Erosion in the tube entrance region of a shell and tube heat exchanger

Abstract

Purpose -In oil and gas industries, the presence of sand particles in produced oil and natural gas represents a major concern because of the associated erosive wear occurring in various flow passages. Erosion in the tube entrance region of a typical shell and tube heat exchanger is numerically predicted. Design/methodology/approach -The erosion rates are obtained for different flow rates and particle sizes assuming low particle concentration. The erosion prediction is based on using a mathematical model for simulating the fluid velocity field and another model for simulating the motion of solid particles. The fluid velocity (continuous phase) model is based on the solution of the time-averaged governing equations of 3D turbulent flow while the particle-tracking model is based on the solution of the governing equation of each particle motion taking into consideration the viscous and gravity forces as well as the effect of particle rebound behavior. Findings -The results show that the location and number of eroded tubes depend mainly on the particle size and velocity magnitude at the header inlet. The rate of erosion depends exponentially on the velocity. The particle size shows negligible effect on the erosion rate at high velocity values and the large-size particles show less erosion rates compared to the small-size particles at low values of inlet flow velocities. Originality/value -In oil and gas industries, the presence of sand particles in produced oil and natural gas represents a major concern because of the associated erosive wear occurring in various flow passages. The results indicate that erosion in shell and tube heat exchanger can be minimized through the control of velocity inlet to the header.

Numerical identification of critical erosion prone areas in tube heat exchangers

“…the plenum, as shown in Figure 5. The simulation results reported by Habib et al (Habib et al, 2005) also showed that the particle distribution among the tubes and the location of eroded tubes greatly depend on the particle size and velocity, as well as predicted erosion only occurred on the tips of some tubes. They reported that large particles (200μm and 350μm) mainly caused the erosion with the tubes located at the bottom, while the fine particles (10μm) mainly caused the erosion of the peripheral tubes of the upper annular section, especially at the inlet flow velocity of less than 1.024 m/s.…”

“…It was found that high erosion only occurs at scattered small areas. The simulations of erosion in a heat exchanges with 824 tubes (Habib et al, 2005) and in a heat exchanger with 38 tubes (Habib et al, 2006) also showed a location profile of the critical erosion tubes and the serious erosion only occurred on a few tubes. Figure 7 shows that HE1 has the most serious erosion on the tube sheet, and the maximum erosion rate of HE3 is the lowest.…”

“…As can be seen from Figure 4 b, particle separation was predicted in the heat exchanger. Large particles tend to move to the bottom section of the inlet plenum and then enter the bottom two row tubes, while the fine particles move with fluid and go to the top of .47 × 10 −9 mg/g (Habib et al, 2005).…”

“…Some authors (Campos-Amezcua et al, 2007;Njobuenwu & Fairweather, 2012;Parsi et al, 2014;Peng & Cao, 2016;Vieira et al, 2016;Zhang et al, 2007) surveyed the available models and examined their application in the prediction of the solid particle erosion of steam turbine components (Campos-Amezcua et al, 2007), the sand particle erosion of pipelines (Parsi et al, 2014), the solid particle erosion damage of flat specimens in water or air flow and 90°e lbows in air flow (Zhang et al, 2007), four different 90°s quare cross-section bends (Njobuenwu & Fairweather, 2012) and 90°elbows due to gas-solid flow (Peng & Cao, 2016;Pereira et al, 2014;Vieira et al, 2016). The Neilson-Gilchrist erosion equations (Neilson & Gilchrist, 1968) were used by Wallace et al (Wallace et al, 2000) and, thereafter, were used by Habib et al to model erosion in a pipe with abrupt contraction (Badr et al, 2005;Habib et al, 2007;Habib et al, 2004), in the tube entrance region and the tube end of a shell and tube heat exchanger (Habib et al, 2006;Habib et al, 2005), and in the tube entrance region of an air-cooled heat exchanger (Badr et al, 2006). Gao et al (Gao et al, 2016) investigated the characteristics of erosion caused by different size sand particles in a shell and tube heat exchanger.…”

“…Building models for the structure of tube heat exchangers is still an art to precisely simulate the multiphase flow and particle erosion in their critical regions. A symmetrical model was used to study the sand erosion of a shell and tubular heat exchanger at different water velocities and particle sizes, where k-ε turbulence model and the Lagrangian approach were used for fluid flow and tracking particles, respectively (Habib et al, 2005;Habib et al, 2006). However, the simulation of this type of heat exchangers with the Reynoldsaveraged Navier-Stokes (RANS) equations and the k-ω SST (Menter's shear stress transport) turbulence equations showed that the flow in the inlet plenum is asymmetrical (Bremhorst & Brennan, 2011).…”