Pyrolysis and Kinetic Characteristics of Ammonium Salt in Solid-State Ammonium SCR System for Heavy Duty Diesel Engine[J]. 2017, 51(9): 44-53.
DOI:
Pyrolysis and Kinetic Characteristics of Ammonium Salt in Solid-State Ammonium SCR System for Heavy Duty Diesel Engine[J]. 2017, 51(9): 44-53.DOI: 10.7652/xjtuxb201709007.
Pyrolysis and Kinetic Characteristics of Ammonium Salt in Solid-State Ammonium SCR System for Heavy Duty Diesel Engine
The pyrolysis and kinetic characteristics of ammonium salts in solid ammonium selective catalytic reduction(SCR)system are investigated to provide theoretical and technical supports for design of solid ammonia SCR gaseous ammonia production and supply system. The pyrolysis characteristics of three kinds of ammonium salts
including decomposition temperatures and rates
are analyzed by thermogravimetric test and decomposition equilibrium pressure test
and the decomposition kinetics parameters of ammonium carbamate and ammonium carbonate are calculated with isothermal method and integral method. The thermal decomposition of ammonium carbonate and ammonium carbam
ate are completed at constant temperature to determine the relationship between the residual mass ratio and the heating time
and the rate constants and reaction orders are obtained by the mass ratio versus reaction time in thermogravimetric analysis curves. The results show that the decomposition rate of ammonium carbamate gets higher than that of ammonium carbonate and ammonium bicarbonate; the reaction order of ammonium carbamate is 1/2
and that of ammonium carbonate is 2/3; the activation energy of ammonium carbamate and ammonium carbonate reaches respectively 56 kJ/mol and 62 kJ/mol; ammonium carbamate and ammonium carbonate are suitable to be the source of the reducing agent of SSCR system
and the advantage of ammonium carbamate is more obvious. Compared with urea SCR technology
solid-state ammonium SCR technology can provide more sufficient amount of reducing agent when the engine is at low exhaust temperature
so that the conversion efficiency of low-temperature NO
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