FlameRoomAdditionalAir L2 Static

Created Friday 28 June 2013

A 0d-flame room model with stationary mass and energy balance regarding heat exchange with neighbouring furnace models and boiler casing walls.

1. Purpose of Model


This model is well suited to model the flame room areas of a boiler. In combination with Hopper_L2, Burner_L2_Static and FlameRoomWithTubeBundle_L2_Static models a 1-dimensional boiler model could be achieved which is discretised in flow direction. Radiative and/or convective heat transfer between linked furnace models or boiler casing walls can be calculated using replaceable models. In addition to the FlameRoom_L2_Static model, here additional air can be considered by an additional flugas/fuel connector.

2. Level of Detail, Physical Effects Considered and Physical Insight


2.1 Level of Detail

Referring to Brunnemann et al. [1], this model refers to the level of detail L2.

2.2 Physical Effects Considered


idealised combustion with the flue gas composition and the elemental composition and the lower heating value of the burnt fuel

2.3 Level of Insight


Heat Transfer


The following listed heat transfer models are the recommended ones. Of course other (e.g. generic ones: Generic HT) heat transfer models could be chosen.

top (radiation to neighbored furnace volumes)

wall (radiation or convection to boiler casing walls) :


Pressure Loss

No pressure losses are considered.


The following replaceable models are used to model the combustion of fuel inside the different furnace volume models. The model for the chemical conversion of fuel can be chosen with the replaceable model ChemicalReactions. The models BurningTime and ParticleMigration are used to calculate the amount of fuel burned inside the current furnace volume. If the preset burning time is lower than the time span for the fuel particles needed to travel though the current furnace volume, the complete amount of fuel is burned inside this component. If the burning timer is higher than the particle migration time, unburnt fuel is entering the following downstream furnace model.

Chemical Reaction

Burning Time

Particle Migration

3. Limits of Validity

4. Interfaces


4.1 Physical Connectors


Basics:Interfaces:FuelSlagFlueGas inlet inlet
Basics:Interfaces:FuelSlagFlueGas outlet outlet
Basics:Interfaces:FuelFlueGas inlet fuelFlueGas_inlet

Basics:Interfaces:HeatPort a heat_top
Basics:Interfaces:HeatPort a heat_bottom
Basics:Interfaces:HeatPort a heat_wall

4.2 Medium Models

5. Nomenclature


6. Governing Equations


6.1 System Description and General model approach

This model is used to build up furnace models with 1-dimensional discretisation and is used together with other models of the furnace package.

The following sketch shows the modelling principle of the component. The flows of fuel and flue gas are mixed separately before being processed inside the bulk zone with stationary energy and mass balance. The amount of burned fuel takes the particle migration time and the burning time from the replaceable model BurningTime into account. The lower heating value of the fuel can either be set in the parameter dialog or is calculated from the fuel's elementary analysis according to the "Verbandsformel" from [?]. Based on the elemental composition of the used fuel and a generalised ideal fuel combustion, the formation enthalpy is calculated to be considered in the energy balance.
All chemical reactions are calculated inside the replaceable model CoalReactionZone which determines the resulting flue gas mixture according to a combustion calculation and fixed parameters for the produced amount of CO and NOx, as well as the fraction of ash turned into slag. The slag moves through the furnace models in reverse direction (downwards). The slag outlet temperature is given by a parameter.

The component exchanges heat flows with up- and downstream models (via the heat ports heat_top and heat_bottom) as well as the surrounding walls (heat_wall) which are calculated with replaceable models for heat transfer correlations. If radiative heat transfer correlations are used inside a 1-dimensional discretised (sequential model arrangement) furnace, radiative heat flows are exchanged between the directly connected models (via heat ports top and bottom) and the surrounding walls (heat port wall). The calculation is performed with view factors which are calculated inside the heat transfer correlations. The following sketch shows the modelling principle for radiative heat transfer between the sequential arranged volumes and the calculation formula for the view factor. The amount of emitted radiation is calculated for a three dimensional volume, but the radiative heat flow between the models is assumed to be exchanged between two flat surfaces with the size of the furnace cross sectional area.

No backflow inside this model is considered. For correct calculation of backflows please use FlameRoomAdditionalAir _L2_Advanced with dynamic mass balance.

6.2 General Model Equations


The equation system of this component equals the one from FlameRoomAdditionalAir _L2_Advanced except the dynamic mass and energy balance of the flue gas. The mass balance of this Burner_L2 is not affected by ther thermal expansion thus the dynamic expression is missing.

The energy balance is carried out stationary too.

The rest of the equation system equals FlameRoomAdditionalAir _L2_Advanced.

Summary

A summary record is available which bundles important component values.


7. Remarks for Usage


8. Validation

The adiabatic outlet temperature of this model has been validated with Ebsilon calculations at identical boundary conditions.

The image below shows the flue gas temperatures over the furnace height. As can be seen there is a good compliance with the design values.

9. References

[1] Johannes Brunnemann and Friedrich Gottelt, Kai Wellner, Ala Renz, André Thüring, Volker Röder, Christoph Hasenbein, Christian Schulze, Gerhard Schmitz, Jörg Eiden: "Status of ClaRaCCS: Modelling and Simulation of Coal-Fired Power Plants with CO2 capture", 9th Modelica Conference, Munich, Germany, 2012

10. Authorship and Copyright Statement for original (initial) Contribution

Author:
DYNCAP/DYNSTART development team, Copyright 2011 - 2022.
Remarks:
This component was developed during DYNCAP/DYNSTART projects.
Acknowledgements:
ClaRa originated from the collaborative research projects DYNCAP and DYNSTART. Both research projects were supported by the German Federal Ministry for Economic Affairs and Energy (FKZ 03ET2009 and FKZ 03ET7060).
CLA:
The author(s) have agreed to ClaRa CLA, version 1.0. See https://claralib.com/pdf/CLA.pdf
By agreeing to ClaRa CLA, version 1.0 the author has granted the ClaRa development team a permanent right to use and modify his initial contribution as well as to publish it or its modified versions under the 3-clause BSD License.

11. Version History