Gradual reforming

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The staged reforming is a toy in the testing thermochemical process for converting organic raw materials ( renewable raw materials , manure or organic waste ) into combustible low-nitrogen gases (in addition to methane and carbon monoxide , especially hydrogen ), in which water vapor is used as a gasifying agent. The process, in which the smoldering ( pyrolysis ) of the biomass and the formation of the product gas take place separately from each other, is to be used to generate heat and electrical energy in gas generators and serve as a hydrogen source.

Procedure

In the case of staged reforming , pyrolysis and gas conversion are technically separated from one another. In the first stage, the biological material is split into gas and (pyrolysis) coke at around 600 ° C. In a second stage, the gas produced is converted into a synthesis gas with steam and the thermal energy obtained from the coke . Then impurities such as tar, dust, HCl, NH 3 , H 2 S etc. are washed out.

The temperature control takes place in a circuit. The heat transfer medium, which is heated to around 1000 degrees Celsius in the preheater, is fed into the reactor from above. The material cools down to 750 degrees through a chemical reaction. The further cooling to 550 ° C is supported by mixing in cool, new material. The material that has migrated down is now reheated to 1050 ° C. The product gas (synthesis gas) of the staged reforming is rich in hydrogen (44%) and also contains carbon monoxide (CO, 19%), carbon dioxide (CO 2 , 11%) and methane (CH 4 , 5%) as well as water (23%).

One advantage of the two-stage process is the wide range of possible raw materials. In addition to renewable raw materials such as hay, straw or wood, paper and sewage sludge as well as animal droppings, organic waste and substitute fuels made from waste can be used. In addition, the dust and tar contents in the product gas are lower than in single-stage processes, which makes it easier to use the gas.

history

The Dr. Mills GmbH & CO. KG patented process was used between 2001 and 2006 in a pilot plant with an output of one megawatt in Herten . The state of North Rhine-Westphalia is funding the construction of a plant (“Blue Tower”) with a capacity of 10 megawatts for the delivery of synthetic natural gas, also in Herten, on the site of the former Ewald colliery. Critics of the project consider the technology to be too expensive and question the practical readiness and energy efficiency of the process. The majority owner of the company shares in Blue Tower GmbH, Solar Millennium AG , filed for insolvency at the Fürth district court on December 21, 2011. The shares in Solar Millennium AG were taken over by Mr. C. Thannhäuser in 2012 and transferred to Concord Blue Engineering GmbH, Düsseldorf. In 2013, the demonstration system in Herten, which was partially built under the direction of Solar Millennium, was also taken over by the insolvency administrator. Since then, the project has continued to be implemented together with general contractor Lookheed Martin, USA, and is scheduled to go into operation at the end of 2016.

Individual evidence

  1. ↑ Michael Mayer, Heinz-Jürgen Mühlen and Christoph Schmid: Staged reforming of biogenic residues - first operational experience. Presentation at the DGMK conference "Velen V" 2002 (PDF; 974 kB).
  2. ↑ A pilot plant for converting biomass into electricity was opened in Herten. ( Memento from August 3, 2012 in the web archive archive.today ) Energieagentur NRW , 2001.
  3. ↑ Joachim Jürgens: Blue Tower in Herten. (PDF; 4.7 MB) In: pro-herten.de. January 15, 2015, p. 85 , accessed July 29, 2017 .
  4. ↑ Joachim Jürgens: Blue Tower in Herten. (PDF; 4.7 MB) In: pro-herten.de. January 15, 2015, p. 15 , accessed July 29, 2017 .
  5. ↑ Blue Tower: Solar Millennium AG is broke. In: Hertener Allgemeine . December 21, 2011.