Design and analysis of scroll conveyor and bowl in decanter

In this thesis, research and development studies were carried out for the decanter machine used in the waste water treatment sector. The most important reason for starting the work is vibration and strength problems in decanters which are produced in our country. The vibration problem causes on the machine elements and reduces the life of the machine. In addition, due to the vibration problem, the working speed of the machine sometimes does not come up to the desired values and therefore the quality of the product deteriorates. In the scope of the study, design of scroll screw, bowl parts and design of the scroll screw were done in decanters used in waste water treatment sector. In the decanters, the product taken into the machine rotates at high angular velocities and is separated into solid and liquid phases. The scroll conveyor and drum rotate at different angular velocities to dewater the solid phase and move it out. The vibration levels are high due to the presence of two rotors rotating at high speeds on the machine, due to the asymmetrical structure of the scroll conveyor and the homogeneous dispersion of the product imported. For the design, firstly, the movement of the product in the machine is calculated by using mathematical formulas, the loads coming to the bowl and scroll conveyor are determined. Strength and vibration analyses of decanter were performed by using analysis programs based on the finite element method. The existing design has resulted in a decrease of 51% of the mass of the scroll screw. With this decrease, the natural frequency has increased by 43% compared to the current situation and capacity of machine has increased by 105.5%. The vibration problem has been solved and a lower cost design has been chosen.