This paper focuses on detecting the mass fraction of urea during the preparation of ammonia

the reducing agent of flue gas denitration system in boilers. On the basis of post-distillation titration method in GB/T2441.1—2008 for determining the total nitrogen content of urea

and combining with the approach of urea solution test method

an improved chemical method was proposed to detect the urea content. Moreover

this method was applied to measure the mass fraction of the urea collected from ammonia preparation device of a power plant

and the value was 99.56%

which is consistent with that by the distillation titration method. Besides

this result also agrees with that obtained by the standard method(Back deriving the ?

? and ? values by using mass fraction of biuret and methylene diurea in the sample). The improved chemical detection method is accurate

reliable and can obtain the mass fraction of urea from different batches rapidly

which can provides data basis for field work.