Reinjection temperatures should be high enough to avoid silica scaling. In a geothermal system, an optimum reinjection strategy should be considered depending on the geochemistry of the brine. In binary power plants, the geothermal brine is passed through the heat exchanger to heat working fluid in a closed circuit of turbine, evaporator, condenser, pump, and preheater. The third type of power plant is binary units using lower-temperature resources. Unlike the flash units, the dry-steam type does not have a flasher/separator and brine to be reinjected. The dry-steam case directs steam to the turbine from the steam field. After flashing the brine, the high-quality steam is sent to the steam turbine to generate electricity. To increase the efficiencies or power generated from the geothermal resource, double or triple flashings are performed by adding one and two more flashing stages, respectively.
The power generated and efficiencies are low for SF units. In single-flash power plants, pressurized two-phase fluid undergoes the flashing process once by lowering the pressure below the saturation pressure of the fluid temperature in one separator. Power plants include flash steam (single flash, double flash, or triple flash), dry steam, and binary (ORC). Thermodynamic principles mainly govern geothermal power plants’ operations and design configurations. For in-ground heating, a closed geothermal loop exchanges heat with the ground within a specified volume where soil or groundwater provides heat to warm buildings or receive excess heat. The regenerative cycle would be best suited where reinjection temperature is constrained by brine geochemistry.Įnergy conversion systems use the geothermal resource for electricity generation in a power plant or for heating as in-ground source heat pumps. The analysis showed that for unlimited reinjection temperatures, basic ORC is suitable. The best pinch point is 10 ☌, since the reinjection temperatures are the highest between 83 and 89 ☌. The pinch point affects the heat transfer rates and effectiveness in the heat exchangers.
/cdn.vox-cdn.com/uploads/chorus_image/image/5194919/orcvengeance_ipadgamereviews10.0.png "access menu orc 980")
In the pinch point consideration, the suitable fluid will depend on the best reinjection temperatures. On the other hand, R236ae had a flow rate of 398.2 kg/s, a higher power output of 7273 kW, and the lowest reinjection temperature of 73.47 ☌ for a 5 ☌ pinch point. For the pinch point of 10 ☌, the working fluid with a lower net power is trans-2-butene at 5936 kW for a flow rate of 138.8 kg/s and the highest reinjection at 89.05 ☌. By maintaining a condenser temperature at 46.7 ☌, the turbine outlet pressures were 557.5 kPa for isobutene, 627.4 kPa for isobutane, 543.7 kPa for butene, 438.9 kPa for trans-2-butene, 412.3 kPa for R236ea, and 622.9 kPa for R142b. As the pressure increased, the efficiencies and net power generated increase to optimal at turbine inlet pressures between 20 kPa. The turbine inlet pressures, and pinch points were varied to obtain optimum pressures for higher net power output and exergy efficiencies. The objective was to combine pinch point analysis and exergy analysis for the optimum utilization of geothermal energy by varying the turbine inlet pressure, pinch point, and reinjection temperature.
Access menu orc 980 code#
Engineering Equation Solver (EES) code was used to design and optimize simple organic Rankine (ORC) and regenerative cycles. This paper presents the effect of six different working fluids to optimize the geothermal of 21.5 MWe of reinjected brine at a single-flash power plant in Kenya. The installed capacity of geothermal energy in Kenya is 847.4 MWe of the total 2.7 GWe. Geothermal energy is a sustainable renewable source of energy.
0 kommentar(er)
