WO2011125081A1

WO2011125081A1 - Methods of scale inhibition with gaseous mixtures comprising c02

Info

Publication number: WO2011125081A1
Application number: PCT/IT2010/000460
Authority: WO
Inventors: Antonino Schillaci; Lucio Piticchio
Original assignee: Antonino Schillaci; Lucio Piticchio
Priority date: 2010-04-09
Filing date: 2010-11-17
Publication date: 2011-10-13
Also published as: IT1399667B1; EP2556034A1; ITRM20100170A1

Abstract

A process for treating water to prevent the formation of concretions and encrustations caused by the minerals present in water circulating in plumbing of any type and/or in wells, as well as to eliminate possible encrustations that might present at the start of treatment, basically envisages the addition in solution, in gaseous form, of CO2 or of an appropriate CO2 -based mixture of gases,- thus obtaining that the gases dissolved in water give rise to a chemical reaction, with the minerals contained therein, designed to: render soluble the calcium/lime, and other minerals, and thus obtain a reaction that produces water-soluble calcium carbonate or calcium bicarbonate; transforming some metals into corresponding hydroxides; and stabilizing the active oxygen, inhibiting the formation of mineral precipitates.

Description

METHODS OF SCALE INHIBITION WITH GASEOUS MIXTURES COMPRISING C02

INTRODUCTION

The present invention relates to a new applicational process, which exploits the chemical reaction of the mixture of technical gases in water, such as, by way of indicative and non- limiting example, He, N, Ar in a C0₂ base. The mixture, which is made up of percentages that vary according to the type of application, is dissolved in water to inhibit formation of mineral precipitates and prevent formation of concretions and/or encrustations.

PRIOR ART

Available on the market are various types of decalcifiers or anti-lime agents, both physical and chemical ones .

Amongst these, we shall recall for example [?LA LISTA CHE SEGUE NON E¹ COERENTE, IN QUANTO NEI PRIMI DUE PUNTI NON ELENCA "DECALCIFICATORI 0 ANTICALCARI " ] : o filtration with salts;

o dispensing of polyphosphates ,- o magnetic and electronic anti-lime agents.

Carbon dioxide is commonly used in the food sector, especially for the production of water-based beverages. In addition, another three gases, He, N, Ar, are commonly used in different health and industrial sectors, especially in the canning industry.

Also known is an application of C0₂ in the sector of maintenance of artesian wells, said application exploiting the cryogenic properties and the properties of expansion in volume of C0₂ when it goes into the liquid phase to remove from the lining tube of the well, in the section that comes into contact with the water of the underground aquifer, the concretions via freezing, unfreezing, and expansion to cause cracking and yielding of the calcified crusts.

The purpose of the present invention is to provide a process for treating water to prevent formation of sediment and encrustations caused by the minerals present in the aquifer water in wells, in water in tanks, and in water circulating in plumbing systems of any type, as well as to eliminate any possible encrustations that might be present at the start of treatment .

The above has been obtained, according to the invention, by providing a process that envisages the use of an appropriate mixture of the gases dissolved in the water to be treated, the chemical reaction of which with the minerals contained therein is designed to:

rendering the calcium/lime, and other minerals, soluble and thus obtaining a reaction that produces water- soluble calcium carbonate or calcium bicarbonate;

transforming some metals into corresponding hydroxides; and

stabilizing the active oxygen inhibiting formation of mineral precipitates.

According to the invention, said result is obtained by the reaction of an appropriate C0₂-based mixture of gases, which dissolved in water produces carbonic acid H₂C0₃, which transforms the calcium into soluble bicarbonate HC0₃. Furthermore, the weak acid produced, sustained with the balanced mixture of the other gases, transforms the metals into hydroxides M(OH)_n, (where n is the number of anion groups) and saturates the water by stabilizing the active oxygen inhibiting oxidation and formation of precipitates and hence of encrustations.

According to a peculiar characteristic of the invention, the process is applicable in the following cases :

in wells, tanks, lines and plumbing systems for water for human consumption: with the use of non-toxic technical gases or superior gases based on CC½ for alimentary use;

in process water: in the environmental and industrial sector, for the maintenance of wells and lines, systems, etc., also with C0₂~based technical gases recovered from industrial activities and re-used (CCS - Carbon Capture and Storage) .

For confirmation of the repeatability of laboratory experiments and of the operative feasibility, an experimental feasibility test was conducted in the most critical of conditions, i.e., within a well for reclamation of aquifer waters, in the presence of waters contaminated by dissolved and/or suspended organic and inorganic compounds and where on the lining of the well there were already present considerable calcareous concretions and encrustations with iron, manganese, sulphates, and various metals.

The results of the feasibility test were verified: a) by gathering the chemico-physical parameters recorded continuously throughout the column of water of the well, via a multi-parametric probe equipped with data logger; the data representing the evolution of the process appear in Tables 1, 2 and 3; and

b) with video-inspections, to observe and verify visually the chemico-physical modifications detected on the walls of the well and of the lines of the delivery pipes, as well as in the body of the pump.

DESCRIPTION OF THE TEST

As mentioned above, a feasibility test was conducted in three steps, in the most critical of conditions, i.e., within a well for reclamation of aquifer waters, underlying a petrochemical industrial area close to the sea, with lithology of the formation of the aquifer represented by sands with a base of calcareous compounds, in the presence of intrusion of high-conductivity sea water.

The aquifer waters were contaminated by dissolved and/or suspended organic and inorganic compounds and minerals, which precipitate following upon release of the active oxygen, with lamination during traversal of the filter and on account of the centrifugation in the pump, creating concretions and encrustations, which involve onset of critical factors in terms of management of the systems .

In the course of Step 3 of the test, after application of the gas mixture optimized following upon the results of the preliminary step, the stabilization in the well of the pH at a mean value of 5.5 was noted, with crystalline transparent waters that were stable over time. Preliminaries of the feasibility test

The initial laboratory test was conducted at the test bench for testing the submerged pumps with the use of CO₂. In fact, initially the test was aimed at prolonging the duration in operation of the pump in the presence of water having chemico-physical characteristics such as the ones shown in Table 1 below. The test aimed at defining the calibrations necessary for creating the conditions of weak acidity with pH 5 to 6 and the reduction of the working temperature below 20 °C in an attempt to reduce the free oxygen and thus obtain a reduction of the calcium precipitates and encrustations.

In the course of the bench test, it was in effect possible to achieve the two targets of pH and temperature, but with a major dispersion of C0₂ and frequent cavitation of the pump. In fact, the test was conducted in a basin practically at atmospheric pressure so that at the minimum pressure of delivery of the gas cylinder (2 to 3 bar) the C0₂ administered bubbled free in the water.

Since to obtain an ideal solution of C0₂ in water operating conditions are necessary with a pressure of approximately 2 to 3 bar, it was decided to proceed with the test in a well that would guarantee said operating conditions, as described hereinafter.

From the preliminary test it may be inferred that, given the multiplicity of the chemico-physical parameters - which cannot all be determined with chemical analyses and laboratory tests - in the absence of data covering a sufficient number of cases, gathered in the course of further experimental and operative applications, the determination of the quantity and quality of the mixture must be made in a preliminary operating step with start-up of the treatment system.

Once the process has been calibrated, the control is entrusted to a purposely provided automatic mixing and delivery system, which will adapt the correction factor of the gas to be administered to the parameters of desired quality of the water to be supplied.

Prior to the start of the test in the well with the administration of C0₂, reference measurements were made via video-inspection and via measurement of the chemico-physical parameters with a multiparameter probe, presented hereinafter.

The aquifer water was sampled by taking it from the delivery line, and the pH and the oxidation times were then measured.

Table 1 below gives the data regarding the measurement made in the aquifer water in the well prior to start of the administration of CO₂, started on the same day.

Table 1

/07/0910:50:00

SA8060- 014.3 6.009ra 23.27°C 1.373mS 6.895pH -233.lmV -0.009ppm 19.9NTO/07/0910:50:00

SA8060- 014.3 7.005m 23.26°C 1.395mS 6.494pH -210.8mV -O.OOSppm 20.9NTU/07/0910:50:00

SA8060- 014.3 8.002m 23.25°C 1.417mS 6.356pH -204.8mV -0.005ppm 17.7NTU/07/0910:51:00

SA8060- 014.3 9.004m 23.24°C 1.438mS 6.486pH -216.0mV -0.003ppm 17.2NTU/07/0910:51:00

SA8060- 014.3 10.001m 23.23°C 1.456mS 6.402pH -213.5mV -0.003ppm 15.7NTU/07/0910:51:00

SA8060- 014.3 11.013m 23.21°C 1.473mS 6.327pH -211.6mV O.OOOppm 24.6NTU/07/0910:52:00

SA8060- 014.3 12.014m 23.21°C 1.488mS 6.325pH -211.5mV O.OOOppm 18.8NTU/07/0910:52:00

SA8060- 014.3 13.000m 23.19°C 1.502mS 6.330pH -213.3mV O.OOOppm 48.6NTO/07/0910:52:00

SA8060- 014.3 14.011m 23.19°C 1.516mS 6.349pH -211.2mV O.OOOppm 35.2NTU/07/0910:52:00

SA8060- 014.3 15.015m 23.17°C 1.528mS 6.359pH -193.7mV O.OOOppm 29.3NTU/07/0910:53:00

SA8060- 014.3 16.003m 23.14°C 1.538mS 6.373pH -183.5mV 0.003ppm 25.ONTO/07/0910:53:00

SA8060- 014.3 17.005m 23.07°C 1.557ms 6.373pH -182.6mV 0.003ppm 25.0NTU/07/0910:53:00

SA8060- 014.3 18.010m 23.04°C 1.575mS 6.373pH -187.lmV 0.003ppm 23.5NTU/07/0910:54:00

The level represents the column of water above the probe; to indicate the level with respect to the well mouth it is necessary to add 9.50 m.

Step 1 of the test with just C0₂

Application: Administration of C0₂ at 2 to 3 bar 3- 5 lt/min at approximately 50 cm below the pump and in the pump body. Duration of the test: approximately 1 month .

As already mentioned, the primary target of the test was initially to prolong the life of the pump.

Hence, the first application of administration of C0₂ was made in two points in the proximity of the intake of the pump, at approximately 3.5 m from the dynamic piezometric level, equivalent to approximately 13 m (3.5+9.5) from the mouth of the well.

There may be noted an appreciable modification of the chemico-physical parameters of the aquifer water in the proximity of and above the point of administration of C0₂, in particular the pH, oxygen, and the turbidity, as emerges_, from the table below.

Table 2 below gives the data, highlighted in which is the appreciable modification - after 5 days - of the chemico-physical parameters of the water of the area affected by introduction of C0₂ and of the overlying column of water.

Table 2

17/07/0909:35:00

SA8060- 014.1 13.006m 22.37°C 24.988mS 6.755pH -333.8mV 0.537ppm 4.6NTU 17/07/0909:36:00

SA8060- 014.1 14.005m 22.34°C 25.274mS 6.748pH -335.9mV 0.537ppm 4.6NTU 17/07/0909:36:00

SA8060- 014.1 15.006m 22.29°C 25.516mS 6.661pH -338.OmV 0.538ppm 4.6NTU 17/07/0909:37:00

SA8060- 014.1 16.001m 22.18°C 27.683mS 6.593pH -341.9mV 0.530ppm 5.1NTU 17/07/0909:37:00

SA8060- 014.1 17.003m 22.13°C 30.883mS 6.518pH -355.2mV 0.530ppm 5.INTO 17/07/0909:38:00

* The level represents the column of water above the probe; to indicate the level with respect to the well mouth it is necessary to add 9.50 m.

After a few days of administration in the proximity of the intake of the pump, the video- inspections revealed positive effects in the filter lining of the well but not as much in the pump, which was the main target. In fact, the images acquired show how in the area affected by the administration of C0₂ the lining is clean and how the encrustations increase proceeding downwards.

Said initial results, highlighted on the filter lining of the well, did not extend in a similar way to operation of the pump and in the water-delivery lines, even though the encrustations had lost consistency with respect to before, giving rise to a pasty material made up of sulphates, iron, manganese, and other metals.

The lack of benefits in operation of the pump, which can be attributed also to a possible cavitation of the suction body consequent upon introduction of the gas in the proximity of the intake, induced us to pass to a second testing step.

The samples of water taken from the same sampling point did not present any appreciable improvement either visually or as regards the parameters monitored in the preliminary sample.

Step 2 of the test with three points of administration of the CQ₂+N+He mixture

Application : base of 80% C0₂, plus a balanced mixture of gases: 10% He, 10% N. Mixture administered at 3 bar, 3-5 lt/min for each of three equidistant points along the vertical of the well.

Step 2 had the following targets:

involving as large a surface as possible of the well lining;

preventing cavitation of the pump; and

stabilizing the solution and causing reaction with the minerals that deposit in the pump body to solubilize them and prolong the life of the pump itself, with addition of N and He.

As points of introduction of the gaseous mixture we considered three equidistant sections of the column of the well: one at the well bottom, at approximately 30 m from the plane of site, one at approximately 2/3 of the column of water at approximately 22 m, and a third one at approximately 15 m from the plane of site so as to exploit the rising current of the solution of C0₂ in water towards the intake of the pump.

The results of the video-inspection showed how at the level at which the administration is made throughout the stretch up to where the chemical reaction of the carbonic acid (H₂CO₃) is still active, the lining of the well became increasingly cleaner with the passage of time, at the end it was cleaned completely. In addition to this, it has been found that in the stretch where the chemical reaction is already exhausted or else in the case where the administration of the mixture of gases has been interrupted, the formation of concretions starts again, confirming that for an effective reaction homogeneous distribution of the mixture is necessary. The mixture must hence be balanced and in an amount calculated as sufficient for the reaction, which is to be determined with a preliminary test, according to the chemistry (i.e., the chemical characteristics) of the waters to be treated.

Following upon the aforesaid administration of gaseous mixture, operation of the pump was slightly prolonged, some improvement being encountered owing to a further loss of consistency of the pasty material that deposits within the pump body until it blocks it.

The samples of water, taken from the same sampling point, presented both visually and as regards the parameters monitored, a sensible improvement as compared to the previous samplings, since it had approximately a pH of 6 and a crystalline transparency that lasted for some minutes.

Step 3 of the test in five points of administration of the C0₂+N+He+Ar mixture

Application: base: 60% C0₂ plus a balanced mixture of gases: 10% He, 20% N, 10% Ar. Mixture administered in five equidistant points along the vertical of the well with variation of administration to favour complete solution of the gases: in the two most superficial points (approx. 13 and 17 m from the plane of site) at 2 bar, 2-3 lt/min; in the three underlying points (approx. 21, 25, and 30 m from the plane of site) at 3 bar, 5 lt/min.

Step 3 had the following targets:

involving the entire surface of the lining of the well with the reaction of the mixture;

improving operation of the pump by aiming better administration of the gaseous mixture both as regards the position and as regards the amount of N and He to solubilize the minerals; and

stabilizing the solution to maintain the pH and limpidity of the water as far as treatment, performing trials with the addition of other technical non-toxic gases .

Given the outcome of Step 2, we proceeded by modifying the set-up of the distribution, with the administration of the mixture at five levels at intervals of approximately 4-5 m so as to involve the entire column of water. In the course of work, also the proportions of the mixture were varied and differentiated between the levels according to the reactions found on the lining of the well and in the pump .

The pH of the water in the well was stabilized between pH 5.3 and 5.5, whereas pH 6 was found at intake of sampling on the delivery line on the surface (after centrifugation of the pump) .

The parameters of oxygen and turbidity were substantially improved, as was highlighted also by a sample taken on the delivery of the pump, and the water maintained the limpidity for a period of more than three hours and a half (monitored up to 3 hours and 38 minutes) .

Part of the mixture of N and He was administered directly in the proximity of the intake of the pump, which as a consequence of said application more than doubled its own service life.

To verify the goodness of the data acquired, after two prolonged cycles of operation of the pump, administration of the mixture of the two gases in the intake was suspended. After five days from the suspension, the pump returned to the same operating conditions as those prior to the test, where N and He were administered in the proximity of the intake, confirming the actual effectiveness of the application.

Amongst the gases tested, moreover, was argon (Ar) , which in the complex chemical balance of the aquifer water determined the stability of the pH and the limpidity of the water.

In the course of Step 3, which lasted approximately one and a half months, the following results were obtained:

the pH, as likewise the other parameters, remained practically uniform throughout the column of water of the well, on average pH < 6 (5.3 - 6), as emerges from Table 3 below and as the video-inspections have shown; with administration of Ar it was possible to stabilize over time the pH and the limpidity of the water for all the time necessary for transport up to the treatment system;

the service life of the submerged pump, from 5 to 7 days, almost tripled with arriving, in the course of the test, at 16 to 18 days, with a tendency to increase ;

it was found that the state of cleanliness of the lining of the well was maintained;

there was ascertained the regression of the concretions that developed in the section of lining of the well that remained without administration of the mixture of gases ;

there was found the absence of encrustations in the pump body and in the delivery tubes and instruments; and

cleanliness of the manifolds and lines for delivery of water to the treatment system was found.

Table 3 below gives the data, highlighted in which is the stabilization of the pH and of the chemico- physical parameters of the water induced by the reaction of the C0₂~based mixture and of the overlying column of water.

Table 3

/11/0916:15:00

SA8060- 014.1 9.013m 22.37°C 22.794mS 5.963pH -253.lmV 0.449ppm 4.1NTU /11/0916:16:00

SA8060- 014.1 10.000m 22.37°C 22.966mS 5.990pH -252.2mV 0.407ppm 8.8NTU/11/0916:16:00

SA8060- 014.1 11.017m 22.33°C 23.628mS 6.076pH -251.8mV 0.389ppm 8.8NTU/11/0916:16:00

SA8060- 014.1 12.010m 22.27°C 25.596mS 6.209pH -251.7mV 0.371ppm 8.8NTU/11/0916:16:00

SA8060- 014.1 13.012m 22.26°C 27.024mS 6.238pH -251.7mV 0.347ppm 8.2NTU/11/0916:16:00

SA8060- 014.1 14.000m 22.25°C 27.588mS 6.255pH -251.7mV 0.321ppm 7.8NTU/11/0916:16:00

SA8060- 014.1 15.018m 22.24°C 27.920mS 6.313pH -251.9mV 0.294ppm 8.8NTU/11/0916:17:00

SA8060- 014.1 16.003m 22.16°C 30.607mS 6.424pH -253.2mV 0.265ppm 8.8NTU/11/0916:17:00

SA8060- 014.1 17.006m 22.01°C 33.548mS 6.564pH -273.2mV 0.241ppm 7.3NTU/11/0916:17:00

The data gathered in Step 3 of the tests described above confirm the effectiveness of the process described so that it is reasonable to conclude that: the reaction produced by the C0₂~based mixture of gases, non-toxic gases, and/or gases for alimentary uses or else of C0₂ recovered from industrial processes (CCS) enables inhibition of the development of concretions and encrustations in wells, tanks, pipes, linings, and removal of concretions and encrustations that may have already formed in all those conditions where the turbulence or lamination of the liquid favours release of the oxygen and hence formation of mineral precipitates.

In accordance with the present invention, according to the purpose of the treatment, the composition of said balanced gaseous mixture is determined on the basis of the chemistry (i.e., of the chemical characteristics) of the water to be treated. In addition, said mixture is dissolved in amounts, proportions, and pressure adequate for the point of administration, the nature and amount of the waters that are to be treated for generating a reaction designed to achieve the purposes of the treatment. After prior chemical laboratory analyses of the water, the minerals, metals, and metalloids to be subjected to treatment can be identified, and the compounds of the mixture of gases designed to react with those minerals and/or metals can be defined accordingly.

In any case, according to the invention to obtain an effective reaction it is necessary to create conditions of weak acidity, with pH between 5 and 6, and a reduction of the working temperature to below 18 °C so as to stabilize the free oxygen and thus obtain a reduction of the mineral precipitates.

As already mentioned at the conclusion of the preliminary step, the determination of the amounts and composition of the mixture must be made during the preliminary operating stage, with start-up of the treatment system. Once the process has been calibrated, the automatic mixing and delivery system will adapt the correction factor of the gas to be administered to the parameters of desired quality of the water to be supplied.

From what has been said so far, it emerges clearly that the present invention envisages the use of a balanced mixture of non-toxic inert gases of an alimentary or superior type, C0₂, He, N, Ar, or else with a base of C0₂ that is recovered from industrial activities, said gaseous mixture being dissolved in wells of aquifer water and/or in water of systems for drinking and/or industrial purposes in order to decalcify and stabilize the oxygen and the minerals dissolved therein and inhibit formation of mineral precipitates and hence formation of encrustations and concretions.

Another peculiar characteristic of the invention lies in the fact of envisaging an automatic control of the quality of the water taken in (input) and supplied (output) via a purposely provided electronically controlled mixer and/or regulator of the mixture introduced necessary for treatment of the water.

Example: CQ₂-based mixture of gases

Carbon dioxide, in balanced conditions of pressure and quantity, in contact with water is solubilized therein and then converted into carbonic acid:

C0₂ + H₂0 → (H2CO3)

Once formed, the carbonic acid in contact with the calcium or lime in the water, transforms it into the bicarbonate ion HC0₃, which is soluble in water and consequently does not precipitate, developing the triple action of:

- transforming the lime in the water (in a well, tank, pipeline, etc.) into soluble bicarbonate;

- attacking also the lime that has already precipitated and adheres to the walls (in a well, tank, pipeline, etc.), dissolving and converting also this into soluble bicarbonate; and - saturating the water by stabilizing the active oxygen thanks to the presence of the weak acid produced by the mixture.

Advantageously, in the presence of weak acidity and in the absence of dissolved oxygen, on the one hand the water is sterilized by the aerobic bacterial formations, and on the other hand the minerals are stabilized. In fact, oxidation is inhibited and there is no formation of mineral precipitates, which are formed by fermentation and/or by oxidation. Furthermore, the transformation of the metals into hydroxides M(OH)n (where n is the number of anion groups) is favoured.

The other gases that make up the mixture are chosen in an adequate percentage for improving or integrating the reaction of the CO₂ base with the compounds to be treated present in the water, which are different from the derivative compounds of calcareous origin .

Purely by way of illustrative and non-limiting example, presented hereinafter are three types of nontoxic technical gases that were used to conduct the test :

Nitrogen (N) , in balanced percent in the mixture, assists saturation of the water and moreover binding of the molecules of active oxygen dissolved in water, blocking oxidation and formation of bacteria, and stabilizing the molecules of hydroxides present in the water. Furthermore, nitrogen binds the ions of Fe, rendering the iron soluble in water to create a porphyrin molecule Fe₄N. Helium (He) , in balanced percent in the mixture, sustains the saturation of water and assists binding of the molecules of the metals and of the metalloids to form the hydroxides or other elements present in the water .

It assists stabilization of the gases with reduction of temperature.

Argon (Ar) , in balanced percent, has shown effective stabilization of the mixture of the gases. In fact, it was noted that, with the addition of this gas dissolved in the mixture, it was possible to prolong the time of stability of the quality and of the pH of the waters treated, keeping them limpid for a longer time and hence prolonging the times within which to carry out transfer of the waters to the treatment and/or delivery system.

The balance of the composition of the mixture, together with the balance of the quantities and pressures of delivery of the mixture of gases themselves, prevents formation of the precipitates and hence of the concretions and/or encrustations in the wells, in the recipients, in the pipelines, etc., which create problems both of flow rate and of use.

After feasibility tests, other gases can be used in mixture with C0₂, which have the property of reacting, in mixture, with the elements present in the chemical composition of the waters, in the proportions to be determined each time in the start-of-process stage .

DESCRIPTION OF THE AUTOMATIC REGULATOR

The stability of the quality of the water to be treated determines the technology to be applied to obtain the balance of the composition of the mixture; this may be obtained with:

a) an electronically controlled automatic regulator or mixer according to the present invention (illustrated schematically in Figure 1), for the cases where the quality of the water to be treated is unstable;

b) a simple regulator for pre-composed gaseous mixture, for the cases where the quality of the water to be treated is stable;

c) control of the quality of the waters with automatic mixer and standard regulator, in the case of C0₂ recovered in loco and individual supplies of the other gases in tanks.

a) The electronically controlled automatic mixer - regulator (Figure 1) according to the invention, is designed to regulate the balance between flow rate and pressure of the mixture as a function of the variation in the physico-chemical parameters of the water, which are monitored continuously at input and at output.

The data detected by the individual specific probes are acquired and processed. As a consequence, the program entered into the PLC will vary the amount of the mixture to be supplied but also the percentage of the individual gases as a function the quality of the water, to cause the quality of the water supplied to remain constant.

This technology enables stabilization of the quality of the water at output also as the quality and flow rate of the water at input varies. In fact, in the case of variation of the intake flow rate upwards or downwards, if the amount and/or quality of the mixture of the gases dissolved were not adequate, there would be a consequent variation of the characteristics of the water supplied.

The change would in any case affect the quality of the water at output both reducing it and increasing it to such an extent as to render the treatment useless or varying the pH to a value not adequate for the subsequent use of the water, which may even be drinking water. This reinforces the importance of use of the automatic regulator in treatments in which there are substantial variations in the quality and quantity of the water during operation.

b) The simple regulator can be constituted by just the automatic regulator of the previous case, which can advantageously be separated from the mixer. It is designed to regulate the balance between flow rate and pressure of the pre-composed mixture as a function of the variation in the continuously monitored physico- chemical parameters of the water at output.

Alternatively, a manual regulator of flow rate and pressure of a commercially available type can be used.

With either of the two types of regulators a pre- composed mixture of gases is adopted, according to the stable quality of the water at input.

The pre-composed mixture is determined following upon characterization of the quality of the water to be treated by means of chemical laboratory analyses conducted preliminarily.

PRACTICAL EXAMPLES OF GASEOUS MIXTURE BASED UPON CHARACTERIZATION OF WATERS

As mentioned above, at the present state of the art it is possible to determine the compounds of the mixture, but it is not possible to pre-define the balanced mixture. In fact, some gases suited to the type of treatment have been identified, whilst the process protocols are refined with the preliminary operating stage: seeing that for the effectiveness of the treatment there concur a multiplicity of parameters, it is important to determine the adequate operating conditions of application of the mixture.

Purely by way of example we refer to what is applied in Step 3 of the experimental test with reference to the chemico-physical characteristics of Table 1.

Application: base of 60% C0₂ plus a 10% He, 20% N, 10% Ar balanced mixture of gases. Mixture administered at five equidistant points along the vertical of the well with variation of administration to favour complete solution of the gases: in the two most superficial points (approx. between 13 and 17 m from the plane of site) at 2 bar, 2-3 lt/min; in the three underlying points (approx. 21, 25, and 30 m from the plane of site) at 3 bar, 5 lt/min.

Once the parameters that characterize the type of water to be treated and the range of administration of the gaseous mixture are determined, in the laboratory the mixture of the gases specific for that particular type of water is created with reference to the standard required for the water to be supplied. In the start-of- treatment stage, a monitoring program is fixed. Then, periodically, first at short intervals apart and subsequently at longer intervals, the samples will be taken with the corresponding analysis of the water supplied, so as to verify that the calibrations are balanced for the type of water of the specific case. In the case where there might be detected values that do not fall within the specifications, the calibrations will be balanced, and the monitoring process will be re-programmed.

c) Control of the quality of the water: the automatic mixer assembly according to the invention, with or without the standard regulator of the gases, is controlled by probes specific for the measurement of some general parameters and other specific parameters according to the quality of the water to be treated, which can be defined case by case.

In fact, it is sufficient to replace one or more detection probes to adjust the process to the parameters required.

By way of example, the following may be detected:

• pH of the water;

• dissolved oxygen;

• temperature;

• conductivity;

• hardness;

• redox;

• etc .

The regulator can be managed both manually (locally) or remotely, according to the complexity of the system and the importance of the system itself. The operating data can be returned either locally or by a distributed control system (DCS) . In any case, it will be necessary to conduct a periodic monitoring with chemical laboratory analyses.

In the case of adoption of a commercial regulator, a frequent monitoring will be conducted with chemical laboratory analyses.

Claims

1. A process for treating waters to prevent formation of concretions and encrustations caused by the minerals present in the water circulating in systems, pipes of any type, and/or in wells, as well as to eliminate possible encrustations that might present at the start of treatment, said process being characterized in that it basically envisages the addition in solution, in gaseous form, of C0₂ or of an appropriate C0₂-based mixture of gases; thus obtaining that the gases dissolved in the water give rise to a chemical reaction with the minerals contained therein, suited to:

- rendering soluble the calcium/lime, and other minerals, and thus obtain a reaction that produces water-soluble calcium carbonate or calcium bicarbonate;

- transforming some metals into corresponding hydroxides; and

- stabilizing the active oxygen, inhibiting formation of mineral precipitates.

2. The process according to the preceding claim, characterized in that it envisages that said C0₂ or said appropriate C0₂-based mixture of gases, dissolved in water, will be suited to producing carbonic acid H₂C0₃, which transforms calcium into soluble bicarbonate HC0₃.

3. The process according to Claim 1 or Claim 2, characterized in that it envisages that said C0₂ or said appropriate C0₂-based mixture of gases, dissolved in water, will be suited to producing and sustaining the weak acid for transforming the metals into hydroxides M(OH)n, (where n is the number of anion groups) and for saturating the water by stabilizing the active oxygen inhibiting oxidation and formation of precipitates and hence of encrustations.

4. The process according to Claim 1, characterized in that said C0₂ is recovered from industrial activities and re-used or else is of the type for alimentary use and in that said mixture of gases is made up of non-toxic C0₂-based technical gases or superior gases.

5. The process according to Claim 1, characterized in that, given the multiplicity of the chemico-physical parameters to be taken into account for the treatment, it envisages that the determination of the quantities and qualities of the mixture of gases is made in a preliminary operating step during start-up of the treatment system.

6. The process according to the preceding claim, characterized in that, once the process has been calibrated, the control is entrusted to a purposely provided automatic mixing and delivery system, designed to adjust the correction factor of the gas to be administered to the parameters of desired quality of the water to be supplied.

7. The process according to Claim 1, characterized in that it envisages administration of C0₂ at a relative pressure of 2 to 3 bar, 3-5 lt/min, in order to modify sensibly the chemico-physical parameters of the groundwater in the proximity of and above the point of administration of C0₂, in particular pH, oxygen, and turbidity; thus obtaining that, after a few days, in the area affected by the administration of C0₂ the lining of the pipes is clean and proceeding downwards, the encrustations increase, whilst the encrustations in the delivery lines of the water are less marked than before, giving way to a pasty material, made up of sulphates, iron, manganese, and other metals.

8. The process according to Claim 1, characterized in that it envisages administration of a balanced mixture of gases containing 80% C0₂, 10% He, 10% N, administered at a pressure of 3 bar, 3-5 lt/min in three equidistant points in the vertical of the well; thus obtaining: involving of as great a surface as possible of the lining of the well; prevention of cavitation of the pump; stabilization of the solution; and reaction with the minerals that deposit in the pump body to solubilize them and prolong the life of the pump itself.

9. The process according to the preceding claim, characterized in that said points of introduction of the gaseous mixture are: one at the well bottom, at approximately 30 m from the plane of site; one at approximately 2/3 of the column of water at approximately 22 m; and a third one at approximately 15 m from the plane of site, so as to exploit the rising current of the solution of C0₂ in water towards the intake of the pump, thus obtaining a prolongation of the service life of the pump.

10. The process according to Claim 1, characterized in that it envisages administration of a balanced mixture of gases containing: 60% C0₂, 10% He, 20% , 10% Ar, administered in five equidistant points in the vertical of the well with variation of administration to favour complete solution of the gases: in the two most superficial points (at approx. 13 m and 17 m from the plane of site) at 2 bar, 2- 3 lt/min; and in the three underlying points (at approx. 21 m, 25 m, and 30 m from the plane of site) at 3 bar, 35 lt/min; thus obtaining: involving the entire surface of the lining of the well with the reaction of the mixture; improving running of the pump, aiming better administration of gaseous mixture both in the position and in the amount of N and He to solubilize the minerals; stabilizing the solution, via Ar, to maintain the pH and the clearness of the water.

11. The process according to any one of the preceding claims, characterized in that it envisages administration of CO₂ or the mixture of gases from a number of points of immersion set at different levels along the column of water to be treated by varying and differentiating also the proportions between the levels according to the reactions found on the lining of the well and in the pump.

12. The process according to Claim 8 or Claim 10, characterized in that it envisages administration of part of the mixture of N and He directly in the proximity of the intake of the pump; thus obtaining considerable prolongation of the service life.

13. The process according to any one of the preceding claims, characterized in that, according to the purpose of the treatment, it envisages determining the composition of said balanced gaseous mixture according to the chemical characteristics of the waters to be treated; said mixture being dissolved in an amount, a proportion, and at a pressure that are adequate for the administration point and the nature and quantity of the waters that are to be treated in order to generate a reaction designed to achieve the purpose of the treatment.

14. The process according to any one of the preceding claims, characterized in that, to obtain an effective reaction, it envisages creating in the water to be treated conditions of weak acidity with pH between 5 and 6 and a reduction of the working temperature to below 18 °C, so as to stabilize the free oxygen and thus obtain a reduction of the mineral precipitates; thus obtaining that, in the presence of weak acidity and in the absence of dissolved oxygen, on the one hand the water is sterilized by the aerobic bacterial formations, on the other hand the minerals are stabilized, and moreover the transformation of the metals into hydroxides M(OH)n, where n is the number of anion groups, is favoured.

15. The process according to any one of the preceding claims, characterized in that it envisages an automatic control of the quality of the water taken in (input) and supplied (output) via a purposely provided electronically controlled mixer and/or regulator of the mixture introduced necessary for treatment of the water .

16. The process according to the preceding claim, characterized in that said automatic control comprises the use of an electronically controlled automatic mixer-regulator, designed to regulate the balance between flow rate and pressure of the mixture as a function of the variation in the physico-chemical parameters of the water, which are monitored continuously as they are taken in (input) and supplied (output) via purposely provided probes.

17. The process according to the preceding claim, characterized in that the data detected by the individual specific probes are acquired and processed by a program entered into a PLC for varying the amount of the mixture to be supplied but also the percentage of the individual gases according to the quality of the water, to keep the quality of the water supplied constant .

18. The process according to the preceding claim, characterized in that, in order to stabilize the quality of the water supplied, also as the quality and the flow rate of the water taken in varies, it envisages adjustment of the quantity and/or quality of the dissolved gas mixture to a possible variation of the intake flow rate in excess or in defect.

19. The process according to Claim 15, characterized in that said automatic control comprises the use of a simple automatic regulator, designed to regulate the balance between flow rate and pressure of the pre- composed mixture according to the variation in the physico-chemical parameters of the water monitored continuously during supply (output) ; said gas mixture being of the pre-composed type, according to the quality of the water taken in (input), which must be stable.