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

Chapter 88.5 BAT for Urea and UANBAT is to apply the common BAT given in Section 1.5.BAT for storage is to apply BAT given in [5, European Commission, 2005].BAT is to improve environmental performance of the finishing section by one or a combinationof the following techniques:• apply plate bank product cooling (see Section 7.4.5)• redirecting urea fines to the concentrated urea solution• select proper size of screens and mills, e.g. roller or chain mills• apply surge hoppers for granulation recycle control• apply product size distribution measurement and control.BAT is to optimise the total energy consumption for urea production by applying one or acombination of the following techniques:• for existing stripping installations, continue applying stripping technology• for new installations, applying total recycling stripping processes (see Sections 8.4.2, 8.4.3and 8.4.4)• for existing conventional total recycling installations, only in the case of a substantial ureaplant capacity increase, upgrading to stripping technology (see Section 8.4.7)• increase heat integration of stripping plants (see Section 8.4.8)• applying combined condensation and reaction technology (see Section 8.4.9).BAT is to treat all exhaust gases from the wet sections by scrubbing, taking into account thelower explosion limit and to recycle the resulting ammonia solutions to the process (e.g. seeSection 8.4.5).BAT is to reduce ammonia and dust emissions from prilling or granulation and to achieveammonia emission levels of 3 – 35 mg/Nm 3 , e.g. by scrubbing or optimising the operationconditions of prilling towers, and to re-use scrubber liquids on-site (see Section 7.4.11). If thescrubbing liquid can be re-used, then preferably by acidic scrubbing, if not, by water scrubbing.In optimising the emission levels to the values mentioned above, it is assumed that dustemission levels of 15 – 55 mg/Nm 3 are achieved, even, with water scrubbing.Where process water with or without treatment is not re-used, BAT is to treat process water, e.g.by desorption and hydrolysation and to achieve the levels given in Table 8.20 (see Section8.4.12). If in existing plants the levels cannot be achieved, it is BAT to apply subsequentbiological waste water treatment.NH 3UreaAfter process watertreatmentNew plants 1 1Existing plants