MTDATA – Phase Diagram Software from the National Physical Laboratory

 

 

 

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Application

Introduction

The APPLICATION module of MTDATA is used for linking the sophisticated MTDATA software for the calculation of multiphase, multicomponent equilibria to user written software to provide calculations specific to a particular process or application. All phases available within MTDATA may be used including alloys, molten salts, gases, aqueous solutions, slags, mattes and pure stoichiometric substances in combination. For each application the calculations are intiated using essentially the same MTDATA command language. The macro which initiates the application provides detailed help on what the user should type in and this may include application specific variables which will transferred to the application through so-called user variables. A number of different applications written by or on behalf of NPL are described in this manual. Further details about these applications and on developing one's own applications can be found in the Application Interface Programming Guide.

Data for the calculations are retrieved either from specified databases or from a datafile prepared in advance. This datafile would normally have been generated from the databases by means of the ACCESS module. The databases will depend on the installation; those that may be available include:

UNARY

Recommended data for the elements

SGSUB

Scientific Group Thermodata Europe database for substances

SGSOL

Scientific Group Thermodata Europe solution database

SALTS

NPL Database for salt systems

to which may be added private or specialised databases managed by individual users or groups.

The following applications are available at present to calculate:

ISOPLETH

Calculation of temperature-composition sections of phase diagrams of multicomponent, multiphase systems at a fixed pressure

NEWISOLIQ

Calculation of liquidus or solidus curves of temperature-composition sections of phase diagrams of multicomponent, multiphase systems at a fixed pressure

TRISECT

Calculation of triangular composition sections of phase diagrams of multicomponent, multiphase systems at a fixed temperature and pressure

LIQPROJ

Calculation of primary phase field for a ternary system at a fixed pressure. Liquidus contours may be superimposed in the future

LIQSECT

Calculation of liquidus contours and primary phase fields for a triangular cut in composition through the phase diagram of a multicomponent, multiphase system (contours generated from calculated temperatures on a triangular grid)

LIQCONT

Liquidus temperature contours for a triangular cut in composition through the phase diagram of a multicomponent, multiphase system (other phase boundaries also possible)

SCHEIL

Solidifications calculations based upon the Scheil model

CPSCHEIL

Updated version of SCHEIL with access to system enthalpy and heat capacity

TSCHEIL

High performance version of CPSCHEIL

ADIABAT

Adiabatic temperature calculations for the mixing of different reaction streams

TRANSN_X

Calculation of phase boundary compositions in multicomponent, multiphase systems for a fixed temperature and pressure

TRANSN_T

Calculation of phase boundary temperatures (eg liquidus and solidus temperatures) in multicomponent, multiphase systems for a fixed overall composition and pressure

TRANSN_P

Calculation of phase boundary pressures in multicomponent, multiphase systems for a fixed overall composition and temperature

PX

Calculation of pressure - composition phase diagrams for a fixed temperature

TP

Calculation of pressure - temperature phase diagrams for a fixed composition (eg unary phase digrams)

ACTSECT

Calculation of component activity contours for a triangular cut in composition through a multicomponent system (contours generated from calculated activities on a triangular grid)

ENTHCONT

Calculation of enthalpy contours for a triangular cut in composition through a multicomponent system (contours generated from calculated enthalpies on a triangular grid)

SPINODAL

Calculation of spinodal curve and two phase boundary for a selected phase exhibiting immiscibility in a binary system

GSURFUN

Gibbs energy plotted as a function of temperature and pressure for a unary system

GSURFBIN

Gibbs energy plotted as a function of composition and temperature for a binary system

GSURFTER

Gibbs energy plotted as a function of composition and temperature for a ternary system

LIQSURF

Liquidus surface replotted from a ".liq" file created using LIQSECT application

STREAMSTEP

Simple process model. A starting composition is specified and a series of equilibrations are carried out. Before each equilibration material is added from an input stream (composition specified by users) and after each equilibration material is removed as an output stream (phases specified by the user). Results are stored in a ".gph" file for plotting as in Multiphase

TEMPCONT_FIXENTHCalculation of temperature contours for a triangular composition sections in a multicomponent system with fixed enthalpy values ie equivalent to ADIABAT application but over ranges of compositions.

Output can be produced in tabular or graphical forms and sent both to the screen and to a file and hence to a printer.

Brief summary of commands

DEFINE allows the user to name the datafile from which the data will be retrieved or to define the system retrieving data from a named database or databases. The datafile would normally have been prepared in advance by means of the ACCESS module.

LIST displays the current definition of the problem in terms of:

(a) the status of the elements, components, substances and phases present
(b) initial and/or equilibrium quantities of components SET by the user
(c) temperature and pressure/volume set by the user.

CLASSIFY allows the status of individual components, phases and substances to be classified as NORMAL (present), ABSENT or FREE for the purposes of a subsequent calculation. The reference phase for individual or all components can be selected. The number of miscibility gaps potentially present may also be specified. A computational parameter DELTA required to deal with FREE components can be fixed in this option.

SET allows the user to specify the temperature, pressure/volume, and quantities within the system. Quantities may be defined in terms of either total amounts or mass of each component in the system or amounts of certain substances present at equilibrium. Equilibrium amounts may be specified in terms of moles, kilograms, mole fraction, partial pressure or molality. A special use of SET is to name and define the end points (GROUPS) of a stepped sequence in overall composition composition and to assign values for user variables which provide a mechanism for application specific variables to be transferred into the application.

RANGE is used mainly in the preparation of graphs. Variables that can be given a range are temperature, pressure, log10 pressure and the composition. The user enters the start, finish, tolerance and the number of steps over which calculations are to be performed. For composition the start and finish are defined in terms of the names of the start and finish composition groups as defined by the SET command.

COMPUTE initiates the computation of the defined application. The STAGES used and the method of initiating the calculation can be changed. For some applications the type of output can be varied to provide more or less detail.

ORDINATE is used to select which, out of many possible variables, is plotted as ordinate, to select log or non log scales and their range.

ABSCISSA is used to control which variable is plotted as abscissa. This does not need to be the originally stepped variable. Log or non log scales may be chosen and their range controlled.

PLOT is used to retrieve a previously calculated graphics file for plotting, to change the physical characteristics of the plot and to initiate the plot itself.

LASER sends a copy of any diagrams plotted on the screen to a local plotting device if available.

RETURN takes the user out of APPLICATION back to the module level.

<"Macro name"> runs a macro taken from a file. The name of the file should be entered in quotes. Commands can also be passed through to the operating system by prefixing them with a $ (dollar sign). The dollar sign and operating system command should be entered within quotes.


Further Information

A gentle introduction to using the options available in APPLICATION contains annotated examples, each directed towards achieving a particular outcome and shows typical combination of commands which would be necessary to achieve that end.

A simple summary of the commands available can also be used as an index to obtain more detailed help about each command.

 

Updated 9 June 2011