Rice husk furnace

The first rice husk furnaces were reported in scientific literature around 100 years ago. It was used in a rice mill in Myanmar as fuel of the boiler that created steam used for powering a rice mill with a steam engine (International steam, 2015; How steam engine work, 2015). Rice husk furnaces, such as the inclined grate manual-fed furnace and the automatic non-grate furnace, have been researched and developed in recent years. The rice husk furnace is selected based on efficiency, quality of flue gas (clean), heat capacity, nature of operation (manual or automatic), investment cost, and energy cost. There are two types of rice husk furnaces that are popularly used in Southeast Asian countries, which are small-scale in nature. These are the inclined grate furnace with a cylindrical combustion chamber (Fig. 1, Nguyen et al 1996) and the downdraft rice husk furnace (Fig. 2, Gummert et al 2007). In large-scale applications, continuously fed furnaces are preferred. There are two typical examples of this type of furnace: the cyclone combustion furnace (Fig. 3, Nguyen et al 2012) and the IRRI-NLU non-grate furnace developed by the ADB-IRRI postharvest project (Fig. 4, Tran et al 2013). A comparison of these furnaces is summarized in Table 1 based on assessments in 2013.

 rice-husk-furnace-with-inclined-grate   downdraft-rice-husk-furnace 
Fig. 1. Rice husk furnace with inclined grate and cylindrical combustion chamber Fig. 2. Downdraft rice husk furnace
 continuously-fed-furnace   irri-nlu-non-grate-furnace 
Fig. 3. Continuously fed furnace with cyclone combustion chamber Fig. 4. IRRI-NLU non-grate furnace


Table 1. Types of rice husk furnace used for paddy dryers.

Furnace type

Scope of use

Drying air efficiency

Investment cost
USD (MJ h-1)-1



Inclined grate - cylindrical combustion chamber

Small-scale flatbed dryers (4–20 tons batch-1)



Simple, low cost maintenance

High required labor

Spraying - fed cyclone furnace

Columnar and fluidized bed dryer with higher capacity



Automatic and continuous operating;

- Lower efficiency
- High investment cost

NLU-IRRI non-grate furnace

Columnar and fluidized bed dryer with higher capacity



Automatic and continuous operating;

Lower efficiency


Paddy dryers (4–10 tons batch-1)



Semi - automatic operating

Not developed for the higher capacity yet


Gummert M, Chandrasekar V, Phan HH, Nguyen TN, Ban LV, Aquino E, Rickman JF. Rice hull furnace – IRRI’s experience. Paper presented at the 5th National Grains Postproduction Conference, 18-19 July 2007, Philippines.

How steam engines work. Accessed 2015. http://science.howstuffworks.com/transport/engines-equipment/steam1.htm

Nguyen VX, Truong V, Phan HH. 1996. Development of rice husk furnaces for grain drying. http://aciar.gov.au/files/node/316/grain_drying_in_asia_part_9_11398.pdf

Nguyen VH, Nguyen TN, Tran VT, Nguyen VX, Phan HH. 2012. Rice husk uses in the Mekong Delta of Vietnam. International Workshop on the Innovative Uses of Rice Straw and Rice Husk, 11-13 December 2012. https://docs.google.com/viewer?a=v&pid=sites&srcid=aXJyaS5vcmd8cG9zdGhhdmVzdC11bml0fGd4OjcyOWMzZTg2MGUwZDZlZDU

Temples of Steam – The Rice Mills of Burma. Accessed 2015. http://www.internationalsteam.co.uk/mills/burmamill00.htm

Tran VT, Nguyen VH, Nguyen VH, Nguyen HT, Le QV, Truong QT, Phan HH. 2013. Design and development of the 10-ton/batch columnar paddy dryer. In: Proceedings of International Workshop on Agricultural Engineering and Post-harvest Technology for Asia Sustainability. Science and Technology Publishing House. p 152-163.