JP3398202B2 - Submersible pump device for liquefied gas tank - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a submerged pump for a liquefied gas tank, and more particularly to a submerged pump capable of operating a plurality of submerged pumps by one controller. The present invention relates to a submerged pump device for a liquefied gas tank suitable for simplifying the apparatus and maintenance. 2. Description of the Related Art A conventional immersion pump apparatus for a liquefied gas tank will be described with reference to FIGS. 3, 4 and 5. FIG. FIG. 3 is a system diagram of a general immersion pump device for a liquefied gas tank, and FIG.
FIG. 5 is a sectional view of the immersion pump device, and FIG. 5 is a circuit diagram of a magnetic bearing control device of the immersion pump device shown in FIGS. In FIGS. 3 and 4, a submerged pump device is mounted in a liquefied gas tank 1 at a plurality of pumping pipes 2 suspended from a ceiling plate 1a of the liquefied gas tank 1 and at the lower end of each pumping pipe 2. Suction valve 3, a submersion pump 5 installed on a submersion pump seating surface 21 on the suction valve 3, a lifting wire 4 of the submersion pump 5, and a pump lifting mechanism at the top of the liquid pumping pipe 2. And a winder 30 and the like. Each of these submersible pumps 5
Is a pumping pipe 2 suspended vertically from the head plate 2a by a wire 4 for lifting from the head plate 2a.
Inside, for example, suspended at a position of 50m depth,
It is seated on the submerged pump seating surface 21. When the operation is started by supplying power to the submerged pump 5 via the power supply cable 17, the liquefied gas is sucked from the suction valve 3 and is pressurized, and is provided at an intermediate portion of the submerged pump 5 in the height direction. The liquid is discharged from the pump discharge port 12 into the liquid pumping pipe 2, rises the liquid pumping pipe 2, and is sent out to the discharge pipe 10. Then, as shown in FIG. 3, the respective discharge pipes 10 are assembled to the mother pipe 14 after passing through the respective check valves 11. When the submersible pump 5 stops operating, the liquefied gas remaining in the liquid pumping pipe 2 flows backward through the discharge port 12 of the submerged pump 5 and is returned from the suction valve 3 into the liquefied gas tank 1. Due to this return, the liquid level in the liquid pumping pipe 2 drops to the same level as the liquid level in the liquefied gas tank 1. Therefore, when the submersion pump 5 is restarted, the operation in a state where the discharge pressure is not ensured is continued until the liquid pumping tube 2 is filled with the liquefied gas. Normally, the operation time in this state is several minutes. Conventionally, a submerged pump for a liquefied gas tank can reduce the axial thrust (hereinafter, referred to as thrust) applied to the bearing during operation of the pump to zero, as described in Japanese Patent Publication No. 61-5558. A thrust balance device is provided. However, since this thrust equilibrium device is configured to function in a state in which the submerged pump generates a predetermined discharge pressure, the thrust equilibrium device is operated in a state where the discharge pressure is not ensured as in the above operation. The thrust acts on the bearing to shorten the life of the bearing. Since this thrust is composed of the weight of the rotating system of the submerged pump and the fluid force acting on the impeller of the submerged pump, the thrust increases as the size of the submerged pump increases and shortens the life of the bearing. . For this reason, the inventors of the present application have previously made a proposal as shown in FIG. 6 in order to reduce the thrust acting on the bearing when the submerged pump is started / stopped and to extend the life of the bearing. . That is, an active type thrust magnetic bearing (hereinafter simply referred to as a magnetic bearing) comprising an electromagnet and a ferromagnetic rotor is attached to the rotating shaft of the submerged pump 5, and a power supply of the magnetic bearing is supplied by a start signal to the submerged pump 5. Is inserted so that the rotating system of the immersion pump 5 is floated and supported.
To start inhalation of the liquefied gas,
As the downward thrust acting on the rotating system increases, the current value to the magnetic bearing is increased to correspond, and when the liquid level in the pumping pipe 2 gradually increases and reaches the discharge pipe 10, Since the discharge pressure increases, the increased pressure is detected by the pressure switch 41 provided in the discharge pipe 10, and this detection signal is taken into the control unit 50 of the magnetic bearing to shut off the power supply of the magnetic bearing. On the other hand, when the submersible pump 5 is stopped, when the pressure switch 41 detects that the pressure has decreased, the power of the magnetic bearing is turned on and the own weight of the rotating system of the submersible pump 5 is supported by the magnetic bearing. Let it. Then, after a lapse of a predetermined time, the power supply of the magnetic bearing is shut off. As described above, the immersion pump device for a liquefied gas tank (refer to Japanese Patent Application No. H10-163873) is configured to turn on / off the power of the magnetic bearing according to the discharge pressure value detected by the control device unit 50.
-268582). In this case, the power supply cable 17 is also connected to the control unit 50 via the take-out terminal block 42. The control of the magnetic bearing of the conventional immersion pump for a liquefied gas tank is performed by a submersible pump 1 as shown in FIG.
In this configuration, one control device unit 50 is installed in correspondence with one device, and therefore, a plurality of control device units 50 for the number of submerged pumps 5 are required. However, when the control unit 50 is installed in correspondence with each submerged pump,
As the number of the control device units 50 increases, the installation area and wiring of the control device unit 50 inevitably increase, and the device becomes complicated and the cost increases. Was. The present invention has been made in view of the above-mentioned problems of the prior art,
It is an object of the present invention to provide a submersible pump device for a liquefied gas tank that enables a plurality of submerged pumps to be operated by a single control device and can simplify the device and maintenance. In order to achieve the above-mentioned object, the present invention provides a submerged pump provided at a bottom of each of a plurality of pumping pipes suspended in a liquefied gas tank. This device discharges the liquefied gas sucked from the bottom of the pipe through the discharge pipe from the top of the pumping pipe.
Balance the axial thrust while generating a constant discharge pressure
In a submerged pump device for a liquefied gas tank provided with a thrust equilibrium device to be adjusted, a rotary shaft of each submerged pump is supported.
Active thrust magnetic bearing mounted
When, for detecting the discharge pressure of the discharge pipe of each submersible pump
A detecting means provided on each submerged pump cormorants, each submersible
One unit for controlling the active thrust magnetic bearing of the pump
Control unit and the one control unit
The active type thrust magnetic bearing of each submerged pump
A changeover switch that switches the circuit so that it can be controlled
And switching control means for switching the changeover switch in response to the discharge pressure signal of each submerged pump detected by the detection means , wherein the thrust balance device functions sufficiently.
Do not switch when starting or stopping each submerged pump.
Active thrust magnet of each submerged pump by control means
The bearing and the one control device unit are connected, and the
The active thrust magnetic bearings of each submerged pump are activated and
And stop control is performed . With the above construction, the first one of the plurality of submerged pumps is started, the liquid level in the liquid pump rises, and the rise of the discharge pressure is controlled by the pressure switch. When detected, the detection signal is sent to the control device unit via the switching control means, and the current value to the magnetic bearing is controlled. When the detection signal of the pressure switch is sent to the control unit via the switching control means, the next submersible pump is started, and the detection signal of the pressure switch of the submersible pump is changed to the switching control means. , And after a series of operations and operations are performed in the same manner as the first submerged pump, an activation signal is sequentially issued to the next submerged pump. Also, at the time of stop, a stop signal is similarly issued sequentially, the magnetic bearing is turned on, the downward thrust acting on the rotating system of the submerged pump is supported, and the ball bearing supporting the own weight of the rotating system is thrusted. Stop in a state where does not work. As described above, only one controller unit per one liquefied gas tank enables the starting and stopping of the magnetic bearings of a plurality of submerged pumps, as well as the installation area and wiring amount of the controller unit. In addition, wiring work can be reduced, the entire submersible pump device can be simplified, and the maintenance of the device and the workability of wiring can be improved. When the submerged pump is started, a signal from the discharge pressure detecting means of the pump discharge pipe is preferably used as an interlock signal so that the switching control means other than the pump is not switched. The same operation may be used as an interlock signal. An embodiment of the present invention will be described with reference to FIGS. This embodiment shows a case where four immersion pumps 5 are installed in the liquefied gas tank 1. FIG. 1 is a circuit diagram of a magnetic bearing control device of a submerged pump device, and FIG. 2 is a system diagram of a submerged pump device for a liquefied gas tank using the circuit of FIG. In the drawings, the same reference numerals as those in FIGS. 3 to 6 denote the same components or components having the same functions. In FIGS. 1 and 2, reference numeral 51 denotes a power supply cable 17 via a pressure switch 41 and a take-out terminal block 42 provided on a discharge pipe 10 of each submerged pump 5, and one control unit 50. The switching control means 60 for the signal from each pressure switch 41 installed between the conventional control unit 50 and the conventional control unit 50 surrounded by a chain line as shown in FIG.
And a control unit provided with a changeover switch that operates in response to a changeover signal from the changeover control means 51. As described above, the configuration in which the pressure switch 41 is provided on the discharge pipe 10 of each submerged pump 5 as the discharge pressure detecting means is the same as the above-described conventional technology, but is installed corresponding to each submerged pump 5. The control device unit 50
Through a single control device unit 60. Now, when the submerged pump 5 shown in FIG. 1 is started and the liquid level in the liquid pumping pipe 2 rises and the rise value of the discharge pressure is detected by the pressure switch 41, the detection signal is outputted. Is sent to the control device unit 60 via the switching control means 51, and the current value to the magnetic bearing is controlled. When the detection signal of the pressure switch 41 is sent to the control unit 60 via the switching control means 51, the submersible pump 5 of B is started, and the pressure switch of the submersible pump 5 of B is turned on. The switching control means 5
1, after a series of operations and operations are performed similarly to the submerged pump 5 of A,
An activation signal is issued to the submerged pump 5. Hereinafter, the submersion pump 5 of D is performed similarly. Also, at the time of stop, a stop signal is similarly issued sequentially, the magnetic bearing is turned on, the downward thrust acting on the rotating system of the submerged pump 5 is supported, and the ball bearing supports the own weight of the rotating system. Stop with no thrust applied. In the above description, the immersion pumps 5 are sequentially activated or stopped one by one for one control device unit 60. However, the immersion pumps 5 are activated or stopped collectively by a plurality of units. It is also possible to do it easily. As described above, by adding the switching control means 51, it is possible to start and stop the operation of the magnetic bearings of the plurality of submerged pumps 5 with only one control unit 60 per one liquefied gas tank. In addition, the installation area, wiring amount, and wiring work of the control device unit 60 can be reduced, and the entire immersion pump device can be simplified, so that the maintenance of the device and the workability of wiring can be improved. As described above, according to the present invention, a plurality of submerged pumps can be operated by a single control unit in the entire liquefied gas tank, and the apparatus and maintenance can be simplified. The effect that can be performed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of a magnetic bearing control device of a submerged pump device according to an embodiment of the present invention. FIG. 2 is a system diagram of a submerged pump device for a liquefied gas tank using the circuit of FIG. 1; FIG. 3 is a system diagram of a conventional general immersion pump device for a liquefied gas tank. FIG. 4 is a sectional view of a conventional submerged pump device. FIG. 5 is a circuit diagram of a magnetic bearing control device of the submerged pump device shown in FIGS. FIG. 6 is an explanatory diagram of magnetic bearing control for extending the life of a thrust bearing of a submerged pump. [Description of Signs] 1 ... liquefied gas tank, 2 ... pumping pipe, 5 ... submerged pump, 1
0: discharge pipe, 11: check valve, 17: power supply cable, 41
... pressure switch, 42 ... take-out terminal block, 50 ... control unit, 51 ... switch control means, 60 ... control unit including switch.

──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Hiroaki Yoda 603, Kandamachi, Tsuchiura-shi, Ibaraki Prefecture Inside the Tsuchiura Plant, Hitachi, Ltd. (72) Inventor Genichiro Nakamura 603, Kandamachi, Tsuchiura-shi, Ibaraki Prefecture Inside the Tsuchiura Plant, Hitachi, Ltd. JP-A-63-183296 (JP, A) JP-A-54-72502 (JP, A) JP-A-59-123693 (JP, U) JP-A-49-91803 (JP, U) (58) (Int.Cl. ⁷ , DB name) F04D 15/00 F04D 7/02 F04D 29/04

Claims (1)

(57) [Claims] A plurality of each suspended in a liquefied gas tank.
Submerged pumps are installed at the bottom of the pumping pipe, respectively,
The liquefied gas sucked from the bottom of the lifting pipe is
Discharge through the discharge pipeEquipment, and a submerged pump
Balance the axial thrust while generating a constant discharge pressure
With thrust balancing device to adjustLiquefied gas tank submersible
In the submersible pump device, Rotary shaft of each submerged pumpMounted to support
WasActive thrust magnetic bearingWhen,Of each submerged pump Detecting the discharge pressure of the discharge pipelike
Provided for each submersible pumpDetection meansWhen,Control the active thrust magnetic bearing of each submerged pump
One control device unit for Each of the submerged pumps is controlled by the one controller unit.
The circuit is designed so that active thrust magnetic bearings can be controlled sequentially.
A changeover switch for switching, Said Discharge pressure of each submerged pump detected by the detection means
SignalReceiving the changeover switchSwitching control hand to switch
Steps andWith Each submerged pump where the thrust balancer does not function well
When starting and stopping, the switching control means
Active thrust magnetic bearing for each submerged pump
Control unit is connected to each of the submerged pumps
Control that the magnetic thrust magnetic bearings start and stop in order.
Be Submersible pump device for liquefied gas tank characterized by the following:
Place.