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WO2002006743A1 - A method for drying the sludge cake - Google Patents

A method for drying the sludge cake Download PDF

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Publication number
WO2002006743A1
WO2002006743A1 PCT/PL2001/000007 PL0100007W WO0206743A1 WO 2002006743 A1 WO2002006743 A1 WO 2002006743A1 PL 0100007 W PL0100007 W PL 0100007W WO 0206743 A1 WO0206743 A1 WO 0206743A1
Authority
WO
WIPO (PCT)
Prior art keywords
fluidisation
drying
cake
air jet
drier
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.)
Ceased
Application number
PCT/PL2001/000007
Other languages
French (fr)
Other versions
WO2002006743A8 (en
Inventor
Olgierd Lossman
Jan Cozdz
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.)
Klimapol Spz Oojv
Original Assignee
Klimapol Spz Oojv
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 Klimapol Spz Oojv filed Critical Klimapol Spz Oojv
Publication of WO2002006743A1 publication Critical patent/WO2002006743A1/en
Publication of WO2002006743A8 publication Critical patent/WO2002006743A8/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B3/00—Drying solid materials or objects by processes involving the application of heat
    • F26B3/02—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air
    • F26B3/06—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
    • 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
    • F26B17/12—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed solely by gravity, i.e. the material moving through a substantially vertical drying enclosure, e.g. shaft
    • F26B17/14—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed solely by gravity, i.e. the material moving through a substantially vertical drying enclosure, e.g. shaft the materials moving through a counter-current of gas
    • 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

Definitions

  • This invention relates to the method for drying the sludge cake. Firstly the sludge is dehydrated then powdered and dried in two steps, initially only the surface of the sludge is dried and next the sludge is dried in the fluidisation drier.
  • Sludge cakes particularly activated sludge have very high moisture content of about 95 %. Before drying, the sludge cakes are dehydrated and its moisture is no higher than 85 %. Dehydrated sludge cake is of a consistency of paste and has a large variety of particle sizes. A powdering process is necessary for drying said cake and then the cake is loaded to the fluidisation drier in a way which excludes the agglomeration process.
  • the methods for repeated drying of sludge cakes after their dehydration include mixing the sludge cake with the carrier, wherein the carrier is preferably the dried sludge cake.
  • the aim of the invention is to provide a cheap continuos method for drying the sludge cake in a counter - current air jet, which makes unnecessary the second mixing of the dehydrated cake with the carrier.
  • a method for drying the sludge cake comprises dehydration of the cake, particularly performed by mechanical way, where the moisture is about 75-85 %, and after powdering the cake is dried in two stages.
  • the initial drying stage takes place in the loading chamber having perforated bed bottom where the sludge cake is dried to the surface - dry condition by free - falling in a counter - current air jet.
  • the second drying step is conducted in the fluidisation drier, and is characterised by that the drying air jet is expanded while flowing upward and its speed at the perforated bottom is 2-4 times higher than the convection speed of the sediments.
  • the height of the sludge cake is established at 30 to 150 mm from the surface of the perforated bottom by the means of the brace in the aperture, which is situated in the separating wall of the loading chamber connected with the fluidisation drier.
  • the initially dried sludge cake is loaded to the fluidisation drier, and the sieve of the fluidisation drier is situated below the perforated bottom of the loading chamber.
  • the drying air jet is blown in with the angle of 15 - 80 ° in relation to the fluidisation drying air jet.
  • the relation of the drying air jet speed rate to the fluidisation drying air speed rate is from 2: 1 to 8: 1.
  • the invented method effects in reducing agglomeration of the particles and excluding sticking the cake to the bottom of the sieve.
  • the gravity distance of free falling of the dried cake is increased by establishing the sieve of the fluidisation drier below the surface of the perforated bottom of the loading chamber. While the fluidisation drying process is performed, the sediment does not agglomerate because it is uniformly thickening in the fluidisation jet air.
  • the dried sludge cake which is obtained is characterised by the small amount of water content, and can be used in the production of fertilisers or as combustion fuel.
  • the sludge is dehydrated by using a centrifugal separator to the moisture of 75-85 %.
  • the cake is powdered and initially dried in a free - falling process in a counter current air jet having 110-160° C. The process is performed until the surface of the cake particles is dry.
  • the initial drying step is performed in the loading chamber having perforated bottom.
  • the drying air jet is expanded while flowing upward and has the speed at the perforated bottom 2-4 times higher than the convention speed of the sediments.
  • the height of the sludge cake is established at 30 to 150 mm from the surface of the perforated bottom by the means of the brace in the aperture, which is situated in the separating wall of the loading chamber connected with the fluidisation drier.
  • the dry cake is continuously loaded to the fluidisation drier in a drying air jet.
  • the sieve of the fluidisation drier is situated below the perforated bottom of the loading chamber.
  • the drying air jet is blown in with the angle of 15 - 80° in relation to the fluidisation drying air jet.
  • the relation of the drying air jet speed rate to the fluidisation drying air speed rate is from 2: 1 to 8: 1.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Microbiology (AREA)
  • Drying Of Solid Materials (AREA)
  • Treatment Of Sludge (AREA)

Abstract

The invention relates to a method for drying the sludge cake, in a drying air jet where its speed at the perforated bed bottom is 2-4 times higher than the convection speed of the sediments. The high of the sludge cake is established at 30-150 mm from the surface of the perforated bottom by means of the brace in the aperture. The intially dried sludge cake is loaded to the fluidisation drier.

Description

A method for drying the sludge cake
This invention relates to the method for drying the sludge cake. Firstly the sludge is dehydrated then powdered and dried in two steps, initially only the surface of the sludge is dried and next the sludge is dried in the fluidisation drier.
Sludge cakes particularly activated sludge have very high moisture content of about 95 %. Before drying, the sludge cakes are dehydrated and its moisture is no higher than 85 %. Dehydrated sludge cake is of a consistency of paste and has a large variety of particle sizes. A powdering process is necessary for drying said cake and then the cake is loaded to the fluidisation drier in a way which excludes the agglomeration process.
The methods for repeated drying of sludge cakes after their dehydration known in the art., include mixing the sludge cake with the carrier, wherein the carrier is preferably the dried sludge cake.
However, the known methods are expensive and not efficient. The use of the fluidisation drier for drying the sludge cakes is difficult because of the initial treatment of the sludge cake. The sludge on the fluidisation sieve agglomerate and glue to each other. It is a drawback while drying. The lack of the cheap method for drying the sludge cake makes both the utilisation as well as the further treatment of the sludge impossible.
That is why the sludge are stored in paddles or dumped at dumpsites.
The aim of the invention is to provide a cheap continuos method for drying the sludge cake in a counter - current air jet, which makes unnecessary the second mixing of the dehydrated cake with the carrier.
The method according to the invention also excludes additional means of transport. A method for drying the sludge cake comprises dehydration of the cake, particularly performed by mechanical way, where the moisture is about 75-85 %, and after powdering the cake is dried in two stages. The initial drying stage takes place in the loading chamber having perforated bed bottom where the sludge cake is dried to the surface - dry condition by free - falling in a counter - current air jet. The second drying step is conducted in the fluidisation drier, and is characterised by that the drying air jet is expanded while flowing upward and its speed at the perforated bottom is 2-4 times higher than the convection speed of the sediments. The height of the sludge cake is established at 30 to 150 mm from the surface of the perforated bottom by the means of the brace in the aperture, which is situated in the separating wall of the loading chamber connected with the fluidisation drier. The initially dried sludge cake is loaded to the fluidisation drier, and the sieve of the fluidisation drier is situated below the perforated bottom of the loading chamber.
The drying air jet is blown in with the angle of 15 - 80 ° in relation to the fluidisation drying air jet.
The relation of the drying air jet speed rate to the fluidisation drying air speed rate is from 2: 1 to 8: 1.
The invented method effects in reducing agglomeration of the particles and excluding sticking the cake to the bottom of the sieve.
This is the result of using the drying air jet 2-4 times higher at the perforated bottom than the convection speed of the sediments. The initially dried sludge cake is continuously loaded to the fluidisation drier, wherein the particles with required moisture content are poured over the brace. The expansion of the drying air jet while flowing upward reduces its speed, it results in uniformity of the drying process.
Loading the drying air jet with the angle 15-80° in relation to the fluidisation drying air jet, increases uniformity of the circulation and separation of the suspension.
The gravity distance of free falling of the dried cake is increased by establishing the sieve of the fluidisation drier below the surface of the perforated bottom of the loading chamber. While the fluidisation drying process is performed, the sediment does not agglomerate because it is uniformly thickening in the fluidisation jet air.
The dried sludge cake which is obtained, is characterised by the small amount of water content, and can be used in the production of fertilisers or as combustion fuel.
Example
The sludge is dehydrated by using a centrifugal separator to the moisture of 75-85 %. Next the cake is powdered and initially dried in a free - falling process in a counter current air jet having 110-160° C. The process is performed until the surface of the cake particles is dry. The initial drying step is performed in the loading chamber having perforated bottom. The drying air jet is expanded while flowing upward and has the speed at the perforated bottom 2-4 times higher than the convention speed of the sediments. The height of the sludge cake is established at 30 to 150 mm from the surface of the perforated bottom by the means of the brace in the aperture, which is situated in the separating wall of the loading chamber connected with the fluidisation drier. The dry cake is continuously loaded to the fluidisation drier in a drying air jet. The sieve of the fluidisation drier is situated below the perforated bottom of the loading chamber. The drying air jet is blown in with the angle of 15 - 80° in relation to the fluidisation drying air jet. The relation of the drying air jet speed rate to the fluidisation drying air speed rate is from 2: 1 to 8: 1.

Claims

1. A method for drying the sludge cake comprising dehydration of the cake, particularly performed by mechanical way, where the moisture is about 75 - 85%, and after powdering the cake is dried in two stages; an initial drying stage in the loading chamber having perforated bed bottom where the sludge cake is dried to the surface dry - condition by free - falling in a counter - current air jet; and a second drying step conducted in the fluidisation drier, is characterised by that the drying air jet is expanded while flowing upward and its speed at the perforated bottom is 2 - 4 times higher than the convection speed of the sediments, and the height of the sludge cake is established at 30 to 150 mm from the surface of the perforated bottom by means of the brace in the aperture, which is situated in the separating wall of the loading chamber connected with the fluidisation drier, wherein the initially dried sludge cake is loaded to the fluidisation drier, where the sieve of the fluidisation drier is situated below the perforated bottom of the loading chamber.
2. A method according to claim 1, characterised by that the drying air jet is blown in with the angle of 15 - 80° in relation to the fluidisation drying air jet
3. A method according to claim 1, characterised by that the relation of the drying air jet speed rate to the fluidisation drying air speed rate is from 2: 1 to 8:1.
PCT/PL2001/000007 2000-07-13 2001-01-29 A method for drying the sludge cake Ceased WO2002006743A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
PL341488A PL195412B1 (en) 2000-07-13 2000-07-13 Method of drying sludge
PLP.341488 2000-07-13

Publications (2)

Publication Number Publication Date
WO2002006743A1 true WO2002006743A1 (en) 2002-01-24
WO2002006743A8 WO2002006743A8 (en) 2002-02-14

Family

ID=20077036

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/PL2001/000007 Ceased WO2002006743A1 (en) 2000-07-13 2001-01-29 A method for drying the sludge cake

Country Status (2)

Country Link
PL (1) PL195412B1 (en)
WO (1) WO2002006743A1 (en)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1729279A1 (en) * 1967-03-13 1971-06-16 Buettner Schilde Haas Ag Feeding device for fluidized bed dryers for pre-drying
US4330411A (en) * 1979-05-28 1982-05-18 Escher Wyss Limited Process for treating clarified sludge
EP0537637A1 (en) * 1991-10-14 1993-04-21 Tsukishima Kikai Kabushiki Kaisha A system for drying moist sludge
DE4401623A1 (en) * 1994-01-20 1995-07-27 Waldner Gmbh & Co Hermann Sewage sludge or slurry dryer
EP0749769A1 (en) * 1995-06-20 1996-12-27 Stork Friesland B.V. Device for preparing a spray-dried product and method for preparing a product of this kind
EP0818224A2 (en) * 1996-07-11 1998-01-14 Powdering Japan K.K. Two-stage drying spray dryer
EP0857930A1 (en) * 1997-02-11 1998-08-12 Allgaier-Werke GmbH & Co. KG Apparatus and process for drying wet solid particles in fluidized beds

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1729279A1 (en) * 1967-03-13 1971-06-16 Buettner Schilde Haas Ag Feeding device for fluidized bed dryers for pre-drying
US4330411A (en) * 1979-05-28 1982-05-18 Escher Wyss Limited Process for treating clarified sludge
EP0537637A1 (en) * 1991-10-14 1993-04-21 Tsukishima Kikai Kabushiki Kaisha A system for drying moist sludge
DE4401623A1 (en) * 1994-01-20 1995-07-27 Waldner Gmbh & Co Hermann Sewage sludge or slurry dryer
EP0749769A1 (en) * 1995-06-20 1996-12-27 Stork Friesland B.V. Device for preparing a spray-dried product and method for preparing a product of this kind
EP0818224A2 (en) * 1996-07-11 1998-01-14 Powdering Japan K.K. Two-stage drying spray dryer
EP0857930A1 (en) * 1997-02-11 1998-08-12 Allgaier-Werke GmbH & Co. KG Apparatus and process for drying wet solid particles in fluidized beds

Also Published As

Publication number Publication date
PL195412B1 (en) 2007-09-28
WO2002006743A8 (en) 2002-02-14
PL341488A1 (en) 2001-01-02

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