FR2491443A1 - PLANT FOR THE PNEUMATIC TRANSPORT OF BULK PRODUCTS - Google Patents

Abstract

INSTALLATION FOR THE PNEUMATIC TRANSPORT OF BULK PRODUCTS, COMPRISING A SECONDARY CONDUIT 5 OF CONVEYOR FLUID PLACED PARALLEL TO CONVEYANCE LINE 1 AND CONNECTED THEREWITH V, V VALVES, AS WELL AS PRESSURE SENSORS FOR THE CONTROL OF THESE VALVES, SENSORS REALIZED IN THE FORM OF ELECTRIC PRESSURE TRANSMITTERS S, S AND WHICH ARE CONNECTED TO AN ELECTRONIC CONTROL UNIT 11 WHICH MAKES A LOGICAL COMBINATION OF THE OUTPUT SIGNALS OF S TRANSMITTERS, WITH PARAMETERS SET AS SET VALUES AND CHARACTERIZING THE CONDITIONS OF TRANSPORT, AND WHICH, WHEN THE ACTUAL CONDITIONS OF TRANSPORT DIFFER FROM THE PRESCRIBED CONDITIONS, ELECTRICALLY OPERATES VALVES V, V CONTROLLED BY OTHER LINES. IN ADDITION, AN ELECTRICAL GAS FLOW MEASUREMENT INSTRUMENT CAN BE PROVIDED IN THE INSTALLATION, CONNECTED TO THE CONTROL UNIT.

Description

The invention relates to an installation for transport

  pneumatic of bulk products, comprising a secondary line

  re of carrier fluid which is laid parallel to the pipe

  transport and is connected to it by valves

  ordered along the transport path, as well as pressure sensors, arranged at intervals in the transport line,

for controlling these valves.

  An installation of this kind is known as a pro-

  position according to the literature (Verfahrenstechnik 12 (1978) 4,

  p. 200, Figure 12) and includes a transport line, parallel-

  in which a secondary fluid pipe is laid

  carrier, from which of the carrier fluid

  additional flow through a section of the transport line whenever the pressure drop in the section of the transport line exceeds an adjustable value. In this

  Indeed, it is planned to fix at intervals, on the trans-

  port, membranes each of which acts, via a

  piston, on a common rocker linkage, each piston if-

  killed upstream being at the same time produced in the form of a

  valve which, if a pre-set value is exceeded

  determined by a spring with respect to the differential pressure

  opens a bypass line which connects the secondary line to several air injection points on the transport line. Leaving aside that this complicated mechanism goes against an economically acceptable realization of a

  such an installation, an installation of this kind would have

  agrees that the spring setting the target value should

  present a significant pre-tension, so that small oscil-

  pressure lations are unlikely to trigger bats

  unwanted valve parts. So that this force of pre-

  voltage can be overcome by the differential pressure detected

  mechanically, the membranes should be dimensioned with

  particularly large areas, according to the relationship "for-

  ce = Pressure x Area ". This increases the size of the pressure sensing and transmission elements and, consequently, makes them expensive. For transport lines up to approximately 80 mm in diameter, they are too large, since the curvature of the pipe is then too great for flat membranes. In addition, large membranes are too sensitive to "water hammer" and to the wear produced by the flow of solid matter.

  large membranes require large passages between the con-

  transport pickup and pressure sensors, which results

  to deposits of solids on the membrane, deposits which

  promise the pressure sensor function of this to

over time.

  Also known, from German patent 17 81 025, is a pneumatic transport installation with a secondary transport fluid line which is parallel to the

  transport line and from which fluid is transported

  additional valve is injected into the transport line by means of controlled valves. Upstream of the controlled valves,

  Measuring points are provided on the transport line.

  the controlled valves are actuated by the signals emitted by these measuring points. The technical purpose of this installation

  known transportation is to move the bulk product to

  carry through the transport pipe by successive plugs separated by cushions of transporting fluid. In order that the different plugs do not meet, additional transport fluid is injected along the transport path into the transport fluid cushions which are located between the plugs. To this end, the measuring points, the measuring principle of which is based on rays of light or on radioactive radiation, record whether it is a plug or a cushion of carrier fluid which is at the point of injection of the fluid.

additional transporter.

249144:

  s 3. We know from the German patent application

  2 022 962, another transport installation comprising a

  secondary carrier fluid which is placed parallel-

  to the transport line, and from which

  conveyor is injected through valves into the transport line along the transport path. The technical purpose of this transport facility is to make the fall uniform

  pressure along the course. But since the soupa-

  injection weights of this known transport facility are not

  not controllable, absolutely no prediction can be made

  tion on the quantity of additional transport fluid which will penetrate, along the route, in the different sections of the

  transport line. However, as long as the injection of the trans-

  additional carrier can not be ordered, we can not fix beforehand what will be the shape of the variation

  pressure in the transport line due to the injection

  tion. It is also known, from German patent application 22 19 199, a transport installation comprising a

  secondary transport fluid line which is laid parallel

  to the transport line and from which additional transport medium flows into the transport line

  transport by valves controlled by the upstream pressure.

  The valves, arranged in the secondary transport fluid line, impose a defined pressure drop in the secondary transport fluid line along the transport path. The technical purpose of this transport installation is the transport of bulk product in the form of caps, with automatic adjustment of the air supply in the event of

  transport. A serious drawback of this trans-

  known port consists in that towards the end of the transport pipe, of the conveying fluid does not pass in the pipe

  transport from the secondary fluid line

  carrier that air was pumped into the transport line

  from the beginning to the point in question (see column 4, li-

  genes 54 to 62). But that means unnecessary air consumption.

  slightly high, that is to say an uneconomic operation, and on the other hand the heaps which block the transport pipe do not

  are only disaggregated with delay.

  Also known, according to German patent application 23 05 030, a pneumatic transport installation comprising a secondary transport fluid line which is laid parallel to the transport line and from which additional transport fluid s' flows into the transport line through valves. In the case of this installation

  where, considering the direction of flow, the pressure

  sion in the secondary transport fluid line exceeds for the first time the pressure in the transport line, the secondary line is closed, which makes it possible, at this location, to inject additional transport fluid into the transport line from secondary pipe. One drawback of this transport installation is that

  during transport, it cannot pass, in the main

  piping, additional transport fluid at only one point at a time in the entire pipeline, which is not sufficient for a

  trouble-free and energy-efficient operation of the facility

transport lation.

  We know from the German patent application

  24 03 533, another pneumatic transport installation, comprising

  carrying a secondary transport fluid line which is po-

  placed parallel to and from the transport line

  which of the additional carrier fluid passes through the line

  transport by valves. In this case, the passage of the fluid

  additional conveyor is controlled by the fact that considering the direction of flow, the first valve produces a blow of pressurized air in the transport line, then

  the next one, then the next one, and so on with a suc-

  increasingly rapid transfer of blows of air under pressure, as a function of the increase in the flow speed along the transport path. If the pulse of pressurized air

  reaches the end of the secondary fluid line

  conveyor, a pressure sensor causes repetition

  tition of the cycle. This transport system also has the disadvantage that at a given time, it is never exerted an influence on the transport process with additional conveyor fluid than at a single point of the transport path. We know from German patent application 24 12 142,

  a transport installation comprising a secondary pipe

  re of carrier fluid which is laid parallel to the

  transport line and from which fluid

  additional carrier is delivered to the transport line by means of injectors. In the case of this transport installation, the bulk product to be transported is introduced in portions into the transport pipe. Under these conditions, the various portions of bulk product would progress, it seems, "by pulses", "the material being alternately displaced and stopped". In connection with this pulaatory state in the transport line, additional transport fluid

  must penetrate in phase or out of phase, by injec-

  air tillers, in the transport line along the route.

  The injectors are controlled either by means of reservoirs

  see intermediate conveyor fluid along the transport path, either by means of a programmer. Apart from the fact that there is absolutely no indication in the document in question on the difference in effect which one obtains between a phase opening and a phase shifted opening - air injectors, nor on what we mean exactly by the term "phase", this command of the air injectors has the serious disadvantage that with it, it does not detect the p state "fasoirè at various points the driving

  transport and even that it does not reach the control device

  of no indication in return on the effect of the addition of additional transport fluid. However, this is an essential condition for the pulsation in the transport pipe,

  which is gradually absorbed by friction towards the end

  transport path, can be reactivated and maintained permanently. With this known transport installation, it must therefore be expected that the desired pulsation will undergo a

  additional attenuation or be completely removed by in-

  air jet at an incorrect time or at wrong points, this

  which results in the collapse of impulse transport.

  Finally, from German patent 25 50 164, a pneumatic conveying installation is known in which additional conveying fluid enters the conveying line by valves, from a secondary fluid line.

  conveyor installed parallel to the transport pipe, ins-

  tallation which corresponds to a large extent, as regards

  does its achievement and the goals sought, at the installation of

  transport known from German patent application 25 05 050.

  The difference is simply that it is arranged each time, between two valves which are provided for cutting the

  secondary line, several crossing points between the line

  secondary and the transport line. Here we find the

  agrees that at a defined time, additional carrier fluid

  can only enter the transport pipe in

  only one section of it. Upstream and downstream of this sec-

  tion, the sections of the transport line escape the in-

fluence of the system at this time.

  The object of the invention is to provide an installation for

  transport of the genus in question which allows pneluma-

  tick of bulk products, and in particular of bulk products having

  different characteristics in the same trans-

  port, with the maximum possible security against incidents, despite limited energy consumption and low wear of the installation.

  This object is achieved according to the invention that the detectors

  pressure sensors are electrical pressure transmitters

  which are connected by lines to an electric control unit

  tronic which performs a logical combination of the output signals

  tie of pressure transmitters with parameters entered as setpoints and characterizing the conditions

  transport, such as pressures, pressure differences, inter-

  times and frequencies, and which, when conditions are

  transport deviate from the prescribed conditions, ac-

  electrically operates the valves controlled by other lines.

  We can briefly summarize this solution by saying that in the installation proposed here, unlike all

  known installations, the principle of indication is used

  return to the control device of the modification of the

  transport process produced by a supply of transported fluid

  addition and that an adaptive regulation of the transport process is thus carried out simultaneously and over the whole

  transport route, which makes it possible to act locally-

  and for a specific purpose on the following transport process

  with regard to regulatory criteria that can be chosen at will.

  It is only with this proposal that it has been possible to solve with the same installation problems of

  different transport. Different types of transport problems

  rents result from the fact that in order to achieve favorable transport

  ble from the energy point of view and sparing the product for various materials, flow conditions must be achieved

  completely different in the conduct of transport. It is thus

  if certain powders can be transported with a maximum

  sluggishness and no risk of engorgement if the gas / solid matter is vibrated with the effect that

  on average over time, the adhesion forces between the parts

  cules are mostly overcome and thus avoided

  if an agglomeration of the product and its agglutination on the con-

  transport pickup. The vibration imparted at the start of the transport path is, however, damped by internal friction, as well as by friction on the tubular pipe along the transport path. Only the installation according to the invention makes it possible to maintain the pulsation by application at the correct rate.

  of compressed gas pulses at appropriate points in the con-

transport pickup.

  According to developments in the installation, indicated below, it is possible to make visible the pulsation which manifests itself by variations in pressure, for example by means of a recording device or an oscillograph and, from this way, to optically control the maintenance or reactivation of the pulsating state. Another advantageous possibility consists in using for the same purposes a functioning optimization program.

  automatically inside the controller.

  With other bulk products, pneumatic transport with vibration impressed on the gas / solid flow is not possible or not advantageous. However, for such bulk products, the aim is to obtain transport as uniform as possible at

  low speed and with a high load. In this case, the trans-

  port is all the more economical and saves all the more the pro-

  0 duit that one approaches more the limit of congestion in

  regarding transport speed and loading. A me-

  Blockage is signaled in the transport line by a local increase in the concentration of bulk product and, consequently, by an increased pressure drop in this area of the

  transport line. In the installation according to the invention,

  tion, as well as in installations according to the state of the

  differences in the pressures measured in the pipeline

  The transport systems for successive sections are certainly formed and compared with predetermined set values. But on the one hand, the most favorable reference values in each case can be adjusted without having to, as in installations of this kind according to the state of the art, take into account the limit values fixed by the construction

  mechanical and, on the other hand, in accordance with the development mentioned-

  born with the use of a recording device or a program

  optimization, it is possible here to determine the optimal value

  differential pressure male for each section of the con-

  transport pickup during transport.

  Finally, another development of the installation according to the invention also consists in that, to obtain transport

  the most favorable energetically, compared to the production flow

  bulk, the amount of gas flowing in the line

  secondary fluid is further detected and trans-

  form of an electrical quantity at the control device

electronic.

  An example of a transport installation

  according to the invention is shown in the drawing.

  A transport pipe 1 is loaded with bulk product by means of a pressure container 2 which is supplied with transport fluid by a supply pipe 3. The product is transported pneumatically to a separator 4. Parallel to the transport pipe a secondary conveyor fluid pipe 5 is placed which is in communication with a reservoir

  of conveyor fluid by connection 6. From the secondary pipe

  carrier fluid detach from the bypass lines

  tion 7 in which electrically controlled valves are mounted

  stick VI to V4. Downstream of the controlled valves, the bypass lines terminate, via check valves 8, at points of injection of conveyor fluid 9, each

  which a filter (not shown) is arranged. Under these conditions

  tions and as shown, several injection points

  of carrier fluid can form a group which is ali-

  additionally conveyed by a combined valve

  common mandate. Between the groups of injection points, as well as upstream of the first and downstream of the last point of injection of the conveying fluid, electrical pressure transmitters Si to S5 are arranged. From these pressure transmitters, signal lines 10 lead to an electronic control device where the pressure signals are used as

  as input signals. From this control device,

  signal genes 12 lead to electrically operated valves

  VI to V4 which are activated by the output signals of the device

  tif of order. For certain transport problems, it is

  advise to install in addition a quantity measuring device

  tity of gas 13 at the start of the secondary transport fluid line. This measuring device also sends the measured value electrically to the control device 11, via a signal line 14. As other input signals, parameters chosen at will or initial parameters can

  be introduced into the electronic control device 11.

  A transport cycle begins with filling the container.

  pient under pressure with the bulk product. Then, the flow valve (not shown) being closed, the pressure vessel is filled by pumping compressed gas through the supply line 3. The actual transport operation then begins, with the opening of the valve flow and

  maintenance of the conveyor fluid supply, by

  feed line 3, in the pressure vessel and at

start of transport line.

  In the event of vibratory transport, the conveying fluid

  is pulsed into the container under pressure

  sion 2 and at the start of the transport line via the supply line 3. The pressure variations thus produced give the bulk product transported a pulsating movement by which the internal adhesion forces between the particles are neutralized and, so, despite the heavy loading of the carrier fluid in bulk, there is no blockage in the transport line. The vibration to be observed in the transport hose would disappear

  very quickly due to internal friction along the path

  Jet, if it was not reactivated by periodic pulses

  compressed air in the transport hose. By brief openings of the controlled valves V1 to V4, pulses of compressed air are introduced at periodic intervals into the transport line through the injection points 9 in the event of vibratory transport. In this way, the desired vibration is

  maintained in the transport line to its end.

  So that the vibration is reactivated and is not dampened by

  compressed air pulses, it is necessary that the pulses

  compressed air at the various injection points,

  come into the transport line at the correct time. To this end, the electrical pressure transmitters 81 to S5

  signal to the operator or to the electronic control device

  as pressure variations in the transport hose. By systematic adjustment of the opening time and the switching instant of the controlled valves V1 to V4, it is then possible to determine the optimal operating mode. Is reached

  when pressure variations in the transmission line

  port are amplified, rather than weakened, by the effect of compressed air pulses. Once the optimal switching mode for the controlled valves Vl to V4 has been found, this setting of the transport installation is no longer modified,

  as long as the same bulk product is transported.

  For many products, vibratory transport is impossible or unfavorable. It is still essential, in order to protect the product to be transported and to reduce wear and tear on the installation, that transport takes place as slowly as possible. Under these conditions, there is always the

  risk of a threatening blockage in the transport pipeline.

  A threat of congestion at a point in the trans-

  wearing here causes increased pressure drop

  * of the conveying fluid. Electric pressure transmitters

  sion S1 to S5 signal to the electronic control device the pressure at the corresponding points in the supply line

  transport. If in a section of the transport line

  be two pressure transmitters, the maximum admissible drop

  pressure ble, which has been programmed in the electronic control device for each section of the transport line, is exceeded, the controlled valve which belongs to the transport section in question opens until, under

  the effect of the conveyor fluid introduced in addition to this sec-

  transport line, the pressure drop is

  lowered below the maximum admissible value.

  The carrier fluid quantity measuring device 13 signals the consumption of additional carrier fluid through the secondary carrier fluid line and thus allows inferences to be made about the expense in

  energy for specific transport conditions.

  The electrically operated valves are actuated

  kills by logical combination of the input signals introduced

  in the electrical or electronic control device,

  with regard to optimization criteria programmed or determined by the operator in the direction of the goals defined above. In order to be able to ascertain the reaction of the transport installation to modifications introduced by manipulation in the arrangement

  electronic control, the input signals,

  say the pressures in the transport line and, if applicable

  if necessary, the consumption of carrier fluid in the pipeline

  The secondary carrier fluid is recorded following interrogation or continuously on suitable recording devices, such as an oscilloscope, continuous line recorder, point recorder or printer. Of

  this way, not only setting the optimal conditions

  the transport of the installation is possible, but we can also carry out permanent monitoring of the installation

of transport in service.

  In the event of a change in the bulk product to be transported or

  of the transport section to be loaded from the feeding device

  ment in bulk product, we can replace in the short term, by program change, both the setting algorithms and the input parameters chosen at will. So,

  with a single transport facility, it is possible

  ble to transport the most diverse bulk products without incident according to different optimization criteria (for example the most energy-efficient or the slowest possible transport). the ideal adjustment of the transport installation can be carried out conveniently from a console

  without having to travel along the trans-

  port, since all information on the instantaneous status of the installation is displayed permanently or on demand on the control console. In this regard, it is advisable to provide feedback or acknowledgment lines (not shown in the drawing) between the valves Vl to V4

  and the control unit 11, signaling the effective state of communication

  tation of each individual valve, so that this switching state can also be viewed on the

* control panel, for example by means of indicator lights.

  This makes it possible to detect and locate in a particular way-

  rapid malfunction of valves, as well as installation malfunctions, provocation

  perhaps due to such a defect.

  As valves, it is quite sufficient,

  As a general rule, use valves that have simple-

  two positions, that is to say an "ON" position and an "OFF" position; but to further reduce the consumption of clean air, we can also use, accepting the implementation

  work of a more sophisticated and more costly control unit -

  valve, which by electrical control signals

  as appropriate, can be placed in an intermediate position

  diary or throttle defined or be open or closed from

continuously.

  The check valves and filters contained in the additional supply medium for transport medium prevent product from passing through this supply system

  additional and thus guarantee functional safety-

absolute installation.

Claims (6)

  1. Installation for the pneumatic transport of products   in bulk, comprising a secondary fluid line   carrier which is laid parallel to the transport line and is connected to it by valves controlled along the transport path, - as well as pressure sensors, arranged at intervals in the transport line, for the   control of these valves, characterized in that the detectors   pressure sensors are electrical pressure transmitters   Zion (Sl to S5) which are connected by lines (10) to a   electronic control unit (11) which performs a combination   its logic of the output signals of the pressure transmitters (S1 to S5) with parameters introduced as set values and characterizing the transport conditions, such as pressures, pressure differences, time intervals and frequencies, and which, when the actual conditions of the   transport deviate from the prescribed conditions, operate elect   three-fold valves controlled (Vl to V4) by others lines (12).   2-. Installation according to claim 1, characterized in that   that the control unit (11) is connected to at least one instrument   electrical measurement of gas flow.   Due to installation according to claim 1 or 2, characterized in that the control unit (11) comprises a control console which indicates optically and / or acoustically, jointly or on demand, the position of the control valves electric (Vl to V4).   L. Installation according to any one of claims 1   to 3, characterized in that the control unit (11) comprises recording devices for the permanent indication of   actual values obtained for the quantities measured.   5. Installation according to any one of claims 1   to 4, characterized in that the control unit (ll) contains several control programs corresponding to conditions   different predetermined transport.   6. Installation according to any one of claims 1   to 5, characterized in that the control unit contains an optimization program which automatically corrects the predetermined set values as initial parameters.   7. Installation according to any one of claims 1   to 6, characterized in that it is associated, with each electrically controlled valve (Vl - V4), several injection points of   transport fluid (9) on the transport line (1).   8. Installation according to any one of claims 1   to 7, characterized in that each fluid injection point   carrier (9) contains a filter.   9. Installation according to any one of claims 1   8, characterized in that a shut-off valve (8) is arranged on the fresh air side before each point of fluid injection transporter (9).