CN110793888A

CN110793888A - SF6/N2Mixed gas diffusion characteristic experimental method

Info

Publication number: CN110793888A
Application number: CN201911144631.XA
Authority: CN
Inventors: 史会轩; 刘晓波; 王磊
Original assignee: Wuhan NARI Ltd
Current assignee: Wuhan NARI Ltd
Priority date: 2019-11-20
Filing date: 2019-11-20
Publication date: 2020-02-14

Abstract

The invention relates to SF₆/N₂The mixed gas diffusion characteristic experiment method comprises the following steps: s1, mixing gas and pure SF according to different proportions₆And pure N₂Simulating molecular motion under different temperature and pressure; s2, obtaining gas condensation condition and molecular diffusion coefficient information through statistical analysis of molecular motion tracks, and providing qualitative and quantitative information according to the gas condensation condition, the proportion selection of the molecular diffusion coefficient information to the mixed gas and gas supplement maintenance. The invention can simulate the diffusion characteristic of the mixed gas and is beneficial to determining the optimal gas mixing ratio.

Description

SF6/N2Mixed gas diffusion characteristic experimental method

Technical Field

The invention relates to SF₆/N₂Experimental method for diffusion characteristics of mixed gas.

Background

SF₆The gas has excellent insulating properties and arc extinguishing ability, is chemically stable and non-toxic, and thus is widely used as an insulating gas in high voltage power equipment, such as circuit breakers (GCBs), Gas Insulated Switchgear (GIS), transformers (GITs), cables (GICs), etc., and has operating voltages ranging from 35kV to 1200 kV. However, studies have shown that SF₆The gas has strong greenhouse effect, and the greenhouse effect is CO₂23900 times of gas, and because of its chemical stability, its life in the atmosphere can reach 3200 years. Thus SF₆Use and discharge requirements ofCaution should be exercised. SF, on the other hand₆In practice, the SF is generally liquefied at high pressure (3 to 6 atmospheres) (0 ℃ at 1.2MPa and-40 ℃ at working pressure), which makes the SF₆The insulation arc extinguishing function is not well performed in a low temperature region. Furthermore, SF₆The price of the gas is also high.

To solve these problems, SF may be used in addition to other alternative gases₆Mixed gases with some inert gases (e.g. nitrogen, carbon dioxide, etc.) instead of pure SF₆A gas. As an inert gas, nitrogen can be obtained from the atmosphere, the cost is low, and N is₂Has the characteristics of difficult liquefaction, weak greenhouse effect and the like, so that the SF can be adopted in the electrical engineering₆In which N is doped₂SF obtained by the method of (1)₆/N₂Mixed gas of (2) instead of pure SF₆Gases, on the one hand diluting SF₆Reduction of SF₆The use and the discharge of the method can not only effectively solve the problem of greenhouse effect, but also reduce the cost; on the other hand, the whole liquefaction temperature can be changed, and the requirement of the material on the regional temperature and pressure intensity is reduced, thereby solving the problem of SF in severe cold regions₆Problems of liquefaction of the gaseous medium.

For SF₆/N₂The mixed gas still has some problems in practical application, such as the mixing proportion problem: SF at different ratios₆/N₂How the leakage is, how the liquefaction temperature is; what ratio is used can optimize the overall insulation arc extinguishing performance, and the like.

Disclosure of Invention

The invention aims to provide SF₆/N₂The mixed gas diffusion characteristic experiment method can simulate the diffusion characteristic of the mixed gas and is beneficial to determining the optimal gas mixing ratio.

The technical scheme adopted by the invention for solving the technical problems is as follows: construct a SF₆/N₂The mixed gas diffusion characteristic experiment method comprises the following steps:

s1, mixing the gas mixture with different proportions,Pure SF₆And pure N₂Simulating molecular motion under different temperature and pressure;

s2, obtaining gas condensation condition and molecular diffusion coefficient information through statistical analysis of molecular motion tracks, and providing qualitative and quantitative information according to the gas condensation condition, the proportion selection of the molecular diffusion coefficient information to the mixed gas and gas supplement maintenance.

In the method, in step S1, mixed gas and pure SF with different proportions are subjected to classical molecular dynamics calculation₆And pure N₂The molecular motion was simulated at different temperature and pressure.

In the above method, in step S2, the gas condensation is characterized by using a radial distribution function.

In the above method, in step S2, the molecular diffusion coefficient is a physical quantity for characterizing the degree of gas diffusion, and is defined as the amount of gas passing through a unit area per unit time.

SF for carrying out the invention₆/N₂The experimental method for the diffusion characteristic of the mixed gas has the following beneficial effects:

the invention adopts the calculation method of classical molecular dynamics to simulate the molecular motion of mixed gas with different proportions and two pure components under different temperature and pressure, obtains information such as gas condensation condition, molecular diffusion coefficient and the like through statistical analysis of tracks, provides certain qualitative and quantitative information for proportion selection and gas supplement maintenance of the mixed gas according to the information, is favorable for researching the appearance and diffusion problems of the mixed gas with different proportions,

drawings

The invention will be further described with reference to the accompanying drawings and examples, in which:

fig. 1 is a schematic illustration of radial distribution function coordinates.

Detailed Description

For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

The invention provides aSF₆/N₂The mixed gas diffusion characteristic experiment method comprises the following steps:

s1, mixing gas and pure SF according to different proportions₆And pure N₂Simulating molecular motion under different temperature and pressure;

Further, in step S1, the mixed gas and pure SF with different ratios are calculated by using classical molecular dynamics₆And pure N₂The molecular motion was simulated at different temperature and pressure. Molecular Dynamics (MD) is a set of computational methods for simulating molecular motion based on newton's classical mechanics. Generally speaking, the coordinate and velocity state of a molecule at each moment can be obtained by adding an initial random velocity of a donor system to the coordinate information of each molecule by using a Newton's mechanical formula under a certain time step.

Further, in step S2, the gas condensation is characterized by using a radial distribution function. With respect to the agglomeration state, we can use a Radial Distribution Function (RDF) to characterize, as shown in fig. 1 below, the particle density in the range from r to r + dr is counted and calculated by taking a given coordinate as a center, and the Function of the density to r is the Radial Distribution Function. For a crystalline solid, the radial distribution shows that a larger density value appears periodically with the increase of r due to the regular molecular arrangement; for gas, the distance between particles is long, the interaction is small, and the gas is relatively free and disordered, so that when the distance is long enough, the density keeps constant; the molecular arrangement of liquid is between that of solid and gas, and the functional performance is between that of solid and gas.

Further, in step S2, the molecular diffusion coefficient is a physical quantity for characterizing the degree of gas diffusion, and is defined as the amount of gas passing through a unit area per unit time.

While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. SF (sulfur hexafluoride)₆/N₂The mixed gas diffusion characteristic experiment method is characterized by comprising the following steps of:

2. SF according to claim 1₆/N₂The experimental method for diffusion characteristics of mixed gas is characterized in that in step S1, a classical molecular dynamics calculation method is adopted to carry out calculation on mixed gas and pure SF with different proportions₆And pure N₂The molecular motion was simulated at different temperature and pressure.

3. SF according to claim 1₆/N₂The experimental method for diffusion characteristics of mixed gas is characterized in that in step S2, the gas condensation condition is characterized by using a radial distribution function.

4. SF according to claim 1₆/N₂The method for testing diffusion characteristics of a mixed gas, wherein in step S2, the molecular diffusion coefficient is a physical quantity for characterizing the degree of gas diffusion and is defined as the amount of gas passing through a unit area per unit time.