SU1544857A1 - Method of stabilizing the temperature of stone materials at the outlet of drying drum - Google Patents

Abstract

This invention relates to the automation of drying and heating of materials. It can be used in countercurrent drying drums in the production of asphalt mixes. Allows to increase the accuracy of stabilization. This is achieved by changing the fuel consumption to the drum depending on the temperature of the material at the drum outlet and adjusting the fuel consumption to the drum in proportion to the change in the amount of materials passing through the drum and the moisture content of the source material. 1 il.

Description

The invention relates to the field of drying and heating of heat-resistant materials in countercurrent-type drying drums in the production of asphalt concrete mixtures.

The purpose of the invention is to improve the accuracy of stabilization.

The method is carried out as follows.

In the production of asphalt concrete, the sand and crushed stone included in its composition must be dried and heated to a temperature of 160 + 10 ° C before mixing with bitumen. The temperature of the finished hot asphalt mixture should be in the range of 140-160 С „

In commercially available asphalt mixing plants, sand and crushed stone are evenly fed into the rotating drum by a conveyor belt. The drum is installed with a slight slope and is equipped with L-shaped blades attached to the inner surface of the drum. As the drum rotates, the sand and rubble move from left to right along the drum, forming a uniform curtain over the entire volume of the drum. A furnace is installed at the right end of the drum, which provides the supply and combustion of fuel inside the drum. When burning fuel, hot flue gases passing from right to left provide

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removing moisture from sand and rubble and heating them to 160 ° C. The heated sand and crushed stone come out of the drum through the Bulk Tray and, after weighing, the weight is mixed with bitumen in the mixer.

In order to determine what amount of fuel is needed to heat sand and rubble up to 1bO ° C, the initial moisture content of the material and the amount of material passing through the drum must be known.

The moisture content of the material is measured by an automatic moisture meter, and the amount of material passing through the drum is determined by the magnitude of the current of the electric drive of the drum. The more material in the drum9, the greater the current {of the electric drive of the drum.

When the humidity and the current of the electric drive change, a corresponding proportional change in the supply of top ™ fuel is achieved by stabilizing the temperature of the materials at the outlet of the drying drum.

In order to heat the material to a predetermined temperature, it is necessary to expend fuel on evaporation of moisture, heating the material to 160 ° C and compensating for heat losses determined by the drum efficiency, usually 80%.

The drawing shows a diagram of the system for stabilizing the temperature of stone materials at the outlet of the drying drum during the production of asphalt concrete mixture, which implements the method.

Stone materials (sand and crushed stone) are fed into the rotating drum 1. The drum is installed with a slight inclination and is equipped with pouring L-shaped blades that coincide when the drum rotates on the path of hot combustion products a curtain of stone materials and ensure their movement towards the slope and discharge of hot materials after passing them along the entire length of the drum.

Stone materials are supplied by cold feed unit 2, furnace 3 provides the supply and combustion of fuel for drying and heating materials. Sensor 4, which controls the amount of material passing through the drum (the degree of material loading of the drying drum1), automatically regulates the flow, for example, current meter

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drum electric drive, sensor 5,

controlling the moisture of raw materials entering the drum,

a sensor 6 controlling the temperature of the heated materials at the drum outlet; a controller 7 controlling the fuel supply.

The system works as follows.

The operator enters the operating mode by manually changing the fuel supply until the materials set the temperature at the drum outlet for a given material feed to the drum or load level. When switching to the automatic mode of supplying fuel, materials, the humidity of the raw materials and the temperature of the materials at the drum outlet do not change for some time.

At the same time, in the established mode of operation of the system for automatically stabilizing the temperature of stone materials, the fuel supply is proportional to the predetermined load level of the drum material, moisture content of the raw materials entering the drum, and the specified heating temperature of the materials at the outlet of the drying drum.

When reducing the drum loading degree, the sensor signal controlling the material loading level of the drying drum affects the increase in the supply of material by the cold supply unit 2 and the decrease in the fuel supply by the regulator 7 and vice versa.

With an increase in the humidity of the source materials, the signal of the humidity sensor 5 acts on the increase in the fuel supply by the controller 7 and vice versa.

When the temperature of the materials at the drum output decreases, the signal of the temperature sensor 6 acts on the increase in the fuel supply by the regulator 7 and vice versa.

In all the above cases, the control actions are aimed at stabilizing the temperature of the materials at the drum outlet.

The use of the proposed method allows for increased reliability of stabilizing the temperature of stone materials, which virtually eliminates the release of underheated or overheated asphalt concrete, saving fuel by eliminating overheating of materials, and extending the time

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Claims (1)

1. A method for stabilizing the temperature of stone materials at the outlet of a cistern drum, mainly in the production of asphalt concrete mixture in a rotating drum with electric drive, including the change in fuel consumption to the drum depending on the material temperature 15 at the drum outlet, by that what. in order to improve the accuracy of stabilization, the amount of materials passing through the drum and the moisture of the source material are measured and the fuel consumption in bar is adjusted a bath, and the correction of the fuel consumption to the drum is carried out in proportion to the change in the amount of materials passing through the drum and the moisture content of the source material. 2. A method according to claim 1, characterized in that the measurement of the amount of materials passing through the drum is made according to the amount of current consumed by the drum electric drive.