WO2007057012A1 - Liquid treatment arrangement, in particular water treatment arrangement - Google Patents

Abstract

A liquid treatment arrangement, in particular water treatment arrangement (1) is specified having at least one reverse osmosis membrane unit (8a, 8b) which comprises an inlet (7), a permeate outlet (10) and a concentrate outlet (13), and a transport device which is connected to the inlet (7) and comprises a pump (6) connected to an electric motor (14) and a hydraulic motor (16) and has an input line (5), the hydraulic motor (16) being arranged between the concentrate outlet (13) and a disposal connection (18). It is wished to be able to carry out cleaning of such a water treatment arrangement with low expenditure. For this purpose it is provided that the hydraulic motor (16) can be operated as a flushing pump which transports permeate into the membrane unit (8a, 8b).

Description

 Liquid treatment arrangement, in particular water treatment arrangement

The invention relates to a fluid treatment arrangement, in particular a water treatment arrangement having at least one reverse osmosis membrane unit having an inlet, a permeate outlet and a concentrate outlet, and a conveyor connected to the inlet and one connected to an electric motor and a hydraulic motor Pump having an input line, wherein the hydraulic motor between the concentrate outlet and a disposal port is arranged.

Such a liquid arrangement designed as a water treatment arrangement is known, for example, from US Pat. No. 6,139,740. For example, the pump delivers salt water through the membrane unit. The membrane unit has a membrane through which the water is forced. The water is purified, especially desalted. The purified water, which is also referred to as "permeate" is discharged through the permeate. However, the volume of permeate is much smaller than the volume of water supplied. Accordingly, a greater proportion of unpurified water remains at an increased level of soil or contaminant, which is accordingly referred to as a "concentrate". The concentrate is discharged via the concentrate outlet.

For operation of the reverse osmosis membrane unit, the supplied water must be brought to an elevated pressure so that it can penetrate the membrane in the membrane unit. At this pressure is then also the concentrate. In order to utilize the energy content of this concentrate, the concentrate is passed through the hydraulic motor, which, together with the electric motor, drives the pump which feeds the water into the inlet of the membrane unit.

A similar embodiment is known from US 6468 431 B1. Again, the concentrate from the concentrate outlet of the membrane unit is fed to a hydraulic motor which acts on the same shaft as an electric motor, the pump being mechanically connected to the shaft.

In such a water treatment arrangement results in the course of time pollution, in particular contamination of the membrane of the membrane unit. This pollution can have different causes. In many cases, one can observe bacterial growth. In many cases, ingredients of the water to be purified settle on the membrane. In order to remove bacteria from the membrane, it is known to pass chemicals through the system. To clean filters, it is known to flush the filter in the reverse direction with liquid, a so-called "reverse flush".

In connection with a water treatment arrangement, it is known (US 6,174,437 B1) to pump the purified water in the reverse direction through the membrane unit in order to clean the membrane unit. However, this requires a considerable effort.

The invention has for its object to perform a cleaning with little effort.

This object is achieved in a water treatment arrangement of the type mentioned above in that the hydraulic motor is operated as a rinsing pump, which promotes permeate in the membrane unit. Thus, the hydraulic motor is not only used to recover energy from the concentrate in order to increase the efficiency of the water treatment system. It also uses the hydraulic motor to clean the membrane unit. Most hydraulic 5 motors can be operated both as a motor and as a pump. In many cases, this can be done simply by reversing the drive direction while maintaining the connections. Since it can be assumed that the hydraulic motor works predominantly as a motor and only in special situations, namely to clean the membrane unit, it must be operated as a flushing pump, the hydraulic motor can also be designed primarily for its task as a motor. It only needs to be ensured that the engine can work as a purge pump. The term "scavenge pump" is introduced in order to distinguish the hydraulic motor, when acting as a pump, from the normal pump 5, which during normal operation conveys the fluid through the membrane unit.

Preferably, the purge pump promotes permeate in the concentrate output. In this case, the membrane of the membrane unit is not cleaned or not o only by flushing. Instead, the permeate pumped by the flushing pump only reaches the side of the membrane which is otherwise exposed to the water supplied and to be cleaned. However, this is sufficient in many cases to remove deposits on the membrane. Particularly effective is the cleaning with the permeate but by the fact that the permeate can kill bacteria that only in the to be cleaned

Water, especially salt water, are viable. If such bacteria are exposed to a "freshwater" atmosphere where the concentration of minerals is not correct, then they are killed or at least greatly inhibited in their growth. The fact that one promotes the per- o meat in the concentrate output, you have to change the "wiring" of the water treatment arrangement basically nothing. The hydrau- The motor can be directly connected to the output of the membrane unit and remain.

Preferably, the electric motor is rotationally reversible, wherein 5 corresponds to a direction of rotation of the electric motor with the direction of rotation of the hydraulic motor in engine operation and operates in the opposite direction of rotation of the hydraulic motor as a rinse pump. So you need no complicated gear assembly to switch the hydraulic motor from the engine operation to the pump operation. It is sufficient to change the direction of rotation of the electric motor. This is easily possible in many cases. The electric motor then has two directions of rotation, being assisted in one direction of rotation by the hydraulic motor. On the pump then acts in the "normal operation" 'the combined drive power of electric motor 5 and hydraulic motor. On the other hand, if the electric motor is reversed, ie operated with a different direction of rotation, then the hydraulic motor operates as a flushing pump. In this case, although missing from the hydraulic motor in normal operation provided drive power is missing. However, this is not critical because the cleaning process of the o membrane unit is usually much shorter than the operation of the

Water treatment arrangement in normal operation.

It is preferred that the electric motor has a power supply device whose current direction is switchable. The switching of the current direction is a particularly simple design to change the direction of rotation of the motor. If the current is a three-phase current, reversing the current direction means reversing the rotation of the rotating field.

o Preferably, the hydraulic motor has an output which opens via a first check valve, which opens away from the output with the Disposal port and a second check valve, which opens to the output, is connected to the permeate port. In this case, the two check valves cooperate so that the concentrate can come from the concentrate output to the disposal port during engine operation. The second check valve prevents concentrate from passing to the permeate outlet. If, however, the hydraulic motor is operated as a rinsing pump, then it can suck in permeate via the second check valve. An access of liquid from the disposal port is reliably prevented by the first check valve. This results in the possibility of automatic operation, in which no additional external intervention is required.

The pump preferably has different conveying directions as a function of the operating state of the hydraulic motor. When the hydraulic motor is operated as a motor, the pump is driven to deliver water to be purified from the input line to the inlet. This is the normal operation. In contrast, when the hydraulic motor is operated as a rinsing pump, then the conveying direction of the pump rotates so that the pump sucks water from the inlet of the membrane unit. This makes it possible to generate a relatively large flow of permeate through the membrane unit.

Preferably, a suction line opens between the pump and the inlet. The pump usually has a larger delivery volume than the hydraulic motor. If the hydraulic motor and the pump are rigidly coupled together via the electric motor, then there is a risk that the pump receives too little liquid from the inlet of the membrane unit and therefore cavitation phenomena occur. It is therefore possible to supply the pump with a sufficient amount of liquid via the suction line. It is preferred that in the Nachsaugleitung a pump opening towards the third check valve is arranged. It prevents so that in normal operation to be cleaned water is pressed into the Nachsaugleitung.

It is particularly preferred that the Nachsaugleitung is connected to the permeate output. The required amount of liquid can then be added via the permeate outlet. This has the advantage that the pump can also be flushed with permeate, ie with purified water.

Alternatively it can be provided that the Nachsaugleitung is connected to the input line of the pump. In this case, liquid can be circulated around the pump, so to speak.

Preferably, a fourth check valve is arranged in the input line, which opens to the pump, and between the fourth check valve and the pump opens a connecting line to the disposal port, in which a check valve is arranged. The fourth check valve prevents the water treatment assembly from idling when the pump is not operating and drawing water. The fourth check valve, however, would prevent purging. Accordingly, a check valve is arranged in the connecting line, which opens when the hydraulic motor is operated as a rinsing pump. This opening of the check valve can take place automatically, for example, when the direction of rotation of the electric motor is changed. It can also be pressure controlled.

The permeate outlet is preferably connected to a collecting container. So you can always keep a sufficient amount of permeate ready for the flushing of the membrane unit. The invention will be described below with reference to a preferred embodiment in conjunction with the drawings. Herein show:

1 is a schematic representation of a water treatment arrangement,

Fig. 2 is an illustration of a simplified embodiment of a

Water treatment arrangement in the production of permeate, and

3 shows the water treatment arrangement according to FIG. 2 during the cleaning.

A water treatment assembly 1 takes water from a supply 2 shown only schematically. The supply 2 may be a well, the sea or any other body of water, the withdrawn water being either salt water or a polluted water or the like.

The removal of the water from the reservoir 2 takes place with the aid of a feed pump 3, which promotes the water via one or more filters 4 in an input line 5 of a pump 6. The pump 6 is connected in each case to an inlet 7 of a reverse osmosis membrane unit 8a, 8b, wherein the membrane units 8a, 8b are connected in parallel. Each membrane unit 8a, 8b has a membrane 9a, 9b, through which a part of the water conveyed into the inlet 7 is pressed.

The membrane unit 8a, 8b operates on the principle of reverse osmosis, ie the water which passes through the membrane 9a, 9b is cleaned or desalted. The purified or desalinated water is also referred to as "per- The permeate passes to a permeate outlet 10 and from there via a collecting line 11 to a tank 12.

However, the reverse osmosis membrane units 8a, 8b have an efficiency that is not too high. Only 20 to 35% of the water fed into the inlet 7 passes as permeate from the permeate outlet 10. The remaining water, which then has a higher concentration of dirt or salt and is therefore also referred to as "concentrate", leaves the membrane unit 8a, 8b a concentrate outlet 13. This concentrate is at the same high pressure of usually 60 bar as the water supplied at the inlet 7.

The pump 6 is driven by an electric motor 14. The electric motor 14 is connected to the pump 6 via a shaft 15. At this shaft 15 also engages a hydraulic motor 16.

The hydraulic motor 16 is connected to the condensate outlet of the membrane units 8a, 8b. The hydraulic motor 16 has an output 17 which is connected to a disposal port 18, which in turn opens into the supply 2.

The hydraulic motor 16 normally operates at the pressure of the water which the concentrate at the outlet 13 has. This pressure is only slightly lower than the pressure at the inlet 7, which has been generated by the pump 6. The motor 16 has a slightly lower volume than the pump 6, ie it consumes slightly less concentrate than the pump 6 promotes water. It is thus possible, in any case, to recover part of the energy which the concentrate at the outlet 13 of the membrane units 8a, 8b still contains. The connection between the hydraulic motor 16 and the disposal port 18 via a first check valve 19, which opens away from the output 17.

The output 17 of the hydraulic motor 16 is connected via a second check valve 20 to the manifold 11 and thus to the tank 12 and the permeate 10 of the membrane units 8a, 8b. The check valve 20, however, ensures that concentrate, which has flowed through the hydraulic motor, enters the tank 12 and the manifold 11.

The manifold 11 is connected via a suction line 21 to the output 22 of the pump 6. In the Nachsaugleitung 21, a third check valve 23 is arranged, which opens to the pump 6 through.

In the input line 5, a fourth check valve 24 is arranged, which also opens to the pump 6 through. On the other hand, the fourth check valve 24 ensures that the water treatment device 1 runs idle when the delivery pump 3 or the pump 6 are not in operation. The fourth check valve 24 may also be integrated in the feed pump 3.

Between the input line 5 and the disposal port 18, a connecting line 25 is arranged, in which a check valve 26 is arranged. The check valve 26 is shown here schematically as a check valve. However, it can also be designed in other ways.

Between the pump 6 and the filters 4, a pressure switch 27 is arranged, which ensures that there is always a certain minimum pressure for the pump 6 is present. This reliably avoids cavitation, for example. In front of the entrance 7 of the membrane units 8a, 8b, a second pressure switch 28 is arranged, which may also be designed as a pressure sensor. With the permeate 10, a third pressure switch 29 is connected, which may also be formed as a pressure sensor. With the help of the pressure switch 28, 29, a differential pressure across the membrane units 8a, 8b can be determined. For example, the differential pressure provides information as to whether cleaning is required, in other words, whether the membranes 9a, 9b are clogged and need to be rinsed. In some cases, however, one can also manage with a single pressure switch 28 (or pressure sensor) which only monitors the inlet pressure. If the pressure at the inlet 7 rises above a certain level, this is also an indication that the membrane units 8a, 8b have to be cleaned.

A sensor 30 determines the quality of the permeate, i. of purified water. If e.g. If too high a salt content is detected, this means that the membranes 9a, 9b are either defective or require rinsing. For example, increased salt content may indicate constipation.

An adding means 31 may be provided to re-add minerals to the permeate. These minerals can be obtained in a manner not shown from the concentrate. The water does not become corrosive or at least less corrosive due to this addition in the feed device 31. The minerals are added before the water hits an iron pipe. In addition, the taste of the water is enhanced by the addition of minerals.

Now, if the pressure switches 28, 29 determine that a flushing or cleaning of the membrane units 8a, 8b is required, then the

Direction of rotation of the motor 14 changed. For this purpose, the engine has an energy For example, in the case of a DC motor, the current direction is reversed to change the direction of rotation of the motor. In the case of a three-phase motor, the rotational direction of the rotating field may be changed to change the direction of rotation of the motor 14. The type of motor 14 used is irrelevant, as long as the direction of rotation of the motor 14 can be changed. The power supply 32 must of course be adapted to the type of motor 14 used.

If the direction of rotation of the motor 14 changes, then the hydraulic motor 16 is a rinsing pump, the liquid to the condensate outlet 13 promotes. The liquid required for this purpose, however, can not be removed from the supply 2 due to the first check valve 19. It is removed via the second check valve 20 from the tank 12. This has the advantage that not only the side of the membrane 9a, 9b is flushed, which is exposed to the water from the inlet 7, but the membrane unit 8a, 8b is filled with desalinated or purified water. Bacteria that can otherwise accumulate and proliferate in salt water are often killed and eliminated in this way, without the use of chemicals is required. Also minerals are flushed out, because they are dissolved in the purified water.

The promotion of the "fresh water", ie the permeate from the tank 12, is supported by the pump 6, which changes its conveying direction with an altered direction of rotation of the electric motor 14 and sucks the permeate from the condensate outlet 13 to the inlet 7.

However, the hydraulic motor 16 operating as a scavenging pump has a somewhat lower delivery rate than the pump 6. In order to prevent cavitation, the pump 6 can therefore be connected via the intake line 21 and the third Non-return valve also suck in permeate from the tank 12, so that cavitation can be avoided.

The evacuated from the inlet 7 permeate can not flow out due to the fourth check valve 24 by the feed pump 3 to the stock 2. For this reason, the connecting line 25 is provided. When the direction of rotation of the electric motor is reversed, the check valve 26 is opened, so that the permeate used for cleaning via the discharge port 18 can flow. The connecting line 25 branches off in front of the filters 4, so that the filter 4 are not applied during flushing with contaminated water, so that clogging of the filter 4 is avoided.

If the check valve 26 is simply formed as a check valve, which opens to the disposal port 18, then it is a biased check valve whose closing spring is dimensioned so that it resists the pressure in the input line 5, when it is normal operation. Only then, when the pump 6 turns its conveying direction, the pressure in the input line 5 increases so far that the check valve 26 opens.

As an alternative to the suction line 21, a suction line 33, shown in dashed lines, may be provided, in which a check valve 34 is arranged, which opens to the inlet 7 of the membrane unit 8a, 8b. Via the suction line 33, the amount of liquid that the pump 6 requires more than they can promote the rinsing pump formed by the hydraulic motor 16 can be replenished and that from the input line. 5

The mode of operation of the water treatment device 1 for the "normal operation" and for the cleaning will be explained again with reference to FIGS. 2 and 3. Here are the same elements with the same reference numeral Chen as provided in Fig. 1. Dashed lines are lines that carry high pressure. With solid lines are shown lines that lead to low pressure.

FIG. 2 shows the water treatment arrangement 1 in normal operation, ie in the production of permeate. The pump 6 promotes to be cleaned or desalinated water from the input line 5 to the input 7 of the membrane unit 8. There enters a portion of the water through the membrane 9 to the permeate 10 and from there into the manifold 11. The remaining 0 remainder comes as a concentrate Concentrate output 13 and drives from there to the hydraulic motor 16, which rotates in the same direction as the electric motor 14 and is attached to the same drive shaft 15, which also drives the pump 6. The hydraulic motor leaving concentrate, which is substantially depressurized, passes through 5 the first check valve 19 in the disposal port 18th

To represent the ratios of the flow rates, it is assumed that the pump 6 has a delivery volume of one liter (all subsequent liters refer to the same time unit). 0 Of these, 0.2 l enter the collecting line 11 as permeate and 0.8 l as

Concentrate and hydraulic drive medium to the hydraulic motor 16.

Fig. 3 shows the same water treatment arrangement 1 during cleaning, 5 thus in the "reverse flush", in which the membrane unit 8 is purged by permeate.

The pump 6 reverses the direction of rotation and promotes 1 I back into the input line 5. This one liter is composed of 0.8 I, o are conveyed by the hydraulic motor 16, which operates here as a scavenge pump, and 0.2 I. , which via the suction line 21 from the manifold 11 be supplied. The 0.8 I promotes the flushing pump (hydraulic motor 16) from the manifold 11 via the second check valve 20th

By a double arrow 35 in the line between the Permeatausgang 5 10 and the manifold 11 is indicated that depending on the design of the membrane unit 8 and the capacity of the pump 6 and the rinsing pump (hydraulic motor 16), a portion of the liquid through the membrane 9 for Permeate output 10 can get. It is also possible that fluid 11 passes from the collecting line 11 into the permeate outlet 10 and the membrane then flows through to the inlet 7. It is also possible to arrange a check valve (not shown) on the permeate outlet 10, which allows a permeate stream only out of the membrane unit 8. This prevents that the membrane 9 flows through flushing in the "wrong" direction. This can lead to damage in some membranes.

One can now largely automate the operation of the water treatment plant 1. Not shown switches in the tank 12 signal when an operation of the water treatment assembly 1 is required. 0

With the help of the pressure switch 28, 29 or the sensor 30 can determine when a cleaning is required. For the purpose of cleaning, the rotational direction of the electric motor 14 is changed and the membrane unit 8 is rinsed. For example, the water treatment assembly can be rinsed three times. Measurements are taken between each rinse. If there are no improvements after the three flushes, the assembly is shut down.

There are a number of additional options. So you can o for example, the electric motor 14 provided with a soft starter, for a slow pressure build-up and also for a slow Pressure reduction ensures. With this option you can spare the membrane 9. Of course, you can also use a different electrical circuit for controlling the electric motor 14 instead of a soft starter.

Such an arrangement can also be used for other applications with minor modifications. For example, if you want to concentrate orange juice or another fruit juice, use the concentrate as a finished product. In this case, however, the concentrate will not be fed back to the supply 2 via the disposal port 18, but will be collected in a separate container.

Claims

claims A fluid treatment arrangement, in particular a water treatment arrangement with at least one reverse osmosis membrane unit having an inlet, a permeate outlet and a concentrate outlet, and a conveyor connected to the inlet and a pump connected to an electric motor and a hydraulic motor an input line has 0, wherein the hydraulic motor between the concentrate outlet and a disposal port is arranged, characterized in that the hydraulic motor (16) is operable as a rinsing pump, the permeate in the membrane unit (8a, 8b) promotes. 5 2. Liquid treatment arrangement according to claim 1, characterized in that the rinsing pump (16) promotes permeate in the concentrate outlet (13). 0 3. The fluid treatment arrangement according to claim 1 or 2, characterized in that the electric motor (14) is reversible rotational direction, wherein a direction of rotation of the electric motor (14) coincides with the direction of rotation of the hydraulic motor (16) in engine operation and in the opposite Rotation direction 5 the hydraulic motor (16) operates as a rinse pump. 4. Liquid treatment arrangement according to claim 3, characterized in that the electric motor (14) has a power supply device (32) whose current direction is switchable o. 5. liquid treatment arrangement according to one of claims 1 to 4, characterized in that the hydraulic motor (16) has an output (17) via a first check valve (19) which opens away from the output (17), with the Entsorgungsan- End (18) and a second check valve (20), the Output (17) opens, is connected to the permeate (10). 6. Liquid treatment arrangement according to one of claims 1 to 5, characterized in that the pump (6) in dependence on the operating state of the hydraulic motor (16) has different conveying directions. 7. liquid treatment arrangement according to claim 6, character- ized in that between the pump (6) and the input (7) a Nachsaugleitung (21, 33) opens. 8. Liquid treatment arrangement according to claim 7, characterized in that in the Nachsaugleitung (21, 33) to the pump (6) opening toward the third check valve (23, 34) is arranged. 9. fluid treatment arrangement according to claim 7 or 8, characterized in that the Nachsaugleitung (21) is connected to the permeate outlet (10). 10. Liquid treatment device according to claim 7 or 8, characterized in that the Nachsaugleitung (33) with the input line (5) of the pump (6) is connected. 11. Liquid treatment device according to one of claims 1 to 11, characterized in that in the input line (5) a fourth check valve (24) is arranged, which opens to the pump (6) out, and between the fourth check valve (24) and the pump (6) a connecting line (25) opens to the disposal port (18), in which a check valve (26) is arranged. 12. Liquid treatment arrangement according to one of claims 1 to 11, characterized in that the permeate (10) is connected to a collecting container (12).