Introduction to the APROS code APROS laboratory manual: Aim of the course Studying the operation of APROS v5.10 thermal-hydraulic system code: building simple flow circuits, displaying process parameters, running and examining transients. APROS system code APROS (Advanced Process Simulator) is basically a one-dimensional thermal-hydraulic system code, developed by Finnish Fortum company (former Imatran Voima Oy) and VTT research institute since 1986. The purpose of the development is to create a software package that makes it possible to design, analyze and simulate complex industrial systems (thermal and nuclear power plants, chemical plants, district heating systems). The main characteristics of the code: The thermal-hydraulic model solves the continuity, momentum and energy equations for steam and water phase in one dimension. Connected to the thermal-hydraulic model, the code is able to calculate one-dimensional reactor kinetics, instrumentation and control (I&C) technolgy, electrical network, containment processes and core damage during severe accidents. Therefore, not just the fundamental physical processes, but the system behaviour can be studied for normal operation, design basis accidents and severe accidents of nuclear power plants. The user builds the model from pre-built components (e.g. pipe, hidroaccumulator, steam turbine), the thermal-hydraulic nodes, branches, heat sources, etc. needed for the mathematical model are generated by the code. Of course, the user has the opportunity to modify these. The code package contains an interactive graphical user interface (GRADES), most of the work can be done using it. Since GRADES is not an integral part of a simulation engine, just a GUI add-on, it is possible (sometimes necessary) to use the original, command-line interface to build, modify and run models. The performance of the current desktop PCs are enough to run simpler transients in real time (or even faster). More complicated, nuclear power plant processes with two-phase flow are computationally more intensive, and run slower. The user is allowed to extend the model with his own modules written in FORTRAN or C language. The physical models of the code have been validated for several real experiments, measurements and benchmark problems. The APROS modell can be presented as a three-level hierarchical modell: 1
The top level is the process level. The model is easier to comprehend if it is divided to different diagrams (e.g. primary and secondary loops, emergency systems, control systems). The second level is the process component level. Using the graphical interface, this level is used most often. The pre-built models (later: modules) help and speed up the modelling work. The bottom level is the calculation level. On this level the elementary building blocks of the process components can be accessed. The most important components here are the nodes (volumes for continuity and energy equation solution) and branches (flow connections between the nodes for the momentum equation) Starting GRADES and the menu bar The code s graphical interface, GRADES can be launched using the desktop icon. During its initialization, GRADES connects to the APROS binary running the thermal-hydraulic simulation in the background (it happens either automatically, or after clicking on the Log In button). After selecting workspace (Project/Open workspace/ ), the program loads the last saved model. The menu bar consists the following items: Project Log In and Out APROS server. Projects and workspaces. Create, load and save Model. Create, open, delete, export and import Net. Create Group. Print and Exit. Mode Run, step and stop simulation. Exclude/Include Net from/to simulation. Tools Manipulation of Symbols. Open Net, Run, Edit, Draw, View windows. Setup of the program (Options). Setup of the simulation (timestep, etc.). Trends Define ( Pick ), list Trend windows. Default settings of Trend windows. Save Trend windows. Exchange Import/export Model/Net. 2
Model Run script. Search Module. Change access level. Setup, lock Model. Edit (active only if a Net is opened!) Copy, paste, delete. Select all Modules. Display (active only if a Net is opened!) Zoom. Add, delete Marker. Go to Marker. Display setup (border, scale, guidelines, etc.). Layers. Setup of editing (show/hide, snap, draw angle). Binary Signals: use, define, refresh Binary Signal Colours. Redraw. Window Change the layout of windows ( Tile, Cascade ), close windows. Open Apros Message Window and Project View. List of opened Nets. Help Available in html format. 1. task: Create a new model and a new net! Open Net, Run, Edit, Draw, View windows! Choose Project/New model menu point and give a name to the model. The name should end with six digits referring to the actual date. Net Choose Project/New net menu point to create an empty net. The name and ID of the net should be n1. If it is not opened automatically, open Net, Run, Edit, Draw, View windows from Tools menu point. The pre-built modules can be selected from this window. At the top of the window, the graphical symbols of the items in the selected module groups are shown. Double-clicking on the group opens it, and the required module can be selected and inserted to the net. The first three letters in the group name refers to the following modell libraries: AUT: instrumentation and control (analog and digital circuit elements, measurement elements, controllers, etc.) BOI: boilers CON: containment ELE: electrical equipment EXE: setup of simulation PRO: thermal and fluids equipment (pipe, heat exchanger, valve, etc.) REA: nuclear power plant equipment (reactor, pressurizer, etc.) 3
Switching to connections between modules is possible from the bottom of the window: Connections: Name Reference Analog Signal Binary Signal Pipe Connection Name Reference is not a module, the logical connections of the modules can be defined with it. Usually a module is connected to other modules, the name of the connection points are terminals. Run Stop, run, step simulation. Edit Upper line: Select module, Move edges/monitors, Delete, Manipulate layers, Rotate. Lower line: Mirroring, change the position of elements. Draw Draw lines, circles, rectangles, create text box, insert picture, create displays (warning light, bar graph). View Upper line: Zoom in (Page Down), Zoom out (Page Up), Zoom to selected area (F2), Create marker, Marker area. Lower line: Full page (Home), Full width, All modules, Jump to marker Right side: scroll net Right clicking on the net opens a menu. If the cursor is on empty space (ie. not on any symbols or connections), then the menu has the following items: Hilite: Switching on/off the display of not defined and out of simulation modules. Monitor: Show/hide/remove all monitors, default monitors Show/Hide: Show/hide Borders, Margins, Rulers, etc. Snap: Fit the modules to the visible grids. Zoom: Zoom in/out Net in simulation: Exclude net from simulation Refresh binary signals: Redraw coloured binary signals. Redraw: Redraw screen. 4
Put three points, a pipe and a basic valve on the net! Point is in the PRO Point and Node, pipe is in the PRO Pipes and the valve is in the PRO Valves group. Right clicking on the graphic symbol of a module opens a menu with the following important menu items: Properties Properties of the module. Documentation: Create documentation. Method: Type of the flow model used by the module (number of equations). Monitor: Display the properties of the module on the net next to the graphic symbol (e.g. flow rate for pipes, level at tanks, etc.). In simulation: Exclude the module from simulation (its parameters are fixed, it becomes a boundary condition). Detach from module / Attach to another module: Detach the graphic symbol from the underlying module, attach a symbol to a module. Copy/Create slave copy: Create a copy of the module: the graphic symbol of a module can appear on different nets (e.g. a pipe s symbol can be used on the pipe network s net and on the controlling system s net as well). Jump to: Jump to slave copy. Take a look at the parameters of the new module! Give initial parameters to the new modules! Connect the modules with Name Reference connection! Create boundary conditions! The table with the parameters of the module opens by clicking right on the graphic symbol and choosing Properties menu point. The first column refers to the name of the parameter, the second is its actual value and the third contains the dimension. Values can be written into the white cells. Important: the program creates the module when we first click OK on the Properties window! Before clicking only the graphical symbol exists. First point (N1_PO01): Flow model: 6 Pressure: 1.5 MPa Temperature: 20 C Pipe between the first and second point (N1_PIP01): Flow length of pipe: 10 m Number of calculation nodes inside the pipe: 3 Second point (N1_PO02): Flow model: 6 Pressure: 1.5 MPa Temperature: 20 C 5
Valve between the second and third point (N1_BV01): Position of valve: 0.5 Third point (N1_PO03): Flow model: 6 Pressure: 0.5 Temperature: 20 C Connecting the modules: choose Name reference connection and then click with the modified cursor on the terminal in the middle of the point (orange square) and on the terminal on the end of the pipe (blue circle). Creating boundary conditions: Right click on the chosen modules (first and last points in this case) and click on In simulation point to remove the tick. The module s parameters get fixed, and will not change and therefore the points become infinite sources and sinks. If it works, after choosing Hilite Not in simulation option, the boundary conditions become visible as red frames shown in the next figure: Let s see the modules through the command-line! What kind of parts build the pipe up? Choose Project/Project Manager point from the menu and press CTRL-A and ENTER. It opens up a command-line window through which commands can be sent to the APROS server. The three most important commands: show <module s name> - list the module s parameters list <module s name> - list the modules connected to the module modify <module s name> <parameter s name> <new value> - modify parameter Let s see the first point s parameters with show n1_po01 command! List the pipe s caculation level modules with list n1_pip01 command! Let s see the parameters of the pipe s first node (N1_PIP01_NO1) and branch (N1_PIP01_BR1)! Speed up the default, real time simuation with modify speed sc_speed 100 command! Dipslay the modules parameters on the net! The actual parameters of the modules can be accessed through the Properties window or with commands written into the commad-line interface, but these are complicated methods. Monitors can display the important parameters for the modeler in character form on the net. The Monitor menu opens by clicking right on the module. The menu consists the following points: 6
Monitor Define / Hide / Remove: Create / hide / delete Monitor. Use this monitor for similar nodes: Creates the monitors defined for the module for the same type of modules on the net. Show / Hide / Remove monitor for similar nodes: Shows / hides / removes the monitors of similar modules. Monitor/Define window consists the following points: Edit / Run / Edit+Run: Display the monitor during edit / run / continuously. Add / Add all: Add the chosen / all parameters. Remove / Remove All: Remove the chosen / all parameters. Format: Setup of format. Font: Change fonts. Display the pressure and temperature for points, flow rate for pipes, the position for valves (three decimals) on the net! The model equipped with monitors can be seen in the following figure: Using trend windows is useful during the testing of the model as the changes of the chosen parameters over time can be tracked. A new trend window can be created from Trend / Pick menu point. After choosing the menu point, the cursor changes. After clicking on the graphical symbol, a new window is opened, where the parameter to be displayed must be selected. The lower bar of the trend window contains the following buttons: Optimal rescaling of both axes Optimal rescaling of Time / y axis Zoom in / out Print graph Stop / run Time axis with simulation Add more parameters to the trend window Save the model! Start the simulation and examine the different parameters in the function of the pressure ratio and valve position! 2. task Build flow measurement into the model! 7
Control the flow rate with control valve! Create the following modules: Flow meter: Net/Nodes/AUT Measurements/Flow High limit: 1000 Connect the orange square on the pipe with the purple dot on the flow meter with Name Reference connection. Valve controller: Net / Nodes / AUT Actuators S / A02: Pneumatic control valves Connect the orange square on the valve with the purple point on the controller with Name Reference connection. PI controller: Net / Nodes / AUT Controllers / PI Controller S Gain: 0.01 Integration time: 2 Setpoint: Net/ Nodes / AUT Analog Basic / Setpoint S Setpoint value: 100 Maximum value 1000 Analog signals: Net/ Nodes / AUT Analog Basic / Signal Analog Analog signals must connect the analog outputs (dark red) and inputs (dark green). The previously created analog signal should be connected to the input and output with Name Reference connection. Connect the following terminals with analog signals: 1. The flow meter s FM_NONSCALED_OUT_SIGN terminal with the PI controller s PI_MEASUREMENT_SIGN terminal. 2. The setpointer s SP_OUTPUT_SIGN point with the PI controller s PI_SETPOINT_SIGN point. 3. The PI Controller s PI_OUTPUT_SIGN point with the controller s DC2_INPUT_SIGN point. The name of the terminal can be checked by holding CTRL button and right clicking on the terminal. Define monitors for the analog signals! Test the model with setting different values for setpoint. The figure on the right shows an example solution for the task. 3. tasd Build a pump into the model! Determine the characteristic curve of the pump! 8
Pump: Net / PRO Pumps / Basic Pump Connect the model s first point to the outlet of the pump and take it back to simulation. Connect the slave copy of the model s last point to the inlet of the pump. Slave copy can be created by right clicking on the point and choosing Create slave copy here option from the menu. To determine the characteristic curve, we need the flowrate and the head (pressure difference) of the pump. Non of these parameters are available directly from the APROS database, but they can be calculated with simple functions: Pressure difference: Net / EXE Boundary Condition / BC General Sum There are four inputs on the left side of the function s graphic symbol and there is one output on the right side. Create the module and connect the first input with the pump s inlet point and connect the second input with the pump s outlet point. The module s settings: First input module and variable: N1_PO03 PO11_PRESSURE Second input module and variable: N1_PO01 PO11_PRESSURE Coefficient of first input variable: -1 (it ensures the difference of the two inputs instead of their sum as the value of the function). Flow rate: Net / EXE Boundary Condition / BC General Product Create the module and connect the first input with the pump s inlet point and the second with the outlet point. The module s settings: First input module and variable: N1_PO03_NO1 NO6_MIX_DENS Second input module and variable: N1_BP01 PU11_MIX_MASS_FLOW Power to which 1. input variable is raised: -1 (it ensures the quotient of the two inputs istead of their product as the value of the function). Determine the head of the pump for at least 5 different flow rates! Display the results on graph and fit a y=a+bx 2 type function! The following figure shows an example for the task. 4. task Build a heat exchanger and temperature control into the model. Examine the effect of the change in flow rate on the temperature control! 9
The aim of the task is to create a system which produces water with given temperature and flow rate. For this purpose we have to create the following model: There are two modules in the model which have not been discussed before: Co-current heat exchanger: Net / PRO Heat Exchangers / Co-current Heat exchanger Average length of heat exchanger tubes: 10 Number of parallel heat exchanger tubes: 1000 Thermometer: Net/Nodes/AUT Measurements/Temperature High limit: 1000 Time constant: 1 The PI Controller s parameters: Gain: 0.001, Integration time: 2. We can examine different transients with changing the setpoints in the model. 5. task Save the results of the simulation into an output file! Create the following modules: DB names: EXE Simulation Control / Database names for IO Database names for IO[1]: <module s name> <parameter s name> (e.g. N1_PIP01 PI12_MIX_MASS_FLOW) IO set: EXE Simulation Control / IO Set IO file name: data<current date>.dat Name of module defining database names: N1_DBN01 Time step of data transfer: 1 Experiment: EXE Simulation Control / Experiment Name of IO set module[1]: N1_IS01 10
The header of the output file - created after running the model - contains the number and the names of the parameters. The header is followed by the calculation results. Each time step has a line which starts with the simulation time and continues with the values of the parameters defined in DB Names module. To plot the saved values, it is recommended to use gnuplot software (available at http://www.gnuplot.info/). Document the APORS models built during the course and simulation results in a report form! 11