HU209270B - Process and equipment for flotation treatment of liquids, particularly water and sewage - Google Patents

Abstract

Liqs. esp. contaminated water and effluents are treated by a flotation process. A gas, esp. air is forced in under excess pressure and absorbed. The pretreated liq. is allowed to expand. Expansion causes bubbles to form on contaminated particle surfaces as well as in agglomerates mostly in floc form. Pretreated pressurised satd. as well as untreated raw liqs. are circulated under controlled conditions, in a closed system and brought into surface contact. At the same time the gas saturation stream or rather the liq. treatment stream and the treated liq. offered for flotation are maintained at their individual pressure levels. - The pressure of the satd. liq. is lowered in individual portions to further processing levels. Simultaneously, the pressure of the liq. to be treated, is increased in batches to that of the gas saturator. Opt. bubble formation in the super satd. liq. is regulated by an increase in the intensity of the bubble formation rate. Liq. volume losses are replenished, and on completion of treatment liqs. are transferred - with opt. prior flocculation treatment - for removal.

Description

In the process of the present invention, the pressurized, saturated and crude fluid are contacted in a closed system under controlled flow at their interface while separating the pressure levels of the gas saturation flow stream and of the crude liquid for treatment and flotation of the treated liquid. Subsequently, the pressure of the saturated liquid is lowered alternately to the pressure of the further technology per serving, simultaneously increasing the pressure of the saturated liquid per serving to the pressure of the gasifier, controlling the bubbling of and finally the treated liquid - optionally discarded in combination with flocculation.

The apparatus also subject to the invention is a pump (1) for raw liquid, a pump (3) for saturation gas, a device for loss of liquid, a device (8, 9) for mixing chemical agent (s), if desired, preferably control flow. control / regulation equipment and a technological pipeline network with appropriate fittings. A characteristic feature of the apparatus is that a gas-discharge flow circuit is connected to the raw liquid dispensing pump (1), which is: - dispenser valve (s) (4f), pressure chamber (s) (5), outlet valve (s) (4k), comprising a circulating pump (2) and a gas purifier (6), a supersaturated liquid flow section (12) connected to the gas purge flow circuit, and the gassing flow circuit and / or supersaturated liquid flow section (12), if necessary, provided with a bubbler.

BACKGROUND OF THE INVENTION The present invention relates to a process and apparatus for liquids, in particular water, waste water, etc. flotation treatment, in which the gas required for evacuation - mostly air - is absorbed in the liquid by pressurization, and the pre-treated liquid is expanded to form bubbles on the surface of the contaminating particles and on the particles agglomerated mainly in the flakes.

Bubbles allow oil, grease impurities, colloidal particles or particles close to the colloidal range, as well as finely divided mineral or other hydrophobic substances, possibly impurities, to be desirable or known per se, under energetically favorable conditions and under good conditions. can be removed with technological efficiency.

The process can also be combined, if desired, with the simultaneous addition and vigorous mixing of any secretagogue.

Water treatment and wastewater treatment technologies often use a variety of, preferably fine-bubble, floatation techniques, sometimes using additives to enhance the floatation efficiency. The air most used for flotation can be introduced into the liquid to be treated in various ways. This is the case with air injection, in which pressurized air is introduced into the liquid through nozzles located in the aeration pool. Preferably used for sweeping grease and oil droplets.

There is a wider use of the so-called. pressure treatment. In this case, the pressure of the air above the liquid in the closed space in the container is increased so that it dissolves in the liquid to be treated, and then the pressure is slowly reduced to normal atmospheric pressure. At this point, the dissolved gas above the saturation value will be in the form of fine bubbles. The gas bubbles then, as they move upward, trap the particles and remove them.

Conventional flotation methods allow for higher oil and solids, municipal or food wastewater treatment solutions, although floating is a relatively expensive selection process due to the equipment required.

Pressurized technology can also be applied by applying pressurized saturation to only part of the purified water. This saturated partial stream is then mixed with untreated raw water before bubbling expansions are introduced and then discarded together in the flotation pool.

DE-PS 2938264.7 discloses such a solution.

patent. In this case, the fluid to be treated is fed to the flotation reactor via two successively connected jet pumps. The first jet pump is driven by a partial stream of purified water and the gas to be absorbed is led to its suction nozzle. The second jet pump 35 is connected to its first outlet. Untreated water is fed to the suction nozzle of the second pump, which, together with the saturated liquid, is introduced into the float pan.

The advantage of this solution is that it is relatively simple, moreover, that at the same time as expansion, the raw water, which is to be treated and treated, can be intimately mixed with one another. However, it has the disadvantage that the liquid partial flow also loads the displacement reactor hydrodynamically. It is also disadvantageous that it is practically difficult to achieve sufficient efficiency in extracting the intake air, while the disperse gas content is detrimental to the operation of the recirculating pump and therefore the system is energetically unfavorable.

DE-PS 2801 494 discloses a similar solution for the prior gas stroke of a partial stream of liquid. patent specification. In this case, the liquid to be treated is dispensed into a horizontal flotation chamber. Underneath this chamber is a space, separated from the chamber by a fine mesh fabric, into which a stream of purified liquid from the flotation chamber is conducted, which is passed through a re-aeration apparatus before being discharged into the chamber.

The disadvantage of the solution is that the flotation equipment2

A separate space shall be delimited for the bubbling expansion space from 270 Β. The two types of media cannot be clearly separated with the mesh, and macrobubbles can form on the mesh, reducing the efficiency of the cleaning and disturbing the calm flow conditions. The fluid circulated in the saturation circuit must be raised by a separate energy supply to the required pressure level, which energy is then lost during expansion.

A common disadvantage of conventional pressurized flotation modes is that the energy for introducing the liquid medium into the gasifier is expelled by expansion and generally forms gas bubbles in the stream of the treated or treated fluid only, so that the efficiency of the cleaning process is strongly dependent on likelihood of encounter or gas trapping.

It is an object of the present invention to provide a method for reducing power consumption and consumption which is good in terms of space utilization, high isolation capacity, simple operation mode and lower operating cost.

It is known that when the pressure of a gas-saturated liquid is reduced at equilibrium, gas evolution is extremely slow. In the case of free surface, only surface is used for material transfer, which is significant only in film reactors. And closed, fluid-filled systems do not have as many material transfer surfaces. Because the gas concentration in the liquid is uniformly distributed, thus not being a driving force, in unmixed non-turbulent systems, gas evolution is therefore a very slow onset process, which is determined by the diffusion rate.

Subsequently, a technologically controlled and controlled process of bubbling gas evolution should be provided: the initial phase surface and the appropriate number of bubble initiators, and the hydrodynamic conditions required to regenerate the gas bubble surface, as well as the time required for gas evolution and bubble growth.

The present invention is based on the discovery that, if proper and intense hydrodynamic conditions are achieved, they can provide a "shock" -like acceleration of desorption. Such a strong hydrodynamic effect, which is as short as possible, creates microbubbles and speeds up the process. The phase surface and the fact that the partial pressure of the gases thus dissolved in the gas phase is less than the equilibrium pressure of the concentration in solution are also apparent.

The intensity of the effect - the power delivered per unit volume flow - influences the initial phase surface.

We have found that the process based on the invention provides all the necessary conditions in a manner not known to date.

The intensity of the exposure - that is, primarily the formation and appearance of microspheres and bubble buds - can be adjusted and controlled during the process, but their desired growth process and rate can also be controlled. The required time may be available either in the pipeline between the saturation-expanding section and the ejection or, with appropriate addition, in the flocculating space. It is not necessary to ensure a tight integrity of the saturation-expanding and flotation sections. Simultaneous and yet elongated run-out of fine-bubble desorption - and, optionally, flocculation and / or droplet capture of oil emulsion - also increases the purification efficiency.

Chemical addition and mixing, which may be carried out concurrently with or subsequent to hydrodynamic "shocking" in the process of the present invention, may further facilitate bubble formation, with the necessary growth, especially when agitated, preferably rapidly, in a gas saturated low pressure fluid stream. On the other hand, when the chemical (s) is added to the high pressure, gaseous water, the agglomeration of the gas and the agglomeration of the possibly broken flakes in the expanded water is practically parallel to each other, and bubbles are also formed inside the flakes.

It has been found that gas saturation of the liquid and desorption by hydrodynamic "shock", preferably intense, controllable and controllable, and flotation treatment based on it, can be achieved by separating the pressure level of the gas saturation-expansion from the pressure level of the crude liquid and the high pressure, saturated liquid is expanded as such, and the low pressure but already supersaturated fluid is "shocked" as needed. In this way, the pressure level to be achieved during gas saturation can be maintained with significant energy savings, the required flow of fluids is achieved and only the internal flow losses of the system need to be compensated for as needed.

Based on these findings, the object of the present invention has been solved by a process wherein the crude fluid is treated with a gas at a pressure above atmospheric pressure, preferably with air, for flotation treatment of pressurized liquids, optionally at chemical addition. SUMMARY OF THE INVENTION The present invention relates to contacting the pressurized, saturated and crude fluid in a closed system under controlled flow at their interface while separating the pressure levels of the gas saturation flow stream and of the crude liquid treatment and flotation of the treated liquid. Subsequently, the pressure of the saturated liquid is lowered alternately to the pressure of the further technology per serving, while simultaneously increasing the pressure of the saturated liquid to the pressure of the gasifier, if desired, the bubble development of the supersaturated reduced fluid is controlled by increasing the make up and finally dispense the treated fluid, optionally in combination with flocculation.

According to the invention, an apparatus for exemplifying the process comprises a raw liquid transfer pump, a saturating gas, optionally air,

EN 209 270 Β A pump, a replacement for loss fluid, a mixing device for the chemical (s) as required, a flow detection / control device, if desired, preferably a control technology, and a technological piping network with appropriate fittings. The apparatus is characterized in that a gas discharge flow circuit is connected to the crude fluid delivery pump, which comprises, respectively, a discharge valve (s), a pressure chamber (s), an outlet valve (s), a recirculating pump and a gas vent. a flow section is connected, and the supersaturated liquid flow section is provided with a bubble former, if necessary.

The process and apparatus of the present invention will be described in more detail and in greater detail with reference to the accompanying drawings, in which: The flotation device of Figure 1 has two pressure transducer chambers and, optionally, four to four single-pass sender and exit fittings. ;

in the embodiment of Fig. 2, the assembly of the previous flowchart is supplemented by introducing a high pressure saturated liquid flow portion acting on the supersaturated liquid flow section to facilitate bubble formation;

in the embodiment of FIG. 3, a chemical mixer and a flocculator are incorporated into the high pressure saturated fluid flow of the process of FIG. 1 to aid in chemical treatment efficiency;

Figure 4 shows the solution of Figure 1 inserted into a low pressure, saturated liquid flow section for a chemical mixer to aid bubble formation and partly to aid in chemical treatment;

and, in the case of the solution shown in Fig. 5, to add chemicals for flotation and flocculation, to increase the efficiency of the chemical treatment, there are fast chemical agitators and flocculators in the gasification flow circuit, while the supersaturated liquid flow section is supplemented by another in-line mixer, in addition to gas secretion, it also aids the mechanism of action of the organic brightener.

1 is a flow chart illustrating an exemplary apparatus for dispensing a crude fluid from two dispensing pumps 5/1, 5/2 connected in parallel with two 4f / l and 4f / 4 and 4f / 3 dispensing chambers, respectively. and 4f / 2 and 4k / l and 4k / 4 and 4k / 3 and 4k / 2 outlet fittings installed at their exit, after the 4k / l, ... 4k / 4 outlet fittings, are connected in the direction of fluid flow It has 2 circulating pumps, 6 gas fillers, the outlet piping of which is connected to the 4f / 4 and 4f / 2 sender fittings. The gas eliminator 6 also has a connection for the air compressor 3 and the loss fluid replacement device. The low-pressure, supersaturated liquid has 12 flow stages of 4k / l and

It is connected to 4k / 3 output fittings and leads to any additional equipment in the technology.

In the process assembly of Fig. 2, the former is supplemented by a high-pressure, saturated liquid stream branching out of the pipeline section after the gasifier 6, which is connected to the low-pressure, supersaturated fluid flow section 12 via a throttle element 10 and an injector.

In the example of the arrangement shown in Fig. 3, the basic arrangement according to Fig. 1 is supplemented with a chemical quick mixer 9 on the post-degasser section 6 and a flocculator 7 in the connection.

Referring to Figure 4, an in-line chemical mixer 8 is inserted into the basic arrangement in the flow section 12 of the low pressure supersaturated liquid.

The arrangement of Fig. 5, as a possible combination of the above, has a chemical quick mixer 9 and a flocculator 7 connected to the post-degasser section 6 and a chemical mixer 8 connected to the flow section 12 of the low-pressure, supersaturated liquid. Bubble formation may also be promoted by ultrasound.

The operation of the apparatus according to the invention, in particular and in detail the basic arrangement according to Fig. 1, will now be described.

The flotation equipment (not shown), the level conditions, determines the required pressure that the crude fluid must have in order to pass through the technology. The pressure level of the gasifier 6 does not impose any requirement on the feed fluid pump 1, since the feeder 4f and outlet outlets 4k do not directly connect the line of the feed fluid pump 1 to the gasifier flow circuit. The pressure of the gas settler 6 is always determined by the compressor 3.

4 / 4-5 /, 4¾

In order to make the 6-./; ~ / 2-6 ⁶ 4 In order to maintain the flow in the gassing flow loop ^ -5 ^ 4¾, there is a need for a circulating pump 2 to cover the internal resistances of the two alternative gassing flow circuits (the horizontal fracture or / or meaning).

The liquid conveyed by the crude fluid delivery pump 1, in the position shown in Figure 1, passes through the open 4f / l delivery assembly to the pressure switch chamber 5/1, whereupon the gas cycle is discharged in the appropriate cycle which is replaced by the valve 4f ... 4k. from the pressure value of the gassing flow loop to the pressure level of the crude liquid, it passes through the open 4k / 3 assembly to the downstream - preferably to a flotation device. Meanwhile, the high pressure, gaseous liquid exiting the gasifier 6, through the operation of the circulating pump 2, passes through the open dispenser assembly 4f / 2 to the pressure chamber 5/2, from where

EN 209 270 Β feeds the crude liquid from the previous stage through the 4k / 2 outlet fitting via the recirculation pump 2 to the gasifier 6. When the pressure chamber 5/1 and 5/2 are completely filled with crude or gaseous liquid, the fittings 4f ... 4k are reversed and the process is repeated.

Of course, the synchronization of the process must be ensured. This can be driven by an evaluation of the quality difference between gaseous and unsaturated liquid, but it is a simple and reliable solution to keep the pumping capacity of the circulating pump 2 at 1-2% above that of the feed pump 1, At the expense of internal recirculation, it is possible to ensure that only gaseous liquid leaves the technological line shown. Thus, the outlet fittings 4f to 4k provide an open flow path for the raw liquid delivery pump 1, but the fluid conveyed therefrom is cyclically exchanged with only the gaseous liquid leaving the process queue. The outlet fittings 4f ... 4k, however, create a "closed" flow in the gasifier flow circuit, however, the fluid supplied by the circulating pump 2 is cyclically exchanged so that, except for 1-2% recirculation, unsaturated crude fluid enters. Through valve changes, the low pressure crude fluid is connected to the gassing flow circuit ("slamming") and the high pressure gaseous liquid is connected to the gaseous discharge pump conduit ("squeeze"). A volumetric loss can occur from the high pressure, gas purge flow loop during drip changes, sampling, and dripping during dip changes. To compensate for this, in order to preserve the fluid level of the gasifier 6, the gasifier flow circuit needs to be replaced in terms of weight loss. This is provided by a fluid supply unit (not shown), optionally with a hydrophore system.

By "leaching" the gaseous liquid over a fraction of a second, the pressure in a volume of a pressure chamber decreases and thereby becomes supersaturated. Desorption is accelerated, provoked by intense hydrodynamic conditions. Short-term strong hydrodynamic effects - "shock" - create microbubbles and accelerate the process. the phase surface appears and the partial pressure of the dissolved gases measured in the gas phase is less than the equilibrium of the concentration measured in the solution.

It is also possible to coordinate desorption with any chemical treatment that may be required. Examples of technological variants include:

a) Non-chemical flotation treatment - eg. Oil selection. A short-term hydrodynamic effect, e.g. by providing a partial current through the elements 10,11 of FIG. 2 or by in-line mixer 8 prior to introduction into the flotator of FIG. 4.

(b) Chemical flotation treatment.

b.l) Flocculation with metal hydroxide only.

B.1.1. As shown in Figure 3, it is desirable to transfer the chemical through the quick mixer 9 to the high pressure, gaseous liquid, whereby the flocculator 7 provides a well flocculated state. With the shocking bubbling of the "spilled" liquid, the gas evolution and the re-agglomeration of the broken flakes take place in parallel, bubble inclusions build up inside or on the surface of the flakes.

b.l.2. Dosing of chemicals with rapid mixing - optionally using an in-line mixer. As shown in Figure 4, rapid agitation takes place in the low-pressure, gaseous liquid, while ensuring that bubble precipitation is initiated.

c) Metal hydroxide flocculation in combination with an organic flocculant:

In the embodiment of Figure 5, the metal hydroxide flocculating chemical is introduced into the high-pressure, gaseous liquid by means of the quick mixer 9. After expansion, the organic flocculant is introduced through the agitator 8. The mixer, optionally in-line 8, not only uniformly blends the chemical, but also promotes bubble formation.

Further main advantages of the method and apparatus of the invention are as follows:

1. Expansion does not occur at local hydraulic resistances but at volume doses. Thus, it is more readily possible to release gas within and / or at the surface of the floating material.

2. Hydrodynamic "shock" of a liquid supersaturated in a gas can enhance bubble secretion or, after single absorption, a two-stage flotation.

3. There is no need for a close connection between the saturation-expansion unit and the flotation reactor. The simultaneous, time-dependent fine-bubble desorption, flocculation and / or droplet capture of the oil emulsion optionally increases the purification efficiency.

Claims (11)

A process for treating liquids, particularly water, wastewater, by pressure flotation, optionally with a chemical addition, wherein the crude liquid is saturated with a gas at a pressure above atmospheric pressure, preferably air, characterized in that the pressurized, saturated and crude fluid is contacting each other at their interface while separating the pressure level of the gas flow flow and the raw liquid treatment and flotation of the treated liquid, alternately lowering the saturated liquid pressure to the level of additional technology per serving, and simultaneously increasing, if desired, the bubble development of the supersaturated, depressurized fluid, optionally by increasing the intensity of development - regulate any volumetric loss5 EN 209 270 Β and finally discard the treated liquid, optionally in combination with flocculation. 2. The method of claim 1, wherein the technological steps of the treatment prior to final dispatch are carried out in complete fluid volume. Method according to claim 1 or 2, characterized in that the chemical (s) is added to the gas stream at higher and / or reduced pressure. 4. A process according to any one of claims 1 to 3, characterized in that bubble development is facilitated by the introduction of a fluid stream and / or chemical or chemical in-line mixing and / or ultrasonic treatment. 5. A method according to any one of claims 1 to 4, characterized in that the flow of interconnected fluids is controlled by the quality sensing of the fluids. 6. Process according to any one of claims 1 to 3, characterized in that the internal fluid circulation is adjusted to a degree, preferably 1 to 2%, to ensure a saturated fluid outlet. 7. Apparatus for treating liquids, especially pressurized water, wastewater, preferably by chemical addition, having a raw liquid dispensing pump, a saturating gas pump, if appropriate air pump, a loss fluid replacement device, mixing device for the chemical (s), if desired, preferably a sensor control device and a technological piping network with appropriate fittings, characterized in that a gas-discharge flow circuit is connected to the raw liquid dispensing pump (1), which - pressure vessel (s) (5) respectively comprising an outlet fitting (s) (4k), a recirculating pump (2) and a gas purifier (6), an overflow liquid flow section (12) connected to the gas flow stream, and a gas flow flow line and / or overflow liquid flow section (12). 12) - if necessary - equipped with a bubble generator. Apparatus according to claim 7, characterized in that there are at least two pressure transduction chambers (5) connected in parallel. Apparatus according to claim 7 or 8, characterized in that the bubble-forming injector (11), optionally in-line, with a gas-saturated liquid, optionally in-line, a mixer (8), a flocculator (7) and / or ultrasound equipment. 10. Device according to any one of claims 1 to 3, characterized in that the flow sensor control device is a device for detecting the difference in quality or flow rate of the crude and the saturated liquid. 11. Apparatus according to any one of claims 1 to 4, characterized in that the chemical mixer (8) is inserted in the flow section after the gasifier (6) and / or the supersaturated liquid.