A device for improving the upward flow pattern of vertical gas-liquid two-phase flow.

Abstract

This invention discloses a device for improving the upward flow pattern of a vertical gas-liquid two-phase flow, relating to the field of chemical process fluid transportation technology. It includes a main vertical pipe, an auxiliary gas pipe, and a flow control unit. One end of the auxiliary gas pipe is connected to a gas source, and the other end is connected to the bottom or near the bottom of the main vertical pipe, and is equipped with an injection port. The flow control unit is used to adjust the auxiliary gas flow rate. The auxiliary gas flow rate accounts for 5% to 50% of the main gas phase volumetric flow rate. The purpose of this invention is to introduce auxiliary gas flow at the bottom of the main vertical pipe, thereby promoting the flow pattern to transform into annular flow or stable bubbly flow, thus effectively preventing liquid blockage.

Description

Technical Field

[0001] This utility model relates to the field of chemical process fluid transportation technology, specifically to a device for improving the upward flow pattern of vertical gas-liquid two-phase flow. Background Technology

[0002] In the fields of chemical engineering, petrochemicals, energy, refrigeration, and liquefied gas transportation, upward flow of gas-liquid two-phase flow in vertical pipelines is common, particularly at evaporator outlets and in liquefied gas pipelines. Due to differences in gas-liquid phase ratios, flow velocities, and physical properties, unstable flow patterns such as slug flow and block flow easily form within the pipe, leading to problems such as pressure fluctuations, liquid reflux, and pipeline vibration. Existing technologies that address this by increasing flow velocity or using separators suffer from drawbacks such as high energy consumption, complex structures, and inflexible adjustment. Utility Model Content

[0003] The purpose of this invention is to provide a device for improving the upward flow pattern of vertical gas-liquid two-phase flow. By introducing auxiliary airflow at the bottom of the main vertical pipe, the flow pattern is transformed into annular flow or stable bubble flow, thereby effectively preventing liquid blockage.

[0004] To solve the above problems, the technical solution provided by this utility model is as follows:

[0005] An apparatus for improving the upward flow pattern of a vertical gas-liquid two-phase flow, comprising:

[0006] Main vertical pipeline, auxiliary gas pipeline, flow control unit;

[0007] One end of the auxiliary gas pipeline is connected to a gas source, and the other end is connected to the bottom or near the bottom of the main vertical pipeline, and is equipped with an injection port;

[0008] The flow control unit is used to regulate the flow rate of the auxiliary gas;

[0009] The auxiliary gas flow rate accounts for 5% to 50% of the main gas phase volumetric flow rate.

[0010] The core architecture of this invention is defined by a main vertical pipe, an auxiliary gas pipe, and a flow control unit. Its function is to physically change the dynamic structure of the gas-liquid two-phase flow inside the pipe by introducing auxiliary airflow at a specific location at the bottom of the pipe at a specific flow rate ratio (5%~50%). This is the basis and prerequisite for achieving flow pattern transformation and preventing liquid blockage.

[0011] Optionally, the auxiliary gas pipeline can be connected to the main vertical pipeline by means of tangential connection, radial connection, or tilt angle of 10° to 45°.

[0012] The access methods for auxiliary ducts (tangential, radial, or inclined at 10°~45°) have been further defined. Their function is to optimize the hydrodynamic effects when the auxiliary airflow enters the main flow, reduce flow resistance and eddy generation, ensure that the auxiliary gas mixes more smoothly and efficiently with the main airflow, and enhance the flow pattern improvement effect.

[0013] Alternatively, the flow control unit may be a mass flow meter, an orifice plate flow meter, or a variable frequency compressor regulating device.

[0014] The specific implementation method of the flow control unit (mass flow meter, orifice plate flow meter, variable frequency compressor) is defined. Its function is to provide a variety of technical means to precisely control the auxiliary airflow, ensuring that the gas flow rate can be stabilized within the preset optimal range under any operating conditions. This is the key to achieving controllable and adjustable flow pattern optimization.

[0015] Alternatively, the auxiliary gas pipeline may be equipped with a porous distributor or a Venturi injector at its end.

[0016] A perforated distributor or Venturi injector is added to the end of the auxiliary gas pipeline. Its function is to solve the problem of gas concentrating in one place and uneven distribution. By dispersing a gas flow into multiple fine streams or using negative pressure to draw in and pulverize the liquid, it greatly improves the uniformity of gas distribution across the pipeline cross-section and the mixing efficiency with the liquid.

[0017] Optionally, the temperature difference between the auxiliary gas and the main gas phase temperature shall not exceed ±20℃.

[0018] The temperature of the auxiliary gas is limited (within ±20℃ of the main gas phase temperature difference). Its function is to prevent thermal shock or unexpected phase change caused by excessive temperature difference (such as the violent vaporization of low-temperature liquid when it encounters hot gas, or the sudden condensation of high-temperature gas when it encounters cold liquid), avoid the generation of new flow instability or equipment safety hazards, and ensure a smooth flow pattern transition process.

[0019] Optionally, the pressure of the auxiliary gas is 0.01 to 0.3 MPa higher than the working pressure at the bottom of the pipeline.

[0020] The pressure of the auxiliary gas is limited (0.01~0.3MPa higher than the pressure at the bottom of the pipeline). Its function is to provide sufficient gas injection power to overcome the internal pressure and hydrostatic pressure of the pipeline, ensuring that the auxiliary gas flow can be smoothly and stably injected into the main flow, preventing the main flow from flowing back into the auxiliary pipeline, which is a basic guarantee for reliable operation.

[0021] Optionally, the liquid phase of the gas-liquid two-phase flow can be liquefied gas, condensate, or chemical reaction liquid.

[0022] The type of liquid medium is specified (liquefied gas, condensate, chemical reaction liquid, etc.). Its function is to clarify the specific application scenarios of this invention's device, demonstrating that its technical solution has a universal improvement effect on low-viscosity, easily vaporized liquid media that are prone to flow blockage.

[0023] Alternatively, the gas phase may be a gas, vapor, or reactive gas.

[0024] The type of gaseous medium is specified (gas, steam, reaction gas). Its function is to demonstrate that the flow pattern improvement method of this invention is applicable regardless of whether the main gas phase is a permanent gas, steam generated by evaporation, or gas generated by a chemical reaction, thus broadening the scope of patent protection.

[0025] Alternatively, the device may be installed at the outlet of a liquefied gas storage tank, the outlet of an evaporator, the outlet of a condenser, or the bottom of a reaction tower.

[0026] The installation locations of the device are specified (LPG storage tank outlet, evaporator outlet, condenser outlet, bottom of reaction tower, etc.). Its function is to directly indicate the specific application locations where this invention can best leverage its advantages and solve the technical problems; these locations are all critical process nodes where vertically rising two-phase flow is prone to blockage.

[0027] Compared with the prior art, the technical solution provided by this utility model has the following advantages:

[0028] I. Simple structure and easy to modify

[0029] It only requires the addition of an auxiliary gas pipeline and a flow control unit at the bottom of the existing vertical pipeline, without the need for large-scale modifications to the original system. It is easy to install and has a low cost.

[0030] II. Can be flexibly adjusted online

[0031] The auxiliary gas flow rate can be adjusted in real time by a flow control unit (such as a mass flow meter or a variable frequency compressor) to adapt to different operating conditions and achieve dynamic flow pattern optimization.

[0032] Third, it has low energy consumption and good economic efficiency.

[0033] The auxiliary gas flow rate accounts for only 5% to 50% of the main gas phase flow rate, and the energy consumption is significantly lower than that of methods such as comprehensively increasing the flow rate or using separators.

[0034] IV. Wide Applicability

[0035] It is suitable for a variety of gas-liquid two-phase systems, including liquefied gases (such as liquid oxygen, liquid nitrogen, LNG), vapor-liquid mixtures, chemical reaction mixtures, etc., and is especially suitable for occasions where liquid stagnation is likely to occur.

[0036] V. Significantly improve operational stability

[0037] By transforming unstable flow patterns (such as slug flow and block flow) into annular flow or stable bubble flow, liquid backflow, pressure fluctuations and pipeline vibration can be effectively reduced, thereby improving conveying efficiency and system safety. Attached Figure Description

[0038] Figure 1 A schematic diagram of the auxiliary gas introduction of a device for improving the upward flow pattern of a vertical gas-liquid two-phase flow, as proposed in an embodiment of this utility model;

[0039] Figure 2 A schematic diagram of a device with an injection nozzle for improving the upward flow pattern of a vertical gas-liquid two-phase flow, as proposed in an embodiment of this utility model;

[0040] Figure 3 A schematic diagram illustrating the flow pattern change of a device for improving the upward flow pattern of a vertical gas-liquid two-phase flow, as proposed in an embodiment of this utility model.

[0041] 1. Main vertical pipe; 2. Auxiliary gas pipe; 3. Injector; 4. Flow control unit; 5. Distributor or injector; 6. Gas inlet; 7. Two-phase flow inlet; 8. Two-phase flow outlet; 9. Mixing section; 10. Diffusion section. Detailed Implementation

[0042] To further understand the content of this utility model, a detailed description of this utility model will be provided in conjunction with the accompanying drawings and embodiments.

[0043] Example

[0044] Combined with appendix Figure 1-3 An apparatus for improving the upward flow pattern of a vertical gas-liquid two-phase flow, comprising:

[0045] Main vertical pipe 1, auxiliary gas pipe 2, flow control unit 4;

[0046] One end of the auxiliary gas pipeline 2 is connected to the gas source, and the other end is connected to the bottom or near the bottom of the main vertical pipeline 1, and is equipped with an injection port 3;

[0047] Flow control unit 4 is used to regulate the auxiliary gas flow rate;

[0048] The auxiliary gas flow rate accounts for 5% to 50% of the main gas phase volumetric flow rate.

[0049] In this embodiment, the structure consists of a vertical pipe (main vertical pipe 1) at the outlet of the liquid nitrogen evaporator, a pipe connecting to the nitrogen source (auxiliary gas pipe 2), and a mass flow meter (flow control unit 4). The operating principle is as follows: During system operation, a gas-liquid two-phase flow enters from the two-phase flow inlet 7 and exits from the two-phase flow outlet 8; nitrogen enters from the gas inlet 6 and is ejected through the auxiliary gas pipe 2 and the injection port 3. The gas-liquid two-phase flow and nitrogen mix through the mixing section 9 and the diffusion section 10. An unstable spherical flow is formed within the main pipe. At this time, the auxiliary gas path is opened, and the mass flow meter controls the injection of nitrogen at a ratio of 20% of the main gas phase flow rate from the bottom. This additional gas disrupts the formation of large gas spherical flows, promoting the fusion of small bubbles or stabilization of the liquid film, thereby transforming the flow pattern into a stable annular flow, ultimately reducing pressure drop and improving delivery efficiency.

[0050] The auxiliary gas pipeline 2 is connected to the main vertical pipeline 1 by means of tangential connection, radial connection or inclination angle of 10° to 45°.

[0051] In an embodiment of the liquid oxygen delivery pipeline, the auxiliary oxygen pipeline can be inserted obliquely into the main vertical pipeline 1 at a 30° angle. The operating principle is as follows: the oblique insertion method imparts a tangential component to the auxiliary airflow, causing it to generate a slight swirling effect upon entry. This not only enhances the mixing of the gas and the falling liquid film but also helps to break up the liquid bridge structure, thereby more effectively eliminating liquid accumulation and reducing pipeline vibration.

[0052] The flow control unit 4 is a mass flow meter, orifice plate flow meter, or variable frequency compressor regulating device.

[0053] In this embodiment, a mass flow meter is used as the control unit. The operating principle is as follows: the mass flow meter monitors and reports the mass flow rate of nitrogen in real time, and transmits this signal to the control system. The control system adjusts the valve opening to precisely maintain the flow rate at a set value (e.g., 20%), thereby ensuring the continuity and stability of the flow pattern transformation effect.

[0054] The auxiliary gas pipeline 2 is equipped with a perforated distributor 5 or a Venturi injector 5 at its end.

[0055] In one possible embodiment, a porous distributor 5 is used at the end. The operating principle is as follows: the auxiliary airflow is forced through numerous tiny holes on the distributor, where it is "crushed" into a large number of tiny bubble clusters before entering the mainstream. These small bubbles, acting as additional nucleation points, are evenly distributed in the liquid, effectively preventing the merging and formation of atmospheric bubbles, and directly contributing to the formation of a stable bubbly flow.

[0056] The temperature difference between the auxiliary gas and the main gas phase should not exceed ±20℃.

[0057] In a liquid nitrogen system, the auxiliary nitrogen gas passes through a heat exchanger before injection to bring its temperature close to that of the main gas flow (evaporating gas). The operating principle is that the injection of auxiliary gas at a similar temperature will not cause violent evaporation of liquid nitrogen or condensation of gas in the main pipeline. The phase change process remains stable, and the improvement in flow pattern is purely driven by fluid dynamics mechanisms, making the effect controllable and predictable.

[0058] The pressure of the auxiliary gas is 0.01 to 0.3 MPa higher than the working pressure at the bottom of the pipeline.

[0059] In this embodiment, the nitrogen source outlet pressure is set by a pressure regulating valve to be 0.1 MPa higher than the pressure detected at the bottom of the pipeline. The operating principle is that this positive pressure difference provides a stable driving force for gas injection, allowing the gas to be continuously injected at a preset flow rate. Regardless of fluctuations in the mainstream pressure, the introduction effect can be guaranteed, and the stable operation of the system can be maintained.

[0060] In a gas-liquid two-phase flow, the liquid phase can be liquefied gas, condensate, or chemical reaction liquid.

[0061] This device is used for transporting liquefied gases such as liquid nitrogen and liquid oxygen. The operating principle is that these media, due to frequent gas-liquid phase transitions, easily form unfavorable flow patterns. This invention intervenes in the flow pattern through bottom gas injection; its principle is applicable to all flowable liquids with similar flow characteristics, rather than being limited to a specific liquid.

[0062] The gas phase can be gas, vapor, or reactive gas.

[0063] This device can be applied to the bottom of a reaction tower, where the gas phase consists of gases produced by chemical reactions (such as ethylene gas produced by polymerization). The operating principle is as follows: the auxiliary gas introduced at the bottom (which can be inert nitrogen) is compatible with the reaction gas. Through the same fluid dynamics mechanism (changing the gas holdup distribution and disrupting the atmospheric blister), the flow pattern is improved, ensuring that the reaction products are smoothly transported upwards and avoiding blockage inside the tower.

[0064] The device is installed at the outlet of the liquefied gas storage tank, the outlet of the evaporator, the outlet of the condenser, or the bottom of the reaction tower.

[0065] The device is installed on the outlet pipe of the liquid nitrogen evaporator. Its operating principle is as follows: the gas-liquid two-phase flow at the evaporator outlet is typically in a highly unstable slug-like flow state, making it a high-risk area for blockage. Installing and injecting auxiliary gas at this location can intervene in the flow pattern formation at its source, directly preventing the development of unfavorable flow patterns in the most critical section and ensuring the smooth flow of the entire downstream pipeline.

[0066] This embodiment also introduces a method for improving the upward flow pattern of a vertical gas-liquid two-phase flow. Using this device, an auxiliary gas flow is introduced at the bottom of the vertical pipe, causing the flow pattern to shift towards annular flow or stable bubbly flow. In this embodiment, the method is configured as follows: the operator starts the system and sets the mass flow meter parameter to 20%. The operating principle is consistent with the device claims, namely, by controlling the gas injection action, the flow pattern within the pipe is changed using fluid dynamics principles.

[0067] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the inventive spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A device for improving the upward flow pattern of a vertical gas-liquid two-phase flow, characterized in that, include: Main vertical pipeline, auxiliary gas pipeline, flow control unit; One end of the auxiliary gas pipeline is connected to a gas source, and the other end is connected to the bottom or near the bottom of the main vertical pipeline, and is equipped with an injection port; The flow control unit is used to regulate the flow rate of the auxiliary gas; The auxiliary gas flow rate accounts for 5% to 50% of the main gas phase volumetric flow rate.

2. The device for improving the upward flow pattern of vertical gas-liquid two-phase flow according to claim 1, characterized in that, The auxiliary gas pipeline is connected to the main vertical pipeline by means of tangential connection, radial connection or tilt angle of 10° to 45°.

3. The apparatus for improving the upward flow pattern of vertical gas-liquid two-phase flow according to claim 1 or 2, characterized in that, The flow control unit is a mass flow meter, an orifice plate flow meter, or a variable frequency compressor regulating device.

4. The device for improving the upward flow pattern of vertical gas-liquid two-phase flow according to claim 1, characterized in that, The auxiliary gas pipeline is equipped with a perforated distributor or a Venturi injector at its end.

5. The apparatus for improving the upward flow pattern of vertical gas-liquid two-phase flow according to claim 1, characterized in that, The temperature difference between the auxiliary gas and the main gas phase temperature shall not exceed ±20℃.

6. The apparatus for improving the upward flow pattern of a vertical gas-liquid two-phase flow according to claim 1, characterized in that, The pressure of the auxiliary gas is 0.01 to 0.3 MPa higher than the working pressure at the bottom of the pipeline.

7. The apparatus for improving the upward flow pattern of vertical gas-liquid two-phase flow according to claim 1, characterized in that, The liquid phase of the gas-liquid two-phase flow is liquefied gas, condensate, or chemical reaction liquid.

8. The apparatus for improving the upward flow pattern of vertical gas-liquid two-phase flow according to claim 1, characterized in that, The gas phase is a gas, vapor, or reactive gas.

9. The apparatus for improving the upward flow pattern of vertical gas-liquid two-phase flow according to claim 1, characterized in that, The device is installed at the outlet of a liquefied gas storage tank, the outlet of an evaporator, the outlet of a condenser, or the bottom of a reaction tower.

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