GB2113563A - Controlling a dewatering machine - Google Patents

Controlling a dewatering machine Download PDF

Info

Publication number
GB2113563A
GB2113563A GB08300229A GB8300229A GB2113563A GB 2113563 A GB2113563 A GB 2113563A GB 08300229 A GB08300229 A GB 08300229A GB 8300229 A GB8300229 A GB 8300229A GB 2113563 A GB2113563 A GB 2113563A
Authority
GB
United Kingdom
Prior art keywords
controlling
dewatering machine
filtrate
sludge
screen
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
Application number
GB08300229A
Other versions
GB8300229D0 (en
GB2113563B (en
Inventor
Peter Eustacchuio
Heinz Perchthaler
Rupert Syrowatka
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.)
Andritz AG
Original Assignee
Andritz AG
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 Andritz AG filed Critical Andritz AG
Publication of GB8300229D0 publication Critical patent/GB8300229D0/en
Publication of GB2113563A publication Critical patent/GB2113563A/en
Application granted granted Critical
Publication of GB2113563B publication Critical patent/GB2113563B/en
Expired legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B9/00—Presses specially adapted for particular purposes
    • B30B9/02—Presses specially adapted for particular purposes for squeezing-out liquid from liquid-containing material, e.g. juice from fruits, oil from oil-containing material
    • B30B9/24—Presses specially adapted for particular purposes for squeezing-out liquid from liquid-containing material, e.g. juice from fruits, oil from oil-containing material using an endless pressing band
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/04—Filters with filtering elements which move during the filtering operation with filtering bands or the like supported on cylinders which are impervious for filtering
    • B01D33/042—Filters with filtering elements which move during the filtering operation with filtering bands or the like supported on cylinders which are impervious for filtering whereby the filtration and squeezing-out take place between at least two filtering bands
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/58—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element
    • B01D33/62—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element for drying
    • B01D33/64—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element for drying by compression
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/70—Filters with filtering elements which move during the filtering operation having feed or discharge devices
    • B01D33/72—Filters with filtering elements which move during the filtering operation having feed or discharge devices for feeding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/70—Filters with filtering elements which move during the filtering operation having feed or discharge devices
    • B01D33/74—Filters with filtering elements which move during the filtering operation having feed or discharge devices for discharging filtrate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/80—Accessories
    • B01D33/804—Accessories integrally combined with devices for controlling the filtration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/80—Accessories
    • B01D33/804—Accessories integrally combined with devices for controlling the filtration
    • B01D33/806—Accessories integrally combined with devices for controlling the filtration by flow measuring
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D37/00—Processes of filtration
    • B01D37/03—Processes of filtration using flocculating agents

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Treatment Of Sludge (AREA)
  • Filtration Of Liquid (AREA)

Abstract

A moving bond screen press for dewatering sludge has a means 12 for monitoring the flow of filtrate from filtration zone 10, and thereby are controlled the variable speed pump 20 which delivers sludge to the press, variable speed pumps 28, 30 which supply flocculant to the sludge upstream of respective mixers 18, 19, and variable speed motor 9 which drives the press screen bonds. Use of flocculant is optimised despite variations in solids-content of the sludge. <IMAGE>

Description

SPECIFICATION Device for controlling a dewatering machine This invention relates to a device for controlling a dewatering machine, in particular a double screen dewatering machine (screen band press), comprising one or more than one control circuit for adjusting it to sludges or suspensions having variable dewatering characteristics, such as a circuitforcontrolling the flocculating agent andlor a circuit for controlling the rate of throughput or the speed of movement of the screen.
According to AT-PS 357 118, it is known to provide a double screen sludge dewatering machine with a control device consisting of a control circuitfor flocculating agent, a control circuit for the rate of throughput and a control circuit for the speed of the screen. In this arrangement, the water content of the expressed sludge and hence the extent to which the filter cake spreads out are used as measure of the quantity of flocculating agent to be added, the level of sludge in the filtering zone is used as measure of the amount of raw material to be introduced into the machine and the speed dewatering is used as an indication for altering the speed of the screen.
One disadvantage of this otherwise quite useful control device is that in certain sludges the spread of filter cake changes abruptly with the quantity of flocculating agent so that the control action is not continuous.
Proceeding from this state of the art, it was an object of the present invention to provide a device for controlling a dewatering machine, in particular a double screen sludge dewatering machine, in which the control not only responds much more sensitively but also reacts to changes in the suspension during the process of dewatering, using a control circuitfor flocculating agent andlor a control circuitfor regulating the rate of throughput or a circuit for controlling the speed of the screen. According to the invention, this object is achieved by making use of the rate at which filtrate freely flows from the filtration zone as a factor governing the circuit which controls the flocculating agent.Using a circuit for controlling the rate of throughput, the level of sludge or thickness of filter cake in the filtration zone is used as a measure of the amount of raw material to be fed in. If the circuit for controlling the speed of the screen is used, this speed is adjusted by a variable speed drive of known type in dependence upon the desired rate of free discharge of filtrate. According to a further feature of the invention, the rate of addition of flocculating agent is optimized by iteration steps to maximize the free discharge of filtrate.
The invention will now be described in more detail with reference to an embodiment illustrated by way of example in the drawings, in which Figure 1 represents a control device for a double screen sludge dewatering machine and Figure 2 is a graph of the variation in quantity of flocculating agent.
Fig. 1 is a schematic representation of the arrangement of the control device for the double screen sludge dewatering machine. The double screen press 1 is constructed in known manner. The upper screen band 6 is carried over the deflecting rollers 2 and 3 arranged at each end of the band while the lower screen band 7 is stretched over deflecting rollers 4 and 5. The deflecting roller 3 also functions as drive roller driven by a variable speed motor 9.
The material which is required to be dewatered is passed between the two screen bands 6 and 7 and is subjected to several S-shaped deflections by the special arrangement of the rollers of the wedgeshaped zone 16 and press zone 15. Each screen 6 and 7 is provided with a screen cleaning device 8. The deflecting roller 4 is set so far forwards that the breast box or entry zone 17 is suitable for dewatering by gravity in the filtration zone. A receiving vat 10 for the filtrate is placed under this region. This vat 10, which has an uneven surface, has the discharge pipe 11 attached at its deepest point This pipe leads to a flow meter 12, the function of which will be described in more detail later. The meter 13 for measuring the thickness of the filter cake is placed at some point on the upper surface of a press roller over which the two screens 6,7 travel.
The suspension to be dewatered is carried by the feed pipe 21 to the sludge pump 20 which is designed to cope with a variable rate of throughput.
The pump 20 is driven by a drive motor 22 which is connected to the control lead 24.
Connected adjacent to the sludge pump 20 is a consistency meter 25 for measuring the solid content. This meter is connected to the control instrument 32 by the control lead 33. A flow meter 26 fitted into the feed pipe 21 is also connected to the control instrument 32 as well as being connected to the control device 23 for adjusting the rate ofthroughput of the suspension.
The feed pipe 21 carrying the suspension to the double screen band press 1 also contains a mixer 18 for sludge deflocculating agent. The flocculating agent is supplied by way of the pipe 27, the solution of flocculating agent being delivered by the pump 28 which is driven by a variable speed drive 29. An additional mixer 19 connected intothefeed pipe is also supplied with solution of flocculating agent by a pump 30 with drive 31 by way of a pipe 27. Both drives 29 and 31 are connected to the control instrument 32 by a control lead 24, and the drive motor 9 of the double band press 1 is also connected to the control instrument 32.
The control instrument 32 which is responsible for contolling the dosing of flocculating agent is thus dependent upon the consistency meter 25, the flow meter 26 and the flow meter 12 by way of the control lead 33. It acts upon the drives 9,29 and 31. The control device 23 is provided for the rate of throughput of suspension and is connected, by way of a control lead 33, to the measuring instrument 14for the sludge level, the meter 13 for measuring thickness of the filter cake and the flow meter 26 which controls the driving motor 22 for the sludge pump.
The drawings originally filed was informal and the print here reproduced is taken from a iater filed formal copy.
Fig. 2 shows a graph in which the quantity of filtrate is entered in m3/h along the ordinate and the quantity of flocculating agent in M3/h along the abscissa. The graph shows the relationship between the quantity of flocculating agent supplied to a sludge of constant quantity and constant solid content and the amount of filtrate obtained when this sludge is dewatered on a screen band press. It shows that the quantity of filtrate obtained initially increases with increasing quantity of flocculating agent added but beyond a certain quantity of flocculating agent, which is specific for a particular sludge, the increase in quantity of flocculating agent is accompanied by progressively less rapid increase in the quantity of filtrate until the quantity of filtrate finally decreases.This known effect is referred to in the art as over-flocculation and is utilized for the purpose of this invention.
The important point is that for the control circuit of flocculating agent, the quantity of filtrate freely discharged in the filtration zone should be used as guiding factor. The quantity of flocculating agent added from one or more than one source of flocculating agent is optimized, the quantity of filtrate freely discharged being made to follow the maximum value or optionally a predetermined value and in particular being adjusted to settle in at that value by iteration steps. If the quantity of solid in the suspension varies along a curve determined by the characteristics of the solid, as represented in its basic form in Fig. 2, then the new optimum for the quantity offlocculating agent is readjusted proportionally.If several filtering agents are used, the proportions of quantities added are altered so that the quantity of filtrate freely discharged also in this case tends towards a maximum.
If yet another control circuit is used, such as the circuit for controlling the rate of throughput, the sludge level in the filtration zone as indicated by the measuring instrument 14 or the thickness of filter cake as indicated by the meter 13 is used as a measure for the quantity of raw material to be supplied.
When a control circuit for regulating the speed of the screen is used, the variable speed drive (motor 9) is also controlled in dependence upon the desired rate of free discharge from the filter.
One result achieved by this control device is that dewatering is always carried out with the optimum or minimum use of flocculating agent even if the suspensions are constantly varying or that a certain operating state is achieved, e.g. maximum throughput of the system, and readjustment is carried out very rapidly and without manual intervention, and the desired results may be obtained using any of the above mentioned control circuits on its own or in combination with the other circuits.

Claims (10)

1. Device for controlling a dewatering machine, in particular a double screen sludge dewatering machine (screen band press), comprising one or more than one control circuit for adjustment to sludges or suspensions having variable dewatering characteristics, such as a control circuitforflocculat- ing agent and/or a circuit for controlling the rate of throughput or a circuit for controlling the speed of movement of the screen, characterised in that the quantity of filtrate freely flowing from the filtration zone is used as guiding factor for the control circuit controlling the flocculating agent.
2. Deviceforcontrolling a dewatering machine using a further control circuit, in particular a circuit for controllins the rate of throughput, characterised in that in the filtration zone, the level of sludge (measuring instrument 14) or the thickness of filter cake (cake thickness meter 131. is used as measure for the quantity of raw material to be fed in.
3. Device for controlling dewatering machine, in particular a circuit for controlling the speed of the screen, characterised in that the screen speed is controlled by a variable speed drive (9) of known type in dependence upon the desired rate of free discharge of filtrate.
4. Device for controlling a dewatering machine according to claim 1, characterised in that the quantity of flocculating agent added from one or more sources of flocculating agent can be optimized, the quantity of freely discharged filtrate being made to follow the maximum value or optionally a predetermined value.
5. Device for controlling a dewatering machine according to claims 1 and 4, characterised in that maximization of the rate of free discharge of filtrate is carried outforthe control process by iteration steps.
6. Device for controlling a dewatering machine according to claims 1,4 and 5, characterised in that as the quantity of solid in the suspension varies, the quantity of flocculating agent is proportionally readjusted to the prevailing optimum value.
7. Device for controlling a dewatering machine according to claims 1 and 4 to 6, characterised in that when several flocculating agents are used, the proportions of their quantities added may be varied so that the rate of free discharge of filtrate tends towards the maximum value or the predetermined value.
8. Device for controlling a dewatering machine according to claims 1 and 4to 7, characterised in that the level of sludge in the filtration zone or the thickness of filter cake is maintained at a given constant value.
9. A dewatering machine having at least one control means for adjustment to sludges or suspensions having different dewatering characteristics, wherein the control means is-operated in dependence on the quantity of filtrate flowing from a filtration zone of the machine.
10. A double screen sludge dewatering machine constructed and arranged substantially as herein described and shown in the drawing.
GB08300229A 1982-01-07 1983-01-06 Controlling a dewatering machine Expired GB2113563B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AT0002882A AT381691B (en) 1982-01-07 1982-01-07 METHOD FOR CONTROLLING A DRAINAGE MACHINE AND DRAINAGE MACHINE

Publications (3)

Publication Number Publication Date
GB8300229D0 GB8300229D0 (en) 1983-02-09
GB2113563A true GB2113563A (en) 1983-08-10
GB2113563B GB2113563B (en) 1985-12-11

Family

ID=3479609

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08300229A Expired GB2113563B (en) 1982-01-07 1983-01-06 Controlling a dewatering machine

Country Status (7)

Country Link
AT (1) AT381691B (en)
AU (1) AU1021783A (en)
DE (1) DE3300249C2 (en)
FR (1) FR2519264B1 (en)
GB (1) GB2113563B (en)
IT (1) IT1159820B (en)
ZA (1) ZA83113B (en)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0146015A2 (en) * 1983-12-02 1985-06-26 BASF Aktiengesellschaft Method of determining the dispersion grade in concentrated flowing dispersions
EP0215653A2 (en) * 1985-09-13 1987-03-25 Wickham Land Limited Filtration apparatus control
WO1989005185A1 (en) * 1987-12-08 1989-06-15 Fospur Limited Production of filter cakes and the like
WO1993022027A1 (en) * 1992-05-01 1993-11-11 Pannevis B.V. Separating apparatus provided with measuring means
US5571404A (en) * 1994-10-31 1996-11-05 Pannevis B.V. Belt filter with means to advance the belt responsive to a capacitance signal
US20110272346A1 (en) * 2008-12-24 2011-11-10 Degremont Quick static decanter for prethickening water treatment sludge, and plant including such a decanter
WO2020013698A1 (en) * 2018-07-13 2020-01-16 Haskoningdhv Nederland B.V. Method for dewatering watery biomass
EP4037801A4 (en) * 2019-10-02 2023-06-21 Tevet Water Technologies Ltd Wastewater treatment system

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH669740A5 (en) * 1985-03-18 1989-04-14 Von Roll Ag
DE3743428A1 (en) * 1986-12-22 1988-07-07 Passavant Werke Process for conditioning and draining sludges
DE102005043445B4 (en) * 2004-10-13 2008-07-24 Gebr. Bellmer Gmbh & Co. Kg, Maschinenfabrik Belt filter press for juice extraction

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2452379C3 (en) * 1974-11-05 1979-08-23 Seitz-Werke Gmbh, 6550 Bad Kreuznach Procedure for determining the switching points for mixed liquids in filtration processes
DE2457844C3 (en) * 1974-12-06 1978-06-08 Vadim Petrovitsch Abramov Control device for periodically operating filters
GB1593045A (en) * 1976-07-26 1981-07-15 Lrs Res Apparatus for the removal of liquid solid and semi-solid wastes from receptacles
US4198298A (en) * 1978-02-13 1980-04-15 EDC/Enviro Development Co., Inc. System and apparatus for control and optimization of filtration process
AT357118B (en) * 1978-10-27 1980-06-25 Andritz Ag Maschf DEVICE FOR CONTROLLING A DRAINAGE MACHINE
DE2920350A1 (en) * 1979-05-19 1980-11-20 Basf Ag METHOD FOR DRAINING CLEANER SLUDGE ON CHAMBER FILTER PRESSES
CA1157390A (en) * 1980-01-30 1983-11-22 Susumu Fujinami Belt pressure filter

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0146015A2 (en) * 1983-12-02 1985-06-26 BASF Aktiengesellschaft Method of determining the dispersion grade in concentrated flowing dispersions
EP0146015A3 (en) * 1983-12-02 1987-01-07 BASF Aktiengesellschaft Method of determining the dispersion grade in concentrated flowing dispersions
EP0215653A2 (en) * 1985-09-13 1987-03-25 Wickham Land Limited Filtration apparatus control
EP0215653A3 (en) * 1985-09-13 1989-07-26 Wickham Land Limited Filtration apparatus control
WO1989005185A1 (en) * 1987-12-08 1989-06-15 Fospur Limited Production of filter cakes and the like
WO1993022027A1 (en) * 1992-05-01 1993-11-11 Pannevis B.V. Separating apparatus provided with measuring means
US5571404A (en) * 1994-10-31 1996-11-05 Pannevis B.V. Belt filter with means to advance the belt responsive to a capacitance signal
US20110272346A1 (en) * 2008-12-24 2011-11-10 Degremont Quick static decanter for prethickening water treatment sludge, and plant including such a decanter
US9011677B2 (en) * 2008-12-24 2015-04-21 Degremont Quick static decanter for prethickening water treatment sludge, and plant including such a decanter
WO2020013698A1 (en) * 2018-07-13 2020-01-16 Haskoningdhv Nederland B.V. Method for dewatering watery biomass
EP4037801A4 (en) * 2019-10-02 2023-06-21 Tevet Water Technologies Ltd Wastewater treatment system

Also Published As

Publication number Publication date
DE3300249A1 (en) 1983-07-14
FR2519264B1 (en) 1990-02-23
AU1021783A (en) 1983-07-14
GB8300229D0 (en) 1983-02-09
GB2113563B (en) 1985-12-11
AT381691B (en) 1986-11-10
IT8319038A0 (en) 1983-01-07
ATA2882A (en) 1986-04-15
IT1159820B (en) 1987-03-04
DE3300249C2 (en) 1986-03-27
FR2519264A1 (en) 1983-07-08
ZA83113B (en) 1983-10-26

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PCNP Patent ceased through non-payment of renewal fee