Vacuum Hot Air Drying Equipment – Providing a Reduced Drying Time

In a comparison of our vacuum hot air drying systems and conventional drying systems that are only operated at atmospheric pressure without vacuum, one characteristic clearly stands out: The drying time is reduced by nearly 50%. HEDRICH vacuum hot air drying equipment can be used for many applications. Benefit from our innovative drying technology and excellent drying results.

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Uniform Drying

In the air circulation system, the heat transferring medium air is circulated by means of fans between the heated autoclave wall and air baffles so that the air is heated up and conducted to the parts to be dried which are uniformly dried. The exchange of air enriched with water vapour is efficiently controlled by a moisture sensor.

Customized Design

We design and build our equipment individually according to your specifications to achieve optimum and energy-efficient drying results. Depending on the application, either round or rectangular autoclaves are used. Customer’s specific needs are also considered by HEDRICH for vacuum pumping units when selecting either oil-sealed or dry-sealing backing pumps to design and build optimum solutions.

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Shorter Drying Times with Current Heating

To reduce the time needed for drying, vacuum circulating air (hot air) drying equipment are provided with an additional direct-current heating. This solution is preferably used for the drying of windings. A combination of resistance and circulating/hot air heating allows to heat up faster and more uniform, thus increasing the energy efficiency.

Homogeneous Heating

HEDRICH heats the complete autoclave with all surfaces, including top, bottom, rear wall and door. The temperature is controlled via different heating circuits, with manual control valves. The typical heating medium is heat transferring oil that is pumped through U-shaped pipes welded on the autoclave. With smaller autoclaves, heating is also possible through electric heating plates installed at the outside.

Advantages
Applications

Advantages of vacuum hot air drying equipment

• Control of circulating air to be exchanged by a moisture sensor
• Optimized and uniform heat distribution through fans and air baffles
• All-around heating of autoclave by means of heat transferring oil, including door
• Further reduction of the drying time up to 75% by additional use of a current heating device to heat the windings
• Loading by air cushion vehicle or trolley
• Online registration of dew point and water rate during the fine vacuum phase

Applications

• Distribution transformers
• Power transformers
• High-voltage instrument transformers
• High-voltage bushings
• Components for transformers
• Transformer windings
• Traction transformers