JPS58117988A - Method of automatically controlling drying of moistened powdered body - 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 The present invention relates to an automatic drying control method for controlling the degree of drying of wet powder with high precision.

Final step in the manufacturing process of metal powder, such as ferroalloy #
Wet grinding or hot grinding is carried out in
Powder in the fI/I4a′ state (hereinafter referred to as powder)
It depends on each purpose! Must be dried to IL. The drying methods are batch type and continuous type.
In the case of the batch method, the wet and hot powder exhibiting a muddy temperature is placed on a tray, placed in a drying room Km, and then lifted onto an appropriate number of shelves and heated air is blown. , the degree of drying differs from tray to tray, and the moisture content of the dried product varies. For this reason, we installed a KmK machine in the drying room to increase the movement of hot air, made the hot air outlet poorer, and changed the tray position periodically or continuously. This method is being considered, but it is possible to reduce the variation slightly, but it has not yet reached an essential solution, and the tray surface rkJ
Variations in the moisture content between the sides and the bottom are considered unavoidable, and the only way to deal with this is to minimize the amount of moisture in the plating.Therefore, a continuous system was devised, for example, 1 MflR on a screw conveyor.
In addition to running the powder in a thin layer, the outside of the conveyor top (2) is equipped with a K steam sword jacket and inside the jacket! cI
A method has become widely used in which the slurry on the screw is heated and dried by passing high-temperature steam (if necessary, through the screw conveyor) to heat and dry the sludge on the screw.

Many of Tako's screw ftM mixture aII are arranged in series to improve dry fineness by arranging two or more of them.

In such a continuous drying method, the operating conditions of the dryer itself are constant, and the amount of heat supplied for drying can be controlled within a certain range, so the moisture content after drying can be kept as fine as possible. It should have been possible.

However, during actual operation, the amount of slurry charged varies, and the moisture content of the slurry itself varies, so the constant operating conditions of the dryer may actually be inconvenient. Technology is also being considered to control the progress of drying by controlling operating conditions. However, the conventional control was only a S degree that adjusted the operating conditions according to only the changes in the total amount of charged slurry and the moisture content, so the control part #J was bad and the moisture content of the dried product There is still considerable variation. As a result, when the moisture content is high, it tends to cause caking during powder storage, and it also has the disadvantage of causing condensation on the sieve when working in the sieve pit.On the other hand, when it is overdried, it wastes thermal energy. However, depending on the type of powder, there is a certain level of risk that it may cause spontaneous combustion.

The present invention has been made in view of these circumstances, and it is an object of the present invention to provide an automatic drying control method that can control the degree of drying of knitted powder to a high #s degree according to each application. The purpose is to However, what is the drying automatic control method according to the book @ Ming?

In the continuous drying method VC, in which wet powder is introduced into a drying device and dried while being continuously transferred, the temperature or moisture content is automatically measured at any position where drying has progressed beyond a certain level, and The gist of this method is to adjust the drying capacity of the drying device by comparing it with a predetermined degree of drying progress, or to adjust the transfer speed of the wet powder in the device a. There are no particular restrictions on the moisture content of the one-direction tU powder, the structure of the dryer, the IT measurement means for temperature and moisture, the control operation means, etc., and based on the examples described below. , it is within the technical scope of the present invention to make changes to the cape enclosure that do not go against the gist of the above and below.

FIG. 1 is a perspective view of the drying process for automatic control according to the present invention. For example, ferroalloy is crushed in a wet crusher 1111, and the resulting muddy wet powder is sent to a dehydrator along the arrow AK. After being subjected to preliminary dehydration by means of centrifugal dehydration or filter press processing, it enters the first dryer 4 along the arrow B and then the second dryer 5 along the arrow CK.
to go into. The powder dried to a desired moisture content by these dryers 4.5 is discharged in the direction of the arrow and shipped as a classified product. 4 a, Fl a is '
:r Indicates the drive part of the dryer, and in the case of a screw type dryer, the screw drive motor is built in.

In carrying out the present invention, the temperature or moisture content of the object to be treated is measured at the outlet M of the first dryer 4 and the center N of the second dryer 5, and at one point d (Idm, n). A measurement signal is input to the control 8 along the line.The control section performs a comparison calculation between the set value and the input signal, and the difference between the set value and the input signal is
(A corresponding operating signal is output along the line 1i4pK, and the drive in the drive parts 4a and 5a is adjusted, and the amount of steam supplied to each dryer is adjusted. In the example shown in the figure, the output line p from the control @W6B is output. Although one line is shown, it is also possible to configure the output lines to each drive unit separately, or to provide 42 or more output twins to transmit two or more operating commands to each dryer. It is also possible to set the measurement points to one each at the outlet of the first dryer and the middle of the second dryer, but it is also possible to measure at two or more points for each dryer. Alternatively, when two or more reverse VC dryers are installed in series, a measurement point is provided at only one point in the entire dryer line, and based on the measurement results, the drive of the dryer or the dryers before and after it is controlled. It is also possible to make adjustments, and all of these cases are included in the present invention.It should be noted that the measurement points for these dryers are points that can be used to clearly determine the progress of drying. Therefore, it is meaningless to measure at the entrance where drying has not yet progressed sufficiently, and it is desirable to set up measurement points at or after the middle section where drying has progressed to a certain extent, especially at one point. In the case of the measurement method, a position as close to the 80 part side as possible is desirable.

Figure 2 is an example of control (2) in the two-point measurement method shown in Figure 1, where the Saiyan curve shows the set target drying curve, and the MA[
When the target moisture content at point is Mt and the target moisture content at point N is Nt, the actual measured moisture content is M't,
If it is N't, you can see that it is insufficiently dry.
t and N't, it can be seen that it is over-dried. Therefore, the target moisture content is positive or negative! Once I is clear, a command to accelerate drying or delay drying can be issued depending on each. The quotient t I W between the above arms
Comparison of t * M”t, and Nt, W t, N
”, t, but (Mt-Nz) and (M't, also t;f M#t-?J' or N"t)
It goes without saying that control may be performed by comparing the values. In addition, when controlling based on temperature measurement, a separate relationship between temperature and moisture content O is provided to determine the temperature.

For example, control is performed by converting the value detected by a humidity sensor into moisture content and displaying it.

Means for measuring moisture content at point M and Nt There are no special restrictions on the medium strength measuring means, but for the former, it is recommended to use a two-color infrared moisture meter, and for the latter, a thermocouple or electrical resistance hygrometer. It was extremely convenient and advantageous in improving the #1 degree of drying. Further, as means for adjusting the degree of dryness, it is preferable to adjust the passage speed in the dryer, heating chamber, ventilation temperature, etc. alone or in a suitable combination. For example, to adjust the passing speed, the rotation of the screw conveyor is set to a multi-speed variable speed system, and if the drying is insufficient, the screw is changed to a low rotation speed, and if the drying is overdrying, the screw is rotated at a high speed (14Iicf History). Regarding the case where adjustment is performed using heating steam pressure, high pressure supply may be used when vLf# is insufficient, and switching to low pressure supply may be performed when overdrying occurs.

Since the control of the present invention is carried out as described above, it is possible to control the dryness of the wet powder with extremely high precision.
For example, when the target moisture content is set at 0.01 to 1.0, it is possible to reach exactly 8.

[Brief explanation of the drawing]

Fig. 1 shows the control device according to the present invention @i4, and Fig. 2 shows #i setting drying curve and sJ! It is a graph showing a comparison of measuring and drying bending machines. 8...Control unit 4...@l dryer 5...Second dryer

Claims (1)

[Claims] ] Otori) Automatic measurement of the temperature or moisture content at an arbitrary position where the drying progresses to a certain extent on a line when the wet powder is introduced into the drying device and dried while being continuously transferred. Drying of wet temperature powder, characterized in that the drying capacity of the drying device is adjusted by comparing with a predetermined degree of drying progress, or the transfer speed of the wet temperature powder in the pupil is adjusted. Automatic control method.