The overall heat balance result from a THERMOFLEX model of the Kramer Junction SEGS VI plant is shown below. The well-known facility is a single reheat indirectly heated Rankine cycle with six feedwater heaters. The solar field heats Therminol VP-1 which flows through the solar boiler to make and reheat steam. The steam turbine exhausts to a water cooled condenser serviced by a wet cooling tower.
The model is a complete representation of the entire facility including solar field, solar boiler elements, steam turbine, feedwater heater train, condenser, cooling tower, and associated balance of plant.
For a given model run, the minimum required inputs are (1) Ambient conditions, and (2) Solar irradiance data. The program computes gross power, net power, auxiliary electric loads, as well as flow, pressure, temperature, and enthalpy throughout the cycle.
The result below is for the 100% solar loading case at design ambient conditions. The plant model produces 35 MW gross electric power, consumes 2.6 MW of auxiliary power, and produces 32.4 MW net power. In the diagram only key state data are displayed for clarity. However, the user can display the state data at every node, and each icon includes a series of text and graphic output reports for each run.
Model predictions match design point data to a high level of fidelity.
Summary results for each component are available by double-clicking an icon from the overall heat balance view. The display above is the summary display for the solar field. THERMOFLEX includes a library of heat transfer fluids that are commonly used in solar applications. The fluid library includes thermal and physical fluid properties used in pressure drop and heat transfer calculations. In this model Therminol VP-1 circulates within the field and the solar boiler. The solar field diagram shows the state of the Therminol (pink fluid) entering the field on the left, and the field delivery condition on the right.
A performance summary is shown in blue in the lower left corner. In this model, DNI is 916 W/m2, total heat transferred to fluid in the field is 92.7 MW, and the fluid pressure drop from receiver inlet to exit is 6.5 bar, or about 27% of exit pressure.
A series of detailed text and graphic reports are presented to describe the computed heat balance, the physical equipment description, and for PEACE components, estimated equipment and installation costs.
The field size and layout report is displayed below. The bird’s-eye view shows the collector rows are oriented North-South. Fifty (50) U-shaped flowpaths are arranged in one hundred (100) collector rows in two row banks. Fluid enters from and returns to headers in between row banks. Major dimensions are listed along with total field aperture and required land area.
THERMOFLEX output reports include text and graphics to describe steam turbine performance, configuration, and cost. Reports include detailed heat balance results in and around the turbine, section efficiencies, turbine casing configuration, leakage schematics, estimated turbine generator size, weight, capital cost, and installation labor.
The steam turbine expansion path, Mollier diagram, is shown in the top right corner above. Extraction pressures for feedwater heaters are shown along the path which consist of an HP section and an IP/LP section with steam reheat in between. Steam exhausts at 80 mbar with a quality of about 90%.
PEACE cost and installation estimates are based on equipment size, weight, and configuration details. A series of reports present this data. The estimated elevation view for the steam turbine is shown below along with a summary of overall dimensions for the turbine and its generator. The steam turbine design model is entirely dynamic, so any changes to design parameters are reflected in these reports, and in the cost and installation labor estimates.