JPH0579600B2 - - Google Patents

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】

[Prior Art] For example, Japanese Patent Laid-Open No. 55-38266 discloses a conventional device for receiving liquid from a mobile tank, which is equipped with a plurality of connecting pipes connected in parallel to an outlet pipe of a tank truck via a flexible hose. The 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 reaches 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, a safety device to prevent cavitation of the pump was removed. It was observed that troubles such as the pump starting and stopping the pump frequently occurred.

[0004] When the above causes are investigated in detail, when the tank truck and the receiving device are connected,
Air that existed in the flexible hose or inlet/outlet pipe between the outlet valve of the tank truck and the original valve of the receiving device does not completely move into the tank of the tank truck, and the air remains in the tank, and furthermore, the movement of the tank truck. This is because air mixed into the liquid due to vibration is immediately sucked in without being separated by standing still, and becomes gas again in the pump suction side piping, and this air is sucked by the pump. There was found.

【0005】

[Means for Solving the Problems] The present invention connects a mobile tank and a fluid transfer facility to drain the liquid in the mobile tank 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 mobile tank is sucked by the transfer pump means of the fluid transfer equipment, and then the liquid level in the mobile tank falls and air is sent from the mobile tank to the transfer pump means. The main idea is to drain the water to the dump tank again by gravity.

【0006】

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

[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 drained by gravity to the dump tank again. Trouble such as cavitation of the transfer pump means can also be avoided. In addition,
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. is preferable, but manual operation is also acceptable.

[0008]

[Embodiment] 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 is a dump tank installed underground, 3a,
3b is a transfer pump, and 4 is a control panel that controls the operation of the entire receiving device. 5 is a tank truck, which is usually divided into 3 to 5 conversions by partitions 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 is turned ON when opened, and a flexible hose 7 is provided on the inlet side of this main valve 8, and a flexible hose 7 is provided on the outlet side of the main valve 8. An automatic three-way valve 9 is connected to the automatic three-way valve 9, and a limit switch 9a that is turned on when switching to the piping _A1 side, which will be described next, is attached to the automatic three-way valve 9. One of the outlets of this automatic three-way valve 9 is located
A ₁ is connected to the header pipe 10, and the other outlet is connected to the header pipe 11 by a pipe B ₁ .

[0010] A plurality of the receiving parts 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 the header pipes 10 and 11 in parallel. The header pipe 10 is connected to the transfer pumps 3a, 3b by a pipe _A2 , and the header pipe 11 is connected to the tamp tank ₂ by a pipe B2. Also, pipe C from dump tank 2
is the piping in the vicinity of the transfer pumps 3a and 3b.
Connected to A ₂ . The system including the pipes A ₁ and A ₂ will be referred to as a tank direct reception system, and the system including the dump tank 2 and pipe C will be referred to as a dump tank transfer system.

[0011] Furthermore, the transfer pumps 3a, 3b and the storage tank 1 are connected by two lines of pipes D ₁ and D ₂ and a pipe D that joins these pipes. A flow rate transmitter 12b and a flow control valve 12 are sequentially provided in the piping _D1 of one system, and a flow rate limiting orifice 17 is provided in the piping _D2 of the other system.

[0012] In addition, the transfer pumps 3a and 3b have bypass piping E ₁ that bypasses the piping on the suction side and the discharge side.
_E2 , and each bypass pipe _E1 , _E2 is provided with a bypass valve _e1 , _e2, respectively. These bypass pipes E ₁ and E ₂ are the tank direct reception system, and if air gets mixed into the dump tank transfer system, the bypass valves e ₁ and e ₂ are opened and the static pressure of the storage tank 1 is applied to prevent air from entering the pipe C or the dump tank transfer system. It is arranged to exit from the dump tank 2 through the pipe A ₂ , the header pipe 10, the pipe A ₁ , the automatic three-way valve 9, the pipe B ₁ , the header pipe 11, and the pipe B ₂ in this order.

[0013] Furthermore, a level switch 13 is installed in each tank truck and detects a certain water level when the liquid content is close to empty and issues a signal for operating the pump and changing the flow rate. This level switch 13 is a compact type using an ultrasonic type or a capacitance type, and is usually installed on a reel on the roof above the loading area, and when the lorry arrives, it is pulled down and emptied first. Possible methods include setting it in a compartment (which one is emptied first depends on the lorry vehicle).

[0014] 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, the pump 3a,
Piping for the lorry direct reception system corresponding to 3b
Automatic valves 15a ₁ and 15b 1 are installed in A ₂ , automatic valves 15a _{2 and} 15b ₂ are installed in pipe C of the dump tank transfer system, and automatic valve 16 is installed in the system of pipe D ₁ .
a ₁ , 16b ₁ , and automatic valves 16a ₂ , 1 are installed in the pipe D ₂ system.
_6b2 is provided, which can be opened and closed in response to signals from the control panel 4 to switch between the above-mentioned systems.

[0015] These automatic valves 16a ₁ , 16a ₂ , 16
Limit switches (not shown) are attached to b ₁ and 16b ₂ , which are turned on when closed. Furthermore, as shown in FIG. 2, the control panel 4 includes a counter circuit 18a that counts the number of ON signals of the limit switches 9a attached to the automatic three-way valves 9 corresponding to the number of receiving tank trucks, and a circuit that operates the automatic valves and pumps. A sequence box 18 that stores the following components, 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 cascade type flow rate control signal that controls the flow rate received from the receiving tank trucks. and a constant current oscillator 20 that causes current to flow through the resistance box 19 to provide a voltage to the controller 12a.

[0016] In this embodiment, the transfer pump means includes the transfer pumps 3a, 3b and the automatic valves 15a ₁ , 15b ₁ , 16a ₁ , 16a ₂ , 1 attached thereto.
6b ₁ , 16b ₂ , bypass piping E ₁ , E ₂ and bypass valves e ₁ , e _{2 ,} etc., and the switching (selection) means is comprised of an automatic three-way valve 9 and piping A ₁ , B ₁ , and the switching means is It is composed of a limit switch 8a, and the control means is composed of a control panel 4.

[0017] Next, the operation of the liquid receiving device of the embodiment shown in the figure will be explained along with the operating method, divided into two parts: receiving from a tank truck and transferring from a dump tank to a storage tank.

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

(2) Connect the flexible hose 7 of each receiving part 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 original valve 8 by hand. Then the limit switch 8 attached to the valve
a becomes ON.

(5) Turn on this limit switch 8a
When the ON conditions for the level switch 13 are met, the automatic three-way valve 9 is switched after a certain period of time by a timer (not shown) in the sequence box 18 so that the liquid flows from the tank truck side to the piping _A1 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) Turn on this limit switch 9a
One transfer pump 3a is activated after a certain period of time by a signal and a timer (not shown) in the sequence box 18.
and giving a control reference signal corresponding to the received flow rate per tank truck to the flow rate controller 12a, and comparing the signal of the flow rate transmitter 12b indicating the flow rate of the pipe D with the control reference signal. The flow control valve 12 is adjusted in a cascade manner at the total 12a, and the amount flowing through the pipe D is set as the flow rate accepted per lorry.

(7) If 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.
Then, the flow rate controller 12a is adjusted according to the number of ON signals.
The setting of the control reference signal is changed, and the flow rate control valve 12 automatically controls the flow rate so that the accepted flow rate corresponds to the number of tank trucks.

[0025] 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 a counter circuit 18a in the sequence box 18, and outputting a relay output according to the required flow rate.
Applying current from a constant current transmitter 20 to a resistance box 19 that changes the resistance according to the relay output,
An output voltage, that is, a control reference signal, corresponding to the set flow rate is obtained. 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)

(8) When the number of tank trucks reaches a preset number, the second pump 3b is activated. In other words, 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.
When the number of signals exceeds the number, a start signal for the second pump 3b is output from the sequence box 18.

[0027] Furthermore, the starting priority order of the pumps 3a and 3b can be changed by making it possible to switch the starting signal from the sequence box 18 to each pump using a switch or the like, so that the operating times of the pumps 3a and 3b are made uniform. good.

(9) When the liquid level in the tank truck decreases and reaches a preset water level just before it becomes empty, the level switch 13 turns OFF and the automatic three-way valve 9 switches to the pipe _B1 side of the dump tank 2. Instead,
The remaining liquid in the lorry tank flows into the dump tank 2 by natural flow due to gravity. Further, as mentioned above, the automatic three-way valve 9 connects the pipe B ₁ to the dump tank 2.
At the same time, the limit switch 9a is turned off, and the opening degree of the flow control valve 12 and the number of pumps in operation are changed.

() 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 activates the sequence box 18 in the control panel 4.
give a signal to Assuming that two transfer pumps 3a and 3b are currently in operation, the signal causes the sequence box 18 to issue a signal to close the automatic valve ₁₆₁ on the discharge side of one transfer pump 3b.
The sequence box 18 changes the control reference signal to the flow rate controller 12a so that the control reference signal does not exceed the discharge capacity flow rate per pump. 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 16b ₁ closes, the limit switch in the automatic valve 16b ₁ turns on,
Under the ON condition, the pump 3b stops, and then the automatic valve 15b ₁ of the tank direct intake system on the pump suction side
is closed, and the automatic valve 15b ₂ of the tamp tank transfer system and the automatic valve 16b ₂ of the piping D ₂ 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 changed from the piping D ₁ system with the flow rate control valve 12 to the piping with the orifice 17.
D Switch to ₂ system.

(3) The above automatic valves 15b ₁ , 15b ₂ , 1
When switching between 6b ₁ and 16b ₂ is completed, 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 adjusted by the flow rate control valve 12, and the transfer flow rate is simply limited by the orifice 17 to below the maximum flow rate per pump. It is.

(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 valves 15b ₁ , 15b ₂ , 16b are turned on again. ₁ and _16b2 are switched to their original states, and normal liquid reception control is resumed 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 the liquid level in the dump tank 2 reaches a high level when originally only one transfer pump 3a is used to receive directly from the tank truck, the automatic valves 15a ₁ , 15b ₁ , 1
6a ₁ , 16b ₁ open, automatic valves 15a ₂ , 15b ₂ , 16
Since a ₂ and 16b ₂ are closed, automatic valve 16
b ₁ and 15b ₁ are closed, automatic valves 16b ₂ and 15b ₂ are opened, and the solution in the dump tank 2 is transferred to the storage tank 1 by the transfer pump 3b which is not in operation. At that time, the control reference signal to the flow rate controller 12a is
The sequence box 18 suppresses the flow rate so that the flow rate does not exceed the discharge capacity flow rate per pump 3a.

[0034] In this embodiment, the limit switch 8a is used as the switching means of the present invention, but it goes without saying that this may be replaced with the level switch 13, or even a manual button switch or the like. Moreover, it goes without saying that the control means may be constituted by a computer. Furthermore, in the case of transferring from the dump tank 2 to the storage tank 1 in this embodiment, transfer using the system of pipe C, automatic valve 15b ₂ , pump 3b, automatic valve 16b ₂ and pipe D ₂ has been described, but instead of this, It goes without saying that the sequence of transferring from the dump tank 2 to the storage tank 1 can be achieved by the system of the pipe C, the automatic valve 15a ₂ , the pump 3a, the automatic valve 16a ₂ and the pipe D ₂ . Also, in place of orifice 17, pipe _D1
A flow rate transmitter, a flow rate control valve, and a flow rate control meter similar to those provided in the above may also be provided separately. Furthermore, by using the above-mentioned combination, the number of pumps can be increased to three or more.

[0035] In addition, the original valve 8 in the embodiment,
In addition to improving the safety of the device, it also functions as a cap to prevent dirt from entering the dump tank 2, and also serves as a support for the limit switch 8a. , this can also be omitted as it has no effect on the reception by the transfer pumping means from other mobile tanks.

【0036】

[Effects of the Invention] Since the present invention has the above-described structure and operation, 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.

[0037] The 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 a start state and an end state that are the same state. Since a so-called closed loop is formed, when the transferred tank leaves the fluid transfer equipment and the next tank arrives, there is no particular problem even if the user overlooks the operation to check the switching state of the selection means, and operator malfunctions can be avoided. This 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 state and ending state, so automation work such as programs can be easily performed, and the automatic device itself is also required. You can simplify it by doing this.

[Brief explanation of the drawing]

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 the control panel.

[Figure 3] From the automatic three-way valve limit switch
FIG. 3 is a transition diagram of the number of ON signals.

[Explanation of symbols]

2 Dump tanks 3a, 3b Transfer pump 5 Tank truck (mobile tank) 9 Automatic three-way valve A ₁ , A ₂ , B ₁ , B ₂ 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 up by the transfer pump means of the fluid transfer equipment, and then returned to the dump tank by gravity before the liquid level in the mobile tank falls and air is pumped from the mobile tank to the transfer pump means. A method for receiving liquid from a mobile tank, characterized by draining it.