Liquid purification or separation – With alarm – indicator – register – recorder – signal or...
Patent
1991-08-06
1993-02-02
Dawson, Robert A.
Liquid purification or separation
With alarm, indicator, register, recorder, signal or...
210 961, 210149, 210199, 210709, 210727, 210742, 2103601, 374 44, 374142, B01D 2130, G01N 2518
Patent
active
051835622
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to an apparatus for coagulating treatment. Particularly, this invention relates to an apparatus for coagulating treatment aimed at controlling to optimize the amount of a coagulant to be injected (added) to a liquid under treatment. More particularly, this invention relates to an apparatus for coagulating treatment suitable for controlling the amount of an organic coagulant (hereinafter referred to occasionally as "polymer") to be added to a liquid under treatment.
BACKGROUND OF THE INVENTION
Heretofore, various methods have been proposed for the control of a coagulant to be added in the dehydration of sludge. It has been proposed, for example, to control the amount of a coagulant to be added by indirectly measuring the residual polymer content of the liquid with the aid of a viscosimeter in view of the fact that the viscosity of the liquid varies with the residual polymer content and then using the result of this measurement as the criterion for the control.
The physical properties of the liquid include specific heat, electric conductivity, etc. besides the viscosity. They bring about various effects on the operation of addition of the coagulant. When the amount of addition of the coagulant is controlled by using as a sole criterion the viscosity which is only one of the physical properties, therefore, the actual amount of addition deviates from the proper level possibly to the extent of entailing ineffective coagulation, excessive addition of the coagulant, and unduly high cost of the coagulant.
DISCLOSURE OF THE INVENTION
An object of this invention is to solve the problems of the prior art described above and provide an apparatus for the coagulating treatment which allows the amount of addition of a coagulant to be controlled accurately and consequently optimized.
Another object of this invention is to provide a coagulating treatment apparatus which prevents the amount of addition of a coagulant from otherwise possibly deviating and accomplishes the coagulating treatment inexpensively and efficiently.
These objects are accomplished by an apparatus for the coagulating treatment wherein a coagulant is added to a liquid subjected to the coagulating treatment, which apparatus comprises a device for coagulant addition capable of adjusting the amount of addition of the coagulant, a liquid to which the coagulant is to be added, a heat transfer detector disposed so as to contact the liquid containing the added coagulant or the filtrate from the liquid containing the added coagulant, and a control device for controlling the amount of the coagulant supplied by the device for coagulant addition in accordance with the value of detection displayed on the heat transfer detector.
The present invention resides in controlling the amount of addition of a coagulant to a sludge by detecting changes in the physical constants of the sludge due to changes in the properties of the sludge as changes in heat transfer and adopting the detected changes in heat transfer as the criterion for the control.
The inventors made a study for many years concerning the dehydrating property of a liquid resulting from a coagulating treatment, to acquire a knowledge that the water content of the cake resulting from the dehydration, the detected value with the heat transfer detector in the liquid produced by the coagulating treatment (or the liquid undergoing the coagulating treatment) and the concentration of added coagulant in the sludge are closely relates to each other as illustrated in FIGS. 5 and 6, and the water content of the dehydrated cake is minimized by controlling the amount of addition of the coagulant so as to minimize the numerical value detected by the use of a hot-wire current meter, for example, in addition to the conventional knowledge.
FIGS. 5 and 6 are graphs showing the relation among the amount of addition of a coagulant (cationic polymer) to a sewage-mixed raw sludge as a raw water, the value of detection (potential difference) indicated on a hot-wire flow meter, and
REFERENCES:
patent: 3170868 (1965-02-01), Atkinson
Publication "Instrumentation and Automation Systems for Waterworks", Applications of distributed instrumentation and control system TOSDIC.TM. for waterworks, Kawabe et al., Toshiba Review, No. 133 (May-Jun. 1981) pp. 5-13.
Publication "Stimultaneous Measurement of the Thermal Conductivity and the Thermal Diffusivity of Liquids by the Transient Hot-Wire Method", Nagasaka et al., Rev. Sci. Instrum 52(2), Feb. 1981, 1981 American Institute of Physics, pp. 229-232.
Shigemi Hirotake
Totoki Toshio
Yasukawa Yoshio
Dawson Robert A.
Drodge Joseph
Kurita Water Industries Ltd.
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