DEVICE FOR INJECTING FLUID INTO A LIQUID, METHOD FOR CLEANING SAID DEVICE, AND EFFLUENT TREATMENT INSTALLATION

Abstract

A device for injecting a secondary fluid into a main liquid, includes a first part able to convey a secondary fluid in a substantially longitudinal direction; a second part able to eject the secondary fluid from the device, so as to inject the secondary fluid into a main liquid, the second part being in fluidic connection with the first part and comprising an open end; the device comprising at least a first position, referred to as the low position, and a second position, referred to as the high position, and further comprising a positioning means able to position the device in a position comprised between the first position and the second position.

Claims

1. A device for injecting a secondary fluid (F) into a main liquid (L), comprising: a first part able to convey the secondary fluid (F) in a substantially longitudinal direction (Z); a second part able to eject the secondary fluid (F) from the device, so as to inject said secondary fluid into a main liquid (L), said second part being in fluidic connection with the first part and comprising an open end; the device comprising at least a first position (Z1), referred to as the low position, and a second position (Z2), referred to as the high position, and further comprising a positioning means able to position the device in a position comprised between the first position (Z1) and the second position (Z2).

2. The device as claimed in claim 1, the first and second positions being defined with respect to a distance (D) between the open end of the second part and a reference surface situated in a transverse plane, a minimum distance (D.sub.min) corresponding to the first position (Z.sub.1) and a maximum distance (D.sub.max) corresponding to the second position (Z.sub.2).

3. The device as claimed in claim 2, the maximum distance (D.sub.max) being comprised between 3 and 6 cm.

4. The device (2) as claimed in claim 1, the second part being configured in such a way as to apply to the secondary fluid (F) a deflection that is transverse, essentially radial, to the longitudinal direction (Z).

5. The device as claimed in claim 4, the second part having a conical shape widening at its open end.

6. The device as claimed in claim 5, the open end of the second part having a first undulating profile in the form of a series of peaks and troughs oriented substantially in the longitudinal direction.

7. The device as claimed in claim 6, the first undulating profile being a substantially sinusoidal profile defined by a first period (T) and a first amplitude (A).

8. The device as claimed in claim 1, the device comprising a flexible part that is flexible in the longitudinal direction (Z).

9. The device as claimed in claim 1, one of the preceding claims, the first part and the second part forming a single piece.

10. The device as claimed in claim 1, the first part and the second part being formed by two pieces connected together in a fluidtight manner.

11. The device as claimed in claim 1, further comprising a measurement means for measuring the pressure (P) inside said device.

12. The device as claimed in claim 2, further comprising a base having a first surface forming the reference surface and situated facing the second part.

13. The device as claimed in claim 12, the open end of the second part being configured in such a way as to have at least one point of contact with the base when the device is in the first position (Z1), while still allowing the secondary fluid (F) out.

14. The device as claimed in claim 12, the first surface of the base having a second undulating profile in the form of a series of peaks and troughs oriented substantially in the longitudinal direction.

15. The device as claimed in claim 14, the open end of the second part having a first undulating profile in the form of a series of peaks and troughs oriented substantially in the longitudinal direction, the second undulating profile being configured to collaborate with the first undulating profile in such a way as to position the second part with respect to the base and to block transverse movements of said second part with respect to said base.

16. The device as claimed in claim 11, the first undulating profile being a substantially sinusoidal profile defined by a first period (T) and a first amplitude (A), the second undulating profile being a substantially sinusoidal profile defined by a second period (T′) and a second amplitude (A′), the second period (T′) being substantially equal to the first period (T) and the second amplitude (A′) being less than the first amplitude (A).

17. The device as claimed in claim 12, the base comprising a centering means for centering the second part and situated facing said second part.

18. The device as claimed in claim 12, further comprising a support situated below the base so that said base is situated between the support and the second part.

19. A method for cleaning an injection device as claimed in claim 1, comprising the following steps: a first step of positioning the device in a third position (Z3) situated above the first position (Z1) and below or even with the second position (Z2); a second step of maintaining the third position (Z3) for a given duration (t); a third step of positioning the device in a fourth position (Z4) situated below the third position (Z3) and above or even with the first position (Z1); the fluid (F) being injected continuously into the device throughout at least all of said steps.

20. The method as claimed in claim 19, the injection device comprising a measurement means for measuring the pressure (P), the positioning first step being initiated when the measured pressure (P) exceeds a maximum pressure threshold (Pmax), and the maintaining second step being carried out until a minimum pressure threshold (Pmin) is reached.

21. An effluent treatment installation comprising an injection device as claimed in claim 1.

22. The effluent treatment installation comprising an injection device as claimed in claim 2, and a treatment reactor or tank, the reference surface being formed by a surface of said reactor or of said tank.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0092] Further features and advantages of the invention will become apparent from the following description given by way of nonlimiting illustration with reference to the attached figures among which:

[0093] FIG. 1 comprises two figures FIG. 1A and FIG. 1B illustrating a radial diffuser of the prior art;

[0094] FIG. 2 illustrates an example of an injection device according to the invention;

[0095] FIG. 3 illustrates a detail of the example of the injection device of FIG. 2;

[0096] FIG. 4 illustrates a variant of the example of FIG. 3;

[0097] FIG. 5 comprises four figures FIG. 5A, FIG. 5B, FIG. 5C, FIG. 5D illustrating the example of the device of FIG. 3 in the two, low and high, positions;

[0098] FIG. 6 illustrates an example of the use of the injection device according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0099] FIGS. 1A and 1B have already been described in the “Prior art” section of the present description.

[0100] FIGS. 2 to 5D illustrate an example of an injection device.

[0101] The injection device 2 is designed to be incorporated into a reactor 1 comprising a floor 11, a roof 12 and walls (the walls are not depicted). The reactor further contains a head 13 of main liquid L and a gas ceiling 14 above said main liquid. As an alternative to a reactor, this may be a tank.

[0102] Alternatively, the injection device may be situated upstream of a reactor or of a tank.

[0103] The injection device comprises a first part 21 able to convey the secondary fluid F in a substantially longitudinal direction Z. In the example depicted, the first part 21 is part of a pipe tube 20.

[0104] The pipe tube 20 may be connected at its upper end (the end not immersed in the main liquid L) to a pressure measuring device 3, for example, although not exclusively, a manometer.

[0105] Furthermore, the first part 21 may comprise a flexible portion 23 that is flexible in the longitudinal direction Z. Said flexible portion may be a bellows, notably a metal bellows.

[0106] The flexible portion 23 depicted is connected to a positioning means 24 which, when actuated, is able to act on the length of said flexible portion, allowing the injection device to be moved by a few centimeters along the longitudinal axis Z. The positioning means is described later on, in connection with FIGS. 5A to 5D.

[0107] The second part 22 able to eject the secondary fluid F forms just one piece with the first part 21. In other words, the tube 20 is a single piece comprising a first part able to convey the secondary fluid F and a second part able to eject said secondary fluid.

[0108] According to the example depicted, the second part is a cone or “ejection cone” 22, said cone being able to be immersed in the main liquid L. In other words, the pipe tube 20 ends in a conical shape. Such a conical shape allows the secondary fluid to be deflected notably so as to force it to exit radially. As an alternative to a conical shape, any other flared shape able to impart a radial direction on the secondary fluid as it exits the tube may be envisioned, such as, for example, a pyramid shape, an ellipsoidal shape, etc.

[0109] According to the example depicted, the ejection cone 22 ends with a first undulating profile 221 in the form of a series of peaks 221a and of troughs 221b oriented substantially in the longitudinal direction Z.

[0110] One example of a first undulating profile 221 is illustrated in greater detail in FIG. 3. The ejection cone ends with a sinusoidal first undulating profile. The sinusoidal first profile is defined by a first period P and an amplitude A. The peak-to-peak amplitude B, which is the amplitude between a peak 221a and a trough 221b which are adjacent, is equal to twice the amplitude A. The minimum ejection section S.sub.min for the ejection of the secondary fluid F (corresponding to the ejection section when the device is in the low position) is equal to the sum of N areas delimited by the sinusoidal curve (profile of the cone) connecting two adjacent troughs and by the straight line connecting said adjacent troughs, N being the number of troughs (or of peaks).

[0111] A sinusoidal first undulating profile may for example be defined:

by a D/N ratio comprised between 10 and 100, preferably between 20 and 70; D being the outside diameter of the cone (in millimeters),
by a peak-to-peak amplitude B comprised between 2 and 20 mm, preferably between 2 and 10 mm.

[0112] As an alternative to a profile of sinusoidal type, the profile may be triangular, square or any other suitable shape. However, the advantage of a sinusoidal profile is its ease of use and of manufacture. Another advantage is that it avoids a risk of additional depositing of solid particles in the device.

[0113] According to the example depicted, the ejection cone 22 is situated facing a base 4, illustrated in the form of a plate.

[0114] The plate depicted comprises on its first surface 4a, or surface facing the ejection cone, a projection 41 of frustoconical shape. Said projection 41 is oriented along the longitudinal axis Z and is directed toward the inside of the ejection cone 22. That allows said ejection cone to be centered and held in place on the longitudinal axis Z, without the need to add a specific fixing and/or retaining and/or centering means to the device.

[0115] When the ejection cone is in contact with the plate 4, only the trough parts 221b of the undulating profile 221 are in contact with said plate. In that case, the total section for outlet of the secondary fluid F corresponds to the minimum ejection section S.sub.min for the ejection of said secondary fluid, namely to the sum of the N areas delimited by the sinusoidal curve (undulating profile of the cone) connecting two adjacent troughs and by the straight line (profile of the plate) connecting said adjacent troughs.

[0116] The plate 4 may advantageously be fixed to a support 5, for example a block. Said support may be positioned on the floor 11 of the reactor 1, so as to raise the secondary fluid F up off said floor. That notably limits the abrading of said floor over the course of time.

[0117] The plate 4 is preferably, but not exclusively, made of steel. The support 5 is preferably, but not exclusively, made of concrete.

[0118] If the reactor needs to be fluidtight and the gaseous ceiling needs to be contained, then a sealing means 6, for example a seal, may be situated between the tube 20 and the roof 12 of the reactor. As a preference, the seal is a hydraulic seal. As a preference, the seal is configured to provide sealing between the injection device and the reactor under low pressure (typically of the order of 0.02 to 0.03 bar, for example, although not exclusively) while allowing the injection device some mobility along the longitudinal axis. The seal thus prevents gas from escaping into the atmosphere.

[0119] FIG. 4 depicts a variant form of plate 4 comprising, on its first surface 4a (the surface facing the ejection cone 22), a second undulating profile 42 of substantially sinusoidal type of which the second period P′ is substantially equal to the first period P (period of the undulating profile of the ejection cone) and of which the amplitude A′ is less than the first amplitude A (amplitude of the undulating profile of the ejection cone).

[0120] That allows improved positioning of the ejection cone and limits the potential lateral movements of said cone with respect to the plate and also notably limits the impact of any potential vibrations of the injection device. It also allows a projection 41 to be dispensed with.

[0121] In that case, the minimum ejection section S′.sub.min for the ejection of the secondary fluid (and which corresponds to the ejection section when the device is in the low position) is equal to the sum of the N areas delimited by the sinusoidal curve (undulating profile of the cone) connecting two adjacent troughs and by the substantially sinusoidal curve (undulating profile of the plate) connecting said adjacent troughs. The surface area S′.sub.min is less than the surface area S.sub.min.

[0122] The undulating peripheral profile of the ejection cone in a simple way ensures a minimum passage section S.sub.min or S′.sub.min for the ejection of the secondary fluid, whether the injection device is in the high position or in the low position, while at the same time advantageously dispensing with the bolts and spacers fixing of the diffusion devices of the prior art. That avoids zones in which solids, for example fibrous waste, can become caught and/or zones in which such solids can accumulate.

[0123] Furthermore, the device of the invention comprises means to allow the ejection cone to move along the longitudinal axis relative to the base. That allows the distance between the ejection cone and the base to be modified, and this has the effect of modifying the passage section for the secondary fluid.

[0124] As a preference, the ejection cone may move away from the base by a distance varying between 3 cm and 6 cm, so as to allow the device to be cleaned while at the same time maintaining sufficient secondary-fluid injection pressure for said fluid to be able to be injected into the main liquid sufficiently effectively.

[0125] FIGS. 5A to 5D illustrate two positions of the injection device. FIGS. 5A and 5B illustrate the positioning means (FIG. 5A) and the positioning of the ejection cone (FIG. 5B) in the low position or the position referred to as the “planted” position, which is a nominal position of the device in operation. FIGS. 5C and 5D illustrate the positioning means (FIG. 5C) and the positioning of the ejection cone (FIG. 5D) in the high position or the position referred to as the “raised” position, which is a position for cleaning (or unclogging) the device.

[0126] The positioning means 24 is configured to act on the flexible portion 23 of the tube, so that the ejection cone 22 can be raised or lowered without the need to stop the circulation of the secondary fluid in the device and the ejection of said fluid into the main liquid. Thus, uninterrupted circulation of the secondary fluid enables the injection device to be cleaned, and allows the velocity at which said fluid is ejected not to be reduced dramatically (or even reduced to nothing as may occur in the event of clogging). This in particular means that the sludge and fibrous waste that may accumulate in the device, notably in the injection cone, can be eliminated, thus avoiding clogging.

[0127] The positioning means 24 depicted is a system of lever type which comprises a fixed bar 242 extending substantially in the longitudinal direction and connected to the roof 12 of the reactor, and a lever arm 241 connected to said fixed bar at a pivot point 243 and to the flexible portion 23 at a first end 241a. To raise the device, all that is required is for the lever arm 241 to be actuated by pressing down on the second end 241b of said arm. That allows the flexible portion 23 to be compressed so as to raise the pipe tube 20 and therefore the ejection cone 22. The longitudinal movement of the cone corresponds to the compression of the flexible portion.

[0128] The longitudinal movement of the device of the invention is therefore very easy to achieve. As a result, the cleaning operations are very easy to perform, and can be carried out without interrupting the effluent treatment operations. This can be done automatically, for example by connecting the second end of the lever arm to a programmed controller.

[0129] As an alternative to this system, another system of lever type may be envisioned or else another positioning means performing the same function, for example a magnetic system or a motorized (electrically, pneumatically, etc. motorized), or else simply a manual, system.

[0130] The positioning means may act on the first part or on the second part of the injection device or on both parts at once.

[0131] According to one embodiment, a method for cleaning the injection device may be initiated (manually and/or automatically) at regular intervals, notably as a preventive measure. For example, provision may be made for a cleaning method to be performed each day of use of the device, or weekly. The frequency of cleaning may be adapted to suit the parameters of use of the device and/or the quality of the effluents being treated.

[0132] According to an alternative or complementary embodiment, a method for cleaning the injection device may be initiated (manually and/or automatically) as a curative measure.

[0133] Whether performed as a preventive measure or as a curative measure, a cleaning method may be initiated as a function of the pressure in said injection device, for example when the pressure measured in said device is above a maximum pressure threshold defined by the operator. In that case, the injection device comprises a pressure measuring means, for example, although not exclusively, a manometer.

[0134] The injection device of the invention can be used for the treatment of effluents, typically in a treatment reactor or tank, more generally in any effluent treatment installation. The injection device may also be used outside, for example upstream of a reactor or of a tank.

[0135] The injection device may be used:

for dissolving and/or diffusing a gas (secondary fluid) into a main liquid, and/or
mixing a liquid (secondary fluid) into a main liquid, and/or
dissolving and/or diffusing a gas/liquid mixture (secondary fluid) into a main liquid.

[0136] Furthermore, the secondary fluid may be laden with solid particles.

[0137] The gas may be air, oxygen, ozonized or chlorinated gases, for example chlorine, chlorine dioxide or else ozone, etc.

[0138] The main liquid may be an effluent that is to be treated, for example an aqueous effluent.

[0139] The secondary fluid may comprise a mixed liquor of biological sludge.

[0140] FIG. 6 illustrates an example of a use of the injection device comprising a tube 20 and a cone 22 at the end of the tube and which allows an ozonized gas to be dissolved by diffusion into a biological mixed liquor by way of functional liquid, the mixed-liquor/gas mixture being the secondary fluid which is then mixed with the effluent that is to be treated (main liquid L) at the outlet of the device for injection into the reactor 1. The injection device rests on a base 4 at the bottom of the reactor.

[0141] The injection device comprises a mixer 7 connected to a functional-liquid inlet 8 and to a gas inlet 9.

[0142] The gas flow rate is, for example, 25 kg O2/O3.Math.h.sup.−1 and the liquor flow rate is, for example, 25 m3/h. The secondary fluid thus exhibits a gas:mixed-liquor ratio of 1 kg gas/m.sup.3 liquid.

[0143] The biological mixed liquor may be characterized by:

an SM concentration comprised between 1 and 15 g/L, for example of 3.1 g/L; and/or
a volatile material content comprised between 50 and 95%, for example 77%; and/or
a fibrous waste concentration in excess of 20 mg/L, for example 138 mg/L, and/or
the presence of sand, notably microsand, for example microsand of which 90% has a particle size of below 0.2 mm.

[0144] Thus, the functional fluid may be particularly concentrated in solid matter, have a clogging capability and may also have a degree of abrasiveness.

[0145] By way of nonlimiting illustration, the device illustrated in FIG. 6 may notably have the following features:

The length of the pipe tube 20 is 5 m and its inside diameter is 100 mm (DN 100).
The tube is immersed in a reactor under 4.5 meters of main liquid L and a gas ceiling of 50 cm.
The diameter D of the ejection cone 22 is 25 cm.
The number of peaks (or number of undulations) N of the profile of the cone is 8.
The ratio D (mm) to N is thus 31.25.
The peak-to-peak amplitude B is 2.5 mm.
The base 4 has a flat profile.

[0146] This configuration of the cone yields a passage section of 9.8×10.sup.−4 m.sup.2 and an ejection velocity of 9.6 m/s when the device is in the low position.

[0147] It is evident from all of the foregoing that the injection device according to the invention can be used with mediums laden with solid matter (sludge, suspended matter, fibrous waste, etc.), such as typically a biological mixed liquor. For example, the suspended matter concentration may be in excess of 1 g/L. The injection device according to the invention may also be used in mediums laden with abrasive matter such as sand and/or silt.

[0148] The injection device also offers the following advantages:

ease of manufacture (absence of welds which are difficult to perform and therefore potentially more sensitive to corrosion);
ease of installation in an existing reactor or tank;
ease of fitting and of removal (no bolts or spacers);
ease of use;
robustness, notably with the technical and energy performance of the device being maintained;
significant reduction in the risk of an accumulation of solids (sludge, fibrous waste, etc.) in the device and therefore a reduction in the risk of the device becoming clogged;
reduction in the risk of abrasion and of aging of the device;
the capacity to carry out maintenance operations (cleaning, unclogging, etc.):
without interrupting the operation of the device, of the reactor or of the tank and more widely of the treatment installation,
manually or automatically,
as a curative and/or preventive measure.