Boiler Flow Distribution

This Case Study describes how Steinmüller was able to do what-if studies and to make decisions such as whether to remove the evaporative platens to optimize the plant in terms of reliability, plant availability and overall plant efficiency. Flownex proved valuable in the investigation by providing the new flow distribution in the water walls and super heaters based on design changes and also the steam condition that is provided to the turbines.

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Blow-off test valve analysis

A blow-off test to determine compressor performance during part load conditions is required at a newly built compressor plant. The test requires controlled flow variation in order to test the compressor’s performance within the specified range. For this, a pipe header with 1½” and 1” solenoid valves needs to be designed. The flow rate should be incrementally variable between 30 Nm3/min and 160 Nm3/min.

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Two Phase Flow Regimes

THEME: Root Cause Analysis of System Performance Anomalies 

This case study ‘Two-Phase Flow Regimes’, aims to demonstrate the capability of Flownex SE to carry out root cause analysis of a system to determine the cause of a system performance and safety issue. In addition to identifying the underlying cause, using Flownex SE it is possible to deliver an optimized design solution in the simulation model, in order to remove the root cause issue and generate an improved design configuration.

The case study presents how Flownex SE was successfully employed in a Power Plant commissioning project where it quickly identified the cause of a system performance anomaly, optimized the system design to remove the anomaly and efficiently returned the system performance back within desired performance parameters.

One of the considerable benefits aside from identifying and rectifying the design issue was that by using Flownex SE the analysis and optimization study was executed quickly and cost effectively keeping the commissioning schedule on track and mitigating the commercial impact on the project.

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Pebble Bed Micro Model Start-up

The PBMM (the world's first closed cycle multi-shaft gas turbine test rig) was developed to demonstrate the operation of a three-shaft, pre- and inter-cooled recuperative Brayton cycle in order to gain a better understanding of its dynamic behavior. The entire cycle was designed, simulated and commissioned with Flownex within 9 months at a cost saving of $48 million.

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Generator Seal Oil System

THEME: Failure Mode Analysis of Thermo Hydraulic Machine Components 

This case study ‘Generator Seal Oil System’, aims to demonstrate the capability of Flownex SE to simulate thermo hydraulic machine system components such as seals and simulate operational scenarios to test limits of the machine component to determine the failure modes and effects analysis of the component, to gain better understanding of how the system behaves and works. 

This case study presents how Flownex SE was successfully employed to model a power generation unit hydrogen seal ring and determine causes of seal failure leading to system trips. The Flownex simulation model clearly demonstrated the relationships between system pressure, seal clearances and turbine speeds.

One of the main benefits of modelling the system to determine failure modes and causes was the saving realised by being about to perform this investigative study in the simulation environment. In order to conduct an inspection and investigation in the plant after a trip the machine is shut down and the time required for cool down, stripping, inspection and restarting is considerably costly. This simulation study quickly highlighted the out of specification issue causing the system trips allowing the client to confidently take remedial action to eliminate the issue causing the system trips. 

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Pebble Bed Micro Model

The case study demonstrates a load following transient simulation of the Pebble Bed Micro model (PBMM).

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Turbine protection - Two phase flow regimes

The main challenge explored in this case study is the root cause analysis of dynamically hazardous movements in the distillate lines to a plant deaerator. Flownex's simulation optimization tool was used to determine the preferred two phase flow regime. By using Flownex to identify the cause, it was possible to mitigate a commercial impact on the project, maintain the planned commissioning schedule and improve the existing plant design thereby also removing the safety risk of unwanted dynamic line movements.

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Boiler Fuel Oil Distribution

This Case Study demonstrates how Steinmüller used Flownex to simulate a fuel oil distribution network. The Flownex models served as a comparison study between the current fuel distribution network and proposed changes to the network. By implementing the proposed changes and accurately simulating the proposed changes, Steinmüller was able to make efficient design decisions and determine the possible cost implication due to the changes.

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Boiler Header Cracking Investigation

This Case Study describes how Steinmüller used Flownex to dynamically simulate the flow and heat transfer over the platen evaporator and determine the possible reasons for header cracking.

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Boiler Tube Failure Thermo-Hydraulic Analysis

This case study ‘Boiler Tube Failure Thermo-Hydraulic Analysis’, aims to demonstrate the capability of Flownex SE to carry out investigative analysis of tube failure issues on a boiler, using Flownex to test various hypotheses which were considered to be the cause of tube failures. This case study also shows the versatility of Flownex to work in an interactive communicate manner with other modelling software in this case ANSYS structural analysis.

The case study presents how Flownex SE was successfully employed in the investigation of boiler tube failures in a power plant setting. Having built a representative model of the boiler wall section in Flownex by importing geometric data from ANSYS it was possible to test all assumptions regarding the cause of the tube failures, related to the thermodynamic effects of operation in Flownex. Then the temperature distribution data from Flownex were fed back into ANSYS to analyse the structural effects on the boiler tube wall owing to the Flownex obtained temperature distribution data.

The results from the model corresponded very well with the measured data from the plant, so this meant the Flownex model was an accurate simulation model of the existing plant performance. This enabled the model to be used for further data analysis for various other plant operating scenarios in the future. 

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Regulator temperature analysis

Pressure regulators are to be employed at a gas-fired power station to reduce upstream gas pressures from a maximum of 15 MPa to approximately 3.5 MPa. Due to the Joule-Thompson effect, the resulting gas temperature drops could be in the region of 55 °C. The dew-point temperature of the hydrocarbons (gas) flowing through is -15 °C, and the minimum ambient temperature of the area is -6 °C. Thus, the regulators could potentially be subjected to gas at -61 °C at start-up. According to the valve manufacturer, temperatures as low as -20 °C can be tolerated for some time, provided that condensation does not occur. 

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Combined Cycle Power Plant

This case study demonstrates the modeling of a Combined Cycle (CC) power plant of a High Temperature Gas-Cooled Reactor (HTGR). The nuclear reactor is not modeled in detail as the focus of this case study is not on the reactor but on the CC Power Conversion Unit (PCU).

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