DE102006015673A1 - Small volume reverse osmosis plant with concentrate management - Google Patents

Abstract

In a method for operating a small-volume reverse osmosis system, in which a reverse osmosis module is supplied with raw water by means of a raw water inlet, of which a subset called concentrate via a concentrate outlet and another subset, filtered through a membrane and called permeate, via a permeate outlet from the Reverse osmosis module is brought out, the invention proposes that the water quality is monitored and a flushing process is automatically triggered when certain limit values are reached.

Description

The The invention relates to a small-volume reverse osmosis system, with a Reverse osmosis module, which has a membrane and a raw water inlet and a concentrate outlet, both on one side of the membrane arranged, and a Permeatauslauf, the reverse osmosis module on the other side of the membrane is arranged. To blockages To avoid the membrane must be rinsed regularly the reverse osmosis module or it must be permanent with a significant excess of water be operated so that the permeate yield in a very low ratio to used amount of raw water and the operation of the reverse osmosis system Accordingly, economically unfavorable. As a yield or also as an efficiency is the ratio of raw water used referred to usable permeate, z. B. 50%, if the used Raw water amount of 100% in 50% concentrate and 50% permeate divides. The relationship from discarded concentrate to recoverable permeate may be referred to as a wastewater ratio be in the above case, so 1: 1, which is the same yield designated.

A small-scale system is a so-called "point-of-use" system that is installed directly at the end user, eg in restaurants or private households, and that generates permeate volumes of about 20 l to about 1,000 l daily output Such a system is eg in the EP 0 567 751 B1 described.

ever According to the locally existing water quality is usually the reverse osmosis systems Water flow adjusted so that a blocking of the membrane is excluded. For this purpose, volume control must each on the individual circumstances the plants are set, for example, depending of membrane size, water temperature, water quality and similar Factors.

Of the Invention is based on the object, a generic reverse osmosis system To improve that this is the simplest possible installation allows with as possible little effort a regular flushing of the reverse osmosis module make sure and one possible achieved high yield.

in the Contrary to large-scale industrial used installations where the water quality is measured and where dependent from the measured values, the concentrate output by means of regulating valves is proposed, according to a much cheaper Design of the facilities allows. While the big industrialists Installations have significant flow rates would have comparable control valves namely according to laboratory standards exactly work to adapt to the small volume reverse osmosis system. In practice, it may be necessary or desirable to have a concentrate flow in the range of less than 50 ml / min, and the required Measuring and control technology would be in relation to Price of the rest Investment disproportionately expensive.

These Task is solved by a reverse osmosis system, in which the water quality sensory is detected and when certain limits are reached an automatic flushing triggered becomes. This is done z. B. by an already existing system control. In particular, electronic plant controls are in practice common, which z. B. serve, depending on the level of a permeate to turn the system on and off, or to trigger unreferenced rinsing, z. B. at predetermined time intervals.

Advantageous can the flushing process as a pulse rinse with a sudden change the flow rate or flow rate accomplished become. These changes as well as the resulting pressure fluctuations an intensive rinsing effect safe and a correspondingly reliable cleaning of the membrane.

With This proposed procedure makes it possible to control the concentrate flow the plant to a minimum limit, which is so low that it is not enough to the Plant to operate in continuous operation. By doing that regularly a rinse cycle is passed through, the membrane is cleaned regularly and before blocking protected, so that the functionality the plant as well as the advantageous high yield for a long time Time is ensured.

The For example, sensory detection of water quality can affect the quality of the concentrate. A concentrate sensor can be provided in the housing be, in which the membrane is arranged, for. B. on the membrane or integrated into the membrane. This proximity to the membrane ensures fast reaction Measurement results in the event of a change the concentrate quality.

A manufacturing technology particularly simple arrangement of the sensor, the no change at the reverse osmosis module itself may, in a line section take place, through which the concentrate is guided by the membrane.

In order to be able to carry out the measurement in such a line section without problems and with a meaningful result, it is advantageous provided to set a certain minimum flow of the concentrate as so-called Grundspülmenge, so that the relevant line section is always flowed through by concentrate and the measurement is not performed in a standing liquid in the quality changes can be detected only with great delay.

In addition can a sensory detection of raw water quality is done, so that a quality ratio between Raw water and concentrate taken into account can be.

For example can Measured values such as the electrical conductivity or other measured values the water quality and when certain limits are reached the rinse cycle triggered.

there the invention assumes that a loss of quality accumulated in a memory Permeate even then is not measurable, if the concentrate already a too low quality to allow further operation with this concentrate quality, for example, shortly before the first crystal formations take place. The timely flushing The reverse osmosis module thus ensures firstly the technical FITNESS the reverse osmosis module and in particular its membrane, and secondly the desired water quality of the permeate.

alternative to the above-described measurement of the concentrate quality can be provided be to perform a very accurate measurement of permeate quality. As in the aforementioned memory always mixed with already there existing permeate and the quality measurement done there accordingly lethargic is advantageous in measuring the permeate quality in the Membrane performed be, e.g. by a conductivity sensor integrated in the membrane, or it can be carried out on the membrane or in its vicinity. At ge ringsten impairments the permeate quality then the automatically initiated rinse cycle can take place.

The automatic adaptation of the system to the given local conditions can easily be done by referencing the permeate quality after such a rinse cycle is made, so that depends on the condition of the plant and the quality and temperature of the Raw water in each case individual quality values for the permeate are determined, which then as a reference for serve the further operation of the system.

When Another alternative when operating the reverse osmosis system may be the change the solved one Substances, that is the filter-out rate of the reverse osmosis system via sensors in the raw water and in the permeate, and in dependence from the determined ratio can the rinse cycle be activated automatically. Alternatively, the change the Ausfilterrate on the basis of comparative measurements of concentrate and permeate are determined.

Advantageous a user interface may be provided so that the operator the reverse osmosis system can set the limit for triggering the flushing serves, for. B. the height the maximum concentration in the concentrate, and so that the operator the reverse osmosis system can influence the duration of the rinsing phase. To this Way lets The reverse osmosis system by the user or at startup from service personnel to adjust to the local water hardness, which is another Optimization of the yield allows, therefore of the relationship of used raw water or discarded concentrate on the one Side and gained permeate on the other side.

Out the measured values for the permeate and the concentrate or for the permeate and the raw water, or for all three mentioned Measured variables can An evaluation of the filter effect can be carried out, which in percent or about one Threshold, for example, on a viewable for the user Display, can be specified.

through the proposed embodiment of the reverse osmosis system, it is possible to To put the system into operation without prior selection and compilation certain technical components to the respective site vote. It may rather be provided, if necessary, on site a certain hardness range to choose the raw water used. Subsequently The system always automatically adjusts to the best possible yield one.

Technically conditioning is economically advantageous that only a single flushing system for a wide Power range required by reverse osmosis systems, which is the cost of manufacturing and attitude at the manufacturer of the reverse osmosis plants significantly reduced. In addition, it will be for the Operator in economically advantageous way possible, clearly to achieve better yield values than with "rigid" set to certain operating conditions Attachments.

The cost of a proposal according to self-regulating, automatically rinsing triggering reverse osmosis system are, according to current economic conditions, hardly higher than a commercial reverse osmosis system with a standard automatic dishwashing and a Conductance comparator. Even with a tenfold increase in membrane performance, the basic configuration of the plant can remain unchanged as it automatically adjusts to the particular conditions. This tenfold increase in membrane performance can be made possible, for example, by using a housing design of the reverse osmosis module with different membrane inserts, ie with different sized effective membrane areas, which is also possible with currently commercial reverse osmosis modules. In the case of proposals designed according to this change, however, this change is particularly easy, without having to make a change or adjustment of the entire system.

For the manufacturer is advantageous that, for example, not 20 or more different Concentrate controller must be kept in order to deliver each one Reverse Osmosis System to the respective local water quality which is found at the customer.

One Another advantage of the proposed system is the automatic Adaptation of the plant to different raw water qualities and Raw water temperatures.

in the Unlike one on the local water quality made-ready, but "rigidly" assembled Facility, for example, by selecting and setting the respective concentrate controller such an adjustment has been made is, when operating a proposed system even with changing raw water quality Automatically adjust the system, depending on the respective circumstances in each case the flushing of the timely Reverse osmosis module takes place, so that in each case the optimal intersection point between as possible high yield on the one hand and possible high permeate water quality on the other hand.

embodiments according to the proposal Reverse osmosis systems are based on the purely schematic representations below explained. It shows

1 a simple plant,

2 a plant with a concentrate recycling, and

3 a plant with a permeate pump.

In the drawings is with 1 denotes a pre-filter, is conducted in accordance with the indicated arrow direction raw water, for example, from a public drinking water supply network. The filtered raw water reaches a raw water solenoid valve 2 , to a raw water sensor 3 and from there into a reverse osmosis module 4 , The raw water solenoid valve 2 is automatically opened and closed as required by means of an electronic system control.

Through the membrane of the module 4 permeate that has passed passes to a permeate sensor 5 and from there for further use. It can be used directly or stored in a memory.

At the reverse osmosis module 4 Concentrate, which is a concentrate sensor, also accumulates 6 happens and to a flow restrictor 7 which also acts as a pressure holding valve for the reverse osmosis module 4 serves.

A bypass line 8th The concentrate passes the flow restrictor 7 over to an outlet pipe 9 , provided a rinse water solenoid valve 10 is open. Basically, the flushing water solenoid valve 10 closed. It is automatically opened and closed by the system controller. The opened solenoid valve 10 allows the short-term outlet of larger amounts of concentrate, so that in a kind of pulse rinsing the reverse osmosis module 4 especially its membrane, can be rinsed.

Deviating from the illustrated embodiment, the solenoid valve 10 with the flow limiter 7 be summarized so that the required installation costs can be reduced.

In 2 is a plant shown, which basically like the plant of 1 is constructed, but with an additional pump 11 equipped to increase the pressure. This pump 11 increases the pressure in the reverse osmosis module 4 beyond the normal pressure of the public drinking water supply network. This makes it possible over the flow restrictor 7 the concentrate in front of the booster pump 11 due to the pressure prevailing in the drinking water supply network. In the reverse osmosis module 4 Therefore, a high flow can be generated without a correspondingly high consumption of raw water, so without correspondingly high water losses at the outlet 9 , Concentrate quality can be determined by means of the concentrate sensor 6 capture, so that at appropriate concentrate values by opening the Spülwassermagnetventils 10 a rinsing process can be initiated. The for this in 2 shown embodiment, plant control is compared to that for the embodiment of 1 usable plant control advantageous extended so that they control the pressure booster pump 11 includes.

3 shows a plant, as it basically with the plant of 1 is comparable. The permeate gets behind the permate sensor 5 in a permeate pump 12 , From this, the permeate is in an accumulator 13 promoted. When the permeate is used, it passes through a postfilter 14 in which it is post-treated and then from a withdrawal tap 15 can be removed under pressure.

To drive the permeate pump 12 the energy, in particular the pressure, of the concentrate is used: a membrane 16 separates a concentrate chamber 17 within the permeate pump 12 from a permeate chamber 18 , For controlling the permeate pump 12 serve control valves 19 and 20 , These are mutually, namely position-dependent on the position of the membrane 16 , controlled. On the part of the permeate chamber 18 serve the pump valves 21 and 22 as check valves for conveying the permeate into the storage tank 13 ,

That through the membrane in the reverse osmosis module 4 entered permeate fills the permeate chamber 18 the permeate pump 12 , wherein the permeate through the pump valve 22 into the permeate chamber 18 arrives. The membrane 16 the permeate pump 12 is doing to the left, so in the concentrate chamber 17 into, distracted. The control valve 19 is closed at this stage. The control valve 20 however, it is open so that the increasing amount of permeate within the permeate pump 12 the concentrate from the concentrate chamber 17 to the outlet pipe 9 repressed.

By reversing the valves 19 and 20 this process is terminated when the membrane 16 has reached its intended left deflected end position. For this purpose, a sensory connection between the valves 19 and 20 on the one hand and the membrane 16 be provided on the other hand. Because the valve 20 now closed and thus the connection to the outlet 9 is interrupted, concentrate flows through the open valve 19 into the concentrate chamber 17 the permeate pump 12 , The membrane becomes 16 pushed back from its maximum left deflected position to the right. That in the permeate chamber 18 accumulated permeate is thereby through the pump valve 21 expelled from the permeate pump and flows into the storage tank 13 , This process lasts until the membrane 16 was moved to its right-deflected end position and the permeate from the permeate largely conveyed out and into the storage tank 13 is encouraged. Subsequently, when the valves 19 and 20 again reversed and the above-described filling of the permeate 18 , at the same time the emptying of the concentrate chamber 17 , starts over.

The above-described processes can basically be repeated until the pressure in the storage tank 13 has reached the inlet pressure of the water supply, ie the public drinking water supply network, or until the supply to the reverse osmosis module 4 via the solenoid valve 2 is closed. The solenoid valve 2 can for example via a pressure switch 23 be controlled. As the effective surface of the membrane 16 to the two concentrate and permeate chambers 17 and 18 is the same amount, the same amount of concentrate is released as the permeate in the storage tank 13 is encouraged. This concentrate flow allows the concentrate quality at the concentrate sensor 6 capture.

Claims (10)

A method for operating a small-volume reverse osmosis system, wherein a reverse osmosis module is supplied by a raw water inlet raw water, led out of which designated as a concentrate subset of a concentrate effluent and another, filtered through a membrane us as permeate designated subset of permeate effluent from the reverse osmosis module is, characterized in that the water quality is monitored and automatically a flushing process is triggered when certain limits are reached. Method according to claim 1, characterized in that that the water quality of the concentrate is sensory detected and upon reaching a predetermined limit of the flushing process automatically triggered becomes. Method according to claim 1, characterized in that that the water quality of the raw water and the concentrate is detected by sensors and upon reaching a predetermined difference value of the flushing process is automatically triggered. Method according to claim 1, characterized in that that the water quality the permeate is detected by sensors and upon reaching a predetermined Limit value of the rinsing process automatically triggered becomes. Method according to one of the preceding claims, characterized characterized in that for determining the water quality of the electrical conductivity the water is detected. Method according to claim 5, characterized in that that an automatic referencing of permeate quality made after at least the reverse osmosis module of the reverse osmosis system by means of a rinsing cycle was cleaned. Method according to one of the preceding claims, characterized characterized in that the determination of water quality change the Ausfilterrate the reverse osmosis system via sensors in the raw water and in the permeate is compared. Method according to one of claims 1 to 6, characterized that for determining the water quality, the change in the Ausfilterrate the reverse osmosis system via sensors in the concentrate and in the permeate. Method according to one of the preceding claims, characterized characterized in that the rinsing process as a pulse rinse with a sudden change the flow rate or flow is performed. Small-volume reverse osmosis system, with a reverse osmosis module, which has a raw water inlet, a concentrate outlet and a permeate discharge, characterized by sensors ( 3 . 5 . 6 ), which detect the water quality according to any one of the preceding claims, as well as by a system control, which automatically triggers the flushing process according to one of the preceding claims, and by an operable by a user and effectively connected to the plant control interface, by means of which the height of the triggering the purge operation serving limit and the duration of the purge phase can be influenced.