ProSimPlus HNO3

Simulation and optimization of nitric acid plants and nitrous vapors absorption

ProSimPlus HNO3 is a unique process engineering tool, specifically designed to model nitric acid production plants and nitrous vapors absorption units.

It allows engineers to represent accurately and to analyse processes in which the absorption of nitrous vapours and associated complex physico chemical phenomenon intervene (nitrogen monoxide oxidation reactions, nitrogen dioxide dimerization reaction, nitrogen oxides absorption in nitric acid aqueous solutions...).

It is used in design phases as well as in plant operations for process optimization, unit debottlenecking or plant revamping. Thanks to a reliable modeling of the unit steady-state behavior, it helps to generate significant improvements in efficiency and profitability as well as to increase reactivity when facing new regulations.

Why a specific software?

The complexity of the physical and chemical phenomena involved in nitric acid processes (chemical reactions in gas phase in nearly all the equipment pieces, thermodynamic properties not easy to model,…) and the specificity of the equipment used in these units make the simulation of these processes nearly impossible with a general purpose simulation software. It is necessary to take into account sizing parameters (pipes volume, absorption column trays spacing,…) at early process design stage as, when adding oxidation volumes, they affect the mass and energy balances. It is generally not the case in other processes and therefore not taken into account in standard simulation software.

The unit operations required to represent your processes accurately

In addition to the unit operation library usually available in general simulation packages, ProSimPlus HNO3 offers a full set of equipment specific to nitric acid production processes, in particular:

• Absorption columns for nitrous vapors by aqueous nitric acid solutions taking into account chemical reactions in gas phase, mass transfer with chemical reaction in liquid phase.Available with possibility of several feeds or nitric acid side streams, and as plate or packing towers, spray columns, plate coolers, etc.
• Heat exchangers, with possibility to take into account oxidation reactions in gas phase
• Chemical reactors (or oxidation volume): oxidation of nitrogen monoxide in vapor phase and dimerization of dioxide in peroxide with tube flow or CSTR option. Adiabatic, isotherm or output temperature specified general reactor (possibility to specify conversion rates or selectivities) which can be used to simulate for example NOx reduction by ammoniac
• Nitrous vapors compressors: monostage or multistage isentropic or polytropic compressor (possibility to specify from the manufacturer flow curves), monostage or multistage expander turbine (condensation possibility), isentropic or polytropic efficiency, pipe pressure drop

Additionally, ProSimPlus HNO3 is a particularly open software in which the user can integrate his own models and specific know-how.

A vast know-how in properties and chemical reactions already integrated

ProSimPlus HNO3 includes physical and chemical models built on many years of research and validated by intensive industrial use. As these elements are readily available in the software, the user can concentrate on other aspects of his process. Among these elements one will find in particular:

• A complete properties database of the components involved in these types of process (H2O, NO, NO2, N2O4, N2, O2, HNO3, NH3, N2O, N2O3, HNO2, CO2, CO, CH4, H2, SO2, SO3).
• A thermodynamic model based on equations, obtained from experimental measurements and able to accurately represent the non-ideality of the liquid phase (liquid fugacity, excess enthalpy, solution density, etc)
• A model particularly well suited to strong nitric acid concentrations (concentration or bleaching columns)
• Mass transfer with chemical reactions in liquid phase automatically taken into account: N2O4 and N2O3 absorption, HNO3 and HNO2 hydrolysis and HNO2 decomposition
• Chemical reactions in gas phase automatically taken into account, with specific correlations:
  • NO to NO2 oxidation reaction kinetic model in gas phase: Sherwood’s, Koukolik and Marek, etc
  • NO2 to N204 dimerisation equilibrium constant in gas phase: Koukolik and Marek, Bodenstein, etc
  • N2O3 formation equilibrium constant in gas phase: Miller, Beattie and Bell, etc
  • NOx-H2O-HNO3 systems equilibrium constant: Koukolik and Marek, Zhidkov, Carberry, etc.

All the chemical reactions likely to take place in nitric acid production or in nitrous vapors absorption processes have been integrated in ProSimPlus HNO3: nitric acid (HN03), nitrous acid (HN02), nitrogen dioxide (N02), nitrogen trioxide (N2O3) and nitrogen tetraoxide (N2O4) formation reaction. The description of a process then becomes very easy and the quality of calculations performed is ensured.

The reference software, quickly adopted by users

World leading engineering firms in the nitric acid field and most efficient fertilizers producers already rely on ProSimPlus HNO3 to design new units or revamp existing installations. This software is also very useful in industries that need to deal with NOx: energy, chemical, nuclear, etc.

No software, regardless of power, will bring payback if it is not used, however, only very few companies can maintain an expert in simulation. ProSimPlus HNO3 utilization is very intuitive. Users who are accustomed to other simulation tools are surprised how easy to use the software is and beginners do not need long and expensive training to become fully operational. The graphical interface provides a large set of functionalities to easily and quickly exploit results: fully configurable table summarizing the streams characteristics, on-line help, unit systems management, results under HTML, MS-Excel.

Additionally, ProSimPlus HNO3 is available in French and English.