JPH0737721B2 - Dust collector for asphalt plant - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dust collector for removing dust contained in exhaust gas generated by a dryer of an asphalt plant.

[0002]

2. Description of the Related Art As a dust collector for an asphalt plant, one shown in FIG. 2 is known. The dust collector mainly includes a dryer 1, a primary dust collector 2, a secondary dust collector 3, and an exhaust fan 4.

The dryer 1 is provided with a burner 6 at the lower end of a dryer drum 5 which is rotated in the circumferential direction in an inclined state, and heats and dries the aggregate and the like introduced from the upper end by a conveyor 7 and then from the lower end. Let it drain.

The primary dust collector 2 is of a cyclone type, and the exhaust gas generated in the dryer 1 is sucked by the suction duct 8 to remove dust particles having a relatively large particle diameter contained in the exhaust gas. The primary dust collector 2 is connected to a screen device (not shown) or the like for sieving the aggregate heated and dried by the dryer 1 by suction ducts 9 and 10, and also removes dust generated in those connecting portions. .

The secondary dust collector 3 is equipped with a bag filter 3a, and is provided with the suction side connected to the exhaust duct 11 of the primary dust collector 2. The exhaust fan 4 is connected to the exhaust duct 12 of the secondary dust collector 3, and the exhaust gas from the dryer 1 is sucked into the suction duct 8, the primary dust collector 2, and the exhaust duct 1.
First, the secondary dust collector 3 and the exhaust duct 12 are suctioned in this order and discharged from the chimney 13 to the atmosphere.

The dryer 1 is provided with a pressure gauge (differential pressure gauge) (pressure detection means) 14 for detecting the pressure in the dryer drum 5, and the exhaust duct 12 is provided with an opening / closing damper 15. The pressure gauge 14 and the opening / closing damper 15 are connected to the control device 16. Based on the detection signal output from the pressure gauge 14, the control device 16 increases the opening degree of the opening / closing damper 15 when the pressure inside the dryer drum 5 increases and the difference from the atmospheric pressure decreases, and also the atmospheric pressure. The opening / closing damper 15 is controlled so that the opening degree of the opening / closing damper 15 becomes smaller when the difference between and becomes larger.

In this structure, the opening / closing of the opening / closing damper 15 is controlled based on the differential pressure between the dryer drum 5 and the atmospheric pressure. As a result, for example, the amount of gas generated in the dryer 1 is changed due to the difference in the water content of the aggregate. Even if there is a change, the differential pressure between the dryer drum 5 and the atmospheric pressure is kept constant, and dust is prevented from leaking from the dryer drum 5 to the outside.

[0008]

However, with the above configuration, when the amount of gas generated by the dryer 1 changes, the flow velocity of the exhaust gas passing through the cyclone type dust collector 2 changes accordingly. Therefore, the particle size of the dust collected by the dust collector 2 varies. The collected dust is recovered and used as a part of the mixture, but if the particle size varies as described above, the quality of the mixture is not constant, which is not preferable.

It is an object of the present invention to provide a dust collector such as an asphalt plant capable of collecting dust while keeping the differential pressure between the atmospheric pressure and the atmospheric pressure in the dryer and the flow velocity of the exhaust gas constant.

[0010]

In order to achieve the above object, the present invention is directed to a dryer for heating and drying aggregates and the like to collect dust.
Machines are connected to each other through a suction duct, and
The exhaust gas generated by the
Asfa with an exhaust fan attached to the outside
Exhaust of the above dust collector in dust collectors such as dust plants
A return fan is installed between the duct and the dryer.
A part of the exhaust gas in the above exhaust duct is operated by the operation of the fan.
A return duct for returning to the dryer is provided, and the above exhaust duct
And the return duct with opening and closing dampers to open and close them.
Each of them is attached individually to the above suction duct.
The speed detection means for detecting the flow velocity of the exhaust gas flowing through
The dryer has a pressure detector for detecting the pressure in the dryer.
The above-mentioned speed detecting means is provided with each output means.
And the pressure detection means based on those detection signals.
The dryer is controlled by controlling the open / close damper or both fans.
And atmospheric pressure differential and exhaust gas flow through the suction duct
A control device was connected to keep the speed constant .

[0011]

[Action] When the amount of generated gas in the dryer is large, open provided the Rigas amount back to the dryer to the return duct
If the amount of gas generated is small by controlling the closed damper or the control of the return fan, and if the amount of generated gas is small, increase the amount of return gas to keep the exhaust gas flow rate constant, and
The amount of discharge of the exhaust gas to the outside is controlled by controlling the attached opening / closing damper or exhaust fan to keep the differential pressure between the internal pressure of the dryer and the atmospheric pressure constant.

[0012]

FIG. 1 shows an embodiment of the present invention. 1, the same members as those in FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

Reference numeral 20 is a return duct. This return duct 20 has one end connected to the middle of the exhaust duct 11 of the primary dust collector 2 and the other end connected to the dryer drum 5. The return duct 20 is provided with a return fan 21 and an opening / closing damper 22. The return fan 21 returns a part of the exhaust gas flowing through the exhaust duct 11 to the dryer drum 5, and the opening / closing damper 22 serves as the return duct 2.
Adjust the opening of 0.

A velocity meter (speed detecting means) is provided in the suction duct 8.
23 are provided. The flow velocity meter 23 detects the flow velocity of the exhaust gas flowing through the suction duct 8. The opening / closing damper 22 and the velocity meter 23 are connected to the control device 16. Control device 16
Controls the opening / closing of the opening / closing valve 15 based on the detection signal of the pressure gauge 14 as described above, and controls the opening / closing of the opening / closing damper 22 based on the detection signal of the velocity meter 23.

Next, the operation of the dust collecting apparatus for an asphalt plant or the like according to the present invention constructed as described above will be described.
While operating the dryer 1 to heat and dry the aggregate, the exhaust fan 4 is operated to allow the exhaust gas generated by the dryer 1 to pass through the dust collectors 2 and 3 and be discharged from the chimney 13 to the atmosphere.
At this time, the dust collectors 2 and 3 capture the dust in the exhaust gas.
If necessary, the return fan 21 is operated to return a part of the exhaust gas flowing through the exhaust duct 11 to the dryer 1 through the return duct 20.

The control device 16 includes a pressure gauge 14 and a velocity meter 23.
The opening degree of the opening / closing dampers 15 and 22 is controlled based on the detection signal of 1) to keep the differential pressure between the dryer 1 and the atmospheric pressure and the flow velocity of the exhaust gas flowing through the suction duct 8 constant.

That is, for example, the suction gas amount per unit time from the dryer 1 required to bring the differential pressure between the internal pressure of the dryer 1 and the atmospheric pressure to a predetermined value is "1", and the suction duct 8 is When the required flow rate of the exhaust gas flowing per unit time is "8" and the generated gas amount per unit time in the dryer 1 is "5", the control device 16
The return amount of the exhaust gas returned to the dryer 1 through the return duct 20 per unit time is “2” (“2” = “8” −
The opening / closing damper 22 is controlled so as to be “5”-“1”), and the discharge amount of the exhaust gas discharged from the chimney 13 to the atmosphere is “6” (“6” = “8” −). "2")
The opening / closing damper 15 is controlled so that When the generated gas amount in the dryer 1 is changed to "4", the opening / closing damper 2 is adjusted so that the exhaust gas return amount is "3" and the discharge amount is "5".
2, 15 are controlled.

In the above embodiment, the control device 16 controls the opening degrees of the open / close dampers 15 and 22, but the same effect can be obtained by controlling the rotation speeds of the exhaust fan 4 and the return fan 21. In addition, when the amount of gas generated in the dryer 1 can be predicted, the opening / closing control of the opening / closing dampers 15 and 22 and the rotation speed control of the fans 4 and 21 are not automatically controlled by the control device 16, but manually by an operator. It can also be controlled. Pressure gauge 14, velocity meter 23, and opening / closing damper 1
The mounting positions of 5, 22, etc. are not limited to the figures, and the types of the pressure gauge 14 and the velocity meter 23 are also arbitrary. Furthermore, the present invention can be implemented in dust collectors other than asphalt plants.

[0019]

As described above, the present invention provides an aggregate and the like.
Dust collector to the dryer to heat and dry through the suction duct
It is connected to the dust collector and collects the exhaust gas generated by the dryer.
Exhaust that is passed through the dust machine and discharged to the outside through the exhaust duct
Dust collecting equipment such as asphalt plant with air fan attached
Between the exhaust duct of the dust collector and the dryer
Equipped with a return fan
Litter that returns part of the exhaust gas in the exhaust duct to the dryer
Exhaust duct and return duct
Each has an opening and closing damper to open and close them.
Is installed in the suction duct.
The speed detection means for detecting the gas flow rate is
The dryer has pressure detecting means for detecting the pressure in the dryer.
Each is attached, and the speed detection means and pressure
Based on those detection signals, the detection means can open and close both
The damper or both fans are controlled to control the dryer and
The pressure difference between the atmospheric pressure and the flow velocity of the exhaust gas flowing through the suction duct
Since the control device that keeps it constant is connected , the flow velocity of the exhaust gas sent to the dust collector is kept constant while keeping the differential pressure between the dryer and atmospheric pressure constant, and the leakage of exhaust gas from the dryer is prevented. At the same time, the particle size of the collected dust can be made uniform.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a dust collecting apparatus for an asphalt plant or the like according to the present invention.

FIG. 2 is a block diagram of a conventional dust collector for an asphalt plant.

[Explanation of symbols]

 1 Dryer 2 Dust collector 4 Exhaust fan 11 Exhaust duct 20 Return duct 21 Return fan

Claims (1)

[Claims] 1. A dust collector is connected to a dryer for heating and drying aggregates through a suction duct , and an exhaust fan for passing exhaust gas generated by the dryer to the dust collector and discharging the exhaust gas to the outside through an exhaust duct. In a dust collector such as an asphalt plant attached, a return fan is provided between the exhaust duct of the dust collector and the dryer.
A part of the exhaust gas in the exhaust duct is removed by operating the fan.
A return duct for returning to the liner is provided, and the exhaust duct
The opening and closing dampers that open and close them
Are individually attached to the suction duct, and the suction duct is connected to the suction duct.
Velocity detecting means for detecting the flow velocity of exhaust gas flowing through the drawing duct
However, the pressure inside the dryer is detected by the dryer.
The pressure detection means for
The speed detection means and the pressure detection means are
Control both open / close dampers or both fans based on
Flow through the suction duct and the differential pressure between the dryer and atmospheric pressure.
A dust collector for an asphalt plant or the like, which is connected with a control device for keeping the flow rate of exhaust gas to be kept constant .