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GB2465361A - Material drying or processing method and apparatus comprising a venturi - Google Patents

Material drying or processing method and apparatus comprising a venturi Download PDF

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Publication number
GB2465361A
GB2465361A GB0820780A GB0820780A GB2465361A GB 2465361 A GB2465361 A GB 2465361A GB 0820780 A GB0820780 A GB 0820780A GB 0820780 A GB0820780 A GB 0820780A GB 2465361 A GB2465361 A GB 2465361A
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GB
United Kingdom
Prior art keywords
enclosure
duct
process gas
tube
higher pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB0820780A
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GB0820780D0 (en
Inventor
Thomas John Stubbing
Terence Patrick Dunne
Graham Bird
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
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Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to GB0820780A priority Critical patent/GB2465361A/en
Publication of GB0820780D0 publication Critical patent/GB0820780D0/en
Priority to GB0912369.6A priority patent/GB2465246B/en
Priority to EP09752449A priority patent/EP2344824A2/en
Priority to MYPI2011002126A priority patent/MY159158A/en
Priority to PCT/GB2009/002630 priority patent/WO2010055281A2/en
Priority to CN200980132659.XA priority patent/CN102132120B/en
Publication of GB2465361A publication Critical patent/GB2465361A/en
Priority to HK10108526.4A priority patent/HK1142122B/en
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • F26B17/106—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, e.g. its axis, being substantially straight and horizontal, e.g. pneumatic drum dryers; the drying enclosure consisting of multiple substantially straight and horizontal stretches
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B11/00—Machines or apparatus for drying solid materials or objects with movement which is non-progressive
    • F26B11/02—Machines or apparatus for drying solid materials or objects with movement which is non-progressive in moving drums or other mainly-closed receptacles
    • F26B11/028—Arrangements for the supply or exhaust of gaseous drying medium for direct heat transfer, e.g. perforated tubes, annular passages, burner arrangements, dust separation, combined direct and indirect heating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B11/00—Machines or apparatus for drying solid materials or objects with movement which is non-progressive
    • F26B11/02—Machines or apparatus for drying solid materials or objects with movement which is non-progressive in moving drums or other mainly-closed receptacles
    • F26B11/024—Arrangements for gas-sealing the drum
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F26B21/001—Drying-air generating units, e.g. movable, independent of drying enclosure
    • F26B21/20—
    • F26B21/30—
    • F26B21/37—
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B23/00—Heating arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B2200/00—Drying processes and machines for solid materials characterised by the specific requirements of the drying good
    • F26B2200/18—Sludges, e.g. sewage, waste, industrial processes, cooling towers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B2200/00—Drying processes and machines for solid materials characterised by the specific requirements of the drying good
    • F26B2200/24—Wood particles, e.g. shavings, cuttings, saw dust

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Drying Of Solid Materials (AREA)

Abstract

A method of drying or processing materials in a drying or processing cylinder, or other drying or processing apparatus, located within or forming at least part of an enclosure 1. At least a portion of a process gas entering a higher pressure region 4 of the enclosure is routed by a fan 2 through a venturi and around, over, across, through or adjacent the open end of a material input tube 7 at increased speed and reduced pressure. This provides suction at the opening of the material input tube into the higher pressure region of the enclosure which is sufficient to prevent, or substantially prevent, the pressure at the higher pressure region of the enclosure causing the process gas atmosphere in the enclosure to be blown through the tube and out of the enclosure into the external air or other gas atmosphere outside the apparatus. Preferably, the venturi is defined by an annulus formed by the material input tube located coaxially within a process gas duct 6, 8. The speed of the fan may be controlled. In a further aspect, an associated apparatus is disclosed.

Description

Methods and apparatus for improving continuous drying or processing of materials The invention relates to methods and apparatus for improving continuous drying or processing of materials. The invention is primarily, but not exclusively, applicable to the drying or processing of particulate materials, for example sewage sludge and wood chips.
It is known continuously to dry moist materials in superheated steam using the method and apparatus described in Patent GB 2281383 and corresponding international patents and patent applications, and continuously to dry or process organic materials in at least one of superheated steam, a hot inert gas, hot air and hot process gases using the method and apparatus described in Patent Application PCTIGBO2/O 1497 and corresponding international patent applications, whereby material inlet and outlet ducts extending downwardly from a drying or processing enclosure are provided which are sealed against ingress of air and egress of superheated steam, hot inert gas, hot air and/or hot process gases through the open bases of said ducts by means of temperature and density differential stratification layer seals formed within and across said ducts which inhibit the escape of said superheated steam, hot inert gas, hot air and/or hot process gases from said enclosure and the entry of external air or other gas into the enclosure while permitting the conveyance of materials along said ducts and through said stratification layer seals.
For brevity and for the avoidance of doubt, all of said superheated steam, hot inert gas, hot air and/or hot process gases, including the superheated steam in which moist materials are dried, are hereinafter referred to as process gas.
Those methods and apparatus have the disadvantage that, when drying or processing materials in a rotating cylinder located within an enclosure, a costly louvred cylinder with openings around its circumference permitting the required weight of process gas employed as the drying or processing medium to pass across the axis of the louvred cylinder by entering and leaving the cylinder through said openings needs to be provided to prevent a pressure differential being created along the length of the cylinder because, if a required weight of process gas is made to pass from one end of a cylinder without such openings around its circumference to its other end, a pressure differential is created along the length of the cylinder resulting in the process gas atmosphere within the enclosure being blown out of the enclosure through the stratification layer seal across, and through the open base of, the duct extending downwardly from the enclosure below the higher pressure end of the cylinder, and in said process gas atmosphere being replaced by external air or other gas drawn into the enclosure through the open base of, and through the stratification layer seal across, the duct below the lower pressure end of the cylinder, said methods and apparatus also having the disadvantage that, because the temperature of the weight of process gas entering the entire length of a louvred cylinder through said openings is limited by the need to avoid heating the dried or processed material about to leave the cylinder and exit the enclosure through the outlet duct to above the required output temperature of said material, to achieve a required output rate with a louvred cylinder a greater weight of process gas at a limited lower temperature needs to pass across the axis of a louvred cylinder to achieve a required dried or processed material output rate, resulting in higher fan power costs being incuned and in the need to provide a larger and more costly fan and a longer louvred cylinder, than if the lesser weight of process gas required at a higher temperature could be made to pass along a shorter and less costly cylinder without openings around its circumference from the material input end of said cylinder to the dried or processed material output end of said cylinder and be cooled by said material input as said material and said process gas pass along said cylinder, whereby heating the dried or processed material about to leave the cylinder and exit the enclosure through the outlet duct to above the required output temperature of said dried or processed material would be avoided.
It is also known continuously to dry moist materials in process gas using a method and an apparatus described in Patent GB 2209383 and corresponding international patents, said method including the provision of substantially gas-tight material inlet sealing means and a moveable conveyor to transport material to be dried into an enclosure in substantially gas-tight manner.
This method and apparatus has the disadvantages that costly material inlet sealing means comprising, for example, substantially gastight pocket valves or equivalent mechanical sealing means need to be provided and that, when continuously drying materials in an apparatus according to said Patent, or when processing materials in a similar apparatus, because the sealing ability of such mechanical sealing means diminishes due to abrasion by the materials being conveyed through them, the process gas pressure at the higher pressure end of said apparatus is limited to that above which process gas would be blown from the higher pressure end of said apparatus through material being transported into the enclosure and through abraded mechanical sealing means into the external air or other gas atmosphere outside said apparatus unless said costly material inlet sealing means are frequently replaced.
The present invention sets out to eliminate the disadvantages of those known methods and apparatus for continuous drying or processing, either by preventing the pressure differential along the length of a drying or processing cylinder causing process gas to be blown out of an enclosure through the open base of a material inlet duct extending downwardly from the enclosure below the higher pressure end of the cylinder and the process gas atmosphere in the enclosure being replaced by external air or other gas drawn into the enclosure through the open base of the material outlet duct extending downwardly from the enclosure below the lower pressure end of the cylinder, or, either by avoiding the need to provide such costly material inlet sealing means and using the material being transported by gravity or by a moveable conveyor into the apparatus as equivalent material inlet sealing means, or by avoiding frequent replacement of abraded mechanical material inlet sealing means when such sealing means are provided, preventing a higher process gas pressure than the limited pressure at the higher pressure end of an apparatus for drying or processing materials causing process gas to be blown from the higher pressure end of the apparatus through said material inlet sealing means into the external air or other gas atmosphere outside the apparatus, and by enabling a lesser weight of process gas at a higher temperature to pass either along a shorter and less costly cylinder or along a shorter and less costly apparatus while avoiding heating the dried or processed material about to leave the cylinder or apparatus to above the required output temperature of the material.
By way of explanation, the methods according to the invention include employing Bernoulli's principle, whereby, in a carburetor, air is passed through a venturi duct to increase its speed and therefore decrease its pressure, the low pressure air being routed over a tube leading from a supply of fuel so that the low pressure air sucks fuel into the airflow, by routing at least a portion of a process gas recirculation through a venturi duct passing over or through the opening of a tube through which material is being conveyed from a supply of material into the higher pressure end of any apparatus according to the invention in order to create suction at the opening of said tube into the higher pressure end of the apparatus, thereby preventing the process gas atmosphere in the apparatus being blown out of the apparatus into the external air or other gas outside the apparatus and being replaced by external air or other gas drawn into the apparatus.
According to the present invention there is provided a method of preventing the pressure differential along the length of a rotating drying or processing cylinder causing the process gas atmosphere to be blown out of an enclosure, within which said cylinder is located, whereby the cylinder may itself form part of the enclosure, through the temperature and density differential stratification layer seal across, and through the open base of, the material inlet duct extending downwardly from the enclosure below the higher pressure end of said cylinder, and the process gas atmosphere in the enclosure being replaced by external air or other gas drawn into the enclosure through the open base of, and through the temperature and density differential stratification layer seal across, the material outlet duct extending downwardly from the enclosure below the lower pressure end of said cylinder, and of avoiding heating the dried or processed material about to leave the cylinder and exit the enclosure through the outlet duct to above the required output temperature of said material, comprising routing by fan means at least a portion of the process gas entering the higher pressure end of a drying or processing cylinder through a preferably cylindrical duct opening into said higher pressure end of said cylinder, and routing material to be dried or processed, preferably by conveyor or by gravity means, through a material input tube having a smaller diameter than that of said preferably cylindrical duct entering the higher pressure end of said cylinder, said material input tube passing co-axially through a portion of the open end of said preferably cylindrical duct and opening into said higher pressure end of said cylinder through the opening of said preferably cylindrical duct, whereby, as said process gas is blown through the annulus, said annulus then acting as a venturi, between said material input tube and said preferably cylindrical duct and over the open end of said material input tube, the speed of said process gas is increased, and its pressure at the opening of said material input tube into said higher pressure end of said cylinder, and within said material input tube, is decreased by the suction created at the opening of said material input tube into the higher pressure end of said cylinder to equal the pressure at the lower, atmospheric pressure end of said cylinder, thereby preventing said pressure differential causing the process gas atmosphere in the enclosure to be blown out of the higher pressure end of said cylinder through said material input tube and out of the enclosure through the temperature and density differential stratification layer seal across, and through the open base of, the material inlet duct extending downwardly from the enclosure below the higher pressure end of said cylinder, and the process gas atmosphere in the enclosure being replaced by external air or other gas drawn into the enclosure through the open base of, and through the temperature and density differential stratification layer seal across, the material outlet duct extending downwardly from the enclosure below the lower pressure end of said cylinder, while the process gas entering said higher pressure end of said cylinder is cooled during passage of said process gas from the higher pressure end to the lower, atmospheric pressure end of said cylinder by heat transfer from said process gas into the material being heated and dried or processed during passage of said material along the length of said cylinder, thereby avoiding heating the dried or processed material about to leave the cylinder and exit the enclosure through the open base of the outlet duct to above the required output temperature of said material.
The method may include an alternative step comprising routing by fan means at least said portion of the process gas entering the higher pressure end of a drying or processing cylinder through an inwardly tapering portion of said preferably cylindrical duct opening into said higher pressure end of said cylinder, and routing material to be dried or processed by gravity means through a material input tube having a larger diameter than that of said duct entering the higher pressure end of said cylinder, a portion of said material input tube forming an annulus passing co-axially around the inwardly tapering portion of said duct, said annulus opening into said higher pressure end of said cylinder around the opening of said duct, whereby, as said process gas is blown through the opening of said inwardly tapering portion of said duct, said said inwardly tapering portion of said duct then acting as a venturi, into the higher pressure end of said cylinder, the speed of said process gas is increased, and its pressure at the opening of the annulus of said material input tube into said higher pressure end of said cylinder, and within said annulus and said material input tube, is decreased by the suction created at the opening of said annulus into the higher pressure end of said cylinder to equal the pressure at the lower, atmospheric pressure end of said cylinder.
In an alternative method according to the invention, there is provided a method of preventing the pressure at the higher pressure end of a drying or processing apparatus from blowing process gas from the higher pressure end of said apparatus either through costly pocket valve or equivalent mechanical sealing means located within a material input tube when the sealing ability of said sealing means has been diminished by abrasion, or through material acting as equivalent sealing means being conveyed along or falling through said tube, into the external air or other gas atmosphere outside the apparatus, comprising either routing by fan means at least a portion of a process gas entering the higher pressure end of said apparatus through a preferably cylindrical duct opening into said higher pressure end of said apparatus and routing material to be dried or processed, preferably by conveyor or by gravity means, through said tube, said tube opening into said higher pressure end of said apparatus having a smaller diameter than that of said duct and opening into the higher pressure end of said apparatus through the opening of said duct into said higher pressure end of said apparatus, said tube passing preferably co-axially through and along a length of said duct, or routing by fan means at least a portion of the process gas entering the higher pressure end of said apparatus through a preferably cylindrical duct tapering inwardly towards and opening into said higher pressure end of said apparatus, and routing material to be dried or processed, preferably by conveyor or by gravity means, through said tube, said tube having a larger diameter than that of said duct and opening into the higher pressure end of said apparatus around the opening of said duct into said higher pressure end of said apparatus, said duct passing preferably co-axially within and along a length of said tube, whereby, as previously described in principle by reference to drying or processing in a rotating cylinder, suction is created at the opening of said material input tube into the higher pressure end of said apparatus and said suction prevents the pressure at the higher pressure end of the drying or processing apparatus from blowing process gas from the higher pressure end of said apparatus through said material input tube into the external air or other gas atmosphere outside said apparatus.
The fan means may take a range of forms. Typically it will comprise a rotatable fan blade or series of blades and a motor operable to drive the blade(s) to increase the speed of process gas flow. However, alternative forms of blower or compressor could be used.
In the methods herein described in which a material input tube has a smaller diameter than that of a preferably cylindrical duct through which at least a portion of process gas is routed through an annulus between a portion of said material input tube and said duct, both said smaller diameter material input tube and said preferably cylindrical duct may be replaced by ducts having rectangular cross sections, whereby a portion of the rectangular material input duct passes preferably coaxially through a portion of a rectangular duct having larger cross-sectional dimensions than those of the material input duct and said portion of process gas is routed through the space within the rectangular duct around the portion of the rectangular material input duct and over the open end of the material input duct, enabling sheet products such as paper or textiles or solid products such as bricks to be conveyed through the material input duct and dried or processed according to the invention.
In the methods herein described, the speed at which said fan means route at least a portion of the process gas through said preferably cylindrical duct, or through said larger diameter duct, either through the annulus between said tube and said preferably cylindrical duct, or through the inwardly tapering portion of said preferably cylindrical duct, or through the space within the larger diameter rectangular duct around the portion of said smaller diameter rectangular material or product input duct, and over or through the open end of said material input tube or of said material or product input duct, may be controlled by inverter or damper means, said inverter or damper means being controlled preferably by thermocouple means located preferably within or on the surface of said material input tube or of said smaller diameter rectangular material or product input duct, whereby, if hot process gas tends to be blown through said material input tube or through said smaller diameter rectangular material or product input duct from said higher pressure end of said cylinder into the enclosure said speed is increased, or if cooler process gas tends to be drawn from the enclosure through said material input tube or through said smaller diameter rectangular material or product input duct into said higher pressure end of said cylinder said speed is decreased, or if the pressure at the higher pressure end of a drying or processing apparatus tends to blow hot process gas from the higher pressure end of said apparatus through said material input tube or duct into the external air or other gas atmosphere outside said apparatus said speed is increased, or if cool external air or other gas tends to be drawn through said material input tube into said higher pressure end of said apparatus said speed is decreased, thereby ensuring that the suction at the opening of said material input tube or of said smaller diameter rectangular material or product input duct into the higher pressure end of said cylinder and within said material input tube or within said smaller diameter rectangular material or product input duct, remains equal to that at the lower, atmospheric pressure end of said cylinder or of said apparatus.
In an alternative method for controlling the speed at which the fan means route at least a portion of the process gas over or through the open end of the material input tube or of the material or product input duct, the inverter or damper means are controlled by pressure detection means located within said material input tube or material or product input duct, whereby, if the pressure within said material input tube or within said material or product input duct tends to rise above atmospheric pressure the speed is increased, or if the pressure tends to fall below atmospheric pressure the speed is decreased.
In a further alternative method for controlling the speed at which the fan means route at least a portion of the process gas over or through the open end of the material input tube or of the material or product input duct, the inverter or damper means are controlled by gas movement detection means located within said material input tube or material or product input duct, whereby, if process gas tends to move along said tube or said duct from the open end of said tube or of said duct the speed is increased, or if external air or other gas tends to move along said tube or along said duct towards the open end of said tube or duct the speed is decreased.
The methods herein described can also be employed when drying or processing materials or products, both hereinafter referred to as materials, in, for example, spray, ring or fluidised bed dryers or processors either to prevent the pressure differential created by passage of process gas along the length of such dryers or processors causing process gas atmospheres to be blown out of the enclosures within which such dryers or processors are located and external air or other gas to be drawn into such enclosures, or to prevent the pressure at the higher pressure end of a drying or processing apparatus, of which such dryers or processors form part, from blowing process gas from the higher pressure end of such apparatus into the external air or other gas atmosphere outside the apparatus, while also preventing external air or other gas being drawn into said higher pressure end of such drying or processing apparatus.
In general, according to the invention there is provided an apparatus for drying or processing materials comprising an enclosure, fan means for routing at least a portion of a process gas entering a higher pressure region of the enclosure through a venturi means located and arranged such that, in use, the portion of process gas passes over an open end of an inlet tube at increased speed and reduced pressure.
The following is a more detailed description of embodiments of the invention, by way of example, reference being made to the accompanying drawings in which: FIG. 1 is a diagrammatic side view section through an apparatus for continuous drying or processing in a rotating cylinder located in an enclosure according to the invention.
FIG. 2 is a diagrammatic side view section through part of an alternative apparatus for continuous drying or processing in a rotating cylinder forming part of an enclosure according to the invention.
FIG. 3 is a diagrammatic side view section through part of a further alternative apparatus for continuous drying or processing according to the invention in an enclosure comprising, for example, a rotating cylinder or a spray, ring or fluidised bed dryer or processor.
Referring to FIG. 1, there is shown diagrammatically a side view sectional representation of an apparatus for preventing the pressure differential along the length of an internally flighted drying or processing cylinder located within an enclosure causing process gas to be blown out of the enclosure through the open base of a material inlet duct extending downwardly from the enclosure below the higher pressure end of said cylinder, and the process gas atmosphere in the enclosure being replaced by external air or other gas drawn into the enclosure through the open base of a material outlet duct extending downwardly from the enclosure below the lower pressure end of said cylinder, and for enabling a lower weight of process gas at a higher temperature to pass along said cylinder while avoiding heating the dried or processed material about to leave the cylinder and exit the enclosure through said outlet duct to above the required output temperature of said material.
The apparatus comprises a thermally insulated enclosure 1, a fan 2, an internally flighted rotating drying or processing cylinder 3, hereinafter refelTed to as said cylinder 3, having a higher pressure end 4 and a lower, atmospheric pressure end 5, a preferably cylindrical duct 6 opening through a length 8 of said duct 6 into said higher pressure end 4 of said cylinder 3, a material input tube 7 having a smaller diameter than that of said duct 6, said tube 7 passing in gastight manner into said duct 6, said tube 7 then running preferably co-axially through said length 8 of said duct 6 and opening into said higher pressure end 4 of said cylinder 3 through the opening of said length 8 into said higher pressure end 4 of said cylinder 3, a material inlet duct 9 extending downwardly from the enclosure 1 below the higher pressure end 4 of said cylinder 3 to an open base 10 of said inlet duct 9, a material outlet duct 11 extending downwardly from the enclosure 1 below the lower, atmospheric pressure end 5 of said cylinder 3 to an open base 12 of said outlet duct 11, a supply of material 13 to be dried or processed, a recirculation fan 14, an indirect heater 15, and a vent 16, whereby, in use, a process gas is recirculated by said recirculation fan 14 through said indirect heater 15, thereby heating said process gas, and through said cylinder 3, as indicated by arrows 20, while said fan 2 routes at least a portion of said process gas, as indicated by arrow 21, into said duct 6, and material 13 to be dried or processed is routed, as indicated by arrow 22, upwards through said inlet duct 9 by a not shown conveyor into said input tube 7 and, by a not shown conveyor or by gravity, through said material input tube 7 into the higher pressure end 4 of said cylinder 3, and, as said portion of said process gas being routed into said duct 6 is blown by said fan 2 along the length 8 of said duct 6 through the annulus between said tube 7 and said length 8 of said duct 6, said annulus acting as a venturi, and over the open end of said tube 7, and past the open end of said length 8 of said duct 6, into the higher pressure end 4 of said cylinder 3, as indicated by arrows 23 and 24, the speed of said portion of said process gas is increased, and the pressure of said portion of the process gas at the openings of both said tube 7 and said length 8 of said preferably cylindrical duct 6 into said higher pressure end 4 of said cylinder 3, and within said tube 7, is decreased by the suction created at the opening of said tube 7 into the higher pressure end 4 of said cylinder 3 to equal the pressure of said process gas at the lower, atmospheric pressure end 5 of said cylinder 3, thereby preventing said pressure differential causing process gas to be blown out of the higher pressure end 4 of said cylinder 3 through said material input tube 7 and out of the enclosure 1 through the open base 10 of said material inlet duct 9, and the process gas atmosphere in the enclosure 1 being replaced by external air or other gas drawn into the enclosure 1 through the open base 12 of said material outlet duct 11, while, as indicated by arrow 25, the portion of said process gas indicated by arrow 21 re-joins the process gas being recirculated by said recirculation fan 14 as indicated by arrows 20, said material 13 being routed through said tube 7 into the higher pressure end 4 of said cylinder 3 is lifted by and cascades from the not shown internal flights within said cylinder 3 through, and is heated and dried or processed by heat transfer from, said process gas, and is progressively blown along said cylinder 3 by the process gas passing along said cylinder 3 towards the lower, atmospheric pressure end 5 of said cylinder 3, and said process gas is cooled by said heat transfer from said process gas during the passage of said process gas along said cylinder 3 from said higher pressure end 4 to said lower, atmospheric pressure end 5 of said cylinder 3, thereby avoiding heating the dried or processed material about to leave the cylinder 3 to above the required output temperature of said material 13, and dried or processed material emerges from said lower, atmospheric pressure end 5 of said cylinder 3 and falls, or is conveyed by a not shown conveyor, out of said enclosure 1 through the open base 12 of said outlet duct 11, as indicated by arrow 26, into the external air or other gas atmosphere outside said enclosure 1, and, as described in Patent GB 2281383 and Patent Application PCT/GBO2/O 1497 and corresponding international patents and patent applications, additonal process gas generated within said cylinder 3 from said material 13 during the drying or processing of said material 13 is vented through said vent 16, as indicated by arrow 27, preferably into a not shown process gas condenser or combustor, at the level, indicated by dotted lines 28, of the density and temperature differential stratification layer seals across said inlet duct 9 and said outlet duct 11 between the process gas atmosphere within said enclosure 1 and the external air or other gas atmosphere outside said enclosure 1.
Referring to HG. 2, there is shown diagrammatically a side view section through the material input end of an apparatus for continuous drying or processing according to the invention illustrating the alternative step of routing material to be dried or processed into the higher pressure end of a rotating drying or processing cylinder through a material input tube having a larger diameter than that of the duct through which at least a portion of process gas is blown into the higher pressure end of said cylinder.
Said input end of the apparatus comprises the input end of a thermally insulated enclosure 1, a fan 2, the higher pressure end 4 of a thermally insulated internally flighted rotating drying or processing cylinder 3, hereinafter referred to as said cylinder 3, whereby said cylinder 3 forms part of said enclosure 1, a preferably cylindrical duct 6 forming part of said enclosure 1, hereinafter referred to as said duct 6, a material input tube 7 having a larger diameter than said duct 6 and opening through a length 8 of said tube 7 into the higher pressure end 4 of said cylinder 3, said duct 6 passing in gastight manner into said tube 7, said duct 6 then running in inwardly tapering manner preferably co-axially through said length 8 of said tube 7 and opening into said higher pressure end 4 of said cylinder 3 in line with the opening of said length 8 of said tube 7 into said higher pressure end 4 of said cylinder 3, whereby the length of said duct 6 outside said tube 7 is preferably thermally insulated, a thermally insulated material inlet duct 9 extending downwardly from the enclosure 1 below the higher pressure end 4 of said cylinder 3 to an open base 10 of said inlet duct 9, a supply of material 13 to be dried or processed, an annular seal 17 between said part of the enclosure 1 and said higher pressure end 4 of said rotating drying or processing cylinder 3, and part of a recirculation duct 18, whereby, in use, said fan 2 routes a portion of the process gas recirculation, indicated by arrows 20 and already described by reference to FIG. 1, into said duct 6 as indicated by arrow 21, and material 13 to be dried or processed is routed, as indicated by arrow 22, upwards through said inlet duct 9 by a not shown conveyor into said input tube 7 and, by gravity means, falls through said material input tube 7 into said higher pressure end 4 of said cylinder 3 as indicated by arrows 23 and 24, and, as said portion of process gas being routed into said duct 6 is blown by said fan 2 through the length of said duct 6 running in inwardly tapering manner preferably co-axially through said length 8 of said tube 7 and through the open end of said tube 7, as indicated by arrow 25, the speed of said portion of said process gas is increased, and the pressure of said portion of the process gas at the openings of both said length 8 of said tube 7 and of said duct 6 into said higher pressure end 4 of said cylinder 3, and within said tube 7, is decreased by the suction created at the opening of said duct 6 into the higher pressure end 4 of said cylinder 3 to equal the pressure of said process gas at the not shown lower, atmospheric pressure end of said cylinder 3, thereby preventing said pressure differential causing process gas to be blown out of the higher pressure end 4 of said cylinder 3 through said material input tube 7 and out of the enclosure 1 through the open base 10 of said material inlet duct 9, and the process gas atmosphere in the enclosure 1 being replaced by external air or other gas drawn into said enclosure 1 through the not shown open base of the not shown material outlet duct located below the not shown lower, atmospheric pressure end of said cylinder 3, while said annular seal 17 between said part of the enclosure 1 and the higher pressure end 4 of said rotating drying or processing cylinder 3, and a conesponding, not shown annular seal between the not shown part of the enclosure above said material outlet duct and said lower pressure end of said cylinder 3, prevent the escape of process gas from or entry of external air or other gas into the enclosure 1.
Referring to both FIG. 1 and FIG. 2, the speed at which said fan 2 blows at least the portion, indicated by arrow 21, of the process gas recirculation, either through the annulus between said material input tube 7 and said length 8 of said duct 6 through said duct 6 running in inwardly tapering manner preferably co-axially through said length 8 of said tube 7 and over the open end of said tube 7, as indicated by arrows 23 and 24, and over the open end of said tube 7 as described by reference to FIG. 1, or through said duct 6 running in inwardly tapering manner preferably co-axially through said length 8 of said tube 7 and over the open end of said tube 7 through said duct 6 running in inwardly tapering manner preferably co-axially through said length 8 of said tube 7 and over the open end of said tube 7, as indicated by arrow 25 and as described by reference to FIG. 2, into the higher pressure end 4 of said cylinder 3, is controlled either by a not shown inverter, or by a not shown damper located in said duct 6, able to increase or decrease the speed at which said fan 2 blows at least the portion of said process gas recirculation, indicated by arrow 25, through said duct 6 running in inwardly tapering manner preferably co-axially through said length 8 of said tube 7 and over the open end of said tube 7 into the higher pressure end 4 of said cylinder 3, said inverter or said damper being controlled either by at least one not shown thermocouple, preferably located within or on the outer surface of said material input tube 7, or by at least one not shown gas pressure detection or gas movement detection device located within said material input tube 7, whereby, in use, if hot process gas tends to be blown through said material input tube 7 from said higher pressure end 4 of said cylinder 3 into said enclosure 1 said speed is increased, or, if cooler process gas tends to be drawn through said material input tube 7 from said enclosure 1 into said higher pressure end 4 of said cylinder 3 said speed is decreased, thereby ensuring that the suction at the opening of said material input tube 7 into said higher pressure end 4 of said cylinder 3, and within said material input tube 7, remains equal to the pressure differential along the length of said cylinder 3, that no process gas is blown out of the enclosure 1 through the open base 10 of the material inlet duct 9 extending downwardly from the enclosure 1 below the higher pressure end 4 of said cylinder 3, that the process gas atmosphere in the enclosure 1 is not replaced by external air or other gas drawn into the enclosure 1 through the open base 12 of the material outlet duct 11 extending downwardly from the enclosure 1 below the lower pressure end 5 of said cylinder 3, and that the density and temperature differential stratification layer seals across the inlet duct 9 and the outlet duct 11 between the process gas atmosphere within the enclosure 1 and the external air or other gas atmosphere outside the enclosure 1, remain in place at the level indicated by dotted lines 28 as described in Patent GB 2281383 and Patent Application PCT/GBO2/01497 and corresponding international patents and patent applications.
Referring to FIG. 3, there is shown diagrammatically a side view section through the material input end of a continuous drying or processing apparatus illustrating the step of preventing the pressure at the higher pressure end of an enclosure comprising, for example, a rotating drying or processing cylinder or a spray, ring or fluidised bed dryer or processor from blowing process gas from the higher pressure end of the enclosure through particulate material entering the enclosure into the external air or other gas atmosphere outside the apparatus and of preventing external air or other gas being drawn into the enclosure through the particulate material by routing material to be dried or processed into the higher pressure end of the enclosure through a material input tube having a larger diameter than that of the duct through which at least a portion of process gas is blown into the higher pressure end of the enclosure.
The material input end of the apparatus comprises a higher pressure end 1 of a thermally insulated drying or processing enclosure 2 containing not shown rotary, spray, ring, fluidised bed or other drying and/or processing apparatus, a fan 3, a preferably cylindrical duct 4, hereinafter referred to as said duct 4, a material input tube 5 having a larger diameter than said duct 4 and opening through a length 6 of said tube 5 into the higher pressure end 1 of said enclosure 2, said duct 4 passing in gastight manner into said tube 5, said duct 4 then running in inwardly tapering manner preferably co-axially through said length 6 of said tube 5 and opening into said higher pressure end 1 of said enclosure 2 in line with the opening of said length 6 of said tube S into said higher pressure end 3 of said enclosure 2, whereby the length of said duct 4 outside said tube 5, and said tube S and the length 6 of said tube S are preferably thermally insulated, a supply of particulate material 7 to be dried or processed, and part of a thermally insulated process gas recirculation duct 8 entering the higher pressure end 3 of said enclosure 2 in gastight manner, whereby, in use, said fan 3 routes a portion of the process gas recirculation, indicated by arrows 20 and already described by reference to FIG. 1, into said duct 4 as indicated by arrow 21, and particulate material 7 to be dried or processed is routed, as indicated by arrow 22, by a not shown conveyor into said material input tube 5 and, by gravity or by not shown conveyor means, falls or is conveyed through said material input tube 5 into said higher pressure end 1 of said enclosure 2 as indicated by arrows 23 and 24, and, as said portion of process gas being routed into said duct 4 is blown by said fan 3 through the length of said duct 4 running in inwardly tapering manner preferably co-axially through said length 6 of said tube 5 and through the open end of said tube 5, as indicated by arrow 25, the speed of said portion of said process gas is increased, and the pressure of said portion of process gas at the openings of both said length 6 of said tube 5 and said duct 4 into said higher pressure end 1 of said enclosure 2, and within said tube 5, is decreased by the suction created at the opening of said duct 4 into the higher pressure end 1 of said enclosure 2 to equal the pressure of said process gas at the not shown lower, atmospheric pressure end of said enclosure 2, thereby preventing the pressure at said higher pressure end 1 of said drying or processing enclosure 2 from blowing process gas from said higher pressure end 1 of said enclosure 2 through the particulate material falling or being conveyed through said material input tube 5 into the external air or other gas atmosphere outside said enclosure 2.
Referring again to FIG. 3, the speed at which the fan 3 routes at least the portion, indicated by arrow 21, of the process gas recirculation into the duct 4 and into and through the inwardly tapering length of said duct 4 and over the open end of the material input tube 5, as indicated by arrow 25, into the higher pressure end 1 of said enclosure 2, is controlled either by a not shown inverter, or by a not shown damper located in said duct 4, able to increase or decrease the speed at which said fan 3 blows at least the portion of said process gas recirculation, indicated by arrow 25, over the open end of said tube 5 into the higher pressure end 1 of said enclosure 2, said inverter or said damper being controlled either by at least one not shown thermocouple, preferably located within or on the outer surface of said tube 5, or by at least one not shown gas pressure detection or gas movement detection device located within said material input tube 5, whereby, in use, if hot process gas tends to be blown through said tube 5 from said higher pressure end 1 of said enclosure 2 into the external air or other gas atmosphere outside said enclosure 2 said speed is increased, or if excessive suction created at the opening of said duct 4 tends to draw external air or other gas through said material tube 5 into said higher pressure end 1 of said enclosure 2 said speed is decreased, thereby ensuring that the suction created at the opening of said tube 5 into said higher pressure end 1 of said enclosure 2, and within said tube 5, prevents either the blowing of hot process gas through said tube 5 from said higher pressure end 1 of said enclosure 2 into the external air or other gas atmosphere outside said enclosure 2 or the drawing of external air or other gas through said material tube 5 into said higher pressure end 1 of said enclosure 2.
While in the preceding detailed description continuous drying or processing of materials in rotating cylinders or in a drying or processing enclosure have been cited by way of example, use of the invention is not confined to drying or processing materials in rotating cylinders, and the apparatus described herein for preventing either the pressure differential created along the length of rotating drying or processing cylinders causing the process gas atmosphere to be blown out of, or external air or other gas to be drawn into enclosures within which such cylinders are located, or the pressure at the higher pressure end of a drying or processing enclosure blowing process gas from the higher pressure end of such drying or processing enclosures into the external air or other gas atmosphere outside such enclosures, or excessive suction created at the opening of material input tubes drawing external air or other gas into the higher pressure ends of such enclosures, may be adapted for use with, for example, drying or processing materials in spray, ring or fluidised bed dryers or processors to prevent either the pressure differential created along such dryers or processors, or the pressure at the higher pressure end of a drying or processing enclosure, or excessive suction created at the opening of material input tubes, causing either process gas atmospheres to be blown out of the enclosures within which such dryers or processors are located or external air or other gas to be drawn into such enclosures, and to enable a lower weight of process gas at a higher temperature to pass along such dryers or processors while avoiding heating the dried or processed materials about to leave such dryers or processors and exit the enclosures within which such dryers or processors are located through the outlet ducts of such enclosures to above the required output temperature of said material.

Claims (13)

  1. CLAIMS1. A method of drying or processing materials in a drying or processing cylinder or other drying or processing apparatus located within or forming at least part of an enclosure, including the step of routing by fan means at least a portion of a process gas entering a higher pressure region of the enclosure through venturi means and around, over, across, through or adjacent the open end of a material input tube at increased speed and reduced pressure to provide suction at the opening of the tube into the higher pressure region of the enclosure, whereby the suction at the opening of the tube into the higher pressure region of the enclosure is sufficient to prevent or substantially prevent the pressure at the higher pressure region of the enclosure causing the process gas atmosphere in the enclosure to be blown through the tube and out of the enclosure into the external air or other gas atmosphere outside the apparatus.
  2. 2. A method according to Claim 1, wherein the venturi means is defined by an annulus, the input tube having a smaller diameter than the external diameter of the annulus.
  3. 3. A method according to Claim 1 or Claim 2, wherein the portion of process gas is routed through the space within a rectangular duct around a rectangular portion of the input tube of smaller dimensions than the rectangular duct and over the open end of the input tube.
  4. 4. A method according to Claim 3, wherein the input tube and rectangular duct are arranged coaxially.
  5. 5. A method according to Claim 1, wherein the portion of the process gas is routed through an inwardly tapering portion of a duct acting as the venturi means and at increased speed and reduced pressure through the inwardly tapering portion of the duct and through the open end of the input tube, the input tube having a larger diameter than said duct.
  6. 6. A method according to any of the preceding claims, further comprising the step of controlling the speed at which the fan means route said at least a portion of the process gas at increased speed and reduced pressure to provide suction at the opening of the tube into the higher pressure region of the enclosure, wherein inverter or damper means controlled by at least one of thermocouple, pressure detection or gas movement detection means vary both the speed at which the fan means route at least a portion of the process gas over, around, adjacent or through the open end of the input tube and the suction at the open end of the input tube whereby, if hot process gas tends to be blown through the input tube from the higher pressure region of the enclosure and out of the enclosure the speed and the suction are increased, or if cool external air or other gas from outside the enclosure tends to be drawn through the input tube into the process gas atmosphere within the enclosure the speed and the suction are decreased, thereby preventing any unwanted movement of any gas through the input tube and into or out of the apparatus.
  7. 7. A method substantially as hereinbefore described with reference to the accompanying drawings.
  8. 8. An apparatus for drying or processing materials comprising an enclosure, fan means for routing at least a portion of a process gas entering a higher pressure region of the enclosure through venturi means located and arranged such that, in use, the portion of process gas passes around, over, across, through or adjacent an open end of an inlet tube at increased speed and reduced pressure to reduce the pressure at the open end of the inlet tube.
  9. 9. An apparatus according to Claim 8, further comprising a duct through which the said at least a portion of a process gas is routed.
  10. 10. An apparatus according to Claim 9, wherein a portion of the inlet tube is located within and extends coaxially with the duct.
  11. 11. An apparatus according to Claim 10, wherein the duct is of inwardly tapering shape.
  12. 12. An apparatus according to Claim 9, wherein a portion of the inlet tube surrounds a portion of the duct.
  13. 13. An apparatus substantially as hereinbefore described with reference to the accompanying drawings.
GB0820780A 2008-11-13 2008-11-13 Material drying or processing method and apparatus comprising a venturi Withdrawn GB2465361A (en)

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Application Number Priority Date Filing Date Title
GB0820780A GB2465361A (en) 2008-11-13 2008-11-13 Material drying or processing method and apparatus comprising a venturi
GB0912369.6A GB2465246B (en) 2008-11-13 2009-07-16 Drying and/or processing of materials
EP09752449A EP2344824A2 (en) 2008-11-13 2009-11-10 Drying and/or processing of materials
MYPI2011002126A MY159158A (en) 2008-11-13 2009-11-10 Drying and/or processing of materials
PCT/GB2009/002630 WO2010055281A2 (en) 2008-11-13 2009-11-10 Drying and/or processing of materials
CN200980132659.XA CN102132120B (en) 2008-11-13 2009-11-10 Drying and/or handling of materials
HK10108526.4A HK1142122B (en) 2008-11-13 2010-09-08 Drying and/or processing of materials

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB0820780A GB2465361A (en) 2008-11-13 2008-11-13 Material drying or processing method and apparatus comprising a venturi

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GB0820780D0 GB0820780D0 (en) 2008-12-17
GB2465361A true GB2465361A (en) 2010-05-19

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GB0912369.6A Active GB2465246B (en) 2008-11-13 2009-07-16 Drying and/or processing of materials

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GB (2) GB2465361A (en)
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RU2593326C1 (en) * 2015-03-11 2016-08-10 Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования Костромская Государственная Сельскохозяйственная Академия Direct action heat generator
RU180416U1 (en) * 2017-07-04 2018-06-13 Александр Викторович Фролов HOT GAS GENERATOR
CN118565179B (en) * 2024-07-31 2024-10-08 福建省德化县帝窑陶瓷有限公司 Daily ceramic drying production device and method thereof

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GB647958A (en) * 1947-08-13 1950-12-28 Peter Spence & Sons Ltd Improvements relating to apparatus for drying or calcining materials
GB774309A (en) * 1953-08-22 1957-05-08 Buttner Werke Ag Process and apparatus for the drying of damp material in pneumatic driers
US3309785A (en) * 1964-10-23 1967-03-21 Northern Natural Gas Co Apparatus for forming a gas-solids suspension
US3518772A (en) * 1968-09-30 1970-07-07 Barr & Murphy Ltd Apparatus for drying finely divided heat sensitive particles
GB2111820A (en) * 1981-12-17 1983-07-13 American Brands Method for expanding tobacco with steam at high temperature and velocity
GB2147982A (en) * 1983-10-13 1985-05-22 Brown & Williamson Tobacco Corp Pneumatic tobacco conveying and treating apparatus
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GB2465246B (en) 2013-11-20
EP2344824A2 (en) 2011-07-20
CN102132120B (en) 2014-12-17
MY159158A (en) 2016-12-30
GB0820780D0 (en) 2008-12-17
CN102132120A (en) 2011-07-20
HK1142122A1 (en) 2010-11-26
WO2010055281A2 (en) 2010-05-20
WO2010055281A3 (en) 2010-11-18
GB0912369D0 (en) 2009-08-26
GB2465246A (en) 2010-05-19

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