Introduction
The Nikkiso Online Geothermal Steam Monitor measures water quality and gas volume of the primary steam at geothermal power plants.
Geothermal Power Generation
To drive turbines and generate electricity, geothermal power generation uses the underground steam produced by thermal energy that is created, for example, during volcanic activities. Because plants of this type do not consume fossil fuel (i.e., they are clean energy systems), they are viewed as a promising technology for future power generation that can help prevent global warming. Presently, there are about 300 geothermal plants (8,880,000 kW) under operation worldwide.
Background of Development
The steam supplied to steam turbines at geothermal plants contains impurities, such as silica and chloride ions, as well as gases, which cause scales to stick to the turbine or that reduce the vacuum in a condenser. To accurately control the plant water (steam) quality, online measurements of both the steam water quality and gas volume have to be taken. To meet this need, Nikkiso has developed an automatic online geothermal steam property monitoring and analysis system in collaboration with Fuji Electric Systems Co., Ltd. and Geothermal Engineering Co., Ltd. When developing this system, Nikkiso applied the same water quality adjustment system technologies used for thermal and nuclear power plants, which have been developed by the company since it was established.
Outline of System
This system monitors the following six conditions, important for the management of geothermal plant operations:
| Silica concentration | index of scale adhesion |
|---|---|
| Chloride ion concentration | index of turbine corrosion |
| Noncondensable gas concentration | index of condenser performance and gas extractor performance |
| pH | index of steam water quality |
| Electric conductivity | index of turbine corrosion |
| Electric conductivity of acids | steam quality monitoring index |
Based on the development of a way to automatically remove substances that impede measurements, such as hydrogen sulfide and carbon dioxide, Nikkiso improved the accuracy of the system; It is now capable of unmanned operation, except for monthly maintenance. Domestic (within Japan) pipe performance tests have demonstrated favorable results.
Main Features
- Measurement of six conditions required for plant management:
- Silica concentration
- Chloride ion concentration
- Noncondensable gas concentration
- pH levels
- Electric conductivity
- Electric conductivity of acids
- Unmanned operations
- Automatically remove hydrogen sulfide in sample water
- Automatically remove carbon dioxide gas in sample water
- Maintenance free, except for monthly maintenance
R&D Report
