GASIFICATION DEVICE

Abstract

A gasification device for gasification of a liquid medium with a gas supply, a control unit, a gas modulation unit and a bubble diffuser. The gas supply supplies a gas to the control unit, the gas modulation unit and the bubble diffuser. The control unit controls the gas volume flow or the pressure of the gas supplied to the gas modulation unit and to supply it to the gas modulation unit with a constant gas volume flow and/or a constant gas pressure. The gas modulation unit varies the gas volume flow and/or the pressure and supplies it to the liquid medium via the bubble diffuser provided with at least one opening, so that at least one bubble is formed at the opening of the bubble diffuser in the liquid medium.

Claims

1-14. (canceled)

15. A gasification device for the gasification of a liquid medium with a gas supply, a control unit, a gas modulation unit and a bubble diffuser, wherein the gas supply is configured to supply a gas to the control unit, the gas modulation unit and the bubble diffuser, the control unit is configured to control the gas volume flow or the pressure of the gas supplied to the gas modulation unit and to supply it to the gas modulation unit in such a way that the gas is supplied to the gas modulation unit at a constant gas volume flow and/or a constant gas pressure, and the gas modulation unit is configured to vary the gas volume flow and/or the pressure and to supply it to the liquid medium via the bubble diffuser provided with at least one opening, so that at least one bubble is formed at the opening of the bubble diffuser in the liquid medium.

16. The gasification device according to claim 15, wherein the gas modulation unit has at least one electrically controllable actuator that is at least one electro-acoustic transducer and/or at least one electro-acoustic actuator.

17. The gasification device according to claim 15, wherein the gas modulation unit and the bubble diffuser are integrally designed.

18. The gasification device according to claim 15, wherein the bubble diffuser has a plurality of openings at each of which at least one electrically controllable actuator, which is an electro-acoustic transducer and/or an electro-acoustic actuator, is arranged for forming different bubble patterns.

19. The gasification device according to claim 15, wherein an acoustic damping unit is arranged in the bubble diffuser, which is designed to prevent back reflections.

20. The gasification device according to claim 15, wherein the control unit is configured to direct the gas to the gas modulation unit at a gas pressure which is up to 20 percent lower than a critical pressure for bubble generation for the respective liquid medium.

21. The gasification device according to claim 15, wherein the gas modulation unit has a signal generator or is connected to a signal generator which is designed to apply periodic modulations of adjustable amplitude and frequency to the gas volume flow or the gas pressure through the gas modulation unit.

22. The gasification device according to claim 21, wherein the modulations are harmonic.

23. The gasification device according to claim 21, wherein a respective period of the modulation comprises a first time proportion with a pressure above a critical pressure for bubble generation for the respective liquid medium and a subsequent second time proportion with a pressure below the critical pressure, wherein: a) the time proportions are different from each other; and/or b) the amounts of the differences of the amplitudes of each time proportion at the critical pressure are different from each other; and/or c) the integrals of the pressure over the duration of the time proportions are different from each other.

24. The gasification device according to option b) of claim 23, wherein the amount of the difference between the amplitude of the first time proportion and the critical pressure is greater than the amount of the difference between the amplitude of the second time proportion and the critical pressure.

25. The gasification device according to option c) of claim 23, wherein the integral of the pressure over time within the first time proportion is greater than the integral of the pressure over time within the second time proportion.

26. A gasification tank including a gasification device according to claim 15.

27. A method for generating bubbles in a liquid medium, in which a gas is directed through the gas supply, the control unit, the gas modulation unit and the bubble diffuser in gasification tank filled with the liquid medium by the gasification device arranged below a surface of the liquid medium according to claim 15, the control unit controlling the gas volume flow and/or the pressure of the gas supplied in such a way that the gas is supplied to the gas modulation unit with a constant gas volume flow and/or a constant gas pressure, wherein the gas modulation unit provides the gas with a gas volume flow modulation and/or a gas pressure modulation and supplies it to the bubble diffuser provided with at least one opening, so that at least one bubble is formed at the opening of the bubble diffuser and is supplied to the liquid medium.

28. Use of a gasification device for the gasification of a liquid medium with a gas supply, a control unit, a gas modulation unit and a bubble diffuser, wherein the gas supply is configured to supply a gas to the control unit, the gas modulation unit and the bubble diffuser, the control unit is configured to control the gas volume flow or the pressure of the gas supplied to the gas modulation unit and to supply it to the gas modulation unit in such a way that the gas is supplied to the gas modulation unit at a constant gas volume flow and/or a constant gas pressure, and the gas modulation unit is configured to vary the gas volume flow and/or the pressure and to supply it to the liquid medium via the bubble diffuser provided with at least one opening, so that at least one bubble is formed at the opening of the bubble diffuser in the liquid medium wherein the gas is directed through the gas supply, the control unit, the gas modulation unit and the bubble diffuser in a gasification tank filled with the liquid medium by the gasification device arranged below a surface of the liquid medium, the control unit controlling the gas volume flow and/or the pressure of the gas supplied in such a way that the gas is supplied to the gas modulation unit with a constant gas volume flow and/or a constant gas pressure, wherein the gas modulation unit provides the gas with a gas volume flow modulation and/or a gas pressure modulation and supplies it to the bubble diffuser provided with at least one opening, so that at least one bubble is formed at the opening of the bubble diffuser and is supplied to the liquid medium for a waste water treatment process comprising the introduction of air or oxygen into an activated sludge tank or for the introduction of ozone into a tank for trace elimination, for supplying oxygen in aquaculture or fish farming, for cleaning membrane filters, for flotation in the extraction of raw materials in mining and in mining recycling, for reducing noise emissions in off-shore work by forming at least one bubble curtain, for dispensing medication or for mixing and mass transfer in chemical processes.

Description

[0052] FIG. 1 shows a schematic side view of a gasification device or bubble generation device, in which a gas to be used for bubble generation is supplied from a gas source, not shown in FIG. 1 for reasons of clarity, via a gas supply 1, which can also be referred to as a gas supply device. The gas supply 1 can be opened and closed via a valve 2. The control unit 3 controls a gas volume flow or gas flow and/or a gas pressure in such a way that a gas modulation unit 4 is supplied with a constant gas volume flow or a constant gas pressure by the control unit 3 via the tubular gas supply 1. However, if the gas volume flow is kept constant, typically only one bubble formation frequency can be controlled, and with a constant gas pressure, the bubble size can also be controlled. The gas modulation unit 4 provides the gas with gas pressure modulation or gas volume flow modulation, i.e. varies the gas pressure as the pressure of the gas and/or the gas volume flow, and the gas is fed from the gas modulation unit 4 to a bubble diffuser 5 via the gas supply line 1, which is designated and continued after the gas modulation unit 4 in this embodiment example as gas supply line 15. In the exemplary embodiment example shown in FIG. 1, the bubble diffuser 5 is plate-shaped and has a circular surface in which several openings are created. Several bubbles 6 then form at the openings and are released into a liquid. In the exemplary embodiment shown, the gas modulation unit 4 and the bubble diffuser 5 are designed as two separate components, i.e. two spatially spaced components that are connected to each other via the gas supply 1. The modulations are damped by a damping unit 14, which is arranged at the end of the gas supply line 15 and prevents acoustic back reflections in the direction of the gas modulation unit 4.

[0053] In FIG. 2, a view corresponding to FIG. 1 shows an exemplary embodiment in which the gas modulation unit 4 and the bubble diffuser 5 are integrally designed, i.e. arranged within a common housing. Recurring features are marked with identical reference symbols in this figure and in the following figures. In addition, a gasification tank 16 is now also shown, which is open on one side facing away from the gasification device and is filled with a liquid 8 or a substance in its liquid phase. The gasification device is arranged below the liquid level, i.e. below the liquid surface, whereby in the illustrated exemplary embodiment only the gas modulation unit 4 and the bubble diffuser 5 designed integrally therewith are arranged inside the gasification tank 16, whereas the valve 2 and the control unit 3 are arranged outside the gasification tank 16. In further exemplary embodiments, however, the control unit 3 and the valve 2 can of course also be arranged inside the gasification tank 16 and only the gas source usually remains outside.

[0054] In the exemplary embodiment shown in FIG. 2, the gas modulation unit 4 is equipped with an electro-acoustic actuator 9, which extends over the entire length of the gas modulation unit 4 below the openings 7 and is housed in a gas-tight closed housing except for the gas supply 1 and the openings 7. This actuator 9 generates gas pressure fluctuations that lead to the formation of bubbles at the openings 7.

[0055] Similarly, FIG. 4 shows an exemplary embodiment in a view corresponding to FIG. 3, in which several openings 7 are arranged next to each other, on each of which a bubble 6 is formed. A separate electro-acoustic actuator 9 is arranged below each of the openings 7, whereby the electro-acoustic actuators 9 can be controlled independently of one another as modulators. For example, a computer can be used to control the gas modulation unit 4 (and thus also the electro-acoustic modulators 9) and the control unit 3.

[0056] FIG. 5 shows one of the openings 7 in a view corresponding to FIG. 3, although the bubble generation is not generated by an electro-acoustic actuator 9, but rather by a modulation of the gas pressure, i.e. a gas pressure wave 10 propagates in the gas modulation unit 4. A corresponding arrangement with several openings 7, at each of which a bubble 6 is generated, is shown in FIG. 6 in a view corresponding to FIG. 3.

[0057] By arranging a separate electro-acoustic actuator 9 below each of the openings 7, any bubble pattern can be produced, as shown in FIG. 7. While bubbles 6 are formed at two of the openings 7 in the exemplary embodiment shown in FIG. 7, no bubble 6 is formed at the middle opening 7 by corresponding control. In this case, bubbles are not generated simultaneously even at adjacent openings 7.

[0058] In addition, provision may also be made to form a standing wave 11 within the gas modulation unit 4, as shown in FIG. 8 in a view corresponding to FIG. 1. The formation of the standing wave, i.e. the frequency range in question, naturally depends on the length and width of the bubble diffuser 5. Due to the length of the bubble diffuser 5, the standing wave 11 forms inside the housing, which can increase the energy efficiency of the gas modulation unit 4. The acoustic wave can be guided parallel or at right angles to the openings 7.

[0059] In addition, the efficiency can also be increased by designing the gas supply 1 in a meandering shape or by providing a pipe 12 perforated with the openings 7 or a correspondingly perforated channel downstream of the gas modulation unit 4. In the exemplary embodiment shown, the openings 7 are all located on the same side of the pipe 12, i.e. their surface normals all point in the same direction. FIG. 9 shows a top view of the upper side of the bubble diffuser 5 with the openings 7 on the left and the layer below with the perforated pipe 12 on the right. A pressure wave guided along the pipe 12 continuously forms bubbles 6 along the path travelled, so that bubbles 6 are released from adjacent openings 7 at a certain time interval and a spatially and temporally predetermined pattern of gas injection is realized. This reduces undesirable interactions, such as the merging of individual bubbles produced one after the other at the same opening 7.

[0060] FIG. 10 shows a side view of a further exemplary embodiment in which the gas supply 1 opens into a cavity in the gas modulation unit 4, which now modulates the supplied gas from below. Funnels 13 or funnel-shaped structures are provided below the openings 7 as perforations in a plate, which focus the gas onto the openings 7. By focusing pressure waves locally, the electrical energy required to generate the bubbles 6 can be reduced compared to a situation in which the pressure wave strikes the perforated plate directly.

[0061] FIG. 11 shows a schematic three-dimensional view of the gasification tank 16, with a gasification device arranged therein with several bubble diffusers 5 and a meandering connection between them. In this way, gas bubbles can be introduced over a large area into the liquid 8 contained in the gasification tank 16, for example waste water, in which a liquid column with a height typically in the range of 4 m to 5 m lies above the openings 7, although smaller and larger liquid columns are also possible. In biological wastewater treatment, air or pure oxygen is typically used as a gas, but other gases can also be introduced depending on the application, for example ozone for trace elimination, biogas or sewage gas or carbon dioxide for membrane cleaning. Other application examples include oxygen supply in aquaculture or fish farming, flotation in the extraction of raw materials in mining and in mining recycling, reduction of noise emissions in off-shore work by forming at least one bubble curtain, for dispensing medication or for mixing and mass transfer in chemical processes.

[0062] Typically, the gasification device is operated continuously, but intermittent emission of pressure waves can also be provided. In further embodiments, in addition to the control unit 3 as a pressure control unit, which sets the pressure level to a specific level, an acoustic damper or the acoustic damping unit 14 can also be provided, which prevents the reflection of acoustic waves at the end of the bubble diffuser 5, the gas supply 1 or the pipe 12. It is also possible to connect the gas modulation unit 4 to a signal generator, or the gas modulation unit 4 already comprises the signal generator, so that harmonic signals, i.e. sinusoidal waves, with adjustable amplitude and frequency are generated. An electrical or electronic amplifier can also be provided to amplify the signals from the signal generator.

[0063] The size of the resulting bubbles 6 is determined by several parameters, namely the size of the openings 7, the frequency of the pressure of the modulated signal, the signal amplitude and the pressure difference between the gas in the gas supply 1 or parts connected to it and a critical pressure level that applies to the formation of bubbles in the respective liquid 8.

[0064] It may be provided that the gas is maintained at a static pressure level that is 20 percent below this critical level, i.e. 20 percent below the minimum pressure at which bubbles 6 begin to form. The control unit 3 is typically designed to maintain this level with an accuracy of 1 percent. As shown in FIG. 12, a continuous sinusoidal pressure signal generated by the signal generator and transmitted via an amplifier to a loudspeaker of the gas modulation unit 4 can generate an acoustic pressure wave that propagates along the gas supply line 1 and/or the pipe 12. The resulting oscillating instantaneous pressure value is shown over time in FIG. 12. FIG. 12 shows three periods of an exemplary signal in which the original signal of the signal generator is compared with pressure variations. The pressure wave shows gas compression for half a period, followed by relaxation for the rest of the period. The maximum acoustic pressure gradient is sufficient to lead to the spontaneous formation of a bubble 6 as soon as the critical pressure is exceeded. The diameters of the generated bubbles 6 can typically be set between 0.01 mm and 5 mm.

[0065] For example, with a pressure wave of a frequency of 165 Hz and a pressure of 0.6 kPa below the critical pressure (which in this example corresponds to 103.5 kPa), a bubble formation can be achieved, since the local pressure level below one of the openings 7 is brought to a pressure level above the critical pressure by the pressure wave, and thus a spontaneous bubble formation begins, in which a bubble forms within a few milliseconds.

[0066] FIG. 13 shows the different phases of bubble formation in a diagram. In each case, the normalized and therefore not unitized pressure is plotted against time. FIG. 13a) shows the gasification device at low acoustic frequencies. When the first acoustic wave reaches the opening 7 in this first operating mode, a sufficiently large pressure difference is provided to produce bubbles 6. Due to the low frequency, the bubble 6 has enough time to grow and the buoyancy force is significant. The detachment of the bubble 6 from the opening 7 is also due to the buoyancy force. The initial detachment of the bubble 6 takes place at the time t.sub.d<0.5t.sub.p, i.e. at a time at which the pressure difference caused by the acoustic wave is positive. t.sub.p denotes the duration of a complete period of the pressure wave and ta the time required for the bubble 6 to detach from the opening 7. In this first operating mode, the start of bubble formation can be controlled, but not the bubble size.

[0067] FIG. 13b) shows a second operating mode in which bubble formation takes place between 0.5t.sub.p<t.sub.d<0.75t.sub.p. During bubble formation, the bubble 6 expands and contracts successively and eventually forms a small bubble 6. In this case, detachment is determined by hydrodynamic forces. In this second operating mode, the bubble size and the frequency of bubble formation can be determined by adjusting the properties of the acoustic wave. For example, bubble sizes between 0.5 mm and 0.7 mm can be generated in a frequency range of 168 Hz to 182 Hz of the acoustic wave. If the pressure difference is increased, the frequency tends to be lower, for example 154-612 Hz, and the size of the bubbles is 1.1-1.5 mm.

[0068] FIG. 13c) shows a third operating mode in which neither the bubble size nor the formation frequency of the bubbles can be controlled. The duration of bubble formation is 0.75t.sub.p<t.sub.d<t.sub.p. In this operating mode, the waiting time for detachment is too short for the bubble 6 to detach from the opening 7. Finally, FIG. 13d) shows a fourth operating mode for high frequencies of the acoustic wave. In this case, the frequency is set too high and the bubble 6 cannot detach from the opening 7. In principle, however, bubbles 6 with defined properties can be formed continuously at any frequency, provided that the original pressure level is set accordingly. For this reason, the control unit 3 is used to provide a constant gas pressure or a constant gas volume flow, so that the first operating mode or the second operating mode can be achieved by adjusting the parameters of the modulation by the gas modulation unit 4. However, it is also true that the operating modes depend on the gas and liquid used 8 as well as the size of the openings 7, the liquid column above the openings 7, the amplitude and frequency of the acoustic wave and finally the response of the gasification device to the intended frequency range. FIG. 16 shows the formation of bubbles in the various operating modes, with FIG. 16a) showing the first operating mode, FIG. 16b) the second operating mode, FIG. 16c) the third operating mode and FIG. 16d) the fourth operating mode.

[0069] FIG. 14 shows an example of the variation of the bubble size in the left part of the figure and the bubble frequency in the right part of the figure with the signal frequency in the second operating mode. The size of the opening 7 is 0.81 mm in the exemplary embodiment shown. The hydrostatic pressure level is kept constant at 200 mm above the opening 7 and the measurement is carried out at atmospheric pressure. In addition, the amplitude of the acoustic signal is kept constant. Regardless of the pressure difference, the maximum achievable bubble size is reached at 161 Hz, whereas the frequency of bubble generation depends on the frequency of the acoustic signal. In a particularly advantageous way, the frequency of the acoustic signal can be tuned to the resonance frequency of the gasification device used, as shown in FIG. 15 in a corresponding diagram.

[0070] FIG. 17 shows a further diagram of a pressure modulation that can be generated according to one embodiment. In this case, the pressure modulation is periodic, but not necessarily harmonic (e.g. not sinusoidal). Instead, the pressure curve p plotted over the time t describes a kind of sawtooth profile, whereby the real pressure curve can also be somewhat less sharp-edged than the variant shown due to inertia effects and other imperfections.

[0071] A period of pressure modulation is made up of two time proportions tA and tB. FIG. 17 shows an example of two periods and the corresponding time end points T1 and T2, whereby the number of periods can be increased as required.

[0072] Each period comprises a pressure modulation to a level above a critical pressure Pcrt and to a level below. Within a first time proportion tA, the pressure is initially increased to an amplitude A1 compared to the critical pressure Pcrt. The pressure is then lowered, whereby an amplitude A2 below the critical pressure Pcrt is reached within a second time proportion tB.

[0073] It has been shown that an initial rapid increase in pressure to a level well above the critical pressure Pcrt is advantageous for rapid and reliably controllable bubble formation. With the subsequent pressure reduction during the time proportion tB, which is shorter in time compared to the time proportion tA and deviates less from the critical pressure Pcrt in terms of amount, the bubble that has already formed proproportionally is reliably released with its size finally determined.

[0074] The respective differences D1, D2 of the amplitudes A1, A2 of the time proportions tA, tB to the critical pressure Pcrt are shown in FIG. 17 and differ noticeably from each other. For example, the difference D1 is at least twice as large as the difference D2.

[0075] FIG. 17 also shows that the integral of the pressure p over time t (i.e. the area between the pressure modulation curve and the time axis) is greater over the duration of the first time proportion tA than over the duration of the second time proportion tB. Thus, an energy input corresponding to this integral and area is greater during the first time proportion tA than during the second time proportion tB.

[0076] Features of the various embodiments disclosed only in the exemplary embodiments can be combined with each other and claimed individually.

LIST OF REFERENCE SIGNS

[0077] 1 Gas supply [0078] 2 Valve [0079] 3 Control unit [0080] 4 Gas modulation unit [0081] 5 Bubble diffuser [0082] 6 Bubble [0083] 7 Opening [0084] 8 Liquid [0085] 9 Actuator [0086] 10 Gas pressure wave [0087] 11 Standing wave [0088] 12 Perforated pipe [0089] 13 Funnel [0090] 14 Damping unit [0091] 15 Gas supply line [0092] 16 Gasification tank