CN106537073B - Vertical flash tube dryer and method of cooling product deposits in the flash dryer - Google Patents
Vertical flash tube dryer and method of cooling product deposits in the flash dryer Download PDFInfo
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- CN106537073B CN106537073B CN201480080587.XA CN201480080587A CN106537073B CN 106537073 B CN106537073 B CN 106537073B CN 201480080587 A CN201480080587 A CN 201480080587A CN 106537073 B CN106537073 B CN 106537073B
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- 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
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- 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
- F26B17/101—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 the drying enclosure having the shape of one or a plurality of shafts or ducts, e.g. with substantially straight and vertical axis
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Abstract
A vertical flash tube dryer (1) defining an axial direction (α) and comprising a drying chamber (2) having a lower section (3) and an upper section (4). A feed inlet (5) for the product to be dried and an inlet (6) for the axial introduction of a drying gas are provided in the lower section. A cooling structure (8) for cooling the wall of the drying chamber is provided, and the cooling structure (8) consists of a gas cooling structure comprising an inlet (81) for cooling gas, the inlet (81) being located in the wall of the lower section (3) at a position between the inlet (6) for drying gas and the feed inlet (5), as seen in the axial direction.
Description
Technical Field
The invention relates to a substantially vertical flash tube dryer (flash tube dryer) defining an axial direction, comprising a drying chamber having a lower section and an upper section, in which drying chamber the lower section comprises a substantially cylindrical wall defining a radial direction perpendicular to the axial direction, and a cooling structure (cooling arrangement) for cooling at least a portion of at least one wall of the drying chamber, an inlet for a product to be dried and an inlet for axial introduction of a drying gas being provided in the lower section, and wherein the upper section comprises a wall and an outlet for dried product and discharged drying gas. The invention also relates to a method for cooling at least one wall of such a flash dryer.
Background
Flash drying is defined as the suspension and transport in a hot air streamAnd (4) drying the particles. The particles are derived from viscous feeds including pastes, filter cakes and high viscosity liquids such as agrochemicals, ceramics, dyes/pigments, inorganic and organic chemicals, and waste products such as sludge, sediment, and the like. Flash drying is often used as an alternative to or upstream of other drying units (e.g., fluid bed dryers). In a flash dryer, the product to be dried is fed to a drying chamber, through which the product is passed once, and some of its liquid content is evaporated and discharged. The flash dryer may be a so-called vortex decomposer dryer, an example of such a dryer being SWIRL fliidizerTM(GEA Niro) or a vertical flash tube dryer. In the vortex decomposer dryer, the feed is introduced into a drying chamber provided at its lower portion with a vertical rotational decomposer. Above the bottom, the drying chamber has an air inlet for introducing hot air in a tangential air flow, thereby creating a controllable swirling air flow together with the rotational decomposer. The impeller thus breaks up the feed and the liquid content of the feed is evaporated while being conveyed upwards in a swirling motion in the drying chamber.
However, in the flash dryer type according to the invention, i.e. the vertical flash tube dryer, the feed is only dispersed by introducing the drying gas due to the high air velocity prevailing in the flash dryer.
Regardless of the type of flash dryer, the short residence time allows for high temperatures of the inlet drying air due to the cooling effect provided by the rapid evaporation of moisture from the particle surface. The spent drying air containing the dried particles flows through a product/air outlet placed in the top of the drying chamber to a combined exhaust air purification and product recovery system.
Typical products suitable for flash drying are chemicals, such as polymers (e.g., s-PVC, PAN and ABS/MBS), or dyes, pigments, etc. Other products are food and feed products, for example, algal products.
Flash dryers typically operate at inlet temperatures of the drying gas which are often as high as 250 ℃ (depending on the heat sensitivity of the product). If the desired low residual moisture is not readily available in a simple flash dryer, special designs, such as a ring dryer, can be considered, or further drying can be performed. This may be a second flash dryer or more often a fluidized bed, where longer residence times are possible at lower and safer temperatures and unwanted over-drying may be avoided.
Due to the high inlet temperature of the drying gas, there is a risk of overheating the product in the lower part of the flash dryer, and therefore, many plants comprise means for cooling the walls in the lower part. In the upper part, evaporation of the water content of the product cools the mixture of product and drying gas, thereby lowering the temperature.
In the prior art, the means for cooling generally comprise a cooling jacket enclosing a wall, for example by forming the wall in a double-walled configuration in which cooling water is circulated. Water has excellent heat transfer characteristics and provides reliable cooling.
Another problem in flash dryers, besides the risk of overheating of the product, consists of deposits formed by the product adhering to the inside of the wall. This problem is particularly pronounced when the product is viscous due to thermoplasticity or hygroscopicity, or for example due to high levels of fat, or if the maximum processing temperature is relatively close to the melting point of the product (where partial melting may occur).
The deposits themselves are not desired, but become a substantial problem only when burned. Not only does combustion make cleaning more difficult, but the combustion deposits can become entrained with the drying gas and mix with the finished product, thereby reducing quality. This is known in the art as the formation of black specks, which is particularly undesirable if the white or light-colored product is improperly colored.
Summary of The Invention
It is an object of the present invention to provide a vertical flash tube dryer wherein the risk of burning deposits is reduced.
In a first aspect, this and further objects are achieved by providing a vertical flash tube dryer of the kind mentioned in the introduction, which is furthermore characterized in that the cooling structure consists of a gas cooling structure and comprises an inlet for cooling gas, which inlet is located in the wall of the lower section substantially at the level of the feed inlet.
In this way, the relevant part of the flash dryer is cooled in an efficient manner by the cooling gas, which after cooling the wall in the lower section follows the discharged drying gas and the dried product through the outlet. As a result, the drying process is not negatively affected to any significant extent as a result of the introduction of the lower temperature gas locally along the wall of the lower section. Overcomes the problems of overheating of the product and burning deposits encountered in the prior art. Without wishing to be bound by theory, it is believed that the fact that the deposits formed on the walls of the lower section are submerged in the cooling gas flow reduces the temperature of the deposits to a level that prevents combustion. Providing an external cooling jacket for the cooling water becomes redundant, thereby reducing the overall cost and complexity of manufacture and operation.
There is provided a substantially vertical flash tube dryer defining an axial direction, the substantially vertical flash tube dryer comprising a drying chamber having a lower section and an upper section, in which drying chamber the lower section comprises a substantially cylindrical wall defining a radial direction perpendicular to the axial direction, and a cooling structure for cooling at least a portion of at least one wall of the drying chamber, a feed inlet for a product to be dried and an inlet for axial introduction of a drying gas being provided in the lower section, and wherein the upper section comprises a wall and an outlet for dried product and discharged drying gas, characterized in that the cooling structure is constituted by a gas cooling structure and comprises an inlet for cooling gas, which inlet for cooling gas is located in the wall of the lower section substantially at the level of the feed inlet.
In a preferred embodiment, the cooling gas inlet is located at a position between the inlet for the drying gas and the feed inlet, as seen in the axial direction. This provides a particularly efficient cooling, since the walls of the lower section are cooled from the entry point of the feed and upwards.
Alternatively, the cooling gas inlet may be located within a distance corresponding to the diameter of the lower section of the flash tube above the feed inlet.
In one embodiment, the cooling gas inlet is formed as a substantially circumferential gap in the wall of the lower section.
In principle, the gap may be formed as a slit, slit portion or nozzle in the wall of the lower section. However, in a preferred development of the above-described embodiment, the substantially circumferential gap is provided by forming the wall of the lower section by a first wall section having a first diameter and a second wall section having a second diameter, the second diameter being larger than the first diameter, such that the gap is provided with a predefined extension in the radial direction. This provides a mechanically simple configuration which provides for a reliable formation of the cooling gas layer along the wall. Furthermore, the first wall section and the second wall section may be slightly movable relative to each other to accommodate dimensional changes of the portion of the flash dryer due to temperature changes.
The predefined extension of the gap in the radial direction may be in an interval of 5mm to 50mm, preferably in an interval of 10mm to 30 mm. The exact dimensions may be selected based on other dimensions of the flash dryer.
In a further development of the wall with respect to the lower section, an embodiment is preferred in which the first wall section has an extension in the axial direction relative to the extension of the second wall section, so that an overlap in the axial direction is formed between the first wall section and the second wall section, which overlap is preferably in the range of 50mm to 500 mm. In this way, the formation of an axial flow of cooling gas is promoted.
In another embodiment, which facilitates the introduction of the cooling gas, the cooling structure comprises a disperser for the cooling gas connected to the cooling gas inlet.
In a preferred embodiment of this embodiment, a lower part of the cooling gas disperser is connected to the first wall section and an upper part of the cooling gas disperser is connected to the second wall section. An advantage of this configuration is that since the wall sections can move slightly relative to each other and relative to the air disperser, dimensional changes due to temperature changes are accommodated.
Additionally, in an even more preferred embodiment, the cooling gas disperser is provided with a plurality of vanes positioned with respect to said gap. In addition to providing a reliable means of achieving a flow of cooling gas along the wall of the lower section, the vane acts as a spacer element such that the gap is sufficiently wide over the entire circumference, as the vane maintains the distance between the first and second wall sections even if manufacturing tolerances and/or temperature-related dimensional variations act to reduce the extension of the gap at specific locations along the circumference.
Each vane may have a predefined extension in the radial direction that corresponds to or is slightly lower than the predefined extension of the gap. The blade may be connected to one or both wall sections, e.g. only to the first wall section.
In a preferred embodiment, the blades extend in a radial direction and parallel to the axial direction. This configuration is advantageous in directing the flow of cooling gas only in the axial direction.
In the above-mentioned specific embodiment, the first wall section has an extension in the axial direction relative to the extension of the second wall section, such that an overlap in the axial direction is formed between the first and second wall sections, which overlap preferably lies in the range of 50mm to 500 mm. In a further development of this embodiment, it is furthermore preferred that the extension of the blade in the axial direction corresponds to the size of the overlap between the first and second wall sections. By this configuration, the blades act as spacer elements in the entire overlap and also have a sufficient length in the axial direction to ensure a proper axial flow of cooling gas along the wall of the lower section.
In a further preferred embodiment, the wall of the upper section has a diameter which varies in the axial direction, the diameter of the upper section preferably increasing by a certain length in the axial direction starting at the transition from the lower section. Since the drying gas is introduced into the lower section of the flash dryer and thus has a relatively small diameter, a venturi effect (venturi effect) is created, locally increasing the velocity of the drying gas. This enhances the effect of breaking down and entraining the feed, which can still be relatively compact and moist at the point of introduction.
The size of the flash dryer is selected according to the desired specifications. In one embodiment, the diameter of the lower section is in the range of 0.2m to 3m, preferably in the range of 0.5m to 2 m.
To ensure that the feed is introduced into the drying gas, in one embodiment, the one or more inlets protrude into the lower section, preferably by a distance of 10mm to 500 mm.
The ratio between the distance the feed inlet projects into the lower section and the diameter of the lower section is selected according to specifications but will advantageously be in the range of 0.02 to 0.45.
In a further development of this embodiment, wherein the predefined extension of the gap in the radial direction is in an interval of 5mm to 50mm, preferably in an interval of 10mm to 30mm, the ratio between the predefined extension of the gap in the radial direction and the diameter of the lower section is within 0.01 to 0.05.
The invention is applicable to vertical flash tube dryers of most sizes, each appropriately sized. The total height of the drying chamber may for example be in the interval of 5m to 25m and the height of the lower section may be in the interval of 0.5m to 5 m.
In a second aspect, there is provided a method for cooling product deposits in a flash dryer as described above, the method comprising the steps of: the method comprises the steps of supplying a product feed via a feed inlet, supplying a drying gas at a predefined temperature and a predefined flow rate, contacting the product with the drying gas to provide an upward flow of the drying gas and the product to be dried in an axial direction, supplying a cooling gas via an inlet of a cooling structure to provide an upward flow of the cooling gas in an axial direction along a wall of at least a lower section of the drying chamber, and allowing a flow of the cooling gas to reduce the temperature of deposits at the wall of at least the lower section.
In some embodiments, the cooling gas is supplied at a flow rate of 30m/s to 90 m/s.
In some embodiments, the flow rate of the cooling gas is in an amount of 2% to 20%, preferably in an amount of 4% to 15%, compared to the cumulative rate of the drying gas and the cooling gas.
In some embodiments, the cooling gas is supplied at a flow rate substantially corresponding to a predefined flow rate of the drying gas.
In some embodiments, the cooling gas is supplied at a temperature of ambient air to 110 ℃, preferably 50 ℃ to 90 ℃.
In some embodiments, the predefined temperature of the drying gas is in the range of 150 ℃ to 250 ℃.
In some embodiments, the flow of Cooling Gas (CG) occurs only in the axial direction.
In some embodiments, the step of allowing the flow of Cooling Gas (CG) to reduce the temperature of the deposits at the walls of at least the lower section prevents the deposits from burning.
Additional details and advantages will appear from the detailed description and the appended claims.
Brief Description of Drawings
The invention will be described in more detail below by means of the following description of preferred embodiments and with reference to the attached drawings, in which:
figure 1 shows a schematic overview of a plant comprising a flash dryer in an embodiment of the invention;
fig. 2 and 3 show schematic side and front views, respectively, of details of an embodiment of a flash dryer according to the present invention;
fig. 4 is a schematic partial cross-sectional view on a larger scale of a detail of an embodiment of a flash dryer corresponding to the flash dryer shown in fig. 2 and 3;
FIG. 5 is a schematic partial perspective view showing details of the flash dryer in FIG. 4;
fig. 6 is a schematic view from above showing a detail of the flash dryer in fig. 4 and 5;
FIG. 7 is an enlarged schematic partial perspective view corresponding to FIG. 5 of another embodiment of a flash dryer according to the present invention;
fig. 8 to 11 show diagrammatic representations of computer simulated examples of temperature distributions when operating a flash dryer with a cooling device according to the invention (fig. 8 and 10) and when not using the cooling device (fig. 9 and 11); and
fig. 12 and 13 are schematic partial cross-sectional side views illustrating the cooling of a prior art flash dryer (fig. 12) and the operating principle of operating with a cooling structure according to the present invention (fig. 13), respectively.
Detailed description of the invention and preferred embodiments
In fig. 1, a vertical flash tube dryer, generally designated 1, is shown in a location in a dryer installation comprising a plurality of known operating units. The feed consisting of the product to be dried is introduced at a feed inlet 5 at the lower end of the flash dryer 1 and the drying gas is introduced via a drying gas inlet 6, which drying gas inlet 6 is in turn connected to a heating device, a supply conduit 62 and an air box 61 in a manner known per se. At the upper end of the flash dryer 1 an outlet 7 provides dried product and exhausted drying gas. Further operating units, including cyclone and/or filter units, further drying units and product recovery units, are not described in detail.
Referring now to fig. 2 and 3, it is shown how a vertical flash tube dryer 1 defines an axial direction α and comprises a drying chamber 2 having a lower section 3 and an upper section 4. The lower section 3 comprises a substantially cylindrical wall defining a radial direction perpendicular to the axial direction α, and is provided with a feed inlet 5 for the product to be dried and an inlet 6 for the axial introduction of a drying gas. The upper section 4 comprises a wall and an outlet 7. A cooling structure, which will be described in more detail below, is provided for cooling at least a portion of at least one wall of the drying chamber 2, here the wall of the lower section 3. There may be more than one inlet 5, e.g. two inlets 5 placed opposite each other at the same horizontal plane.
The cooling structure is constituted by a gas cooling structure, generally indicated as 8, and is therefore the only cooling structure of the flash dryer. As shown in detail in the schematic view of fig. 4, the cooling structure 8 comprises an inlet 81 for cooling gas in the lower section 3. In the currently preferred embodiment, the cooling gas inlet 81 is located at a position between the inlet 6 for drying gas and the feed inlet 5, as seen in the axial direction. Alternatively, the cooling gas inlet may be located within a distance corresponding to the diameter of the lower section of the flash tube above the feed inlet.
In the embodiment shown, the cooling gas inlet is formed as a substantially circumferential gap in the wall of the lower section 3. A substantially circumferential gap is provided by the wall forming the lower section 3 by a first wall section 31 having a first diameter and a second wall section 32 having a second diameter, the second diameter being larger than the first diameter, such that the gap is provided with a predefined extension in the radial direction. The gap thus has an extension represented by the distance between the line g representing the contour of the second wall section 32 and the contour of the first wall section 31. The predefined extension of the gap in the radial direction is typically in the interval of 5mm to 50mm, preferably in the interval of 10mm to 30 mm. In the embodiment shown, the extension of the gap is about 20 mm. The part of the flash dryer 1 comprising the first wall section 31 and the second wall section 32 is typically made of metal, e.g. steel of suitable dimensions and properties.
As is most clearly shown in the schematic view of fig. 4, the first wall section 31 has an extension in the axial direction α relative to the extension of the second wall section 32, so that an overlap in the axial direction is formed between the first wall section 31 and the second wall section 32. As shown, the overlap is the difference between the upper edge of the first wall section 31, represented by line h31, and the lower edge of the second wall section 32, represented by line h 32. The overlap will typically be in the range 50mm to 500mm, here 200 mm.
In the embodiment shown, the cooling structure 8 comprises a disperser 82 for cooling gas connected to a cooling gas inlet 81. The cooling gas disperser 82 is connected to a supply of cooling gas, which is not shown.
The lower portion 82a of the cooling gas disperser 82 is connected to the first wall section 31, and the upper portion 82b of the cooling gas disperser 82 is connected to the second wall section 32. The connection may occur in any suitable manner, such as by welding.
The cooling gas disperser 82 is provided with a plurality of vanes 83 positioned in connection with said gap.
Each blade 83 has a predefined extension in the radial direction, indicated by the line w. The extension is here slightly lower than the predefined extension of the gap, but the vane 83 may also span substantially the entire distance between the first wall section 31 and the second wall section 32.
In the embodiment shown, the vane 83 is connected only to the first wall section 31, also typically by welding. The vanes 83 extend generally in a radial direction and parallel to the axial direction. The extension of the vane 83 in the axial direction here corresponds to the size of the overlap between the first wall section 31 and the second wall section 32. The vanes 83 have a substantially larger dimension in the axial direction than in the radial direction.
The present invention is applicable to most sizes of vertical flash tube dryers, with each section appropriately sized. The total height of the drying chamber may for example be in the interval of 5m to 25m and the height of the lower section in the interval of 0.5m to 5 m. Here, the total height is about 15m and the height of the lower section is 3 m. The diameter of the lower section 3 is typically in the range of 0.2 to 3m, preferably in the range of 0.5 to 2 m. Here, the diameter is about 1 m.
Returning to fig. 2 and 3, it is shown how the wall of the upper section 4 has a diameter that varies in the axial direction, the diameter of the upper section 4 increasing by a certain length in the axial direction starting at the transition from the lower section 3. Towards the upper end, the diameter of the upper section 4 decreases again in the direction of the outlet 7.
In the embodiment shown, the inlet 5 projects into the lower section 3, preferably by a distance of 10mm to 500 mm. Here, the distance is about 350 mm. The ratio between the distance the inlet 5 protrudes into the lower section 3 and the diameter of the lower section 3 is in the range of 0.02 to 0.45. In a particular embodiment, this ratio is therefore approximately 0.035. As shown in fig. 7, the inlet 5 is provided with a cap section 51, the cap section 51 mainly preventing product from accumulating and depositing on top of the inlet, but may also have some importance for reducing pressure losses from the flow of the drying gas and the cooling gas.
It follows that the ratio between the predefined extension of the gap in the radial direction and the diameter of the lower section 3 is in the range of 0.01 to 0.05. In a particular embodiment, this ratio is about 0.02.
Hereinafter, the operation of the vertical flash tube dryer 1 will be described in detail. Additionally, reference is made to fig. 13 which shows the principle of operation.
A method for cooling product deposits in a flash dryer of the kind described above comprises the steps of: the product feed is supplied via the feed inlet 5, the drying gas is supplied at a predefined temperature and a predefined flow rate, the product is brought into contact with the drying gas to provide an upward flow F of the drying gas and the product to be dried in the axial direction, the cooling gas is supplied via the inlet 81 of the cooling structure 8 to provide an upward flow CG of the cooling gas in the axial direction along the wall of at least the lower section 3 of the drying chamber 2, and the flow CG of the cooling gas is allowed to reduce the temperature of the deposits at the wall of at least the lower section 3.
In fig. 13, the deposit is represented by a deposit 100a on the wall (here the second wall section 32). In fig. 12, a prior art cooling structure in the form of a cooling jacket of double-walled configuration is shown, in which cooling water CW circulates, showing the corresponding deposit 100 b.
The values of temperature, flow rate and flow rate of the cooling gas are selected according to the size of the flash dryer and the corresponding parameters of the drying gas. Typical intervals are described here and simulations with specific values will be further described. The cooling gas is supplied at a flow rate of 30m/s to 90 m/s. The flow rate of the cooling gas is in an amount of 2% to 20%, preferably 4% to 15%, compared to the cumulative rate of the drying gas and the cooling gas. The cooling gas is supplied at a flow rate substantially corresponding to the predefined flow rate of the drying gas. The cooling gas is supplied at a temperature of ambient air of up to 110 c, preferably 50 c to 90 c. The predefined temperature of the drying gas is in the range of 150 ℃ to 250 ℃. The choice of cooling gas temperature depends on the temperature of the drying gas and the product characteristics, but may typically be ambient air or as indicated above.
Examples
To illustrate the operation of the vertical flash tube dryer, a computer simulation of the configuration as in the above-described embodiment of flash dryer 1 was performed. Fig. 8 to 11 show diagrammatic representations of the temperature distribution when operating a flash dryer with a cooling device according to the invention (fig. 8 and 10) and without a cooling device (fig. 9 and 11), respectively.
The temperature of the drying gas at inlet 6 was set to 210 ℃, and the feed temperature at inlet 5 was set to 5 ℃ to 50 ℃. The temperature of the cooling gas was set to 80 ℃.
The flow rate measured in kg/h of the drying gas was 127,000kg/h and the flow rate of the cooling gas was 15,000kg/h, the flow rate of the cooling gas being 10.6% compared to the cumulative rate of the drying gas and the cooling gas.
The velocity of the drying gas was 70 m/s. The simulation was performed with cooling gas velocities of 30m/s, 50m/s, 70m/s and 90 m/s. A velocity of 30m/s results in cooling of only a smaller part of the wall of the lower section. A velocity of 90m/s results in a relatively large influence on the flow of drying air in the upper section of the flash dryer. Speeds of 50m/s and 70m/s lead to satisfactory cooling and a moderate effect on the drying air.
The flow CG of the cooling gas enables to reduce the measured temperature of the deposit 100a at the wall of the lower section and the burning of the deposit 100a is reduced or even eliminated compared to the corresponding deposit 100b when the cooling structure 8 is not operated.
Although the flash dryer in the illustrated embodiment is described as a vertical flash tube dryer with only a generally axial flow of drying gas, it is envisaged that the basic principles of the invention may function in a vortex flash dryer which operates with a swirling flow of drying gas and impeller disintegration of the feed in the lower section.
The invention should not be considered limited to the embodiments shown and described above, but various modifications and combinations of features may be made without departing from the scope of the following claims.
Claims (37)
1. A substantially vertical flash pipe dryer (1) defining an axial direction (a), the substantially vertical flash pipe dryer (1) comprising a drying chamber (2) having a lower section (3) and an upper section (4), in which drying chamber the lower section comprises a substantially cylindrical wall defining a radial direction perpendicular to the axial direction (a), and a cooling structure (8) for cooling at least a portion of at least one wall of the drying chamber, an inlet (5) for a product to be dried and an inlet (6) for the axial introduction of a drying gas being provided in the lower section, and wherein the upper section (4) comprises a wall and an outlet (7) for the dried product and the discharged drying gas, the cooling structure (8) being constituted by a gas cooling structure and comprising an inlet (81) for a cooling gas, said inlet for cooling gas (81) being located in the wall of the lower section (3) substantially at the level of the feed inlet (5), characterized in that the cooling structure (8) comprises a disperser (82) for cooling gas connected to the inlet for cooling gas (81),
wherein the inlet for cooling gas is formed as a substantially circumferential gap in the wall of the lower section (3),
wherein the substantially circumferential gap is provided by forming the wall of the lower section (3) by a first wall section (31) having a first diameter and a second wall section (32) having a second diameter, the second diameter being larger than the first diameter, such that the substantially circumferential gap is provided with a predefined extension (g) in the radial direction,
wherein a lower portion (82a) of the disperser (82) is connected to the first wall section (31) and an upper portion (82b) of the disperser (82) is connected to the second wall section (32),
wherein the disperser (82) is provided with a plurality of blades (83) positioned in relation to the substantially circumferential gap.
2. A substantially vertical flash pipe dryer according to claim 1, wherein the inlet (81) for cooling gas is located at a position between the inlet (6) for axial introduction of drying gas and the feed inlet (5), seen in the axial direction.
3. A substantially vertical flash tube dryer according to claim 1, wherein the inlet for cooling gas is located within a distance corresponding to the diameter of the lower section (3) above the feed inlet (5).
4. A substantially vertical flash pipe dryer according to claim 3, wherein said predefined extension (g) of said substantially circumferential gap in said radial direction is in an interval of 5mm to 50 mm.
5. A substantially vertical flash pipe dryer according to claim 4, wherein said predefined extension (g) of said substantially circumferential gap in said radial direction is in the interval of 10mm to 30 mm.
6. A substantially vertical flash pipe dryer according to any one of claims 3 to 5, wherein the first wall section (31) has an extension (h31) in the axial direction (a) relative to an extension (h32) of the second wall section (32) such that an overlap in the axial direction is formed between the first wall section (31) and the second wall section (32).
7. A substantially vertical flash pipe dryer as claimed in claim 6, wherein the overlap is in the range of 50mm to 500 mm.
8. A substantially vertical flash pipe dryer according to claim 7, wherein each vane (83) has a predefined extension (w) in the radial direction, said predefined extension (w) of said vane (83) corresponding to said predefined extension (g) of the substantially circumferential gap or being slightly lower than said predefined extension (g) of the substantially circumferential gap.
9. A substantially vertical flash pipe dryer according to claim 7 or 8, wherein the vanes (83) are connected only to the first wall section (31).
10. A substantially vertical flash pipe dryer according to any one of claims 7-8, wherein the vanes (83) extend in the radial direction and parallel to the axial direction.
11. A substantially vertical flash pipe dryer according to claim 9, wherein the vanes (83) extend in the radial direction and parallel to the axial direction.
12. A substantially vertical flash pipe dryer according to claim 1, wherein each vane (83) has a predefined extension (w) in the radial direction, said predefined extension (w) of said vane (83) corresponding to said predefined extension (g) of the substantially circumferential gap or being slightly lower than said predefined extension (g) of the substantially circumferential gap.
13. A substantially vertical flash pipe dryer according to claim 1, wherein the vanes (83) are connected only to the first wall section (31).
14. A substantially vertical flash pipe dryer according to claim 12, wherein the vanes (83) are connected only to the first wall section (31).
15. A substantially vertical flash pipe dryer according to any one of claims 12-14, wherein the vanes (83) extend in the radial direction and parallel to the axial direction.
16. A substantially vertical flash pipe dryer according to any one of claims 12-14, wherein the extension of the vanes (83) in the axial direction corresponds to the size of the overlap between the first wall section (31) and the second wall section (32).
17. A substantially vertical flash pipe dryer according to any one of claims 1-3, 4-5, 7, 8 and 11-14, wherein the wall of the upper section (4) has a diameter that varies along the axial direction.
18. A substantially vertical flash pipe dryer according to claim 17, wherein the diameter of the upper section (4) increases by a length in the axial direction starting at the transition from the lower section (3).
19. A substantially vertical flash pipe dryer according to any one of claims 1-3, 4-5, 7, 8, 11-14 and 18, wherein the diameter of the lower section (3) is in the range of 0.2-3 m.
20. A substantially vertical flash pipe dryer according to claim 19, wherein the diameter of the lower section (3) is in the range of 0.5 to 2 m.
21. A substantially vertical flash pipe dryer according to any one of claims 1-3, 5 and 7, 8, 11-14 and 18 and 20, wherein the feed inlet (5) protrudes into the lower section (3).
22. A substantially vertical flash pipe dryer according to claim 21, wherein the feed inlet (5) protrudes into the lower section (3) a distance of 10mm to 500 mm.
23. A substantially vertical flash pipe dryer according to claim 19, wherein the feed inlet (5) protrudes into the lower section (3).
24. A substantially vertical flash pipe dryer according to claim 23, wherein the feed inlet (5) protrudes into the lower section (3) a distance of 10mm to 500 mm.
25. A substantially vertical flash pipe dryer according to claim 4, wherein the feed inlet (5) protrudes into the lower section (3).
26. A substantially vertical flash pipe dryer according to claim 25, wherein the feed inlet (5) protrudes into the lower section (3) a distance of 10mm to 500 mm.
27. A substantially vertical flash pipe dryer according to claim 23 or 24, wherein the ratio between the distance the feed inlet (5) protrudes into the lower section (3) and the diameter of the lower section (3) is in the range of 0.02 to 0.45.
28. A substantially vertical flash pipe dryer according to claim 25 or 26, wherein the ratio between the predefined extension (g) of the substantially circumferential gap in the radial direction and the diameter of the lower section (3) is in the range of 0.01 to 0.05.
29. A substantially vertical flash pipe dryer according to any one of claims 1-3, 5, 7, 8, 11-14, 18 and 20 and 22-26, wherein the total height of the drying chamber (2) is located in the interval of 5-25 m and the height of the lower section (3) is located in the interval of 0.5-5 m.
30. A method for cooling product deposits in a substantially vertical flash tube dryer according to any one of claims 1 to 13, comprising the steps of:
supplying a product feed via said feed inlet (5),
the drying gas is supplied at a predefined temperature and a predefined flow rate,
contacting the product with a drying gas to provide an upward flow (F) of drying gas and product to be dried in said axial direction,
supplying cooling gas via vanes (83) of the disperser at the inlet (81) for cooling gas of the cooling structure (8) to provide an upward flow (CG) of cooling gas in the axial direction along the wall of at least the lower section (3) of the drying chamber (2), and
allowing a flow (CG) of cooling gas to reduce the temperature of deposits at the walls of at least the lower section (3),
wherein the cooling gas is supplied at a temperature of ambient air up to 110 ℃, and
wherein the predefined temperature of the drying gas is in the range of 150 ℃ to 250 ℃.
31. The method of claim 30, wherein the cooling gas is supplied at a temperature of 50 ℃ to 90 ℃.
32. The method of claim 30, wherein the cooling gas is supplied at a flow rate of 30 to 90 m/s.
33. The method of any one of claims 30 to 32, wherein the flow rate of the cooling gas is in an amount of 2% to 20% compared to the cumulative rate of drying gas and cooling gas.
34. The method of claim 33, wherein the flow rate of the cooling gas is in an amount of 4% to 15% compared to the cumulative rate of the drying gas and the cooling gas.
35. A method according to claim 32 or 34, wherein the cooling gas is supplied at a flow rate substantially corresponding to a predefined flow rate of the drying gas.
36. The method of any one of claims 30 to 32 and 34, wherein the flow of Cooling Gas (CG) occurs only in the axial direction.
37. The method according to any one of claims 30-32 and 34, wherein the step of allowing a flow (CG) of cooling gas to reduce the temperature of deposits at the walls of at least the lower section (3) prevents deposit combustion.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/DK2014/050225 WO2016008484A1 (en) | 2014-07-16 | 2014-07-16 | A vertical flash tube dryer, and method for cooling product deposits in such a flash dryer |
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| Publication Number | Publication Date |
|---|---|
| CN106537073A CN106537073A (en) | 2017-03-22 |
| CN106537073B true CN106537073B (en) | 2020-09-15 |
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| CN201480080587.XA Active CN106537073B (en) | 2014-07-16 | 2014-07-16 | Vertical flash tube dryer and method of cooling product deposits in the flash dryer |
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| Country | Link |
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| CN (1) | CN106537073B (en) |
| WO (1) | WO2016008484A1 (en) |
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| CN109631499A (en) * | 2018-12-19 | 2019-04-16 | 西安近代化学研究所 | A kind of quick continuous drying technique of insensitive energetic material |
| CN116294525A (en) * | 2021-12-13 | 2023-06-23 | 青岛海湾化学股份有限公司 | Flash drying tower and flash drying system |
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| US2054441A (en) * | 1932-01-29 | 1936-09-15 | Western Condensing Co | Method and apparatus for drying liquid containing materials |
| GB947134A (en) * | 1962-07-24 | 1964-01-22 | Prvni Brnenska Strojirna Zd Y | Improvements in or relating to combustion chambers of gas turbines |
| US3621902A (en) * | 1969-02-01 | 1971-11-23 | Morinaga Milk Industry Co Ltd | Apparatus for spray drying milk or the like |
| CN85104951A (en) * | 1985-06-28 | 1987-01-07 | 国际壳牌研究有限公司 | Cool off the method and apparatus that a kind of sweat goes out gas |
| US5227018A (en) * | 1989-09-26 | 1993-07-13 | Niro A/S | Gas distributor and heater for spray drying |
| CN1207168A (en) * | 1995-12-30 | 1999-02-03 | 株式会社奈良机械制作所 | Pulverized body drying method and apparatus |
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| GB402707A (en) * | 1932-08-27 | 1933-12-07 | Paul Rosin | Improvements relating to pneumatic drying devices |
| GB647657A (en) * | 1942-04-16 | 1950-12-20 | Prep Ind Combustibles | A turbulent pneumatic drying device |
| US3254420A (en) * | 1963-04-09 | 1966-06-07 | Midland Ross Corp | Method and apparatus for the treatment of moisture containing materials in gaseous streams |
| US5658142A (en) * | 1995-02-14 | 1997-08-19 | Novadyne Ltd. | Material drying system |
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- 2014-07-16 WO PCT/DK2014/050225 patent/WO2016008484A1/en active Application Filing
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2054441A (en) * | 1932-01-29 | 1936-09-15 | Western Condensing Co | Method and apparatus for drying liquid containing materials |
| GB947134A (en) * | 1962-07-24 | 1964-01-22 | Prvni Brnenska Strojirna Zd Y | Improvements in or relating to combustion chambers of gas turbines |
| US3621902A (en) * | 1969-02-01 | 1971-11-23 | Morinaga Milk Industry Co Ltd | Apparatus for spray drying milk or the like |
| CN85104951A (en) * | 1985-06-28 | 1987-01-07 | 国际壳牌研究有限公司 | Cool off the method and apparatus that a kind of sweat goes out gas |
| US5227018A (en) * | 1989-09-26 | 1993-07-13 | Niro A/S | Gas distributor and heater for spray drying |
| CN1207168A (en) * | 1995-12-30 | 1999-02-03 | 株式会社奈良机械制作所 | Pulverized body drying method and apparatus |
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| Publication number | Publication date |
|---|---|
| WO2016008484A1 (en) | 2016-01-21 |
| CN106537073A (en) | 2017-03-22 |
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