EP3146284A1 - Distributeur de gaz pour un séchoir à convection possédant une commande améliorée de la vitesse radiale de gaz - Google Patents

Distributeur de gaz pour un séchoir à convection possédant une commande améliorée de la vitesse radiale de gaz

Info

Publication number
EP3146284A1
EP3146284A1 EP15727584.3A EP15727584A EP3146284A1 EP 3146284 A1 EP3146284 A1 EP 3146284A1 EP 15727584 A EP15727584 A EP 15727584A EP 3146284 A1 EP3146284 A1 EP 3146284A1
Authority
EP
European Patent Office
Prior art keywords
gas
distributer
flow
radial
drying
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP15727584.3A
Other languages
German (de)
English (en)
Inventor
Henrik SCHØNFELDT
Christian HOLM FRIDBERG
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SPX Flow Technology Danmark AS
Original Assignee
SPX Flow Technology Danmark AS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by SPX Flow Technology Danmark AS filed Critical SPX Flow Technology Danmark AS
Publication of EP3146284A1 publication Critical patent/EP3146284A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D1/00—Evaporating
    • B01D1/30—Accessories for evaporators ; Constructional details thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D1/00—Evaporating
    • B01D1/16—Evaporating by spraying
    • B01D1/18—Evaporating by spraying to obtain dry solids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D1/00—Evaporating
    • B01D1/16—Evaporating by spraying
    • B01D1/20—Sprayers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects

Definitions

  • the present invention relates to the field of gas distributers or gas dispersers mounted on spray dryers, spray coolers, spray absorbers and similar equipment, collectively called convective dryers, wherein the gas or air dispersed or distributed may be e.g. atmospheric air or a specialty gas or mixture of specialty gasses and wherein the equipment collectively called convective dryers are useful in many diverse technical fields wherein it is desired to produce a powdery material from an atomized liquid containing one or more substances to be dried and retrieved as a powdery, agglomerated, coated, or granulated material.
  • a convective dryer is an apparatus that produces dry powdery substances from an atomized liquid.
  • atomized droplets are dried or solidified within a processing chamber by convective heat and often mass transfer with a fluid. This process takes place in a confined space.
  • the processing chamber is usually called a drying chamber.
  • the liquid feed is atomized using an atomization device such as a rotary atomizer, a pressure nozzle or a multi-fluid nozzle, and mixed with a drying gas typically in the temperature range of -50-800 °C.
  • the dry powdery substance can be e.g. a powder, an agglomerated powdery substance, a coated powdery substance or a granulated substance; which are all examples of products the skilled person knows may result from drying an atomizing liquid capable of forming such a powdery substance.
  • the drying gas itself may be any gaseous phase fluid, but is often air, nitrogen, or steam. Often a dedicated component called a gas or an air distributer is used as a component for directing the gas appropriately into the drying chamber, taking into account the selected means of atomization, by ensuring a proper gas velocity profile suitable for the convective dryer.
  • gas distributer or "air distributer” as used herein is meant any disperser or distributer supplied with a drying gas to be used in a convective dryer.
  • gas may be taken to cover any single component gas, such as e.g. molecular nitrogen or argon, as well as any mixture of gases such as is found in e.g. air or steam.
  • the present invention is hence not limited by any particular choice of the drying gas intended for distribution by the gas distributer.
  • air or steam is often used as the drying gas when the liquid to be atomized is an aqueous solution, while an inert gas is often used when the liquid to be atomized is a non-aqueous solution.
  • drying gas covers any drying gas, which may be used in a convective dryer.
  • the gas distributer can be of any type known to the skilled person but may e.g. be in the shape of a bend duct type, a plenum type or a scroll type with each type potentially having area contractions and expansions.
  • the gas distributer may encapsulate or include the atomizing means, in particular an atomizer, or be decoupled from the atomizing means.
  • a drying gas jet is formed extending from a gas distributer exit surface and into the chamber.
  • the drying gas jet has a center core that protrudes a certain distance into the chamber while continuously mixing with the surroundings, eventually becoming fully mixed with the surrounding gas.
  • the velocity field of the drying gas jet can be described in terms of its axial, tangential and radial gas velocity components.
  • the axial gas velocity component is aligned with the center axis of the gas distributer; the tangential gas velocity component defines the rotational velocity component of the gas with respect to the center axis of the gas distributer while the radial velocity component defines a direction of gas movement perpendicular to the axial and tangential velocity components.
  • the axial gas velocity component carries the gas into the chamber, the tangential velocity aids in breaking up the inlet jet, while the radial component controls direction stability.
  • the flow pattern in the disclosed invention can be described by applying the continuity, Navier-Stokes and energy equations as in eq. 1.3a, 1.9a and 1.11 from Fundamental mechanics of fluids by I.G. Currie 2nd edition from McGraw-Hill mechanical engineering series.
  • the energy equation may be disregarded for isothermal flows which often is the case for well isolated ducts or ducts with small area-to-flow ratio such as the invention. Once in the spray chamber, the flow cannot be described accurately without the energy equation.
  • tangential velocity may be influenced by the presence of guide vanes such that when these guide vanes are properly installed, a rotation of the drying gas flow is obtained.
  • guide vanes which may be straight or curved or a combination hereof.
  • the radial velocity component as described above is the object of the present invention.
  • the present inventors have now realized that for high capacity, low deposit convective drying it is preferable that the drying gas jet should be aligned best possible with the axis of the gas distributer with the radial gas velocity components being conferred a substantial degree of rotational symmetry around the central axis of the gas distributer and/or a controlled radial velocity. This ensures that as much as possible of the dryer volume is utilized, keeping the wet product away from the walls with reduced risk of deposits on the walls.
  • WO 2007/071238, WO 2011/047676 is utilizing one or more guide vanes assembled within the gas distributer to regulate the flow path and velocity of its constituent velocity components, particularly the tangential velocity components, before contacting the drying gas with the atomized liquid.
  • the present invention relates to a convective dryer and a gas distributer for, and a method of, controlling the velocity profile of a drying gas in a convective dryer, particularly the radial velocity profile of the drying gas, by creating an advantageous velocity profile of the drying gas prior to introducing the drying gas into the convective dryer chamber.
  • the invention is further described in the claims.
  • the velocity profile may have different requirements depending on the convective process, chamber dimensions and atomizing means, but common gas distributer targets may be defined, such as an advantageous velocity distribution and flow alignment.
  • the radial gas velocity component When following the directions of the present invention, the radial gas velocity component will retain a non-zero velocity, the size of which will be dependent on the distance to the central axis of the gas distributer, which can be significant and comparable to the initial radial gas velocity in size. Nevertheless, upon passage of the gas distributers and flow aligners of the present invention the radial gas velocity will become substantially rotationally symmetrical around the central axis of the gas distributer or flow aligner and/or will have a controlled radial gas velocity component.
  • the invention further concerns a convective dryer comprising the gas distributer of the present invention, and the use of said convective dryer and said gas distributer in a method to produce a powdery substance in a convective dryer according to the present invention.
  • the inventors have become aware of the importance of reducing uncontrolled or random radial gas velocity components in order to achieve improvement of the mixing profile; while at the same time utilizing as much of the dryer volume as possible and simultaneously keeping any wet product away from the dryer walls. Thereby the risk of undesired materials deposits on the walls of the convective dryer is reduced.
  • the invention comprises a gas distributer for a convective dryer configured to produce a drying gas jet in a drying chamber of a convective dryer, said drying gas jet having a radial gas velocity component which is substantially rotationally symmetrical around a common center axis and/or has a controlled radial velocity respective to said center axis; which common center axis will be further defined below.
  • the present invention also relates to a method of controlling the gas velocity profile in a convective dryer using a gas distributer capable of achieving the above goal. In the context of the present invention, it is the aim to obtain a substantially rotationally symmetrical radial gas velocity component of the drying gas jet.
  • a low or zero rotationally asymmetrical radial gas velocity component is to be understood to mean that the average resulting rotationally asymmetrical radial gas velocity component of a drying gas jet at the entrance to the exit surface of a gas distributer and before entry into a drying chamber compared to the average initial rotationally asymmetrical radial gas velocity component at constant gas mass-flow in the drying chamber is smaller by at least a factor of 4, at least a factor of 8, preferably by at least a factor of 16 and more preferably by at least a factor of 32.
  • a flow aligner adaptable to be installed into the flow path of a drying gas within an gas distributer for a convective dryer, said flow aligner having a plurality of flow channels, said plurality of flow channels so organized as to form a mesh or mesh-like structure and so dimensioned that a low or zero rotationally asymmetrical radial gas velocity component of the drying gas upon exit from the gas distributer is obtained
  • Figure 1 shows a convective dryer with a gas distributer and a flow aligner according to the invention.
  • Figure la shows a sideways view of the convective dryer whereas
  • Figure lb shows a top view of the convective dryer along an axis centered on the gas distributer.
  • Figure 2 shows a diagrammatic representation of three different mesh or mesh-like structures for use in a flow aligner according to the invention.
  • Figure 3 shows a diagrammatic representation of a flow aligner having a circular-like mesh or mesh-like structure adapted to align a gas jet with the central axis of a convective dryer and to reduce the radial gas velocity to a low or zero value.
  • Figure 4 shows a diagrammatic representation of a flow aligner comprising a plurality of evenly spaced conically shaped guide vanes.
  • Figure 5 shows a diagrammatic representation of a flow aligner comprising a plurality of increasingly spaced conically shaped guide vanes.
  • Figure 6 shows a diagrammatic representation of a flow aligner comprising a plurality of decreasingly spaced conically shaped guide vanes.
  • Figure 7 shows a diagrammatic representation of a flow aligner comprising a plurality of increasingly spaced conically shaped guide vanes having varying gas exit levels .
  • Figure 8 shows a diagrammatic representation of a flow aligner comprising a plurality of trumpet opening shaped guide vanes .
  • a drying gas jet for a convective dryer having improved rotationally symmetrical radial gas velocity control and/or controlled radial velocity at the exit surface of an associated gas distributer is central to the present invention.
  • this is tantamount to reducing the rotationally asymmetrical radial gas velocity component in the velocity field of said drying gas.
  • the present inventors have realized that an improvement to jet stability can be achieved in a simple manner by inserting a flow aligner according to the present invention into the flow path of the drying gas, wherein said gas distributer comprises said flow aligner.
  • a further object of the present invention is to provide a flow aligner for a gas distributer resulting in a low or zero rotationally asymmetrical radial drying gas velocity component upon exit from said gas distributer and into said drying chamber as a drying gas jet.
  • the present invention relates to a convective dryer (100) configured for producing a powdery substance from an atomized liquid, said convective dryer (100) comprising at least one gas distributer (110) configured to generate a drying gas jet (120), said jet protruding from an exit surface (111) of said gas distributer (110) into a drying chamber (101) of said convective dryer (100), said drying gas jet (120) having a center axis (121) aligned with an axis of said gas distributer (110); said drying gas jet (120) characterizable by a gas velocity field; said gas velocity field having an axial gas velocity component with said axial gas velocity component carrying said drying gas into said drying chamber (101), a tangential gas velocity component and a radial gas velocity component, said radial gas velocity component comprising a rotationally asymmetrical radial gas velocity component; and wherein said drying gas jet (120) has a low or zero rotationally asymmetrical radial gas velocity component .
  • FIG. 1 an exemplary, but non-limiting, convective dryer (100) according to the invention is described.
  • the convective dryer (100) comprises a drying chamber (101), a gas distributer (110), atomizing means (112) and a flow aligner (130) .
  • a drying gas exits a flow conduit (141) and enters the gas distributer (110) at a point along the flow path (140) of the drying gas.
  • the gas distributer (110) the drying gas is directed into the drying chamber (101) and further, the drying gas is passed through a flow aligner (130) of the present invention.
  • the drying gas forms a gas jet (120) in the drying chamber (101) upon exiting the gas distributer (110) and flow aligner (130) at an exit surface (111), wherein gas distributer (110), flow aligner (130) and the gas jet (120) are now aligned to create a common center axis (121) .
  • the atomizing means (112) are also aligned along the common center axis (121) just described.
  • said gas distributer (110) is configured to reduce or minimize the rotationally asymmetrical radial velocity components in said drying gas jet (120) velocity field.
  • said gas distributer (110) comprises a flow aligner (130,410,510,610,710,810), said flow aligner
  • a gas distributer (110) for directing a drying gas jet (120) into a drying chamber (101) of a convective dryer (100), said convective dryer (100) configured for producing a powdery substance from an atomized liquid, said gas distributer (110) configured to generate a drying gas jet (120) protruding from an exit surface (111) of the gas distributer (110) into said drying chamber (101), said drying gas jet (120) having a center axis (121) aligned with an axis of said gas distributer (110) essentially perpendicular to said gas distributer exit surface (111); said drying gas jet characterizable by a gas velocity field; said gas velocity field having an axial gas velocity component, a tangential gas velocity component and a radial gas velocity component, said radial gas velocity component comprising a rotationally asymmetrical radial gas velocity component, with said axial gas velocity component carrying said drying gas into said drying chamber (101); wherein said gas distributer (110) is
  • the gas distributer (110) may be in the shape of a bend duct type gas distributer, a plenum type, or a scroll type, and may have area contractions and expansions.
  • the gas distributer may encapsulate or include the atomizing means or can be decoupled from the atomizing means.
  • the gas distributer (110) comprises a flow aligner (130,410,510,610,710,810) inserted into the flow path (140) of said drying gas internally in said gas distributer (110), said flow aligner defining a plurality of flow channels (211,221,231,241) for reducing or minimizing a rotationally asymmetrical radial gas velocity component in the flow field of the drying gas jet (120), said plurality of flow channels (211,221,231,241) organized to form a mesh or mesh-like structure (210,220,230,240) and so dimensioned that a low or zero rotationally asymmetrical radial gas velocity component of said drying gas upon exit from said gas distributer (110) is obtained after passing said drying gas through said plurality of flow channels (211, 221, 231, 241) .
  • a mesh or a mesh ⁇ like structure (210,220,230,240) is to be understood as a 3-dimensional structure or construction, which influences the gas flow velocity field of a drying gas passing through the mesh or mesh-like structure by reducing or minimizing the rotationally asymmetrical radial gas velocity components to a low value or zero during passage .
  • a mesh or mesh-like structure (210,220,230,240) of the present invention may be tubular in construction, such that the drying gas passes through a plurality of tubes during its passage of the mesh or mesh-like structure. It can also be constructed from a plurality of guide vanes having an extension along the direction of said center axis (121), at least a subset of the guide vanes forming an inclination angle to said center axis (121) .
  • the mesh or mesh-like structure (210,220,230,240) may also be constructed from a plurality of sets of guide vanes, each set of guide vanes having an extension along the direction of said center axis and each set of guide vanes being differently radially oriented with respect to the center axis within the mesh or mesh-like structure.
  • a characteristic length scale ( ⁇ ) can now be defined, herein called the radial distance ( ⁇ ) , which is the maximum distance between two walls of a mesh observed by projection as described above, when measured from said center axis (121) along a straight line connecting said center axis (121) to an outer rim (215,225,235,245) of said flow aligner
  • Figure 2 shows a diagrammatic representation of three different mesh or mesh-like structures (210,220,230,240) for use in a flow aligner (130,410,510,610,710,810) according to the invention.
  • Figure 2a shows the projection area of a flow aligner having a square-like mesh or mesh-like structure (210) .
  • Figure 2b shows the projection area of a flow aligner having a circular-like mesh or mesh-like structure (220) .
  • Figure 2c shows the projection area of a flow aligner having a honeycomb-like mesh or mesh-like structure (230)
  • Figure 2d shows the projection area of a flow aligner having a honeycomb-like mesh or mesh-like structure (240) without fines in the middle.
  • the value ⁇ is a characteristic length of the flow aligner as explained above.
  • the flow channels (211,221,231,241) created by the mesh or mesh-like structures have been indicated on the figures in an exemplary manner. Further it has been indicated in the figures the location of exemplary guide vanes (212,213,222,223,232,233) or tubes (242) in a non- limiting manner as described below. While the embodiment comprising a mesh or mesh-like structure is preferred, it is possible to dispense with control of the tangential gas velocity and still obtain a significant portion of the benefits of the present invention through control of the radial gas velocity in itself .
  • Figure 3 shows a diagrammatic representation of a flow aligner having a circular-like mesh (320) or circular- like mesh-like (310) structure adapted to align a gas jet
  • the value a is a characteristic length of the flow channels which is defined by the length the flow channel (211,221,231,241) measured along the center axis
  • a plurality of tangential guide vanes (223) in the form of rings or cylinders are assembled concentrically around the center axis (121) of the flow aligner and combined with a plurality of radial guide vanes (222), these radial guide vanes serving like spokes in a wheel.
  • the radial (222) and tangential (223) guide vanes are separated along the center axis of the flow aligner (310) into a first layer (340) and a second layer (330); whereas in the flow aligner (320) of Figure 3c the radial (222) and tangential (223) guide vanes are connected into a single first layer (350) thereby forming tubes.
  • the resulting flow channels (221) are indicated with reference to the two-dimensional projection of the constructed flow aligners of figure 3a.
  • FIGS 4A and 4B show a diagrammatic representation of a flow aligner (410) according to the present invention, said flow aligner (410) comprising a plurality of evenly spaced conically shaped guide vanes (423) , said plurality of evenly spaced conically shaped guide vanes (423) arranged to form a circular-like mesh or mesh-like structure and adapted to reduce or minimize a rotationally asymmetrical radial gas velocity component in the gas velocity field of a drying gas jet (120) to a low value or zero, said circular-like mesh or mesh-like structure conforming to the requirements of the above definitions of mesh or mesh-like structures.
  • the flow aligner (410) having a circular-like mesh or mesh-like structure adapted to reduce or minimize a rotationally asymmetrical radial gas velocity component in the gas velocity field of a drying gas jet (120) to a low value or zero of the embodiment shown in the figures is constructed in parallel to the flow aligner (310) shown in figure 3b. It has a first layer (440) and a second layer (430) which separates radial (422) and tangential (423) guide vanes along the center axis (121) of the flow aligner (410) .
  • the tangential guide vanes (423) are now no longer ring or cylinder shaped, rather they form cut-off cones which have been spaced apart by said characteristic distance ⁇ , to form a second layer of conically shaped tangential guide vanes (423) arranged concentrically around said center axis (121).
  • a smaller or larger rotationally symmetrical radial gas velocity is controllably conferred to said drying gas jet (120), while simultaneously suppressing the rotationally asymmetrical radial gas velocity components in the gas velocity field of said drying gas jet (120) to a low value or zero.
  • the inclination angle ( ⁇ ) is locally defined as positive (as shown in Figure 4) if, when defining a radial distance, Rl, for the inlet as well as a radial distance for the outlet, R2, of the second layer Rl ⁇ R2.
  • the inclination angle ( ⁇ ) is defined as positive by average (as shown in Figure 4) if, when defining an average radial distance, Rl, for the inlet as well as average radial for the outlet, R2, of the second layer Rl ⁇ R2. In both cases, if the ratio is 1, the inclination angle ( ⁇ ) is zero which corresponds to the situation of Figure 3.
  • the present invention relates to flow aligners wherein ( ⁇ ) is larger than 0° but smaller than 90°.
  • ⁇ is larger than 0° but smaller than 90°.
  • ⁇ shall at least be larger than 0°, larger than 2°, larger than 5° or larger than 10°, but smaller than 90°, preferably smaller than 75°, preferably smaller than 60°, preferably smaller than 50°, and most preferably smaller than 45°.
  • the flow aligner (410) having a circular-like mesh or mesh-like structure adapted to reduce or minimize a rotationally asymmetrical radial gas velocity component in the gas velocity field of a drying gas jet (120) to a low value or zero may also be constructed as a combination of the embodiment shown in Figure 3c with a first layer (350) of combined radial (222) and tangential (223) guide vanes and a second layer (430) constructed as described above.
  • the flow aligner (410) having a circular-like mesh or mesh-like structure adapted to reduce or minimize a rotationally asymmetrical radial gas velocity component in the gas velocity field of a drying gas jet (120) to a low value or zero in parallel to the flow aligner (240) of figure 2D by allowing each throughgoing opening or flow channel (241) of the embodiment in figure 2D to form said inclination angle ( ⁇ ) with said center axis (121) .
  • the guide vanes shown in Figures 4A and 4B have been defined as conically shaped.
  • a substantially true cone- shape is the preferred geometry for the guide vanes of the present invention as this particular geometry provides optimal symmetry around the center axis (121) of the flow aligner when the guide vanes are concentrically assembled .
  • the guide vanes of the present invention which shall be considered oligo-angular shall have at least 3 corners; while guide vanes of the present invention which shall be considered poly-angular shall have at least 6 corners, preferably at least 12 corners, more preferably at least 20 corners. Obviously, as the number of angles of the guide vanes increase, these will more and more approach a true cone structure,
  • Figure 5 shows a diagrammatic representation of a flow aligner (510) comprising a plurality of increasingly spaced conically shaped guide vanes (530) .
  • a flow aligner (510) comprising a plurality of increasingly spaced conically shaped guide vanes (530) .
  • ⁇ and ⁇ are related by the following equation:
  • ⁇ 1 ⁇ 0 + ⁇ ( ⁇ ), a » ⁇ 1
  • ⁇ and a are as previously defined. Due to the manner the value ⁇ was defined above, ⁇ and ⁇ will always be smaller or equal to the value ⁇ with the largest value of ⁇ or ⁇ being equal to ⁇ . Due to the manner in which the guide vanes are constructed, ⁇ will not be constant over a guide vane. In figure 5 e.g., ⁇ increases exponentially with constant exponent between every two guide vanes. Rather, each guide vane will have a constant inclination angle ( ⁇ ) albeit different from its neighbors.
  • Figure 6 shows a diagrammatic representation of a flow aligner (610) comprising a plurality of decreasingly spaced conically shaped guide vanes (630) .
  • ⁇ decreases exponentially with constant exponent between every two guide vanes making ⁇ 0 equal to ⁇ .
  • Figure 7 shows a diagrammatic representation of a flow aligner (710) comprising a plurality of increasingly spaced conically shaped guide vanes having varying gas exit levels .
  • the inventors have found, that for some purposes it is advantageous to allow the above defined exit surface from the flow aligners (410,510,610,710) of the invention to deviate from being perpendicular to the center axis (121) .
  • the exit surface follows a hyperbole, but e.g. linear, exponential, logarithmic, or circular exit surfaces could be equally relevant depending on the purpose of use of the convective dryer (100) comprising the gas distributer (110) and flow aligner (410,510,610,710) of the invention.
  • Figure 8 shows a diagrammatic representation of a flow aligner (810) comprising a plurality of trumpet opening shaped tangential guide vanes (830) .
  • the radial guide vanes are not shown to ease the reader's understanding.
  • the tangential guide vanes (830) are constructed with a first section (831) and a second section (832) .
  • the first section is aligned parallel with the center axis (121) and serves to achieve the target of a low or zero asymmetrical radial gas velocity component of the drying gas jet (120) upon exit of the drying gas jet from the gas distributer.
  • the second section (831) is angled with respect to the center axis as defined above. In the drawing, ⁇ is 45°, but this of course may be varied as detailed in the present document .
  • the radial guide vanes must be located either as a first layer or constructed as a combined layer with the second layer in order to obtain the benefits of the present invention.
  • the first section (831) is substantially more elongated in the direction of the center axis (121) than the second section (832), but this is not necessary as flow alignment will take place in both sections. Accordingly, the second section (832) may be as long or longer as the first section (831) .
  • the advantage of the embodiment detailed in Figure 8 is that a more compact flow aligner (810) can be constructed, where an angular direction is not imposed on the flow until close to the exit surface from the flow aligner (810) of the invention.
  • the radial guide vanes arranged in the first layer (440,540,640,740) of the flow aligners (410,510,610,710) appear to larger than the radial guide vanes of the second layer (430,530,630,730), which however shall not be considered limiting on the present invention.
  • the first layer comprising the tangential guide vanes (440,540,640,740) of the invention may be larger, smaller, or of the same size as the second layer (430,530,630,730,830) comprising the radial guide vanes of the invention.
  • the order of the first and second layers may be reversed or the layers may be built into each other as elsewhere detailed.
  • the flow aligners (130,410,510,610,710,810) of the present invention with one or more throughgoing passages, these one or more throughgoing passages traversing said mesh or mesh-like structure (210,220,230,240) comprised in said flow aligners (130,410,510,610,710,810) in the direction of said drying gas flow (140) .
  • These one or more throughgoing passages may have a diameter or cross section which is larger than the characteristic radial length ( ⁇ ) associated with the mesh or mesh-like structure (210,220,230,240) comprised in the flow aligners (130,410,510,610,710,810) also comprising said one or more throughgoing passages. This is e.g. shown in the flow aligner (130) comprising the atomizer (112) of Figure 1.
  • the advantage of this embodiment is to allow space for instalment of further equipment, such as but not limited to, atomizers and/or additional air nozzles of interest in the art of convective drying, when this further equipment is of a size which is too large to fit within a single mesh of said mesh or mesh-like structure in said flow aligner.
  • the honeycomb structure (230,240) could be preassembled as a tubular structure or assembled as a layered structured from at least two layers each presenting a plurality guide wanes (232,233) in the form of zigzag walls (232,233) and wherein the two layers are oriented at an angle to each other such that an essentially honeycomb-like structure is created when the projection area of the assembled flow aligner (130,310,320) onto the plane defined by the tangential and the radial gas velocity components is observed.
  • the plurality of tubes (242) or guide vanes (232, 233) will have one or more inclination angles ( ⁇ ) to the center axis (121) as detailed above.
  • ⁇ inclination angles
  • gas distributers (110) wherein a plurality of tubular and/or a plurality of guide vanes structure elements of any shape are bundled together into smaller insert substructures which are subsequently assembled to form a larger flow aligner (410,510,610,710,810) according to the present invention and fitting the dimensions of the gas distributer (110) wherein the larger flow aligner (410,510,610,710,810) is intended to be installed.
  • the present inventors have discovered that it is advantageous for achieving an appropriate radial velocity control that the said flow channels (211,221,231,241) have an axial length (a) and a radial distance ( ⁇ ) , such that said flow channels can be characterized by an axial length (a) to radial distance ( ⁇ ) ratio (DR) of 2 ⁇ DR, preferably 3 ⁇ DR, more preferably 4 ⁇ DR, more preferably 3 ⁇ DR ⁇ 100, more preferably 3 ⁇ DR ⁇ 50, more preferably 3 ⁇ DR ⁇ 20, most preferably 4 ⁇ DR ⁇ 20.
  • DR radial distance
  • the plurality of flow channels in an embodiment of the flow aligner (130,410,510,610,710,810) according to the present invention, the plurality of flow channels
  • said mesh or mesh-like structure is a plurality of tubes or a plurality of guide vanes or a combination thereof.
  • the plurality of tubes or plurality of guide vanes or combination thereof can either be connected or organized in layers, preferably at least two layers, more preferably two layers.
  • said flow aligner (130,410,510,610,710,810) comprises more than two layers, e.g. a first layer (340) and a second layer (330); a sequence of layers can be envisaged such as e.g. a first first layer (340), a first second layer (330), a second first layer (340), a second second layer (330) and so forth. Further structural variations can easily be envisaged by the skilled person.
  • said plurality of guide vanes (212,213,222,223,232,233,423) are oriented radially and tangentially with respect to said velocity field thereby forming a set of radial guide vanes and tangential guide vanes.
  • said tangential guide vanes may be formed as a set of rings or cylinders (223) and/or straight guide vanes (222) .
  • multiple sets of straight guide vanes (212,213) are assembled into a cross pattern having an angle with respect to the axial gas velocity component axis.
  • the plurality of flow channels (211,221,231,241) of the present invention may in one embodiment form a rounded or a polygonal structure or a combination thereof in particularly the plurality of flow channels (211,221,231,241) may form a honeycomb structure ( 231, 241) .
  • a combination of separate guide vanes (232,233) may be oriented radially and tangentially to form an axially stretched honeycomb (231) .
  • the plurality of tubes or guide vanes are arranged in a further embodiment of the present invention.
  • 212,213,222,223,232,233,242,423 may be manufactured from a metal or from a plastic and can be extruded, point wise or fully welded, or loosely assembled to form an assembled flow aligner (130,310,320) within said gas distributer (110) .
  • honeycomb structured flow aligner 230 was simulated using the CD-Adapco Star-ccm+ software (2013-build) .
  • the honeycomb construction guides both the tangential and the radial velocity components independently with the purpose of reducing the radial gas velocity components while allowing a given amount of tangential gas velocity to be maintained for improved mixing.
  • DR is larger than 2, preferably larger than 3, most preferably larger than 4, the benefits of the present invention are achieved.
  • Some exemplary dimensions for use in commercial spray towers have a between 40 mm to 300 mm and ⁇ between 10 mm to 50 mm in combinations suitable for yielding an appropriate DR-value.
  • the radial angle for the example with no guide rings is seen to be high and inward pointing (and gas flow is therefore directed towards the center rather than away from the center) and determined by upstream conditions, whereas gas flow alignment ensures a close to zero flow angle or a controlled outward direction decoupled from inlet conditions with enforced radial velocity.
  • the use of guide rings has a significant effect on the average radial velocity at entrance to the dryer.
  • the radial velocity component will for the present example be 3.0 m/s whereas for 3 rings inserted in the duct between the dryer and the inlet the radial velocity has been calculated to be 1.6 m/s.
  • the reduction will depend on the number of rings, the length, diameter and spacing of the rings as well as the position of the rings. As such, the mere presence of a single (or a few) tangential guide vanes in the flow aligners of the invention are not sufficient to achieve the goals of the present invention, even if an effect on the radial velocity can be observed.
  • the present invention further relates to a convective dryer (100) comprising a gas distributer (110) as previously described; preferably the gas distributer (110) comprises a flow aligner (130,410,510,610,710,810) as previously described.
  • the gas distributer (110) comprises a flow aligner (130,410,510,610,710,810).
  • said flow aligner (130,410,510,610,710,810) has an axial length (a) and comprises a plurality of tubes or guide vanes (212, 213, 222, 223, 232, 233, 242, 423) , said plurality of tubes or guide vanes organized to form a mesh or mesh- like structure (210,220,230,240) having a plurality of openings (211,221,231,241), said tubes or guide vanes being so dimensioned that a low or zero rotationally asymmetrical radial gas velocity of said drying gas upon exit from said gas distributer (110) is obtained after passing said drying gas through said plurality of tubes or guide vanes.
  • the present invention also relates to a method for controlling the gas velocity field of a drying gas jet (120) protruding from a gas distributer (110) into a drying chamber (101) of a convective dryer (100), said gas velocity field comprising an axial gas velocity component, a tangential gas velocity component and a radial gas velocity component, said radial gas velocity component comprising a rotationally asymmetrical radial gas velocity component, said method comprising reducing or minimizing said rotationally asymmetrical radial gas velocity component such that the rotationally asymmetrical radial gas velocity of said drying gas jet (120) is low or zero.
  • the present invention in particular also relates to a method for controlling the gas velocity field of a drying gas jet (120) protruding into a drying chamber (101) of a convective dryer (100) from an exit surface (111) of a gas distributer (110), said gas distributer (110) comprising a flow aligner (130,410,510,610,710,810), said flow aligner comprising flow channels (211,221,231,241), said flow aligner defining an axial length (a) and a radial distance ( ⁇ ) , wherein said flow channels are characterized by an axial length (a) to radial distance ( ⁇ ) ratio (DR) of 2 ⁇ DR , preferably 3 ⁇ DR, more preferably 4 ⁇ DR, more preferably 3 ⁇ DR ⁇ 100 , more preferably 3 ⁇ DR ⁇ 50 , more preferably 3 ⁇ DR ⁇ 20 , most preferably 4 ⁇ DR ⁇ 20 .
  • DR axial length
  • DR radial distance
  • the present invention relates to the use of a method for controlling the gas velocity field of a drying gas jet (120) protruding from a gas distributer (110) into a drying chamber (101) of a convective dryer (100) as described above for producing a powdery substance, such as e.g. a powder, an agglomerated powdery substance, a coated powdery substance or a granulated substance from an atomizing liquid capable of forming a such powdery substance in a convective dryer (100) and a powdery substance produced from an atomizing liquid containing a material capable of forming a powdery substance in a convective dryer (100) using a method as described above.
  • a powdery substance such as e.g. a powder, an agglomerated powdery substance, a coated powdery substance or a granulated substance from an atomizing liquid capable of forming a such powdery substance in a convective dryer (100) and a powdery substance produced from an

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
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  • General Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Microbiology (AREA)
  • Drying Of Solid Materials (AREA)

Abstract

L'invention concerne un distributeur de gaz, et un procédé pour la commande du profil de vitesse d'un gaz de séchage dans un séchoir à convection, en particulier le profil de vitesse radiale, consistant à créer un profil de vitesse avantageux avant l'introduction du gaz de séchage dans la chambre du séchoir à convection. Le profil de vitesse peut avoir différentes exigences en fonction du processus de convection, des dimensions de la chambre et du moyen d'atomisation, mais des cibles communes de distributeur de gaz peuvent être définies, telles qu'une distribution de vitesse symétrique par rotation et un alignement axial. L'invention concerne en outre un séchoir à convection comprenant le distributeur de gaz de la présente invention, l'utilisation dudit procédé pour produire une substance pulvérulente dans un séchoir à convection selon la présente invention.
EP15727584.3A 2014-05-21 2015-05-21 Distributeur de gaz pour un séchoir à convection possédant une commande améliorée de la vitesse radiale de gaz Withdrawn EP3146284A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DKPA201400272 2014-05-21
PCT/EP2015/061342 WO2015177324A1 (fr) 2014-05-21 2015-05-21 Distributeur de gaz pour un séchoir à convection possédant une commande améliorée de la vitesse radiale de gaz

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EP3146284A1 true EP3146284A1 (fr) 2017-03-29

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EP (1) EP3146284A1 (fr)
CN (1) CN106413831A (fr)
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CN113251756A (zh) * 2021-04-29 2021-08-13 张梅虹 一种阻燃塑木复合材料制备用的干燥设备
CN114520171B (zh) * 2022-02-15 2023-03-21 智程半导体设备科技(昆山)有限公司 一种基于槽式清洗机的气流增强装置及方法

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US5227018A (en) * 1989-09-26 1993-07-13 Niro A/S Gas distributor and heater for spray drying
EP2143476A1 (fr) * 2008-07-10 2010-01-13 Alstom Technology Ltd Dispositif de dispersion pour un absorbant séchant par pulvérisation
EP3060866A1 (fr) * 2013-10-24 2016-08-31 Spx Flow Technology Danmark A/S Distributeur de gaz pour un séchoir à convection possédant une commande améliorée de vitesse radiale de gaz

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US2835597A (en) * 1954-12-10 1958-05-20 Barzelay Martin E Spray drying process
NZ188155A (en) * 1977-08-29 1981-12-15 Henningsen Foods Air distributor plate for spray drier
US4226670A (en) * 1978-12-14 1980-10-07 Sonic Dehydrators, Inc. Material injection nozzle for pulse jet drying systems
CN203196350U (zh) * 2013-04-28 2013-09-18 天津澳德添加剂制造有限公司 喷雾干燥设备

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Publication number Priority date Publication date Assignee Title
US5227018A (en) * 1989-09-26 1993-07-13 Niro A/S Gas distributor and heater for spray drying
EP2143476A1 (fr) * 2008-07-10 2010-01-13 Alstom Technology Ltd Dispositif de dispersion pour un absorbant séchant par pulvérisation
EP3060866A1 (fr) * 2013-10-24 2016-08-31 Spx Flow Technology Danmark A/S Distributeur de gaz pour un séchoir à convection possédant une commande améliorée de vitesse radiale de gaz

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Title
See also references of WO2015177324A1 *

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WO2015177324A1 (fr) 2015-11-26

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