Erosion of plugged tees in exhaust pipes through variously-sized cuttings

- Erosions in the plugged tee are distributed mainly along the buffer wall and the inside and outside joints.
- With an increase in the particle size, the residence time of the particles in the inlet section is prolonged.
- With an increase in particle size, the reentrance distance and number of collision cuttings in the buffer segment increase.
- When the distribution index or characterization factor increase, the maximal erosion area of a plugged tee shifts from the joint to the buffer wall.

A plugged tee is the easily-worn part of an exhaust pipe used in gas drilling. It comprises three segments: the inlet, buffer, and outlet. The contact part of the inlet and outlet segments is called the inside joint, and the contact part of the buffer and outside segments is called the outer joint. Computational fluid dynamics (CFD) was used to simulate the erosion of a plugged tee through identically-sized and variously-sized cuttings. Variously-sized cuttings were described using Rosin-Rammler (R-R) distribution functions, and the maximal erosion rate of the erosion appearing on the buffer and joint was quantified. The motion trajectories and mass concentration distribution of cuttings were specified. The results show that an increase in particle size led to distinct motion trajectories of cuttings and a change in the erosion position of the plugged tee. The high-concentration regions of the plugged tee are distributed mainly at the inside and outside joints and the buffer. The erosion of joints is caused by small cuttings, and the erosion of the buffer segment increases with increased particle size of the cuttings. The location of the maximal erosion shifts from the joints to the buffer wall when the distribution index or characterization factor of the particle size increases. This shift is attributed to the distinct particle trajectories of variously-sized cuttings. The maximal erosion rate was determined, and it was shown that the erosion rate was sensitive to changes in the distribution index.