Drying Technology

Drying Technology & it’s Features

We are expert for solution of suitable drying technology with input of our long R&D work & experience in the field of thermal gasification & renewable energy. Based on client’s requirements & our vast techno commercial and field experience we will help to select the best technology which has high energy efficiency, better safety, economical & environment friendly.

Many factors are taken into consideration when designing a dryer that can both energy efficient and effectively dry a material. Factors such as bulk density, specific heat, and flowability, among others, all interact to influence how the material will behave in the dryer, and subsequently, how that material will be dried. One critical factor in designing a dryer that produces the desired end product characteristics is the air-flow configuration, or the direction in which the process gas flows through the dryer in relation to the material.

Dryer has been developed through extensive research and development in order to maximize the thermal efficiency of the drying process. The selection of which air-flow configuration will best suit the process is based on the material’s properties, as well as overall process requirements. Even though the material characteristics are ultimately the deciding factor, it is important to understand how each air-flow option is designed to fully understand the benefits each has to offer.

1. Rotary Dryer : It is a type of drum dryer is being used to reduce or minimize the moisture% of materials by bringing it into direct contact with hot gases. It is a long cylindrical inclined tube supported with structure due to inclination heated material come out by gravity. Material to be dried enters to the rotating dryer & will be lifted by internal fins & after required rotation will come out of dryer after contact with incoming hot gases. Material will be dried in contact with hot gases in mostly two ways. If hot gases moving towards the discharge end from feed end with material is called co-current flow. If hot gases move towards feed end from discharge against material flow called counter current.
   1. Rotary Dryer (Co-Current): Co-current drying, which is also referred to as parallel flow, is when the drying air flows in the same direction as the material flow. This immediately puts the wettest material in contact with the hottest combustion gases, resulting in quick initial drying. This system also causes rapid cooling of the drying air, which results in a cooler surface temperature of the dryer shell compared to a counter current dryer. Furthermore, this design makes it much easier to control the temperature of the dried material, because it correlates directly with the air temperature.
   2. Rotary Dryer (Counter-Current): Counter current drying is when the drying air flows in the opposite direction of the material flow. In this design, the wettest material comes in contact with the coolest drying air. Unlike the co-current system, the material will come in contact with the hottest drying air at the discharge end of the dryer, at its most dehydrated state. Because of this, the counter current method provides increased thermal efficiency for materials that need to be heated to high temperatures.
2.  Paddle Dryer: It is a new generation compact design with high efficiency drying technology. It is a indirect dryer uses heat transfer fluid (Thermic Fluid) to transfer heat from hot air generator to raw materials which are to be dried. The paddle dryer is well known for its compact & strong design & in very small space can give high heat transfer efficiency.Features:
   • Wide range of application in any raw material.
   • Dryer size is minimum due to the large heat transfer area per volume
   • The wedge shaped paddles obtain high transfer area due to proper mixing
   • Exhaust gas/flue gas treatment can be low due to low volume of hot gases
   • Raw material sensitive to temperature can be dried easily due to indirect heating.
3. Flash Dryer : It is a simplest & cheapest way to dry material. Flash dryers having low residence time within the equipment thus flashing of moisture from the feed. Low temperature dehumidified air could be used for heat. Wet material is disposed into a steam of heated air which conveys it through a drying duct. Material dried in air steam while conveying. Final Product can be separated using cyclones, bag filters with scrubbers in fuel gas.Temperature sensitive material difficult to handle in this type of dryer. Mostly less sensitive low water is being used in flash type of dryer. This type of dryer use higher gas temperature versus other types of dryer, because the material retention time is very short.
4.  Fluidized Bed Dryer: Fluidizing is a process in which granular material is converted from static solid like state to dynamic fluid like state.  When hot air flow introduced through the bottom of a bed of furnace to solid particles via empty space between particles by increasing velocity of hot air simultaneously the bed is said to be fluidized and will exhibit fluidic behavior. A bed of solid particles will behave as a fluid. In this state object with lower density than the bed density will float on its surface, bubbling up & down. While objects with higher density sink to bottom of bed. The fluidic behavior allows the particles to be transported like a fluid & become dry. Water will evaporate with hot air.
5. Flat & Wave Bed Paddle Dryer: This is thoroughly new concept & design from Radhe Group. This technology called Flat & Wave Bed Paddle Dryer.In this type of dryer high moisture contain material is being feed in flat bed surface where material will be dried in motion of wave. This will give ultimate drying effect to any material to be dry with low velocity hot air. In this technology not required any flue gas cleaning & scrubbing.