JPS6233905A - Control of rotation of dryer of asphalt plant - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for controlling the rotation of a dryer in an asphalt plant that produces asphalt mixture for road paving.

(b) Conventional technology Asphalt plant dryers are designed with drum size, rotation speed, blade shape, number of blades, etc. depending on the desired drying capacity, and the drum always rotates at a constant rotation speed. ing.

(c) Problems to be solved by the invention In asphalt plants, combustion gas sent into the drum is sucked by an exhaust fan installed at the end of the drum exhaust flue to maintain a high-temperature gas flow passing through the drum. The aggregate is heated. Therefore, it is good when the amount of gas generated in the drum (the sum of the amount of combustion gas sent in from the burner and the amount of water vapor generated from the aggregate) and the amount of gas sucked in by the exhaust fan is balanced, but when the balance is disrupted. ,
If the amount of gas sucked in by the exhaust fan is insufficient compared to the amount of gas generated in the drum, excess gas will be present in the drum, which will prevent good combustion and reduce drying efficiency. .

In recent years, as the amount of construction work has increased, it has become increasingly difficult to stably obtain high-quality aggregates, and it is therefore difficult to obtain aggregates with a constant moisture content. Therefore, when aggregates with high moisture content are heated and dried, a large amount of water vapor is generated in the drum, and the amount of gas corresponding to the increased amount cannot be sucked and exhausted by the exhaust fan, so excessive gas is generated in the drum. It is common practice to reduce the feed of aggregate into the drum as the moisture content of the aggregate increases, since this can interfere with good combustion conditions.

If the amount of aggregate supplied into the drum is reduced, the amount of aggregate scraped by the scraping blades will also be reduced, making it impossible to maintain the desired heating efficiency and resulting in poor fuel efficiency.

(d) Means for Solving the Problems The present invention provides a drive for rotating a cylindrical drum 3 in which a cylindrical drum 3 having a large number of blades 2 is rotatably supported at an angle. The motor 5 is a variable speed motor, and the rotation speed of the drum 3 is controlled to vary in response to an increase or decrease in the amount of aggregate supplied into the drum.

(E) Function In the present invention, when heating the aggregate, the aggregate is supplied from one end of the drum 3, and fed from the burner 7 while being raked up by the raking blades 2 and flowing down the drum. Heat by contacting with combustion gas.

At this time, the number of rotations of the drum 3 is changed depending on the moisture content of the aggregate supplied to the drum 3. For example, when the water content of the aggregate increases and the amount of aggregate supplied is to be reduced, the variable speed motor 5 that rotates the drum 3 is controlled to increase the number of rotations of the drum 30, and the aggregate is removed by the raking blades 2. The heating efficiency is improved by increasing the scraping area and increasing the opportunities for the aggregate to come into contact with the high-temperature gas flow passing through the drum 3.

(F) Embodiment 1 is a dryer that heats aggregate, and is of a rotary kiln type, in which a cylindrical drum 3 with a large number of raking blades 2 arranged around it is mounted on a machine base 4 and is rotatable. It is tilted and pivoted. 5 is a drive motor that rotates the drum,
A variable speed motor is employed, and by rotating the support roller 6 by the variable speed motor 5, the drum 3 placed on the support roller 6 is rotated. Reference numeral 7 denotes an eight installed at one end of the drum 3, which feeds the combustion residue into the drum 3 and also sends the combustion residue into the exhaust flue at the other end of the drum 3 (
While maintaining the gas flow through the drum 3 by suctioning the gas with an exhaust fan installed at the end of the drum (not shown), a predetermined amount of aggregate of various particle sizes is transferred to the belt according to the composition of the asphalt mixture to be manufactured. Feed through conveyor 8 and scrape up aggregate with blades 2
It is heated up to a desired temperature while flowing down inside the drum 3 while being scraped up by the drum 3.

If the moisture content of the aggregate increases and the amount of aggregate supplied to the drum 3 is reduced, the rotation speed of the drum 3 is increased by increasing the rotation speed of the variable speed motor, and the aggregate is Increase the amount of raking to increase heating efficiency. Control of a variable speed motor can be easily performed using a commercially available inverter. Automatic control is also possible by controlling the rotation speed of the drum 3 in substantially inverse proportion to the amount of aggregate supplied.

(G) Effects of the Invention The present invention provides a variable speed motor for the drive motor 5 that rotates the drum 3 of the dryer 1 of an asphalt plant, and by making it possible to change the rotational speed of the drum 3, aggregates to the drum 3 can be changed. The drum 3 is controlled to rotate at the optimum rotation speed according to the amount of supply. Especially when the moisture content of the aggregate is high and the amount of aggregate supplied into the drum 3 is to be reduced, the rotation speed of the drum 3 is By increasing the rotation speed and increasing the amount of aggregate scraped up by the scraping blades 2, heating efficiency can be improved.
Furthermore, since the residence time of the aggregate in the drum 3 can be shortened, it has the practical benefit of improving processing capacity.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view of a dryer for an asphalt plant.

Claims (1)

[Claims] A cylindrical drum with a large number of raking blades arranged inside is rotatably supported on an inclined axis, and the drive motor that rotates the drum is a variable speed motor, responding to increases and decreases in the amount of aggregate supplied into the drum. A method for controlling the rotation of a dryer in an asphalt plant, characterized in that the rotation speed of a drum is changed by changing the number of rotations of a drum.