CH662553A5 - Process and device for purifying water, using ozone produced from oxygen-rich gas - Google Patents

Abstract

The water is treated with ozone mixed with oxygen gas and a fraction of the oxygen not absorbed by the water is recirculated to the ozone generation. Before the addition of the ozone, it is brought into solution in a part-stream of the water to be purified from which the dissolved nitrogen has been expelled. The device serving for carrying out the process has an oxidation reactor (22), an ozone-generation apparatus (10), an oxygen source and a recirculation line (11) for oxygen-rich gas connected to the ozone-generation apparatus. The device further has an ozone-enriching absorber (7), and a nitrogen-expelling desorber (4). <IMAGE>

Description

The invention will now be explained in more detail with reference to the attached drawing, which shows a circuit diagram of the device according to the invention as an exemplary embodiment (the flow directions are indicated by the arrows drawn on the lines).

The water to be cleaned (to be treated with ozone) enters the device via a line 1, is pressed into the upper part of a desorber 4 used to expel the nitrogen using a pump 3 installed in a line 2.

The desorber 4 is a cylindrical standing container, in the interior of which the operating water level is designated by the reference letter v. The desorber 4 is only flowed through by a partial stream of the entire amount of water to be cleaned (to be treated with ozone). In the lower part of the desorber 4, a gas distribution head 5 is installed, which is connected to a gas line 6. This gas line 6 is led out of the upper part of an absorber 7, which serves to dissolve and enrich the ozone generated from oxygen-rich gas.

An absorber 7 is also only flowed through by a partial flow of the entire amount of water to be cleaned (to be treated with ozone) which has already been mentioned (here, too, v denotes the water level). In the lower part of its cylindrical container, a gas distributor head 8 is provided, which connects to a further gas line 9.

The gas line 9 emerges from an ozone generator 10 below and passes on such an ozone-rich gas mixture to the absorber 7, which contains, for example, 65% oxygen. In the absorber 7 the ozone is left - more precisely: its predominant part, e.g. B. about 95% - absorb by water.

Because the ozone dissolves in the water much faster than that

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Oxygen, a large part of the latter is "exhausted" with the remaining ozone and together with some nitrogen and escapes via line 6.

From the absorber 7, the smaller part of the oxygen-rich gas which has not gone into solution - as already mentioned - is passed via line 6 into the desorber 4, i. H. it is blown off to reduce the nitrogen content of the recirculated gas. With the oxygen in desorber 4, the major part of the nitrogen is namely expelled from the water, so that the water fed from the desorber 4 via a line 27 into the absorber 7 contains practically no or hardly any nitrogen. Accordingly, the smaller part of the blown-off oxygen-rich gas leaving the desorber 4 was used to expel the nitrogen from the partial flow of the solution water, while the larger part of the gas mixture is recirculated to the ozone development apparatus 10 via a line 11. This means that the gas recirculated via lines 6 and 11 to the ozone developing apparatus 10 mainly contains oxygen and ozone which is not dissolved (approx. 5%) in the absorber 7, i. H. is excellent for generating ozone.

The dissolving of the ozone in the partial flow enables, according to the above, the loss through the - already mentioned - dissolving of oxygen in water, as well as the amount of nitrogen introduced into the oxygen circulation system with the water to be purified. A further reduction in the amount of nitrogen is that a nitrogen expulsion is carried out beforehand in the desorber 4, which can be increased even further if ozone-treated water is already used to dissolve the ozone.

We now come back to the drawing, where from the desorber 4 the nitrogen-rich gas is passed outside via a line 12, while to the gas mixture recirculated via line 11 from an oxygen tank 13 via line 14 - in the required amount - the supplementary Amount of oxygen is added. The gas enriched with oxygen in this way is subsequently pressed into the ozone generator 10 via a line 15 with the aid of a compressor 16 via a droplet separator 17, a cooler 18 and a dryer 19, and ozone is again generated from this (this is cooling and drying necessary because the oxygen is passed between two electrodes to generate ozone).

From the absorber 7, the ozone-rich water (ozone solution) - this partial stream contains the ozone corresponding to the entire amount of water to be treated - is passed via a line 20 into a mixer 21 which is built into the line 1. With the help of the mixer 21, the ozone solution is distributed in the main stream of the water to be purified arriving via line 1; then the main stream is passed into an oxidation reactor 22. This creates and ensures the preconditions for the interaction of the impurities in the water to be cleaned and the ozone generated from the oxygen-rich gas. The gases exiting in the oxidation reactor 22 are then blown off via a line 23.

The above in summary: The use of the ozone produced from oxygen-rich gas is carried out with the conventional ozone admixing devices in three stages, namely:

Nitrogen desorption; Expulsion

Ozone absorption; enrichment

Oxidation in the reactor.

As a result, the ozone required for cleaning is dissolved in a partial stream of the water that was previously made low in nitrogen, but the ozone solution is used for the oxidative treatment of the main water stream.

We now return to the drawing; The following is to be said in this regard: the cleaned water leaves the oxidation reactor 22 via a line 24, in order then to be fed to a place of use via a discharge pipe 25. At point a of the pipe 5, a pipe 26 is branched off, which opens into the pipe 2 in front of the pump 3. This connection makes it possible to use not the partial flow of the water to be cleaned, but rather the already cleaned water, possibly a partial flow consisting of an OK mixture of water to be cleaned and already cleaned, for nitrogen expulsion or for ozone enrichment. Of course, the system contains a necessary number of shut-off and control fittings. However, these were not shown in the drawing for the sake of clarity.

15 Determining the technological parameters for a specific process is a technical-economic optimization task. These parameters depend on the following factors: quality of the water to be treated; a specific ozone requirement; Concentration of the oxygen produced in the oxygen generator 20; Type of gas treatment; Type of ozone generator; Size of prices for electrical energy and for ozone generation; Temperature of water; Height of absorption and desorption columns etc.

As an example it should be mentioned that for the ozone treatment of max. 25 20 ° C water and its average ozone requirement of 3 gl m3 ozone from a gas with 85-90 vol .-% oxygen content, an ozone produced with 40-60 g / m3 gas concentration is dissolved in a 20-30% partial flow of purified water when the height of the liquid column in the ozone enrichment 30 absorber is 5-6 m. In this case, the gas leaving the enrichment has 2-4% ozone, which must be expected as a loss. The ozone loss can be reduced to 1-2% by connecting two absorber columns, e.g. B. using existing Ozonmi-3 shears. The use of enrichment columns connected in series is not uneconomical, since the dimensions of the columns are only determined by the absorption processes; in contrast to the conventional ozone admixture, where the oxidation processes dominate.

4t For new systems, it is advisable to increase the height of the accumulating liquid columns, as this can also reduce nitrogen contamination. If the height of the liquid column increases downwards - hence a so-called absorption well is used - hydraulic losses are not to be expected. The ozone decomposition occurring in the solution can also mean a certain loss of ozone, but this can be kept below 3% by lowering the pH value of the partial flow (e.g. pH = 6.5). At lower water temperatures (e.g. below 10 ° C) there is no need for this.

In the absorber 7, the oxygen concentration of the recirculated gas decreases by 2-3%, since oxigen dissolves in the water. For this reason, 10-20% of the gases leaving the absorber 7 must be blown off, so that after the 55 blown-off gas has been supplemented by a gas with an oxygen content of 90-95 vol to be able to feed the ozone developing apparatus 10.

An essential advantage of the invention is that it enables water purification with the ozone generated from oxygen-rich gas 60 to be carried out much cheaper than with the previously known processes serving the same purpose, since according to the invention the cost of using conventional ozone admixing devices Ozone water treatment and the ozone generation can be brought closer to each other at most 65.

Of course, the invention is not only limited to the implementation of the method, for example, or only to the embodiment shown, but it

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can also be implemented in numerous other ways within the scope of protection defined by the claims.

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1 sheet of drawings

Claims (9)

662 553 2 PATENT CLAIMS Solution of special tasks (e.g. cyan oxidation) added to them. Ozone is explosive, that's why it becomes like 1. Method for purifying water using customary at the place of purification - in the wastewater treatment plant of ozone produced from oxygen-rich gas, at which - generated. ozone mixed with oxygen gas in the water to be treated ozone is generally obtained from the air or passed out and a fraction of the oxygen-rich gas not absorbed by the water is generated. The latter of course means Oxygen portion for ozone production is recirculated, thereby additional costs, since the oxygen costs money, while the air indicates that the ozone is available in unlimited quantities before it is added to the free; on the other hand, treating water in such a partial flow from purifying ozone can be produced from oxygen at a lower price than oxygen from dissolved and / or purified water, evasive air. As a result of the ever more rational technology of the oxygen gas generation previously blown off from the oxygen recirculation system, the oxygen itself, the oxygen-containing gas, becomes the nitrogen dissolved in the water, or cheaper, and has at least largely eliminated the generation of ozone from oxygen gas. increasingly in the foreground. 2. The method according to claim 1, characterized in that, as is known, by increasing the oxygen content of the approximately 20-30% of the total water to be purified, 15 the gas used for ozone development frees the capacity of the ozoners - the partial stream of nitrogen and for dissolving and Incentive system to be expanded, also the concentration near the ozone is used. of the ozone generated in the gas, while the specific energy 3. Device for performing the method can be reduced after the cost of ozone generation. Thus, claim 1 or 2, which are an oxidation reactor, a ten as a result of these factors, the investment ozone generator, an oxygen gas source, a connected to the 2o and operating costs for gas treatment, ozone generation and ozone generator are reduced equally for ozone water treatment, Oxygen-rich gas and a line for introducing the water. In the known solutions, however, the water that purifies the water can have, characterized in that it introduces oxygen that has not been converted into ozone via an ozone-enriching absorber (7) and a nitrogenous committee that in the water with the ozone in solution, does not have a driving desorber (4), the 25 being recovered in the desorber (4) and therefore appears clearly as to introduce the partial flow of cleaning and / or loss, nevertheless in certain cases - e.g. B. in the wastewater clean water serving line (2) opens, and a nigung- a saturation with oxygen of the water desired - for forwarding the nitrogen-free partial stream could be worth. The tube (27) serving from the water treated with ozone absorber (7) is led out, while in exiting oxygen is due to other gases present in the water to the absorber (7), which is released from the ozone generator (10) 30 - especially emerging, a mixture of ozone and oxygen gas contaminated here by nitrogen, so that the exiting gas is introduced into the forwarding tube (9), furthermore that from this form are not reused for ozone generation Absorber (7), the recirculation line (6, 11) can be led out. from which the line (6) for feeding the oxygen-free TT. . , ",, ,,. , • 1. • j TN 1. fA \ i_. For this purpose, the water must be branched off into the desorber (4) before the ozone treatment, as well as 35 ^,, “,,.,, ,,. ,, ö j • j- t / 1N. y? ,,,, are degassed. The then excreted-practically pure that into line (l), which feeds the c 0 to be treated, “,, ~ r .... wi ■ a nV ',. . . ... A oxygen gas can then be recirculated to generate ozone Water m the oxidation reactor (22) serves, em with the Aus,, UD. ... ..,,. . ,. , T * • «. 1 v «mj au 1- / n \ x. j t. , ■, / 01N, but this is a rather expensive technical solution, tnttsleitung (20) of the absorber (7) connected mixer (21) T • ^,; f. , 0 w v 'Read the excreted ozone water treatment £ 1TÌP £ h /) Uf icf 0 0 B.. , 1 . . ,,. recycle gases without prior degassing, then - 4. EinnchtungnachAnspruch3, characterized, 4 ° 0 °? ,,. jj TN u / a \ jj au u / "7 \ 1 i- j • 1. by replacing only the gas used for ozone development - that the desorber (4) and the absorber (7) as cylindrical".,.,. . "0. ..., \ ... ^. ,. , rv 'J ..,. . Composition of the recirculated gas sooner or later Standing containers are formed, in the interior of which the “0,. T 1. j , * - *. * <. ** _ • u u become identical with the composition of the air. to feed oxygen-rich gas or ozone- D1 ...,. ,, T ■■ u •,,. • u j- j% v n \,,, A solution is also known in which the lines (6, 9) serving to rich gas are from top to bottom. , ,,,. , ...,. , 0, " r> •, j n * j • !. , t-, .. cleaning water not directly with the ozone Area of the container bottom, and at its lower end 4a 0. ., ... ". ... "- / - e- o \ u • ozone-containing gas is treated, are provided with a gas distribution head (5 or 8). 5 j ^ A. 0 TT uj 1 u \ J. A uij / jj vi -u but first the ozone in a wet high pressure absorber 5. Einnchtung according to claim 3 or 4, characterized gekennzeich-. ,. , ,, .... . . ,. ,. j, y. . j. . enriched, but then cleaned with ozone solution. On net that from the line (24,25) for the derivation of the cleaned- 0. ,,. .,, ö,. . "J j" 6 \ J ',,. t this way, the enricher can th water from the oxidation reactor (22) a line (26) jj. ,, A u j 1,, v, T / oN o - j of the corresponding absorption pressure - also without branching, which m the line (2) for feeding the 50 ® "" .., a m «i, • 5 ^ u fA \ ■ ..,. Blowing off a gas of 90-95% oxygen content, the nitrogen-free partial stream recovered, flows into the desorber (4). , ", TT uj t u ^ °, w be. But the high pressure absorption is the odd thing Dirty water cleaning systems foreign. In addition, this is a very energy-intensive process, requires large invers ~ _ £ - j,. rr. ■, 7 _r u JT- • u stitions, and in the compression of the ozone-containing gas The invention relates to a method and device for 55 ... I. ",; ,. . , b, n. . "F. -t /, ° rr. the total losses cannot be avoided either. Purification of water using oxygen-free ^ r. ,. ^, ... ^, ... , “0 The aim of the invention is to address the above-mentioned deficiency to ehmi-chem gas produced ozone. . kidney As is known, ozone is used in the Water treatment practice - actually the most powerful oxidizing agent. According to the invention, the object is achieved by solving the contaminants 60 present in the water that the ozone reacts before it is added to the one to be treated, breaks down the organic substances and the water in one such partial flow from to be cleaned and / or living organisms kills. The ozone improves the quality of the purified water from which it is previously dissolved Drinking water increases its enjoyment value, so that the ozone-depleted oxygen-circulating action blown off oxygen-containing action in the different phases of drinking water purification gas, or at least its often used. In the last technological phase 65 predominant part was expelled, ozone treatment can also be used for wastewater treatment. The invention is based on the following knowledge: are used (for disinfection, tertiary cleaning). A part of the excreting gases is derived, and also When industrial wastewater is cleaned, ozone is replaced by oxygen, so that recirculated water can ten gas, the oxygen concentration can be kept practically at any value. On the other hand, as the oxygen concentration increases, the ozone generation costs decrease, but the blowdown gradually increases, and hence the oxygen costs. The oxygen concentration thus has an optimum at which the water treatment by ozone is carried out at the lowest cost. This optimum concentration is around 60-70%. On the other hand, the optimum of ozone generation - where the specific energy consumption is the lowest, but the ozone production per tube and the ozone concentration is the greatest for a given gas speed, discharge voltage and equipment parameters - between 90-95%. From this it follows that the possibilities for rationalization are far from exhausted and that the savings through ozone extraction from oxygen-rich gas in water and wastewater treatment can be realized if we optimize the cost of ozone-water treatment and ozone generation using the conventional ozone mixing devices can bring each other closer. Another finding is that ozone dissolves in water much better than oxygen, it is sufficient to have the ozone-gas mixture only absorbed by a part of the water to be treated. Because while the majority of ozone (approx. 95%) goes into solution in this partial amount (this partial stream), a much smaller amount of oxygen is converted into water solution: as if the oxygen-gas mixture had been added to the entire amount of water to be treated. So there is a large amount of - not absorbed - oxygen present in the gas blown off from the partial flow. On the other hand, we considered that any natural water absorbs significant amounts of nitrogen from the air. In other words: With the water to be treated, nitrogen also gets into the ozone water treatment system. This is disadvantageous because the nitrogen dilutes the oxygen gas, which requires oxygen-rich gas to generate ozone (as already mentioned, in extreme cases the concentration of the gas mixture can match that of the air, so much it is diluted. This is only a question currently). Another gas is required to purge the nitrogen. The nitrogen can already be distributed in the gas phase formed by the other gas, i. H. A large part of the nitrogen gas can pass from the aqueous phase into the gas phase formed by the other gas. This other gas cannot be air, since it also contains nitrogen, which would keep the equilibrium with the nitrogen of the gas mixture to be used for the generation of ozone. Another cheaper gas (e.g. methane or carbon dioxide) cannot be used in part because these gases could get into the drinking water, which is not permitted. On the other hand, the presence of extraneous gas would also interfere with ozone generation. However, if one were to "sacrifice" part of the oxygen gas in the system - which is basically intended for ozone generation - to drive off the nitrogen, the water treatment with ozone can be carried out and secured at an optimal cost. The object is thus achieved with the aid of a method in which an ozone mixed with oxygen gas is allowed to enter the water to be treated, and a fraction of the oxygen gas not absorbed by the water is recirculated to produce ozone. The essence of the invention is that the ozone is added to the water to be treated (purified) in such a partial flow of the water to be cleaned and / or purified, from which the oxygen-containing gas blown off from the oxygen circulation system previously releases the ozone solved 662 553 Nitrogen or a predominant part of it has been driven off. According to an advantageous implementation of the method according to the invention, a partial flow of approx. 20-30% of the entire water flow to be cleaned is used to remove nitrogen and to dissolve (enrich) the ozone. The inventive method can be carried out by a device which an oxidation reactor, an ozone generator, an oxygen gas source, for. B. a gas bottle, further for the oxygen-rich gas, a recirculation line connected to the ozone generating apparatus, and a line to let the water to be cleaned get into the treatment device. The essence of the facility is seen in the fact that it has an ozone-enriching absorber and a nitrogen-expelling desorber. The tube for supplying the partial flow for the water to be cleaned and / or cleaned opens into the desorber, preferably in the upper part thereof, and advantageous from the lower part is that in the absorber of the nitrogen-free partial flow, advantageously in the upper part thereof. led out pipe. The tube emerging from the ozone generating apparatus and passing on a mixture of ozone and oxygen gas is introduced into the absorber. The recirculation line, from which the line for feeding the water to be treated into the oxidation reactor, is led out of the absorber, and a mixing element (wiper apparatus) connected to the absorber outlet line is installed. In an advantageous embodiment, the absorber and desorber have the shape of standing cylindrical containers, and the tubes that extend into them and are used to feed oxygen-rich or ozone-rich gas down from the top to the bottom of the container, but are each provided with a distributor head at the bottom. Such an embodiment is also possible, in which such a line branches off from the line for the discharge of the purified water from the oxidation reactor and opens into the pipe for feeding the partial stream to be freed of nitrogen into the desorber.