JPH043793B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an asphalt plant for manufacturing asphalt mixture, which is a road paving material, and particularly relates to combustion control of a burner that supplies hot air to a dryer, which is an aggregate heating device. It is about the method.

(Prior art) Combustion control in a conventional asphalt plant is as shown in the schematic flowchart of Figure 1.
First, start with low combustion and use high quality aggregates.
If aggregate is detected by an aggregate sensor installed near the inlet of the dryer, automatic combustion control is performed by switching to high combustion mode. This automatic combustion control detects the temperature of the heated aggregate discharged from the dryer, compares it with a preset aggregate temperature, and adjusts the combustion amount of the burner and the amount of combustion air using a control signal according to the comparison. Combustion is controlled by driving the control motor.

(Problem to be solved by the invention) However, as mentioned above, automatic combustion control controls the combustion of the burner in response to the temperature of the heated aggregate discharged from the dryer. When the control is performed, the aggregate has not reached the dryer outlet, and combustion is controlled at a low virtual aggregate temperature, and the combustion amount reaches the maximum and the aggregate is used more than necessary until the aggregate reaches the dryer outlet. There was a problem with the quality of the asphalt mixture, which was produced by heating and raising the temperature.

(Means for Solving the Problems) The present invention has been developed in view of the above-mentioned shops, and it is possible to reduce the amount of aggregates beyond the required amount by initially burning the aggregates at a preset combustion rate until the aggregates reach the outlet of the dryer. This prevents it from being heated.

That is, the present invention provides a temperature sensor in the exhaust flue that guides the gas flow passing through the dryer, which is a heating device, detects the exhaust gas temperature at the start of aggregate supply with the temperature sensor, and adjusts the exhaust gas temperature to the exhaust gas temperature. The asphalt is characterized in that after initial combustion is performed in the burner with a preset combustion amount and combustion time, the combustion amount of the burner is controlled in response to the temperature of heated aggregate discharged from the dryer. The present invention provides a combustion control method in a plant.

(Function) According to the present invention, the exhaust gas temperature at the start of aggregate supply is detected, and initial combustion is performed in the burner with a preset combustion amount and combustion time based on the exhaust gas temperature. It is possible to produce high-quality asphalt mixture without heating it more than necessary.

(Example) Hereinafter, the present invention will be explained based on examples.

FIG. 2 is a system diagram of combustion control of a dryer in an asphalt plant.

In the figure, 1 is a dryer in which a cylindrical body with a large number of scraping blades arranged around its inner periphery is tilted and rotatably supported, and aggregate cut from an aggregate hopper 2 stored in various particle sizes is transferred to a belt conveyor. 3 and 4 into the dryer 1, and the aggregate is rolled and flowed down while being scraped up by scraping blades provided around the inner periphery. 5 is a liquid fuel spray burner, and the burner 5 sends combustion gas into the dryer 1, and an exhaust fan 7 disposed at the end of an exhaust flue 6 connected to the dryer 1 sucks the combustion gas. A high-temperature gas flow is maintained through the dryer 1, and the rolling aggregate is heated and dried. Since the exhaust gas discharged through the exhaust flue 6 contains a large amount of dust, a dry cyclone dust collector (not shown) is used to remove coarse particles of dust, and a bag filter 8 is used to remove finer dust particles. It is released into the atmosphere from chimney 9. 10 is an aggregate sensor that detects the aggregate conveyed by the belt conveyor 4, and 11 is a temperature sensor that detects the temperature of the heated aggregate discharged from the dryer 1. 12 is a temperature sensor that detects the temperature of exhaust gas passing through the exhaust flue 6,
In the embodiment, it is provided at the entrance of the bag filter 8. 13 is a process input/output device that exchanges analog and digital contact signals with external equipment;
The signal detected by the sensor is transmitted to the central processing controller 14 via the process input/output device 13. The central processing control unit 14 processes signals input from external equipment, has a storage device for storing necessary operation programs, displays, recording signals, etc., and controls the entire plant. Reference numeral 15 denotes a CRT display device that displays the output results of the central processing control unit 14 in a message or graphic form on a cathode ray tube.
A keyboard 16 is attached for selecting the screen of the display device 15 and inputting signals. Reference numeral 17 denotes an operator's console comprised of pushbutton switches and the like for operators to operate the plant. A combustion control circuit 18 controls the amount of combustion in accordance with a control signal sent from the central processing controller 14, and controls the control motor 19 to control the intake of fuel and fuel air to the burner 5.

Next, a combustion control method will be explained.

FIG. 3 is a general flowchart of combustion control. First, low combustion is started, and high-grade aggregate is started from the aggregate hopper 2. Aggregate sensor 10
When the aggregate sensor 10 detects that the temperature has reached the position of An output signal is given to the combustion control circuit 18 so that the combustion amount is maintained for the set combustion time to perform initial combustion. This initial combustion is performed until the aggregate passes through the dryer 1 and reaches the aggregate sensor 11, and the aggregate sensor 11 can detect the true aggregate temperature. The time and other information are entered on the keyboard 16 along with various setting values before operation. FIG. 4 shows an initial combustion setting screen displayed on the CRT display device 15, on which the exhaust gas temperature range, the combustion time within that temperature range, and the combustion opening degree of the burner 5 are previously set and input. In Figure 4, the exhaust gas temperature range settings are below 60℃, 60~80℃, and 80℃.
Although three patterns of temperatures above ℃ are set, this is not limited to three patterns. In the initial combustion, when the detected exhaust gas temperature is low, the combustion amount of the burner 5 is increased, and when the exhaust gas temperature is high, the combustion amount of the burner 5 is increased because the dryer 1 and the exhaust flue 12 have already been heated in the previous operation. By reducing the amount, the aggregate is not heated more than necessary, and the exhaust gas temperature is also prevented from rising too much and burning the filter cloth of the bag filter 8. Since the set value is influenced by, for example, the amount of aggregate supplied, the moisture content of sand, etc., it is preferable to determine and set the set value by taking these operating conditions into consideration through trial runs or the like.

After the initial combustion is completed, the automatic combustion control shifts to the same automatic combustion control as in the past. This automatic combustion control detects the temperature of the heated aggregate discharged from the dryer 1 with the temperature sensor 11 as described above, and then uses the central The control device 14 compares the aggregate temperature with a preset temperature, and sends a control signal corresponding to the comparison to the combustion control circuit 18 to drive and control the control motor 19, which adjusts the combustion amount and combustion air amount of the burner 5. control.

(Effects of the Invention) As described above, in the present invention, the exhaust gas temperature at the start of aggregate supply is detected, and the combustion amount is preset based on the exhaust gas temperature to prevent the aggregate from being overheated. Unlike conventional methods, it detects the low fictive temperature of the aggregate that has not reached the dryer outlet, and uses automatic combustion control to combust it at the maximum amount to heat the aggregate more than necessary. Since there is no carbon, the quality of asphalt composite material can be improved. Furthermore, since the exhaust gas does not reach an extremely high temperature, it is possible to prevent the filter cloth of the bag filter from burning out.

[Brief explanation of drawings]

Fig. 1 is a schematic flowchart of the conventional combustion control method, Fig. 2 is a system diagram of combustion control of an asphalt plant dryer, Fig. 3 is a schematic flowchart of the combustion control method of the present invention, and Fig. 4 is a CRT display. This is the initial combustion setting screen of the device. 1... Dryer, 2... Aggregate hopper, 5... Burner, 6... Exhaust flue, 8... Bag filter,
10... Aggregate sensor, 11, 12... Temperature sensor, 13... Process input/output device, 14... Central processing control unit, 15... CRT display device, 16...
Keyboard, 17... Operator's console, 18... Combustion control circuit, 19... Control motor.

Claims (1)

[Claims] 1. A temperature sensor is installed in the exhaust flue that guides the gas flow through the dryer, which is a heating device, and the temperature sensor detects the exhaust gas temperature at the start of aggregate supply, and the temperature is set in advance according to the exhaust gas temperature. A method for controlling combustion in an asphalt plant, characterized in that the combustion amount of the burner is controlled in response to the temperature of heated aggregate discharged from a dryer after initial combustion is performed in the burner according to the combustion amount and combustion time. .