JP6753639B2 - Heat treatment device for powder and granular material - Google Patents

Description

The present invention relates to a heat treatment device for powder or granular material obtained by heat-treating powder or granular material obtained by crushing, for example, waste gypsum board or the like using a rotary kiln.

When heat-treating various powders and granules, a rotary kiln that has excellent heating efficiency and can be continuously charged is often adopted. For example, it is in the state of dihydrate gypsum that is generated in large quantities due to the dismantling of buildings. The waste gypsum board is crushed into powder and granules, which are put into the kiln body of the rotary kiln and heat-treated to a predetermined temperature by the high-temperature combustion gas supplied from the burner, and then hemihydrate gypsum or type II anhydrous gypsum. It is being regenerated as a soil solidifying material, a raw material for cement, etc., and the applicant has also applied for a heat treatment device for powdered gypsum such as waste gypsum that uses a rotary kiln (Patent). Reference 1).

In the invention described in Patent Document 1, in the rotary kiln of the countercurrent heating method, heat-resistant casters are internally provided on the front half side of the kiln body on the burner installation side, and scraping blades are internally provided on the latter half side. , An intermediate input section is provided in the substantially central portion of the kiln body, and a scraping blade is provided in the latter half of the kiln body where the gas flow temperature drops to improve heating efficiency and reduce the size of the device. A relatively large amount of powder or granular material is captured and collected by a downstream dust collector, and the powder or granular material is re-injected from the intermediate charging portion into the first half of the kiln body and heat-treated to a desired temperature to prevent a decrease in yield. ing. At this time, the powder or granular material captured by the dust collector is preheated to the same extent as the powder or granular material that has passed through the latter half of the kiln body by being exposed to the exhaust gas of a predetermined temperature derived from the kiln body. Even if it is refilled from the middle, it can be heat-treated evenly.

Japanese Unexamined Patent Publication No. 2016-38116

However, in the above-mentioned conventional apparatus, when the properties of the powder or granular material to be put into the rotary kiln are relatively stable, the heat treatment can be performed without any particular problem, but the degree of crushing treatment of the waste gypsum board like the above-mentioned waste gypsum can be stored. The particle size, water content, and other properties of the powdered gypsum may vary greatly depending on the condition, and if the burner combustion amount is adjusted each time according to such variations in the properties, the exhaust gas temperature will follow. Since it fluctuates greatly, the powder or granular material captured by the dust collector is exposed to exhaust gas outside the predetermined temperature range, and when this is reintroduced from the middle of the kiln, the temperature with the powder or granular material that has passed through the latter half of the kiln body. There is a possibility of causing problems such as uneven heating due to the difference.

In view of the above points, the present invention provides a powder or granular material heat treatment apparatus capable of recovering powder or granular material of constant quality with little heating unevenness in good yield even if the properties of the powder or granular material to be heat-treated vary. The task is to do.

In order to solve the above problems, in the heat treatment apparatus for powders and granules according to claim 1 of the present invention, the flow of combustion gas supplied from the burner and the flow direction of the powders and granules to be heated face each other. It is a heat treatment device for powder and granules using a countercurrent heating type rotary kiln, and has a burner that determines the amount of combustion based on the temperature inside the furnace and the outlet temperature of the powder and granules, and has a heat-resistant caster inside. The fired kiln and the preheated kiln in which a plurality of scraping blades are internally provided are provided, and the fired kiln and the preheated kiln are arranged in a straight line so that the rotation axes of the main bodies of the kilns are aligned with each other, and the kiln of the preheated kiln. The lower end of the main body in the flow direction of the powder particles is loosely fitted into the upper end of the main body of the kiln in the flow direction of the powder particles of the firing kiln, and the main bodies of the firing kiln and the preheated kiln are independently and rotatably connected to each other. The connecting portion is provided with an intermediate charging portion for recharging the powder and particles captured by the dust collector on the downstream side of the kiln into the firing kiln, and the kiln rotation speed of the preheating kiln is set to a variable speed and derived from the preheating kiln. It is characterized by being equipped with a kiln rotation speed controller that adjusts the kiln rotation speed of the preheated kiln so as to maintain the exhaust gas temperature at a predetermined set temperature.

Further, in the powder or granular material heat treatment apparatus according to claim 2, the kiln rotation speed of the firing kiln is set to a variable speed, and the outlet temperature of the powder or granular material discharged from the firing kiln is maintained at a predetermined set temperature. It is characterized by being equipped with a kiln rotation speed controller that adjusts the kiln rotation speed of the firing kiln.

According to the powder / granule heat treatment apparatus according to claim 1 of the present invention, a heat-resistant caster having a burner for determining the combustion amount based on the furnace temperature and the outlet temperature of the powder / granule is installed internally. A firing kiln and a preheating kiln having a scraping blade internally provided are provided, and the firing kiln and the preheating kiln are arranged in a straight line so that the rotation axes of the kiln bodies of the firing kiln and the preheating kiln are aligned with each other, and the powder of the kiln body of the preheating kiln is arranged. The lower end of the firing kiln in the flow direction is loosely fitted into the upper end of the kiln body of the firing kiln in the flow direction of the particles, and the firing kiln and the preheating kiln are independently and rotatably connected to each other. Is provided with an intermediate charging section for recharging the powder and granules captured by the dust collector on the downstream side of the kiln into the firing kiln, and the kiln rotation speed of the preheating kiln is set to a variable speed, and the exhaust gas temperature derived from the preheating kiln. Since it is equipped with a kiln rotation speed controller that adjusts the kiln rotation speed of the preheated kiln so as to maintain the temperature at a predetermined set temperature, the exhaust gas temperature is adjusted even when the burner combustion amount is adjusted according to the variation in the properties of the powder and granules. Is kept at a predetermined set temperature, the powder and granules captured by the dust collector are preheated to the same extent as the powder and granules that have passed through the preheating kiln, and then re-injected into the firing kiln and heat-treated to the predetermined temperature. It is possible to recover powders and granules of constant quality with little unevenness in good yield.

Further, according to the powder or granular material heat treatment apparatus according to claim 2, the kiln rotation speed of the firing kiln is set to a variable speed, and the outlet temperature of the powder or granular material discharged from the firing kiln is maintained at a predetermined set temperature. Since it is equipped with a kiln rotation speed controller that adjusts the kiln rotation speed of the firing kiln, the exhaust gas temperature is slightly higher than the set temperature even though the rotation speed of the preheating kiln is adjusted according to the degree of variation in the properties of the powder or granular material. Even if it comes off, the heating temperature of the powder or granular material can be finely adjusted by adjusting the residence time of the powder or granular material in the firing kiln where the powder or granular material captured by the dust collector is re-injected. It is possible to recover a small amount of powder or granular material of constant quality in good yield.

It is schematic explanatory drawing which shows one Example of the heat treatment apparatus of the powder or granular material which concerns on this invention. FIG. 5 is a cross-sectional view taken along the line AA in which a part of FIG. 1 is omitted. It is a cross-sectional view of BB which partially omitted FIG.

The heat treatment apparatus for powders and granules according to the present invention is provided with a burner that determines the amount of combustion based on the temperature inside the furnace and the outlet temperature of the powders and granules, and is a heat-resistant caster that does not have a scraping function. Each kiln is provided with a fired kiln in which the kiln is internally provided and a preheated kiln in which a plurality of scraping blades are internally provided, and powders and granules preheated in the preheated kiln are transferred to the fired kiln and flowed down. Arrange each kiln in a straight line so that the rotation axes of the kiln body of the preheated kiln are approximately aligned, and the lower end of the kiln body of the preheated kiln is loosely fitted into the upper end of the kiln body of the firing kiln, and the kiln body of each kiln is fitted. Each is independently rotatably connected. Further, the connecting portion is provided with an intermediate charging portion that recharges the powder or granular material captured and collected by the dust collector on the downstream side of the kiln to the firing kiln side without using a preheating kiln.

Further, in the preheating kiln, for example, the kiln rotation speed is set to a variable speed by an inverter or the like, and the exhaust gas temperature derived from the preheating kiln is set in advance to a predetermined set temperature, for example, the powder or granular material that has passed through the preheating kiln. It is provided with a kiln rotation speed controller that adjusts the kiln rotation speed of the preheating kiln so as to maintain the temperature at the same level as the preheating temperature.

As described above, a plurality of scraping blades are internally provided in the preheated kiln, and as the kiln rotates, the powder or granular material in the kiln is repeatedly scraped up and dropped into a veil shape, so-called flight action. The structure is such that the powder or granular material is heat-treated by contacting the veil-shaped powder or granular material with the combustion gas passing through the kiln. For example, when the kiln rotation speed is increased, the number of bale formations increases and the heating efficiency is improved. While the exhaust gas temperature can be lowered by that amount, the exhaust gas temperature can be raised by that amount because the number of bale formations is reduced and the heating efficiency can be lowered by lowering the kiln rotation speed.

Further, preferably, the firing kiln also has a variable speed of kiln rotation by, for example, an inverter, and the outlet temperature of the powder or granular material discharged from the firing kiln is set to a predetermined set temperature (target temperature) set in advance. A kiln rotation speed controller that adjusts the kiln rotation speed of the firing kiln to maintain may be provided.

As described above, heat-resistant casters that do not have a scraping function are internally installed in the fired kiln, and as the kiln rotates, the powder or granular material in the kiln is slightly reduced near the inner bottom of the kiln. A configuration in which the powder or granular material is heat-treated by performing a so-called kiln action in which the material is allowed to flow along the inner wall surface of the caster while repeatedly rising and collapsing, and being exposed to a high-temperature atmosphere due to high-temperature combustion gas from a nearby burner. For example, if the number of revolutions of the kiln is increased, the flow rate of the powder or granular material can be increased and the residence time in the kiln can be shortened, and the outlet temperature of the granular material can be lowered. It is possible to reduce the flow rate of the body, extend the residence time in the kiln, and raise the outlet temperature of the granular material.

Then, when the powder or granular material to be heated is heat-treated using the apparatus having the above configuration, if the powder or granular material having different properties, for example, different water content is put into the preheating kiln during the operation, it is fired due to the influence. Since the temperature inside the kiln and the outlet temperature of the powder or granular material fluctuate, the burner that determines the combustion amount based on the temperature inside the furnace or the outlet temperature of the powder or granular material has a fluctuation range of each temperature. Adjustment control is performed so as to increase or decrease the burner combustion amount.

At this time, when the exhaust gas temperature derived from the preheated kiln fluctuates according to the increase or decrease in the burner combustion amount, the temperature of the powder or granular material captured by the dust collector exposed to this exhaust gas and the powder that has passed through the preheated kiln without scattering. If a temperature difference occurs with the preheating temperature of the granules and the powder or granular materials captured by the dust collector are directly refilled into the firing kiln from the intermediate charging portion, problems such as uneven heating may occur in some cases. Although there is a property, the kiln rotation speed controller adjusts to increase or decrease the kiln rotation speed of the preheated kiln according to the difference value between the exhaust gas temperature and the preset predetermined exhaust gas temperature, thereby preheating. The heating efficiency is adjusted by increasing or decreasing the number of veil formations of the powder or granular material in the kiln so that the exhaust gas temperature is maintained at the predetermined set temperature, for example, the preheating temperature of the powder or granular material that has passed through the preheating kiln. Adjust and control to.

Further, depending on the variation in the properties of the powder or granular material, for example, the degree of variation in the water content, the exhaust gas temperature deviates slightly from the predetermined set temperature even if the rotation speed of the preheating kiln is increased or decreased by the kiln rotation speed controller. As a result, when the outlet temperature of the powder or granular material discharged from the firing kiln deviates from the set temperature, the kiln rotation speed controller uses the powder or granular material outlet temperature and a preset predetermined powder or granular material outlet set temperature. The kiln rotation speed of the firing kiln is adjusted to increase or decrease according to the amount of difference between the above and the firing kiln, thereby increasing or decreasing the residence time of the powder or granular material in the firing kiln to finely adjust the heating temperature and the powder or granular material outlet. Adjustment control is performed so that the temperature is maintained at the predetermined set temperature (target temperature).

In this way, even when the burner combustion amount is adjusted according to the variation in the properties of the powder or granular material to be heated, the exhaust gas temperature is determined by adjusting the heating efficiency by appropriately increasing or decreasing the rotation speed of the preheating kiln. The temperature can be maintained at the set temperature of, and the powder or granular material captured by the dust collector downstream of the kiln can be preheated to the same extent as the powder or granular material that has passed through the preheating kiln, and the captured powder or granular material is fired from the intermediate charging section. Even if it is directly reintroduced to the kiln side, problems such as uneven heating can be suppressed, and powders and granules of a certain quality can be recovered in good yield. In addition, since the exhaust gas temperature can be maintained at a substantially constant temperature regardless of the amount of burner combustion, dew condensation occurs in the downstream dust collector and chimney due to the exhaust gas temperature falling too low, and the dust collector burns due to the exhaust gas temperature rising too high. It can also be expected to prevent problems such as.

In addition, depending on the degree of variation in the properties of the powder or granular material, the exhaust gas temperature deviates from the set temperature and the outlet temperature of the powder or granular material discharged from the firing kiln fluctuates slightly even though the rotation speed of the preheating kiln is adjusted. Even in such a case, by adjusting the residence time of the powder or granular material by appropriately increasing or decreasing the number of rotations of the firing kiln, the outlet temperature of the powder or granular material can be finely adjusted and maintained at a predetermined set temperature, and the quality is constant with little unevenness. Granules can be recovered in good yield.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In the figure, for example, 1 is a powder or granular material obtained by crushing a waste gypsum board or the like, which is heat-treated and transferred to a type II anhydrous gypsum and regenerated as a raw material for cement. It is a body heat treatment device, and is mainly composed of a preheating kiln 2 and a firing kiln 3 of a countercurrent heating method in which the flow direction of the object to be heated and the flow direction of the combustion gas supplied from the burner face each other. ..

The preheating kiln 2 rotatably supports a cylindrical kiln body 5 on a base 4 and is rotationally driven by a drive motor 6 so as to rotate the upper end portion of the kiln body 5 (in FIG. 1). A cold hopper 7 is provided at the right end portion), and the cold hopper 7 is provided with a screw conveyor 8 for charging powdery dihydrate gypsum which is an object to be heated, and an exhaust duct 9 for deriving exhaust gas.

On the other hand, similarly, the firing kiln 3 also has a cylindrical kiln body 10 rotatably supported on a common base 4 and rotationally driven by a drive motor 11, and the lower end of the kiln body 10 is driven. A hot hopper 12 is provided in a portion (the left end portion in FIG. 1), and the hot hopper 12 has a discharge portion 13 for discharging powdery granular type II anhydrous gypsum dislocated from dihydrate gypsum by heat treatment, and a discharge portion 13. It includes a rotary valve 14 and a burner 15 for supplying combustion gas.

Further, downstream of the exhaust duct 9, a bug filter 16 which is a dust collector for capturing powdery dihydrate gypsum or the like flowing out from the preheated kiln 2 accompanying the exhaust gas is provided, and on the downstream side thereof. Is provided with a main damper 17, an exhaust fan 18, and a chimney 19 for adjusting the amount of exhaust air.

As shown in FIG. 2, a plurality of scraping blades 20 having a substantially L-shaped cross section are provided around the inner wall of the kiln main body 5 of the preheated kiln 2, and dihydrate gypsum is applied to the kiln main body 5 as the kiln main body 5 rotates. It has a structure that performs so-called flight action while repeatedly scraping up to the upper part of the kiln body 5 and dropping it in a veil shape, and the inner wall near the center of the kiln body 5 in the longitudinal direction partially blocks the flow of the injected dihydrate gypsum. A plurality of rows of substantially arc-shaped damming bodies 21 are provided around the kiln body 5 at predetermined intervals, and the dihydrate gypsum charged into the preheated kiln 2 is temporarily retained near the center of the kiln body 5 to be retained. The amount of dihydrate gypsum in the kiln is kept substantially constant regardless of the number of revolutions, and the number of veils formed in the kiln can be increased or decreased according to the increase or decrease in the number of revolutions of the kiln to adjust the heating efficiency. We are trying to improve the correlation with the exhaust gas temperature.

On the other hand, a heat-resistant caster 22 such as a refractory brick that does not have a scraping function is provided around the inner wall of the kiln body 10 of the firing kiln 3 that is exposed to a high temperature atmosphere by the high-temperature combustion gas from the burner 15. The structure is such that the dihydrate gypsum flows along the inner wall surface of the caster 22 while repeating a slight rise and fall near the bottom of the kiln body 10 as the kiln body 10 rotates, that is, a so-called kiln action is performed. ..

Further, as shown in FIG. 1, the preheating kiln 2 and the firing kiln 3 are arranged in a straight line on a common base 4 so that the rotation axes of the kiln bodies 5 and 10 are substantially aligned with each other, and are fired. The lower end of the kiln body 5 of the preheated kiln 2 having an outer diameter slightly smaller than the inner diameter of the kiln body 10 of the kiln 3 is loosely fitted into the upper end of the kiln body 10 of the firing kiln 3, and each kiln body 5, 10 Independently and rotatably connected to each other so that the dihydric plaster put into the preheated kiln 2 is transferred to the fired kiln 3 and flows down, and the combustion gas supplied from the burner 15 into the fired kiln 3 is preheated as it is. It is supplied in the kiln 2.

Further, the outer periphery of the connecting portion 23 between the preheating kiln 2 and the firing kiln 3 is covered with a substantially annular cover body 24 to form a substantially sealed structure, which suppresses problems such as ejection from the connecting portion 23 and intrusion of outside air. It is possible.

FIG. 3 is an enlarged cross-sectional view of the connecting portion 23, in which a plurality of through holes 25 are bored at predetermined intervals along the circumferential direction with respect to the peripheral wall of the kiln body 10 of the fired kiln 3. The cover body 24 is provided around the cover body 24 so as to surround the cover body 24, and the dihydrate gypsum captured and collected by the bag filter 16 is put into the cover body 24 along the tangential direction of the cover body 24. The intermediate input section 26 is provided.

On the outer side of each of the through holes 25, a guide chute 27 that guides the dihydric gypsum charged into the cover body 24 from the intermediate charging portion 26 to the through holes 25 and sends it into the kiln body 10 of the firing kiln 3 is provided. On the other hand, on the inner side, the dihydric gypsum that flows down from the kiln body 5 of the preheated kiln 2 to the kiln body 10 of the fired kiln 3 should not overflow from the through hole 25 to the cover body 24 side as much as possible. A substantially pocket-shaped guide plate 29 is provided so as to cover the opening surface of the through hole 25 and to form a slit-shaped opening 28 only on the downstream side in the rotation direction of the kiln body 10 (opposite the arrow in FIG. 3). The dihydric gypsum flowing down from the upstream side gets over the guide plate 29 and flows down to the firing kiln 3 downstream.

Further, the rotation locus of the guide chute 27 is set to be close to the inner wall surface of the cover body 24, and even if the dihydrate gypsum charged from the intermediate charging portion 26 overflows to the bottom portion of the cover body 24, the guide chute 27 It is designed so that it can be scooped up and put into the kiln body 10 through the through hole 25.

On the other hand, below the bug filter 16, a screw conveyor 30 for delivering the dihydrate gypsum captured and recovered from the exhaust gas and a rotary valve 31 are provided, and the dihydrate gypsum delivered from the rotary valve 31 is sent to the air pressure feeding device 32. , The air pipe 33 can supply the cyclone type recovery machine 34 above the connecting portion 23. The cyclone type recovery machine 34 recovers the dihydrate gypsum from the pumped air, sequentially discharges it from the lower rotary valve 35 to the intermediate charging section 26, and scatters without a scraping blade without passing through the preheating kiln 2. It is designed to be directly reintroduced into the kiln body 10 of the few fired kilns 3. The air after collecting the dihydrate gypsum by the cyclone type recovery machine 34 may be merged with the exhaust duct 9 in front of the bug filter 16, for example.

Further, a static pressure sensor 36 for detecting the static pressure inside the kiln body 10 of the firing kiln 3 is provided at a corner of the hot hopper 12, based on the static pressure value detected by the static pressure sensor 36. A static pressure / exhaust air amount controller 37 for variably controlling the exhaust air amount by adjusting the opening degree of the main damper 17 downstream of the exhaust duct 9 (or the rotation speed of the exhaust fan 18) is provided. In the static pressure / exhaust air amount controller 37, the exhaust air amount is controlled so that the static pressure inside the kiln main body 10 is substantially the same as or slightly negative with respect to the outside air pressure, and the kiln main body 10 and the kiln main body 5 are controlled. In addition to preventing spouting from the gaps at each end, the intrusion of outside air is suppressed to improve energy saving.

38 in the figure is a furnace temperature sensor that detects the temperature inside the kiln body 10 of the firing kiln 3, and the temperature measuring part at the tip of the temperature sensor 38 is a caster provided around the inner wall of the kiln body 10. The temperature inside the furnace can be detected by penetrating 22 and projecting to the vicinity of the substantially central portion of the kiln body 10. A plurality of the furnace temperature sensors 38 may be installed at predetermined intervals along the longitudinal direction of the kiln main body 10, and the protruding positions of the temperature measuring portions of the furnace temperature sensors may be different. By doing so, it becomes possible to grasp the temperature distribution, temperature change, etc. in the furnace in more detail.

Reference numeral 39 in the figure is a burner combustion controller that adjusts the combustion amount of the burner 15 based on the furnace temperature detected by the furnace temperature sensor 38, and is a furnace temperature detected by the furnace temperature sensor 38. The combustion amount of the burner 15 is controlled based on the difference value while comparing the detected value of the above and the preset temperature in the furnace, and the set temperature in the furnace is set to dihydrate plaster or semi-hydrated plaster. It is suitable to set the temperature, for example, about 950 to 1050 ° C., which is suitable for transferring the temperature to type II anhydrous gypsum for cement raw materials. Instead of the in-core temperature sensor 38, the outlet temperature of the type II anhydrous gypsum is directly detected by the discharge portion 13 at the lower end of the hot hopper 12, and the burner combustion amount is controlled based on this outlet temperature. In that case, the outlet temperature of the type II anhydrous gypsum may be set to, for example, about 850 to 950 ° C., which is the firing temperature of the type II anhydrous gypsum suitable for cement raw materials.

Further, on the outer peripheral surface of the kiln main body 10 which is a rotating body, a transmitter 40 which takes in the signal data of the furnace temperature detected by the furnace temperature sensor 38 and wirelessly transmits it is provided, while being separated from the kiln main body 10. A receiver 41 that receives the signal data transmitted from the transmitter 40 in a non-contact manner is installed on the ground surface, and the signal data of the furnace temperature value received by the receiver 41 is burned by the burner. A wireless telemeter device 42 configured to sequentially output data to the controller 39 is provided.

43 and 44 in the figure are inverters, of which the inverter 43 can adjust the rotation speed of the kiln body 5 by adjusting the output of the drive motor 6 that rotationally drives the kiln body 5 of the preheating kiln 2. Similarly, the inverter 44 can adjust the rotation speed of the kiln main body 10 by adjusting the output of the drive motor 11 that rotationally drives the kiln main body 10 of the firing kiln 3.

Reference numeral 45 in the figure is a kiln rotation speed controller that adjusts the kiln rotation speed of the kiln main body 5 of the preheating kiln 2 and the kiln main body 10 of the firing kiln 3, and the rotation speed of the kiln main body 5 of the preheating kiln 2 is the exhaust duct. The detection value of the exhaust gas temperature detected by the exhaust gas temperature sensor 46 provided in the middle of 9 is compared with the preset exhaust gas set temperature, and the kiln main body 5 is connected via the inverter 43 based on the difference value. While controlling the number of rotations, the number of rotations of the kiln body 10 of the firing kiln 3 is the outlet temperature of the type II anhydrous gypsum detected by the powder and granule outlet temperature sensor 47 provided in the discharge portion 13 at the lower end of the hot hopper 12. The detected value is compared with the preset temperature at the outlet of the powder and granules, and the number of rotations of the kiln main body 10 is controlled via the inverter 44 based on the difference value.

The exhaust gas set temperature is not more than the heat resistant temperature of the bag filter 16 downstream, can suppress dew condensation in the exhaust duct 9, and is suitable as a preheat treatment for transferring dihydrate gypsum to type II anhydrous gypsum, for example. , Set about 130 to 180 ° C, which is an effective temperature range for dehydrating a part of dihydrate gypsum and transferring it to hemihydrate gypsum, which is an intermediate between dihydrate gypsum and type II anhydrous gypsum. If the detected value of the exhaust gas temperature sensor 46 exceeds the exhaust gas set temperature, the kiln rotation speed of the kiln main body 5 of the preheating kiln 2 is increased according to the difference value, while the set temperature is set. If it falls below the difference, the number of rotations of the gypsum body 5 of the preheated gypsum 2 is reduced according to the difference. As the amount of increase / decrease in the kiln rotation speed with respect to the temperature difference, for example, a relational expression such as how many times the exhaust gas temperature can be adjusted by increasing / decreasing the rotation speed by performing a test operation in advance is obtained. , It is preferable to adjust the kiln rotation speed based on the above relational expression.

On the other hand, the powder / granular material outlet set temperature is set to the firing temperature of type II anhydrous gypsum suitable for cement raw materials, for example, about 850 to 950 ° C., and the powder / granular material outlet temperature sensor 47 is detected. If the value exceeds the set temperature at the outlet of the powder or granular material, the kiln rotation speed of the kiln body 10 of the firing kiln 3 is increased according to the amount of the difference, while if the value is lower than the set temperature, the difference value. The number of kiln rotations of the kiln body 10 of the firing kiln 3 is reduced according to the amount. As the amount of increase / decrease in the kiln rotation speed with respect to the temperature difference, it is preferable to adjust the kiln rotation speed based on the relational expression obtained by performing a test operation in advance in the same manner as described above.

Then, for example, when the powder or granular material heat treatment device 1 is used to heat-treat the powder or granular material dihydrate gypsum to regenerate it as a type II anhydrous gypsum suitable for cement raw materials, first, The burner combustion controller 39 was set and registered with the set temperature in the furnace at 950 to 1050 ° C, and the kiln rotation speed controller 45 was set and registered with the exhaust gas set temperature of 130 to 180 ° C and the powder or granular material outlet set temperature of 850 to 950 ° C. After that, while supplying the combustion gas from the burner 15 to the calcined kiln 3 and the preheated kiln 2, a predetermined amount of powdery dihydrate gypsum is charged into the preheated kiln 2 from the screw conveyor 8. The dihydrate gypsum put into the preheated kiln 2 comes into contact with the combustion gas flow passing through the kiln body 5 while being repeatedly scraped up by the plurality of scraping blades 20 and falling like a veil, and is efficiently dried. -Preheated, and some or all of it is transferred to the intermediate hemihydrate gypsum.

Next, the dihydrate gypsum (or semi-hydrated gypsum) preheated by the preheated kiln 2 is transferred from the lower end of the kiln body 5 to the upper end of the kiln body 10 of the fired kiln 3 and flows down. The dihydrate gypsum that has flowed down to the calcined kiln 3 gradually flows along the inner wall surface of the caster 22 near the inner bottom of the kiln body 10 with a kiln action, and the high-temperature combustion gas from the adjacent burner 15 is in the meantime. It is exposed to the high temperature atmosphere and the radiant heat from the caster 22 stored at a high temperature, heat-treated to a predetermined temperature, transferred to type II anhydrous gypsum suitable for cement raw materials, and then discharged at the lower end of the hot hopper 12. It is sequentially discharged from No. 13 and stored in an appropriate storage bottle or the like.

On the other hand, due to the flight action in the preheating kiln 2, a part of the added dihydrate gypsum flows out to the exhaust duct 9 along with the exhaust gas without being sufficiently dried and preheated, but downstream of the exhaust duct 9. After being captured and collected by the bug filter 16 of the above, it is supplied to the connecting portion 23 at any time via the air pipe 33, and is recharged to the firing kiln 3 side from the intermediate charging portion 26 provided in the connecting portion 23 to preheat. Similar to the dihydrate gypsum that has passed through the kiln 2, it is heat-treated to a predetermined temperature and transferred to type II anhydrous gypsum for recovery.

At this time, the dihydrate gypsum that is captured by the bag filter 16 and re-injected into the firing kiln 3 from the intermediate charging section 26 is derived from the preheating kiln 2 and passed through the exhaust duct 9 when captured by the bag filter 16. By being exposed to the flowing exhaust gas, it has been dried and preheated to the same extent as the dihydrate gypsum that has passed through the preheated kiln 2, and part or all of it is transferred to the semi-hydrated gypsum that is an intermediate. In the calcined kiln 3 which is the refilling destination, these dihydrate gypsum (or semi-hydrated gypsum) can be heat-treated evenly to a predetermined temperature and transferred to type II anhydrous gypsum.

Further, if dihydrate gypsum having different properties, for example, a high water content, is put into the preheating kiln 2 during the operation of the heat treatment apparatus 1, the temperature inside the firing kiln 3 drops due to the influence, so that the furnace In the burner combustion controller 39 that determines the burner combustion amount based on the internal temperature, the combustion amount of the burner 15 is increased according to the decrease in the furnace temperature.

At this time, as the amount of burner combustion increases, the temperature of the exhaust gas led out to the exhaust duct 9 also rises, and the temperature of the dihydrate gypsum captured by the bag filter 16 exposed to the exhaust gas having a temperature higher than the set exhaust gas temperature. A temperature difference is generated from the preheating temperature of the dihydrate gypsum that has passed through the preheating kiln 2, and when the captured dihydrate gypsum is directly recharged into the firing kiln 3 from the intermediate charging portion 26 of the connecting portion 23, the temperature difference In some cases, there is a possibility of causing quality problems such as uneven heating due to the influence of the above, but the kiln rotation speed controller 45 has the exhaust gas temperature detected by the exhaust gas temperature sensor 46 and the set temperature. The number of rotations of the preheated kiln 2 is increased according to the difference value from the above, thereby increasing the number of veil formations of the dihydric gypsum in the preheated kiln 2 to improve the heating efficiency and set the exhaust gas temperature to the exhaust gas set temperature. Adjust and control to recover and maintain.

Then, if the dihydrate gypsum having a relatively low water content is added to the preheated kiln 2 again, the burner combustion amount is returned, and the kiln rotation speed controller 45 uses the kiln rotation speed of the preheating kiln 2 as the original rotation speed. The exhaust gas temperature is adjusted and controlled so as not to deviate from the exhaust gas set temperature.

Further, depending on the degree of water content of the dihydrate gypsum, even if the rotation speed of the preheated kiln 2 is increased by the kiln rotation speed controller 45, the exhaust gas temperature does not fall within the range of the exhaust gas set temperature, and as a result. If the outlet temperature of the type II anhydrous gypsum discharged from the discharge unit 13 of the firing kiln 3 exceeds the set temperature at the outlet of the powder or granular material, the kiln rotation speed controller 45 uses the outlet of the type II anhydrous gypsum. The kiln rotation speed of the firing kiln 3 is increased according to the difference value between the temperature and the set temperature at the outlet of the powder or granular material, thereby shortening the residence time of the type II anhydrous gypsum in the firing kiln 3 and the type II anhydrous gypsum. The outlet temperature of the powder or granular material is finely adjusted so as to recover and maintain the set temperature at the outlet of the powder or granular material.

On the other hand, when the outlet temperature of the type II anhydrous gypsum discharged from the discharge unit 13 of the calcined kiln 3 falls below the set temperature at the outlet of the powder or granular material, the kiln rotation speed controller 45 uses the type II anhydrous gypsum. The kiln rotation speed of the calcined kiln 3 is reduced according to the difference value between the outlet temperature and the set temperature at the outlet of the powder or granular material, thereby extending the residence time of the type II anhydrous gypsum in the calcined kiln 3 and causing the type II anhydrous. Finely adjust the outlet temperature of the plaster so as to recover and maintain the set temperature at the outlet of the powder or granular material.

In this embodiment, the kiln rotation speed of the firing kiln 3 is adjusted based on the outlet temperature of the type II anhydrous gypsum detected by the powder or granular material outlet temperature sensor 47 provided in the discharge portion 13 at the lower end of the hot hopper 12. However, the mounting position of the powder or granular material outlet temperature sensor 47 is not limited to this, and for example, the temperature of the type II anhydrous gypsum flowing on the caster 22 on the inner wall of the kiln body 10 can be directly measured. The side temperature portion at the tip of the sensor may be attached so as to penetrate the caster 22 and slightly project inward. Further, if a plurality of temperature sensors are provided at predetermined intervals along the longitudinal direction of the kiln main body 10, the temperature change rate, temperature distribution, etc. of the type II anhydrous anhydrite flowing down in the kiln main body 10 can be grasped in detail. Based on the rate of temperature change, for example, it is possible to take measures with more margin so that the type II anhydrous anhydrite does not reach the limit temperature (about 1100 ° C.) where problems such as thermal decomposition and melting occur due to overheating. It will be possible.

In this way, when the powdery dihydrate gypsum which is the object to be heated is preheated and heat-treated and regenerated into type II anhydrous gypsum via the hemihydrate gypsum, the dihydrate gypsum which is the object to be heated is used. Due to the variation in properties, there is a temperature difference between the temperature of the dihydrate gypsum captured and recovered by the downstream bug filter 16 and the preheating temperature of the dihydrate gypsum that has passed through the preheating kiln 2, for example, one of them. It is possible that only the semi-hydrated gypsum is transferred to the intermediate, and the other remains in the state of the di-hydrated gypsum, and if these different states are heat-treated together with the firing kiln 3, uneven heating will occur. Although there was a possibility of causing quality problems such as occurrence, the temperature difference could be eliminated by adjusting the heating efficiency in the gypsum by making the rotation speed of the preheating gypsum 2 adjustable. It is possible to recover a constant quality type II anhydrous gypsum with little heating unevenness in good yield.

Furthermore, by adjusting the residence time of the object to be heated in the kiln by adjusting the rotation speed of the firing kiln 3, the outlet temperature (heating temperature) of the type II anhydrous gypsum at the time of discharging the kiln can be finely adjusted. As a result, it becomes possible to recover type II anhydrous gypsum of more stable quality in good yield.

The present invention can be widely used for a processing apparatus for drying and heat-treating various powders and granules.

1 ... Heat treatment device for powder and granules 2 ... Preheated kiln 3 ... Firing kiln 4 ... Base 5 ... Kiln body (preheating kiln) 6, 11 ... Drive motor 9 ... Exhaust duct 10 ... Kiln body (firing kiln)
15 ... Burner 16 ... Bug filter (dust collector)
20 ... Raising blade 22 ... Caster 23 ... Connecting part 26 ... Intermediate input part 33 ... Air piping 38 ... In-furnace temperature sensor 39 ... Burner combustion controller 43, 44 ... Inverter 45 ... Kiln rotation speed controller 46 ... Exhaust gas temperature sensor 47 ... Powder and granule outlet temperature sensor

Claims (2)

A heat treatment apparatus of the particulate material using a rotary kiln countercurrent heating system and flow-down direction of a particulate material in the combustion gas stream and the object to be heated which is supplied from the burner faces, furnace temperature and particulate A firing kiln having the burner and having heat-resistant casters internally for determining the amount of combustion based on the outlet temperature of the body and a preheating kiln having a plurality of scraping blades internally are provided, and the firing kiln and the preheating kiln are provided. The lower end of the kiln body of the preheated kiln in the powder flow direction is arranged in a straight line so as to coincide with the rotation axis of each kiln body, and the lower end of the kiln body of the preheated kiln is freed in the upper end of the kiln body of the fired kiln. The kiln bodies of the fired kiln and the preheated kiln are independently and rotatably connected to each other, and the powder particles captured by the dust collector on the downstream side of the kiln are re-injected into the fired kiln. Kiln rotation speed control that includes an intermediate input unit, sets the kiln rotation speed of the preheating kiln to a variable speed, and adjusts the kiln rotation speed of the preheating kiln so as to maintain the exhaust gas temperature derived from the preheating kiln at a predetermined set temperature. A heat treatment device for powder and granules, which is characterized by being equipped with a vessel. A kiln rotation speed controller is provided for adjusting the kiln rotation speed of the firing kiln so that the kiln rotation speed of the firing kiln is variable and the outlet temperature of the powder or granular material discharged from the firing kiln is maintained at a predetermined set temperature. The heat treatment apparatus for powder or granular material according to claim 1, wherein the powder or granular material is heat-treated.

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