CA1179398A - Device for pneumatic conveying of loose material - Google Patents
Device for pneumatic conveying of loose materialInfo
- Publication number
- CA1179398A CA1179398A CA000387147A CA387147A CA1179398A CA 1179398 A CA1179398 A CA 1179398A CA 000387147 A CA000387147 A CA 000387147A CA 387147 A CA387147 A CA 387147A CA 1179398 A CA1179398 A CA 1179398A
- Authority
- CA
- Canada
- Prior art keywords
- pressure
- conveying
- conduit
- medium
- control unit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
- B65G53/00—Conveying materials in bulk through troughs, pipes or tubes by floating the materials or by flow of gas, liquid or foam
- B65G53/34—Details
- B65G53/52—Adaptations of pipes or tubes
- B65G53/521—Adaptations of pipes or tubes means for preventing the accumulation or for removal of deposits
Abstract
ABSTRACT OF THE DISCLOSURE
A primary pneumatic conveying conduit for trans-porting loose material is provided with consecutive groups of connection points connected via electrically controlled valves to a secondary line for an auxiliary pressure medium.
Upstream and downstream of each group of connection points are arranged pressure sensors in the form of electrical pres-sure transducers; a programmable electronic control unit has its inputs connected to respective pressure transducers and its outputs to respective valves for controlling the latter in response to differences between stored reference signals corresponding to desired parameters of the conveying opera-tion and the input signals.
(212) 687-5068
A primary pneumatic conveying conduit for trans-porting loose material is provided with consecutive groups of connection points connected via electrically controlled valves to a secondary line for an auxiliary pressure medium.
Upstream and downstream of each group of connection points are arranged pressure sensors in the form of electrical pres-sure transducers; a programmable electronic control unit has its inputs connected to respective pressure transducers and its outputs to respective valves for controlling the latter in response to differences between stored reference signals corresponding to desired parameters of the conveying opera-tion and the input signals.
(212) 687-5068
Description
~i7~
BACKGROUND OF THE INVENTION
.. _ _ The present invention relates in general to pneumatic conveyors for loose material, and in particular to a conveying device of the type having a primary conveying conduit and a secondary pressure-medium sonduit extending . parallel to the primary conduit, a plurality of electrically controllable valves distributed al~ng the conveying path and connected to the primary conveyinCJ conduit and a plurality ~f pressure sensors arranged at intervals alony the primary conauit for controlling the actuation of the valves.
. A proposal for a conveyi~g device of this kind is known from literature ~VerfahreIlstechnik 12, 1978, 4, p. 200, FIG. 12). It includes a conveying conduit and the medium supply auxiliary conduit extending parallel to the conveying conduit and communicating therewith so as to supply into a section of the main conveying conduit a pressure medium when the pressure drop in thi5 section falls below an adjustable limit. For thl.s purpose, the main conveying pipe is provided ith a series of spaced diaphragms each acting by means of a . piston on a common balance linkage. At the same time, tne . piston is designed as a valve and arranged upstream of the section so that, upon overcoming a certain nominal value of the differential pressure set by a spring, a tap line is opened connecting the auxiliary conduit for the pressure ' _~_ 11'79;39~ ~
1 ¦medium wi~h several pressure air feeding connections in the ¦main conveying conduit.
¦ This proposed solution, however, due to its ¦mechanical complexity, contradicts the requirement for an ¦economical and simple design of the conveying devices of this ¦type. In addition, the disadvantage of SUC}l prior-art device ¦is that the springs for sett~ng the nominal value of the ¦-differential pressure must be excessively biased to avoid ¦valve flutter at small pressure variationsO In order to ¦counteract this high bias by mechanically s~ns~d differen-¦tial pressure, the employed diaphragm must have correspond-¦ingly increased surface to meet the equation: force equals ¦pressure times surface. ~o meet ~his requirement, the pressure-sensing and pressure-transmitting elements are is bulky and consequently expensive. For conveying conduits up to 80 mm in di~meter, such bulky sensing and transmitting el2ments would be excessively large because the large-area diaphragms could not match the curvature of the conveying pipe r Such large-area diaphragms, moreover, are sensitive to pressure impulses and to wear caused by the flow of solid particles. -Furthermore, the large-area diaphragms require correspondingly large cut-outs in the conveying conduit, which may cause deposits of solid particles in the diaphragm and! in a prolon~ed operation may unfavorably influence the func-tion of the pressure sensors.
13~'7~
Another prior-art conveying device of this kind is known from the German patent 1,781,025 (Waeschle) dated August 10, 1968, disclosing a pneumatic conveying conduit with a parallel pressure-medium auxiliary conduit from which through controllable valves additional conveying medium is supplied into the main condui-t. The latter conduit is provided with measuring means assigned to respective valves for generating signals which control the valves. The obiect-ive of this known pneumatic conveyor is to move the loose material through the main conveying conduit in batches separated by conveying medium cushions. To prevent inter-action between the batches oE loose material, the additional pressure medium is injected along the conveying path into respeckive cushions of conveying medium between the batches.
The measuring points operating on the principle of light barriers merely detect whether, at the point of the additional feeding of conveying medium, a batch of loose material or the pressure medium cushion take place.
From the German publication 20 22 962 (Kanics~ filed May 12, 1970, a further conveying device of this kind is known having a primary conveying conduit and a parallel pressure-medium secondary conduit from which via valves additional conveying medium is fed into the primary conduit. The objective of ~his prior-art device is to equalize pressure drQps along the conveying path. Due to the fact that the feed-in valves in this known device are not controllable, there is no way to determine how much additional conveying medium should be supplied into the individual sections of the primary conveying conduit. For the same reason, it cannot be determined in advance how to change the pressure gradient by feeding in the additional pressure medlum.
From the German publication 2 219 199 ~Hahn) filed April 20, 1979, it is also known to provide a pneumatic conveyor having a primary conveying conduit and controllable valves for feeding the pressure medium from the auxiliary conduit into the primary conduit. The valves are connected to the auxiliary conduit and cause a definite pressure drop in the latter along the feeding path. The objective of this solution is to achieve a batchwise transportation of loose material with an automatic regulation of feeding of auxiliary air in the case of conveying disturbances. A serious disadvantage of this known conveying device is that the additional conveying medium is supplied from the auxiliary pressure-medium conduit only at the end of the primary conveying conduit when the pressure medium has been blown at the inlet of the latter up to the feed-in point in question.
Thereore this solution means an unnecessarily high consump-tion of pressurized air, and thus uneconomical operation, as well as delayed dissolution of batches in the primary conveying conduit.
From the German publication 2 305 030 (Krambrock) filed February 2, 1973, it is also known to provide a ~ 5 -'3;~
pneumatic conveying device of this kind in which additional conveying medium from an auxiliary conduit flows in the primary conveying conduit. In this prior-art device, at a point where pressure in the auxiliary medium supply line exceeds the pressure in the main conveying conduit when considered in the direction of flow, the auxiliary conduit is closed and additional pressure medium is supplied at this point from the auxiliary line in the main conveying line. A
disadvantage of this known conveying device ls its limitation to a single feed-in point only for applyiny the auxiliary pressure medium into the entire length of the conveying conduit. This single feeding point is insuf~icient for a trouble-free and energy-saving operation of -the pneumatic conveyor.
From the German published patent application
BACKGROUND OF THE INVENTION
.. _ _ The present invention relates in general to pneumatic conveyors for loose material, and in particular to a conveying device of the type having a primary conveying conduit and a secondary pressure-medium sonduit extending . parallel to the primary conduit, a plurality of electrically controllable valves distributed al~ng the conveying path and connected to the primary conveyinCJ conduit and a plurality ~f pressure sensors arranged at intervals alony the primary conauit for controlling the actuation of the valves.
. A proposal for a conveyi~g device of this kind is known from literature ~VerfahreIlstechnik 12, 1978, 4, p. 200, FIG. 12). It includes a conveying conduit and the medium supply auxiliary conduit extending parallel to the conveying conduit and communicating therewith so as to supply into a section of the main conveying conduit a pressure medium when the pressure drop in thi5 section falls below an adjustable limit. For thl.s purpose, the main conveying pipe is provided ith a series of spaced diaphragms each acting by means of a . piston on a common balance linkage. At the same time, tne . piston is designed as a valve and arranged upstream of the section so that, upon overcoming a certain nominal value of the differential pressure set by a spring, a tap line is opened connecting the auxiliary conduit for the pressure ' _~_ 11'79;39~ ~
1 ¦medium wi~h several pressure air feeding connections in the ¦main conveying conduit.
¦ This proposed solution, however, due to its ¦mechanical complexity, contradicts the requirement for an ¦economical and simple design of the conveying devices of this ¦type. In addition, the disadvantage of SUC}l prior-art device ¦is that the springs for sett~ng the nominal value of the ¦-differential pressure must be excessively biased to avoid ¦valve flutter at small pressure variationsO In order to ¦counteract this high bias by mechanically s~ns~d differen-¦tial pressure, the employed diaphragm must have correspond-¦ingly increased surface to meet the equation: force equals ¦pressure times surface. ~o meet ~his requirement, the pressure-sensing and pressure-transmitting elements are is bulky and consequently expensive. For conveying conduits up to 80 mm in di~meter, such bulky sensing and transmitting el2ments would be excessively large because the large-area diaphragms could not match the curvature of the conveying pipe r Such large-area diaphragms, moreover, are sensitive to pressure impulses and to wear caused by the flow of solid particles. -Furthermore, the large-area diaphragms require correspondingly large cut-outs in the conveying conduit, which may cause deposits of solid particles in the diaphragm and! in a prolon~ed operation may unfavorably influence the func-tion of the pressure sensors.
13~'7~
Another prior-art conveying device of this kind is known from the German patent 1,781,025 (Waeschle) dated August 10, 1968, disclosing a pneumatic conveying conduit with a parallel pressure-medium auxiliary conduit from which through controllable valves additional conveying medium is supplied into the main condui-t. The latter conduit is provided with measuring means assigned to respective valves for generating signals which control the valves. The obiect-ive of this known pneumatic conveyor is to move the loose material through the main conveying conduit in batches separated by conveying medium cushions. To prevent inter-action between the batches oE loose material, the additional pressure medium is injected along the conveying path into respeckive cushions of conveying medium between the batches.
The measuring points operating on the principle of light barriers merely detect whether, at the point of the additional feeding of conveying medium, a batch of loose material or the pressure medium cushion take place.
From the German publication 20 22 962 (Kanics~ filed May 12, 1970, a further conveying device of this kind is known having a primary conveying conduit and a parallel pressure-medium secondary conduit from which via valves additional conveying medium is fed into the primary conduit. The objective of ~his prior-art device is to equalize pressure drQps along the conveying path. Due to the fact that the feed-in valves in this known device are not controllable, there is no way to determine how much additional conveying medium should be supplied into the individual sections of the primary conveying conduit. For the same reason, it cannot be determined in advance how to change the pressure gradient by feeding in the additional pressure medlum.
From the German publication 2 219 199 ~Hahn) filed April 20, 1979, it is also known to provide a pneumatic conveyor having a primary conveying conduit and controllable valves for feeding the pressure medium from the auxiliary conduit into the primary conduit. The valves are connected to the auxiliary conduit and cause a definite pressure drop in the latter along the feeding path. The objective of this solution is to achieve a batchwise transportation of loose material with an automatic regulation of feeding of auxiliary air in the case of conveying disturbances. A serious disadvantage of this known conveying device is that the additional conveying medium is supplied from the auxiliary pressure-medium conduit only at the end of the primary conveying conduit when the pressure medium has been blown at the inlet of the latter up to the feed-in point in question.
Thereore this solution means an unnecessarily high consump-tion of pressurized air, and thus uneconomical operation, as well as delayed dissolution of batches in the primary conveying conduit.
From the German publication 2 305 030 (Krambrock) filed February 2, 1973, it is also known to provide a ~ 5 -'3;~
pneumatic conveying device of this kind in which additional conveying medium from an auxiliary conduit flows in the primary conveying conduit. In this prior-art device, at a point where pressure in the auxiliary medium supply line exceeds the pressure in the main conveying conduit when considered in the direction of flow, the auxiliary conduit is closed and additional pressure medium is supplied at this point from the auxiliary line in the main conveying line. A
disadvantage of this known conveying device ls its limitation to a single feed-in point only for applyiny the auxiliary pressure medium into the entire length of the conveying conduit. This single feeding point is insuf~icient for a trouble-free and energy-saving operation of -the pneumatic conveyor.
From the German published patent application
2 403 533 (Waeschle et al) Eiled January ~5, 1974, a further pnPumatic conveyor with a primary conveying conduit and a parallel auxiliary medium-supplying line is ~nown, in which the auxiliary pressure medium is fed through valves. The flow of the auxiliary pressure medium is controlled in such a manner that, when considered in the direction of flow, the first valve introduces an impulse of pressure air to the main conduit, then in consecutive order the remaining valves with increasing rate apply pressure air shocks corresponding to the resulting increase in speed of the flow of the conveying medium along the conveying path. As soon as the pressurized air impulse is derived from the end of the auxiliary pressure-medium line, a pressure sensor initiates a repetition of this cycle. Also this pneumatic conveying system has the disadvantage that at a certain time point only a single point at the conveying path is supplied with the additional pressure medium for controlling the conveying process.
From the German published patent application 2 412 142 (Brown et al) filed March 13, 197~, it is known to provide a similar conveying arrangement including injectors for feeding additional pressure medium into the main conveying conduit. In this conveying device, loose material to be conveyed is fed into the main conveying conduit also in batches or portions. The individual portions of the loose material are supposed to advance in impulses so that the loose material is alternately moved and stopped. In accordance with this intermittent conveying condition in the main conduit, the pressure air injectors feed the additional pressure medium along the en~ire conveying path either in phase or with a phase shift. The control of the injector is effected either through an intermediate container of the pressure medium extending along the conveying path, or by means of a time control. This publication, however, does not disclose any difference in the effect of controlling the injectors in phase or with a phase shift, and a serious drawback of using the pressure air injectors 9;~
is the fact that no detection of the momentary pressure variations at different points of the main conveying condui-t is possible, and also there is no checkback indication of the effects of the additional injection of the pressure medium on the entire conveying process. Such a checkback, however, is an indispensable condition for exciting and maintaining the pulses in the conveying conduit, since such pulses, due to the friction, are increasingly damped at the end of the conveying pipe. In this prior-art pneumatic conveyor, one mus-t take into account the fact that instead of exciting the desired impulse a pressure-air injection at a false time point or at incorrect locations may con-tribute to the damping of the pulse-like stream, or to completely stop the same thus leading to a complete in-ter-ruption of the impulse-like transport.
From the German patent 2 550 164 (Krambrock et al) dated November 7, 1975, it is also known to provide a pneumatic conveying device in which auxiliary pressure medium is fed via valves into the main conveying conduit, which is substantially similar to that described in the German publication 2 305 030. The only difference can be seen in the fact that between two valves arranged for closing the auxiliary pressure medium conduit, there are provided several feed-in points between the auxiliary line and the main conveying conduit. Also in this case, there is a disadvantage that at certain time point only ~ 79;~
1 a single section of the main conveying conduit is supplied with the additional conveying medium. A11 sections before and ater the controlled section of the conveying conduit are unaffected by the system at this time point.
SUMMARY OF THE INVENTION
. . . ~
It is therefore a genaral object of the present invention to overcome the aforementioned disadvantages.
More particularly, it is an object of the inven-tion to provide an improved pneumatic conveying device for loose material, particularly for loose material of different ~ualities, which has an increased operational reliability and consumes less energy. -Another object of the invention is to provide such an improved conveying device which is wear resistant and unsusceptible to failureO
In keeping with these objects and others which will become apparent hereafter, one feature of the invention resides, in a conveying device of the aforedescribed type, in a combination which comprises a plurality of pressure sensors in the form of electrical pressure transducers con-nected at intervals to the primary conveying conduit, and an electronic control unit having logic circuits for generating reference signals corresponding to desired operational para---meters such as overall pressure, pressure differences, time interv of feedina auxiliary medium, and pulse r~te, input 1:~>~9~9~
1 means connected to respective sensors and output means con-nected to respective valves for comparing output signals from the sensors with the corresponding reference signals and for controlling the valves in response to diferences S between the reference signals and the output signals.
In summary, by contrast to the above-described known pneumatic conveying devices, in the device of this invention any change introduced into the pneumatic conveying process by the admission of the additional conveying medium is monitored and fed back into the control unit so as to achieve an adaptive and simultaneous regulation of the con-veying process over the entire length of the main conveyor.
As a result, it is possible to ma~e use of freely selectable control programs for any location and any time point of the lS conveying process.
The device of this invention makes it poss:ible to solve a broad variety of con~eying pro~lems in a single device. The various re~uirements imposed on the conveying device arise from the necessity to realize in an energetical--20 ly advantageous manner the transport of different loose materials which re~uire different flow conditions for achieving an optimum and material-protecting transport. For instance, some pulverized materials can be conveyed most slowly and without the danger of clogging by imparting vibra-tions to t advencing gas/solid particle mixture in order to il'79;398 1 achieve that in the middle in the conveying period the adhes-ive forces between the particles be mostly overcome and any impedement or adhesion of the product on the conveying con-duit will be avoided. Vibrations introduced at the beginnin~
of the conveying length are damped by the internal friction of the particles as well as by friction`against the convey-. . ing tube~ Onl.y the conveying device of-this invention . enables that the pulse rate is maintained by the synch:conous int~oduction oE pressure gas impulses at correct points along the main conveying conduit.
. In a further elaboration of this invention, it is poSsible to regis-ter the pressure variations, for example by means o a printer ox make the oscillation visible .in order to control the excitation of the pressure variations and t~us the entire conveying process.
Ano~her advantageous possibility is to be seen in the fact that the electronic control unit is programmable so that a self-optimi~ing program can be set in the unit.
. . In conveying another kind of loose material, the aforementioned method of imparting vibrations to the gas/
solid particle stream is either impossible or disadvantage-ous. This invention, however, enables even with this kind of loose material a uniform advance at low conveying speed . and at high load. The economy and product protection of a pneumatic conveying process increase-when the conveying speed l:L'79~39B
1 and the load approach the clogging limit. An imminent clogging reveals itself by ~he increase of local concentra-tion of the loose material resulting in an increased pressure drop in this region of the conveying conduit. In the device of thls invention, similarly as in the prior art devices of this kind, the measured pressure differences in the conveying conduit in the consecutive sections of the latter are measured and compared with given nominal values. These nominal values however, by contrast to prior art, can be readily adjusted to o~timum values without any consideration of the limits imposed by the mechanical construction of the devi~e; moreover, as mentioned before, the programm~ble electronic control unit, in cooperation with a,xegistering' apparatus or by means of''an optimizing program, is capable 15, o adjusting an optimum value of the differential pressure for each section of the conveying conduit already in the course and in response to the conveying process.
To obtain an energetically favorable conveying , ' operation, the device of this invention can be modified to 20 ' measure the amount ~f pressure medium flowing through the auxiliary secondary line and convert the same into electrical magnitudes which in turn are processed by the programmable electronic unit.
il~79~398 BRIEF DESCRIPTION OF THE DRAWING
. ~
The single FIGURE illustrates schematically an example of a pneumatic conveying device embodying this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
. A primary conveying conduit 1 is supplied with a conveying pressure medium from a container 2 into which the .
.~ pressure medium is admitted through supply line 3~ Loose material to be conveyed is charged through a hopper into the container 2 and is pneumatically conveyed through the convey-or 1 to a separator 4. Parallel to the primary conve~or 1 extends a secondary conduit 5 connected via a connection 6 to a reservoir of pressure medium. Tap lines 7 branch at regu-. lar intervals from the secondary conduit 5 and are connected to electrically controllable valves Vl-V4. The outlet of each valve is connected by non-return valves 8 to feed-in connections 9 (each containing a non-illustrated filter) in the main conveying conduit 1. As seen in the FIGURE, a group of several feed-in connections 9 is assigned to respective control~able valves to. inject additional pressure medium into the main conduit~ Electrical pressure transducers Sl-S5 are distributed along the main conveying conduit 1 to detect pressure upstream and downstream of respective groups o~
. feed-in connections 9. The outlets of respective pressure . transducers are connected via conductors 10 to corresponding il'~'.);;~98 1 ¦inputs of a programmable electxonic control unit 11, where th~
¦pressure signals are stored and processed ~y suitable logic ¦circuits to be compared with adjustable reference values ¦corresponding to the desired parameters of the conveying ¦device. The output signals from-unit ll are applied via ¦output conducto.-s 12 to the electrically controlled valves ¦V1-V4. If desired, a gas flow meter 13 can be arranged at ¦the beginning of the au~iliary pressure medium line 5 to feed via conductor 14 a measuring signal proportional to the flow of the auxiliar~ pressure medium to the control unit 11. The latter unit has add.itional inputs for auxiliary input signals or for setting arbitrary parameters or starting parameters for the conveying program.
. A conveying cycle starts with charging a loose material into the container 2, whereby a non-illustrated outlet valve at the inlet opening to the main conduit l is closed. Thereupon, pressure medium is admitted through feed-ing line 3 into the vessel 2. The actual conveying process . starts with the opening of the outlet valve while the pres-20 - sure medium continues to be fed into the pressure container 2. .
In the case of a vibrational transport, the pres-sure medium is intermittently applied through the feeding line 3 into the pressure container 2 or into the inlet of the main conveying conduit l. The resulting pressure varia-il'~9;~98 1 tions cause an oscillating movement of the stream of the conveyed loose material, during which the internal binding forces between the particles of the material are neutralized and therefore in spite of high load of the conveying pressure medium with the loose material no clogging in the conveying conduit occurs. Vibrations of the conveyed stream introduced into the conveying pipe would promptly disappear due to the internal forces along the conveying path if no periodic impulses of pressure air were injected into the conveying conduit. In this embodlment, these excitation impulses are generated by indiyidually opening the valves Vl-V4 50 tha-t pressure air jets are periodically introduced into the main .conveying aonduit at controllable time intervals. In this . manner, the desired vibrations are regenerated up to the outlet end of the conduit 1. To ensure the synchronization o the introduced impulses of pressure air with the vibra-tions of the.conveyed stream, so that these vibrations be amplified and not cancelled, it is necessary to control the timing of these pulses. For this purpose, the electricai 2~ pressure transducers Sl-S5 signalize either to the operator or the electronic control unit 11. the pressure variations in the main conveying conduit 1. Accordingly, the operator or the automatic control unit can adjust the duration and the moments of actuation of the controllable valves Vl-Y4 until an optimum operation of the conveyinq device is achieved.
1 1'~ 38 1 ¦The correct operation, as mentioned before, is indicated by ¦the amplification of the pressure variations in the main con-¦veying conduit in response to the introduced pressure air ¦impulses, whereas incorrect operation is indicated by the ¦decrease of these pressure variations. As soon as an optimum ¦s~itching order for the controllable valves is found, then jthe adjustment of the entire conveying device remains un-¦changed as long as the same loose material is being con-veyed.
With many products, the vibrational ,conveying is either impossible or impractical. Even in such cases, in order to protect the conveyed material and to reduce wear on the device, it is of importance that the loose material be advanced as slowly as possible. In doing so, the danger is always present that a clogging or blocking of the conveyed material occurs in the conveying conduit. ~n immanent rlog-ging at a point of the conveying pipe produces an increased pressure drop of the conveying medium. The electronic pres-sure transducers Sl-S5 transmit signals about the pressure conditions in predetermined sections of the conveying con-duit. In the event that the pressure drop in a conduit sec-tion between two pressure transducers exceeds a maximum per-missiblepressure drop which is determined by an internal program of the electronic control unit ~or respective con-duit sections, then the control unit produces a control sig-.
9~38 1 nal applied ~o the controllable valves and opens the same so long until the admitted pressure medium ~t that specific location of the conveying conduit produces the pressure drop below this maximum permissible value.
Flow mete- 13 for the pressure medium transmits electrical signals indicative of the consumption o~ the additional pressure medium flowing through secondary conduit 5~ thus permitting use of a suitable program in the unit ll for estimating energy consumption for a particular conveying condition.
The actuation of the electrically controllable valves can be made either in response to output signals from the programmable unit ll corresponding to the di~ference of the signals from the pressure transducers and the reference signals which are determined by the program of the unit;
alternatively, the valves can be controlled manually by an attendant observing the aforementioned criteria for optimi~-ing the conveying process. To enable an analysis of the reaction of the conveying device to the control by the elec-tronic control unit, the input signals to the latter, that is the pressures in the conveying conduit or the consumption of the auxiliary pressure medium in the secondary line, are either selectively or continuously registered in suitable recording devices, such as an oscillograph, line printer, -dotted-line recorder, or other printer. In this manner, . I
1 1:~7~33~3 f 1 ¦the control unit 11 not only optimizes the ac~ual conveying ¦condition o the device, but also makes it possible to set ¦a program for the optimum conveying operation. In changing ¦the loose material to be conveyed or the conveying medium to S ¦be loaded with the material, the algorithms as well as the ¦freely selectable parameters of the program in the unit 11 ¦can be readiIy changed according to the new conditions. The same conveying unit therefore is capable of conveying wi~hout t difficulties a wide assortment of loose material requiring different optimization'criteria for achieving an eneryetical-ly advantageous mode of operation or a very slow advance.
The setting of optimum conveying operation of the device can be made,wi~hout monitoring the entire conveying path, conven-iently from a control console where all information relating to the momentary condition of the device is received either continuously or upon interrogation. It is also advantageous when the controllable valves Vl-V4 are provided with confirm-ation or repetition signalling devices connec~ed to the unit 11 by non-illustrated conductors to apply to the unit,signals indicative of the actual operative condition of each valve and made visible or otherwise indicated. In this manner any failure of the valves and the resulting malfunction of the device is quickly recognized and localized. Valves having only two valve positions, namely an open position and a ¦¦closed sition, are usually fully sufficiert for Uc appli~
.
f 9~
1 ¦cation in the device of this invention; if desired, however, valves can be employed which are controllable to assume in-¦termediate or throttling positions in addi.tion to ~he closed ¦or opened limit positions, so as to save the auxiliary pres-¦sure medium at the cost of more expensive construction.
¦ Back pressure valves 9 and filters prevent leakage ¦of the conveying pressure air from the main conveying conduit ¦into the auxiliary pressure medium lines, thus contributing ¦to the operational reliability of the whole device.
¦ It will be understood that each of the elements ¦described above, or two or more together, may also find a ¦useful application in other types o constructions differing ¦from the types described above.
¦ While the invention has been illustrated and ¦described as embodied in a pneumatic conveying device with a ¦programmable control unit, it is not intended to be limited ¦to the details shown, since various modifications and struc-¦tural changes may be made wlthout departing in any way from ¦the spirit of the present invention.
¦ Without further analysis, the fo~egoing will so ¦fully reveal the gist of the present invention that others ¦can by applying current knowledge readily adapt it for vari-¦ous applications without omitting features that, from the ¦standpoint of prior art, fairly constitute essential charac-~5 ¦teristics of the generic or specific aspects of this inven-~ -19-' ~lt7933~ ~
1 tion.
What is claimed as new and desired to be protected by Letters Patent is set forth in the appended cl~
. ' . i .' i ~F ~ ~r, ~ ~"``''!'':~-`
From the German published patent application 2 412 142 (Brown et al) filed March 13, 197~, it is known to provide a similar conveying arrangement including injectors for feeding additional pressure medium into the main conveying conduit. In this conveying device, loose material to be conveyed is fed into the main conveying conduit also in batches or portions. The individual portions of the loose material are supposed to advance in impulses so that the loose material is alternately moved and stopped. In accordance with this intermittent conveying condition in the main conduit, the pressure air injectors feed the additional pressure medium along the en~ire conveying path either in phase or with a phase shift. The control of the injector is effected either through an intermediate container of the pressure medium extending along the conveying path, or by means of a time control. This publication, however, does not disclose any difference in the effect of controlling the injectors in phase or with a phase shift, and a serious drawback of using the pressure air injectors 9;~
is the fact that no detection of the momentary pressure variations at different points of the main conveying condui-t is possible, and also there is no checkback indication of the effects of the additional injection of the pressure medium on the entire conveying process. Such a checkback, however, is an indispensable condition for exciting and maintaining the pulses in the conveying conduit, since such pulses, due to the friction, are increasingly damped at the end of the conveying pipe. In this prior-art pneumatic conveyor, one mus-t take into account the fact that instead of exciting the desired impulse a pressure-air injection at a false time point or at incorrect locations may con-tribute to the damping of the pulse-like stream, or to completely stop the same thus leading to a complete in-ter-ruption of the impulse-like transport.
From the German patent 2 550 164 (Krambrock et al) dated November 7, 1975, it is also known to provide a pneumatic conveying device in which auxiliary pressure medium is fed via valves into the main conveying conduit, which is substantially similar to that described in the German publication 2 305 030. The only difference can be seen in the fact that between two valves arranged for closing the auxiliary pressure medium conduit, there are provided several feed-in points between the auxiliary line and the main conveying conduit. Also in this case, there is a disadvantage that at certain time point only ~ 79;~
1 a single section of the main conveying conduit is supplied with the additional conveying medium. A11 sections before and ater the controlled section of the conveying conduit are unaffected by the system at this time point.
SUMMARY OF THE INVENTION
. . . ~
It is therefore a genaral object of the present invention to overcome the aforementioned disadvantages.
More particularly, it is an object of the inven-tion to provide an improved pneumatic conveying device for loose material, particularly for loose material of different ~ualities, which has an increased operational reliability and consumes less energy. -Another object of the invention is to provide such an improved conveying device which is wear resistant and unsusceptible to failureO
In keeping with these objects and others which will become apparent hereafter, one feature of the invention resides, in a conveying device of the aforedescribed type, in a combination which comprises a plurality of pressure sensors in the form of electrical pressure transducers con-nected at intervals to the primary conveying conduit, and an electronic control unit having logic circuits for generating reference signals corresponding to desired operational para---meters such as overall pressure, pressure differences, time interv of feedina auxiliary medium, and pulse r~te, input 1:~>~9~9~
1 means connected to respective sensors and output means con-nected to respective valves for comparing output signals from the sensors with the corresponding reference signals and for controlling the valves in response to diferences S between the reference signals and the output signals.
In summary, by contrast to the above-described known pneumatic conveying devices, in the device of this invention any change introduced into the pneumatic conveying process by the admission of the additional conveying medium is monitored and fed back into the control unit so as to achieve an adaptive and simultaneous regulation of the con-veying process over the entire length of the main conveyor.
As a result, it is possible to ma~e use of freely selectable control programs for any location and any time point of the lS conveying process.
The device of this invention makes it poss:ible to solve a broad variety of con~eying pro~lems in a single device. The various re~uirements imposed on the conveying device arise from the necessity to realize in an energetical--20 ly advantageous manner the transport of different loose materials which re~uire different flow conditions for achieving an optimum and material-protecting transport. For instance, some pulverized materials can be conveyed most slowly and without the danger of clogging by imparting vibra-tions to t advencing gas/solid particle mixture in order to il'79;398 1 achieve that in the middle in the conveying period the adhes-ive forces between the particles be mostly overcome and any impedement or adhesion of the product on the conveying con-duit will be avoided. Vibrations introduced at the beginnin~
of the conveying length are damped by the internal friction of the particles as well as by friction`against the convey-. . ing tube~ Onl.y the conveying device of-this invention . enables that the pulse rate is maintained by the synch:conous int~oduction oE pressure gas impulses at correct points along the main conveying conduit.
. In a further elaboration of this invention, it is poSsible to regis-ter the pressure variations, for example by means o a printer ox make the oscillation visible .in order to control the excitation of the pressure variations and t~us the entire conveying process.
Ano~her advantageous possibility is to be seen in the fact that the electronic control unit is programmable so that a self-optimi~ing program can be set in the unit.
. . In conveying another kind of loose material, the aforementioned method of imparting vibrations to the gas/
solid particle stream is either impossible or disadvantage-ous. This invention, however, enables even with this kind of loose material a uniform advance at low conveying speed . and at high load. The economy and product protection of a pneumatic conveying process increase-when the conveying speed l:L'79~39B
1 and the load approach the clogging limit. An imminent clogging reveals itself by ~he increase of local concentra-tion of the loose material resulting in an increased pressure drop in this region of the conveying conduit. In the device of thls invention, similarly as in the prior art devices of this kind, the measured pressure differences in the conveying conduit in the consecutive sections of the latter are measured and compared with given nominal values. These nominal values however, by contrast to prior art, can be readily adjusted to o~timum values without any consideration of the limits imposed by the mechanical construction of the devi~e; moreover, as mentioned before, the programm~ble electronic control unit, in cooperation with a,xegistering' apparatus or by means of''an optimizing program, is capable 15, o adjusting an optimum value of the differential pressure for each section of the conveying conduit already in the course and in response to the conveying process.
To obtain an energetically favorable conveying , ' operation, the device of this invention can be modified to 20 ' measure the amount ~f pressure medium flowing through the auxiliary secondary line and convert the same into electrical magnitudes which in turn are processed by the programmable electronic unit.
il~79~398 BRIEF DESCRIPTION OF THE DRAWING
. ~
The single FIGURE illustrates schematically an example of a pneumatic conveying device embodying this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
. A primary conveying conduit 1 is supplied with a conveying pressure medium from a container 2 into which the .
.~ pressure medium is admitted through supply line 3~ Loose material to be conveyed is charged through a hopper into the container 2 and is pneumatically conveyed through the convey-or 1 to a separator 4. Parallel to the primary conve~or 1 extends a secondary conduit 5 connected via a connection 6 to a reservoir of pressure medium. Tap lines 7 branch at regu-. lar intervals from the secondary conduit 5 and are connected to electrically controllable valves Vl-V4. The outlet of each valve is connected by non-return valves 8 to feed-in connections 9 (each containing a non-illustrated filter) in the main conveying conduit 1. As seen in the FIGURE, a group of several feed-in connections 9 is assigned to respective control~able valves to. inject additional pressure medium into the main conduit~ Electrical pressure transducers Sl-S5 are distributed along the main conveying conduit 1 to detect pressure upstream and downstream of respective groups o~
. feed-in connections 9. The outlets of respective pressure . transducers are connected via conductors 10 to corresponding il'~'.);;~98 1 ¦inputs of a programmable electxonic control unit 11, where th~
¦pressure signals are stored and processed ~y suitable logic ¦circuits to be compared with adjustable reference values ¦corresponding to the desired parameters of the conveying ¦device. The output signals from-unit ll are applied via ¦output conducto.-s 12 to the electrically controlled valves ¦V1-V4. If desired, a gas flow meter 13 can be arranged at ¦the beginning of the au~iliary pressure medium line 5 to feed via conductor 14 a measuring signal proportional to the flow of the auxiliar~ pressure medium to the control unit 11. The latter unit has add.itional inputs for auxiliary input signals or for setting arbitrary parameters or starting parameters for the conveying program.
. A conveying cycle starts with charging a loose material into the container 2, whereby a non-illustrated outlet valve at the inlet opening to the main conduit l is closed. Thereupon, pressure medium is admitted through feed-ing line 3 into the vessel 2. The actual conveying process . starts with the opening of the outlet valve while the pres-20 - sure medium continues to be fed into the pressure container 2. .
In the case of a vibrational transport, the pres-sure medium is intermittently applied through the feeding line 3 into the pressure container 2 or into the inlet of the main conveying conduit l. The resulting pressure varia-il'~9;~98 1 tions cause an oscillating movement of the stream of the conveyed loose material, during which the internal binding forces between the particles of the material are neutralized and therefore in spite of high load of the conveying pressure medium with the loose material no clogging in the conveying conduit occurs. Vibrations of the conveyed stream introduced into the conveying pipe would promptly disappear due to the internal forces along the conveying path if no periodic impulses of pressure air were injected into the conveying conduit. In this embodlment, these excitation impulses are generated by indiyidually opening the valves Vl-V4 50 tha-t pressure air jets are periodically introduced into the main .conveying aonduit at controllable time intervals. In this . manner, the desired vibrations are regenerated up to the outlet end of the conduit 1. To ensure the synchronization o the introduced impulses of pressure air with the vibra-tions of the.conveyed stream, so that these vibrations be amplified and not cancelled, it is necessary to control the timing of these pulses. For this purpose, the electricai 2~ pressure transducers Sl-S5 signalize either to the operator or the electronic control unit 11. the pressure variations in the main conveying conduit 1. Accordingly, the operator or the automatic control unit can adjust the duration and the moments of actuation of the controllable valves Vl-Y4 until an optimum operation of the conveyinq device is achieved.
1 1'~ 38 1 ¦The correct operation, as mentioned before, is indicated by ¦the amplification of the pressure variations in the main con-¦veying conduit in response to the introduced pressure air ¦impulses, whereas incorrect operation is indicated by the ¦decrease of these pressure variations. As soon as an optimum ¦s~itching order for the controllable valves is found, then jthe adjustment of the entire conveying device remains un-¦changed as long as the same loose material is being con-veyed.
With many products, the vibrational ,conveying is either impossible or impractical. Even in such cases, in order to protect the conveyed material and to reduce wear on the device, it is of importance that the loose material be advanced as slowly as possible. In doing so, the danger is always present that a clogging or blocking of the conveyed material occurs in the conveying conduit. ~n immanent rlog-ging at a point of the conveying pipe produces an increased pressure drop of the conveying medium. The electronic pres-sure transducers Sl-S5 transmit signals about the pressure conditions in predetermined sections of the conveying con-duit. In the event that the pressure drop in a conduit sec-tion between two pressure transducers exceeds a maximum per-missiblepressure drop which is determined by an internal program of the electronic control unit ~or respective con-duit sections, then the control unit produces a control sig-.
9~38 1 nal applied ~o the controllable valves and opens the same so long until the admitted pressure medium ~t that specific location of the conveying conduit produces the pressure drop below this maximum permissible value.
Flow mete- 13 for the pressure medium transmits electrical signals indicative of the consumption o~ the additional pressure medium flowing through secondary conduit 5~ thus permitting use of a suitable program in the unit ll for estimating energy consumption for a particular conveying condition.
The actuation of the electrically controllable valves can be made either in response to output signals from the programmable unit ll corresponding to the di~ference of the signals from the pressure transducers and the reference signals which are determined by the program of the unit;
alternatively, the valves can be controlled manually by an attendant observing the aforementioned criteria for optimi~-ing the conveying process. To enable an analysis of the reaction of the conveying device to the control by the elec-tronic control unit, the input signals to the latter, that is the pressures in the conveying conduit or the consumption of the auxiliary pressure medium in the secondary line, are either selectively or continuously registered in suitable recording devices, such as an oscillograph, line printer, -dotted-line recorder, or other printer. In this manner, . I
1 1:~7~33~3 f 1 ¦the control unit 11 not only optimizes the ac~ual conveying ¦condition o the device, but also makes it possible to set ¦a program for the optimum conveying operation. In changing ¦the loose material to be conveyed or the conveying medium to S ¦be loaded with the material, the algorithms as well as the ¦freely selectable parameters of the program in the unit 11 ¦can be readiIy changed according to the new conditions. The same conveying unit therefore is capable of conveying wi~hout t difficulties a wide assortment of loose material requiring different optimization'criteria for achieving an eneryetical-ly advantageous mode of operation or a very slow advance.
The setting of optimum conveying operation of the device can be made,wi~hout monitoring the entire conveying path, conven-iently from a control console where all information relating to the momentary condition of the device is received either continuously or upon interrogation. It is also advantageous when the controllable valves Vl-V4 are provided with confirm-ation or repetition signalling devices connec~ed to the unit 11 by non-illustrated conductors to apply to the unit,signals indicative of the actual operative condition of each valve and made visible or otherwise indicated. In this manner any failure of the valves and the resulting malfunction of the device is quickly recognized and localized. Valves having only two valve positions, namely an open position and a ¦¦closed sition, are usually fully sufficiert for Uc appli~
.
f 9~
1 ¦cation in the device of this invention; if desired, however, valves can be employed which are controllable to assume in-¦termediate or throttling positions in addi.tion to ~he closed ¦or opened limit positions, so as to save the auxiliary pres-¦sure medium at the cost of more expensive construction.
¦ Back pressure valves 9 and filters prevent leakage ¦of the conveying pressure air from the main conveying conduit ¦into the auxiliary pressure medium lines, thus contributing ¦to the operational reliability of the whole device.
¦ It will be understood that each of the elements ¦described above, or two or more together, may also find a ¦useful application in other types o constructions differing ¦from the types described above.
¦ While the invention has been illustrated and ¦described as embodied in a pneumatic conveying device with a ¦programmable control unit, it is not intended to be limited ¦to the details shown, since various modifications and struc-¦tural changes may be made wlthout departing in any way from ¦the spirit of the present invention.
¦ Without further analysis, the fo~egoing will so ¦fully reveal the gist of the present invention that others ¦can by applying current knowledge readily adapt it for vari-¦ous applications without omitting features that, from the ¦standpoint of prior art, fairly constitute essential charac-~5 ¦teristics of the generic or specific aspects of this inven-~ -19-' ~lt7933~ ~
1 tion.
What is claimed as new and desired to be protected by Letters Patent is set forth in the appended cl~
. ' . i .' i ~F ~ ~r, ~ ~"``''!'':~-`
Claims (10)
1. A device for pneumatic conveying of loose material, comprising a primary conveying conduit and a secondary pressure-medium line extending parallel to the primary condult; a plurality of electrically controlled valves arranged at intervals along the conveying path for connecting the secondary pressure-medium line to the primary conveying conduit; a plurality of pressure sensors in the form of electrical pressure transducers communicating at intervals with the primary conduit; and an electronic control unit having means for storing reerence signals corresponding to desired operational parameters such as pressure, pressure differences, time intervals and vibrational frequency, input means connected to respective sensors, and means for compar-ing the signals from the input means with the reference sig-nals to produce output signals connected to respective valves to control the feeding of pressure medium from the secondary line into the primary conveying conduit according to a preset criterion.
2. A device as defined in claim 1, further including a flow meter in said secondary pressure-medium line and being coupled to said control unit.
3. A device as defined in claim 1, wherein said control unit includes a control console for optically or acoustically indicating the operative condition of respec-tive valves.
4. A device as defined in claim 1, wherein said control unit includes recording devices for continuously registering the operation of the device.
5. A device as defined in claim 1, wherein said control unit includes means for storing a plurality of con-trol programs corresponding to different operational condi-tions of different sorts of loose material.
6. A device as defined in claim 5, wherein the control unit includes means for automatically correcting the preset reference signals in response to an optimization program.
7. A device as defined in claim 1, wherein said primary conveying conduit includes a plurality of connection points for feeding-in the auxiliary pressure medium from the secondary line, and each valve being assigned to a separate group of said connection points.
8. A device as defined in claim 7, wherein each connection point includes a filter.
9. A device as defined in claim 7, wherein a back pressure valve is connected at each connection point to prevent leakage of pressure medium from the primary conduit into the secondary line.
10. A device as defined in claim 7, wherein said pressure sensors are arranged upstream and downstream of each group of connection points.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3037517A DE3037517C2 (en) | 1980-10-03 | 1980-10-03 | System for the pneumatic conveying of bulk goods |
| DEP3037517.8-22 | 1980-10-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1179398A true CA1179398A (en) | 1984-12-11 |
Family
ID=6113585
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000387147A Expired CA1179398A (en) | 1980-10-03 | 1981-10-02 | Device for pneumatic conveying of loose material |
Country Status (15)
| Country | Link |
|---|---|
| JP (1) | JPS57121530A (en) |
| AU (1) | AU541179B2 (en) |
| BE (1) | BE890603A (en) |
| CA (1) | CA1179398A (en) |
| CH (1) | CH652695A5 (en) |
| DE (1) | DE3037517C2 (en) |
| DK (1) | DK151565C (en) |
| FR (1) | FR2491443B1 (en) |
| GB (1) | GB2085388B (en) |
| IT (1) | IT1138648B (en) |
| LU (1) | LU83659A1 (en) |
| NL (1) | NL8104374A (en) |
| NO (1) | NO813351L (en) |
| SE (1) | SE8105598L (en) |
| ZA (1) | ZA816853B (en) |
Families Citing this family (25)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0060135B1 (en) * | 1981-03-09 | 1985-09-11 | Macawber Engineering Limited | Conveying apparatus |
| DE3225449C2 (en) * | 1982-07-07 | 1988-09-29 | Klöckner Stahlforschung GmbH, 8458 Sulzbach-Rosenberg | Method and device for measuring and / or regulating the mass flow of solid particles |
| JPS59124624A (en) * | 1982-12-27 | 1984-07-18 | Kawasaki Steel Corp | Method for distribution and transport of pulverized/ granular material |
| JPS6118635A (en) * | 1984-06-21 | 1986-01-27 | Matsui Seisakusho:Kk | Pneumatic conveyance of powder material free from clogging and apparatus thereof |
| DE3435907A1 (en) * | 1984-09-29 | 1986-04-10 | AVT Anlagen- und Verfahrenstechnik GmbH, 7981 Vogt | METHOD AND DEVICE FOR THE PNEUMATIC AND HYDRAULIC TRANSPORT OF SOLIDS BY PIPING |
| JPS61140415A (en) * | 1984-12-14 | 1986-06-27 | Nippon Spindle Mfg Co Ltd | Powder transport method |
| DE3714923A1 (en) * | 1987-05-05 | 1988-12-01 | Waeschle Maschf Gmbh | DEVICE FOR PNEUMATICALLY CONVEYING SCHUETTGUT |
| DE3714924A1 (en) * | 1987-05-05 | 1988-12-01 | Waeschle Maschf Gmbh | DEVICE FOR PNEUMATICALLY CONVEYING SCHUETTGUT |
| DE4118560C1 (en) * | 1991-06-06 | 1992-09-10 | Alb. Klein Gmbh & Co. Kg, 5241 Niederfischbach, De | |
| JPH0741991B2 (en) * | 1991-08-27 | 1995-05-10 | 株式会社日本アルミ | Pneumatic transportation method of powder and granular material and pneumatic transportation device of powder and granular material |
| DE4328626A1 (en) * | 1993-08-27 | 1995-03-02 | Motan Verfahrenstechnik | Method for operating a conveyor pipeline with dense-stream conveyance and apparatus for carrying out the method |
| DE4424897A1 (en) | 1994-07-15 | 1996-01-18 | Motan Verfahrenstechnik | Method and device for the pneumatic conveying of bulk material |
| US5584612A (en) * | 1994-11-02 | 1996-12-17 | Nol-Tec Systems, Inc. | Apparatus and process for pneumatically conveying material and for controlling the feed of supplemental gas |
| DE19542787A1 (en) * | 1995-11-16 | 1997-05-22 | Wacker Chemie Gmbh | Self-regulating fluidised transport system |
| US6106202A (en) * | 1998-05-04 | 2000-08-22 | Nol-Tec Systems, Inc. | Pneumatic conveying air assist line with air bleed |
| GB2375104B (en) * | 2001-05-03 | 2003-11-19 | Rugby Group Ltd The | Material handling apparatus and method |
| DE10202248A1 (en) * | 2002-01-21 | 2003-07-31 | Buehler Ag | System for influencing the rheological properties of a conveyable material |
| GB2392895B (en) * | 2002-09-10 | 2006-07-19 | Rotaval Ltd | Control system for pneumatic conveyor control device and method therefor |
| DE102004047457B8 (en) * | 2004-09-30 | 2009-11-26 | Coperion Gmbh | Method for operating a conveyor system for flowable bulk materials, conveyor system for carrying out the method and multiple-function valve for this purpose |
| DE102013007705B4 (en) * | 2013-05-03 | 2017-11-23 | Zeppelin Systems Gmbh | Device and method for operating a pneumatic conveyor in the dense stream by means of controlled overflow valves |
| GB201611662D0 (en) | 2016-07-04 | 2016-08-17 | Clyde Process Ltd | Material conveying apparatus and method |
| CN108584443A (en) * | 2018-04-16 | 2018-09-28 | 江苏师范大学 | A kind of Pneumatic conveying pipeline blocks dredging system and method |
| GB201906310D0 (en) | 2019-05-03 | 2019-06-19 | Schenck Process Uk Ltd | Material conveying apparatus with shut down valves |
| CN110550457A (en) * | 2019-09-09 | 2019-12-10 | 浙江乔治白服饰股份有限公司 | Waste material collecting device and waste material collecting method |
| WO2021240554A1 (en) * | 2020-05-25 | 2021-12-02 | Nte Holding S.R.L. | Fluid control system in pneumatic conveying ducts for powdered or granular material |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1405207A (en) * | 1961-07-22 | 1965-07-09 | Poirier Pauze & Cie Ets | Method for transporting powdery, pasty or similar products and device for applying said method |
| JPS5593734A (en) * | 1978-12-29 | 1980-07-16 | Gen Resource Corp | Method and device for carrying corpuscular substance through pipeeline |
-
1980
- 1980-10-03 DE DE3037517A patent/DE3037517C2/en not_active Expired
-
1981
- 1981-09-15 GB GB8127855A patent/GB2085388B/en not_active Expired
- 1981-09-16 FR FR8117461A patent/FR2491443B1/en not_active Expired
- 1981-09-18 CH CH6052/81A patent/CH652695A5/en not_active IP Right Cessation
- 1981-09-22 SE SE8105598A patent/SE8105598L/en not_active Application Discontinuation
- 1981-09-23 AU AU75585/81A patent/AU541179B2/en not_active Ceased
- 1981-09-23 NL NL8104374A patent/NL8104374A/en not_active Application Discontinuation
- 1981-09-28 IT IT24178/81A patent/IT1138648B/en active
- 1981-09-30 DK DK433281A patent/DK151565C/en not_active IP Right Cessation
- 1981-10-01 LU LU83659A patent/LU83659A1/en unknown
- 1981-10-02 CA CA000387147A patent/CA1179398A/en not_active Expired
- 1981-10-02 JP JP56156305A patent/JPS57121530A/en active Pending
- 1981-10-02 BE BE0/206148A patent/BE890603A/en not_active IP Right Cessation
- 1981-10-02 NO NO813351A patent/NO813351L/en unknown
- 1981-10-02 ZA ZA816853A patent/ZA816853B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| IT8124178A0 (en) | 1981-09-28 |
| AU7558581A (en) | 1982-04-08 |
| NL8104374A (en) | 1982-05-03 |
| BE890603A (en) | 1982-02-01 |
| NO813351L (en) | 1982-04-05 |
| ZA816853B (en) | 1982-09-29 |
| LU83659A1 (en) | 1982-02-17 |
| DE3037517C2 (en) | 1983-12-08 |
| GB2085388A (en) | 1982-04-28 |
| DE3037517A1 (en) | 1982-04-22 |
| FR2491443A1 (en) | 1982-04-09 |
| JPS57121530A (en) | 1982-07-29 |
| DK151565B (en) | 1987-12-14 |
| DK433281A (en) | 1982-04-04 |
| AU541179B2 (en) | 1984-12-20 |
| IT1138648B (en) | 1986-09-17 |
| DK151565C (en) | 1988-05-24 |
| SE8105598L (en) | 1982-04-04 |
| GB2085388B (en) | 1984-05-10 |
| CH652695A5 (en) | 1985-11-29 |
| FR2491443B1 (en) | 1988-04-22 |
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