Patent Publication Number: US-3875060-A

Title: Flow mixer

Description:
United States Patent 1191 Noma 1 1 FLOW MIXER [75] Inventor: Shigeki Noma, Osaka, Japan [73] Assignee: Sun Engineering Co., Inc., Osaka,  
 Japan 221 Filed: June 14, 1974 211 Appl. No.: 479,571  
 [30] Foreign Application Priority Data 210/198 R, 199, 200, 201, 202. 205, 209; 259/4, DIG. 30; 261/76 [56] References Cited UNITED STATES PATENTS 2.532.973 12/1950 Wallentin et al. 259/4 X 3.002.922 10/1961 Baddour 210/209 X 1185.447 5/1965 Hach 259/4 Richens et a1. Fujimoto et a1. .1 259/4 X [11] 3,875,060 Apr. 1,1975  
 Primary Examiner-Samih N. Zaharna Assistant Examiner-Robert H. Spitzer Attorney, Agent, or Firm-Wenderoth, Lind &amp; Ponack [57] ABSTRACT A flow mixer for stirring or mixing liquid medium by the current of the liquid medium passing through the flow mixer, which may be referred to as a floculator. The flow mixer comprises a substantially drum-shaped housing, within which a sleeve of a substantially splitring shaped section having a clearance is provided in alignment with the longitudinal axis of the drumshaped housing Two sets of alternately radially outwardly and inwardly extending barriers are respectively secured to the outer peripheral surface of the sleeve and the inner peripheral surface of the housing. Liquid medium to be stirred or mixed enter the hollow of the sleeve and then the space between the sleeve and the housing through the clearance. Due to a particular arrangement of the barriers, the liquid medium within the space therebetween undergoes alternate expansion and contraction thereby being severely stirred or mixed.  
 10 Claims, 6 Drawing Figures PATENTEUAPR 1 I975 SHEET 2 OF &#39;2 FIG. 6  
 FLOW MIXER The present invention relates in general to a device for stirring liquid medium as it passes therethrough under pressure.  
  The present invention also pertains to a flow mixer for mixing liquid medium with an additive, which may be liquid, solid or gas or a mixture thereof, by the current of the liquid medium passing through the flow mixer under pressure.  
  So far as the iquid mixing or stirring is concerned, the present invention has a wide range of application in many fields of industry. However, due to the background in which the present invention has been developed, the device according to the present invention may be advantageously used in sewage disposal and, therefore. description of the present invention will now be made as applied in the process of sewage disposal.  
  lt is well known that the sewage disposing process essentially requires the sewage to be mixed with such a chemical additive as one or a mixture of coagulant, disinfectant, neutralizer, catalyst and/or others, which may be liquid, solid or gas or a mixture thereof, before the sewage to be disposed is fed to a settling or thickening tank or any other subsequent process, though the type of such chemical additive is selected depending on the type of the sewage to be disposed.  
  Heretofore, for mixing the sewage with the chemical additive, a mixer has generally been employed ofa type comprising a rotary blade assembly. With this conventionally employed mixer, so far as the sewage is processed by the addition oflime and aluminum surfate so as to nucleate or agglomerate impurities or contaminations that form the sewage together with water and by the subsequent addition of high polymer coagulant to render the agglomerated impurities or contaminations to separate from the water and subsequently to form a flock thereof floating on or near the surface of the body of the separated water, it has well experienced that the agglomeration of impurities or contaminations, that is taking place or has already taken place is hampered or destroyed as the sewage is fed through the rotary blade mixer. This is particularly considerable when the rotary blade assembly of the mixer is operated at a relatively high speed and, therefore. continuous, but reliable sewage disposal is often hampered, substantially reducing a sewage disposal efficiency.  
  An improved version of flow mixer now commercially available is a flow mixer of cyclone type designed such as to permit the sewage to enter a mixing chamber of the flow mixer in a tangential direction and to permit the sewage, mixed with a coagulant, to emerge from an outlet formed at the center of the top of the mixing chamber. In this cyclone-type flow mixer, the stirring speed is so low that satisfactory mixing of the sewage with the coagulant is hardly achieved and, therefore, in order to purify the sewage satisfactorily, one or more flow mixers of the same or different structure or a blade stirrer or agitator have to be connected in series with the cyclone-type flow mixer.  
  In view of the above, the conventional cyclone-type flow mixer requires a relatively complicated assemblage and a relatively high cost of maintenance and does not operate to produce the sewage satisfactorily mixed with the chemical additive.  
  Accordingly. an essential object of the present invention is to provide an improved flow stirrer which does not employ any movable part such as a rotary blade assembly and which can satisfactorily stir a liquid medium even through the latter flows therethrough at a relatively low speed, thereby substantially eliminating the disadvantages and inconveniences inherent in the conventional devices for a similar purpose.  
  Another object of the present invention is to provide an improved flow stirrer of the type referred to above, which can be manufactured in such a compact size that no largespace for installation is required and which is serviceable for a substantially long period of time with no trouble and with maintenance inexpensive.  
  It is a related object of the present invention to provide a flow mixer by which material to be mixed to liquid medium can be uniformly and efficiently mixed to such liquid medium by the action of positive current of the same liquid medium flowing up through the body of the mixer.  
  Another related object of the present invention is to provide a tower assembly of a plurality of vertically stacked flow mixers so that liquid medium to be disposed is sequentially mixed with different kinds of material to be added or mixed thereto at different stages.  
  According to one preferred embodiment of the present invention, there is provided a flow stirrer which comprises a substantially drum-shaped housing composed of a cylindrical hollow body and a pair of closure members secured on both ends of the cylindrical hollow body. Within the drum-shaped housing, a sleeve extends between the closure members in alignment with the longitudinal axis of the cylindrical hollow body and has a split portion communicating between the hollow of the sleeve and a space defined by the closure members between the sleeve and the cylindrical hollow body. Adjacent the split portion, a partition plate having both ends terminating in contact with the associated closure members extends between the sleeve and the cylindrical body with both edges secured to said sleeve and cylindrical body, respectively. A first one of the closure members is formed at its center with an opening communicated to the hollow of the sleeve and the other closure member is formed adjacent the periphery thereof with an opening that is communicated to a portion of the space on one side of the partition plate remote from the split portion.  
  Within the space between the sleeve and the cylindrical body, two sets of a plurality of barriers are alternately connected to the cylindrical body and the sleeve so as to radially inwardly and outwardly extend at alternate intervals, thereby forming a zig-zag shaped flow path around the sleeve.  
  Either ofthe openings in the respective closure members may serve as an inlet for liquid medium to be stirred while the other opening as an outlet.  
  The device of the above construction is particularly effective in dealing with the liquid medium that has been mixed or added with an additive prior to entering the flow stirrer. Once this liquid medium under pressure has entered the flow stirrer of the above construction through, for example, the opening leading to the hollow of the sleeve, the liquid medium flows through the split portion into the space between the cylindrical body and the sleeve. The liquid medium thus fed into the space flows towards the other opening, travelling in a substantially zig-zag manner guided by the alternately arranged barriers and finally deflected by the partition plate towards the other opening through which it is discharged.  
  During the zigzag travel of the liquid medium previously mixed with an additive, for example. powdery coagulant, the liquid medium can be severely stirred to permit particles of the added coagulant to be uniformly dispersed in the liquid medium even though the flow speed of the liquid medium passing through the stirrer is relatively low. This is possible because the liquid medium flowing in the zig-zag manner within the space between the cylindrical body and the sleeve alternately undergoes expansion and contraction, thereby creating a turbulent or eddy current each time it is expanded.  
  These and other objects and features of the present invention will become apparent from the following description taken in conjunction with preferred embodiments thereof with reference to the accompanying drawings, in which;  
  FIG. 1 is a longitudinal sectional view ofa flow stirrer according to one preferred embodiment of the present invention,  
  FIG. 2 is a cross sectional view taken along the line ll-ll in FIG. 1,  
  FIG. 3 is an exploded view ofa flow mixer according to another preferred embodiment of the present invention,  
  FIG. 4 is a longitudinal section] view of the flow mixer shown in FIG. 3,  
  FIG. Sis an elevational view of a flow mixer assembly according to a further preferred embodiment of the present invention, and  
  FIG. 6 is a longitudinal sectional view ofa portion of the flow mixer assembly of FIG. 5, showing the lowermost or first stage thereof.  
  Before the description of the present invention proceeds, it should be noted that like parts are designated by like reference numerals throughout the accompanying drawings for the sake of brevity.  
  Referring first to FIGS. 1 and 2, a flow stirrer according to the present invention, generally indicated by 10, comprises a cylindrical hollow body 11 having both ends integrally formed with radially outwardly extending annular flanges 11a and 11b. A pair of opposed closure discs 12 and 13 are respectively secured to the flanges 11a and 11b of the cylindrical body 11 by any suitable means, for example, by means of rivetting as at 140 and 14b. The cylindrical body 11 accommodates therein a sleeve 15 ofa length substantially equal to the length of said cylindrical body 11 and extending between the closure discs 12 and 13 in alignment with the longitudinal axis of said cylindrical body 11, at least one end of which is welded to either of the opposed closure discs 12 or 13. As best shown in FIG. 2, the sleeve 15 may have a sectional shape similar to the contour of a split ring and has a split portion or clearance 15a extending in a lengthwise direction of the sleeve 15. A partition plate 16 having both ends terminating at the adjacent closure discs 12 and 13 extends between the cylindrical body 11 and the sleeve 15 in a radial direc tion with both side edges respectively secured to the cylindrical body 11 and to the sleeve 15 adjacent one of the opposed edges thereof which define the clearance 15a.  
  The closure disc 12 is formed therein an opening 12a, which is, in the instance as shown, substantially segmentally shaped. The position of this opening 120 in the closure disc 12 should be selected such as to be adjacent the periphery of said disc 12 and above one side of the partition plate 16 that is remote from the clearance 150 so that liquid medium flowing from the clearance 150 or entering the opening 12a can be deflected towards the opening 12a or towards the clearance 15a, respectively, by the partition plate 16. On the other hand, the closure disc 13 is formed with an opening 13a in alignment with the longitudinal axis of the cylindrical body 11, which opening 13a communicates to the hollow of the sleeve 15.  
  Either of the openings 12a and 13a respectively formed in the opposed closure discs 12 and 13 may serve as an inlet for the liquid medium to be stirred while the other as an outlet for the same. However, for the sake of description, the opening 13a is assumed as adapted to be connected to a source of the liquid me dium through a suitable pumping device while the other opening adapted to be connected to such a reservoir as a settling or thickening tank or a container which may be selected depending on the use of the flow stirrer shown in FIGS. 1 and 2.  
  Within the space between the cylindrical body 11 and the sleeve 15, two sets of a plurality of equally spaced outer and inner barriers l7 and 18, each being ofa length substantially equal to the length of the cylindrical body and a width smaller than that of the partition plate 16, preferably, two thirds of the width of said partition plate 16, extend radially inwardly and outwardly from the cylindrical body and the sleeve 15, respectively. These barriers 17 and 18 are positioned such as to alternately inwardly and outwardly extends in a radial direction of the cylindrical body, each of either set of the barriers 17 or 18 substantially terminating in between the adjacent couple of the barriers 18 of the other set or 17. It will be seen that the angular distance between the free side edge of each of the barriers l7 and a substantially intermediate portion of any one of the adjacent couple of the barriers 18 which 10- cate on both sides of said each of the barriers 17 is greater than that between the free side edge of said any one of the adjacent couple of the barriers l8 and a substantially intermediate portion of said each of the barrier 17. This difference in angular distance substantially provides an effect similar to that available in a narrownecked orifice.  
  With the flow stirrer of the above construction, as suming that the opening 13a in the closure disc 13 is connected to a source of liquid medium to be stirred through a suitable pumping device (not shown) while the opening 12a in the closure disc 12 is connected to such a reservoir as a settling or thickening tank or any other suitable container which may be selected depending on the use of the flow stirrer of the present invention, the liquid medium under pressure flows into the hollow of the sleeve 15 through the opening 13a. The liquid medium in the hollow of the sleeve 15 then flows through the clearance 15a into a substantially circularly extending stirring chamber defined between the cylindrical body 11 and the sleeve 15 with the closure discs 12 and 13 mounted on both ends of said cylindrical body 11. Thereafter. the liquid medium within the stirring chamber flows towards the other opening 120. travelling in a substantially zig-zag manner guided by the alternately arranged barriers 17 and 18, and is finally deflected by the partition plate 16 towards the opening 12a through which it is discharged.  
  During the zigzag travel of the liquid medium within the stirring chamber, the liquid medium undergoes substantial vermiculation, that is, alternate expansion and contraction, due to the fact that a substantially circular passage for the flow of the liquid medium which constitutes the stirring chamber and which extends between the clearance a and the opening 120 varies in width by the reason as hereinbefore described. Alternate expansion and contraction of the liquid medium flowing within the stirring chamber results in formation of a turbulent or eddy current and, therefore, the liquid medium can be severely stirred even through the flow rate is relatively low.  
  It should be noted that the closure discs 12 and 13 may be of a diameter substantially equal to the inner or outer diameter of the cylindrical body 11 without being provided with the flanges 11a and 11b. In this case, the closure discs may be fillet-welded to the corresponding ends of the cylindrical body.  
  Shown in FIGS. 3 and 4 is a flow mixer, rather than a flow stirrer, because it can be used for mixing an additive to a liquid medium as the latter passes therethrough. This flow mixer shown in FIGS. 3 and 4 comprises a pair of stirring and mixing chambers, the stirring chamber thereof being of substantially the same construction as that shown in FIGS. 1 and 2. However, a slight difference resides in that a cylindrical body 11 employed in this embodiment is longer than that 11 employed in the foregoing embodiment while the closure disc 12 employed in the foregoing embodiment serves as a partition disc 12&#39; dividing the hollow of the cylindrical body 11&#39; into the stirring chamber and the mixing chamber positioned thereabove. An additional closure disc 23 is provided which is adapted to be rigidly mounted on the flange ll&#39;a of the cylindrical body 11&#39;. which is of the same construction as the closure disc 13 secured to the flange 11&#39;!) thereof.  
  Since the stirring chamber is substantially the same as that in the foregoing embodiment, reference will now be made to the mixing chamber for the sake of brevity.  
  Within the mixing chamber and above the partition disc 12&#39;, a substantially helically sloping duct 19 having a slope surface 19a is rigidly mounted on the partition disc 12&#39;. The sloping duct 19 has a flattened, closed end positioned adjacent the opening l2&#39;a in the partition disc 12&#39; and an open end positioned so as to cover the opening 12a, the slope surface 19a substantially upwardly convoluting about the longitudinal axis of the cylindrical body 11&#39; from the flattened, closed end, one side edge of which slope surface 19a is rigidly secured to the inner surface of the cylindrical body 11&#39; while the opposite side edge is equally spaced from the outer peripheral surface of a guide tube 23b downwardly extending from the closure disc 23 in alignment with the opening 23a.  
  At a substantially intermediate portion of the cylindrical body 11 and above the plane of the partition disc 12. a supply port ll&#39;c is formed which opens into a portion of the sloping duct 19 adjacent the open end thereof. A coupler rigidly secured to the cylindrical body 11&#39; in alignment with the supply port ll&#39;c is adapted to be connected to a source of fluid additive to be mixed with the liquid medium fed through the mixer.  
  During operation, the liquid medium fed to the opening l2&#39;a in the partition disc 12&#39; in the manner as hereinbefore described in connection with the embodiment of FIGS. 1 and 2 flows into the duct 19 and is then oriented towards the open end of the duct 19, since the opening 12&#39;a locates inside the duct 19 and rearwardly of the open end of said duct 19. The liquid front emerging from the open end of the duct 19 commences to e1- evate riding on the slope surface thereby forming a substantially swivelling current around and in substantially spaced relation to the tube 23b that is downwardly extending from the closure disc 23. The liquid front after having reached the inner surface of the closure disc 23 turns downwards flowing towards the partition disc 12&#39; in a direction substantially parallel to the longitudinal axis of the tube 23b and again turns backwards flowing up through the tube 23b. The liquid medium flowing up through the tube 23b is thereafter discharged to the reservoir (not shown) such as a settling or thickening tank or any other suitable container.  
  The fluid additive supplied through the coupler 20 and then fed into the mixing chamber through the port llc impinges against the flow of the liquid medium travelling from the opening l2&#39;a towards the open end of the sloping duct 19 and is uniformly mixed into the fluid medium during substantially swivelling motion of the fluid medium within the mixing chamber. It should be noted that the liquid medium flowing from the opening 12&#39;a towards the open end of the sloping duct 19 will not flow in part&#39;into the coupler 20 because the fluid additive is made to be fed under pressure greater than the pressure imposed on the flow of the liquid medium.  
  A number of the flow mixer of the construction shown in FIGS. 3 and 4 may be used in a vertically stacked arrangement as shown in FIG. 5. In this case, the closure disc 13 is preferrably provided with a downwardly extending tube 13b in alignment with the opening 13a, thereby enabling the closure disc 13 to be used as an upper closure disc, similar to the closure disc 23, for the mixer unit positioned next to and below the upper mixer unit.  
  In FIG. 5, a six-stage flow mixer assembly is shown as supported above the ground by means ofa bench structure B. While a mixer unit of the lowermost stage T is constructed as hereinafter described, the other mixer units of the second to last or uppermost stages T, to T are each constructed in substantially the same as shown in FIGS. 3 and 4. These units are preferrably vertically stacked one above another by the use of annular rubber packings each firmly held between the adjacent pair of the units.  
  The unit of the lowermost stage T, comprises a cylindrical hollow body 21 having both ends integrally formed with a pair of radially outwardly extending flanges 21a and 21b, as shown in FIG. 6, and the cylindrical body 21 so far described may be similar in shape to the cylindrical body 11 or 11&#39;. A bottom disc 22 formed with an opening as at 22a is rigidly mounted within the hollow of the cylindrical body 21 and provided with a drain tube 24 downwardly extending therefrom in alignment with the opening 220. A lower end portion of the cylindrical body 21 below the plane of the bottom disc 22 serves as a mounting leg together with the flange 21b adapted to be secured to the bench structure B by any suitable method, for example, by the use of rivets (not shown). The drain tube 24 is adapted to communicate through a valve V to any suitable location or a source of liquid medium to be processed,  
 said valve V, being adapted to open only when liquid medium remaining in the multi-stage mixer assembly is to be drained for any purpose, for example, of cleaning or repairment or of preventing any of the units from being damaged by freezing.  
  Mounted above the unit of the uppermost stage T is a cap assembly 30 having an observatory window 31 and formed with an outlet coupler 32. This cap assembly 30 may not be employed, in which case the outlet coupler 32 should be connected to the upper closure disc 23 in alignment with the opening 23a. The outlet coupler 32 is in turn communicated to a valve V leading to the atmosphere through a line L, and also to the reservoir through a line L It should be noted that when the liquid medium remaining in the mixer assembly is to be drained through the drain tube 24, the valve V should be set to complete a circuit between the outlet coupler 32 and the line L,.  
  Referring back to FIG. 6, the cylindrical body 21 of the lowermost, mixer unit T, is formed with an intake port 21c which is aligned with a coupling flange 25. The coupling flange 25 is in turn connected to the source of liquid medium S through a valve V and a pumping device P so that liquid medium to be processed can be supplied into the hollow of the cylindrical body 21 under pressure. It should be noted that the coupling flange 25 and the intake port 21c are designed such that the liquid medium fed from the source S thereof through the pumping device P flows into the cylindrical body 2] in a direction substantially parallel to the tangential direction of the cross sectional contour of the cylindrical body 2].  
  In the embodiment illustrated, the couplers 20 of the mixer units of the second, third and fifth stages T T and T are respectively connected to sources of fluid additives, for example, 5 percent lime solution, 5 per cent aluminum sulfate solution and 0.05 percent high polymer coagulant, through valves V V and V,,- and then pumping devices P P and P, The couplers 20 of the mixer units of the fourth and sixth stages T, and T are, in this instance, closed by any suitable plugs (not shown].  
  It will be seen that the liquid medium fed into the lowermost unit through the intake port 21c under pressure flows in a substantially similar manner as in the mixing chamber of the flow mixer of FIGS. 3 and 4 and then flows up through the downwardly extending tube 13b in the closure disc 13 of the unit of the next stage T The liquid front thus fed into the stirring chamber of the unit of the next stage T successively flows upwards through the other units of the subsequent stages T to T in substantially the same manner as hereinbefore described with reference to FIG. 1 and 2 and FIGS, 3 and 4 and is finally discharged to the reservoir through the outlet coupler 32.  
  From the foregoing full description of the present in vention, it has now become clear that lumps of impurities or contaminations present in the liquid medium to be disposed that are previously formed will not be destroyed because of no movable part employed. It should be noted that even though the flow rate of the liquid medium to be disposed is relatively low, for example, 75cm/sec., it can flow upwards through the multistage mixer assembly while being satisfactorily stirred and mixed with the fluid additives sequentially added thereto. Therefore, the pumping device P may have a relatively low horsepower.  
  Although the present invention has been fully described by way of example with reference to the accompanying drawings, it should be noted that various changes and modifications are apparent to those skilled in the art. By way of example, the positions of the stirring and mixing chambers in a single flow mixer shown in FIGS. 3 and 4 may be reversed with respect to each other as compared with that shown. Therefore, these changes and modifications should be construed as included within the true scope of the present invention unless otherwise they depart therefrom.  
 I claim:  
  1. A device for stirring liquid medium by the flow of the liquid medium passing therethrough under pressure, which comprises a cylindrical hollow body having both ends closed by first and second plate members, respectively, a sleeve stationarily housed within said cylindrical hollow body in alignment with the longitudinal axis of said cylindrical hollow body and having both ends terminating at the first and second plate members, said sleeve further having a clearance extending in parallel to the longitudinal axis of said sleeve, said clearance communicating between the hollow of said sleeve and a space that is defined between said sleeve and said cylindrical body, a first opening formed in said first plate member adjacent the periphery of said first plate member and communicating between said space and the outside of said device, a second opening formed in said second plate member and communicating between said hollow of said sleeve and the outside of said device, a partition wall rigidly housed within said space with both ends thereof terminating at said first and sec ond plate members, one side edge of which is secured to one of the opposite edges of said clearance and the other side edge of which partition wall is secured to the cylindrical hollow body, and means housed within said space for guiding the flow of the liquid medium, that has entered either of said first and second openings, in a substantially zig-zag manner towards the other opening and also for alternately expanding and contracting said liquid medium during the flow thereof from said either of said first and second opening towards said other opening thereby creating a turbulence required to severely stir said liquid medium passing therethrough under pressure.  
  2. A device as claimed in claim I, wherein said guiding means comprises two sets of alternately outwardly and inwardly extending barriers in a radial direction of said cylindrical hollow body, said barriers of one set secured to said cylindrical body and said barriers of the other set secured to said sleeve, each of said barriers of both sets having both ends substantially terminating at said first and second plate members.  
  3. A device as claimed in claim I, wherein said first opening serves as an outlet for the liquid medium and said second opening serves as an inlet for the same,  
  4. A device as claimed in claim 2, further comprising a cylindrical hollow extension coaxial with said cylindrical hollow body and situated on one side of and above said first plate member remote from said second plate member, said cylindrical hollow extension having one end rigidly connected to said cylindrical hollow body, a third plate member secured to the other end of said cylindrical hollow extension and having an opening formed therein at the center thereof in alignment with the longitudinal axis of said cylindrical hollow extension, a guide tube having one end secured to said third plate member in alignment with said opening in said third plate member and the other end extending into the hollow of said cylindrical hollow extension to a position adjacent said first plate member, a supply port formed in the wall of said cylindrical hollow extension at a position adjacent said first mentioned end thereof and adapted to supply therethrough a material to be mixed with the liquid medium entering said hollow of said cylindrical hollow extension through said first opening in said first plate member, and means for orienting the flow of the liquid medium, that has entered said hollow of said cylindrical hollow extension through said first opening in said first plate member, in the circumferential direction of said cylindrical hollow extension whereby the front of said liquid medium thus oriented upwardly swivel about the guide tube within the hollow of said cylindrical hollow extension and, after having reached the third plate member, flows downwards in substantially parallel to the guide tube and then flows up through said guide tube onto said opening in said third plate member.  
  5. A device as claimed in claim 4, wherein said orienting means comprises a substantially helically extending slope having one end secured to said second plate member adjacent said first opening in said first plate member and the other end situated above said first opening.  
  6. A device as claimed in claim 4, further comprising a guide tube having one end connected to said second plate member in alignment with said second opening in said second plate member, said guide tube together with said second plate member serving as said guide tube together with said first plate member when said device is vertically connected above another unit of said device.  
  7. A device as claimed in claim 4, wherein said cylindrical hollow extension is integrally formed with said cylindrical hollow body.  
  8. A floculator assembly which comprises in combination:  
 a plurality of vertically stacked floculator units, each of which except for the lowermost unit comprises a cylindrical hollow body having both ends closed by upper and lower plate members, said upper and lower plate members being formed with respective openings at the center thereof in alignment with the longitudinal axis of said cylindrical hollow body,  
 first and second guide tubes downwardly extending respectively from said upper and lower plate members in alignment with said openings in said plate members,  
 said upper plate member adapted to serve as the lower plate member for the cylindrical hollow body of either of said lowermost floculator unit and any one of the other floculator units positioned immediately below said each of said floculator units except for the lowermost floculator unit and said lower plate member adapted to serve as the upper plate member for the cylindrical hollow body of any one of said floculator units including the lowermost floculator unit,  
 a partition plate member stationarily housed within said cylindrical hollow body for dividing the hollow of said cylindrical hollow body into stirring and mixing chambers,  
 a sleeve stationarily housed within said stirring chamber in alignment with the longitudinal axis of said cylindrical hollow body and having both ends terminating at said lower plate member and said partition plate member, the hollow of said sleeve being communicated to said second guide tube, said sleeve further having a clearance extending in parallel to the longitudinal axis of said sleeve, said clearance communicating between the hollow of said sleeve and a space that is defined between said sleeveand said cylindrical body within said stirring chamber,  
 a through hole formed in said partition plate member adjacent the periphery of said partition plate member and communicating between said space and said mixing chamber,  
 a partition wall rigidly housed within said stirring chamber with both ends thereof terminating at said lower plate member and said partition plate member, respectively, one side edge of which is secured to one of the opposite edges of said clearance and the other side edge of which is secured to the cylindrical hollow body,  
 means housed within said space for guiding the flow of liquid medium, that has entered said space through the hollow of said sleeve via said guide tube in said lower plate member, in a substantially zig-zag manner towards the through hole in said partition plate member and also for alternately expanding and contracting said liquid medium during the flow thereof from said hollow of said sleeve towards said through hole in said partition plate member through said clearance thereby creating a turbulence required to severly stir said liquid medium passing therethrough under pressure,  
 a supply port formed in the wall of said cylindrical hollow body and opening into said mixing chamber at a position immediately above said partition plate member, said supply port being adapted to supply therethrough a material to be mixed with the liquid medium entering said mixing chamber through said through hole in said partition plate member, and  
 means for orienting the flow of the liquid medium,  
 that has entered said mixing chamber, in the circumferential direction of said cylindrical hollow body whereby the front of said liquid medium thus oriented upwardly swivels about the first guide tube in said upper plate member within said mixing chamber and, after having reached the upper plate member, flows downwards in substantially parallel to said first guide tube and then flows up through said first guide tube onto said opening in said upper plate member,  
 the opening in the upper plate member of the cylindrical hollow body for the uppermost floculator unit being adapted to be connected to a suitable reservoir where said liquid medius is disposed,  
 the lowermost floculator unit comprising a cylindrical hollow receptacle having a lower end closed by a closure plate and an upper end adapted to be closed by the lower plate member for the cylindrical body of the floculator unit positioned immediately thereabove with the guide tube extending into the hollow of said cylindrical receptacle and substantially terminating adjacent said closure plate and an inlet port communicating between a source of the liquid medium to be disposed and the hollow of said cylindrical receptacle through a suitable pumping means, drain means communicating between the hollow of said cylindrical hollow receptacle and a suitable location for discharging a portion of the liquid medium remaining within said floculator assembly, and means for connecting the floculator units in a substantially vertically stacked arrangement.  
 9. An assembly as claimed in claim 8, wherein said guiding means comprises two sets of alternately outwardly and inwardly extending barriers in a radial di-