The working fluid in of low temperature boiling point could be isopentane for the Rankine cycle or a mixture of ammonia and water for the Kalina cycle. In a next step, the fluid is flashed by the
and then expanded in a thermal turbine driving an electric generator.
Sulzer provides the following vertical pump as a hydrocarbon feed pumps for these processes:
| SJD-API | |
|
Capacities |
Up to 3,800 m3/h / 20,000 USgpm |
| Heads | Up to 700 m / 3,000 ft |
|
Pressures |
Up to 75 bar / 1,100 psi |
| Temperatures | Up to 205°C / 400°F |
Binary cycle processes are quite frequent nowadays to make use of the medium enthalpy hydrothermal resources available in the underground. A secondary working fluid having a flashing point at much lower temperature is heated-up by the hydrothermal resource and then expanded in a thermal turbine to drive an electric generator.
A binary cycle plant transfers heat from the hot geothermal fluid (105°C < T < 185°C) that is sent through a heat exchanger to vaporize a secondary working fluid such as pentane, iso-butane in the Organic Rankine Cycle, or ammonia in the Kalina Cycle. The working fluid is then expanded in a turbine, condensed and reheated in a closed loop cycle. The brine is disposed of by re-injection into the ground. Sulzer supports these processes with Production pumps (PP), Brine Re-Injection pumps (BRIP), Hydrocarbon Feed pumps (HFP), Cooling Water pumps (CWP) and auxiliary pumps.
Dry rock enhanced geothermal systems are currently being deeply investigated. In such cases, the hydrothermal resources are not available in the underground but generated artificially through the stimulation of fractured hot bedrock by injecting water on them. The outcome of this technology is usually very high enthalpy hydrothermal resources.
Dry steam geothermal resources were the first used since the beginning of the 20th century to generate electricity. In this process, the steam source available in the underground flows naturally to run a thermal turbine driving an electric generator.
Flash / binary geothermal power plants are also described as combined-cycle. The purpose is to optimize the efficiency of the thermal cycle combining the high enthalpy hydrothermal resources available in the underground by flashing them into steam while the rejected hot brine is used to flash a hydrocarbon or ammonia in a binary cycle.
Flash steam plants use high enthalpy hydrothermal resources available in the underground that are flashed into steam in a drum at low pressure. The flashed steam runs a thermal turbine driving an electric generator.
