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The condenser design data required for the preparation of the thermo-hydraulic model will include, but not necessarily be limited to, the following:
Design conditions (thermal)
- Shellside: Effective surface area, design duty, steamflow, enthalpy, single or multiple shells and/or pressure
- Tubeside: Cooling water, source, specific gravity, specific heat capacity, flowrate, inlet and outlet temperatures (or rise)
- Shellside: Design/test pressure and temperature
- Tubeside: Design/test pressure and temperature
- Tubes: Quantity, material, diameter, gauge (thickness), length
- Tubesheets: Quantity, material, thickness
- Support plates: Quantity, material, thickness, spacing in bundle
- Condenser hotwell, shell, transition and waterboxes: Physical arrangements, number of shells and details
Note that the following are typically reliable
- HEI surface condenser data sheet
- Fabrication and erection drawings (specifically)
- General arrangement (outline) drawing
- Connection listings
- Foundation arrangement
- Support plates
- Instruction and installation, operation and maintenance manuals, including:
- Data sheets
- Condenser predicted performance curves
- Ancillary equipment
- Venting equipment drawings and manuals
- Cooling water pump curves
Establish baseline model for the existing condenser
From the above data, a thermo-hydraulic model can be developed that will form the basis of the review of the existing steam surface condensers thermal capabilities for the power uprate. With the correct design inputs, an accurate thermo-hydraulic model can be created. Unknown design inputs must be determined and agreed upon by other acceptable methods.
Once the thermo-hydraulic model has been created, the model will need to be verified for the original design prior to use with the power uprate conditions. This is to ensure that the model will accurately reflect the performance under a variety of known operational parameters for the power uprate.
Verification of the thermo-hydraulic model is therefore very important. HEI standards for steam surface condensers will often provide the design basis for the thermo-hydraulic model. If at all possible, the thermo-hydraulic model should reflect the factors and coefficients in effect at the time of the original condenser design, since this will provide the most accurate model. Previous editions of HEI standards may need to be researched in order to obtain this information. In the absence of the actual factors and coefficients from the relevant HEI (in force at the time of the original condenser design) the latest factors and coefficients may be utilized with the understanding that slight discrepancies in any of the thermo-hydraulic model outputs, vs. the originally published data sheet, may occur.
Furthermore, the existing condition of the steam surface condenser needs to be carefully considered. This information needs to be factored into the thermo-hydraulic model. A visual condition assessment of the existing condenser is strongly recommended, and this should include an inspection of the condenser externals and internals with the goal of understanding any material degradation, as well as any modifications that might have occurred since the unit was originally designed and installed. It is important to ensure that the thermohydraulic model is created based on the original design conditions, while the use of the model for predicting future performance should always reflect actual known conditions. For the review of the thermal design, examples of highlighted concerns would be determining the quantity of plugged tubes within the tube bundle.
Often the plant can provide tube maps, which will include this information and therefore the reduction in available surface area (from the original design condition), which can then be factored in future performance predictions. Any modifications that have been performed to the condenser should always be noted and reviewed for possible impact on the performance predications when using the established thermo-hydraulic model (eg. retubing, etc.).