International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 1, January 2013)
Productivity Improvement of Screw Conveyor by Modified Design Jigar N. Patel1, Sumant P. Patel2, Snehal S. Patel3 1
2
Research scholar, U.V.Patel engg. Coll. Ganpat univ. Assistance Proffessor, U.V.Patel engg. Coll. Ganpat univ. 3 Research scholar, U.V.Patel engg. Coll. Ganpat univ. The rate of volume transfer is proportional to the rotation rate of the shaft. In industrial control applications the device is often used as a variable rate feeder by varying the rotation rate of the shaft to deliver a measured rate or quantity of material into a process.
Abstract—Screw(Auger) conveyors are widely used for transporting and/or elevating particulates at controlled and steady rates. They are used in many bulk material applications in industries ranging from industrial minerals, agriculture, chemicals, pigments, plastics, cement, sand, salt and food processing. They are also used for metering (measuring the flow rate) from storage bins and adding small controlled amounts of trace materials such as pigments to granular materials or powders. Here in this paper we represent the modification of screw conveyor for get same output from modified design with reduced size and less power consumption. And also given the generalized design of shaftless screw conveyor(SSC) for 2 tonnes per hour capacity to convey cement. The finite element analysis (FEA) of both model is given so we can easily find that the design is safe or not for industrial use.
Screw conveyors can be operated with the flow of material inclined upward. When space allows, this is a very economical method of elevating and conveying. As the angle of inclination increases, the allowable capacity of a given unit rapidly decreases.
Keywords—Screw conveyor, Auger, SSC, FEA, bulk material.
I. INTRODUCTION A screw conveyor or auger conveyor is a mechanism that uses a rotating helical screw blade, called a "flighting", usually within a tube, to move liquid or granular materials. They are used in many bulk handling industries. Screw conveyors in modern industry are often used horizontally or at a slight incline as an efficient way to move semi-solid materials, including food waste, wood chips, aggregates, cereal grains, animal feed, boiler ash, meat and bone meal, municipal solid waste, and many others. First screw conveyor was invented by Archimedes (circa 287–212 B.C.).For elevating water from the hold of a King Hero of Syracuse ship.[1] The geometry of an Archimedes screw is governed by certain external parameters (its outer radius, length, and slope) and certain internal parameters (its inner radius, number of blades, and the pitch of the blades). Chris Rorres[2] found that the inner radius and pitch that maximize the volume of water lifted in one turn of the screw. They usually consist of a trough or tube containing either a spiral blade coiled around a shaft, driven at one end and held at the other, or a "shaftless spiral", driven at one end and free at the other.
Fig. 1.1 Screw conveyor[8]
The rotating part of the conveyor is sometimes called simply an auger. The aim of this paper is to design of 2 tonnes per hour capacity screw conveyor as per IS codes and to setup generalized methodology to design screw conveyor. The modification of screw conveyor is done by removing shaft from screw and setup generalized methodology to design shaftless screw conveyor. II.
DESIGN AND ANALYSIS OF SCREW CONVEYOR
The capacity of screw conveyor depends on the screw diameter, screw pitch, speed of the screw and the loading efficiency of the cross sectional area of the screw. The capacity of a screw conveyor with a continuous screw may be expressed as[3]: 492
International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 1, January 2013) Q = Vƍ Q = 60 D2SNѱƍC From this equation we get the diameter of screw conveyor required to convey material. Design is given for convey cement. The distance is about 5 meter. For this parameter 148mm diameter is required. Power requirement of screw conveyor basically depends on the length of screw conveyor, capacity and a factor for total apparent resistance. This resistance varies with respect to type of material conveyed that is its nature, abrasiveness, grain size, internal resistance, etc., and many also depend upon the degree of filling. There are various factors with quite a few variables involves for determination of power requirement of screw conveyor depends, are as follows [4] [5]: a. Friction between the casing and the transported material. b. Friction between the screw and the transported material. c. Friction in the intermediate and in the end bearing and hence on type of bearings installed. d. Friction in the axial bearing owing to axial force. e. Additional resistance due to partial compensation of thermal expansion of the screw supported between the material or when the temperature difference between winter and summer is too high and the screw conveyor is comparatively long. f. Additional resistance owing to accumulation of transport material at the intermediate bearings, mixing and rolling of the transport material. g. Additional resistance for friction of the screw edge with the transport material when a grain is wedged between the grain between the screw and the casing. h. Additional resistance fir upward conveying in case of inclined screw conveyors. The various factors mentioned shall apply basically to horizontal and slightly inclined screw conveyor. For vertical screw conveyor there may be some other factors also. The total power required to run the screw conveyor is given by: Pt = From above equation we find that 0.149 kw power required to convey the material. Modelling of screw conveyor is carried out using solid works 2009.
Fig. 2.1 Model of screw
And analysis of screw conveyor is carried out using ansys 12.1. Applying the loading conditions
Fig. 2.2 loading conditions
Result
Fig. 2.3 Total deformation
493
International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 1, January 2013) Modelling of screw conveyor is carried out using solid works 2009.
Fig 2.4 Equivalent stress
From above figure we find that the total deformation of conveyor is 1.93 mm and equivalent stress is 149.2 Mpa. From the result, the total deformation and stresses are permissible. III.
Fig.3.1 Shaftless Screw
Analysis of the model is carried out using ansys 12.1.
DESIGN AND ANALYSIS OF SHAFTLESS SCREW CONVEYOR
The shaftless screw conveyors open up new and special areas of application for screw conveyance, which are determined according to special properties of the bulk solids. The SSC expands the screw conveyor’s field of application and is used for those bulk solids, when the usual screw conveyor cannot be used. The principles of calculation for usual horizontal and lightly inclined screw conveyors cannot be applied for shaftless screw conveyor, because of considerable differences in design, principle of work and in areas of application [6]. The fill ratio of shaftless screw conveyor is usually taken between 0.5 ≤ n f ≤ 0.9, the fill ratio in vertical shaftless screw conveyors is always n f ≈ 1.0. The volumetric ratio n v shows how much usable volume of a trough is occupied by the volume of the shaftless screw and can be calculated as the ratio between the screw and the trough volume. nv = 1 -
Fig. 3.2 loading condition
Result
The mass throughput of shaftless screw conveyor are given by[7] Im = I V * ρ b Im = dT2 *
* nw * lSt* nF * nV * kF * kδ * ρb Fig. 3.3 Total deformation
So, from equation we find that the 90 mm diameter is required to convey material.
494
International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 1, January 2013) Total Deformation comparison Table II Total Deformation comparison
Total Deformation Existing Design Modified Design
Value Maximum 1.9359 mm 0.17023 mm
Minimum 0 mm 0 mm
Deformation mm
Total Deformation
From above figure we find that the total deformation of conveyor is 0.17 mm and equivalent stress is 67.27 Mpa. From the result, the total deformation and stresses are permissible and lesser then the existing model.
From above analysis of both model we find that the deformation and stresses are reduce in modified model. The comparisons of both model is given below. Graph of each comparison is given. Stress (von-mises stress) comparison
Existing Design Modified Design
Stress comparision
Stre ss , Mpa
•149.2 Mpa •67.27 Mpa
100
0
The following were derived from design, modeling and analyzing of the both design. First, the both model developed in solid works 2009 software. The static model analysis was performed on ansys 12.1. The FEA modeling and simulated data were generated. The stresses and deformation developed in models are permissible. The maximum deformation and stresses of modified design are 0.17 mm and 67.278 Mpa. So, the deformation and stresses in modified design is much lesser then existing design. We can get same output from modified design with reduced size of conveyor. The power consumption and weight of conveyor also reduce around 12% of existing design.
Minimum 0.044 Mpa 0.0021 Mpa
150
1
V. CONCLUSION
Table I Stress comparison
Value Maximum 149.2 Mpa 67.278 Mpa
•1.93 mm •0.17
Deformation is occurs due to transportation material as Existing design Modified design well as the self-weight of structure. As per analysis total deformation developed in structure is under permissible value.
IV. RESULT AND DISCUSSION
Stress
2
,
Fig 3.4 Equivalent stress
REFERENCES
50 [1] Don McGlinchey. 2008 ―Bulk Solids Handling: Equipment Selection and Operation‖ Page No. 197-219 Blackwell Publishing Ltd. ISBN: 978-1-405-15825-1.
0 Existing design Modified design
[2] Chris Rorres 2000. ―THE TURN OF THE SCREW: OPTIMAL
The main cause for failure in screw conveyor is due to generated stresses during operation. By comparison of the results of maximum stresses it can be easily predict that the stresses generated in the modified design are lesser than the stresses in the existing design. From above comparison we find that the stress is reduced 54.91%.
DESIGN OF AN ARCHIMEDES SCREW”,JOURNAL OF HYDRAULIC ENGINEERING Page : 72-80
[3] Siddhartha ray 2008 ,‖ Introduction to Material Handling‖ New age international publication , page no 112-118
[4] IS 12960 :1990, "Determination of power requirement of screw feeder – general requirement"
495
International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 1, January 2013) [5] T. K. Ray, 2004 ―Mechanical handling of materials‖,Asian books publications. pp. 92-105.
[6] Prof. Dr. Friedrich Krause 2006 ―Theoretical and experimental study of horizontal and lightly inclined shaftless screw conveyors , part-2‖ WISSENSPORTAL baumaschine.de 3.
[7] Prof. Dr. Friedrich Krause 2006 ―Theoretical and experimental study of horizontal and lightly inclined shaftless screw conveyors , part-1 ―WISSENSPORTAL baumaschine.de 3.
[8] www.rhengineers.tradeindia.com.
496
