Читать книгу Introduction to the simulation of power plants for EBSILON®Professional Version 15 - Steffen Swat - Страница 2
Оглавление2 Functionality of EBSILON®Professional
2.1 General
The modelling software EBSILON®Professional (short: EBSILON) can be used to calculate the most diverse energy-technical systems.
The main task, which is realized by EBSILON, is the process simulation. This is based on two different types of components:
lines
components.
The EBSILON component library contains components for all typical power plant processes. By means of parameters and characteristic curves, the components can be adapted to the real performance behaviour. In addition, there are logical components (e.g. controllers) with which the parameters of the components can be influenced.
In the program environment the whole process is designed and balanced with regard to the most important process parameters. The design of the process is done step by step, first of all a few components are needed to start i.e. with the turbo set. Afterwards, other components can be added, but it must always be checked whether the simulation is running correctly, that means successfully.
Table 1: Selected components
| Physical components | Logical components |
| Steam generator Turbines Condenser Pumps Heat exchangers Cooling towers | Controllers Signal transformers Calculation moduls |
All components have to be connected by lines. The fluid in the lines is determined by mass flow, (temperature,) pressure and enthalpy. The required material data are provided by an integrated extensive material data library.
Calculation algorithms are used in the components to correlate the fluid properties of the outgoing lines with the incoming lines.
Table 2: Selected lines
| Fluids | Fuels |
| Water Air Thermal oils and molten salts Binary mixtures: ammonia / water, lithiumbromid / water Ideal and real gases Two-phase fluids User-defined fluids | Solid fuels (coal, biomass) Oil Gas User defined fuels (by composition) |
In addition to the main program, the calculation of a thermal cycle diagram, EBSILON consists of the following modules, some of which are optionally available [STE21]
EbsBoiler – components for detailed mapping of the boiler geometry
EbsSolar – Components for the imaging of a solar field
OEM-GTLib – Gas turbine database based on manufacturer data
EbsOptimize – Integrated optimizer based on genetic algorithm
EbsValidate – Data validation according to VDI 2048
EbsHTML – Plant Model in the web browser
EbsScript – PASCAL-based script language for EBSILON
2.2 Mathematical principles
The mathematical modelling of the thermal cycle diagram is carried out with the aid of a non-linear system of equations, which is solved iteratively. It is built in the background based on the user input. The decisive variables of the equation system are mass flow, pressure and specific enthalpy.
The actual circular process calculation is carried out internally in two partial steps:
Creation of the nonlinear system of equations from the input data of the thermal cycle diagram (geometry of the cycle and thermodynamic key data)
Iterative solving of the system of equations to calculate the remaining unknown parameters and performance variables.
2.3 Explanations of the program interface
The program interface of EBSILON (Figure 1) is structured analogous to other Microsoft Windows programs. Certain commands directly access standard windows, so that the handling of the program is easy to learn.
The usual operating philosophy for Windows applies:
To edit an object on the screen, it must first be clicked on (e.g. assigning values, deleting, moving, etc.).
Several objects can be selected at the same time by simultaneously pressing the Shift key and clicking on them one after the other.
Selected objects can be moved, enlarged, reduced, rotated and mirrored at their marking frame.
An action (e.g. insert element) can be performed several times until it is terminated by pressing the right mouse button.
Before filling in an input field it must be clicked first. The cursor for input is then positioned in the corresponding input field.
Error messages and requests to the user appear as dialog boxes or in the status line.
Figure 1: Program interface and description of the main work areas
2.4 Basic procedure for the application of EBSILON®Professional
The following basic steps must be observed when creating a thermal cycle diagram:
1. Structure of the thermal cycle diagram:
The cycle diagram is modelled using the following components:
Components (boiler, turbines, pumps, heat exchangers, controllers, etc.)
Lines (pipelines, mechanical shafts, regulation and control lines)
Value crosses
Text boxes
2. Input of boundary conditions on lines and adaptation of specification values in components:
The input of thermodynamic data (e.g. live steam state) and the characteristics of the individual elements (e.g. efficiency of turbine stages) is done via input windows, which are opened by double-clicking on the corresponding element in the cycle diagram.
As shown in Figure 2, a simple heat cycle system comprises the boiler ❶, the steam turbine ❷, the generator ❸, the condenser ❹, the feed water pump ❺ and starting values ❻.
Figure 2: Simple example of an EBSILON model
3. The calculation can be started with a button in the toolbar or with the command in the menu. Before the calculation all input data are checked for completeness and plausibility. Incorrect input data are recognized by the program and displayed in an output window. An error analysis is offered for correction.
4. The results of the calculation are entered directly into the thermal cycle diagram. The output of calculated parameters is done in value crosses on the lines. ❼The value crosses in the figure show the pressure, temperature, specific enthalpy and mass flow of the working medium at each point. (A value cross should be provided only with the units, the units apply then to all value crosses). The calculated power is displayed above the generator with the corresponding unit. Furthermore, the results are written into the input masks of the components and lines. These can be viewed via menus.
The connecting lines between the components differ from the real lines. The connecting lines have no size and only play a role in the transmission of data. All parameters on each connecting line have only one value, which represents the export parameters of one component and the import parameters of the next component.
It is recommended to save the cycle diagram by saving it frequently.
Data, which has not been saved, will be lost, when the program is closed or crashed!
