Rock‐breaking mechanism and efficiency of straight‐swirling mixed nozzle for the nondiagenetic natural gas hydrate in deep‐sea shallow

• Published in: Energy science & engineering Vol. 8; no. 10; pp. 3740 - 3752
• Main Authors: Tang, Yang, Sun, Peng, Wang, Guorong, Fu, Biwei, Yao, Jiaxin
• Format: Journal Article
• Language: English
• Published: London John Wiley & Sons, Inc 01.10.2020; Wiley
• Subjects: Breaking; breaking efficiency; Design; Efficiency; Energy; experimental study; Flow velocity; Fluidizing; Gas hydrates; Natural gas; natural gas hydrate; Nozzles; Parameters; Rocks; rock‐breaking mechanism; straight‐swirling mixed nozzle; Swirling; South China Sea
• ISSN: 2050-0505; 2050-0505
• DOI: 10.1002/ese3.779

Jet breaking using a high‐pressure nozzle is one solution for breaking natural gas hydrate (NGH) formations, creating a larger breaking volume and fluidizing broken solid fragments. Based on the analysis of various jet breaking mechanisms for the variation of the flow velocity of the internal and outlet sections of different nozzles, a straight‐swirling mixed nozzle (SSMN) was designed. We obtained different jet breaking effects for a single nozzle, including the influences of the working pressure and target distance on the hole shape, as well as working pressure on hole parameters and target distance on hole parameters. In addition, we analyzed the influences of the nozzle number, type of NGH rock, and construction parameters on the rock‐breaking efficiency and selected the best combination mode of multiple nozzles. The research results of the rock‐breaking mechanism and efficiency of the SSMN promotes the development of commercial mining technology for nondiagenetic NGH in deep‐sea shallow areas. Based on analysis of various jet crushing mechanisms about variation of flow velocity of internal and outlet section of different nozzles, a straight‐swirling mixed nozzle (SSMN) was designed. We obtained different jet crushing effect of the single SSMN with effect of working pressure on hole shape, influence of working pressure on hole parameters, effect of target distance on hole shape, and influence of target distance on hole parameters. In addition, the influence of different number of nozzles, different NGH rocks, and different construction parameters on rock‐breaking efficiency of combined nozzles was analyzed so that a best combination mode of multiple nozzles was selected.