JP3725577B2 - Fluid roasting furnace - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a fluid roasting furnace for roasting particles (including powder in the present invention) such as foundry sand after use in a fluidized bed formation state.
[0002]
[Prior art]
Since the cast sand after use has organic substances such as a binder remaining attached in a deteriorated state, a fluid roasting furnace is used for the removal. In this type of furnace, a nozzle having a lower end communicating with an air supply chamber is generally provided at the bottom of the roasting chamber, and a fluidized bed of foundry sand is formed by air ejected from nozzle holes directed in the horizontal direction of the nozzle. Thus, a fluidized bed furnace of the type that performs roasting of the foundry sand is used.
[0003]
[Problems to be solved by the invention]
However, in the above-described fluidized roasting furnace, when one type of foundry sand is roasted and then switched to roasting of the next different type of foundry sand, for example, sand having a depth of about 40 to 50 mm on the hearth. The residual sand and the next sand to be treated are mixed, and the mold using the mixed sand of different types is not preferable because it adversely affects the strength and casting surface of the casting. Therefore, in the past, there was no choice but to stop the furnace and have the worker enter the furnace after cooling down and clean it, requiring manpower, reducing the operating rate of the furnace, and raising the cooled furnace again. The fuel cost for heating was also problematic.
[0004]
SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and an object thereof is to provide a fluidized roasting furnace capable of discharging residual granules from the furnace in a short time without manpower.
[0005]
[Means for Solving the Problems]
The fluid roasting furnace according to the present invention comprises a nozzle having a lower end communicating with an air supply chamber at the bottom of the roasting chamber, and forms a fluidized bed of particles by air ejected from a nozzle hole above the nozzle. In a fluid roasting furnace for performing body roasting, the nozzle hole of the nozzle is directed obliquely downward, and a conical body concentric with the nozzle is fitted and installed at the base of the protruding part on the hearth of the nozzle, An air flow increasing means is provided in the air blowing system to the air chamber so that the air blowing amount to the air supply chamber can be switched between the rated air flow at the time of forming the fluidized bed and the air flow at the time of discharging the granule having a larger flow rate. In addition, an exhaust port is drilled in the lower portion of the side wall of the roasting chamber, and a dust collector and an exhaust device having an air volume substantially the same as the air volume when the particles are discharged are connected to the exhaust port. Features.
[0006]
In the present invention, it is preferable that the nozzle hole of the nozzle is directed toward the outer peripheral portion of the conical body fitted and installed in the adjacent nozzle. Further, the air volume at substantially the same time as the air volume at the time of discharging the particles refers to an air volume within a range of ± 20% of the air volume at the time of discharging the particles.
[0007]
[Action]
In the present invention, a fluidized bed of granules is formed by the air ejected from the nozzle hole of the nozzle during the roasting process. When continuous roasting of a predetermined amount of particles is completed and the processed particles are discharged by their own weight from the discharge port at the bottom of the roasting chamber, air is discharged from the nozzle holes while maintaining the fluidized bed formation state. However, since the nozzle holes are obliquely downward, the amount of residual particles (residual particle depth) is smaller than in the case where the conventional nozzle holes are horizontally oriented.
[0008]
Next, if the exhaust system is operated by switching the air volume to the air supply chamber to the air volume at the time of granule discharge, the residual particles on the hearth are ejected from the obliquely downward nozzle holes by the jet air that is faster than at the time of fluidized bed formation. The body is blown up, sucked from the exhaust port, and collected by the dust collector. At this time, the conical body of the nozzle base excludes residual particles that tend to collect around the nozzle base, so that the residual particles on the hearth are discharged out of the furnace in a short time.
[0009]
In addition, since the exhaust volume of the exhaust system is almost the same as the volume of air discharged from the granule delivered to the air supply chamber, the amount of granular loss that the blown up granule flows out through the exhaust chamber and the amount of air from outside the furnace Cooling of the furnace body by suction is all suppressed to a small amount.
[0010]
【Example】
An embodiment of the present invention will be described below with reference to FIGS. In the figure, reference numeral 1 denotes a fluid roasting furnace for reclaiming casting sand, in which a cylindrical furnace body 2 is vertically divided by a hearth 3 to form a roasting chamber 4 and an air supply chamber 5. An exhaust gas chamber 8 is provided in the upper part of the furnace lid 7 with the exhaust hole 6 placed on the upper part of the furnace body 2, and the exhaust gas port 9 at the top of the exhaust gas chamber is connected to a dust collector (not shown). 11 is a chute for supplying casting sand into the roasting chamber 4, 12 is a sand discharge port for treated sand, 13 is a preheating burner, and 14 is a gun burner for injecting fuel for roasting into a fluidized bed 15 of foundry sand. A plurality of radial lines are provided.
[0011]
Reference numeral 21 denotes a nozzle provided through the hearth 3, and the lower end communicates with the air supply chamber 5. The nozzles 21 are disposed at lattice point positions (may be staggered) at a predetermined pitch over the entire surface of the hearth 3, but only a part of them is shown in FIG. 2. As shown in FIGS. 3 and 4, a plurality of diagonally downward nozzle holes 22 are radially provided above the nozzle 21 (a generic term for the nozzle 21 a and the nozzle 21 b having different nozzle hole orientations as will be described later). (In this embodiment, 8 pieces × 3 steps = 24 pieces every 45 degrees). Reference numeral 23 denotes a heat-resistant steel cone (specifically, a partial cone having no top corresponding to the nozzle diameter), which is concentric with the nozzle 21 and is fitted into the base of the nozzle 21 protruding on the hearth 3 to be hearth. 3 is mounted.
[0012]
Of the nozzle holes 22, the nozzle holes 22 facing the nozzles 21 adjacent in the vertical and horizontal directions in FIG. 3 are the outer peripheral portions of the cones 23 fitted in the adjacent nozzles 21 (specifically, the inner peripheral side of the outer peripheral edge portion 23 a). Directed downward (in this embodiment, all nozzle holes 22 are inclined 20 degrees with respect to the horizontal line) so as to be directed to the cone 23 portion to the hearth 3 portion on the outer diameter side from the outer peripheral edge portion 23a. It is.
[0013]
In FIG. 3, the nozzle 21 a and the nozzle 21 b that are adjacent in the vertical and horizontal directions in FIG. 3 are shown in FIG. 3 so that the nozzle holes 22 face each other in a straight line so that the jetted air does not collide and interfere with each other. As described above, the nozzle hole 22 of the nozzle 21b is shifted from the nozzle hole 22 of the nozzle 21a at a position rotated about 10 degrees on a plane. As a result, the blown air flows X and Y (only part of which are shown) toward the outer periphery of the conical body 23 fitted into the adjacent nozzle are blown to the outer periphery without causing the interference, and the vicinity of the outer periphery. Residual sand accumulated in can be reliably removed by blowing up.
[0014]
On the other hand, in FIG. 1, 31 is an air blower system to the air supply chamber 5, and the front end portion of the duct 33 connected to the blower outlet of the blower 32 having the rated air volume for forming the fluidized bed 15 is opened in the air supply chamber 5. It consists of 34 is a sub blower, and its discharge port is connected to the duct 33 via the on-off valve 35 to constitute the air volume increasing means 36 in this embodiment. In this embodiment, the auxiliary blower 34 having the same discharge amount as the blower 32 is used.
[0015]
1 and 2, reference numeral 41 denotes an exhaust port provided in a lower portion of the side wall 10 of the roasting chamber 4 (in this embodiment, a position near the hearth 3), which is connected to a header 43 via an on-off valve 42. The header 43 is connected to a suction port of an exhaust device (blower) 47 via a duct 44 and a cyclone type dust collecting device 45 and a water cooling device 46, and the discharge port of the exhaust device 47 is open to the atmosphere. . The exhaust amount of the exhaust device 47 is a total value of the air volume of the blower 32 and the sub-blower 34, that is, the air volume substantially the same as the sand discharging air volume (an air volume within a range of ± 20% of the sand discharging air volume).
[0016]
In the apparatus having the above configuration, the blower 32 is operated to form the fluidized bed 15 of the foundry sand introduced through the chute 11 into the roasting chamber 4, and the foundry sand is roasted by blowing the fuel with the gun burner 14. Treats and burns and removes organic materials such as caking materials.
[0017]
When the roasting of one type of foundry sand is finished, the operation of the blower 32 is continued and the treated sand is sequentially discharged from the sand discharge port 12 while the fluidized bed 15 is formed. However, since the nozzle hole 22 has a diagonally downward nozzle hole as compared with the conventional furnace in which the nozzle hole is oriented in the horizontal direction, the depth of the residual sand on the hearth 3 at the end of the self-weight discharge is conventional. It is reduced to about 1/2 of the case of the furnace.
[0018]
When the amount of sand discharged from the sand discharge port 12 decreases to a small amount (at the end of self-weight discharge), the auxiliary blower 34 is started to operate, and the on-off valve 35 is opened to reduce the amount of air blown into the air supply chamber 5 (sand). While switching to the discharge air volume, the opening / closing valve 42 of the exhaust port 41 is opened and the exhaust device 47 is operated. As a result, the amount of air delivered to the air supply chamber 5 during sand discharge, and hence the amount of air ejected from the nozzle holes 22 of the nozzles 21, is approximately twice that of the formation of the fluidized bed. Residual sand on the hearth 3 is blown up by the high-speed blown air, and the blown-up residual sand is sucked together with the air from the exhaust port 41 and collected by the dust collecting device 45, and the base of each nozzle 21. Since the residual sand that tends to collect near the base is eliminated by the cone 23 fitted to the base 23, almost no residual sand is left on the hearth 3 in a short time of about several minutes.
[0019]
After the above sand discharge, each device is returned to its original state, and the next different type of foundry sand roasting process may be started. As described above, after the furnace body 2 is cooled as in the prior art, it is possible to remove the residual sand in an extremely short time and without manual labor, compared to the case where the worker enters the furnace body 12 and performs the residual sand removal work. In addition, since the cooling and cooling of the furnace body 2 due to sand discharge is minimal, there is little damage to the refractory of the furnace body 2, and the fuel cost for reheating the furnace body is greatly reduced. It is made.
[0020]
The present invention is not limited to the above embodiment. For example, as a means for increasing the amount of air blown into the air supply chamber, a method of driving a single blower with a variable speed motor or the like may be adopted. The ratio of the air volume during sand discharge may be a ratio other than 1: 2 according to the nozzle hole diameter, the number of nozzles, the arrangement, and the like. The dust collector connected to the exhaust port may be other than the cyclone type.
[0021]
Further, in the above embodiment, some nozzle holes are directed to the outer peripheral portion of the conical body that is fitted and installed in the adjacent nozzle, so that it is possible to reliably blow up and remove residual particles (sand) accumulated in the vicinity of the outer peripheral portion. However, depending on the shape of the cone and the air ejection speed from the nozzle hole, all the nozzle holes may be directed to the outer periphery of the cone. It is good also as a structure which is not made to point to a part.
[0022]
In addition, the fluidized roasting furnace for reclaiming casting sand has been described above. However, the present invention is applied to a roasting (incineration) furnace that incinerates sludge and other granular wastes using sand as a medium, and a nonferrous metal refining process. The present invention can be widely applied to fluid roasting furnaces for roasting various particles (including powder) for various purposes, such as a roasting furnace for oxidizing metal sulfide ore.
[0023]
【The invention's effect】
As described above, according to the present invention, air is ejected from the nozzle hole obliquely downward of the nozzle at a higher speed than that when the fluidized bed is formed, and residual particles on the hearth are blown up and sucked from the exhaust port to collect dust. Since the conical body eliminates the accumulation of residual particles at the nozzle base, the residual particles can be discharged from the furnace in a short time without manpower, and the generation of mixed particles can be prevented. The operating rate of the furnace is improved, and the cooling temperature of the furnace body is low when the granule is discharged, so that the furnace refractory is less damaged and the fuel cost for reheating the furnace body can be reduced.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view (including equipment connection system) of a fluid roasting furnace for reclaiming foundry sand showing one embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line AA in a state where there is no fluidized bed 15 in FIG.
FIG. 3 is a partially enlarged plan view of the hearth in FIG. 2;
4 is a cross-sectional view taken along line BB in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fluid roasting furnace, 2 ... Furnace body, 3 ... Hearth, 4 ... Roasting chamber, 5 ... Supply chamber, 10 ... Side wall, 15 ... Fluidized bed, 21 ... Nozzle, 22 ... Nozzle hole, 23 ... Conical Body ... 31 Air blower system, 32 ... Blower, 33 ... Duct, 34 ... Sub blower, 35 ... Open / close valve, 36 ... Air supply increasing means, 41 ... Exhaust port, 42 ... Open / close valve, 45 ... Dust collector, 47 ... exhaust device.

Claims (2)

Fluid roasting in which a nozzle whose lower end communicates with the air supply chamber is provided at the bottom of the roasting chamber, and a fluidized bed of particles is formed by the air ejected from the nozzle holes at the top of the nozzle to thereby roast the particles. In the furnace, the nozzle hole of the nozzle is directed obliquely downward, and a conical body concentric with the nozzle is fitted and installed at the base of the protruding part on the hearth of the nozzle, and sent to the air blowing system to the air supply chamber. An air volume increasing means is provided so that the air volume to the air supply chamber can be switched between the rated air volume at the time of forming the fluidized bed and the air volume at the time of discharging the granule having a larger flow rate, and the side wall of the roasting chamber A fluid roasting furnace characterized in that an exhaust port is formed in a lower part, and a dust collector and an exhaust device having an exhaust amount substantially the same as the particulate discharge amount are connected to the exhaust port. The fluid roasting furnace according to claim 1, wherein the nozzle hole of the nozzle is directed toward an outer peripheral portion of a cone fitted and installed in an adjacent nozzle.

Images