Material and Energy valorisation of waste in a Circular Economy

Computational Fluid Dynamics for improving large-scale woody biomass and Municipal Solid Waste combustion units

SINTEF Energy Research is involved in the project GrateCFD (Enabling optimum Grate fired woody biomass and waste-to-energy plant operation through Computational Fluid Dynamics, 2017-20) where a huge effort is made towards modelling large-scale combustion systems using Computational Fluid Dynamics (CFD).

GrateCFD, is a competence building project led by SINTEF Energy Research. It is 80 % financed by the Research Council of Norway and 20 % financed by a number of industrial partners, where fundamental knowledge about woody biomass and municipal solid waste and their degradation behavior and burnout in a hot environment is coupled with Computational Fluid Dynamic (CFD) tools. The overall aim is to develop CFD toolboxes that are able to simulate a wide range of combustion units, contributing to their improved energetic, environmental and climate performance through improved design and operational optimization.

Development of tools and guidelines

The objective of GrateCFD is development of CFD aided design tools and operational guidelines for optimum grate fired Biomass-to-energy (BTE) and Waste-to-Energy (WtE) plant operation through:

  • Model development and validation of: improved fuel/fuel bed and gas release models, heat-exchanger deposition models and reduced kinetics models (NOx)
  • Simulations: transient and steady state CFD simulations of BtE and WtE plants; and validation
  • Concept improvements: BtE and WtE plant case studies selection, setup, simulations and analysis, giving design and operational guidelines

In the project, substantial efforts are made regarding developing and validating the sub-models needed for describing and predicting the fuel conversion process; a conversion process that in practice is sustained by the hot surrounding environment. Hence, a direct coupling between the fuel conversion and the gas phase combustion is needed. Transient or dynamic combustion processes or phenomena are also important, for grate fired combustion plants due to feedstock or operational changes, causing emission peaks for example.

The level of details that could be implemented in such CFD toolboxes is vast; however, there will always be a trade-off between the level of details and computational time, or cost. Hence, it is very important to understand and consider the connected practical implications and constraints.

The project has a significant integrated educational activity, through PhD and postdoc candidates financed by the projects, and connected graduate students as well.

Together, the partners are working towards the Waste-to-energy circular economy future; a future which is influenced by many factors including political, legislative, societal, technological, economic and environmental. The results from GrateCFD is a significant contribution to the technological and environmental aspects connected to the core processes taking place in a WtE plant combustion chamber.

A significant further effort is needed to make todays WtE plants, the heart of the WtE value chain – that takes care of what is left after recycling/sorting, capable of meeting this challenging circular economy future. This requires a considerable and multifaceted effort, through the whole WtE value chain.

More information about the project and results, can be found on the project website:

R&D partners: Statkraft Varme AS, Oslo EGE, Returkraft AS, Vattenfall AB and Hitachi Zosen Inova AG, while the RTD partners are SINTEF Energy Research – Department of Thermal Energy, Norwegian University of Science and Technology (NTNU) – Department of Energy and Process Engineering and LOGE AB.

Funding: The project is a KPN-project (Competence building project for the industry) supported (80%) by The Research Council of Norway and 20% financed by a number of industrial partners.

Duration: 2017-2020

Budget: 24 M NOK

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Image: Simulation of a flow field around heat exchanger tubes