The study scientific farming "RICE DRYING TO MECHANICAL Minimise" pdf

This training manual brought to you by CARD project VIE026/025 – Nong Lam University HCMC – The University of Queensland, AustraliaMECHANICAL RICE DRYING TO MINIMISE 1.. Higher rice qu

The study scientific

farming "RICE

DRYING TO MECHANICAL

Minimise"

This training manual brought to you by CARD project VIE026/025 – Nong Lam University HCMC – The University of Queensland, Australia

MECHANICAL RICE DRYING TO 

MINIMISE 

1 Higher rice quality and longer storage period: less cracked grain, higher head rice yield COMPARISON OF EFFICIENCY 

Is mechanical rice  drying better than sun 

drying ?! 

         TRAINING MANUAL 

2 More active, less weather dependence (alternative sun and rain , flood )

Cost: Mechanical rice drying cost is not

too high as compared to sun drying:

• Mechanical drying: 40-50 VND/kg;

• Sun drying: 30-40 VND/kg (sunny day); 120-130 VND/kg (rainy day) Sun drying (high labor cost,

large area required for drying,

weather dependent,…)

3 Less grain losses due to attacks of pests, rodents, poultry…

Quality: Mechanical dried rice is better

in terms of:

• Increase in head rice recovery

• Decrease in grain losses

Mechanical drying (less labor

required, more active…)

…it is sunny

It’d better to apply  mechanical rice drying 

even if 

Economic efficiency: higher benefit

than sun drying (66-76 VND/kg after expenditure deduction)

4 Cost-saving and issues regarding labor force, small space required for drying

Contact information: Dr. Truong Vinh, Project Leader, Head Department of Chemical Engineering, Nong Lam University HCMC, Tel: 08‐7242527/7245030

This training manual brought to you by CARD project VIE026/025 – Nong Lam University HCMC – The University of Queensland, Australia

Contact information: Dr. Truong Vinh,  oject Leader, Head Department of Chemical Engineering, Nong Lam Un versity HCMC, Tel: 0

VARI ARE

NORMAL and REVERSIBLE AIRFLOW FLAT BED DRYERS

  OPERATION TECHNIQUE 

1 Paddy loading

Load a uniform moisture content paddy

to dryer (set-back feeding, don’t

trample upon paddy)Æ level the

surface of paddy load

Thickness of paddy for flat bed drying,

airflow upward: 30-35cm; reverse

downward: 60-70cm

2 Furnace burning

Husk furnace: Spread husk, set husk

on fire until husk burned outÆ start the

dryer

Coal furnace: Use fire-wood to set coal

on fire Æ start the dryer

3 Drying air checking:

Drop a paper on the surface of paddy,

and then speed dryer up gradually;

+ Drying-airless if a paper is still on the

surface of paddy

+ A paper flies upon the surface of

paddy 2-3 cm indicating drying air

sufficiency

Drying air should be widespread over

the surface of paddy mass

4 Dry

Use tempe

42oC;

Higher rice qu Lower drying

 CURRENTLY USING

thermometer to monitor drying rature: : food rice 45oC; seed rice:

drying temperature results in lower ality;

drying temperature leads to longer timeÆ energy cost

5.Grai

- Grai drying:

interva

- Air r

drying

fan, c metal benea airflow

n mixing or air reversal

n mixing: applied for normal flat-bed switch off the fan, mix paddy in 2h

l

eversal: Applied for reversible airflow

: Stop the heat supply, switch off the over paddy by the plastic sheet or lid, open both drying air outlet

th and air distribution tube upper for going through

6 Red

After paddy over-h

ucing drying temperature

a paddy reversal, continue to dry

at 38oC to prevent the bottom layer eating

7 Air

Stop h contin before

blowing

eating when paddy is dried uniformly,

ue air blowing 45 mins for cooling finishing up the drying batch

Caution

drying t rice rec increas For exa recover recover

: Drying paddy “properly” uses appropriate

emperature and air volume so that high head overy is obtained Drying paddy “improperly”

es the level of losses due to grain breakage

mple, drying 100 kg paddy: Drying “properly”:

s 62 kg “rice 10%”; Drying “improperly”:

s 50-54 kg “rice 10%”

Nong Lam University, HCM city – The University of Queensland, Australia- CARD Project 026/VIE05

Contact Address: CARD 026/VIE05 Office ment - Nong Lam University, HCM city, Tel.: 08-7242527/ 7245030, Email: cnhh@hcmuaf.edu.vn Chemical Engineering Depart

RICE HARVESTING METHODS:

MINIMISING LOSSES

There are 4 common harvesting methods:

1 Manual cuttingÆ field drying, manual

collectingÆ machine, threshing

Advantages : Low threshing energy due to short

rice stem, independent of soil condition and the

degree of rice lodging, high cleanness of rice

Disadvantagess : High grain losses, low

capacity, large number of labourers – poor rice

quality if raining before threshing

2 Cutting by reaperÆfield drying, manual

collectingÆ machine, threshing

Advantages : The machine is not heavy, high

capacity (1-6 ha/day); it can work in the soft

soil field - high cleanness of rice, low

investment, high mobility

Disadvantagess : Long rice stem leading to

high threshing energy, lager grain losses, large

number of labourers for collection, hard to

harvest lodged rice, poor rice quality if raining

before threshing

3 Cutting by reaper Æ combine collecting and threshing

Advantages : The reaper is not heavy, high

capacity (1-6 ha/day); it can work in the soft soil field, high cleanness of rice, high mobility

Disadvantagess : Large investment; long rice

stem leading to high threshing energy, difficult

to harvest lodged rice, poor rice quality if field drying is applied before collecting

4 Harvesting by combine harvester

Advantages : High capacity- save time and

labourers, good rice quality, limited rice cracking

Disadvantagess : Low

mobility when using caterpillar- depending on soil firmness - difficult to harvest lodged rice – hard

to maintain the harvester, high investment

CONSIDERED ISSUES WHEN INVESTING AND USING THE COMBINED HARVESTER :

- Selection of appropriate harvesting method and harvester type for high capacity should base on soil conditions and cultivated season

- Movability of combine harvester on farm depends on its weight and the firmness of field soil base Moving by caterpillar has lower mobility than others

- The machine has many complex components and parts Thus, care, maintenance and operation of the machine should be carried out properly

SOME COMBINED HARVESTERS CURRENTLY USED IN THE MEKONG

RIVER DELTA

Company Operation

width(m) Recommended field Vinappro

Nhựt Thành Chín Nghĩa

Út máy cày

1,2 1,3 1,5 1,9

Narrow, soft soil Narrow, soft soil

Moderate field, dry soil

Moderate to large field

Nong Lam University HCM city, Viet Nam – Queensland University, Australia - CARD 026/VIE05 Project

For more information, contact Dr Truong Vinh, Head Chemical Engineering Department - Nong Lam University, HCM city Tel.: 08-7242527/ 7245030, Email: cnhh@hcmuaf.edu.vn

OPTIMUM HARVESTING TIME Famers agreed that late harvesting caused

reduction in head rice yield

Variety Season Growing time

Wet 88 90 92 94 96 98

OM1490

Dry 88 90 92 94 98 104

Wet 88 90 92 94 96 98

OM2718

Dry 88 90 92 94 96 98

Wet 86 88 90 92 94 96

OM2517

Dry 82 84 86 88 90 92

Wet 86 88 90 92 94 96

OM4498

Dry 87 89 91 93 95 97

Jasmine Wet 94 96 98 100 102 104

AG 24 Wet 86 88 90 92 94 96

IR50404 Wet 88 90 92 94 96 98

Late harvesting Early harvesting

The date of physiological maturity, good time for harvesting

What are rice

losses? Losses from harvesting ? Losses from drying, storage ?

Losses from milling ?

Harvesting time experiments

More broken rice (Late harvesting)

More head rice

(correct harvesting)

80 – 85% of rice is ripe

Reasons for late harvesting: lack of labour,

harvesting is concentrated in a short time…

Solution methods:

- Mechanical harvesting

- To plant varieties with different maturities

in the same location

1 Harvesting after maturation date increased cracking fraction and reduced head rice yield

2 A late harvesting of 4-6 days reduced 7-28% head rice yield equivalent to a loss of 600.000 – 2.100.000 VND/ha

Encouraged harvesting time (shade red color)

This training manual brought to you by CARD Project 026/VIE-05 – Nong Lam University HCMC – The University of Queensland, Australia

Training

Project Co-ordinators: Australia- Bhesh Bhandari and Shu Fukai, The University of Queensland, Australia Vietnam: Truong Vinh, Head Department of Chemical Engineering, Nong Lam University HCMC; Tel: 08-7242527/7245030

Selecting appropriate

rice milling system and

technology in production

scale

Milling quality enhanced

Size of milling plant versus milling quality

Milling plant Head

rice

Cracked rice

Broken rice Bran Husk

Larger production scale, less cracked grains

Brown rice milling quality in small scale plant

Huskers Head

rice

Cracked rice

Broken rice Bran Husk

Huskers Head

rice

Cracked rice

Broken rice Bran Husk

Brown rice milling quality in medium scale plant

Corresponding milling capacities for large, medium & small

scales are above 4 tons/h, 1-4 tons/h, and below1 ton/h,

respectively Combined type is the combination of disc and

rubber roll huskers

Husker Head

rice

Cracked rice

Broke

n rice Bran Husk

Using combination of 2 huskers for brown rice milling

Disc husker is applied firstly

to mill paddy

Rubber roll husker is applied secondly for unhusked rice

Enhance milling capacity, reduce maintenance cost, low cracked grains.

Milling system for white rice consists of 3 units of cone shape mill Each unit removes bran layers consecutively

Rice milling and polishing system,

capacity 5 tons/h

Brown rice milling quality in large scale plant

Stone mill Coffee

mill

Coffee husker: capacity 0.2 ton/h, high cracked grains, low head rice yield, mobile

Disc husker: high cracked grains, low maintenance cost, capable of milling high moisture content rice

Cone shape mill:

milling thoroughly, high cracked grains

Rubber

r Cone shape

mill

oll husker Rubber roll husker:

low cracked grains, low capacity, high maintainance cost.