Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
  • B04B—CENTRIFUGES
  • B04B1/00—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles
  • B04B1/20—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles discharging solid particles from the bowl by a conveying screw coaxial with the bowl axis and rotating relatively to the bowl
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
  • B04B—CENTRIFUGES
  • B04B11/00—Feeding, charging, or discharging bowls
  • B04B11/02—Continuous feeding or discharging; Control arrangements therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
  • B04B—CENTRIFUGES
  • B04B13/00—Control arrangements specially designed for centrifuges; Programme control of centrifuges

Definitions

• the present invention relates to a process for regulating centrifuges used in solid / liquid separation, in particular for the dewatering of sludge.
• a reagent (polymer) is added to the mud.
• centrifuges require regulation in order to maintain the centrifuge in the best operating zone despite the variations in concentration and quality of the inlet mud, while optimizing the dose of reagent injected. and minimizing the quantity of suspended matter not captured by the centrifuge and which ends up in the centrate.
• a choice must also be made between conventional centrifuges and so-called "intensive" centrifuges with a high filling rate of dry matter.
• Conventional regulation methods involve measuring the concentration of suspended matter and they can include:
• WO 97/20 634 describes a method as well as a device for controlling and controlling a continuous feed centrifuge which consists in measuring in real time in particular the flow of sludge and / or reagents, the content of suspended matter , the value of the torque of the centrifuge in order to regulate in particular the flow of sludge at the inlet of the centrifuge.
• the purpose of the present invention is to provide the above-mentioned performances without supervisory personnel, that is to say to automatically obtain the following characteristics:
• centrate The applicant is also the holder of FR-A-2 707 758 which relates to a device for the continuous measurement of the concentration of suspended solids a centrate, this device making it possible to carry out a reliable and continuous measurement of the content of suspended matter in the liquid phase called "centrate".
• the present invention is characterized in that the regulation of the centrifuge is carried out in fuzzy logic using the sensor signal according to Fr-A-2 707 758 as well as the other signals available on the centrifuge, which makes it possible to control the flow rates sludge and reagent admitted into said centrifuge.
• FIG. 1 of the appended drawing the structure of a fuzzy controller can be represented in the form of the diagram of this FIG. 1 in which:
• F represents the transformation of inputs E into fuzzy variables ("fuzzification")
• I is the reasoning module applied to fuzzy variables (inference rules) and,
• Fuzzy variables are sets of values assigned a degree of belonging to a family or a set of families.
• the transformation of an analog input can be broken down into a multitude of variables, or to simplify into four fuzzy variables: low, correct, high, very high (see Figure 2). The same is true for the output variables.
• the inference rules and the definition of the degree of belonging to a family define the value that the output D must take.
• the calculation of the command D consists in quantifying the fuzzy output (s) and in transform it (or them) into digital quantity (s) applicable to the process (see LA ZADEH "information and control", 8-1965).
• the present invention provides a method of regulation by fuzzy logic of a centrifuge used in solid / liquid separation, in particular for the dehydration of sewage sludge, which consists in:
• the relative speed VR (which represents the residence time of the mud in the centrifuge) and possibly, the value of the torque CPL.
• (C) act, according to the results of the treatment of the inputs on the flow of sludge, (Db) at the input of the centrifuge and / or on the flow of reagent (Dp).
• the outputs are of two types:
• These flow variation commands Db and Dp are actuated as a function of the position of the operating point of the centrifuge (characterized by the “process inputs” values mentioned above) with respect to operating ranges, defined from the rules. expertise a priori enacted by those skilled in the art; these operating ranges are standard spaces (with n dimensions, depending on the number of “process inputs” taken into account) in which the actions on the sludge and reagent flow rates make it possible to bring the operating point of the centrifuge in a space characterized as being a stable and optimal operating space.
• the invention also relates to a device for operating a centrifuge used in solid / liquid separation, in particular for the dewatering of sludge from treatment plants, characterized in that it comprises:
• this device comprises means for measuring additional input variables, such as in particular the flow of sludge Db, the flow of polymer Dp, the relative speed VR of the screw of the centrifuge relative to the bowl of this (in the case of conventional centrifuges) or of the CPL torque of the centrifuge motor (in the case of intensive centrifuges).
• additional input variables such as in particular the flow of sludge Db, the flow of polymer Dp, the relative speed VR of the screw of the centrifuge relative to the bowl of this (in the case of conventional centrifuges) or of the CPL torque of the centrifuge motor (in the case of intensive centrifuges).
• this device there is at least one zone Zs belonging to the space Z1 ... Zn called “stable and optimal operating zone” corresponding to a rule Rs according to which the flow rates of sludge Db and of polymer Dp are unchanged as long as the point representing the operation of the centrifuge is located in said zone Zs.
• the rules R1 ... Rn other than the rules Rs have the objective of bringing the point representative of the operation of the centrifuge into the zones Zs.
• the rules R1 ... Rn are defined a priori, depending on the type of centrifuge, regardless of the site where the centrifuge is located, while the limits of the zones Z1 ... Zn are defined on site, depending on local conditions, in particular the type of sludge to be treated.
• the rules Ri belonging to the set R1, ... Rn include a conclusion of the type:
• Bb (t + ⁇ t) Db (t) x (1 + Xi), in which Xi is any adjustable number on the site, Db (t) is the sludge flow at the time of Db (t + ⁇ t) is the sludge flow at time t + ⁇ t.
• each rule R1, ... Rn is associated with a number IC1 ... Icn, called the Confidence Index, representative of the appreciation of the quality of the functioning of the centrifuge and, a overall confidence, representative of the appreciation of the quality of the operation of the centrifuge at the instant operating point, is determined by fuzzy logic and assigned for information to the personnel in charge of monitoring the centrifuge.
• the invention makes it possible to ensure optimal, stable and unattended operation which results in various advantages in terms of the investments to be made for the establishment of the sludge dewatering workshop by centrifugation.

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• Centrifugal Separators (AREA)

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ID=9514058

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• 1997
  • 1997-12-02 FR FR9715166A patent/FR2771659B1/fr not_active Expired - Fee Related
• 1998
  • 1998-11-03 WO PCT/FR1998/002349 patent/WO1999028040A1/fr not_active Ceased
  • 1998-11-03 AU AU11589/99A patent/AU749997B2/en not_active Ceased
  • 1998-11-03 DE DE1051260T patent/DE1051260T1/de active Pending
  • 1998-11-03 ES ES98954506T patent/ES2151469T1/es active Pending
  • 1998-11-03 CA CA002312858A patent/CA2312858A1/fr not_active Abandoned
  • 1998-11-03 US US09/555,571 patent/US6549817B1/en not_active Expired - Fee Related
  • 1998-11-03 EP EP98954506A patent/EP1051260A1/de not_active Ceased
  • 1998-11-03 NZ NZ504619A patent/NZ504619A/xx unknown
  • 1998-11-03 JP JP2000523011A patent/JP2001524382A/ja active Pending

Non-Patent Citations (1)

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