Power Plant Technology and Power Engineering


Staged air injection reduces peak temperatures in the primary combustion zone (low NOx production) and enables a good mixture of unburned species in the primary combustion zone. This ensures that most of the unburned species are burned in the secondary air injection zone.

The design of the secondary air inlet nozzles is essential for the optimal operation of the plant. In some cases, wrong design of the nozzles can lead to unwanted flows and to possible damages.

CFD simulations make developing effective secondary air nozzles during design and engineering of the plant possible. CFD simulations show detailed information about the penetration length and the mixture of the secondary air with the primary flue gas. CFD simulations are by far the cheapest and most efficient tool to identify and solve problems concerning the flow field in combustion chambers.

ENRAG has got the knowhow to use CFD simulations as an efficient tool and is the ideal partner for your project.

We are happy to discuss your concerns. For any information on CFD simulations in general and grate furnaces for municipal waste incineration or biomass furnaces, do not hesitate to contact us.



Grate Stoker Furnaces

The combustion of solid fuels using grate stoker furnaces is used today for municipal solid waste incineration and for biomass combustion. The combustion of solid fuels with a grate stoker furnace comes along with some technical challenges. The combustion of municipal solid waste is difficult to control due to the inhomogeneity of the waste.

Modeling and simulation of grate furnaces is challenging and should be performed by experts. The combustion of the solid fuel must be modeled using special tools which have to be connected to the CFD simulation of the boiler.

ENRAG has got the knowhow and the experience in modeling and simulating grate furnaces for municipal solid waste combustion plants and biomass plants. ENRAG provides high quality simulations with highest accuracy and reliability.








Combustion Systems

Combustion systems in power plants or facilities are wide spread and state of the art technology. Combustion is the basis of many different industrial processes and the combustion of (fossil) fuels contributes by far the biggest part of today’s power supply.

The modeling of the oxidation of fuels (gaseous, liquid, solid) and thus the modeling of the flame as the place where combustion takes place is complex and time consuming.


Even the phenomena when simulating gaseous fuel combustion are quite complex and time consuming:

  • Normally the fluid flow in industrial combustion systems is turbulent.
  • During combustion (inside the flame) the fundamental fluid properties like density, viscosity, specific heat, etc., as well as the composition are changing.
  • During combustion many elementary reactions take place simultaneously, forming and decomposing short-lived reactive radicals.
  • Even the simple combustion of hydrogen with oxygen (H-O system) requires 37 reactions for a detailed model.
  • Besides chemical reactions, combustion is driven by all types of heat transfer (convection, conduction and radiation including gas phase radiation) and changes in density.
  • Additionally, air pollutants are produced inside the combustion zone.


Therefore it is often necessary to make some simplifications to be able to solve the problem with tolerable efforts on the one hand and to ensure high quality results that matching the reality on the other hand. These simplifications and their application to industrial size combustion systems require extensive knowledge and years of experience.

The design of industrial combustion systems is normally based on trial and error. Computational fluid dynamics (CFD) simulations offer the first real opportunity in history to have a look into combustion zones and are ideal for combustion engineering. CFD simulations enable engineers to test and validate even complex burner systems during the designing and engineering phase. Thus it is possible to see and solve potential problems even before combustion systems are constructed or in operation.


Computational fluid dynamics (CFD) simulations provide a much better insight into industrial combustion systems than any other technologies of modeling or measurements. It is possible to get information on temperature distribution, species concentrations, velocity distribution, heat transfer and the mixture of fuel and oxidizing fluid.

ENRAG’s employees have several years of experience in the field of combustion modeling and are therefore able to provide high quality CFD simulation of combustion and gasification systems.

For more information feel free to contact us (Contact, office@enrag.at, +43 7674 21103).