Device for feeding bulk material into a conveyor line in which the supplied bulk material is conveyed pneumatically

Abstract

The invention relates to a device (1) for feeding bulk material (2) into a conveying line (3), in which the fed bulk material (2) is conveyed pneumatically, comprising a conveyor screw (4) for transporting the bulk material (2) from a feed chamber (5) to a conveyor screw discharge (6), with a hollow screw shaft (7) for simultaneously conveying a propellant gas flow through the hollow screw shaft (7) to a front-end shaft outlet (8) for the propellant gas flow out of the screw shaft (7), and a mixing chamber (9) connected to the conveyor screw discharge (6), which has a conically tapered chamber inner wall (9a) in the conveying direction (F) with a downstream chamber discharge (10) for connecting the mixing chamber (9) to a conveying line (3), in which the bulk material (2) carried by the propellant gas flow is conveyed through the conveying line (3),and an outlet nozzle (11) for the propellant gas flow, which is connected in the flow direction (S) to the frontal shaft outlet (8) of the conveyor screw (4), which has a conical outer shell wall (11a) which is aligned concentrically to the inner chamber wall (9a) of the mixing chamber (9) and which has an outlet opening (11b) arranged in the center of the mixing chamber (9).

Description

[0001] The invention relates to a device for feeding bulk material into a conveyor line, in which the fed bulk material is conveyed pneumatically, comprising a conveyor screw for transporting the bulk material from a feed space to a conveyor screw discharge, with a hollow screw shaft for simultaneously conveying a propellant gas flow through the hollow screw shaft to a front-side shaft outlet for the propellant gas flow out of the screw shaft, and a mixing chamber connected to the conveyor screw discharge, which has a conically tapered chamber inner wall in the conveying direction with a downstream chamber discharge for connecting the mixing chamber to a conveyor line, in which the bulk material carried by the propellant gas flow is conveyed through the conveyor line.

[0002] The patent specification DE 471 297 A describes a compressed air conveying device with a drive screw, in which the compressed air required for conveying is introduced into a conveying pipeline through a hollow shaft of the drive screw.

[0003] Patent DE 1 169 370 A describes a pneumatic feeding device for loose bulk material with a feed screw, through whose hollow, cantilevered screw shaft a conveying gas is injected into a mixing chamber to convey the material in a conveying line connected to the mixing chamber. The generatrices of the inner wall of the outlet opening in the screw shaft are at different distances from the axis of the mixing chamber, so that the gas enters the mixing chamber in a helical manner as the feed screw rotates.

[0004] DD 1 43 753 A1 describes a feeding device for the pneumatic conveying of bulk material, consisting of a metering screw with a hollow, overhung screw shaft, a subsequent mixing chamber and an annular nozzle arranged around the metering screw, the channels or nozzle openings of which are arranged tangentially to the screw circumference, wherein the mixing chamber is composed of a cyclone which is coaxial with the metering screw and tapers in the conveying direction and has a tangential air inlet nozzle at the enlarged end, an adjoining cylindrical transition piece and an adjoining diffuser with a conical cross-section, wherein the extended end of the hollow screw shaft, the end of which is designed as a nozzle, projects into the cyclone and the nozzle ends in the region of the narrowest part of the cyclone.

[0005] DE 66 00 775 U describes a transport device for fine-grained or dust-like bulk materials with a conveyor screw connected to a feed hopper, the hollow shaft of which is connected to a compressed air line near the feed point and opens into a collecting chamber, from which the bulk material is conveyed by means of compressed air into a pipe connected thereto, wherein the end of the conveyor screw opening into the collecting chamber has a vortex attachment firmly connected to the screw shaft.

[0006] The object of the invention is to provide a device for feeding bulk material into a conveying line in which the supplied bulk material is conveyed pneumatically, with which the bulk material can be fed particularly effectively into the pneumatic conveying line.

[0007] The object is achieved by a device for feeding bulk material into a conveying line, in which the supplied bulk material is conveyed pneumatically, comprising: - a screw conveyor for transporting the bulk material from a feed chamber to a screw conveyor discharge, with a hollow screw shaft for simultaneously conveying a propellant gas flow through the hollow screw shaft to a frontal shaft outlet for the propellant gas flow out of the screw shaft, - a mixing chamber connected to the screw conveyor discharge, which has a conically tapered chamber inner wall in the conveying direction with a downstream chamber discharge for connecting the mixing chamber to a conveying line in which the bulk material carried by the propellant gas flow is conveyed through the conveying line, and - an outlet nozzle for the propellant gas flow, which adjoins the front-end shaft outlet of the conveyor screw in the flow direction and has a conical outer shell wall which is aligned concentrically to the inner wall of the mixing chamber, wherein the outlet nozzle has an outlet opening arranged in the center of the mixing chamber and the conveyor screw has a first screw section in which a screw flight of the conveyor screw has a pitch which is progressive in the conveying direction and the conveyor screw has a second screw section which is arranged downstream of the first screw section in the conveying direction and which is designed as a multiple screw flight.

[0008] The bulk material to be conveyed by means of the device according to the invention is generally, depending on the grain size, a powdery, granular or lumpy, possibly moist or slightly sticky mixture of solids, which is in a pourable form.

[0009] To transport such bulk material through conveyor lines, the bulk material is fluidized in a propellant gas stream during pneumatic conveying to make it transportable. The propellant gas stream serves the purpose of both fluidizing the bulk material, i.e., dynamically carrying it through the propellant gas stream, and acting as a carrier to transport the fluidized bulk material through the conveyor lines.

[0010] The device comprises a screw conveyor, which mechanically feeds the bulk material stored in a reservoir into the mixing chamber. The feed chamber, in which the bulk material is stored as a reservoir, can be formed, for example, by an inlet hopper located above the screw conveyor, so that the bulk material can flow from the inlet hopper to the screw conveyor by gravity.

[0011] The feed chamber can also be a silo or a feed line through which the bulk material can be fed to the screw conveyor. The screw conveyor can be supported on one side by means of a main bearing, so that the front end of the screw conveyor, which has the frontal shaft outlet, projects freely and is positioned axially centered in the area of ​​the screw conveyor discharge without bearings.

[0012] The mechanical feed of the not-yet-fluidized bulk material ends at the front end of the screw conveyor shaft outlet, where the bulk material enters the mixing chamber. Within the mixing chamber, the bulk material fed into the mixing chamber by the screw conveyor is fluidized to make it transportable through the conveyor line. Fluidization is achieved by injecting the propellant gas stream into the mixing chamber.

[0013] The propellant gas stream is injected into the mixing chamber via the hollow screw shaft of the conveyor screw. The inner wall of the mixing chamber is tapered in the conveying direction, so that the bulk material stream to be fluidized and the bulk material stream already fluidized in the propellant gas stream pass through a continuously decreasing flow cross-section until it enters the conveying line in the chamber discharge area.

[0014] By providing an outlet nozzle for the propellant gas flow, which is connected in the flow direction to the frontal shaft outlet of the conveyor screw, which has a conical outer shell wall which is aligned concentrically to the inner wall of the mixing chamber and which has an outlet opening arranged in the center of the mixing chamber, according to the invention, a device for feeding bulk material into a conveyor line can be created, with which bulk material is fed particularly effectively into a pneumatic conveyor line.

[0015] According to the invention, an outlet nozzle is arranged within the mixing chamber, which has an outlet opening located in the center of the mixing chamber. Due to the arrangement of the outlet opening in the center of the mixing chamber, the propellant gas flow is not only introduced into the mixing chamber centrally on the axis of symmetry of the mixing chamber, but the central position of the outlet opening also divides the mixing chamber along its axial extent into two mixing chamber zones that follow one another in the direction of flow. In a first mixing chamber zone located upstream of the outlet nozzle in the direction of flow, a suction annular space is formed, from which bulk material that has not yet been fluidized and emerges from the conveyor screw discharge is guided laterally past the conical outlet nozzle.Due to the propellant gas stream emerging from the outlet opening of the outlet nozzle and the conically tapered inner chamber wall, particularly in the area of ​​the second mixing chamber zone, which is located downstream of the outlet nozzle in the conveying direction, a Venturi effect occurs, which creates a negative pressure in the first annular mixing chamber zone, which sucks the not yet fluidized bulk material into the second mixing chamber zone. In this respect, the propellant gas stream emerging from the outlet opening of the outlet nozzle carries the not yet fluidized bulk material away from the screw conveyor discharge and draws it into the second mixing chamber zone for fluidization. This also relieves any back pressure at the screw conveyor discharge, so that the screw conveyor can subsequently convey the conveyed bulk material into the mixing chamber with comparatively lower performance.

[0016] The mixing chamber can thus have a suction annular space upstream of the outlet opening of the outlet nozzle in the conveying direction, which is laterally delimited on the one hand by the conical inner chamber wall and on the other hand by the conical outer shell wall of the outlet nozzle, wherein the mixing chamber has a mixing space downstream of the outlet opening of the outlet nozzle in the conveying direction, which continuously tapers conically towards the chamber discharge, in which mixing space an annular bulk material flow flowing axially past the outlet nozzle is fluidized by the propellant gas flow entering the center of the mixing chamber.

[0017] The division of the mixing chamber into a first mixing chamber zone upstream of the outlet opening of the outlet nozzle and a second mixing chamber zone downstream of the outlet opening of the outlet nozzle can be carried out exactly in half, so that the respective axial lengths of the first mixing chamber zone and second mixing chamber zone are the same.

[0018] In a modified embodiment, the division into a first mixing chamber zone and a second mixing chamber zone can optionally be made in a different ratio. For example, the axial length of the first mixing chamber zone can be somewhat larger and the axial length of the second mixing chamber zone somewhat smaller. Alternatively, the axial length of the first mixing chamber zone can be somewhat smaller and the axial length of the second mixing chamber zone somewhat larger. In any case, however, both an effective suction annular space must be maintained in the first mixing chamber zone and an effective mixing space, i.e. fluidization space, must be maintained in the second mixing chamber zone.

[0019] Due to the reduction in cross-section in the mixing chamber, the not yet or not yet fully fluidized bulk material is at least partially, and in particular largely, pre-accelerated by the conical suction annulus before it reaches the area of ​​the outlet opening of the outlet nozzle.

[0020] The conical outer shell wall of the outlet nozzle can be designed as a straight circular conical surface. The conical angle of the conical outer shell wall of the outlet nozzle can, in particular, be 10 degrees.

[0021] The conical inner chamber wall can be arranged coaxially at a constant distance around the conical outer shell wall of the outlet nozzle. Accordingly, the conical inner chamber wall can also be designed as a straight circular conical surface. The conical angle of the conical inner chamber wall can, in particular, also be 10 degrees. This creates a suction annular space having parallel lateral boundary walls. The conical inner chamber wall can, if appropriate, be designed as an inclined circular conical surface. This can be useful, for example, if, in a variant described in more detail below, the inner chamber wall is to run horizontally in a lower floor area.

[0022] The inventive design, in which the device has an outlet nozzle for the propellant gas flow, which adjoins the frontal shaft outlet of the screw conveyor in the flow direction, which outlet nozzle has a conical outer shell wall aligned concentrically with the conical inner chamber wall of the mixing chamber and which has an outlet opening arranged in the center of the mixing chamber, is particularly advantageous when starting up the screw conveyor at the beginning of a conveying operation and also when emptying the screw conveyor at the end of a conveying operation. Especially when emptying the screw conveyor, even when the screw conveyor is rotating slowly or even when the screw conveyor has already stopped, residual bulk material can be discharged from the mixing chamber due to the Venturi flow, as long as the propellant gas flow is maintained.

[0023] The outlet nozzle is preferably connected to the screw conveyor. In this respect, the outlet nozzle can be connected with its flow inlet directly to the frontal outlet of the screw conveyor's screw shaft. If the outlet nozzle is connected to the screw conveyor, the outlet nozzle rotates along with the screw shaft when the screw conveyor is driven to convey the bulk material.

[0024] If necessary, in a modified embodiment, the outlet nozzle can form part of the mixing chamber, whereby the frontal shaft outlet of the rotating screw shaft can be coupled in a gas-tight manner to the flow inlet of the fixed outlet nozzle, for example via a slip ring seal.

[0025] The outlet nozzle can, in particular as an attachment to the screw shaft of the conveyor screw, have at least one clearing blade extending from the outer casing wall of the outlet nozzle in the direction of the chamber inner wall.

[0026] To assist in clearing the first mixing chamber zone, i.e., the suction annulus, in particular, the outlet nozzle can have at least one clearing blade. The clearing blade can thus rotate through the suction annulus if the screw conveyor is rotationally driven. The clearing blade is positioned such that, when the screw conveyor rotates, a clearing effect occurs in the conveying direction of the bulk material.

[0027] The outlet nozzle can be removably attached to the screw shaft of the conveyor screw.

[0028] The outlet nozzle can be easily replaced thanks to a detachable attachment to the screw shaft. For example, an outlet nozzle can be attached to the screw shaft, which can be selected from a range of several differently designed outlet nozzles. For example, different outlet nozzles can be designed that differ, for example, in their nozzle lengths, their cone angles, and / or the cross-sectional sizes and / or cross-sectional shapes of the outlet openings.

[0029] The mixing chamber may have at least one inlet opening for an additional fluidizing gas flow in the region of a lower chamber wall half of the mixing chamber.

[0030] Despite a propellant gas stream introduced centrally into the mixing chamber via the outlet nozzle to fluidize the bulk material, bulk material may settle in the bottom area of ​​the mixing chamber. To prevent this, at least one inlet opening can be provided in the area of ​​a lower chamber wall half of the mixing chamber, through which an additional fluidizing gas stream can be fed into the mixing chamber.

[0031] The at least one inlet opening may preferably extend in the region of the lowest point of the mixing chamber or at least be positioned there.

[0032] If necessary, the mixing chamber can be reoriented from its horizontal position along the axis of symmetry of the conical mixing chamber so that the inner wall of the conical mixing chamber runs horizontally in its lower floor area. This has the advantage that bulk material that may tend to settle above the inlet opening does not have to be conveyed upwards against gravity by the fluidizing gas flow, but can be transported away in a horizontal direction in the floor area of ​​the inner wall of the chamber in the direction of flow.

[0033] In a specific embodiment, the at least one inlet opening can be formed on a separate intermediate flange that is inserted between a first flange of the conveyor screw discharge and a second flange of the chamber inlet. In addition, an inlet in the manner of a crescent-shaped distribution chamber can be assigned to the inlet opening. The crescent-shaped inlet can extend, in particular, over an angle of up to 180 degrees or less. The crescent-shaped inlet can have a larger chamber width in a central section than at its two edge regions. The inlet opening is preferably designed as an annular gap, which, in a particularly expedient embodiment, can be formed by an enlarged diameter of a tubular mixing chamber in the region of the chamber inlet, which in this region is not aligned with the edge of the conveyor screw discharge, but leaves a gap.

[0034] The crescent-shaped inlet expands the inlet cross-section of a bypass branch line, through which an additional fluidizing gas stream is supplied, at a discrete point on the intermediate flange toward the partially circular inlet opening, which can extend up to 180 degrees around a circumference. The bypass branch line can be connected to an inlet opening on the intermediate flange. Furthermore, any remaining cleaning fluid at the lowest point of the mixing chamber can be drained via the inlet opening, for example, after cleaning the mixing chamber, via a valve arranged in the bypass branch line, such as a ball valve. This allows for at least extensive residual drainage.

[0035] The screw shaft of the conveyor screw can have a connection opening for supplying the propellant gas flow at an end of the screw shaft opposite the frontal shaft outlet, to which connection opening a propellant gas flow feed pump is connected via a propellant gas main supply line, wherein a bypass secondary line branches off from the propellant gas main supply line, which is connected to the at least one inlet opening of the mixing chamber in order to branch off a partial air flow from the main air flow of the propellant gas, which forms the additional fluidizing gas flow.

[0036] The main propellant gas supply line connects the propellant gas flow pump to the channel formed by the hollow screw shaft. For this purpose, a fixed connection piece, to which the main propellant gas supply line is connected, can be connected to the rotating hollow screw shaft via a sealed rotary union.

[0037] A partial air flow of the propellant gas flow is branched off as a fluidizing gas flow via the bypass branch line and fed to at least one inlet opening, in particular the crescent-shaped gap.

[0038] The LPG flow pump can, for example, be a rotary lobe pump.

[0039] The device according to the invention can have a control device which is designed and arranged to control and / or regulate the rotational speed of the conveyor screw as a function of a pressure of the propellant gas flow, in particular the pressure of the propellant gas flow in the main propellant gas supply line.

[0040] For this purpose, a pressure sensor can be connected to the main propellant gas supply line. The pressure sensor can be designed to provide an electrical signal that provides information about the pressure currently prevailing in the main propellant gas supply line. This electrical signal can be evaluated by the control device, and depending on the evaluated signal, the control device can provide a control signal and send it to the motor, whose motor shaft is coupled to the conveyor screw. The motor is preferably an electric motor, in particular a three-phase motor, whose speed can be controlled via a frequency converter. The control signal provided by the control device can thus control the frequency converter.

[0041] The speed of the screw conveyor, and consequently the flow rate of bulk material into the mixing chamber, can thus be adjusted to the pressure of the propellant gas. The propellant gas can, in particular, be compressed air.

[0042] The device according to the invention can have a nozzle needle which is mounted in the outlet nozzle or in the hollow screw shaft in an axially adjustable manner and which cooperates with an orifice plate arranged in the outlet nozzle or in the hollow screw shaft in order to adjust the outlet speed at the outlet opening of the outlet nozzle or at the frontal shaft outlet by means of a cross-sectional change in the free flow cross-section between the orifice plate and the nozzle needle which occurs as a result of the axial adjustment of the nozzle needle.

[0043] The nozzle needle can be connected to a push rod that extends axially through the channel of the hollow screw shaft of the conveyor screw. Outside the hollow screw shaft, the push rod can be connected to a linear drive designed for automatic linear adjustment of the push rod, thereby moving the nozzle needle.

[0044] The conveyor screw has a first screw section in which a screw helix of the conveyor screw has a progressive pitch in the conveying direction and the conveyor screw has a second screw section downstream of the first screw section in the conveying direction, which second screw section is designed as a multiple screw helix.

[0045] To form the multiple screw flights, for example, three additional screw flights spaced at equal axial intervals from one another can be arranged in the conveying chamber defined by the side walls of the first screw flight. The three additional screw flights, for example, divide the original conveying chamber into four equally sized partial conveying chambers. The additional screw flights can have different numbers of turns. For example, one additional screw flight can only extend over 3 / 4 of a complete revolution and another additional screw flight can only extend over 1 / 2 of a complete revolution. The additional screw flights can each have a continuously changing radial flight width. For example, the respective radial flight width of the additional screw flights can be designed to increase counter to the direction of rotation of the worm shaft.

[0046] In a transition area between the screw conveyor discharge and a chamber inlet of the mixing chamber, a membrane flap can be arranged to prevent the bulk material from flowing back into the conveying chamber of the screw conveyor.

[0047] The diaphragm valve may have one or more diaphragm lips. Each diaphragm lip may have the shape of a circular ring sector. The diaphragm lips may be made of polyester urethane rubber (abbreviation AU according to ISO 1629).

[0048] The diaphragm flap can be arranged in the transition region between the conveyor screw discharge and the chamber inlet of the mixing chamber and extend in the first annular mixing chamber zone, i.e. in the suction annulus of the mixing chamber. Preferably, the diaphragm flap can extend only in the region of an upper chamber wall half of the mixing chamber, with no diaphragm lips being present in the region of a lower chamber wall half of the mixing chamber. The diaphragm flap can in particular extend over an angle of 180 degrees. Consequently, the upper section, which comprises the diaphragm flap, and the lower section, which optionally comprises an inlet opening, in particular in the form of a crescent-shaped gap for an additional fluidizing gas flow, can complement each other to form a closed circular circumference.

[0049] Specific embodiments of the invention are explained in more detail in the following description with reference to the accompanying figures. Regardless of the specific context in which they are mentioned, specific features of these exemplary embodiments may represent general features of the invention, even when considered individually or in further combinations.

[0050] They show: Fig. 1 a sectional view from the side of an exemplary embodiment of a device according to the invention, Fig. 2 a partial sectional view of the exemplary embodiment of a device according to the invention according to Fig. 1 in the area of ​​the mixing chamber with an outlet nozzle, Fig. 3 a side view of a conveyor screw of the device according to the invention according to Fig. 1 with an outlet nozzle detachably attached to the screw shaft and two separate outlet nozzles, which are designed differently, Fig. 4 a partial sectional view of the exemplary embodiment of a device according to the invention according to Fig. 1 in the area of ​​the screw conveyor drive with a screw conveyor bearing, a propellant gas flow feed pump and a bypass line connected to a main propellant gas supply line, Fig. 5 a schematic representation of a further embodiment of a conveyor screw in which the outlet nozzle or the screw shaft is provided with an axially adjustable nozzle needle, and Fig. 6 a sectional view of a membrane flap which is inserted in the transition area between the conveyor screw discharge and the chamber inlet of the mixing chamber together with an inlet opening in the form of a sickle-shaped gap.

[0051] In the Fig. 1 shows an exemplary device 1 for feeding bulk material 2 into a conveying line 3, in which the supplied bulk material 2 is conveyed pneumatically.

[0052] The device 1 has a conveyor screw 4 for transporting the bulk material from a feed chamber 5 to a conveyor screw discharge 6, with a hollow screw shaft 7 for simultaneously conveying a propellant gas flow through the hollow screw shaft 7 to a front-side shaft outlet 8 for the propellant gas flow out of the screw shaft 7.

[0053] The device 1 also has a mixing chamber 9 connected to the conveyor screw discharge 6, which has a conically tapered chamber inner wall 9a in the conveying direction F with a downstream chamber discharge 10 for connecting the mixing chamber 9 to a conveying line 3, in which the bulk material 2 carried by the propellant gas flow is conveyed through the conveying line 3.

[0054] The device 1 is characterized by an outlet nozzle 11 for the propellant gas flow, which adjoins the frontal shaft outlet 8 of the conveyor screw 4 in the flow direction S and has a conical outer shell wall 11a, which is aligned concentrically to the inner wall 9a of the mixing chamber 9 and which has an outlet opening 11b arranged in the center of the mixing chamber 9. The conveyor screw discharge 6, the outlet nozzle 11 and the mixing chamber 9 are in Fig. 2 is shown in more detail.

[0055] Arranged within the mixing chamber 9 is the outlet nozzle 11, which has an outlet opening 11b located in the center of the mixing chamber 9. Due to the arrangement of the outlet opening 11b in the center of the mixing chamber 9, the propellant gas flow is not only introduced into the mixing chamber 9 centrally on the axis of symmetry of the mixing chamber 9, but the central position of the outlet opening 11b also divides the mixing chamber 9 along its axial extent into two mixing chamber zones 9.1 and 9.2, which follow one another in the direction of flow. In a first mixing chamber zone 9.1, which is located upstream of the outlet nozzle 11 in the flow direction S, a suction annular space 12 is formed, from which bulk material 2 which has not yet been fluidized and which emerges from the conveyor screw discharge 6 is guided laterally past the conical outlet nozzle 11.Due to the propellant gas flow emerging from the outlet opening 11b of the outlet nozzle 11 and the conically tapered chamber inner wall 9a, particularly in the region of the second mixing chamber zone 9.2, which is located downstream of the outlet nozzle 11 in the conveying direction F, a Venturi effect occurs, which creates a negative pressure in the first annular mixing chamber zone 9.1, which sucks the not yet fluidized bulk material 2 into the second mixing chamber zone 9.2. In this respect, the propellant gas flow emerging from the outlet opening 11b of the outlet nozzle 11 carries the not yet fluidized bulk material 2 away from the screw conveyor discharge 6 and draws it into the second mixing chamber zone 9.2 for fluidization. This also relieves a back pressure at the screw conveyor discharge 6, so that the screw conveyor 4 can subsequently convey the conveyed bulk material 2 into the mixing chamber 9 with comparatively lower performance.

[0056] The mixing chamber 9 can thus have a suction annular space 12 upstream of the outlet opening 11b of the outlet nozzle 11 in the conveying direction F, which is laterally delimited on the one hand by the conical chamber inner wall 9a and on the other hand by the conical outer shell wall 11a of the outlet nozzle 11, wherein the mixing chamber 9 has a mixing space downstream of the outlet opening 11b of the outlet nozzle 11 in the conveying direction F, which continuously tapers conically towards the chamber discharge 10, in which mixing space an annular bulk material flow flowing axially past the outlet nozzle 11 is fluidized by the propellant gas flow entering the center of the mixing chamber 9.

[0057] The division of the mixing chamber 9 into a first mixing chamber zone 9.1 upstream of the outlet opening 11b of the outlet nozzle 11 and a second mixing chamber zone 9.2 downstream of the outlet opening 11b of the outlet nozzle 11 can be carried out exactly in half, so that the respective axial lengths of the first mixing chamber zone 9.1 and second mixing chamber zone 9.2 are the same.

[0058] As in Fig. 3, in the present embodiment, the outlet nozzle 11 is connected to the conveyor screw 4. Thus, the outlet nozzle 11, with its flow inlet 11c, is directly connected to the frontal shaft outlet 8 of the screw shaft 7 of the conveyor screw 4. When the outlet nozzle 11 is connected to the conveyor screw 4, the outlet nozzle 11 rotates together with the screw shaft 7 when the conveyor screw 4 is driven to rotate to convey the bulk material 2.

[0059] In Fig. 3 also shows that the outlet nozzle 11 can optionally have at least one clearing blade 14 extending from the outer jacket wall 11a of the outlet nozzle 11 in the direction of the chamber inner wall 9a.

[0060] In the Fig. In the embodiment shown in Figure 3, the outlet nozzle 11 is detachably attached to the screw shaft 7 of the conveyor screw 4. A first outlet nozzle 11.1, which is attached to the screw shaft 7 as shown, can thus be detached from the screw shaft 7 and replaced by a second outlet nozzle 11.2 or a third outlet nozzle 11.3. The respective outlet nozzle 11.1, 11.2, 11.3 can have an external thread 15, which interacts with a corresponding internal thread on the screw shaft 7, so that the outlet nozzle 11 can be easily screwed onto the screw shaft 7. The thread pitches of the external thread 15 and internal thread are designed opposite to the direction of rotation of the screw shaft 7, so that undesired loosening of the outlet nozzle 11 due to the rotation of the screw shaft 7 is reliably prevented.

[0061] By detachably attaching the outlet nozzle 11 to the screw shaft 7, the outlet nozzle 11 can be easily replaced. For example, one outlet nozzle 11 can be attached to the screw shaft 7, which can be selected from a series of several differently designed outlet nozzles 11.1, 11.2, 11.3. For example, different outlet nozzles 11.1, 11.2, 11.3 can be designed, which differ, for example, in their nozzle lengths, their cone angles, and / or the cross-sectional sizes and / or cross-sectional shapes of the outlet openings 11b.

[0062] Returning to Fig. 2, the mixing chamber 9 can have at least one inlet opening 16 for an additional fluidizing gas flow in the region of a lower chamber wall half of the mixing chamber 9.

[0063] In this specific embodiment, the at least one inlet opening 16 can be formed on a separate intermediate flange 17, which is inserted between a first flange of the screw conveyor outlet 6 and a second flange of the chamber inlet 18. In addition, the inlet opening 16 can be assigned an inlet 19 in the form of a crescent-shaped distribution chamber, as shown in Fig. 6. The crescent-shaped inlet 19 can, in particular, extend over an angle of up to 180 degrees or less. The crescent-shaped inlet 19 can have a larger chamber width in a central section than at its two edge regions. The inlet opening 16 is preferably designed as an annular gap, which, in a particularly expedient embodiment, can be formed by an enlarged diameter of a tubular mixing chamber 9 in the region of the chamber inlet 18, which in this region is not aligned with the edge of the conveyor screw discharge 6, but leaves a gap.

[0064] In Fig. 4 shows how the screw shaft 7 of the conveyor screw 4 can have a connection opening 13 for supplying the propellant gas flow at an end of the screw shaft 7 opposite the frontal shaft outlet 8, to which a propellant gas flow feed pump 20 ( Fig. 1) is connected via a propellant gas main supply line 21, wherein a bypass secondary line 22 branches off from the propellant gas main supply line 21 and is connected to the at least one inlet opening 16 of the mixing chamber 9 in order to branch off a partial air flow from the main air flow of the propellant gas, which partial air flow forms the additional fluidizing gas flow.

[0065] In Fig. 1 also shows a control device 23 which is designed and arranged to control and / or regulate the rotational speed of the conveyor screw 4 as a function of a pressure of the propellant gas flow, in particular the pressure of the propellant gas flow in the propellant gas main supply line 21.

[0066] The Fig. 5 shows a nozzle needle 24 which is mounted in the outlet nozzle 11 or in the hollow screw shaft 7 in an axially adjustable manner and which cooperates with an orifice 25 arranged in the outlet nozzle 11 or in the hollow screw shaft 7 in order to adjust the outlet pressure at the outlet opening 11b of the outlet nozzle 11 or at the frontal shaft outlet 8 by means of a cross-sectional change in the free flow cross-section between the orifice 25 and the nozzle needle 24 which occurs as a result of the axial adjustment of the nozzle needle 24.

[0067] The nozzle needle 24 can be connected to a push rod 28, which is guided axially through the channel of the hollow screw shaft 7 of the conveyor screw 4. Outside the hollow screw shaft 7, the protruding push rod 28 can be connected to a linear drive 29, which is designed for automatic linear adjustment of the push rod 28 in order to move the nozzle needle 24 by adjusting the push rod 28.

[0068] In Fig. 3 also shows how the conveyor screw 4 has a first screw section SA1 in which a screw helix 26 of the conveyor screw 4 has a progressive pitch in the conveying direction F and the conveyor screw 4 has a second screw section SA2 which is arranged downstream of the first screw section SA1 in the conveying direction F and which is designed as a multiple screw helix 26a.

[0069] To form the multiple screw flight 26a, three additional screw flights 26.1, 26.2, 26.3, spaced at equal axial intervals from one another, can be arranged in the conveying chamber defined by the side walls of the first screw flight 26. The three additional screw flights 26.1, 26.2, 26.3, for example, divide the original conveying chamber into four equally sized sub-conveying chambers. The additional screw flights 26.1, 26.2, 26.3 can have different numbers of turns. For example, one additional screw flight 26.1, 26.2, 26.3 can extend over only three-quarters of a complete revolution, while another additional screw flight 26.1, 26.2, 26.3 can extend over only half of a complete revolution. The additional screw flights 26.1, 26.2, and 26.3 can each have a continuously varying radial helix width. Thus, the respective radial helix width of the additional screw flights 26 can be adjusted.1, 26.2, 26.3 are designed to rise in the opposite direction of rotation of the worm shaft 7.

[0070] In a transition area between the screw conveyor discharge 6 and the chamber inlet 18 of the mixing chamber 9, a membrane flap 27 can be arranged to prevent the bulk material from flowing back into the conveying chamber of the screw conveyor 4. This is in Fig. 2 in an upper wall area of ​​the chamber inner wall 9a and in particular in Fig. 6 in a unique position together with the intermediate flange 17 in a sectional view along the section line AA ( Fig. 2) is shown.

[0071] The illustrated diaphragm flap 27 has a plurality of diaphragm lips 27a. Each diaphragm lip 27a can have the shape of a circular ring sector. The diaphragm lips 27a can be made of a polyester urethane rubber (abbreviation AU according to ISO 1629).

[0072] The diaphragm flap 27 is arranged in the transition region between the conveyor screw discharge 6 and the chamber inlet 18 of the mixing chamber 9 and extends in the first annular mixing chamber zone 9.1, i.e. in the suction annular space 12 of the mixing chamber 9. In the case of the present exemplary embodiment, the diaphragm flap 27 extends only in the region of an upper chamber wall half of the mixing chamber 9, with no diaphragm lips 27a being present in the region of a lower chamber wall half of the mixing chamber 9. The diaphragm flap 27 extends over an angle of 180 degrees. Consequently, the upper section, which comprises the diaphragm flap 27, and the lower section, which comprises an inlet opening 16 in the form of an annular gap for an additional fluidizing gas flow, complement each other to form a closed circular circumference.

Claims

[1] Device for feeding bulk material (2) into a conveying line (3), in which the supplied bulk material (2) is conveyed pneumatically, comprising: - a conveyor screw (4) for transporting the bulk material (2) from a feed chamber (5) to a conveyor screw discharge (6), with a hollow screw shaft (7) for simultaneously conveying a propellant gas flow through the hollow screw shaft (7) to a front-side shaft outlet (8) for the propellant gas flow out of the screw shaft (7), - a mixing chamber (9) connected to the screw conveyor discharge (6), which has a conically tapered chamber inner wall (9a) in the conveying direction (F) with a downstream chamber discharge (10) for connecting the mixing chamber (9) to a conveying line (3), in which the bulk material (2) carried by the propellant gas flow is conveyed through the conveying line (3), and - an outlet nozzle (11) for the propellant gas flow, which is connected in the flow direction (S) to the frontal shaft outlet (8) of the conveyor screw (4), said outlet nozzle having a conical outer shell wall (11a) which is aligned concentrically with the inner chamber wall (9a) of the mixing chamber (9), characterized by that the outlet nozzle (11) has an outlet opening (11b) arranged in the center of the mixing chamber (9) and the conveyor screw (4) has a first screw section (SA1) in which a screw flight (26) of the conveyor screw (4) has a progressive pitch in the conveying direction (F) and the conveyor screw (4) has a second screw section (SA2) arranged downstream of the first screw section (SA1) in the conveying direction (F), which second screw section is designed as a multiple screw flight (26a). [2] Device according to claim 1, characterized byin that the mixing chamber (9) has a suction annular space (12) which is arranged upstream of the outlet opening (11b) of the outlet nozzle (11) in the conveying direction (F), and which is laterally delimited on the one hand by the conical inner chamber wall (9a) and on the other hand by the conical outer shell wall (11a) of the outlet nozzle (11), and the mixing chamber (9) has a mixing space which is arranged downstream of the outlet opening (11b) of the outlet nozzle (11) in the conveying direction (F), and which continuously tapers conically towards the chamber discharge (10), in which mixing space an annular bulk material flow flowing axially past the outlet nozzle (11) is fluidized by the propellant gas flow entering the center of the mixing chamber (9). [3] Device according to claim 1 or 2, characterized by that the outlet nozzle (11) has at least one clearing blade (14) extending from the outer casing wall (11a) of the outlet nozzle (11) in the direction of the chamber inner wall (9a). [4] Device according to one of claims 1 to 3, characterized by that the outlet nozzle (11) is detachably attached to the screw shaft (7) of the conveyor screw (4). [5] Device according to one of claims 1 to 4, characterized by that the mixing chamber (9) has at least one inlet opening (16) for an additional fluidizing gas flow in the region of a lower chamber wall half of the mixing chamber (9). [6] Device according to claim 5, characterized byin that the screw shaft (7) of the conveyor screw (4) has a connection opening (13) for supplying the propellant gas flow at an end of the screw shaft (7) opposite the frontal shaft outlet (8), to which connection opening a propellant gas flow feed pump (20) is connected via a propellant gas main feed line (21), wherein a bypass secondary line (22) branches off from the propellant gas main feed line (21) and is connected to the at least one inlet opening (16) of the mixing chamber (9) in order to branch off a partial air flow from the main air flow of the propellant gas, said partial air flow forming the additional fluidizing gas flow. [7] Device according to one of claims 1 to 6, characterized by a control device (23) which is designed and arranged to control and / or regulate the speed of the conveyor screw (4) as a function of a pressure of the propellant gas flow, in particular the pressure of the propellant gas flow in the propellant gas main supply line (21). [8] Device according to one of claims 1 to 7, characterized by a nozzle needle (24) which is mounted in the outlet nozzle (11) or in the hollow screw shaft (7) in an axially adjustable manner and which cooperates with an orifice plate (25) arranged in the outlet nozzle (11) or in the hollow screw shaft (7) in order to adjust the outlet pressure at the outlet opening (11b) of the outlet nozzle (11) or at the frontal shaft outlet (8) by means of a cross-sectional change in the free flow cross-section between the orifice plate (25) and the nozzle needle (24) which occurs as a result of the axial adjustment of the nozzle needle (24). [9] Device according to one of claims 1 to 8, characterized by that in a transition area between the conveyor screw discharge (6) and the chamber inlet (18) of the mixing chamber (9) a membrane flap (27) is arranged which prevents the bulk material (2) from flowing back into the conveying chamber of the conveyor screw (4).

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