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

Chapter 3Option 1 Option 2 Option 3Design values, lowsteam exportLow HNO 3concentration, lowsteam exportMost economicoption, high steamexportAbsorption pressure in bar 15 15 12Produced HNO 3 concentration in % 65 56 60NO x tail gas levelppm 100 40 130 – 170mg/Nm 3 205 82 267 – 349Table 3.11: Theoretical study of the optimisation of the absorption stage design at ZAK, Tarnow[88, infoMil, 1999]The nitric acid plant of Yara, Porsgrunn was built in 1992 and has a capacity of 2000 tonneHNO 3 /day. It is a M/H plant (5/11 bar). Due to the design of the absorption column and thetemperature of the cooling water (as a result of the climate in Porsgrunn, the temperature of thewater is 4 – 6 o C without cooling), NO x emissions at 80 – 90 ppm (164 – 185 mg/Nm 3 ) wereachieved without using an additional abatement system.The nitric acid plant of Agropolychim, Devnia was built in 2003, has a capacity of 1100tonnes/day and is designed as a M/H plant (3.5/12.8 bar). At absorption temperatures of 20 –40 ºC, NO x levels of 170 – 200 ppm are achieved.Economics• monopressure operation has been shown in the past to give special economical advantages.Capital costs are lower, because only one compression unit is required. When feedstock andenergy prices are low: low investment costs ensure a quick payback. If feedstock and energyprices are high, yield and energy efficiency must be maximised, so higher investment costsare more acceptable. Plant size also plays an important role. For a large production capacity(>1000 tonnes 100 % HNO 3 /day) it is more realistic to build a dual pressure plant• in a dual pressure system, stainless steel compressor units are necessary to compress NO X .As a result, dual pressure plants need investments that are approximately 15 – 20 % higherthan the investment for a monopressure plant. On the other hand, a dual pressure plantoptimises the NO yield and energy recovery, thereby recovering the higher investmentcosts. As stated above, a dual pressure plant is more feasible if a large production capacityis desired (>1000 tonne 100 % HNO 3 /day)• total costs for NO x removal using the HEA system were in 1998 USD 0.6/tonne HNO 3produced (about EUR 0.55/tonne HNO 3 produced, figures based on a 365 tonne 100 %HNO 3 /day plant).Driving force for implementationOptimised HNO 3 yield and lower NO x emissions.Reference literature and example plants[88, infoMil, 1999, 94, Austrian UBA, 2001], ZAK, Tarnow; Yara, Porsgrunn, Agropolychim,Devnia, Haifa Chemicals Ltd.120 Large Volume Inorganic Chemicals – Ammonia, Acids and Fertilisers