JP2011016042A - Method and system for dewatering muddy water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and system for dewatering muddy water which can stably obtain dehydrated cakes having a fixed strength.SOLUTION: The muddy water is reacted with a flocculant in a flocculation reaction tank 3 to generate flocculated muddy water. The flocculated muddy water is drained off by a rotating drum screen 41, and then compressed and dehydrated by a screw press 5 to generate dehydrated cakes C having a predetermined water content. The rotational speeds of the drum screen 41 optimum for a plurality of muddy waters different in concentration are obtained as data with respect to the respective concentrations of the muddy waters. While referring the data, the rotation drive of the drum screen 41 is controlled, and the amount of the flocculated muddy water supplied from the flocculation reaction tank 3 to the drum screen 41 per unit time is controlled so as to be optimum.

Description

  The present invention relates to a method and system for dewatering muddy water generated mainly during dredging work for dam lakes, harbors and rivers, tunnel excavation work, and the like.

  The mixture of water, clay, silt, etc. (hereinafter referred to as “muddy water”) generated during dredging work in dam lakes, harbors and rivers, tunnel excavation work, etc. (hereinafter referred to as “muddy water”) is separated into dehydrated cake. In the agglomeration reaction tank, the muddy water and the aggregating agent are agitated and mixed so that the soil particles form flocs, and agglomerated muddy water is generated and supplied into the filter cylinder of the screw press. It is dehydrated while being transported through the filter cylinder by rotation to form a dehydrated cake.

  When the coagulated mud water is directly supplied from the coagulation reaction tank to the screw press, draining is insufficient, and the moisture content of the coagulated mud water supplied to the screw press increases. As a result, water that could not be filtered by the filter cylinder in the vicinity of the inlet of the screw press accumulates, and the processing efficiency of the screw press decreases. Moreover, the water | moisture content in aggregation mud water is transferred to the discharge port of a screw press, and the produced | generated dehydrated cake has a high moisture content, is inferior in intensity | strength, and there exists a possibility that it cannot be reused.

  Therefore, Patent Document 1 discloses that the condensed mud water is supplied to the screw press after draining with a draining conveyor.

Japanese Patent No. 3924738

  However, the moisture content of the generated dewatered cake changes due to the change in the concentration of muddy water depending on the place of occurrence, and it is not possible to stably obtain a dehydrated cake with a certain strength.

  An object of this invention is to provide the dehydration processing method and system of a muddy water which can obtain the dewatering cake of fixed intensity | strength stably in view of the above point.

  1st invention produces | generates the mixture which added the intensity | strength increasing material of the dewatering cake produced | generated to a muddy water in a coagulation reaction tank, reacts a coagulant | flocculant with this mixture, produces | generates the agglomerated muddy water, and the drum which rotates this agglomerated muddy water A muddy water dehydration method for producing a dehydrated cake having a predetermined moisture content by pressing and dewatering with a screw press after draining with a screen, the content determined from the content of the strength increasing material and the specifications of the screw press An optimum rotation speed of the screw of the screw press is determined based on the limit moisture content of the dewatered cake, and a throughput per unit time of the aggregated mud water in the screw press when the screw rotates at the optimum rotation speed is determined. In order to supply an agglomerated muddy water with a throughput per hour to the screw press, a mixture of different contents and muddy water concentrations of the strength increasing material Supplying a plurality of kinds of agglomerated muddy water produced by reacting the collecting agent to the drum screen, and obtaining the optimum rotation speed of the drum screen optimal for draining the agglomerated muddy water as data for each concentration of the muddy water, The rotation of the screw of the screw press is controlled to rotate at the optimum rotation speed, and the optimum rotation speed of the drum screen according to the content of the strength increasing material and the concentration of muddy water is referred to the data. The rotational drive of the drum screen is controlled so as to rotate at the determined optimum rotational speed, and the drainage ratio and the screw press when the drum screen is rotated at the optimum rotational speed are set to the optimum rotational speed. Based on the treatment amount per unit time of the coagulated mud water when rotating in the above, the drum screen from the coagulation reaction tank And controlling the unit time per supply amount of the aggregating mud supply.

  According to the first invention, since the rotational drive of the drum screen and the supply amount per unit time of the aggregated mud supplied to the drum screen are controlled based on the content of the strength increasing material and the concentration of the muddy water, Regardless of changes in the content rate and the concentration of muddy water, the moisture content of the aggregated muddy water supplied to the screw press can be made constant. Therefore, the dehydrated cake discharged from the screw press has a predetermined moisture content and a constant strength.

  Further, the limit moisture content of the dewatered cake is uniquely determined from the content of the strength increasing material and the specifications of the screw press, and the optimum rotational speed of the screw of the screw press is determined based on the determined limit moisture content of the dewatered cake. And since the rotational drive of a screw press is controlled so that it rotates with this calculated | required optimal rotational speed, the dewatering cake discharged | emitted from a screw press has required intensity | strength, and it becomes possible to reuse it suitably.

  Furthermore, the data to be referred to when determining the optimum rotation speed of the drum screen is actually the drums of multiple types of coagulated mud produced by reacting the coagulant with a plurality of mixtures having different contents of the strength increasing material and mud concentration. The optimal rotation speed of the drum screen that is supplied to the screen and optimal for draining the agglomerated muddy water is obtained in advance for each muddy water concentration, so that the optimum rotation speed of the drum screen is easy even if the muddy water concentration changes. Can be determined.

  Furthermore, the agglomeration supplied from the agglomeration reaction tank to the drum screen based on the draining rate when the drum screen is rotated at the optimum rotation speed and the treatment amount per unit time of the agglomerated mud water when the screw press is rotated at the optimum rotation speed. Since the amount of muddy water supplied per unit time is controlled, the processing capacity can be maximized.

  Further, in the first invention, since the mixture in which the strength increasing material of the dehydrated cake to be generated is added to the muddy water is generated in the aggregation reaction tank, the strength of the dehydrated cake to be generated can be appropriately increased, It becomes possible to stably produce a dehydrated cake having strength suitable for use.

  In the first invention, the strength increasing material preferably includes at least one of sand, fly ash, slag, and cement.

  The second invention is a flocculation reaction in which a flocculant is reacted with a plurality of mixtures having different strength-increasing material contents and muddy water concentrations in a mixture to which a strength increasing material for a dehydrated cake produced in muddy water is added. A tank, a muddy water concentration detection unit for detecting the concentration of the muddy water, a strength increasing material content rate detection unit for detecting the content of the strength increasing material in the mixture, and the agglomerated mud water generated in the agglomeration reaction tank by rotating. A drum screen that drains water, a drum screen control unit that controls rotation of the drum screen based on the concentration of muddy water detected by the muddy water concentration detection unit, and agglomerated mud water that is supplied from the agglomeration reaction tank to the drum screen The agglomerated muddy water supply amount control unit for controlling the supply amount per unit time and the agglomerated muddy water drained by the drum screen have a predetermined water content A screw press for generating a water cake, and an optimum rotational speed of the screw of the screw press is determined based on a limit moisture content of the dehydrated cake determined from the content of the strength increasing material and the specification of the screw press, and the optimum rotational speed The amount of the agglomerated muddy water in the screw press when the screw rotates is determined per unit time, and the content of the strength increasing material so that the agglomerated muddy water in the unit time is supplied to the screw press. And a plurality of kinds of agglomerated mud produced by reacting the flocculant with a plurality of mixtures having different muddy water concentrations are supplied to the drum screen, and the optimum rotation speed of the drum screen is optimal for draining the agglomerated muddy water. A data storage unit for storing data acquired for each concentration, and a screw for controlling the rotational drive of the screw press A press control unit, wherein the drum screen control unit refers to the data stored in the data storage unit, the strength increasing material content rate detected by the strength increasing material content rate detection unit and the muddy water concentration detection unit Determining the optimum rotation speed of the drum screen according to the concentration of the muddy water detected in step (b), controlling the rotation drive of the drum screen so as to rotate at the determined optimum rotation speed, A unit of aggregated muddy water to be supplied from the aggregation reaction tank to the drum screen based on a draining rate when the drum screen is rotated at the optimum rotation speed and a processing capacity per unit time of the aggregated muddy water in the screw press. The supply amount per hour is controlled.

  According to the second invention, the drum screen controller drives the drum screen to rotate based on the content of the strength increasing material detected by the strength increasing material content detecting unit and the concentration of muddy water detected by the muddy water concentration detecting unit. Since the control unit controls the supply amount per unit time of the aggregated muddy water supplied to the drum screen by the aggregated muddy water supply control unit, it is supplied to the screw press regardless of the change in the content of the strength increasing material and the concentration of the muddy water. It is possible to keep the water content of the coagulated mud water constant. Therefore, the dehydrated cake discharged from the screw press has a predetermined moisture content and a constant strength.

  Further, the limit moisture content of the dewatered cake is uniquely determined from the content of the strength increasing material and the specifications of the screw press, and the optimum rotational speed of the screw of the screw press is determined based on the determined limit moisture content of the dewatered cake. And since the screw press control part controls the rotational drive of the screw press so that it rotates at the obtained optimum rotational speed, the dewatered cake discharged from the screw press has the necessary strength and can be reused suitably. It becomes possible.

  Furthermore, the data to be referred to when determining the optimum rotation speed of the drum screen is actually the drums of multiple types of coagulated mud produced by reacting the coagulant with a plurality of muddy water having different contents and mud concentrations of strength increasing materials. Since the optimum rotation speed of the drum screen that is optimal for draining the agglomerated muddy water is obtained in advance for each muddy water concentration and accumulated in the data accumulation unit data, the strength increasing material content rate detection unit Even if the content rate of the detected strength increasing material and the concentration of muddy water detected by the muddy water concentration detection unit change, the drum screen control unit can easily determine the optimum rotation speed of the drum screen.

  Furthermore, the agglomerated mud supply controller controls the agglomeration reaction based on the drainage rate when the drum screen is rotated at the optimum rotational speed and the throughput per unit time of the agglomerated mud when the screw press is rotated at the optimum rotational speed. Since the supply amount per unit time of the aggregated mud water supplied from the tank to the drum screen is controlled, the processing capacity can be maximized.

The figure explaining the dehydration processing system of the muddy water concerning the embodiment of the present invention. The graph which shows the relationship between the rotation speed of a drum screen by the difference in the density of muddy water, and the draining rate. The flowchart which shows the dehydration processing method of muddy water.

  A muddy water dewatering system A according to an embodiment of the present invention will be described. Referring to FIG. 1, a muddy water dewatering apparatus A mainly includes a muddy water storage tank (raw mud tank) 1, a mixture storage tank 2, an agglomeration reaction tank 3, a hopper 4, and a screw press 5.

  The muddy water storage tank 1 stores muddy water. The muddy water is a mixture of water, clay, silt, etc., from which the gravel and a lot of sand have been removed from the mud generated from dredging work in dam lakes, harbors and rivers, tunnel excavation work, etc. The muddy water stored in the muddy water storage tank 1 is stirred by a stirring blade that is rotationally driven by a motor (not shown) in order to prevent sedimentation. The muddy water stored in the muddy water storage tank 1 is discharged by the pump P <b> 1 and is pumped toward the mixture storage tank 2 through the pipeline 11. The pump P1 is driven and controlled by the control unit 12.

  The muddy water storage tank 1 is provided with a muddy water concentration detection unit 13 that detects the concentration α of muddy water in the muddy water storage tank 1. The muddy water concentration detection unit 13 measures the specific gravity of the muddy water in the muddy water storage tank 1, and based on the measured specific gravity and data indicating the correlation between the specific gravity and the concentration of muddy water obtained in advance. Is detected.

  The mixture storage tank 2 stores a mixture of muddy water and sand. The muddy water is discharged from the muddy water storage tank 1 by the pump P <b> 1 and supplied into the mixture storage tank 2 through the pipe line 11. Sand is added for the purpose of improving the dewatering rate of muddy water and increasing the strength of the dewatered cake, and is supplied into the mixture storage tank 2 from a sand storage place (not shown) via a belt conveyor or the like. The mixture stored in the mixture storage tank 2 is stirred by a stirring blade that is rotationally driven by a motor (not shown) in order to prevent sedimentation. The mixture stored in the mixture storage tank 2 is discharged by the pump P <b> 2 and is pumped toward the aggregation reaction tank 3 through the pipe line 21. The pump P <b> 2 is driven and controlled by a control unit (aggregated mud water supply control unit) 22.

  The mixture reservoir 2 is provided with a sand content detector 23 that detects the sand content A in the dry matter (solid matter other than water in the muddy water) in the mixture reservoir 2. The sand content detection unit 23 measures the specific gravity of the mixture in the mixture storage tank 2 and obtains the specific gravity by measurement in advance from the measured specific gravity value and the value of the mud concentration α detected by the mud concentration detector 13. The sand content A in the dry matter in the mixture reservoir 2 is detected based on the data indicating the correlation between the specific gravity of the mixture and the sand content.

  Although the details of the agglomeration reaction tank 3 are not shown, the rotating shaft on which the stirring blades are formed is driven to rotate by a motor (not shown) to stir the staying matter staying inside, and the staying matter is removed from the upstream side. This is a biaxial paddle mixer that is transported downstream. In addition, a rotating shaft having a feeding blade formed in the agglomeration reaction tank 3 may be provided, and the staying material may be transferred by rotationally driving it with a motor.

  The mixture discharged from the mixture storage tank 2 is supplied into the aggregation reaction tank 3 from the receiving port 31. The mixture supplied into the agglomeration reaction tank 3 is mixed with an aggregating agent such as an anionic or cationic one charged from the inlet 32 while being stirred by a stirring blade as a stagnant substance and transferred downstream by a feeding blade. By reacting, the soil particles are aggregated to form flocs and become agglomerated muddy water.

  The side wall on the downstream side of the tank where the agitating blade and, if necessary, the feed blade rotate is a weir 33, and the agglomerated muddy water overflowing over the weir 33 flows into the hopper 4 through the discharge port 34.

  The hopper 4 incorporates a rotating drum screen 41. The drum screen 41 is a cylindrical draining screen in which a large number of fine meshes are formed, and is driven to rotate by a motor M1. The motor M1 is rotationally controlled by a control unit (drum screen control unit) 42. The upper part of the drum screen 41 is exposed through the opening. The agglomerated muddy water dropped on the outer cylinder surface of the rotating drum screen 41 is transported downstream as the drum screen 41 rotates. However, a part of the agglomerated muddy water passes through the mesh of the drum screen 41 and passes through the filtrate. As shown in FIG. On the other hand, the agglomerated muddy water that has passed through the drum screen 41 is supplied to the screw press 5. Further, a watering shower (not shown) for spraying water to wash the drum screen 41 is provided, and this water is also discharged into the filtrate treatment tank.

Optimum rotation speed of the drum screen 41 when a plurality of agglomerated muds produced by reacting a flocculant charged in the agglomeration reaction tank 3 with a plurality of mixtures having different sand contents A and muddy water concentrations are drained by the drum screen 41 N _D and the data indicating the draining rate S when the drum screen 41 were rotated at the optimum rotational speed N _D is stored in the data storage unit 43. These data are obtained by conducting experiments using the drum screen 41. The drainage rate S is data obtained when aggregated muddy water in the vicinity of the processing capacity limit is supplied to the drum screen 41, in other words, when aggregated muddy water is supplied in such an amount that the drainage rate is about S. Optimum rotating speed N _D, and draining the ratio S of the drum screen 41, the specifications of the drum screen 41, i.e. the diameter, width, of the mesh size, determined by the circumferential length and the like of the draining portions, is specific to the drum screen 41.

If the concentration of the muddy water is drained drum screen 41 have the same cohesive mud at a feed rate per the same time, with reference to FIG. 2, when the rotational speed N _D of the drum screen 41 is at a low speed, outside of the drum screen 41 Since the subsequent agglomerated muddy water falls on the agglomerated muddy water existing on the cylinder surface, the draining rate S is low. On the other hand, when the rotational speed N _D of the drum screen 41 is a high speed, aggregation muddy water is short time present on the outer cylinder surface of the drum screen 41, the lower draining rate S. Thus, draining the ratio S is present a region of the rotational speed N _D good drum screen 41.

When muddy water is high concentration, with reference to the curve shown by the solid line in FIG. 2, draining ratio S is relatively poor, and there is a narrow speed N _D region D1 of good drum screen 41 draining ratio S . The area itself good rotational speed N _D of the draining rate S can be optimized rotational speed N _D. On the other hand, if muddy water is at low concentrations, with reference to the curve shown by a dotted line in FIG. 2, draining ratio S is relatively high, and the area of the rotational speed N _D of the draining rate S good drum screen 41 D2 Is wide. Then, if the energy efficiency is also considered necessary for driving the drum screen 41, the optimum rotational speed N _D of the drum screen 41, draining ratio S is within region D1 or D2 of the good rotational speed N _D, and the lowest rotational speed Become. In addition, the higher the sand content, the better the draining rate S.

  The screw press 5 includes a cylindrical filter cylinder 51 formed of punching metal or the like and extending in the horizontal direction, and a screw 52 rotatably disposed in the filter cylinder 51. The supplied agglomerated muddy water is squeezed and dewatered while being conveyed to the downstream side (left side in FIG. 1) by the screw 52, and the separated water falls from the gap between the filter tubes 51.

  The filter tube 51 is provided with a receiving port 53, and the condensed mud supplied from the hopper 4 is introduced into the filter tube 51 from the receiving port 53. The screw 52 includes a tapered screw shaft whose diameter gradually increases from the upstream side to the downstream side of the filter tube 51, and a helical screw blade fixed to the outer peripheral surface of the screw shaft. The screw 52 is rotationally driven by the motor M2. The rotation drive of the motor M2 is controlled by a control unit (screw press control unit) 54.

  When the screw 52 is rotated, the agglomerated muddy water received from the receiving port 53 is conveyed from the upstream side to the downstream side of the filter tube 51 by the feeding action by the screw blades. Since the space between the filter tube 51 and the screw shaft is gradually narrowed toward the downstream side, the aggregated mud is compressed while being conveyed toward the downstream side of the filter tube 51. The water of the aggregated mud water is squeezed out through the filter cylinder 51, falls as a filtrate, and is discharged to the filtrate treatment tank through a water collecting bowl 55 formed at the bottom. In addition, although not shown in figure, the watering pipe which sprays water and wash | cleans the outer surface of the filter cylinder 51 is provided, and this water is similarly discharged | emitted by the said filtrate treatment tank. A discharge port 56 is opened at the downstream end of the filter tube 51. The dewatered cake C that is the dewatered agglomerated muddy water is discharged to the outside from the discharge port 56.

  Hereinafter, a method for dewatering muddy water according to an embodiment of the present invention using the muddy water dewatering system A will be described with reference to FIG.

First, the supply amount X per unit time of the condensed mud water to the screw press 5 is determined (S10). Although the supply amount X per unit time changes according to the rotational speed of the screw 52 of the screw press 5, first, the strength of the dewatered cake C is determined (S11). The dewatered cake C is reused as embankment or backfill according to its strength. The strength of the dehydrated cake C is evaluated by, for example, the cone index defined by JISA1228. If the cone index is 800 kN / m ² or higher, it is classified as Type ² construction generated soil, if it is 400 kN / m ² or higher, it is classified as Type 3 construction generated soil, and if it is 200 kN / m ² or higher, it is classified as Type 4 construction generated soil. , The usage of reuse is specified respectively.

  The strength of the dehydrated cake C is determined by its moisture content and sand content A. Then, the limit moisture content at which further dewatering is impossible is determined by the sand content A and the specifications of the screw press 5 to be used. In this type of muddy water having a high water content, the ratio of dewatering by gravity filtration through the filter cylinder 51 of the screw press 5 is large, and dehydration by pressing reduces the opening area of the cross section. Since the concentration is performed only in a short section near the outlet of 5, the dehydration rate at the time when the rotation of the screw 52 of the screw press 5 is changed from natural filtration to pressing is not related to the concentration of muddy water. This is because the value is almost constant. Therefore, the moisture content of the dewatered cake C is a substantially constant value close to the limit moisture content regardless of the height of the screw 52 as long as the rotational speed of the screw 52 is within a predetermined range. In this way, the moisture content of the dewatered cake C is determined depending on the sand content A and the specifications of the screw press 5 to be used, regardless of the concentration of the muddy water to be supplied. The sand content A1 in the dry matter of the muddy water corresponding to the required strength is determined (S12). That is, dewatering with various sand contents A by screw press 4 until the limit moisture content is reached. At that time, a muddy water dry matter having a sand content A satisfying the required strength with the strength of dewatered cake C satisfying the required strength. The sand content is A1. And the content rate A1 in the mixture currently stored in the mixture storage tank 2 is adjusted so that the sand content rate A which the sand content rate detection part 23 detects becomes the determined sand content rate A1. Specifically, when the sand content A is lower than the sand content A1, sand is supplied into the mixture storage tank 2 from a sand storage place (not shown) via a belt conveyor or the like. When the sand content A is higher than the sand content A1, the pump P1 is driven to supply muddy water from the muddy water storage tank 1 into the mixture storage tank 2.

Based on the determined sand content A and the specifications of the screw press 5, that is, the diameter, total length, blade pitch, opening width of the discharge port 57, the mesh size of the filter cylinder 51, etc., the optimum rotation of the screw 52 determines the speed _{N S} (S13). For example, when priority is given to processing of aggregation mud in the screw press 5, the optimum rotational speed N _S of the screw 52, which can be required strength of dehydrated cake C is obtained, in other words, the fastest to reach the critical moisture content Rotation speed. By optimum rotating speed N _S of the screw 52 is determined, per unit time supply amount X of aggregation mud to a screw press 5 is determined (S10).

  Next, the supply amount Y per unit time of the condensed mud water to the hopper 4 is determined (S20). Since the aggregated mud supplied to the hopper 4 is drained by the drum screen 41, the supply amount Y per unit time is increased from the supply amount X per unit time by the draining rate S by the drum screen 41. .

The muddy water concentration detector 13 detects the muddy water concentration α (S21). Based on the sand content A1 determined in S12 and the muddy water concentration α detected in S21, the optimum rotational speed N _D and draining rate S of the drum screen 41 are determined with reference to the data stored in the data storage unit 43. (S22). Thereby, the supply amount Y per unit time of the condensed mud water to the hopper 4 is determined (S20).

Then, the control unit 22 drives and controls the pump P2 so that the mixture stored in the mixture storage tank 2 is supplied to the aggregation reaction tank 3 by the supply amount Y per unit time, and is stored in the mixture storage tank 2. The control unit 13 drives and controls the pump P1 so that the mixture becomes a predetermined amount. Moreover, as the drum screen 41 is rotated at optimal speed N _D, drives and controls the rotation of the motor M1 by the control unit 42, so that the screw 52 is rotated at optimal speed N _S, the motor M2 by the control unit 54 Drives and controls the rotation.

As described above, according to the density α of mud mud density detection unit 13 has detected, the drum screen 41 is optimum rotating speed N rotate together with _D, per unit time supplied aggregation mud supplied to the drum screen 41 Since the amount is controlled, the moisture content of the aggregated mud water supplied to the screw press 5 can be made constant regardless of the change in the mud concentration α. Therefore, the dewatered cake C discharged from the screw press 5 has a predetermined moisture content, has a constant strength, and has excellent reusability.

Further, based on the required strength of the dehydrated cake C, to determine the sand content in the mixture, the screw 52 is rotated at optimal speed N _S determined on the basis of the determined sand content. Therefore, the dewatered cake C discharged from the screw press 5 has the required strength and can be reused suitably. Furthermore, since the data accumulated in the data accumulating unit 43 corresponds to a plurality of composites having different sand contents and muddy water concentrations A, the required strength of the dewatered cake C is changed and the sand contents change. also, it is possible to determine the optimum rotating speed N _D of the drum screen 41. Further, the agglomerated muddy water supply amount controller controls the agglomeration reaction tank 3 based on the drainage rate S when the drum screen 41 is rotated at the optimum rotational speed N _D and the treatment capacity per unit time of the agglomerated muddy water in the screw press 5. Since the supply amount per unit time of the aggregated mud water supplied to the drum screen 41 is controlled, the processing capacity can be maximized.

  In addition, although the case where the horizontal screw press 5 was used as an example was explained as the muddy water dewatering treatment system A, the components of the system, the arrangement order, and the like were appropriately changed, such as using a vertical screw press. May be.

  Moreover, each control part 13,22,42,54 may perform an automatic control, or an operator may control using a switch etc. FIG. Further, the data storage unit 43 may store data in a memory or the like of a personal computer, or may describe data, a graph, or the like on a document.

  Further, sand is added as a strength increasing material for increasing the strength of the dehydrated cake. However, the present invention is not limited to this, and materials such as fly ash, slag, cement and the like may be used alone or in combination with sand. Good.

Depending on the kind of strength-increasing agent is not necessarily to be effective to promote drainage like sand, optimum rotating speed N _D and critical moisture content of a screw press 5 the drum screen 41, the kind of strength-increasing agent Needless to say, it varies depending on the content.

  DESCRIPTION OF SYMBOLS 1 ... Muddy water storage tank, 2 ... Mixture storage tank, 3 ... Coagulation reaction tank, 5 ... Screw press, 13 ... Muddy water concentration detection part, 22 ... Control part (coagulation muddy water supply control part), 23 ... Sand content rate detection part, DESCRIPTION OF SYMBOLS 41 ... Drum screen 42 ... Control part (drum screen control part) 43 ... Data storage part 51 ... Filter cylinder 52 ... Screw 54 ... Control part (screw press control part) A ... Muddy water dehydration processing system, C ... dehydrated cake, M1 ... motor, M2 ... motor, P2 ... pump.

Claims (3)

After producing a mixture added with a strength increasing material for dehydrated cake produced in muddy water in the coagulation reaction tank, reacting the mixture with a coagulant to produce coagulated mud water, and draining the coagulated mud water with a rotating drum screen , A muddy water dehydration method for producing a dehydrated cake having a predetermined moisture content by pressing and dewatering with a screw press,
The optimum rotation speed of the screw of the screw press is determined based on the limit moisture content of the dehydrated cake determined from the content of the strength increasing material and the specifications of the screw press, and the screw is rotated at the optimum rotation speed. The amount of coagulated muddy water in the screw press is determined per unit time, and the mixture of the content of the strength increasing material and the muddy water concentration is different so that the amount of coagulated muddy water per unit time is supplied to the screw press. A plurality of types of agglomerated muddy water generated by reacting the aggregating agent is supplied to the drum screen, and the optimum rotation speed of the drum screen that is optimal for draining the agglomerated muddy water is obtained as data for each concentration of the muddy water. ,
Controlling the rotational drive of the screw of the screw press so as to rotate at the optimum rotational speed,
An optimum rotation speed of the drum screen according to the content of the strength increasing material and the concentration of muddy water is determined with reference to the data, and the drum screen is driven to rotate so as to rotate at the determined optimum rotation speed. As well as control
Based on the draining rate when the drum screen is rotated at the optimum rotation speed and the throughput per unit time of the agglomerated muddy water when the screw press is rotated at the optimum rotation speed, the drum screen is removed from the aggregation reaction tank. A method for dewatering muddy water, characterized in that the supply amount per unit time of agglomerated muddy water supplied to the water is controlled.   The method for dewatering muddy water according to claim 1, wherein the strength increasing material includes at least one of sand, fly ash, slag, and cement. A coagulation reaction tank for producing coagulated mud water by reacting a coagulant with a plurality of mixtures having different contents and muddy water concentrations of the strength increasing material in the mixture to which the strength increasing material of the dewatered cake generated in the muddy water is added;
A muddy water concentration detector for detecting the muddy water concentration;
A strength increasing material content detection unit for detecting the content of the strength increasing material in the mixture;
A drum screen that rotates and drains the agglomerated muddy water generated in the agglomeration reaction tank;
A drum screen control unit that controls the rotational drive of the drum screen based on the concentration of muddy water detected by the muddy water concentration detection unit;
An agglomerated mud water supply control unit for controlling the amount of agglomerated mud supplied from the agglomeration reaction tank to the drum screen per unit time;
A screw press that produces a dehydrated cake having a predetermined moisture content by squeezing and dewatering the agglomerated muddy water drained by the drum screen;
The optimum rotation speed of the screw of the screw press is determined based on the limit moisture content of the dehydrated cake determined from the content of the strength increasing material and the specifications of the screw press, and the screw is rotated at the optimum rotation speed. The amount of coagulated muddy water in the screw press is determined per unit time, and the mixture of the content of the strength increasing material and the muddy water concentration is different so that the amount of coagulated muddy water per unit time is supplied to the screw press. A plurality of types of agglomerated muddy water generated by reacting the aggregating agent are supplied to the drum screen, and the data obtained for the optimum rotation speed of the drum screen optimal for draining the agglomerated muddy water is accumulated for each concentration of the muddy water. A data storage unit;
A screw press control unit for controlling the rotational drive of the screw press,
The drum screen control unit refers to the data accumulated by the data accumulation unit, the strength increase material content rate detected by the strength increase material content rate detection unit and the muddy water concentration detected by the muddy water concentration detection unit. Determining the optimum rotation speed of the drum screen according to the control, and controlling the rotation drive of the drum screen to rotate at the determined optimum rotation speed,
The agglomerated muddy water supply amount control unit is configured to remove the agglomerated reaction tank from the agglomeration reaction tank based on a draining rate when the drum screen is rotated at the optimum rotation speed and a processing capacity per unit time of the agglomerated muddy water in the screw press. A muddy water dewatering system that controls the amount of aggregated muddy water supplied to the screen per unit time.

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