ES2622057T3 - Method to control 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) submerged in said electrolytic solution, an electric power generator (14) connected to said electrode (13) and said reservoir (12), and a controller (16) provided with a meter (15) measuring at least one electrical quantity that is established between said electrode (13) and said reservoir (12), providing said method at least one stage in which said electric power generator (14) is regulated to maintain, between said electrode (13) and said reservoir (12), a known and substantially constant first value (Vp) in time, suitable to guarantee the protection of said tank (12) against corrosion, characterized in that it comprises at least one stage of detection of alternating currents of electrical dispersions present in said dep site (12), wherein said detection stage comprises: - a first stage in which said electric power generator (14) cyclically alternates, between said electrode (13) and said reservoir (12), a variation of potential that varies between a first potential value (VI) and a second potential value (V2), less than the value of said first potential (VI), to establish said protection potential (Vp) in said electrolytic solution; - a second stage in which said meter (15) makes a plurality of measurements of the currents that circulate between said electrode (13) and said reservoir (12); - a third stage in which said controller (16) verifies whether the measured values (Im) of the current flowing between said electrode (13) and said reservoir (12) remain variable around a balanced current with value (Ie) and, in this case, said controller (16) recognizes a state in which there is an absence of stray currents; - a fourth stage in which, if the measured values (Im) of the current flowing between said electrode (13) and said reservoir (12) are outside a balanced current with value (Ie), said controller (16) verifies if the frequency of the variation values of said measured currents corresponds to the cyclicity of said parasitic currents and, in this case, recognizes the presence of electrical dispersions that are derived from the alternating currents in said deposit (12).

Description

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DESCRIPTION

Method for controlling the operation of a heating apparatus 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 connected 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 cathode protection devices against corrosion of containers, tanks or metal parts containing water, such as boilers.

Background of the invention

Devices are known, for the cathodic protection of heating devices 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, 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 against corrosion.

The current that is established between the anode and the boiler varies periodically over time, in its intensity, for a given 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 measured potential difference is compared with a predetermined reference value, corresponding to a known value in 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 in order to obtain a potential difference substantially equal to the predetermined reference value.

The known difference in the potential value, hereinafter referred to as 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 the possible stability conditions. in 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 reference is made to iron alloys, but it is also applicable to other metals, although with the adoption of different potentials.

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

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

The prior art documents WO 2009/029287 A1, WO 2007/010335 A2 and US 6,080,973 describe systems for controlling corrosion and / or other operating anomalies for water tanks and heaters.

One of the purposes of the present invention is to improve a method for controlling the operation of a heating apparatus that is efficient and that allows to increase the working life of the heating apparatus in which it is applied.

Another objective of the present invention is to improve a method that increases the safety of the heating apparatus.

The applicant has devised, tested and realized the present invention to overcome the inconveniences 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 independent claims, while the dependent claims describe other features of the invention or variants of the main inventive idea.

In accordance with the above purposes, a method according to the present invention is applied to control the

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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 equipped with a meter that measures at least one electrical quantity that is established between the electrode and the tank.

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

According to 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 the at least one electrical quantity in order to determine the presence of dispersions. electrical, which must be avoided as they are the cause of the corrosive effect generated in the tank walls.

The detection stage provides for detecting alternating currents of electrical dispersion.

The measured electrical quantity is a measured electrical current. In this case, the detection stage comprises:

- a first stage in which the electric power generator cyclically alternates, between the electrode and the tank, a variation of potential that varies between a first potential and a second potential, less than the value of the first potential, to establish the potential of protection in the electrolytic solution;

- a second stage in which the meter performs a plurality of measurements of the current flowing between the electrode and the reservoir;

- a third stage in which the controller verifies whether the measured values of the current flowing between the electrode and the reservoir remain variable around a balancing current and, in this case, the controller recognizes a condition in which there is a absence of parasitic currents;

- a fourth stage in which, if the measured values of the current flowing between the electrode and the reservoir are outside a balancing current, the controller checks whether the frequency of the variation values of the measured currents corresponds to the cyclicity of the parasitic currents and, in this case, the presence of electrical dispersions that are derived from the alternating currents in the tank is recognized.

The present invention also relates to an electrical cathode protection device to be associated with a heating apparatus comprising a reservoir containing an electrolytic solution. The device comprises an electrode submerged during use in the electrolyte solution, an electric power generator connected to the electrode and, during use, to the reservoir, and a controller provided with a meter configured to measure an electrical quantity that is established between the electrode and the deposit. According to a feature 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 drawings

These and other features of the present invention will become apparent from the following description of a preferred form of realization, given as a non-restrictive example with reference to the accompanying drawings in which:

- 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 in time that is applied to the heating apparatus during normal operation, according to a first embodiment that is not part of the present invention;

- 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 in time that is applied to the heating apparatus during normal operation, in accordance with one embodiment;

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

To facilitate understanding, the same reference numbers have been used, when possible, to identify common common elements in the drawings. It is understood that the elements and characteristics of a

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embodiment, can conveniently be incorporated into other embodiments, without further clarification.

Detailed description of some embodiments

A heating apparatus according to the present invention is indicated in its entirety by reference number 10 and comprises an electrical cathode protection device 11 against corrosion.

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

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

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

An embodiment that is not part of the present invention provides that the electric power generator is a direct current controlled generator, hereinafter referred to as a current generator 14.

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

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

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

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

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

In order to ensure adequate corrosion protection of the tank 12, during normal operation of the heating apparatus 10, the current generator 14 maintains, between the electrode 13 and the tank 12, a protection potential that is substantially constant in time, is indicated in Figure 2a as potential protection Vp.

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

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

The potential protection Vp that will be established in the electrolyte solution can be generated iteratively by regulating the current supplied by the current generator 14 and detecting with the meter 15 the establishment of electric currents inside the cathodic protection device electric 11.

The detection of electric currents identifies an unstable condition of the potential in the 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, parasitic currents affecting the tank 12 and which can contribute significantly to corrosion inside.

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

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

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

With reference to Figures 2a and 2b, a first embodiment describes the method that is not in accordance with the present invention, which is used to detect electrical dispersions in direct current.

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

There is then a step of detecting electrical dispersions during which a controlled variation of the electrical energy supplied by the current generator was presented.

As shown in Figure 2a, the detection stage occurs during a time interval T shorter than the total operating time of the heating apparatus 10 according to the invention. By way of example only, it can be provided that the time interval T lasts approximately one minute and is executed with a periodicity of twelve hours, that is, the detection is carried out periodically twice a day.

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

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

From the analysis of the experiment, the applicant has found that, in the absence of electrical dispersions, the measured potential Vm or the residual potential moves rapidly to an asymptotic value substantially stable over time, as shown in Figure 2b, so similar to the curve in which the measured potential Vm1 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 moving to an asymptotic potential over time, decreases rapidly, therefore facilitating the corrosive action. This condition is shown by the curve in Figure 2b, in which the potential value Vm2 is detected.

Based on these observations, the method not in accordance with the present invention provides that the potential measurement value Vm is compared by the controller 16 with a reference potential Vr. By way of example only, 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, the controller 16 recognizes an operating condition within the standard. To this end, 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, the controller 16 recognizes the presence of harmful electrical dispersions in the reservoir 12 and orders the activation of the indicators 17. In this condition, in figure 2b the measured potential is indicated as Vm2 and it can be seen that Vm2 <Vr.

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

An embodiment not in accordance with the present invention provides that the period of time S is between 30 s and 60 s. The period of time S, before measuring, prevents the detection of transient effects and temporarily stabilizes the operation of the heating apparatus 10.

Example

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

- Value of the measured Vm potential, 60 s after the temporary interruption of the current generator 14, without direct current dispersions: Vm1 = - 750 mV;

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

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

With reference to Figures 3a, 3b and 3c, an embodiment of the method according to the present invention is described, which is used to detect electrical dispersions in alternating current.

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

In particular, the current generator 14 alternates in very short times, that is, approximately every 200 | js, the generation of a first potential V1, and a second potential V2 with a reduced intensity compared to a first potential V1.

The values of the first potential V1 and the second potential V2 are determined in order 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 of 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 js (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 to be supplied to the current generator 14 in order to guarantee said potential protection Vp in the electrolytic solution.

During this stage, the meter 15 measures the electrical quantities, in this case the current flowing in the electrical cathode protection device 11, to assess whether an equilibrium condition has been reached. The currents measured by the meter 15 are indicated in Figures 3b and 3c, by Im.

The balanced condition is represented by the consecutive detection of measured currents Im 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 parasitic currents, therefore, the measured current values Im are not subject to large deviations, and remain limited to a band of values 18 that vary around a balanced current, that is, as shown in the figure 3b

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

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

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

If the processing unit 19 identifies a cyclic development of the measurements performed as indicated above, the activation of the indicators 17 is ordered to indicate to the user an anomalous operating condition.

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Some embodiments of the present invention may provide that the light indicators 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 cathode protection device 11.

For example, it can be established that, in the first power supply to the heating apparatus 10, the indicators 17 indicate to the user said working time, for example, an indication of the working years corresponding to the number of flashes of the red led 17a , and an indication of the months of work corresponding 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 working time.

In 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, yellow LED 17c turns on and stays on until a maintenance operation 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 conditions or an open circuit in the heating apparatus 10.

It is clear that modifications and / or additions of parts can be made to the method for controlling the operation of a heating apparatus as described so far, 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 of skill in the art will certainly be able to achieve many other equivalent forms of method for controlling the operation of a heating apparatus, which has the characteristics as set forth in the claims and therefore fall within the field of protection defined by them.

Claims (3)

5 10 fifteen twenty 25 30 35 1. Method for controlling the operation of a heating apparatus (10) comprising a tank (12) containing an electrolytic solution inside it, an electrode (13) immersed in said electrolytic solution, an electric ene generator ( 14) connected to said electrode (13) and said reservoir (12), and a controller (16) provided with a meter (15) measuring at least one electrical quantity established between said electrode (13) and said reservoir (12 ), said method providing at least one stage 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 over time, suitable to guarantee the protection of said deposit (12) against corrosion, characterized in that it comprises at least one stage of detection of alternating currents of electrical dispersions present in said deposit (12), whereinsaid detection stage comprises: - a first stage in which said electric power generator (14) alternates cyclically, between said electrode (13) and said tank (12), a variation of potential that varies between a first potential value (VI) and a second value of potential (V2), less than the value of said first potential (VI), to establish said protection potential (Vp) in said electrolytic solution; - a second stage in which said meter (15) performs a plurality of measurements of the currents that circulate between said electrode (13) and said reservoir (12); - a third stage in which said controller (16) verifies whether the measured values (Im) of the current flowing between said electrode (13) and said deposit (12) remain variable around a balanced current with value (le) and, in this case, said controller (16) recognizes a state in which there is an absence of parasitic currents; - a fourth stage in which, if the measured values (Im) of the current flowing between said electrode (13) and said tank (12) are outside a balanced current with value (Ie), said controller (16) verifies if the frequency of the variation values of said measured currents corresponds to the cyclicity of said parasite currents and, in this case, recognizes the presence of electrical dispersions that are derived from the alternating currents in said deposit (12). 2. Method according to claim 1, characterized in that the measurements of said measured currents (Im) are carried out when the potential assumes the value of said second potential (V2). 3. Method according to claims 1 or 2, characterized in that said second potential (V2) is comprised between 30% and 70% of said first potential (V1).