JP2503463B2 - Pulp processing method in Biscose human silk plant - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a continuous production method of alkali cellulose in a viscose human silk plant, and in particular, it is of high quality even if the material of the raw material pulp changes or the supply amount changes. The present invention relates to a pulp treatment method in a viscose human silk plant capable of stably and continuously producing the above-mentioned alkali cellulose.

[Prior Art] In the undiluted process in the production of viscose rayon, natural fibers such as wood pulp and linter pulp are soaked in caustic soda solution and further crushed to produce alkali cellulose, which is then aged, sulfided and dissolved. To produce viscose. The above-mentioned method for producing alkali cellulose is historically classified into a batch method and a continuous method, but the latter is now widely used in consideration of the rationality of the process. FIG. 2 is an explanatory diagram showing a continuous type slurry system. The raw material pulp P placed on the raw material pulp supply conveyor 1 is quantitatively charged into the slurry tank 3 by the feed mechanism 2. For this quantitative supply, a device equipped with an automatic weighing device controlled by an integral proportional operation is used. A caustic soda supply pipe 9 is connected to the slurry tank 3 to supply a solution, and caustic soda and raw pulp in the tank 3 are agitated and crushed by an agitator 3a to form a slurry.
An inner cylinder is concentrically provided inside the tank 3,
The slurry is stirred by the slurry circulation between the outer cylinder and the inner cylinder,
The slurry concentration in the tank can be made uniform. A circulation pump 10 is used for the forced circulation. Then, the slurry is sent to the surge tank 5 by the slurry pump 4, adjusted to a constant pressure, and then supplied from the surge tank 5 to the press roll 6. The caustic soda solution is squeezed by the press roll 6, becomes slab-like alkali cellulose, is sent to the shredder 8 and is crushed.

[Problems to be Solved by the Invention] When supplying the raw material pulp P to the slurry tank 3, the pulp automatic quantitative supply device is used as described above to adjust the amount of input pulp. However, the material of the raw material pulp has a moisture content (6
~ 12% range) and pulp active ingredient ratio (90 ~ 94% range), etc. Change. As a result, the composition of the alkali cellulose becomes unstable, and the stability of sulfidation / dissolution in the next step is adversely affected, and the properties of viscose become nonuniform.

Therefore, the present inventors have conducted various studies for the purpose of establishing a method capable of stably and continuously producing high-quality alkaline cellulose, and have completed the method of the present invention.

[Means for Solving Problems] In the present invention which has achieved the above object, the slurry concentration is measured, the raw material pulp supply amount is controlled so that the slurry concentration matches a set value, and the slurry flow rate is measured. The point is to control the pulp supply amount, the slurry pump rotation speed, and the press roll rotation speed.

[Operation] In the method of the present invention, it is first determined that the slurry concentration at the outlet side of the slurry tank is constant, and a densitometer for measuring the slurry concentration in the slurry tank is provided. Then, as a means for matching the slurry concentration measured by the densitometer with the set value, the supply amount of the raw material pulp was controlled. That is, by controlling the supply amount of the raw material pulp, the concentration in the slurry tank is controlled and controlled so that it is always constant, and high-quality alkaline cellulose is stably produced. And in the present invention, the slurry discharge flow rate by the slurry pump is further measured, the raw material pulp supply amount, the slurry pump rotation speed and the press roll speed are adjusted and controlled, and the production amount of the alkali cellulose is produced in accordance with the set value. is there.

[Examples] FIG. 1 is an explanatory view showing an example of a slurry system used for carrying out the method of the present invention. First in the embodiment
The feature is that the slurry concentration meter 11 is installed on the discharge side of the circulation pump 10.
And the slurry flow meter 12 is provided on the discharge side of the slurry pump 4. Each measuring device is connected to the centralized control device 13, and the detected value is input to the control device 13 as needed. The second feature is that the centralized control device 13 is connected to each drive device of the raw material pulp supply conveyor 1, the slurry pump 4 and the press roller 6 to adjust the conveyor speed, the slurry discharge flow rate and the press roller speed. Are performed by remote control. The broken line arrow in FIG. 1 indicates the input system to the centralized control device 13, and the alternate long and short dash line arrow indicates the output system. As the slurry concentration meter 11, it is recommended to use an in-line concentration meter such as a viscous tube type, stirring rotation type, friction rotation type, shear rotation type and stationary probe type. It is recommended to use an in-line flow meter such as a flow meter. However, the present invention does not limit these used devices.

 Next, the control operation by the centralized control device 13 will be described.

That is, when the detected value of the slurry densitometer 11 becomes lower than the preset value input in advance to the centralized controller 13, the feed pulp supply amount by the feed conveyor 1 and the feed mechanism 2 is increased to set the concentration to the preset value. Adjustment control is performed so as to automatically match with, and conversely, when the slurry concentration becomes higher than the set value, the supply amount of the raw material pulp is decreased.

For example, the rotation speed of the slurry pump 4 and the press roller 6
In the case of quantitative production with constant rotation speed, the slurry concentration is detected every 30 seconds and the belt conveyor speed is feedback-controlled. By doing so, it becomes possible to adjust and control the supply amount of the raw material pulp to the tank in accordance with the material variation of the raw material pulp and the like.

Now, set the target flow rate of alkali cellulose to 130 tons / day and set the slurry flow rate to 1100 l / min.
The above feedback control was performed by setting it to 31.7 g / l.
The press roller drawing ratio at this time was set to 2.6 times.
The fluctuation of the raw material pulp supply at the production site was 2 kg / min, but the fluctuation of the slurry concentration could be controlled at 31.7 ± 1.0 g / l, and high-quality alkaline cellulose was obtained quantitatively.
A comparative example using the conventional method (same production target)
As the raw material pulp was supplied at a constant rate of 35 kg / min, the fluctuation of the slurry concentration was 26.7 to 36.7 g / l, which caused a considerable fluctuation in the quality of the alkali cellulose.

Next, a case where the set production amount of alkali cellulose is changed will be described. That is, a slurry flow rate proportional to the production amount of alkali cellulose is set in advance in the centralized control device 13, and the conveyor speed, the slurry pump rotation speed, and the press roller speed are sequentially controlled through the time constant. For example, in the above example, the production amount of alkali cellulose was set to 130
In order to change from tons / day to 150 tons / day, the slurry flow rate in the central control unit 13 was reset to 1250 l / min. Conveyor speed and slurry pump rotation while maintaining the slurry concentration at 31.7 ± 1.0 g / l The number and press roller speed of 3 conditions were automatically restored to a stable state in only 3 minutes. Therefore, by performing the above-mentioned control, the automatic pulp metering device and automatic metering device in the raw material pulp supply conveyor, which have been conventionally implemented, become unnecessary.

[Advantages of the Invention] By using the method of the present invention, the slurry concentration is stabilized, and high-quality alkali cellulose is continuously obtained in accordance with the set production amount of alkali cellulose. As a result, the sulfurization and dissolution in the next step are stable. Then, it became possible to manufacture viscose with uniform properties.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a slurry system used in the method of the present invention, and FIG. 2 is an explanatory view showing a conventional slurry system. 1 ... Raw material pulp supply conveyor 2 ... Feed mechanism 3 ... Slurry tank 4 ... Slurry pump 5 ... Surge tank 6 ... Press roller, 8 ... Shredder 9 ... Caustic soda supply pipe 10 ... Circulation pump , 11 …… Slurry concentration meter 12 …… Slurry flow meter, 13 …… Centralized control device

Claims (1)

(57) [Claims] 1. A raw material pulp is supplied to a tank for dipping an alkaline solution to form a slurry, and when the slurry is sent to a press roll through a slurry pump and a surge tank, the slurry concentration is measured and the slurry concentration is set to a set value. The pulp in a viscose human silk plant is characterized by controlling the raw material pulp supply amount so as to conform to the above, and controlling the slurry supply amount, the slurry pump rotation speed and the press roll rotation speed by measuring the slurry flow rate. Processing method.