Drying and Dryer

Grain Drying and Dryers

Bio-oriented Technology Research Advancement Institution (BRAIN)Institute of Agricultural Machinery (IAM)

Yasuyuki HIDAKA

Agricultural Mechanization for Sustainable Farming System Course 2004

Introduction of IAM 1Introduction of IAM 1Japan

Saitama

Tokyo

Ibaraki

TochigiGunma

Chiba

Kanagawa

Head office

museum

Show room

Introduction of IAM 2Introduction of IAM 2Fundamental Technology Department

Crop Production Machinery and System Department

Horticultural Engineering Department

Animal Industry Engineering Department

Testing and Evaluation Department

Introduction of IAM 3Introduction of IAM 3Testing and Evaluation Department

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Harvester Test

Transplanter Test

Tractor Test

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Boom sprayer test

Safety Test

National Test

Introduction of IAM 4Introduction of IAM 4

Certificate for safety test

Certificate for national test

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http://brain.naro.affrc.go.jp/iam/

Situation of Situation of Post Harvest Post Harvest in Japan 1in Japan 1

Harvest 　Moisture content 25 ％

DryMoisture content 　 15 ％

Transporting to dryer within 4 hours

Artificial Drying 　92 ％

Drying facility 　30 ％

Natural Drying

Japanese farmer controlled paddy by moisture contents.

Husk

Individual 62 ％


Storage

Distribute

Rough Rice

Brown Rice

Brown Rice

Brown Rice

Milling Factory

Country Elevator

Individual Farmer

Governmental ,JA and Private company’s Warehouse

Distribute


0

2

4

6

8

10

12

14

16

18

0 10 20 30 40 50 60 70 80 90 100 110 120 130

Storage period　（ｈours）

Co

lore

d g

rain

by

mic

roo

rga

nis

m　

（％）

(Toyama pref. Agri. Tech. Center, 1997)


-15

-10

-5

0

5

10

15

20

25

30

35

1 2 3 4 5 6 7 8 9 10 11 12

Manth

Temperature　(℃)

Harvesting period

Temperature Precipitation

70

90

110

130

150

170

190

210

230

1 2 3 4 5 6 7 8 9 10 11 12

ManthPrecipitation　

mm

（）

Harvesting period

We need artificial drying.

We have a lot of precipitation in harvesting period.

Temperature is low in harvesting period.

5%

10%

15%

20%

25%

30%

10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Relative humidity

Eq

uili

bri

um

mo

istu

re c

on

ten

ts (

w.b

.)

10℃

30℃

20℃

Average temperature and humidity range in harvest time of Japan

Equilibrium moisture content (paddy rice)

Situation of Post Harvest in Japan 5Situation of Post Harvest in Japan 5

Grain DryingGrain Drying Calculate amount of remove waterCalculate amount of remove water

Air properties on psychrometric chartAir properties on psychrometric chart

Relationship between temperature andRelationship between temperature and

humidity in thick grain layerhumidity in thick grain layer

Calculate amount of air and heat Calculate amount of air and heat energy using psychrometric chartenergy using psychrometric chart

Drying and qualityDrying and quality

We can know the drying energy by calculating the amount of remove water.

Calculate Amount of Remove WaterCalculate Amount of Remove Water

Weight of dry matter before drying ＝ Weight of dry matter after drying

　 Total weight（ W ）

　 Total weight（ W’ ）

Dry matter Moisture Dry matter Moisture

Before drying After drying

Mi % Mg %

W× （ 1-Mi/100 ）

W’ ＝（ 1-Mi/100)

（ 1-Mg/100)W ×

Amount of remove water ＝ W - W’

W’× （ 1-Mg/100)＝

Ww: Weight of remove waterW：Weight of grainMi： Initial moisture contentMg： Goal moisture content

Mg)-(100

Mi)-(100w WWW ＝

Conclusion

Equation

Practice

Q.1 　 Calculate amount of remove water when 3000kg paddy (M.C.27%) was dried to 15%.

W = 3000kg

Mi = 27%

Mg = 15%

WW ＝（ 100-Mi)

（ 100-Mg)W ×W －

（ 100 － 27)

（ 100 － 15)3000 ×　 3000 －＝

＝ 3000 　－　 2576

＝ 424 　 kg

In this case, We must remove 424 kg water.

Dry bulb temp. （℃）

Wet bulb temp.（℃）

Rel

ativ

e h

um

idit

y（％）

Ab

so

lute

hu

mid

ity（

kg/kg’）

Dew point temp （℃）

Enthalpy（kcal/kg’） S

atu

rati

on

lin

e

Specific volume（ｍ 3/kg）

Property of Moist Air on Psychrometric Chart

Dry bulb Wet bulb

Enthal

py

Relative humidity (%)

Dry bulb temperature (℃ ）

Wet

bul

b te

mpe

ratu

re

(℃）

Specific volume

Ab

so

lute

hu

mid

ity

(k

g/k

g’)

Psychrometric Chart

Grain layer

t2 ：Temperatureh2 ： Humidity

t1 ： Temperatureh1 ： Humidity

Air-inlet

t1 t2>

h1 h2<

Relationship between temperature and humidity on thick layer

Air-outlet

Dry bulb temp. （℃）R

elat

ive

hum

idity

（％）

Abs

olut

e hu

mid

ity（

kg/kg’）

h1

％

t2

h2 ％

H1

t1

H2

Relationship between temperature and humidity on psychrometric chart

(H2-H1)Capacity of absorbable water per 1 kg-air

Humidity is increase when air passes grain layer

Drying process

t1 ℃h1 ％

Grain layer

t2 ℃

t3 ℃h2

％

BurnerFan

A Model of Heated Air Drying

In this case, How dose sate point of air changeon psychrometric chart?

Dry bulb temp.（℃）

Rel

ativ

e h

um

idit

y（％）

Enthalp

y（kc

al/kg’）

t1 t2

H1

H2

e2

e1

(e2-

e1)

t3

e3

e4Eva

poratio

n late

nt hea

t

Ab

solu

te h

um

idit

y（

kg/k

g’）

ｒSpecific volume （ m3/kg ）

Relationship between temperature and humidity on psychrometric chart 　 in a model

(H2-H1)

h1h2

Capacity of absorbable water per 1 kg-air

Heat e

nergy

require

d for d

ryin

g

Heating process

Drying process

Ｇ (kg) = Ww÷(H2-H1)

Ｑ (m3) = Ｇ ×r

ｑ (kcal) = G×(e2-e1)

Equation of Amount of Air

Equation of Heat Energy

Conclusion about Drying

Drying Simulation 1

20℃70 ％

25℃ 、 75％

42℃

Weight ： 500kgM.C. ： 24 ％

Grain layer

The grain which weight is 500kg dried from 24% to 15% of moisture contents after 8hours.

Q.1 Calculate amount of remove water.

Drying Simulation 2

＝500 – 500 ×（ 1-0.24 ）（ 1-0.15 ）

We must evaporate 52.8kg water. And we must evaporate 6.6kg per 1hour because drying time 8 hours.

52.8 ÷ 8 = 6.6 （ kg/h)

52.8kg

W = 500kg

Mi = 24%

Mg = 15%

WW ＝（ 100-Mi)

（ 100-Mg)W ×W －

Dry bulb temp. （℃）R

elat

ive

hu

mid

ity（％）

Absolute humidity （ kg/kg’）

Enthal

py（kc

al/k

g’）

Specific volume（ｍ 3/kg）

70％

20 4275

％

0.0102

0.0149

16.1

11

0.0047

0.908

5.1

25

Drying Simulation 3Q.2 Read 　 differences of absolute humidity and enthalpy from psychrometric chart.

Drying Simulation 4

Q.3 Calculate amount of air.

Ｇ = Ww÷(H2-H1)

Ｑ = Ｇ ×r

= 1404×0.908

= 1275 (m3/h)

= 0.354 (m3/sec)

= 6.6 ÷ 0.0047

= 1404 (kg/h)

Drying Simulation 5Q.4 Calculate heat energy.

ｑ = G×(e2-e1)

The kerosene that heat combustion is 10500kcal/kg, is used for fuel.

7523 (kcal/h) ÷10500 （ kcal/kg) = 0.72 (kg/h)

0.72 (kg/h) 　 × 　 8 （ hours) = 5.76 (kg)

In this case, we need 5.76kg kerosene.

= 1404×5.1

= 7523 (kcal/h)

Relationship between palatability and germination

Drying & Quality 1

Relationship between cracking rate of brown rice and percentage of broken of milled rice

Drying & Quality 2

Relationship among Initial moisture content and drying air temperature and drop in germination rate.

Drying & Quality 3

Relationship among Initial moisture content and drying air temperature and serious cracking rate.

Drying & Quality 4

Relationship among Initial moisture content and drying rateand serious cracking rate.

Drying & Quality 5

Relationship among air flow rate and drying rateand serious cracking rate.

Drying & Quality 6

Initial moisture content

Dry air temperature

Drying rate

high low

low high

low high

Conclusion about quality

GrainGrain 　　 DryersDryers

Classification grain Classification grain dryersdryers

Batch type dryersBatch type dryers Continuous type dryersContinuous type dryers Storage type dryersStorage type dryers

Fixed temperatureRising temperature

Descending temperature

Ambient airDehumidification air

Heated air

No heated

air

Air flow rate per 1t

(m3/s・t)Drying 0.5-3

Bin drying 0.05-0.2Storage 0.02-0.002

Classification grain dryers 1Classification grain dryers 11.Classification by Aeration temperature

2.Classification by air flow rate

Structure Description Schematic diagram

Flat bed type

The drier which makes itprinciple to dry without

moving grain. Aventilation floor is

horizontal.

Upright type

A basic principle is thesame as the above. But

ventilation floor isvertical. When moisture ishigh, grain may be moved

several times usingthrower

Recirculationtype

While grain is drying,grain is always circulating.

Grain is drying andtempering per 1 cycle.

Uni pass type

While grain is flowingcontinuously from

entrance to exit, grain isdrying.Grain is dried to

goal moisture contents byone pass.

Multi pass type

A basic principle is thesame as the above. Grainis dried to goal moisturecontents by several pass.Grain is storaged in silobetween drying and next

drying.

Grain moving

Static

Batchtype

Moving

Continuoustype

3.Cassification by structure

Classification grain dryers 2Classification grain dryers 2

Grain dryers Grain dryers in facility in facility

(a) Country elevator

(b) Rice center

Continuous type dryer

Batch type dryer

high weight high weight high weightcm kg cm kg cm kg

1.7㎡ 41 370 43 390 45 4203.3㎡ 38 690 40 730 42 7505㎡ 36 980 37 1000 35 960

8.6㎡ 34 1200 31 1100 20 1000Note）a. Paddy density is 550kg/m3 b. Blower power is 0.37kW

Amountof grain

fordryingarea

Blower diameter 48cm 38～35cm 35～32cm

Flat bed type dryer

Moisture contents meter

Electric Resistance type

Grain inlet (front)

Fuel tank

Control panel

Burner

Bucket elevator

Tempering section

Drying section

Suction blower

Feed inlet (side)

Upper screw

Feed roll

Sensor roll

Recirculating type dryer 1

Burner

Suction blower

Grain

Exhaust air

Heated air

Heated air

Exhaust air

Under screw Rotary valve



Heated　air

Ambient　air

Heated air dryer

Grain

Far　-infrared　radiation

Far -infrared radiation dryer

Burner

Radiation body

Burner

Ambient　air

Heated　air

Grain

Suction　fun

Suction　fun


Drying　Chamber

Under　Screw(U.　S.)

FIR　Body

Rotary　Valve(R.　V.)

Drying　Chamber


FIR　Body


DryingChamber

FIR　body

Heated　Air

Exhaust　Air

FIR



DryingChamber

FIR　body

Heated　Air

Exhaust　Air

FIR




Round type (for soy beam)

Large type (for facility)

(a) Columnar type (c) Inverted trough type(LSU)

(b) Buffle type

Flow of grain Flow of grain

Heated

air

Heated

air

Heated

air

Heated air tube

Exhaust air tube

Continuous flow type dryer 1

Exhaust air

Exhaust air

Drying chamber

Blower

Dumper

Air inlet

Burner

Grain inlet

Exhaust air

(a) Columnar type

(b) Buffle type

(c) Inverted trough type

Brower

Grain inlet

Drying chamber

Exhaust air duct

Air inlet

Leveler

Exh

aust

air

Rotary valve

Heated air tubeExhaust air tube

heat

ed a

ir d

uct

heated air

Continuous flow type dryer 2

Grain inlet

Burner

Suction Blower

The limit safe air flow rate in storage drying

Storage type dryer

Grain

Air flow Sweep floor

Direction of grain moving

Storage type dryer 1 Square bin type

Storage type dryer 2 Round bin type

　

Tank

Receipt

Blower

Lift

Container rack

Balance

Power supply

Control box

Storage type dryer 3

Rack type

Storage type dryer 4

Mixing husk type

Paddy tank

Husk silo Mixing silo

Husk separatorHusk dryer

(2-3%wb)

Husk tank

Raw paddy

Paddy tank

Husk siloHusk silo Mixing siloMixing silo

Husk separatorHusk separatorHusk dryer

Husk

Dried paddy To husk silo

(2-3%wb)

Storage silo Husk tank

From husk dryer

Raw paddy

Mixing ratio Raw paddy : Dried husk = 1 : 1.5 ～ 2

Storage type dryer 5Storage type using solar energy

Solar energy

Green houseReceiving section

Processing section

Rotary stirrer

Drying bed

Bin Bin

Measurement methodMeasurement method

Moisture contentMoisture content　　①① Standard methodStandard method　　②② Moisture meterMoisture meter

CrackCrack

Grain Coefficient

Paddy 1.0121

Weat 1.0086

Barley 1.0086

Beer 1.0071

Brawn rice 1.0122

Milled rice 1.0133

M105 ＝ 100 － α （ 100-

M135 ）

Moisture content 1

Moisture contents (% w.b.) =Before drying weight － After drying weight

Before drying weight

Drying conditions

M105 : 5g(ground grain) － 105 ℃ － 5 hours

M135 : 10g(whole grain) － 135 ℃ － 24 hours

-0.6

-0.4

-0.2

0

0.2

0.4

0.002 0.008 0.014 0.020 0.026

Absolute humidity (kg/kg‘)

Dev

iati

on

5g(ground grain)-105 -5hours℃

4g(whole grain)-135 -24hours℃

×100

①Measure 10g of grain and put into an aluminum can.

②Remove the cover downward and puts it into a

dryer (135 ).℃

③Take it out after 24 hours, puts it into a desiccator

with a desiccant, and be cooling for 30 to 40 minutes.

④Measure weight and calculate by the following formula.

Measure 3 times per 1 sample and describe

by average value.

Cock

Vaseline is applied.

Desiccant

<Procedure>Moisture content 3

.

Water contents meter 1

Electric resistance type

I

R

E

R E

I

I =E

R

R water contents∝

.


Electric capacitance type

Q=CV

ε water contents∝

Ci

V

d

S

C=8.855×10-8εS

d

.


Infrared moisture determination balance

Moisture contents are detected weight loss by heating and drying.

<Definition of crack grain>

(1) Grains that have 1lateral crack that goes all the way through.

(2) Grains that have 2 lateral cracks on one side that do not go all the way through; viewed from another surface there are 2 lateral cracks, which occur in difference parts of the grain.

(3) Grains that have 3 or more lateral crack on one side that do not go all the way through.

(4) Grains that have longitudinal cracks, regardless of them number or form.

(5) Grains in which there are honeycomb pattern cracks.

Crack 1

<Procedure>

①Cracking rate is measured by brown rice which husked by hand or handy husker.

②Good grain containing crack grain is measured.

③Measurement is judged in seeing through them with

the naked eye using equipment.

④Samples are extracted after drying. It is measured, after sealing this sample and

saving in normal temperature for 48 hours or more.

⑤The number of measurement grains are 250 grains.

Crack 2

100250

grains crack of Count(%) rate Cracking ＝

Rough rice WheatOther thanrough riceor wheat

Foreignmatter

g/l % % % % % % % % %

1st grade 810 701st gradesample

15.0 15 7 0.1 0.3 0.1 0.3 0.2

2nd grade 790 602nd

grade15.0 20 10 0.3 0.5 0.3 0.5 0.4

3rd grade 770 453rd

grade15.0 30 20 0.7 1.0 0.7 1.0 0.6

Offgradeupper

limit 770- - 15.0 100 100 5.0 5.0 5.0 5.0 1.0

Item/

Grade

Lower limits Upper limits

Damaged kernels, dead kernals, colored kernels, other grains and foreign matter

Moisturecontent

Testweight

Headrate

Graincharacter

Other grainsColoredkernels

TotalDead

kernels

HuskingHusking Separating Polishing

Engelberg rice huller polisher

One machine performs husking and polishing

Combination of husker,separator and polisher

This system simple but milling yield is lowPolisherSeparatorHusker

Space between rolls

Husking 1

Clamp

Brawn rice

Palea

Lemma×

Husking 2

Conclusion of Easy Husking

①Direction of Length

②Friction Force

(a) equal-diameter (b) difference-diameter

Husking 3

Roll type husker

nN d

D

n (rpm) > N (rpm) d (m) < D (m)

(a) equal-diameter (b) difference-diameter

Husking 4

Roll type husker

nN d

D

n (rpm) > N (rpm) d (m) < D (m)

Roll 　 clearance ；　 0.8 ～ 1.2

Ratio of peripheral velocity difference ；　 0.23 ～ 0.24

Husking 5 Structure of roll type husker

300kg/h-1inc.

Liner

Impeller blade

Husking fan

Husking 6

Impeller type husker

Inlet paddy

Moisture　contents　(%)

Roll　type　husker

Impeller　type　husker

Hus

king

rate

(%)

Husking 7Relationship between moisture contents and husking rate.

Husking 8

Roll type Impeller type

Capacity (kg/h)

Husking rate (%)

Durability

Scared kernel

Air-gun eject type Flapper eject type

Good eject type

Bad eject type

Good eject type

Bad eject type

Flapper ejectorAir-gun ejector

ChuteBelt conveyer

Sensor

CCD cameraLight

Feeder

Light

CCD cameraLight

Back ground

Viewing chamber

Drying and Dryer

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