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EP-4437293-B1 - A DEVICE FOR ADJUSTING AND METERING OF DRY ICE GRANULATE FOR A DEVICE FOR MIXING SOLID PARTICLES OF DRY ICE WITH A FLOW OF GASEOUS MEDIUM

EP4437293B1EP 4437293 B1EP4437293 B1EP 4437293B1EP-4437293-B1

Inventors

  • BAKALA, Ludovít
  • GABRIS, PETER
  • KUBIS, IVAN

Dates

Publication Date
20260513
Application Date
20221123

Claims (2)

  1. A device (1) for adjusting and metering of dry ice granulate for a device for mixing solid particles of dry ice with a stream of a gaseous medium, comprising a body (2) having a granulate input section (5) and a granulate output section (6), between which a rotary element for transporting the granulate from the granulate input section (5) to the granulate output section (6) is arranged, wherein at least two rotary feeding elements (3) are arranged in parallel to each other in the body (2), wherein the feeding elements (3) are driven into rotation such that to rotate against each other relative to the direction of passage of the granulate from the granulate input section (5) to the granulate output section (6), where the rotary feeding elements (3) are formed as rotary rollers (32) comprising recesses (33) for transporting the granulate arranged around their periphery, these recesses (33) are oriented in the axial direction of the feeding element (3), wherein a shearing member (4) is arranged between the rotatable feeding elements (3), characterized in that the recesses (33) are arranged in at least two rows in succession along the length of the roller (32) of the feeding element (3), and each two adjacent rows of recesses (33) for transporting the granulate are offset relative to each other, and in that the shearing member (4) comprises at least one shearing edge (41) at each roller (32), where the position of the shearing edges (41) relative to the rollers (32) is in the range below the level of the connecting line (OS) of the axes of rotation of the feeding members (3), including the position of the shearing edges (41) at the level of the connecting line (OS), the angle ( γ ) between the connecting line (OS) of the axes of rotation of the feeding elements (3) and the face (42) of the shearing member (4) is in the range 0 to 45° and there is a gap (X) between the roller (32) and the shearing edge (41), the size of which is less than the smallest dimension of the granulate to be transported.
  2. The device according to claim 1, characterized in that a device (7) for grinding of dry ice granulate is connected to the output section (6) of the device (1), where a driven grinding roller (15) connected to a torque source is mounted in the body (71) of the device (7) for grinding of the granulate, where parallel to this grinding roller (15) a rotary support body (17) connected to a regulation for rotating this support body (17) is arranged in the body (71) of the device (7), wherein a second grinding roller (18) is rotatably mounted in the rotary support body (17), off-axis of this body (17), continually connected via a transmission (29) and the driven grinding roller (15) to the same torque source.

Description

Technical Field The invention relates to a device for adjusting and metering of dry ice granulate for a device for mixing solid particles of dry ice with a stream of gaseous medium. Background Art In the operation of dry ice cleaning machines using solid carbon dioxide (CO2) granulate, known as dry ice, often a reduction or a complete cut-off of the supply of particles from a container to the mixing system occur due to the tendency of the dry ice particles to clump together. This clumping can be up to the size of big dry ice clusters that form in the dry ice container of the equipment. The mixing system is herein understood to be the part of the machine where the dry ice particles are mixed with a stream of gaseous medium, typically a stream of air, after which the stream of dry ice particles is led into the blasting gun. The clumping of dry ice particles can occur for a number of reasons such as the method of production, degradation over time, poor storage, operating conditions and so on. In the same way, conventional dry ice pellet production typically produces cylindrical particles with an axial length several times the diameter of the particle, so for example, for a pellet diameter of 3 mm, the length of the pellet is typically 12 to 15 mm. This particle shape then adversely affects the quality, or consistency, of the feeding of the mixing systems. Various systems are known in the prior art to prevent clogging of the feeding ports of the devices, or transport rollers for removing the granulate from the container. Irregular feeding, also known as pulsation, is also a common problem with mixing systems working with dry ice granulate, which is most pronounced when the granulate consumption requirement is low. This pulsation is caused by the rotation of the mixing member and its shaped parts. These rotating mixing members contain separate chambers or pockets that are filled with granulate, from which the granulate is then transported by a stream of air. These rotating mixing members known in the prior art are disc or cylindrical in shape. The above problems are partially solved by the device described in the published application DE102009027974A1, which shows a device for adjusting and metering of dry ice granulate according to the preamble of claim 1, and by the device described in the published U.S. application 2019/0321942 A1, the particle blast apparatus includes a metering portion, a comminutor and a feeding portion. The metering portion and comminutor may each be configured to provide uniformity in the discharge of particles. The metering portion controls the particle feed rate, and may include a rotor, which may have V or chevron shaped pockets. The comminutor includes at least one roller which may be moved between and including a position at which the gap of the comminutor is at maximum and a position at which the gap is at minimum. The metering portion may discharge direction into the feeding portion without a comminutor being present. The comminutor may receive particles directly from a source of blast media without a metering portion being present. The device according to the said document, in the metering part, comprises a single rotating roller which rotates in one direction relative to a wiping edge on the body of said metering part. This rotating roller has chevron, "V", grooves, pockets, of "U" cross-section, formed along its length from each end thereof, which meet at the center of the cylinder at a peak which faces in the opposite direction to the direction of rotation of the roller. This arrangement is intended to ensure that the granulate in the grooves moves to their axial centre, providing a more uniform distribution of granulate along the length of the roller. Said wiping edge is then intended to ensure that the granulate is not forced into the grooves. Forcing of the granulate would lead to clumping of the granulate in the grooves and could lead to retention of the granulate in these grooves and unwanted irregular and unpredictable loss of the granulate, or clumps of granulate, into the next stages of the device. The metering device then controls the amount of granulate supplied into the mixing system instead of the feeding or mixing device itself. The feeding or mixing devices can then operate continuously in a speed range that does not cause pulsation of the dry ice particle stream, wherein the amount of dry ice particles may be small which would otherwise cause said pulsation due to the low speed of the feeding element of the existing mixing device. As mentioned above, it is not rare for clumps of dry ice to form in the dry ice container in the form of clusters which, due to their size, are unable to pass through, for example, the roller of the metering device described above. Other additional devices are then added because of the formation of such clusters, which mechanically break up such clusters. However, these additional devices then add to the complexity of the device and al