Nitric acid process na2000tm

aN advaNced process withwide experieNce

NITRIC ACID PRoCess NA2000Tmcasale

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The NA2000™ nitric acid technology technology is Casale process for plants with capacities ranging from 600 to 2000 MTD. The process was formerly developed and delivered by GP and was acquired by Casale in 2014 together with entire technology portfolio of GP’ Nitrates and Phosphates.

KeY FeatUres

•Dual Pressure process •Proven design•Optimized plant cost•High ammonia conversion •Low emissions•Highest energy efficiency.

Two different processes are available, depending on the operating pressures, respectively:•mono pressure processes •dual pressure processes.In the mono pressure processes the operating pressure is the same throughout the plant whilst in the dual pressure processes ones the oxidation of ammonia takes place at a lower pressure than in the subsequent phase.The typical operating range required is 70 - 110% of the nominal plant capacity.

Nitric acid processesThe investment costs of mono pressure plant are lower than in case of dual pressure ones but their operating costs are higher. Mono pressure processes are usually preferred for small capacity plants.Dual pressure plants are more sophisticated, requiring higher investments on one hand but, on the other hand, having reduced operating costs and for these reasons they are recommended in case of higher capacities.The selection between mono and dual process is usually driven by:• the capacity of the plant• the cost of raw materials, catalysts and utility•specific local conditions or client demands.

absorber

nitric acidbleacher

reactor

ammonia

expander

de nox

air

air

water

Nitric acidprocess Na2000tM

NITRIC ACID PRoCess NA2000Tmcasale

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The nitric acid produced is then bleached with air.The tail gas from the absorber, pre-heated in the two tail gas preheaters, is sent to the selective catalytic reactor for reduction of its NOx and N2O content and then to the tail gas expander for energy recovery.The HP nitrous gas coming from the condenser enters into the bottom of the absorber.The production of the nitric acid takes place on the absorber trays by absorption and reaction of nitrogen dioxide and nitrogen tetra oxide with water fed in the upper tray.The process water flows counter-currently in respect to the nitrous gas, down from the top tray to the bottom of the absorber.The heat released by the acid formation and the NO oxidation is removed by the cooling water circulating in the coils.A discontinuous purge from some trays is effected in order to maintain the chlorides concentration at a low level. The nitric acid is recovered from the first tray of the absorber and sent to the bleacher where the dissolved nitrous gases contained in large amounts, which color the acid, are eliminated by stripping with hot air, reaching a NO

2 content in the colorless, bleached acid of less than 100 ppm (expressed as HNO2).The acid is then finally sent to storage.At the outlet of the absorber the NOx content in the tail gas is usually lower than 600 ppm.The tail gas from the absorber, pre-heated in the two tail gas preheaters, is sent to the selective catalytic reactor for reduction of its NOx and NO content and then to the tail gas expander for energy recovery.

tUrbo MachiNesThe mechanical train includes:•an air compressor to supply the process air•a compressor for the nitrous gases from LP section to HP section•a tail gas expander to recover the energy of the hot tail gas before venting to the atmosphere •a steam turbine to balance the power.

The nitric acid is produced in a dual pressure unit and it is delivered at the battery limits at different concentrations, depending on Client s specific needs, up to azeotropic concentration (69%). The ammonia feed is supplied as liquid and it is first evaporated and superheated, then mixed with air before oxidation in the burner at low pressure.The oxidation of ammonia is favored if occurs at low pressure, while the high pressures promote the subsequent absorption of the nitrous gases and the eventual acid production.

The gas distribution, velocity, contact time and oxidation temperature on the platinum gauzes are optimized to achieve a high ammonia conversion efficiency and to minimize the catalyst lossesAt the outlet of the burner the nitrous gas mixture flows through a train of heat exchangers:•Steam super heater•Waste heat boiler•Tail gas superheater •Economizer •LP reaction water condenser.The heat exchanger train is optimized to maximize both the energy transfer to the tail gas and the production of HP steam. Nitrous gases are then compressed above 10 bar (a) in the NOx compressor. From the outlet of the NOx compressor, the HP nitrous gas enters the Tail Gas Heater. In this process the temperature of the gases increases due to the oxidation of NO into NO

2.At this point the HP nitrous gas is cooled in the tail gas heater while heating the tail gas.The total oxidation heat released in the HP nitrous gas system has been optimized without over-complicating the process and avoiding the risk to work in corrosive areas.The HP nitrous gas cooling and the strong acid condensation occour in the HP cooler condenser.The acid is separated from the HP nitrous gas in a separator at the outlet of the condenser and either recycled to the absorber or sent directly to the bleacher. In the absorber it is fed on the tray with the matching nitric acid concentration.

Na2000tM

process oUtliNe

NITRIC ACID PRoCess NA2000Tmcasale

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services

Casale provides a comprehensive range of services including: •know-how and process design•basic engineering•detail engineering •procurement and supply of all materials.

Furthermore, in combination with their sister company, Casale Project (formerly known as Chemoproject Nitrogen), Casale is in position to supply the entire plant on turnkey basis.

Casale Project is a reputed engineering and construction contractor with over 20 years of experience in the following fields:•Nitric acid•Ammonium Nitrate•Ammonia•Urea melt and granulated•NPK fertilizers•CAN.

Since 2014 Casale Project is part of Casale Group and the synergic combination of their experience as global contractor together with Casale know-how and process leadership in nitric acid technology brings unparalleled advantages to our clients:•Best performances from one of the most referenced process in the world•Minimum environmental impact•Optimized plant configuration for high cost effectiveness•Wide flexibility in the project execution, with capacity to adapt our scope of supply to specific

needs and local conditions•Proven construction capabilities•Effective integration with both upstream processes (ammonia) as well as downstream

(e.g. nitrates), thanks to Casale’s complete technology portfolio encompassing the entire nitrogen fertilizer production chain.

NITRIC ACID PRoCess NA2000Tmcasale

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Nitric acid plaNtBorsodChem, Kazinbarcika

Nitric acid plaNtGPN, Le Grand-Quevilly

NITRIC ACID PRoCess NA2000Tmcasale

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left page Absorption towerleft General view

right Compressor houseNitric acid plaNtZAK, Kedzierzyn

reFereNcesMore than 30 plants worldwide have adopted Casale’s dual pressure process, with capacities up to 1800 MTD, whilst Casale Project has completed 10 nitric acid projects.

Via Giulio Pocobelli, 6 | 6900 Lugano | Switzerland (CH)tel. +41 91 6419200 | fax +41 91 6419291

www.casale.ch | info@casale.ch

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