Residual Analysis of the Residual Analysis of the Production of Nitric AcidProduction of Nitric Acid

Erik Tolonen

Nick Poulin

Environmental Engineering

Environmental Planning and Decision Making

ENVE4104

Residual Analysis:

Residuals are leftover material and energy from industrial processes

Residuals can be harmful to the environment

RA Can be used to analyses a process and increase its efficiency

We are only focusing on the production side for simplicity

Background:

Nitric Acid among the 10 chemicals produced in the largest amounts

Used for explosives, dyes and most importantly Fertilizers

Unstable in its liquid form, decomposes quickly into nitrous oxidesCompletely miscible with water, mainly produced and used in its aqueous state

High Pressure process used in our Residual Analysis, other processes include athmospheric and split pressure

Chemical Equations:

NH3 + 1.25 O2 NO + 1.5 H2O H298K = -226kJ/mol

Oxidization of Ammonia:

2NO + O2 <-> 2NO2 H298K = -114kJ/mol

Oxidization of Nitric Oxide:

3NO2(g) + H2O(l) <-> 2HNO3(aq) + NO(g) H = -135.6 kJ/mol

Absorbtion of Nitrogen Oxides & Production of Nitric Acid:

Air

Air Filter

Ammonia NH3 (g)

Ammonia Converter

NO (g)

Warm Water Circulate

Compressor

Oxidization of Ammonia

Evaporator

NO (g)

Heat Exchanger

NO2 (g)

Condenser

Cold Water Circulate

HNO3 (aq)

Bleacher HNO3 (aq)

Filtered

Air

Absorption Tower

Formation of Nitric Acid

Tail Gases

To Catalytic Combustor

Catalytic Combustor

Compressor

Waste Heat Boiler

Vent

Tail Gases

Emissions:

Emissions:

Absorption Towers used to reduce nitrous oxides in the tail gas (NOx)

Catalytic Combustor used to convert nitrous oxides to elemental nitrogen

Waste heat from processes is recycled for other plant processesEmissions can be reduced to under 200 ppm

Calculations:

Absorption of Nitrogen Oxides:Nitrous Oxide: (NO) 119 tonnes/yrNitrogen Dioxide (NO2) 548 tonnes/yrWater: (H2O) 71 tonnes/yrNitric Acid: (HNO3) 500 tonnes/yr

2NO + O2 <-> 2NO2 H298K = -114kJ/mol

NH3 + 1.25 O2 NO + 1.5 H2O H298K = -226kJ/mol

3NO2(g) + H2O(l) <-> 2HNO3(aq) + NO(g) H = -135.6 kJ/mol

Oxidation of Nitric Oxide:Nitrous Oxide: (NO) 357 tonnes/yrOxygen: (O2) 190 tonnes/yrAir: (O2 + N2) 907 tonnes/yr

Oxidation of Ammonia:Ammonia: (NH3) 202 tonnes/yrOxygen: (O2) 476 tonnes/yrAir: (O2 + N2) 2269 tonnes/yrWater: (H2O) 321 tonnes/yr

Energy:Compressor: 521.1 GJ/yr (16.5kW)Waste Heat Boiler: 208.44 GJ/yr (6.6kW)Net: 312.7 GJ/yr (9.9kW)

Conclusion:

References:

[1] Nitric Acid