JP2016098081A - Energy saving control method for air type unloader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an energy saving control method for an air type unloader capable of achieving energy saving without hindering cargo handling.SOLUTION: In an energy saving control method for an air type unloader 1, a transport pipe 13 connected to a suction tank 16 to which negative pressure by a blower 15 is applied is disposed in a boom 12 capable of performing an undulation operation and a turning operation, and cereals are sucked into the suction tank 16 via the transport pipe 13. An electric motor for driving the blower 15 includes a variable voltage variable frequency device. A power source of the blower 15 is automatically controlled by the variable voltage variable frequency device so that suction pressure of the blower 15 becomes minimum suction force required for normal cargo handling during a cargo handling operation.SELECTED DRAWING: Figure 1

Description

  TECHNICAL FIELD The present invention relates to an energy saving control method for a pneumatic unloader used for unloading (landing) a bulk load such as grain in a ship's hold (hereinafter, sometimes referred to as “grain”). The present invention relates to an energy saving control method for a pneumatic unloader that can save energy without hindering the unloading (hereinafter sometimes referred to as “loading”).

Conventionally, in the transportation of grain by ship, it has been customary to load the grain directly into a dedicated cargo hold, omitting bagging and packing in order to improve loading efficiency and reduce transportation costs. An unloader is widely used to carry out the grain inside.
As this unloader, as shown in FIG. 6 (a), the grain M is finned via a feeder 111 (FIG. 6 (b)) comprising a feeder, a screw and the like provided with a rotating impeller as a supply unit. A mechanical unloader (also referred to as a “mechanical continuous unloader”) 110 or a grain M is transferred to a hopper 113 after being transferred to a conveyor 112 such as a conveyor and then supplied to a land conveyor 115 via a chute 114. Is sucked by a suction duct 122 to which a negative pressure is applied by a blower 126 via a nozzle 121 as a supply unit, and then transferred to a land conveyor 125 via a rotary feeder 123 and a discharge duct 124. An unloader 120 is used (see, for example, Patent Documents 1 and 2).

In the case of a mechanical unloader, the unloader is provided with a horizontal boom on the main body so as to be able to perform hoisting and turning operations, and a vertical boom is provided at the tip thereof so as to be capable of swinging. A feeder is provided, and during operation, the vertical boom and feeder are inserted into the hold to carry out the grain.
Similarly, in the case of a pneumatic unloader, a boom is arranged on the fuselage so as to be able to move up and down and turn, and a transport pipe (horizontal telescopic pipe and A vertical telescopic tube) is disposed, and a nozzle is disposed at the tip thereof. During operation, the vertical telescopic tube and the nozzle are inserted into the hold to carry out the grain.

JP 2002-234619 A JP-A-6-255798

By the way, since the Great East Japan Earthquake, power facilities including the power plant were damaged, and after the accident at the Fukushima Daiichi nuclear power plant, the domestic nuclear power plant was shut down for safety review. As a result, the industry is widely required to support energy savings. However, the unloader described above may interfere with the handling of cargo during the handling operation, regardless of whether it is a mechanical unloader or a pneumatic unloader. As described above, the above-mentioned requirement is met because the drive is always driven at a constant output state regardless of the unloader operation status, that is, regardless of the presence or absence of the grain to be carried out or the amount of grain to be carried out. It was the present situation that was not accepted.
Specifically, for example, in a pneumatic unloader, the electric motor that drives the blower rotates at a constant speed in accordance with the voltage and frequency of the power supply when cargo handling is started. There was a problem with respect to.

  An object of the present invention is to provide an energy-saving control method for a pneumatic unloader that can achieve energy saving without hindering cargo handling in view of the current state of the conventional unloader.

  In order to achieve the above object, an energy saving control method for a pneumatic unloader according to the present invention includes a transport pipe connected to a suction tank in which a negative pressure by a blower is applied to a boom that enables ups and downs and swiveling operations. In an energy saving control method for a pneumatic unloader that is arranged and sucks grain into a suction tank through the transport pipe, the electric motor that drives the blower is provided with a variable voltage variable frequency device, and during the cargo handling operation, The power supply of the blower is automatically controlled by a variable voltage variable frequency device so that the suction pressure becomes the minimum suction pressure necessary for normal cargo handling.

  In this case, the minimum suction pressure of the blower can be automatically calculated from the pressure loss of the transport pipe corresponding to the boom undulation angle.

  Further, the minimum suction pressure of the blower can be automatically calculated from the type of grain.

  Moreover, when the transport pipe is closed, the suction pressure of the blower and the opening degree of the air intake valve installed on the suction side of the blower can be controlled.

  Further, the suction pressure of the blower can be automatically controlled to the minimum suction pressure capable of sucking the grain during the bottom-carrying handling operation or the idle operation of the blower.

  Further, the speed of the rotary feeder and the carry-out conveyor can be controlled in accordance with the amount of grain supplied from the discharge part of the suction tank.

  Further, the idling operation of the blower can be performed when the air intake valve installed on the suction side of the blower is opened.

  According to the energy-saving control method for a pneumatic unloader of the present invention, the pneumatic unloader includes a variable voltage variable frequency device in the motor that drives the blower, and the suction pressure of the blower is the minimum suction required for normal cargo handling during the cargo handling operation. By automatically controlling the power supply of the blower with a variable voltage variable frequency device so that the pressure becomes equal, specifically, the minimum suction pressure of the blower is automatically calculated from the pressure loss of the transport pipe corresponding to the undulation angle of the boom. By calculating or automatically calculating the minimum suction pressure of the blower from the type of grain, energy saving can be achieved without hindering cargo handling.

  In addition, when the transport pipe is closed, the blower suction pressure and the opening degree of the air intake valve installed on the blower suction side are controlled to prevent the blower from stopping due to a vacuum abnormality. The number of start-ups can be minimized, and the energy saving operation of the blower and the mechanical life of the blower can be extended.

  It is also possible to smoothly return to the cargo handling operation by automatically controlling the suction pressure of the blower to the minimum suction pressure that can suck the grain during the bottom handling operation or the idle operation of the blower. Thus, energy can be saved without hindering cargo handling.

  In addition, energy saving can be achieved by controlling the speed of the rotary feeder and the carry-out conveyor following the amount of grain supplied from the discharge part of the suction tank. And by reducing the light load rotation of the carry-out conveyor, the mechanical life of the rotary feeder and the carry-out conveyor can be extended.

  Further, when the air suction valve installed on the suction side of the blower is opened, the blower is idling so that energy can be saved when the air suction valve that cannot suck the grain is opened.

It is explanatory drawing of the pneumatic unloader which enforces the energy saving control method of the pneumatic unloader of this invention. It is explanatory drawing of the electric circuit of the electric motor which drives the blower of the pneumatic unloader. It is explanatory drawing of the control apparatus of the suction pressure of the blower of the pneumatic unloader. It is a flowchart which shows an example of the operating method of the pneumatic unloader. It is a flowchart which shows an example of the operating method of the pneumatic unloader. It is explanatory drawing of the conventional unloader, (a) is explanatory drawing which shows an unloader typically, (b) is explanatory drawing which shows the feeder of a mechanical unloader.

  Embodiments of a pneumatic unloader energy saving control method according to the present invention will be described below with reference to the drawings.

  1 to 3 show a pneumatic unloader for carrying out the energy saving control method of the pneumatic unloader of the present invention.

[Outline of pneumatic unloader]
As shown in FIG. 1, the pneumatic unloader 1 is provided with a boom 12 in a body 11 so as to be able to move up and down and turn, and the boom 12 can be transported by an expansion tube so as to be capable of horizontal expansion and contraction. A tube 13 (a horizontal telescopic tube 13a having a distal end connected to the trolley 13c traversing the boom 12 and a vertical telescopic tube 13b having a proximal end connected to the trolley 13c) is disposed, and a nozzle 14 serving as a supply unit is provided at the distal end. Each mechanism operates independently, and during operation, the vertical telescopic tube 13b and the nozzle 14 are inserted into the ship's hold so as to carry out the grains contained in the hold. I have to.
Grain is carried out by sucking the grain through a nozzle 14 and a transport pipe 13 and sucking the grain into a suction tank 16 to which a negative pressure is applied by a blower 15 connected to the transport pipe 13.
Then, the grain sucked into the suction tank 16 is carried out from the discharge part of the suction tank 16 to the ground conveyor 19 provided on the land via the rotary feeder 17 and the carry-out conveyor 18.

[Electric circuit of the motor that drives the blower]
As shown in FIG. 2, the electric circuit of the electric motor that drives the blower 15 that applies a negative pressure to the suction tank 16 is configured as follows.
(1) Supply AC three-phase power.
(2) Install a circuit breaker consisting of an earth leakage breaker.
(3) A relay composed of an electromagnetic contactor or the like can be installed to supply power to the variable voltage variable frequency device.
(4) The variable voltage variable frequency device is a device that can arbitrarily control the effective voltage and frequency of the output AC power in a power converter that outputs AC power.
Install harmonic suppression devices such as AC reactors.
It is controlled by a program controller such as PLC.
(5) The current value of the motor is taken into the PLC.

[Blower suction pressure control device]
As shown in FIG. 3, the control device for controlling the suction pressure of the blower 15 is configured as follows.
(1) Install a pressure switch on the suction side of the blower.
(2) The pressure switch is capable of transmitting the degree of vacuum, and is taken into the PLC and always recognized.
Moreover, what can output an alarm contact signal is desirable.
(3) An air intake valve is provided on the suction side of the blower and is opened by a pressure switch alarm signal.
The air intake valve is preferably an electric valve that can be adjusted in opening in addition to opening and closing both ends.
(4) Install a boom undulation angle meter and recognize the inclination of the transport pipe (horizontal telescopic pipe).

[Normal cargo handling operation]
In order to continue stable cargo handling with the pneumatic unloader 1, it is important to minimize the number of times the blower 15 is started.
When the transport pipe 13 is blocked due to the posture of the boom 12 or a rapid increase in the amount of grain suction, the vacuum degree on the suction side of the blower 15 increases to the negative pressure side, and the blower 15 may be stopped due to a vacuum abnormality. . If this is repeated, power consumption at the start of operation and machine life will be affected.

The suction pressure of the blower 15 determines the capacity of the blower 15 so that the rated load can be handled when the undulation angle of the boom 12 is a negative angle.
On the other hand, when the undulation angle of the boom 12 is a positive angle, the horizontal telescopic tube 13a is also a positive angle, the horizontal telescopic tube 13a does not become a suction loss, and the suction pressure of the blower 15 may become excessive.
In addition, when the type of grain changes, if the blower 15 is operated at the rated speed, the cargo handling amount may increase due to differences in bulk density, weight, and the like.
In such a case, an air intake valve (not shown) is provided at an appropriate location on the nozzle 14 or the transport pipe 13 (horizontal telescopic pipe 13a, vertical telescopic pipe 13b) to adjust the amount of outside air sucked.

  If the suction pressure of the blower 15 is controlled to the set pressure and the increase in the negative pressure is suppressed, but the increase in the suction pressure still cannot be suppressed, an air intake valve is installed on the suction side of the blower 15 and the air intake valve is opened. By controlling the degree, it is possible to prevent the blower 15 from being stopped due to a vacuum abnormality of the blower 15 and to enable energy saving operation.

Since the inclination of the transport pipe 13 (horizontal telescopic pipe 13a) changes depending on the angle of the boom 12, the set pressure enables energy-saving operation with the function of automatically controlling to the minimum suction pressure according to the angle of the boom 12. .
By changing the type of grain, the excess air suction amount can adjust the cargo handling amount by suppressing the suction pressure of the blower 15, thereby enabling energy saving operation.
The suction pressure of the blower 15 can be controlled by controlling the rotational speed of the blower 15 below the rated speed.
Thus, by controlling the rotational speed of the blower 15 (controlling it below the rated rotational speed), the power consumption is reduced, and further, the mechanical life of the blower 15 is extended by reducing the number of times the blower 15 is started. Enable.

[Bottom handling operation and blower empty operation]
If grains are accumulated in the hangar, the supply section can be sufficiently inserted into the grains, so that steady cargo handling operation is possible.
On the other hand, if the grain in the hangar becomes small, the supply section cannot be fully inserted into the grain. In such a state, in order to fully insert the supply unit into the grain, a bulltozer or the like is placed in the shed, the grain is scraped from the periphery, and the supply unit is inserted around the supply unit. At this time, if the scraping is delayed, the blower 15 may be idle.
Such a standby state is regarded as a bottom-up operation.

When the grain is being sucked during cargo handling, the suction is sucked near the set suction pressure. However, if there is no grain near the supply section, the blower 15 is idled, and the pressure loss of the transport pipe 13 is reduced. The negative pressure is reduced. This is judged and it shifts to the bottoming operation.
During bottom-up operation, the suction pressure of the blower 15 is controlled to the minimum suction pressure that can suck up the grains.
When the grain is sucked up again, the suction pressure increases to the negative pressure side, so that the normal cargo handling operation is automatically resumed.

[Quantitative loading transport operation]
Even when a change occurs in the supply amount of the supply unit, the number of rotations of the carry-out conveyor can be reduced by holding the carry-out conveyor conveyance amount (grain load amount) at the rated load handling load amount.
During the cargo handling operation, the rotary feeder 17 is operated at a constant speed in order to cut out the rated cargo handling amount.
During normal cargo handling, the supply amount of the supply unit is also stable, so the rotary feeder 17 cuts out the rated amount and sends it to the carry-out conveyor 18.
When the supply tatami of the supply unit is reduced, the amount of grain remaining in the suction tank 16 is small, and the cutting amount of the rotary feeder 17 is also small.
When the cutting amount of the rotary feeder 17 changes, the current value also changes, and the cutting amount to the carry-out conveyor 18 is calculated by monitoring the current value.
The load amount of the carry-out conveyor 18 is made to follow from the cut-out amount of the rotary feeder 17, and the speed is controlled to the rated load-carrying load amount of the carry-out conveyor 18.
By controlling the speed of the carry-out conveyor 18 in response to changes in the supply amount of the supply unit, it is possible to extend the machine life of the carry-out conveyor 18 by reducing power consumption and light load rotation of the carry-out conveyor 18. To do.

[Idling operation]
During the cargo handling operation, the supply section is raised and the boom 12 is moved, such as when changing the suction location in the garage.
In this case, the air intake valve is opened and the blower 15 is operated in a no-load state, so that a slight power consumption reduction effect can be obtained. Here, however, the blower 15 and the transport device ( The rotary feeder 17 and the carry-out conveyor 18) are automatically switched to idling operation.
Here, the idling operation refers to the minimum rotation speed at which the electric motor can be continuously operated.
In this case, the automatic switching is performed based on the determination of the PLC or the like, but it is also possible to provide a manual button and perform the determination based on the operator's determination.
Moreover, if the state of the bottoming operation continues, the grain in the suction tank 16 is exhausted, and the rotary feeder 17 is idled.
The idling operation of the rotary feeder 17 is confirmed by confirming that the current value has become a no-load current for a certain time, and also has a function of switching the rotary feeder 17 and the carry-out conveyor 18 to the idling operation during the bottoming operation.
By performing the idling operation, it is possible to reduce power consumption, reduce the light load rotation of the blower 15 and the conveying device, and extend the life of the machine.

[Operation example of pneumatic unloader]
An example of the operation method of the pneumatic unloader will be described with reference to the flowcharts shown in FIGS.

(1) When the cargo handling operation is started, the idling operation of the transfer device and the blower is started with the air intake valve opened.
When starting the blower, it starts with no load in order to reduce mechanical shock.
In addition, since it takes time to move the boom and the like until the suction is actually started after the cargo handling start operation is performed, the energy saving effect is enhanced by adopting the idling operation.

(2) By closing the air suction valve provided on the suction side of the blower at the operator's discretion, the negative pressure in the suction tank is increased and the suction of the grain is started. (Fig. 4 (1))
At the moment when the air suction valve is closed, the suction pressure of the blower is controlled to the minimum suction pressure that can suck the grain (the minimum suction pressure of the blower that can suck the grain).
This is for automatically discriminating whether the normal cargo handling operation or the bottoming operation is performed.
When the grain is actually sucked, the negative pressure becomes higher than the set value, so it is automatically recognized as normal cargo handling operation.
When the set time elapses when the negative pressure does not increase near the set value, it is automatically recognized as a bottom-up operation.

(3) When it is recognized as normal cargo handling operation, the blower is controlled for normal cargo handling operation. (Fig. 4 (2), Fig. 4 (4))
With respect to the initial setting of the suction pressure of the blower according to the grain type and the boom reference angle, the loss of the horizontal transport pipe is calculated from the current boom angle, the setting value of the suction pressure of the blower is corrected, and the variable voltage of the blower is variable. By controlling the frequency device, energy saving operation is possible by minimizing the blower capacity.
The relationship between the number of rotations of the blower and the suction pressure of the blower is almost proportional, and a proportional expression is stored from the characteristics of the blower.

Only in the first time during the operation, the initial rotational speed of the blower is calculated from the suction pressure setting based on this proportional expression.
Thereafter, the control of the variable voltage variable frequency device of the blower is performed every sampling time. (Fig. 5 (6))
Correction of the differential pressure between the set value of the suction pressure of the blower and the current suction pressure value corrects the rotational speed of the blower from the slope of this proportional expression.
At this time, when moving in the convergence direction from the previous correction control, the gain k may be considered in the correction amount of the rotational speed of the blower.
Here, the blower characteristic proportional expression is used. However, there is a case where the correction amount is registered in the speed correction amount table for the differential pressure (positive and negative sides) and the control is performed based on this table.

(4) If it is recognized that the cargo handling operation is bottoming, the blower is controlled for the cargo handling operation. (Fig. 4 (3))
When the blower idle operation continues for a certain period of time, it shifts to the main operation.
The suction pressure of the blower is controlled to the minimum suction pressure that the grain can suck. (Fig. 5 (7))
This operation is applied not only to the bottom-climbing operation but also to the case where the blower is idling with the atmospheric intake valve closed, such as when the boom is moving.
When the suction of the grain is resumed, the suction pressure of the blower increases and changes to the negative pressure side, so this is automatically recognized and shifts to normal cargo handling.

(5) Regardless of normal cargo handling operation or bottom-climbing operation, the transport device performs a quantitative loading transport control.
If there is grain in the suction tank, operate the rotary feeder at normal speed.
The sampling time is desirably related to a fixed period (within about 1 second) or a cutting period.
The cutting cycle is determined by the rotational speed of the rotary feeder and the number of impellers.
Calculate the fixed loading speed of the carry-out conveyor from the cut-out amount of the rotary feeder, and control the speed. (Fig. 5 (8))
The cutting amount of the rotary feeder is as follows.
Current cutting amount of the rotary feeder = Current value of the current rotary feeder ÷ Current value of the rotary feeder at the rated loading amount × Cutting amount at the rated loading × Machine efficiency Here, the cutting amount of the rotary feeder is the current It is almost proportional to the value, but the machine efficiency is included depending on the machine configuration.
Quantitative loading speed of unloading conveyor = current cutting amount ÷ cutting amount at rated loading x rated loading speed of unloading conveyor x machine efficiency Here, the unloading conveyor's fixed loading speed is almost proportional to the cutting amount of the rotary feeder. However, mechanical efficiency is included depending on the structure of the carry-out conveyor.
If the remaining amount in the suction tank runs out and the rotary feeder runs idle or the blower is crawling, it recognizes that no grain is being transported, and conveys equipment (rotary feeder, unloading conveyor, , Ground conveyor) is shifted to idling operation. (Fig. 4 (5))
When the blower returns to normal handling, or when the suction of grain is resumed, the remaining amount of the suction tank and the current value of the rotary feeder also change, so that it automatically returns to the quantitative loading control.

(6) When loading / unloading is interrupted due to setup, boom long-distance movement, etc. after the start of loading / unloading operation, the blower motor has a large capacity, and there is a risk of shortening the life of the motor if it is frequently turned on and off.
In this case, opening the air intake valve and waiting in idle operation (no-load operation) reduces power consumption, but it includes reactive power such as reduced motor efficiency. Absent.
Here, since the cargo cannot be handled when the atmospheric intake valve is opened, the operation automatically shifts to the idling operation.
When it is ready for loading again and the air intake valve is closed, it automatically returns to normal loading.

  As mentioned above, although the energy saving control method of the pneumatic unloader of the present invention has been described based on the embodiments thereof, the present invention is not limited to the configurations described in the above embodiments, and does not depart from the spirit thereof. The configuration can be changed as appropriate.

  Since the energy saving control method for a pneumatic unloader according to the present invention can save energy without hindering cargo handling, the pneumatic unloader can be widely and suitably used for pneumatic unloaders.

DESCRIPTION OF SYMBOLS 1 Pneumatic unloader 11 Airframe 12 Boom 13 Transport pipe 13a Horizontal expansion pipe 13b Vertical expansion pipe 13c Trolley 14 Nozzle 15 Blower 16 Suction tank 17 Rotary feeder 18 Unloading conveyor 19 Ground conveyor

Claims (7)

  A transport pipe connected to a suction tank that allows negative pressure by a blower to be applied to a boom that enables ups and downs and swiveling motions, and grain is sucked into the suction tank via the transport pipe In the energy-saving control method of the pneumatic unloader, the electric motor that drives the blower is equipped with a variable voltage variable frequency device, and the power supply of the blower is set so that the suction pressure of the blower becomes the minimum suction pressure required for normal cargo handling during the cargo handling operation. An energy-saving control method for a pneumatic unloader, wherein automatic control is performed by a variable voltage variable frequency device.   2. The energy saving control method for a pneumatic unloader according to claim 1, wherein the minimum suction pressure of the blower is automatically calculated from the pressure loss of the transport pipe corresponding to the boom undulation angle.   The energy saving control method for a pneumatic unloader according to claim 1 or 2, wherein the minimum suction pressure of the blower is automatically calculated from the type of grain.   4. The air unloader according to claim 1, wherein the suction pressure of the blower and the opening degree of the air suction valve installed on the suction side of the blower are controlled when the transport pipe is closed. Energy control method.   The blower suction pressure is automatically controlled to a minimum suction pressure capable of sucking grain during a bottom handling operation or an idle operation of the blower. Energy saving control method for pneumatic unloader.   The speed of the rotary feeder and the carry-out conveyor is controlled so as to follow the supply amount of the grain supplied from the discharge part of the suction tank. Energy saving control method for pneumatic unloader.   The energy-saving control of the pneumatic unloader according to claim 1, wherein the blower is idling when the atmospheric intake valve installed on the suction side of the blower is opened. Method.