Gas-carrying-liquid flow electrochemical corrosion experiment loop

Abstract

The invention discloses a gas-carrying-liquid flow electrochemical corrosion experiment loop, and relates to the field of multiphase flow corrosion and protection. According to the invention, a gas-carrying liquid flow corrosion condition is considered, a gas-carrying liquid flow electrochemical corrosion experiment loop is established, and the flow corrosion conditions of a wet gas gathering and transportation pipeline, condensed water formation and gas-carrying liquid are reduced. A pressure sensor, a temperature sensor, a temperature controller and a liquid film tester are arranged in the loop, and electrochemical testing is combined, so that experimental data are more accurate, construction of a gas-carrying-liquid flow corrosion mechanism is supported, and safe transportation of the natural gas gathering and transportation pipeline is guaranteed.

Description

Technical Field

[0001] The invention relates to a gas-carrying-liquid flow electrochemical corrosion experimental loop, and relates to the field of multiphase flow corrosion and protection. Background Art

[0002] With the introduction of the "dual carbon" strategy and global energy transformation, shale gas is playing an increasingly important role.

[0003] However, in the production and development of natural gas, especially shale gas production, a gravity separator is installed on the platform, and then the wet gas gathering and transportation process is used to transport the natural gas to the purification plant. The corrosion environment in the gathering and transportation pipeline is complex. Not only corrosive gases but also highly mineralized production water exist. Under the flow of the pipeline, if the terrain where the pipeline is located is undulating, a special gas-liquid two-phase flow, ZNLF (zero net liquid flow) will be formed. Corrosion failure accidents occur from time to time. For example, since 2017, there have been 4 gas production pipeline perforations in the Weiyuan shale gas operation area, 17 punctures and perforations in the platform's ground gathering and transportation process pipeline, and 6 gathering and transportation pipeline perforations in the Changning shale gas field from 2020 to 2021, posing a major hidden danger to production safety.

[0004] Existing corrosion research results cannot reproduce the corrosion environment in natural gas gathering and transportation pipelines. In the loop experiment, both gas and liquid are powered to flow, resulting in differences in the corrosion rate and corrosion mechanism studied and the corrosion in the real gathering and transportation pipeline. In order to restore the flow corrosion environment in the wet natural gas gathering and transportation pipeline and identify the flow corrosion mechanism, a gas-liquid flow electrochemical corrosion experiment loop was designed. Summary of the invention

[0005] The purpose of the present invention is to provide a gas-carrying liquid flow electrochemical corrosion test loop to simulate the wet gas gathering and transportation process in natural gas production. A gas-carrying liquid flow electrochemical corrosion test loop consists of a gas supply system, an electrochemical test system and a loop circulation system.

[0006] The characteristics are as follows: the gas supply system includes a nitrogen generator, N2 / CO2 / O2 high-pressure gas cylinders, and is provided with a regulating valve to control the flow of dry gas. The dry gas flow flows into the pipeline and forms a wet gas flow when it flows out of the solution tank. A liquid film monitor is designed at the bend to ensure the partial pressure and dissolved amount of corrosive gas during the experiment.

[0007] Since the flow of gas-carrying liquid causes backflow and vortex in the pipe bends and uphill pipes, working electrodes for the bends and uphill sections are designed in the test pipe section in the electrochemical test system, which can simultaneously monitor the corrosion of the bends and uphill sections under the flow state.

[0008] The pipeline part in the loop circulation system is made of acrylic transparent tube and has an upward inclination angle. Flow meters, pressure sensors, temperature sensors, temperature controllers and other devices are installed on the pipeline. A liquid film tester is set in the test section to monitor the liquid flow state, and data recording and temperature adjustment of the temperature controller are carried out through the control cabinet. The core equipment of the loop circulation system is a gas circulation pump for gas circulation. The gas is circulated in the loop through negative pressure self-priming at the inlet and positive pressure exhaust at the outlet. The gas circulation pump can adjust the gas flow rate. In the gas-liquid flow electrochemical corrosion experiment loop, the liquid has no power, and the flow energy comes from the shear force of the gas flow.

[0009] The present invention adopts the above technical solution, and can achieve the following beneficial effects:

[0010] In the experiment, the liquid flow does not require additional power, and the flow is carried out under the gas, reproducing the gas-carrying liquid flow environment in the natural gas pipeline.

[0011] The use of a gas circulation pump reduces the use of high-pressure gas cylinders, allowing long-term experiments to be carried out, breaking through the limitations of existing experimental technology.

[0012] A loop with an upward inclination angle was established to restore the location of the section of the natural gas gathering and transportation pipeline most prone to corrosion accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of a gas-carrying-liquid flow electrochemical corrosion experimental loop provided by the present invention.

[0014] In the figure, 1-nitrogen generator, 2-high-pressure nitrogen cylinder, 3-high-pressure oxygen / carbon dioxide mixed gas cylinder, 4-control cabinet, 5-flow meter, 6-pressure sensor, 7-temperature sensor, 8-electric heating belt controller, 9-array electrode test section, 10-liquid film tester, 11-electrochemical workstation, 12-air compressor, 13-gas circulation pump, 14-centrifugal pump, 15-solution tank, 16-temperature controller. DETAILED DESCRIPTION

[0015] The following is combined with Figure 1 The present invention is further described, but the specific implementation forms of the present invention are various and are not limited to the following embodiments.

[0016] The present invention is a gas-carrying liquid flow electrochemical corrosion experimental loop, comprising 1-nitrogen generator, 2-high-pressure nitrogen cylinder, 3-high-pressure oxygen / carbon dioxide mixed gas cylinder, 4-control cabinet, 5-flow meter, 6-pressure sensor, 7-temperature sensor, 8-electric heating belt controller, 9-array electrode test section, 10-liquid film tester, 11-electrochemical workstation, 12-air compressor, 13-gas circulation pump, 14-centrifugal pump, 15-solution tank, 16-temperature controller.

[0017] The specific implementation is:

[0018] In the first step, the electrochemical reference electrode, auxiliary electrode and working electrode are installed in the 9-array electrode test section and connected to the electrochemical workstation.

[0019] In the second step, according to the experimental conditions, the solution was injected into the 9-array electrode test section and the experimental temperature was set.

[0020] The third step is to open 1-nitrogen generator, 2-high-pressure nitrogen cylinder and 3-high-pressure carbon dioxide / oxygen high-pressure cylinder according to the required gas, adjust the flow rate through the regulating valve, and form a wet gas flow when the dry gas flows out through 15-solution tank. After meeting the experimental requirements, open the control valve to allow wet gas to flow into the loop, and the gas flows clockwise, passing through 5-flow meter, 6-pressure sensor, 7-temperature sensor in turn, and exhaust the air. After reaching the specified pressure, turn off 1-nitrogen generator, 2-high-pressure nitrogen cylinder and 3-high-pressure carbon dioxide / oxygen high-pressure cylinder, and start 13-gas circulation pump.

[0021] The fourth step is to conduct relevant corrosion tests through the 11-electrochemical workstation and conduct corrosion mechanism analysis in combination with the 10-liquid film tester.

[0022] Step 5. After the test is completed, turn off 11-electrochemical workstation and 13-gas circulation pump, and take out each electrode.

[0023] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement and improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A gas-carrying liquid flow electrochemical corrosion test loop, characterized in that: It consists of three parts: gas supply system, electrochemical test system and loop circulation system. The main equipment includes 1-nitrogen generator, 2-high-pressure nitrogen cylinder, 3-high-pressure oxygen / carbon dioxide mixed gas cylinder, 4-control cabinet, 5-flow meter, 6-pressure sensor, 7-temperature sensor, 8-sampling port, 9-array electrode test section, 10-liquid film tester, 11-electrochemical workstation, 12-air compressor, 13-gas circulation pump, 14-centrifugal pump, 15-solution tank, 16-temperature controller.

2. The gas-carrying-liquid flow electrochemical corrosion test loop according to claim 1, characterized in that: The gas supply system includes a nitrogen generator, N2 / CO2 / O2 high-pressure gas cylinders, and a regulating valve to control the dry gas flow. The dry gas flows into the pipeline, forms a wet gas flow when it flows out of the solution tank, and then enters the loop to flow clockwise. A liquid film tester is designed at the bend to ensure the corrosive gas partial pressure and dissolved amount during the experiment.

3. The gas-carrying-liquid flow electrochemical corrosion test loop according to claim 1, characterized in that: Since the flow of gas-carrying liquid causes backflow and vortex in the pipe bends and uphill pipes, working electrodes for the bends and uphill sections are designed in the test pipe section in the electrochemical test system, which can simultaneously monitor the corrosion of the bends and uphill sections under the flow state.

4. The gas-carrying-liquid flow electrochemical corrosion test loop according to claim 1, characterized in that: The pipeline part in the loop circulation system is made of acrylic transparent tube and has an upward inclination angle. Flow meters, pressure sensors, temperature controllers and other devices are installed on the pipeline. A liquid film tester is set in the test section to monitor the liquid flow state, and data is recorded and the temperature of the temperature controller is adjusted through the control cabinet. The core equipment of the loop circulation system is a gas circulation pump for gas circulation. The gas is circulated in the loop through negative pressure self-priming at the inlet and positive pressure exhaust at the outlet. The gas circulation pump can adjust the gas flow rate. In the gas-liquid flow electrochemical corrosion experiment loop, the liquid has no power, and the flow energy comes from the shear force of the gas flow.

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