A safe working condition design method of offshore gas-liquid separator

Abstract

The application provides a safe working condition design method of a marine gas-liquid separator, comprising the following steps: determining different rolling working conditions related to the gas-liquid separator; establishing a geometric model of the gas-liquid separator, establishing a corresponding calculation domain, and determining a complex flow region; finely simulating the liquid tank flow field of the gas-liquid separator under the rolling state according to the geometric model of the gas-liquid separator, and monitoring the water level change of each point to obtain the lowest safe water level position; obtaining the corresponding relationship between different rolling working conditions and the lowest safe water level according to the lowest safe water level position, and designing the safe water level working condition under different rolling conditions according to the corresponding relationship; the beneficial effects of the application are that: the application can accurately calculate the lowest safe water level, thereby predicting the safe water level working condition, providing a method and modeling technical support for the rolling safety work and working condition design of the gas-liquid separation device of the marine hydrogen production system, and having important guiding significance for the efficient development of new energy hydrogen production.

Description

Technical Field

[0001] This invention relates to the field of operational safety technology for offshore gas-liquid separators, and in particular to a method for designing safe operating conditions for offshore gas-liquid separators. Background Technology

[0002] As global climate change leads to increasingly significant and frequent climate anomalies, there is an urgent need to develop more clean energy sources to replace traditional fossil fuels. Hydrogen, as an important clean energy source, boasts advantages such as versatility, cleanliness, and flexibility, with an energy density three times that of traditional petroleum. In the global effort to accelerate the clean energy and low-carbon transition and actively address climate change, offshore hydrogen production using renewable energy has become a focal point in the new energy field, considered a crucial solution for addressing issues related to power transmission, peak shaving, and energy consumption.

[0003] Hydrogen production equipment at sea is typically installed on floating platforms, which experience sloshing motion. This sloshing motion causes the liquid in the gas-liquid separator mounted on the deck to slosh as well. Different sloshing periods and amplitudes correspond to different water level changes. Increased sloshing amplitude increases the contact area between the free surface water level and the tank wall, thus decreasing the minimum safe water level. The sloshing period also affects the minimum safe water level. Currently, there is a lack of methods for assessing the minimum safe water level of gas-liquid separators under sloshing conditions, which seriously impacts operational safety in engineering. This invention provides a predictive method for assessing the minimum safe water level of gas-liquid separators under sloshing conditions. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a safe operating condition design method for offshore gas-liquid separators, which solves the problem of the lack of an assessment method for the minimum safe water level of gas-liquid separators under sloshing conditions, which seriously affects the safety of operation in engineering.

[0005] To achieve the above and other related objectives, the present invention provides the following technical solution:

[0006] A method for designing safe operating conditions for a marine gas-liquid separator includes the following steps: determining different sloshing conditions for the gas-liquid separator; establishing a geometric model of the gas-liquid separator, establishing a corresponding computational domain for the geometric model, and determining complex flow regions; performing a detailed simulation of the liquid tank flow field of the gas-liquid separator under rolling conditions based on the geometric model, and monitoring water level changes at various points to obtain the minimum safe water level position; obtaining the correspondence between different sloshing conditions and the minimum safe water level based on the minimum safe water level position, and designing safe water level operating conditions under different sloshing conditions based on the correspondence.

[0007] In one embodiment of the present invention, the swaying conditions include swaying period and swaying amplitude, and the swaying amplitude and swaying period can be freely combined in an alternating manner.

[0008] In one embodiment of the present invention, the geometric model of the gas-liquid separator is a cylindrical structure, and the shape of the complex flow region is a cylinder.

[0009] In one embodiment of the present invention, after establishing the geometric model of the gas-liquid separator, establishing a corresponding computational domain for the geometric model of the gas-liquid separator, and determining the complex flow region, before performing a detailed simulation of the liquid tank flow field of the gas-liquid separator under the rolling state based on the geometric model of the gas-liquid separator, and monitoring the water level changes at each point to obtain the lowest safe water level position, the method further includes: dividing the computational domain using an unstructured volume mesh, refining the mesh using a surface reconstruction model, and performing mesh densification processing on the complex flow region to obtain a complex flow densified region.

[0010] In one embodiment of the present invention, the step of performing a detailed simulation of the liquid tank flow field of the gas-liquid separator under the rolling state based on the geometric model of the gas-liquid separator, and monitoring the water level changes at each point to obtain the minimum safe water level position, includes: using the closed control equation of the turbulence model, the free surface tracking method and the finite volume method to discretize the fluid control equation, and performing a detailed simulation of the liquid tank flow field of the gas-liquid separator under the rolling state based on the CFD method, and monitoring the water level changes at each point to obtain the minimum safe water level position.

[0011] In one embodiment of the present invention, the turbulence model may be a K-Epsilon two-layer model, a standard K-Epsilon two-layer model, an SST K-Omega model, or a standard K-Omega model, etc.

[0012] In one embodiment of the present invention, given that liquid tank sloshing involves complex nonlinear phenomena such as gas-liquid mixing, the Euler multiphase flow model, VOF model, and other models are also used in the detailed simulation of the liquid tank flow field of the gas-liquid separator under swaying conditions.

[0013] In one embodiment of the present invention, the step of using the finite volume method to discretely simulate the liquid tank flow field of the gas-liquid separator under rolling conditions and monitoring the water level changes at each point to obtain the minimum safe water level position includes: using the finite volume method to discretely simulate the fluid control equations, using the central difference scheme to process the linear diffusion term, using the second-order upwind scheme to process the nonlinear convection term, and using the SIMPLE algorithm to solve the problem, thereby performing a detailed simulation of the liquid tank flow field of the gas-liquid separator under rolling conditions and monitoring the water level changes at each point to obtain the minimum safe water level position.

[0014] As described above, the safety operating condition design method for a marine gas-liquid separator of the present invention has the following beneficial effects:

[0015] This invention first sets up different sloshing operating conditions for gas-liquid separators, then establishes a geometric model of the gas-liquid separator, and sets up a corresponding computational domain and complex flow region. It then uses a turbulence model with closed control equations, a free surface tracking method, a finite volume method with discrete fluid control equations, and a multiphase flow model to simulate the gas-liquid two-phase flow. This allows for a detailed simulation of the liquid tank flow field of the gas-liquid separator under sloshing conditions, monitoring changes in the minimum water level to design safe water level conditions under different sloshing conditions. Compared with existing technologies, this invention can accurately calculate the minimum safe water level, thereby predicting safe water level conditions. It provides methodological and modeling technical support for the safe operation and condition design of gas-liquid separation devices in marine hydrogen production systems, and has important guiding significance for the efficient development of new energy hydrogen production. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the overall safety operating condition design method for a marine gas-liquid separator disclosed in an embodiment of the present invention.

[0017] Figure 2 This diagram illustrates how different sway amplitudes affect the minimum safe water level in the safety operating condition design method for a marine gas-liquid separator disclosed in this embodiment of the invention. Detailed Implementation

[0018] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. It should be noted that, unless otherwise specified, the following embodiments and features described herein can be combined with each other.

[0019] This invention relates to a safety design method for offshore gas-liquid separators. Addressing the impact of various sloshing conditions on the minimum safe waterline, it specifically provides a safety design method for gas-liquid separators operating at sea under sloshing conditions. This method enables reasonable and safe assessment of the minimum safe waterline position during offshore operations, thereby avoiding potential safety hazards. The process is as follows: Figure 1 As shown, the details are as follows:

[0020] Step 101: Determine the sloshing conditions for different gas-liquid separators.

[0021] Specifically, different oscillation conditions for the gas-liquid separator are artificially set and made into an operating condition table, as shown in Table 1. The oscillation conditions include the oscillation period and the oscillation amplitude, and the oscillation amplitude and the oscillation period can be freely combined.

[0022] Table 1: Operating Conditions for Gas-Liquid Separation

[0023] Operating conditions Oscillation cycle Sway amplitude Case 1-Case 3 T1 A1, A2, A3 Case 4-Case 6 T2 A1, A2, A3 Case 7-Case 9 T3 A1, A2, A3 …. …. ….

[0024] Step 102: Establish the geometric model of the gas-liquid separator, establish the corresponding computational domain for the geometric model of the gas-liquid separator, and determine the complex flow region.

[0025] Specifically, a complex flow region is artificially created, in which the geometric model of the gas-liquid separator is a cylindrical structure, and the shape of the complex flow region is a cylinder.

[0026] Step 103: Use an unstructured volume mesh to divide the computational domain, then use a surface reconstruction model to refine the mesh, and perform mesh refinement processing on the complex flow region to obtain the complex flow refinement region.

[0027] Specifically, the unstructured mesh uses a cut volume mesh.

[0028] In practical applications, CFD multiphase modeling methods, coupled with six-degree-of-freedom equations of motion and Navier-Stokes equations, are used to perform time-domain simulations to solve the liquid tank sloshing problem of a gas-liquid separator. The physical model is set up, using the Navier-Stokes equations (NS equations) as the governing equations. In Cartesian coordinates, its form is as follows: Among them, u i u j The velocity components are in three dimensions (i,j = 1, 2, 3); x i x j The coordinate components are represented in three dimensions (i,j = 1, 2, 3); t is time; ρ is fluid density; p is pressure; v is kinematic viscosity; f i This represents the volume force component.

[0029] Step 104: Based on the geometric model of the gas-liquid separator, perform a detailed simulation of the liquid tank flow field of the gas-liquid separator under the rolling state, and monitor the water level changes at each point to determine the lowest safe water level position.

[0030] Specifically, a two-phase gas flow and free liquid surface capture model were used, and a liquid tank sloshing model of the gas-liquid separator was established based on CFD methods. The dynamic changes of the liquid tank under sloshing conditions were simulated, and the water level history at different locations was monitored. After comparison, the lowest safe water level position was determined. For details, please refer to [link / reference needed]. Figure 2 .

[0031] More specifically, the fluid control equations are discretized using a turbulence model with closed control equations, a free surface tracking method, and a finite volume method. Based on CFD methods, a detailed simulation of the liquid tank flow field of a gas-liquid separator under swaying conditions is performed. Water level changes at various points are monitored to determine the minimum safe water level. Specifically, the swaying process of the gas-liquid separator is numerically simulated using CFD methods, and the minimum water level h is determined by monitoring water level changes at different points. i =min(H i ).

[0032] Furthermore, turbulence models can employ K-Epsilon two-layer models, standard K-Epsilon two-layer models, SSTK-Omega models, or standard K-Omega models, etc.; given that liquid tank sloshing involves complex nonlinear phenomena such as gas-liquid mixing, Euler multiphase flow models, VOF models, etc., are also used; in addition, the finite volume method is used to discretize the fluid control equations, the central difference scheme is used to handle the linear diffusion term, the second-order upwind scheme is used to handle the nonlinear convection term, and the SIMPLE algorithm is used to solve the problem, so as to perform a detailed simulation of the liquid tank flow field of the gas-liquid separator under swaying conditions.

[0033] Step 105: Obtain the correspondence between different swaying conditions and the minimum safe water level based on the minimum safe water level location, and design safe water level conditions under different swaying conditions based on the correspondence.

[0034] For details, please refer to Table 2;

[0035] Table 2: Minimum Safe Water Level for Each Operating Condition

[0036] Operating conditions Minimum safe water level Case 1 h1 Case 2 h2 Case 3 h3 Case 4 h4 Case 5 h5 Case 6 h6 Case 7 h7 Case 8 h8 Case 9 h9

[0037] In summary, this invention first sets different sloshing conditions for the gas-liquid separator; then, it establishes a geometric model of the gas-liquid separator and uses an unstructured volumetric mesh to divide the computational domain; next, it uses a two-phase gas flow and free liquid surface capture model, and establishes a liquid tank sloshing model of the gas-liquid separator based on the CFD method, simulating the dynamic changes of the liquid tank under sloshing conditions, monitoring the water level history at different locations, and determining the lowest water level position by comparison; finally, based on the lowest safe position, it summarizes the correspondence between different sloshing conditions and the lowest position, and designs safe water level conditions under different sloshing conditions based on this correspondence; therefore, the method of this invention can accurately assess the lowest safe liquid level change caused by sloshing, ensure the normal operation of the gas-liquid separator, and improve the stability and safety of the system.

[0038] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. All equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this invention should still be covered by the claims of this invention.

Claims

1. A safety operating condition design method for an offshore gas-liquid separator, characterized in that, Includes the following steps: Determine the oscillation conditions for different gas-liquid separators; A geometric model of a gas-liquid separator is established, a corresponding computational domain is established for the geometric model of the gas-liquid separator, and a complex flow region is determined. The geometric model of the gas-liquid separator is a cylindrical structure, and the shape of the complex flow region is a cylinder. The computational domain is divided using an unstructured volume mesh, the mesh is then refined using a surface reconstruction model, and the complex flow region is subjected to mesh refinement processing to obtain a complex flow refinement region. The flow field of the liquid tank of the gas-liquid separator under the rolling state was simulated based on the geometric model of the gas-liquid separator, and the water level change at each point was monitored to obtain the lowest safe water level position. Based on the minimum safe water level position, the correspondence between different sloshing conditions and the minimum safe water level is obtained, and the safe water level conditions under different sloshing conditions are designed based on the correspondence. The step of simulating the liquid tank flow field of the gas-liquid separator under rolling conditions based on the geometric model of the gas-liquid separator, and monitoring the water level changes at various points to determine the minimum safe water level position, includes: The fluid control equations were discretized using the turbulence model closed control equations, the free surface tracking method, and the finite volume method. The flow field of the liquid tank of the gas-liquid separator under the rolling state was simulated based on the CFD method, and the water level changes at each point were monitored to obtain the lowest safe water level position. The flow field in the liquid tank of a gas-liquid separator under rolling conditions was simulated using the discrete fluid control equations of the finite volume method, and the minimum safe water level was determined by monitoring water level changes at various points, including: The fluid control equations were discretized using the finite volume method. The linear diffusion term was handled by the central difference scheme, the nonlinear convection term was handled by the second-order upwind scheme, and the SIMPLE algorithm was used to solve the problem. The flow field of the liquid tank of the gas-liquid separator under the rolling state was simulated, and the water level changes at each point were monitored to obtain the lowest safe water level position.

2. The safety operating condition design method for a marine gas-liquid separator according to claim 1, characterized in that: The swaying conditions include swaying period and swaying amplitude, and the swaying amplitude and swaying period can be freely combined.

3. The safety operating condition design method for a marine gas-liquid separator according to claim 1, characterized in that: The turbulence model used is either the K-Epsilon two-layer model, the standard K-Epsilon two-layer model, the SST K-Omega model, or the standard K-Omega model.

4. The safety operating condition design method for a marine gas-liquid separator according to claim 3, characterized in that: Given that liquid tank sloshing involves complex nonlinear phenomena of gas-liquid mixing, the Euler multiphase flow model or VOF model is used in the simulation of the liquid tank flow field of the gas-liquid separator under swaying conditions.

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