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

Chapter 3NOx removal efficiency in %10 0908070605040NO x level at the inlet to the SCR (lowest: 200, highest: 2500 ppm)Figure 3.12: NO x removal efficiencies of SCR units applied in HNO 3 plantsThe efficiencies are related to the NO x inlet concentrations of the plant. This figure is based on datagiven in Table 3.8Cross-media effects• ammonia consumption depending on the amount of NO x reduced• ammonia slip, usually less than 10 ppm (7.6 mg/Nm 3 )• older catalysts in particular could produce some N 2 O.Operational data• optimum operating temperature varying from 200 to 350 °C• pressure drop before the expander unit of 0.01 – 0.1 bar• the tail gas temperature after reduction of 200 – 360 °C is significantly lower than in thecase of NSCR (650 – 800 °C), allowing the use of simpler, cheaper construction materials.ApplicabilityGenerally applicable. In principle, SCR facilities can be applied in both new and existing nitricplants and can operate at all pressures.Due to safety concerns, an SCR facility is usually not operated at inlet gas temperatures ofbelow 180 ºC [154, TWG on LVIC-AAF, 2006].EconomicsBased on an M/H plant with a production output of 1000 tonnes 100 % HNO 3 /day and an operatingtime of 8400 hours/year, the costs of an SCR are as follows:• capital costs: EUR 2000000• annual costs: EUR 300000• total costs: approximately USD 1.3/tonne HNO 3 produced in 1998 (in 1998 about EUR1.16/tonne HNO 3 produced).Assuming a catalyst price of between USD 35000 and 53000 per m 3 (about EUR 32000 – 49000 perm 3 ), excluding technical and maintenance costs, a catalyst volume of 3.75 m 3 at a flowrate of 48235m 3 /hour, ammonia consumption of 77 kg NH 3 /hour and a NO x reduction from 2000 to 150 ppm(from 4100 to 308 mg/Nm 3 ), the following costs can be calculated:Large Volume Inorganic Chemicals – Ammonia, Acids and Fertilisers 133