(2005) investigated impact of cone tip diameter on cyclone performance by CFD simulation and concluded that the reduction of the diameter increases the efficiency and pressure drop (Gimbun et al., 2005). Many researches have been performed for improving the performance of a cyclone and specifying the flow field behavior (Azadi and Azadi, 2011). He realized that the standard k–ɛ turbulence model is not appropriate to simulate swirling flow inside a cyclone due to excessive turbulence viscosities and insubstantial tangential velocities. ![]() Boysan carried out one of the first CFD simulations (Boyson et al., 1986). Nowadays, the Computational Fluid Dynamics (CFD) method is a promising tool to investigate the flow field behavior and performance of a cyclone. The conventional method for predicting the flow field in a cyclone and its performance is empirical (Wang et al., 2006). ![]() Most of them are based on empirical or semi-empirical equations. For predicting the performance of a cyclone, many mathematical models have been developed such as Lapple theory(1951), Barth theory (1958), Sproull theory(1970), Lieth and Licht theory(1972) (Davis, 2000). A slight change in the dimensions of cyclone can improve its performance. The collection efficiency and pressure drop are two main performance characteristics of the cyclone separators (Azadi and Azadi, 2011). It should be noted that against apparent simplicity of cyclones, their flow and collection characteristics are complex and the cyclone performance is influenced severely by any change in geometrical dimensions and operating conditions (Azadi et al., 2010). The centrifugal force created by rotation of the gas in the cyclone causes the particles suspended in the gas, which are denser than it, move toward the cyclone wall (Hoffmann and Stein, 2008). Simple design, low cost of construction and maintenance, lack of moving parts and high resistance to difficult operating conditions are the main reasons for significant use of cyclones (Davis, 2000). To remove these particles from natural gas, a filter-separator or gas cyclone separator is used (Azadi et al., 2012).Ĭyclone separators have been used for over 100 years and are still one of the most useful devices to remove solid particles from their carrying fluid flow. These particles are one of the important problems in gas transmission pipelines. Suspended solids in natural gas are known as “black powder”. The gas in different places of transmission and distribution lines always containing some solid particles that is created the pressure drop and will cause damage to the equipment transmission lines and the station (corrosion, abrasion and environmental issues). Natural gas is produced from gas reservoirs located below the level of land and sea by a proper system is transferred and distributed between the consumers. The cyclone is able to separate particles with efficiency of more than 96% in summer (the lowest consumption time) and winter (the highest consumption time) well.Ĭurrently, natural gas is considered one of the main sources of energy for many the developed and developing countries and also be used as a raw material in many industries. Simulation validation was done using the Grid Convergence method. Diameter and thickness of the designed cyclone are 55 cm and 1.125 inches respectively. It is attempted to satisfy the standards of American Society of Mechanical Engineers for pressure vessels in cyclone design. The cyclone was designed at pressure and temperature of 1000 psi and 20 ☌ respectively for maximum capacity of CGS #1 of Kerman city. In order to design the cyclone, a number of algorithms were written to calculate the required number of cyclones. ![]() To increase the efficiency and prevent direct escapement of particles entering into the cyclone from the internal vortex finder, the vortex length was optimized using Genetic Algorithm (GA). A high efficiency Stairmand cyclone was selected. Particle trajectories were calculated by discrete phase model. The Reynolds Stress model was used to model the turbulent flow due to existence of swirling flow inside the cyclone. Then, using computational fluid dynamics, simulations were done and their performance evaluated at different conditions. In this study, the required cyclones for separating black powder from natural gas at high pressure for CGS #1 of Kerman city, Iran were designed. Thus, with regarding to the size of black powder, to improve the filtration a cyclone separator before the filtration process was proposed. It was found that the current filtration system not to be efficient to remove the solids. Conducted measurements in the natural gas network of Kerman city, Iran showed a high concentration of black powder in the pipeline. Solid particles suspended in natural gas pipelines cause many fundamental problems in transmission and distribution network of natural gas.
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