JP2017008508A - Dryer of asphalt plant and operation control method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dryer of an asphalt plant in which an exhaust gas temperature is prevented from becoming a dew-point temperature or less even if an operation condition of the dryer varies greatly, troubles due to dew condensation are prevented from being caused, and provide its operation control method.SOLUTION: In a dryer employing a countercurrent heating system, a sub burner 16 smaller than a main burner 8 is disposed in an aggregate supply hopper 5 side, and a second exhaust duct 17 for guiding the exhaust gas by the burning of the sub burner 16 to a bag filter 10 is connected to an aggregate discharge hopper 7. Also, a first exhaust duct 9 and the second exhaust duct 17 includes a first switching damper 18 and a second switching damper 19 for interrupting a flow of the exhaust gas. Then, when a burner combustion amount is reduced and a decrease of an exhaust gas temperature is expected, it is operated in a co-current heating system in which a flow of an aggregate is made the same direction as a flow of a hot air by the burning of the sub burner 16 and the opening of the second switching damper 19, and thereby the exhaust gas temperature is prevented from becoming a dew-point temperature or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a dryer for heating aggregate in an asphalt plant for producing an asphalt mixture which is a road pavement material, and an operation control method thereof.

  In the asphalt plant, two new aggregates (hereinafter referred to as “new materials”) and asphalt pavement waste materials (hereinafter referred to as “waste materials”), which are materials of the asphalt mixture, can be heated to about 160 degrees. Equipped with a dryer. Among the two dryers, the new material dryer that heats the aggregate, which is a new material, considers increasing the heating efficiency, and the bone is formed by countercurrent contact with the flow of the aggregate and the flow of hot air facing each other. While adopting the counter-current heating method to heat the material, the waste material dryer that heats the waste material (recycled material) takes into account the thermal degradation due to overheating of the asphalt contained in the waste material, and the flow of waste material and the flow of hot air are the same The co-current heating method is adopted in which the waste material is heated by co-current contact in the direction, and the waste material that has flowed down in the drum and heated up is not exposed to a high-temperature burner flame near the drum discharge section.

  The counter-current heating type new material dryer is capable of increasing the heating efficiency to the limit by lowering the exhaust gas temperature lower than the heating aggregate temperature discharged from the drum because of the counter-current contact between the aggregate and hot air. In the new dryer, exhaust gas containing a large amount of water vapor is exhausted by heating sand with high moisture content in the new material, so that the exhaust gas temperature does not fall below the dew point so as not to cause problems due to condensation. I'm driving. Further, the co-current heating type dryer has a co-current contact between the aggregate and the hot air, so the exhaust gas temperature becomes higher than the heating aggregate temperature, and as a result, in the waste material dryer, the exhaust gas is below the dew point temperature. There is almost no trouble caused by condensation.

  In the asphalt plant, a new material and waste material obtained by heating in both the asphalt mixture using the new material heated by the new material dryer and the new material dryer and the waste material dryer are mixed at a predetermined ratio. Appropriate asphalt mixtures such as asphalt mixtures are manufactured upon request. By the way, for example, when trying to manufacture an asphalt mixture in which 50% of new material and 50% of waste material are mixed, it is heated to about 160 ° C. while supplying a new material amount that is half the rated supply amount to the new material dryer. In order to produce a promising medium temperature compound from the viewpoint of energy saving, the new material is heated to about 130 ° C., which is about 30 ° C. lower than the normal temperature of about 160 ° C.

  However, the new material dryer adopting the countercurrent heating system is designed to heat up to a temperature of about 160 ° C while supplying the new material at the determined rated supply amount. Or when operating with burner combustion amount greatly reduced from the rated capacity, such as when heating new materials for medium temperature compound materials, the exhaust gas temperature will be lower than normal operation, and in some cases it may be below the dew point temperature If sufficient consideration is not given during operation, condensation may occur in the exhaust duct, the downstream bag filter, the chimney, etc., which may cause clogging or corrosion of the filter cloth.

  In a new material dryer adopting such a countercurrent heating method, as a means for preventing dew condensation of exhaust gas, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-169377), a bypass pipe is connected to a discharge hopper on the burner side of the dryer. The other end of the bypass pipe is connected to the exhaust flue of the dryer in front of the bag filter, and a part of the hot hot air supplied from the burner is joined to the exhaust flue via the bypass pipe so that the exhaust gas temperature is dew point temperature. I try to keep it above.

JP 2004-169377 A

  However, as described above, the bypass pipe connected to the burner side of the dryer is connected to the exhaust flue of the dryer in front of the bag filter, and a part of the high-temperature hot air is merged with the exhaust gas to raise the exhaust gas temperature to the dew point temperature or higher. Even so, the exhaust gas from the vicinity of the exhaust gas outlet in the drum (near the aggregate input part) to the junction may be at a certain low temperature or below the dew point temperature, which may cause some trouble at that point. possible.

  In view of the above points, the present invention can prevent the exhaust gas temperature from becoming the dew point temperature or less even if the operation condition of the dryer greatly fluctuates, and a dryer for an asphalt plant that does not cause trouble due to condensation. It is an object to provide an operation control method.

  In order to solve the above-mentioned problems, in the asphalt plant dryer according to claim 1 according to the present invention, a cylindrical drum is rotatably supported and the aggregate is drummed from the aggregate supply hopper side at one end of the drum. While being fed into the other end of the drum and flowing down to the aggregate discharge hopper side, the aggregate is brought to a predetermined temperature by making countercurrent contact with the hot air supplied from the main burner disposed on the aggregate discharge hopper side. In an asphalt plant dryer that employs a countercurrent heating system that heats and exhausts exhaust gas discharged from the drum by an exhaust fan downstream of the first exhaust duct connected to the aggregate supply hopper and leads to a bag filter A secondary burner smaller than the main burner is disposed on the aggregate supply hopper side, and a second exhaust duct for guiding exhaust gas generated by combustion of the secondary burner to the bag filter is connected to the aggregate discharge hopper On the other hand, each of the first exhaust duct and the second exhaust duct is provided with a first open / close damper and a second open / close damper that block the flow of exhaust gas, and is supplied by combustion of the auxiliary burner and opening of the second open / close damper. A feature of the present invention is that the aggregate can be heated even by a co-current heating method in which the flow of the aggregate and the flow of hot air are in the same direction.

  Further, in the asphalt plant dryer according to claim 2, the second exhaust duct is provided with an exhaust gas temperature sensor for detecting an exhaust gas temperature, and a drum is provided at a corner in an aggregate supply hopper provided with the sub-burner. A second static pressure sensor for detecting the internal static pressure is provided, and when the aggregate is heated by the cocurrent heating method, the sub burner is controlled so that the exhaust gas temperature detected by the exhaust gas temperature sensor becomes a predetermined set value. An operation controller is provided for controlling the amount of exhaust air so that the combustion pressure is controlled and the static pressure value detected by the second static pressure sensor becomes a predetermined set value.

  Further, in the operation control method of the asphalt plant dryer according to claim 3, while the aggregate is heat-treated by selecting the countercurrent heating method at the time of normal operation, the aggregate for feeding the aggregate in a small amount or for the intermediate temperature mixture When operating with a reduced burner combustion amount, including during heating, select the co-current heating method, and adjust the combustion amount of the auxiliary burner so that the exhaust gas temperature becomes a predetermined set value above the dew point temperature while detecting the exhaust gas temperature. It is characterized by controlling and heating the aggregate to a predetermined temperature.

  According to the asphalt plant dryer according to claim 1 of the present invention, in the asphalt plant dryer adopting a countercurrent heating system, a sub-burner smaller than the main burner is disposed on the aggregate supply hopper side, and the sub-burner A second exhaust duct for guiding exhaust gas generated by combustion to the bag filter is connected to the aggregate discharge hopper, and a first open / close damper and a second exhaust passage are provided in each of the first exhaust duct and the second exhaust duct. Normal operation because it is equipped with an open / close damper and the aggregate can be heated even with a co-current heating method in which the flow of the aggregate supplied by the combustion of the sub burner and the opening of the second open / close damper and the flow of hot air are in the same direction In some cases, it is possible to efficiently heat the aggregate with a counter-current heating method with excellent heating efficiency, and to reduce the burner combustion amount. When the exhaust gas temperature is likely to fall close to the dew point temperature, the exhaust gas temperature can be maintained above the dew point temperature by switching to a co-current heating method in which the exhaust gas temperature is higher than the heating aggregate temperature. There is no trouble such as corrosion due to condensation.

  Further, in the asphalt plant dryer according to claim 2, the second exhaust duct is provided with an exhaust gas temperature sensor for detecting an exhaust gas temperature, and at the corner of the aggregate supply hopper in which the auxiliary burner is disposed, When the aggregate is heated by the cocurrent flow method, the combustion of the sub-burner is performed so that the exhaust gas temperature detected by the exhaust gas temperature sensor becomes a predetermined set value. Since it has an operation controller that controls the amount of exhaust air so that the static pressure value detected by the second static pressure sensor becomes a predetermined set value while controlling the amount, it operates with the cocurrent heating method Sometimes the set value of the exhaust gas temperature is higher than the heated aggregate temperature and above the dew point temperature, and the combustion amount of the sub-burner is controlled with this set value as a target, and there is no problem due to condensation.In addition, by controlling the exhaust air volume while maintaining the static pressure at the corner in the aggregate discharge hopper near the secondary burner to be slightly negative from the atmospheric pressure, the intrusion of outside air from the gap near the secondary burner is suppressed as much as possible. Exhaust without exhaustion can be performed, optimal exhaust treatment can be performed even if the exhaust conditions such as the combustion of the sub burner smaller than the main burner, the amount of water vapor generated, and the change of the exhaust path are different, and suction of excess outside air It is possible to prevent the exhaust gas temperature from being lowered due to this.

  Further, in the operation control method of the asphalt plant dryer according to claim 3, while the aggregate is heat-treated by selecting the countercurrent heating method at the time of normal operation, the aggregate for feeding the aggregate in a small amount or for the intermediate temperature mixture When operating with a reduced burner combustion amount, including during heating, select the co-current heating method, and adjust the combustion amount of the auxiliary burner so that the exhaust gas temperature becomes a predetermined set value above the dew point temperature while detecting the exhaust gas temperature. Since the aggregate is heated to a predetermined temperature by controlling it, the new material can be efficiently heat-treated by the counter-current heating method with excellent heating efficiency during normal operation, and the dryer operation such as reducing the burner combustion amount If the situation fluctuates greatly, the exhaust gas temperature can be maintained above the dew point temperature by switching to a co-current heating method in which the exhaust gas temperature is higher than the temperature of the new heating material, causing problems such as corrosion due to condensation. And no.

It is a schematic explanatory drawing which shows one Example of the dryer of the asphalt plant which concerns on this invention, and its operation | movement control method.

  In the dryer of the asphalt plant according to the present invention, the cylindrical drum is supported so as to be rotatable, and the aggregate is supplied into the drum from the aggregate supply hopper side at one end of the drum, and the bone at the other end of the drum is supplied. While flowing down to the aggregate discharge hopper side, the aggregate is heated to a predetermined temperature by making countercurrent contact with hot air supplied from the main burner disposed on the aggregate discharge hopper side, and the exhaust gas discharged from the drum is The air is sucked and exhausted by a wind exhauster downstream of the first exhaust duct connected to the aggregate supply hopper and led to the bag filter, and the aggregate can be heated by a countercurrent heating method.

  A sub-burner smaller than the main burner is disposed on the aggregate supply hopper side, and a second exhaust duct that guides exhaust gas generated by combustion of the sub-burner to the bag filter is connected to the aggregate discharge hopper. Further, when either the main burner or the sub burner is selected and burned, in order to ensure or block the exhaust gas passage, each of the first exhaust duct and the second exhaust duct has a first open / close damper and A second opening / closing damper is provided.

  Further, the second exhaust duct is provided with an exhaust gas temperature sensor for detecting an exhaust gas temperature, and a second static pressure for detecting a static pressure in the drum at a corner in the aggregate supply hopper in which the sub-burner is disposed. A sensor is provided. When the aggregate is heated by the cocurrent heating method, the combustion amount of the sub-burner is controlled so that the exhaust gas temperature detected by the exhaust gas temperature sensor becomes a predetermined set value, and the second static pressure sensor Is provided with an operation controller for controlling the amount of exhausted air so that the static pressure value detected at the above becomes a predetermined set value.

  When the dryer is normally operated, a counter-current heating method with excellent heating efficiency is selected, and while supplying hot air from the main burner, the aggregate is supplied from the opposite side and brought into counter-current contact so that the aggregate is predetermined. Heat to temperature. At this time, the combustion control of the main burner controls the amount of combustion so that the aggregate temperature discharged from the drum becomes a predetermined set value. At this time, the operation is carried out while considering that the exhaust gas temperature does not fall below the dew point temperature.

  Also, when the burner combustion amount is reduced below the rated combustion amount, such as when the aggregate supply amount is smaller than the rated supply amount, or the intermediate heating compound whose aggregate heating temperature is lower than usual is manufactured, When the exhaust gas temperature is lower than normal operation, and in some cases it is expected that the exhaust gas temperature will be lower than the dew point temperature and cause troubles such as corrosion, etc. Choose to drive.

  In the co-current heating method, the sub-burner is burned instead of the main burner, the aggregate is supplied from the same direction as the flow of hot air, and the aggregate is heated to a predetermined temperature by co-current contact. At this time, the combustion control of the auxiliary burner controls the combustion amount so that the exhaust gas temperature derived from the drum becomes a predetermined set value. In the co-current heating method, the set value of the exhaust gas temperature is higher than the heated aggregate temperature and is equal to or higher than the dew point temperature. If the burner combustion amount is controlled with this set value as a target, there is no concern about condensation.

  Further, the amount of exhaust air is controlled so that the static pressure value detected by the second static pressure sensor provided at the corner in the aggregate supply hopper on the sub-burner side becomes a predetermined set value. The set value is preferably substantially the same as the external air pressure or slightly negative pressure, for example, a value of about −10 to −30 Pa, for example, combustion of the sub-burner smaller than the main burner occurs. Even if the exhaust conditions such as the amount of water vapor and the change of the exhaust route are different, the gas generated in the drum can be sucked and exhausted without excess or deficiency, and good combustion can be maintained, and by extra air suction from the gap on the sub burner side The exhaust gas temperature drop is also suppressed as much as possible.

  During combustion of the main burner or auxiliary burner, dust accompanying the gas flow in the drum may enter the burner that is not burned and damage the burner. It is preferable to take appropriate burner protection measures such as attaching a blocker.

  As described above, since the counter-current heating type of dryer is configured so that it can be operated by the co-current heating method as well, the operating condition of the dryer may fluctuate greatly, for example, the burner combustion amount may be reduced, and the exhaust gas temperature may decrease or become below the dew point temperature When there is, the exhaust gas temperature can be maintained at the dew point temperature or more by switching to the co-current heating method in which the exhaust gas temperature is higher than the heating aggregate temperature, and it is possible to prevent troubles such as corrosion due to condensation.

  Embodiments of the present invention will be described below with reference to the drawings.

  In the figure, reference numeral 1 denotes a dryer for heat-drying an aggregate installed in an asphalt plant, and a cylindrical drum 2 having a large number of scraping blades (not shown) around its inner periphery is a base. An aggregate supply hopper 5 which is supported on an inclined surface 3 and rotated at a predetermined speed by a driving device (not shown), and an aggregate supply conveyor 4 is disposed at one end of the drum 2. The other end is provided with an aggregate discharge hopper 7 having an aggregate discharge port 6.

  The aggregate discharge hopper 7 is provided with a main burner 8 for supplying hot air, and the aggregate supply hopper 5 is connected with a first exhaust duct 9, and a dust is disposed downstream of the first exhaust duct 9. A trapping bag filter 10, a main damper 11 for adjusting the amount of exhaust air, an air exhauster 12, and a chimney 13 are provided.

  The aggregate discharge port 6 at the lower end of the aggregate discharge hopper 7 is provided with an aggregate temperature sensor 14 for detecting the temperature of the heated aggregate discharged, and the heated aggregate temperature detected by the aggregate temperature sensor 14 is detected. While controlling the amount of combustion of the main burner 8 so as to be a predetermined set value, a first static pressure sensor 15 for detecting static pressure is provided at a corner in the aggregate discharge hopper 7 provided with the main burner 8. The degree of opening and closing of the main damper 11 is adjusted so that the static pressure value detected by the first static pressure sensor 15 becomes a predetermined set value, and an amount corresponding to the amount of gas generated in the drum 2 is removed. 12 is suctioned and exhausted.

  The set value of the static pressure control is substantially the same as the external air pressure, preferably slightly negative pressure, for example, about −10 to −30 Pa so that the gas generated in the drum 2 can be exhausted substantially without excess or deficiency. Set the value of. As a result, even if the burner combustion amount or the generated water vapor amount fluctuates depending on the properties of the aggregate or the supply amount, the exhaust gas is sucked and exhausted without excess or deficiency. Wasteful outside air is introduced into the drum 2 so as not to lower the gas temperature.

  In addition to the above-described configuration, a sub-burner 16 smaller than the main burner 8 is disposed on the aggregate supply hopper 5 side so that a co-current heating method can be operated, and the sub-burner 16 is disposed in the aggregate discharge hopper 7. While connecting the 2nd exhaust duct 17 which exhausts the exhaust gas by combustion, the terminal of this 2nd exhaust duct 17 is connected with the 1st exhaust duct 9. FIG.

 Each of the first exhaust duct 9 and the second exhaust duct 17 is provided with a first open / close damper 18 and a second open / close damper 19 that block the flow of exhaust gas, and the first open / close damper 18 is provided when the sub burner 8 burns. By closing and opening the second opening / closing damper 19, the aggregate can be heated by a cocurrent heating system in which the flow of the aggregate to be supplied and the flow of hot air are in the same direction.

  The second exhaust duct 17 is provided with an exhaust gas temperature sensor 20 for detecting the exhaust gas temperature, and the combustion amount of the auxiliary burner 16 is controlled so that the exhaust gas temperature detected by the exhaust gas temperature sensor 20 becomes a predetermined set value. doing. Further, a second static pressure sensor 21 for detecting static pressure is provided at a corner portion in the aggregate supply hopper 5 provided with the sub-burner 16, and when the aggregate is heated by the cocurrent heating system, the second static pressure sensor 21 is provided. The degree of opening and closing of the main damper 11 is adjusted so that the static pressure value detected by the static pressure sensor 21 becomes a predetermined set value, and an amount corresponding to the amount of gas generated in the drum 2 by the exhaust fan 12 is set. Suction exhaust is made without excess or deficiency.

  Reference numeral 22 in the figure denotes an operation controller for operating the dryer 1, which incorporates a counter-current heating mode incorporating a control means that operates in a counter-current heating system and a control means that operates in a co-current heating system. A storage unit that stores each operation mode with the co-current heating mode and stores initial setting values such as an aggregate temperature setting value, an exhaust gas temperature setting value, and a static pressure setting value necessary for operation control in each operation mode 23.

  The operation controller 22 includes a heating aggregate temperature value detected by the aggregate temperature sensor 14 and an aggregate discharge hopper on the main burner 8 side, which are required during the countercurrent heating mode operation in which the main burner 8 is combusted. The exhaust gas temperature detected by the exhaust gas temperature sensor 20 that is required when operating in the cocurrent heating mode in which the sub-burner 16 is combusted while taking in the static pressure value detected by the first static pressure sensor 15 provided at the corner in the cylinder 7 The value and the static pressure value detected by the second static pressure sensor 21 provided at the corner in the aggregate supply hopper 5 on the sub burner 16 side are taken in, and the main burner 8 or the sub burner based on the taken detection value 16 is provided with an input / output unit 24 for outputting control signals such as a combustion amount of 16 and opening / closing of the main damper 11.

  The operation controller 22 includes an operation mode selection unit 25 for selecting and operating either the countercurrent heating mode or the cocurrent heating mode, and the operation mode selection unit 25 uses the countercurrent heating mode or the cocurrent flow mode. When one of the heating modes is selected, a control unit 26 is provided which takes in the corresponding operation mode and initial set value from the storage unit 23 and performs burner combustion control and static pressure / exhaust air volume control in the selected operation mode. ing.

  During normal operation, the counter flow heating mode is selected by the operation mode selection unit 25 of the operation controller 22. When the countercurrent heating mode is selected, the first opening / closing damper 18 is opened and the second opening / closing damper 19 is closed. And while supplying aggregate from the aggregate supply conveyor 4 side and flowing down the inside of the drum 2, it is made to counterflow contact with the hot air supplied from the main burner 8, and is heated to predetermined temperature. At this time, the combustion amount of the main burner 8 is adjusted and controlled based on the amount of difference between the heated aggregate temperature detected by the aggregate temperature sensor 14 and the set value, and the first static pressure sensor near the main burner 8 is controlled. Based on the amount of difference between the static pressure value detected at 15 and the set value, the opening degree of the main damper 11 (or the rotational speed of the exhaust fan 12) is adjusted to control the exhaust air amount.

  In addition, the cocurrent heating mode is selected by the operation mode selection unit 25 of the operation controller 22 at the time of feeding a small amount of new material in which the burner combustion amount decreases or at the time of new material heating processing for the intermediate temperature compounding material. When the co-current heating mode is selected, the first open / close damper 18 is closed and the second open / close damper 19 is opened, and the sub burner 16 is burned instead of the main burner 8, contrary to the opening / closing of the damper. The hot air supplied from the sub-burner 16 flows in the same direction as the flow of the aggregate, and contacts the parallel flow to heat the aggregate to a predetermined temperature. At this time, the combustion amount of the sub-burner 16 is adjusted and controlled based on the difference value between the exhaust gas temperature detected by the exhaust gas temperature sensor 20 and the set value, and at the second static pressure sensor 21 in the vicinity of the sub-burner 16. Based on the amount of difference between the detected static pressure value and the set value, the opening degree of the main damper 11 (or the rotational speed of the exhaust fan 12) is adjusted to control the exhaust air amount.

  In this way, even when the dryer operating conditions fluctuate significantly, such as when a small amount of new material is fed or when a new material is heat-treated for a medium-temperature compounding material, even if the operating condition of the dryer fluctuates significantly, it is better to operate using the cocurrent heating method. Although the heating efficiency is inferior to the flow heating method, the exhaust gas temperature is higher than the heating aggregate temperature, and even if the burner combustion amount is controlled by the exhaust gas temperature, the heating aggregate temperature can be controlled as it is, and the exhaust gas temperature setting value By setting the above the dew point temperature, there will be no trouble caused by condensation.

  Further, when the burner combustion amount is decreased by the counter-current heating method, the exhaust gas temperature is lowered accordingly. Therefore, the ambient temperature in the drum in the vicinity of the aggregate supply hopper 5 is decreased, and the aggregate wetted to the portion is reduced. If supplied, sand with high water content and fine particle size may adhere to check blades and scraping blades (not shown), which may cause problems such as reduced blade function and corrosion. If the operation is performed by the co-current heating method, the combustion in the auxiliary burner 16 causes the inside of the drum in the vicinity of the aggregate supply hopper 5 to become a high temperature, and the above-mentioned problems do not occur.

DESCRIPTION OF SYMBOLS 1 ... Dryer 2 ... Drum 4 ... Aggregate supply conveyor 5 ... Aggregate supply hopper 6 ... Aggregate discharge port 7 ... Aggregate discharge hopper 8 ... Main burner 9 ... First exhaust duct 10 ... Bag filter 11 ... Main damper 12 ... Ventilator 14 ... Aggregate temperature sensor 15 ... First static pressure sensor 16 ... Sub burner 17 ... Second exhaust duct 18 ... First open / close damper 19 ... Second open / close damper 20 ... Exhaust gas temperature sensor 21 ... Second static pressure sensor 22 ... Operation controller

Claims (3)

  While the cylindrical drum is rotatably supported, the bone is supplied from the aggregate supply hopper side at one end of the drum to the aggregate discharge hopper side at the other end of the drum. Downstream of the first exhaust duct, where the aggregate is heated to a predetermined temperature by making countercurrent contact with hot air supplied from the main burner disposed on the aggregate discharge hopper side, and exhaust gas discharged from the drum is connected to the aggregate supply hopper In an asphalt plant dryer that employs a countercurrent heating system that sucks and exhausts air with an air exhauster and leads to a bag filter, a sub-burner smaller than the main burner is disposed on the aggregate supply hopper side, and the sub-burner A second exhaust duct for guiding exhaust gas from combustion to the bag filter is connected to the aggregate discharge hopper, while each of the first exhaust duct and the second exhaust duct shuts off the exhaust gas flow. And a second open / close damper, and the aggregate can be heated by a co-current heating method in which the flow of the aggregate supplied by the combustion of the auxiliary burner and the opening of the second open / close damper and the flow of hot air are in the same direction. An asphalt plant dryer characterized by this.   The second exhaust duct is provided with an exhaust gas temperature sensor for detecting the exhaust gas temperature, and a second static pressure sensor for detecting the static pressure inside the drum is provided at a corner of the aggregate supply hopper provided with the sub-burner. And when the aggregate is heated by the cocurrent heating method, the combustion amount of the auxiliary burner is controlled so that the exhaust gas temperature detected by the exhaust gas temperature sensor becomes a predetermined set value, and the second static pressure sensor The asphalt plant dryer according to claim 1, further comprising an operation controller that controls the amount of exhaust air so that the static pressure value detected in step 1 becomes a predetermined set value.   The operation control method for an asphalt plant dryer according to claim 1 or 2, wherein the countercurrent heating method is selected during normal operation and the aggregate is heated, while the aggregate is used for feeding a small amount of aggregate or for medium temperature compounding. When operating with a reduced burner combustion amount, including during aggregate heating, select the co-current heating method and burn the sub-burner so that the exhaust gas temperature becomes a set value above the dew point temperature while detecting the exhaust gas temperature. An operation control method for an asphalt plant dryer, wherein the amount is controlled to heat the aggregate to a predetermined temperature.

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