Experimental Study on Important Components of Urea Deposits for SCR System

MO Chunlan; LONG Hualin; MO Yitao; QIU Chonghuan; JIANG Mingru; HUANG Fuchuan

Vehicle Engine ›› 2021, Vol. 0 ›› Issue (2) : 76-81.

MO Chunlan,LONG Hualin,MO Yitao,QIU Chonghuan,JIANG Mingru,HUANG Fuchuan

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Abstract

In order to reduce the urea spray deposits for the SCR system of diesel engine, thermogravimetric tests were conducted at a heating rate of 10 ℃/min to analyze the composition, content and formation of urea deposits. The results show that the urea deposits are mainly composed of biuret, cyanuric acid and their homologues. The generated isocyanic acid triggers the formation of various deposits and its insufficient hydrolysis is an indispensable condition of urea deposits. Cyanuric acid and its homologues can be generated by side reactions of urea or biuret, in which biuret is the key substance. Cyanuric acid produces a small amount of byproducts in its pyrolysis process. Ammelide and ammeline are the main reactants to produce high temperature resistant products. About 20% mass proportion of urea deposits is biuret, about 60% is cyanuric acid and about 20% is cyanuric acid homologues. The test results provide a reference for the improvement of reaction kinetic mechanism and formation prediction of urea deposits.

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SCR / thermogravimetric test / urea / deposit / component

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MO Chunlan,LONG Hualin,MO Yitao,QIU Chonghuan,JIANG Mingru,HUANG Fuchuan. Experimental Study on Important Components of Urea Deposits for SCR System[J]. Vehicle Engine. 2021, 0(2): 76-81