Natural gas sample collecting method for detecting content of mercury in natural gas

Abstract

The invention provides a natural gas sample collecting method for detecting content of mercury in natural gas. The method comprises the steps of: mounting a sampling device on a to-be-tested natural gas pipeline, wherein the sampling device comprises a three-way pipe fitting for dividing gas flow from the natural gas pipeline into a main path and a bypath, the main path is orderly connected with a first needle valve and a three-way valve in series, two outlets of the tree-way valve are respectively connected with a gas bag for collecting a gas sample and a first flow meter, and the bypath is orderly connected with a second needle valve and a second flow meter in series. During sampling, the second needle valve is regulated so that flow speed in the bypath is 25-35L / min, the three-way valve of the main path is placed to be communicated with the first flow meter for regulating the flow speed in the main path to be 55-65L / min, and then the three-way valve is placed to be communicated with the gas bag so that the natural gas flows into the gas bag so that the sample is collected. By adopting the method provided by the invention, mercury loss in the natural gas sampling process is eliminated to the greatest extent, the collected sample can truly reflect the mercury content in the natural gas inside the pipeline, and the method is simple and convenient for operation, strong in applicability, high in safety and convenient for popularization.

Description

technical field [0001] The invention belongs to the fields of natural gas geochemistry and natural gas ground engineering, and in particular relates to a method for collecting natural gas samples, and the collected samples are used to detect mercury content in natural gas. Background technique [0002] Mercury is a common harmful heavy metal element in natural gas, and the mercury content of different types of natural gas often varies greatly. For gas field production, high-mercury natural gas is not only highly corrosive to production equipment, causing catastrophic accidents such as gas leakage, shutdown or even explosion, but may also cause great harm to operators. Therefore, it is necessary to remove mercury from natural gas with high mercury content, and the detection results of mercury content in natural gas are the most basic data for mercury removal in gas fields. [0003] At present, the method for detecting mercury content in natural gas is mainly for product gas,...

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Problems solved by technology

[0003] At present, the method for detecting mercury content in natural gas is mainly for product gas, which is not only complicated but also not suitable for raw gas containing more water and oil, and the detection of raw gas is more important for mercury removal in gas fields

[0004] The biggest problem in the detection of mercury content in natural gas is the collection of natural gas samples. This is because the mercury in natural gas is easily absorbed or lost by the sampling device and sampling container if the method is not appropriate during the natural gas sample collection process. At the same time, due to the high pressure of natural gas pipelines , sampling at reduced pressure will cause the temperature of natural gas to drop suddenly, which will easily lead to the condensation and precipitation of mercury

After investigation, no relevant technical reports on how to accurately and effectively collect samples for the detection of mercury content in natural gas were found

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