JP2630850B2 - Automatic temperature control valve device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve device for automatically controlling the temperature of steam on a secondary side to a constant value.

2. Description of the Related Art Conventionally, as the above-mentioned apparatus, for example, there has been one as shown in FIG. In the figure, reference numeral 33 denotes a pressure reducing valve attached to a steam pipe 32, which keeps the pressure of the secondary steam at a set pressure. The pressure reducing valve 33 is configured such that the set pressure can be changed by the drive unit 34.
The control is performed by the PID controller 35. Three
6 is a temperature sensor used for the control.
Is provided on the secondary side pipe.

The pressure reducing valve 33 and the drive unit 34 are configured as shown in FIG. 4, for example. That is, the motor provided at the upper part in the main body 41
Adjustment screw for rotation of 42 through speed reducer 43 and spline shaft 44
When transmitted to 45, the male screw cut at the tip of the adjusting screw 45
Since the screw 46 is screwed into the screw portion 47 for fixing in the main body 41, the adjusting screw 45 is lowered, and the ball 48 is in contact with the tip of the adjusting screw 45, and the pressure adjusting spring is Compress one end of 50. Due to this compression, the diaphragm 52 is moved through a spring receiver 51 provided at the other end of the pressure adjusting spring 50.
To lower the pilot guide 53, and push down the pilot valve 54 against the acting force of the coil spring 55. In this state, when steam is introduced from the inlet 56, a part of the steam passes through the first passage 57 and passes through the pilot valve 54.
Into the chamber above the piston 59 through an open pilot valve 54, a second passage 58. As a result, the piston 59 descends against the acting force of the coil spring 60, and opens the main valve body 61. Most of the primary pressure steam introduced from the inlet 56 is sent out from the outlet 62 to the heat exchanger 32 as secondary pressure steam through the opened main valve body 61. Part of the secondary pressure steam enters the lower chamber of the diaphragm 52 through the third passage 63. The pressure of this secondary pressure steam is adjusted by the pressure adjusting spring 50.
When the pressure is higher than the set pressure set in the above, the diaphragm 52 is pushed up by the action force of the coil spring 55, and the opening of the pilot valve 54 decreases. Accordingly, the steam pressure applied to the piston 59 is reduced, the opening of the main valve body 61 is reduced by the action force of the coil spring 60, the secondary pressure is reduced, and the set pressure is maintained. On the other hand, if the secondary pressure is smaller than the set pressure, the secondary pressure is increased by the operation reverse to the above, and is maintained at the set pressure.
Thus, the pressure reducing valve 33 self-adjusts the secondary pressure to the set pressure.

The pressure of the secondary steam is self-adjusted to a set pressure by a pressure reducing valve 33. Since there is a correlation between the steam pressure and its temperature, the steam pressure is maintained at a certain value by maintaining the steam pressure at a constant value. on the other hand,
The PID controller 35 calculates the PID calculation unit 37 based on the measured value PV that is the temperature of the secondary steam detected by the temperature sensor 36, the preset temperature set value SV of the object to be heated, and the PID constant. Calculate the operation output value MV, control the drive unit 34,
The set pressure of the pressure reducing valve 33 is changed.

Problems to be Solved by the Present Invention The pressure reducing valve 33 adjusts the pressure of steam to a preset set pressure by itself, and changes the set pressure by controlling a driving unit. Therefore, in order to simplify the control, the operation output value MV and the operation amount l of the drive unit are in a proportional relationship as shown in FIG. 5 (a), and the operation amount l of the drive unit and the secondary pressure The pressure P of the steam is proportional to the pressure P as shown in FIG. However, the pressure P of the secondary pressure steam
And the temperature PV are not in a proportional relationship as shown in FIG. Accordingly, the operation output value MV and the temperature PV of the secondary pressure steam are not in a proportional relationship as shown in FIG. 3D, and the gain is small in a high temperature range and large in a low temperature range. Therefore,
With only one PID constant, there was a problem that hunting occurred in the setting of the low temperature range.

Therefore, a technical problem of the present invention is to prevent hunting from occurring at any set temperature.

Means for Solving the Problems The technical means of the present invention taken to solve the above technical problem is a self-regulating valve for self-adjusting the pressure of the secondary steam to a preset pressure, and Setting pressure changing means for changing the set pressure of the self-regulating valve; temperature detecting means for detecting the temperature of the secondary steam; measured value detected by the temperature detecting means and a preset temperature of the secondary steam Set value and
In an automatic temperature control valve device having a PID calculation unit for calculating an operation output value from a PID constant, an operation output correction calculation for correcting the operation output value calculated by the PID calculation unit and calculating an operation output correction value And an operation output correction value calculated by the operation output correction calculation unit and the temperature of the secondary steam are proportional to each other.

Operation The operation of the above technical means is as follows.

The PID calculation unit calculates an operation output value based on the temperature of the secondary steam detected by the temperature detection means, a preset temperature set value, and a PID constant. The operation output value is corrected to an operation output correction value proportional to the temperature of the secondary steam by the operation output correction calculation unit, and is input to the set pressure changing unit. The set pressure changing means is controlled based on this operation output correction value, and the set pressure of the self-regulating valve is changed, that is, the temperature of the secondary steam is controlled. Become. Therefore, hunting does not occur at any set temperature.

Embodiment An embodiment showing a specific example of the above technical means will be described.

In FIG. 1, reference numeral 3 denotes a pressure reducing valve attached to the steam pipe 2 for maintaining the pressure of the secondary steam at a set pressure. The pressure reducing valve 3 is configured such that the set pressure is
It is configured so that it can be changed. The control is performed by the PID controller 5. Reference numeral 6 denotes a temperature sensor used for the control, which is provided on a secondary pipe of the pressure reducing valve 3.

As the pressure reducing valve 3 and the drive unit 4, those described with reference to FIG. 4 as the prior art are used.

The pressure of the secondary steam is self-regulated to a set pressure by the pressure reducing valve 3. Since there is a correlation between the steam pressure and its temperature, the steam pressure is maintained at a certain value by maintaining the steam pressure at a constant value. on the other hand,
The PID controller 5 performs a PID operation based on the measured value PV, which is the temperature of the secondary steam detected by the temperature sensor 6, a preset temperature set value SV of the object to be heated, and a PID constant. The operation output value MV is calculated. This operation output value MV
Is corrected to an operation output correction value MV ′ proportional to the steam temperature by the operation output correction calculation unit 8 and is input to the drive unit 4. That is, the operation output correction value MV 'and the secondary steam temperature PV
Are in a proportional relationship as shown in FIG. The drive unit 4 is controlled based on the operation output correction value MV ', and the pressure reducing valve 3
Is changed, that is, the temperature of the secondary steam is controlled and maintained at the set value.

Effects of the Invention The present invention has the following specific effects.

Since the secondary steam temperature and the operation output correction value are in a proportional relationship, one
PID constants provide stable control without hunting, which makes handling easier.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of one embodiment of the automatic temperature control valve device of the present invention, FIG. 2 is a diagram showing the relationship between the operation output correction value and the temperature of the secondary steam of the embodiment, and FIG. FIG. 4 is a schematic view of an automatic temperature control valve device in a conventional heat exchanger, FIG. 4 is a sectional view of a pressure reducing valve used in this embodiment and a conventional automatic temperature control valve device,
FIG. 5 is a diagram showing the relationship between the operation output value of the conventional automatic temperature control device and the temperature of the secondary steam. 3: Pressure reducing valve (self-regulating valve) 4: Drive unit 6: Temperature sensor (temperature detection means) 7: PID calculation unit 8: Operation output correction calculation unit

Claims (1)

(57) [Claims] 1. A self-regulating valve for self-adjusting the pressure of a secondary steam to a preset pressure, a set pressure changing means for changing a set pressure of the self-regulating valve, and a temperature of the secondary steam. Temperature detecting means for detecting, a measured value detected by the temperature detecting means, and a preset temperature set value of the secondary steam.
In an automatic temperature control valve device having a PID calculation unit for calculating an operation output value from a PID constant, an operation output correction calculation for correcting the operation output value calculated by the PID calculation unit and calculating an operation output correction value And an operation output correction value calculated by the operation output correction calculation unit and a temperature of the secondary steam are proportional to each other.