JPH0442276B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in a flow rate control device for supplying a fixed amount of fluid.

[Technical background of the invention and its problems]

Conventionally, flow control devices have been used to supply a fixed amount of heavy oil, light oil, etc. from an oil refinery to the tanks of tankers and tank trucks, or to supply liquids such as beer and chemicals to containers for preparation.

FIG. 1 is a diagram showing a system for sending heavy oil from an oil refinery to a tanker tank using such a flow rate control device. The temperature of the heavy oil discharged by the pump 1 in the tank 2 of the oil refinery is measured by a temperature compensation resistance temperature detector 3, and the flow rate of the heavy oil is measured by a pulse generating flowmeter 4 such as a turbine flowmeter or a positive displacement flowmeter. These measurement signals are introduced into the flow control device 10.

This flow rate control device 10 suddenly opens the operation valve 5 based on the flow rate pulse signal output from the flow meter 4 and supplies the tank of the tanker 6.
It is determined from the flow rate pulse signal and time that the weight in the tank of the tanker 6 has reached a predetermined accumulated flow rate, and the operation valve 5 is suddenly opened.

However, when the operation valve 5 is suddenly opened and closed as described above, a water hammer phenomenon occurs due to a sudden change in the flow rate. Therefore, in order to eliminate this phenomenon,
A flow rate control device 10 as shown in FIG. 2 is used. The flow rate control timing of this device is performed at a predetermined period T (0.2 to 1 second) according to the control pulse shown in FIG. 3 issued from the control pulse generator 12, and the control content is composed of ROM and RAM. This is performed by program processing stored in the ROM of the storage unit 11.

First, when the flow rate control device 10 is powered on, the central processing unit (hereinafter abbreviated as CPU) 13 operates according to the program in the ROM. As a result, the operating valve 5 is opened and heavy oil is sent to the tank 6. The flow rate counter 14 counts the flow rate pulse signal from the flow meter 4 and sends it to the storage unit 1 via the bus 15.
1 RAM. The CPU 13 uses the count value of the flow rate pulse signal stored in the RAM to
Calculate and find the flow rate q per unit time sent to. Furthermore, the CPU 13 calculates and obtains the accumulated flow rate Q of the tank 6 from the same count value, and calculates the difference between this accumulated flow rate Q and the target accumulated flow rate Q1 of the tank 6, Q1-
Q is calculated by calculation, and based on the value of this deviation Q1-Q, an operation signal by P control is sent to the DA converter 16 via the bus 15 according to a program. This operation signal is converted into an analog signal by the DA converter 16 and sent to the operation valve 5. This allows the degree of opening and closing of the operation valve 5 to be adjusted.

At the same time, the temperature of the fluid is detected by the resistance temperature detector 3, converted into a temperature by the temperature measuring section 17, converted into a digital signal by the AD converter 18, and stored in the RAM via the bus 15. Thereby, the CPU 13 determines whether the temperature of the fluid is constant. The operation is performed as described above, and the flow rate q per unit time is controlled.

This flow rate control pattern is performed as shown in FIG. 3 above. That is, the flow rate q per unit time at the start of control increases at a predetermined rate of increase and is sent to the tank 6. This flow rate q reaches the upper limit flow rate q1 at time t1
Then, the heavy oil is sent to the tank 6 at a constant upper limit flow rate q1. Then, when the accumulated flow rate Q of the tank 6 reaches the pre-batch flow rate QP that is preset according to the target accumulated flow rate Q1 at time t2, the flow rate q decreases at a predetermined rate of decrease from this time t2 until it reaches the lower limit flow rate q2. and sent to tank 6. and,
When the lower limit flow rate q2 is reached at time t3, the flow rate q
is sent to the tank 6 at a constant flow rate of the lower limit flow rate q2. Thereby, when the CPU 13 determines that the accumulated flow rate Q of the tank 6 has reached the target accumulated flow rate Q1, it outputs an operation signal to fully open the operation valve 5 at time t4 of the control timing when the target accumulated flow rate Q1 is exceeded. This stops the flow supply.

However, in such control, the predetermined period T is 1
If the cycle is as long as a second, a flow rate error ΔQ may occur even if the operation valve 5 is fully closed. for example,
If we use a flowmeter that generates one pulse for a flow rate of 0.1 liters and send a target accumulated flow rate of 500 liters of heavy oil to the tank 6 under the condition that the lower limit flow rate q1 is 1 liter per second, the predetermined Since the period T is 1 second, there is a possibility that 501 liters will be sent to the tank 6. Therefore, when sending heavy oil to tank 6 with an error of less than 0.1 liter, the amount may significantly exceed 0.1 liter.

[Purpose of the invention]

Therefore, it is an object of the present invention to provide a flow rate control device that can accurately send fluid at the target accumulated flow rate by immediately closing an operating valve when the accumulated flow rate of a tank or the like reaches the target accumulated flow rate even when the control cycle is long. With the goal.

[Summary of the invention]

The present invention obtains the accumulated flow rate of the fluid accumulated in the container by taking in the count value of the flow rate counter in the control means according to the control pulse, and calculates the accumulated flow rate of the fluid accumulated in the container, and the target accumulated flow rate obtained from this accumulated flow rate and a preset flow rate control pattern. A control calculation is performed on the deviation of the control valve, and an operation signal indicating the degree of opening/closing of the operation valve is output. At the same time, when the accumulated flow rate reaches a preset range accumulated flow rate that is lower than the target accumulated flow rate, the difference between the target accumulated flow rate and the accumulated flow rate is calculated. A value corresponding to the deviation is preset in a preset counter, and when this preset value is decreased to zero by a flow rate pulse signal from a flow meter, a signal to stop flow rate control is sent to the control means. .

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. Note that the same parts as in FIG. 2 are given the same reference numerals, and detailed explanation thereof will be omitted.

FIG. 4 is a block diagram of the flow control device. The difference in this device from that shown in FIG. 2 is that a preset counter 20 is provided.

This preset counter 20 indicates that the accumulated flow rate Q in the tank 6 of the tanker is within the preset range accumulated flow rate Q.
2, a count value corresponding to the deviation Q1-Q between the target accumulated flow rate Q1 and the accumulated flow rate Q in the tank 6 is preset, and this count value is set according to the input of the flow rate pulse signal from the flow meter 4. When the value decreases to zero, an interrupt signal is sent to the CPU 13 to open the operating valve 5.

Next, we will explain the operation of the device applied when transporting heavy oil from an oil refinery to a tanker tank. First, until the accumulated flow rate of heavy oil accumulated in the tank 6 reaches the preset range accumulated flow rate Q2 shown in FIG. 3, the flow rate control is performed in the same way as in the conventional case.

That is, when the flow control device 10 is powered on, the CPU 13 gradually opens the operation valve 5 based on commands from a program stored in the ROM. As a result, heavy oil is sent from the tank 2 of the oil refinery to the tank 6 of the tanker. The amount of this heavy oil is controlled when pulses are generated every predetermined period T from the control pulse generator 12 shown in FIG. Flow meter 4
measures the flow rate of heavy oil and sends a flow rate pulse signal shown in the figure to the flow counter 14. The flow rate counter 14 counts the flow rate pulse signal from the flow meter 4 and sends this count value to the storage unit 1 via the bus 15.
Send to 1 RAM. The CPU 13 calculates the count value of the flow rate pulse signal stored in the RAM to obtain the flow rate q per unit time. Furthermore, the CPU 13 calculates and obtains the accumulated flow rate Q of the tank 6 from the same count value, and combines this accumulated flow rate Q with the target accumulated flow rate Q of the tank 6.
Calculate the deviation Q1-Q from 1, and use the program based on the value of this deviation Q1-Q.
The operation signal by PI control is sent via bus 15 to D-
The signal is sent to the A converter 16. This operation signal is converted into an analog signal by the DA converter 16 and sent to the operation valve 5. As a result, the opening degree of the operation valve 5 is adjusted, and the flow rate of heavy oil is controlled.

Next, this flow rate control will be specifically explained with reference to FIG. When the heavy oil starts to be delivered, the flow rate q per unit time increases at a predetermined rate of increase, and the heavy oil is sent to the tank 6. This flow rate q is the upper limit flow rate q
When the flow rate reaches 1, the flow rate q1 is maintained and fed into the tank 6. Then, when the accumulated flow rate Q of heavy oil in the tank 6 reaches a preset range accumulation amount QP that is preset according to the target accumulated flow rate Q1, the flow rate q is sent to the tank 6 while decreasing at a predetermined reduction rate. When this flow rate q reaches the lower limit flow rate q2, the flow rate is sent to the tank 6 while maintaining the flow rate q2.

As a result, the accumulated flow rate Q of the heavy oil in the tank 6 has reached the preset range accumulated flow rate Q2 (for example, if the count of the target accumulated flow rate Q1 in the flow rate counter 14 is set to 500, the accumulated flow rate Q of heavy oil is 480 to 490 counts). At this time, the CPU 13 calculates the deviation Q1 between the target accumulated flow rate Q1 and the accumulated flow rate Q of heavy oil in the tank 6.
-Q is obtained by calculation, and the count number of this deviation Q1-Q is preset in the preset counter 20.

This preset counter 20 counts the flow rate pulse signal from the flow meter 4 and decrements a preset count value. When this count reaches zero, that is, when the accumulated flow rate Q of heavy oil in the tank 6 reaches the target accumulated flow rate Q1,
Preset counter 20 sends an interrupt signal to CPU 13. In response to this interrupt signal, the CPU 13 sends a signal to close the operating valve 5 via the bus 15 to D-A.
to converter 16. This signal is sent to the D-A converter 16
The signal is converted into an analog signal and sent to the operating valve 5. This closes the operating valve 5.

In this way, in the above embodiment, control is performed according to the flow rate control pattern, and when the accumulated flow rate of heavy oil reaches the preset range accumulated flow rate, the accumulated flow rate Q
and the target accumulated flow rate Q1 of tank 6 Q1-Q
The preset counter 20 is preset with a count value corresponding to the control period T, and when the preset count value decreases at a cycle shorter than the control cycle T and reaches zero, an interrupt signal is sent to the CPU 13 and the operation valve 5 is activated. Since it is made to close, even if the predetermined cycle T is a long cycle time (for example, 1 second), the accumulated flow rate Q of heavy oil sent to the tank 6 is equal to the target accumulated flow rate Q.
This does not happen, and heavy oil is sent to the tank 6 accurately with respect to the target accumulated flow rate Q, without causing a situation where the accumulated flow rate ΔQ is increased by ΔQ until the control timing is reached.

Moreover, this flow rate control device 10 is used not only when feeding heavy oil into the tank 6, but also when feeding light oil, beer,
It can also be applied to the case where a preset amount of a liquid such as a medicine is accurately sent into a predetermined container.

Note that the present invention is not limited to the above embodiment. For example, the flow rate control device 1 shown in FIG.
A counter 30 may be provided at 0. This counter 30 is a combination of the flow rate counter 14 and the preset counter 20 shown in FIG. That is, this counter 30 counts the flow rate pulse signal from the flow meter 4. Then, the accumulated flow rate of the heavy oil sent to the tank 6 is set within a preset accumulated flow rate range (for example, the target accumulated flow rate Q1 is determined by the counter 30).
If the count of is 500, then 480 before reaching this
490 counts), the deviation Q1-Q between the target accumulated flow rate Q1 and the accumulated flow rate Q of the tank 6 is preset in the counter 30.

For example, if the full scale of the counter 30 is 1000 counts and the target accumulated flow rate is 500 and the flow rate is preset at 486, then
The count value preset in the counter 30 is
The count is 986. Next, the fluid is sent and the count advances, and when the count of the counter 30 reaches 1000 counts, the counter 30 at this time
Sends an interrupt signal to 13. As a result, CPU1
3 sends a signal to the operating valve 5 to close it. Upon receiving this signal, the operation valve 5 closes and stops supplying the flow rate to the tank 6.

Therefore, even in the flow rate control device 10 shown in FIG.
By controlling the flow rate to the tank 6, it is possible to accurately send only the target accumulated flow rate Q1 of heavy oil.

Further, this flow rate control device can accurately send not only heavy oil but also light oil, beer, chemicals, and other liquids to a predetermined container by the target accumulated flow rate Q1.

〔Effect of the invention〕

As described above, according to the present invention, even when the control cycle is long, when the accumulated flow rate in a tank or the like reaches the target accumulated flow rate, the operation valve is immediately closed and the fluid at the target accumulated flow rate can be accurately sent. A control device can be provided.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram of a flow rate control device applied to sending heavy oil into a tank, Figure 2 is a block configuration diagram of a conventional device, Figure 3 is a diagram showing the state of flow control, and Figure 4 is a diagram of the present invention. FIG. 5 is a block diagram showing a modification of the flow rate control device. 1... Pump, 2... Oil refinery tank, 3...
Resistance temperature sensor, 4... Flow meter, 5... Operation valve, 6... Tanker tank, 10... Flow rate control device, 11... Storage section, 12... Control pulse generation section, 13... Central processing unit, 14... Flow rate counter, 15...bus, 16...A
-D converter, 17...Temperature measuring section, 18...A-D converter, 20...Preset counter.

Claims (1)

[Scope of Claims] 1. A flow meter that detects the flow rate of fluid supplied to a container and outputs a flow rate pulse signal according to the flow rate per unit time; and an operating valve that adjusts the supply of fluid to the container. , a flow rate counter that counts flow rate pulse signals from the flow meter; a control pulse generator that emits control pulses with a predetermined cycle longer than the cycle of the flow rate pulse signal output from the flow meter; and a count value of the flow rate counter. an accumulated flow rate calculating means for obtaining the accumulated flow rate of the fluid accumulated in the container according to the control pulse; and an accumulated flow rate calculated by the accumulated flow rate calculating means and a preset flow rate control pattern. a control means that calculates a deviation from a target accumulated flow rate, performs a control calculation on the deviation, and outputs an operation signal indicating the degree of opening/closing of the operation valve; A value corresponding to the deviation between the target accumulated flow rate and the accumulated flow rate is preset when a preset range accumulated flow rate smaller than the flow rate is reached, and this preset value is decreased by a flow rate pulse signal from the flow meter. A flow rate control device comprising: a preset counter that sends a signal to the control means to stop the flow rate control when the count reaches zero.