Hopper Design Indian Standard

इंटरनेट

मानक

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“The Right to Information, The Right to Live”

“Step Out From the Old to the New”

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Jawaharlal Nehru

IS 9178-3 (1980): Criteria for Design of Steel Bins for Storage of Bulk Materials, Part 3: Bins Designed for Mass Flow and Funnel Flow [CED 7: Structural Engineering and structural sections]

“!ान $ एक न' भारत का +नम-ण” Satyanarayan Gangaram Pitroda

“Invent a New India Using Knowledge”

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“Knowledge is such a treasure which cannot be stolen”

IS : 9178 (Part III ) -1980

Reaffirmed 2010

Indian Standard CRITERIA FOR DESIGN OF STEEL BINS FOR STORAGE OF BULK MATERIALS PART 111 BINS DESIGNED FOR MASS FLOW AND FUNNEL FLOW

© Copyright 1982 I N D I AN S T A N D A R D S I N S T I T U T I O N MANAK

BHAVAN, 9 BAHADUR SHAH ZAFAR MARG N E W DELHI 110002 January 1982

Is : 9178 ( Part III ) • 1980

Indian Standard CRITERIA FOR DESIGN OF STEEL BINS FOR STORAGE OF BULK MATERIALS PART III

BINS DESIGNED FOR MASS FLOW AND FUNNEL FLOW

Structural Engineermg Sectional Committee, SMllDC 7 Chairman

Repr;se"llng Mimstry of Railways

DIRECTOI: Sl'ANIJARDS ( CIVIT, )

A[""bers

R. i\f AGAR'VAL DIt Puuv KurSUN ~ SUIH A K IlAXLltJEI'.

Insriturion of Engineer' ( Inrha }, Calcutta

SnRI

(

Alternal. ) Metallurgic d and Engrncerrng l India) Ltel, Ranchi

Consultants

Sum S. SA"KARAN (Allerrral' ) Slim P. G. ihnDIIAN Brauhw.ntc & Co Lt,l, Ca lcutra :::. HI":::' K t; ,,,COPAllIlY, Y (Altemale ) SlIIlI S, N BASU Inspccuon Wing, Drrecrorate General of Supplies ami D.'pm"h, New Delln SII'" D Il I ~1'1 (AIJ,mal' ) Sru.t P. C JIll 1"'1 Mrmsrrv ofS!Jippilll'; -md Transport (Department ut I'rnnvpor-t ) ( Road, WIIII'; ) DIt 1'. N CIH'." L" TEl" Government 01 W"'tBengal DR P D,YA"A I '1A" Indr.m Institute of Technology, Kanpur i:>lilti D S 1\1. N. Dastur & Co PH Ltd, Calcutta

J)""

:::'1I1 d13, OJ' may be increased by 5° from the optimum value selected earher. 7.5 Estimation of Outlet Size 7.5.1 The estimated flow factor if (see 7.... 1) shall now be plotted against flow function FF of the bulk solid FF is a plot of V and F with Vas abscissa and F a~ ordrnate, whereas if is the plot of Vand V with V as ordinate, scale of (' and F being same for the plot.

7.5.2 II ( 6 ) corresponduig to the estimated 6 for the selected shape of outlet IS determined from FJ!j C-12 of Appendix C. 7.5.3 If there is no intersection of.f! with FF, and FF lies below if, it shows that the material stored IS free flowing and any dimension of outlet based on the rate of discharge and lump size shall be sufficient. An outlet size bo = G ;~ (m.lximum lump xiz e ] or the size based on discharge whichever IS greater shall be selected. The following relation yields the value of [' at the outlet condition:

V ~ ~o_w A~ -

When obtained.

r so determined

H (0)

is located on .fJline, V at the outlet is also

7.5.4 If FF lies above jJ, it means that the solid will not flow in a channel w.th flow factor assumed. lflower values ofJfare available and if 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 If there is an intersection of ffwith FF, it shows that the bin of a particular slope an~ outlet size can be desisned for mass flow, The intere section point ( V, r ) is noted.

IS : 9178 ( Part III ) • 1980 7.5.6 After plotting If over FFo and FF, if It I~ found that lhe,ffline lies between FF0 and FF t , that 1~, JrIS above FF 0 hut below FF t • the stored material shows a tendency of consolidation wit h time. In these cases, vibrators are specified, so rhat the flow may be started, and the outlet is designed with a factor of safety to allow for any unfavourable effect of ~ibration. This shall be accomplished by so selecting V that at outlet V = 1'5 F. 7.5.7 From 7.5.3 to 7.5.6 according to tile case f.tced in design V shall be selected and H (0) shall be revalued from Frg, C·12 of Appendix C if any modification in 11 has been done dunng the location of ( V, V). 7.5.8 Minimum outlet di rnensrons, ho shall be calculated from the following formula'

bo=_~,-H(Ot

.r, w

7.6 Check for Estimated Design Data the I' value obtained under 7.5.3 to 7.5.6, S shall bc read from plot 0 and I', This v.iluc of Swill determine the EYL of the stored rnass at outlet conditions.

7.6.1 Corresponding

\0

7.6.2 The Mohr's semicircle shall be drawn through ( V, 0 ) such that it shall be tangential to ElL The WYL shall then be drawn over this Mohr's semicircle. The point of iniersecuon shall determine 8' at outlet. This should check with the estimated 0', 7.6.3 If the estimated 0' does not tally WIth the check value of 5', a further estimation offf and 0' shall be done, so that the check value of 0' is dosdy reached.

7.7 Recalculation for Slope of Hopper and Outlet Size on Basis of Corrected Data 7.7.1 The corrected values ofjJ, 0 and o' shall be noted and the correspending 11 ( hopper slope) shall be obtamed from Fig C-13 to C-15 of Appendix C. H ( ll) shall be obtained from Fig C-12 of Appendix C. V is obtained 111 the manner shown under 7.5.3 to 7.5.6. The outlet size bo shall then be obtained according to 7.5.3.

7.7.2 A check is done once again to ascertain the recalculated values in a similar way as shown in 7.6.1,7.6.2 and 7.6.3 7.7.3 The check and recalculation shall be continued until corrected and check values of o' are equal.

13

IS: 91'78 ( Part III ) • 1980

7.8 Adopted Values of Outlet Size aod Slope of Hopper for Design 7.8.1 The hopper slope angle shall be equal to or less than the calculated values It shall not exceed the calculated value in any case. 7.8.2 In the case of conical hoppers or steep pyramidal hoppers, the outlet 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 minimum dimension boo 7.8.3 In the case of plane flow hopper, the outlet shall be rectangular or full slot. In the case of rectangular opening, the small side shall not be less than bo Incase the stored solid contains lumps, the smaller side shall be atleast four times ( preferably silt times) the maximum lump size. The greater side of the rectangular outlet shall not be less than three times the smaller Side. In the case of full slot opening, the width of opening shall be greater than the calculated boo For lumpy stored solid, it shall always be more than four times (preferably six times) the maximum lump size. The length of slot shall be at least six times the width of slot (lo>6b o l . 7.8.4 A recommended calculation sheet is given in Appendix D for the design of bins for mass flow, including determination of outlet size and slope of hopper.

SECTION 3 DESIGN FOR FUNNEL OR PLUG FLOW 8. GENERAL 8.1 In funnel flow ( plug flow). the hulk solid flows towards the outlet of the bin in a channel formed within the mass, while the mass around the channel remains stationary ( see Fig. 2). It is a gravity flow without any flow promoting devices. 8.2 Funnel flow bins are used for storage when segregation is unimportant and there is no problem of deteriorauon with time of the stored material. Since there is httle wear in the hopper walls during service, this storage system 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, or c) Bins with pyramidal hopper. 8.4 The shape of the outlet may be circular, square or rectangular.

14

IS: 9178 ( Part III ) • 1980

DRAW MOSTL¥ COARSE

2

FIG

\

PLUG FLOW

I

\

I

\

\

I

DRAW SAME AS CHARGE

I \

I

I I

I

I

\

"

/

la) FLAT BOTTOM

lblCQNICAL FIG. 3

PLUG FLOW BINS

15

(e 1PYRAMIDAL

IS I 9178 ( Part III ) - 1980 9. FACTORS INFLUENCING DESIGN 9.1 Flow Properties of Stored Bulk Solid - The flow properties of bulk solids stored in the bm is the principal factor affecting the design. These properties shall be determined under similar conditions of the bulk mass as It is stored in and delivered by the bin being designed. The factors affecting the flow properties are as follows: a) Particle size and shape, b) Bulk density and consolidation, c) Moisture coni ent, d) Temperature, e) Surface finish of bin walls, f) Time period of storage. The flow proper\les thus determined will help in arriving at the outlet size, the slope 01 hopper and the load distribution on the walls of the bin.

9.1.1 Outle: - For a sausfactory flow in funnel flow bins, the outlet shall be large enough so that pipmg and doming do not occur and the flow continues WIthout any 110w promoting device. 9.1.2 Slope oj Hopper - The hopper slope shall be so selected that the moving channel 01 the mass attains a maximum possible size and there IS no 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 be designed for an optimum lump size.

10

10. DESIGN PROCEDURE 10.1 Collection of Information about the Stored Bulk Material and Wall Material of the Bin 10.1.1 The size, aerated bulk density and packed bulk density of the powdered and granular solid shall be determined. The lump size ( if lumps are present) shall also 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 temperature of the bulk material at actual service and the time period for which the bulk material is stored at rest in the bin. 10.1.3 The bin wall material and its surface condition (finish, lining finish) shall be determined or the mfnrmauon shall be obtained from the specification sheet of the bin.

16

IS 19178 (tart ttl) .1... 10.2 Determination of the Flow Properties of Bulk Material 10.2.1 The bulk material shall be tested on a shear tester ( flow factor tester) to obtain 1\ distribution curve with respect to major consolidating force, V, and flow function FF. These tests shall be conducted with the sample of bulk material representing the actual material to be stored (size, moisture content, time period, temperature, etc, shall be similar). The r/l distribution with respect to various consolidation shall also be determined (see Appendix C ). 10.2.2 The values for shear cell area As, mean values of 8 and r/l shall be determined from the flow property data. 10.3 Determination of Hopper Slope Angle

.p

10.3.1 Flow factor (ff) corresponding to the average 8 and

o

-

,.~

sn EL SAMPLE

V 2

I

I 9

r10

- Similar charts for various other materials should be drawn.

Flo. C-3

so

'l!~~

",.,-

~ .....

I

V ./

f-- fo- f---

NOT~

oL

...

WALL YIELD

V~RY

Locus ( COAL

ON STRUCTURAL STEEL) .

I

VkRY

F

POOR

l

VE R V

POOR

F

0

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>- 35

....

:;

iii 30

~

w

I

P

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~

~

P

a

R

PASSABLE

20

~

15

l'

10

0

F

l

W

L

0

0

W

I

. r- GOOD FAIR

EXCElLENT

FlOW

0

f

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,

0,

2S'

F

F L

0 W )0'

l

o W )S·

W '0'

'5"

50'

ss"

60'

65"

10'

15'

80'

ANGLE OF REPOSE. DEGREES ~---

FlO. G-4 ANGLE OF REPOSE VERSUS COMPRESSIBILITY ( PACKED BULK DENSITY - AERATED BULK DENSITY) PACKED BULK DENSITY

46

85" 9

IS I 9178 (Part

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CONSOLIDATING FORCE, V, k g t -

FIG. C-5

SOLID FLoW FUNCTION FF AND HOPPER FLOW FACTORfj

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III

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