GPT - Thermo-Chemical Processes Group Instituto Universitario de Investigación en Ingeniería de Aragón. Universidad de Zaragoza
Laboratory scale pyrolysis plant
This set-up is a laboratory-scale plant (<1 kg/h) operating at atmospheric pressure, with continuous feed of solids, a fluidizing gas and equipped with a continuous ash removal system. The sloping inlet is refrigerated with air in order to avoid the reaction taking place uncontrolled before the reactor. This air, only serving as a refrigerant, does not come into contact with the raw material. The fluidized bed reactor is made of refractory steel (AISI 310), with an inner diameter of 38 mm and a height of 800 mm. The bed height is kept at 150 mm by means of a concentric tube of 12 mm diameter passing through the distributing plate, enabling the bed material to overflow and be collected in a solid vessel. This ash removal system is very useful for materials with a high ash content as it prevents an increase in the bed height.
Usually nitrogen (pyrolysis), or air (gasification), are used as fluidizing gases, depending on the thermochemical process which is applied. Usually, two-thirds of the fluidizing gas is introduced through the distributing plate in order to fluidize the bed, while the rest of the flow is fed into the reactor with the solid feed in order to facilitate its entry. The fluidizing flow rate is controlled by a mass flow controller and the gas production (first trial) is measured by a volumetric gas meter.
The reactor is heated by an electrical furnace with three heating zones (bed, free-board, and cyclone), which could be independently controlled. A hot filter is placed after the cyclone to remove the smaller particles. The liquid recovery system is located after the heated filter. This system can be composed of different configurations depending on the thermochemical process, including cooled condensers, scrubbers, electrostatic precipitators, cotton filters, etc.
Furthermore, a tubular fixed bed reactor made of AISI 310 steel (length = 25 cm, inner diameter = 5.4 cm) can be attached downstream the reactor in order to do a catalytic post-treatment of the vapours. The vapours flow from the top of the fixed bed reactor to the bottom section. The available length of catalyst bed is between 0-15 cm. This reactor is heated with electrical resistances and its temperature controlled using appropriately placed thermocouples and a PDI controller
The production of non-condensable gases is measured by a volumetric gas meter. The gas composition is determined by means of a micro-gas chromatograph (micro-GC; Agilent G2801A) connected online. Mainly, sewage sludge has been used as raw material in this set-up whether in torrefaction, pyrolysis or gasification processes. Other raw materials depending on its particle diameter and fluid-like properties could be used in this set-up.

Tech. Spec.

  • Feeder: Solid feed rate ; 0.1-16 g/min.
Solid feed rate per volumetric unit; 0.005-0.9 kg/ s m3.
  • Gas flow rate: 0.1-8 dm3 (NTP) / min.
  • Hopper: 4 dm3 (capacity).
  • Oven: Maximum Bed Temperature limit 850 ºC.
Electrical resistance: 800-1100 W.
  • Maximum fixed bed temperature limit: 550 ºC.
  • Maximum hot filter temperature limit: 550 ºC.

Research projects

Research Project CTQ2004-05528-PPQ.
Energy and environmental optimization of the gasification process of sewage sludge from wastewater treatment plants.
Main researcher: María Benita Murillo Esteban
Research Project CTQ2007-66885-PPQ.
Optimization of sewage sludge valorization by thermochemical processes of pyrolysis and gasification.
Main researcher: María Benita Murillo Esteban
Research Project CTQ2010-20137/PPQ.
Sewage Sludge valorization by means of pyrolysis: study and improvement of the applicability of their products.
Main researcher: Gloria Gea Galindo.


Manyá, J.J.; Sánchez, J.L.; Ábrego, J.; Gonzalo, A.; Arauzo, J. (2005). Air Gasification of Dried Sewage Sludge in a Fluidized Bed: Effect of the Operating Conditions and In-Bed Use of Alumina. Energy & Fuels, 19, 629-636.

Manyá, J.J.; Sánchez, J.L.; Ábrego, J.; Gonzalo, A.; Arauzo, J. (2006). Influence of gas residence time and air ratio on the air gasification of dried sewage sludge in a bubbling fluidised bed. Fuel 85 2027–2033.

Manyà, J.J.; Aznar, M.; Sánchez, J.L.; Arauzo, J.; Murillo, M.B. (2006). Further Experiments on Sewage Sludge Air Gasification: Influence of the Non-Stationary Period on the Overall Results. Industrial & Engineering Chemistry Research, 45, pp. 7313−7320.

Aznar, M.; González, E.; Manyà, J.J.; Sánchez, J.L.; Murillo, M.B. (2007). Understanding the effect of the transition period during the air gasification of dried sewage sludge in a fluidized bed reactor. International Journal of Chemical Reactor Engineering, Vol. 5, Article A18.

Fonts, I.; Juan, A.; Gea, G., Murillo, M. B.; Sánchez, J. L. (2008). Sewage sludge pyrolysis in fluidized bed, 1: Influence of operational conditions on the product distribution. Industrial & Engineering Chemistry Research 47(15), 5376-5385.

Aznar, M.; Manyà, J.J.; García, G.; Sánchez, J.L.; Murillo, M.B. (2008). Influence of freeboard temperature, fluidization velocity and particle size on tar production and composition during the air gasification of sewage sludge. Energy & Fuels, 22, pp. 2840−2850.

Fonts, I.; Juan, A.; Gea, G., Murillo, M. B.; Arauzo, J. (2009). Sewage Sludge Pyrolysis in a Fluidized Bed, 2: Influence of Operating Conditions on Some Physicochemical Properties of the Liquid Product. Industrial & Engineering Chemistry Research 48(4), 2179-2187.

Fonts, I.; Azuara, M.; Lázaro, L.; Gea, G.; Murillo, M. B. (2009). Gas Chromatography Study of Sewage Sludge Pyrolysis Liquids Obtained at Different Operational Conditions in a Fluidized Bed. Industrial & Engineering Chemistry Research 48(12), 5907-5915.

Fonts, I.; Azuara, M.; Gea, G.; Murillo, M. B. (2009). Study of the pyrolysis liquids obtained from different sewage sludge. Journal of Analytical and Applied Pyrolysis 85(1-2), 184-191.

Aznar, M.; San Anselmo, M.; Manyà, J.J.; Murillo, M.B. (2009). Experimental Study Examining the Evolution of Nitrogen Compounds during the Gasification of Dried Sewage Sludge. Energy & Fuels, 23, pp. 3236−3245.

European Comission Brisk
The Thermochemical Processes Group (GPT) is partly funded by the EU's European Social Fund and by the Gobierno de Aragón (Aragonese government)
EU's European Social Fund Gobierno de Aragón