A device for inhibiting erosion corrosion of a bend by liquid-solid two-phase flow
By combining flow field structure control and cathodic protection technology, the scouring and corrosion of bends is reduced by using helical flow, thus solving the problems of scouring and corrosion in multiphase flow of bends and achieving comprehensive protection for bends.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-02
- Publication Date
- 2026-03-24
AI Technical Summary
In the existing technology, the application of cathodic protection methods on the inner wall of pipes is limited, and it cannot effectively suppress erosion corrosion in multiphase flow in bends, especially erosion damage caused by solid particles. Furthermore, the application of helical flow at bends has not been fully utilized to reduce erosion.
Combining flow field structure control technology and cathodic protection technology, a liquid-solid two-phase flow erosion corrosion suppression device for bent pipes is designed. The spiral flow generated by the spiral tube reduces the erosion effect of solid particles on the bent pipe, and the cathodic protection system suppresses electrochemical corrosion, thus achieving comprehensive protection for the bent pipe.
It effectively suppresses scouring and corrosion at pipe bends and their synergistic effects, improving the operational safety and economy of pipe bends and simplifying protective measures.
Smart Images
Figure CN117512601B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of pipeline erosion corrosion protection, and particularly relates to a bend liquid-solid two-phase flow erosion corrosion inhibition device based on a spiral pipe and forced current cathodic protection. BACKGROUND
[0002] Pipeline erosion corrosion is a common problem in different industries including the petroleum and natural gas industry. Various pipes, equipment and fittings exposed to flowing fluids, especially multiphase flow containing solid particles, will be subjected to erosion corrosion to varying degrees. Erosion corrosion will aggravate the mass loss of metal materials, and even cause pipeline perforation, thereby leading to serious economic losses and environmental problems.
[0003] Erosion corrosion is the result of the combined action of corrosion and erosion, and is caused by the rapid flow of any unstable fluid on the metal surface. Corrosion is mainly a process of material degradation caused by chemical or electrochemical action, while erosion is a purely mechanical damage. The combined effect of the two processes in a liquid environment is considered to be erosion corrosion. The combined action of erosion and corrosion can be significantly higher than the sum of the individual processes, and this net effect is called synergistic effect. This net effect is due to the fact that erosion enhances corrosion and corrosion enhances erosion, so erosion corrosion is considered to be an important risk of localized corrosion.
[0004] Bends are indispensable components in fluid conveying pipelines, but due to the complexity of their geometry, the flow pattern and the movement of solid particles in the bends change significantly, resulting in a much greater degree of erosion corrosion damage to the bends than to the straight pipe sections. Moreover, there are significant differences in erosion corrosion behavior at different parts of the bend, which brings great difficulties to the prediction and prevention of bend erosion corrosion. Therefore, how to effectively prevent and control the erosion corrosion of bend multiphase flow has become a key problem to improve the safety and economy of pipeline operation.
[0005] Among the current methods for controlling erosion corrosion, cathodic protection is an effective and relatively economical corrosion control method, and has been widely used in the external corrosion protection of metal facilities such as underground pipelines, oil well casings and marine steel structures. However, due to the particularity of the internal structure of the pipeline, the application of cathodic protection technology to the inner wall of the pipeline is still limited. Moreover, cathodic protection is an electrochemical protection method, which only has a good inhibitory effect on the metal material damage caused by electrochemical action, but has no obvious erosion reduction effect on the erosion damage caused by solid particles. Therefore, to some extent, the application of cathodic protection method in the prevention of pipeline erosion corrosion is limited.
[0006] Pipe spiral flow has the characteristics of uniform cross-sectional concentration distribution, low energy consumption, long conveying distance, strong carrying capacity, etc., and has been widely used in the fields of oil and gas exploitation and transportation, solid-liquid separation, pneumatic conveying and other industrial fields. Spiral flow theory and numerical simulation show that in the spiral flow hydraulic transportation, the spiral flow can effectively reduce the erosion rate of the key position of the elbow and the pipe accessories by reducing the fluid velocity in the pipe, suspending the settled particles in the fluid, and improving the particle distribution at the key position of the pipe.
[0007] Therefore, in the process of liquid-solid two-phase flow transportation, it is necessary to study how to use spiral flow and cathodic protection together to fully utilize the advantage of spiral flow in reducing the scouring effect of solid particles, so as to provide a simple and efficient method for preventing the scouring corrosion of the elbow multiphase flow. SUMMARY
[0008] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art, and to provide a bend liquid-solid two-phase flow scouring corrosion inhibition device, which combines flow field structure control technology and cathodic protection technology to inhibit the scouring and corrosion components and their synergistic effect components in the scouring corrosion from the aspects of fluid mechanics and electrochemistry, thereby effectively preventing the scouring corrosion behavior of the bend liquid-solid two-phase flow.
[0009] The technical scheme adopted by the present application to solve the technical problem is: a bend liquid-solid two-phase flow scouring corrosion inhibition device, comprising a spiral pipe, a bend and a downstream straight pipe connected in sequence, the spiral pipe has four arc-shaped inner side walls in its circumferential direction, the four arc-shaped inner side walls are synchronously rotated along the axial direction of the spiral pipe to form a four-leaf spiral pipe; an electrode mounting pipe is mounted on the outer arc wall of the middle part of the bend, an anode mounting pipe is mounted on the inner arc wall of the middle part of the bend, a reference electrode is inserted into the electrode mounting pipe, the test end of the reference electrode protrudes out of the inner wall of the bend and contacts with the fluid medium in the bend, an auxiliary anode is inserted into the anode mounting pipe, and the auxiliary anode extends by abutting the inner wall of the bend; a cathode connection terminal and a zero connection terminal are fixedly connected to the outer wall of the bend, and a signal transmitter is fixedly connected to the wiring end of the reference electrode;
[0010] The device has a cathodic protection power supply, the signal transmitter is connected to the reference wiring end of the cathodic protection power supply through a reference cable, the auxiliary anode is connected to the positive wiring end of the cathodic protection power supply through an anode cable, the cathode connection terminal is connected to the negative wiring end of the cathodic protection power supply through a cathode cable, and the zero connection terminal is connected to the zero wiring end of the cathodic protection power supply through a zero cathode cable.
[0011] A transition straight pipe is connected between the bend and the spiral pipe.
[0012] Preferably, the tangent line of the junction of the electrode installation pipe and the bend is perpendicular to the axis of the electrode installation pipe, and the tangent line of the junction of the anode installation pipe and the bend forms an angle of 135° with the axis of the anode installation pipe.
[0013] Further, the outer end of the electrode installation pipe is fixedly connected with a first flange, the outer end of the anode installation pipe is fixedly connected with a second flange, the reference electrode is threadedly connected with the central hole of the first flange, and the outer end joint of the auxiliary anode is threadedly connected with the central hole of the second flange.
[0014] Preferably, the auxiliary anode is a flexible anode, and the reference electrode is a long-acting probe-shaped Ag / AgCl electrode, and the auxiliary anode is wrapped with a reticular PE hose.
[0015] Further, the cathodic protection power supply is a high-frequency pulse power supply system.
[0016] The present application has the advantages that: the present application makes full use of the advantages of the helical flow generated by the spiral pipe in reducing the scouring effect of solid particles on the wall of the bend and the effective inhibition of electrochemical corrosion by cathodic protection, thereby inhibiting the scouring and corrosion components and their synergistic effect components in the scouring corrosion from the aspects of fluid mechanics and electrochemistry, and thus providing a simple and efficient method and device for preventing and treating the multiphase flow scouring corrosion of the bend in the engineering site. BRIEF DESCRIPTION OF DRAWINGS
[0017] The present application will be further described below in combination with the drawings and examples.
[0018] Figure 1 is a structural schematic view of the device of the present application.
[0019] Figure 2 is a sectional structural schematic view of the spiral pipe of the present application.
[0020] Figure 3 is a three-dimensional structural schematic view of the spiral pipe of the present application.
[0021] Figure 4 is a structural schematic view of the installation of the reference electrode and the auxiliary anode of the present application.
[0022] Figure 5 is a structural schematic view of the auxiliary anode of the present application.
[0023] In the drawings, 1 is a spiral pipe, 2 is a transition straight pipe, 3 is a bend, 4 is a downstream straight pipe, 5 is a cathodic protection power supply, 6 is an auxiliary anode, 7 is a reference electrode, 8 is a signal transmitter, 9 is a cathode connection terminal, 10 is an electrode installation pipe, 11 is an anode installation pipe, 12 is a second flange, 13 is a first flange, 14 is a PE hose, 15 is an anode cable, 16 is a reference cable, 17 is a cathode cable, and 18 is a zero connection terminal. Detailed Implementation
[0024] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.
[0025] like Figures 1-5 The illustrated bend-pipe liquid-solid two-phase flow erosion corrosion suppression device includes a spiral pipe 1, a transition straight pipe 2, a bend 3, a downstream straight pipe 4, and a cathodic protection power supply 5. The transition straight pipe 2 is connected between the upper ends of the spiral pipe 1 and the bend 3 via a flange, and the downstream straight pipe 4 is connected to the lower end of the bend 3 via a flange. Both ends of the device can be connected to a piping system via flanges. The liquid-solid two-phase fluid flows in from the inlet end of the spiral pipe 1, generating a strong spiral flow under the induction of the spiral pipe 1. After passing through the transition straight pipe 2, it enters the bend 3 and finally flows out through the downstream straight pipe 4.
[0026] The inner diameter of the spiral tube 1 is D. The inner contour of the cross-section of the spiral tube 1 is a four-leaf-shaped cross-section formed by four outwardly convex arc segments connected in sequence. The radius of each of the four arc segments is D / 4, and they are all internally tangent to the same circumference with a radius of D / 2. The center of the circumference coincides with the center of the spiral tube 1.
[0027] The helical tube 1 has four arc-shaped inner sidewalls along its circumference. These four arc-shaped inner sidewalls are synchronously rotated along the axial direction of the helical tube 1 to form a four-leaf helical tube 1. Specifically, based on the inner diameter D of the helical tube 1 when it is not twisted, four circles with a radius of D / 4 are inscribed in the same circle with a radius of D / 2 and rotated by an angle of 90°. The four arc-shaped inner sidewalls formed are then synchronously rotated 360° along the axial direction of the helical tube 1 at a distance of 8D, thereby forming a four-leaf helical tube 1.
[0028] An electrode mounting tube 10 is installed on the arc-shaped wall at the top outer side of the middle of the bend 3. The tangent at the junction of the electrode mounting tube 10 and the bend 3 is perpendicular to the axis of the electrode mounting tube 10. An anode mounting tube 11 is installed on the arc-shaped wall at the bottom inner side of the middle of the bend 3. The tangent at the junction of the anode mounting tube 11 and the bend 3 forms a 135° angle with the axis of the anode mounting tube 11. A first flange 13 is fixed to the outer end of the electrode mounting tube 10, and a second flange 12 is fixed to the outer end of the anode mounting tube 11.
[0029] A reference electrode 7 is inserted into the electrode mounting tube 10. The reference electrode 7 is an Ag / AgCl electrode in the shape of a long-lasting probe. The reference electrode 7 is threaded to the center hole of the first flange 13. A signal transmitter 8 is fixedly connected to the wiring end of the outer end of the reference electrode 7. An auxiliary anode 6 is inserted into the anode mounting tube 11. The auxiliary anode 6 is a flexible anode. The outer end connector of the auxiliary anode 6 is threaded to the center hole of the second flange 12.
[0030] The auxiliary anode 6 is wrapped with a reticular PE hose 14, which can prevent the platinized titanium core of the auxiliary anode 6 from contacting the inner wall of the anode installation pipe 11 and the inner wall of the elbow pipe 3 to cause short circuit, and can also prevent the solid particles in the medium transported in the elbow pipe 3 from impacting and damaging the auxiliary anode 6.
[0031] The test end of the installed reference electrode 7 slightly protrudes from the inner wall of the elbow pipe 3 to contact the fluid medium in the elbow pipe 3, and extends in the gap between the auxiliary anode 6 inserted into the elbow pipe 3 and the inner wall of the elbow pipe 3.
[0032] The cathode connection terminal 9 and the zero connection terminal 18 are fixed on the outer wall of the elbow pipe 3 at intervals. The cathodic protection power supply 5 adopts a high-frequency pulse power supply system. The signal transmitter 8 is connected to the reference connection terminal of the cathodic protection power supply 5 through a reference cable 16. The auxiliary anode 6 is connected to the positive connection terminal of the cathodic protection power supply 5 through an anode cable 15. The cathode connection terminal 9 is connected to the negative connection terminal of the cathodic protection power supply 5 through a cathode cable 17. The zero connection terminal 18 is connected to the zero connection terminal of the cathodic protection power supply 5 through a zero connection cable 19.
[0033] The basic principle of the present application is that the spiral flow induced by the spiral pipe 1 upstream of the elbow pipe 3 increases the tangential velocity of the sand particles, generates a ring vortex and a "floating" effect, and the combination of the tangential velocity and the axial velocity improves the carrying capacity of the fluid and makes the sand particles suspended in the fluid, so that the particles are more uniformly distributed in the elbow pipe 3, the impact frequency and focusing effect of the particles on the wall of the elbow pipe 3 are reduced to a certain extent, and the spiral flow suppresses the secondary flow driven collision at the elbow pipe, greatly reducing the erosion of the sand particles on the elbow pipe 3. On the other hand, the forced vortex generated by the spiral flow in the spiral pipe 3 greatly enhances the velocity fluctuation near the pipe wall, disturbs the fluid in the concentration boundary layer, and promotes the mass transfer of oxygen, which to a certain extent increases the electrochemical corrosion rate at the elbow pipe 3, so that the erosion corrosion behavior of different parts of the elbow pipe 3 gradually changes from erosion-electrochemical corrosion control to electrochemical corrosion-erosion control, the influence degree of erosion is weakened, and the influence degree of electrochemical corrosion is increased. Therefore, the present application utilizes the spiral flow induced by the spiral pipe 1 to suppress the erosion and damage of the solid particles on the elbow pipe 3, and utilizes the cathodic protection system arranged at the cathodic protection pipe section of the elbow pipe 3 to make the current flow through the auxiliary anode 6 into the elbow pipe 3, and then reach the inner wall of the pipeline through the fluid medium in the elbow pipe 3, and then flow back to the cathodic protection power supply 5 through the cathode cable 17 connected to the pipe body of the elbow pipe 3, so as to apply cathodic protection to the pipe body of the elbow pipe 3, thereby suppressing the electrochemical corrosion enhanced by the mass transfer effect of the spiral flow.
[0034] In summary, the present application realizes full suppression of the erosion and corrosion behavior and their synergistic effect at the elbow pipe 3 under the condition of liquid-solid two-phase flow by the synergistic use of the spiral flow flow field control technology and the cathodic protection technology.
[0035] The above-described embodiments according to the present application are intended to be illustrative only. Changes can be made by those skilled in the art, without departing from the scope of the present application, which is defined by the following claims. The technical scope of the present application is not limited to the above-described embodiments. The technical scope of the present application must be determined based on the scope of the claims.
Claims
1. A device for inhibiting erosion corrosion in a bent pipe liquid-solid two-phase flow, characterized in that: It includes a spiral pipe, a bend pipe and a downstream straight pipe connected in sequence. The spiral pipe has four arc-shaped inner sidewalls in its circumference. The four arc-shaped inner sidewalls rotate synchronously along the spiral pipe axis to form a four-leaf spiral pipe. An electrode mounting tube is installed on the outer arc wall of the middle section of the bend, and an anode mounting tube is installed on the inner arc wall of the middle section of the bend. A reference electrode is inserted into the electrode mounting tube, and the test end of the reference electrode protrudes from the inner wall of the bend and contacts the fluid medium inside the bend. An auxiliary anode is inserted into the anode mounting tube, and the gap between the auxiliary anode and the inner wall of the bend extends. A cathode connection terminal and a zero-position connection terminal are fixedly connected to the outer wall of the bend, and a signal transmitter is fixedly connected to the wiring end of the reference electrode. It has a cathodic protection power supply. The signal transmitter is connected to the reference terminal of the cathodic protection power supply through a reference cable. The auxiliary anode is connected to the positive terminal of the cathodic protection power supply through an anode cable. The cathode connection terminal is connected to the negative terminal of the cathodic protection power supply through a cathode cable. The zero position connection terminal is connected to the zero position terminal of the cathodic protection power supply through a zero position cathode cable. The spiral flow induced by the spiral tube is used to suppress the scouring and damaging effect of solid particles on the bend. The cathodic protection power supply applies cathodic protection to the bend tube body to suppress the electrochemical corrosion enhanced by the spiral flow-enhanced mass transfer effect.
2. The device for inhibiting erosion corrosion in a bent pipe liquid-solid two-phase flow as described in claim 1, characterized in that: A transition straight pipe connects the bent pipe and the spiral pipe.
3. The device for inhibiting erosion corrosion in a bent pipe liquid-solid two-phase flow as described in claim 1, characterized in that: The tangent at the junction of the electrode mounting tube and the bend is perpendicular to the axis of the electrode mounting tube, and the tangent at the junction of the anode mounting tube and the bend forms a 135° angle with the axis of the anode mounting tube.
4. The device for inhibiting erosion corrosion in a bent pipe liquid-solid two-phase flow as described in claim 3, characterized in that: The outer end of the electrode mounting tube is fixedly connected to a first flange, the outer end of the anode mounting tube is fixedly connected to a second flange, the reference electrode is threadedly connected to the center hole of the first flange, and the outer end connector of the auxiliary anode is threadedly connected to the center hole of the second flange.
5. The device for inhibiting erosion corrosion in a bent pipe liquid-solid two-phase flow as described in claim 1, characterized in that: The auxiliary anode is a flexible anode, the reference electrode is a long-lasting probe-shaped Ag / AgCl electrode, and the auxiliary anode is wrapped with a mesh PE tubing.
6. The device for inhibiting erosion corrosion in a bent pipe liquid-solid two-phase flow as described in claim 1, characterized in that: The cathode protection power supply adopts a high-frequency pulse power supply system.