Steam generators used in the industry or in power plants are complex systems. The design and engineering of steam generators requires experience and expertise. These systems may consist of complex pipe networks. Heated pipe networks are also the main component of many energy and process plants. Examples are
- Heat exchangers
- District heating systems
- Central heating Systems
Various steam generator technologies are available for different applications:
- Natural circulation steam generators
- Forced circulation steam generators
- Once through steam Generators
Natural circulation steam generators are used for sub critical steam parameters, whereas modern pulverized coal power plants use supercritical steam parameters. Concentrated solar thermal power plants (CSP) may use once through steam generators in future applications. Today’s concentrated solar thermal power plants use oil as heat transfer medium from the solar field to the power island.
The knowledge of the distribution of the mass flow inside the pipe network is essential for the optimal design of the steam generator as well as to ensure safe and stable operation. Therefore the point of dry out (if occurring), the flow regime and the stability of the fluid flow are of great importance too.
Feedback effects of the mass flow, the pressure loss, the point of dry out and the temperature of the fluid inside the tubes can lead to instabilities of the fluid flow. These instabilities can lead to the following:
- Different distribution of the mass flows in the individual tubes compared to the design point
- Reverse flow in individual tubes of natural convection steam generators
- Migration of the evaporation endpoint of once through steam generators
- Undesirable drying up of heating surfaces
- Fluctuations of the steam mass flow, -pressure and -temperature at the outlet of the steam generator
- Fluctuations of the mass flow, the steam point, the pressure or the temperature inside the tubes.
- Oscillations of the tube wall temperatures.
- The effects of these undesirable points of operation are for example
- Damaged tubes, steam drums or other components
- Vibrations of plant components
- Poor performance of individual components or the whole plant
- Poor controlling Performance
Modeling and simulation can provide valuable input during the design and engineering stage of steam generators and to the efficient and fast solution of problems during their operation:
Natural circulation steam generators: Simulations and analysis of the natural circulation behavior enables the designing engineer to prevent upcoming problems already at the stage of designing and engineering. Transient analysis of start up and shut down procedures provide important information for engineering and the performance of the steam generator.
Forced circulation steam generators: The same as for natural circulation steam generators is also true for forced circulation steam generators. In addition to conventional plants, simulations can also be useful in the area of solar thermal energy, e.g. at direct evaporation in parabolic troughs used in solar power plants. When looking on stochastically changing weather conditions, these steam generators will be operated in transient load point many times during their lifetime. Models and simulations provide the necessary information in order to design an optimal plant, before any detailed engineering and construction work has even started. With modeling and simulation tools it is also possible to develop efficient control systems.
Once through steam generators: In times of rising renewable energy production, large power plants have to cope with additional load increase and load reduction; the dynamic simulation of the water vapor cycle illustrates the effects of this on the whole plant.
ENRAG supports you during designing and engineering of steam generators using the following solutions:
- Designing and basic engineering of heat exchangers and steam generators
- Dynamic simulations of heat pipe networks during start up and shut down or load changes.
- Modeling and simulation of the circulation inside natural circulation steam generators
- Verification of the static and dynamic stability of the fluid flow in steam generator Systems
ENRAG has the necessary skills and software as well as experienced staff to model steam generator systems and heat pipe networks. This ensures high quality simulations and reliable results.