Large Volume Inorganic Chemicals - Ammonia ... - ammk-rks.net

Chapter 9Cross-media effectsProcess using increased pressure might require energy for NH 3 compression.Operational dataNo specific information provided.ApplicabilityThe issues listed above are not only relevant to prevent environmental effects, and hazardousconditions, but also ensure a high quality of product and a more efficient process. The balancebetween these parameters is very sensitive. It can be assumed that these parameters will havebeen optimised for the technical specification of the existing plant. Neutralisers working underpressure or over two-stages to improve environmental performance are technically feasible forbackfitting to an existing plant but may be economically non-viable.EconomicsThe optimisation of the neutralisation section is not only relevant from an environmental pointof view, it also optimises the process. Higher investments for, e.g. two-stage neutralisers, arelikely to repay themselves. Single-stage neutralisers are cheaper and simpler.Driving force for implementationAll plants across the world could be expected to operate at an optimum within the technicallimitations of the plant. In principal, better performances are obtained using neutralisersworking at low pH and/or at high pressure.References to literature and example plants[52, infoMil, 2001], AMI, LinzDSM Agro IJmuiden (the Netherlands) uses two-stage neutralisers. The first stage takes place inan acid environment, pressurised to 2 bar. The AN solution is depressurised before sending it tothe second stage, where the solution is neutralised. [10, InfoMil, 2001]Kemira Agro Rozenburg (the Netherlands), which is now closed, used a two-stage neutraliser.The first step of the neutralisation took place at a pH value of 2 to prevent ammonia losses. Inthe second step, the solution was neutralised to pH 6.Lovochemie (Czech Republic) uses a single-stage neutraliser pressurised to 3.5 bar and theconcentration of resulting AN is 72 – 75 % at a temperature of 168 – 171 ºC.Large Volume Inorganic Chemicals – Ammonia, Acids and Fertilisers 375