JP2013104258A - Asphalt pavement waste material regenerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an asphalt pavement waste material regenerating device for reducing the amount of exhaust gas to achieve energy saving by effectively utilizing the exhaust gas from a waste material dryer when subjected to deodorizing treatment in a deodorization furnace, as secondary combustion air for a burner of the deodorization furnace to reduce the amount of combustion air to be supplied from a combustion air supply fan.SOLUTION: An exhaust duct 9 of a waste material dryer 2 is connected to a burner flame formation part 20 of a deodorization furnace 3, and an oxygen concentration meter 21 is provided on the downstream side thereof for detecting an oxygen concentration in combustion gas. On the other hand, in a burner combustion controller 22, the reference concentration of residual oxygen in the combustion gas formed during the complete combustion of a burner 16 in the furnace is preset as a target oxygen concentration. The amount of air blown by a combustion air supply fan 23 is adjusted to keep the oxygen concentration in the combustion gas at the target oxygen concentration while avoiding the supply of extra combustion air. This reduces the amount of exhaust gas to achieve energy saving.

Description

  The present invention relates to an asphalt pavement waste material recycling apparatus capable of heating and regenerating asphalt pavement waste material generated by road construction or the like.

  Asphalt pavement waste material recycling equipment that recycles asphalt pavement waste material (hereinafter referred to as “waste material”) generated by road construction, etc. is an asphalt pavement waste material regeneration dryer (hereinafter referred to as “waste material dryer”) that heats and recycles waste material by exposing it to hot air from a burner. And a deodorizing furnace for deodorizing by burning and decomposing odor components generated during heat regeneration of waste materials. In the waste dryer, for example, as disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2010-281117), a part of the exhaust gas is circulated and supplied to the throat portion at the tip of the burner via the branch duct, It is known that the residual oxygen is effectively used as the secondary combustion air for the burner.

  At this time, the burner controller of the waste material dryer controls the amount of combustion and the amount of air blown by the combustion air supply fan (primary combustion air amount) to burn the burner, but the amount of air blown introduced as the primary combustion air is The amount of air required for burner combustion (approximately 1.2 in terms of air ratio) is not covered by all of the air. For example, the amount of air in the air ratio is limited to approximately 0.6, while the remaining air required for burner combustion. The amount is controlled by controlling the amount of air blown from the exhaust fan of the branch duct so that the amount of exhaust gas (secondary combustion air) equivalent to about 0.6 is introduced into the throat at the burner tip to secure combustion air. As a result, the amount of exhaust gas is reduced to improve fuel efficiency.

JP 2010-281117 A

  By the way, in the deodorizing furnace installed on the downstream side of the waste material dryer, a furnace temperature maintaining burner is provided at one end of the furnace body, and the furnace temperature is maintained at a high temperature of about 750 ° C. by combustion of the burner. However, exhaust gas from the waste material dryer is introduced into this furnace and exposed to a high-temperature atmosphere, and the odor components in the exhaust gas are burned and decomposed to deodorize the residual oxygen in the exhaust gas. I think that it can be used as.

  However, if the exhaust gas containing residual oxygen is used as the secondary combustion air while fixing the blast amount of the combustion air supply fan supplied to the burner to an air ratio of 1 or less as in the prior art, The blast volume of the combustion air supply fan is fixed at the set air ratio, and only the amount of exhaust gas corresponding to the air ratio can be reduced. In addition, uncertain factors such as fluctuations in the oxygen concentration in the exhaust gas depending on the operating state of the equipment and the extent to which the residual oxygen in the exhaust gas is effectively consumed as secondary combustion air are considered. Then, in order to maintain the stable combustion of the burner, there is a problem that the air ratio, which is the blowing amount of the combustion air supply fan, cannot be made too small. Since the exhaust gas from this deodorizing furnace is a high temperature of about 750 ° C. and is released into the atmosphere from the chimney with a large amount of retained heat, if the amount of exhaust gas can be reduced as much as possible, energy saving can be achieved. It seems to be particularly effective.

  In view of the above points, the present invention effectively uses as the secondary combustion air of the burner of the deodorization furnace when the exhaust gas from the waste material dryer is deodorized in the deodorization furnace, and is used for combustion while stably burning the burner. It is an object of the present invention to provide an asphalt pavement waste material recycling apparatus that reduces the amount of exhaust gas and saves energy by reducing the amount of combustion air supplied from an air supply fan as much as possible.

  In order to solve the above-mentioned problem, in the asphalt pavement waste material recycling apparatus according to claim 1 according to the present invention, a deodorization furnace for disposing the odor components in the exhaust gas by heat decomposition is disposed downstream of the exhaust duct of the waste material dryer, The furnace is provided with a burner that maintains the interior of the furnace at a predetermined temperature, and is provided with a burner combustion controller that controls the amount of air blown from the combustion air supply fan in accordance with the amount of combustion of the burner. In the asphalt pavement waste material recycling apparatus configured to form a burner flame in the furnace and supply hot air while controlling the combustion of the burner, residual oxygen in the exhaust gas of the waste material dryer is used for secondary combustion of the burner of the deodorization furnace The exhaust duct of the waste dryer is connected to the burner flame forming part of the deodorizing furnace so that it can be used as air, and oxygen which detects the oxygen concentration in the combustion gas is located downstream of the burner flame forming part. On the other hand, the burner combustion controller is preset with a target concentration of residual oxygen in the combustion gas when the burner is completely burned in the furnace as a target oxygen concentration. The combustion air supply fan is adjusted so that the oxygen concentration in the combustion gas detected in this way is maintained at the target oxygen concentration, so that the combustion air is not supplied excessively.

  Moreover, in the asphalt pavement waste material recycling apparatus according to claim 2 according to the present invention, the burner combustion controller is configured so that the amount of air blown from the combustion air supply fan required for stable combustion of the burner for each combustion amount. The lower air volume is set as a lower limit air flow, and the air flow of the combustion air supply fan is controlled so as not to fall below the lower air volume.

  According to the asphalt pavement waste material recycling apparatus according to claim 1 of the present invention, the exhaust duct of the waste material dryer is connected to the burner flame forming portion of the deodorizing furnace, and oxygen in the combustion gas is disposed downstream of the burner flame forming portion. While equipped with an oxygen concentration meter for detecting the concentration, the burner combustion controller is set in advance as a target oxygen concentration, a target concentration of residual oxygen in the combustion gas when the burner is completely burned in the furnace, Since the combustion air supply fan is adjusted so that the oxygen concentration in the combustion gas detected by the oxygen concentration meter is maintained at the target oxygen concentration, the combustion air is not supplied excessively. Even if the oxygen concentration of the exhaust gas used as the secondary combustion air fluctuates, and it is unclear how effectively the residual oxygen in the exhaust gas is consumed as the secondary combustion air, In order to feedback control the blast volume of the combustion air supply fan according to the oxygen concentration in the side combustion gas, the amount of combustion air supplied from the combustion air supply fan can be reduced as much as possible while stably burning the burner, As a result, the amount of exhaust gas can be reduced and energy saving can be achieved.

  According to the asphalt pavement waste material recycling apparatus according to claim 2 of the present invention, the burner combustion controller is configured so that the amount of air blown from the combustion air supply fan necessary for stable combustion of the burner is set for each combustion amount. It is set as the lower limit air flow rate, and the air flow rate of the combustion air supply fan is controlled so that it does not fall below the lower limit air flow rate. Thus, it is possible to reliably avoid this problem and to maintain stable burner combustion.

It is a schematic explanatory drawing which shows one Example of the asphalt pavement waste material reproduction | regeneration apparatus which concerns on this invention. It is a control map showing the relationship between the fuel supply amount with respect to the burner combustion amount (%), the blowing amount of the combustion air supply fan, and the target oxygen concentration.

  In the asphalt pavement waste material recycling apparatus according to the present invention, the exhaust duct of the waste material dryer is connected to the burner of the deodorization furnace so that residual oxygen in the exhaust gas of the waste material dryer can be used as secondary combustion air of the burner of the deodorization furnace. In addition to being connected to the flame forming unit, an oxygen concentration meter for detecting the oxygen concentration in the combustion gas is provided on the downstream side. In addition, the burner combustion controller that controls the amount of air blown by the combustion air supply fan according to the amount of combustion of the burner in the deodorization furnace is a guideline for the residual oxygen in the combustion gas when the burner is completely burned in the furnace. The concentration is set in advance as a target oxygen concentration, and the air flow rate of the combustion air supply fan is adjusted and controlled so that the oxygen concentration in the combustion gas is maintained at the target oxygen concentration. It should be noted that the target oxygen concentration is unclear that the amount of residual oxygen in the exhaust gas from the waste dryer fluctuates and how effectively the residual oxygen in the exhaust gas is consumed as secondary combustion air for the burner. In consideration of uncertain factors such as, and the like, it may be determined as appropriate with reference to a combustion test or the like.

  In addition, when adjusting the air flow rate of the combustion air supply fan, the air flow rate is reduced and oxygen necessary for burner combustion is supplied, but the air flow rate is small and the burner flame may not be properly maintained. In view of this, the burner combustion controller previously sets the air blowing amount of the combustion air supply fan necessary for stable combustion of the burner as the lower limit air blowing amount for each combustion amount. Control is performed so that the air flow rate of the supply fan does not fall below the lower limit air flow rate.

  When the waste material is heated and regenerated by the asphalt pavement waste material recycling device having the above configuration, the exhaust gas from the waste material dryer is introduced into the burner flame forming part of the deodorization furnace via the exhaust duct, and the odor components in the exhaust gas are combusted and decomposed. Thus, while deodorizing, the remaining oxygen in the exhaust gas is utilized effectively as secondary combustion air for the burner. At this time, the burner combustion controller sequentially takes in the furnace temperature from the thermometer for detecting the temperature in the furnace to increase or decrease the burner combustion amount, and controls the blown amount of the combustion air supply fan in conjunction with this. At this time, the oxygen concentration in the combustion gas detected by the oxygen concentration meter provided on the downstream side of the burner flame forming portion is sequentially taken and compared with a preset target oxygen concentration, and the detected oxygen concentration is higher than the target oxygen concentration. If it is higher, fine adjustment is made by reducing the amount of air blown from the combustion air supply fan. As a result, the amount of air blown by the combustion air supply fan is reduced from the normal amount of air blown, and is suppressed from supplying excess combustion air.

  Further, in the burner combustion controller, when the air flow rate of the combustion air supply fan is controlled to be reduced, when the preset lower limit air flow rate is reached, the lower air flow rate is maintained without further reducing the air flow rate. To burn the burner stably.

  In this way, exhaust gas from the waste dryer is introduced into the burner flame formation part of the deodorization furnace and used as secondary combustion air for the burner while deodorizing the exhaust gas, and detected downstream of the burner flame formation part Since the air flow rate of the combustion air supply fan is adjusted and controlled so that the oxygen concentration in the combustion gas to be maintained at a preset target oxygen concentration, the air flow rate from the combustion air supply fan is controlled while stably burning the burner. It can be reduced as much as possible, reducing the amount of exhaust gas and saving energy.

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

  1 in the figure is an asphalt pavement waste material recycling apparatus according to the present invention, which mainly comprises a waste material dryer 2 that heats and recycles waste material, and a deodorization furnace 3 that burns and decomposes odor components generated during heat regeneration of the waste material and deodorizes it. It is configured. The waste material dryer 2 rotatably supports a cylindrical drum 4 having a large number of scraping blades (not shown) on its inner periphery on a machine base (not shown) to drive a motor ( (Not shown) is rotated at a predetermined speed. The hot hopper 5 on the one end side of the drum 4 is provided with a burner 7 through a combustion chamber 6, and hot air is supplied into the drum 4 while forming a flame in the combustion chamber 6 ahead by the burner 7. The high temperature that passes through the drum 4 by being sucked by the exhaust fan 11 while adjusting the air volume with the air volume adjusting damper 10 interposed downstream of the exhaust duct 9 connected to the cold hopper 8 on the other end side of the drum 4. Maintaining gas flow.

  A waste material storage hopper (not shown) for storing waste material is installed in the vicinity of the waste material dryer 2, and the waste material discharged from the waste material storage hopper is supplied into the drum 4 via the belt conveyor 12, and the waste material is While the drum 4 is rolling down, it is brought into contact with the hot gas flow to be heated to a desired temperature, and sequentially discharged from a discharge port below the cold hopper 8 downstream. Reference numeral 13 denotes a circulation duct that is branched from the middle of the exhaust duct 9. The other end of the circulation duct 13 is connected to the combustion chamber 6, and a part of the exhaust gas that is discharged from the exhaust duct 9 and has a slightly lowered temperature. Is circulated through the combustion chamber 6.

  The deodorizing furnace 3 is provided with a burner 16 that maintains the inside of the furnace at a predetermined temperature at one end thereof, the exhaust gas from the waste dryer 2 introduced into the furnace is exposed to a high temperature atmosphere, and asphalt volatile matter contained in the exhaust gas Deodorizing treatment is possible by burning and decomposing odor components. The deodorizing furnace 3 controls the furnace temperature so that odor components can be completely burned and decomposed, for example, the combustion amount of the burner 16 so as to maintain a high temperature of about 750 ° C. or higher, and the exhaust gas passes through the furnace. It is preferable to have a furnace length that takes at least 1 to 2 seconds or more. Then, the high-temperature exhaust gas that has passed through the deodorizing furnace 3 is purified and discharged into the atmosphere from the end chimney 18 through the exhaust duct 17.

  The exhaust duct 9 of the waste dryer 2 passes through a heat exchanger 19 disposed in the middle of the exhaust duct 9 to preheat the exhaust gas, and then the burner flame forming section 20 (for example, the burner 16 uses the burner 16 to enter the furnace). The oxygen concentration meter 21 detects the oxygen concentration in the combustion gas on the downstream side of the burner flame forming section 20 (for example, near the end of the burner flame). It has. In addition, since the connection part of the furnace main body of the deodorizing furnace 3 and the burner 16 is sealed and there is no intrusion of outside air into the furnace, the oxygen concentration in the combustion gas is detected on the downstream side of the burner flame forming part 20. Thus, it is possible to grasp the combustion state such as excess or deficiency of the oxygen amount required for burner combustion relatively accurately.

  22 is a burner combustion controller for controlling the combustion amount of the burner 16 and the blown air amount of the combustion air supply fan 23 based on the furnace temperature. The burner combustion controller 22 detects detected values from various sensors and control signals to each device. An input / output unit 24 that inputs and outputs, a setting storage unit 25 that registers various setting values for control, and a control unit 26 that executes various controls based on these various detection values and setting values are mainly configured. ing.

  The burner combustion controller 22 takes in the furnace temperature sequentially detected by the thermometer 27 provided in the furnace body of the deodorizing furnace 3 and opens the fuel supply valve 29 via the control motor 28 based on the detected temperature. In other words, the burner combustion amount is controlled by adjusting the fuel supply amount, and the opening degree of the blower amount adjustment damper 31 of the combustion air supply fan 23 is adjusted via the control motor 30 according to the burner combustion amount. The amount of combustion air is adjusted.

  In the setting storage unit 25 of the burner combustion controller 22, the burner 16 is used as the secondary combustion air of the burner 16 when the exhaust gas introduced from the exhaust duct 9 of the waste dryer 2 is deodorized. The reference concentration of residual oxygen in the combustion gas when the gas is completely burned is set in advance as the target oxygen concentration. The target oxygen concentration may be set for each burner combustion amount, for example, about 7 to 9%. The burner combustion controller 22 is configured to adjust and control the blowing amount of the combustion air supply fan 23 so that the oxygen concentration in the combustion gas detected by the oximeter 21 is maintained at the target oxygen concentration. Yes.

  Further, as shown by a two-dot chain line in FIG. 2, the setting storage unit 25 includes a lower limit air blowing amount (lower limit combustion air amount) necessary for stably burning the burner 16 for each burner combustion amount. It is set in advance. In addition, as indicated by a one-dot chain line in FIG. 2, a reference blast amount (reference combustion air amount, for example, air ratio 1.2) supplied by the combustion air supply fan 23 is set in conjunction with the burner combustion amount. ing. Then, in the burner combustion controller 22, with respect to the burner combustion amount (%) on the horizontal axis in FIG. 2, the upper limit is the reference air flow rate (reference combustion air amount) that is the intersection on the vertical line, and the lower limit air flow rate ( The amount of air blown by the combustion air supply fan 23 is adjusted and controlled within a range in which the lower limit combustion air amount) is the lower limit.

  When the waste material is heated and regenerated by the asphalt pavement waste material recycling apparatus 1 configured as described above, the exhaust gas exhausted from the waste material dryer 2 is introduced into the flame forming unit 20 of the deodorizing furnace 3 through the exhaust duct 9, The residual oxygen in the exhaust gas is utilized effectively as secondary combustion air for the burner 16 while decomposing it by exposing it to a high-temperature atmosphere in the furnace and subjecting it to combustion decomposition. At this time, the burner combustion controller 22 takes in the furnace temperature sequentially detected by the thermometer 27, adjusts the opening of the fuel supply valve 29 via the control motor 28 based on the furnace temperature, and burners. The amount of combustion (air amount for combustion) is adjusted by controlling the amount of combustion and adjusting the opening degree of the air amount adjustment damper 31 of the combustion air supply fan 23 via the control motor 30 according to the amount of combustion of the burner. .

  At this time, the oxygen concentration in the combustion gas detected by the oxygen concentration meter 21 is sequentially taken, the oxygen concentration is compared with a preset target oxygen concentration, and the combustion air supply fan 23 is based on the difference value amount. The opening degree of the air flow adjustment damper 31 is finely adjusted. For example, as shown in FIG. 2, if the burner combustion amount (%) is at position a, the amount of air blown from the combustion air supply fan 23 is reduced from the reference air amount (reference combustion air amount) b0 to the lower limit air volume ( It is controlled between the lower limit combustion air amount b1.

  In this way, the amount of air blown from the combustion air supply fan 23 is reduced from the normal amount of air blowing while maintaining stable combustion of the burner 16, and is suppressed so as not to supply excess combustion air as much as possible. As a result, the amount of high-temperature exhaust gas discharged from the deodorizing furnace 3 can be reduced and energy saving can be effectively achieved.

  In the embodiment, the oximeter 21 is installed in the vicinity of the flame end of the burner 16. However, if it is possible to grasp the complete combustion of the burner 16, it is installed at the outlet of the deodorizing furnace 3 or the downstream exhaust duct 17. You may do it.

  In the embodiment, the combustion air supplied from the combustion air supply fan 23 of the burner 16 is normal air at room temperature. However, the present invention is not limited to this. It is only necessary to supply a minimum amount of air containing the necessary amount of oxygen. For effective use of exhaust gas heat, it is possible to use outside air (preheated air) that has been heated up by exchanging heat with the exhaust gas of the deodorizing furnace 3. The exhaust gas from the deodorizing furnace 3 adjusted to a low oxygen concentration that can be combusted by mixing outside air may be circulated and used.

  Further, although the air flow rate of the combustion air supply fan 23 is adjusted by controlling the opening degree of the air volume adjusting damper 31, the rotational speed of the combustion air supply fan 23 may be inverter-controlled. Of course, various changes can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Asphalt pavement waste material recycling apparatus 2 ... Waste material dryer 3 ... Deodorizing furnace 9 ... Exhaust duct (waste material dryer)
16 ... Burner (deodorization furnace) 17 ... Exhaust duct (deodorization furnace)
DESCRIPTION OF SYMBOLS 20 ... Burner flame formation part 21 ... Oxygen concentration meter 22 ... Burner combustion controller 23 ... Combustion air supply fan 31 ... Blowing amount adjustment damper

Claims (2)

  A deodorizing furnace is provided downstream of the exhaust duct of the waste material dryer to thermally decompose the odor components in the exhaust gas, and a burner for maintaining the interior of the furnace at a predetermined temperature is disposed in the deodorizing furnace, and the burner according to the combustion amount of the burner. An asphalt comprising a burner combustion controller for controlling the amount of air blown by the combustion air supply fan, and supplying hot air by forming a burner flame in the furnace while controlling the combustion of the burner by the burner combustion controller In the pavement waste material recycling apparatus, the exhaust duct of the waste material dryer is connected to the burner flame forming part of the deodorization furnace so that residual oxygen in the exhaust gas of the waste material dryer can be used as secondary combustion air of the burner of the deodorization furnace, On the downstream side of the burner flame forming section, an oxygen concentration meter for detecting the oxygen concentration in the combustion gas is provided, while the burner combustion controller has a combustion gas when the burner is completely burned in the furnace. The reference concentration of residual oxygen is preset as the target oxygen concentration, and the combustion air supply fan is fed so that the oxygen concentration in the combustion gas detected by the oximeter is maintained at the target oxygen concentration. An asphalt pavement waste material reclaiming device characterized by adjusting the air volume and not supplying extra combustion air.   In the burner combustion controller, the amount of air blown from the combustion air supply fan necessary for stable combustion of the burner is set as the lower limit air blow amount for each combustion amount, and the amount of air blown from the combustion air supply fan is set. The asphalt pavement waste material recycling apparatus according to claim 1, wherein the asphalt pavement waste material recycling apparatus is controlled so as not to fall below a lower limit blowing amount.

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