Schlussbericht
(Deutsch)
|
Vor Beginn des Projekts wurden in Voruntersuchungen Messungen an einer einstufigen absatzweise betriebenen Versuchsanlage mit direkter katalytischer Verflüssigung durchgeführt. Diese Messungen liessen eine hohe Ausbeute an Pyrolyseöl mit Diesel ähnlichen Eigenschaften erwarten, waren jedoch insbesondere wegen des Batch-Betriebs mit grossen Unsicherheiten behaftet. Ziel des vorliegenden Projekts war die Realisierung einer kontinuierlichen Technikumsanlage und die Validierung einer hohen Ausbeute an als Diesel ähnlichem Flüssigöl. Die Ausbeute sollte sicher höher als 50% mit einem Zielwert von über 60% bezogen auf die zugeführte Energie erreichen.Im Projekt wurde eine kontinuierliche Versuchsanlage realisiert, in welcher in einem ersten Reaktor eine Pyrolyse stattfindet, welche Eigenheiten der schnellen und der ablativen Pyrolyse verbindet. Anschliessend ist eine Konversion der hochmolekularen Verbindungen in einem mit Katalysator und schwersiedendem Öl betriebenen Crackreaktor vorgesehen, danach werden die Gase direkt in eine Rektifikationskolonne geleitet, aus der eine Abtrennung der Flüssigfraktion mit Diesel ähnlichem Siedebereich erfolgt, während der Sumpf in den Crackreaktor zurückgeführt wird.
Auftragnehmer/Contractant/Contraente/Contractor:
Verenum
Autorschaft/Auteurs/Autori/Authors:
Good,Jürgen
Nussbaumer,Thomas
Ott,Hanspeter
Zugehörige Dokumente
|
Schlussbericht
(Englisch)
|
Prior to the present project, preliminary tests on the direct catalytic liquefaction of biomass in a singlestep reactor have been performed in a batch-wise operated test bench enabling promising, but uncertain results with respect to the potential yield of liquid fuel. The target of the present project was to validate the high yield of liquid fuels by a revised concept combining the characteristics of ablative and fast pyrolysis, a catalytic cracking of heavy tars in a secondary reactor, and a subsequent direct distillation of the high molecular product gas. For this purpose, the test-bench plant was extended to a continuously operated plant for a fuel throughput of 20 to 100 kg per hour with the target to confirm the capability of a direct conversion of biomass into a liquid fuel with similar fuel properties as Diesel and with high energetic yield, i.e. certainly > 50% with a target of > 60%.
The operation parameters such as temperatures and mass flows were measured to derive experimental data of the product yield and to calculate the mass and energy balances during stationary operation. During several test runs, the plant was operated with dry saw dust at a typical pyrolysis temperature of app. 480°C without addition of catalyst to the secondary reactor. Further, the gaseous products such (CO, CH4, H2, CO2) were continuously analysed during the tests. The liquid products, i.e., product fractions with boiling temperatures corresponding to gasoline and Diesel, were planned to be investigated by chemical analyses in order to check their suitability as transportation fuel with respect to fuel specification EN 590. During the test runs, the fuel throughput was lower than expected and a stationary operation was enabled during few hours, i.e. up to maximum 8 h, only which did not enable an final assessment during real steady-state operation. Consequently, the measurement of mass flows and results on mass balance and energy balance exhibit high uncertainties. However, the evaluation of the results show, that the target yield of liquid fuel with similar boiling point as Diesel was not achieved and estimated to be app. 20% based on energy input only, while roughly 60% of the energy content was found in the highly volatile pyrolysis gas and the rest in the pyrolysis coke.
It is assumed, that neither the needs for fast pyrolysis with high convective heat transfer in the bed nor the conditions for efficient ablative pyrolysis can be achieved in the presented concept of pyrolysis, thus resulting in an insufficient heating rate leading to a conversion to highly volatile gases instead of high molecular condensable organic compounds. The conversion to light gases may be further promoted by catalytic cracking on solid coke available in the reactor and on the filter for coke removal. Furthermore, the principle of subsequent direct distillation may be responsible for a further conversion into gaseous products, since pyrolysis oil is thermally instable mainly due to its high oxygen content.
Since the target yield of liquid product set as a milestone was not achieved by the investigated process, the project was not continued.
Auftragnehmer/Contractant/Contraente/Contractor:
Autorschaft/Auteurs/Autori/Authors:
Good,Jürgen
Nussbaumer,Thomas
Ott,Hanspeter
|
