Design and analysis of screw conveyor

Institute of Technology, NIRMA UNIVERSITY 1

Design and Analysis of Screw Conveyor

Presented by :Gandhi Keyur(08MME004)M.Tech (CAD/CAM)

Guided by :Dr. D. S. Sharma


Outline of Presentation • Introduction to Screw Conveyor• Major Screw Conveyor Components• Types of Screw Flight• Types of pitch• IS code using for designing • Design of screw conveyor• Matlab program for screw conveyor design• Modeling of screw conveyor

– Exploded View of Screw Conveyor• Powder property and screw conveyor capacity• Effect of vortex motion on the Volumetric Performance of Enclosed Screw Conveyors• System for Conveyor Equipment Selection• Future Work of Project• References


Introduction to screw conveyor

• Screw 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 (grains), pharmaceuticals, 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.


Major Screw Conveyor Components:

• Hopper or Bin• Stationary screw casing (tubular, open or

covered trough)• Rotating screw.


Types of Screw Flight


Types of pitch

Standard Full Pitch P/D = 1Used for conveying material horizontally or on slight inclines.

Half Pitch P/D = 0.5Used in screw feeders, also in conveyorswhere material is being conveyed up anincline.

Double Flight Full Pitch P/D = 0.25Used in conveyors where an even discharge of materials is required.

RibbonUsed in conveyors to convey sticky materials.


CutUsed in conveyors where mixing materials is desired.

Cut and FoldUsed in conveyors where high levels of mixing materials and increased retention time is desired.

Varied PitchUsed in screw feeders, short pitch below inlet, full pitch beyond to allow material loading to drop.

Cone with Consistent PitchUsed in screw feeders where an even loading across the inlet length is desired.

Cone with Varied PitchUsed in screw feeders where a specific loading across the inlet length is desired.


IS code using for designing

• IS 5563 :1985 Screw conveyor for industrial use

• IS 13324 :1982 Screw Feeders• IS 12960 :1990 Determination of power

requirement of screw feeder – general requirement


Design calculation

• Q = V.ρ = 60 ∏/4 D2.S.n.ψ.ρ.c

– V = volumetric capacity (m3)– ρ = Bulk Density of the material (kg/m3) – D = nominal diameter of screw conveyor(m)– S = screw pitch (m)– N = R.P.M. of screw – Ψ= loading efficiency of screw – C = factor to take into amount the inclination of screw

conveyor


Matlab program for screw conveyor design

• Q = input('Enter the capacity of conveyor in tons / hour : ')• th = input('Enter the inclination of conveyor degree : ')• if th>=0&&th<5• inclinationfactorC=1• elseif th>=5&&th<=9• inclinationfactorC=.9• elseif th>=10&&th<=14• inclinationfactorC=.8• elseif th>=15&&th<=19• inclinationfactorC=.7• elseif th==20• inclinationfactorC=.65• else• inclinationfactorC=.5• end• Length = input('Enter the length of conveyor in metres : ')• Bulk_Density = input('Enter the Bulk Density of conveying material in kg/cubic metre : ') • conveying_material = input('Enter the type of conveying material \n press 1 for abresive,\n press 2 for midly abresive and \n press 3

for non abresive and free to flow : ')


Matlab program for screw conveyor design

• switch conveying_material• case 1• progress_resistance_coefficient = 4• loading_efficiency = 0.125• %fprintf('loading efficiency of conveying material is=%f\n',loading_efficiency)• case 2• progress_resistance_coefficient = 2.5• loading_efficiency = 0.275• %fprintf('loading efficiency of conveying material is=%f\n',loading_efficiency)• case 3• progress_resistance_coefficient = 2.5• loading_efficiency = 0.425• %fprintf('loading efficiency of conveying material is=%f\n',loading_efficiency)• • otherwise• disp('Unknown conveying_material ')• end• Pitch_to_Diameter_Ratio = input('Enter the Pitch to Diameter Ratio of conveyor between 0.75 to 1.0 :')• speed = input('Enter the speed of conveyor in RPM :')• diameter_of_conveyor = ((Q*4)/(22/7*60*Pitch_to_Diameter_Ratio*speed*loading_efficiency*Bulk_Density*inclinationfactorC))^(1/3)• fprintf('diameter_of_conveyor =%f metre\n',diameter_of_conveyor)• power_req = Q/367*progress_resistance_coefficient*Length + Length * sin(th*3.14*2) + (diameter_of_conveyor * Length)/20• fprintf('power_req = %f kilowatt \n',power_req)


Matlab run program• Enter the capacity of conveyor in tons / hour : 50• Q =

• 50

• Enter the inclination of conveyor degree : 15• th =

• 15

• inclinationfactorC =• 0.7000

• Enter the length of conveyor in metres : 25• Length =

• 25

• Enter the Bulk Density of conveying material in ton / cubic metre : 1.6• Bulk_Density =

• 1.6000• Enter the type of conveying material • press 1 for abresive,• press 2 for midly abresive and • press 3 for non abresive and free to flow : 1

• conveying_material = • 1• progress_resistance_coefficient =

• 4

loading_efficiency =

0.1250

Enter the Pitch to Diameter Ratio of conveyor between 0.75 to 1.0 :1

Pitch_to_Diameter_Ratio =

1

Enter the speed of conveyor in RPM :50

speed =

50

diameter_of_conveyor =

0.5331

diameter_of_conveyor =0.533112 metre

power_req =

13.0963

power_req = 13.096333 kilowatt

Ans : Diameter = 533 mm Power req. = 13.KW

For 50 ton/hour output capacity

Institute of Technology, NIRMA UNIVERSITY 13Modeling of screw conveyor


EXPLODED VIEW OF SCREW CONVEYOR


Powder property and screw conveyor capacity

• Coarse powders will flow into the screw easier than fine powders.

• The screw capacity will also be higher if a dense powder is used.

• Particle with a round shape have lower internal friction that results in a greater screw capacity.

• The clearance and the free length of the intake have a big influence on screw capacity.

• No correlation between conveying length and conveyor capacity was found.[1]


Effect of vortex motion on the Volumetric Performance of Enclosed Screw Conveyors

• Vortex motion arises as a result of internal friction, friction between the granular material and surface of the helical blade.

• The vortex motion, together with the degree of fill govern the volumetric efficiency. [2]

• = Rotational or vortex efficiency• = Fullness Efficiency = • = Average height of material on the screw surface.


System for Conveyor Equipment Selection

• The system provides the user with a list of conveyor solutions for their material handling needs along with a list of suppliers for the suggested conveyor devices.

• Conveyor types are selected on the basis of a suitability score, which is a measure of the fulfillment of the material handling requirements by the characteristics of the conveyor.

• The Expert System(ES) approach to conveyor selection provides advantages of unbiased decision making, greater availability, faster response, and reduced cost as compared to human experts.

• The computation of the score is performed through the Weighted Evaluation Method

Institute of Technology, NIRMA UNIVERSITY 18Conveyor category selection screen [3]


Attribute importance specification screen [3]


FUTURE WORK OF PROJECT

• Design of screw conveyor.• Programming of screw conveyor design• CFD analysis of screw conveyor. • Prediction of screw conveyor performance at

different operating condition.– The rotational speed of the screw.– The inclination of the screw conveyor.– The volumetric fill level of the bulk material.


References1) Alma Kurjak ,The vertical screw conveyor- powder properties and Screw

conveyor design , SE-221 00 Lund ,Sweden January 2005.2) A.W. Roberts, The influence of granular vortex motion on the volumetric

performance of enclosed screw conveyors, Callaghan NSW, 2308, January 1999.

3) Daniel J. Fonseca*, Gopal Uppal, Timothy J. Greene, A knowledge-based system for conveyor equipment selection, Elsevier 26 (2004) page no. 615–623.

4) Jianjun Dai, John R. Grace, Biomass screw feeding with tapered and extended sections, Powder Technology 186 (2008) 56–64, Elsevier

5) W. McBride, P.W. Cleary, An investigation and optimization of the ‘OLDS’ elevator using Discrete Element Modeling, Powder Technology 193 (2009) 216–234, Elsevier

6) T. K. Ray, Mechanical handling of materials 2004,92-105

Engineering

Design and analysis of screw conveyor