SteamSeparatorVLE L3

Created Freitag 12 Februar 2016

An advanced model of a steam separator like a steam cyclone or a start-up vessel.

1. Purpose of Model

This model is suitable for steam separators of all sizes like cyclones and for cases where the mass storage capacities of the components are of relevance. Thus, a filling level is calculated which influences the separation behaviour. This is especially the case in abnormal operation conditions (e.g. completely filled component).

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 dynamic balance equations for the steam and liquid volume in the component.

2.2 Physical Effects Considered

non-ideal steam separation featuring limited mass and heat transfer
pressure loss in the component

2.3 Level of Insight

PhaseSeparation

RealSeparated: non-ideal phase separation, state at ports depend on filling level and state of the distinct zones, inlet flow is allocated in corresponding zone (final parameter absorbInFlow=1).

Pressure Loss

3. Limits of Validity

separation processes are based on density differences. Thus, with increasing pressures the efficiency decreases. This is not considered in the model which leads to an decreasing steam quality at the liquid outlet (outlet2) at increasing pressures.
no heat losses to the environment

4. Interfaces

5. Nomenclature

— no model-specific nomenclature —

6. Governing Equations

6.1 System Description and General Modelling Approach

The model instantiates an VolumeVLE L3 TwoZonesNPort with non-ideal phase separation as described above. The different phases are balanced separately.

The incoming mass flow rate is allocated in the zone of the inlet port. The separation behaviour is achieved with small time constants for condensation. Thus, we have a fast transition of the liquid mass flow from the vapour volume to the liquid volume.

7. Remarks for Usage

The default values of the parameters in the parameter dialog tab "Phase Separation" are chosen in such a way that a reasonable separation behaviour is achieved. Adjust these parameters carefully as a completely different behaviour will be reached if these parameters are chosen badly.
According to [2] the steam quality at outlet1 is expected to be 0.96 at 60 bar and decreasing to 0.90 at 180 bar. Steam quality at the liquid outlet2 are expected to be approximately 0.01 and 0.06 at 60 bar and 180 bar, respectively. This behaviour that reflects decreasing density differences of water and steam at higher pressures is not considered in this model.
It is recommended to use this model with an appropriate control. If the filling level falls below the outlet liquid flanges' height or rises above the outlet flanges height the separation behaviour changes drastically. In that cases whether vapour is sucked into the liquid outlet or liquid is sucked into the vapour outlet.

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
[2] Karl Strauß: "Power Plant Technology for Exploitation of Fossil, Nuclear and Regenerative Energy" (in German), Springer, 6th edition, 2009.

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

07.03.2016 -v 1.1.0 - Initial Implementation - Friedrich Gottelt/XRG Simulation GmbH
28.04.2016 -v 1.1.1 - offer option to set position of liquid pressure state either at the liauid surface of at the vertical middle of the zone and added optional measurement conectors - Friedrich Gottelt, XRG Simulation GmbH

Backlinks: ClaRa:Components:MechanicalSeparation:Bottle L3