DE2506638A1 - ATOMIZING DRYERS - Google Patents

Description

PATENT ADVOCATES A. GRÜNECKER

D1PL.-ING.

H. KINKELDEY

DR-INS.

W. STOCKMAIR

*? C Π ß C O Q DR.-INQ. AaE (CALTECH)

Z 3 UW 0 WHERE K. SCHUMANN

DR. RER. NAT. · DIPL.-PHYS. PH JAKOB

<3. BEZOLD

DR. RBR. NAT. · D1PL.-CHEM.

MUNICH E. K. WEIL

DR. RER. OEC. INQ.

LINDAU

8 MUNICH 22

MAXIMILIANSTRASSS 43

17th February 1975 PH 8988

STOBK AMSTERDAM B.V.

198, Sportlaan, Amstelveen, The Netherlands

Atomizing dryer

The invention relates to spray dryers. In general, it relates to spray drying systems and especially on systems with a conical centrifugal design. Such systems are used to convert into a liquid suspended material used to a dry, powdery or granular product, this conversion taking place in the presence of a hot, gaseous desiccant, normally filtered and air heated to a certain temperature

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TELEPHONE (OSS) 22 28 62 TELEX O5-293BO TELEGRAMS MONAP

is. The atomization takes place in a drying chamber the food liquid. The almost sudden evaporation of the moisture leads to the fact that with the carrier liquid Materials fed into the chamber are airborne dried.

Such systems are used for the production of dried, powdery or granular products in numerous, used in commercial applications, for example in the production of foodstuffs, chemicals, Pharmaceuticals, ceramics and the like.

Thus, the invention is generally in the field of drying. Within this area, it is particularly relevant the area where there is a conversion of a feed liquid into dried, flowable solids takes place within a stationary chamber in which the conversion takes place is carried out by subjecting the atomized feed liquid to a cyclanic air flow after which the solids are separated from the desiccant and removed by gravity.

Up until now it was common practice to remove the desiccant to provide laterally running drainage lines, which have the disadvantage that when they go into the collecting area The chamber protrudes, as was usual, these ducts tend to create an actual cyclonic air flow disturb. As for the relationship between the collection device of the chamber and the device for Removal of the desiccant from the chamber is concerned, so far has not actually been done with conventional systems Given symmetry. As a result, the separation efficiency of the plant was deteriorated. The industry

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endeavors to achieve an ever higher ratio between the proportion of product that is collected and discharged at the product outlet and the proportion of product that remains in the desiccant and is carried along by it while it is
through the discharge line provided for this purpose. A complete separation would of course mean that one hundred percent of the dried product flows through the. Product outlet are discharged, with no product solids being transported out with the discharged, gaseous desiccant. In practice, however, it would already be considered a very favorable result if, for example, a separation of the order of ninety percent of dried products that pass through the product outlet and ten percent of dried products that are discharged with the desiccant were achieved.

However, even this relationship is common with conventional ones
Facilities extremely difficult to reach.

Furthermore, it applies to conventional constructions that the
internal arrangement of their elements the risk of a
Accumulation of the product on the surfaces of the air discharge duct and the drying chamber increased, namely
because parts of the lines protrude in such a way that there is a risk of disruption or interruption of the
cyclonic air currents existed to such an extent that eddy currents, undesirable turbulence and the like were generated.

Atomization dryers according to the invention are set out in the claims marked.

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The invention is based on an atomization dryer, the - as known, "conventional dryer comprises a drying chamber, the upper portion of which has a cylindrical shape and constant diameter and merges into a lower section or outlet section, which is in the shape of an inverted cone or truncated cone.

Also as in the prior art, the product is carried by a stream of liquid into the upper inlet end fed into the chamber and subjected to centrifugal atomization there. Ih the top of the drying chamber heated dry air is blown in, which turns the feed liquid into a dried, powdery or granular product converts.

Furthermore, the drying chamber of the spray dryer according to the invention also designed as in the prior art so that a cyclonic flow of the Dry air is generated in the lower, conical section, thereby separating the dried product caused by the desiccant - in this case heated air.

According to the invention there is now a discharge device or withdrawal device for the desiccant in the form of a vertical arranged, open-top air discharge line provided, which is symmetrical to the drying chamber and in particular to whose conical section 'is formed and arranged completely concentrically therewith. This training leads to a special cooperation between the conical chamber and the drainage device for the desiccant, so that an improved separation of the dried product from the desiccant is achieved, whereby the already

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thinks the separation ratio is increased. will.

Furthermore, according to the invention, between the wall of the drying chamber and the drain line for the desiccant is a formed annular separation chamber into which the separated, dried product flows. Within this Separation chamber, according to the invention is a fluidizing, gas-permeable floor provided in the form of a double helix, so that all sections of the floor are inclined on the entire circumference of the separation chamber to a product outlet. There is one under the floor inclined storage chamber provided, which has constant depth over the entire chamber circumference and into which as a means for floating or fluidizing air is fed in, which is upward through the air-permeable Soil flows and thereby increases the flowability of the product, while it is due to gravity to the Moved product outlet.

An embodiment of the invention is shown in the drawings and will be explained in more detail below. Show it:

Fig. 1 is a plan view of an atomization dryer in which the air feed line is shown broken off is;

Figure 2 is a side view of the spray dryer with the air feed line being an air discharge line and a product discharge line are shown broken away;

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Fig. 3 is an enlarged, * excerpts, vertical Sectional view of the lower section or outlet section of the drying chamber, some sections are shown in elevation and the sectional view is the improved one Figure 9 shows a collection device, a discharge device and a flow device according to the invention;

FIG. K shows a horizontal sectional view on the same scale as FIG. 3 through the lower end section of the drying chamber;

5 is a further enlarged, more detailed, vertical sectional view in the same plane as FIG. 3 according to 5-5 in FIG. K, showing the product outlet; and

Fig. 6 is a partial view of the lower portion of the device, the ¥ and of the lower end of the drying chamber is broken away, so that the inclined fluidized bed floor and the associated storage chamber and the product outlet can be seen.

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A spray dryer according to the invention is designated as a whole by 10. Typical dimensions for a dryer of this type can be, for example, a total height of 12.19 m (40 ¹⁾ and a diameter of about 6.09 ro (20 x) at the point of the largest transverse dimension. Accordingly, and taking into account the fit of such a construction in terms of fill weight, it is clear that this construction includes an outer frame and a support construction. Neither this frame nor the support structure are shown, since their structure is known and their presentation and explanation would only unnecessarily expand the description.

In the context of this description, it should be sufficient to point out that, in the embodiment shown, a sideways air feed line is provided through which heated dry air is blown into a feed head 14 through which it enters a drying chamber 16. Furthermore, a line 17 for the feed liquid, which carries the solids to be dried in a liquid flow, leads into the ^{feed head 4 Xk.}

Inside the chamber 16, the feed liquid is atomized in a known manner at the lower end of the feed head Ik , usually by means of an atomization wheel 19. At the same time, the atomized liquid F is exposed to the heated dry air while it flows off the atomization wheel under the action of centrifugal forces. The solids are dried almost suddenly and then flow into a lower section 18 of the drying chamber. As Fig. 2 shows, this has the shape of an inverted cone butt it, which at its lower end in e & ie cylindrical, downwardly projecting extension 20 of the

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—Σ -

Drying chamber has a constant diameter.

Developed in the conical, lower section 18 of the chamber a cyclonic air flow, which is indicated by dashed directional arrows in FIG. 2. This will the separation of the dried solid products from promoted gaseous desiccant, with the result that the solids can flow into the extension 20, so that they can exit through a product outlet.

The previous description also applies to conventional atomization dryers, how they were built and operated up to now.

Reference is made below to FIG. 3 and at the same time to FIG. According to the invention, a vertically arranged discharge line is provided for the gaseous desiccant, which in this case comprises heated air, as has already been mentioned. This line is denoted by 22 and extends upwards and runs coaxially to the conical section 18 of the drying chamber. As can be seen from the drawings, the line protrudes upwards in the lower, smaller-diameter end of the conical or conical chamber section 18 and opens freely into this chamber section at a certain height above its lower end. At its upper end, the discharge line 22 is provided with an outwardly widened mouth or such an inlet Zk , whereby the absorption of the gaseous desiccant and its discharge through the line 22 is facilitated.

The line 22 forms, thus together with the lower section 18 of the drying chamber an annular product

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collection chamber 25, the cross-sectional area of which gradually increases decreases towards its lower outlet end.

As the dried product P flows in the collection chamber, it is carried by a cyclonic air flow which is generated in the conical lower end portion 18 of the drying chamber. The product then flows into an annular separating chamber 26 which is delimited by the wall of the extension 20 and the discharge line 22. In the separating chamber 26, the product flows freely to an inclined plied bed base which is generally denoted by and - as will be explained in more detail - is inclined sufficiently relative to the horizontal to ensure that the dried product P is free to a product outlet at the bottom Can flow at the end of the fluidized bed bottom. The fluidized bed floor is at a distance above and parallel to a correspondingly inclined lower end wall 28 of the extension of the drying chamber.

The special materials that make up the bottom 30 are can be different. For the invention, it is primarily important that the bottom 30 for a gaseous Flux must be permeable, while at the same time it should be designed so that clogging the gas-permeable pores of the soil through the Bottom to the product outlet flowing, dried product is prevented as possible.

In a preferred embodiment, it has proven advantageous to have a layered base 30 use. As extremely suitable for a top layer 32 Material a sintered metal can be used,

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for example a. porous material made of stainless steel, sold under the name "POR-O-SEPTA" and from the company Multi-Metal Wire Cloth, Inc., 501 Route 303 » Tappan, New York, IO983.

In the illustrated embodiment, the lower layer Jh is a mushroom which is so porous that it allows air flowing upward to pass through, which then also flows upward through the porous upper layer 32.

The support for the layered floor 30 can be arranged entirely inside the drying chamber. As shown, however, the outer edges of the layers 32 and 3k- may alternatively protrude through the extension 20 of the chamber, in which case the protruding outer edge portions are enclosed between retaining rings 36 and 38 of metal which are attached to the wall of the extension 20 of the Chamber above and below the bottom 30 are attached. The securing of the layers by the retaining rings can be supported by C-clamps (not shown) or the like, if this should be necessary.

For the invention it is of particular importance that the Bottom 30 is practically a double helix, i. E. that the bottom has a highest point 35 (Fig.3), of from which it runs inclined in both directions down to a lowest point 37, which is the highest point of the bottom is diametrically opposite. Thus, the floor 30 runs all the way from its highest Point 35 inclined downwards to its lowest point 37, so that the dry product P flowing down the cutting chamber in both directions around the air vent

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line 22 around from the highest point 35 to the lowest Point and a product outlet flows.

To float or fluidize the dry product P air is introduced into a storage chamber 40, which is between the bottom 30 and the lower end wall 28 is formed. Because of the parallel relationship between the floor and the lower end wall, the storage chamber 40 is corresponding inclined to the ground. Furthermore, it has a constant depth or - in other words - constant cross-sectional area over the entire extent of the storage chamber the air release line 22.

Air is introduced into the storage chamber through a fluid inlet line h2 which leads from an air inlet hk with an air filter to the storage chamber. The completely conventional air filter is not shown as such. In any case, it must be taken into account that, in addition to filtering the air before it is fed into the storage chamber, further conditioning of the air can be carried out. This means that it can be heated, cooled, dried or otherwise treated depending on the requirements of the particular situation.

In either case, the air entering the storage chamber flows upward through the porous layers 32 and 3 ^ and fluidizes the product P flowing along the floor 30 so that this product flows from the highest point 35 i * i in both directions along the path formed by the floor flows in the form of a double helix to an outlet 48 (see FIGS. 5 and 6) which is delimited by end plates k6 of the base which converge downwards. As shown in FIG. 6, the end plates k6 are spaced apart at their upper ends from

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one another and converge downward so that they form the product outlet 48 of the separating chamber 26. Simultaneously act the end plates 46 in such a way that they have a direct connection between the Speichererkararaer 40 and the separation chamber 26 except through the pores of the bottom.

As FIG. 6 shows, air flowing upwards through the pores fluidizes the product P, so that the product is discharged flows off in both directions from the lower end of the tray into the outlet 48, after which it flows into a product discharge line 50 with an inlet end 52 flows in.

Meanwhile, the cyclonic air flow flows inside the drying chamber following the separation of the Product P from the air flow in the plenum chamber over the outside of the discharge line 22 upwards and in the inlet end or mouth 24, after which the air through an extension piece 27 of the air discharge line is discharged. The extension piece passes through the lower end wall 28 as shown in FIGS is.

During practical operation of the spray dryer according to the invention has been shown that this has a very high efficiency in terms of the separation of the dried product results from the gaseous desiccant. This separation effect is on the order of ninety percent of the product that passes through the discharge line 50 go, ten percent of the product, going through the air vent line 22. At the same time, the Invention of product deposition on internal components the drying chamber is reduced to a level that is significantly less than in conventional systems in which

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the air discharge duct is a component that is sideways leads out of the lower end of the chamber, and in which further causes turbulence and disturbances of the desired, cause cyclonic air currents.

It is obvious that the discharge of the dried product through the discharge line 50 on any known Can be controlled manner, for example by means of a rotary air valve, not shown.

It is noteworthy that in a practical embodiment It was not necessary to use a blower device or the like. To the Fließ- or Fluidisiermxttel to be fed into the storage chamber 40 and then conveyed upwards through the permeable soil. Rather can the fluid into the storage chamber 40 through therein prevailing negative pressure are sucked in; In fact an installed system works in this way. However, the invention also includes the case that a fan or blower or similar device is used to introduce air into the storage chamber 40 and after to push through the porous bottom if this should be desired or necessary.

Patent claims:

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Claims (14)

Claims Atomization dryer with a drying chamber that has a lower product outlet section in the shape of an inverted one Has a truncated cone, a device for feeding dissolved or suspended in a carrier liquid Solids in the drying chamber, means arranged in the drying chamber for atomizing the liquid and a device for feeding a first, gaseous desiccant into the upper part of the drying chamber for drying the atomized liquid containing solids, solids dried therewith are generated, characterized by a discharge device (22) for the first, gaseous agent, which in the axial direction of the product outlet section (18) and its inlet (24) lies between the ends of the product outlet section, one for a second, gaseous medium which is used for Fluidizing or floating the dried solids is introduced, permeable bottom plate (30), which has a forms inclined path for the flow of the dried solids along the same and around the discharge means for the first, gaseous agent runs around the lower end of the drying chamber (16) and on the web one has the lowest point (37) and the lowest point has a product outlet (48) through which the dried Solids can be discharged from the chamber, the permeable bottom plate forming a device, too which also includes a storage chamber (4o) under the base plate and which is used to store the second, gaseous agent to guide through the base plate and to float or Fluidize the dried solids flowing along the bottom plate to the product outlet. 609835/0548 2. Spray dryer according to claim 1, characterized in that the discharge device comprises a line (22), which is concentric with the lower product outlet section (18) of the drying chamber (16) and together with this a collecting space (25) for dried solids is limited, its horizontal cross-sectional area gradually decreases towards the lower end of the drying chamber. 3 · atomization dryer according to claim 1, characterized in, that the drainage device comprises a vertically arranged line (22) which is concentric to the lower Product outlet section (18) of the drying chamber (16) runs upwards in this, has a constant diameter and together with the lower section of the drying chamber an annular collecting space (25) for dried solids forms in between, its horizontal cross-sectional area in the direction of the smaller end of the lower section the drying chamber gradually decreases. 4. Atomization dryer with a drying chamber that has a has lower product outlet section in the shape of an inverted truncated cone, means for feeding dissolved or suspended in a carrier liquid Solids in the drying chamber, means arranged in the drying chamber for atomizing the liquid and means for feeding a first, gaseous desiccant into the upper part of the chamber for drying the atomized liquid containing solids, characterized by a discharge device (22) for the first, gaseous means, which are in the axial direction of the product outlet section (18) and has an inlet (24), that between the ends of the product outlet section 60983 5/0548 -1ο- and one for a second, gaseous agent for Fluidizing or floating the resulting, dried pesticide-permeable base plate (30), which forms an inclined path for the flow of the dried solids along the same, the permeable Bottom plate forms a device which also includes a storage chamber (4o) under the bottom plate and which serves to conduct the second, gaseous agent through the base plate and to float or To fluidize the dried solids flowing along the bottom plate to the product outlet, whereby the bottom plate extends around the drainage means at the lower end of the drying chamber (16) and on the web one has the lowest point (37) at which the bottom plate has a product outlet (48) through which the dried Solids can be discharged from the chamber, wherein the discharge device is also arranged vertically Comprises line (22) which extends concentrically to the lower section (18) of the drying chamber (i6) in this upwards, has an inlet end (24) disposed between the ends of the lower portion of the drying chamber, constant Has diameter and together with the lower section of the drying chamber an annular collecting space (25) for forms dried solids, the horizontal cross-section of which sflache towards the smaller end of the lower Section of the drying chamber gradually decreases, and wherein the drying chamber has a cylindrical extension (20) having constant diameter in communication with the lower end of the lower portion of the drying chamber stands and protrudes downward from this, the line being concentric to this extension and together with it an annular separation chamber (26) delimits in which the dry solids from the first, gaseous medium 609835/0548 can be separated, and with the bottom plate on The lower end of the separation chamber runs around the pipe, so that you have the solids in connection with it Separation from the first, gaseous desiccant are supplied. 5 · Spray dryer according to claim 4, characterized in that the base plate (30) has the shape of a double helix with two opposite slopes along which the solids from a high point (35) on the helix to the deep point (37) in opposite Directions around the line (22) can flow. 6. atomization dryer according to claim 5 »characterized in that that the extension (20) contains an annular storage chamber (4o) below the floor plate (30) around the line (22) and the a second gas inlet (42, 44) which is used as a device for feeding in a second, fluidizing, gaseous agent is used in the storage chamber, the bottom plate for this fluidizing agent permeable is to cause the fluidizing agent to flow through the bottom plate into the web, thereby increasing the flowability the solids moving along the web due to gravity is increased. 7 · Spray dryer according to claim 6, characterized in that the base plate (30) lie one on top of the other Layers (32, 33), the upper of which is made of sintered metal and the lower of which is made of felt. 609835/0 5 48 8. Atomization dryer with a drying chamber which has a lower product outlet section in the shape of an inverted truncated cone, means for feeding solids dissolved or suspended in a carrier liquid into the drying chamber, means arranged in the drying chamber for atomizing the liquid and means for feeding a first , gaseous drying agent in the upper part of the drying chamber for drying the atomized, solids-containing liquid so that dried solids are produced, characterized by an outlet line (22) for the first, gaseous drying agent, which extends vertically and axially in the lower product outlet section (18, 20 ) runs and together with this in a corresponding manner vertically arranged, connected, annular collecting and separating spaces (25 »26) for dried solids bounds or forms an outlet (48) for the solids at the lower end of the collecting space, an annular one Bottom plate (30) which is permeable to a second, gaseous medium which is introduced to fluidize or float up the dried solids, and which forms the bottom of the collecting space and provides an inclined flow path along which the solids can flow to the outlet, wherein the permeable base plate forms a device which also includes a storage chamber (4o) under the base plate and which serves to guide the second, gaseous agent through the base plate and to cause the dried solids to float or fluidize, which is then to the product outlet flow. 9. atomization dryer according to claim 8, characterized in that the line (22) at its upper end a 09835/0548 Has inlet (24) for the first, gaseous agent, which is arranged symmetrically and concentrically to the lower portion (18) of the drying chamber (16), and that the Collection and separation spaces (25, 26) are arranged completely below the inlet of the line. · 10. atomization dryer according to claim 9 »characterized in that that the inlet (24) of the line (20) is widened and a mouth with a large diameter forms into which the first, gaseous desiccant can flow while it is withdrawn from the drying chamber will. 11. Spray dryer according to claim 8, characterized by a device for fluidizing the pesticides their way along the flow path to the outlet (48), which includes a fan which serves to blow the second, gaseous To conduct agent into the storage chamber (4o) and to push it through the base plate (30). 12. Spray dryer with a drying chamber, the one has lower product outlet section in the shape of an inverted truncated cone, means for feeding dissolved or suspended in a carrier liquid Solids in the drying chamber, arranged in the drying chamber means for atomizing the liquid guide and a device for feeding in a first, gaseous one Desiccant to the upper part of the drying chamber Drying the atomized, solids-containing liquid to produce dried solids through a drain line (22) for a desiccant, dio vertically and in the axial direction in the lower product 609835/0548 auslaßabsclinitt (18) runs and together with this a correspondingly vertically arranged, annular space (25, 26) for collecting the pesticides and Separation of the gas forms or limits a solids outlet (48) for the solids at the lower end of this Space, an annular base plate (30). which forms the floor of the room and creates an inclined flow path, along which the solids flow to the solids outlet can, a storage chamber (4o) which extends over the entire length of the bottom plate below this, the Base plate for a gaseous agent is permeable, and a device for feeding a second, gaseous Means in the storage chamber so that it flows up through the base plate and the dried solids floats or fluidizes moving along the flow path to the outlet. 13 · Spray dryer according to claim 8, characterized in that the base plate (30) is an annular element which around the line (22) inclined downwards to the solids outlet (48) so that the solids along flow this element to the outlet. 14. Spray dryer according to claim 8, characterized in that the base plate (30) is an annular Element is that has a high point (35) and in opposite directions on spiral paths with opposite slopes from the high point around the line (22) downwards, and that the high point the Fe stoffauslaß (48) is diametrically opposite, so that the bottom plate from opposite sides of the solids outlet to this, runs inclined downwards. 6098 3 5/0548 15 · Atomization dryer according to claim 12, characterized in that the bottom plate (30) is an annular element which has a high point (35) and slopes downwards in opposite directions around the conduit (22) from the high point, the high point is diametrically opposite the outlet (48) for the dried solids, so that the bottom plate runs inclined downwards on opposite sides of the outlet, and that the storage chamber (4o) is ring-shaped and is inclined correspondingly in the bottom plate, wherein the outlet comprises opposing walls (46) which channel the dried solids as it flows out through the outlet and close the connection between the storage chamber and the collection and separation spaces (25, 26) . 609835/0548