ANDRITZ Separation - ANDRITZ Group

- Gouda Paddle Dryer



The machine has a heated through, containing rotating heated paddle shafts. The specially shaped paddles do not have a transport function but are designed for maximum heat transfer. This results in an excellent control of the temperature of the product and enables a uniform product quality. At the outlet side, the product moves out of the machine via an adjustable overflow.

The ANDRITZ Gouda paddle dryer offers a once-through drying technology that avoids back-mixing, which makes the machine very suitable for sludge drying. The long sludge retention time combined with the average sludge temperature of 100º C makes it possible to provide pasteurization and hygienic treatment of sludge – any sludge. Any residual moisture level can be chosen for the end product. This makes the machine suitable for partial drying to 35-40% dry solids, which is required prior to incineration of sludge.

  • Good plug flow
  • Fully continuous
  • Low temperature possible due to vacuum
  • Hygienic design


  • Industrial sludge
  • Municipal sludge
  • Drilling mud
  • Paper sludge
  • Biomass
  • Digested manure


  • Polymers (PET, SAP, PA)
  • Gypsum
  • Minerals
  • Metal powders


  • Milk
  • Starch
  • Cocao
  • Flour
  • Sugar

ANDRITZ Gouda’s paddle dryers / coolers are well-known for their robust construction with accurate constant tolerances. ANDRITZ Gouda offers any solution that contributes to the reliability of your particular production process. The machines are manufactured with sophisticated, state-of-the-art welding procedures, according to FEM analysis, so they can withstand high temperatures, heavy duty products and corrosion. The machines are designed for a long, continuous lifecycle. Our quality is certified by ASME, TÜV, European PED, Chinese SQLO and other certified bodies, anywhere in the world.

There are many ways to dry products, but two things are essential: enough heat to evaporate liquid and a means of removing the vapor.

A direct dryer uses hot air flow for both functions. Usually a lot of heat is wasted in the exhaust – and a lot of dust is created and consequent foul smelling - requiring expensive equipment for removal. Solvent recovery can be a problem too.

An indirect dryer avoids all these problems: air flows, where present at all, are negligible. Moreover, a fully enclosed operation enables the safe treatment of toxic, noxious and/or flammable products.

The ANDRITZ Gouda paddle dryer is a compact machine. That is because it has many square meters of heat exchanging surface relative to the volume. Two hollow shafts with hollow paddles turn in opposite directions in the horizontal trough. The trough has an ω- (omega) shape that follows the contours of the paddles.

Moving parts are crucial for the system. They have been expertly designed. Excellent heat transfer is ensured when the product is refreshed regularly and remains in good contact with the heat exchanging surface. The paddles of the ANDRITZ Gouda paddle dryer play a large role in creating these optimal conditions. The uniquely shaped paddle has a self-cleaning capacity. The wedge-shaped paddle produces shear forces on the paddle surface and this keeps the paddle clean and contributes to a higher heat transfer.

As the product moves through the machine, the paddles ensure that the product is well mixed and that it flows easily through the machine. The paddles give excellent mixing in radial direction. The product is not mixed in axial direction. As it moves further into the machine, the product increasingly meets the end specifications with preservation of the plug flow. An even flow (plug flow) through the machine gives each product particle a more or less identical retention time and ensures a high uniform end-product.

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