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Hot gas cleaning to make the transformation of wood into gas more economical

 

Instead of burning wood to produce heat and electricity, it can be transformed into a combustible gas via gasification. This gas contains impurities that need to be removed before it can be used in higher quality applications. By replacing cold gas cleaning with hot gas cleaning, the gasification of wood can become much more economical.

Project description (completed research project)

The research project examined hot gas cleaning. By cleaning gas at high temperatures, impurities related to wood gasification can be broken down or eliminated.

The type and scale of impurities - among them sulphur, chlorine or alkalis - depends on the quality of the gasified wood. And the required level of purity depends on whether the gas will be used for electricity or as fuel because different uses can tolerate different levels of impurity. So-called cold gas cleaning procedures can deliver the required levels but they could be replaced by hot gas cleaning in the future, thereby significantly improving cost-effectiveness.

The insights of the research project will promote the use of wood as a source of energy beyond combustion and render the technologies needed for this more economical for practical application.

Background

Currently we do not have an industrially viable, biological procedure to transform wood into a different type of energy. However, thermochemical procedures such as gasification are suitable for transforming wood into a combustible gas with high efficiency. This gas contains impurities such as tar which limit their usefulness and therefore have to be removed.

Aim

The project aimed to further develop hot gas cleaning for commercial plants where wood is gasified. For this purpose, the researchers measured the incoming and outgoing material flows at different test facilities while varying the temperature, pressure, gas flow and composition. The main focus of the work was on examining sorption agents which remove the impurities sulphur, chlorine and alkalis from the gas. The results should serve as a basis for computer models which upscale the experimental data for industrial plants and thereby help to optimise processes.

Relevance

The results of the project should contribute towards making hot gas cleaning suitable for industrial use. This technology helps to increase effectiveness and reduce the investment and operating costs of plants. This allows for a wider use of wood as an energy source and, in particular, paves the way for providing high-quality energy to the end user in the form of electricity and fuels.

Results

The researchers have developed a new analytical method for gas which makes it possible to measure impurity levels both rapidly and precisely. This allows them to identify the best sorption agent and introduce it into the process. Thanks to the new test methods, they can assess potential sorption agents swiftly. The results can be used to develop new physicochemical computer models.

Original title

Hot gas cleaning of producer gas from wood gasification for production of bioSNG and electricity from wood (Hot gas cleaning wood gasification)

Project leader

  • Dr. Serge Biollaz, Paul Scherrer Institut (PSI), Villigen
  • Dr. Tilman Schildhauer, Paul Scherrer Institut (PSI), Villigen
  • Prof. Christian Ludwig, Paul Scherrer Institut (PSI), Villigen; École polytechnique fédérale de Lausanne

 

 

Further information on this content

 Contact

Dr Serge Biollaz Paul Scherrer Institut (PSI) 5232 Villigen +41 56 310 29 23 serge.biollaz@psi.ch