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The Carousel Dryer - 30 years proven technology

This article is published in International Aquafeed June 2021

A proven technology with more than 30 years of history in the market

As there are a lot of dryer options available in the market. What criteria are important for you to consider before making your selection?

If you are considering buying a new dryer and are looking for a dryer with high reliability, easy moisture control, high energy efficiency, and quick product changeover, then this article is definitely for you.

There are many different options, but this article will focus on the CAROUSEL DRYER, proven technology with more than 30 years history in the market.

The main function of a dryer is evaporating water. The evaporation must uniformly take place and consistent in time, with minimum energy usage and with the option for quick changeovers to minimize downtime and to improve your overall drying process efficiency.

Carousel dryer airflow arrow
Figure 1. Airflow of carousel dryer

Target moisture versus time
Figure 2. Target moisture changes in time

Reliable and Easy Moisture control

For the past 40 years, IDAH designs and manufactures equipment and process lines for the aquafeed and pet food industries. In 2011, IDAH started focusing on the Carousel Dryer technology. Our team of expert Engineers have worked intensively to improve the Carousel Dryer technology even further to increase the drying process efficiency. The Carousel Dryer delivers outstanding performances when compared to traditional dryers. The main advantages of choosing a Carousel Dryer are:

• All the products undergo the same drying conditions, resulting in very uniform and steady drying.
• Optimal counter-flow heat transfer, resulting in low energy costs.
• Quick changeovers in a controlled way, lessen product contamination.

The impact of moisture on your product

When choosing the correct dryer for your application, moisture control should be one of the most important selection criteria. Moisture has serious impact on your product quality and cost price levels, and profits for your business One aspect of moisture control is uniformity, together with drying result consistency–in-time will determine the target average moisture content. The closer the average moisture to the maximum moisture levels, then the less raw material are lost through over-drying, generating more profit for your company.

In the cylindrical-shaped Carousel Dryer, the product is rotated 360° on multiple decks and mixed by each drop when the tray gently tilts and the material flows into the deck below. By rotating the product, the product is situated in a fixed air stream, so all the product gets the same drying conditions resulting in a product with uniform moisture and consistent quality. In summary, uniform consistent drying is using less raw material and reducing energy costs.

Improving dryer efficiency and saving energy costs

Water evaporation, or drying, is naturally a highly energy-intensive process. The drying process has an unavoidable constraint to supply enough energy for evaporation. The efficiency of a dryer will be determined by the energy input about the amount of water evaporation.
The Carousel drying air passes the incoming product in this multiple layer dryer in a counterflow direction to achieve maximum heat transfer, resulting in a low exhaust air temperature. This in combination with drying air recirculation will reduce the exhaust air volume and improve energy efficiency.

Another option for energy conservation is the re-use of the cooling air. Using the cooling air as make-up air for the dryer will reduce the volume of exhaust air resulting in fewer odor control issues. Plus, all the heat from the cooled product will be used in the dryer for water evaporation. This combination will improve dryer efficiency and saving energy costs.

The feed market trend is demanding to customize products, which results in an increase of formula-changing frequency. This situation demands producer to have a good and tight production schedule to keep machine running optimally, while at the same time ensure no product contamination using the FIFO (first in first out) principle.

Carousel dryer in customer site
Figure 4. Carousel dryer (Model TT-300-4-4) in customer site

Control system of carousel dryer developed by IDAH
Figure 4. Control system for carousel dryer developed by IDAH

Developing an operator-friendly control system

In 2020, IDAH incorporated a new moisture control system. This control the system consists of:
Air volume and Temperature control - The control philosophy of the dryer will be a crucial factor in the overall performance. To get maximum profit for the uniform drying performance of the Carousel Dryer, we control the energy absorption from the product by controlling the air volume and temperature control.

Water evaporation calculations - the Carousel Drying System helps companies accurately control their product moisture and keep track of any changes in the parameters during production. This will help the operator to achieve and maintain the target moisture quickly and efficiently.
Energy efficiency indication - With the automatic calculation, the operator can see the efficiency of the drying process and take quick measures whenever the numbers are abnormal. Energy control is drying control

Total control over energy consumption in your plant

Depending on your expectation of an ideal dryer, you may have to look for different dryer options in the market. The dryer is a big investment and also a big energy consumer in your plant.
IDAH considers all of your process requirements, moisture uniformity, efficient energy transfer, easy operation, and minimal down-time to select the suitable Carousel Dryer for your industry.


Graduated from National Taiwan Ocean University Food Science Department earning the title of Master of Science (MSc.) Albert has a strong background in science and used this science-based approach to deliver knowledge to Customers. Yearly experience in sales, technical, and marketing departments, added with continuous communication with the Customer gives him the knowledge in feed machinery and its operations.

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