IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
UP-0911475
(2005-07-20)
|
등록번호 |
US-7828961
(2010-11-25)
|
우선권정보 |
JP-2005-116491(2005-04-14) |
국제출원번호 |
PCT/JP2005/013292
(2005-07-20)
|
§371/§102 date |
20071012
(20071012)
|
국제공개번호 |
WO06/112041
(2006-10-26)
|
발명자
/ 주소 |
- Sugaya, Kenzou
- Kawasaki, Hiroichi
- Katayama, Masayoshi
- Yamashita, Manabu
- Miyawaki, Masaharu
|
출원인 / 주소 |
|
대리인 / 주소 |
Greenblum & Bernstein, P.L.C.
|
인용정보 |
피인용 횟수 :
0 인용 특허 :
9 |
초록
▼
A differential rate rotary thickener; a power detector which is disposed in a sludge receiver tank for thickened sludge thickened in the differential rate rotary thickener; a discriminator which receives an electric signal for a thickened sludge concentration (X) detected by the power detector and w
A differential rate rotary thickener; a power detector which is disposed in a sludge receiver tank for thickened sludge thickened in the differential rate rotary thickener; a discriminator which receives an electric signal for a thickened sludge concentration (X) detected by the power detector and which calculates and discriminate the data; a first controller which receives an instruction signal being a discriminated result in the discriminator and which operates an outer cylinder driving machine and a screw driving machine; a ratio setter which receives a discriminated signal of the discriminator and which increases or decreases a chemical feed rate (α) of flocculant stepwise; and a second controller which receives an instruction signal from the ratio setter and which operates a flocculant-feeding pump are provided. Thickening of sludge is performed by controlling the chemical feed rate (α), a rotational speed (S) of a screw, and a rotational speed (C) of an outer cylinder screen.
대표청구항
▼
The invention claimed is: 1. A sludge thickening device comprising: a differential rate rotary thickener, provided with a screw in a rotatable outer cylinder screen, for filtering raw slurry sludge being fed to a feed end of the outer cylinder screen, and for discharging thickened sludge from a dis
The invention claimed is: 1. A sludge thickening device comprising: a differential rate rotary thickener, provided with a screw in a rotatable outer cylinder screen, for filtering raw slurry sludge being fed to a feed end of the outer cylinder screen, and for discharging thickened sludge from a discharge end of the outer cylinder screen, while rotating the screw at a variable speed; a thickened-sludge-concentration detecting section configured to detect a sludge concentration of the thickened sludge discharged from the differential rate rotary thickener; a flocculant-feeding section provided with a flocculant-feeding pump for feeding flocculant to the raw slurry sludge; and a control section configured to control a rotational speed C of the outer cylinder screen, a rotational speed S of the screw, and an amount of the flocculant to be fed by the flocculant-feeding pump; wherein: the differential rate rotary thickener includes an outer cylinder driving machine configured to rotate the outer cylinder screen, and a screw driving machine configured to rotate the screw; the thickened-sludge-concentration detecting section includes a sludge receiver tank configured to store the thickened sludge discharged from the differential rate rotary thickener, and a power detector configured to detect the sludge concentration of the thickened sludge and to send an electric signal to the control section; and the control section includes: a discriminator configured to receive the electric signal sent from the thickened-sludge-concentration detecting section, and thus perform arithmetic on, and discriminate, the electric signal data, a first controller configured to receive a first instruction signal sent from the discriminator for controlling rotational speeds respectively of the outer cylinder driving machine and the screw driving machine, a ratio setter configured to receive the first instruction signal sent from the discriminator for varying a chemical feed rate α of the flocculant fed to the raw slurry sludge stepwise, and a second controller configured to receive a second instruction signal sent from the ratio setter for operating the flocculant-feeding pump. 2. The sludge thickening device according to claim 1, wherein: the outer cylinder screen is closed at both ends with discoidal flange plates; the screw includes a cylindrical center axle provided with a screw vane on an outer peripheral surface thereof; a diameter f of the cylindrical center axle is 40% to 70% of an inner diameter F of the outer cylinder screen; an inlet opening configured to lead the raw slurry sludge into the outer cylinder screen from an inside of a cylindrical hollow part of the cylindrical center axle is provided on a part of a peripheral surface of the cylindrical center axle, the part being positioned near one end of the outer cylinder screen; and an outlet opening configured to discharge the thickened sludge is provided on the flange plate near the other end of the outer cylinder screen. 3. The sludge thickening device according to claim 2, wherein the screw vane is one of a single-thread vane, a double-thread vane, a triple-thread vane. 4. The sludge thickening device according to claim 1, wherein: the discriminator stores an upper limit X max and a lower limit X min of the thickened sludge concentration, an upper limit C max and a lower limit C min of rotational speed of the outer cylinder screen, and an upper limit S max and a lower limit S min of rotational speed of the screw, which are set in advance; and the discriminator sends the first instruction signal when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not less than the upper limit X max of the thickened sludge concentration or not greater than the lower limit X min of the thickened sludge concentration; the first controller receives the first instruction signal sent from the discriminator; and when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not less than the upper limit X max of the thickened sludge concentration, the first controller increases a rotational speed of the screw driving machine stepwise when a chemical feed rate of flocculant is not greater than a lower limit α min of the chemical feed rate; and when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not greater than the lower limit X min of the thickened sludge concentration X min, the first controller decreases the rotational speed of the screw driving machine stepwise until the thickened sludge concentration X becomes not less than the lower limit X min of the thickened sludge concentration or until a rotational speed S of the screw becomes equal to the lower limit S min of the rotational speed; the ratio setter stores the chemical feed rate α of flocculant, and an upper limit α max and a lower limit α min, which are respectively a maximum value and a minimum value of the chemical feed rate α of flocculant, and which are all set in advance; and the ratio setter receives the first instruction signal sent from the discriminator; and when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not less than the upper limit X max of the thickened sludge concentration, the ratio setter sends a second instruction signal until the thickened sludge concentration X becomes not greater than the upper limit X max of the thickened sludge concentration X max or until the chemical feed rate of flocculant becomes equal to the lower limit α min of the chemical feed rate; and when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not greater than the lower limit X min of the thickened sludge concentration, the ratio setter sends the second instruction signal when the rotational speed S of the screw is not greater than the lower limit S min of the rotational speed; and the second controller receives the second instruction signal sent from the ratio setter; and when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not less than the upper limit X max of the thickened sludge concentration, the second controller decreases the chemical feed rate α of flocculant stepwise until the thickened sludge concentration X becomes not greater than the upper limit X max of the thickened sludge concentration or until the chemical feed rate of flocculant becomes equal to the lower limit α min of the chemical feed rate; and when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not greater than the lower limit X min of thickened sludge concentration, increases the chemical feed rate α of flocculant stepwise when the rotational speed S of the screw is not greater than the lower limit S min of rotational speed. 5. The sludge thickening device according to claim 1, wherein: the discriminator stores an upper limit X max, a lower limit X min of the thickened sludge concentration, an upper limit C max and a lower limit C min of rotational speed of the outer cylinder screen, and an upper limit and a lower limit S min of the rotational speed of the screw, which are set in advance; and the discriminator sends the first instruction signal when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not less than the upper limit X max of the thickened sludge concentration or not greater than the lower limit X min of the thickened sludge concentration; the first controller receives the first instruction signal sent from the discriminator; and when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not less than the upper limit X max of the thickened sludge concentration, the first controller increases the rotational speed of the screw driving machine stepwise until the rotational speed S of the screw becomes equal to the maximum rotational speed S max when the chemical feed rate of flocculant is not greater than the lower limit α min of the chemical feed rate; and when the rotational speed S of the screw is not less than the upper limit S max of the rotational speed, the first controller decreases the rotational speed of the outer cylinder driving machine stepwise until the thickened sludge concentration X becomes not greater than the upper limit X max of the thickened sludge concentration; and when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not greater than the lower limit X min of the thickened sludge concentration, the first controller decreases the rotational speed of the screw driving machine stepwise until the thickened sludge concentration X becomes not less than the lower limit X min of the thickened sludge concentration or until the rotational speed S of the screw becomes equal to the lower limit S min of the rotational speed; and when the rotational speed of the screw is not greater than the lower limit S min of the rotational speed, the first controller increases the rotational speed of the outer cylinder driving machine stepwise until the sludge concentration becomes not less than the lower limit X min of the thickened sludge concentration or until the rotational speed of the outer cylinder screen becomes equal to the upper rotational speed C max; the ratio setter stores the chemical feed rate α of flocculant, and an upper limit α max and a lower limit α min of the chemical feed rate of flocculant, which are respectively a maximum value and a minimum value of the chemical feed rate α of flocculant, and which are all set in advance; the ratio setter receives the first instruction signal sent from the discriminator; and when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not less than the upper limit X max of thickened sludge concentration, the ratio setter sends a second instruction signal until the thickened sludge concentration X becomes not greater than the upper limit X max of the thickened sludge concentration or until the chemical feed rate of flocculant becomes equal to the lower limit α min of the chemical feed rate; and when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not greater than the lower limit X min of the thickened sludge concentration, the ratio setter sends the second instruction signal when the rotational speed C of the outer cylinder screen is not less than the upper limit C max of the rotational speed; and the second controller receives the second instruction signal sent from the ratio setter; and when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not less than the upper limit X max of the thickened sludge concentration, the second controller decreases the chemical feed rate α of flocculant stepwise until the thickened sludge concentration X becomes not greater than the upper limit X max of the thickened sludge concentration or until the chemical feed rate of flocculant becomes equal to the lower limit α min of the chemical feed rate; and when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not greater than the lower limit X min of the thickened sludge concentration, the second controller increases the chemical feed rate α of flocculant stepwise when the rotational speed C of the outer cylinder screen is not less than the upper limit C max of the rotational speed. 6. The sludge thickening device according to claim 1, wherein: the discriminator stores an upper limit X max and a lower limit X min of the thickened sludge concentration, an upper limit C max of and a lower limit C min of the rotational speed of the outer cylinder screen, an upper limit S max and a lower limit S min of the rotational speed of the screw, which are set in advance; and the discriminator sends the first instruction signal in any one of the case where the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not less than the upper limit X max of the thickened sludge concentration and the case where the thickened sludge concentration X is not greater than the lower limit X min of the thickened sludge concentration; the first controller receives the first instruction signal sent from the discriminator; and when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not less than the upper limit X max of the thickened sludge concentration, the first controller increases a rotational speed of the screw driving machine stepwise, and simultaneously decreases the rotational speed of the outer cylinder driving machine stepwise, when the chemical feed rate of flocculant is not greater than a lower limit α min of the chemical feed rate; and when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not greater than the lower limit X min of the thickened sludge concentration, the first controller decreases the rotational speed of the screw driving machine stepwise, and simultaneously, increases the rotational speed of the outer cylinder driving machine stepwise until the thickened sludge concentration X becomes not less than the lower limit X min of the thickened sludge concentration, or until a rotational speed S of the screw becomes equal to the lower limit S min of the rotational speed, or until the rotational speed C of the outer cylinder screen becomes equal to the upper limit C max of the rotational speed; the ratio setter stores the chemical feed rate α of flocculant, and an upper limit α max and a lower limit α min of the chemical feed rate of flocculant, which are respectively a maximum value and a minimum value of the chemical feed rate α of flocculant, and which are all set in advance; and the ratio setter receives the first instruction signal sent from the discriminator; and when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not less than the upper limit X max of the thickened sludge concentration, the ratio setter sends the second instruction signal until the thickened sludge concentration X becomes not greater than the upper limit X max of the thickened sludge concentration or until the chemical feed rate of flocculant becomes equal to the lower limit α min of the chemical feed rate; and when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not greater than the lower limit X min of the thickened sludge concentration, sends the second instruction signal when the rotational speed S of the screw is not greater than the lower limit of the rotational speed S min or when the rotational speed C of the outer cylinder screen is not less than the upper limit C max of rotational speed; and the second controller receives the second instruction signal sent from the ratio setter; and when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not less than the upper limit X max of the thickened sludge concentration, the second controller decreases the chemical feed rate α of flocculant stepwise until the thickened sludge concentration X becomes not greater than the upper limit X max of the thickened sludge concentration or until the chemical feed rate of flocculant becomes equal to the lower limit α min of the chemical feed rate; and when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is not greater than the lower limit X min of the thickened sludge concentration, the second controller increases the chemical feed rate α of flocculant stepwise when the rotational speed S of the screw is not greater than the lower limit S min of the rotational speed, or when the rotational speed C of the outer cylinder screen is not less than the upper limit C max of the rotational speed of the outer cylinder screen. 7. The sludge thickening device according to claim 1, wherein: the discriminator stores an upper limit X max and a lower limit X min of the thickened sludge concentration, an optimal rotational speed Cso of the outer cylinder screen, and an optimal rotational speed Sso of the screw, which are set in advance; and sends the first instruction signal at a time when starting to operate the differential rate rotary thickener and at a time when an amount of feed raw slurry Qs fluctuates when the thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is lower than the upper limit X max of the thickened sludge concentration and higher than the lower limit X min of the thickened sludge concentration; the optimal rotational speed Cso of the outer cylinder screen and the optimal rotational speed Sso of the screw are defined by the following relational expressions, which are derived by setting the rotational speeds of the screw and the outer cylinder screen depending on a fluctuating amount of feed raw slurry Qs: Optimal rotational speed Sso (rpm) of screw=Rotational factor S1×Process speed of raw slurry (m3/m2/h); and Optimal rotational speed Cso (rpm) of outer cylinder screen=Rotational factor C1×Process speed of raw slurry (m3/m2/h); the first controller receives the first instruction signal sent from the discriminator; and the first controller controls the screw driving machine and the outer cylinder driving machine based on the optimal rotational speeds Sso, Cso of the screw and the outer cylinder screen, respectively, calculated from the above relational expressions at a time when starting to operate the differential rate rotary thickener and at a time when the amount of feed raw slurry Qs fluctuates when a thickened sludge concentration X, which is detected by the thickened-sludge-concentration detecting section, is lower than the upper limit X max of the thickened sludge concentration and higher than the lower limit X min of the thickened sludge concentration. 8. The sludge thickening device according to claim 1, wherein the thickened-sludge-concentration detecting section further includes: a cylindrical detecting body which is suspended down into the thickened sludge, a lower end thereof being open and an air hole being formed on a top end thereof; and a driving motor including a rotary axle being connected to the cylindrical detecting body; the power detector detects a change in an electric current value of the driving motor and outputs the change in the electric current value in the form of the electric signal. 9. The sludge thickening device according to claim 2, wherein the differential rate rotary thickener further comprises: an outer cylinder closed at both ends with the discoidal flange plates, a circumferential surface thereof being formed by the outer cylinder screen, wherein: the outer cylinder has a degree-of-outlet-opening adjusting mechanism configured to increase/decrease an opening area of the outlet opening; and the degree-of-outlet-opening adjusting mechanism includes a shutter plate, the shutter plate being placed so as to overlap the flange plate having the outlet opening being formed thereon, the shutter plate providing a rotational displacement relative to the flange plate, the degree-of-outlet-opening adjusting mechanism configured to increase/decrease the opening area of the outlet opening with the shutter depending on a rotational position of the shutter relative to the flange plate. 10. A concentration detection device for a differential rate rotary thickener in which a screw is disposed in a rotatable outer cylinder screen; raw slurry sludge is fed into a feed end of the outer cylinder screen; filtered liquid is separated from the outer cylinder screen while rotating the screw at a variable speed; and thereafter thickened sludge is discharged from a discharge end of the outer cylinder screen, the concentration detection device comprising: a cylindrical detecting body for detecting a sludge concentration of the thickened sludge, which is suspended down into the thickened sludge discharged from the differential rate rotary thickener, having a lower end thereof being open and on a top end thereof an air hole being formed; a driving motor having a rotary axle which is connected to the cylindrical detecting body; and a power detector configured to detect a change in an electric current value of the driving motor, and output the change in the electric current value in the form of an electric signal. 11. The concentration detection device according to claim 10, wherein: the power detector sends the electric signal to a discriminator configured to receive the electric signal, perform arithmetic on, and discriminate, the electric signal data. 12. The concentration detection device according to claim 11, wherein the discriminator receives successive electric signals sent from the power detector; calculates a mean current value of the successive electric signals; performs a comparison operation for the mean current value, and rates of upper and lower limits of a stable current value set in advance; decreases a rotational speed S of the screw when the mean current value becomes successively lower than the rate of the lower limit for the stable current value; and increases the rotational speed S of the screw when the mean current value becomes successively higher than the rate of the upper limit for the stable current value. 13. The concentration detection device according to claim 12, wherein: the discriminator sends an instruction signal to a flocculant-feeding pump, even when the rotational speed S of the screw is controlled, if the mean current values having been continuously detected still increase to higher than the rate of an upper limit of the stable current value or still decrease to lower than the rate of an lower limit of the stable current value; the flocculant feeding pump receives the instruction signal sent from the discriminator; increases a chemical feed rate α of flocculant to be fed to raw slurry sludge when the mean current value is lower than the rate of the lower limit of the stable current value; and decreases the chemical feed rate α of flocculant to be fed to raw slurry sludge when the mean current value is higher than the rate of the upper limit of the stable current value.
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