Cement erosion process with recyclable sand particle water-jet impacts

Particle water-jet technology is an efficient method that increases the erosion rate of cement material. The full potential of the jet energy, the ability to cover the full cement surface, and avoidance of erosion of the side casing are vital issues that need to be solved. In this study, a full-scale testing apparatus was developed to perform ground tests of the cement erosion process with recycling particle water-jet impact. This device allows for the cement erosion rate to be reliably adjusted and measured. A two-way coupled Eulerian-Lagrangian Computational Fluid Dynamics (CFD) modelling approach was utilized to investigate the impact flow field and erosion characteristics of the particle liquid-solid jet. The operating parameters (particle concentration, particle velocity, particle diameter, and standoff distance) were determined to obtain the optimal erosion rate. Overall, the simulation results are in good agreement with the experimental results. Results demonstrate that the potential core in the free jet zone can maintain a high impact velocity of the particles, while the maximum pressure is distributed in the impact zone. After impact with the cement surface at a very high velocity, the rebound particle velocity considerably decreases. The measured average erosion rate increases when the particle concentration reaches a critical value of 8%, at which the average erosion rate increases to its maximum value. Both the maximum unit erosion rate and average erosion rate increase as the particle diameter increases. To improved erosion of the cement, the optimal standoff distance is 3 cm (about 5 times the nozzle diameter). Also, industrial tests were successfully performed to increase the erosion rate by 50.7% for cement compared to traditional erosion methods.