FR2499035A1 - PROCESS AND DEVICE FOR HANDLING A BULK PRODUCT - Google Patents

Abstract

The bulk material is stored in a storage container (1) whose lower end (5) is connected to an outlet line (8). A compressor (12) feeds two air supply lines (3, 9) which can each be shut off by a valve (14, 15) controlled by a control device (17). The first air supply line (3) opens out at several points into the lower, tapered part (2) of the container (1). The second air supply line (9) opens out into the outlet line (8). The two valves (14, 15) are controlled in such a way that the compressed air flows alternately through the first and the second air supply lines (3, 9). While the air flows through the first air supply line (3) into the lower part (2) of the container, the bulk material thereby fluidised flows through the lower end (5) of the container into the outlet line (8), no risk of blockage occurring whatsoever. While the air flows through the second air supply line (9) into the outlet line (8), the bulk material is blown through the latter to the site of use. In this case, a valve (7) arranged between the outlet line (8) and the lower end (5) of the container prevents reversal of the flow direction. By means of the alternate blowing of compressed air into the lower part (2) of the container and into the outlet line (8), a particularly high conveying capacity is surprisingly achieved.

Description

Process and device for handling a bulk product.

 The present invention relates to a method for handling a bulk product, in particular premixed and dry plaster mortar or flat mortar, from a tank with a conical lower part through an outlet pipe connected to its lower end, according to which compressed air is blown into the conical lower part of the tank and into the outlet pipe in order to fluidize the bulk product so that it flows through the lower end of the tank into the outlet pipe through which it is blown, a stop member preventing the reversal of the flow.

 The invention also relates to a device for implementing this method, comprising a conical tank, a first air supply line with several outlet openings in the conical lower part of the tank, an outlet line connected to the bottom end of the tank, a second supply line fitted with a nozzle opening into the line, a stop member disposed between the bottom end of the tank and the outlet line, and a source of compressed air connected to the two supply lines.

 Application DE-GM 79 22 159 describes a process and a device of this kind. According to this known method, compressed air is blown simultaneously into the conical lower part of the tank and into the outlet pipe. To this end, the known device comprises a compressor which is connected to a first air supply pipe opening at several places on the periphery in the conical lower part of the tank, and to a second air supply pipe provided a nozzle and opening into the outlet pipe. A check valve which opposes a reversal of the current, that is to say the return of the air flow and of the bulk product from the outlet pipe to the reservoir is housed in a spacer which connects the lower end of the reservoir to the outlet pipe. the disadvantage of the known solution lies in the fact that the bulk product flows only slowly from the reservoir in the outlet pipe and that the flow is interrupted relatively frequently due to the bottlenecks appearing essentieLlement at the lower end of the tank, which allows only low yields to be obtained.

 This is why the invention proposes to ensure a high flow rate by rapid and reliable collapse of the bulk product.

 The invention makes it possible to achieve this object by a method of the type mentioned at the start, characterized in that the compressed air is blown alternately in the lower part of the tank and in the outlet pipe.

 As for the device allowing this process to be implemented, it will essentially be characterized by a stop device for selectively isolating the two supply lines, and by a control device which controls the stop device so that the compressed air supplied by the compressed air source alternately passes through the first and second supply lines.

 The invention takes advantage of the astonishing fact that the bulk product flows quickly and reliably from the reservoir into the outlet pipe and that there is no risk of clogging, if the compressed air is not not blown simultaneously, but alternately in the lower part of the tank and in the outlet pipe.

It has surprisingly been found that the yield with this intermittent and progressive feeding is greater than that obtained with the known feeding, even if in the latter case there is no waterlogging proper. This fact is already surprising, since it should be supposed that it is possible to convey more material in a continuous process than by a progressive and discontinuous flow. The reasons why the known process only allows relatively small volumes to be avoided. It is assumed that the compressed air which is constantly blown into the outlet pipe slows the flow of bulk material from the tank. This is based on the fact that the check valve certainly prevents proper direction of movement of the current, but cannot prevent the pressure conditions prevailing between the outlet pipe and the lower part of the tank from being unfavorable to the flow of the bulk product, if the compressed air is blown simultaneously into the latter.

 The invention is described in more detail with the aid of an exemplary embodiment with reference to the accompanying drawing.

 The only figure is a schematic representation showing a device for handling a bulk product.

 The device comprises a reservoir 1 provided at its upper part with an opening capable of being closed off for filling the bulk product and the lower part 2 of which ends conically towards the bae.

A first air supply pipe 3 has at its end an annular pipe extending in a circular fashion around the part 2 of the tank, while four connection pipes 4 arranged at the same distance from each other leave the pipe ring to open inside the tank. The lower end 5 of the reservoir is connected to an outlet pipe 8 leading to the point of use (not shown) by means of a connector 6, in which are housed a stop member for closing the reservoir in in the event of non-use as well as a check valve 7. A second air supply line 9 which, at its outlet, has an injection nozzle 10 oriented in the direction of the nux 11 leading towards the point of use, opens out in driving 8.

A compressor 12 for the production of compressed air is connected to the air supply lines 3 and 9 as well as to a pressure relief line 13. Each of the three lines 3, 9 and 13 can between isolde-au by means of a solenoid valve 14, 15 and 16. The three solenoid valves 14, 15 and 16 are controlled by means of a control device 17 which is connected to a pressure switch 19 and provided with a time delay relay 20 The pressure switch 19 controls the air pressure in the line 18 connecting the compressor 12 to the three valves 14 to 16 and sends a signal to the control unit 17 when this pressure falls below a predetermined limit value chosen in the range from 0.4 to 1.2 bar for example.

 In the figure, the valve 14 is open and the valves 15 and 16 are closed. The device's operating mode is described in detail below, based on these valve positions. The control unit 17 having opened the valve 14, the latter remains open for a predetermined time by the time delay relay 20. This time is adjusted according to the fluidity of the bulk product and is conveniently within a range of 2 at 10 seconds.

During this period, the compressed air supplied by the compressor 12 passes through the supply line 3 in the lower part 2 of the tank, so that the bulk product therein is fluidized and flows through the lower end 5 of the tank and the open check valve 7 in the connector 6 to reach the outlet pipe 8. At the end of the period predetermined by the time delay relay 20, the control unit 17 closes the valve 14 and opens the valve 15. The compressed air supplied by the compressor 12 thus passes through the supply line 9 and the nozzle 10 into the outlet line 8. The compressed air blows the bulk product through the line outlet 8 to the point of use, while the check valve 7 prevents compressed air from passing from the pipe. outlet 8 in the lower part of the tank 2. While the bulk product is blown through the outlet line 8 by compressed air, the pressure in the line 18 controlled by the pressure switch is greater than the predetermined limit value. As soon as the compressed air has blown the bulk product out of the outlet line 8 or at least has ensured its routing, the pressure drops below the limit threshold, the pressure switch 19 delivers a signal to the apparatus for control 17 which closes the valve 15 and opens the valve 14 again, so that the valves resume the positions shown in the figure and that the compressed air is again blown into the lower part 2 of the tank for a period determined by the timing relay 20. To interrupt or stop the flow, the valves 14 and 15 are closed and the valve 16 closed during the flow is opened by the control unit 17, so that the compressed air supplied by the compressor 12 pass through the discharge line 13 in the open air. The interruption of the flow rate by closing the valves 14 and 15 and opening the valve 16 can for example be triggered by a level sensor (not shown) arranged in a reservoir at the end of the outlet pipe 8.

 LB closing the valve 15 as a function of the pressure is particularly advantageous, when the bulk product conveyed is heavy and difficult to fluidize, since there is then a significant pressure drop during the blowing of the bulk product through the supply line. outlet 8. On the other hand, when the bulk product conveyed is light and particularly easy to fluidize, the pressure drop is low, which makes reliable control more difficult. In this case, it is particularly advantageous to blow the compressed air into the outlet pipe 8 not as a function of the pressure, but for a predetermined period, conveniently chosen between 1 and 10 seconds.

To this end, the control 17 can be provided with two timing relays which determine the periods at which the compressed air passes respectively through the first and second supply lines 3 and 9. It goes without saying that the compressed air can pass successively through the two supply lines 3 and 9 for periods of the same duration. This has the advantage of requiring only one time delay relay, but has the disadvantage of not allowing one to choose different optimal periods for fluidizing the bulk product in part 2 of the tank and for blowing the product @ it an bulk through outlet pipe 8.

 In place of the three solenoid valves 14, 15 and 16 cn can also use other types of valve, shutters or taps which, instead of being electrically controlled, can also be pounded by pneumatic means. In addition, the two solenoid valves 14 and 15 can be replaced by a three-way valve (with adequate piloting) or all three valves 14, 15 and 16 by a single multi-way valve.

 As with the check valve described in application DE-GM 79 22 159, the check valve 7 may include a suspended spherical body? a chain in connection 6 which is raised in the event of a reversal of the current and closes a constriction in this connection. Instead of the check valve, it is also possible to use a different stop member, for example a valve controlled by the control device 17, which opens and closes this stop member together with the solenoid valve 14. A stop member controlled by the control device 17 has the advantage over the check valve 7 is closed exactly during the period during which the compressed air passes through the outlet line 8, while the check valve 7 closes only when an air flow sufficient to lift the body of the valve passes against current towards the lower part 2 of the tank, and opens again when there is a strong pressure drop in the outlet pipe 8 (after the blowing of the bulk product).

 Instead of the pressure switch 19, a pressure sensor can also be provided, the measurement variable of which is compared with a predetermined limit value by means of a comparator mounted in the control device 17. In addition, the pressure switch 19 or the sensor pressure can measure the pressure not in the line 18, but in the supply line 9 or in the inlet element of the outlet line 8 connected to the fitting 6.

 Instead of being carried out by the control device 17, it is also possible to manually actuate the closing of the solenoid valves 14 and 15 and the opening of the solenoid valve 16 to interrupt or stop the flow.

 As is apparent from the figure, the reservoir 1 can be supported by a frame, and this in an appropriate manner by means of a retaining device secured to the reservoir or fixed to the frame allowing exchange of the reservoir. The power supply and control group of the device which comprises the lines 3, 9, 13 and 18, the solenoid valves 14 to 16, the pressure switch 19 and the control unit 17 can also be arranged in the space between the lower part 2 of the tank, the connector 6 and the frame, so that it is not laterally projecting from the shell of the tank.

 Empty tanks can be filled at a central station instead of being filled on site. If it is not desired to provide a supply and control group for each tank which is integral therewith, it can then be fixed to the frame and provide removable tubular connections at the points designated by the references 21, 22 and 23 of the pipes. supply 3, 9 and the outlet pipe 8, so that the supply and control group as well as the outlet pipe 8 can be detached from the tank 1 and reconnected to a full tank newly placed in the frame . The tanks can between conveniently transported in a horizontal position by means of trucks to the central station and brought back to the site.

 As goes without saying and as it already follows from the above, the invention is in no way limited to that of its modes of application, any more than those of the embodiments of its various parts, having been more particularly envisaged; on the contrary, it embraces all its variants.

Claims (11)

 1. Method for handling a bulk product, in particular premixed and dry plaster mortar or plaster mortar, from a tank (1) with a conical lower part through an outlet pipe (8 ) connected to its lower end (5), according to which compressed air is blown into the conical lower part (2) of the tank and into the outlet pipe (8) in order to fluidize the bulk product so that it flows through the lower end (5) of the reservoir into the outlet pipe (8) through which it is blown, a stop member (7) preventing the reversal of the flow, characterized in that l compressed air is blown alteinatively into the lower part (2) of the tank and into the outlet pipe (8).  2. Method according to claim 1, characterized in that the compressed air is blown for a predetermined period in the lower part (2) of the tank, then in the outlet pipe (8) until the pressure of the air in the outlet pipe (8) or in the supply pipe (9, 18) leading to the latter falls below a predetermined limit value.  3. Method according to claim 1, characterized in that the compressed air is blown for a predetermined duration respectively in the lower part (2) of the tank and in the outlet pipe (8).  4. Method according to one of claims 1 to 3, according to which the compressed air is supplied by a compressor (12), characterized in that the compressed air is sent to the open air (13) at the end of the routing process.  5. Device for implementing the method according to claim 1, comprising a tank (1) with a conical lower part, a first air supply pipe (3) with several outlet openings (4) in the conical lower part (2) of the tank, an outlet pipe (8) connected to the lower end (5) of the tank, a second supply pipe (9) provided with a nozzle (10) opening into the pipe ( 8), a stop member (7) arranged between the lower end (5) of the tank and the outlet pipe :: 8), and a source of compressed air (t2) connected to the two supply pipes ( 3.9), characterized by a stop device (4, 15) for selectively isolating the two supply lines (3.9), and by a control device (17) which controls the stop device (14, 15) so that the compressed air supplied by the compressed air source (12) passes alternately through the first (3) and the second supply line (9).  6. Device according to claim 5, characterized in that the stop device (14, 15) is constituted by two solenoid valves (14, 15), each being mounted in one of the two supply lines (3, 9 ).  7. Device according to claim 5, characterized in that the amt stop device constituted by a multi-way stop member,  8. Device according to any one of claims 5 to 7, for the implementation of the method according to claim 2, characterized in that the control device (17) comprises a timing relay (20) which determines the duration during which the compressed air passes through the first supply line t3), and that it is connected to a pressure switch (19) which against the air pressure at the inlet of the outlet line (8) or in the second supply line (9) or on their connection (18) with the compressed air source (12) and triggers the closing of the second supply line (9) and the opening of the first supply line supply (3) in the event of a fall below a predetermined limit value.  9. Device according to any one of claims 5 to 7, for the implementation of the method according to claim 3, characterized in that the control apparatus comprises two timing relays which determine the durations during which the air tablet passes through the first and second supply lines, respectively.  10. Device according to any one of claims 5 to 9, potu. the implementation of the method according to claim 4, in which the source of compressed air consists of a compressor (12, characterized by a discharge line (13) connected to the compressor (12), open at its end and capable of being isolated by means of the stop device (14, 15, 16), the control device (17) controlling the stop device (14, 15, 16) so that the discharge line (13) is closed during the conveying process and that the two supply lines (3, 9) are closed and the discharge line (13) is open if the routing process is interrupted or terminated.  11. Device according to any one of claims 5 to 10, characterized in that the stop member (7) disposed between the lower end (5) of the tank and the outlet pipe (8) is controlled by the control device (17), and so that it is exactly in the closed and open positions when the first supply line (9) is closed and open.