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IS: 9178 (Part II I ) -1980Indian Standard

Reaffirmed 2010

CRITERIA FOR DESIGN OF STEEL BINS FOR

STORAGE OF BULK MATERIALS

PART 111 BINS DESIGNED FOR MASS FLOWAND FUNNEL FLOW

IND IAN S T A N D A R D S I N S T I T U T I O NBHAVAN, 9 BAHADUR SHAH ZAFAR MARG

N E W DELHI 110002

Janua ry 1982

Copyright1982

MANAK

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s : 9178 ( Part III 98ndian Standard

CRITERIA FOR DESIGN OF STEEL BINS FORSTORAGE OF BULK MATERIALS

P RT III INS DESIGNED FOR M SS FLOWN FUNNEL FLOW

Structural Engineermg Sectional Committee, SMllDC 7hairman

DIRECTOI: Sl ANIJARDS ( CIVIT, )A[ bers

SnR I R. i \f AGAR VALDIt Puuv KurSUN ( Alternal. )SUIH A K I lAXLltJEI .

Repr;se llngMimst ry of Railways

Insriturion of Engineer ( Inrha }, CalcuttaMetallurgic d an d Engrncerrng Consultantsl India) Ltel, Ranchi

Sum S. SA KARAN (Allerrral )Slim P. G. ihnDIIAN Brauhw.ntc Co Lt,l, Ca lcutra::: HI : : : K t; , , ,COPAllI lY, Y (Altemale )SlIIlI S, N BASU Inspccuon Wing, Drrecrorate General of Supplies

ami D. pm h, New DellnSII D Il I (AIJ,mal )Sru.t P. C JIll 1 1 Mrmsrrv ofS Jippilll'; -md Transport (Departmentut I rnnvpor-t ) Road, WIIII ; )DIt 1'. N CIH . L T l Government 01 W tBengal

DR P D,YA A I 1A Indr.m Inst i tute of Technology, Kanpuri:>lilti D S J) \ N. Dastur Co PH Ltd, Calcutta

::: 1I1l1 D I R J . ~ j O S T A u JI 8 Muustry of Railways(B S)

1\88 81 \ 1 Dl ln l run ( B S)sn Alternate )jvr r DIHLLr l l I (D.,, , , , , ) Natronal Burldrngs Orgaruzution, New DelhiSum K S S1U I\AS, :>I ( .Jllernal.)SI IHI KAH. l lK \U Indian Roads Congress, New DelhiSHIU:::' C, CIHK l lA l l T I .lllernal )

{ Cnnllnwd on page : }@ OPYrlghl 198t

INDIAN STANDARDS INSTITUTIONThu publicanon I I protected u.ider the Indian Copy ghi Acl ( XIV of 1957) andreproducllon 10 whole or ID part by an y means except with written permission of thepUblisher shall be deemed to be an inCflngement o copyright under the ,aId Act.

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IS 9118 Part I 198

In d ia,

Representlll,Jessop Co Ltd, Calcutta

flhlllUd ftl l e I )MembersSHIU P. K. MALLICK8Hm T S. BAGCHI ( AlttTMte )SHIU S. K. MUKHEIlJEE Bridge Roof Co ( India) Ltd, HowrahSHIll n. K CHATTERJEll ( AlternateSalll P V. NAIK RIchardson Cruddas Ltd, Bombay

SnRI V. G. MANORULKAR AllernateSHill DILIF PAUL Industrial Fasteners Association ofCalcuttaBmny Ltd, MadrasHin N RADHAKRISHNAN

SHIn P. ApPARAO ( AlternateSIun N. V. R....tAN Structural Engineermg Research Centre, MadrasDn T. V. S. R. ApPARAO ( AlternateSHIll C. S, s RAO Engmeer-in-Ohrefs Branch, Ministry DeCellceREPIlESENTATlVE Tata Consultrng Engmeers, New DeihlREPRESENTATIVE Hindustan Steel Works Construction Ltd,CalcuttaRai l Ind ian Technical and Economics Services,New DeihlSlun A B. RIBEIROSHIll S K BUANDT ( AlltTnateSHill P SENGUP1 A Stewarts Lloyds of Ind ia L td , Calcu tt aSHIll M. M. GnOSH A.lternateSH1U M. M. SUENOY JOInt Plant Committee, CalcuttaSHRl D. SRINIVASAN Allt:rnaleSnm C. N. SRINIVASAN CR. Narayana Rao, Karpagambal Nagar, MartrasSIIIlI C N RAG1IAVENDIIAN AlltrMle)SHIll G SIlmp A AN l lharat Heavy Electrrcals Ltd, I iruchirapalhH. K. TANJ JA Indran Register of Shipping, BombaySHEI D SAIlANGDIlAR AlternaleSHIll M. D. [HAMDEKAR Bombay Port Trust, BombayOil D. N TIl,mN s

SHRI S. CHATTERJEESHI

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MARCH 98MENDMENt NOto

IS 9178 Part III )-1980 CRITEIUA FORDESIGN O STEEL BINS FOR STORAGE OFBULK MATERIALS

PART SINS SIGN FOR MASS FLOWANDFUNNEL FLOWCol rilead1lm

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IS : 9178 Part JIJ ) .1980ndian tandard

CRITERIA FOR DESIGN OF STEEL INS FORSTORAGE OF ULK M TERI LSP RT II I INS SIGN FOR M SS FLOW

ND FUNN L FLOW

FOREWORD0.1 This Indian Standard Part was adopted by the IndianStandards Institution on 7 July 1980, after the draft finalized by theStructural Engineering Sectional Cornrmttee had been approved bythe Structural and Metals Division Council and the CIVIl EngineeringDivision Council,0.2 Bins are known as silos if they have circular or polygonal shape inplan. When square or rectangular in plan they are known as bunkers. Inthis standard. bin shall mean both silos and bunkers unless otherwisestated.0.3 The functions of bins as storage structures are very important in powerstations, fertilizer complexes, steel plants, cement plants and other similarindustries for efficient storage and use of bulk m at er ia l in both granularand powdery form. On the agriCultural front bins are used to store food.grains for ensuring their supply throughout the year. Bulk storage ofmate ria ls in bins has certain a dv an ta ge s over o th er forms of storage. AnIndian Standard on this subject has, t her efor e, been a long fclt ne ed andthis standard is arm ed at givmg the necessary guidance the analysis anddesign of steel bins for storing various materrals of different characteristicsand flow properties.0.4 Bins have been designed on the basis of Janssen s Theory withmodifications to the original . From experimental investigations and astudy of the perform ance of the existing bins, it has been noticed that thepressure distribution is influenced by the size and shape of the material tobe stored that is granular or powdery , moisture and temperature, bulkdensity, which, in t ur n, are affected by storage and flow characteristics.Besides, there is increase in the imposed loads during filling and emptying,the latter being more predominant.0.5 For reasons me ntione d above, in the bins designed by conventionalmethods, m aterials do not easily flow due to arching and piping. This

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IS 9178 Part 1980requires frequent poking - manually, pneumaticallv, with steam or byother mechanical means. With rr-sr-arch data available, this problem hasbeen successfully solvcd by adnpting mass Iluw or funnel flow bins wherethe shape of the bin hopper and the size of the openmg, are based on theflow properties of the stored material.0 6 In this part of the code the present t hmking on the design of massflow and funnel flow bunkers based on jernke s work is explamed. Furtherresearch in this field is cnntinuJO ; and it will not be possible to give aumvcrsal approach for all rnaterrals under varymg scrvrce conditions. is standard has lunitauons winch are explained in Appendix Awith proper reference. i therefore, suggested that designers shouldconsider all these aspects while adopting the recommendations given inthis code.0 7 In order to deal with the subject 10 an effective manner this standardhas been prepared in three parts, namely,

Part I General requirements and assessment of loads.Part Design crrreria,Part Bins designed for mass flow and funnel flow.

0 8 Thi s s tandard keeps in view the pract ices being followed in Indiaand elsewhere in th e field. Assistance has also been der ived f rom thefollowing publications:

I. DIN 1055 (Sheet 6 Design loads for building bins, issued byDeutsche Norrnenausschluss.

2. Pressure distribution in bins (in German) Pioper K., andWenzel, F. Verlag Vom Wilhelm Erust Sohn, Berlin,Munchen, 1964.

3. Bins and bunker for handling bulk material eisner \V andRothe, M E. Trane-Tech. Publication, Ohio, USA

4. Jenike, A. W.; Storage and flow of solids, Bull 123 (UtahEngmeering Experiment Station, Unice. of Utah, U.S A. ),1964.

5. Jenike, A. W.;Johanson, JR . ; Carson,J. W.; Bin loads - PartConcepts, bin loads - Part 3: Mass flow bins, bin loads - Part 4:Funnel flow bins, Published in the Journal of Engineering fonIndustry Feb 1973 by American Society of MechanicalEngineers.

0 9 Recommended literature for reference is given in Appendix B.0 10 For th e purpose of deciding whether a particular requirement of thisstandard is complied with, the final value, observed or calculated, express,ing the result of a test or analySIS, shall be rounded off in accordance with

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IS: 9178 Part III 198IS : 2-1960 . The number of significant places retained in the rounded offvalue should be the same as that of the specified value in this standard.

SE TION I GENER LI. SCOPE1 1 his standard Part I dl .lls with the design of steel brns orstorage of bulk materials ensuring satisfactory mass ow and funnel ow( plug f low) under gravity flow the case of powdery and granularmaterials.2 TERMINOLOGY2 1 For the purpose of this standard, the definitions given in Parts and in addition to the following definitions shall apply.

2 1 1 ctive Pressure ield - The field in which the major pressure isvertical or near vertical.2 1 2 rched Pressure Fields - In arched pressure fields major pressurelines arch across flow channels, synonymous with passive pressure insoil mechanics.2 1 3 harger - Deposition of bulk solid into a bin, usually hy droppingin or blowing from above.2 1 4 ylinder - Vertical part of a bin.2 1 5 raw - Withdrawal or feeding of bulk solids from a bin.2 1 6 low hannel - Space through which a bulk solid is actuallyflowing during draw.2 1 7 low Pressure - Pressure which the mater ia l exerts on the wallsof a bin during flow2 1 8 Funnel or Plug low - The flow pattern in which the materialflows primar ily in the central region of the bin or hopper.2 1 9 Initial Pressure - Pressure exerted by bulk solids on the walls of

the bin during and after charging, but before any withdrawal of thematerial.2 1 1 Mass low - Flow in which the entire mass of material flows

without stagnation.2 1 11 Passive PrUSUTt ield - Field in which the major pressure ishorizontal or near horizonta Rules or rounding off numerical value. w.ued .

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IS 9 8 artIII 19802 2 Peaked Pressure ields - In peaked pressure fields major pressurelines f rom peaks at the centre of the bin, synonymous wrth activepressure in soil mechanics.2 3 Radial Pressure ield - Field which occurs in the lower part ofa hopper and in which pressures are proport ional to the distance from

the vertex of the hopper.2 4 Strain nergy - The energy of a flowing mass of solid whichcould be recovered by a re laxation of boundary forces and displacements.2 5 Switch - Region of change of an active pressure field towardsa passive pressure field.2 6 Transition o in t between the cylinder wall and the conicalflow channel in a funnel flow bin, In mass flow it is the joint betweencylinder and hopper.

standard the notations as given below shall= Mmor dimension of the outlet, m Major dimension of the outle t or length of the opening slot length , m Diameter of the opening of hopper, m Diameter of a circular cylinder, that is. dia of vertical,

portron of s torage system, width of rectangular Orsquare cylinder, m- Height of the cylinder, m

Coefficient, m 0 for wedge hopperm for conical hopper

Distance from the axis of symmetry. Bulk density of the solid, kg/m3

Area of horizontal section of a cylinder, S= Diameter of hopper, width of a hopper, m Unconfined yield force of bulk solid, kgf= Hydraulic radius = V Perimeter of the cross-section of the stored material, m Shearing force, kgf Janssen s pressure line Depth of the fill in the cyhnder, m Fnctional stress on the bin wall, kgf/ml Frictional stress on the hopper wall, kgf/ml

w

VS]

rmh

3 NOTATIONS3 1 For the purpose of thisapply:

bo10

6

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Asjifvr

wn

H O

IS 9178 ar t 198= Shear cell area cross-sectional area of the testsample), m2= Radius of curvature at transition

V= r = Flow factor of a channel hopper)= Major consolidating force kgf= Major force in a dome or a pipe bulk material underflow), kgf= Flow function of bulk material= Instantaneous flow function of bulk solid= Time flow function of bulk solid s tored for a period Ibefore delivery starts= Pressure normal to hopper or cylinder wall kgf m= Initial pressure on a hopper wall at the vertex kgfjml= Peak pressure at the transition kgf/m l= Initial pressure on a hopper wall at the transitionkgf/m2= Radial pressure on a hopper wall at the transitionkgf/m= Peak pressure at an effective transition kgf m2= Non-dimensional vert ical force act ing within a bulksolid at the level of the transition due to radial stressesin the hopper= Vertical force developed in cylinder walls due to wallfriction kg f= Pressure normal to cylinder wall. kgfjm= Total vertical force acting within the bulk solid at thelevel of transition due to stresses in the cylinder kgf= Effective yield locus of the How of bulk solid= Wall yield locus of the flow of bulk solids for a

particular hopper wall= Hopper slope measured from vertical deg= Conical hopper slope measured from vertical deg= Plane flow hopper slope measured from vertical. deg= Slope of flow channel with respect to vertical deg= A function depending on

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IS I 9178 P a r t111) - 1980G 1iiii

a

= Kinematic angle of internal Irrction of bulk solid, de g= A function depending upon r- Effective angle of wall friction of bulk solid on th ewalls of th e bin, de g= K in emat ic ang le of wall friction between bulk solid

an d wall of bin, de g Angle of friction between bulk solid an d hopper wall,

de g= A function depending on ii= Coefficient of friction between th e bulk solid an d th ecyLinder wall= Pressure ratio, that is, horizontal to vertical pressure= Pressure, kgfJm 2

4. DESIGN CONSIDERATIONS4.1 In th e design of bins for bulk s torage, th e tw o important considerations involved are:

a) flow characteristics, an db) load distrrbution characteristics of th e stored material.

.1.1 The now characteristics determine th e slope of the hopper portionof the bill an d the outlet dimeusions wlnch indrrecrlv lead to th e selecnonof shape an d Sl ze of th e bID. These are dealt wlth in detail n Section 2and Section 3 of t he c od e for mass ow an d funneL ow respectively.

4.1. 2 Load distrrbution characteristics give th e actual loading conduionon th e wal ls of the bm an d at th e ouuct, The-se govern th e structuraldesign of the bi n as well as th e selection of th e feeder system to be incorporated at th e outlet. This has b ee n d ea lt with n detai l in Section 4 ofth e code.

SECTION DESIGN FOR MASS FLOW5. GENERAL5.1 In mass flow, th e contents of the hopper move at all points an d slidingtakes place at the walls whenever an y solid is d raw n t hro ug h the outlet ofth e bin, Inactive or dead regIOns are absent th e stored mass. Massflow IS a gravlt) flow without any flow promoting device.

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Is t 9 78 I a r t tit) 95.2 Mass flow has the fallowing characteristics which guide the selectionof the design parameters:

a Channelling, hang-ups, surging an d flooding are absent,b Flow is uniform, an d steady state flow can be achieved closely,c Pressure throughout th e mass an d at th e walls is relatively low,which results in low consolidation or packing,d There ar e no dead regions within the bin; hence there isminimum of consolidanon at rest.e A first-in-first-out How pattern may be obtained, if desired This

useful in the storage of solids which either deteriorate With timeor segregate during chargingf By circulating a mixture around a suitable bin, blending may beattained.

5.3 Mass flow storage bins may be designed with a variety of hoppershapes listed below Fig. Ia Conical or pyramidal hoppers with circular or square outlet,b Chisel hoppers with rectangular outlet or slot,c Transition hopper with rectangular outlet,d Wedge hopper with full slot or rectangular outlet.

5.4 This standard covers the various hopper shapes given in 5.3 under thefollowing two distinct groups:a Conical channel with square or circular outlet,b Plane flow channel with rectangular or full slot outlet.

6. FACTORS INFLUENCING TH E DESIGN6.1 Flow Properties o f Stored Bulk Solids - Th e flow properties ofbulk solid stored the bi n is the principal factor affecting the design.These properties shall be determined under similar conditions of the bulkmass as It is stored in an d delivered by the bin being designed. Factorsaffecting the flow properties are as follows:

a Particle size an d shape,b Bulk density an d consolidation,c Moisture content,d Temperature,e Surface finish of bin walls, an df) Period of storage.The flow properties shall be determined after considering thesefactors in the actual storage conditions. The flow properties thus

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IS 9178 artIII 198determined will help in determining the outlet size the slope of hopperand the load distribution on the walls of the bin.

ZI- - - td

\110

rj ,

- lIi8 c

a Conical bl Pyramidal c Chisel

d

T IZ, Sp8e 8 10 .

d ransrtron e WedgeFIG. 1 HOPPER SHAPES FOR M ss FLOW BINS

6 lope o opper - For a good design the hopper slope angle shallbe so selected s 7.4 tha t the stored mass moves in a first-in-first-outfashion and each point of [he mass moves when flow starts. The bin shallfully clear itselfWithout any flow promoting device.10

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IS 9178 Part .19806 1 2 hdlet - For a satisfactory flow in a mass Row storage system, theoutlet shall be large enough s 7.5 so that plug flow piping anddoming do not occur and the flow continues without the aid of flow promoting devices.

6.2 Ul p Size - The flow is also influenced by lump size with respectto a certain outlet size. For uninterrupted flow, the outlet shall be designedfor an optimum lump size. Normally, the lumps are free flowing and aresuitable for mass flow.7. DESIGN PROCEDURE7.1 Design procedure involves the following stages:

a Collection of information about the stored bulk solids andthe wall material of the bin,b Determination of the flow properties of the bulk material to bestored,

c Estimation of the hopper slope 8,d Estimation of the size of outlet.

7.2 Collection of Information About th e Stored Bulk Solids andthe Wall Material of the Bin7.2.1 The size, unpacked bulk density aerated bulk density and thelump size if lumps are present of the powdered and granularsolid shall be determined.7.2.2 The condition of the bulk solid to be stored shall be conformed.This requires information about the moisture content and temperature ofthe bulk material of actual service and the time period for which the bulkmaterial is stored at rest in the bin.7.2.3 The wall material and its surface condition finish, lining finishshall be determined or the information shall be obtained from theprescribed specifications of the bin.

7.3 DeternUDatioD of the Flow Properties of Bulk Material7.3.1 The bulk materia l shall be tested on a shear tester flow factortester to obtain tdistribution curve with respect to major consolidatingforce V and flow function The test shall be done With the sample ofbulk material representing the actual material to be stored size,moisture content, time period, temperature, etc, shall be similar . The rdistr ibution with respect to various consolidation and wall yield lociwri shall be determined Appendix C .7.3.2 The values of shear cell area AB mean values of and a at theoutlet conditions shall be determined from the flow property data. shallbe estimated from WYL Fig. C-3 of Appendix C .

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IS *9178 Part III) 19807.4 E.timation of Hopper Slope Angle 9

7. 1.1 Flow factor .fJ corresponding to the assumed 8 and 8 valuesat outle t sha ll be e stim ated from the .fJ c ontours for c onica l and plane flowchannel Fig. C-1S to C-15 of A pp en di x C). helf values should beso selected that th e point , 0 ) IS very close to the extreme boundary.

7....2 shall be selec te d from Fig. C B of A pp en di x C such that thepoint 0 8 ) lies within the boundary of the selectedff for the case ofconical flow.1 .... 3 I n th e case of pla ne flow c ha nnels, 0]. shall be s el ect ed v er y closeto the left of t he d ot te d e xt re me b ou nd ar y. In the case of a smooth tran-sition zone transition from verticalportion of storage equipment to thehopper) wi th a ra di us of curvature Rt d 3 O may be increased by 5f rom t he optimum value selected earher.

7.5 Estimation of Outlet Size7.5.1 The e stim ated flow fac tor see 7....1) shall now be plotted

against flow function FF of the bulk solid FF is a plot of V and F withVas abscissa and F ordrnate, whereas i is the plot of Vand V with Vas ordinate, scale of and F being same for the plot.

7.5.2 6 ) c or re sp on du ig to the e st im at ed 6 for the selected shape ofoutlet IS determined from FJ j C-12 of Appendix C.

7.5.3 If there is no interse ction of.f with FF, and FF lies below if itshows that the material stored IS free flowing and any dimension of outletbased on the rate of discharge and l um p size s ha ll be sufficient. An outletsize bo = G (m.lximum lump xiz e ] or the size based on dischargewhichever IS gre ater sha ll be selec ted. The following relation yields thev al ue of [ at the outlet co ndi ti on:V ~ ~ H 0

When r so d et erm in ed is l ocat ed on .fJline, V at th e outlet is alsoobtained.7.5.4 lies above jJ, it means that the solid will not flow in a

channel w.th flow factor assumed. lflower values ofJfare available andif an intersection can be obtained, the new flow factor jf shall be selected.Based on this modified.o; the intersection point V V ) is noted.7.5.5 t he re is an i nt ers ecti on of ffwith FF, shows that the bin of a

particular slope outlet size can be desisne d for mass flow, The inter-s ect ion p oi nt V r ) is noted. e

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IS : 9178 Part III ) 19807.5.6 After plotting If over F Fo an d FF if It found that lhe,fflinelies between FF0 and FFt that J r I S above FF0 hu t below FF t the storedmaterial shows a tendency of consolidation wi t h time. In t he se c ases,

vibrators ar e specified, so rhat th e flow may be started, and th e outlet isdesigned with a factor of safety to allow for any unfavourable effect of

~ i b r a t i o n . This shall be accomplished by so selecting V that at outletV = 1 5 F.7.5.7 From 7.5.3 to 7.5.6 according to tile cas e f.tced in design V shallbe selected an d H 0 ) shall be revalued from Frg, C12 of Appendix C

if an y modification in ha s been done dunng th e location of V .7.5.8 Minimum outlet di rnensrons, ho shall be c al cu la te d f ro m th e

following formulab o = _ ~ - H O t.r, w

7.6 Check f o r E s ti m at ed Design Data7.6.1 Corresponding \ th e I value obtained under 7.5.3 to 7.5.6,S shall bc read from plot 0 an d I This v.iluc of Swill d etermine th e EYL

of th e stored rnass at outlet conditions.7.6.2 The Mohr s semicircle shall be d ra w n t hr ou gh V 0 ) such that

it shall be tangential to l The WY shall then be drawn over thisMohr s semicircle. The point of iniersecuon shall determine 8 at outlet.This should check w it h t he e st im at ed 0

7.6.3 f t he e st im at ed 0 does no t tally WIth th e c he ck v al ue of 5 , afurther estimation offf an d 0 shall be done, so that th e check value of 0is dosdy reached.7.7 Recalculation for Slope o f Hopper and Outlet Size o n B as is o fCorrected Data

7.7.1 The corrected values ofjJ, 0 and s hal l be noted an d t he correspending hopper slope) shall be obtamed from Fig C-13 to C-15 ofAppendix C. H ll ) shall be obtained from Fi g C-12 of Appendix C.V is obtained 111 t he m an ne r shown under 7.5.3 to 7.5.6. The outlet sizebo shall then be obtained according to 7.5.3.

7.7.2 A check is d on e o nc e again to ascertain the recalculated values ina similar wa y as shown in 7.6.1,7.6.2 an d 7.6.37.7.3 The check and recalculation shall be continued until corrected

and c he ck val ue s of are equal.

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IS: 9 78 Part III 19807.8 Adopted Values of Outlet Size aod Slope of Hopper for Des ign

7.8.1 The hopper slope angle shall be equal to or less than thecalculated values shall not exceed the calculated value in any case.7.8.2 In the case of conical hoppers or steep pyramidal hoppers, theoutlet shall be circular or square. The diameter of the circular outlet or

the side of the square outlet shall not be less than the calculated minimumdimension 7.8.3 In the case of plane flow hopper, the outlet shall be rectangularor full slot. In the case of rectangular opening, the small side shall notbe less than o Incase the stored solid contains lumps, the smaller sideshall be atleast four times preferably silt times the maximum lump size.The greater side of the rectangular outlet shall not be less than threetimes the smaller Side. In the case of full slot opening, the width of open-ing shall be greater than the calculated For lumpy stored solid, it shallalways be more than four times preferably six times the maximumlump size. The length of slot shall be at least six times the width of slot

lo> bo 7.8.4 A recommended calculation sheet is given in Appendix D for thedesign of bins for mass flow, including determination of outlet size andslope of hopper.

SECTION DESIGN FOR FUNNEL OR PLUG FLOW8. GENERAL8.1 In funnel flow plug flow . the hulk solid flows towards the outlet ofthe bin in a channel formed within the mass, while the mass around thechannel remains stationary s Fig. 2 . is a gravity flow without anyflow promoting devices.8.2 Funnel flow bins are used for storage when segregation is unimportantand there is no problem of deter iorauon with t ime of the stored material.Since there is ht tle wear in the hopper walls during service, this storagesystem is useful for the storage of hard, abrasive and lumpy solids.8 .3 Funnel flow bins Fig. 3 may be classified in the following types:a Flat, bottom bins without hopper,

b Bins with conical hopper, orc Bins with pyramidal hopper.

8.4 The shape of the outlet may be circular, square or rectangular.4

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S 9178 Part III 1980

DRAW MOSTLCOARSE DRAW SAMEAS CH RGEFIG 2 PLUG FLOW

\ \ \ I I I I

l FL T OTTOM lblCQNICAL e 1PYRAMIDALFIG 3 PLUG FLOW INS

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IS I 9178 Part III - 1989. FACTORS INFLUENCING DESIGN9.1 Flow Properties of Stored Bulk Solid - The flow properties ofbulk solids stored in th e bm is the principal factor affecting the design.These properties shall be determined under similar conditions of th e bulkmass as is stored in and delivered by the bin being designed.The factors affecting th e flow properties are as follows:

a Particle size and shape,b Bulk density and consolidation,c Moisture conient,d Temperature,e Surface finish of bin walls,f Time period of storage.The flow proper\les thus determined will help in arriving at th e

outlet size, th e slope hopper and the load distribution on the walls ofth e bin.

9 Outle - For a sausfactory flow in funnel flow bins, the outletsha ll be la rge enough so that pipmg and doming do no t occur and theflow continues WIthout any 11 w promoting device.9 2 Slope opper - The hopper slope shall be so selected that the

moving channel the mass attains a maximum possible size and there ISno possibihty of plpmg and doming.9.2 Lump Si: ;e - The flow is also influenced by lump size with respect a certain outlet size. For uninterrupted flow, the outlet shall bedesigned for an optimum lump size.10. DESIGN PROCEDURE10.1 Collection of Information about the Stored Bulk Material andWall Material of the Bin

10.1.1 The size, aerated bulk density and packed bulk density of thepowdered and granu lar solid shall be determined. The lump size iflumps are present shall a lso be determined.

10.1.2 The condiuon of the bulk solid to be stored shan be confirmed.This requires information about the moisture content and temperatureof the bulk material at actual service and the time period for which thebulk material is stored at rest in the bin.

10.1.3 The bin wall material and its surface condition finish, liningfinish shall be determined or the mfnrmauon shall be obtained from thespecification sheet of the bin.16

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IS 19178 ta r t ttl .110.2 Determination of the Flow Properties of Bulk Material

10.2.1 The bulk material shall be tested on a shear tester ( flow factortester to obtain \ distr ibution curve with respect to major consolidatingforce, and flow function FF. These tests shall be conducted with thesample of bulk material representing the actual material to be storedsize, moisture content, t ime period, temperature, etc, shall be similar .The r l dist ribution with respect to various consolidation shall also bedetermined see Appendix C ).10.2.2 The values for shear cell area As mean values of 8 and r l shallbe determined from the flow property data.

10.3 Determination of Hopper Slope Angle p10.3.1 Flow factor ff corresponding to the average 8 and shall befixed with reference to Fig. C-9 of Appendix C. The value offfshall notbe less than 1 7.10.3.2 Referring to Fig C-IO the hopper slope may be fixed corresponding to the average \ and the obtained under 10.3.1. The maximum9 values for conical and plane flow channels shown in Fig. C-IO ofAppendix C shall not be exceeded If doming is to be avoided.10.3.3 In the case of plane flow rectangular outlet hoppers, th eslope 91l shall always be more than 30 , \ is greater than 40 , whichrepresents the rnajonty of bulk solids. In the case of pyramidal hoppers,the slope angle refers to the valley angle.10.3.4 The conical channels for plug flow are usually very steep andthis leads to the adoption of flat bottom bins 10 place of a conicalchannel.

10.4 DeterlDination of Outlet Size10.4.1 The flow factor ff determined as per 10.3.1 plotted against theflow function FF of the bulk material. FF is a plot of V and F with Vasabscissa and F as ordinate, whereas ff is the plot of V and Vwith Vasordinate, scale of V and F being the same. The Intersection ofifwith FFyields a point ( V V .10.4.2 Functions G ( p and H ( a are evaluated from Fig. C-II andFig. C.12 respectively of Appendix C.10.4.3 the out let shape selected for design is square or circular , themajor dimension of the outlet will represent the side of square or diameterof circular opening. The major dimension, 10 for rectangular or do forcircular opening shall be calculated by the following formula:

10 or do = VG .pA w

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IS ,9178 Part III 198010.4.4 the outlet is rectangular in shape, the minor dimension bo ofthe outlet apart from the major dimension 1 shall be obtained to avoidany doming. bo is calculated by the following relation:

bo = V 6As w10.4.5 The dimension of the rectangular outlet is given by bo X The dimension 10 shall be so adopted that is always greater than threetimes

10.5 Adopted Valaes of Outlet Size aDd Slope ofHopper10.5.1 Adopted values for the outlet dimensions shall be larger thanthe calculated values to accommodate the uninterrupted flow of lumps

also. Thedimenslon of outlet shall be at least sill: times the diameterof thesize of lump being handled.la 5 2 Adopted slope of the hopper shall be equal to or smaller thanthe calculated value. t shall not exceed the calculated value in any case.

10.6 A recommended calculation sheet is given in Appendix E for thedesign of bin for funnel flow.SECTION 4 LOAD DISTRIBUTION FOR DESIGNOFBULK STORAGE NS

11. INITIAL AND FLOW PRESSURES11.1 The method of calculation is based on the principle of minimumrecoverable strain energy For full details of the concept and pressuredistribution, reference may be made to the papers Bin Loads Par t IIconcepts; Part II - Mass flow bins and Part IV - Funnel flow bins byA W lemke ] R. Johansen and] W Carson published n tne Journalof Engineering for Industry ofASME, February 9 8 There are certainlimitations of this theory as pointed out by different research workerswhich are outlined in Appendix A. The procedure for determiningpressure distribution as given in this section may be adopted subject tothese limitations. The loads which act on the bin walls are different during the initial stage of charge into a bin and during the flow stage from abin, because the deformations which the stored materials undergo duringthese two stages are different. In the initial stage when the bulk materialis charged into an empty bin with the discharge gate closed or the feederat rest, the bulk material settles down as the head of bulk material rises.During this process, the material contracts vertically in ,the cylinder asalso in the hopper. The major pressure tends to align with the directionof contraction of the bulk material. Hence. these initial pressures are closeto vertical throughout the bin thus forming a .. peaked pressure field.

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IS 9178 Part II I 1980This initial pressure corresponds to load calculated by Janssen s methodin the cylindrical part of the bin an d by a linear distribution inth e hopper. This assumes that th e bulk materials are not charged withsignificant impact and the bulk storage materials in powder form ar echarged at sufficiently low rate so that they deaerate. If granular bulkmaterials ar e to be dropped from some height th e bins have to bedesigned with safety fo r impact an d wear in impact areas. Powderymaterial when charged at high rate may develop close liquid pressures onth e walls. Also, it should be ensured that the storage materials ar e suffi.ciently free flowing without obstruction; otherwise, stable arches of th estored materials may form. When this arch collapses, a large amount ofbulk material falls an d induces dynamic loads in th e bin.11.2 When the gate is open or th e feeder is started th e stored materialstarts flowing out to th e outlet, an d in this case, a vertical expansion ofsolid takes place within th e flow channel. Th e minor pressures may tendto align with the direction of expansion of th e stored materia l. As a rule,th e flow channel diverges upwards from th e outlet. Hence, th e flawingmass of stored material also contracts laterally. Th e major pressures with.in th e flow channels tend to align with the lateral contractions. Hencemajor pressures are essentially lateral, minor ones are vertical an d thepressure field is arched.11.3 The region of switch from peaked to arched fields originates at theoutlet of th e b in w he n th e gate is first opened or the feeder is slarted an drapidly travels upwards into the bin as th e stored material is withdrawnfrom th e bin. At th e level of th e switch, th e equi librium of the massimposes a sharp overpressure on th e walls of the flow channels. Thisoverpressure travels upward with th e switch at least to th e level at whichth e channel intersects th e cylindrical part of the bin to the level of th etransition in mass flow bins an d effective transmission in th e case of funnelflow bins. In a cylinder, above a transition, experimental data indicatewide oscillation of low pressure with time an d this along with the peaksneed be predicted. This has been analysed as a strain energy, based onth e second law of thermodynamics an d the pressure distributions for th emass an d funnel flow bins are worked out .11.4 Th e procedure for load distr ibut ions suggested in this code ma y beapplied to bins designed for mass an d funnel flow.12. PROCEDURE FOR CALCULATION OF LOAD DISTRIBUTION

IN MASS FLOW BINS12.1 Initial Pressure12 1 1 Cylinder - Initial pressure Ph on the walls of cylinder is:

< ] l

19I

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IS 9 78 Part111 1980dand the hydraulic radius R = - - = - - - ~ - - , - - - - c 2 I + m

wherem = I for circular bin,

= 0 for long rectangular or square cylinder. andA = 0 4.

.oo (2)

I n the cylinder, the frictional stress lw is related to normal pressurePh by, (3)

.. . (4)

2 2 opper- The surcharge, due to the stored material in thecylinder. exerts a vertical load Qc ( see Fig, 4-) on the stored material ofthe hopper. This force becomes maximum when the cylinder wall pressureis minimum (Janssen s distribution ). This is given byQc wR [ =fi J-:4 = T I - eValues of ~ ~ 1 . - are plotted in Fig. 5.

The initial pressures perpendicular to the hopper wall are assumedto vary linearly from the apex to the transition, as shown in Fig. 4. Thevalue at the apex, Pnl is given byP w d

OJ = 2 tan 6 - + - t - a n ~ 8 ~ h )The initial pressure at the transition. n is given by

,.. (5)

2 +m(1+ m) tan II tan 6 + tan ... (6)The parameter m is 0 for long edged shape hopper and 1 for conicalhopper.The frictional stress / is related to normal pressure Po by

= Po tan ll ... (7)

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JS 9J Part III

d

\ II a

\\\

FIG INITI L PRESSURES IN A ONI L HOPPER

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II 9 7 Part UI 9o ~ ~ .

g oW N-

12 208 R

o

8

20

10 12

8

L hIRlclFIG 5 FUN TION ~ -w

2 2 Flow Presaures 2 2 ylinder - hepressures exerted by a mass of stored materialin a cylindrical vessel are governed by

a) Slight deviation in shape of the vessel from cylindrical, andb) t hin stable or unstable boundar y layers of solid which forms atthe wall of the cylinder.As a result, only bounds on wall pressures can be established.Janssen s formula nearly gives the lower bound and the upper bound iscalculated by the consideration of str ain ener gy of the mass of storedmaterial.An example of the loci of maximum cylinder pressure computedfrom strain energy and modified for the hopper effect is plotted in nOD-dimensional form hlwd )max in Fig. 6. These pressures are a functionof the distance from the top of cylinder a nd the product pl Janssenpressures are also plotted as a reference.

22

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1819178 ,PartlD

2IPhl .... ) m

SlR IN ENER:a, . . .-- : 0 011\ _:0 151 -020 \\ -olit,

1 J NSSEN : 011\ 4 0 2 5, of r 0-]7 SI' . ,- 0 50It ' ___ =0 7:; : IJ

o

e

I,jIII

.1

F I G . 6 a ) Phlwd lmal FO R CIRCULAR CYLINDERS, hId = 30F:: ------

\ ............................_o )IP lwd) I r\U

J N S S ~. - 0

)1,0 25,0 315050015

S T Q I ~ ENUGl}.lA,o 10

. 0 15: 0 20: 0 )0

dr

FrG. 6(b) Phlwd )wu. FO R CIRCULAR CYLINDERS, hId= 5Th e vertical force w caused by th e frictional stress twPh is computed from

Pw [ p ] wdSr = W d 1 m l X Ty pical results in non-dimensional form ( Pdw_a WBJ;te d in Fig. 7 for circular cylinders ,

and Pressure.. , (8)

are represen-

23

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o

i

l e- ~ i

ASEDONSTAINENERGV

I

I 1

/JA=Q3

~=OI

~=oo

2

3

(wfWdrn

BASEDaNSIRAN ,

oz

1

\

NA.

3

1

2

FNWdmi

,

,

,

l

o

I

\

FO7(a{wdmaFORCRLAR

CN

hd3

FG.7(bPw)maFORCRLAR

CLNDEhd

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IS 19178 rt III .1980 2 2 2 opp r - Flow pressure variation in a mass /low hopper consistsof a pressure peak at the transition, then a lmear decrease to anintermediate value and another linear decrease to zero at the apex s Fig. 8 .

o FlO 8 FLOW PRESSURE IN A CONICAL HOPP R

2 2 2 The radial pressure component at the transition isgiven byP t r .w r 9

Typical plots of as a function of eand are given in Fig. 9and Fig. 10 for conical channels and symmetr ic p lane flow channelsrespectively.

25

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JI.9178 Part III 198

20 30et GR S 0

3 0 . . . ~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .I 0 ~ 2 0 k = = ~ ~ J LIJJ0::eo 10s:] 0

I 30II IIIJIIJQ:C) 200 .cco

10

loS min VAlUE

< , , . . . . . . . . , r - ~ T I - - - n - - T - -

t c ~ ~ r = f : ~ ~ ~ H/)20UJ 1- :: -1h 0o . l o k - = ~ ~ ~ - - - - - = : : : : : t : = - ~ j . . . L ~ - ls:IC

tFlO. 10(a) wB CONTOURS FOR SYMMETRIC PLANE FLOW CHANNELS. = 30028

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Is 9 8 t-art ll

1/1 20 p o ~ - - - . = . . . . . . . .ao

50 60p.DEGREES FlO. 10 b CONTOURS FOR SYMMETRIC P LA NE F LO W CHANNEL Il = 40

50

10 20 8 p.DEGREES

1FIG. lO c w COr .TOURS FOR SYMME1RIC P LA NE F LO W C HA NN EL Ii = 5 29

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IS 9178 Part 1980

60 ,....---...,....--r T ...,.-,, It --...,....--- ;-----,

so I - - - - - l - - - - - I - - - - - - - - - \ - - - \ - t \ - - - \ - - \ - ~ - - - t - - - - t

40 SL e = oJ 30wIXCQ 20J::1

10 20 30 40 p GR S

FIO.lO(d) w CONTOURS FOR SYMMETRIC PLANE FLOWCIIANNEL, 3 = 61 0

30

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S 9178 Part III 1918

600

1~ ~ wB IwB

500 W l r ~ 1 2

J i w ~ 01Q:UJ0 .s 300 - - ] r O 5 : - 0 - - : : : : . . . . . . . . . - - - - 1 f \ - - - - - ~oJoJ oJ 0.10.c.

FIG. 12 a) P, CONTOURS FOR SYMMETRIC PLANE FLOW CHANNELS 3 = 3033

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IS I 9J18 ( rt in . J980

20 30e p O E G R E E S

0358o

r l 2 ~ - ~ + - - , - - ; - - - ~ - - - f - ; ; : - - ~ - + - - ~ ; : t - - - - - : ~ - i:c

FIG. 12(b) r CONTOURS FOR SYMMETRIC PLANE-FLOW CHANNELS, = 5 :--_:-1 ---.::c-r_,.._........, ; _ _ . .

40

t 30r l0::I 200 sItO

1

I : q ~O O 10 2 JO 40 5 60

8 p GR S FIG 12(c) CONTOURS FOR SYMMETRIC PLANE-FLOW CHANNELS, 0=50

34

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IS 9178 Part III 198012.3 Appendix F may be referred to for a typical procedure for theapplication of th e above-mentioned met hod for calculating loaddistribution in mass flow bins13. PROCEDURE FOR CALCULATING THE LOADDISTRIBUTION IN FUNNEL FLOW BINS13 1 In tall funnel flow bins, th e flow pressures are larger than th e initialJanssen s pressure. Hence, for design purposes flow pressures have to beused. Fig. 13 shows the general bin configuration an d some of the usefulvariables.

JANSSEN

o

d

r

LOCUS OFPEAK PRESSURE

OWEST LOCAl-. -;-.- --j ON OFEFFECTIVETRANSITION

FI G. 13 FUNNEL F LO W B IN PRESSURES

13. 2 Cylinder - The loci of lwd )max th e maximum non-dimensionalhori zonta l wall pressures exerted by a mass of stored materials on th ewalls of a vertical cylinder ar e drawn in Fig. 14 for different i ratioswith as y-axis, These pressures ar e a function of the h ei gh t f rom thetop of the cylinder an d the product rA A value of 0 4 is t ak en for .\.13.2.1 The equations on the basis of which the figures for differentvalues of i may be drawn are given in clauses 13.2.2 to 13. 2.4.

N O T E - For a h ei ght to diameter ratio less than 2. It rs suggested that] an senequation may be used, for the flow channel seldom intersect. the cylmder wall. 5

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IS 9178 rt III 1980

1/

I

ju A= 002 010wO20 0'30

1 2 3 4( f 'h wdl , . .

FlO. 14 a b wd mox FOR CIRCULAR CYLINDERS, hid 2

I aII

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FG.1ePhwd)mFORCIRCULAR

CYLNDEShd4

I> ~ =-4

)J00

,0O

0

= =2

:

c~=030

I

I

}r1

r

>

Pfdma

DK

I

Phwd)maFORCIRCULAR

CYLNDEShd=5

2 5

r

o

I

I

I

d LFG1d

d IX,00

,00

=1

1

=2=03

2

3

L1111

I

o

,lPwdn

31

fj

O z d l

d w

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S 9178 Part III 198013.2.2 Figure 15 shows the equilibrium at an effective transition.

Assuming that the ratio of horizon ta l to vertical pressure at aneffective transiuon, .\1 is equal that ratio m the radial stress field, lowerin the conical channel, the peak pressure at an effective transitionis given byu k [ - e , Z ]PI = 1 I ll,.,.

1 - f p.\ 0 /\ e //,9 \1/

FlO. 15 EQUILIBRIUM AT AN EFFECTIVE TRANSITION13.2.3 Considering the radial stress field, .\ is to be determined as givenin Eq. 12) after establishing

a) a re la tionship be tween T and h assuming that the wall of theflow channel to be a velocity characteristic, andb) a relationsh ip between T and Pr

\ = 24 tan 0 + 1r1 Pr 1 - sin 8 . tan 6 ) (12) 16 ( sin 8 + tan 6 ) ..Value of Pr and 6 as function of 8 can be determined. y taking.\ = A PI can be calculated from Eq (11).

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IS .9178 Part III .1980A-2. Arching just below th e transition is frequently reported 3 . Thisdoes no t seem ro cover that.A-3. Actual stresses close to the transition z on e b et we en parallel part ofth e silo a nd t he hopper section deviate strongly from those predicted byt he r ad ia l theory 1 .A-4. t does no t adequately allow fo r th e impact loading which oftenoccurs on filling and can easily cause arching 3) . This is believed to be amajor reason for th e discontinuity of flow that commonly occurs inb un kers d esig ned b ased on ]enike s method.A5. Jenike s shear cell which is th e main tool in finding ou t t he designparameters of the bul k mat er ia ls used in t hi s t he or y which ha s beendescribed in Appendix A of th e draft code) could be used only in th ecase of sa mpl es w it h pa rt ic le s to p size of only about 1-6 mm and issubjected to th e foHowing Jimuations 4) .A.5.1 The limited shear displacement available makes necessary a ratherarbitrary an d laborious preparation of th e s am pl e p ri or to th e shearconsolidation.A5.2 To obtain design data for hoppers with outlets less than about1 metre across requires knowledge of material characteristics at majorprincipal stresses of less than 70 k m At the low normal loads requiredfor this, llftinR or pivoting of th e cell lid , assocrated with non-uniformstress distribuuon becomes nouccable.A.S.3 The tensrle strength of material ma y b e measu red in t he a nn ul arshear celI designed by Walker and Carr 5 instead of a split Jenike-typeceU as recommended by Ashton, Farley an d Valentin 6 .A.S.4 Professor Schwedes 7 points out that in th e flow factor tester ofJenike, t he s ta te of stress c an no t b e d et er mm ed completely an d assumpnons regarding th e positions of slip planes are necessary to e va lu at e t hetest results.A.G. Other r es ea rc h w or k h as b ee n in progress an d the relevant referencesar e included 8 .Conclusions: The theories presented by Walkar 9 , Walkers 10.12 an dEnstad I) are meant t cover t he l im it at io ns of Jemke s

t he or y b ut they ar e approximate a fact also pointed out byth e authors themselves.Reference to th e work done by Doc kse n I 3) m ay bemade for th e precautions that have to be observed while

designing th e bIDS.

40

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IS : 911 l art til ) . 198PPEN IX B

( l use 0.9 )RECOMMENDED LITERATURE FOR REFERENCE

1. Enstad O n the theory of arching in mass flow hoppers Chemical Engineering SCience, 1975, Vol. 30,pp . 1273-1283.2. Molerus, a and AuslegungsdiagrammeSchoneborn, Chemie-Ing-Techn, Ed.P. R. S.741/45.

fur Schuttgutbunker43 1971), Nr. 13,3.

4.

6.

8.

9.

10.

Wright, H

Walker, MCarr,]. F.an d Walker, MAshton, M. D.Farely, R . ValenunF . H . H .Schwedes, J.Proposed, ACIStandard

Walker, D. M

Walters, J. K

An evaluation of the ]enike Bunker designMethod Transactions of ASME, Journal of Engg.for Industry, Feb. 1973, pp. 4B-54.A basis for unker design , Powder Technology,1 1967), pp. 228-236.I An annular shear celt for granula r materials ,Powder Technology, I 19b7/6B , pp. 369-373., An improved apparatus for measuring th e tensilestrength of powders ; ]ournal of Scienufic Instrument41 ( 1961 ), pp 763-755., Measui ement of powder properties for HopperDesign , Trans. of ASME, Journal of Ep gg forindustry, Feb. ~ 7 3 pp. 5559Commentary on Recommended Practice forDesign an d Construction of Concrete Bins,Silos an d Bunkers for Storing Granular MaterialsAC I Journal, Title No. 72-38, pp . 550, Oct. IY75., An approximate theory for pressures an d archingin hoppers Chemical Engineering Science, 1966,21, pg. 975. theoretical analysis of stresses in silos withvertical walls , Chemical Engineering Science,Bd. 2B ( 1973), NT I, pp. 13-21.

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18 J 9 78 Part DI 198Walters, J. K. A theoretical analysis of stresses in axiallysymmetric hoppers an d bunkers; Chemical EngineeringScience, Bd. 28 1973 ) Nr. 3, pp. 779/89.

12. Walters,J K. A note on the stress distribution at great depth inand Neederman, silo , C hemic al Enginee ring Science, Vol. 28R. M. 1973) Nr. 5, pp. 1907/8.13. Doeksen, G. Precautions in order to attain design capabilitiesor Mass-flow system , Journal of En gin ee rin g forIndustry, Transactions of ASME, Feb. 1973;

pp.93-96.Bunker Design-Transactions of ASME Journal ofEngmeering for Industries November 1977 byAmerical Society or Mechanical Engineers Pages809 to 827 )Part I Bunker outlet design an d initial measurem ent of wall pressures by PC RichardsPart W al l pressure in mass flowPart III Wall pressure an d flow patterns in funnelflowPart IV Recommendations

PPEN IX C lause 7 3 )

PROCEDURE FOR TESTING OF FLOW PROPERTIESOF BULK SOLIDSCol. The tests for determination of flow properties ar e performed on th eflow factor tester which consists or a shear cell with cover an d arrangement for applying normal an d shearing load on th e sample packed in th eshear cell. The nor ma l load is a pplied through the hange r an d weightsan d th e sh ea ring load is applied gradually by an advancing screw stemoperated by elec tric m oto r, causing a stem d is pla ce me nt of 0 9 mm/min,Th e she ar loa d is measured by a proving ring placed between the screwstem an d shear cell see Fig. C-I a)].

The inside diameter or sh ea r cell is 63 m m, a nd t he height is 38 mm,which yields th e shear cell area,A 0 003 12 m 2

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15 9178 art 191NORMAL LOAD

Pl ANE OF SHEAROF AREA As

S H E A ~ l f r G = ; ; ; : : ; : : : ; = n f ~ - ~ 4 - L _ 4I..LOAD

RING

SE

FRAME

/

a Shear CellMAJORCDNSOLIDAT I VN FORCE ,

MOULD

RING SE

FRAME

b Preconsolidation of a Shear Cell

FILLERFRAME

SAMPLE OFWALL MATERIAL

NORMALLOAD

OVER

~ : : : ; = = l - - - l l - - - - - L ~ RING

STEM

SHEARINGLOAD u J4l -\-_-- -_----.J.u-----

c Measurement of the Kinematic ngle of Frict ion Between Bulk Solidand Wall MaterialFIG. C.l DETERMINATION OF TH E FLOW PROPERTIES USING

A FLOW- FACTOR TESTER43

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9 8 Part t8C-l. l Shear cell which is the main tool in finding out the design parameters of the bulk materials used in this theory could be used only in thecase of samples w ith particle top size of I 6 C-2. Bulk density of the aerated bulk m aterial is determined without anypacking. Thereafter the bulk densities of packed bulk solids shall bere corded as further tests proceed under various consolidating loads.Typical curves giving bulk density at different consolidating loadsare given in Fig. C-2 for gypsum, trl ple su pe rp ho sp ha te and pulverisedcoal. Sim ilar curves should be drawn for the ma te ria l to be s tor ed.C-3. The bulk solid to be tested is placed in the cell set-up shown inFIg. C ol b) for preconsolidation One la yer a ft er a no th er is p ac ke d up tothe top of the mould and excess material is scraped off. The twisting topis placed over the p ac ke d solid. A no rma l loa d is a pp li ed on the top withthe help of hanger and weights. A number of oscillating twists areapplied to the top by means of a special wrench. This completes thepreconsolidation.C4. The load applied for preconsolidation is rem oved and the twistingto p and the m ould is rem oved with precaution SI that the b as e and ringof the s he ar cell are not disturbed. T he excess ma ter ial over the r in g isscraped ofT lever with the to p of ring. The test cover is placed over thematerial and the consolidation load is applied to the cover. The screwstem shearing device is advanced against the bracket so that the shearof the laver of m aterial starts. The s he ar l oa d a tt ai ns a st ea dy m ax im umvalue for a certain consolidation normal load. This completes theconsolidation and shear yielding of the bulk solid. The values of normalloa ds and s he ar l oa d are recorded.C-5. The shearing of the material is done at various normal loads underthe same consolidation. This is do ne by consolidating the test sam plefollowing the same pr oc edu re as u nd er C \ s he ar in g until 95 p er ce nt ofthe m ax im um s he ar in g force as o bt ai ne d under C-4 is reached. At thisp oint , the n or ma l c onsolidation load is r epla ce d by sma ll er n or ma l l oa dsfor f ur th er s he ar in g of the sample. The ma ximum steady she ar forcevalues thus obtained shall be recorded.C 6 Yield locus shall be plotted by locating various normal loadsvs shear load values for a particular consolidation load. A number ofsui ta ble c onsolidation loads selected shall yield a family of yield loci.Mo hr s circles, when drawn yield major consolidating force andunconfined yield force, F These plots shall also give kinem atic angle ofinternal friction and effective angle of friction of the bulk solid.C 7 Plots of Wall Yield Locus - The s he ar cell shall be arranged asshown in Fig. Col c). The sa mple of wall m at er ia l is pla ce d as the b ase ,representing the a ctu al m at er ia l and surface condition of the bin

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8 9 78 Part 98

f0- oL

,.,-

- \ . o 9 : l ~l L ~ ~ ~ f fo- f--- - I .....

/ sn EL SAMPLE LATHE MA ,HINED MEDIUM FINISH -COAL SIZE. -200 MESHt> C O N D I ; O ~ lOR; I I I I r72 3 4 S 6NORMAL lOAD, Vn. J... t 8 9 10

- Similar charts for various other materials should be drawn.F l o . C 3 WALL YIELD Locus ( COAL ON STRUCTURAL STEEL)

V ~ R Y VkRY I.

POOR Fl

V E R V POOR F 0L W

I P P a R f 0IPASSABLE F l WIFAIR F. L 0r- GOOD F lL 0 WEXCElL- oENT 0 Wl W W W0 0, ,2S )0 )S 0 5 50 ss 60 65 10 15 80 85 9

so

>- 35:;iii 30w 25

20

l 1

ANGLE OF REPOSE. DEGREES FlO. G ANGLE OF REPOSE VERSUS COMPRESSIBILITY( PACKED BULK DENSITY - AERATED BULK DENSITY)

PACKED BULK DENSITY

46

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IS 9 78 Part m1910

:l/ \ yQ ?lY h_>cO . L / ~ : 2 l ~ ~ ~ vi ; -tft- IfE - - - , - 1 - - -en - r/ (j- , , ~ D- - - - - 1 - - - _ D \ S ~

f/ l J vtz e--0 ~ 170 7 t/ FF DRY SAND0 o Po

CONSOLIDATING FORCE V, k t

FIG. C-5 SOLID FLoW FUNCTION F F AND HOPPER FLOW FACTORfj

w...llI:o

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HOP

SOPANGL8D

-A . J iP: -=-

I . U

O LA

.f-W

\

,

l

1

I

I

r

I-

, I r r r

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IS 9178 Part III - 1

FIG C if FLOW FACTOR FOR No PIPING

9

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18 19178 art III 98

C6 0 ~ - + - - I - - - - - - - ~ : - - - : - ' L - - t - - - - t - - - + - - - + ~ - + - - - l

f - - - + - + - ~ - - + - - : o o I . : - - - - + - - F I o O O : : : + - - + - - - - 1

=1 8f t _

If = 4

IG C lO ff ONTOURS FOR OMING IN PLUG LOW

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IS 19178 rt III -1980

4

/II

V V

230 40 50 60 70KINEMATIC ANGLE OF INTERNALFRICTION OF BULK souo e DEGREES

FIG l UN TION G ( )

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IS.9178 Part IU .1980

I1 r . \ ~ C I J ~ IP SO\l... t lo--

l l ~ lbnl~ E C l N G U l ~ 0 I I

5

1 00 10 200 30 40HOPPER SLOPE e DEGREE

FIG. C12 FUNCTION H ll)

25

30

20 3D D 50Ge DEGREES -

FlO. C-13 a ffCONTOURS FOR CONICAL CHANNELS, ~ =

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[S : 9178 Part II I - 1980

200 309c GR S