JP2814022B2 - Moisture control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for controlling water content in a drying process of yarn, paper, pulp, various foods and the like.

In the drying process of yarn, paper and pulp, in order to maintain predetermined quality and improve productivity, the yarn and paper are controlled so that the water content of the yarn or paper is within a predetermined range. . Also, in the drying process of foods and the like, control of retained moisture is performed in order to dry the food without losing its flavor. Moisture control has been strictly controlled for its quality in order to further improve quality and productivity.

[0003]

2. Description of the Related Art As a conventional moisture control device, a moisture sensor for detecting moisture in an object to be heated and a valve opening of a pressure regulating valve for adjusting a steam pressure for heating based on a signal from the moisture sensor are known. Adjustment methods were commonly used.

[0004]

The conventional apparatus has a problem that the water content of the object to be heated cannot be controlled with high accuracy.
That is, in order to perform feedback control by detecting only the water content of the object to be heated, an overshoot occurs,
This is because the water content is in a hunting state and cannot be controlled with high accuracy.

Accordingly, it is a technical object of the present invention to control the water content of an object to be heated with high accuracy so as not to be in an overshort or hunting state.

[0006]

The constitution of the moisture control device of the present invention is as follows. A method in which a steam supply pipe is connected to a heat exchanger via a pressure regulating valve, and the heat of the object is controlled by heating the object with the heat exchanger. A moisture sensor for detecting the moisture after and a temperature sensor for detecting the temperature, and a pressure sensor for detecting the steam pressure on the inlet side of the heat exchanger, comprising the moisture, temperature and pressure sensors. And a control unit for controlling the opening degree of the pressure regulating valve based on the signal of (1), and the inside of the heat exchanger is connected to a vacuum pump.

[0007]

[Function] To control the water content of the object to be heated with high accuracy by detecting not only the moisture of the object to be heated but also the temperature and the steam pressure and controlling the pressure regulating valve based on the detection results. Can be. That is, the water content of the object to be heated changes depending on the temperature state of the object to be heated and the steam pressure for heating, that is, the steam temperature. Therefore, the steam pressure on the inlet side of the heat exchanger is reduced.
The steam pressure, that is, the steam temperature is detected in advance by detecting with a force sensor.
Of water to be heated during or after the heating process
By controlling the degree of opening of the pressure regulating valve by detecting the minute and the temperature , the water content does not overshoot or enter a hunting state.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. In this embodiment, an example in which the yarn is dried to control the amount of retained water will be described. The moisture control device according to the present invention includes a steam supply pipe 1 for supplying steam for heating, a pressure regulating valve 2 for controlling a supply pressure of steam, and a heating roll for heating a yarn 3 as an object to be heated.
The heating roll 4 includes a steam trap 5 for discharging condensed drain in the heating roll 4 and a vacuum pump 29 for reducing the pressure in the heating roll 4.

The pressure regulating valve 2 has a built-in steam trap 6 for removing the drain generated in the steam supply pipe 1 to the outside of the system, and an electric actuator 7 for externally setting the regulated pressure value. Having.

The heating roll 4 supplies steam to the inside with a cylindrical rotary drier and dries while rotating the yarn 3 along the outside. A pressure sensor 8 for detecting a steam pressure is provided at the inlet side of the heating roll 4. Further, a temperature sensor 9 for detecting the temperature of the yarn 3 is provided above the yarn 3 and a moisture sensor 10 for detecting the water content of the yarn 3 is provided. As the moisture sensor 10, it is desirable to use an infrared moisture meter whose infrared absorption changes according to the amount of moisture. Each of the sensors 8, 9, 10 and the electric actuator 7 of the pressure regulating valve 2 are connected to a control unit 1 by a signal line.
Connect to 2.

The inside of the heating roll 4 and the steam trap 5 are connected by a pipe 13. Although not shown, the steam trap 5 has a built-in bypass which bypasses the valve port of the trap, and has an electric actuator 14 for opening and closing the bypass. The discharge pipe 15 of the steam trap 5 communicates with a vacuum pump 29 or the atmosphere via a three-way switching valve 16.

The vacuum pump 29 is an ejector-type vacuum pump, and connects the liquid supply tank 30 and the suction port of the spiral pump 31 to connect the discharge port of the spiral pump 31 to the ejector 3.
2 is connected, and the ejector 32 and the liquid supply tank 30 are connected. A suction force is generated by the high-speed fluid passing through the ejector 32, and the drain generated in the heating roll 4 is sucked without stagnation. Further, the suction force generated by the ejector 32 becomes equal to the saturation pressure at the temperature of the fluid passing through the ejector 32, so that the saturation pressure, that is, the suction force, is maintained more precisely.
Cooling water is injected from a cooling water supply pipe 35 via a temperature control valve 33 for controlling the temperature of the liquid within 0. The temperature of the liquid in the liquid supply tank 30 is detected by a temperature sensor 34 and input to the control unit 12, and the temperature control valve 33 is controlled. An excess amount of the mixed fluid of the drain and the cooling water circulating in the vacuum pump 29 is detected by water level sensors 38 and 39, and is discharged from the system through a drain discharge passage 52 through a drain discharge valve 51. The electric actuators of the respective sensors and valves / traps are connected to the control unit 12 so that centralized control can be performed.

When controlling the water content of the yarn 3, 100
If heating at a relatively high temperature of not less than ° C. is required, the three-way switching valve 16 is operated to communicate the discharge pipe 15 with the atmosphere. 10
If the temperature is 0 ° C or higher, the pressure is higher than the atmospheric pressure.
The drain condensed in the heating roll 4 is supplied to a vacuum pump
There is no need for suction at 29, the discharge pipe 15 and the three-way switching valve 1
It is discharged to the atmosphere via 6. Supplied from the pressure regulating valve 2
The high-temperature and high-pressure steam having a pressure higher than the atmospheric pressure heats the yarn 3 to control the amount of water. In this case, not only the moisture of the yarn 3 but also the temperature by the temperature sensor 9 and the steam pressure, that is, the steam temperature by the pressure sensor 8, and the control unit 12 controls the pressure regulating valve 2 in accordance with these detection signals, By supplying an optimal steam amount so that the water content of the yarn 3 becomes a desired value, the yarn 3
Can be controlled with high precision.

Although not shown, in this embodiment, a heating roll is used.
Since a rotary dryer is used as the roll 4, the accuracy can be further improved by detecting the rotation speed of the heating roll 4 and inputting it to the control unit 12.

In the present embodiment, the water content of the yarn 3 can be controlled by relatively low-temperature steam of 100 ° C. or less. This is because some types of yarn can be heated only at 100 ° C. or lower. In this case, the three-way switching valve 16
To communicate the discharge pipe 15 with the vacuum pump 29. The water in the liquid supply tank 30 is circulated in the vacuum pump 29 to generate a negative pressure in the ejector 32. This negative pressure causes heating
The inside of the nozzle 4 is also in a negative pressure state. By supplying low-temperature and low-pressure steam from the pressure regulating valve 2, 100
Then, the yarn 3 is heated to a steam of not more than ℃. Since there is a correlation between the steam pressure and the temperature, the steam temperature can be controlled by controlling the pressure. That is, the ejector 32
By controlling the negative pressure generated in the above, the steam temperature in the heating roll 4 can be controlled. And ejector-3
2 can be controlled by adjusting the temperature of the fluid passing through the ejector 32,
By controlling the temperature of the water in the liquid supply tank 30, the pressure, ie, the temperature, in the heating roll 4 can be adjusted.

[0016]

According to the present invention, by controlling the pressure regulating valve by detecting not only the moisture of the object to be heated but also the temperature and steam pressure, the amount of moisture in the object to be heated can be reduced. It is possible to control the amount of water with high precision without causing a shunt or a hunting state.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of a moisture control device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steam supply pipe 2 Pressure control valve 3 Thread 4 Heating roll 5 Steam trap 8 Pressure sensor 9 Temperature sensor 10 Moisture sensor 12 Control part 16 Three-way switching valve 29 Vacuum pump 30 Feed pump 32 Ejector

──────────────────────────────────────────────────の Continuation of front page (51) Int.Cl. ⁶ identification code FI G05D 22/00 G05D 22/00 Z 23/00 23/00 B (58) Field surveyed (Int.Cl. ⁶ , DB name) G05D 27/00 D21F 5/00 F26B 13/00 G05D 16/20 G05D 22/00 G05D 23/00

Claims (1)

(57) [Claims] An apparatus for controlling a moisture content of an object to be heated by connecting a steam supply pipe to a heat exchanger through a pressure regulating valve and heating the object to be heated by the heat exchanger. A moisture sensor for detecting moisture during or after the heating step, a temperature sensor for detecting temperature, and a pressure sensor for detecting steam pressure at the inlet side of the heat exchanger, A moisture control device comprising: a control unit for controlling a valve opening of a pressure regulating valve based on a signal from a temperature or a pressure sensor; and a heat exchanger connected to a vacuum pump.