ES2752849T3 - Method for controlling the operation of a heating appliance - Google Patents

Abstract

Method for controlling the operation of a heating apparatus (10) comprising a tank (12) containing an electrolytic solution inside, 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) that measures at least one electrical quantity that is established between said electrode (13) and said tank (12), providing said method at least one protection step in which said electric power generator (14) is regulated to maintain, between said electrode (13) and said tank (12), a protection potential with a first value (Vp), known and substantially constant in time, suitable to guarantee the protection of said tank (12) against corrosion, said protection step provides a regulation of a current supplied by the electric power generator (14), a detection, with said measurement or (15), of established electric currents, and a regulation of the current supplied by the electric power generator (14) to maintain a balanced condition of said protection potential at said first value (Vp), characterized in that it comprises at least one detection step of direct currents of electrical dispersions present in said tank (12), wherein said detection step comprises: - a temporary interruption or reduction step of the electrical energy supplied by said generator (14) of electrical energy; - a step of measuring the residual potential, having a second value (Vm), which is established between said electrode (13) and said tank (12), said step of measuring the residual potential being performed during said interruption step or temporary reduction of electrical energy, and after a period of time (S) from the moment in which the controlled variation of the protection potential (Vp) is ordered; - a step of comparing said second value (Vm) of the measured residual potential and a third value (Vr) of a reference potential; where, if said second measured value (Vm) is greater than said third value (Vr) of the reference potential, said controller (16) recognizes an operating condition that is within the norm, and where, if said second value measured (Vm) is less than said third value (Vr) of the reference potential, said controller (16) recognizes the presence of electrical dispersions derived from direct currents in said tank (12).

Description

DESCRIPTION

Method for controlling the operation of a heating appliance

Field of the Invention

The present invention relates to a method for controlling the operation of a heating apparatus, which is advantageously used to reduce the corrosion phenomena related to the continued use of said apparatus. In particular, the method according to the present invention can be implemented in a heating apparatus comprising electrical cathodic protection devices against corrosion of containers, tanks or metal parts containing water, such as for example boilers.

Background of the Invention

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

In particular, a boiler-type apparatus for heating water is known, in which an electrode, also called an 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 protect it from corrosion. The current that is established between the anode and the boiler varies periodically with time, in its intensity, during a certain interval, with respect to the normal operating value, and during this variation, the potential difference that is established between the two poles of the generator.

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

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

Knowing the material of which the boiler is made, therefore, it is possible to determine the protection potential that will be applied between the anode and the boiler.

This protection method, although it guarantees adequate protection against corrosion in the boiler, is a closed system in itself, and cannot detect possible influences due to factors external to the heating apparatus, such as for example electrostatic charges, electrical dispersions or others.

Prior art documents WO 2009/029287 A1, WO 2007/010335 A2 and US 6,080,973 A describe systems for controlling corrosion and / or other operating abnormalities for water tanks and heaters. Other cathodic protection devices are disclosed in US-A-2007/251834, and in BYTYN W ET AL: "Kathodischer Korrosionsschutz von emaillierten Speicherwassererwarmern", MATERIALS AND CORROSION, WILEY; and HANS RICKERT ET AL: "Elektrochemische Untersuchungen zum kathodischen Korrosionsschutz mit Unterbrecherpotentiostaten", MATERIALS AND CORROSION / WERKSTOFFE UND KORROSION.

One purpose of the present invention is to perfect a method of controlling the operation of a heating apparatus that is efficient and that allows the useful life of the heating apparatus to which it is applied to be increased. Another purpose of the present invention is to perfect a method that increases the safety of the heating apparatus.

The Applicant has devised, tested and performed the present invention to overcome the deficiencies of the state of the art and obtain these and other purposes and advantages.

Summary of the Invention

The present invention is set forth and characterized in the appended claims.

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

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

- an electrode immersed in the electrolytic solution,

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

- a controller provided with a meter that measures at least an electrical quantity that is established between the electrode and the tank.

The method provides for regulating the electric power generator to maintain a protection potential in the electrolytic solution that has a first known value, substantially constant in time, adequate to ensure that the tank is protected against corrosion.

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

In accordance with the present invention, the detection step provides for detecting direct stray currents present in the tank. According to this embodiment, the direct current detection step comprises:

- a step of interruption or temporary reduction of the electrical energy supplied by the electrical energy generator;

- a step to measure the residual potential, which has a second value, which is established between the electrode and the tank;

- a step of comparing the second value of the measured residual potential and a third value of a reference potential;

and where, if the second measured value is greater than the third value of the reference potential, the controller recognizes an operating condition that is within the norm, and where, if the second measured value is less than the third value of the reference potential, the controller recognizes the presence of electrical dispersions derived from direct currents in the tank.

The present disclosure also relates to an electrical cathodic protection device that is associated with a heating apparatus comprising a tank containing an electrolytic solution. The device comprises an electrode submerged during use in the electrolytic solution, an electric power generator connected to the electrode and, during use, to the tank, and a controller provided with a meter configured to measure an electrical quantity that is established between the electrode and the tank. In accordance with a characteristic of the invention, the controller comprises a processing unit configured to receive the data of the electrical quantity 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 dispersions.

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

Brief description of the figures

These and other features of the present invention will become apparent from the following description of a preferred embodiment, given as a non-limiting example with reference to the accompanying drawings where:

figure 1 is a schematic representation of a heating apparatus using a control method according to the present invention;

figure 2a is a graph showing the development of the potential over time that is applied to the heating apparatus during normal operation, according to a first embodiment;

figure 2b is a graph showing the potential difference over time that is measured in the heating apparatus according to the first embodiment;

figure 3a is a graph showing the development of the potential over time that is applied to the heating apparatus during normal operation, according to a second embodiment that is not part of the present invention;

figure 3b is a graph showing the development of electric currents over time, which is detected in the heating apparatus according to the second embodiment and in an operating condition;

figure 3c is a graph showing the development of electric currents over time, which is detected in the heating apparatus according to the second embodiment and in another operating condition.

For ease of understanding, the same reference numbers have been used, whenever possible, to identify identical common elements in the drawings. It is understood that the elements and features of one embodiment can be conveniently incorporated into other embodiments without further clarification. Detailed description of some embodiments

A heating apparatus is indicated in its entirety by reference number 10 and comprises a device 11 for electrical cathodic protection against corrosion.

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

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

Electrode 13 may comprise a titanium rod, possibly activated with noble materials.

An embodiment of the present disclosure provides that the electric power generator is a direct current controlled generator, indicated below as a current generator 14.

The current generator 14 is in turn connected to the controller 16 that 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 dispersions.

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

Meter 15 may be a voltmeter, an ammeter, a wattmeter, or simply a device for comparing at least one of the electrical quantities to be detected.

Some embodiments establish that controller 16 comprises a processing unit 19, provided to process the data detected by meter 15 and to signal possible abnormal operating conditions due to the presence of electrical dispersions.

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

To ensure adequate protection against corrosion of tank 12, during normal operation of heating apparatus 10, current generator 14 maintains, between electrode 13 and tank 12, a protection potential that is substantially constant over time, indicated in figure 2a as protection potential Vp.

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

Just as an example, if 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 regulating the current supplied by the current generator 14 and detecting with the meter 15 the establishment of electrical currents within the electrical cathodic protection device 11.

The detection of electrical currents identifies an unstable condition of the potential in tank 12.

If the meter 15 detects a considerable deviation in the electric currents with respect to the previous measurement, the controller 16 regulates the current supplied by the current generator 14 to bring it to a constant value corresponding to a balanced current. With reference to Figures 2a, 2b, 3a, 3b and 3c, a method is described for controlling the operation of the heating apparatus 10 and, in particular, for detecting possible electrical dispersions, for example, eddy currents affecting tank 12 and They can contribute significantly to corrosion inside.

Eddy currents can have a small entity and, therefore, not produce a direct intervention of electrical safety devices, such as circuit breakers normally provided in the electrical network.

Although they do not harm the general safety of the electrical network or the heating apparatus 10, eddy currents are an important factor with respect to the creation of corrosive phenomena.

Such problems occur both with direct current dispersions and with alternating current dispersions.

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

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

It then follows a step to detect electrical dispersions during which a controlled variation of the electrical energy supplied by the current generator is provided.

As shown in FIG. 2a, the detection step occurs over a time interval T shorter than the overall operating time of the heating apparatus 10 according to the invention. Simply by way of example, it can be provided that the time interval T lasts for about one minute and runs at a cyclicity of twelve hours, that is, detection is performed periodically twice a day.

Some embodiments provide that, during the detection step, the supply of electrical current to the current generator 14 is temporarily interrupted, and the meter 15 performs a measurement.

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

Other embodiments provide only a reduction in the current supplied by the current generator 14, and not an interruption thereof.

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

From analysis of the experiment, the Applicant has discovered that, in the absence of electrical dispersions, the measured Vm potential or residual potential moves rapidly to a substantially stable asymptotic value over time, as shown in Figure 2b, similarly to the curve in which the measured Vm1 potential is detected. If there are electrical dispersions in the heating apparatus 10, it should be noted that the development of the measured potential Vm, instead of passing to an asymptotic potential over time, decreases rapidly, facilitating corrosive action. This condition is shown by the curve in figure 2b, in which the potential Vm2 value is detected.

Based on these observations, the method according to the present invention provides that the measured potential value Vm is compared by controller 16 with a reference potential Vr. Just as an example, the 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, controller 16 recognizes an operating condition within the standard. For this purpose, in figure 2b, the measured potential is indicated as Vm1 and it can be seen that Vm1> Vr.

If the measured potential Vm is less than the reference potential Vr, controller 16 recognizes the presence of harmful electrical dispersions in tank 12 and orders the activation of indicators 17. In this condition, in figure 2b the measured potential is indicated as Vm2 and you can see that Vm2 <Vr.

The present invention establishes that the potential is measured after a period of time S from the moment the controlled variation of the protection potential Vp is ordered. The time period S is evaluated, using theoretical experiments, also in relation to the stabilization time of the potential to move to the asymptotic value as described above.

An embodiment of the present invention provides that the time period S is between 30 seconds and 60 seconds. The period of time S, before measuring, prevents the detection of transient effects and makes it possible to temporarily stabilize the operation of the heating apparatus 10.

Example

- Value of the protection potential maintained during normal operation of the heating apparatus 10, Vp = -1000mV;

- Measured potential value Vm, 60 seconds after the temporary interruption of the current generator 14, without direct current dispersions: Vm1 = -750mV;

- Value of the potential Vm measured, 60 seconds after the temporary interruption of the current generator 14, in the presence of direct current dispersions: Vm2 = - 290mV.

Once the measured potential Vm has been measured, that is, after the time interval T (FIG. 2a), the heating apparatus 10 resumes its normal operation, returning the potential difference to the value of the protection potential Vp.

With reference to Figures 3a, 3b and 3c, another embodiment of the method that is not part of the present invention is described, used to detect alternating current electrical dispersions.

During normal operation of the heating apparatus 10, the controller 16 commands the current generator 14 to generate, between the electrode 13 and the tank 12, a potential difference with a desired and variable development over time.

In particular, the alternating current generator 14 in very short times, that is, approximately every 200 ^ s, generating a first potential V1 and a second potential V2 with a reduced intensity compared to the first potential V1.

The values of the first potential V1 and the second potential V2 are determined to obtain a polarization of the electrolytic solution at a value corresponding to the protection potential Vp.

Some embodiments provide that the second potential V2 is between 30% and 70% of the first potential V1.

The variation in potential between the first potential V1 and the second potential V2 can occur with a square wave development of the period P which can be, for example, approximately 200 ^ s (Figure 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 that will be supplied to the current generator 14 to guarantee said protection potential Vp in the electrolytic solution.

During this step, the meter 15 measures the electrical quantities, in this case the current flowing in the electrical cathodic protection device 11, to evaluate if a balanced condition has been reached. The currents measured by meter 15 are indicated in Figures 3b and 3c, by Im.

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

The measurements are taken by the meter 15 when the potential in the heads of the current generator 14 assumes the value of said second potential V2.

In the absence of stray currents, therefore, the measured current values Im are not subject to large deviations, and remain confined to a band of values 18 that vary around a balanced current as depicted in Figure 3b.

In the presence of alternating current dispersions, the meter 15 detects a fluctuation in the measured currents Im that varies with a periodicity close to or comparable to that of the alternating currents of electrical dispersion. To this end, the data detected by the meter 15 on each occasion is transmitted to the processing unit 19 to reconstruct the development in time of the measured currents Im. The processing unit 19 can identify the cyclicity of the detected values which, in the presence of eddy alternating currents, vary with a frequency substantially equal to, or a multiple of, the latter, for example, with a frequency of 50Hz or 60Hz or multiples of the same.

It is quite clear that, to allow a correct acquisition of the cyclicity of the eddy currents, the frequency at which the measurements are made must be greater than the frequency of the eddy currents.

If the processing unit 19 identifies a cyclical development of the measurements made as indicated above, it orders the activation of the indicators 17 to indicate to the user an abnormal operating condition.

Some embodiments of the present invention may provide that the indicator lights comprise a plurality of light sources, in this case (figure 1) a red led 17a, a green led 17b and a yellow led 17c, each of which identifies a particular operating condition of the heating apparatus 10. The controller 16 described above can also provide a function of counting the working time of the electrical cathodic protection device 11.

For example, it can be provided that in the first electrical supply to the heating apparatus 10, the indicators 17 indicate to the user said working time, for example, an indication of the working years that corresponds to the number of flashes of the red LED 17a, and an indication of the working months that corresponds to the number of flashes of the green led 17b. For this purpose, it may be provided that controller 16 also comprises timer means for determining working time.

In the normal operation of the heating apparatus 10, and if no electrical dispersions are detected, the green led 17b remains on.

If electrical dispersions are detected, the yellow LED 17c lights up and stays on until a maintenance operation is requested.

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.

It is clear that modifications and / or additions of parts can be made to the method of controlling the operation of a heating apparatus as heretofore described, without departing from the field and 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 achieve many other equivalent forms of method for controlling the operation of a heating apparatus, having the characteristics set forth in the claims and therefore all fall within the field of protection thus defined.

Claims (6)

1. Method for controlling the operation of a heating apparatus (10) comprising a tank (12) containing an electrolytic solution therein, an electrode (13) immersed in said electrolytic solution, a generator (14) of electrical energy connected to said electrode (13) and to said tank (12), and a controller (16) provided with a meter (15) that measures at least an electrical quantity that is established between said electrode (13) and said tank (12), said method providing at least one protection step in which said electric power generator (14) is regulated to maintain, between said electrode (13) and said tank (12), a protection potential with a first value (Vp), known and substantially constant in time, suitable to guarantee the protection of said tank (12) against corrosion, said protection step provides a regulation of a current supplied by the electric power generator (14), one of detection, with said meter (15), of established electric currents, and regulation of the current supplied by the electric power generator (14) to maintain a balanced condition of said protection potential at said first value (Vp), characterized in that it comprises at least one detection step of direct currents of electrical dispersions present in said tank (12), wherein said detection step comprises: - a step of interruption or temporary reduction of the electrical energy supplied by said electrical energy generator (14); - a step of measuring the residual potential, which has a second value (Vm), which is established between said electrode (13) and said tank (12), said step of measuring the residual potential that is performed during said interruption step or temporary reduction of electrical energy, and after a period of time (S) from the moment the controlled variation of the protection potential (Vp) is ordered; - a step of comparing said second value (Vm) of the measured residual potential and a third value (Vr) of a reference potential; where, if said second measured value (Vm) is greater than said third value (Vr) of the reference potential, said controller (16) recognizes an operating condition that is within the norm, and where, if said second value measured (Vm) is less than said third value (Vr) of the reference potential, said controller (16) recognizes the presence of electrical dispersions derived from direct currents in said tank (12). 2. Method as in claim 1, characterized in that, if said second value (Vm) of the measured potential is less than the reference potential (Vr), the indicators (17) are activated to warn of the presence of electrical dispersions. 3. Method as in claim 1 or 2, characterized in that said third value (Vr) of the reference potential is comprised between 20% and 40% of said first value (Vp) of the protection potential. Method as in any of the preceding claims, characterized in that said interruption or reduction of the electrical energy supplied by said electrical energy generator (14) has a duration of a time interval (T). 5. Method as in claim 1, characterized in that said period of time (S) is comprised between 30 seconds and 60 seconds. 6. Method as in claim 4, characterized in that after said time interval (T), said protection potential is returned to said first value (Vp).