JPH04157000A - Drying method for slurry by rotary drier - Google Patents

Abstract

PURPOSE:To allow stable drying of even a slurry, such as sludge, by controlling the discharge temp. from the drier together with the required driving power for rotating a drum or the required driving power for rotating crushing and dgitating vanes or the detected value from torque. CONSTITUTION:The temp. of an exhaust gas is detected by a temp. detector 12 mounted at a proper point of a discharge duct 11 and the driving power required for rotating the drum 2 or the driving power or the torque required for rotating the crushing and agitating vanes 4 is detected by meter relays 15, 16 and the detected values are inputted to a computer. The computer controls a motor 8 of a screw conveyor 7 in a charging hopper 6 and a hot stove 9 in accordance with these inputted values. If the detected value from the temp. detector 12 and the detected value of the driving power required for rotating the drum 2 or the driving power or torque required for rotating the crushing and agitating vanes 4 both exceed reference values, the rotation of the motor 8 is controlled according to the ratio thereof to decrease the charge of the slurry or to increase the heat quantity from the hot stove 9.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an improvement in a method for drying muddy substances such as sludge using rotary drying having a crushing stirring blade.

BACKGROUND OF THE INVENTION Conventionally, the following method has been used to dry muddy substances such as sludge using a rotary dryer having crushing and stirring blades.

That is, the temperature of the exhaust gas from the dryer is detected and if this rises above a predetermined temperature.

Increase the amount of sludge input into the dryer or reduce the amount of heat supplied. If the exhaust temperature drops below the specified temperature, reduce the amount of sludge input into the dryer or reduce the amount of heat supplied. This is a method to increase the amount of heat.

This is because in hot air drying, the exhaust temperature from the dryer generally increases because the amount of material to be dried is too small relative to the amount of heat supplied to the dryer, and the exhaust temperature does not decrease. This is because the opposite phenomenon is observed.

C.9 Problems to be Solved by the Invention In normal cases, the above method is appropriate, but when muddy substances such as sludge have a high water content, they have high viscosity and their dispersibility in the dryer deteriorates. Therefore, in such cases, drying may not be possible using the above method. In other words, if too much sludge is put into the dryer, drying will be insufficient and the sludge will not be sufficiently dispersed, causing it to stick to the inside wall of the dryer, crushing stirring blades, etc., or form large lumps. As a result, the effective contact area with hot air decreases, heat transfer characteristics deteriorate, and drying efficiency extremely decreases. The hot air blown into the dryer then blows through the dryer without making sufficient contact with the mud.

Exhaust temperature increases. In conventional methods, in order to maintain the exhaust temperature at the set value, the amount of sludge added to the dryer is increased or the amount of heat supplied is decreased. The adhesion increases more and more, and progresses toward a layer that is not dry, and in the worst case, it becomes impossible to dry the layer.

The problem to be solved by the present invention is to determine whether or not the increase in the exhaust gas temperature of the dryer is due to non-drying as described above, and to take appropriate countermeasures to reduce the amount of dirt caused by the rotary dryer. The purpose of the present invention is to provide a method that allows stable and continuous drying of objects.

2. Means to solve the problem In order to solve the above problems, the present invention has the following features.

In a method of drying muddy materials such as sludge using a rotary dryer equipped with crushing and stirring blades, the temperature of the exhaust gas from the dryer is detected, and this detected value is combined with the power required to rotate the drum of the dryer or crushing. The power or torque required to rotate the stirring blades is compared, and the amount of slurry to be thrown into the dryer or the amount of heat to be supplied to the dryer is adjusted by 11+ based on the relationship between this detected value and the two detected values. be.

1. Effect As mentioned above, 1. If drying is insufficient due to overloading, for example, muddy materials put into the dryer will adhere to the inner wall of the dryer or crushing stirring blades, or form large lumps. .

Therefore, in such a state, the rotational power of the drum of the dryer increases, or the rotational power or torque of the crushing agitation blade also increases, and a power or torque fluctuation peculiar to this state occurs, so this change cannot be detected. Based on the relationship between this detected value and the detected value of exhaust gas temperature, the amount of sludge introduced into the dryer or the amount of heat supplied is adjusted. In other words, is it based on exhaust gas temperature? ! If the value increases beyond the i value, the rotational power or torque of the drum or crushing agitation blade is detected, and if this detected value also exceeds the standard and shows a characteristic fluctuation, the amount of sludge input to the dryer is adjusted. If the detected value does not exceed the standard value, either increase the amount of slurry fed into the dryer or decrease the amount of heat supplied.

In order to correct instantaneous output fluctuations, the determination of whether the above reference value is exceeded or not is made based on the percentage of time per unit time during which the detected value exceeds the reference value, and also the degree of Accordingly, the amount of slurry input to the dryer and the amount of heat supplied are adjusted by 114 degrees.

Example The present invention will be explained below based on illustrated embodiments.

Reference numeral 1 denotes a rotary dryer body with crushing stirring blades, and a drum 2 is rotated by a motor 3 at 2 to 8 rpm.

The slurry stored in the input hopper 6 is fed in a fixed amount into the dryer by a screw conveyor 7 rotated by a motor 8. The sludge put into the dryer is attached to the inner wall of the drum 2 or lifted to the top by the lid 10, and when it falls under its own weight, it is heated by the motor 5 at 200 to 400 rplN.
The crushed particles are violently beaten and dispersed by the rotating crushing stirring blades 4.

9 is a hot air stove, 17 is a burner, and 18 is an oil amount control valve.

13 is an exhaust blower, 11 is an exhaust gas duct, and a temperature sensor 12 is attached at a proper position. 15 and 16 are meter relays, and 14 is a product discharge port.

The drying method according to the present invention using the above apparatus is as follows.

The slurry that is fed in a fixed amount from the input hopper 6 is fed to the lifter 10. The sludge, which is dispersed by the action of the crushing stirring blades 4 and dried by the hot air blown by the hot blast furnace 9, is usually placed in the front part of the drum (input hopper 6).
The product is discharged from the product discharge port 14 in the form of mud lumps at the sides, small lumps at the center, and dry granules at the rear. The hot air is blown into the drum 2 from the hot blast furnace 9 at a temperature of usually 700 to 800°C, and heat is removed while flowing in parallel with the mud, resulting in a temperature of 120 to 250°C.
The air is exhausted from the exhaust duct 11 at . The temperature of this exhaust gas is measured by a temperature detector 12 installed at a suitable location in the exhaust duct.
At the same time, the power required to rotate the drum 2 or the power or torque required to rotate the crushing stirring blades 4 is detected by meter relays 15 and 16, and this detected value is input into the computer. Although a meter relay is used for this detection in this embodiment, the present invention is not limited to this. The computer controls the motor 8 of the screw conveyor 7 in the input hopper 6 and the hot air stove 9 based on these input values. That is, if both the detected value from the temperature detector 12 and the detected value of the required rotation power of the drum 2 or the detected value of the rotation required power or torque of the crushing stirring blades 4 exceed the reference value, the motor 8 is
The rotation of the hot air stove 9 is controlled to reduce the amount of mud thrown in, or to increase the amount of heat from the hot air stove 9. The amount of heat may be increased by raising the exhaust gas temperature standard and increasing the amount of fuel in the burner 7 to increase the hot air temperature, or by adjusting the exhaust blower 13 to increase the amount of hot air. Furthermore, if only the exhaust gas temperature exceeds the standard value and the required power, etc. is below the standard value, the amount of sludge input is increased or the amount of heat supplied is decreased.

G. Effect As mentioned above, the present invention detects the required rotation power of the drum or the rotation required power or torque of the crushing agitation blade in addition to the exhaust temperature from the dryer, and controls it in conjunction with this detected value. It is possible to determine whether the rise in exhaust gas temperature is due to so-called insufficient drying, and to perform appropriate control, making it possible to perform stable continuous drying even for muddy materials such as sludge.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a drying apparatus for implementing the present invention. FIG. 2 is a sectional view taken along line A-A in FIG. 1 Rotary dryer with crushing stirring blades 2 Drum 3. Motor I 4. Crushing stirring blade 5. Motor... 6. Input hopper 7. Screw conveyor 8 Motor m 9.Hot stove 10, Lifter 11. Exhaust duct 12. Temperature detector 13. Exhaust blower 14. Product outlet 15.16 Meter relay 17, Burna 18, Oil amount control valve

Claims (1)

[Claims] 1. In a method of drying muddy materials such as sludge using a rotary dryer having crushing and stirring blades, the temperature of the exhaust gas from the dryer is detected, and this detected value is combined with the drum of the dryer. It is characterized by detecting the required power required for rotation of the crushing agitation blade or the required power or torque required for rotation of the crushing stirring blade, and adjusting the amount of slurry to be fed into the dryer based on the relationship between this detected value and the two detected values. 2. A method for drying mud by a rotary dryer according to claim 1, wherein the amount of heat supplied to the dryer is adjusted based on the relationship between the two detected values. Method