Liquid purification or separation – Processes – Making an insoluble substance or accreting suspended...
Reexamination Certificate
2002-09-12
2004-11-30
Hopkins, Robert A. (Department: 1724)
Liquid purification or separation
Processes
Making an insoluble substance or accreting suspended...
C210S711000, C210S713000, C210S723000, C210S738000, C210S788000, C210S802000, C210S805000, C210S806000, C210S202000, C210S208000
Reexamination Certificate
active
06824692
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the domain of water treatment and is applied, in particular, to methods for treating liquid wastes, especially those using a flocculation-sedimentation system.
BACKGROUND OF THE INVENTION
These methods consist of adding one or several reagents to the waste water making it possible to coagulate at least a large part of the pollutant materials present in the waste and flocs, and then to separate the flocs thus formed from the purified water.
According to an advanced type of installation, intake means for at least one granular material denser than water, such as sand, are provided in such a way as to ballast the flocs in question and thus encourage and accelerate their sedimentation. Such a device is described in particular in the French patent FR2627704 published on Dec. 13, 1991 in the name of the Applicant.
This type of installation, called “installation for waste water treatment by ballasted flocs”, comprises a coagulation zone in the usual way, provided with water intake means, intake means for adding at least one coagulating reagent, intake means for at least one granular material denser than water and stirring means; a flocculation zone provided with stirring means; at least one sedimentation zone provided with a zone for recuperation and evacuation of sludges, means for evacuation of clarified water able to integrate lamellae; and means for recycling at least a part of the granular material contained in said sludges upstream of the sedimentation zone. In most cases these recycling means include at least one hydrocyclone.
With this type of installation, control of the concentration of granular material in the fluid during treatment is usually carried out either by direct sampling in the flocculation zone, and measuring the concentration of granular material, or by dividing the flow-rate of treated water (in cu. m. per hour) by the flux of granular material (in kg/hr) recycled to ballast the flocs. This flux is measured in the underflow of the recycling hydrocyclone.
The principal aim of the present invention is to detect, either automatically or manually, the possible losses of granular material which can occur through the underflow of the recycling hydrocyclone, particularly in the case of small hydrocyclones.
Another aim of the present invention is to measure the concentration of granular material in the fluid during treatment, so as to detect any abnormal changes of this concentration.
A further aim of the present invention is to provide means enabling rapid resumption of normal conditions of concentration of granular material.
BRIEF SUMMARY OF THE INVENTION
These aims are achieved through the present invention which relates to an installation for measuring the concentration of dense granular material in a flow comprising a liquid, a dense granular material and fine particles in suspension, characterised in that it comprises at least one separation unit for separating the dense granular material on the one hand, and the liquid and fine particles in suspension on the other hand; and at least one measurement device for the measuring of at least one parameter representative of the quantity of dense granular material separated during a defined time period T.
It is understood that this type of installation can be used with any type of flow constituted of a liquid, a dense granular material (that is to say denser than the liquid in question) and fine particles in suspension. Preferably, the liquid in question is water, said dense granular material is sand or micro-sand and the fine particles are sedimentation sludges.
According to a variant of the invention, said separation organ of said dense granular material includes at least one sedimentation unit operating at a given flow-rate and at a sedimentation speed comprised between the sedimentation speed of the sludges and the sedimentation speed of the sand, in particular between 2 m/hr and 100 m/hr, and preferably between 10 m/hr and 50 m/hr and even more preferably at a speed of 30 m/hr.
Also, according to another variant of the invention, said separation unit for the separation of said dense granular material includes at least one hydrocyclone operating at a given flow-rate instead of a sedimentation unit and whose cutting size is chosen so as to separate the granular material in the underflow of the water from the fine particles in the upper flow.
According to a preferred variant of the invention, the installation comprises a storage capacity in which the underflow of said separation unit, containing the separated dense granular material, is stocked for said given time period T, said storage capacity being provided with at least one sensor able to measure the quantity of granular material stocked inside and an emptying means making it possible to empty said storage capacity. The sensor in question is advantageously a sensor enabling measurement of the height or the weight of said dense granular material. This sensor can be mounted so as to be height-adjustable. It is also possible to use a combination of two sensors.
The present invention also relates to a process for using an installation such as that described above, which consists of calculating the concentration of said granular material in said flow by comparing, at the end of each time period T, the quantity of granular material separated from the flow constituted by the liquid and the material sent to said separation unit.
According to a variant of the invention, the process consists of comparing said concentration in granular material with a predetermined value and, in function of the result of said comparison, of activating an alarm or the stop-start means of said installation, to maintain the concentration of dense granular material in said flow within the required limits.
According to another variant, the process consists of triggering an action (alarm, stop or start-up of the installation) when the weight or the height of material in said storage capacity exceeds a predetermined threshold.
The invention also applies to any water treatment system comprising:
at least one assembly of coagulation-flocculation zones provided with means for taking in water, means for taking in at least one coagulant agent, means for taking in at least one granular material denser than water, and stirring means;
at least one sedimentation zone provided with a recuperation and evacuation zone for sludges and means for evacuating clarified water;
means for recycling at least a part of the granular material contained in said sludges upstream relative to the sedimentation zone through the intermediary of a hydrocyclone or equivalent device, making it possible to recycle the granular material and to evacuate excess sludges as overflow,
characterised in that it includes an installation for measuring the concentration of said dense granular material such as described above.
The invention thus relates to integrating, in such a system, means enabling automatic sampling of part of the waste, either directly in the coagulation zone or in the recycling means, to ascertain the quantity or concentration of granular material in this flow and consequently to obtain information about the operational quality of the system.
REFERENCES:
patent: 3666419 (1972-05-01), Cahour et al.
patent: 4279759 (1981-07-01), Pardikes
patent: 4927543 (1990-05-01), Bablon et al.
patent: 5641397 (1997-06-01), Grienberger
patent: 5730864 (1998-03-01), Delsalle et al.
patent: 6588601 (2003-07-01), Costinel
patent: 2 627 704 (1989-09-01), None
patent: 2 719 235 (1995-11-01), None
Binot Patrick
Rineau Stanislas
Hopkins Robert A.
OTV S.A.
Westman Champlin & Kelly
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