Pioneering tempering dryer
by Kazutaka Ikeda, International Business Division, Satake Corporation, Japan
Satake's history for the development of the tempering grain dryer began in the 1960's. After building Japan's first country elevator (CE) with LSU type dryers in 1964, Satake started installing its new type dryer SDR- Speed Dryer, in its CEs.
The new dryer repeated the process of heating up the paddy for six minutes and holding it for two hours in a separate bin to evenly distributethe moisture contents (MC) between the husk and the brown rice inside, a process referred to as 'tempering', to slowly bring the MC down for safer storage.
A single heating and tempering cycle reduced the MC by approximately two percent. Besides contributing to the yield by reducing the broken rice caused by rapid drying, the tempering drying method was also able to reduce the size of the equipment. It needed only 1/20th the size of drying section compared to previous continuous dryers. The tempering drying method became the standard for paddy drying since that period.
In 1966, Satake introduced a smaller size dryer, the MDR series, for farmers. It had both drying and tempering sections in a single unit. Paddy moved through a drying section receiving heated air at approximately 40-60°C for few minutes then transferred to a tempering section above by a bucket elevator.
It was held here for approximately one hour to equilibrate the MC between husk and brown rice before then being moved through the drying section again. Repeating this cycle multiple times, the MC dropped by 0.5 percent every one hour. This signaled the introduction of both the first 'tempering dryer' and'recirculating dryer'.
Since then, Satake's tempering dryer has continuously made advances in its functionality, introducing such features as a standard moisture meter controlled drying time, and an automatic shut off burner function once the desired moisture level is achieved.
When I joined as a sales person in 1997, Satake had already sold the GDR- Gourmet Dryer, equipped with a single-grain automatic moisture meter and a gun-type kerosene burner. The dryer was equipped with a "Gourmet Drying' function- a special drying mode, and an innovative function not found in other dryers in the market.
Its purpose was to prevent the deterioration of germination rate and to increase tastiness by gradually raising the hot air temperature rather than fixed high temperature to dry the grain.
Unfortunately, many customers did not use this function because the dryer's automatic temperature control system provided sufficient final product quality for them even at the normal drying setting.
The accuracy of the moisture meter, trouble free machine mechanism, high final product quality, made this dryer extremely popular among farmers. I am proudly pleased to see that some users still use the dryer even today.
In 1999, Satake launched the RMDR, Magic Dryer. It was designed to dramatically improve drying efficiency by adding a warming section additional to the ordinary drying section and provided the fastest drying speed in the market.
At the time, most of other manufacturers began to introduce far-infrared dryers. This was almost a fad in the industry. However, Satake went one step beyond because what our customers truly needed was drying efficiency and shorter drying time.
In 2004, Satake developed the 'Solana' type dryer, from the Spanish word 'sun', as a successor to the RMDR in the Japanese market. Although it was well received by the market, Satake engineers continued improving the dryer.
Inverters were added to reduce operation cost. The addition of a humidity sensor also made it possible to automatically maintain the drying rate even at high ambient humidity. To make its operation as easy and simple as possible, our engineering team pushed the limit of automated operational functions.
In 2016, Satake began sales of Solana base dryer NSDR to overseas markets. By 2019, it has gained popularity in many countries, especially in Asia, such as India, Bangladesh, Thailand, the Philippines, Vietnam, Indonesia and Myanmar.
The Asian market has even greater potential in the future. Many still do not utilise mechanical dryers and sundry rice paddy, and most of all, rice production is still growing.
As an added feature to NSDR, paddy husk which is more economical and easier to procure than kerosene in many Asian region, was adopted as a heat source option. The dryer performance was designed to maximise the yield and quality of the final product - white rice.
Another function our engineers focused was ease of operation. For example, the degree of variation in MC is displayed in detail on a monitor, and even when the variation is large, the gradual variation in moisture as it becomes uniform can be visually checked in detail, during and after drying.
By visually checking on the monitor, its operator can choose to dry slowly or less slowly when there is excessive MC variation. Even if the grain temperature is unexpectedly increased, depending on the nature of the rice, the grain temperature is controlled by sensor, so it is automatically controlled to be lower.
This automatic control function, which is standard to NSDR, enables the production of dried paddy with superior storage and processing properties, and with low moisture variability. When dried paddy is mixed with high-moisture paddy, there is a high possibility of producing damaged rice, such as discolored or rotten rice - unsellable in the market.
NSDR can avoid this issue. Additionally, both over-dried and high-moisture rice can cause instability in milling, such as yield, amount of broken, whiteness, etc. NSDR can avoid this issue by drying grains to a set moisture level regardless of ambient conditions, resulting in a stable milling process, and a better taste in the final product, white rice.
Grain dryer design, incorporating all the elements from drying efficiency, through processing, to final product taste, is something Satake continues to pioneer amid a long history of tempering dryer development. Satake continues to develop equipment that responds to the true needs of its customers, industry, and the market.