Design and numerical simulation of a microwave antenna with coaxial slots for preventing secondary formation of gas hydrate

Abstract

Gas hydrate is a new clean energy resource with polar molecule. However due to the change of temperature and pressure during extraction process, there will be secondary formation of gas hydrate, which usually occurs in reservoirs or pipelines near the wellhead. It is significance to prevent secondary formation of hydrate because of safety issues or production rate reduction caused by it. Theoretically, microwave heating can accelerate the decomposition of gas hydrate. Therefore, it is possible to use microwave radiation to prevent secondary formation of hydrate. In this paper, a microwave antenna with special shaped coaxial-slots was designed. Based on electromagnetics and antenna transmission theories, the key parameters of the coaxial-slot antenna were calculated. The frequency is 2.45 GHz, the impedance is 50 ohms, and ratio of outer to inner conductor radius is 3.32. The slots were designed as ‘H’-shape with the width is 2 mm, the radial length is 12mm, the axial length is 14 mm and the interval is 35 mm. Teflon was used as filling material and the radome. Then the software HFSS and ANSYS were used to analyze the electromagnetic field and temperature field to further optimize the parameters. It will be proved that the microwave antenna can heat gas hydrate and prevent the secondary formation.