Optimization of screw conveyors for wood-fired power plants.

“You’re welcome to come over for a coffee, but we don’t need any new components yet. Your snails still look like new after 3 years. “ ~ Lukas Hampel – Operations Manager HHKW Hollabrunn

In the world of energy production from renewable raw materials, wood-fired power plants are a reliable source of heat and electricity. These plants use wood chips as fuel to generate heat through the combustion process, which is then fed into district heating networks or converted into electricity. A central element of these systems are the screw conveyors, which are responsible for transporting wood chips to the oven and ash from the oven. In this article I would like to give you an insight into the optimization of screw conveyors for wood-fired power plants.

The challenge of wear and tear

One of the main problems that I repeatedly encounter in wood-fired power plants is the extremely abrasive wear to which the screw conveyors are exposed. This wear occurs particularly in the area of ​​ash removal, as ash itself is very abrasive, but additional wear problems arise due to the formation of lumps. Screw spirals and hutchs are therefore subject to very high stress.

As a rule, the operator of the wood-fired power plant in Hollabrunn had to partially or completely replace his screw conveyors several times a year, which led to considerable downtime and maintenance costs.

The solution: coated screw conveyors

In order to solve this problem and sustainably save operating costs, I pursued the following approach: using coated screw conveyors. Instead of using traditional black steel, these screws are provided with special hard coatings that make them significantly more resistant to fretting wear. These coatings are specifically designed for use with abrasive materials such as ash and offer a significantly longer lifespan.

The manufacturing process

These modifications to the screw conveyors require a highly precise manufacturing process, which my partners implement perfectly. First, the screw spirals are prefabricated and formed from hard faced plates adapted to this material. They are then carefully assembled and welded onto the snail tree. The outer edges of the scroll are then hand hard faced to provide additional protection against wear. The result is screw conveyors that can counteract the extremely abrasive material in wood-fired power plants.

Long-term operation and cost-effectiveness

Our coated screw conveyors have been used successfully in many wood-fired power plants in Austria for several years. Instead of having to repair the augers twice a year, as was previously the case, they have now been running maintenance-free and without any problems for several years. This not only reduces maintenance costs and downtimes, which leads to integrally reduced operating costs, but also makes customers like Lukas Hampel very positive.

Other applications in wood-fired power plants

In addition to these coated screw conveyors, I have also developed components for other applications in HHKW’s that are used in a wide variety of systems in Austria: substrate screw conveyors, push or scraper floors and wear strips in combustion chambers.

Adapting this technology to different applications offers potential for significant cost savings and longer service life of equipment components.


In conclusion, optimizing screw conveyors through special coatings has proven to be an extremely effective solution to the challenges in wood-fired power plants. The use of this technology can not only reduce operating costs, but also improve the reliability and efficiency of the systems. Investing in high-quality, coated screw conveyors pays off in the long term and contributes to sustainable energy production and resource use.