Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
  • B01F25/50—Circulation mixers, e.g. wherein at least part of the mixture is discharged from and reintroduced into a receptacle
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
  • B01F23/20—Mixing gases with liquids
  • B01F23/23—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids
  • B01F23/234—Surface aerating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
  • B01F23/20—Mixing gases with liquids
  • B01F23/23—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids
  • B01F23/234—Surface aerating
  • B01F23/2341—Surface aerating by cascading, spraying or projecting a liquid into a gaseous atmosphere
  • B01F23/23413—Surface aerating by cascading, spraying or projecting a liquid into a gaseous atmosphere using nozzles for projecting the liquid into the gas atmosphere
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
  • B01F25/20—Jet mixers, i.e. mixers using high-speed fluid streams
  • B01F25/21—Jet mixers, i.e. mixers using high-speed fluid streams with submerged injectors, e.g. nozzles, for injecting high-pressure jets into a large volume or into mixing chambers

Definitions

• the invention relates to a device for mixing the contents of a tank.
• a bubble elevator uses a device already used for this and commonly used in particular in the nuclear industry: it is called a bubble elevator and consists of a generally vertical tube, open at its ends and which also includes an inlet nozzle for at an intermediate height. The lower end is always immersed in the liquid from the tank and corresponds to a liquid inlet opening, while the upper end can be emerged or submerged according to the circumstances and corresponds to a mixture ejection opening.
• air and liquid in fact, the air introduced into the tube by the nozzle rises, carrying with it the liquid occupying the tube, until it leaves by the upper end, and the ejected liquid is replaced by liquid from the tank entering through the lower opening.
• Bubbles elevators do not require the use of moving mechanical parts and thus can be used 'even in corrosive liquids; they are very effective in stirring and homogenizing the liquid in the tanks, in particular in resuspending the deposits accumulated at the bottom of the tank.
• the efficiency of a bubble elevator can be defined as the quotient of the flow of liquid entrained by the flow of air supplied. We see that it is very variable and strongly depends on the rate of submergence, either of the ratio between the height separating the air connection from the level of the liquid in the tank and the invariable height between the air connection and the top of the elevator; the first of these heights actually corresponds to the difference in level between the air intake and the free surface of the liquid.
• the subject of the invention is an improved bubble elevator which offers both good efficiency and the possibility of auxiliary operation in sparsely filled tanks. It can replace several ordinary elevators.
• This bubble elevator comprises an open tube at a lower liquid inlet end, at an upper end for ejecting a gas and liquid mixture and at a gas injection nozzle at a height intermediate between the ends, and it turns distinguishes in that the tube also comprises at least one additional opening at an intermediate height between the upper end and the air injection nozzle. This new opening can be used to suck up an additional flow of liquid in certain circumstances or to eject the mixture on the contrary.
• a tube is generally connected to this opening.
• FIG. 1 represents a bubble elevator according to the invention
• FIGS. 2a to 2d illustrate several operating modes which can be distinguished
• the bubble elevator of FIG. 1 is shown housed in a tank 1 and comprises a main tube 2 open at its lower end 3 and at its upper end 4 where, as usual, it is bent in the shape of a stick to reject the mixture of lifting gas and liquid driven horizontally or even downwards.
• An intermediate opening corresponding to an air connection 5 is made at a low height from the lower end 3; a compressed air line 6 is connected to it which supplies the mixing gas.
• the essential element of the invention consists of an additional opening 7 of the main tube 2, located between the tap 5 and the upper end 4 and to which a connection tube 8 can be connected which extends from there horizontally or towards the bottom, and opens in the tank 1 below the upper end 4.
• connection tube 8 lends itself as well to the suction of the liquid from the tank as to the ejection of a mixture. It is good to mention beforehand certain geometric characteristics of the elevator and to explain their interest. This is how the main tube widens upwards, passing from a diameter D1 on the side of the lower end 3 to a larger diameter D2 on the side of the upper end 4. The variation in diameter is localized. a little below the connection opening 7 and it is abrupt, but correct operation would be obtained with a gradual variation in diameter over a small height of the main tube 2.
• connection opening 7 • are produced, and the connection opening 7 must be as small as possible, perhaps a few centimeters; the suction effect would be reduced or compromised if it was too large.
• additional tests, carried out with a view to optimizing and reducing the value of the difference in level b between the lower end 3 and the opening of the air nozzle 5, have shown that the empirical values recommended in the devices of the prior art, situated in a range of values between 15 and 25 cm, in order to avoid any risk of exhaust of air downwards through the lower end 3, which would reduce the lift performance, could be reduced significantly.
• the difference in height b a value of approximately 5 cm for a main tube 2, without observing air exhaust even by increasing the injection rate by the nozzle 5 until it triples.
• This possibility of reducing the difference in level b is beneficial since it increases the rate of submergence of the elevator, all other things being equal, and therefore the extent of its operation in sparsely filled tanks, since the rate of submergence corresponding to the cut of operation remains 1/3. Even when operation is possible with a high air tapping, lowering it increases the efficiency of the elevator.
• the diameter D3 of the connection tube 8, its angle of inclination and its length are determined empirically. The diameter D3 must be smaller than the diameter D2, and the length shorter than that of the lower part (of diameter Dl) of the main tube 2.
• FIG. 2a illustrates a situation where the tank 1 • is almost empty but where a homogenization of its content is still sought.
• the air is supplied at the desired flow rate and it drives the liquid present at the bottom of the tube 2 to the connection opening 7 before discharging it through the connection tube 8: an "first stage” operation is therefore obtained.
• the elevator which only concerns its lower part, while the rest, between the opening of connection 7 and the upper end 4, consists of a "second stage” which remains entirely empty for this operating mode except for an air leakage rate, since its submergence is too low. If the tank fills, we can arrive at the state of Figure 2b where the liquid level extends to the connection opening 7: this operation remains roughly the same as before, all the mixture of air and liquid passing through the connection tube 8, except that the mixture is discharged directly into the liquid.
• FIG. 3 shows that the concept of intermediate orifice can be generalized to a bubble elevator with more than two ejection stages: the elevator which is illustrated therein thus has a second intermediate orifice 17 above the first (referenced by 7 as in the previous example), and a second connection tube 18 is connected to it.
• the tube 2 then comprises three sections, of diameters D1, D2 and D4, which are connected 7 and 17 with abrupt or progressive variations in diameter as before.
• the mixture of air and liquid leaves the elevator 7 and 17 or through the upper end 4 of the tube 2, or more of these places at the same time according to the submergence and the air flow rate, as previously.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Mixers With Rotating Receptacles And Mixers With Vibration Mechanisms (AREA)
• Infusion, Injection, And Reservoir Apparatuses (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=9504300

Family Applications (1)

Country Status (7)

Families Citing this family (17)

Family Cites Families (14)

• 1997
  • 1997-02-28 FR FR9702427A patent/FR2760197B1/fr not_active Expired - Lifetime
• 1998
  • 1998-02-24 DE DE69806906T patent/DE69806906T2/de not_active Expired - Lifetime
  • 1998-02-24 KR KR10-1999-7007860A patent/KR100501917B1/ko not_active Expired - Fee Related
  • 1998-02-24 EP EP98910820A patent/EP0963243B1/de not_active Expired - Lifetime
  • 1998-02-24 WO PCT/FR1998/000359 patent/WO1998037956A1/fr not_active Ceased
  • 1998-02-24 US US09/355,618 patent/US6237898B1/en not_active Expired - Lifetime
  • 1998-02-24 JP JP53736998A patent/JP3727072B2/ja not_active Expired - Fee Related

Non-Patent Citations (1)

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