DE4313337C2 - Cyclone for the separation of solid particles from vertically downward gas / solid flows - Google Patents

Description

The invention has the separation of solid particles from gas / solid Currents according to the preamble of claim 1 to the subject.

Gas phase reactions in which fine-grained solids have a catalytic effect advantageously carried out in such a way that the catalyst particles ge in the vertical-upward directed gas flow carried essentially over time in a so-called remaining layer remain. A major improvement in cross-section Performance can be achieved by referring to the empty cross section Gas velocity significantly above the sink rate of a single kata lysator grain is increased. The state of motion that then arises with increasing gas speed, it approaches that of a pneumati more and more vertical-up promotion. Of course, with this driving style the entrained catalyst particles are separated from the gas stream.

According to the known prior art, this is done in that the vertical upward gas / solids flow first diverted into the horizontal and then in a known manner a separating cyclone with tangential on occurs is fed. With all known advantages of the latter driving style, he result in solid volume concentrations that are interesting from the point of view of reaction technology ions and flow vertically upwards unavoidable disadvantages for an optima le Reaction management are disadvantageous: Solids preferentially occurs in the wall zone mixing, which in turn entrains gas, d. H. an almost uniform ver because there is neither time for the catalyst particles, nor for the flowing through Adjust gas mixture. Tends to follow the chemical reaction to be carried out actions, the yield-reducing by-products become undesirable Quantity generated. To avoid these disadvantages described in recently proposed such a solid-catalyzed gas phase reaction in vertically downward gas / solids flow because doing so Flow forces and gravity in the same direction on the catalyst particles minimize both solids and gas back-pulling. The techni The implementation of such a driving style depends on a custom baren separation of the solid from the reaction gas at the bottom of one downward gas / solids flow. The term "usable" includes Solid-catalyzed gas phase reactions two essential aspects:

• 1. Effective separation of the solid from the gas at
• 2. gentle treatment of the solid.

The fulfillment of only the first requirement may be sufficient, e.g. B. in the case of Ver burning or gasification of coal, for example, because the burnt out solid Ash is then discarded, d. H. Abrasion or crushing of the ash parties keln is more or less irrelevant to the success of the process.

When catalytic cracking of gasoline raw materials z. B., on the other hand, becomes the catalyst moved back and forth between a reactor and a regenerator many times, d. H. the catalyst particles must have a large number of separation processes if possible Survive without breaking and with as little abrasion as possible.

Cyclone separators according to the known prior art meet at vertical downward solids / gas flow only the first of the two tasks ben, d. H. the effective separation, but not the second, d. H. the gentle treatment of the solid.

In the usual cyclone with tangential entry, the solid / gas flow has to stop the vertical are more or less redirected to the horizontal. Here the solid particles hit the manifold wall under considerable stress and therefore unavoidable breakage or abrasion.

Such a solution is used for a downward flowing liquid-solid Flow (hydrocyclone) disclosed in DE 27 12 763 A1.

According to the known prior art, tan would be an alternative to the cyclone potential inlet a cyclone with axial inlet from above in question, which is the immersion surrounds the pipe concentrically (see e.g .: Vauck / Müller: basic operations Mechanical process engineering, VCH publishing company Weinheim, 7th edition 1988, Fig. 4.48, p. 239) The one required for the separation of the solid In this cyclone variant, centrifugal force is generated by an axial inflow inserted fixed axial diffuser according to the type of fixed diffusers from Axial turbines or axial compressors generated.

In order for such a flow deflection to be effective, such axial cylinders have clones analogous to axial compressors or turbines idlers with a variety of Shovels. Because of their inertia, practically all solids then bounce particles on the guide vanes and therefore suffer abrasion or breakage. Conversely, the guide vanes suffer considerable wear as a result of the impacts the particles. This wear is likely to be the main reason why so-called Axial cyclones with axial guide wheels in the inlet are rarely used in practice could.

According to the known prior art are eccentrically from above in the Separation room opening supply lines for the solid / gas to be cleaned Flow provided for basic cylindrical shapes of the separating space. So US 1 734 677 relates to a continuously cylindrical gas scrubber with tangential inlet for the flow to be cleaned in the upper cover below an angle against the vertical axis of symmetry according to the drawing of 45 ° Similarly, DE-OS 15 03 601 discloses for one continuous cylindrical basic shape an eccentric inlet with a circular  Cross-section which opens from above into the cylindrical chamber in such a way that Side view of the axes of the cylindrical body and the off-center inlet enclose an angle that is pointedly pointed in the writing itself.

DE-AS 10 78 998 in particular discloses an inflow into a hydrocyclone that is at an angle significantly greater than 45 ° against the Cyclone axis opens laterally into the cylindrical cyclone body at the top. With such a cyclone, however, especially in the case of a solid / gas Flow the discontinuous change of direction of the diagonally flowing downward Strands of solid material a corresponding abrupt change in momentum abrasion-sensitive solids is harmful.

The invention described below has therefore set itself the task for Solids separation at the bottom of a vertically downward facing Gas / solids flow to provide a solution that:

• 1. causes an effective separation of the solid from the gas at the same time
• 2. gentle treatment of the solid.

This task is done according to the characteristic Features of claim 1 solved.

A further training as a cyclone is in claim 2 specified.

The device according to the invention is explained below in words and pictures using an example. Figure 1 shows a side view of the device, Figure 2 shows a radial section according to the viewing direction AA of Figure 1 and Figure 3 shows the cross-sectional shape of the inflow channel when it enters the cyclone cover.

As shown in Figure 1, the device contains a continuously conical separation chamber 1 for the separation of solid and gas, a central immersion tube 2 for the removal of the cleaned gas and a solid downpipe 4, which may be protected from the gas flow by a shielding cone 3 . According to the invention, the inflow of the gas / solid mixture takes place via an inflow channel 6 which opens out of the center of the cover 5 of the device. In the interest of the most gentle possible separation of solids, this inflow channel 6 is inclined against the axis of symmetry 7 of the device by an angle α, which is preferably less than 45 °.

This measure ensures that the vertical gas / solids flow with regard to the separating device, the one required for solids separation Swirl is obtained without the solid particles as in the known prior art a strong redirection within a channel, a grating or one Edge in the cyclone body with correspondingly high abrasion and wear of the Would be subject to particles.

Figure 2 shows a radial section through the device according to the patent, which reveals the arrangement of the vertical inflow channel 6 . In order to minimize particle wear and breakage by hitting walls, the patented device is inclined in the radial direction against the vertical inflow channel in such a way that the outer wall 1 a of the conical separating space 1 and the outer wall 6 a of the vertical inflow channel are aligned.

Figure 3 shows the design of the part of the vertical inflow channel 6, which opens into the device according to the patent, which is expedient for solids separation. Here, the inflow channel is designed with a triangular cross section, the outer, curved part of the triangular cross section exactly following the contour of the conical separating space 1 .

Reference list

1 conical separation room
1 a side wall contour of the conical separating space
2 central dip tube
3 shielding cones
4 solid downpipe
5 Cover of the separation room
6 off-center inflow channel
6 a lateral wall contour of the eccentric inflow channel
7 symmetry axis of the cyclone

Claims (2)

1. Cyclone for separating solids from vertically downward-directed gas-solid flows with an inflow channel for the gas-solid mixture opening eccentrically obliquely from above into the separation space, with the cleaned gas flow flowing out via a centrally arranged one at the upper end of the separation space Immersion tube and with outflow of the separated solids via a solids downpipe arranged at the lower end of the separating space, characterized in that the separating space ( 1 ) is continuously conical in that the outside rectilinear contour of the inflow channel ( 6 ) opening eccentrically from above into the cyclone body for the gas-solid mixture the elongated contour of the continuously conical separation space ( 1 ) follows, and that the inflow channel ( 6 ) for the gas-solid mixture in the side view against the vertical axis of symmetry of the cyclone makes an angle of less than 45 ° includes. 2. Cyclone according to claim 1, characterized in that the feed line for the gas-solid mixture opens into the upper cyclone cover ( 5 ) with a triangular cross-section, the contour of which follows the outside of the contour of the cyclone wall.