JPS63273014A - Measurement control of liquid and powder and measurement control instrument - Google Patents

Abstract

PURPOSE:To realize a highly accurate and short time measurement and secure a wide measuring range by calculating an output to an operating unit for enabling a flow velocity to change by any of fuzzy control, learning control and optimum control methods from the observation of a deviation between a planned setting value and an actual measured value and the quantity of temporal change in the deviation. CONSTITUTION:A planned setting value is set to a measurement controller 3. A DRV (drain valve) 9 and a CDV (cleaning drain valve) 10 are changed over to a measuring system line to start a measurement. Thus, an SRV (stop valve) 8 is opened by the controller 3, the flow of a material is caused by adjusting the opening of an FCV (opening control valve) 7 and the raw material in a tank 1 is fed to a tank 2. A load cell 4 detects the weight of the raw material and feeds back the value of the weight to the controller 3. The controller 3 calculates a deviation between the actual weight value and a set value from an actual weight value thus obtained and the quantity of temporal change in the deviation. Further, the controller 3 issues a new opening command thus obtained to the FCV 7 by any of fuzzy control, learning control and optimum control systems and changes a flow velocity.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a liquid and powder metering control method and device;
More specifically, this method of liquid and powder material improves measurement accuracy, expands the measurement range, and stabilizes measurement time by sequentially changing the flow velocity of the object to be measured based on the observed tFC obtained during measurement. The present invention relates to a metering control method and device.

(Prior Art) In liquid measurement, there are various detection methods, such as Mftx type (load cell, etc.), pressure type (pressure transmitter, etc.), and volumetric type (oval flowmeter, etc.).

In powder measurement, there is mainly a weight method using a load cell or the like.

However, in either method, the metering control is based on the premise that the flow rate is constant, and there is no closed-loop metering control method that continuously varies the flow rate.

Conventionally, the following techniques have been implemented as a method for improving the accuracy of the sound.

■ Divide the flow rate into two stages and set the flow rate near the measurement setting value.
Technology for measuring by switching to a slower flow rate (for example, Japanese Patent Application Laid-Open No. 5
6-148019).

Specific example 1) Two types of devices with different flow velocities are installed and switched when the deviation between the measurement setting value and the actual measurement value reaches a certain condition value.

2) Install a single device that has the function of switching the flow rate to two fixed conditions, and switch the flow rate when the deviation reaches a certain condition value, as in 1).

3) Regarding the contents of 1) and 2), a learning function is added as a software function to correct the condition value for commanding the switching from the previous measurement result value.

■ As a measurement stop condition, there is an inflow *<also referred to as head amount.Technology for predicting this amount and stopping the flow in advance for measurement (for example, Japanese Patent Application Laid-Open No. 57-29114).

Specific example 1) When a certain condition of deviation between the measurement setting value and the actual measurement value is reached, the measurement is stopped.

2) Same as ①-5), but the condition value for commanding the stop of measurement is corrected by calculating from the previous measurement result value.

(Disadvantages of conventional technology) However, in conventional metering control, although the flow rate is constant or the flow rate is divided into two stages and switched as described above, the metering is fixed within a certain range, so there are the following disadvantages. .

■Measuring accuracy: Accuracy may not be guaranteed due to flow velocity and shift due to disturbances or changes in the physical properties of the object to be measured.

For example, in the case of gravity transfer, the remaining amount of the object to be measured in the upstream container (hereinafter, this remaining amount is referred to as the head difference). ,
If the change in head difference is large, the flow velocity will go outside a certain range of conditions, and accuracy will deteriorate. Also, about this.

This results in a restriction during the head change of the upstream vessel, and in order to keep the head difference within the required range,
It is necessary to stop measuring or to continue to replenish the upstream container with raw materials as appropriate, which leads to secondary loss of raw materials.

■Measuring range: Since the flow rate is limited, the ratio of the minimum and maximum possible noise values is usually about 1:5.

Even with a two-stage flow rate setting type, the maximum is about 1:10.

The reason why the weighing range is so narrow is that even when the weighing is stopped,
There is a flow-in area due to the response delay of the system, and this area is determined by the flow velocity, so if the measurement setting value is small, this will exceed the guaranteed accuracy range, and as a result, the measurement range will be limited.

In a manufacturing plant that handles a wide variety of products, even for the same raw material, the measuring range may be approximately 1:100 at most, so it is necessary to select a metering device within the metering setting value range.

■Measuring time: The measuring time depends on the IT setting value.

If the metric setting value is small, the total time will be short; if it is large, the total time will be long.

If the metering set value is small, there will be variations in the operating time of the system, and it will not be possible to guarantee the level of metering, but it will also lead to a narrowing of the metering range.

Furthermore, from the perspective of the entire system that mixes multiple types of objects to be weighed to produce a new product, the manufacturing capacity is affected by the weighing time, and the manufacturing system is a mobile manufacturing system that does not require special Pc,) Z-in-0. In this case, the transport capacity will be limited.

The above-mentioned drawbacks result in economical drawbacks in process construction. Tsumaishi Jumai has installed a large number of measuring devices according to the measurement setting value, and also installed a measuring device for each optimal weighing time and each raw material due to manufacturing capacity limitations. Ta.

(Object of the invention) The object of the present invention was achieved based on the above circumstances, and
Fluctuations in flow velocity due to disturbances, liquid physical properties (viscosity, etc.) and powder physical properties (
Measurement of liquids and powders that achieves high-accuracy measurement that is not affected by fluctuations in flowability, etc.), secures a wide measurement range, and realizes short measurement times that are not affected by the size of measurement settings. The objective is to provide a control method.

Another object of the present invention is to provide a control device for implementing the above-described control method.

Furthermore, by configuring a system using this precision weighing control device, we can reduce the number of equipment, increase equipment capacity, and reduce raw material loss.

■ Initial cost reduction ■ Running cost reduction ■ Maintenance cost reduction, etc. The objective is to achieve a process with high economic efficiency.

(Summary of the invention) By changing the constant flow rate condition, which is the basic factor that causes the drawbacks of conventional metering devices, to a metering control method that changes the flow rate using closed loop control, ■ it is not affected by flow rate fluctuations due to disturbances. Highly accurate weighing ■ Wide measuring range ■ Achieves short-time weighing that is not affected by the size of the weighing setting value. Therefore, the metering control method is composed of the following components.

1) Control method: When considering the modeling of the metrology system, it is nonlinear. Therefore, this cannot be easily realized using conventional control methods such as simple PID control.

Therefore, using fuzzy control, learning control, or optimal control methods, the deviation between the measurement setting value and the actual measurement value,
Calculate the optimal manipulated variable from the observed amount of deviation time change,
Metering control is performed by sequentially changing the flow rate to the optimum state either continuously or discretely.

2) This is a device that observes moment-to-moment changes in the detector value.

Any device that can observe measured values such as a load cell, differential pressure transmitter, etc. may be used. However, the metering range depends on the static accuracy of this detector.

3) Manipulator: A device for changing the flow rate.

The device consists of mechanical parts and electrical equipment for driving. (It may also be driven by air, oil, or other fluid.) In the case of liquids, the usual method is to change the flow rate by varying the degree of opening, but in this case, the pulp used in this case depends on the shape of the control valve. For example, there are known valves with various external shapes, or a new valve having a notched groove extending in the valve driving direction on the valve circumferential surface so that the flow rate can be varied by the shape of the groove. Good too. Note that the known knob valve may be any valve having flow characteristics other than quick-open characteristics. The pump may be one in which the flow rate varies continuously from 1 cO. Although there are various other methods, any device that can change the flow velocity from zero may be used.

In the case of powder, a common method is to use a screw feeder that changes the amount of powder transferred by changing the rotational speed of the motor.

(Embodiment) Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings.

FIG. 1 illustrates a liquid measuring device applied to one embodiment of the present invention, in which material filled in an upstream tank 1 is transferred to a measuring tank, that is, a downstream tank 2. A case will be described in which one monkey is weighed using the a-docel 4 attached to the downstream tank 2.

The piping system between the tank 1 and the tank 2 has an FC;
An RV (drain valve) 9, a 5RVC stop valve) 8, and a cvn (cleaning waste liquid valve) 10 are arranged in this order. A load cell 4 serving as a detector for determining the weight of the object to be weighed is disposed in the downstream tank 2, and the load cell 4 is connected to a weighing control device 6 through a load cell amplifier 5. Further, the metering control device 6 is connected to a servo driver 6 and an FCV 7 that constitute an operating device.

When measuring an object to be measured using the liquid measuring device configured as described above, a measurement setting value is set in the meter-control device 6, and the DRV
(Drain nozzle) 9 and CDv (Cleaning waste liquid nozzle) 10 are switched to the metering system line and the process is started. When the measurement start is instructed by the meter tht control device 6, the SR
A position command is transmitted from the metering control device 6 to the servo driver 6, and the servo motor Set the valve boat of FCV7 to the indicated position by driving, adjust the opening degree, and cause the flow of raw materials. As a result, the raw material in tank 1 is transferred to tank 2.
begins to be transferred to

The load cell of the tank 2 detects the weight of the transferred raw material and feeds back the value to the weighing control device 3 through the load cell amplifier 5.

The weighing control device 3 calculates the deviation from the set value and the time change of the deviation from this actual weight value, and calculates the appropriate weight in the next control cycle based on any of the control methods of fuzzy control, optimal control, and learning control. Calculate the valve opening command (position command) that will give the flow velocity. Then, in the next control cycle, FC
Instruct V7 with a new opening command (position command) and change the flow velocity.

As described above, the opening degree of b' c v 7 is controlled in a closed loop (Fig. 2) at a predetermined control cycle based on the observed amount of the load cell 4, and as a result, the opening degree of b' c v 7 is controlled continuously or at predetermined time intervals. The flow rate is controlled discretely.

When the observed amount approximates the metric setting value and the metric deviation becomes small, the FCV 7 reduces its opening and becomes a minute flow velocity. Therefore, the inflow lid becomes smaller after metering is stopped, and the flow rate improves regardless of flow velocity fluctuations caused by disturbances such as head differences.

In addition, in the measurement control device 6 of the present invention, the operation of the FCV 7 changes depending on the measurement setting value and process system within the measurement range, and the measurement can be performed with the same measurement device regardless of the size of the measurement setting value, expanding the measurement range. do.

However, it is within the static accuracy of the detector. Historically, the measuring time (l
This is also the result of an experiment conducted in a short period of time, in which the operating JR turn of the FCV7 changes and regardless of the magnitude of the metering setting value.

The resulting weighing device can weigh up to 10 kg, and the accuracy of the load cell is 1/5000. The position is controlled by an FCV (opening adjustment valve) Vi servo motor, and a position command is output from the metering control device.

Figure 6 shows that when 1.2 o'clock liquid remains in the upstream tank, the same measuring device weighs 1000.9°500g.
The graph shows the measurement characteristics when each is measured, and the measurement deviation and FCV valve opening at that time are shown on the vertical axis, and the measurement time is shown on the horizontal axis.

As is clear from the figure, measurement can be performed with the same measuring device regardless of the size of the measurement setting value, and therefore the measurement range is expanded. Although the valve opening degree changes naturally, the measurement time shows the relationship between the measurement accuracy and the measurement setting value.

Note that the measurement accuracy was determined by measuring the outflowing liquid using a different certified weighing scale.

In the case of 10 kg, the weighing time was about 160 seconds, and the weighing accuracy was ±0.5I. Therefore, weighing range 1:1
00, an accuracy of ±1.0 was obtained.

Furthermore, although the flow rate changes depending on the remaining amount in the tank, it was confirmed that the measurement accuracy and measurement time do not change even if measurement is started from a different remaining amount level, and are not affected by flow rate fluctuations.

In addition, the above-mentioned embodiment shows an addition type measurement (method of storing and measuring a liquid in a measuring tank).
DRV9 and CDVlo in the figure are valves for incidental cleaning and waste liquid. In addition to the additive method described above, the present invention may also be a subtractive method in which a detector is placed in the storage tank (upstream tank) to measure the amount of outflow, as shown by the broken line in the figure. It is inferred that As a detector, in addition to overlay weighing using Hola A-, for liquid measurement, for example, a liquid level gauge is used to measure the liquid level, and this is fed back to the metering controller via a differential pressure transmitter amplifier. It may also be a pressure type using a pressure type, a tanizumi 2 using an O/Guru flow, etc.

Further, for liquid metering, the operating device is generally a combination of the opening adjustment valve and the motor described in the above embodiment, but the present invention is not necessarily limited to such a configuration. -For powder measurement, screw feeders, dump saws, gates, etc. are used instead of opening adjustment valves.

(Effects of the Invention J) In addition to the above description, the present invention provides the following effects.

■ Achieving high-accuracy measurement that is not affected by flow velocity fluctuations caused by external disturbances ■ Achieving wide-range measurement with a wide range of measurement setting values ■ Achieving short-time measurement that is independent of the magnitude of measurement setting values Adoption of the control device of the present invention In the system, it is possible to ■ reduce the number of weighing devices ■ reduce the loss of raw materials, etc., so the following economic effects can be obtained.

■ Reducing initial costs by reducing the number of devices ■ Reducing maintenance man-hours by reducing the pressure of the number of devices ■ Reducing failures by improving reliability by reducing the number of devices ■ Flow rate control reduces the influence of residual t (head difference) of raw materials, etc. Reducing running costs by reducing material loss

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating a liquid metering device applied to one embodiment of the present invention, and FIG. 2 is a table showing the proper metering characteristics of the control method of the present invention. 1...Upstream tank, 2...Downstream tank, 3...Sound control device, 4...Load cell, 5... Load cell amplifier, 6...
...Surce liner, 7...Mountain/opening control valve (FC)
V), 8...stop valve (SRV), 9.
...Drain valve (DRV), 10...
・Cleaning waste liquid/lube (CVD). Representative Patent Attorney (8107) Kiyoyuki Sasaki (and 6 others) Figure 2

Claims (1)

[Claims] 1) In a closed-loop metering control method in which the flow velocity is changed based on a metering set value and a fed-back actual metered value, a metering set value that is arbitrarily set and a detector that measures an object to be measured are used. The output to the actuator that varies the flow velocity is calculated using one of the following control methods: fuzzy control, learning control, or optimal control from the observed amount of the deviation from the actual measured value and the amount of deviation change over time, and the flow velocity is successively adjusted to the optimal state. A method for controlling the measurement of liquids and powders, characterized by a change in the amount of liquid and powder. 2) The control method according to claim 1, wherein the flow rate change is a continuous change. 3) The control method according to claim 1, wherein the flow velocity change is a discrete change. 4) In a closed-loop metering control device that changes the flow rate based on the metering set value and the actual metered value that is fed back, there is an operator that changes the flow rate, a metering tank, and an object to be measured attached to the metering tank for observing the object to be measured. Fuzzy control or learning of the operating device is performed from the observed quantity obtained by calculating the deviation amount and deviation time change amount based on the arbitrarily set measurement setting value and the actual measurement value from the detector. A metering control device for liquids and powders, characterized by controlling or optimally controlling them.