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    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 6, November - December (2013) © IAEME AND TECHNOLOGY (IJMET) ISSN 0976 – 6340 (Print) ISSN 0976 – 6359 (Online) Volume 4, Issue 6, November - December (2013), pp. 186-200 © IAEME: www.iaeme.com/ijmet.asp Journal Impact Factor (2013): 5.7731 (Calculated by GISI) www.jifactor.com IJMET ©IAEME PRESSURE BALANCING OF DUCT FOR DUCT EXTRACTION SYSTEM Anil Kumar Mishra*, Anup Kumar** *Engineer, TRF Limited, Jamshedpur (India) **Dept. of Mechanical Engineering, National Institute of Technology, Durgapur, India ABSTRACT The paper includes dust emissions at different transfer point operations in iron ore crushing plant that is critically examined and a design of a dust extraction system is presented for proposed layout. The traditional methodology for design is relies on empirical relations, charts, multivariable tables and monographs. A rational technique of design is employed for understanding of actual mechanism of problem which is predicated on fundamentals of fluid and particle mechanics. In this paper exhaust flow rate for hoods are critically examined for optimized results from theory of air induction that is fairly well developed. Based on exhaust volume duct and its fittings are designed and recommended. A parametric study is performed on flow pattern in duct network and balanced flow is achieved by comparing two different methods of obtaining balanced flow. Keywords: Rational Design, Exhaust Volume, Mine Dust, Dust Extraction System. 1.0 INTRODUCTION One consequence of high degree of mechanization of recent mining techniques is production of huge quantity of mine dust throughout the process of bringing ores from seam to surface. This dust consists of tiny solid particles carried by air current and non- specific with respect to size, shape, and chemical composition of the particles. In ore handling plant dust is ubiquitous and may be found at fan, stack, conveyors and crushers. In mining dust is emitted due to (Moody. Jakhete.R, 1989)i. Breaking of ore by impact, crushing, blasting and grinding. ii. Release of previously generated dust during handling operations such as dumping, loading transferring. iii. Recirculation of previously generated dust by wind or by movement of workers and machinery. 186
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 6, November - December (2013) © IAEME Depending on factors like climate, geology, technique of mining and kind of ore the potential exists for greatly increased dust levels in the environment of mine. Mine dust is not only detrimental to flora and fauna but it is also harmful to buildings, structures, dams and monuments (Hilson. G). This dust is additionally responsible for amendment in land form and loss of bulk solids. Dust control is the science of reducing harmful dust emissions by applying sound engineering principle. Properly deigned, maintained and operated dust control systems can reduce dust emissions effectively [9].For an effective dust control the necessary preventive measures has to be adopted in every process of dust generation. The controlling method of dust extraction system involves dry collection, wet dust suppression system, combination system and electrostatic precipitators (Moody. Jakhete.R, 1989). Dry collection involves hooding or enclosing dust producing points and exhausting emissions to a collection device. The dry collection is used at several points and crusher discharge i.e. screening and transfer operations. In dry significant fugitive dust emissions result during formation of new aggregate piles and erosion from previously stock piles are controlled by wet dust suppression and devices designed to minimize the free fall distance to which the material is subjected thus lessening its exposure to wind. In wet suppression system, basic components are dust control agent, proportioning equipment and a distribution system and control actuators. Distribution is accomplished by spray nozzles. In combination control systems, the wet suppression is used to control primary crushing stage and subsequent screens, transfer points and crusher feed. Control devices for these emissions include telescopic chutes, stone ladders and hinged stacker conveyors. Locating stock piles behind natural or artificial wind breaks also aids in reducing wind-blown dust (Countess, R. J, Cowherd, C). The most common type of dust collector used in mining industry is cyclone dust collector as it is more efficient than the other air cleaners as it is simple in operation and relatively inexpensive in construction [9]. In this work, a rational method of design is proposed by incorporating the important aspects of traditional design and implementing the concepts of mechanics [9]. The initial design of dust extraction system for iron ore crushing plant is critically examined and a new design is proposed for better performance and reliability. 2.0 DUST EXTRACTION SYSTEM Dust extraction systems are used to collect dust emissions at various transfer point. The extraction system for dust is essentially a ducted system that prevents excessive employee exposure to the dust in the working zone. It comprise of four mechanisms: - i. Capture of contaminant by hood at transfer points ii. Transport of contaminated air through the duct network iii. Separation of dust in dust collector i.e. cyclone iv. Exhaust of clean air through stack. 187
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 6, November - December (2013) © IAEME Fig. 1 Dust Extraction System The four major components of a dust extraction system:i. Hoods ii. Ductwork iii. Air cleaner iv. Fan i) Hoods: - The hood is the point where air with captured contaminants enters the system. Its purpose is to direct the air flow so that its direction and distribution are appropriate for the conditions at the site of contaminant generation. Capturing hoods create a directed air current with sufficient velocity to draw contaminants from outside the hood itself (Goodfellow.H, Smith). Enclosing hoods surround the contaminant source as completely as possible. ii) Ductwork: - The ductwork is a network of piping which carries the captured contaminant out of the workspace to its final disposition. The primary goals in designing ductwork are to maintain sufficient air velocity in the piping, and to minimize the resistance to flow created by bends, junctions and changes in cross-sectional area. Maintenance of air velocity is important for transport of particulate contaminants, since if the air velocity falls below a critical value, the dust will deposit on the inner surfaces of the ducts and impede flow (Goodfellow.H, Smith). Resistance can be the major part of the energy required to operate the system, and a poorly designed duct system may cause so much resistance that the fan is unable to move the required volume of air. iii) Air Cleaner: - The air cleaning device removes the captured contaminant before the exhausted air is discharged. Collectors may range from simple centrifugal collectors much like the cyclone used to sample Respirable dust, to elaborate filters and gas/vapor absorbers specially designed for the 188
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 6, November - December (2013) © IAEME contaminant present. All air cleaners add to the total resistance of the system; generally, the more efficient the collector, the greater the resistance added. iv) Fan: - The final component provides the energy to accelerate the air as it enters the hood and to overcome friction and dynamic losses between the moving air and the surfaces of the ductwork and cleaning device. If possible the fan is almost always placed downstream of the air cleaner, to prevent deposition of contaminant on the fan blades, or damage due to contact with corrosive contaminants. 3.0 SYSTEM DESCRIPTION Figure 2 illustrates the dust extraction system for a crusher house, handling iron ore at a rate of 200 tones per hour (tph). It has following components: enclosures, hoods, duct network and mounting systems, pressure regulating valves, multi-cyclone dust collector, fan, motor and stack. The dust collected in the multi-cyclone hopper is fed back to the conveyor belt C3. The crusher is single roll of capacity 200 tones per hour (tph). The system has to operate at an altitude of 760 m having an average ambient air temperature of 450 C. The technical specifications of conveyor belts and roll crusher are presented in Table 1. The plant for which the system has to be designed is studied in detail to identify the points where dust generates and the factors responsible for the same. The plant layout, process flow-sheets, drawings and other operational details are carefully examined. The contour of fugitive dust cloud must be identified to delimit the zone of potential dust hazard. The optimum shape and position of the hoods depend on the dust cloud behavior. The entire working space is surveyed for installation and sampling and monitoring instruments to find out the dust loading, particle size distribution, shape and density and chemical characteristics of airborne dust particles. Fig. 2 Dust Extraction System for Crusher House of Iron Ore 189
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 6, November - December (2013) © IAEME 4. SYSTEM DESIGN The conveyor and crusher specifications are given in table as follows: Table 1. Technical Specifications of conveyor belt and crusher Description Design Detail C1 C2(2 numbers) CONVEYOR Mean diameter of iron ore (mm) 250 250 Capacity,tph 200 100 Volumetric flow rate of iron ore, m3/s 0.04 0.02 Belt width, Bbmm 0.12 0.08 Belt speed, Vb m/s 1.00 0.30 Surcharge angle, degree 25 25 Idler trough angle, degree 35 35 Skirt board length, m 4 Leakage area at belt loading zone, Ab, 0.08 m2 Falling material stream area, As , m2 0.40 0.25 Discharge chute cross section, Acs , m2 0.36X2 0.28X2 Leakage area at conveyor head pulley, 0.40 0.30 A1 , m2 Belt inclination, degrees 15 0 Chute inclination, θc , degrees 60 Height of free fall of material on 3.4 4.1 conveyor, h ,m Single Roll Crusher Volumetric flow rate of iron ore, m2/s 0.04 Diameter, m 1.34 Receiving chute cross section , m2 0.56 Chute inclination, θc , degrees 60 Height of free fall, m 4.1 Impact velocity of lumps at crusher top, m/s 8.97 Capture velocity, m2/s 1.5 Chute entry loss factor, ξ , dimensionless 2.3 Coefficient of drag, cd , dimensionless 0.44 C3 80 200 0.04 0.065 1.50 25 35 3 0.08 0.15 0.20 Nil 0 60 1.25 5. HOOD DESIGN The concept of air movement induction from the surroundings takes place when a falling material steam enters an enclosed space. This concept is used to find the exhaust volume in material handling and processing plants for transfer point operation taking place in an enclosed space. The theory of air induction is well developed for estimating exhaust flow rate through hoods for a number of enclosed material flow rates through hoods for a number of enclosed material handling transfer point operations. The rate of induced air flow depends upon the material flow rate, height of free fall and size of falling particles. It is also influenced by the chute cross section and the open area through which the induced air enters the enclosure. The effect of air induction will be reduced if the open 190
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 6, November - December (2013) © IAEME area is large. A high pressure zone will be created at the enclosure bottom when the falling material hits the base of the enclosure. As a result dust particles would escape through the leakage area around the impact zone. Hence, for effective control of dust emission, the net air volume flowing due to induction should also include an additional component of air volume that provides the necessary velocity for the capture of dust particles over the leakage area in material impact zone of the enclosure. It is generally agreed that the there is no best method for finding exhaust flow rate for hoods. In conveyor to conveyor discharge operations the component associated with capture velocity is much larger than the induced air component because of presence of large openings. The net air volume for exhaust ventilation consist of two components• Air flow to capture fugitive dust • Induced air flow from surroundings The exhaust air entering the hoods are estimated from given standards and practicing norms that takes into account both the induced air and captured air components. The proposed model for ventilation floe rate for material transfer from conveyor to conveyor/crusher/screen in an enclosure is given by the following relations: Qc = f(Al, Vc) and Qi = f(Vi , Qbs , Acs, dp,θc ) Table 2. Exhaust flow rate through hood Duct Diameter Velocity Length of (mm) (m/sec.) Straight Duct (m) 1360 23 3.53 Section Flow Rate (m3/hr.) P-3 120960 1-3 72997.2 1055 23 4.7 1277105.26 2-3 72997.2 1055 23 4.7 1277105.26 3-7 266954.4 2025 23 2.3 2451315.79 4-6 8685 360 23 8.7 435789.4737 5-6 75989.08 1075 23 3.2 1301315.79 6-7 84674.088 1140 23 3.2 1380000 7-10 351628.488 1160 23 2.5 1404210.526 8-10 3947.1 245 23 1.5 296578.9474 9-10 3947.1 245 23 2.2 296578.9474 10-11 359522.688 1160 23 1404210.526 11-12 359522.688 3250 12 2052631.579 12-13 359522.688 3250 12 Fan 359522.688 3250 12 Stack 359522.688 3250 12 191 2.2 Flow Reynolds No. 1646315.789 2052631.579 2052631.579 5.0 2052631.579
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 6, November - December (2013) © IAEME 5.1 Critical analysis of hood design A critical analysis of induced air and velocity assists in proper location of hoods. If Qi is greater than Qc, the hood must be located some distance away from the point of material impact to prevent the capture of coarse dust particles. For larger value of Qc, the hood must be located close to the source. Hood locations for enclosed transfer point operations of materials are shown in Figure 3. The air velocity at the face of hood for all enclosed transfer point operation must be in the range of 2 to 5 m/s. The hood dimensions will have to be selected on the basis of hood face velocity of the ventilated air and the available space of the casing on that it has to be installed. The following points may be noted for location and design of hood for conveyor to conveyor discharge. If Qi is greater than Qc, the hood must be located some distance away from the point of material impact to prevent the capture of coarse dust particles. For a larger value of Qc the hood must be located close to the source. Fig. 3 HOOD LOCATION In Figure 3.2, no hood has been provided at X but the hood at Y is nearer to the point of material impact than in Figure. The hood at Y has been designed to capture the net ventilated air due to induction and capture velocity. A hood has been provided at X in Figure and to provide a path for the flow of ventilated air associated with capture velocity through the skirt seal gap. Hood at Y collects the induced air and air flow associated with the moving material load. No hood will be required at X if the ventilated air component associated with capture velocity for the skirt seal gap is very low. It must always be tried to have a minimum number of hoods. A good skirt seal should be 192
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 6, November - December (2013) © IAEME provided to eliminate the hood at X. Usually; no hood is required at Z. However, a hood will have to be provided at Z, if there is a perfect sealing at the impact zone of material in the downstream. The hood in this case must be designed to handle the ventilated air associated with induction. Thus, it is essential to redesign and relocate the hoods. Fig 4. Revised Design of Dust Extraction System Fig 5. Schematic Line Diagram for Dust Extraction System 193
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 6, November - December (2013) © IAEME Table 3. Flow rate for revised duct network Section Flow Rate (m3/hr) Duct Diameter (mm) Velocity (m/sec) Length of Straight Duct (mm) 1-3 2-3 72997.2 72997.2 1055 1055 23 23 4 6 Elbows Angle Number (Degree) 14599.4 1499 23 1 Hoods and Connecting Pieces Flow Reynolds No. Hood at 1 Hood at 2 3 1 60 3-5 E-E 90 90 Branch Entry 1.277x106 1.277x106 30 2.45x106 2.3 L= 575mm F-F L= 800mm 4-5 8920.30 365 23 8 5-7 G-G 275874.7 2055 23 2.1 6-7 75989.08 1075 23 8.5 7-8 351863.7 2325 23 90 60 1 1 30 2.7 Hood at 4 4.418x106 2.487x106 L=900mm 30 1.301x106 2.814x106 Connecting pieces at multi cyclone outlet and fan inlet 2.033x106 Fan outlet connecting piece Stack 8-9 1 1 Hood at 6 Multicyclone Inlet Piece 90 60 2.033x106 Multicyclone 9-10 351863.7 3220 12 2.2 10-11 11-12 351863.7 351863.7 3220 12 2.2 12-13 351863.7 3220 90 12 2 Fan 2.033x106 6. DUCT DESIGN Many graphs and empirical relations for friction losses in straight ducts are available in standard design manuals. However, most of them are used for new or clean ducts. The manufacturers have their own proprietary standards and graphs for estimation of pressure drop but these are not easily available for friction factor over the range of feasible operating conditions. The turbulent or laminar nature of flow in duct is given by Reynolds number which is expressed asRed = (ρa/µ a)Vdd = νaVdd The air velocity in the duct must be equal to the transport velocity to move the dust particles without settling. The norms for transport velocity in duct for coal dust are given as (Russian Norms 1996), 194
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 6, November - December (2013) © IAEME • • • • • For horizontal ducts and ducts aligned at less than 60o Vd>18 and 20<Vd (m/s) 25. For vertical ducts and duct with inclination greater than 60o transport velocity condition is given by 10< Vd<18. For duct after the dust collector Vd >10 preferably between 14 to15 m/s. Duct diameter less than 100 mm should be avoided to prevent dust build up and duct plugging. The transport velocity should be preferably uniform in the entire duct network. The fluid flow is associated with two types of pressure namely Static Pressure (Ps) and Dynamic or Velocity Pressure (Pg). Total pressure is the algebraic sum of Static Pressure (Ps) and Dynamic or Velocity Pressure (Pg). Fluid flow through duct encounters resistance to flow from friction and turbulence Friction loss takes place due to the shear forces between (i) fluid particles resulting from the viscosity of the fluid and (ii) fluid particles and the boundary walls of the pipe. Dynamic loss occurs due to fluid turbulence from changes in flow direction or variations. It is always exerted in the direction of fluid flow and is expressed by the following equation, Total pressure PT is algebraic sum of static pressure and velocity pressure. 7. FRICTION LOSS IN DUCT Pressure drop due to friction in a duct is given by well-known Darcy Weisbach equation which is given by, Friction loss in a duct of length ld is given by, 7.1 Dynamic pressure loss The co-efficient of dynamic resistance is used to find the dynamic pressure loss due to turbulence or local resistance in duct accessories and fittings. 7.2 Total pressure loss 195
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 6, November - December (2013) © IAEME 8. BALANCING There are two common approaches for computing the pressure drop in a duct network. In the first approach pressure drop of fittings expressed in terms of dynamic pressure is computed with the help of standard tables and graph and added to the pressure drop of straight duct and in the latter approach equivalent length of fittings is computed and added to the length of straight duct to find the total pressure. • • Blast gate adjustment (by use of dampers, valves, diaphragms, venturis, etc) Balanced system design (by proper design of duct diameter) 8.1 Balancing by system Design A balanced system in any two branches at a junction may be obtained when (i) static and dynamic pressure as well as total pressure are balanced or (ii) both the branches have the same pressure losses (frictional and turbulence). It can easily show that the two approaches of balancing are not different i.e. when Ps, Pg and are balanced P is also balanced. According to the first approach, the flow at junction 3 will be in balance when any one of the following condition is satisfied: Therefore, The junction at point 7 will be in balance when the following condition is met: The duct diameter of the section having a lower pressure drop is reduced if the pressure. The duct diameter of the section having a lower pressure drop is reduced if the pressure. By trial and error and repetitive calculation a diameter can be chosen for that the difference in pressure is less than 5%. Balanced flow may be obtained by increasing the exhaust air flow rate in the section of lower pressure drop if the pressure differences of the two branches are less than 20%. 8.2 Balancing with Dampers In this approach no attempt is made to balance the pressure resistance. At each section branch flow is added to the main flow path and duct is sized to maintain the required transport velocity. The balance is achieved by using pressure regulating devices, blast gates and dampers. 196
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 6, November - December (2013) © IAEME Table 4. Balance by design 3 2-3 72997.2 1055 23 6 90 1 60 1 30 236.12 241.38 241.38 0.88 4.36 236 240.36 241.38 19.92 770.7 770.7 770.7 770.7 Friction 5.269 261.3 Entry 0.88 Remarks 90 Governing pressure (N/mm2) 4 Total Branch 23 Turbulence Length of Straight Duct 1055 Local Loss Coefficient Velocity 72997.2 Flow Rate (m3/hr.) 1-3 Section Duct Diameter (mm) Pressure Loss(N/mm2) The flow is balanced at junction 3. 3-5 14599.4 1499 23 2.3 19.92 1-3-5 4-5 8920.30 365 23 8 90 1 60 30 0.462 2.87 767.83 Use Damper in 1-3 1 Reduce the diameter of section 1-3 & 2-3 and recheck for balance. Section 1-3, 2-3 is balanced at flow rate 72997.2 m3/hr & duct dia is 775 mm. The flow is balanced at junction 5. 2-3 75025.97 775 2055 42.9 8 23 5-7 4-5-7 6-7 277903.47 78018.55 6 2.1 1075 23 8.5 90 1 30 0.73 26 683 709 770 243.69 19.5 790.2 247.9 790.2 790.2 790.5 19.5 90 60 1 1 30 0.89 4.26 2-3 Reduce the diameter of section 6-7 and recheck for balance. Section 5-7 is balanced at flow rate 78018.55 m3/hr & duct dia is 1075 mm The flow is balanced at section 6-7 7-8 357453.43 2325 0.214 4-5-7-8 8-9 357453.43 9-10 Fan 357453.43 357453.43 3220 Fan 12.5 11-1213 357453.43 3220 12 16.73 60 2.2 90 2 0.166 2.2 1.25 197 1.68 1.68 16.30 91.21 790.2 Use Damper in 6-7 866.6 1000 Multicyclone 76.63 1866.6 Vendor’s data 17.98 196 1884.58 2080.58 92.89 2173.47 Fan loss is 10% of total loss
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 6, November - December (2013) © IAEME 4-5 8920.30 365 23 8 5-7 4-5-7 6-7 275874.7 2055 23 2.1 75989.08 1075 23 8.5 7-8 351863.7 60 236.12 236 241.38 240.37 241.38 241.38 19.92 261.3 770.7 770.7 767.83 770.7 1 770.7 790.2 790.2 790.2 19.92 90 60 1 1 30 0.4622 2.87 351863.7 3220 16.73 57.45 74.18 847.65 1847.65 17.98 196 1865.63 2062.51 92.89 Use Damper in 1-3 2155.40 0.1668 12 Use Damper in 2-3 847.65 Fan 11-1213 243.69 30 351863.7 351863.7 351863.7 4.26 1000 1 1 0.89 847.65 9-10 Fan 19.5 90 60 19.5 790.2 247.95 0.214 4-5-78 8-9 Remarks 2.3 30 5.269 4.36 Governing pressure(N/m2) 23 0.88 0.88 Total 1499 3 1 Turbulence 14599.4 90 90 Friction 3-5 1-3-5 Entry 4 6 Local Loss Coefficient Length of Straight Duct 23 23 Pressure Loss(N/mm2) Branch Velocity 1055 1055 (mm) 72997.2 72997.2 Flow Rate (m3/hr) 1-3 2-3 Section Duct Diameter Table 5. Balance by dampers 2.2 1.25 1.68 1.68 16.30 91.21 Use Damper in 6-7 Vendor’s data Fan loss is 10% of total loss 9.0 CONCLUDING REMARKS The mining industry is not generally regarded as a high technology sector. Nonetheless many developments in advanced technology are revolutionizing mining by improving process efficiency and capacity to achieve and sustain best practice environmental management. The traditional method of design was not taken into consideration as the actual process and physical reality and most empirical models lack sound theoretical basis. In many instances the traditional method of design results in faulty system which includes additional cost and maintenance problems. This work results saving towards maintenance and installation of dust extraction system. A number of standards are available for pressure loss in duct fittings. Pressure loss can be obtained from complex multivariable tables and charts. There are wide discrepancies in the results obtained from different sources. In this work pressure loss coefficients for different fittings are presented in the form of mathematical relations to facilitate easy computation for balanced flow design. Different approaches for balanced flow is examined and it is found that there is no difference in the methods of balancing a duct network. 198
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 6, November - December (2013) © IAEME Notations Acs Al - d dp ld Pg Pg1-3 PS1-3 PS Qbs Qi Q1-3 Qa Red R1-3 RS Rf Rt Vc - VD Vi - Pf PF PT P1-3 ηF θc µa νa ρa ρp Σ - cross sectional area of the chute, m2 cross sectional area through that the dust escapes into the surroundings after the material impact on the receiving system, m2 duct diameter, m particle mean diameter, m total length of the duct, m dynamic pressure, N/m2 dynamic pressure in section 1-3 of the duct and so on, N/m2 static pressure in section 1-3 of the duct and so on, N/m2 static pressure, N/m2 volumetric flow rate of the bulk solids being handled, m3/s volumetric flow rate of air due to induction, m3 /s volumetric flow rate of air in the section 1-3 and so on volumetric flow rate of air, m3 /s Reynold's number for fluid flow in duct, dimensionless resistance to flow in the section 1-3 and so on total resistance to the flow, N s2 m-8 frictional resistant, N s2 m-8 turbulence resistant, N s2 m-8 capture velocity required to prevent the dust from escaping though the leakage area Al of the material impact zone, m/s velocity of air in duct, m/s mean velocity of the individual lump of falling stream of bulk solids at the impact point, m/s pressure drop due to friction per unit length, N/m2/m total pressure drop due to friction, N/m2 total pressure loss,N/m2 pressure drop in section 1-3 of the duct and so on, N/m2 overall efficiency of fan slope of chute, degree dynamic viscosity of air, kg/ms kinematic viscosity of air, m2/s air density, kg/m3 particle density, kg/m3 local loss coefficient REFERENCES [1] [2] [3] [4] [5] Tsuji. Katsuhiko, H. Taro, S. Masaru,”Required Exhaust Volume for Lateral Hood” 1978. Moody. Jakhete.R,”Dust control hand book”, Noves data corporation, New Jersey, 1989. War Hurst. A, Bridge G,” Improving Environmental Performance through Innovation: Recent Trends in Mining Industry”, Elsevier, vol. No. 9, pp. 907-921, 1996. Ullman A, Dayan A, “Exhaust Volume model for dust emission control of belt conveyor transfer points”, Powder Technology, vol.96, pp. 139-147, 1998. Witt. P.J, Carey, K.G, Nguyen, T.V,”Prediction of dust loss from conveyor using computational fluid dynamics”, Elsevier, vol. 26, pp. 297-309, 2002. 199
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 6, November - December (2013) © IAEME [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] “10 key steps for comparing dust extraction system”, SHAPA TECHNICAL BULLETIN, no. 6, pp. 1-13, 2002. Hilson. G, “Defining clear production and pollution prevention in the mining context” Elsevier, vol. 16, pp. 305-321, 2003. Kissell, N. Fred, “Hand book for Dust Control in Mining”, NIOSH Publication, 143, 2003. Dwivedi, R., Sinha, A.N., “Design and analysis of dust extraction system”, bulk solid handling, vol. 6:3, pp. 131-143, 2006. Silvester .S, Lowndes. I, Kingman. S,” Improved dust capture methods for crushing plant”, Elsevier, vol. 31, pp. 311-331, 2007 Countess, R. J, Cowherd, C,”Development of a fugitive dust handbook”, 1134. Goodfellow.H, Smith. Industrial Ventilation, pp 14.1-14.15. Norm 4.1,”Dust control strategies”, vol.4.1, Chamber of mineral and energy, 2010. Ramesh Chandra Mohapatra, Antaryami Mishra and Bibhuti Bhushan Choudhury, “Investigations on Tensile and Flexural Strength of Wood Dust and Glass Fibre Filled Epoxy Hybrid Composites”, International Journal of Mechanical Engineering & Technology (IJMET), Volume 4, Issue 4, 2013, pp. 180 - 187, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359. Dr.N.G.Narve and Dr.N.K.Sane, “Experimental Investigation of Laminar Mixed Convection Heat Transfer in the Entrance Region of Rectangular Duct”, International Journal of Mechanical Engineering & Technology (IJMET), Volume 4, Issue 1, 2013, pp. 127 - 133, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359. Anup Kumar and Anil Kumar Mishra, “A CFD Investigation and Pressure Correlation of Solar Air Heater”, International Journal of Mechanical Engineering & Technology (IJMET), Volume 4, Issue 2, 2013, pp. 401 - 417, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359. 200