JPH09269834A - Powder fluidized transferring flow rate controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder fluidized transferring flow rate controller realizing stable controlling response and wide-range transferring flow rate control by the opening degree operation of a transferring flow rate adjusting valve. SOLUTION: At the time of respectively controlling the supply quantity of gas to a transferring tank by a fluidized flow rate adjusting valve 8, the pressure of the transferring tank by a transferring tank pressure adjusting valve 11 and a powder flow rate transferring from the transferring tank by a transferring flow rate deciding valve 5, a stable area deciding means 35 decides whether the opening degree of the valve 5 is in a stable control area. On the other hand, a set value arithmetic means 40 calculates the set values of the respective opening degree of the valves 8 and 11 based on the set value of the powder transferring flow rate and the set value of a gas flow rate transferring powder. When the opening degree of the valve 5 goes out of a previously set stable control area at this time, the opening degree is returned by a function which is provided to change the set value of the opening degree of the valve 11 for this. A parameter switching means is provided for change-setting the parameter of the PID arithmetic controlling transferring flow rate adjusting valve to a previously set value when pressure within the transferring tank is increased in this case.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to food, cement,
A powder fluidization transfer flow rate control device for supplying a gas for fluidizing powder to a transfer tank loaded with the powder and controlling the transfer amount of the fluidized powder in a steel or oil plant, etc. Regarding

[0002]

2. Description of the Related Art Conventionally, in a plant for transferring powder from a tank to a production facility, a powder fluidization transfer flow rate control device of this kind has been used. In this powder fluidization transfer flow rate control device, the tank internal pressure is kept constant according to the set value of the transfer flow rate, and the opening of the transfer flow rate control valve provided in the path for transferring the powder is controlled, or However, the opening degree of the transfer flow rate control valve is kept constant and the pressure in the tank is controlled only by one of them. That is, in order to prevent mutual interference between the flow rate control and the pressure control, the flow rate control is performed by one element.

[0003]

Of the two control methods described above, when the opening pressure of the transfer flow rate control valve is controlled with the tank pressure fixed, the control response is good, but the transfer flow rate control is good. There is a problem that the range is narrow. Conversely, when the transfer flow control valve opening is fixed and tank pressure control is performed,
Although the control range of the transfer flow rate is wide, there is a problem that the control response is deteriorated.

In order to solve these problems, when the transfer flow rate is controlled by the two elements of the transfer tank internal pressure and the transfer flow rate control valve opening, the change in the transfer tank internal pressure is before and after the transfer flow rate control valve. There was another problem that a pressure difference was generated between the two, and this pressure difference changed the flow rate.

Incidentally, the flow rate Q of the powder flowing through the transfer flow rate control valve is given by the following equation. Q = C _v · (ΔP / γ) (1) where C _v : Flow rate characteristic value of the transfer flow rate control valve (value changes depending on valve opening) ΔP: Pressure difference before and after the transfer flow rate control valve γ: Powder Is the density of.

Therefore, in order to control the transfer flow rate by the two elements of the transfer tank internal pressure and the transfer flow rate control valve opening, the flow rate change based on the pressure difference before and after the transfer flow rate control valve must be taken into consideration. did not become.

The present invention has been made to solve the above problems, and its purpose is to provide a good response characteristic of the powder flow rate control by operating the opening degree of the transfer flow rate control valve and a wide range control by the pressure control in the tank. It is an object of the present invention to provide a powder fluidized transfer flow rate control device which enables stable control response and a wide range of transfer flow rate control without deteriorating the performance.

[0008]

A powder fluidization transfer flow rate control device according to the present invention controls a gas supply amount to a powder-loaded transfer tank by a fluidization flow rate control valve. When the transfer tank pressure control valve controls the powder flow rate transferred from the transfer tank by the transfer flow rate control valve, it is determined whether or not the opening of the transfer flow rate control valve is within a preset stable control range. On the other hand, the set value that calculates the set value of each opening of the fluidizing flow rate control valve and the transfer tank pressure control valve based on the set value of the powder transfer rate and the set value of the gas transfer rate of the powder. In addition to the computing means, it has a function of changing the set value of the opening of the transfer tank pressure control valve so as to return to the stable control area when the opening of the transfer flow rate control valve deviates from the preset stable control area. I made it The transfer tank internal pressure setting is changed only when the transfer flow rate control valve opening is out of the stable region, that is, when the transfer flow rate is very high and when it is very low. A wide range of transfer flow rate control is possible.

In this case, when the pressure in the transfer tank becomes large, a pressure difference may occur before and after the transfer flow rate control valve, and the control performance may be deteriorated. Therefore, the control system of the transfer flow rate control valve executes the PID calculation. At this time, by providing the parameter switching means for changing and setting the parameter of the PID calculation to a predetermined value according to the internal pressure of the transfer tank, the control performance is reduced due to the pressure difference before and after the transfer flow rate control valve. It is possible to suppress and secure a stable control response.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on preferred embodiments shown in the drawings. FIG. 2 is a control system diagram showing a schematic configuration of an embodiment of the present invention. In the figure, a transfer tank 1 for loading powder has a conical bottom wall, a powder transfer tube 1a is inserted in the center thereof, and an upper end of the transfer tube 1a holds a powder. It is fitted into the opening of 1b. The fluidized gas supply pipe 1c is joined to the conical bottom wall, and the transfer tank 1
A pressure adjusting pipe 1d is provided to allow the internal gas to escape from the upper side wall to the powder transfer pipe.

When the weight detector 2 detects the weight of the transfer tank 1, the weight measuring device 3 weighs the powder based on the output of the weight detector 2. The transfer pipe 1a is provided with a transfer flow rate control valve 5, and a transfer flow rate control device 4 is provided to control the opening degree of the transfer flow rate control valve 5. The transfer flow rate control device 4 calculates the transfer flow rate of the powder from the amount of change in the weighing value of the weighing device 3 per unit time, and opens the transfer flow rate control valve 5 so that this transfer flow rate follows the transfer flow rate set value. Manipulate the degree. Further, the fluidizing gas supply pipe 1c is provided with a fluidizing flow rate detector 6 and a fluidizing flow rate adjusting valve 8, and the fluidizing flow rate control device 7 sets the flow rate detection value by the fluidizing flow rate detector 6 to a set value. The opening degree of the fluidizing flow rate control valve 8 is operated so as to follow it. Further, the transfer tank pressure control valve 11 is provided in the pressure control pipe 1d, and the transfer tank pressure is adjusted so that the detection value of the transfer tank pressure detector 9 for detecting the internal pressure of the transfer tank 1 follows the set value of the internal pressure. The controller 10 operates the opening degree of the transfer tank pressure control valve 11.

The carrier gas for feeding the powder is also supplied to the transfer pipe 1a, and the carrier gas is fluidized in accordance with the total set value of the transfer gas, which is a combination of the carrier gas flow rate and the gas flow rate of the fluidizing gas supply pipe 1c. The flow rate setting value of the gas supply pipe 1c is determined, and the fluidizing gas is fed so that the flow rate detecting value of the fluidization flow rate detector 6 follows the flow rate setting value,
The fluidized powder is transferred from the transfer pipe 1a. Here, the transfer amount of powder is controlled by the transfer flow rate control device 4 and the transfer tank pressure control device 10 by operating the transfer flow rate control valve 5 and the transfer tank pressure control valve 11 according to the transfer flow rate set value.

FIG. 1 is a block diagram showing the configuration of each control system of a transfer flow rate control valve 5, a fluidization flow rate control valve 8 and a transfer tank pressure control valve 11. In the figure, the same elements as those of FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted. This control system operates the transfer flow rate control valve 5, the fluidization flow rate control valve 8 and the transfer tank pressure control valve 11 based on the powder transfer flow rate set value and the transfer gas total set value. Here, the transfer flow rate control device 4 executes a well-known PID calculation for the deviation between the transfer flow rate set value SV and its detected value, and operates the opening degree of the transfer flow rate control valve 5 so that the deviation becomes zero. To do.
At this time, depending on the pressure in the transfer tank, the gain switching device 2
0 is configured to change and set the parameters of the PID calculation. On the other hand, the transfer flow rate control valve 5 has a good range of flow rate control characteristics according to the type of powder, density, etc., and in order to control the flow rate within this range as much as possible, the operation amount MV is determined by the stable region determination device 35. I'm watching. When the upper limit of the range is exceeded, a command to increase the set value of the internal pressure of the transfer tank 1 is output, and conversely, when the lower limit of the range is exceeded, a command to decrease the set value of the internal pressure of the transfer tank 1 is output. Is output.

On the other hand, the transfer flow rate set value is added to the flow rate set value change detector 31 and the set value holder 34. Of these, the flow rate set value change detector 31 stores the transfer flow rate set value, and the deviation between the set value for the previous time and the set value for the current time is a reference value that is determined separately for increasing and decreasing, respectively. Is exceeded, and when it exceeds the reference value, a signal of "H" is output, and this signal is added as one input of the OR circuit 33. Also, the signal indicating that the powder is being transferred is NOT
It is applied as the other input of the OR circuit 33 via the circuit 32. When the output of the OR circuit 33 becomes "H", the set value holder 34 temporarily takes in the transfer flow rate set value and holds it, and adds the held transfer flow rate set value to the set value calculator 40. .

The set value calculator 40 is a set value holder 34.
The set value of the internal pressure of the transfer tank 1 is calculated based on the set value of the transfer flow rate and the set value of the total transfer gas, and the transfer tank pressure control valve 11 adjusts the set value so that the set value matches the detected value. The manipulated variable MV and the manipulated variable MV for the fluidizing flow rate control valve 8 are determined. Further, the set value calculator 40 changes the set value when receiving a command to increase or decrease the set value of the internal pressure of the transfer tank 1 from the stable region determiner 35, and changes the transfer tank pressure according to the changed set value. It is configured to change the operation amount MV of the control valve 11.

The operation of this embodiment configured as described above will be described below. First, when the powder is not being transferred, the output of the OR circuit 33 becomes “H”, and the transfer flow rate set value at this time is self-held in the set value holder 34 and added to the set value calculator 40. The set value calculator 40 calculates the pressure set value and the fluidization flow rate set value SV based on the transfer flow rate set value and the transfer gas total set value, and the fluidization flow rate control device 7 operates the fluidization flow rate control valve 8. Then, the powder in the transfer tank 1 is fluidized, and the transfer tank pressure control device 10 operates the transfer tank pressure control valve 11 to control the internal pressure of the transfer tank 1. When the transfer flow rate control device 4 operates the transfer flow rate adjusting valve 5 in this state, the powder in the transfer tank 1 is transferred to the transfer destination.

During the transfer of the powder, the transfer flow rate set value is changed to the larger side, and the deviation is a coefficient y from the set value before the change.
Change command when it exceeds the value multiplied by (%), or when the transfer flow rate set value is changed to a smaller value and the deviation exceeds the value obtained by multiplying the set value before change by the coefficient z (%) Is output and added to the set value holder 34. As a result, the set value holder 34 self-holds the new transfer flow rate set value and adds it to the set value calculator 40. The set value calculator 40 calculates the pressure set value and the fluidized flow set value SV according to the change of the transfer flow set value. In addition, the transfer flow rate control device 4
Operates the transfer flow rate adjusting valve 5 according to the change of the transfer flow rate set value.

During the powder transfer process, the stable region determination device 35 determines whether or not the flow rate control characteristic deviates from the preferable range. For example, if the manipulated variable MV is 60% or more, the inside of the transfer tank is determined. A change amount or a command for increasing (+) the pressure set value is added to the set value calculator 40, and conversely, the operation amount MV is 40
If it is less than%, a change amount or a command for decreasing (-) the set value of the transfer tank internal pressure is added to the set value calculator 40. At this time, there are the following methods a and b for changing the set value of the transfer tank internal pressure. a. Increase / decrease rate (%) of the manipulated variable with respect to the upper and lower limit values of the stable region
When the value exceeds a preset value, the set value calculator 40 calculates the change amount of the pressure according to the rise and fall of the pressure.
Add to b. The operation amount MV of the stable region determiner 35 is 6
If it is 0% or more, an increase (+) command of the pressure set value is output, and conversely, if the operation amount MV is 40% or less, a decrease (-) command of the pressure set value is output. In response to this, the set value calculator 40 changes the pressure set value by a value determined according to the rise and fall of the pressure when each command continues for the time set in the timer or longer.

By the way, when the set pressure is changed to a large side by changing the set pressure described above, a pressure difference occurs before and after the transfer flow rate control valve 5, and the flow rate control performance is deteriorated. To prevent this, a gain switch 20 is provided.

FIG. 3 is a block diagram showing the detailed structure of the gain switching device 20. Here, the determination calculator 24 determines whether or not the pressure in the transfer tank exceeds a preset threshold value, and while the pressure exceeds the threshold value, the changeover switch 2
1, 2, 23 are switched to set the proportional gain of the manipulated variable calculation to the transfer flow rate deviation from P ₁ to P ₂ (<P ₁ )
Then, the integration time is changed from I ₁ to I ₂ (<I ₁ ) and the differentiation time is changed from D ₁ to D ₂ (<D ₁ ). In this case, to prevent control hunting, as shown in FIG.
Switching operation threshold PSV1 and return threshold PSV2
(<PSV1) has a difference of ΔP.

Thus, according to this embodiment, a stable control response and a wide range of transfer flow rate control are possible. Also,
When the pressure in the transfer tank increases, the transfer flow control valve P
By changing and setting the parameter of the ID calculation, it is possible to suppress the deterioration of the control performance due to the pressure difference before and after the transfer flow rate control valve.

In the above embodiment, when the internal pressure of the transfer tank exceeds a predetermined value, the PID calculation parameter of the third flow rate control system for operating the transfer flow rate control valve is set to a smaller value. However, when the internal pressure of the transfer tank exceeds the predetermined value even by the change setting, the parameter may be sequentially changed and set to a smaller parameter.

Further, in the above embodiment, the case where the upper and lower limits of the stable region of the stable region determination device 35 are set to 60% and 40% has been described. It may be possible to change and set.

Furthermore, in the above-described embodiment, the control for detecting the powder transfer flow rate and following the detected value to the set value is executed. However, instead of the transfer flow rate, the powder transfer speed of the transfer pipe 1a is changed. The same operation as described above can be performed even if the control is performed so that the detected value follows the set value.

[0025]

As is apparent from the above description, according to the present invention, the setting of the transfer tank internal pressure is not changed for the transfer flow rate in which the opening of the transfer flow rate control valve is in the stable region, and the transfer flow rate is not changed. Since the setting of the transfer tank pressure is changed for the transfer flow rate where the opening of the control valve is out of the stable region,
A stable control response and a wide range of transfer flow rate control are possible.

In this case, when the pressure in the transfer tank exceeds a preset threshold value, the parameter for PID calculation of the transfer flow rate control valve is changed and set, so that the control performance due to the pressure difference before and after the transfer flow rate control valve is changed. It is possible to suppress the decrease and ensure a stable control response.

[Brief description of drawings]

FIG. 1 is a block diagram showing a detailed configuration of an embodiment of a powder fluidization transfer flow rate control device according to the present invention.

FIG. 2 is a system diagram showing a schematic configuration of the embodiment shown in FIG.

FIG. 3 is a block diagram showing a detailed configuration of a main part of the embodiment shown in FIG.

FIG. 4 is an operation explanatory diagram of the main part of the embodiment shown in FIG.

[Explanation of symbols]

 1 Transfer Tank 2 Tank Weighing Detector 3 Weighing Measuring Device 4 Transfer Flow Control Device 5 Transfer Flow Control Valve 6 Fluidization Flow Detector 7 Fluidization Flow Control Device 8 Fluidization Flow Control Valve 9 Transfer Tank Pressure Detector 10 Transfer Tank Pressure Control device 11 Transfer tank pressure control valve 20 Gain changer 21, 22, 22 Changeover switch 24 Judgment calculator 31 Flow rate set value change detector 35 Stable area judge 40 Set value calculator

Claims (2)

[Claims] 1. When supplying a gas to a transfer tank loaded with powder and transferring the fluidized powder, a first fluidization flow rate control valve provided in the gas supply path is operated.
Flow control system, a second flow control system for operating a transfer tank pressure control valve provided in a path for releasing gas in the transfer tank, and a transfer flow rate provided in a path for transferring powder from the transfer tank. In a powder fluidization transfer flow rate control device including a third flow rate control system for operating a control valve, a stable region for determining whether or not the opening degree of the transfer flow rate control valve is within a preset stable control region. Determination means, and calculates the set values of the opening degrees of the fluidization flow rate control valve and the transfer tank pressure control valve based on the set value of the powder transfer flow rate and the set value of the gas flow rate for transferring the powder. Along with this, when the opening degree of the transfer flow rate control valve deviates from the preset stable control area by the stable area determination means, the set value of the opening degree of the transfer tank pressure control valve is changed and set so as to return to this stable control area. Setting to Powder fluidization transfer flow control apparatus characterized by comprising: a calculating means. 2. When the third flow rate control system executes a PID calculation to control the opening of the transfer flow rate control valve, each time the internal pressure of the transfer tank exceeds a predetermined value,
The powder fluidization transfer flow rate control device according to claim 1, further comprising parameter switching means for changing and setting a parameter of the PID calculation of the third flow rate control system to a smaller value.