JPH04339800A - Method for receiving liquid from movable tank - Google Patents

Abstract

PURPOSE:To efficiently unload liquid from a tank lorry by removing air bubbles therefrom. CONSTITUTION:Pipes A1 and B1 are connected to a three-way valve 9 connected to a tank lorry 5. The one pipe A1 is connected to a transfer pump 3a and the other pipe B1 is connected to a dump tank 2. The dump tank 2 is provided in a lower position than the tank lorry 5. By the operation of the three-way valve 9, the pipe is arranged in communication with the tank lorry 5 to allow liquid in the tank lorry 5 to flow into the dump tank 2 under the force of gravity. In this way the air bubbles trapped between the dump tank 2 and the three- way valve 9 are eliminated. After the lapse of a predetermined time, the pipe A1 is arranged in communication with the tank lorry 5 by switching the three- way valve 9 and the liquid in the tank lorry 5 is unloaded by operating the transfer pump 3a. When the liquid in the tank lorry 5 is running short, the liquid therein is sent through the pipe B1 into the dump tank 2 by switching again the three-way valve 9.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid receiving method for receiving liquid in a mobile tank such as a tank truck or a tank wagon into a storage tank or the like.

0002

2. Description of the Related Art A conventional device for receiving liquid from a mobile tank, for example, disclosed in Japanese Patent Application Laid-open No. 55-38266, is equipped with a plurality of connecting pipes connected in parallel to an outlet pipe of a tank truck via a flexible hose. A header pipe is connected to the suction pipe on the suction side of the transfer pump, and a drop pipe is provided that branches from the suction pipe and leads to a dump tank (air separation device) located at a lower position than the tank truck. It is stated that at the beginning of acceptance, the liquid inside the tank truck is sucked directly by a pump, and as the acceptance progresses, the liquid level inside the tank truck decreases, and when the possibility of air being pumped is visually observed, the flow path is switched to the dump tank mentioned above. .

0003

[Problems to be Solved by the Invention] However, when we actually manufactured and used the liquid receiving device as described above, we found that, unexpectedly, during the initial stage of receiving liquid when the liquid is directly sucked by the pump, the safety device for preventing cavitation of the pump was removed. It was observed that troubles such as the pump starting and stopping the pump frequently occurred.

[0004] A detailed investigation of the above causes revealed that when the tanker truck and receiving device were connected, there was a problem in the flexible hose or inlet/outlet pipe between the outlet valve of the tanker truck and the main valve of the receiving device. If the air does not completely move into the tank of the tank truck and remains there, or even if the air gets mixed into the liquid due to vibrations while the tank truck is moving, it is immediately sucked in without being separated by standing still, causing pump suction. It turned out that the air had become gas again in the side piping and was being sucked in by the pump.

[0005]

[Means for Solving the Problems] The present invention connects a mobile tank and a fluid transfer facility to allow the liquid in the mobile tank to drain by gravity into a dump tank of the fluid transfer facility located at a lower position than the mobile tank. After a predetermined period of time has elapsed from the start of outflow, the liquid in the moving tank is sucked by the transfer pump means of the fluid transfer equipment, and then, before the liquid level in the moving tank falls and air is sent from the moving tank to the transfer pump means. The gist is to drain it back to the dump tank by gravity.

[0006]

[Operation] By taking the above measures, in the early stage of receiving from a mobile tank, air present in the flexible hose or inlet/outlet pipe when the mobile tank and receiving device are connected, and liquid due to vibration during movement of the mobile tank can be removed. The air mixed in the liquid is entrained by the natural flow of the liquid in the transfer tank to the dump tank, where it is separated. After that, there is no air in the flexible hose, inlet/outlet pipe, etc., and the air mixed into the liquid due to vibration during movement of the moving tank has been separated by standing still, so the pump means to transfer the liquid from the moving tank. Cargo handling can be started without causing cavitation even if suction is applied.

[0007] Near the end of receiving from the mobile tank, the liquid level in the mobile tank drops and air is sent from the mobile tank to the transfer pump means, but before that, it is forced to flow out to the dump tank again by gravity. Trouble such as cavitation of the transfer pump means can also be avoided. Note that this switching between the suction flow path and the drop flow path can be done automatically by providing a timer or a liquid level detection means that detects when the liquid in the moving tank has fallen to a predetermined liquid level and outputs a detection signal. It is preferable to do this, but it may also be done manually.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the figure, 1 is a storage tank installed above ground, 2
3 is a dump tank provided underground, 3a and 3b are transfer pumps, and 4 is a control panel that controls the operation of the entire receiving apparatus. 5 is a tank truck, usually 3~ depending on the partition
It is divided into five conversions and has an outlet valve 5a.

[0009] In the receiving part 6 of this liquid receiving device, a main valve 8 is provided with a limit switch 8a that turns on when opened, and a flexible hose 7 is connected to the inlet side of the main valve 8, and a flexible hose 7 is connected to the outlet side of the main valve 8. An automatic three-way valve 9 is connected to the automatic three-way valve 9, and the following piping A is connected to the automatic three-way valve 9.
Limit switch 9a that turns ON when switched to the 1 side
is installed. One outlet of this automatic three-way valve 9 is connected to a header pipe 10 through a pipe A1, and the other outlet is connected to a header pipe 11 through a pipe B1.

[0010] A plurality of receiving portions 6 are provided so that a plurality of tank trucks 5 can be connected at the same time, and all of them are connected to header pipes 10 and 11 in parallel. The header pipe 10 is connected to the transfer pump 3 through the pipe A2.
a, 3b, and header pipe 11 is connected to pipe B2.
is connected to dump tank 2. Further, a pipe C from the dump tank 2 is connected to the pipe A2 near the transfer pumps 3a and 3b. In addition, piping A1, A2
The system using the dump tank 2 and piping C is called the dump tank transfer system.

Further, the transfer pumps 3a, 3b and the storage tank 1 are connected by two lines of piping D1, D2 and a piping D that joins these lines. And piping D1 of one system
A flow rate transmitter 12b and a flow rate regulating valve 12 are installed in this order, and a flow rate limiting orifice 1 is installed in the piping D2 of the other system.
7 is provided.

Furthermore, the transfer pumps 3a and 3b have bypass pipes E1 and E2 that bypass the pipes on the suction side and the discharge side, and each bypass pipe E1 and E2 has a bypass valve e1,
e2 are provided respectively. This bypass piping E1
, E2 is the tank direct reception system, and if air gets mixed into the dump tank transfer system, the bypass valves e1 and e2 are opened to apply the static pressure of the storage tank 1 and the air is transferred to pipe C or sequentially to pipe A2, header pipe 10, Piping A1, automatic three-way valve 9
, pipe B1, header pipe 11, and pipe B2 to exit from the dump tank 2.

[0013]Furthermore, set inside each tank truck,
A level switch 13 that detects a certain water level when the liquid content is nearly empty and issues a signal for operating the pump and changing the flow rate.
has been established. This level switch 13 is an ultrasonic type,
Alternatively, it is a compact capacitive type, which is usually attached on a reel to the roof above the loading area, and when the lorry arrives, it is pulled down to the compartment that will be emptied first (note which compartment will be emptied first). One possible method is to set it within the lorry vehicle.

A level switch 14 is also set in the dump tank 2 to detect the high level and low level of the liquid level. In addition, an automatic valve 15a1 is installed in the piping A2 of the lorry direct receiving system corresponding to each of the pumps 3a and 3b.
, 15b1, automatic valves 15a2, 15b2 are provided in the pipe C of the dump tank transfer system, automatic valves 16a1, 16b1 are similarly provided in the system of the pipe D1, and automatic valves 16a2, 16b2 are provided in the system of the pipe D2. , control panel 4
It is possible to switch between the above-mentioned systems by opening and closing in response to signals from the system.

These automatic valves 16a1, 16a2, 16b
1 and 16b2 are attached with limit switches (not shown) that turn on when closed. Further, the control panel 4 includes a counter circuit 18 that counts the number of ON signals of the limit switch 9a attached to the automatic three-way valve 9 corresponding to the number of receiving tank trucks as shown in FIG.
a, a sequence box 18 that houses circuits for operating automatic valves and pumps, a resistance box 19 that changes the resistance value in accordance with the number of receiving tank trucks counted by the counter circuit 18a, and a flow rate received from the receiving tank trucks. and a constant current transmitter 20 that sends a current through the resistance box 19 in order to provide a control reference signal for controlling the flow rate controller 12a as a voltage to the cascade flow rate controller 12a.

In this embodiment, the transfer pump means includes the transfer pumps 3a, 3b and the automatic valves 15a1, 15b1, 16a1, 16a2, 16b1,
16b2, bypass piping E1, E2 and bypass valve e1
, e2, etc., the switching (selection) means is constituted by an automatic three-way valve 9 and piping A1, B1, the switch means is constituted by a limit switch 8a, and the control means is constituted by a control panel 4.

Next, the operation of the liquid receiving device according to the embodiment shown in the figure will be explained along with the operating method, divided into two sections: receiving from a tank truck and transferring from a dump tank to a storage tank.

I) Receipt from tank truck 1)
Automatic valves 15 on the suction side and discharge side of the pumps 3a and 3b
a1, 15b1, 16a1, 16b1 are opened by operation push buttons (not shown) attached to the sequence box 18 of the control panel 4.

2) Connect the flexible hose 7 of each receiving section 6 arbitrarily to the outlet valve 5a of each tank truck 5 that has arrived.

3) Set the level switch 13 for each tank truck. At this time, there is sufficient liquid content, so this level switch 13 is turned on.

4) Next, open the main valve 8 by hand. Then, the limit switch 8a attached to the valve turns O.
It becomes N.

5) Turning on this limit switch 8a
When the conditions for turning on the level switch 13 are met, a timer (not shown) in the sequence box 18 causes the automatic three-way valve 9 to close the pipe A1 from the tank truck side after a certain period of time.
Switch so that liquid flows to the side. At this time, the limit switch 9a of the automatic three-way valve 9 is turned on. Note that until the automatic three-way valve 9 is switched, the automatic three-way valve allows liquid to flow from the tank truck side to the dump tank 2.

6) Turning on this limit switch 9a
In response to the signal, a timer (not shown) in the sequence box 18 starts one transfer pump 3a after a certain period of time,
Then, a control reference signal corresponding to the flow rate received per tank truck is given to the flow rate controller 12a, and the pipe D is connected.
The flow control valve 12 is adjusted in a cascade manner by the flow controller 12a, which compares the signal from the flow transmitter 12b indicating the flow rate with the control reference signal, and the flow rate through the pipe D is adjusted to the receiving flow rate per lorry. shall be.

7) When the number of tank trucks increases thereafter, the limit switch 9a of the automatic three-way valve 9 of the newly connected tank truck is turned ON, and the control standard for the flow rate controller 12a is set according to the number of ON signals. The setting of the signal is changed, and the flow rate control valve 12 automatically controls the flow rate so that the received flow rate corresponds to the number of tank trucks.

That is, this flow rate control is performed by counting the number of ON signals of the limit switch 9a of each automatic three-way valve 9 using the counter circuit 18a in the sequence box 18, causing a relay output according to the required flow rate to be output, and then A constant current transmitter 20 is installed in a resistance box 19 that changes resistance according to the output.
A current is applied to obtain an output voltage corresponding to the set flow rate, that is, a control reference signal. Then, the control reference signal is used as a cascade signal of the flow rate regulator 12a, and the opening degree of the flow rate regulating valve 12 is controlled. (See Figure 2)

0
8) When the number of tank trucks reaches a preset number, the second pump 3b is activated. That is, the counter circuit 18a counts the number of ON signals of the limit switch 9a of each automatic three-way valve 9, and as shown in the relationship shown in FIG. A start signal is issued.

The starting priority order of the pumps 3a and 3b is as follows:
The activation signal from the sequence box 18 to each pump can be switched using a switch or the like, so that the pumps 3a and 3b can be switched.
The operating time may be made uniform.

9) When the liquid level in the tank truck decreases to a preset water level just before it becomes empty, the level switch 13 is turned OFF and the automatic three-way valve 9 is switched to the pipe B1 side of the dump tank 2, The remaining liquid in the lorry tank flows into the dump tank 2 by natural flow due to gravity. Further, as described above, when the automatic three-way valve 9 is switched to the pipe B1 side to the dump tank 2, the limit switch 9a is turned off at the same time, and the opening degree of the flow rate control valve 12 and the number of pumps in operation are changed.

II) Transfer from the dump tank to the storage tank 1) When the liquid level rises due to the inflow into the dump tank 2 and reaches a high level, the level switch 14 detects this and sends a message to the sequence box 18 in the control panel 4. give a signal. Assuming that the two transfer pumps 3a and 3b are currently in operation, the sequence box 18 outputs a signal to close the automatic valve 16b1 on the discharge side of one transfer pump 3b in response to the signal, and the sequence box 18 The control reference signal to the flow rate controller 12a is changed so that the control reference signal does not exceed the discharge capacity flow rate per machine. As a result, the automatic valve 16b1 is closed, the flow rate control valve is controlled to a flow rate equivalent to one pump, and one transfer pump 3a continues to receive liquid from the tank truck.

2) When the automatic valve 16b1 closes, the limit switch in the automatic valve 16b1 turns ON, and under the ON condition, the pump 3b stops, and then the automatic valve 15b1 of the tank direct intake system on the pump suction side closes. The automatic valve 15b2 of the dump tank transfer system and the automatic valve 16b2 of the pipe D2 system are opened. Therefore, in this transfer pump 3b, the suction side is switched from the tank direct reception system to the dump tank transfer system, and the discharge side is also switched from the piping D1 system with the flow control valve 12 to the piping D2 system with the orifice 17. .

3) The above automatic valves 15b1, 15b2
, 16b1, and 16b2, the pump 3b that has been temporarily stopped is started again, and the liquid in the dump tank 2 is transferred to the storage tank 1. In this case,
The flow from the dump tank 2 by the pump 3b is not regulated by the flow control valve 12, and the transfer flow rate is simply limited by the orifice 17 to below the maximum flow rate per pump.

4) When the liquid level in the dump tank 2 falls to a low level, the level switch 14 detects this, the transfer pump 3b stops, and the automatic valve 15 is activated again.
b1, 15b2, 16b1, and 16b2 switch to their original states, and return to normal liquid reception control in which the two transfer pumps 3a and 3b directly receive liquid from the tank truck.

5) In the above, when the liquid level in the dump tank 2 reaches a high level when originally only one transfer pump 3a was used to receive directly from the tank truck, the automatic valves 15a1, 15b1, 16a1, 16b
1 is open, automatic valves 15a2, 15b2, 16a2, 16b
2 is closed, the automatic valves 16b1 and 15b1 are closed, the automatic valves 16b2 and 15b2 are opened, and the liquid content of the dump tank 2 is transferred to the storage tank 1 by the transfer pump 3b which is not in operation. At this time, the control reference signal to the flow rate controller 12a is suppressed by the sequence box 18 so that the flow rate does not exceed the discharge capacity flow rate per pump 3a.

In this embodiment, the limit switch 8a is used as the switch means of the present invention, but it is of course possible to replace this with the level switch 13, or even use a manual button switch or the like. . Moreover, it goes without saying that the control means may be configured by a computer. Furthermore, in the case of transferring from the dump tank 2 to the storage tank 1 in this embodiment, the pipe C, the automatic valve 15b
2. Transfer using the system of pump 3b, automatic valve 16b2, and piping D2 has been explained, but instead of this, piping C and automatic valve 15
Of course, the sequence of transferring from the dump tank 2 to the storage tank 1 can be made by using the system of the pump 16a2, the pump 3a, the automatic valve 16a2, and the piping D2. Further, in place of the orifice 17, a flow rate transmitter, a flow rate control valve, and a flow rate control meter similar to those provided in the pipe D1 may be separately provided. Furthermore, with the above combination, the number of pumps can be increased to 3.
You can also make it more than just a stand.

In addition, in the embodiment, the original valve 8 improves the safety of the device and functions as a cap to prevent dirt from entering the dump tank 2, while also serving as a support for the limit switch 8a. If the selection means selects the drop-in channel, this can be omitted since it has no effect on the reception by the transfer pump means from other mobile tanks.

[0036]

[Effects of the Invention] Since the present invention has the structure and operation described above, it has the following effects. ■ Suction from the moving tank can be started smoothly and reliably without causing cavitation of the transfer pump, and complicated work due to stopping the transfer pump can be avoided.

■ Transfer switching between the dump tank and the transfer pump means is "dump tank → transfer pump means → dump tank", and the selection means for switching the flow path such as a three-way valve has the same starting state and ending state. This forms a so-called closed loop, so when a mobile tank that has been accepted leaves the fluid transfer equipment and the next mobile tank arrives, there is no problem even if the operator overlooks the operation to check the switching state of the selection means. Malfunctions can be prevented and complicated switching operations can be simplified.

[0038]Furthermore, when automating, the selection means for switching the flow path such as a three-way valve has the same starting and ending states, making it easy to automate programs and other tasks, and to make the automation itself easier. It can be simplified if necessary.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing the overall configuration of a device for receiving liquid from a mobile tank that implements the present invention.

FIG. 2 is a block diagram showing the configuration of a control panel.

FIG. 3 is a transition diagram of the number of ON signals from an automatic three-way valve limit switch.

[Explanation of symbols]

2 Dump tank 3a, 3b Transfer pump 5 Tank truck (mobile tank) 9 Automatic three-way valve A1, A2, B1, B2 Piping

Claims (1)

[Claims] Claim 1: Connecting a mobile tank and fluid transfer equipment, causing the liquid in the mobile tank to flow out by gravity to a dump tank of the fluid transport equipment located at a lower position than the mobile tank, and moving the liquid after a predetermined period of time has elapsed from the start of this outflow. The liquid in the tank is sucked by the transfer pump means of the fluid transfer equipment and then drained by gravity again into the dump tank before the liquid level in the transfer tank falls and air is pumped from the transfer tank to the transfer pump means. A method for receiving liquid from a mobile tank, characterized in that: