Exploration of Detection Technology about Arsenic Content in Natural Gas and Application

Abstract

Although volatile arsenides in natural gas are usually in trace amounts, the service life of a catalyst in natural gas processing can still be shorten by them. Environmental pollution is caused by distribution of As into the atmosphere through gas burning. Health and safety issues happen for workers in close contact with unprocessed gas during exploration and handling. As an important part of natural gas product quality inspection, the technology of arsenic content detection in natural gas needs to break through immediately. We confirmed the feasibility of the two solutions as the adsorption of arsenic through choosing an arsenic adsorbent in natural gas and exploring multi-stage, circulating, and subsequent instrument methods. We selected concentrated nitric acid and silver nitrate solution as the adsorbents and tested the solutions by inductively coupled plasma mass spectrometry (ICP–MS). The results were obtained that the highest absorption efficiency of silver nitrate solution was 98.7%, the average of which was 80.31%, of which concentrated nitric acid could be up to 45%. Detection was also taken in the gas production plant using the methods mentioned above. Moreover, sandstone gas from fields of different provinces was also collected to be detected in the laboratory. We could draw the conclusion from the data that the two absorbents could reach the minimum detection value of the instrument in both gas field and the laboratory. The method of silver nitrate solution was better, and concentrated nitric acid should be used when detecting high H2S gas. Some wells were of higher arsenic content than the safety standard line, in which proper treatment should be taken.