Application of Commercial Grade Ammonia Liquor in the Selective Non–Catalytic Reduction of NO× in Combusted Gas from a Diesel Burner

Abstract

Satu kajian menggunakan rig skala pandu dengan Penurunan Tanpa–bermangkin Terpilih (SNCR) telah dijalankan menggunakan larutan akuas likur ammonia gred komersial sebagai agen penurunan NO_× di dalam gas ekzos yang membakar diesel pada 6% oksigen lebihan dan dengan suhu pancitan antara 923 dan 1323 K. Relau ini mensimulasikan sistem pembakaran skala–kecil seperti dandang muatan rendah, pemanas air dan pemanas minyak, dan sebagainya, yang menghasilkan NO_× garis dasar yang rendah selalunya di bawah 100 ppm dan di mana suhu kendalian sentiasa berada dalam julat suhu yang dikaji. Dengan larutan 5% akuas ammonia, pada Nisbah Stoikiometrik Ternormal (NSR) 4, sekurang–kurangnya 57% pengurangan telah diperolehi pada suhu optimum 1063 K, yang mana adalah amat ketara bagi aras NO_× garis dasar yang dikaji. Pengurangan NO_× ini didapati meningkat dengan meningkatnya nilai NSR. Masa mastautin regen ini mempunyai kesan yang ketara ke atas prestasi tindak balas, namun, kebanyakan daripada pengurangan berlaku di dalam julat masa mastautin yang pendek dan selepas itu penambahan selanjutnya dalam masa mastautin tidak menunjukkan sebarang perubahan yang ketara. Pengukuran gelincir ammonia menunjukkan bahawa pada suhu optimum dan NSR 4, gelincirnya ialah sekitar 18 ppm. Kajian ini juga menunjukkan bahawa ammonia likur gred komersial berpotensi sebagai agen penurunan NO_× yang boleh digunakan secara selamat dan berkesan jika dipertimbangkan masalah mudarat kesihatan. Kata kunci: SNCR, NO_×, NSR, gelincir ammonia A pilot–scale investigation with Selective Non–catalytic Reduction (SNCR) of NO_× were carried out by employing the aqueous solution of commercial grade ammonia liquor as NO_× reducing agent in diesel burning exhaust at 6% excess oxygen and injection temperatures between 923 and 1323 K. The furnace simulated the small–scale combustion systems such as low capacity boilers, water heaters, oil heaters etc., which produce low level of baseline NO_×, usually below 100 ppm and where the operating temperatures remain within the investigated temperature range. With 5% aqueous ammonia solution, at a Normalised Stoichiometric Ratio (NSR) of 4, as much as 57% reduction was achieved at an optimum temperature of 1063 K, which is quite significant for the investigated level of baseline NO_×. The NO_× reduction was observed to increase as the value of NSR increased. The residence time of the reagent has significant effect on the reaction performance, however, most of the reduction occurred within a short range of residence time and after that further increase in residence time showed very insignificant effect. The ammonia slip measurement showed that at optimum temperature and NSR of 4, the slip was about 18 ppm. The investigations demonstrate that commercial grade liquor ammonia is a potential NO_× reducing agent, which could be used effectively and safely considering the health hazards. Key words: SNCR, NO_×, NSR, ammonia slip