Simulation

Software for Process Simulation

A modern approach to development of chemical technologies is based on computer simulation of processes and equipment.  For developing new processes, revamping or retrofitting existing plants, and analyzing performance of process systems it is necessary to use mathematical models and computer analysis.

A mathematical model of the process scheme to be developed reflects the nature of physical & chemical processes, design features of equipment as well as process interconnections between the elements of the process system. In general terms, the model is a set of non-linear equations of mass and heat balances and equations of functional relations. Such set of equations cannot be built and solved without computer simulation programs.

Our company applies a specialized proprietary software computational complex that gives undeniable advantages during process simulation such as:

— Possibility to customize computational modules to customer’s process and equipment design specifics;
— Quick and efficient use of recent achievements of global science in the field of chemical process simulation;
— Possibility to “adjust” models based on experimental data within the required parameter ranges.

The mathematical models are based on the basic principles and laws of thermodynamics, hydrodynamics, chemical kinetics, and heat transfer theory.

The mathematical modeling is applied at all technical decision-making stages:

  • Development of process flow diagram.  Making optimum choice from a variety of alternative multiply-calculated solutions.
  • Calculation of equipment parameters and design in order to achieve the specified process characteristics.
  • Assessment of equipment condition by modeling of process parameters based on plant survey data.
  • Assessment of plant process performance.

We have created a unique database for each process task to be solved. It covers the physical & chemical process basis, process system structure data, set of computational modules for process equipment with input data and design data.

Our software enables to compute both flow-through and circulation loop-based process schemes. Through multiple computations we define the optimum process parameters of both the whole system (capacity, circulation ratio, number of blowdowns, etc.) and individual equipment parameters (catalyst charge volume, arrangement of reaction and heat exchange tubes, compressor and pumps capacity, etc.). The use of kinetic dependencies allows making a detail calculation of reactors and assessing process conditions at various catalyst activities (SOR, EOR). The application of respective phase equilibrium models to calculate mass transfer equipment makes possible to obtain an adequate model of the distillation stage.

The computation results are presented in form of diagrams, tables, and graphs.

Our software is a unique computational complex comprising databases, computational modules and interface part.

We have developed a special software including a bank of kinetic dependencies to describe catalyzed chemical conversion processes.

A number of models and computational modules is used for calculating non-standard process equipment such as hydrocarbon feed reformers of various types, ammonia and methanol converters of various designs, WHBs recovering reformed and flue gas waste heat with due consideration of equipment design features.

Software Complex Structure

1. Data Support
1.1. Database of Individual Substance Properties

The database contains the numerical values of the constants for calculating physical & chemical properties of individual substances within temperature and pressure ranges. It is used as a basis to calculate properties of multicomponent fluids and characteristics of physical & chemical phenomena.

1.2. Bank of Binary Parameters

The bank contains the values of binary interaction parameters for improving accuracy of equilibrium calculations for vapor-liquid and vapor-liquid-liquid multicomponent mixtures.

1.3. Database of Kinetic Dependencies

The bank contains the kinetic dependencies  with numerical values of the constants for the following processes:
— Methane steam reforming over nickel catalyst;
— HT CO shift over iron-chromium catalyst;
— LT CO shift over copper-containing catalyst;
— Homogeneous CO shift;
— Ammonia synthesis over iron catalyst;
— Methanol synthesis over copper-containing catalyst;
— DME synthesis;
— Ammonia decomposition over Ni-Al2O3 catalyst;
— Homogeneous oxidation of NO to NO2 .

1.4. Database of Catalysts for Catalytic Stages of Ammonia and Methanol Production Plants

The bank contains characteristics and properties of basic catalysts used in ammonia and methanol production plants.

2. Simulation Software
2.1. Basic Algorithm Library

The library is a basis of computational modules. It comprises a set of programs for calculating  the properties of process fluids, chemical conversion parameters, hydrodynamic characteristics and heat and mass transfer processes for various conditions.

2.2. General-Purpose Computational Modules

A basic set of computational programs for modeling most of process equipment items such as:
— Mixing and separation systems;
— Pumps, compressors;
— Heat exchangers: shell-and-tube exchangers, coils, fired heaters and burners;
— Mass transfer equipment: separators, absorbers, distillation columns;
— Kinetic catalytic reactor with radial or axial gas flow pattern for calculation of chemical conversion;
— Equilibrium model-based chemical reactor;
— Reactor for homogeneous gas phase kinetic non-catalytic processes.

2.3. Computational Modules for Special Equipment

2.3.1. Hydrocarbon Feed Reforming:
— Reformer with arch burners;
— Reformer with staged burners;
— Reformer with terrace wall burners;
— Reformer convection coils and natural-circulation and forced-circulation boilers;
— Steam-oxygen (steam-air) reformer.

2.3.2. Ammonia Synthesis
— 4-bed axial flow-type ammonia converter;
— 3-bed ammonia converter with radial basket and inter-bed heat exchanger;
— 2-bed ammonia converter with radial basket and inter-bed heat exchanger.

2.3.3. Methanol Synthesis
— Multiple-bed axial flow-type methanol converters  with inter-bed cold shot or gas cooling in heat exchangers;
— Radial flow-type methanol converters;
— Tubular-type steam-raising methanol converter;
— Methanol converter with recuperative plate-type steam-water or gas interchanger.

2.3.4. Other Equipment
— Multi-row WHB recovering flue gas waste heat with naturally circulated heat transfer medium;
— Shell-and-tube WHB recovering  reformed gas waste heat with naturally circulated heat transfer medium;
— WHB recovering nitrous gas waste heat;
— Nitrous gas absorber.

3. Interface Part of Software Complex

This part of software complex enables a user-process engineer to form a computational base of the task.
It performs the following functions:
— Assignment of physical & chemical basis of the computational task;
— Assignment of process system structure;
— Assignment of initial data for each equipment item;
— Task computation management;
— Displaying output data in form of tables and graphs.

4. Auxiliary Modules

  • Set of special programs (controllers) for computation management and data output.
  • Set of auxiliary modules for processing experimental and published data to determine and/or reconfirm  numerical values of equation parameters.