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

Chapter 3Installation of a tower with a dry absorbent material. Figures are not known but a NO Xreduction of at least 70 % during startup can be expected.Cross-media effectsHeating the tail gas. Energy is required to raise the temperature to the optimum needed forthe SCR or NSCR facility.Installing a low temperature SCR. The NH 3 added to the SCR and the nitrous gases in the tailgas could react to form ammonium nitrate or ammonium nitrite when the tail gas passesthrough an SCR as a result of these unstable process conditions and low temperatures duringstartup. Deposits of these salts could potentially cause an explosion. The temperature of thetail gas must be 180 °C or higher when the SCR is started, to minimise the risk.Installing a scrubber. A large amount of water vapour will escape from the scrubber liquiddue to the high tail gas temperature when an SCR is used at between 200 and 350 °C. As aresult, water consumption is high. The used scrubber fluid cannot be re-used, and it has to bedisposed of as waste.Installation of a tower with a dry adsorbent material. The spent adsorbent material is a wastefor disposal.Operational dataNo specific information provided.ApplicabilityHeating the tail gas. A tail gas heating unit needs lots of space, particularly when enclosed, butcan be applied in new and existing nitric acid plants with an SCR or an NSCR. Energy isneeded to raise the temperature to the optimum needed for the SCR or NSCR facility, i.e. 180to 450 °C.Installing a low temperature SCR. Enough space should be available to install this facility.When the old catalyst is replaced, the new one should fit into the facility.Installing a scrubber. There must be enough space to place the rather large scrubber facility.Installation of a tower with a dry adsorbent material. Free space must be available andsufficient to install an adsorber facility. The high temperatures that are necessary before theSCR can be started, i.e. 200 – 350 °C, could damage the adsorbent.EconomicsGenerally, most end-of-pipe technologies to reduce startup and shutdown emissions are quiteexpensive in comparison to the NO x reduction.Heating the tail gas. Equipment costs for a burner are approximately NLG 200000 (aboutEUR 91000). Installing a furnace (equipment and engineering) will cost at least NLG1000000 (EUR 450000). Other economics are not known.138 Large Volume Inorganic Chemicals – Ammonia, Acids and Fertilisers