JP6508998B2 - Asphalt plant dryer - Google Patents

Description

  The present invention relates to an aggregate heating and drying dryer for an asphalt plant that produces an asphalt mixture that is a road pavement material.

  In an asphalt plant, the dryer which heat-dry-processes the aggregate which is a raw material of an asphalt mixture is provided. The dryer rotatably supports a cylindrical drum having a large number of scraping blades provided around the inner periphery, and has a burner for hot air supply at the front end through a hot hopper and a rear end at the front end. Has a conveyor for supplying the aggregate via a cold hopper and an exhaust duct, and a bag filter which is a dust collector downstream of the exhaust duct, and in the exhaust gas discharged from the drum by the bag filter After capturing the dust, the cleaned exhaust gas is released to the atmosphere through a chimney at the end of the exhaust duct.

  By the way, since the heating efficiency of the dryer has already been raised to the limit and the exhaust gas temperature is lowered to a temperature just before dew condensation slightly higher than the dew point temperature, for example, the inclusion of supply aggregate If the moisture, properties, and the like greatly vary, the exhaust gas temperature may easily fall below the dew point temperature, causing condensation in a bag filter, chimney, or the like, which may cause defects such as clogging of the filter cloth or corrosion. Further, recently, opportunities for producing asphalt mixtures called medium-temperature compound materials having a low heating temperature of aggregate and excellent energy saving properties are also increasing, and the temperature of exhaust gas tends to further decrease.

  Therefore, for example, as disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2004-169377), the bypass pipe is connected to the hot hopper of the dryer while the other end of the bypass pipe is an exhaust duct in front of the bag filter. An open / close damper is provided in the middle of the bypass pipe, and the open / close damper is released when the exhaust gas temperature is close to the dew point temperature, and a part of the high-temperature hot air supplied from the burner is exhausted through the bypass pipe There is disclosed a dryer of an asphalt plant designed to prevent condensation on a bag filter by introducing it into a duct and maintaining the temperature of exhaust gas above the dew point temperature.

Unexamined-Japanese-Patent No. 2004-169377

  However, not only the bag filter but also the furnace temperature near the rear end of the drum located on the upstream side may fall below the dew point temperature due to the high efficiency of the dryer and the decrease of the exhaust gas temperature due to the production of the medium temperature compound. When aggregates such as sand moistened in that state are introduced from the rear end of the drum, scraping blades and non-returning vanes provided in the vicinity (to prevent backflow of aggregates inserted into the drum There is also a problem that it adheres and grows on the surface of the blade specialized for the feeding function as it is and sometimes the scraping function of the blade and the feeding function are degraded or lost. Even if it is, it can not effectively cope with the above-mentioned problem that occurs near the rear end of the drum located upstream of the exhaust duct (bug filter) to which hot air is supplied (introduced).

  In view of the above points, the present invention adjusts the exhaust gas temperature to prevent condensation after the exhaust duct, and also enables heating of the scraping blade and the non-returning blade near the drum rear end to make aggregate on the blade surface It is an object of the present invention to provide a dryer of an asphalt plant which can prevent the adhesion and growth of the asphalt and suppress the deterioration of the raking function and the feeding function.

In order to solve the above problems, in the dryer of the asphalt plant according to the present invention according to the present invention, a burner for hot air supply is provided via a hot hopper at the front end of the drum which is rotatably supported rotatably. in dryer for aggregate heating comprising an exhaust duct and aggregate feed conveyor through a cold hopper to an end, the connecting the hot air outlet duct to the hot hopper, hot air amount adjustment in the middle of the hot air outlet duct Means coupled to a hot air guide passage for guiding the hot air to the immediate vicinity of the inner peripheral wall of the rear end of the drum while interposing a hot air supply fan provided with means ; drum rear blown from the hot air outlet at the tip of the hot air guide channel a part of the hot air is derived from the burner through the hot air outlet duct by operating It is characterized in that the inner peripheral wall and adapted to heat directly.

  In the dryer of the asphalt plant according to claim 2, the exhaust duct is provided with an exhaust gas temperature sensor, and a hot air flow / temperature controller is provided to control the hot air flow adjusting means based on the temperature detected by the exhaust gas temperature sensor. It is characterized by

According to the dryer of the asphalt plant according to claim 1, wherein according to the present invention, by connecting the hot air outlet duct to the hot hopper, one in the middle of the hot air outlet duct to interpose a hot air supply fan with hot air amount adjusting means, with linking to the nearest to the hot air guide passage for guiding the hot air of the inner peripheral wall of the drum rear end and the other end opening of the hot air outlet duct, a portion of hot air is derived from the burner by operation of the hot air supply fan Since the inner peripheral wall of the drum rear end is directly heated by blowing out from the hot air outlet at the tip of the hot air guide passage through the hot air outlet duct, part of the hot air is kept at high temperature to the drum rear end The atmosphere temperature in the furnace can be raised by the supply, thereby effectively heating the scraping blade and the non-returning blade near the rear end of the drum, and the blade of the aggregate introduced into the drum The attachment and growth of the surface can be maintained to scooping function and feeding function inhibition. Further, the temperature of the exhaust gas flowing down to the exhaust duct is appropriately raised by the merging of the hot air supplied to the rear end of the drum, and condensation on the downstream bag filter can be prevented to prevent clogging and corrosion of the filter cloth.

  According to the dryer of the asphalt plant of claim 2, the exhaust duct is provided with an exhaust gas temperature sensor, and the hot air flow / temperature controller controls the hot air flow adjusting means based on the detected temperature of the exhaust gas temperature center. Since it is equipped, the amount of hot air supplied can be adjusted automatically and appropriately according to the detected exhaust gas temperature, and the heating efficiency can be prioritized without reducing the amount of hot air supplied into the drum for aggregate heating as much as possible. While maintaining the above operation, it is possible to prevent the problems such as the adhesion of the aggregate to the scraping blade and the non-returning blade near the rear end of the drum and the generation of the condensation downstream of the exhaust duct.

It is a schematic explanatory drawing which shows one Example of the dryer of the asphalt plant which concerns on this invention. It is a principal part enlarged view of FIG. It is AA sectional drawing which partially abbreviate | omitted FIG.

  In the dryer of the asphalt plant according to the present invention, a cylindrical drum having a large number of scraping blades and non-returning blades provided around the inner circumferential wall is rotatably supported on a base, and the drive device While rotating at a speed, the front end of the drum is provided with a burner for hot air supply via a hot hopper, while the drum rear end is provided with an aggregate supply conveyor via a cold hopper An exhaust duct is provided, and at the downstream of the exhaust duct, the duct end is connected to the chimney through a dust filter for catching dust and an exhaust fan.

  The hot hopper is connected to a hot air outlet duct having a hot air flow rate adjusting means in the middle, and the other end opening of the hot air outlet duct is exposed to the rear end of the drum, and from the burner to the drum A part of the hot air led out is branched and supplied to the drum rear end through the hot air outlet duct, the ambient temperature near the drum rear end which is the hot air supply destination is raised, and the surrounding scraping blades and nonstop blades The inner circumferential wall and the like are heated to prevent adhesion and growth of aggregate such as sand wet at normal temperature which is introduced into the drum on the surface of each blade and the inner circumferential wall of the drum.

  Preferably, an exhaust gas temperature sensor for detecting an exhaust gas temperature is provided on the front side of the bag filter of the exhaust duct, and a hot air flow / temperature controller for controlling the hot air flow adjusting means based on the temperature detected by the exhaust gas temperature sensor. The hot air volume / temperature controller is provided with a predetermined preset temperature (for example, a scraping blade near the rear end of the drum, a check blade, etc., at least an aggregate such as wet sand is hard to cause adhesion) It is good to register in advance the exhaust gas temperature that can be maintained at a reasonable temperature, and to program to adjust the amount of hot air supplied according to the difference between the detected exhaust gas temperature and the set temperature. In this way, the exhaust gas temperature is at least equal to or higher than the set temperature while maintaining the operation giving priority to the heating efficiency without reducing the amount of hot air supplied into the drum for aggregate heating as much as possible. It can prevent problems such as occurrence of condensation in the aggregate adhesion and bag filter or the like of the hot air supply amount to be able automatic adjustment check blade or the like to be kept to become.

  The control mechanism need not necessarily be employed. For example, it is expected that aggregate adhesion will occur on the non-returning blade near the rear end of the drum, or the like when the aggregate such as wet sand is charged, or when the intermediate temperature compound is used. At the time of material production, or at the initial stage of operation when the temperature in the furnace near the rear end of the drum is not sufficiently warmed, the hot air volume adjustment means is operated by manual control each time to adjust the hot air supply amount. Also good. Further, as the hot air volume adjustment means, for example, a fan for hot air supply and a damper for air volume adjustment are provided in the middle of the hot air outlet duct, and the opening degree of the air volume adjustment damper is adjusted. A suitable means may be employed, such as one in which the amount of hot air is adjusted, or one in which the amount of hot air is adjusted by adjusting the fan rotational speed with the hot air supply fan as inverter control.

  Then, when the aggregate which is the material of the asphalt mixture, for example, the aggregate such as wet sand, is heat-dried by the drier of the asphalt plant having the above configuration, a part of high temperature hot air drawn from the burner is branched; The drum is forcedly supplied to the rear end of the drum through the hot air outlet duct. At this time, the in-furnace temperature near the rear end of the drum, which is the injection point of the aggregate, is appropriately raised by the high temperature hot air supplied from the hot air outlet duct, and the adhesion of the aggregate to the scraper blade, the backstop blade, etc. The growth can be effectively suppressed, and the exhaust gas temperature can also be raised to prevent condensation on a bag filter or the like, thereby suppressing clogging and corrosion of the filter cloth.

  Further, when the supply of hot air is to be automatically controlled, an exhaust gas temperature sensor and a hot air volume / temperature controller are provided, and the hot air volume / temperature controller has a predetermined set temperature in advance, for example, an aggregate insertion point. The substantially lower limit value of the exhaust gas temperature at which the adhesion of the aggregate does not occur at least near the rear end of the drum is registered. Then, when the aggregate is heated and dried by a dryer, the amount of hot air supplied is automatically controlled by controlling the amount of hot air volume adjustment according to the amount of difference between the exhaust gas temperature detected by the exhaust gas temperature sensor and the set temperature. The temperature in the furnace near the rear end of the drum is maintained at an appropriate temperature that does not cause defects such as aggregate adhesion. At this time, only the substantially minimum amount of hot air necessary to prevent adhesion of the aggregate is supplied to the rear end of the drum, and the amount of hot air for heating the aggregate can be supplied into the drum without being reduced as much as possible. The influence on the heating efficiency of the dryer can be minimized.

  As described above, in the dryer of the asphalt plant, part of the high temperature hot air drawn from the burner is branched, and the high temperature is maintained to the rear end of the drum without heat exchange with the aggregate via the hot air outlet duct Since the supply is possible, the rear end of the drum and the exhaust gas can be appropriately heated and heated effectively with a relatively small amount of hot air supply, and the scraping blade and the reverse are provided around the rear end of the drum. The adhesion and growth of aggregate to the stop vanes and the like can be suppressed to maintain the blade function, and the occurrence of condensation on a bag filter and the like downstream of the exhaust duct can be suppressed, which is useful in maintenance.

  Hereinafter, embodiments of the present invention will be described based on the drawings.

  Reference numeral 1 in the figure is a dryer for heating and drying the aggregate installed in the asphalt plant, and is based on a cylindrical drum 4 having a large number of scraping blades 2 and non-return blades 3 provided around the inner periphery. Hot air is blown into the drum 4 from the burner 7 provided on the hot hopper 6 at the front end of the drum 4 while being rotatably supported on the stand 5 so as to be rotatably inclined and rotated at a predetermined speed by a driving device (not shown) While adjusting the air volume with the main damper 10 for air volume adjustment provided on the end side of the exhaust duct 9 connected to the cold hopper 8 at the rear end of the drum 4 while discharging the exhaust gas with the exhaust fan 11 downstream thereof. While maintaining the high temperature gas flow by suction and passing through the inside of the drum 4, while the aggregate input from the aggregate supply conveyor 12 provided in the cold hopper 8 is rolled down toward the front end side of the drum 4, Make contact And dried by heating to Nozomu temperature, and are sequentially discharged from the discharge chute of the hot hopper 6 side (not shown). In addition, the exhaust gas generated by the dryer 1 is trapped in a filter cloth (not shown) built in via the bag filter 13 disposed in the middle of the exhaust duct 9, and thereafter, is collected into the atmosphere through the chimney 14 at the end. I am trying to release it.

  Further, while the hot hopper 6 is connected to a hot air outlet duct 17 in which an air volume adjusting damper 15 as a hot air volume adjusting unit and a hot air supply fan 16 are interposed in the middle, the other end of the hot air outlet duct 17 The opening is connected to the cold hopper 8 to face the rear end of the drum 4 and a part of the hot air drawn from the burner 7 with the operation of the hot air supply fan 16 through the hot air outlet duct 17 It is supplied to the end portion, and it is possible to heat the rake-up blade 2, the non-return blade 3 and the inner peripheral wall of the drum around the periphery.

  Further, 18 in the figure is formed along the inner wall of the cold hopper 8 connecting the opening at the other end of the hot air outlet duct 17 and for guiding the hot air to the immediate vicinity of the inner peripheral wall of the rear end of the drum 4 The heating blade 2 and the non-returning blade 3 provided around the inner circumferential wall near the rear end of the drum are exposed directly to the hot air blown out from the hot air outlet 18a at the end of the hot air guide passage 18 and heated. This makes it possible to heat each blade surface more effectively even with a relatively small amount of hot air. Further, a substantially flat baffle plate 19 as shown in the figure is disposed in front of the hot air outlet 18a, and the hot air for heating the aggregate flowing down the inside of the drum 4 is the hot air outlet. The hot air from the hot air outlet 18a which is substantially reverse to the hot air flowing down the inside of the drum 4 while keeping the downstream side (rear side) of the baffle plate 19 at a negative pressure while preventing it from flowing from 18a. To be able to blow out stably.

  The hot air guide passage is not limited to the above configuration, but it is essential that the hot air can be guided to the inner peripheral wall near the rear end of the drum 4, for example, after the drum 4 An annular chamber is formed in a substantially annular shape so as to surround the outer peripheral portion on the end side, and the other end opening of the hot air outlet duct 17 is connected to the annular chamber, and the drum 4 surrounded by the annular chamber A through hole is formed in the outer peripheral wall, and a part of the hot air drawn out from the burner 7 is introduced to the vicinity of the inner peripheral wall of the rear end of the drum 4 through the hot air outlet duct 17, the annular chamber and the through hole An appropriate configuration such as one guided can be adopted.

  Further, an exhaust gas temperature sensor 20 is provided on the front side of the bag filter 13 of the exhaust duct 9, and the amount of hot air for controlling the opening degree of the air volume adjustment damper 15 of the hot air derivation duct 17 based on the temperature detected by the exhaust gas temperature sensor 20. A temperature setter 21 is provided, and a predetermined set temperature is set and registered in advance in the hot air volume / temperature controller 21, and the exhaust gas temperature detected by the exhaust gas temperature sensor 20 and the setting are set. The opening degree of the air volume adjustment damper 15 is controlled in accordance with the amount of difference from the temperature to program to adjust the amount of hot air delivery. The hot air supply fan 16 may be inverter-controlled, and the rotational speed of the hot air supply fan 16 may be controlled based on the exhaust gas temperature to adjust the amount of hot air delivery.

  Then, when the aggregate which is the material of the asphalt mixture is heated and dried in the dryer 1 of the asphalt plant having the above configuration, first, the hot air amount / temperature controller 21 controls the temperature in the furnace near the rear end of the drum 4 at least. An exhaust gas temperature value that can be maintained at a temperature that hardly causes aggregate adhesion such as sand, for example, a temperature value of about 100 ° C. or more is set and registered as a set temperature. Then, while feeding the high temperature gas flow derived by burning the burner 7 into the drum 4, a predetermined amount of aggregate is charged from the aggregate supply conveyor 12 at the rear end side of the drum 4, and the rolling flow down the drum 4. It is exposed to a high temperature gas flow while heating to a predetermined temperature and dried.

  At this time, for example, aggregates such as wet sand may be introduced from the rear end of the drum 4 and may adhere to the scraping blade 2 or the non-return blade 3 etc. around it or may condense in the exhaust duct 9 downstream. Even if it occurs, the surfaces of the blades and the inner peripheral wall are appropriately heated by the high temperature hot air supplied from the hot air outlet duct 17 to the vicinity of the rear end of the drum 4 to effectively adhere and grow the aggregate. The exhaust gas temperature is also appropriately raised by joining high-temperature hot air while preventing condensation from occurring in the bag filter 13 and the like downstream of the exhaust duct 9 to prevent defects such as clogging of the filter cloth. Can be suppressed.

  On the other hand, the hot air volume / temperature controller 21 successively takes in the exhaust gas temperature value detected by the exhaust gas temperature sensor 20, and the air volume of the hot air outlet duct 17 according to the difference value amount from the preset temperature set in advance. The degree of opening of the adjustment damper 15 is automatically controlled to adjust the amount of hot air appropriately adjusted to adjust the temperature inside the furnace near the rear end of the drum 4 to such an extent that adhesion of aggregates does not occur at least, and condensation of the exhaust gas temperature occurs. While maintaining the temperature to an appropriate degree, it is possible to supply the amount of hot air for heating the aggregate fed into the drum 4 as much as possible without reducing it.

  Thus, according to the dryer 1 of the asphalt plant of the present invention, it is possible to branch a part of the high temperature hot air led out from the burner 7 and to supply it near the rear end of the drum 4 from the hot air outlet duct 17 Since the scraping blade 2, the non-returning blade 3, the inner peripheral wall, etc. near the rear end of the drum 4 which is an aggregate charging point can be heated effectively, the blade can be While being able to prevent a functional fall, generation | occurrence | production of dew condensation in the bag filter 13 grade | etc., Of the exhaust duct 9 downstream can be suppressed, and it becomes a preferable thing on maintenance.

DESCRIPTION OF SYMBOLS 1 ... Dryer 2 ... Raking blade 3 ... Backstop blade 4 ... Drum 6 ... Hot hopper 7 ... Burner 8 ... Cold hopper 9 ... Exhaust duct 12 ... Aggregate supply conveyor 13 ... Bug filter 15 ... Air volume adjustment damper (heat air volume adjustment means)
17 ... hot air outlet duct 20 ... exhaust gas temperature sensor 21 ... hot air volume / temperature controller

Claims (2)

For heating the aggregate comprising a burner for hot air supply at the front end of the rotatably supported inclined drum via a hot hopper and an aggregate supply conveyor and an exhaust duct at the rear end via a cold hopper in the dryer, the connected hot air outlet duct to the hot hopper, one in the middle of the hot air outlet duct to interpose a hot air supply fan with hot air amount adjusting means, after the drum and the other end opening of the hot air outlet duct The hot air guide passage for guiding the hot air to the immediate vicinity of the inner peripheral wall of the end is connected, and a part of the hot air drawn from the burner by the operation of the hot air supply fan is transmitted through the hot air outlet duct . A dryer for an asphalt plant, configured to blow off from a hot air outlet at a tip to directly heat an inner peripheral wall of a drum rear end portion.   The asphalt plant according to claim 1, characterized in that the exhaust duct is provided with an exhaust gas temperature sensor, and a hot air flow / temperature controller is provided to control the hot air flow adjusting means based on the temperature detected by the exhaust gas temperature sensor. Dryer.

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