Dear reader
The GAFT project is closing in on the end. We have had our last steering committee meeting on November the 29th. We also arranged a workshop a day before the SC meeting where most of the results from the final year's deliverables were disseminated.

We have also informed the steering committee about the challenges that we have faced with the newly constructed entrained flow reactor. This installation is now on the verge of being fully operational and we are hoping to start an initial experimental campaign early next year. The deliverables dependent on an operational entrained flow reactor have unfortunately been delayed. We therefore have applied to the Research Council of Norway for a project period extension of 6 month, which has now been approved.

This period will be used to finalize all deliverables connected to the gasification reactor. The results will be presented to industry partners at an additional workshop that will be held in Trondheim before the summer of 2019. This will give us the opportunity to present a work that the industry is very much interested in and at the same time keep in touch with a consortium that have similar interest as SINTEF concerning future energy systems.

Progress update on entrained flow gasification

Experimental work

Reactivity of products of incomplete gasification in a pressurised TGA
The objective of this task is to study the effect of conditions on decomposition behaviours and reaction kinetics of incomplete gasification residues from the entrained flow gasifier. Experimental methods were developed and established for studying gasification behaviours of incomplete gasification residues (mainly soot) under different concentrations of reactive gases and pressures. Carbon nano-powder acquired from Sigma-Aldrich (purity > 99.99 %, particle size < 150 nm) is used as a reference material in the current work.

The figures below show differential weight loss curves of the reference carbon powder under increasing CO2 concentrations (left) and pressures (right). It shows clearly that the weight loss of the carbon powder is shifted to lower temperatures with increasing CO2 concentration. Increasing pressure has similar promoting effects on gasification of the carbon powder towards CO2, as it decomposes faster at lower temperature. The kinetic evaluation results revealed that high pressure causes change of activation energy of the studied carbon powder. The results indicate that increase of pressure can be an efficient way to enhance the fuel conversion rate during biomass gasification. However, gasification of carbonaceous material at both high temperature and pressure conditions is complicated. More detailed and complementary analysis of the studied samples are needed to provide extended information for improved interpretation of the obtained results.
DTG curves of reference carbon nanoparticles obtained at different CO2 concentrations and pressures.
SNG quality assessment at Ecopro
SINTEF Energy Research together with SINTEF Industry have now performed two measurement campaigns for the assessment of the gas quality at Ecopro. The measurements performed the second time showed no signs of impurities when it comes to siloxanes, water, ammonia and hydrogen sulphide content in the gas. This was also the case during the first campaign. The methane content in the gas during the second measurement was even better (higher) compared to the first campaign. A third and last measurement is planned in early 2019.
SINTEF on-site at the Ecopro biogas plant in Verdal, the picture shows the sampling point from the process with the CO2 removal unit in the background.
Entrained flow reactor status
A lot of work has been carried out lately to get the reactor ready for the experimental campaigns that are now planned for early 2019. A list of completed and planned activities for 2018 can be found below:

  • all leakage tests (8-9 bars)
  • Low and high heat-up tests
  • Established location of reactor hot-spots (max 150 °C) and installed proper cooling
  • Installed high capacity N2 tank
  • Gas sampling system upgraded and tested (FTIR/GC/ELPI)
  • Upgraded rotameters (shutdown safety) installed and tested
  • Last corrections in the LabView control software
  • Repair the oil leakage from screw-feeder gearbox
  • Setup new electrical connection for the feeding screw
  • Test feeding system after reparation
The control room for the gasifier, overlooking the reactor in the background
Upscaling experiments
An experimental campaign on gasification of pulverised stem wood pellets of pine and spruce have been performed at RISE ETC. The pellets were pulverised in a hammer mill and sieved afterwards to a maximum particle size of 0.75 mm. The gasifier operated at atmospheric pressure with air as the gasification medium. Approximately 20 kg/h of fuel (100 kW) was used during the experiment with lambda being set to 0.55. Gas measurements were performed using a combination of a FTIR (Fourier-Transform Infrared Spectrometer) and a GC (Gas Chromatograph). In addition, an ELPI (Electrical Low-Pressure Impactor) was used to measure the particle numbers and size distribution.

A similar experiment will be run at SINTEF at a lower reactor capacity (15 kW). The small-scale experiment will be performed with the same fuel and at the same temperature as the large-scale experiment. The temperature in the small-scale reactor is easily controlled through electrical heating rods that are permanently installed around the reactor core. This setup will allow to run similar experiments where the only main variable is the residence time of the particles inside the reactor. This will give a unique opportunity to study the effect of residence time on the gasification reactivity of the particles.
A schematic drawing and a picture of the pilot scale entrained flow gasification installation at RISE ETC in Piteå, Sweden

Modelling work

Progress update on gasification modelling (Ph.D. work)
The Ph.D. work continues to simulate entrained flow gasification of pulverized biomass with the assumption that pulverized biomass particles are spheroidal. A study has been conducted to investigate the modelling difference among the traditional sphere approach, the simplified non-sphere approach and the new spheroid approach by simulating a non-reactive entrained flow gasification process. By comparing the simulation results of particle velocity in axial, radial and tangential directions, it has been found that the new spheroid approach predicts more dispersed particle residence time and local concentrations. These findings have been reported in a manuscript with the title “Eulerian-Lagrangian simulation of pulverized biomass jet using spheroidal particle approximation”, which has been published in Fuel. In addition, the work was also presented in the format of poster at the 37th International Symposium on Combustion in Dublin.

Based on the results from the aforementioned paper, it is reasonable to assume that the new spheroid approach may have implications also under reactive conditions. Therefore, an experimental campaign has been carried out in cooperation with Luleå University of Technology in Sweden to produce experimental data to validate the CFD simulations. Several experiments were conducted using a flat flame burner under different operating conditions. In addition, reactive simulations are planned to investigate the effects of different particle models under reactive conditions. The work is expected to be presented the 17th International Conference on Numerical Combustion in Aachen in 2019.
Illustration of the flat flame burner reactor.
Progress update on Fischer-Tropsch testing
During the GAFT project, the effect of different BTL (Biomass to liquid) process conditions was tested on several cobalt and iron-based Fischer-Tropsch catalysts. Normally, cobalt catalysts are preferred for FTS (Fischer-Tropsch Synthesis) but it is not clear that this is true for all BTL processes. Therefore, for H2/CO <1 further and extra focus was put on one of the iron-based catalyst at medium to high reactor temperatures>
A kinetic model was chosen and parameters describing this catalyst in the current FTS reactor system was established. The GAFT project has led to increased understanding of the FTS in BTL operations with low H2/CO and at low to medium temperatures. Based on all findings from the project, one article has been already published and another one will be published in 2019.
A picture of the reactor setup that has been used for studying the different Fischer-Tropsch catalysts.
Progress update on value-chain analysis (Challenges to achieve the 2050 target for decarbonization of the transport sector)
The techno-economic evaluation study in GAFT has now been finalized. A report and a journal publication are under preparation as part of the final deliveries in this sub-project. The value chain that has been analyzed takes into account the co-processing of biomass and MSW sludge in an entrained flow gasifier coupled to a FT-synthesis process for the production of a product high in wax that is refined further to numerous liquid and gaseous biofuels in existing refineries. All important aspects of the value chain such as transport costs, pre-treatment (torrefaction), gas cleaning and CO2 separation and storage have been considered. The data has been evaluated using three important indicators:
  1. Feedstock to biofuels energy efficiency (J/J)
  2. Cost of biofuels production ($/liter)
  3. GHGs reduction (%)
In addition, a sensitivity analysis on several uncertain parameters has been performed. Also, numerous different scenarios that were thought to have a significant impact on the biofuels price were evaluated. For example, the choice of plant location, decentralized pretreatment step (torrefaction) vs centralized and energy integrated pre-treatment are among the factors that have been evaluated. The economic model evaluated also two business cases that are relevant for Norway, the Tofte and the Follum case.

The conclusions so far are as follows:
  • The economy of wood to biofuels is very dependent on wood price and logistics of supply
  • Decentralized torrefaction leads to higher biofuels production cost
  • Introducing torrefaction gases to the entrained flow gasification process improves feedstock supply cost and biofuels production cost
  • Co-processing with sludge is beneficial above 50 $/ton
  • Including CCS improves biofuels production cost above
    - 30 $/ton_CO2 using only wood
    - 70 $/ton_CO2 using sludge addition (25% sludge at 100 $/ton)
  • Upgrading at refinery leads to 10-15% lower biofuels production costs
A graphical breakdown distribution of the biodiesel production costs showing the main contributors to the final fuel price. Major contributors: feedstock supply, insurance and taxes, syngas production and conditioning, landsite preparation and buildings and contingency

Calendar of events

There are several new events on the GAFT event list that is published on the project website.


GAFT project manager: Roger Khalil
Feedstock pretreatment: Liang Wang
Fischer-Tropsch synthyesis: Rune Myrstad
Gasification: Morten Seljeskog
Value-chain analysis: Gonzalo del Alamo
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