2020 RD (14) An introduction to process simulation using FactSage by Jean Philippe Harvey
Introduction to Process Simulation using FactSage
In this presentation, the speaker introduces the audience to process simulation using FactSage. The speaker explains how to use FactSage to simulate a process from an overall mass and energy perspective.
Using Computational Thermochemistry for Process Simulation
- The speaker explains that computational thermochemistry is used to identify the operating conditions of a simulated process in terms of temperature, pressure, and mass balance.
- To perform thermodynamic calculations, it is important to have precise knowledge about the technology being simulated and any local equilibria that may impact impulse constraints.
- By simulating a process with FactSage, one can obtain resolved mass and energy balances which are useful for identifying element partitioning between different phases, parasitic reactions, environmental impacts in terms of gaseous emissions, and energy balances.
Basic Ingredients for Successful Process Simulation
- To successfully simulate a process using computational thermochemistry like FactSage, it is important to identify all impulse conditions onto the system.
- An accurate thermodynamic description of each important face of the system is necessary. This is where FactSage's specialized databases come into play.
- Integration of all important components in these solutions such as the slag phase is critical if one wants to quantify partitioning of different elements inside various faces.
- Adequate phase selection must be made in order to interpret and analyze results obtained from thermodynamic calculations.
Objectives of First Workshop Session
The speaker outlines the objectives for the first workshop session on using FactSage for process simulation.
Objective 1: Introduce Basic Options Available in FactSage
- The speaker introduces basic options available in FactSage such as database selection, identification of initial conditions, adiabatic calculation, precipitation and formation target options, impulse activity constraint, and construction of streams.
Objective 2: Define Fundamental Process Simulation Concepts
- The speaker defines fundamental process simulation concepts essential for analyzing pyrometallurgical processes such as the Boudouard reaction, oxidation of impurities using oxygen blowing, and slag reduction using carbon.
- The speaker shows how to analyze results obtained from thermodynamic calculations in terms of chemistry of different faces that are in equilibrium as well as overall phase assemblage for some imposed conditions.
Example Simulations
- The speaker outlines six example simulations that will be covered during the first workshop session. These include evaluating Gibbs free energy of a compound as a function of temperature, analysis of meat and combustion under different conditions, quantifying volatilization of zinc during melting of scrap materials, stability and metastability of faces (graphite and cementite), and process simulation for the Hollywood process.
Using the Equilibrium Module to Plot Gibbs Free Energy
In this section, we learn how to use the equilibrium module to plot the evolution of the Gibbs free energy of a compound as a function of temperature.
Getting Thermodynamic Information for a Compound
- To get thermodynamic information for a compound, go to the Compound Module and enter its chemical formula.
- View the list of products in the Compound Module and select the appropriate database.
- Click on a phase to see its molecular weight, name, and reference where you can find thermodynamic information.
- Enable extended properties to see thermal expansion parameters used to define this property as well as other characteristics.
Calculating Gibbs Free Energy
- Go to Equilibrium and enter mass balance for one mole of Al3.
- Select FTlight database and work with molar basis by double-clicking on unit here.
- Right-click on pure solid and select phase interested in (in this case, Al3 intermetallic).
- Enter range of temperature from 25°C up to 600°C per step of 10°C.
- Calculate results and plot Gibbs free energy as a function of temperature.
Clearing the System and Selecting Databases
In this section, the speaker clears the current system and selects a database to work with.
Clearing the System
- To clear the current system, select "Yes" when prompted.
- When asked if you want to keep the selection of databases that are already activated, select "No."
Selecting Databases
- The speaker selects only the FactPS database.
- The FactPS database contains thermodynamic information about gaseous species as well as compounds.
Reacting Methane with Air
In this section, the speaker sets up a reaction between methane and air.
- The speaker adds two reactants - O2 and M2 - to methane (CH4).
- The alpha parameter is introduced to vary the proportion of methane to air in the system.
- The initial condition button is activated to define the initial condition of each stream in equilibrium population.
- The temperature of all species is set at room temperature and pressure at one bar.
Running Calculations for Enthalpy Release
In this section, calculations are run to determine how much enthalpy is released upon combustion of methane by air.
- Upon clicking on "Next," there are no solutions available because we're working solely with FactPS database.
- By left-clicking on mouse, all gaseous PCS considered in FactPS database can be selected along with pure solid and liquid substances.
- A calculation is run where alpha parameter varies from 0 to 1 per step of 0.01 to see energy released upon combustion of methane by air.
- Results show delta H evolution as a function of ratio between methane and air.
- A plot is created to show the evolution of delta H as a function of alpha parameter.
Adiabatic Flame Temperature
In this section, the speaker works with impulse delta H to determine adiabatic flame temperature for the system.
- No changes are made in terms of mass balance.
- Impulse delta H is used instead of impulse temperature.
- All energy released upon combustion of methane is used to heat up products and reactants.
Thermodynamic Properties of Gas Phase
In this section, the speaker discusses the species present in the gas phase and how to obtain thermodynamic properties using a thermodynamic equation.
Obtaining Thermodynamic Properties
- The speaker explains that they can obtain thermodynamic properties by performing a thermodynamic equation using FactSage.
- They plot the temperature of the system as a function of alpha parameters and find that an alpha parameter close to 0.9 maximizes the temperature at around 1957 degrees Celsius.
Volatility of Species with Temperature Increase
In this section, the speaker demonstrates how to determine the volatility of species when increasing temperature in a system.
Determining Volatility
- The speaker uses an example where they want to recycle scrap material containing zinc in an electric car furnace.
- They enter a hundred gram basis of stainless steel containing impurities such as copper, zinc, and carbon.
- Chromium is added to form an oxide layer on top of stainless steel for protection against corrosion caused by surroundings.
- Nickel is added to stabilize austenite phase for optimum mechanical properties.
- Copper, carbon, and zinc are also added as impurities.
- Iron is added for mass balance purposes.
- The speaker selects faces from various phases including solution, solid, liquid, and gaseous species.
- They define a temperature of 1600 degrees Celsius to melt everything and obtain a hundred gram basis of liquid metal containing all elements.
- The speaker notes that zinc has a fugacity close to one, indicating that the gaseous vapor is close to forming.
Equilibration with Gas Phase
In this section, the speaker discusses how the liquid phase equilibrates with the gas phase.
Equilibration
- The speaker notes that even though there is zero amount of gas present, there will still be gas release due to the atmosphere surrounding the system.
- The liquid phase equilibrates with the gas phase.
Adding Argon to the System
In this section, the speaker adds a small amount of argon to the system and observes its impact on the phase assemblage.
Observations
- The speaker adds 1e-3 gram of argon to the system.
- Zinc is observed as an important species in the gas phase after adding argon.
- The transfer of zinc to the gas phase can be problematic as it can lead to an attack on refractory material by zinc vapor.
Defining Metastable Equilibrium
In this section, the speaker defines metastable equilibrium using faces dormant.
Observations
- Cementite is a metastable phase that forms under real-life conditions in iron-carbon systems.
- The databases activated for this calculation are fact ps and fstl databases.
- The speaker uses a mass balance with 0.5 grams of carbon and 99.5 grams of iron.
- All faces must be selected for consideration in calculations.
- Ferrite is found to be stable at 600 degrees Celsius, and carbon graphite has precipitated indicating saturation.
- Carbon solubility is modified when cementite is used instead of graphite as a metastable phase.
Chemical Equilibrium and Gas Phase Evolution
In this section, the speaker discusses the chemical equilibrium induced by the boudoir reaction in an excess of carbon. The gas phase evolution is studied as a function of temperature to identify conditions for oxide reduction.
Gas Phase Chemistry
- The boudoir reaction induces an important equilibrium state that is crucial for designing parametrical processes.
- The speaker enters reactants for the reaction and selects databases containing thermodynamic information about gaseous species and pure compounds.
- All gaseous phases and pure solids are selected, and dominant species are identified through computation of solid electrodes.
- Equilibrium states are calculated at various temperatures to observe the evolution of dominant species in the gas phase.
Gas Phase Evolution
- At room temperature, a gas with mostly CO2 is observed due to excess graphite carbon. At 1200 degrees Celsius, a CO-rich gas is obtained which can be used for oxide reduction.
- A graph shows the evolution of molar fraction of CO2 and CO as a function of temperature. A shift occurs around 700 degrees Celsius as predicted by the boudoir reaction.
- The partial pressure of oxygen as a function of temperature is plotted on a graph.
Selecting O2 Chemical Species in Gas Phase
In this section, the speaker selects the O2 chemical species in the gas phase and plots the results. They show how to impose a partial pressure of oxygen to reduce a given oxide and obtain metallic iron.
Plotting Results
- The speaker selects specifically their O2 chemical species in the gas phase.
- They plot the evolution of the partial pressure of oxygen as a function of temperature at 1200 degrees Celsius.
- Double-clicking on the line on this graph allows you to see the exact value, which is 7.55 x 10^-18.
Imposing Partial Pressure of Oxygen
- The partial pressure of oxygen starts to increase drastically or exponentially above 700 degrees Celsius.
- To reduce a given oxide, they remove carbon and introduce some hemfe2.
- The speaker goes into that as surge and activates both the ft oxide database and fstl database.
- They perform this calculation at a high temperature (1200 degrees Celsius) and impose the partial pressure of oxygen (7.55 x 10^-18).
- By deselecting everything and performing their face selection again, they can go specifically in the gas phase and impose the partial pressure of oxygen.
Obtaining Metallic Iron
- After performing their last calculation, they see that with this low partial pressure of oxygen, they are able to obtain metallic iron.
Manipulating Streams for Oxidation
In this section, the speaker shows how to manipulate streams by saving them and manipulating them in subsequent calculations. They use an example involving oxidation of liquid metal (iron) containing some amount of carbon.
Example Calculation
- The speaker opens a simulation that they have already saved on their computer.
- They explain that they have 99 grams of iron with one gram of carbon added to mimic the presence of impurities in their liquid system.
- They also have an alpha parameter to introduce oxygen in order to mimic oxygen blowing in their application.
Phase Selection
- All the solution coming both from fs steel and fd oxide are selected.
- All the gaseous species contained in their gas solution as well as all the pure compounds are selected.
Manipulating Streams
- The speaker shows how to manipulate streams by saving them and manipulating them in subsequent calculations.
- They explain that too much oxygen blowing will lead to the oxidation of the metal that you want to value (in this case, iron).
Understanding the Liquidus and Solidus Temperatures
In this section, the speaker explains how to determine the liquidus and solidus temperatures of a system using precipitation targets.
Precipitation Targets
- The speaker sets a precipitation target on the liquid to ensure that at a certain temperature, all components will be in the liquid state.
- By right-clicking on "i," the speaker can select precipitate target phase to identify what temperature only has liquid and when solid starts forming.
- The primary phase is fcc solid with an activity of one, so it is about to form. The top temperature (1461.7) is the liquidus temperature.
- By selecting formation target, we can evaluate the solidus of our system.
Impact of Oxygen Blowing on Carbon Content
In this section, the speaker discusses how blowing oxygen affects carbon content in iron.
Calculations
- The speaker runs 61 calculations to see how carbon content changes as oxygen is blown into iron.
- Using output plot results, we can visualize weight percent of elements inside liquid metal by varying species from zero to one per step of 0.1 and alpha parameter going from zero to three per step of 0.05.
- Selecting carbon and oxygen from solution allows us to observe their evolution in liquid metal as oxygen is blown in.
Results
- As expected, carbon content decreases as oxygen is blown into iron.
- The speaker observes the formation of a slag phase around 1.777 t in terms of oxygen blowing.
Next Steps
- The speaker saves the stream at an alpha value of 3 for the slag and tries to reduce it by injecting carbon inside the solution.
Generating a New Equilibrium Calculation
In this section, the presenter generates a new equilibrium calculation and incorporates a stream.
Importing Stream and Incorporating it into the Calculation
- To incorporate the stream, the presenter imports it by editing mixture and selecting "stream import".
- The slide is then imported with 100% mass balance.
- Carbon is added to reduce the stack phase.
- The important gas pieces solid and solution are reselected.
Evolution of Phase Assemblage as Carbon is Added
In this section, the presenter shows how phase assemblage evolves as carbon is added to the system.
Plotting Results
- Output plot is used to plot results.
- Gram amount is plotted against alpha parameter.
- Liquid metal and stack phases are selected for plotting.
Recovering Iron in Slag Phase
- All iron oxidized in slag phase can be recovered by injecting carbon into the system.
- At an alpha parameter equal to 1.5, all iron that was oxidized in slag phase can be recovered.
Conclusion
The presenter concludes their mini faxed workshop presentation.
Final Remarks
- Presenter hopes audience enjoyed presentation.
- Audience encouraged to see how they can use faxage in their applications.