Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
  • B04B—CENTRIFUGES
  • B04B1/00—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles
  • B04B1/20—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles discharging solid particles from the bowl by a conveying screw coaxial with the bowl axis and rotating relatively to the bowl
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
  • B04B—CENTRIFUGES
  • B04B15/00—Other accessories for centrifuges
  • B04B15/12—Other accessories for centrifuges for drying or washing the separated solid particles
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B17/00—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement
  • F26B17/10—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by fluid currents, e.g. issuing from a nozzle, e.g. pneumatic, flash, vortex or entrainment dryers
  • F26B17/107—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by fluid currents, e.g. issuing from a nozzle, e.g. pneumatic, flash, vortex or entrainment dryers pneumatically inducing within the drying enclosure a curved flow path, e.g. circular, spiral, helical; Cyclone or Vortex dryers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B17/00—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement
  • F26B17/24—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by shooting or throwing the materials, e.g. after which the materials are subject to impact
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B3/00—Drying solid materials or objects by processes involving the application of heat
  • F26B3/02—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air
  • F26B3/10—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour carrying the materials or objects to be dried with it
  • F26B3/12—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour carrying the materials or objects to be dried with it in the form of a spray, i.e. sprayed or dispersed emulsions or suspensions
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B5/00—Drying solid materials or objects by processes not involving the application of heat
  • F26B5/08—Drying solid materials or objects by processes not involving the application of heat by centrifugal treatment
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B7/00—Drying solid materials or objects by processes using a combination of processes not covered by a single one of groups F26B3/00 and F26B5/00

Definitions

• the invention relates to a device for dewatering and drying of suspensions according to the preamble of claim 1.
• a dewatering and drying device is known from EP 0591299.
• the radially sprayed moist solid particles with a size of 0.3-3 mm at the ejection of the centrifuge are deflected in the axial direction of the centrifuge by suitable means, for example deflection surfaces or by a suitable gas flow and guided by the gas flow on a spiral trajectory in the drying room.
• the sprayed solid particles are washed around and dried by the drying gas at a high relative speed.
• the drying room is a concentric annular space. It is formed from the outer dryer housing, the inner rotating drum shell of the centrifuge or an inner housing surrounding the drum and the two housing end walls. The outer walls of the concentric drying room are fixed and have to be sealed at least at one point against the rotating parts of the internal centrifuge.
• the rotary seal between the centrifuge rotor and the surrounding dryer housing must bridge and withstand a high relative speed, a gas differential pressure between the inside and outside, and displacement movements from thermal expansion and vibrations.
• the escape of gases from the The interior of the dryer or the entry of false air from the outside in should be prevented or minimized by the seal.
• the gap width must be chosen so large that, despite thermal expansions and displacements of the dryer housing, the non-contact seals do not tarnish.
• Another disadvantage is that the gap also changes due to vibrations of the dewatering centrifuge inside the dryer, since the rotating and the non-rotating part of the seal are attached to different seal supports.
• the object of the invention in contrast, is to avoid operational disturbances in a drainage and drying device of the type mentioned, caused either by leaks between the dryer housing and centrifuge or by deposits and incrustations of solid particles, by constructive measures.
• the invention provides for mechanically fanned turbulence vortex rolls of the drying gas to produce a fine dispersion of the pre-dewatered solid, to distribute the dispersed solid particles well in the drying gas, to distribute the particle concentration in the drying gas as evenly as possible and to blow away any incrustation layers that build up.
• concentration of the dispersed, moist, small particles in the dryer room should be uniform and low, and the relative speed of the hot gas with respect to the particles should be as high as possible in order to ensure that the moist solid particles dry off very quickly in flight.
• elements protruding into the dryer space on the outside of the rotating centrifuge drum which light up the gas flow and ensure strong turbulence in the vicinity of the encrusted surfaces in the dryer space or on the deflection surfaces.
• the surfaces of the active chamber walls in the dryer can be polished or anti-adhesive to help prevent incrustation.
• Perforated walls through which gas flows are also suitable for preventing incrustations caused by moist, sticky solid particles if the inflowing hot gas keeps the sticky particles away from the walls until the particles have dried sufficiently on their surface and then lose their tendency to adhere at a lower moisture content.
• the tendency to adhesion is particularly high in certain moisture ranges and must be overcome in a split second in flight.
• the invention also provides for the radial end walls of the dryer housing to be sealed off from the rotating outer surface of the centrifuge by means of a rotary seal, as a result of which the sealing gap can be kept very closely without the risk of mechanical contact between the rotating and non-rotating active surfaces of the rotary seal comes and their damage and destruction.
• Another advantage of the rotary seal is that even uncontrollable larger displacement and expansion movements of the dryer housing during the heating or cooling phase of the centrifuge dryer or stronger vibrations during operation do not affect the sealing function despite the narrow gap of the rotary seal.
• the narrow sealing gap almost completely prevents internal gases or solids from escaping, or the entry of false air into the inert drying gas.
• Fig. 1 is a dewatering and drying device (hereinafter as
• Fig. 2 add a centri dryer with baffles in the dryer room in
• Fig. 3 shows the dispersion zone of a centrifuge dryer with rotating
• Fig. 4 shows the dispersion zone of a centrifugal dryer with rotating
• Fig. 5 shows a combination of cleaning and turbulence blades
• Fig. 6 shows a combination of turbulence and transport blades for
• Fig. 10 is a non-contact labyrinth seal for one
• Fig. 11 is a non-contact thread conveyor seal for a
• Fig. 12 is a non-contact threaded conveyor seal with a tip thread
• Fig. 13 is a non-contact seal with flat grooves.
• the dewatering and drying device (“centrifuge dryer”) shown in FIG. 1 has a solid-bowl screw centrifuge 1 of known design in the example shown. Instead of the solid bowl screw centrifuge shown, other ones for the dewatering of suspensions, e.g. Slurries, suitable centrifuges, for example sieve jacket screw centrifuges or 3-phase separating centrifuges, in which one phase is to be dried.
• suitable centrifuges for example sieve jacket screw centrifuges or 3-phase separating centrifuges, in which one phase is to be dried.
• the solid-bowl screw centrifuge 1 referred to below as the "dewatering centrifuge” or “centrifuge” for short, has a rotating one Drum 2, which is rotatably mounted on roller bearings 3 at its axial ends.
• the drum 2 tapers conically at one or both ends and is provided at its tapered end with discharge openings 4 which form the discharge zone 5 for the pre-dewatered solid 6.
• the suspension fed through a pipe 7 into the interior of the centrifuge 1, for example liquid sludge 8, is separated in the centrifuge 1 due to the centrifugal force into a solid 6 and a clarified liquid 9 which at the other end of the drum shell 2 from the centrifuge 1 in a separate housing 10, the Zen chute, is hosed down.
• the dryer directly surrounding the centrifuge 1 is formed by an outer dryer housing 11 and an inner housing 12 surrounding the rotating drum 2 or by the drum 2 itself, and by the two end walls 13 and 14.
• the drying gas 15 is introduced through a hot gas shaft 16 into the dryer space 17, for example tangentially, flushes around the solid 6 dispersed in the form of particles, which is deflected in the axial direction by the impact cone 18, and transports the drying solid particles in spiral paths through the concentric annular space 19 to the outlet channel 20 of the dryer housing 11. From here, the drying gas 21 loaded with the dried solid particles flows through a pneumatic delivery line (not shown) to a solid matter separator and is separated there again into gas and solid matter heap.
• a perforated plate 22 for example in the form of a cone, through which the hot gas 15 flows, is installed.
• the perforated plate 22 can consist of a conical surface or can be composed of several sections with different cone angles, hole shapes, slots, free opening cross sections or partial solid sheet sections in order to achieve the effects mentioned.
• the flow-through distribution plate 22 can also have a bowl-shaped, cylindrical or flat shape that deviates from the cone, or can be composed of different shapes.
• FIG. 2 shows a combined centrifuge dryer with built-in guide elements 25, 26 in the concentric annular space of the dryer.
• the centrifuge dryer is constructed from similar components and functions as in Fig. 1. Instead of the perforated plate 22, however, spiral-shaped guide plates 25, 26 are installed in the dryer space 19, which force the gas flow in the concentric dryer space 19 and prevent short-circuit flows between the hot gas inlet 16 and the gas outlet 20.
• the guide plate 26 can preferably have a smaller gradient in its spiral shape than the guide plates 25 arranged behind the guide plate 26 in the axial direction.
• the hot gas 15 (for example tangentially entering) (also referred to as “drying gas”) is initially guided almost completely in the circumferential direction in the discharge zone 5 of the dispersed, moist solid 6 by a baffle 26, where it is permeated with solid particles.
• the solids-laden drying gas 15 is guided through the spiral guide plates 25 in spiral paths to the dryer outlet 20.
• the baffles 25 and 26 prevent dead zones in the dryer space 19 from which no flow occurs, and a predetermined minimum transport speed of the drying gas 15 and an equal residence time of the dispersed solid particles are enforced everywhere.
• FIG. 3 shows in an enlarged scale the discharge zone 5 of a combined centrifuge dryer with two or more rotating cleaning blades 28, which clean the deflection surface 29 of the impact cone 18 with each rotor revolution.
• the pre-dewatered solid 6 is from the screw conveyor of the centrifuge 1 Sprayed edge 30 transported and there at high speed out of the rotor
• 60 m / s also exert a suction and promoting effect on the surrounding hot gas 15 a, with the further consequence that the surrounding hot gas 15 a partially conveys the solid dust located in the drying chamber 19 into the discharge zone 5.
• the dust-containing hot gas 15a sucked in by the sheep 28, together with the scraped off solid particles, is flung radially or conically into the dryer space 19 by the cleaning blades, depending on the design of the guide surfaces.
• suction and baffle plates 32 can be attached to the blades.
• FIG. 4 shows the discharge zone 5 of a centrifuge dryer with a steeper angle of the impingement cone 18, perforated gas guide plates 22 and rotating blower blades 33. In contrast to the cleaning blades 28 in FIG.
• the cleaning action of the blowing blades 33 is not based on a scraping action, but on the blowing action of the intensive gas flow 34, which flows out of the rotating nozzle 33 and occurs on the surface 29 of the baffle cone 18 to be cleaned at a flat angle.
• the gas delivery through the bladder blade 33 is particularly increased by suitable measures, such as, for example, large intake cross sections at the blade inlet 35, guide elements in the blade and directed blowing out at the blade outlet. Due to the suction effect of the dust-containing hot gas 15a on the blade inlet side 35 and the hot gas 36 flowing out of the perforated gas guide surfaces 22, the gas flow in the dryer space 19 with the dispersed solid particles 6 is kept away from the walls of the dryer housing 11 and is shifted more inwards.
• the solid 6 flying out from the spraying edge 30 of the centrifuge drum 2 reaches the area of influence of the hot gas 15 a, which contains dust and is conveyed through the blower blade 33, before it hits the surface 29 of the impingement cone 18.
• the solid particles are dried on their surface and coated with dry solid dust (coating), so that they lose their tendency to stick even before contact with the surface 29.
• the deflecting surface can also be coated with a suitable material, such as, for example, PTFE, enamel, ceramic, or other anti-adhesive materials.
• the surface 29 can also consist of a perforated surface and be ventilated.
• FIG. 5 shows a combination of a rotating cleaning blade 28 and a bladder blade 33, cooperating with a perforated gas guide plate 22.
• the surface 29 of the impact cone 18 is cleaned by a rotating scraper 38 in conjunction with the blowing effect of the hot gas drawn in.
• the emerging bubble jet 34 is not only directed onto the surface of the impingement cone, but also blows tangentially onto the perforated gas guide plate 22 to be able to suck in more gas.
• the discharge openings 4 of the centrifuge 1 exert a conveying effect on the gas within the interior 37 of the centrifuge 1 at their edges. As a result of this conveying action, moist gas is sucked out of the interior 37 of the centrifuge 1 and hot, dry gas is drawn in.
• the moist solid 6 is pre-dried with long dwell time before being ejected in the spiral passage of the centrifuge 1.
• 6 shows a combination of a turbulence vane 40 for keeping the dryer space 19 free and a cleaning vane 28 for cleaning the surface 29 of the impact cone 18.
• the turbulence vane 40 has a high circumferential speed and generates a strong swirl 41 of the drying gas in the dryer space 19. Dead zones which are not flowed through are thereby avoided and the drying gas 15 entering is intensively mixed with the dispersed particles.
• the cleaning blade 28 can scrape or blow off part or all of the surface 29 of the impact cone.
• the blades 28 and or 40 can be fixed to the rotor 2 so that they can move in a rigid or oscillating manner.
• rotating turbulence disks for the production of tubular vortex rolls 43 are installed in the dryer room 19.
• the dryer housing 11 is designed without a fixed inner housing 12, which in some embodiments of the centrifuge dryer envelops the drum 2.
• the concentric dryer chamber 19 is therefore delimited on the outside by a non-rotating cylinder wall and on the inside by the rapidly rotating centrifuge drum 2.
• the rotating surface of the drum 2 in connection with the rapidly rotating disks 42 induce in the dryer space 19 a series of turbulent vortex rollers 43 rotating in themselves.
• These turbulent vortex rollers 43 are driven by the rotating surfaces of the drum 2 and the disks 42, produce one in the entire cross section high degree of turbulence and equalize the flow through the dryer chamber 19 in the circumferential direction.
• the high degree of turbulence of the vortex rollers prevents deposits on the boundary walls of the dryer housing 11, forces an intimate mixing of the drying gas and the dispersed solid particles and generates a high drying rate for the moist solid particles, combined with an extremely high water evaporation rate based on the dryer volume.
• the entering hot gas 15 is made uniform in its axial movement over the entire circumference by the passage gaps 44 outside the rotating disks 42 and by the torus-shaped turbulence vortex rollers. Instead of rotating disks 42, others can also be on the centrifuge drum 2
• Elements for generating turbulence rollers are used in the dryer, for example a radial blade ring, axial or radial feed wheels, beater arms or other suitable internals known per se.
• one or more vane rings 46 are attached to the outside of the rotating centrifuge drum 2 to generate a high degree of turbulence in the dryer space 19 and to uniformly promote and control the dwell time of the drying gas laden with solids.
• the vane rings 46 also break up agglomerates in the dryer space 19.
• the surface 29 of the impact cone 18 consists of several geometrically composed smooth surfaces.
• the surface consists of a flat cone, to which a rounded surface contour 49 adjoins further out. Due to the flat impact angle of the dispersed moist solid particles 6 onto the smooth impact cone 18, their reflection and further transport is promoted despite the division into several smaller particles 47.
• the centrifuge dryer shown in FIG. 9 again consists of a centrifuge, in the example shown a solid bowl centrifuge 1 which is encased by an outer housing 11 of an atomizing dryer. An inner housing 12 is arranged around the centrifuge drum 2.
• the outer dryer housing 11 and the inner housing 12 form the concentric dryer space 19 through which the drying gas 15 is passed.
• the drying gas 15 is fed through the tangential hot gas shaft 16, detects in the region of the discharge zone 5 the dewatered solid which is thrown off in the form of a dispersed particle veil and transports the Solid particles with increasing drying in spiral paths through the dryer chamber 19 and reach the outlet channel 20 as gas 21 laden with solids.
• the water separated in the centrifuge 1 is drained off in the centrate chute 10.
• the outer dryer housing 11 is sealed on the two end walls 13 and 14 against the rapidly rotating centrifuge drum 2.
• the gap 190 of the rotary seals 160 is formed by the centrifuge drum 2 and the sealing ring 170, which, like the drum pedestals 210, is rigidly attached to the base frame 220.
• the sealing gap 190 is guided precisely and stably.
• the centrifuge drum 2 remains cold even when hot gas 15 flows through the dryer suspension 19 and does not expand, whereas the dryer housing 11 through which hot gas 15 flows expands greatly in the axial and radial directions.
• the displacement movements of the two housing walls 13 and 14 are compensated for by a gastight flexible compensator 180 or an elastic membrane or a displaceable sliding ring 300 relative to the rigidly attached sealing ring 170, so that the sealing gap 190 is not changed.
• Fig. 10 shows in detail a non-contact labyrinth seal for a centrifuge dryer, which connects the sealing ring 170 rigidly attached to the frame 220 with the axially and radially displacing dryer section 14 in a gas-tight manner by a compensator 180.
• the flexible compensator 180 is e.g. gas-tightly connected to the sealing ring 170 and to the end wall 14 by means of tensioning straps 230 or other fastening means.
• the sealing gap 190 between the tips 240 of the labyrinth seal and the rotating surface of the centrifuge drum 2 can be kept very narrow (0.3-0.5 mm), since the displacement movement of the end wall 14 is not transmitted to the labyrinth seal. All non-rotating parts are hatched to the right, all rotating parts are hatched to the left.
• Fig. 11 shows a non-contact rotary seal 160 in the form of a thread seal for a centrifuge dryer which e.g. has a negative pressure in the dryer room to the right of the end wall 14.
• the sliding and sliding movements of the end wall 13 and 14 of the dryer during the heating or cooling phase of the dryer housing 11 are compensated for by a sheet metal ring 260 which is sealed by heat-resistant O-rings 270 and both on the housing end wall 13 and 14 as well as on rigidly attached sealing ring 170 can slide.
• the narrow sealing gap 190 of the rotary seal 160 which is designed as a threaded conveyor seal, brings about a threading action in the surface of the centrifuge drum 2 which has a conveying effect which counteracts the vacuum in the dryer and a gas back pressure which prevents the penetration of incorrect air into the dryer chamber 19.
• the threads 280 can also be filled with a fluid barrier medium, such as water or barrier gas, which is passed through the threads 280.
• the sliding dryer housing 11 is compensated by the sliding block 300 in the gap.
• the sliding block 300 itself is slidably sealed by heat-resistant O-rings both on the dryer end wall 14 and on the rigidly attached sealing ring 170.
• FIG. 13 shows a non-contact rotary seal 160 with flat grooves, which rotates in a soft cylinder liner 320 made of slide bearing materials with a very narrow gap 190.
• the displacement movement of the end wall 13 or 14 of the dryer housing 11 is compensated for by a sliding ring 340 which is resilient in the radial and axial directions.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Health & Medical Sciences (AREA)
• Molecular Biology (AREA)
• Microbiology (AREA)
• Drying Of Solid Materials (AREA)
• Centrifugal Separators (AREA)
• Treatment Of Sludge (AREA)

Priority Applications (1)

Applications Claiming Priority (3)

Related Child Applications (1)

Publications (2)

Family

ID=7801851

Family Applications (2)

Family Applications Before (1)

Country Status (8)

Families Citing this family (14)

Family Cites Families (12)

• 1996
  • 1996-08-05 DE DE19631605A patent/DE19631605C1/de not_active Expired - Fee Related
• 1997
  • 1997-03-27 CA CA002262705A patent/CA2262705A1/fr not_active Abandoned
  • 1997-03-27 AT AT97915449T patent/ATE204638T1/de not_active IP Right Cessation
  • 1997-03-27 JP JP50749798A patent/JP3215439B2/ja not_active Expired - Fee Related
  • 1997-03-27 WO PCT/EP1997/001570 patent/WO1998005912A1/fr active Application Filing
  • 1997-03-27 EP EP99121798A patent/EP0979984A3/fr not_active Withdrawn
  • 1997-03-27 EP EP97915449A patent/EP0916065B1/fr not_active Expired - Lifetime
  • 1997-03-27 ES ES97915449T patent/ES2163751T3/es not_active Expired - Lifetime
  • 1997-03-27 US US09/242,038 patent/US6618956B1/en not_active Expired - Fee Related
  • 1997-03-27 DE DE59704388T patent/DE59704388D1/de not_active Expired - Fee Related

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events