Patent ID: 7422727

Claim:
An apparatus for preparing hydrazodicarbonamide comprising: a pyrolysis furnace to obtain biuret and ammonia by pyrolyzing urea; a recrystallization reactor to purify the biuret obtained from the pyrolysis furnace; a first reactor to obtain an metal monohalobiuret salt by reacting the biuret with metal hypohalogen compound or with halogen and base; a second reactor to synthesize the hydrazodicarbonamide by reacting the monohalobiuret metal salt with ammonia; and an ammonia evaporator to separate the excess ammonia from hydrazodicarbonamide and to supply the separated ammonia to an ammonia concentrator, wherein wherein the ammonia concentrator is to concentrate the excess ammonia and ammonia obtained at the pyrolysis furnace, and is to supply the concentrated ammonia to the second reactor.