JP2005112519A - Powder conveying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a powder conveying device capable of reducing the air quantity required to make conveyance while the conveying performance of powder having a high closing characteristic is enhanced and of taking a countermeasure against the dust easily. <P>SOLUTION: The powder conveying device 1 equipped with a pump 11 of uniaxial eccentric screw type and a conduit 12 coupled with the pump 11 for leading the powder sent out of the pump 11 to the specified destination, wherein to the conduit 12, an accompanying gas blow-in means 24 is connected for blowing in the gas accompanying the conveyed powder to the powder conveying direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a powder transfer apparatus, and more particularly to an apparatus suitable for transferring powder having extremely high adhesion and high blocking properties.

  As a method of transferring powder, an air transport method of transferring powder using air supplied in large quantities by a blower is often used, but in this method, when separating powder and air at the transfer destination, Since it is necessary to clean a large amount of dust-containing air and release it to the atmosphere, it is necessary to install a cyclone and a large bag filter. In a transfer system that also requires a small amount of powder to be transferred, it is generally difficult to make an automatic device. Therefore, after weighing manually, the carriage is often transferred manually. It is also possible to transfer a small amount of powder by the above-mentioned pneumatic transportation system for large-scale transportation. However, the power cost of the blower, the cost of the filter cloth for dust countermeasures and its maintenance are compared with the amount of transportation. There is a problem that a large cost is required for such as.

On the other hand, as a device for transferring powder, a single shaft eccentric screw pump that sucks and sends powder by rotation of an eccentric rotor provided in the stator as a device that enables even a small amount of quantitative transfer, and the single shaft eccentric screw pump. 2. Description of the Related Art There is known a powder transfer device that is connected and has a pipe that guides a powder sent from the uniaxial eccentric screw pump to a predetermined destination (for example, Patent Document 1 and Patent Document 2). Also known is a powder transfer device in which the powder transfer device is further improved and a wire connected to an eccentric rotor is extended in the transfer pipe so that the powder is less likely to be blocked in the pipe. (Patent Document 3).
No. 7-3031 No. 7-48587 JP 2001-151346 A

  However, for powders with very strong adhesion and high blockage, for example, powders such as slaked lime prepared under certain conditions, the eccentricity of a uniaxial eccentric screw pump as disclosed in Patent Document 3 above is used. The improved structure in which the wire is connected to the rotor and the wire is simply extended into the transfer pipe is not sufficient to prevent the powder from clogging, and is short in actual transfer, especially when trying to transfer a small amount. There may be a situation where the blockage occurs in time and the transfer becomes impossible. Accordingly, the apparatus disclosed in Patent Document 3 is also difficult to apply, particularly for the transfer of a small amount of powder that is extremely adherent and highly occlusive.

  Therefore, the problem of the present invention is that the powder transfer device using the uniaxial eccentric screw pump focuses on the excellent quantitative transfer performance that can be exhibited even when transferring a small amount, such as slaked lime prepared under certain conditions. An object of the present invention is to provide a powder transfer apparatus capable of performing stable transfer for a long time without clogging, particularly stable automatic transfer, even when transferring powder having extremely high adhesion and high blocking properties.

  Another object of the present invention is to improve the transportability of the powder having a high blocking property as described above, while reducing the amount of air necessary for the transport, and to easily take measures against dust. It is to provide a transfer device.

  In order to solve the above problems, a powder transfer device according to the present invention is connected to a single-shaft eccentric screw pump that sucks and sends powder by rotation of an eccentric rotor provided in a stator, and the single-shaft eccentric screw pump. In the powder transfer device having a pipe for guiding the powder fed from the uniaxial eccentric screw pump to a predetermined destination, the entrained gas is blown into the pipe in the direction of the powder transfer. It consists of what is characterized by connecting the gas blowing means. That is, the powder delivered from the uniaxial eccentric screw pump is stably transferred to a predetermined destination over the entire length of the pipe without causing any trouble-causing adhesion and without causing clogging in the pipe. Thus, the desired fluidity is imparted by the gas blown by the accompanying gas blowing means.

  In this powder transfer device, one end of the powder transfer device is connected to the outlet side end of the eccentric rotor so as to be able to rotate synchronously with the eccentric rotor, and a wire extending substantially over the entire length of the pipe is loosely fitted. Preferably it is. By providing such a wire, adhesion of powder to the inner surface of the pipe is prevented or reduced, and if the wire, the rotor connected to it, or the casing in contact with it is grounded, Occurrence can also be suppressed, and it becomes possible to prevent the adhesion of powder even better.

  The uniaxial eccentric screw pump has first fluidity imparting gas blowing means for blowing a gas for imparting fluidity to the powder on the inlet side, and imparts fluidity to the powder on the outlet side. Therefore, the second fluidity imparting gas blowing means for blowing the gas for the purpose may be used. These fluidity imparting gas blowing means constitute means different from the entrained gas blowing means in the present invention. The first fluidity imparting gas blowing means imparts fluidity to the powder on the inlet side of the uniaxial eccentric screw pump to prevent clogging, and the second fluidity imparting gas blowing means prevents the uniaxial eccentric screw pump from exiting. On the side, the powder is given fluidity to prevent clogging. That is, the powder is reliably prevented from being blocked before and after the uniaxial eccentric screw pump, and first, a stable supply of a predetermined amount of the powder into the pipe is ensured.

  Moreover, in the powder transfer apparatus according to the present invention, it is preferable that a pressure detection means for detecting the pressure in the pipe is provided at the uniaxial eccentric screw pump outlet side portion of the pipe. That is, whether or not the powder can be stably transferred in the pipe after this part depends on the pressure at the outlet side of the uniaxial eccentric screw pump, which is the starting end of the pipe, in order to ensure the fluidity of the powder thereafter. Depending on whether or not the pressure corresponds to the amount of gas, it can be determined by pressure detection at this portion. Therefore, it is more preferable to provide means for controlling the amount of gas blown by the accompanying gas blowing means to an optimum amount in accordance with the pressure detected by the pressure detecting means.

  Further, gas blowing by the accompanying gas blowing means can be performed intermittently. For example, if the pressure in the pipe is detected by the pressure detection means as described above and it can be determined whether or not the amount of blown gas is appropriate, the gas is blown only when the amount of blown gas is likely to be insufficient. Is possible. Intermittent gas blowing makes it possible to minimize the amount of air used for transfer as compared to continuous blowing, and facilitates measures against dust at the transfer destination.

  It is also possible to constantly perform a small amount of gas blowing by the accompanying gas blowing means and to intermittently increase the amount of the blowing gas. When it is detected that there is a risk of adhesion or clogging in the piping for some reason by securing the minimum amount of blowing gas required to ensure fluidity in the piping by a small amount of gas blowing performed constantly. In this case, the danger is eliminated by increasing the amount of blown gas intermittently. Even by controlling the amount of blown gas, it is possible to keep the amount of air used for the transfer small compared to the case where a relatively large amount of blown gas is constantly maintained while maintaining stable transfer. Become.

  The powder transfer device according to the present invention is particularly suitable for transfer of powder having extremely high adhesion and high blocking properties, and in particular for transferring small amounts. As a representative example of such extremely adherent and highly occlusive powder, slaked lime prepared under certain conditions, that is, prepared under conditions that are extremely adherent and highly occlusive. be able to. However, the powder targeted in the present invention is not limited to slaked lime.

  As described above, according to the powder transfer device of the present invention, even when a small amount of highly adherent and highly occlusive powder is transferred, the powder is stably transferred for a long time without causing clogging. be able to. In addition, by appropriately controlling or operating the gas blowing by the accompanying gas blowing means, it is possible to achieve stable transfer with a small amount of gas blowing, and it is possible to easily take measures against dust at the transfer destination.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a powder transfer apparatus 1 according to an embodiment of the present invention. In this embodiment, the powder 3 stored in the silo 2 is transferred to a powder receiving tank 4 as a predetermined destination using the powder transfer device 1. The powder 3 stored in the silo 2 is discharged to the lower dispensing hopper 7 by the discharger 6 provided at the lower part of the silo 2 with the gate valve 5 opened. The dispensing hopper 7 is provided with a powder level meter 8, and the opening / closing of the gate valve 5 and the operation of the discharger 6 are controlled based on a signal from the powder level meter 8. Further, the dispensing hopper 7 is provided with a bridge breaker 9 of the type for generating vibration on the inner plate for preventing bridging. The bridge breaker 9 is actuated once every few minutes, for example, to prevent the formation of bridges and rat holes in the dispensing hopper 7, and is particularly effective for powders that are highly adherent and difficult to transfer. To work. Further, the dispensing hopper 7 is provided with a discharge feeder 10 for smooth suction of a uniaxial eccentric screw pump described below.

  The powder transfer device 1 includes a uniaxial eccentric screw pump 11 and a pipe 12 that is connected to the uniaxial eccentric screw pump 11 and guides the powder fed from the uniaxial eccentric screw pump 11 to the powder receiving tank 4. ing. The pipe 12 may be a fixed pipe or a flexible pipe. The uniaxial eccentric screw pump 11 includes a female screw type stator 13 and a male screw type eccentric rotor 14 that is rotatably fitted in the stator 13, and is attached to a rotary shaft 16 that is driven to rotate by a drive motor 15. The eccentric rotor 14 connected via a universal joint or the like is rotated in the stator 13 to suck in the powder on the inlet side, feed the uniaxial eccentric screw pump 11 and send it out to the outlet side. Reference numeral 17 denotes a plate blade that feeds surrounding powder toward the inlet side of the uniaxial eccentric screw pump 11 when the rotary shaft 16 is rotated. The pipe 12 is grounded or has an antistatic function in order to suppress adhesion of powder. A wire 18 extending over the entire length is loosely fitted in the pipe 12. One end of the wire 18 is connected to the outlet side end of the eccentric rotor 14 of the uniaxial eccentric screw pump 11 so as to be able to rotate synchronously with the eccentric rotor 14. As the eccentric rotor 14 rotates, the wire 18 is rotated in a flexible state in the pipe 12 to mechanically prevent the powder from adhering to the inner surface of the pipe 12 and blocking in the pipe 12. The wire 18 is grounded via the wire 18 itself or the eccentric rotor 14 to which the wire 18 is connected, and further via the stator 13 and the casing, thereby suppressing the generation of static electricity and providing an antistatic function. The body can be prevented from adhering to the inner surface of the pipe 12 and from being blocked in the pipe 12. The other end of the wire 18 protrudes slightly (for example, about 10 cm) from the outlet end of the pipe 12 on the powder receiving tank 4 side, and can more reliably prevent adhesion and blockage at the pipe outlet. Yes.

  On the inlet side (suction side) of the uniaxial eccentric screw pump 11, a gas supply pipe 19 as a first fluidity imparting gas blowing means for blowing a gas for imparting fluidity to the sucked powder is provided as an on-off valve. 20 is connected. The gas injected by the gas supply pipe 19 imparts fluidity so that the powder in the suction portion of the uniaxial eccentric screw pump 11 is smoothly sucked, and the gas used for imparting fluidity. Most of the liquid flows out from the dispensing hopper 7 side, and a small amount is sucked into the uniaxial eccentric screw pump 11. Therefore, in order to impart fluidity to the powder immediately after being discharged from the uniaxial eccentric screw pump 11 so as not to be clogged, the discharged powder is disposed on the outlet side (discharge side) of the uniaxial eccentric screw pump 11. A gas supply pipe 21 as a second fluidity imparting gas blowing means for blowing a gas for imparting fluidity to the body is connected via an on-off valve 22. In this embodiment, air, particularly dry air, is used as the gas supplied by the gas supply pipes 19 and 21. Hereinafter, the air supplied by the gas supply pipe 21 may be referred to as end air. In this embodiment, the gas supply pipe 21 is connected to a reducer-like tapered pipe 23 used for connection to the pipe 12 on the outlet side of the uniaxial eccentric screw pump 11. If the amount of air supplied by the gas supply pipe 21 is too large, the component in the direction of stopping the powder discharged from the uniaxial eccentric screw pump 11 becomes too strong. It is not possible to supply a very large amount, and it is necessary to keep the amount necessary to give fluidity to the discharged powder.

  In the powder transfer apparatus 1 as described above, in the present invention, the entrained gas blowing means 24 for blowing the gas accompanying the transferred powder in the powder transfer direction is connected to the pipe 12. The accompanying gas blowing means 24 has a gas supply pipe 25 connected to the pipe 12, and the gas supply pipe 25 blows the accompanying gas into the pipe 12 toward the powder transfer direction. It is inclined and connected. As this accompanying gas, dry air is used in this embodiment. After the air compressed by the compressor 26 is dehumidified by the dehumidifier 27, the dry air is temporarily stored in the air storage tank 28 and is supplied into the pipe 12 as entrained air via the air supply line 29. The air supply line 29 is provided with a flow control valve 30 so that the amount of entrained air supplied into the pipe 12 can be controlled. In the present embodiment, a pressure gauge 31 as a pressure detecting means for detecting the pressure in the pipe 12 is provided at the outlet side portion of the uniaxial eccentric screw pump 11 of the pipe 12 at the portion of the reducer-like taper pipe 23. ing. That is, the pressure gauge 31 can detect the pressure in the pipe 12 after supplying the end air. In the present embodiment, the amount of entrained air can be controlled by the flow control valve 30 in accordance with the pressure detected by the pressure gauge 31. The control of the entrained air amount by the flow rate control valve 30 can be performed by manually sending a control signal to the flow rate control valve 30 by looking at the detection value of the pressure gauge 31, or according to the detection signal of the pressure gauge 31. The flow control valve 30 can also be controlled automatically. For example, when the pressure detected by the pressure gauge 31 is equal to or higher than a preset pressure, the flow control valve 30 is opened to supply a predetermined amount of accompanying air, as well as a constant amount of accompanying air. If the pressure detected by the pressure gauge 31 is equal to or higher than a preset pressure, a method of intermittently increasing the amount of entrained air to be blown can be employed. In the present embodiment, the dry air from the air storage tank 28 is also used as a gas to be blown to impart fluidity on the inlet side and the outlet side of the uniaxial eccentric screw pump 11 described above. For this purpose, the dry air is fed through an air supply line 32 branched from the air supply line 29.

  The powder transfer apparatus 1 according to the present embodiment configured as described above is particularly suitable for transferring powder having high adhesion and high blocking properties. As described above, a structure in which a wire extending into a pipe is connected to an eccentric rotor of a uniaxial eccentric screw pump has been conventionally known, and prevention of powder adhesion in the pipe by preventing rotation and electrification of this wire. Although it is effective, it is extremely adherent and highly occluded powder, typically some types of slaked lime produced by a certain preparation method, prevent adhesion in the piping and the resulting occlusion. There are times when it cannot be done. In such a case, by flowing entrained gas (in the above embodiment, dry air) into the pipe 12 in the powder transfer direction, fluidity can be appropriately imparted to the powder transferred through the pipe 12. By cooperating with the wire 18, it becomes possible to reliably prevent the occurrence of adhesion and blockage in the pipe 12. In particular, by appropriately controlling the amount of entrained gas blown in accordance with the pressure detected by the pressure gauge 31, smooth powder transfer that prevents adhesion and blockage while appropriately controlling the amount of entrained gas supplied. Can be realized.

  The following demonstration test was performed on the excellent powder transfer performance of the powder transfer apparatus 1 as described above using slaked lime having extremely high adhesion and high blockage as powder. The used slaked lime is difficult to handle and transfer with conventional uniaxial eccentric screw pumps, and can hardly be used practically for small-volume transfer with small-diameter pipes. It is slaked lime that was forced to be sent with a large amount of air by a pneumatic transport system using a blower. Such slaked lime is troublesome and very difficult to handle even if it is transported by a pneumatic transport system using a blower. In particular, in the case of a small amount of transportation, for example, about 100 to 200 kg / h, blockage occurred in the piping due to adhesion in a short time.

  Using slaked lime with extremely strong adhesion and high blocking properties as described above, dehydrated dry air having a dew point of −30 ° C. is used as the air supplied through the gas supply lines 29 and 32, and the diameter of the pipe 12 The transfer test was performed under the conditions of 25A, the rotational speed of the uniaxial eccentric screw pump 11 is 150 rpm, the slaked lime transfer amount is 180 kg / h, the end air amount is 2000 L / h, and the accompanying air amount is 2000 L / h. As a result, the piping was blocked 55 minutes after the start of transfer, and the operation was stopped when the pressure detected by the pressure gauge 31 increased to 90 kPa. In this test, the pressure detected by the pressure gauge 31 is about 35 kPa for about 10 minutes after the start of operation, then increases to 35 to 55 kPa in the next 10 minutes, once decreases to about 30 kPa, and again 50 to 60 kPa. 3 times, and suddenly increased from 75 kPa to 90 kPa within 5 minutes after the start of operation, and the powder ( Judging from the fact that the discharge of slaked lime was not observed, it was judged as a blockage and the operation was terminated.

  From the above test results, it can be determined that the amount of entrained air is small under the above operating conditions, so the amount of entrained air was increased to 5000 L / h, and the others were tested under the same conditions. As a result, the range of 25 to 45 kPa was about 5 to 10 minutes. The transfer continued smoothly while repeating the pressure fluctuation in the period of. Since there was no change in this situation, the operation under this condition was discontinued in 3 hours.

  On the other hand, in the above test, a test in which the dew point of the supplied dry air was changed to −15 ° C. was performed under the same conditions as the operation in which the amount of the entrained air was increased to 5000 L / h. It was seen. From this result, it was found that -15 ° C. is not sufficient as the degree of dehumidification at the dew point of dry air, and it is preferable to use dry air having a dew point of about −30 ° C. as described above.

  From the above test results, it was confirmed that the entrained air amount of 2000 L / h was not always sufficient, and if it was always set to 5000 L / h, it was confirmed that stable and good transfer could be continued. Whether or not the amount of air could not be reduced was investigated as follows in relation to the pressure detected by the pressure gauge 31. That is, for the purpose of reducing the amount of entrained air, from the test results of the entrained air amount of 2000 L / h and the entrained air amount of 5000 L / h, the dangerous pressure when the pressure increases is set to 40 kPa, and the accompanying entrained air that is constantly supplied When the pressure reaches 40 kPa, the amount of entrained air is increased to 5000 L / h when the pressure reaches 40 kPa, and the pressure is reduced to 25 kPa until the pressure decreases to 25 kPa. At that time, the increase was stopped and the control was returned to the base 2000 L / h. As a result, even if the operation was continued for 3 hours, the transfer could be continued smoothly without any problem. The time required for the pressure to drop from 40 kPa to 25 kPa is about 5 seconds. With this operation method, it was possible to significantly reduce the amount of entrained air compared to the operation condition of 5000 L / h at all times.

  In the above operation, the frequency at which the outlet pressure of the uniaxial eccentric screw pump 11 becomes 40 kPa or more appears once every 5 to 10 minutes. Therefore, if it is calculated that the entrained air amount is increased from 2000 L / h to 5000 L / h once every 7.5 minutes, the entrained air amount only needs to be increased by 40 times for a total of 40 seconds. It will be. As a result, the amount of entrained air can be reduced to 1/90 as compared with the case where the amount of entrained air is always 5000 L / h. With such a small amount of entrained air, a small amount of powder can be transferred with a small-diameter pipe. It will be possible to continue stably.

  Further, in the powder transfer device according to the present invention, the amount of air (gas) used as a whole is much smaller than that of a conventional pneumatic transport method using a blower. For example, in the conventional pneumatic transportation method, when the powder is sent only by the air flow rate, the wind speed in the pipe is about 15 m / s. Therefore, in the powder transfer device according to the present invention, the end air amount is 2000 L / h. Even if it adds, when entrained air quantity is 5000 L / h, it will become 5 m / s or less as a wind speed in piping, and it is remarkably small. When the accompanying air amount is 2000 L / h, the value becomes even lower. Therefore, compared with the conventional pneumatic transportation method, the amount of air used can be greatly reduced, the capacity of the air source equipment can be reduced and the size can be reduced, and the dust countermeasure equipment at the destination can be downsized. Simplification can be achieved.

  In addition, a powder that has been extremely difficult to transfer in the past, such as the above-mentioned slaked lime, which is extremely adherent and highly occlusive, can be stably used in a small amount while utilizing the quantitative property of the uniaxial eccentric screw pump 11. Smooth transfer is possible. In addition, since a small amount of stable transfer is possible, even when stirring and mixing at the transfer destination or when the slurry is dissolved, those operations can be continued, and the product is transferred by transferring the powder. It is possible to automate the operation of any device that is made. Furthermore, since a small amount of powder can be transferred continuously and the apparatus can be downsized, the cost of the entire equipment including the post-process can be greatly reduced.

  As described above, the powder transfer apparatus according to the present invention is particularly suitable for transferring a small amount of powder having extremely high adhesion and high blocking properties, but can transfer several hundred kg to several tons or more per hour. It is also possible to configure a device using a large uniaxial eccentric screw pump, and excellent transfer performance can be expected as described above.

  The powder transfer device according to the present invention can be suitably applied particularly to a small amount transfer of powder having extremely high adhesion and high blockage like certain types of slaked lime. However, since such a small amount of powder can be stably transferred in a small amount, it is practically applicable to transfer of any other powder.

It is a schematic equipment system diagram of a powder transfer device concerning one embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Powder transfer apparatus 2 Silo 3 Powder 4 Powder receiving tank 4 as a predetermined destination
DESCRIPTION OF SYMBOLS 5 Gate valve 6 Discharge machine 7 Dispensing hopper 8 Powder level meter 9 Bridge breaker 10 Discharge feeder 11 Uniaxial eccentric screw pump 12 Piping 13 Female screw type stator 14 Male screw type eccentric rotor 15 Drive motor 16 Rotating shaft 17 Plate blade 18 Wire 19 1 Gas supply pipe as fluidity imparting gas blowing means 20, 22 Open / close valve 21 Gas supply pipe as second fluidity imparting gas blowing means 23 Reducer-shaped taper pipe 24 Entrained gas blowing means 25 Gas supply pipe 26 Compression Machine 27 Dehumidifier 28 Air storage tank 29, 32 Air supply line 30 Flow control valve 31 Pressure gauge as pressure detection means

Claims (9)

  A uniaxial eccentric screw pump that sucks and feeds powder by the rotation of an eccentric rotor provided in the stator, and is connected to the uniaxial eccentric screw pump, and the powder fed from the uniaxial eccentric screw pump is sent to a predetermined destination. In the powder transfer apparatus having a pipe for guiding, a powder transfer apparatus characterized in that entrained gas blowing means for blowing a gas accompanying the transferred powder in the powder transfer direction is connected to the pipe.   The powder according to claim 1, wherein one end of the pipe is connected to an outlet side end of the eccentric rotor so as to be able to rotate synchronously with the eccentric rotor, and a wire extending substantially over the entire length of the pipe is loosely fitted. Transfer device.   The uniaxial eccentric screw pump has first fluidity imparting gas blowing means for blowing a gas for imparting fluidity to the powder on the inlet side, and for imparting fluidity to the powder on the outlet side. The powder transfer apparatus according to claim 1 or 2, further comprising a second fluidity imparting gas blowing means for blowing gas.   The powder transfer device according to any one of claims 1 to 3, wherein a pressure detection means for detecting a pressure in the pipe is provided at a portion of the pipe on the outlet side of the uniaxial eccentric screw pump.   The powder transfer apparatus according to claim 4, wherein means for controlling the amount of gas blown by the accompanying gas blowing means is provided in accordance with the pressure detected by the pressure detecting means.   The powder transfer apparatus according to any one of claims 1 to 5, wherein gas blowing by the accompanying gas blowing means is performed intermittently.   The powder transfer apparatus according to any one of claims 1 to 5, wherein a small amount of gas is constantly blown by the accompanying gas blowing means, and the amount of blown gas is intermittently increased.   The powder transfer apparatus according to any one of claims 1 to 7, wherein dry air is used as the gas blown by the accompanying gas blowing means.   The powder transfer apparatus in any one of Claims 1-8 whose powder to be transferred is slaked lime.

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