PSI - Issue 13

M. Amara et al. / Procedia Structural Integrity 13 (2018) 2137–2142 Author name / Structural Integrity Procedia 00 (2018) 000–000

2139

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2. Background and basic equations The study of particles is calculated the mass accumulation rate and erosion attributable to the interaction of particles with model walls. gravity is defined through the components of the gravity acceleration vector in the global coordinate (X,Y and Z) system to calculate the mass accumulation rate: R � � ∑ �� � � � �� � ��� , [kg/(s.m 2 )] (1) R �� � ∑ R � d ����� S , [kg/s] (2) the accumulation rate is calculated by the following formula: �� � � � � ,[mm/year] (3) The equation of mass erosion rate � � � can be written as following � � ∑ � � ��� �� � ���� � ����� ���� �� , [kg/(s.m 2 )] (4) where � � � � � � � is the difference between the speed of the particle and the speed of the wall. The next formula is used to calculate the resulting total of mass erosion rate: �� ∑ � ����� , [kg/s] (5) The erosion rate is calculated by the formula �� � � � � � ,[mm/year] (6) with � � , the mass flow for a trajectory, calculated from the total mass flow of the injection. dS: represents the surface of the cell or cell group. � ; is the particle density. K : is a coefficien. � : is the density of the wall material. The shear stress of the fluid at the wall surface is: τ = (µ+ � � � � � � (7) with µ is the fluid velocity, µ � is turbulent viscosity and � � � � is determined on the internal wall surface. 3. Materials and numerical methods The candidate pipeline selected for the current study is located in Algeria and is still under operation. The characterizations of carbon steel elbow were conducted using chemical composition analysis and mechanical properties including tensile test and hardness measurement. Table 1 shows the standard chemical composition of the elbow steel with the mechanical properties. By using SolidWorks and Ansys softwares, the laminar flow of a fluid as a water with added of sand particles, were analysed with the solid particles of different dimensions, with a pressure of 400000 Pa at a temperature of 80 ° C and 1013625 Pa at mospheric pressure in the inlete and oulet respectively. The geometrical structure is composed of two flanges, a valve, an elbow and a pipe. The simulation analysis was performed on the erosion rate calculation according to the proposal opening valve angle (15°, 30°, 45° and 90°) as shown in Fig. 2 and the sand (particles) injected into the liquid with different sizes of grain (2mm, 0.4 mm and 0.001 mm ). This simulation was performed to the real case on the Ténes desalination plants. A shematical representaion of the differents part was presente in the the Fig. 4.a with an example of a particle trajectory in the elbow pipe in the Fig.4.b.

Table 1. Chemical composition and mechanical properties of elbow pie.

Grade

C % 0.17

Si %

Mn %

P % 0.03

S %

Tensile strength

Yield strength

ST35.8

0.10-0.35

0.40-0.80

0.03

˜ 420 MPa

235 MPa