Gaseous ammonia generating system used for marine tail gas purification device

The invention provides a gaseous ammonia generating system used for a marine tail gas purification device. The marine tail gas purification device comprises a particulate matter removing device and a catalytic reduction device. The gaseous ammonia generating system comprises a gas flowing type mist spraying system and a mist spraying adjusting device. A urea solution is sprayed out through a mist spraying opening of the gas flowing type mist spraying system to be fully mixed with high-temperature tail gas sprayed out from a marine diesel engine, and biuret and gaseous ammonia which is used by the catalytic reduction device are generated. The spraying quantity of the urea solution is controlled by the mist spraying adjusting device. The gaseous ammonia generating system directly conveys the urea solution into the marine tail gas purification device through a pipeline, the urea solution is fully mixed with the high-temperature tail gas, thus the gaseous ammonia and the biuret are generated, and a gaseous ammonia generating device composed of an ammonia gas evaporator, an ammonia gas buffer tank, a gas flow valve and other huge devices in a selective catalytic reduction method is replaced. As for most diesel engines which are mobile pollution sources, the gaseous ammonia generating system can generate the gaseous ammonia in real time according to the demanded quantity of tail gas purification for marine diesel engines. In addition, the urea solution is used, the stability is good, and thus the work safety of the whole gaseous ammonia generating system is higher.