JPH0819165B2 - Discharge end control device for batch type polymerization can - Google Patents

Description

Description: [Industrial field of use] The present invention relates to a discharge completion control device for a batch type polymerization can.

[Prior Art] In the manufacturing process of synthetic fibers, for example, polyester-based synthetic fibers, it is common practice to carry out melt polymerization in a batch-type polymerization vessel to chip the obtained polymer into chips. The inside of the polymerization vessel is pressurized with an inert gas, discharged from the bottom of the polymerization vessel in the form of a sheet or a strand, and cut into chips by an appropriate cutter such as a dicing machine or a strand cutter.

In such a discharging operation, the completion of the discharging is judged by the operator visually observing sheet tears and strand breaks that occur when the inert gas leaks from the discharging port when the amount of the polymer in the polymerization vessel is low. ing.

However, such a discharge end determination has a drawback that labor is required because it requires labor and that if the determination is slightly delayed, the inert gas is ejected violently to scatter the high temperature polymer. is there.

Conventionally, as a method for determining the end of this discharge
The methods disclosed in Japanese Patent No. 7663 and Japanese Utility Model Publication No. 56-6446 are known.

In the former case, a rod is provided so as to be in sliding contact with the sheet when the sheet is ejected, and a hole in the sheet is detected. However, although this device can be applied in the case of discharging in the form of a sheet, it cannot be applied in the case of discharging in the form of a strand because it is difficult to bring the rod into sliding contact with all of the many strands. .

The latter is provided with a temperature detection unit for detecting the temperature inside the polymerization can during discharge, near the bottom of the can, and detects the temperature change when the polymer liquid level passes through the temperature detection unit, and the discharge speed and the It is a method to determine the end time of discharge from the remaining amount of polymer,
In this method, the reliability of judgment is low. That is, by the stop position after the reaction of the stirring blade provided in the polymerization vessel,
The flow of the polymer in the vicinity of the temperature detecting portion immediately before the end of discharge is different, and the temperature drop pattern is different accordingly, so that it is difficult to detect the temperature change accurately in each batch. As a result, the remaining amount of the polymer based on the temperature change detection is not always detected as a constant amount, and there is a possibility that the discharge end time determined based on the remaining amount of the polymer may be incorrect. In addition, a preset discharge speed is used to calculate the discharge end time point.
Since the discharge pressure and the thickness of the discharged substance may change when the thickness changes during cutting, there is also a disadvantage that the calculated value is distorted due to the change.

[Problems to be Solved by the Invention] An object of the present invention is to accurately determine the end of discharge in a batch-type polymerization container, minimize the amount of the polymer left in the polymerization container, and leave the polymer residue in each batch. The present invention provides an effective discharge completion control device which is applicable to both a sheet shape and a strand shape.

[Means for Solving Problems] The above-mentioned object of the present invention is a batch-type polymerization container in which an inert gas is press-fitted into the polymerization container to discharge the polymer from a discharge port, which is rotated in the polymerization container. A position detector that detects the rotational position of the stirring blade to stop the stirring blade at a fixed position for each batch after the completion of the polymerization reaction, a temperature detection unit that detects the temperature inside the can near the bottom of the polymerization can, and The moment when the polymer liquid level passes through the temperature detection unit is detected by expanding a minute signal change from the temperature detection unit based on the temperature difference between the coalescence temperature and the gas phase temperature in the can, and based on the detection. Discharge in a batch type polymerization can, characterized by being provided with a control device for determining the discharge end time from the relationship between the remaining amount of polymer in the polymerization can and the discharge speed based on the actual detection value, and for issuing a discharge end signal. Depending on the termination controller Can be achieved.

The position detector is configured by detecting the rotational position of the stirring blade using a photoelectric switch, for example. To stop the stirring blade, in addition to the method of turning off the power source of the stirring blade by the signal from the position detector, after turning off the power source of the stirring blade and completely stopping it, it is driven by a driving source with a small capacity, You may make it stop at a fixed position using a position detector.

Further, the detection of the polymer liquid level based on the minute signal change is easily achieved, for example, by providing a differentiator in the control device and detecting the expanded minute signal change by the differentiator. .

Further, the discharge speed of the polymer based on the actual detection value is calculated by, for example, detecting the weight of the chip cut by the cutter moment by moment.

[Operation] In such an apparatus, the position detector detects a fixed position of the stirring blade and the stirring blade is stopped based on the detection, so that the stirring blade is surely stopped accurately at a fixed position for each batch. Since the stop position of the stirring blade is constant, the flow of the polymer in the polymerization vessel at the time of discharge is also reproduced in a constant state for each batch, and the temperature when the polymer liquid level passes through the temperature detection unit The temperature drop pattern around the detector is also constant for each batch. Therefore, if the temperature detection unit is once adapted for temperature detection, the optimum detection state that is constant for each batch is reproduced, the detection variations are eliminated, and the polymer liquid level is accurately detected. Since the amount of the polymer accommodated below the temperature detecting portion is simply determined by the shape (volume) of the polymerization can, the constant amount of the remaining polymer can be detected with good accuracy in each batch by the above-mentioned highly accurate detection. In addition to the constant remaining amount of the polymer, the discharge end time is determined based on the relationship with the actual discharge speed at that time, so that the accurate discharge end time in which the dispersion of the discharge speed is corrected is determined. As a result of the discharge being ended by an accurate discharge end signal from the control device,
Inert gas is not spouted from the polymerization vessel, and the amount of polymer left in the polymerization vessel is kept to a certain minimum amount, and this series of control is automatically performed.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

The figure is an instrumentation system diagram of an apparatus according to an embodiment of the present invention.
After the completion of the polymerization reaction, the polymer G in the polymerization container 2 is discharged in sheet form 10 from the discharge port 9 by opening the discharge valve 8.
It is sent to the cutter 11 and made into chips. 4 is a temperature detecting part inserted near the bottom of the polymerization can 2, 5 is a resistance / temperature converter, 6 is an enlarged signal from the temperature detecting part 4, and the polymer liquid level L indicates the position of the temperature detecting part 4. A buzzer 7 is used to detect the moment of passage using a differentiator and to calculate the discharge speed from the signal of the tip weight unit 13, and 7 to inform the discharge.
Further, 1a is a photoelectric switch used to keep the stop position of the stirring blade constant, 1b is a reflection tape thereof, and 12 is a hopper into which chips are put in to measure the discharged chips.

Immediately before the completion of the polymer reaction, the rotation speed of the stirring blade 3 is about 6 to 12 rotations / minute, and after the OFF signal of the stirring blade 3, the stirring blade 3 stops at several rotations (constant for each batch). Therefore, if the stirring blade 3 is turned off at the time when the signal of the photoelectric switch is obtained after the constant torque is reached immediately before the completion of the polymerization reaction, the stirring blade can be stopped at a constant position without fail. As a result, the flow of the remaining amount of polymer in the vicinity of the temperature detection unit 4 in each batch becomes constant, and the temperature detection unit 4 for detecting the temperature difference between the polymer temperature and the gas phase temperature in the can has the same temperature drop in each batch. The pattern will be obtained. Therefore, the detection accuracy is improved. Here, the temperature change before and after the polymer liquid level L passes through the temperature detection part 4 is as small as about 1 ° C./min, and the time constant is large. In the present invention, the minute change is magnified by the control device 6 and differentiated so that the liquid level passage can be detected quickly.

It is necessary to perform the actual discharge to the extent that the inert gas does not blow out from the discharge port 9 as much as possible. Therefore, after the temperature detection unit 4 detects the polymer liquid level L, a timer or the like is used.
Further, it is designed to be discharged. This discharge rate varies from about 35 to 55 kg / min depending on the batch. For this reason, if the timer is set to a constant value, the discharge amount will vary from batch to batch, and in the worst case, an inert gas may blow out. For this purpose, the discharge weight signal from the tip weight device 13 is input to the control device 6 to calculate the discharge speed, and the timer value is corrected. When the time is up, the discharge valve 8 is interlocked and automatically closed. Therefore, it leads to labor saving of the discharge end work. Further, in addition to the above-mentioned highly accurate detection of the amount of remaining polymer, the actual discharge speed is calculated, so the time when the discharge should be finished is accurately determined, and at the optimum time, that is, only the minimum necessary polymer remains. When not present, the discharge valve 8 is closed.

In order to see the effect of stabilizing the stop position of the stirring blade,
The results of measuring the variation in the chip amount are shown below.

(1) When the stirring blade stop position is constant: N number = 25, average tip weight = 2740 kg, σ = 15.1 kg (2) When the stirring blade stop position is free: N number = 15, average tip weight = 2754 kg, σ = 32.5kg where N is the number of tests and σ is the degree of variation. As described above, by fixing the stop position of the stirring blade, the variation in the obtained chip weight was reduced to less than half, and the variation in the remaining amount of the polymer in the polymerization vessel was also greatly reduced.

[Effects of the Invention] As described above, according to the present invention, the stirring blade is stopped at a fixed position to make the temperature drop pattern in the temperature detection unit constant, and the polymer liquid level is detected with good accuracy in each batch. Since the discharge end time can be determined by using the discharge speed of No. 3, the discharge end can be accurately performed according to the target for each batch, and labor can be saved by linking with the discharge valve. Further, since the final residual amount of the polymer in the discharge part can be minimized to prevent the ejection of the inert gas, a great effect can be obtained in terms of safety and productivity.

INDUSTRIAL APPLICABILITY The apparatus of the present invention can be effectively used for controlling the discharge end of a batch type polymerization can of polyester, polyamide and the like.

[Brief description of drawings]

FIG. 1 is an instrumentation system diagram of a polymerization device using a discharge termination control device according to an embodiment of the present invention. 1a …… Photoelectric switch 1b …… Reflective tape 2 …… Polymerization can 3 …… Stirring vane 4 …… Temperature detector 6 …… Control device 8 …… Discharge valve 9 …… Discharge port 11 …… Cutter 12 …… Hopper 13 …… Tip weight scale G …… Polymer L …… Polymer liquid level

Claims (1)

[Claims] 1. In a batch-type polymerization container in which an inert gas is injected under pressure into the polymerization container to discharge the polymer from a discharge port, a stirring blade rotated in the polymerization container is stopped at a fixed position for each batch after the completion of the polymerization reaction. Therefore, a position detector for detecting the rotational position of the stirring blade, a temperature detection unit for detecting the temperature inside the can provided near the bottom of the polymerization can, and the above based on the temperature difference between the polymer temperature and the gas phase temperature inside the can. The moment when the polymer liquid level passes through the temperature detecting unit is detected by expanding a minute signal change from the temperature detecting unit, and based on the detection amount of the polymer remaining in the polymerization vessel and the actual detection value. A discharge end control device for a batch-type polymerization can, comprising: a control device that determines a discharge end time point from a relationship with a discharge speed and issues a discharge end signal.