ITUD20130035A1 - METHOD FOR CHECKING THE FUNCTIONING OF A HEATING SYSTEM - Google Patents

Description

"METHOD FOR CHECKING THE OPERATION OF A HEATING APPARATUS"

FIELD OF APPLICATION

The present invention relates to a method for controlling the operation of a heating apparatus, which is advantageously used to reduce the corrosion phenomena connected with the continued use of said apparatus.

In particular, the method according to the present invention can be implemented in a heating apparatus which comprises electrical devices for cathodic protection against corrosion of containers, tanks, or metal parts containing water, such as for example boilers.

STATE OF THE TECHNIQUE

Devices for the cathodic protection of heating apparatuses against corrosion applicable to boilers or water heaters are known.

In particular, a boiler-type water heating apparatus is known in which an electrode, also called anode, made for example of titanium, is immersed in the water contained in the boiler. An electric power generator is connected with the positive pole to the anode and with the negative pole to the boiler to be protected from corrosion. The current that is established between the anode and the boiler is periodically varied over time, in its intensity, for a determined interval, with respect to the steady state value and, during this variation, the measurement of the potential difference that is established is foreseen. between the two poles of the generator.

The measured potential difference is compared with a predetermined reference value, corresponding to a known value for which corrosion is inhibited; any deviation from this reference value is used to determine a current intensity to be applied between the anode and the storage tank in order to obtain a potential difference substantially equal to the predetermined reference value.

The aforementioned known potential difference value, hereinafter referred to as protection potential, is determined in a known way for example with reference to the Pourbaix diagram, or potential / pH diagram, which is a representation of the possible stable conditions at equilibrium of an electrochemical system in aqueous solution. This model is used to predict the corrosion behavior of a metallic material, in this case referred to iron alloys, but also applicable for other metals albeit with the adoption of different potentials.

Knowing the material with which the storage tank is made, it is therefore possible to determine the protection potential to be applied between the anode and the storage tank.

This method of protection, while guaranteeing adequate protection against corrosion of the boiler, is a closed system on itself, and not able to incorporate any influences due to factors external to the heating apparatus, such as for example electrostatic charges, dispersions. electric, or whatever.

An object of the present invention is to provide a method for controlling the operation of a heating apparatus which is efficient and which allows to increase the useful life of the heating apparatus in which it is implemented.

A further object of the present invention is to provide a method which increases the safety of the heating apparatus.

In order to obviate the drawbacks of the known art and to obtain these and further objects and advantages, the Applicant has studied, tested and implemented the present invention.

EXPOSURE OF THE FOUND

The present invention is expressed and characterized in the independent claim. The dependent claims disclose other characteristics of the present invention or variants of the main solution idea.

In accordance with the aforementioned purposes, a method according to the present invention is applied for controlling the operation of a heating apparatus in which the heating apparatus comprises:

- a tank for holding an electrolytic solution, for example water,

an electrode immersed in the electrolyte solution,

an electric power generator connected to the electrode and to the tank, e

- a controller equipped with a meter of an electrical quantity for measuring at least one electrical quantity which is established between the electrode and the tank.

The method involves adjusting the electricity generator to maintain a suitable protection potential in the electrolytic solution to ensure the corrosion protection of the tank.

In accordance with an aspect of the present invention, the method comprises a step for detecting electrical dispersions present in the tank, during which the meter measures at least one electrical quantity, and the controller processes the at least one electrical quantity to determine the presence of dispersions. electrical, which are to be avoided as they cause the corrosive effect generated on the tank walls.

In accordance with a first embodiment of the present invention, the detection step provides for the detection of continuous electrical leakage currents. In accordance with this embodiment, the method can provide that the measured quantity is a measured potential and that, during the detection phase, a temporary variation of the electrical energy supplied by the electrical energy generator is provided, for the subsequent measurement by part of the meter of the measured potential. A comparison of the measured potential with a reference potential follows to identify the presence or absence of continuous leakage currents.

According to another embodiment, the detection step provides for the detection of alternating electrical leakage currents.

According to the latter embodiment, the measured electrical quantity is a measured electrical current. In this case, the method provides that the generator of electrical energy cyclically alternates, between the electrode and the tank, a variation of variable potential, between a first potential and a second potential of reduced intensity with respect to the first potential, in order to maintain in the electrolytic solution, the aforementioned protection potential. It is also expected that during this variation a plurality of measurements will be made to reconstruct the trend over time of the measured currents.

According to a further aspect, during said detection phase the controller is expected to compare the trend over time of the measured currents to identify a cyclicality of the stray currents and consequently demonstrate their presence.

The present invention relates to an electric cathodic protection device to be associated with a heating apparatus comprising a reservoir for containing an electrolytic solution. The device comprises an electrode immersed, in use, in the electrolytic solution, an electric power generator connected to the electrode and, in use, to the tank, and a controller equipped with a meter configured to measure an electrical quantity that is established between the electrode and tank. In accordance with an aspect of the invention, the controller comprises a processing unit configured to receive the electrical quantity data detected by the meter and to process the electrical quantity in order to determine the presence of electrical dispersions. The device also includes indicators associated with the controller to indicate the presence of electrical leaks.

ILLUSTRATION OF DRAWINGS

These and other characteristics of the present invention will become clear from the following description of embodiments, provided by way of non-limiting example, with reference to the attached drawings in which:

- fig. 1 is a schematic representation of a heating apparatus which implements a control method according to the present invention;

fig. 2a is a graph of the trend of the potential over time that is applied to the heating apparatus during its normal operation, in accordance with a first embodiment;

fig. 2b is a graph of the potential difference over time which is measured in the heating apparatus according to the first embodiment;

- fig. 3a is a graph of the trend of the potential over time that is applied to the heating apparatus during its normal operation, according to a second embodiment;

fig. 3b is a graph of the trend of the electric currents over time which is detected in the heating apparatus in accordance with the second embodiment, and in an operating condition;

fig. 3c is a graph of the trend of the electric currents over time which is detected in the heating apparatus in accordance with the second embodiment, and in a further operating condition.

To facilitate understanding, identical reference numbers have been used wherever possible to identify identical common elements in the figures. It should be understood that elements and features of one embodiment can be conveniently incorporated into other embodiments without further specification.

DESCRIPTION OF EMBODIMENTS

A heating apparatus according to the present invention is indicated as a whole with the reference number 10 and comprises an electric cathodic protection device 11 against corrosion.

In particular, the heating apparatus 10 comprises a tank 12 having a metal surface in contact with an electrolytic solution, such as water.

The electric cathodic protection device 11 comprises, in turn, an electrode 13, or anode, an electric power generator 14, and a controller 16.

The electrode 13 can comprise a titanium bar possibly activated with noble materials.

An embodiment of the present invention provides that the electric power generator is a direct current controlled generator, hereinafter referred to as current generator 14.

The current generator 14 is connected, in turn, to the controller 16 which controls and manages the operation of the current generator 14, and possibly signals particular operating conditions of the heating apparatus 10, such as the presence of electrical leaks.

Specifically, the controller 16 is provided with a meter 15 of at least one electrical quantity, configured to detect, for example, the current or electrical voltage values that are established in the electrical cathodic protection device 11, in this case between electrode 13 and tank 12.

The meter 15 can be a voltmeter, an ammeter, a wattmeter, or simply a comparator of at least one of the electrical quantities to be measured.

Embodiments provide that the controller 16 comprises a processing unit 19 designed to process the data detected by the meter 15 and to signal any anomalous operating conditions due to the presence of electrical dispersions.

For this purpose, the controller 16 can be associated with indicators 17, for example light indicators, each of which identifies an operating condition of the heating apparatus 10.

In the normal operation of the heating apparatus 10, to ensure adequate corrosion protection of the tank 12, the current generator 14 maintains, between the electrode 13 and the tank 12, a protection potential substantially constant over time, indicated in fig.

2a as protection potential Vp.

The protection potential Vp is a known value determined, as described above, according to the material with which the tank 12 is made and with reference to the Pourbaix diagram.

By way of example only, if the tank 12 is made of steel, the protection potential Vp assumes a value between 900mV and 1200mV.

The protection potential Vp to be established in the electrolytic solution can be generated iteratively by adjusting the current supplied by the current generator 14 and detecting, with the meter 15, the establishment of electric currents inside the electric cathodic protection device 11.

The detection of electric currents, in fact, identifies a condition of non-stability of the potential in the tank 12.

If the meter 15 detects a significant deviation of the electric currents with respect to the previous measurement, the controller 16 adjusts the current delivered by the current generator 14 to bring it to a constant value corresponding to an equilibrium current. With reference to figs. 2a, 2b, 3a, 3b and 3c, a method is described for controlling the operation of the heating apparatus 10 and, in particular, for detecting any electrical leaks, for example stray currents affecting the tank 12 and which can contribute significantly internal corrosion of the latter.

These stray currents can be of small entity, and therefore do not produce a direct intervention of the electrical safety devices, such as differentials normally provided in the electrical network.

Stray currents, while not jeopardizing the overall safety of the electrical network, or of the heating apparatus 10, are a relevant factor as regards the establishment of corrosive phenomena.

These problems occur both in the case of direct current leaks and in the case of alternating current leaks.

With reference to figs. 2a and 2b, a first embodiment of the method, according to the present invention, used to detect electrical leakages in direct current is described.

During normal operation of the heating apparatus 10, the controller 16 adjusts the current delivered by the current generator 14, as described above, to maintain a condition of equilibrium of the protection potential Vp between the electrode 13 and the tank 12.

An electrical leakage detection phase follows, during which a controlled variation of the electricity supplied by the current generator is envisaged.

As shown in fig. 2a, the detection step intervenes for a time interval T which is reduced with respect to the overall time of operation of the heating apparatus 10 according to the invention. By way of example only, it can be envisaged that the aforementioned time interval T has a duration of approximately one minute and is carried out with a cyclical cycle of twelve hours, or that the aforementioned survey is carried out periodically twice a day.

Embodiments provide that, during the detection step, the supply of electric current to the current generator 14 is temporarily interrupted and a detection is performed by the meter 15.

It is clear that a temporary interruption of the aforesaid time interval T, in the normal operation of the heating apparatus 10, does not affect the corrosion protective effect normally performed by the heating apparatus 10 itself.

Other embodiments provide only for a reduction of the current delivered by the current generator 14, and not for its interruption.

During the detection, the meter 15 detects the potential difference, hereinafter referred to as the measured potential Vm. Said measured potential Vm corresponds to the residual potential that is established between the electrode 13 and the tank 12.

From experimental analyzes, the Applicant has verified that, in the absence of electrical dispersions, the measured potential Vm, that is the residual potential, quickly reaches an asymptotic value substantially stable over time, as shown in fig. 2b, corresponding to the curve in which the measured potential Vml is detected

If electrical dispersions are present in the heating apparatus 10, it is noted that the trend of the measured potential Vm, instead of reaching an asymptotic potential over time, decreases rapidly, consequently favoring the corrosive action. This condition is represented by the curve of fig. 2b where the potential value Vm2 is detected.

On the basis of these observations, the method according to the present invention provides that the measured potential value Vm is compared by the controller 16 with a reference potential Vr. By way of example only, the aforementioned reference potential Vr is between 20% and 40% of the protection potential Vp.

If the measured potential Vm is greater than the reference potential Vr, the controller 16 recognizes an operating condition in the standard. In this regard, in fig.

2b, the measured potential is indicated as Vml and it can be seen that Vml> Vr.

If the measured potential Vm is lower than the reference potential Vr, the controller 16 recognizes the presence of electrical leakages of harmful significance in the tank 12 and commands the activation of the indicators 17. In this condition, in fig. 2b the measured potential is indicated as Vm2 and it is noted that Vm2 <Vr.

An embodiment of the present invention provides that the measurement of the potential takes place after a time period S from the instant in which the controlled variation of the protection potential Vp is commanded. This time period S is evaluated, by means of theoretical tests, also in relation to the stabilization time of the potential to reach the aforementioned asymptotic value as described above.

An embodiment of the present invention provides that the time period S is comprised between 30s and 60s. The time period S, before the measurement, avoids the detection of transient effects and allows the temporary stabilization of the operation of the heating apparatus 10. Example of realization

- Protection potential value maintained during normal operation of the heating apparatus 10, Vp = - 100OrnV;

Value of the measured potential Vm, after 60s from the temporary interruption of the current generator 14, in the absence of direct current leakage: Vml 750 mV;

Value of the measured potential Vm, after 60s from the temporary interruption of the current generator 14, in the presence of direct current leakage: Vm2 = - 290 mV;

Once the measurement of the measured potential Vm has been carried out, i.e. after the time interval T (fig.

2a), the heating apparatus 10 resumes normal operation by bringing the potential difference back to the value of the aforementioned protection potential Vp.

With reference to figs. 3a, 3b and 3c, a further embodiment of the method according to the present invention is described, used to detect electrical leakages in alternating current.

During normal operation of the heating apparatus 10, the controller 16 controls the current generator 14 to generate, between the electrode 13 and the tank 12, a potential difference with a desired and time-varying trend.

In particular, the current generator 14 alternates, in a very short time, that is about every 200 µ43, the generation of a first potential Vi, and a second potential V2 of reduced intensity with respect to the first potential VI.

The values of the first potential Vi and of the second potential V2 are determined so as to obtain a bias of the electrolytic solution at a value corresponding to the aforementioned protection potential Vp.

Embodiments provide that the second potential V2 is comprised between 30% and 70% of the first potential Vi.

The variation of the potential, between the first potential Vi and the second potential V2, can take place with a square wave trend of period P which can be, for example, about 200Î1⁄4Ξ (fig. 3a).

In the normal operation of the heating apparatus 10, and in the absence of electrical dispersions, due to alternating currents, the controller 16 acts by modulating the current to be supplied to the current generator 14 so as to guarantee, in the electrolytic solution, the aforementioned protection potential Vp.

During this phase, the meter 15 carries out measurements of electrical quantities, in this case of the current circulating in the electrical cathodic protection device 11, to evaluate the achievement of an equilibrium condition. The currents measured by the meter 15 are indicated in figs. 3b and 3c, with Im

The equilibrium condition is represented by the consecutive detection of measured currents Im substantially uniform over time (fig. 3b).

The measurements by the meter 15 are performed when the potential across the current generator 14 assumes the value of the aforementioned second potential V2.

In the absence of stray currents, therefore, the measured current values Im do not undergo significant deviations, and remain confined to a band of variable values 18 around an equilibrium current 1 as shown in fig. 3b.

In the presence of alternating current leakage, the meter 15 detects a fluctuation of the measured currents Im which varies with a periodicity close to, or attributable to, that of the alternating electrical leakage currents.

For this purpose, the data detected, from time to time, by the meter 15 are transmitted to the processing unit 19 to reconstruct the trend over time of the measured currents Im. The processing unit 19 is able to identify the cyclicality of the detected values which, in the presence of stray alternating currents, vary with a frequency substantially equal to, or multiple of that of the latter, for example with a frequency of 50Hz or 60Hz or multiples thereof.

It is quite clear that, in order to allow a correct acquisition of the cyclicality of the stray currents, the frequency with which the measurements are carried out must be greater than the frequency of the stray currents.

If the processing unit 19 identifies a cyclical trend of the measurements made as indicated above, it commands the activation of the indicators 17 to signal to the user an anomalous operating condition.

Embodiments of the present invention can provide that the light indicators comprise a plurality of light sources, in this case (fig. 1) a red LED 17a, a green LED 17b, and a yellow LED 17c, each of which identifies a particular condition of operation of the heating apparatus 10.

The controller 16 described above can also provide a function for counting the operating time of the electrical cathodic protection device 11.

For example, it can be envisaged that in the phase of the first electrical supply of the heating apparatus 10, the indicators 17 indicate to the user the aforementioned operating time, for example an indication of the years of operation which corresponds to the number of flashes of the red LED 17a, and an indication of the months of operation which corresponds to the number of flashes of the green LED 17b. For this purpose it can be provided that the controller 16 also comprises timing means for determining the operating time. In normal operation of the heating apparatus 10, and in the event that the presence of electrical dispersions is not detected, the green LED 17b remains on.

In the event that the presence of electrical leaks is detected, the yellow LED 17c is switched on and remains on until maintenance is requested.

The red LED 17a can be used to indicate conditions of excessive electrical absorption by the heating apparatus 10, or to indicate short-circuit or open-circuit conditions in the heating apparatus 10 itself.

It is clear that modifications and / or additions of parts can be made to the method for controlling the operation of a heating apparatus described up to now, without departing from the scope of the present invention.

It is also clear that, although the present invention has been described with reference to some specific examples, a person skilled in the art will certainly be able to implement many other equivalent forms of method for controlling the operation of a heating apparatus, having the characteristics expressed in the claims and therefore all falling within the scope of protection defined by them.

Claims (12)

CLAIMS 1. Method for controlling the operation of a heating apparatus (10), which apparatus comprises a tank (12) for containing an electrolytic solution, an electrode (13) immersed in said electrolytic solution, an electric power generator ( 14) connected to said electrode (13) and to said tank (12), and a controller (16) provided with a meter (15) which measures at least one electrical quantity that is established between said electrode (13) and said tank (12) ), said method providing for the regulation of said electric power generator (14) to maintain in said electrolytic solution a protection potential (Vp) suitable for guaranteeing protection from corrosion of said tank (12), characterized in that it comprises at least one phase of detecting electrical dispersions present in said tank (12) during which said meter (15) measures at least one electrical quantity (Vml, Vm2; Im), and said controller (16) processes said at least one electrical quantity (Vml, Vm2; Im) to determine the presence of said electrical dispersions. 2. Method as in claim 1, in which the detection of continuous electrical leakage currents is provided, characterized by the fact that said electrical quantity is a measured potential (Vml, Vm2), and that during said detection phase a temporary variation of the electricity supplied by said electricity generator (14), the subsequent measurement of said measured potential (Vml, Vm2), and a comparison of said measured potential (Vml, Vm2) with a reference potential (Vr) . 3. Method as in claim 2, characterized in that in said detection phase the supply of electrical energy by said electrical energy generator (14) is interrupted. 4. Method as in claim 2 or 3, characterized in that if the measured potential (Vm) is lower than the reference potential (Vr), warning indicators (17) are activated to warn of the presence of electrical dispersions. 5. Method as in claim 2, 3, or 4, characterized in that said reference potential (Vr) is comprised between 20% and 40% of said protection potential (Vp). 6. Method as in any one of claims 2 to 5, characterized in that said temporary variation of the electrical energy delivered by said electrical energy generator (14) has a duration of a time interval (T), and that the detection of said measured potential (Vml, Vm2) takes place after a time period (S) from said temporary variation. 7. Method as in claim 1 wherein the detection of alternating electrical leakage currents is provided, characterized by the fact that said electrical quantity is a measured current (Im), which said electrical energy generator (14) alternates cyclically, between said electrode (13) and said tank (12), a variation of potential variable between a first potential (Vi) and a second potential (V2), of reduced intensity with respect to said first potential (Vi), to establish in said electrolytic solution said protection potential (Vp), and that a plurality of measurements are carried out to reconstruct the trend over time of said measured currents (Im). 8. Method as in claim 7, characterized in that the measurements of said measured currents (Im) are carried out when the potential assumes the value of said second potential (V2). 9. Method as in claim 7 or 8, characterized in that said second potential (V2) is comprised between 30% and 70% of said first potential (Vi). 10 Method as in claim 9 characterized in that said controller (16) compares the trend over time of said measured currents (Im) to identify a cyclicality of said stray currents. 11 Method as in claim 10 characterized in that during said comparison it is envisaged to evaluate whether said measured currents (Im) have a cyclic trend with a frequency of about 50Hz or about 60Hz. 12. Electric cathodic protection device to be associated with a heating apparatus (10) comprising a tank (12) for containing an electrolytic solution, said device comprising an electrode (13) immersed, in use, in said electrolytic solution, a generator of electric energy (14) connected to said electrode (13) and, in use, to said tank (12), and a controller (16) provided with a meter (15) configured to measure at least one electrical quantity that is established between said electrode (13) and said tank (12), characterized in that said controller (16) comprises a processing unit (19) configured to receive the data of said electrical quantity (Vml, Vm2; Im) and to process said quantity electrical leakage (Vml, Vm2; Im) for the purpose of determining the presence of electrical leaks, and which comprises indicators (17) associated with said controller (16) to indicate the presence of said electrical leaks,