— Hydrocyclone is a simple mechanical device, with no moving par ts, where solid particles are separated from liquid with very little head loss. As its name describes, it uses a cyclone or tangential injection flow process enhancing the centrifugal forces and moving solids outwards. The dispersed particles, move downwar ds in a spiral path into an underflow chamber, while clean liquid move upwards to the center of the spiral, towards the top outlet. In this way, sand and other particles get separated from the water. Due to the various types of sediments in the water the m echanical parts of the turbine are damaged. Mainly s ediments which are hard and also contains sharp edges cause s the most damage to the turbine blade . Such problems due to sediments arise due to varying climate and terrain of Nepal. This problem of erosion of mechanical part due to sediments has become a global maintenance problem of hydropower plants. This is natural phenomena so it can neither be controlled nor completely stopped but it can be managed. So that we used this project as model for protecting turbine blades. The model is designed for the removal of sediments of size around 48microns and larger sizes from sedimental water. The model is designed with combination of 16° cone angles and 0.027, 0.027 and 0.010m inlet, overflow, underflow cylinder diameters respectively . The hydrocyclone is fabricated with 1.6mm thick mild steel sheet. The initial water sand mixture is compared with the resulting underflow and overflow. Keywords —Hydrocyclone Separator, Sediments, cut size I. Introduction Originally in the later part of the 19th century hydrocyclone was used as a solid/liquid separator to remove sand from well water. Later on cyclone shape hydroelectric power plant is also introduced with name Gravitational Wate r Vortex Power Plant [1] [2] [3] [4].A typical hydrocyclone consists of a cylindrical section, a conical section, an underflow cylinder section and a sand collection basket. The separation is based on density difference between the liquid and the matter to be separated. The principle of centrifugal separation is used to remove or classify solid particles from a fluid, based on particle size, shape and density. Due to the various types of sediments in t he water the mechanical parts of the turbine are damaged. Mainly s ediments which are hard and cont ains sharp edges cause the most damage. According to resea rch the most damage is caused in the turbi ne blade by these sediments. Such problems arise due to varying climate and terrain of Nepal. This problem of erosion of mechanical part due to sediments has become a global maintenance problem of hydropower plants. This is natural phenomena so it can neither be controlled nor completely stopped but it can be managed. [5] [6] II. Methodology In hydrocyclone unit must be installed vertically with sedimentation tank under the hydrocyclone. Conical shape accelerates the velocity of the water increasing centrifugal forces and maximizing separation. It’s easy to operate and maintain with no moving parts or screens. There is no head loss build -up or clogging during separation. KEC Conference __________________________________________________________________________________________ 7 KECConference2019, Kantipur Engineering College, Dhapakhel LalitpurThere are various design parameters of hydrocyclone which are as follows: Cone angle: For design purpo se, 16° cone angles were chosen [7] .The larger the hydro cyclone diameter, the coarser the separation. The included angle of the cone section i s normally between 10° and 20°. Cone section length: The length of cone depends upon the underflow cylinder diameter and cone angle. And for this project we made it 0.280m. Fig. 1. Typical Hydrocyclone [6] Inlet and overflow section diameters: The inlet and overflow pipe diameter values were fixed at 0.027 and 0.027m, respectively for a flow rate of 3.6m3/h. To increase the intake capacity of a hydrocyclone, its inlet diameter has to be increased. Cylinder section diameter: In the present stud y, all the six models including the control model had a diameter of 0.198 m (I.D.) which was 3.73 times the overflow pipe diameter. The diameter of cylinder section of the cyclone should be 2 times the overflow pipe diameter. For this project cylinder dia meter is 0.100m. Cylinder section length: Typically, hydrocyclone have a cylinder section length equal to or greater than the hydrocyclone diameter. The length of cylinder section should be 3 times the overflow pipe diameter. In the present study, the cy linder section length was chosen as 2.5 times the overflow p ipe. For this project we made the length 0.070 m. Vortex finder design: Vortex finder takes the clean water and delivers it to the outlet. If the length of vortex finder increases, it is likely to disturb the vortex and result in coarser separation of particles. So, the length of the vortex finder should be optimum and is found by a trial and error method. In this study, the length of the vortex finder was kept at 0.16m. Height of hydrocyclone: The heigh t from the top of the outflow pipe to the end of the underflow cylinder section is referred to as total height of hydrocyclone. And for this project the total height of the hydrocyclone is 0.40m. Cut size: The cut size is defined as the diameter ( ) of a particle, which has a probability of n% to end up in the underflow section. The design probability (n) of trapping of particles in the collection basket was taken as 50%. Particle separation is based on the density difference between the liquid and the m atter to be separated. A higher density difference results in a finer separation. The hydrocyclone was designed by using the mathematical expression given by, d 𝑝𝑝 = √ n×0.01 ×0.5( D−D0) ×18ղ (ƍ𝑠𝑠 − ƍ𝑙𝑙) λa where, 𝑑𝑑𝑝𝑝 = Diameter of removed particle, m n = Probability of trapping of particles, % D= Diameter of cylindrical part, m KEC Conference __________________________________________________________________________________________ 8 KECConference2019, Kantipur Engineering College, Dhapakhel Lalitpur DESIGN, FABRICATION AND TESTING OF HYDROCYCLONE SEPARATOR AS SEDIMENT SEPARATION SYSTEM Bibek Aryal , Prithivi Gurung , Samman Singh Pradhan , Rakish Shrestha Department of Mechanical Engineering School of Engineering, Kathmandu University Kavre, Nepal bbkarl77@gmail.com Aman Kapali Turbine Testing Laboratory Department of Mechanical Engineering School of Engineering, Kathmandu University Kavre, Nepal Rabin Dhakal Department of Mechanical Engineering Texas Tech University Lubbock, Texas Rabin. Dhakal @ttu.edu Abstract— Hydrocyclone is a simple mechanical device, with no moving par ts, where solid particles are separated from liquid with very little head loss. As its name describes, it uses a cyclone or tangential injection flow process enhancing the centrifugal forces and moving solids outwards. The dispersed particles, move downwar ds in a spiral path into an underflow chamber, while clean liquid move upwards to the center of the spiral, towards the top outlet. In this way, sand and other particles get separated from the water. Due to the various types of sediments in the water the m echanical parts of the turbine are damaged. Mainly s ediments which are hard and also contains sharp edges cause s the most damage to the turbine blade . Such problems due to sediments arise due to varying climate and terrain of Nepal. This problem of erosion of mechanical part due to sediments has become a global maintenance problem of hydropower plants. This is natural phenomena so it can neither be controlled nor completely stopped but it can be managed. So that we used this project as model for protecting turbine blades. The model is designed for the removal of sediments of size around 48microns and larger sizes from sedimental water. The model is designed with combination of 16° cone angles and 0.027, 0.027 and 0.010m inlet, overflow, underflow cylinder diameters respectively . The hydrocyclone is fabricated with 1.6mm thick mild steel sheet. The initial water sand mixture is compared with the resulting underflow and overflow. Keywords —Hydrocyclone Separator, Sediments, cut size I. Introduction Originally in the later part of the 19th century hydrocyclone was used as a solid/liquid separator to remove sand from well water. Later on cyclone shape hydroelectric power plant is also introduced with name Gravitational Wate r Vortex Power Plant [1] [2] [3] [4].A typical hydrocyclone consists of a cylindrical section, a conical section, an underflow cylinder section and a sand collection basket. The separation is based on density difference between the liquid and the matter to be separated. The principle of centrifugal separation is used to remove or classify solid particles from a fluid, based on particle size, shape and density. Due to the various types of sediments in t he water the mechanical parts of the turbine are damaged. Mainly s ediments which are hard and cont ains sharp edges cause the most damage. According to resea rch the most damage is caused in the turbi ne blade by these sediments. Such problems arise due to varying climate and terrain of Nepal. This problem of erosion of mechanical part due to sediments has become a global maintenance problem of hydropower plants. This is natural phenomena so it can neither be controlled nor completely stopped but it can be managed. [5] [6] II. Methodology In hydrocyclone unit must be installed vertically with sedimentation tank under the hydrocyclone. Conical shape accelerates the velocity of the water increasing centrifugal forces and maximizing separation. It’s easy to operate and maintain with no moving parts or screens. There is no head loss build -up or clogging during separation. KEC Conference __________________________________________________________________________________________ 7 KECConference2019, Kantipur Engineering College, Dhapakhel LalitpurThere are various design parameters of hydrocyclone which are as follows: Cone angle: For design purpo se, 16° cone angles were chosen [7] .The larger the hydro cyclone diameter, the coarser the separation. The included angle of the cone section i s normally between 10° and 20°. Cone section length: The length of cone depends upon the underflow cylinder diameter and cone angle. And for this project we made it 0.280m. Fig. 1. Typical Hydrocyclone [6] Inlet and overflow section diameters: The inlet and overflow pipe diameter values were fixed at 0.027 and 0.027m, respectively for a flow rate of 3.6m3/h. To increase the intake capacity of a hydrocyclone, its inlet diameter has to be increased. Cylinder section diameter: In the present stud y, all the six models including the control model had a diameter of 0.198 m (I.D.) which was 3.73 times the overflow pipe diameter. The diameter of cylinder section of the cyclone should be 2 times the overflow pipe diameter. For this project cylinder dia meter is 0.100m. Cylinder section length: Typically, hydrocyclone have a cylinder section length equal to or greater than the hydrocyclone diameter. The length of cylinder section should be 3 times the overflow pipe diameter. In the present study, the cy linder section length was chosen as 2.5 times the overflow p ipe. For this project we made the length 0.070 m. Vortex finder design: Vortex finder takes the clean water and delivers it to the outlet. If the length of vortex finder increases, it is likely to disturb the vortex and result in coarser separation of particles. So, the length of the vortex finder should be optimum and is found by a trial and error method. In this study, the length of the vortex finder was kept at 0.16m. Height of hydrocyclone: The heigh t from the top of the outflow pipe to the end of the underflow cylinder section is referred to as total height of hydrocyclone. And for this project the total height of the hydrocyclone is 0.40m. Cut size: The cut size is defined as the diameter ( ) of a particle, which has a probability of n% to end up in the underflow section. The design probability (n) of trapping of particles in the collection basket was taken as 50%. Particle separation is based on the density difference between the liquid and the m atter to be separated. A higher density difference results in a finer separation. The hydrocyclone was designed by using the mathematical expression given by, d 𝑝𝑝 = √ n×0.01 ×0.5( D−D0) ×18ղ (ƍ𝑠𝑠 − ƍ𝑙𝑙) λa where, 𝑑𝑑𝑝𝑝 = Diameter of removed particle, m n = Probability of trapping of particles, % D= Diameter of cylindrical part, m KEC Conference __________________________________________________________________________________________ 8 KECConference2019, Kantipur Engineering College, Dhapakhel Lalitpur 𝐷𝐷0= Diameter of overflow, m ղ= Dynamic viscosity of water, pa -s ƍ𝑆𝑆=Density of solid, kg/m³ ƍ𝑙𝑙= Density of liquid, kg/m³ λ=Residence time, s a= Acceleration, m/s² λ= L Q π(D²−D0² 4) L= Length of cyclone from top inlet to end of cone, m a= U𝑖𝑖² D/2 where, U𝑖𝑖= Initial velocity, m/s U𝑖𝑖= Q A𝑐𝑐 Where, Q= Inlet flow rate, m³/s A𝑐𝑐= π 4×𝐷𝐷0² = Cross -sectional area of inlet pipe, m² [8]. Fabrication and testing of hydrocyclone: The cylinder section and cone section of the hydrocyclone was fabricated by using M.S. (mild steel) sheet of 1.6mm thickness. Commercially available 0.027m diameter mild steel pipe was used to fabricate the inlet and outlet sections of the hydrocyclone. Experimental procedure: Fig. 2. Testing of hydrocyclone The experimental setup for testing the hydrocyclone performance is illustrated in the Fig. 2. The pump of 1.5 L/s discharge rate was taken for the testing of the hydrocyclone. Experimentally, the discharge rate of the pump was found to be 1.35 L/s by putting some specific known volume of water and noting the time at which the pump discharges that specific volume. Then, 100 gm sediment of size less than 250 µm was added to the water of known volume. It was noted that the overflow discharge rate was 1 L/s. The clean water pressure drops in the model of hydrocyclone was recorded. The sample of 200 mL from each of the three outlets was collected and analyzed and the concentration was filtered using filter paper. The dry mass of the sediment was measured to calculate the efficiency of the cylone. These values were then compared with the particle size distribution of the sand sample that was fed into the system. The overall trapping efficiency of the hydrocyclone was calculated by using the following formula given by E=[W𝑢𝑢 W𝑓𝑓 ]× 100% where, E =trapping efficiency of hydrocyclone, dimensionless W𝑢𝑢 = mass fraction in the feed flow, dimensionless W𝑓𝑓 = mass fraction in the underflow, dimensionless [8] III. RESULTS AND DISCUSSION The results obtained from the experiment on design, fabrication and testing of hydrocyclones are discussed in this section. Design of hydrocyclone: It was observed that the cone angle and the underflow cylinder diameter were the main variables for the design of the hydrocyclone. The model was designed to remove particles of size 48microns and more. KEC Conference __________________________________________________________________________________________ 9 KECConference2019, Kantipur Engineering College, Dhapakhel LalitpurHere we take, n= 50% D= 0.10m 𝐷𝐷0= 0.027 m ղ= 8.9 6×10−4 pa.s ƍ𝑠𝑠=1680 kg/m³ ƍ𝑙𝑙=1000 kg/m³ L=0. 40m Q=0.001 m³/s A𝑐𝑐= 𝜋𝜋 4× (0.027 )²= 5.72×10^ -4 m² λ= 𝐿𝐿 𝑄𝑄 π(D²−Do² 4)= 3s U𝑖𝑖= 𝑄𝑄 A𝑐𝑐= 0.74m/s a= U𝑖𝑖² D/2= 60.96 m/s² Now, d𝑝𝑝 = √ n×0.01 ×0.5( D−D0) ×18ղ (ƍ𝑠𝑠 − ƍ𝑙𝑙) λa  d𝑝𝑝=√ 50×0.01 ×0.5× (0.10−0.027 )×18 ×8.96×10−4 (1680 − 1000 )× 3×60.96  d𝑝𝑝=48.57×10−6=48µm Therefore, the diameter of removed particle for our hydro cyclone must be 48µm. Again , for efficiency of hydrocyclone Total mixture =8000gm +100gm =8100 W𝑢𝑢=Mass fraction of underflow  W𝑢𝑢=Mass of underflow Totalmixture=70gm 8100gm W𝑓𝑓= Mass fraction of feed W𝑓𝑓=Mass of feed Total mixture=100gm /8100gm E=[W𝑢𝑢 W𝑓𝑓] × 100% Where ,E=Efficiency  E=[70 100]×100% =70% According to the calculation, it is assumed that the hydrocylone separator should be able to separate particle size of more than 48 microns and it was planned to design the separator accordingly. After t he fabrication, the testing is performed with the separator using t he sand that was available of less than 250 microns and the efficiency is calculated by measuring certain volume of underflow, overflow and the feed rate and nearly 70% efficiency was found which shows that this design and the final result was somewhat sim ilar as less than 50 microns sand were not able to be tested on the separator due to various problems. The graph below shows that separation efficiency increases with particle size which matches our conclusion. Figure 1: Sediment Removal Efficiency comparison between theoretical and designed test apparatus IV. CONCLUSION The hydrocyclone is capable of separating particles upto 48µm critical diameter at flow rate 1 lit/sec with 70% separation efficiency. The efficiency KEC Conference __________________________________________________________________________________________ 10 KECConference2019, Kantipur Engineering College, Dhapakhel Lalitpur 𝐷𝐷0= Diameter of overflow, m ղ= Dynamic viscosity of water, pa -s ƍ𝑆𝑆=Density of solid, kg/m³ ƍ𝑙𝑙= Density of liquid, kg/m³ λ=Residence time, s a= Acceleration, m/s² λ= L Q π(D²−D0² 4) L= Length of cyclone from top inlet to end of cone, m a= U𝑖𝑖² D/2 where, U𝑖𝑖= Initial velocity, m/s U𝑖𝑖= Q A𝑐𝑐 Where, Q= Inlet flow rate, m³/s A𝑐𝑐= π 4×𝐷𝐷0² = Cross -sectional area of inlet pipe, m² [8]. Fabrication and testing of hydrocyclone: The cylinder section and cone section of the hydrocyclone was fabricated by using M.S. (mild steel) sheet of 1.6mm thickness. Commercially available 0.027m diameter mild steel pipe was used to fabricate the inlet and outlet sections of the hydrocyclone. Experimental procedure: Fig. 2. Testing of hydrocyclone The experimental setup for testing the hydrocyclone performance is illustrated in the Fig. 2. The pump of 1.5 L/s discharge rate was taken for the testing of the hydrocyclone. Experimentally, the discharge rate of the pump was found to be 1.35 L/s by putting some specific known volume of water and noting the time at which the pump discharges that specific volume. Then, 100 gm sediment of size less than 250 µm was added to the water of known volume. It was noted that the overflow discharge rate was 1 L/s. The clean water pressure drops in the model of hydrocyclone was recorded. The sample of 200 mL from each of the three outlets was collected and analyzed and the concentration was filtered using filter paper. The dry mass of the sediment was measured to calculate the efficiency of the cylone. These values were then compared with the particle size distribution of the sand sample that was fed into the system. The overall trapping efficiency of the hydrocyclone was calculated by using the following formula given by E=[W𝑢𝑢 W𝑓𝑓 ]× 100% where, E =trapping efficiency of hydrocyclone, dimensionless W𝑢𝑢 = mass fraction in the feed flow, dimensionless W𝑓𝑓 = mass fraction in the underflow, dimensionless [8] III. RESULTS AND DISCUSSION The results obtained from the experiment on design, fabrication and testing of hydrocyclones are discussed in this section. Design of hydrocyclone: It was observed that the cone angle and the underflow cylinder diameter were the main variables for the design of the hydrocyclone. The model was designed to remove particles of size 48microns and more. KEC Conference __________________________________________________________________________________________ 9 KECConference2019, Kantipur Engineering College, Dhapakhel LalitpurHere we take, n= 50% D= 0.10m 𝐷𝐷0= 0.027 m ղ= 8.9 6×10−4 pa.s ƍ𝑠𝑠=1680 kg/m³ ƍ𝑙𝑙=1000 kg/m³ L=0. 40m Q=0.001 m³/s A𝑐𝑐= 𝜋𝜋 4× (0.027 )²= 5.72×10^ -4 m² λ= 𝐿𝐿 𝑄𝑄 π(D²−Do² 4)= 3s U𝑖𝑖= 𝑄𝑄 A𝑐𝑐= 0.74m/s a= U𝑖𝑖² D/2= 60.96 m/s² Now, d𝑝𝑝 = √ n×0.01 ×0.5( D−D0) ×18ղ (ƍ𝑠𝑠 − ƍ𝑙𝑙) λa  d𝑝𝑝=√ 50×0.01 ×0.5× (0.10−0.027 )×18 ×8.96×10−4 (1680 − 1000 )× 3×60.96  d𝑝𝑝=48.57×10−6=48µm Therefore, the diameter of removed particle for our hydro cyclone must be 48µm. Again , for efficiency of hydrocyclone Total mixture =8000gm +100gm =8100 W𝑢𝑢=Mass fraction of underflow  W𝑢𝑢=Mass of underflow Totalmixture=70gm 8100gm W𝑓𝑓= Mass fraction of feed W𝑓𝑓=Mass of feed Total mixture=100gm /8100gm E=[W𝑢𝑢 W𝑓𝑓] × 100% Where ,E=Efficiency  E=[70 100]×100% =70% According to the calculation, it is assumed that the hydrocylone separator should be able to separate particle size of more than 48 microns and it was planned to design the separator accordingly. After t he fabrication, the testing is performed with the separator using t he sand that was available of less than 250 microns and the efficiency is calculated by measuring certain volume of underflow, overflow and the feed rate and nearly 70% efficiency was found which shows that this design and the final result was somewhat sim ilar as less than 50 microns sand were not able to be tested on the separator due to various problems. The graph below shows that separation efficiency increases with particle size which matches our conclusion. Figure 1: Sediment Removal Efficiency comparison between theoretical and designed test apparatus IV. CONCLUSION The hydrocyclone is capable of separating particles upto 48µm critical diameter at flow rate 1 lit/sec with 70% separation efficiency. The efficiency KEC Conference __________________________________________________________________________________________ 10 KECConference2019, Kantipur Engineering College, Dhapakhel Lalitpur is affected by the dimensional errors. Increasing the dimensional accuracy wi ll increase the separation efficiency. This device is aimed to replace the settling tanks in hydropower plants to minimize head loss and increase the separation efficiency . A CKNOWLEDGEMENT This project was possible due to the supervision and information provided to us by our superv isor s Er.Aman Kapali and E r. R abin D hakal . S o we are thankful to them for providing support and we also l ike to acknowledge Turbine Testing lab (TTL) for support. V.