Gas treatment for biomass gasification

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Dahlman is investing in the development of products in the field of renewable energy. For biomass gasification we have important technology commercially available. The renewable energy team of Dahlman has a dedicated website: www.renewableenergy.nl

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Biomass is one of the most important sources of sustainable energy. The highest electric efficiency is reached by gasification of biomass in biomass product gasses. This product gas than can be used in gas motors, gas turbines chemical synthesis or fuel cells.

The presence of tars in the product gas is seen as the biggest problem in the smooth commercial application of biomass product gas as source of sustainable energy. Tars are responsible for fouling, efficiency loss, unscheduled plant stops and chemical pollution of the scrubbing water in downstream ammonia and acid scrubbers. Tar is defined as all organic compounds with a molecular weight bigger than benzene. 

Principle
OLGA is a highly efficient tar removal system which operates above the water dew point. The tar removal principle is based on a multiple stage scrubber in which the gas is cleaned by a special scrubbing oil. In the OLGA columns all tar aerosols and the heavy and light tars are removed from the gas, as well as most of the BTX compounds (Benzene, Toluene & Xylene). Product gas leaving the OLGA is tar free (tar dew-point < 10 °C), which eliminate all tar related problems. In fact, tar is removed so efficiently that more demanding applications as gas turbines or fuel cells are now well within reach.

Further down stream; aqueous scrubbers used for e.g. ammonia removal can operate without problems. Scrubbing water is no longer contaminated with tars (e.g. phenols) as the dew point of the remaining tars is now well under the water dew point.

The tar loaded scrubbing oil which leaves the absorption column is fed into a stripper column. In this stripper the scrubbing oil is regenerated after which the oil is fed back to the absorption columns. The stripper medium (hot air) is used as fluidisation gas for the gasifier. In the gasifier all recycled tars are destructed which makes the OLGA a virtual waste free system.

The principle of OLGA is shown by a simplified PFD sketch (see the photo’s on the top right). More information can be found in the attached PFD (POC report OLGA). 

Summarised advantages of OLGA

• No more condensation of organic compounds (tars)
• No more tar related problems like system fouling
• No pollution of process water in aqueous scrubbers
• Biomass product gas, which is clean enough for advanced applications like gas engines (CHP), gas turbines (IGCC), fuel cells or chemical synthesis (e.g. SNG production).

Dahlman / ECN cooperation
The Energy research Centre of the Netherlands – ECN - is the leading institute for energy research in the Netherlands. The OLGA principle is a patented ECN invention. Dahlman has developed OLGA together with ECN and is has the exclusive world wide licence. In 2006 the OLGA technology proved itself in a long term duration test. OLGA is now a commercial available technology.

Possibilities ECN & Dahlman
The activities of Dahlman and ECN are complementary to each other. Dahlman and ECN therefore form an excellent team, which can assist you in every aspect of your project. Underneath we give you a short summary:

• Chemical research.
  We are able to study you process conditions and can make an optimal pre-process design of an OLGA for your specific situation. ECN is an authority in the field of energy research. Your process circumstances are clearly understood and can be discussed in detail because of our know-how
• Lab scale tests.
  Possible in our own lab facilities in Petten or at your site. In Petten we can use a small bubbling fluidised bed gasifier, which has a capacity of 1-2 Nm³/hr.
• Pilot scale tests.
  Possible in our own pilot facilities in Petten or at your site. In Petten we can use a pilot scale circular fluidised bed gasifier, which has a capacity of 200 Nm³/hr.
• Basic design and mechanical engineering according to your specifications.
  Design and engineering of industrial scrubber and filtration systems for e.g. global contractors and end customers in the (petro)chemical and power industry are Dahlman’s daily business.
• Detailed engineering according to your standards and requirements
• Production, turn-key delivery and full project management (ISO 9001 certified)
• Commissioning & start-up on site (VCA** certified)
• Service activities

Other applications:
Next to gas cleaning product gas in biomass gasification systems the OLGA principle can be used to remove organic compounds or tars from gasses in other applications. Please contact us to investigate the possibilities together.

Contacts