Three processes(liquid ammonia evaporation

urea pyrolysis

urea hydrolysis) to produce ammonia used as reductant in denitrification by selective catalytic reduction(SCR) method was compared on aspects such as raw material sources

technological process

land occupation

investment operating cost and running safety.Results show that

compared with ammonia production from urea

the liquid ammonia evaporation process has low construction and operation costs

while the urea methods can save the land occupation area and raw material cost.Running cost of urea hydrolysis process is lower than that of the pyrolysis process.Factors that should be considered in selecting the preparation programs of NOx reducing agent

as well as the development trends of each technology are both proposed.