Detailed lecture on grain storage by Chitesh kumar. Department of processing and food engineering, Punjab Agricultural University, Ludhiana

1. Grain Storage Systems
Submitted by : Chitesh Kumar
Department of processing and food engineering
Punjab Agricultural university

2. Why are storage structures needed?
2
• Pro te c t io n o f fo o d g ra in s f ro m u n c e rta in we at h e r.
• S to ra ge o f a n ima l fo d d e r a n d fe e d s, fe rt ilize rs , se e d s , ve geta b le s, fo o d
g ra in s, milk a n d milk p ro d u c t s etc .
• Fo r sto ra ge o f b u ffe r sto c k to su sta in h u ma n a n d a n ima l p o p u lat io n .
• Re d u c e p o st h a r ve st lo sse s
 (It is re p o rte d t h at mo re t h a n 1 0 % o f fo o d g ra in s a n d 3 5 % o f f ru it s a n d
ve geta b le s a re lo st in p o st h a r ve st h a n d lin g ).

3. For safe and scientific storage following points should
be remembered.
3
• Si te s e l e cti on : t h e site sh o u ld b e c h o se n in su c h a way t h at a ll ye a r ro u n d it
is mo ist u re f re e .
• Storage Stru ctu re : S to ra ge st ru c t u re sh o u ld b e c h o se n by ke e p in g in min d
t h at t h e sto ra ge ca p a c it y a n d d u rat io n o f g ra in sto ra ge .
• Cl e an i n g an d F u m i gati on : S to ra ge st ru c t u re sh o u ld b e co n st ru c te d in su c h a
way t h at c le a n in g o f sto ra ge st ru c t u re a n d f u migat io n is e a sy.

4. Cont..
4
• Aeration: The ventilation should be proper in storage
facility. Aeration helps in minimizing the moisture of
grains.

5. Cont..
• Inspection: Structure should be built or constructed such that
anyone can make regular inspection of grain stock without any
hassle.

6. Bag storage
• This method consists of storing dried and cleaned grains in woven/plastic bags and
neatly storing them in prepared areas.
• It is adopted in developed as well as developing countries.
• It is economic and well adopted to local transport and market conditions.

7. Cont…
• The bags of grain can be stacked out-of-doors under covers, or placed inside
storehouses, sheds or warehouses.
• Sometimes, especially for seeds, grain is stored in bags in refrigerated warehouses.

8. Permanent bag storage:
• Conventional godowns with tubular truss.
• Structures with portal frames.
• Godowns with shell roof.

9. Semi-permanent bag storage:
• Storage structures with Galvanised Iron (GI) sheet cladding with
tubular trusses, sheet roofing.

10. Temporary bag storage:
• The word ‘CAP’ is used for cover and plinth,
• Plinth from the bottom and cover from the top.
• This type of open storage is considered as transit storage and serves
the purposes of storage of food grains in bags for short period.

11. Cover and plinth

12. Layout of stacks inside godowns
Bags can be stacked with different
patterns to provide proper
strength, aeration and
Space for the movement of
machinery and
people in godowns.

13. Cont..
• They must be stored on pallets
• Bags must be placed such that bags are interlocked stabled
• If individual pallets are used maximum 8 layers are recommended
• Enough room must be left between stacks and walls

14. Layout of stack for larger platforms
• For larger platforms no of layers
can be increased upto 10.
• More than 27 per of space can be
freed up for inspection and
movement of machinery.

15. Design considerations of warehouses
The following points to be considered during design of godowns:
• Generally are of 5000 Tonnes capacity,
Having 3 compartments of 21.7m Long and 5.4m clear height.
• Steel ventilators for aeration are must.
• There should be 2.4*2.4m size two large doors in opposite directions.

16. Cont..
• Each door is provided with large
overhanging hood of 3.6m*2.4m.
• Each ventilator of 30*30 cm is
provided with wire netting.
• The thickness of wall is kept between 37.5 cm and 45 cm.

17. Cont.
• The floor of the storehouse must prevent rising damp. A water proof
layer can be put under the cement flooring.
• The height of wall on which trusses are placed is generally kept about
5.5 m.
• Materials used for side walls can be of brick or stone masonry and for
sloped roofing (CGI) Corrugated Galvanized Iron sheets over steel
trusses.

18. Types of bags used for bag storage
Jute bags
• They are available in 25-100 kg capacities
• They can be used with or without inside
plastic lining
• They are mostly used for short term storage

19. Bags for grain storage
PP woven Bags
• PP woven bags are very much moisture resistant
• In PP woven bags rains can be stored a
little longer than jute bags
• They are also available in 25-100 kg capacities

20. Bags for grain storage
Plastic/Hermetic bags
• They are available in 5-50kg capacities
• They create a low oxygen Modified atmosphere inside
which reduced the infestation problems and increase
the shelf life of the product.
• Properly designed hermetic storage is highly
rodent resistant.

21. Cocoon Storage with Co2 purging

22. Comparative effectiveness of GrainPro
Cocoon with traditional storage
• The mortality of all tested insects increased with increase in storage
period.
• After 5 days of storage mortality increased significantly and kept
increasing even after 15 days storage.
• The results of the present study suggest that Grainpro Cocoon was
the most effective hermetic storage structure to control all types of
insects for extended storage period.

23. Question:
• Prepare a design and layout of a bag storage structure for storing 96
tonnes of paddy
Solution:
No of Bags?
*assuming 75kg of paddy can be stored in one bag
no of bags required will be = 96000/75
=1280 bags
For 10+6 stacking arrangement, there are 10 bags width wise and 6
bags length wise

24. • And if there are 8 rows in 1 layer while alternating the bags width wise and
length wise
then no of bags in 1 layer will be = 6*4+10*4 = 64 bags in 1 layer
assuming there are total 5 layers in 1 stack = 64*5
=320 bags in 1 Stack
then no of stacks required are = 1280/320= 4 stacks are required

25. For 10+6 Arrangement

26. Size of stack?
Length of stack (L) = length of bag*no of rows with bags length wise
= 100*4=400cm= 4m
Width of stack (W) = width of bag * no of bags width wise along stack
width
= 60*10=600cm=6m
Height of stack = height of bag*no of layers= 30*5 = 150cm = 1.5m

27. Clear distance between walls and end of
stack (a) = 0.8m
Clear distance between stacks (b)= 2.0m
By arranging the stack as shown in fig:-

28. • if N is the no of stacks made widthwise along length of godown and
M is the no of stacks kept length wise along width
Lg =(N*W)+(2*a)+(N-1)b
=(2*6)+(2*0.8)+(2-1)2=15.6m Length
Wg=(M*L)+(2*a)+(M-1)b
=(2*4)+(2*0.8)+(2-1)2 = 11.6m width
Hg=H+2 (2m free space for ventilation) = 1.5+2= 2.7m

29. Storage Structures on Farms
29

30. Grain Storage
30
Gr a i n a r e g e n e r a l ly s t o r e d i n b a g s o r i n b u l k . Ho we v e r t h e r e i s a l s o a s y s t e m
o f b a g -c u m-b ulk - sto ra g e .
Th r e e ma i n t y p e s o f s t o r a g e s t r u ctu r es f o r s t o r a ge o f g r a i n a r e -
1 . Tr a d i t io n al s tor a ge s t r u c tu re s
2 . I mp r o v e d s t o r a g e s t r u ctu re s
3 . Mo d e r n s t o ra g e s t r u c tur e s

31. Traditional storage structures:
31
Th e s e t y p e s o f s t o r a g e s tru ctu re s g e n e ra lly h a v e c a p a c i tie s
b e t we e n 1 -5 0 t o n e s . Di ff e r e n t t y p e s i n c l ud e s:-
1 . Mo r a i t y p e s t o r a g e s t r u ctu re s
2 . Bu k h a r i t y p e s t o ra g e s t r u c tur e s
3 . Ko t h a r t y p e s t o r ag e s t r u c tu re
4 . Mu d Ko t h i t y p e s t o r a g e s t r u c tur e
5 . Mu d a t y p e s t o r a ge s t r u c tu re
6 . Ka n a j t y p e s t o r a g e s t r u c tur e
7 . Ku t h l a t y p e s t o r a ge s t r u ctu re
8 . Me t a l / St e e l b i n t y p e s t o ra g e s t r u c tur e
9 . Ba g t y p e s t o r a g e s t r u ctu re

32. Bukhari type storage structure:
32
• Gr a i n s : - Wh e at, Pa d d y , g r a m, So rg h u m
• Ca p a c i t y : 3 .5 -1 8t
• Cy l i n d ric a l i n s h a p e .
• M a d e o f mu d o r c o mb i na tion o f mu d a n d
b a mb o o .
• Ra i s e d a b o v e b y wo o d ma s o n r y p l a t fo rm.

33. Kothar Type Storage structure
33
• Gr a i n s : - Pa d dy, M a i z e , So rg h u m , Wh e a t .
• Ca p a c i t y : 9 - 3 5 t
• Sh a p e : Bo x Ty p e
• No g a p b e t we e n p l a n k s

34. Bag type storage structure
34
• Ca p a c i t y : 2 5 -5 0 0 t .
• Ge n e r a l l y t h e l e n g t h o f b u i l din g i s
t wi c e t h e wi d t h .
• En t i r e s t r u ctu re h a s t o b e wa t e r p r o o f
• Do o r s i z e s h o u l d b e l a rg e .
• Ve n t i l a to rs wi t h wi r e n e t tin gs a r e
i m p o rta n t.
• To e n s u r e t h a t f l o o r i s d a mp p r o o f , i t i s
ma d e u p o f 6 d i ff e r e nt l a y e r s o f
ma t e r ia ls.

35. Improved storage structures:
35
• I n t h i s t y p e o f s t o r ag e s t r u c tu re s t h e r e a r e s o me i mp r o v e me nts
ma d e i n t r a d ition al s tor a ge s t r uc tu re s.
• Th e y h a v e h i g h e r s t o r ag e c a p a c i t y a n d c a n s t o r e f o r r e l a t ive ly
l o n g e r t i me .
• Ca p a c i t y v a r i e s f r om 1 .5 -1 5 0 t o n e s .

36. The improved storage structures are:
36
P u s a B i n :
I t i s l i k e o t h e r t r a d i t i o n a l s t o r a g e s t r u c t u r e s m a d e o f m u d . H o w e v e r t o m a k e t h i s
s t r o n g e r s t r u c t u r e m o i s t u r e p r o o f p l a s t i c f i l m i s u s e d i n a l l t h e i n n e r s i d e s o f b i n .
B r i c k a n d c e m e n t b i n :
Ve r y s t r o n g a n d e ff e c t o f w e a t h e r i s m i n i m u m . .
B u n k e r s t o r a g e : I t i s u s e d t o s t o r e l a rg e v o l u m e o f g r a i n s f o r l o n g p e r i o d
C A P s t o r a g e s t r u c t u re s :
C A P - C o v e r a n d p l i n t h , P l i n t h f r o m b o t t o m a n d c o v e r f r o m t o p . H e r e g r a i n s a r e
s t o r e d i n o p e n a r e a f o r a s h o r t t i m e .

37. Modern Storage Structures
37
Si l o s
Si l o s/Bi n s a r e c l a s sifie d i n t o t wo g r o u p s
d e p e n d i n g u p o n t h e r e l a t ive d i me n sion o f the
c o n t a i ne r.
Th e y a r e c l a s s ifie d a s
Sh a l l o w Bi n s :
A g r a i n b i n i s r e f e r r e d t o a s a s h a l l ow b i n
wh e n t h e d e p t h o f g r a i n i s l e s s o r e q u a l t o
t h e e q u i v a le nt d i a me t er.

38. Modern Storage Structures
38
De e p Bi n s :
A g r a i n b i n r e f e r r e d t o a s a d e e p b i n wh e n
t h e d e p t h o f g r a i n i s g r e a t e r t h a n t h e
e q u i v a le nt d ia me te r.
Th e e q u i v a le n t d i a me te r is t a k e n a s f o u r
t i me s t h e h y d r a u lic r a d i u s o f t h e b i n .
Hd > 4 R ,.
Wh e r e Hd i s d e p t h o f g r a i n
R= Hy d r a u l i c r a d i u s
( Ar e a o f c r o s s s e c t io n/Pe r imete r o f b i n )

39. Modern Storage Structures
39
Ho r i z o n t a l s h e d s :
Th e y a r e u s e d t o p r o v i d e lo w c o s t , La rg e
v o l u me s t o r a g e .
A t y p ic a l b u l k wa r e h o u s e o f ( 6 0 x 1 5 x 6 )
s i z e wo u l d h a v e a s t o r a g e c a p a c i t y o f
2 ,8 4 0 t o n n e s .
Th e s a me s i z e b u i ld ing f o r b a g s t o r a ge h a s
o n l y 1 4 4 0 t o n n e s s t o r a g e c a p a c i t y

40. 40
Silos for grain storage

41. Silos :- Bulk storage
41
• Generally silos are used for granular products, animal fodder , milk and milk products etc
• Stored fodder is known as silage.
• They are generally circular in cross section, though square or rectangular cross sections are
commonly adopted for shallow bins.

42. Advantages of silo over warehouses
42
• Very large storage capacities >=50K tonnes
• Low running cost
• Low labour requirement.
• Lower losses from spillage and rodents
• Easy fumigation.
• Good aeration for long time.

43. Types of silos
43
Silos
Tower silos Horizontal silos
Pit silos Trench silos Surface silos

44. Tower silos
44
• Also known as permanent silos
• They are generally made of metal/wooden or concrete walls.
• Material is loaded my mechanical means.
• Wall has to be smooth so that material can settle down easily.
• It is mostly used in areas with high water tables.

45. Shallow and deep bins
45

46. Tower silos
46
1) Shallow bins 2)Deep bins
Relative dimensions effects the plane of ruptures of shallow and deep bins
.

47. Definations for shallow bins and deep bins
47
Shallow Bins Deep Bins
1) h < L tan
90+∅
2
1) ℎ > 𝐿𝐿 𝑡𝑡𝑡𝑡𝑡𝑡
90+∅
2
2) ℎ ≤ 4𝑅𝑅 2) ℎ > 4𝑅𝑅
• h= height of silo
• L= base length of the bin
• R= Hydraulic radius
• ∅= angle of repose

48. Horizontal silo with concrete lining
48

49. Horizontal silos
49
• They are Cheap and temporary or permanent.
• They can be easily filled without equipment.
• Lining is important to prevent water from entering.
• Stored silage should be levelled and packed
• After filling upto the ground level they should be covered with paddy straw or plastic covers.

50. Pit and trench silo
50

51. Pit and trench silo
51
• Both silos are lined all along the sides and bottom to prevent the
water from entering.
• They can be made of bricks or concrete.
• A simple roof over the silo can be provided to protect the silage from
sun and rain

52. Surface silo
52

53. Question:-
53
Work out the economical diameter and depth of a silo to
store sufficient quantity of silage for a herd of 300 dairy cows having
an average body weight of 450 kg each. The cows fed with silage for
200 days /year.
No. cows - 300
Body weight - 450 kg
No of days per year - 200 days /year.

54. 54
Let -
i) 1m3 of silage = 650kg.
ii) Thickness of silage fed per day = 10 cm/day.
iii) Let each cow I fed 3kg of silage per 100 kg of the body weight.
Weight of silage required for each cow = (3/100) X 450
= 13.5 kg / day
Weight of silage required for 300 cows = 13.5 X 300
= 4050 kg / day
Volume of silage required to be stored = 4050/650
= 6.23 m3

55. 55
Allowing 20 % loss,
Actual volume of silage = 6.23 + (0.2x6.23) = 7.476 m3
Volume of pit for a daily withdrawal depth of 10 cm = π/4 (d*d) X 0.1
7.476 m3 = π /4 (d*d) X 0.1
d (diameter) = 10 m
Depth of the silo = daily depth x no. of days = 0.1 x 200 = 20 m
Depth of the silo = 20 m

56. Grain Presure Theories
56
• The silos walls are subjected to two main forces or thrusts -
1)The horizontal thrust due to loading of material which tries to open up the silo
2)The vertical pressure which is generated due to loading of material on the walls.
The grain pressure theories are very important part of silo design consideration.

57. Forces on walls of silos
57
• Horizontal force is maximum at the bottom of the silo and opening up the cylinder even when it is held
together with uniform no. of rubber strips.

58. Cont..
58
So the solution will be to
concentrate the maximum no
of bands at the bottom where
the the pressure is maximum.

59. 59
• Considering an element of grain at depth 'h'. The vertical pressure acting
on this element 𝑃𝑃𝑣𝑣 and the horizontal pressure 𝑃𝑃𝑙𝑙.
Cont..

60. Rankine’s Theory –
60
The lateral pressure inside a shallow
bin is given by :
𝑃𝑃𝑙𝑙 = 𝑤𝑤𝑤𝑤𝑤 = 𝑤𝑤𝑤
1 − 𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠
1 + 𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠
Where,ℎ → 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑 𝑜𝑜𝑜𝑜 𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔
𝜃𝜃 → 𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎 𝑜𝑜𝑜𝑜 𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖
𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓 𝑜𝑜𝑜𝑜 𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔
𝑤𝑤 → 𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤 𝑜𝑜𝑜𝑜 𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔
𝐾𝐾 → 𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑒𝑒′
𝑠𝑠 𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐
𝐾𝐾 =
𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙 𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝
𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣 𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝
=
𝑃𝑃𝑙𝑙
𝑃𝑃𝑣𝑣
=
1 − 𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠
1 + 𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠
𝑊𝑊𝑊𝑊𝑊𝑊𝑊, angle of internal friction = angle of repose
𝑃𝑃𝑙𝑙 = 𝑤𝑤𝑤𝑤𝑤 = 𝑤𝑤𝑤
1 − 𝑠𝑠𝑠𝑠𝑠𝑠𝑠
1 + 𝑠𝑠𝑠𝑠𝑠𝑠𝑠
Where,
∅ → 𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎 𝑜𝑜𝑜𝑜 𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟 𝑜𝑜𝑜𝑜 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚.

61. Airy Theory –
61
The lateral pressure exerted by
grains in a shallow bin is given by:
𝑃𝑃𝑙𝑙
= 𝑤𝑤𝑤
1
𝜇𝜇 𝜇𝜇 + 𝜇𝜇′ + (1 + 𝜇𝜇2)
2
Where,
𝑤𝑤 → 𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔 𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑
ℎ → 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑 𝑜𝑜𝑜𝑜 𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔 𝑡𝑡𝑡𝑡 𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝 𝑢𝑢𝑢𝑢𝑢𝑢𝑢𝑢𝑢𝑢 𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐
𝜇𝜇 → 𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐 𝑜𝑜𝑜𝑜 𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓 𝑜𝑜𝑜𝑜 𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔 𝑜𝑜𝑜𝑜 𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔
𝜇𝜇 = 𝑡𝑡𝑡𝑡𝑡𝑡𝑡
Where, ∅ → 𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎 𝑜𝑜𝑜𝑜 𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖 𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓
𝜇𝜇′
= 𝑡𝑡𝑡𝑡𝑡𝑡∅′
Where, ∅′ → 𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎 𝑜𝑜𝑜𝑜 𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤 𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓

62. Jensen Theory -
62
The lateral pressure inside a silo
may be expressed as:
𝑃𝑃𝑙𝑙 =
𝑤𝑤𝑤𝑤
𝜇𝜇
1 − 𝑒𝑒−
𝑘𝑘𝑘𝑘𝑘
𝑅𝑅
Where,
𝑃𝑃𝑙𝑙 → 𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙 𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝
𝑅𝑅 → ℎ𝑦𝑦𝑦𝑦𝑦𝑦𝑦𝑦𝑦𝑦𝑦𝑦𝑦𝑦𝑦𝑦 𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟
𝑤𝑤 → 𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔 𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑
𝜇𝜇 →
𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐 𝑜𝑜𝑜𝑜 𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓
𝑜𝑜𝑜𝑜 𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔 𝑜𝑜𝑜𝑜 𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤
ℎ → 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑 𝑜𝑜𝑜𝑜 𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔.

63. Question:-
63
A cylindrical grain storage bin has internal diameter of 5 m and is 20 m deep.
It is completely filled with paddy weighing 600 kg/m3.
The angle of internal friction for paddy can be taken as 35, while the angle of
friction between paddy and bin wall is 30°.
The ratio of horizontal and vertical pressure intensity k, is 0.4.
Calculate the lateral pressure intensity at 4.0 m and 18 m depth using Janssen
theory

64. Cont..
64
• Pl = lateral pressure
• w = grain bulk density (unit weight of
grain) = 600 kg/m3
• R = hydraulic radius =D/4 = 5/4 =
1.25 m
• µ = coefficient of friction of the grain on
the wall
• = tan Φ= tan 300 = 0.577
• K= Pl/PV = 0.4
• h = depth of grain = 4.0 m and 18 m
Substituting the values of 4.0 m and 18.0 m
depths in above equation, we get

65. References
65
• http://ecoursesonline.iasri.res.in/course/view.php?id=23
• http://ecoursesonline.iasri.res.in/mod/page/view.php?id=623
• Patty, R. L., "Pit and Trench Silos" (1927). Cooperative Extension Circulars: 1917-1950. Paper 263.
• http://ecoursesonline.iasri.res.in/mod/page/view.php?id=918
• A Text Book Unit Operations of Agricultural Processing by K.M Sahay and K.K.Singh
• Sinha, R.N & Muir. Grain Storage: Part of a System. Avi Publisher.
• Ansari Irfan Ahmad 2018, Solved Numerical Problems in Food Process Engineering and Technology, Second
edition, Jain Brothers, New Delhi, India

66. References
• DSE: Lesson 40. Storage Of Cereal Grains (iasri.res.in)
• Villers P., NavarroS., Bruin T. De, Development of Hermetic Storage
Technology in Sealed Flexible Storage Structures, CAF 2008
Conference Paper
• Muhammad Noor ul Ane et all, Comparative effectiveness of
GrainPro CocoonTM with traditional storage systems against
Tribolium castaneum (Hbst.), Rhyzopertha dominica (F.) and Sitophilus
oryzae (L.) pp 2-7
• DSE: Lession-39 Design of Warehouses (Shed) and Control of
Environment (iasri.res.in)
• Villers P,Navarro S, Development of Hermetic Storage Technology in
Sealed Flexible Storage Structures, CAF 2008 Conference Paper,pp 4

67. 67
THANK YOU