RU114054U1 - INSTALLATION FOR PULSE CATHODE PROTECTION - Google Patents

Abstract

The utility model relates to equipment for electrochemical protection and can be used in cathodic protection systems of underground metal structures against corrosion. The installation contains an electronic unit, an anode ground electrode and a reference electrode. The electronic unit contains a direct current source, a pulse amplifier, an energy storage device, a pulse shaper. The energy store is connected to a pulse amplifier. The latter is connected to a pulse shaper, to the anode earthing switch and to the protected structure. The reference electrode is connected to a pulse shaper. The electronic unit has a constant voltage level converter, which is connected to an energy storage device, a direct current source, and a pulse shaper. A direct current source is connected to a pulse shaper connected to the protected structure. The installation allows to increase the accuracy of maintaining the polarization potential throughout the protected area. 1 n.p. crystals, 3 figures, 1 ave.

Description

The utility model relates to equipment for electrochemical protection and can be used in cathodic protection systems of underground metal structures against corrosion.

There are various modifications of devices for pulsed cathodic protection [US patent for invention No. 5324405 "Pulse cathodic protection system", DE patent for invention No. 2007347 "Verfahren zur automata-tischen Steuerung einer Kathodenschutzanlage", RU patents for invention No. 1429591 "Installation of cathodic protection" , No. 2091503 “Device for cathodic protection against atmospheric corrosion”, No. 2394943 “Device for cathodic protection of gas pipelines and underground structures”].

Also known is the “System of cathodic protection of trunk pipelines” [RU patent for invention No. 2202001], which includes several cathode stations, each of which contains a unit for measuring and processing information, a polarization potential sensor, a corrosion rate sensor, a hydrogen pickup sensor, a receiving unit and transmission, reference electrode, logic, telemetry and teleregulation unit, switching unit for measuring protection parameters, phase adjustment unit, pulse modulation unit and selective filter. To stabilize the potential, depending on the measurement results of the signals from the sensors of the potential, corrosion rate and hydrogen pickup, the parameters of the output pulse signal are changed.

The above devices are characterized by insufficiently high accuracy of maintaining the polarization potential, due to the fact that stabilization of the polarization potential is carried out by modulation of the temporal parameters of the pulse signal supplied to the structure, as well as the fact that during stabilization of the potential an indirect estimate of the actual value of the potential of the structure is used in the form of the auxiliary potential electrode.

Also known is the “Wind Farm of Cathodic Protection of Pipelines” [RU patent for invention No. 2117184], the principle of which is to form a pulse voltage on the pipeline relative to the anode earthing switches with relay control of the protective potential, the current value of which is controlled by a reference electrode. In this case, if there is an output current of the station flowing in the pipeline-soil-anode ground electrode circuit, the current value of the pipe-soil potential is compared with a threshold value corresponding to the maximum critical value of the potential, above which the output current of the station is turned off, and if not the output current of the station, the value of the potential "pipe-soil" is compared with a threshold value corresponding to the minimum critical value of the potential, at a decrease below which, the output current of the station is turned on. Thus, the time parameters of the output pulse signal of the station are set by the nature and rate of change of the protective potential.

This station is characterized by large ripple potential during stabilization (from -0.85 V to -1.5 V). In addition, the duration of the pulse of the output current of the station and its pause time can vary significantly during operation, which imposes stringent requirements on the power source of the cathode station. When the operating conditions change, a situation may arise in which the power of the station becomes insufficient to increase the potential to the upper threshold value. The cathode station will remain with a continuously-switched output current and the advantage of the pulsed operation mode of the station is lost. In addition, this can lead to failure of the cathode station power source.

The closest analogue of the claimed utility model is a “Device for protection against corrosion by pulsed current” [RU patent for invention No. 2223346], containing an electronic unit with a direct current source, a pulse amplifier and a pulse shaping circuit installed in a conductive medium at a given distance from the protected structure, grounding device, measuring electrodes of the potential of the protected structure and polarization potential. The direct current source is connected through a pulse amplifier to the protected structure and to the grounding device. The measuring electrodes are connected to a pulse generating circuit of the electronic unit. The output of the latter is connected to the control input of the pulse amplifier. Between a constant current source and a pulse amplifier, a charger and an energy storage device are installed in series.

The disadvantages of the closest analogue are: low accuracy of maintaining the potential and the unevenness of maintaining the potential throughout the protected section of the pipeline.

The objective of the claimed utility model is to increase the accuracy of maintaining the polarization potential throughout the protected area.

The essence of the claimed utility model lies in the fact that in the installation for pulsed cathodic protection containing an electronic unit, an anode ground electrode and a reference electrode, the electronic unit of which contains a direct current source, a pulse amplifier, a pulse shaper, an energy storage device connected to a pulse amplifier, which is connected with a pulse shaper, with an anode ground electrode system and a protected structure, and a reference electrode connected to a pulse shaper, the electronic unit is connected to the drive w energy pulse shaper, a source of DC constant voltage level converter, wherein the DC power source is connected to the pulse generator connected to the protected construction.

The technical result of the claimed utility model is to solve the problem.

The output power control in the inventive installation, necessary to maintain the potential, is carried out by changing the amplitude parameter of the output pulse signal, in contrast to the prototype, where its time parameters (duty cycle or frequency) change. The proposed approach allows to eliminate or significantly reduce the variation in potential along the length of the protected section of the pipeline, which is a "long line" with distributed parameters, including both active and reactive components, and which has its own impedance for each protected structure. Since the inventive installation works essentially like a pulse generator with its own output impedance, the degree of matching of this resistance with the wave impedance of the section of the protected structure, as well as the time parameters of the output pulse signal of the installation, significantly affect the processes occurring in this section of the protected structure. If the potential signal and the temporal parameters of the pulse signal supplied to the protective structure change during stabilization, uncontrolled significant non-uniformity of the potential change in individual segments of this section may occur due to the resonance phenomenon. To eliminate this phenomenon, before putting into operation, the optimal time parameters of the pulse output signal of the installation are selected for this section of the protected structure, and the potential is stabilized by changing the amplitude of the output pulse. To implement the latter, a constant voltage level converter has been introduced into the installation as a functionally independent essential feature and its attendant connections with other units of the installation as functionally dependent essential features.

The use of the polarization potential of the protected structure as a sensor, and not its equivalent in the form of an auxiliary electrode (see position 9 in Figure 2 in the description of the closest analogue), improves the accuracy of maintaining the polarization potential. The potential generated at the auxiliary electrode is an indirect assessment of the real value of the potential of the protected structure. In the proposed installation, an indirect assessment of the polarization potential is replaced by a real value, taken directly from the protected structure. For this, a connection is introduced between the protected structure and the pulse shaper.

The inventive utility model is illustrated using Fig.1-3, which depict: Fig.1 is a schematic representation of the installation for cathodic protection, Fig.2 is a timing diagram of the operation of the installation, Fig.3 shows the oscillograms of the polarization potential in a real pipeline obtained using a digital storage oscilloscope type DC5042M firm RIGOL.

1-3, the positions 1-8 indicate:

1 - electronic unit;

2 - anode grounding;

3 - reference electrode;

4 - a direct current source;

5 - pulse amplifier;

6 - pulse shaper;

7 - energy storage;

8 - DC voltage level converter.

The installation contains an electronic unit 1, anode ground electrode 2, reference electrode 3.

The electronic unit 1 contains a direct current source 4, a pulse amplifier 5, a pulse shaper 6, an energy storage device 7, a constant voltage level converter 8.

The outputs of the pulse amplifier 5 are connected to the anode ground electrode 2 and the protected structure, which is also connected to the second input of the pulse shaper 6, the first input of which is connected to the reference electrode 3. The first output of the pulse shaper 6 is connected to the control input of the pulse amplifier 5, the inputs of which are connected with the conclusions of the energy storage 7 and the outputs of the DC voltage level converter 8, the control input of which is connected to the second output of the pulse shaper 6, the power inputs of which are connected inens with outputs of a direct current source 4 and inputs of a transformer of a constant voltage level 8.

A description of the operation of the installation is illustrated by the timing diagrams shown in FIG. 2 and the voltage plots shown in FIG. 3. Installation for pulsed cathodic protection works as follows.

Before starting work in the setup mode, the operator, using the control and display panel (not shown in the figure), sets the value of the polarization potential, which should be automatically maintained during the operation of the installation. In addition, the time parameters of the output signal of the pulse amplifier 5 are recorded in the memory of the pulse shaper 6 by technical programming tools, including the pulse duration, the duration of the pause between pulses, the time delay after the end of the pulse, after which the polarization potential is measured.

After the transition to the operating mode, the pulse shaper 6 generates a signal at the control input of the converter of the DC voltage level 8 that determines the initial value of its output constant voltage.

When voltage appears on the terminals of the energy storage device 7 (time point T0 in FIG. 2 of diagram 1), the process of accumulation of electric energy begins in it, after which the pulse shaper 6 generates a signal at the control input of the pulse amplifier 5 that determines the time parameters (pulse duration and duration pauses between pulses) of its output pulse signal generated on the anode ground electrode 2 relative to the protected structure.

In this case, the initial and subsequent sections of the potential change curve, the intervals T2-T7, T4-T8 and the intervals T7-T3, T8-T5 (Figure 2, diagram 3), have a significantly different slope, since the initial section (intervals T2- T7, T4-T8 Figure 2, plot 3) corresponds to a change in the ohmic component of the potential, and the subsequent section (intervals T7-T3, T8-T5 of Figure 2, plot 3) corresponds to a change in the polarization component, which decreases significantly more slowly than the ohmic component. Due to the fact that the setup should stabilize the polarization potential, the measurement of its actual value should be carried out after the disappearance of the ohmic component. To this end, the pulse shaper 6 measures the potential after the ohmic component of the potential disappears (time instants T9, T10, etc. in Fig. 2, see also plot 3 in Fig. 3 - section of the transition of the potential curve from steeper to more gentle) .

The time interval during which the ohmic component of the potential decreases to an insignificant value depends on many factors and can take values from 10 μs to 300 μs. In this regard, it is advisable to initialize the installation into operation at a specific protected facility to measure this interval using a storage oscilloscope and write it to the pulse shaper 6. To protect the measurement result from accidental influences, the average value should be taken as the measured value of the polarization potential at least ten measurements, i.e. each measurement of the polarization potential must be carried out for at least ten periods of the output signal, after which its average value is calculated. The pulse former 6. Measured in this way by the polarization potential, compares it with the value set during tuning and changes, with the help of a constant voltage level converter 8, the amplitude of the output pulse of the installation in the phase necessary to stabilize the polarization potential at a given level. For example, if the measured value of the polarization potential is less than the specified value, then the amplitude of the output pulse of the setup increases; if it is more than the specified value, it decreases.

Implementation example.

As a source of direct current 4, any AC 230 V to DC 24 V voltage converter with an output current of 16 A can be used, operating in the temperature range from (-45 to +45) ° C. DC source 4 can also be made according to the standard circuit (Titz U., Schenk K. Semiconductor circuitry. Dodeka XXI p. 254), in which a transformer TPP319 can be used, as a diode bridge KBPC-25-06- W, as a filter capacitor - three capacitors connected in parallel to K50-35-4700 μFx50V. Energy storage 7 can be made in the form of a set of capacitors K50-35 - 3300 μFx63V, connected in parallel, in the amount of 50 pcs. Pulse amplifier 5, can be implemented on a transistor IRF4905. As a reference electrode 3, a copper-sulfate reference electrode ENES-ZM can be used. As the anode ground electrode 2 can be used oxide iron-titanium ground electrode.

Pulse former 6 can be implemented on a PIC controller type PIC24FJ256GA106-I / PT.

The DC voltage level converter 8 must provide both an increase and a decrease in the input voltage. In this regard, it is made in the form of series-connected step-down and step-up converters. The step-down converter is made on the uA78S40 chip, the IRF4905 key transistor, and the MBR20100CT return diode. The boost converter is made on a UC3844 chip, a key transistor IRF3710, a reverse diode MBR20100CT. The common storage element is made on a choke with a working current of 10A and an inductance of 0.6 mlH.

The control, indication and signaling panel not shown in FIG. 1 can be implemented as a set of potentiometers (type SP4-1) for setting analog parameters, as well as rocker (type SS-309) and push-button (type SPA-106) switches to form discrete control signals and on a specialized control chip indicators MAX6925EPL and five LED matrix type BC56-12EWA. The audible alarm can be realized using a piezo emitter type PCM13EPYH.

The interface not shown in FIG. 1 for communication with a remote operator can be implemented on the ADM3485 chip.

The period of the pulse signal during the experiments varied from 100 mlsec to 10 mlsec., And the pulse duration, respectively, from 10 mlsec to 1 mlsec. The fill factor varied from 0.05 to 0.2. The voltage amplitude varied from 10 V to 48 V. In this case, the dependences of the potential change measured by the oscilloscope after disconnecting the voltage from it at various real objects - pipelines with different parameters showed that the steep section on the potential change graph (T2-T7 in Figure 2), corresponding ohmic component of the potential, can be from 10 μs to 300 μs. The values of the stationary potential ranged from -0.55 V to -0.6 V.

The claimed technical solution is made in the form of a prototype that has successfully passed testing in one of the organizations in the city of Saratov.

Claims (1)

Installation for pulsed cathodic protection, containing an electronic unit, anode ground electrode and a reference electrode; the electronic unit contains a direct current source, a pulse amplifier, a pulse shaper, an energy storage device connected to a pulse amplifier, the latter is connected to a pulse shaper, with an anode ground electrode and a protected structure, the reference electrode is connected to a pulse shaper, characterized in that its electronic block has a connected to a power storage device, a pulse shaper, a direct current source, a constant voltage level converter, while the direct current source is connected pulse shaper connected to the protected construction.