Device for protection against corrosion of pulsed current

 

The invention relates to the field of cathodic protection from corrosion. The technical result - improving the efficiency of protection. Device for protection against corrosion of pulsed current metal structures placed in a conductive environment, contains a power source DC is connected through a pulse amplifier to the protected building and is set in a conductive environment at a given distance from protected structures grounding device. The device also contains placed in a conductive medium, the electrodes measure the potential of the protected structure and the electrode measuring the polarization potential connected to the pulse forming network, the output of which is connected to the control input of the pulse amplifier. Between the power source and pulse amplifier installed in series charger and power storage. The pulse forming network includes a device, such as a controller for regulating a functional dependency relationship duration current pulse to the period between pulses from the potential difference between the electrodes, and generates a pulse current and/or gap between impelentation. The device allows to reduce energy consumption and eliminate the development of stress-corrosion, increases the turnaround interval of protected structures. 10 C.p. f-crystals, 3 ill.

The invention relates to cathodic protection against corrosion of the objects located in a conductive environment, and can be particularly effectively used for the protection of pipelines in the oil and gas industry, as well as in urban municipal services.

The prior art Known and widely used now cathodic protection station DC located in earth structures do not provide the uniformity protect them from corrosion. Facing the anode to the grounding surface, underground and underwater structures are protected better than surface facing in the opposite direction. To increase the coverage of cathodic protection extended objects, which are, in particular, pipelines, it is necessary for the cathodic protection stations to set the high voltage, which leads to the dissociation of water near the points of connection of stations to those objects. The hydrogen produced during the dissociation of water into the metal protected structures and groupsyahoocom, causing the need for unscheduled repairs. If near protected structures are other metal objects, then branches off to them talk of protected structures causes accelerated corrosion destruction of this building in the areas of branch current. In addition, protection of objects with a constant current consuming power unnecessarily increasing operating costs for protected structures. The use of pulsed currents eliminates or substantially reduces the above-mentioned disadvantages of the protection of underground structures by DC.

In the literature [Petukhov Century C. "Integral", 1, 2001, S. 14 - 16] describes the basic theory of corrosion protection of pulsed current. On the basis of the classical ideas about the motion of charged particles in the conductors of the second kind and phenomenological diffusion equation in one-dimensional approximation for the protection of pulse currents were obtained by the maximum possible ratio between the pulse duration and pause between them: T//2D, which must achieve a minimum concentration of corrosive negatively src="https://img.russianpatents.com/chr/964.gif">- pulse duration,- the mobility of ions,electrochemical potential of the metal protected structure, D is the diffusion coefficient.

This ratio has the same scope as the above-mentioned theory. In the case of point defects in the insulation should be applied two-dimensional approximation, which gives a much smaller value of the ratio T/. It is noteworthy that this relationship is not explicitly included frequency. This circumstance leads to greater flexibility of application of the pulse method of corrosion protection to a variety of securable objects. The mobility of ionsand the diffusion coefficient D significantly depend on the composition of the soil, so to achieve the greatest efficiency of pulse protection it is necessary to study the parameters of the environment and, in particular, the composition of the soil near the protected object. It should be noted that the diffusion coefficient D grows faster with increasing temperature than the mobility of ionstherefore , the efficiency of pipeline protection, pulse currents during transportation of the heated gas or liquid will be lower than if up>oWith the ratio T/for ions of oxygen, not more than 52, for chloride ions is not more than 44. These figures show what savings can give the impulse system of protection of pipelines against corrosion compared to protection systems by DC.

One of the first such devices is samootkryvayuschiesya device cathodic protection boats pulse current [U.S. Patent 3242064, M CL8C 23 F 13/00 from 22.03.1966] , which was changed this ratio is proportional to the potential difference of the reference electrode and the protected surface. In this device, the environment in which you have placed the protected object is premazepam element for the control circuit of the pulse frequency. If for boats and other small objects, this approach is quite justified, for extended structures, which are, for example, pipelines, properly configure the operation of this device will fail, because even in one section of the environment settings are highly dependent on many factors (temperature, pressure, humidity, time of year, frequency and duration of rainfall, and so on). Therefore, a simple feedback is not enough. You must install the control law (transfer function) via device is small, the scope of protection extended structures, due to lack of pulse power developed by the power source (battery) and a high pulse repetition frequency (1-200 Hz). Extended structures, which certainly include all piping, have a large private capacity and inductance, so they integrate passing the current pulses. For example, according to literature data [Sergiovanni C. T. and other Pipeline as a channel of communication in remote control systems. M., "Nedra", 1984, S. 12-15] native capacity of one kilometer pipeline with a diameter of 1 m is 4 PF, and the inductance - 120 mH. Calculations and practice show that the impulses from the above pulse device will turn into a permanent slightly pulsating current on the second kilometer of such a pipeline. Thus losing the advantages of the pulse mode. Install the same in every kilometer pipeline separate pulse device is not justified from an economic point of view.

Another method and device protection piping pulsed current, proposed in the U.S. [U.S. Patent 3612064, M CL8B 01 D 13/02 from 12.10.1971]. In the proposed device the power capacitor of small capacitance is fully discharged through the thyristor on OCA frequency of this device was fixed and could be set in the range from 2 to 5 kHz. At this frequency the impedance of the pipeline increases hundreds of times compared to its DC resistance [Sergiovanni C. T. and other Pipeline as a channel of communication in remote control systems. M., "Nedra", 1984, S. 15], therefore, to extend the range of the pulse mode, had to raise the output pulse voltage devices up to 150-300 Century to Use such a strain on gas pipelines and oil pipelines is unacceptable from a security point of view, therefore, the proposed device has a limited scope.

In the future, the authors improved their invention [U.S. Patent 3692650, M CL8C 23 F 13/02, 19.09.1972], proposing to apply the pulse voltage at the resonant frequency of the electric circuit formed of the protected structure serving as a cathode, the environment in which is located a structure and an anode placed in this environment. When this was achieved the significant energy savings, but at large distances from the place of connection of the device to the extended object to implement the pulse mode, giving the well-known advantages, it was not possible, because the pulses are integrated into constant bit pulsating current. To carry out the conversion of the acid ions and impulsiv from 7 to 60 μs, however, the high pulse voltage 150-300 In issued proposed device smoothes the selectivity of the electrochemical reactions caused by the pulse duration, and initiates the flow of useful and harmful chemical reactions in soils, such as the decomposition of water into oxygen and hydrogen, so that the device does not completely solve the problem of absorption of securable objects.

Subsequently, one of the authors - Donigan perfected this switching device [U.S. Patent 5324405, M CL8C 23 F 13/00 from 28.06.1994] and added a circuit interrupting current inductance continuing to flow in the load after completion of the pulse voltage, pulse issued by the device. This allowed to reduce the effects of stray currents caused by the presence in the environment of extraneous metal structures, and to provide more uniform distribution of the protective potential both along the extensive protected structures and in the transverse direction. However, the high voltage at the output of the device limits the scope of its application, especially in the oil and gas industry.

The decrease of the output voltage pulse of resonant devices type frame exponential growth of the wave load resistance with increasing frequency. To lower pulse operating voltage for the device, it is necessary to reduce the frequency and, consequently, to increase the pulse duration. Therefore, the lower limit of the pulse duration is limited by the inductance and capacitance of the protected object, which is defined primarily by its length. On the other hand, the pulse duration is limited to the beginning of the gassing. It was established experimentally that in a strong alkali solution (KOH) with a concentration of 350 g/l gassing begins at 10 seconds after turning on the pulse. In the different composition of the soils this time will be different, but not much.

Based on these considerations, it was proposed method of protection gas and/or gas condensate pipelines, oil pipelines and/or pipeline, water pipeline engineering construction and complex facilities for the extraction and transportation of gas, oil and water [RF Patent 2172887, M CL8F 16 L 58/00 from 27.08.2001]. The method involves the use of pulses of duration 1 MS - 10 s Interval between pulses is determined from the ratio of the time interval between pulses to their duration, which must not exceed relations drift velocity cause corrosion of the item. The specification of this provision leads to the formula above: T//2D. Closest to the invention the device is a device for the protection against corrosion of pulsed current metal structures placed in a conductive medium containing an electronic unit with a constant current source, a pulse amplifier and a pulse forming network, installed in a conductive environment at a given distance from protected structures earthing device, the electrodes measure the potential of the protected structure and potential polarization, in which the constant current source is connected through a pulse amplifier to the protected structure and the ground device, the measuring electrodes connected to a pulse forming network, the output of which is connected to the control input of the pulse amplifier (see U.S. Patent 3242064, M CL8C 23 F 13/00 from 22.03.1966).

This device, like all mentioned above may not work effectively and efficiently in the corrosion protection of buildings of considerable length, such as pipes, because the pulses of short duration, issued in the extensive structures. Another significant disadvantage of this device that prevents its use for protection of extended objects, is the inclusion of environment in frameshadow chain of the pulse generator. The environmental parameters may change along the length of the extended object, in addition, the environment settings depend on the abundance of precipitation, soil temperature, atmospheric pressure, time of year and so on, so a simple dependency relationship of pulse duration to the duration of the pause between pulses from the magnitude of the polarization potential can be sufficient to complete overlap of the ranges of frequency and pulse duration from the point of view of economical and reliable protection against corrosion. The third disadvantage of limiting the area of protection of this device, due to the use of low-power DC source (battery), is easily overcome by using as the primary power source AC and the rising level of the output pulse voltage, however, this technical solution is in conflict with safety requirements on oil and gas pipelines.

Disclosure of the invention
Order ultramediatisee in pulsed mode, created the present invention.

For this purpose, the device for protection against corrosion of pulsed current metal structures placed in a conductive medium containing an electronic unit with a constant current source, a pulse amplifier and a pulse forming network, installed in a conductive environment at a given distance from protected structures earthing device, the electrodes measure the potential of the protected structure and potential polarization, in which the constant current source is connected through a pulse amplifier to the protected structure and the ground device, the measuring electrodes connected to the pulse forming network of the electronic unit, the output of which is connected to the control input of the pulse amplifier, according to the invention between the constant current source and a pulse amplifier installed in series charger and power storage. This allows you to get the pulse is much greater (up to 10) duration than in known devices. Such pulses do not have time to pointerisovatsya at significant distances from the point of connection of the electronic unit to the pipeline and can effectively protect from corriveau operation of the device when changing the physical properties of the conductive corrosion-hazardous environment the pulse forming network includes a device for controlling a functional dependency relationship duration current pulse to the period between pulses from the potential difference between the electrodes.

In addition, a device for controlling a functional dependency relationship of pulse duration to the interval between pulses from the potential difference between the electrodes is made in the form of a device for forming the duration of the current pulse and/or duration of the interval between pulses. This allows to increase the coverage area of corrosion protection and to implement the most economical mode when synchronous operation of multiple devices on adjacent sites.

To increase functionality and the implementation of some service functions of the electronic unit the control unit functional dependency relationship of pulse duration to the interval between pulses from the potential difference between the measuring electrodes are made in the form of the controller.

To extend the range of pulse durations in the direction of increasing the drive power is made in the form of a capacitor with a double electric layer.

To increase the pulse amplitude and increasing the coverage of extended structures corrosion protection the drive power is made in the form of a capacitor Bank.

For the implementation of the service functions of the electronic unit sabrailov on the measuring electrodes, output voltage and current of the electronic unit, and a count time of operation of the device at the specified interval, the potential difference between the measuring electrodes.

For current limiting inductance resulting from the inductive nature of the load on the output terminals of the electronic unit after termination of the current pulse amplifier at the output of the pulse amplifier mounted current-limiting device.

To prevent destruction of the electronic unit when lightning strikes to the protected structure, grounding device or the connecting wires at the output of the pulse amplifier installed lightning protection device.

To extend the functionality of the device and reduce operating costs constant current source made with the possibility of connection to the electrical network.

To prevent destruction of the electronic unit when lightning strikes to the power grid at the entrance to the constant current source from the network, installed additional lightning protection device.

Thus, the essence of the invention lies in the fact that for the protection of the longest structures in the electric circuit device is inserted nakopitelnuy transistor to the load, formed by grounding, conductive environment and the protected structure, is placed in this environment, and the pulse duration is set by the pulse forming network, which introduced a controller that determines the duration and the pulse frequency depending on the potential difference of the reference electrode and auxiliary electrode is also placed in this environment. The introduction of a storage capacitor of a large capacity with operation of the protective device in pulsed mode was enabled to apply a relatively low constant current source while maintaining the effectiveness of the corrosion protection.

Brief description of drawings
In Fig. 1 shows a functional diagram of the device for the protection against corrosion of pulsed current; Fig.2 is a structural diagram of the device of Fig.3 is a chart of the time variation of the polarization potential in the device.

The best option of carrying out the invention
The block diagram in Fig.1 explains the principle of operation of the pulse device protection against corrosion, which contains the constant current source 1, the power storage 2, the transistor 3, the pulse forming network 4, the grounding device 5 shown in Fig.1 in the form of three Otsa specified distance from protected structures 7. Near protected structures are measuring electrodes: electrode 8 measurement of the polarization potential (menoselricky the reference electrode MSAS) and the electrode 9 measuring the capacity of protected structures (auxiliary electrode).

The best embodiment of the invention implemented with the protection of pipelines with the help of the device block diagram is shown in Fig.2. From the wall outlet voltage is applied through the circuit breaker 10 and the ground device 11 on the power transformer 12. The secondary winding of the power transformer 12 is connected to the rectifier 13. In this implementation, the power transformer 12 and rectifier 13 form a constant current source, indicated in Fig. 1 figure 1. The output of the constant current source 1 is connected to the input of the charger 14. The output of the charger 14 is connected to the power storage 2, representing in this case a capacitor Bank with double electric layer, which has a large (up to 300 f) electric capacity. The power storage 2 is connected to a pulse amplifier 15 (in particular, if it can be made in the form of transistor 3, see Fig.1), the output of which through the limiting device 16, actionsa chain, consisting of a grounding device 5, a conducting medium 6, and protected structures (pipeline) 7. On one of the conductors connecting the pulse amplifier 15 the output terminals 18 or 19, a current sensor (not shown) connected to the first input of the controller 20. One of the outputs of the controller 20 is connected to the feedback amplifier 21, which, in turn, is connected with retarded blocking oscillator 22 and the pulse generator 23. The pulse generator 23 is connected through the switch to slow the blocking oscillator 22 and directly with the control input of the pulse amplifier 15. The second input of the controller is connected to the electrode 8 of the measurement of the polarization potential (reference electrode) and the electrode 9 measuring the capacity of protected structures (auxiliary electrode). The third input of the controller 20 is connected to the network input of the constant current source 1. The fourth input of the controller 20 is connected to the power storage 2. The second output of the controller 20 is connected to the indicator 24, the third output of the controller 20 connected to the sound detector 25, the fourth output of the controller 20 is connected to the interface 26, and the fifth output of the controller 20 is connected to the counter, taking into account the time 27. All these nodes positive electrodes 8 and 9 are placed in the housing of the electronic unit 28.

The device operates as follows. The constant current source 1 charges the power storage 2, made for example in the form of a capacitor of a large capacitance (capacitor with a double electric layer). The power storage 2 is discharged through the transistor pulse amplifier 3 to the load formed by the grounding 5, the conductive medium 6 and the protected structure (pipeline) 7. To the input of the pulse-forming network 4 is the potential difference of the reference electrodes 8 and the auxiliary electrode 9. Depending on the potential difference measuring electrodes 8 and 9, the pulse forming network 4 produces pulses, the duration and frequency of which is changed so that the ratio of the duration of the pause between pulses to the pulse duration was increased with increasing polarization potential and, conversely, decreased with decreasing potential polarization.

The circuit breaker 10 is designed to disable the device under overload conditions, such as failure of power transformer 12 and rectifier 13, and when lightning strikes in the electrical network. In the latter case, triggered lightning protection device 11, proposeci switch 10 and to prevent the destruction of the other expensive functional units of the electronic unit 28.

The power transformer 12 lowers the voltage to levels required for other energy-consuming devices of the electronic unit 28.

Relatively low current rectifier 13 converts AC power to DC power through the charger 14 with a special charging characteristics charging the power storage (battery capacitors electric double-layer) 2. Storage capacitor of large capacity 2 partially discharged through the pulse amplifier 15 to the load formed by a serial electrical circuit containing the grounding 5, a conductive medium 6 and the protected structure 7, which is a pipe or casing pipe in the well.

Current-limiting device 16 limits the emission voltage of the opposite polarity at the output terminals 18 and 19 of the electronic unit 28, due to the inductive nature of the load and by circulating currents.

Lightning protection device 17 connected directly to the output terminals 18 and 19, protects the electronic unit 28 from damage due to lightning strikes in the pipe 7, the grounding 5 or wires connecting the earthing between themselves and with the electronic unit 28.

The electrode 8 relative to the x, when the protection of small structures and the absence of interference, the auxiliary electrode 9 can be eliminated. Then the corresponding output at the input of the controller must be connected to the protected structure 7. In Fig.3 is a diagram of a change in time (sec) potential (V) polarization auxiliary electrode is measured relative to mediasurface reference electrode (MSAS). On the chart there is a rapid increase in potential polarization during the current pulse duration of 2 s and a relatively slow decline within 8 between them. The controller 20 processes the incoming with these electrodes, the signal and delivers it to the feedback amplifier 21. The feedback amplifier 21 generates a control signal affecting ramasadaya chain master pulse generator 23 in such a way as to change the frequency and/or duration of pulses produced by the master oscillator 23, to maintain the polarization potential of the protected structure 7 at the optimum level.

When installed on the protected object one device protection depending on the electrical characteristics of this object (inductance, capacitance etc ) and environment (specific resistance) is the basic duration of the extent of change of polarization potential is changed, accordingly, the frequency (duration) of the pulse.

If the adjacent pipe section operates the same pulse protection device, to improve work efficiency, you must synchronize their pulses. For this purpose, functional scheme introduced inhibited the blocking oscillator 22. There are circuit options, which combine in a single node specifies the pulse generator and inhibited the blocking generator. In the case of work on protected device has several protection devices presenter mode is set protection device, which is the most severe operating conditions. The frequency of the pulse mode other protection devices are synced automatically with the help of retarded blocking oscillator, and the most economical mode of the slave device protection is achieved by changing the pulse duration (time between pulses).

The controller 20 also serves signals from the current sensor installed on any part of the high-current wires (for example, the wire passing through the shielding device 17), and voltage sensors, installed at the entrance to the electronic unit 28 in front of the transformer 12, and the drive of elekes any of the monitored parameters is displayed on the indicator 24 or through the interface 26 is transmitted to the base computer. If one of the monitored parameters are outside of the predetermined values, the controller provides an alarm signal at the buzzer 25 and signal LEDs (not shown). The time counter 27 allows to control the time interval during which, for whatever reason, the device did not work in the specified mode.

Industrial applicability
All electronic components of the device contain elements serial industry. Assembly and adjustment of the electronic unit of the device is feasible in terms radiomontazhnogo shop and do not require special tooling and equipment. One of the variants of the device was tested on the initiative and showed satisfactory results.


Claims

1. Device for protection against corrosion of pulsed current metal structures placed in a conductive medium containing an electronic unit with a constant current source, a pulse amplifier and a pulse forming network, installed in a conductive environment at a given distance from protected structures earthing device, measuring the electrode potential of the protected structure and potency and to a grounding device, the measuring electrodes connected to the pulse forming network of the electronic unit, the output of which is connected to the control input of the pulse amplifier, characterized in that between the constant current source and a pulse amplifier installed in series charger and power storage.

2. The device under item 1, characterized in that the pulse forming network includes a device for controlling a functional dependency relationship duration current pulse to the period between pulses from the potential difference between the measuring electrodes.

3. The device according to p. 2, characterized in that the device for regulation of a functional dependency relationship of pulse duration to the interval between pulses from the potential difference between the measuring electrodes are made in the form of the device forming the duration of the current pulse and/or duration of the interval between pulses.

4. The device under item 2 or 3, characterized in that the control unit functional dependency relationship of pulse duration to the interval between pulses from the potential difference between the measuring electrodes are made in the form of the controller.

5C electric double layer.

6. Device according to any one of paragraphs.1-5, characterized in that the drive power is made in the form of a capacitor Bank.

7. Device according to any one of paragraphs.1-6, characterized in that the electronic unit is equipped with control devices, signaling and data transfer voltage power source, the potential difference measuring electrodes, the output voltage and current of the electronic unit, and a count time of operation of the device at the specified interval, the potential difference between the measuring electrodes.

8. Device according to any one of paragraphs.1-7, characterized in that the output of the pulse amplifier mounted current-limiting device.

9. Device according to any one of paragraphs.1-8, characterized in that the output of the pulse amplifier installed lightning protection device.

10. Device according to any one of paragraphs.1-9, characterized in that the constant current source made with the possibility of connection to the electrical network.

11. The device according to p. 10, characterized in that the input to the constant current source installed additional lightning protection device.

 

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SUBSTANCE: electronic drainage can be used for protecting pipelines against stray current induced by rail electric transport. Electronic drainage has circuit, which connects unit to be protected against corrosion induced by stray currents and electric transportation vehicle rail provided with differential transformer. Circuit has three parallel branches. The first one has filtering capacitor, the second one - first electronic two-sided switch and first reactor, the third branch has second two-sided electronic switch, second reactor and recuperating capacitor. Midpoint of second branch disposed between first two-sided electronic switch and first reactor is connected to midpoint of third branch through third electronic two-sided switch. Third branch is disposed between second reactor and recuperating capacitor. Both potentials, as positive and negative, can be taken from pipeline. Short time of "rail-pipeline" capacity discharge is provided. Drainage can be used widely for currents up to 1000 A.

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2 cl, 1 dwg

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2 tbl, 1 dwg, 1 ex

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3 dwg

FIELD: electricity.

SUBSTANCE: invention relates to protection of metal articles from corrosion. The device for pipeline protection from action of leaking in and out constant and alternating currents induced from external ground current sources contains the capacitor unit for alternating current filtration placed in an electric cabinet, and it is designed with a possibility of connection to the cathodic protection station of (CPS) and in addition contains a rectifier diode bridge with a possibility of connection between CPS anode grounding conductor and the protected pipeline parallel to CPS output, and a ballast load resistor connected to the output of the rectifier diode bridge parallel to the capacitor unit.

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1 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to field of cathode protection of metal objects against corrosion and can be applied for objects, which are in contact with electricity-conducting liquid. Device contains antenna electrode for supply of electrical load current into electricity-conducting liquid, protective electrode, source of protective current, electrically connected with conducting part of surface and protective electrode, with source of protective current being made with possibility of changing protective current in response to change in load current. Method includes supply of load current into electricity-conducting liquid, change of protective current in response to change in load current, with protective current flowing between electricity-conducting part of surface and protective electrode. Processor device contains computer programme for realisation of control of cathode protection of object by said method.

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1 tbl, 1 ex

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