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WO2014170823A1 - Procédé et installation pour la régénération d'eau de traitement dans un système de lavage pour des flocons de matière plastique - Google Patents

Procédé et installation pour la régénération d'eau de traitement dans un système de lavage pour des flocons de matière plastique Download PDF

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Publication number
WO2014170823A1
WO2014170823A1 PCT/IB2014/060730 IB2014060730W WO2014170823A1 WO 2014170823 A1 WO2014170823 A1 WO 2014170823A1 IB 2014060730 W IB2014060730 W IB 2014060730W WO 2014170823 A1 WO2014170823 A1 WO 2014170823A1
Authority
WO
WIPO (PCT)
Prior art keywords
process water
water
collecting tank
washing
plant
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/IB2014/060730
Other languages
English (en)
Inventor
Flavio Previero
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.)
Previero N SRL
Original Assignee
Previero N SRL
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 Previero N SRL filed Critical Previero N SRL
Publication of WO2014170823A1 publication Critical patent/WO2014170823A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
    • C02F1/004—Processes for the treatment of water whereby the filtration technique is of importance using large scale industrial sized filters
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/38—Treatment of water, waste water, or sewage by centrifugal separation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F2001/007—Processes including a sedimentation step
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/30—Organic compounds
    • C02F2101/301—Detergents, surfactants
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/002—Grey water, e.g. from clothes washers, showers or dishwashers
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00—Specific treatment goals
    • C02F2303/16—Regeneration of sorbents, filters

Definitions

  • the present invention refers to a method and a plant for regeneration of process water in systems for washing plastic materials to be recycled, in which the process water that exits a washing module is regenerated whilst it is made to recirculate between a collecting tank and the washing module.
  • the invention relates to a method and a plant for regeneration of process water used in washing modules for flakes of plastic materials, obtained from grinding PET containers and bottles.
  • the containers are ground into flakes of small dimensions, for example of the order of a centimetre, which are subjected to further washing steps in suitable apparatuses forming part of an entire system to remove pollutants and/or solid particles that have remained adhering to the flakes of plastic materials, or present in the mass of material.
  • the flakes of plastic materials which have to be subjected to washing treatment, are supplied in washing modules, where they are subjected to a hydraulic and mechanical action of a water flow heated to a temperature, for example, of 60-70°C, to which a suitable chemical solution is added, to permit the flakes of plastic materials to be both washed and moved.
  • a correct elimination of the solids suspended in the process water is one of the elements that determine the good operation of any washing and recirculating system; further, considering the high volumes of water that normally have to be recirculated in a washing system, as the continuous removal of the polluting material entails progressive clouding of the water and rapid depletion of the chemical washing solution, in conventional washing plants, after a certain period of time one is forced to replace much of the used water with other fresh water that has to be appropriately heated and supplemented with a new chemical washing solution.
  • a general object of the present invention is to provide a method and a plant for regeneration of process water in a system for washing flakes of plastic materials, in particular flakes of plastic materials from PET containers or bottles, by means of which it is possible to remedy the problems inherent in conventional washing systems.
  • the technical problem addressed by the present invention thus consists of regenerating the process water, achieving a substantial reduction in energy consumption, mains water and chemicals, and the reuse of the process water for comparatively longer periods than with a conventional plant, always maintaining optimum operative conditions.
  • a further object of the invention is to provide a washing method and a plant as defined, by means of which the waste water discharged into the environment can be substantially reduced, with all the consequent economic advantages for process costs.
  • a method for regeneration of process water in a washing system for flakes of plastic materials in which the process water is made to circulate between a first collecting tank and a washing module subjecting the process water to a filtration,
  • a plant suitable for regeneration of process water in a washing system for flakes of plastic materials, by the method referred to above, characterised by comprising:
  • a second recirculation circuit comprising a filtration device for the process water, between the first collecting tank for the process water and the second collecting tank for the filtered water, the filtration device for the process water being configured for eliminating solid particles having dimensions of a first order of magnitude;
  • Fig. 1 is a flow chart illustrating the method for the regeneration of the process water, according to the present invention, in a washing system for flakes of plastic materials;
  • Fig. 2 is a general diagram of a plant for the regeneration of the process water, according to the flow chart of figure 1 ;
  • Fig. 3 is an enlarged sectional view of the filtration device, according to line 3-3 of figure 2.
  • the water that exits a washing module 10 of any washing system for flakes of plastic materials, in particular flakes of plastic materials obtained from PET containers and/or bottles, after a coarse filtration 1 1, is collected in a first tank or reservoir 12, and is continuously recirculated along the circuit 13, from the collecting tank 12 to the washing module 10 to enable the flakes of plastic materials to be mixed and washed.
  • the process water that exits the washing module 10 generally consists of mains water heated to a preset temperature, in which a detergent chemical solution has been dissolved, which drags the foreign matter in suspension that has been removed from the flakes of plastic materials during the washing step 10.
  • the foreign matter removed from the flakes of plastic materials generally consists of solid particles suspended in the process water, which with the continuous recirculating cause a progressive clouding of the process water and a progressive consumption of the washing chemical; the particles of suspended solid material, generally have different dimensions, which are variable from an order of magnitude of a few microns, to a few hundred microns and more.
  • the flow of process water that exits the washing module 10 is firstly subjected to a coarse filtration step to remove foreign matter of large dimensions, for example of the order of 1 -1.5 micron.
  • the process water that has undergone this first coarse filtration is then collected in a first tank 12 from which it is again recirculated to the washing module 10 along a first circuit 13.
  • a first tank 12 As the continuous recirculation of the process water and the continuous removal of dirt or foreign material from the flakes of plastic materials entails progressive clouding of the process water, instead of discharging and completely renewing the entire process water after a preset time according to the conventional methods, with consequent costs of greater consumption of water and washing chemical, and the need to dispose of great volumes of polluted water, according to the present invention it was decided to regenerate the process water by drawing part of the process water contained in the collecting tank 12; filtering the process water in a suitable filtration device 15, so as to remove solid suspended and/or sedimentable particles having dimensions of a first order of magnitude greater than that of the holes or meshes of the filter; and collecting the filtered water in a second collecting tank 16 from which the filtered water is made to circulate, a schematically shown by 17, mixing the filtered water with the
  • the washing chemical are not depleted, which thus remains in the process water that is made to recirculate; in this manner not only the process water and the chemical in the solution are reused to continue washing the flake material in the module 10, with a consequent reduction in the consumption of the chemical and of mains water, but dilution of the process water with new mains water is also avoided with consequent reduction of water consumption and saving of the heating energy that would otherwise be necessary to return the process water to the required washing temperature.
  • part of the filtered water is drawn from the second collecting tank 16, subjecting the filtered water to a clarification step 19, i.e. to a further filtration step for removing solid particles having a lower order of magnitude than that of the particles removed during the first filtration step 15.
  • the filtered and subsequently clarified water can now be supplied to a cleaning system 20 for cleaning the filtering device 15, as explained above.
  • the waste water produced during the clarification step 19 and the filter cleaning step 20 is then disposed of; as the waste water is concentrated and of an extremely reduced volume, the quantity of mains water and of new chemical required to renew the process water, are in turn extremely reduced.
  • the flakes of plastic materials to be recycled are washed in a module 10, of per se known type, by a flow of suitably heated process water containing the necessary detergent chemical; the process water that exits the washing module 10 with the various solid substances in suspension, after a pre-filtration step for example by a vibrating screen 1 1 necessary for removing the coarsest solid parties of a few millimetres, is collected in the first tank 12 and then made to circulate to the washing module 10 by a pump PI and a flow line 13.
  • a fraction of the process water contained in the first collecting tank 12 is drawn by a pump P2 and made to circulate along a second flow line 14, to a mechanical filter 15 suitable for providing a high filtration degree, i.e. that is such as to retain solid particles in suspension that have an order of magnitude equal to about 100 micron and above.
  • the filtered water that exits the filter 15, is collected in a second tank 16 connected to the first collecting tank 12, for example by overflowing as indicated with 17.
  • Part of the filtered water contained in the second collecting tank 16 is in turn drawn by a pump P3 and supplied, by a flow line 18, to an inlet 19' of a clarification device 19, where the water is filtered further to separate suspended substances having dimensions of a lower order of magnitude than that of the particles retained by the filter 15, for example an order of magnitude of a few microns, or a little more.
  • the clarified water that exits the outlet 19" of the clarification device 19, by a flow line 20 is supplied to a cleaning system 34 of the filter 15.
  • the concentrated waste that exits the filter 15 and the clarifying device 19 is in turn discharged into a sludge collecting tank 21 ' and 21" or is otherwise deposed of.
  • the collecting tank 12 for the process water that is recirculated to the washing module 10, and the tank 16 collecting the filtered water can be of any type or conformation and arrangement, always maintaining a fluid connection between one another to enable the filtered water in the collecting tank 16 to flow into the tank 12 and regenerate the process water.
  • the filtered water contained in the tank 16 flows into the tank 12 by simple gravity. This can be achieved, for example as shown in figure 2, by configuring the two tanks 12 and 16 in the form of an integrated unit in which the collecting tank 16 for the filtered water is positioned on a side of the collecting tank 12 for the process water, and has an upper edge through which the filtered water can overflow by gravity into the tank 12.
  • the filter 15 used only for the fraction of process water necessary for regeneration and for clarification of the cleaning water for the filter 15, can be of any type provided that is suitable for the prescribed use.
  • the filter 15 is a rotary filter, for example of the disc type as schematically shown in figure 3.
  • the filter 15 comprises a tank 25 inside which two filtering discs 26 rotate, that are axially spaced apart and mechanically connected to a drive shaft driven of a reduction gear motor 27.
  • the two filtering discs 26 divide the tank 25 into three separate chambers, of which one is a central chamber 28 for containing the process water to be filtered, and two lateral chambers 30 for containing the filtered water; the process water enters the chamber 28 by an inlet fitting 29, whilst the filtered water contained in the chambers 30 can be made to flow out through a first outlet fitting 31 , to be discharged into the second collecting tank 16.
  • a second outlet fitting 32 (figure 2), discharges overflow water from the central chamber 28 of the filter into the first collecting tank 12 of the process water.
  • the discs 26 have through holes or openings for the passage of the water that, by simple gravity, filters from the central chamber 28 into the two lateral chambers 30, passing through a filtering layer 33 consisting for example of a net with meshes of reduced dimensions, of the order of a few microns, that are suitably fixed to the internal side of each filtering disc 26 facing the central chamber 28.
  • the water in the central chamber 28 in general is maintained at a higher level than that of the filtered water in the two lateral chambers 30, so that it passes by simple gravity through the filtering layer 33 of the two discs 26.
  • the two discs protrude beyond the level of water in the chambers 28 and 30 so as to clean the nets 33 by a counterflow cleaning system, for example formed by two sets of flow nozzles 34 positioned in the upper part of the two lateral chambers 30, suitably connected to the supply line 20 of the clarified water.
  • a counterflow cleaning system for example formed by two sets of flow nozzles 34 positioned in the upper part of the two lateral chambers 30, suitably connected to the supply line 20 of the clarified water.
  • clarified water for cleaning the filtering discs is advantageous because it contains solid particles in suspension that are of a lower order of magnitude than that of the meshes of the filtering nets 33, preventing the nets from being obstructed by solid particles contained in the sprays of clarified water.
  • the second filtration required for clarifying the cleaning water for the filter 15 can be made with any suitable filtration and clarifying device; in the case shown, a centrifugal clarifying device of per se known type has been used, comprising a conical disc rotor 35 that is rotated at high speed to provide a higher filtration degree that that of the first filter 15 by the centrifugal force generated by the revolution number of rotor 35.
  • the plant for regenerating the process water, in a washing system for flakes of plastic materials, will be provided with all the instrumentation necessary for automatic control thereof, which provides continuous regeneration of the process water that is made to circulate between the collecting tank 12 and one or more washing modules 10, and clarification of a fraction of the process water, for cleaning the filtration device 15.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Organic Chemistry (AREA)
  • Analytical Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Cleaning By Liquid Or Steam (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)

Abstract

L'invention concerne un procédé et une installation pour régénérer de l'eau de lavage pour des flocons de matières plastiques, en particulier provenant de conteneurs et bouteilles de PET. L'eau de traitement qui quitte un module (10) de lavage est recirculée en continu le long d'un premier circuit (13) entre un premier réservoir de collecte (12) et le module de lavage (10) ; on régénère l'eau de traitement en la mélangeant avec de l'eau de traitement filtrée obtenue en soutirant une partie de l'eau de traitement dans le premier réservoir de collecte (12), en la faisant recirculer le long d'un second circuit (14) comprenant un dispositif de filtration (25), puis en la déchargeant dans un second réservoir de collecte (16) en communication fluidique avec le réservoir de collecte (12) pour l'eau de traitement. Une partie de l'eau filtrée dans le second réservoir de collecte (16) est à son tour clarifiée dans un dispositif de clarification (19) et utilisée pour le nettoyage du dispositif de filtration (15).
PCT/IB2014/060730 2013-04-15 2014-04-15 Procédé et installation pour la régénération d'eau de traitement dans un système de lavage pour des flocons de matière plastique Ceased WO2014170823A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITMI2013A000614 2013-04-15
IT000614A ITMI20130614A1 (it) 2013-04-15 2013-04-15 Metodo e impianto per la rigenerazione di acqua di lavaggio per materie plastiche in scaglie

Publications (1)

Publication Number Publication Date
WO2014170823A1 true WO2014170823A1 (fr) 2014-10-23

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2014/060730 Ceased WO2014170823A1 (fr) 2013-04-15 2014-04-15 Procédé et installation pour la régénération d'eau de traitement dans un système de lavage pour des flocons de matière plastique

Country Status (2)

Country Link
IT (1) ITMI20130614A1 (fr)
WO (1) WO2014170823A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4104164A (en) * 1977-03-02 1978-08-01 Chelton Robert G Device for treating waste water
US4379525A (en) * 1981-08-06 1983-04-12 Owens-Illinois, Inc. Process for recycling plastic container scrap
WO1992022380A1 (fr) * 1991-06-18 1992-12-23 Sampson Donald L Procede et appareil pour le recyclage des plastiques
DE19749530A1 (de) * 1997-11-08 1999-05-12 Hoffmeister Helmut Dr Verfahren und Vorrichtung zur Aufbereitung von Biomüll-Sammelgut

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4104164A (en) * 1977-03-02 1978-08-01 Chelton Robert G Device for treating waste water
US4379525A (en) * 1981-08-06 1983-04-12 Owens-Illinois, Inc. Process for recycling plastic container scrap
WO1992022380A1 (fr) * 1991-06-18 1992-12-23 Sampson Donald L Procede et appareil pour le recyclage des plastiques
DE19749530A1 (de) * 1997-11-08 1999-05-12 Hoffmeister Helmut Dr Verfahren und Vorrichtung zur Aufbereitung von Biomüll-Sammelgut

Also Published As

Publication number Publication date
ITMI20130614A1 (it) 2014-10-16

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