Analysis of weakly cemented gas hydrate bearing sediments particles movement and de-cementation behavior in hydrocyclone separator

Abstract

In the solid fluidization process of natural gas hydrate (NGH) mining, the hydrate reservoir is mainly broken mechanically. Since there is no phase change, many undissolved gas-hydrate-bearing sediment (GHBS) particles are present in the recovered slurry. Some of these GHBS particles tend to discharge from hydrocyclone separator underflow with the sediment during the in-situ separation process, affecting the hydrate recovery efficiency. Therefore, in the separation process, it is necessary to de-cement GHBS particles, promote hydrate decomposition, and improve the collection efficiency. Based on classical hydrocyclone theory, this paper established a prediction model of the weakly cemented GHBS particle rotation behavior in hydrocyclones and the load on the hydrate skeleton. The de-cementation behavior mainly occurred in the cylindrical section. The theoretical model reliability was verified by experiments, and the rotational movement mode of the weakly cemented GHBS particles in the separator was found. Using a CFD-DEM coupling simulation method, de-cementation effect predictions of the hydrocyclone separator under different hydrate skeleton lengths and separator structural parameters were obtained. This research has a certain guiding significance for the design of NGH solid fluidization tools.