GB2053714A - Stabilizing fluidised beds - Google Patents
Stabilizing fluidised beds Download PDFInfo
- Publication number
- GB2053714A GB2053714A GB7927140A GB7927140A GB2053714A GB 2053714 A GB2053714 A GB 2053714A GB 7927140 A GB7927140 A GB 7927140A GB 7927140 A GB7927140 A GB 7927140A GB 2053714 A GB2053714 A GB 2053714A
- Authority
- GB
- United Kingdom
- Prior art keywords
- partition
- processed
- medium
- particles
- casing
- 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.)
- Granted
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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
- F26B3/06—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 flowing through the materials or objects to be dried
- F26B3/08—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 flowing through the materials or objects to be dried so as to loosen them, e.g. to form a fluidised bed
- F26B3/092—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 flowing through the materials or objects to be dried so as to loosen them, e.g. to form a fluidised bed agitating the fluidised bed, e.g. by vibrating or pulsating
- F26B3/0923—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 flowing through the materials or objects to be dried so as to loosen them, e.g. to form a fluidised bed agitating the fluidised bed, e.g. by vibrating or pulsating by mechanical means, e.g. vibrated plate, stirrer
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
- B01J8/24—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles according to "fluidised-bed" technique
- B01J8/38—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles according to "fluidised-bed" technique with fluidised bed containing a rotatable device or being subject to rotation or to a circulatory movement, i.e. leaving a vessel and subsequently re-entering it
- B01J8/382—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles according to "fluidised-bed" technique with fluidised bed containing a rotatable device or being subject to rotation or to a circulatory movement, i.e. leaving a vessel and subsequently re-entering it with a rotatable device only
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Microbiology (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physical Or Chemical Processes And Apparatus (AREA)
Abstract
A method of processing e.g. drying solid, solute, dispersed, sludge- like or semiplastic material, wherein the particles of the material to be processed are set in free motion by a combined action of at least one stream of gas and/or liquid and mechanical agitation, while the whole system of the freely moving particles is caused to perform a rotary motion about a horizontal or oblique axis. An apparatus for carrying out the method comprises a casing (1) subdivided by a curved fluidization partition (2) into an upper zone, which includes a rotary agitator (3, 4), and a lower zone for supplying at least one stream of gaseous and/or liquid medium through the partition, the upper zone being provided with means (5, 10; 14; 6) for supplying the material to be processed and for discharging the finished product and the medium. <IMAGE>
Description
SPECIFICATION
A method of and an apparatus for processing solid, solute, dispersed or semiplastic material with gas and/or liquid
This invention relates to a method of processing solid, solute, dispersed, sludge-like, or semiplastic material, particularly material a layer or bed of which is difficult to expand or fluidize with gas and/or liquid, and to an apparatus for carrying out said method.
In the methods, known hitherto, for processing material in an expanded especiallyfluidized layer, the particles are set in free motion by a stream or an expanding medium only, the latter being, in principle, fed into the processed material at a fluidization velocity. This technique often uses a liquid or a mixture of liquid and gas asthe expanding medium.
In some cases, media of varying physical properties (e.g. temperature, pressure, humidity) and/or chemical properties (e.g. oxidizing atmosphere, reducing atmosphere) are used sequentially in the course of processing.
The use of a fluidizing medium by itself may be sufficient in a great number of uses to produce a sufficient and well working expanded layer and to improve the process.
The respective plants used for the fluidization processes are designed to suit these methods.
Mostly they consist of vertical casings widening upwardly and divided by means of flat grates into a working compartment and a lower portion used for the intake of expanding and working media, this portion being divided, in some cases, into separate chambers used for the independent intake of media having different physical parameters, and/or different chemical properties for the successive processing of the fluidized material.
An equipment is also known, formed by a horizontally situated cylindrical casing, secured by grates in the lower and upper opposite portions and provided inside with rotary pocket blades dividing the working space of the casing into separate compartments. The blades are adapted also for conveying the processed material in the working direction as far as the outlet branch. Under the lower portion of the cylindrical casing there are separate chambers serving for the independent intakes of fluidizing and working media of dissimilar properties; a similar system of chambers is arranged above the upper grate of the cylindrical casing, serving as outlets of the fluidizing medium and the products of reaction.
All the plants are provided with corresponding branches in the upper and lower portions serving for feeding the material to be processed and the fluidizing and working media, and for the discharge of the fluidizing and working media after the operation has been finished, and/or for the withdrawai of the reaction products and the removal of finished products, as well. Branches for the supply of the material to be processed are located on the front walls of the plants.
The methods described and the corresponding plants have a common drawback in that they do not enable the processing of materials whose specific physical properties and/or special shape of particles, e.g. needleshaped crystals, limit the possibility of application of the technology with a fluidized layer.
In such cases it is necessary to overcome the mechanical resistance of the layer caused by the cohesion of the individual particles; this may be attained by such a velocity of the gas stream which causes the following process to have the character of pneumatic conveying. Such properties has e.g. the antibioticum chloramphenicol which hardly ever forms a fluidized layer with free motion of particles, e.g. when attempts are made to dehydrate it by using fluid technology. This technology has been used to take advantage of the fluidal process for the dehydration, i.e. to make use of the large specific surface, of the intimate contact between the gas and solid phases, and effective heat and mass transfer, which enable working at a low temperature in the fluidized layer and avoid thermal decomposition of the product. Chloramphenicol could not be dehydrated in any plant for fluid processes.
There are many other substances of a similar character. However, even substances having otherwise suitable physical properties may be brought, e.g. at a high moisture content, into a fluidized state only with great difficulty. Channelling, pistoning, or clotting occur, non-fluidized configurations remain lying on the grate, and the like. This results in uneven processing of the substance, in nonexploitation of a part of the energy of the fluidizing and working media, and also in local overheating which may cause the contents of the apparatus to self-ignite as soon as the flash point has been attained, and the like.
As far as plant design is concerned the main disadvantages lie in the use of a horizontal rate.
Devices with cylindrical casings have also been found notto be suitable because of a high escape rate of some materials. In addition to the disadvantages mentioned a further substantial disadvantage of known plants is the fact that there is no other possibility to overcome the cohesion forces of the processed material in them than to use an increased pressure of the expanding medium which has the above mentioned disadvantages.
The disadvantages described may be avoided by a method and an apparatus according to the invention.
The invention provides a method of processing solid, solute, dispersed, sludge-like or semiplastic material, wherein the particles of the material to be processed are set in free motion by a combined action of at least one stream of gaseous and/or liquid medium and mechanical agitation, while the whole system of the freely moving particles is caused to perform a rotary motion about a horizontal or oblique axis.
At least two media of mutually different physical and/or chemical properties may be used for the processing. The medium or media may impinge on the material at a velocity which is equal to or lower than the incipient fluidizing velocity. The agitator may rotate at 10 to 200 rpm and the whole system of particles of the material being processed may be moved in the direction of the processing sequence.
The invention also provides an apparatus for carrying out the method, comprising a casing subdivided by a curved fluidization partition into an upper zone, which includes a rotary agitator, and a lower zone for supplying at least one stream of gaseous and/or liquid medium through the partition, the upper zone being provided with meansforsupplying the material to be processed and for discharging the finished product and the medium.
The advantage of the method and the apparatus according to the invention lies mainly in the fact that the cohesion forces bonding the particles of some materials are overcome by the agitation and in this way the stream of the expanding medium produces, at a suitable velocity, a homogeneous expanded layer with a sufficient free motion of the particles of the processed substance. Also the geometry of the partition (grate) contributes to this aim since it has an agitating effect itself.In this way it is possible to extend the range of materials, workable by the technology of expanded layer, which is, in a number of cases, the only suitable means for attaining the resulting properties of the product, as is the case, e.g., with the dehydration of liquid vaccines on solid particles of a substance of the same kind, or on an auxiliary carrier and similar materials, where a high biological activity of the final product is required, and/or with the processing of substances of semiplastic consistency with which it is not possible to attain a fluidized layer with the use of the methods and plants, hitherto employed, at all.
Another advantage of a method and an apparatus according to this invention are increased process economy and increased yield.
Examples of a possible practical use of a method according to the invention are given generally and also in the following description of processing of some specific materials. One embodiment of an apparatus according to the invention is diagrammatically illustrated in the accompanying drawings, in which:
Figure 1 is a front view of the apparatus, and
Figure 2 is its side view.
In principle, according to the invention gas or liquid, or a mixture of gas and liquid, are forced into a layer of the material being processed through holes in a partition 2, the gas or the liquid, and/or their mixture being fed into the lower portion of a casing 1. At the same time, an agitator 4 agitates the layer of the material being processed with an intensity which is sufficient to cause the particles of the material being processed to be separated from each other by the combined action of the agitator and the expansion of the layer by gas, liquid, or their mixture, to such an extent that each of the particles performs free motion in the particle system which is moving from the inlet of the material to be processed into the apparatus to its outlet from the apparatus by the action of the blades.If it is required for the perfect separation of the particles, the expanded system of the material being processed may be set into a rotary motion about a horizontal axis by means of a suitable selection of the speed of rotation and the agitator design.
The velocity of flow of the expanding medium should be chosen according to the character of the material to be processed; in order to prevent an unacceptable fly-loss of material the velocity may be even lower than the corresponding incipient fluidizing velocity.
If the substance to be processed is a liquid it may be metered in various ways, e.g. in the form of a mist entering from the upper part of the casing 1, from the side walls, or directly into the layer of solid particles. This is used for the working of solutions and suspensions supported by the solid phase of the same substance or an auxiliary carrier.
If required by any particular technical circumstances, the initial material may be procesed sequentially with media of different physical or chemical properties; this us used e.g., for treating a solid -material A with a liquid material B. For this purpose an apparatus is used whose lower portion is fitted with chambers 7, 8,9 serving for separately supplying the expanding and working media.
Via the chamber 7 air at a higher temperature (e.g.
1 500C) enters and preheats the solid particles of material A on to which melted material B is fed, e.g.
through an inlet branch 10 in the upper portion of the apparatus.
The chamber 8 serves for supplying air at 80"C, which is the optimum processing temperature.
Before being discharged the treated product should be cooled down by air at 20"C entering through the chamber 9.
After they have passed through the layer of the processed material, the expanding and working media and also the reaction products together with light particles of the material, are carried away through branches 14 out of the apparatus, and then, outside the apparatus they are freed from the said particles in cyclone separators and/orfilters. Before being discharged from the apparatus the expanded layer may cease to be fluidized.
Practical examples of carrying out a method according to the invention will now be described.
Conversion ofpoultry wastes into protein fodder
In giant fattening stations with a capacity of 250 000 to 500 000 animals wastes are produced in an amount of several tens of tons a day. Due to the ineffectively working digestive tract of poultry these wastes represent high quality components of protein fodder suitable particularly for cattle. The raw material in the form of a suspension containing 85 - 92% of water is pumped into the apparatus in the working space of which the expanded layer of the product having a moisture content of 30 - 40% rotates. The entry temperature of the air is 400 - 600"C and its linear velocity is about 1 m/s at which fluidization takes place. The agitator rotates at a frequency of 80 -120 rpm. The resulting products are brown particles of elongate shape, comparable to cut tobacco, deprived of mercaptanic and other components, deodorized, having a water content lower than 10%, and a calorific value equal to that of grain.
Dehydration of chlorinated rubber
The raw material is a white, very light, coarse grained matter, which when squeezed in hand is little cohesive, and whose water content is higher than 75%. It tends to form cannels and it is a material for which the difference between the incipient fluidizing velocity and the entrainment velocity is very small. The air temperature is 150"C under the grate, the linear velocity of the air is below 0.2 m/s and the frequency of rotation is 30 rpm. On leaving the apparatus the temperature of the processed product is 65 - 70"C, and its moisture content below 0.3%.
Dehydration ofbentonites These products pertain to the group of hydrated aluminium silicates. The processed samples were non-homogeneous and contained particles the size of which varied from 0.1 to 20 mm. The material was enriched with the necessary quantity of ions Na+.
The samples to be processed were untreated, mechanically sieved, and made into a form of paste and suspension. The entry moisture content of the product was 40 - 80%. The temperature of the product was not allowed to exceed 90"C. They were dehydrated with air at 200do, the temperature of the product in the apparatus was 65"C at most, the linear velocity of the air about 1 m/s, the frequency of rotation 60 rpm. The entry moisture contents were below 10% within the requirements of the processing.
Dehydration of vaccines based on the solid matter of vaccines oran artificial carrier
The vaccines were process successfully under the following working conditions:
The temperature of gas under the grate was 60 70"C, the linear velocity of gas was 0.2 - 0.28 m/s, the temperature of the product in the final phases was below 38"C, the time of processing 25 - 40 minutes, the frequency of rotation 120 rpm.
The apparatus according to the invention, shown in Figure 1 and Figure 2, comprises a casing 1 widening upwards. In the narrow portion the casing 1 is divided by means of a curved perforated partition (or other type of curved grate) 2 into an upper working space and a lower portion serving for the supply of expanding and working media. The lower portion may be divided into separate chambers 7,8,9 arranged along the whole length of the apparatus and serving for independent supplies of media of different properties. Immediately above partition 2 is arranged the agitating system, including a rotary shaft 3 and a row of blades 4 fixed to it.
The shaft 3 passes through the end walls of the casing 1 and is driven by a drive having adjustable speed of rotation. In the cover of the casing 1 branches 5, 10 for feeding the material to be processed are mounted, the side walls of the upper portion of the casing 1 hold branches 14for carrying away the expanding and working media which have passed through the processed material and/or the products of reaction. A branch 6 for discharging the finished product is mounted on the rear end wall of the casing, the lower portion of the casing, and/or its individual chambers 7,8,9 are provided with branches 11, 12, 13 serving for supplying the expanding and working media. The branches 14 may be connected to cyclone separators or filters.The casing 1 must be widened in its upper portion to such an extent that the surface of its cover is three to five times larger than the surface of the partition 2.
The agitating system may be composed of several shafts with blades arranged next to each other in the direction of the longitudinal axis of the casing 1. The blades 4 may be provided with elastic scrapers.
The partition 2 may be in the form of a partcylindrical shell. The part of the partition 2 on the outlet side for the finished product may be without any perforation, whereby a settling zone is provided.
The branches 5, 10 forfeeding the material to be processed may be located also on the side walls of the casing 1, and/or they may have intakes in the partition 2 (not shown).
During the process the material to be processed is brought in through the branch 5, or, if several materials are to be processed through branch 10 or through other inlet branches in the side wall of the casing 1, and/or in the partition 2, while, at the same time, the expanding and working media are forced into the layer of solid particles being formed from the lower portion of the casing 1. Owing to the action of the agitator 4 the layer of the solid material becomes homogeneous and/or separated. The agitator causes the whole expanded system of freely moving particles to advance to the outlet of the apparatus. The speed of advancement should be selected according to the desired time for the given type of processing and material.
In the course of their advancing through the apparatus the freely moving particles may be exposed to different kinds of processing in different sections defined by the width of the chambers 7, 8, 9.
The stream of the expanding and working media passing through the layer of the material being processed advances into the widened portion of the casing 1 where it loses its speed and for this reason most of the entrained parts of the processed material fall back into the layer. Then it leaves, together with the finest material entrained therein, through the branches 14 from the apparatus into the cyclone separators and/or filters.
The method and the apparatus according to this invention are applicable e.g. in the pharmaceutical and foodstuff industries, in fertilizer manufacture, in cement making, and in the plastic industry.
Claims (20)
1. A method of processing solid, solute, dispersed, sludge-like or semiplastic material, wherein the particles of the material to be processed are set in free motion of by combined action of at least one stream of gaseous and/or liquid medium and mechanical agitation, while the whole system of freely moving particles is caused to perform a rotary motion about a horizontal or oblique axis.
2. A method according to Claim 1 wherein at least two media are used for the processing, the media being of mutually different physical and/or chemical properties.
3. A method according to Claim 1 or 2 wherein the medium or at least one of the media impinges on the material at a velocity which is equal to or lower than the incipientfluidizing velocity.
4. A method according to any one of Claims 1 to 3 wherein an agitator rotating at 10 to 200 revolutions per minute is used for agitation.
5. A method according to any one of Claims 1 to 4 wherein the whole system of particles of the material being processed is moved in the direction of the processing sequence.
6. A method of processing solid, solute, dispersed, sludge-like or semiplastic material substantially as herein described with reference to the accompanying drawing.
7. An apparatus for carrying out the method according to Claim 1 comprising a casing subdivided by a curved fluidization partition into an upper zone, which includes a rotary agitator, and a lower zone for supplying at least one stream of gaseous and/or liquid medium through the partition, the upper zone being provided with means for supplying the material to be processed and for discharging the finished product and the medium.
8. An apparatus according to Claim 7 wherein the casing has vertical or upwardly diverging walls.
9. An apparatus according to Claim 7 or 8 wherein the partition is a perforated partition, a grate, a grid, a lattice or a sieve.
10. An apparatus according to any one of Claims 7 to 9 wherein the partition is in the shape of a part-cylindrical shell.
11. An apparatus according to Claim 10 wherein the partition has a horizontal or oblique axis.
12. An apparatus according to any one of Claims 7 to 11 wherein the partition has a portion through which the medium cannot pass.
13. An apparatus according to any one of Claims 7 to 12 wherein the lower zone is subdivided into chambers through which the medium is fed to and through the partition.
14. An apparatus according to any one of Claims 7 to 13 wherein the agitator comprises one to five horizontal or oblique shafts, each provided with blades.
15. An apparatus according to Claim 14 wherein the blades reach to close proximity of the partition.
16. An apparatus according to any one of Claims 7 to 15 wherein the agitator rotates at a speed of 10 to 200 revolutions per minute.
17. An apparatus according to any one of Claims 7 to 16 wherein the means for supplying the material and the means for discharging the medium are tubular elements situated on a side wail of the upper zone.
18. An apparatus for carrying outthe method according to Claim 1, constructed, arranged, and adapted to operate, substantially as herein described with reference to, and as shown in, the accompanying drawing.
19. Material processed by a method according to any one of Claims 1 to 6.
20. Material processed in an apparatus accord ingto any one of Claims 7 to 18.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7927140A GB2053714B (en) | 1979-06-15 | 1979-08-03 | Stabilizing fluidized bed |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7920911 | 1979-06-15 | ||
| GB7927140A GB2053714B (en) | 1979-06-15 | 1979-08-03 | Stabilizing fluidized bed |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2053714A true GB2053714A (en) | 1981-02-11 |
| GB2053714B GB2053714B (en) | 1983-10-26 |
Family
ID=26271855
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7927140A Expired GB2053714B (en) | 1979-06-15 | 1979-08-03 | Stabilizing fluidized bed |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2053714B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0063486A1 (en) * | 1981-04-16 | 1982-10-27 | Din Engineering Limited | Heat treatment of a particulate commodity |
| GB2249375B (en) * | 1990-10-30 | 1994-09-07 | Fukutaro Kataoka | Fluidized crusher/drier for use in a fluidized crusher/drying system |
-
1979
- 1979-08-03 GB GB7927140A patent/GB2053714B/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0063486A1 (en) * | 1981-04-16 | 1982-10-27 | Din Engineering Limited | Heat treatment of a particulate commodity |
| GB2249375B (en) * | 1990-10-30 | 1994-09-07 | Fukutaro Kataoka | Fluidized crusher/drier for use in a fluidized crusher/drying system |
| AU656334B2 (en) * | 1990-10-30 | 1995-02-02 | Fukutaro Kataoka | Fluidized crusher/drier for use in a fluidized crusher/drier system |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2053714B (en) | 1983-10-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |