Effect of the protrusion of the mining chamber on particle recovery performance in solid-state fluidization mining for natural gas hydrate

Abstract

Solid-state fluidized mining is a promising method for the development of natural gas hydrate (NGH), in which hydrate recovery is a key technology. Following the water jet, circular protrusions appeared on the inner wall of the mining chamber, having a substantial effect on the recovery of hydrate particle. In order to improve the particle recovery rate, this paper uses experimental and modeling methods to investigate the effects of protrusion height (h) and protrusion spacing (s) on particle recovery performance. The results show that the resistance of protrusion and gravity results in the formation of three types of recovery flow fields, each of which contains circulating flow, supplementary flow, and recycling flow. The third type of flow field is beneficial for particle recovery. When s is 90 mm or more, the recovery flow field changes from the first type of flow field to the third type of flow field as h increases. The particle recovery rate gradually increases as h increases when s is 90 and 120 mm, and the maximum recovery rates can reach 44.6 % and 46.2 %, respectively. When h is 40 mm or more, the recovery flow field gradually transforms into the third type of flow field as s increases. The particle recovery rate gradually rises and then declines with increasing s, with the turning points occurring at s = 110 mm. The results further enrich the mechanism of hydrate recovery and help optimize the design of recovery tools.