grate alone structure, A channel groove through which cooling gas passes with a heat-radiating fin that also serves as a reinforcing rib is formed on the lower surface of the grid, and the nozzles are arranged in all or a part of the channel groove, so that the grate train is widened. In this case, the cooling mechanism in the incinerator for stoker type combustion furnace is characterized in that the spread is suppressed by the mechanical restraint of the nozzle (see, for example, Patent Document 1).

Certainly, since cooling air is newly introduced from the outside, it can be said that it is suitable for efficiently cooling the grate regardless of the combustion air.
However, it is necessary to supply a large amount of air specialized for cooling. Then, since an air passage is required inside the grate, a lot of piping for cooling air is required, and a special-shaped “dedicated grate” with an air passage for cooling ventilation is required. come. Then, it cannot be applied to a conventional stoker-type incinerator or a conventional grate as it is, and it is difficult to be a mechanism that is easy to introduce for improvement purposes, and the grate of a stoker furnace is generally a movable system. For some reasons, the design of the entire incinerator, including the stalker drive system, may need to be reviewed, and the complexity of the structure has become a bottleneck.

  Furthermore, if the combustion air and cooling air are added together and discharged as exhaust gas, the load on the flue gas treatment facility will not be reduced, so reducing the amount of exhaust gas will reduce the energy associated with exhaust gas treatment. It is not suitable for the reduction, and it has become a roundabout method for the purpose of operating an energy-saving incinerator system.

  As another means, instead of preparing to introduce cooling air from the outside, a method has also been attempted in which heat radiation is promoted by increasing the amount of blowing air of the combustion air introduced into the furnace. Certainly, a separate facility for introducing cooling air is not required. However, since it is necessary to control the temperature in the furnace as a whole, the flow rate of combustion air is supplied and controlled in a manner that depends on the combustion control. That is, since the amount of air to be blown changes due to a factor different from cooling, priority is given to the combustion efficiency. As a result, it is difficult to keep the cooling efficiency constant, and the air volume cannot be increased in a dark manner. On the other hand, the thermal burnout of the hardware of the grate proceeds abruptly as the temperature rises, so from the viewpoint of cooling so as not to damage the grate, it is not always necessary to raise the amount of combustion air blown as a whole. It was difficult to say enough.

  As another means, there is a method of limiting the grate to be cooled and cooling only a part of the grate, thereby reducing the air required for cooling and eliminating the influence of the change in the amount of combustion air. Certainly, the change in the amount of combustion air that accompanies the cooling is small, so that it is not easily affected. However, since only a part of the grate is cooled, it is difficult to cope with unexpected grate wear. In addition, since it is necessary to provide piping and nozzles for cooling air in the immediate vicinity of some of the grate, it can be said that it is difficult to add the retrofit to the conventional grate. In the end, it was necessary to design with a dedicated grate from the beginning, and the structure including the drive device for swinging the grate could not be denied.

  In addition to air cooling, it is also conceivable to cool the grate itself (see, for example, Patent Document 2). However, if the piping for passing the cooling water is arranged so as to be in close contact with the lower side of the grate, the degree of freedom in installation is small, and it is substantially limited to new equipment. In conventional air-cooled equipment, replacing the grate itself with a liquid-cooled one is not always easy to implement due to the installation space and piping. In addition, the water cooling jacket that stretches between the swinging grate needs not only to follow the swing but also to use water with a low boiling point as the cooling medium. The installation and introduction was inevitably large because it had to take measures against pressure.

Japanese Patent No. 3922993 JP 2000-146141 A Japanese Utility Model Publication No. 57-46035

  In order to cool the grate efficiently, it is effective by giving a speed to the combustion air. Therefore, if a device that gives a wind speed like a fan can be installed in the combustion air chamber below the grate, stirring is possible. Becomes easy. However, since the combustion air chamber is filled with combustion air (combustion air) from about 120 ° C. to about 250 ° C., it is difficult and difficult to use a device with a built-in electric motor. In addition, when the power is installed outside, the structure becomes complicated, and it is not always desirable to install the power in an existing facility because of a large space restriction.

  That is, the following problems are observed in the conventional cooling method as described above. For example, the grate installed in existing stoker furnaces is difficult to supply in large quantities as a general-purpose product because the staircase type stoker furnace and the shape of the grate are various and diverse. Therefore, it is not practically easy to replace it with a dedicated grate shape for cooling. In order to introduce dedicated cooling air, it is desirable to install new piping, but the space of the combustion air chamber directly under the grate of the existing incinerator is limited, so it is not always necessary to install such piping. There are also circumstances where installation and optimal placement cannot be easily added.

  In addition, a method of cooling a part of the grate is conceivable, but since the cooling points are apt to be biased inevitably, it is desirable to optimize the selection and arrangement in order to improve the efficiency of the cooling points. Since the size and shape of the furnace are various, it was impossible to optimize the location of the fitting and to carry out the work without worrying about it.

  Furthermore, if cooling air is introduced in addition to the combustion air that is supplied and blown for the purpose of appropriate combustion of the incinerator, it is considered that the amount of air flowing into the furnace increases as a whole. However, this increases the load on the smoke exhaust facility. On the other hand, even if the combustion air is gently introduced below the stoker, it is only drawn slowly, so the air fluidity is low and the combustion air immediately below the bottom of the grate is immediately heated and stagnates. Heat dissipation and cooling are difficult to proceed.

  In addition, the operation of the incinerator will give priority to the appropriate incineration of the input waste, so the control of the combustion air is not focused on grate cooling and is sufficient for grate cooling. It is not always easy to increase the supply amount. Since it is affected by the combustion state, it can be said that the thermal wear of the grate is difficult to avoid.

  Furthermore, since the temperature conditions of the grate are completely different depending on the location, such as drying, incineration, and post-incineration, it is not effective to cool all the grate uniformly. However, since it is more efficient without increasing the displacement, it is desired that the grate can be appropriately cooled according to the installation location of the grate and the location of the grate.

  Therefore, in order to improve these problems in the conventional method, the problem to be solved by the present invention is that the combustion air that is introduced into the bottom of the furnace in a slow flow is flowed so as to efficiently convection on the lower side of the grate. The stoker-type incinerator fire that promotes appropriate heat dissipation and cooling of the grate by enabling it and prolongs the replacement life of the grate as much as possible by preventing thermal wear on the upper surface of the grate as much as possible. It is to provide a grid cooling apparatus and cooling method. Therefore, instead of changing the basic supply of combustion air for cooling, rather than relying on cooling by introducing a large amount of external air, the air on the underside of the grate is heated. Focusing on stagnation, it is to provide a method of improving cooling efficiency by encouraging heat dissipation by effectively convection of combustion air while flowing the stagnation air while suppressing the introduction amount of external air. . Moreover, it is to be able to realize an incinerator with less energy load by reducing the amount of air discharge as much as possible by making it possible to cool the necessary places in an intensive manner. .

  The means of the present invention for solving the above problems will be described below. The first means uses an air volume amplification type air nozzle capable of increasing the flow velocity by introducing compressed air from the outside into the combustion air chamber provided below the grate of the stoker incinerator. A grate cooling mechanism for a stoker-type incinerator, characterized in that the discharge port of the air nozzle faces the grate and is separated from the lower surface (back side) of the grate.

  The grate of the stoker-type incinerator easily burns the garbage to be incinerated, which is sequentially fed onto it, at a temperature of about 800 to 950 ° C., so that the temperature tends to rise. The combustion air sent into the combustion chamber above the grate is generally preheated and blown from the duct, and the tip of the duct spreads widely and is connected to the lower part of the grate. It is sent from. By installing an air volume amplification type air nozzle on the path where the combustion air reaches the grate, the flow velocity of the combustion air is increased, and the combustion air is discharged from the air nozzle to the lower surface of the grate to promote heat dissipation of the grate. .

  Unlike general fan-type blowers, air volume amplification type air nozzles do not use motors and do not have built-in electric heating equipment, so there is no need for countermeasures against such heat in the first place. Nor. By introducing separately pressurized air (compressed air) from the outside into the air nozzle pipe in the combustion air chamber, the flow velocity of the combustion air taken into the air nozzle pipe is increased, and the air nozzle discharges toward the lower surface of the grate. Combustion air is convected by blowing from the outlet, so that hot air does not stay immediately below the grate bottom surface.

  As shown in FIG. 2, an air volume amplification type air nozzle of the type that introduces compressed air from the outside of the present invention for accelerating combustion air to efficiently reach the lower surface of the grate and convect the staying air on the lower surface of the grate A suitable transvector is preferred. In addition, as shown in FIG. 3A, an ejector-type air nozzle (a device for increasing the speed of fluid passing by discharging a small amount of jet air or air flow into a conduit whose path is narrowed) Other air volume amplification such as an air nozzle that uses the Coanda effect to increase the flow velocity around the inner wall surface by blowing compressed air from the outlet shown in 4 (b) in front of a cylindrical tube narrowed in the middle of the path A mold air nozzle can also be used.

  A second means of the present invention for solving the problem is to arrange the air volume amplification type air nozzle in the combustion air chamber so that the discharge port of the air nozzle is spaced from the bottom surface of the grate from 15 cm to 100 cm. A stoker-type incinerator grate cooling mechanism described in the first means, characterized in that it is provided.

  If the separation distance is in the range of 15 cm or more, the combustion air accelerated by the air volume amplification type air nozzle spreads and can be widely applied to the lower surface of the grate. be able to. On the other hand, if the separation distance is too large, the flow rate of the accelerated combustion air when reaching the lower surface of the grate will drop, and the effect of promoting the heat radiation from the lower surface of the grate by sufficiently flowing the staying air will be reduced. come. Therefore, it can be said that a distance of about 15 to 100 cm is more preferable from the viewpoint of the cooling range and efficiency.

  A third means of the present invention for solving the problem relates to the direction of the discharge port when the air volume amplification type air nozzle is disposed in the combustion air chamber, and the discharge port of the air nozzle is directed to the lower surface of the grate. The stoker-type incinerator grate cooling mechanism according to the first or second means, wherein the grate cooling mechanism is arranged obliquely and spaced apart from the lower surface of the grate.

  A fourth means of the present invention for solving the above-mentioned problems is characterized in that a transvector is used as the external compressed air introduction type air volume amplification type air nozzle. A grate cooling mechanism for a stoker-type incinerator according to any one of the above means.

  A transvector is one of air volume amplifying air nozzles, and is a known low pressure / high air volume device based on the technology developed by VORTEC in the United States (see, for example, Patent Document 3). In addition to increasing the flow velocity of the gas passing through the tube as shown in Bernoulli's theorem, as shown in FIG. A thin slit for discharging compressed air from the outside is provided in the middle of the inner wall of the cylindrical tube around the inner circumferential surface in the transverse direction, and the compressed air is supplied from the slit along the inner wall of the cylinder toward the discharge port. By blowing at a high flow rate, the movement of the air taken in from the intake port in the cylinder is accelerated, and the flow rate of the air discharged from the discharge port and the wind speed are increased by increasing the overall gas flow rate. Is greatly increased.

  The fifth means of the present invention for solving the problems is that the external compressed air introduction type air volume amplification type air nozzle adjusts the air pressure of the air nozzle outlet by adjusting the introduction pressure or the introduction air volume of the compressed air. The grate cooling mechanism for a stoker-type incinerator according to any one of the first to fourth means, characterized in that the adjusting means is provided.

  The pressure can be adjusted by providing a valve or throttle for adjusting the pressure and the amount of air introduced when the compressed air is introduced on the path of the external compressed air, or adjusting the rotational speed of the pump to be pressurized.

  In addition, sensors such as an infrared radiation thermometer that measures the temperature of combustion air and combustion chamber air and the temperature of the grate surface (upper or lower surface) are installed, and the measurement results are reflected in the adjustment of the amount of compressed air introduced. By doing so, efficient cooling can be realized, and further feedback control will optimize the grate cooling temperature to the desired set temperature range, and increase the combustion chamber air further. Can be avoided.

  A sixth means for solving the problem is a stoker-type incinerator provided with the grate cooling mechanism according to any one of the first to fifth means. That is, the means of the present invention can be carried out without bringing the air nozzle into contact with the grate (rooster) itself of the stoker-type incinerator, so that a conventional stair-sliding stoker (for example, a vertical row of stair-like stokers) Any type of stoker-type incinerator, such as one that skips in a single row) or a parallel-oscillating stalker (for example, one that oscillates back and forth one step of a stair-like stalker) Therefore, it can be widely applied to cooling the grate of a stoker-type incinerator.

  Since the grate cooling mechanism can be applied later, not only when installing the grate cooling mechanism of the present invention in a new stoker-type incinerator, but also in a conventional stoker-type incinerator of the present invention. This includes cases where a grate cooling mechanism is provided.

  The seventh means of the present invention for solving the problem is that the combustion air sent into the combustion air chamber provided below the grate of the stoker type incinerator is taken up by the air volume amplification type air nozzle in the combustion air chamber. The compressed air introduced from the outside into the pipe of the air nozzle and introduced from the outside separately from the combustion air is supplied into the pipe of the air nozzle to accelerate the air flow of the combustion air in the pipe, and the accelerated air flow is A stoker-type incineration that promotes cooling of the upper surface of the grate by releasing the air from the discharge port of the air nozzle toward the lower surface of the grate, causing the accumulated air around the lower surface of the grate to flow, and promoting heat dissipation from the lower surface of the grate This is a method for cooling a furnace grate.

  By using the grate cooling mechanism described above, the convection speed of combustion air is increased using compressed air from the outside, and the air that has been heated and stays directly under the grate is circulated efficiently and sequentially. It promotes heat dissipation from the bottom of the grid. Since the thermal conductivity of air is never high, if the heated light air convects directly under the grate, it will be difficult to release heat. Therefore, it is very effective for efficient cooling to push out the accumulated air by blowing the combustion air with a strong air volume.

  The eighth means of the present invention for solving the problem is that the combustion air sent into the combustion air chamber provided below the grate of the stoker-type incinerator is taken up by the air volume amplification type air nozzle in the combustion air chamber. The compressed air introduced from the outside into the pipe of the air nozzle and introduced from the outside separately from the combustion air is supplied into the pipe of the air nozzle to accelerate the air flow of the combustion air in the pipe, and the accelerated air flow is By discharging upward from a position 15 cm to 100 cm away from the discharge port of the air nozzle toward the lower surface of the grate, the staying air immediately below the lower surface of the grate flows and promotes heat dissipation on the lower surface of the grate. A method for cooling a grate of a stoker-type incinerator that promotes surface cooling.

  The ninth means of the present invention for solving the problem is that the combustion air sent into the combustion air chamber provided below the grate of the stoker incinerator is taken up by the air volume amplification type air nozzle in the combustion air chamber. The air flow of the combustion air in the pipe is accelerated by supplying the compressed air introduced into the pipe of the air nozzle from the inlet and introduced from the outside separately from the combustion air into the pipe of the air nozzle so that the pressure or the air volume can be adjusted. , By releasing the accelerated air flow from the discharge port of the air nozzle toward the lower surface of the grate so that the air volume can be adjusted, the stagnant air around the lower surface of the grate flows to promote heat dissipation on the lower surface of the grate This is a method for cooling the grate of a stoker-type incinerator that promotes cooling of the surface of the grate.

  The pressure or air volume of the compressed air introduced from the outside is adjusted by adjusting the pressure of the compressed air by changing the pressure of the pressurizing pump if the pressure is adjusted, and on the compressed air path if the air volume is adjusted. Adjust the degree of opening and closing of the air volume adjustment valve at. Both pressure and air volume may be combined. When the pressure of the compressed air introduced into the pipe of the air nozzle is high, the jet pressure of the compressed air introduced into the pipe rises, so that the air flow of the combustion air is also accelerated. Further, when the flow rate of the compressed air to be input increases, the amount of compressed air flowing in increases and the speed increases, so that the air flow of the combustion air is also accelerated.

  The tenth means of the present invention for solving the problem is that the adjustment degree of the ninth means is feedback control based on the temperature of the grate surface. That is, when the temperature of the grate surface is higher than a predetermined set temperature, the supply of air introduced into the pipe of the air nozzle is increased by adjusting the pressure or the air volume of the compressed air, so that the grate than the predetermined set temperature range. When the surface temperature is low, the cooling temperature of the grate surface is controlled by feedback control according to the temperature of the grate surface, such as reducing the supply introduced into the tube of the air nozzle by adjusting the pressure or air volume of the compressed air. This is a method for cooling a grate of a stoker-type incinerator according to the ninth means, wherein the grate is held in the set temperature region.

  When the surface temperature of the grate is measured and fed back to determine the amount of compressed air introduced, the sum of the combustion air and the compressed air used for combustion in the incinerator does not increase more than necessary. As a result, the operation in which the combustion temperature at the high temperature of the combustion chamber is maintained and the total amount of exhaust gas is optimized can be efficiently performed.

  For example, the temperature of the upper surface of the grate is measured with an infrared radiation thermometer, and when the temperature is higher than the desired setting area, the amount of compressed air introduced is increased to promote heat dissipation from the lower surface of the grate, When the temperature is lower than the desired setting range, the amount of compressed air introduced is suppressed, and the amount of air in the combustion chamber is not increased more than necessary.

  The intended set temperature range is a temperature range in which the grate burnout and wear are unlikely to proceed, and the introduction air is not increased more than necessary for cooling. Therefore, for example, the upper limit is set to 400 ° C. and the lower limit is set to 350 ° C. Stepwise control can be made possible even within the set temperature range, for example, by increasing the air volume when approaching the upper limit, thereby making it easier to keep in the set temperature range in advance. Also, feedback control is based on the relationship between the state of the grate temperature change for each incinerator and the volume and pressure of the compressed air to be introduced, while taking into account the change in the amount of combustion air from the duct. Also good. In this way, in addition to the relationship with the compressed air, it is possible to set a suitable feedback condition based on the relationship with the amount of combustion air, and it is possible to suppress excessive temperature fluctuations on the grate surface. Operation that does not increase more than necessary can be realized more easily.

  The eleventh means of the present invention for solving the problem is the one of the seventh to tenth means characterized in that a transvector is used as the air volume amplification type air nozzle. This is a method for cooling a grate of a stoker-type incinerator.

  In the present invention, by introducing a small amount of compressed air from the outside into the air volume amplification type air nozzle, a large amount of surrounding combustion air is drawn from the intake port of the air nozzle and flows vigorously. It can be amplified to a gas air volume many times that of air, and the flow velocity will be accelerated. In particular, transvectors are efficient and can discharge 5 to 20 times as much gas from the air nozzle as compared to external compressed air, so that the flow velocity can be greatly increased accordingly. And by increasing the wind speed and increasing the amount of air that can contact the lower surface of the grate per hour, the combustion air taken from the duct into the combustion air chamber can be more efficiently convected and blown vigorously Can do. As a result, the combustion air heated around the bottom of the grate is less likely to stay and convection to replace the combustion air, so the temperature of the combustion air immediately below the bottom of the grate is lowered and heat radiation from the bottom is increased. It becomes easy to prompt. In addition, due to the heat conduction inside the grate, the temperature of the upper surface of the grate is also likely to drop, making it difficult for the upper surface of the grate to burn out and being cooled sufficiently, extending the life of the grate and enabling long-term use It becomes. Since the amount of compressed air is smaller than the amount of combustion air, a cooling effect can be efficiently obtained while suppressing the influence on the amount of air to the incineration chamber.

  In the transvector, the discharge port can be opened so as to be loosely tapered, and the discharge direction can be diffused to about 15 degrees. By doing so, the combustion air around the outer periphery of the transvector discharge port is also attracted when blowing out, and can be moved while entraining more gas.

  Further, as in the third means of the present invention, the discharge port of the air volume amplifying type air nozzle is installed obliquely upward from a distance slightly spaced from the lower surface of the grate in the combustion air chamber. Since it flows along the lower surface, combustion air having a high flow rate can be efficiently applied to the lower surface of the grate even from a distance. Since the air that has been heated and stayed on the lower surface of the grate is efficiently convected, the heat radiation efficiency is increased accordingly, and a higher cooling effect is obtained, and overheating of the grate is avoided. Since the heated staying air on the lower surface of the grate can be greatly flowed, the staying air can be efficiently flowed in a wide range by blowing the combustion air on a wider lower surface by separating the hot air.

  By changing the separation distance between the discharge port of the air volume amplification type air nozzle and the lower surface of the grate within a range of 15 to 100 cm, the range applied to the lower surface of the grate and the flow velocity of the combustion air can be adjusted. When the separation distance is large, the range that blows out to a wide grate increases, while the wind speed reaching the grate lower surface becomes slower. If the separation distance is short, the narrow grate can be strongly blown at a high wind speed.

  When multiple air volume amplification type air nozzles are arranged on the lower surface of the grate, the distance from the lower surface of the grate should be changed for each air nozzle outlet even if the compressed air pipe introduced from the outside is shared. Therefore, it becomes easy to intensively cool the grate immediately below the combustion part. Since the arrangement with such a separation distance is possible, it is not necessary to introduce extra external compressed air, so there is no need to increase the amount of air to the combustion chamber. sell.

  By making the air volume and pressure of the external compressed air introduced to be adjustable, it is possible to adjust the air speed and air volume of the combustion air discharged from the air nozzle in an adjustable manner. Convection can be made efficient. In particular, if the flow rate of compressed air is changed based on the temperature of the grate surface, it can be cooled only when it is necessary to cool, and excessive cooling can be avoided. By introducing the minimum amount of compressed air, an optimum cooling effect of the grate can be obtained, an increase in unnecessary waste gas can be avoided, and the influence on the temperature control of the combustion chamber can be reduced.

  DESCRIPTION OF EMBODIMENTS Embodiments for carrying out the present invention will be described below with appropriate reference to the drawings. Hereinafter, a transvector will be described as an example of the air volume amplification type air nozzle, but the use of another air volume amplification type air nozzle 4 is not excluded (for example, FIG. 3). There are various types of stoker-type incinerators for use in the present invention, such as the shape of the grate and the method of sending garbage. As a general one, the stair-swing type stoker is shown in FIG. This shows how to move the garbage by moving with the grate arrangement of the stoker. Since the present invention can be carried out without bringing the air nozzle into contact with the grate itself of the stoker-type incinerator, it can be applied to a general stoker-type incinerator. Therefore, in the following description, a parallel rocking stalker will be described as an example of the stalker incinerator 1 shown in FIG.

  FIG. 1 schematically shows a positional relationship around the grate 2 of the stoker-type incinerator 1. Incineration materials such as trash are incinerated while continuously moving, and are put in from the hopper 8 on the upper right side of the drawing, incinerated on the grate 2 and then burned, and then left as incinerated ash. It is discharged from the lower incineration ash discharge port 9. The grate 2 in FIG. 1 is a multi-step staircase with a large number of hardware arranged side by side, and a set of a horizontal staircase of 10 rows x 9 vertical steps as one set, It consists of a set of post combustion grate for the lower left side. The grate 2 can sequentially send out the incinerated materials such that one row is swung back and forth in one step.

  Above the set on the right side of the grate 2 is a combustion chamber portion 4, which is a portion where the incinerated product is incinerated at a high temperature. The upper part of the combustion chamber 4 is connected to an incineration gas treatment device. Above the set on the left side of the grate 2 is the post-combustion chamber 5, and the residue incinerated in the combustion chamber 4 is combusted on the grate and becomes ash. Under each set of left and right grate, combustion air chambers 3 are provided, and combustion air 6 preheated to about 120 to 250 ° C. is sequentially supplied to each combustion air chamber 3 from duct 7. Yes. After the combustion air 6 is sent into the combustion air chamber 3, it escapes upward from below the grate 2 and is sent out to the combustion chamber portion 4 or the post-combustion portion 5. The combustion temperature of the combustion chamber section 4 and the post-combustion chamber 5 is controlled by controlling the amount of air blown from the duct 7 because the combustion temperature is controlled by the supply amount of the combustion air 6.

  Inside the combustion air chamber 3, as shown in FIGS. 4 and 5, a transvector 11 is arranged at a position separated from the grate lower surface 20 as an air volume increasing type air nozzle 4. 4 and 5, the transvector 11 is inclined 45 degrees, and the combustion air 6 is discharged through the pipe of the transvector 11 from the lower right suction port 12 toward the upper left discharge port 15. It will be. The transvector 11 is supplied with compressed air that is separately pressurized into the combustion air chamber 3 and sent from outside. By ejecting this compressed air from the inner wall slit of the pipe, the flow rate of a large amount of combustion air 6 passing through the pipe is efficiently increased. The external compressed air piping is connected to an air volume amplification type air nozzle, and is provided with a pressurizing pump for compressing the air externally, an adjustment valve for adjusting the air volume and pressure, and the like. The piping can be led from the outside through the duct of the combustion air chamber into the combustion air chamber, or a hole is made in the side wall of the combustion air chamber and the piping from the outside is inserted, and then the piping is main. A pipe is branched and connected to the compressed air intake of a plurality of arranged air volume amplification type air nozzles.

  The air immediately below the grate lower surface 20 becomes hot due to the heat radiation action, and is light and easily stays there. When the combustion air 6 discharged from the discharge port 15 reaches just below the grate lower surface 20 while flowing the surrounding air, it moves along the grate lower surface. Since it moves along the grate lower surface by the Coanda effect, the transvector 11 can be disposed at a distance. Then, the air staying on the lower surface of the grate is convected and the combustion air 6 having a lower temperature is efficiently supplied. Naturally, heat is transmitted from a high temperature to a low temperature, so that if the temperature difference increases, the heat of the grate 2 from the grate lower surface 20 is promoted to be released to the combustion air 6 accordingly. The temperature of the grate 2 is lowered, and the temperature of the grate upper surface 21 can be lowered even if the temperature of the combustion chamber portion 4 remains high.

  Now, the compressed air 13 necessary to be sent from the outside in order to operate the transvector 11 may be about 1/5 to 1/20 of the combustion air 6 promoted and conveyed by this, so that the compressed air 13 to be input is supplied. Even if it is added to the combustion air 6 sent to the combustion chamber 4, it is easy to avoid that the entire amount of air is excessively supplied. Furthermore, if the input amount of the combustion air 6 from the duct 7 is reduced in advance by the amount of the compressed air 13, the amount of air used for combustion in the incineration chamber portion 4 of the stoker-type incinerator 1 is suppressed and operated. Therefore, efficient operation can be easily realized while controlling the combustion temperature in the combustion chamber 4.

  The transvector is an air volume increasing type air nozzle having a structure as shown in FIG. The intake air 16 (combustion air 6) is taken from the intake port 12. In addition to increasing the flow velocity of the combustion air 6 passing through the inside of the pipe as shown by Bernoulli's theorem as the diameter of the pipe decreases in a conical shape toward the inside of the pipe, it is introduced from the outside into the middle of the inner wall of the cylindrical pipe. A narrow slit 14 for discharging the compressed air 13 is provided around the inner circumferential surface in the transverse direction, and the compressed air 13 is blown out at a high flow rate from the slit 14 toward the discharge port 15 along the inner wall of the cylinder. Thus, the movement of the air taken in from the suction port 12 in the cylinder is accelerated, and the flow rate and the wind speed of the discharge air 19 discharged from the discharge port 15 are increased by increasing the flow velocity of the entire gas. It rises. The discharge air 19 also attracts air around the discharge port 15 (attraction air 18).

  By the way, as will be described later, the transvector 11 is small and has a high discharge speed such as a wind speed rising from about 2 m per second to 9 m. Therefore, even if the transvector 11 is installed about 50 cm away from the grate 2, Sufficient wind speed can be applied to the vicinity of 20. Therefore, it is difficult to be affected by a structure such as a drive device that swings the grate 2 during installation, and an arrangement with a very high degree of freedom can be achieved. Therefore, it is possible to install an existing stoker furnace without replacing it with a new special grate shape without using a dedicated grate etc. or adjacent to the grate. .

  When the grate 2 is cooled, it is possible to select whether to cool a plurality of grate 2 extensively or to locally cool the grate 2 by changing a transvector mounting method or the like. For example, the surface temperature of the upper surface of the grate differs depending on the location, for example, the combustion chamber portion 4 and the post-combustion chamber portion 5 have higher temperatures in the combustion chamber portion 4. Therefore, in order to cover a wide area, the transvector 11 is arranged with a little distance, the separation distance is shortened and the number of transvectors is increased, and the separation distance is varied. You may decide to arrange. By doing in this way, the compressed air 13 supplied from external piping can be shared by a plurality of transvectors, and the internal structure can be simplified correspondingly.

  For example, a commercially available transvector, model 903, manufactured by Niigi of the present applicant has a minimum aperture of 40 mm, a compressed air input amount of 360 to 730 Nl / min, and an amplification ratio of 1: 8. The model 904 has a minimum diameter of 78 mm, compressed air of 730 to 1470 N liters / minute, and an amplification ratio of 1:10 at the maximum. The model 903 has an overall length of 82 mm and 904 has a size of 170 mm. The model 903 is relatively small, and even in a relatively narrow space in the combustion air chamber 3, it is sufficient to arrange the model 903 so as to be separated from the grate lower surface 20 by, for example, about 50 cm It's possible.

(About the contact wind speed below the grate)
For example, in a staircase-type stoker-type incinerator capable of treating 10 tons of waste for 8 hours, when the combustion air having a set temperature of 170 ° C. is slowly fed into the combustion air chamber from below as in the prior art, it is about 10 m. if air volume of 8195Nm ³ / h against ² 180 sheets grate (horizontal 10 sheets × 9 vertical stages × 2), on the lower surface of the grate, in contact with air velocity of about 2.3 m / s It will be.

On the other hand, the transvector of the air flow rate amplifier with the discharge port directed upward by 45 degrees is placed 500 mm below the grate in the combustion air chamber below the grate and spaced apart from the grate, and 10 per transvector. When 18 units are installed so as to cover the grate of the above, even when combustion air having the same set temperature of 170 ° C. is sent in the same amount of air flow of 8195 Nm ³ / h, the increase in the wind speed due to the transvector causes a substantial increase. The air volume can be increased by 24585 Nm ³ / h. Then, the total amount of contact airflow to the grate is 32780 Nm ³ / h, and the lower surface of the grate comes into contact at a wind speed of about 9.1 m / s. If this is expressed in the wind class of the Japan Meteorological Agency, it means that it has increased from wind power 2 to wind power 5. Compared with the prior art, the amount of contact air on the lower surface of the grate rises about four times, so that the combustion air flows more easily and heat radiation from the lower surface of the grate is performed well.

(About changes in grate surface temperature)
In order to confirm the effect of suppressing the temperature rise of the grate surface temperature by using the air flow amplifier of the present invention, the furnace temperature in the combustion chamber was raised to 850 ° C. while using a transvector in a small experimental furnace. The case where the grate surface temperature and the grate lower surface temperature were changed was observed for the case and the case where the transvector was stopped while being held at 850 ° C. thereafter. Note that the total amount of air introduced into the small experimental reactor is approximately 13 m ³ / h when using the transvector and when the transvector is stopped, so that the total amount of air flowing into the combustion chamber is approximately the same. The temperature in the combustion chamber is controlled under similar conditions. FIG. 8 is a graph showing the temperature change at each location during operation of the transvector, and FIG. 9 is a graph showing the temperature change after the transvector is stopped.

  When the contact air volume of the combustion air to the lower side of the grate is increased by operating the transvector, the temperature of the upper surface of the grate at the time when the furnace temperature is 850 ° C. as shown in FIG. The grate bottom surface temperature was 226 ° C. The combustion air in the combustion chamber was flowed so as to be in contact with the lower surface of the grate, and as a result of stirring, what was 130 ° C. at the time of preheating was increased to about 145 ° C. Since the combustion air was stirred in the combustion air chamber below the grate, the temperature of the grate surface was much lower than 400 ° C. at which burning out increased.

  On the other hand, when the transvector was stopped while the furnace temperature was maintained at 850 ° C., as shown in FIG. 9, the grate surface temperature reached 400 ° C. after 16 minutes and reached 435 ° C. after 30 minutes. The grate bottom surface temperature was 240 ° C. after 30 minutes. The combustion air was around 130 ° C.

  When using a transvector, the wind speed of the combustion air that contacts the lower surface of the grate is greatly different between when the transvector is used and when it is not used, hot air stays on the lower surface of the grate and prevents heat dissipation. On the other hand, if a transvector is used and combustion air is continuously applied to the lower surface of the grate, heat is easily released from the lower surface of the grate, so in the present invention using a transvector, the temperature of the upper surface of the grate In experiments, it was confirmed that it can be maintained at a low temperature as close to 100 ° C. as compared with the case of not using it.

  As described above, according to the cooling mechanism of the present invention, the grate can be efficiently cooled and the cooling performance is high, so that the cooling efficiency can be optimized by adjusting the air volume from the discharge port of the air nozzle. Is sufficiently possible. Therefore, specifically, for example, in PID control, feedback control is performed in which the input value is controlled by three elements, namely, the deviation between the output value and the target value, its integration, and differentiation. The pressure and air volume of compressed air introduced from the outside are adjusted according to the temperature conditions such as the lattice lower surface and the combustion air temperature, and the air volume discharged from the air nozzle outlet is adjusted.

  For example, the set temperature on the surface of the grate is 380 ° C. This leads to not increasing the amount of exhaust gas by selecting a temperature at which the burnout of the grate does not extremely proceed, but setting the temperature with less influence so as not to lower the incineration temperature of the combustion chamber. In addition to the temperature of the upper surface of the grate, the temperature of the stagnant air around the grate and its surroundings, the temperature of the combustion air, the temperature of the compressed air from the outside, the pressure, the opening / closing status of the regulating valve, etc. are measured. If the temperature of the upper surface of the grate rises, the pressure or air volume of the compressed air introduced from outside will increase, and if the temperature of the upper surface of the grate tends to fall, the pressure or air volume of the compressed air will decrease. At this time, by using the PID control, the deviation in the proportional control toward the target value of 380 ° C. can be corrected early, and it becomes easy not to increase the fluctuation caused by the correction operation. Stable and continuous combustion operation is possible. Thereby, it is possible to continue cooling the grate stably in the combustion operation in the stoker type incinerator that performs the continuous treatment.

It is the schematic which shows the positional relationship centering on the grate of a stoker type incinerator. It is the figure which showed the mode of the flow of the air in the intake port, a slit, the inside of a pipe | tube, and the discharge port vicinity using the longitudinal direction sectional drawing of a transvector. (A) is the schematic which showed the flow of the air of an ejector type air volume amplification type air nozzle, and (b) the air volume amplification type air nozzle using the Coanda effect. It is an arrangement view of the air volume amplification type air nozzle to the stair swinging stalker. It is an arrangement view of the air volume amplification type air nozzle on the parallel swing type stalker. It is the figure which showed a mode that it swung with the arrangement | sequence of the grate of a stair slide type stoker. It is the figure which showed the arrangement | sequence of the grate | grating of a parallel rocking | swiveling type stoker, and a mode that it rocks every other stage in (a) and (b). It is the figure which showed the mode of the temperature change of each place of the small experimental furnace at the time of transvector operation. It is the figure which showed the mode of the temperature change of the various places of a small experimental furnace at the time of a transvector stop.

1 Stoker-type incinerator 1
2 Grate 3 Combustion Air Chamber 4 Combustion Chamber Part 5 Post Combustion Chamber Part 6 Combustion Air 7 Duct 8 Hopper 9 Incineration Ash Discharge Port 10 Air Volume Amplification Type Air Nozzle 11 Transvector 12 Suction Port 13 Compressed Air 14 Slit 15 Discharge Port 16 Suction Air 18 Attracting air 19 Discharged air 20 Grate lower surface 21 Grate upper surface

Claims (11)

Compared to external compressed air by introducing compressed air from the outside into the combustion air chamber provided below the grate of the stoker-type incinerator and increasing the flow velocity of the combustion air in the combustion air chamber taken into the pipe of the air nozzle. Then, an external compressed air introduction type air volume amplification type air nozzle that increases the discharge air volume of the combustion air from the air nozzle discharge port is disposed with the discharge port of the air nozzle directed toward the grate and separated from the lower surface of the grate. A grate cooling mechanism for a stoker-type incinerator.   The stoker-type incinerator according to claim 1, wherein the air volume amplification type air nozzle is disposed in a combustion air chamber with a discharge port of the air nozzle spaced apart from a lower surface of a grate from 15 cm to 100 cm. Grate cooling mechanism.   3. The air volume amplification type air nozzle is arranged such that the discharge port of the air nozzle is inclined with respect to the lower surface of the grate and is separated from the lower surface of the grate. 4. Grate cooling mechanism of the new stoker-type incinerator. An external compressed air introduction type air volume amplification type air nozzle is designed to discharge external compressed air ejected from a slit provided on the inner circumferential surface in the transverse direction of the flow path of the nozzle along the inner wall surface, thereby discharging from the air nozzle outlet. The grate cooling mechanism for a stoker-type incinerator according to any one of claims 1 to 3, wherein a transvector for amplifying the air volume of combustion air is used.   The external compressed air introduction type air volume amplification type air nozzle is provided with an adjusting means capable of adjusting the air volume of the air nozzle outlet by adjusting the introduction pressure or the air volume of the compressed air. The grate cooling mechanism of the stoker-type incinerator according to any one of claims 1 to 4.   A stoker-type incinerator comprising the grate cooling mechanism according to any one of claims 1 to 5. The combustion air sent into the combustion air chamber provided below the grate of the stoker-type incinerator is taken into the air nozzle pipe from the intake port of the air volume amplification type air nozzle in the combustion air chamber. Separately, compressed air (external air) introduced from the outside is supplied into the tube of the air nozzle to accelerate the air flow of the combustion air in the tube, and the accelerated air flow is directed from the discharge port of the air nozzle toward the lower surface of the grate. A method for cooling a grate of a stoker-type incinerator that promotes cooling of the upper surface of the grate by causing the stagnant air around the lower surface of the grate to flow by releasing and promoting heat dissipation of the lower surface of the grate. The combustion air sent into the combustion air chamber provided below the grate of the stoker-type incinerator is taken into the air nozzle pipe from the intake port of the air volume amplification type air nozzle in the combustion air chamber. Separately, compressed air (external air) introduced from the outside is supplied into the tube of the air nozzle to accelerate the air flow of the combustion air in the tube, and the accelerated air flow is directed from the discharge port of the air nozzle toward the lower surface of the grate. A stoker-type incinerator that promotes cooling of the upper surface of the grate by causing the staying air immediately below the grate lower surface to flow by releasing it obliquely upward from a position 15 cm to 100 cm apart and promoting heat dissipation on the lower surface of the grate Grate cooling method. The combustion air sent into the combustion air chamber provided below the grate of the stoker-type incinerator is taken into the air nozzle pipe from the intake port of the air volume amplification type air nozzle in the combustion air chamber. Separately, compressed air (external air) introduced from the outside is supplied into the pipe of the air nozzle so that the pressure or the air volume can be adjusted, thereby accelerating the air flow of the combustion air in the pipe. A stoker that promotes cooling of the upper surface of the grate by allowing the air remaining in the vicinity of the lower surface of the grate to flow and releasing heat from the lower surface of the grate by releasing the air flow from the discharge port toward the lower surface of the grate. To cool the grate of the incinerator.   When the temperature of the grate surface is higher than the desired set temperature, the supply to be introduced into the pipe of the air nozzle is increased by adjusting the pressure or the air volume of the compressed air, and the grate surface temperature is higher than the desired set temperature range. When the temperature is low, the cooling temperature of the grate surface is set by the feedback control according to the temperature of the grate surface, which reduces the supply introduced into the pipe of the air nozzle by adjusting the pressure or air volume of the compressed air. The method for cooling a grate of a stoker-type incinerator according to claim 9, wherein the grate is held in a temperature region. As the air volume amplification type air nozzle, external compressed air ejected from a slit provided on the inner peripheral surface in the transverse direction of the nozzle flow path is discharged along the inner wall surface to amplify the air volume of the combustion air from the air nozzle outlet. The method for cooling a grate of a stoker-type incinerator according to any one of claims 7 to 10, wherein a transvector to be used is used.

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