Energy Process Engineering

Hydrogen is an important energy source and reducing agent for chemical and metallurgical processes, as it contributes to the decarbonisation of various industry sectors, e.g. steelmaking, but also to mobility or production of synthetic hydrocarbons. Although no CO2 is emitted due to the utilisation of hydrogen, production processes with low CO2-emissions are necessary. The methane pyrolysis would be such a process. It refers to the generation of hydrogen from methane or rather natural gas, whereby methane is decomposed into hydrogen and solid carbon. Different process designs are possible for this purpose. Such routes have already been investigated in an exploratory project at Montanuniversitaet Leoben in cooperation with several chairs and industrial partners. Besides a comparably low energy requirement, also solid carbon being the by-product is a positive aspect of the methane pyrolysis. Carbon offers a wide range of possible applications, which are also being investigated within the research activities.

In the course of a program for hydrogen production at Montanuniversitaet Leoben, several chairs will cooperate to further advance the process development of methane pyrolysis. As a part of this collaboration also a joint pilot plant will be built, where the most promising process routes can be tested on a larger scale. For example, a liquid metal bubble column reactor and a plasma reactor will be set up. The chair of process technology and environmental protection takes on the product gas treatment for the pilot plant, which includes the removal of solid carbon as well as the separation of hydrogen and unreacted methane. In addition to these experimental investigations, modelling and simulation of the pyrolysis process are conducted. Specifically, CFD-simulations of a reactive bubbly flow in liquid metal are carried out in the research group energy process engineering.

In the project BioHeat the conversion of biomass (residues) such as waste wood or sewage sludge into high-temperature process heat is being investigated.

The BioHeat process consists of a dual-step biomass gasification producing syngas, which can subsequently be either directly combusted or transformed to SNG. SNG production necessitates finer gas cleaning steps to avoid catalyst deactivation. However, the advantage of SNG production is long-term energy storage and distribution within the existing natural gas grid. These to variants of syngas utilization will be thoroughly tested and compared within the project also in terms of its socio-economic impacts. A further focus point concerns the nutrient recovery from bed ashes of the gasification process to reduce disposal mass.

Catalytic methanation of syngas at VTIU Leoben:

The tasks of the project BioHeat will be jointly conducted by the Technical University Vienna, BEST Bioenergy and Sustainable Technologies GmbH, Wien Energie GmbH, Energy and Chemical Engineering GmbH, der Jagiellonian University Krakow and the polish plant construction company Danex. The transnational research project is funded via the ERA-NET initiative (Networking the European Research Area) in cooperation with FFG (Forschungsförderungsgesellschaft). The main focus of VTIU lies on the investigation of catalytic methanation in fixed-bed reactors of the gasification product gas. PhD student Andreas Krammer will manage the project for VTIU. After the successful completion of HydroMetha this is his second project with the focus on catalytic methanation including experimental and modelling approaches.

Motivation:

The achievement of the strict national and international climate targets for the years 2030 and 2040 form the motivation for the implementation of the project “Carbon to Product Austria (C2PAT)”. Companies with high carbon dioxide footprints need to avoid their emissions by modifying their current process procedures and adapting their energy sources or reducing them through innovative and new technologies. In the C2PAT project, companies from different industrial sectors, namely Lafarge Zementwerke GmbH, Verbund AG, OMV AG and Borealis AG, are working together to contribute to tackling the climate crisis.

Exhaust gases from cement plants contain high concentration of carbon dioxide. The production of cement relies naturally on an endothermal reaction and requires high-temperature heat of around 1,450°C for clinker formation in the rotary kiln. One third of emitted carbon dioxide stems from the provision of heat from fuels such as pieces of tires or plastic, while the remainder is released during the burning of the cement clinker from the fed limestone mixture.

Project implementation:

In the project “C2PAT” these unavoidable, process-related carbon dioxide emissions should be used as feedstock for renewable plastics production. At the Lafarge site in Mannersdorf am Leithagebirge (Lower Austria), CO2 will be captured from the waste gas of the cement plant by an amine scrubbing unit, and further processed in a newly erected power-to-liquid pilot (PtL) plant. Green hydrogen will be produced on site with the help of an electrolyzer, which is powered on the one hand by electricity from a newly constructed PV park near the cement plant and on the other hand will be fed with renewable power from the grid. Syncrude will be produced in a reverse water gas shift reactor with downstream Fischer Tropsch synthesis. The further treatment of the syncrude into various forms of plastic (polymers) will be done in co-processing at the nearby refinery. In addition to using carbon dioxide as feedstock, this project is also an example for a circular economy approach and sectoral cooperation among companies operating in different industrial sectors. The material flow from fired plastics through a carbon capture plant with synthesis and processing to renewable plastics in existing steam crackers is unique.

The annual capacity of the PtL pilot plant is designed for 10,000 tons CO2 obtained from the exhaust gas of the cement plant Mannersdorf am Leithagebirge. The pilot plant will be used to further develop critical parts of the value chain as well as process equipment, and prove a stable, long-term operation. The pilot plant is a preliminary project to analyze and support the interconnection between the cement plant and the energy supplier handling green power and the operation of the electrolyzer, as well as the chemical conversion to plastics. Furthermore, the cooperation of a large, cross-sectoral industry consortium is implemented in practice. This project shall provide the basis for the breakthrough to erect a scaled-up, industrial sized plant which captures the entire CO2 of Mannersdorf’s cement plant of about 700,000 tons annually.

Additional information: C2PAT

Natural carbonation, also known as silicate weathering, describes a process in which atmospheric CO₂ reacts with alkali and alkaline earth metals to form a carbonate. This process, which occurs in nature, takes place over a geological timescale and therefore has extremely slow reaction kinetics. The present research project deals with the acceleration of the carbonation process. Under optimized pressure and temperature conditions, the CO₂ absorption capacity of minerals containing metal oxides is investigated. In this process, the metal oxides (MO), predominantly magnesium or calcium oxide, are brought into contact with carbon dioxide as shown in reaction equation (1) to produce a carbonate (MCO₃). Carbonation represents an exothermic reaction, which is why additional heat is released during the formation of the carbonate.

MO + CO₂ → MCO₃ + Heat    (1)

Together with our project partner RHI Magnesita, the Montan University of Leoben is researching the carbonation potential of various minerals and secondary raw materials using direct aqueous carbonation. In this process, a carbonation reaction is enabled with the addition of water and the CO₂ uptake is accelerated by adjusting various parameters such as temperature, CO₂ partial pressure, particle size or even the use of additives. The laboratory set-up used is a batch process in which solid material and water are added to the reactor. The reactor is then sealed, heated, and a pure CO₂ gas stream is injected after the desired temperature is reached. A carbonation reaction then takes place under these elevated pressure and temperature conditions. The finished product is removed and analyzed after completion of the experiment.

In the project „Innovation Flüssige Energie“ (IFE) a system for the highly efficient generation of CO2-neutral synthetic fuels is being designed and subsystems are being developed. A Solid Oxide Co-Electrolysis (Co-SOEC) is combined with an efficient CO2 extraction and a Fischer-Tropsch (FT) process. The plant produces synthetic diesel, naphtha, and waxes from water and carbon dioxide. The SOEC is operated as co-electrolysis which generates H2 and CO in one process step. Together with the thermal coupling of the Co-SOEC and the FT process, a significantly higher degree of efficiency can be achieved compared to alkaline and PEM low-temperature electrolysis and downstream FT processes.

The system is designed for a maximum electrical input power of 1 MW, which enables the production of about 500,000 litres of synthetic fuel per year. The research focus for VTiU is on the assessment and selection of an appropriate CO2 extraction method as well as on the establishment of a process concept for upgrading the Fischer-Tropsch products.

Further information: iwo-austria.at/innovation-fluessige-energie

The urgent need for reducing CO₂ from anthropogenic sources creates the necessity of developing new systems and/or readjusting current ones. The intention of this project is the inclusion of waste gas streams from energy intensive sources (typical from the petrochemical, steel or refractory industry) being rich in CO₂ into reforming processes in order to produce syngas. Due to the complexity of the processes, plenty emission points are available as CO₂ input for the reforming. The largest CO₂ emission sources in the steel industry are the blast furnace (BF) accounting for 65% of the overall emissions, the coke plant and the sinter plant with 27% and 6% respectively. In the case of petroleum refineries, furnaces and boilers are responsible of 65% of the emissions, whereas for the catalytic cracker or gasifier the emissions account for 16%.For the refractory industry, 70% of the CO₂ emitted is bounded to the treatment of the raw materials and less than 20% come from the thermal energy required in the process.

In the “Tri-Reforming” project, CO₂ is catalytically converted to synthesis gas by addition of methane and steam resulting in varying CO/H₂ ratios. The CO₂ is not captured from the exhaust gases but the exhaust gas is directly reformed. In the catalytic reactor, steam reforming, dry reforming and partial oxidation are taking place simultaneously. By adding steam and methane, the inert gas share is significantly diluted in the product gas. For the experimental investigation of the reforming process, a new laboratory plant will be erected and operated.

In the European Union, 25 Million tons of plastic waste is generated annually, whereby about 40 % are ephemeral packaging waste. In order to reduce fossil resources and to enable the required recycling rates, the ReOil process is an attractive option for feedstock recycling of plastic waste by pyrolysis. In the process also contaminated and mixed plastic waste fractions can be exploited for which a classical mechanical recycling is not possible. Polymer waste is heated up to temperatures above 400°C in inert atmosphere resulting in thermal cracking of the polymer chains. The derived product has properties of a synthetic crude oil which can be further processed in existing refinery infrastructure to petrochemical products, feedstock for polyolefin and fuels.

We work on the further development, the optimization and the scale-up of this process as co-operation partner of industry. Main focus is given to the potential feedstock and its preprocessing, the influencing parameters for operation and on the product spectrum, and particularly the reaction mechanisms as well as the kinetic of the thermal crack process. Beside experimental work on laboratory and pilot plants, model building and simulation are applied.

Further information:

Schubert, T., Lechleitner, A., Lehner, M., & Hofer, W. (2019). 4-Lump kinetic model of the co-pyrolysis of LDPE and a heavy petroleum fraction. Fuel, 116597. doi: 10.1016/j.fuel.2019.116597

Schubert, T., Lehner, M., Karner, T., Hofer, W., & Lechleitner, A. (2019). Influence of reaction pressure on co-pyrolysis of LDPE and a heavy petroleum fraction. Fuel Processing Technology, 193, 247-211. doi: 10.1016/j.fuproc.2019.05.016