Fd.E. 425 Food Engineering Design Coordinator
Middle East Technical University
Food Engineering Department
November 25, 2011
Dear Mr. Ungan,
Please accept the accompanying Work Term Report, aimed designing a toasting oven in order to produce corn flakes. In the designed system 10 tons corn flakes per day is produced. After some processes, corn flakes enters the roasting oven at 20% humidity and exits at 4%humidity.The roasting oven can operate at (±10 ºC) 225 0C.Toasting oven is designed by considering its length, area and operating temperature. Optimizations are done according to these factors on the cost of the total design. In the design system, rotary drum drier is used.350 days of the year plant works and production occurs 16 hours in a day. Corn flakes enter the oven at 225 0C .Amount of air is calculated as 0,648 kg dry air/s .Length of the drier is calculated as 2.27 m. in the result of optimizations done according to proper drying time and dryer diameter. Heat energy needed to raise the inlet temperature of air to 225 0C, is found as 157kw and heat loss is found as 23.6kw.Through these data, total investment which contains dryer cost and electricity cost is found as 92794.98TL. Sincerely, group 3 members
TABLE OF CONTENT
In this design a rotary dryer is designed for drying of corn flakes which have the moisture content 20%.Corn flakes are dried with air 9 % moisture content. The production is done for 16 hours in a day and 10 tons corn flakes are produced per day. In production process, corn flakes are cooked under pressure. After cooking step, big masses are broken to pieces and sent to driers in order to get the moisture level at 20%.After this process, product is flaked between large steel cylinders and cooled with internal water flow. Soft flakes are sent to rotary dryers in order to dehydration to 4% final moisture content and toasting. In the toasting oven, flakes are exposed to 225 0C air for 2-3 min. The drier length is calculated as 2.27 m with the diameter of 0.082m with the assumption of 4%moisture content inlet air and 9%content outlet air. Flow rate of feed is calculated as 0.206kg/s. Mass flow rate of the inlet air is calculated as 0,648 kg dry air/s. Energy needed for bring the temperature of air to 225 0C is calculated as 157kw and heat loss in the system is 23.6kw. By making optimizations total capital investment is calculated as92794.98TL which includes 84881TL electricity cost and 7913TL dryer cost. Finally by making optimizations, in order to have minimum length and suitable energy for the drier, 215 0C is chosen the best temperature for the inlet air.
Rotary dryers potentially represent the oldest continuous and undoubtedly the most common high volume dryer used in industry, and it has evolved more adaptations of the technology than any other dryer classification. Drying the materials is an important consumption process. It is also one of the important parts in cement production process, and affects the quality and consumption of the grinding machine. Drum dryer is the main equipment of drying materials, it has simple structure, reliable operation, and convenient to manage. However there are some problems which are huge heat loss, low thermal efficiency, high heat consumption, more dust, and difficult to control the moisture out of the machine. It plays a significant role in improving drying technology level and thermal efficiency in drying process, reduce the thermal and production lost. In this design we are asked to design a rotary drier which works 16 hours in a day and produces 10 tones corn flakes per day. Also it is mentioned that, corn flakes enters to drier at 20 %humidity and exits 3-5%humidity.This report is about designing a rotary dryer with its dimensions for considering to get the minimum total cost. Optimizations are done according to inlet temperature of the air to the drier. In the...