FeedWaterTank L3

Created Monday 10 June 2013


A feedwater tank model with non-ideal phase separation depending on the filling level. Appropriate when a higher precision during transients is needed. Ports for venting and auxiliary condensate inputs are supported.

1. Purpose of Model

In most cases the degasification of the feedwater is integrated in the feedwater storage tank. There are two main concepts for degasification. For small and medium capacities trickling deaerators are common, see left illustration below. In this type the condensate trickles through a structured or unstructured package or through a set of trickle plates thus increasing the condensate's surface allowing the gas to be dispensed from the liquid. For large capacities this enhancement of the liquid surface is achieved by spraying the condensate into the vessel.
Both types can be modelled with this component model. The characteristics of the heat and mass transfer between the liquid and vapour phase are defined in both cases by varying the parameters in the parameter dialogue's tab "Phase Separation".

The model suits well if high transients with temporary subcooling or two-phase states in the liquid and vapour phase can not be ruled out. If the precise transients in the tank are not of interest the less complex model FeedWaterTank L2 is recommended. A typical source of high-transients in tanks are short term changes of tapping mass flows, e.g. applying condensate stop for primary control.

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 L3 because the system is modelled with the use of balance equations applied to two distinct zones, i.e. the vapour volume and the liquid volume.

2.2 Physical Effects Considered

2.3 Level of Insight


Heat Transfer

Pressure Loss

PhaseSeparation

RealSeparated: non-ideal phase separation, state at ports depend on filling level and state of the distinct zones.

3. Limits of Validity


4. Interfaces


5. Nomenclature

6. Governing Equations


6.1 System Description and General model approach


6.2 General Model Equations

The heat losses to the ambient are calculated as follows

Summary

A summary is available including the following:


7. Remarks for Usage

8. Validation


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

- optional insulation and heat losses
- propagated mass struc, added cylinder's top and bottom wall mass
- propagated initialisation for wall - Timm Hoppe, XRG Simulation


Backlinks: ClaRa:Basics:ControlVolumes:FluidVolumes:VolumeVLE L3 TwoZonesNPort