A system and method for producing compound fertilizer using chemical tail gas

Abstract

The invention discloses a system and method for producing compound fertilizer by utilizing chemical engineering tail gas. The system comprises an ammonia evaporation unit, an ammonium nitrate solution preparation unit and a nitro-compound fertilizer preparation unit which are connected in sequence. The ammonia evaporation unit mainly comprises a liquid ammonia buffer tank, a gas ammonia filter and a gas ammonia superheater which are connected in sequence. The ammonium nitrate solution preparation unit mainly comprises a tubular reactor, a neutralizing flash tank and an evaporation device which are connected in sequence. The nitro-compound fertilizer preparation unit is a high tower granulation device. The gas ammonia superheater in the ammonia evaporation unit is connected with the tubular reactor in the ammonium nitrate solution preparation unit, and the evaporation device in the ammonium nitrate solution preparation unit is connected to the high tower granulation device in the nitro-compound fertilizer preparation unit. Melamine tail gas is filtered and heated through the ammonia evaporation unit and then enters the ammonium nitrate solution preparation unit to be prepared into ammonium nitrate solution together with nitric acid, and finally the ammonium nitrate solution enters the nitro-compound fertilizer preparation unit to be prepared into nitro-compound fertilizer.

Description

technical field [0001] The invention relates to the fields of comprehensive utilization of melamine tail gas and production of nitro compound fertilizers, in particular to a system and method for producing ammonium nitrate and nitro compound fertilizers. Background technique [0002] At present, domestic urea production capacity has been severely oversupplied, and melamine has become the choice for the development of urea downstream products, but melamine tail gas treatment has become the primary issue for the development of melamine plants. The return of melamine tail gas to the urea production system increases the load of the urea medium and low pressure system, the economic benefits of producing ammonium bicarbonate are not good, and the production of soda ash and ammonium chloride requires high supporting conditions. [0003] There are advanced and mature production technologies for nitro compound fertilizers at home and abroad. The foreign technology is basically to se...

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Problems solved by technology

[0002] At present, domestic urea production capacity has been severely oversupplied, and melamine has become the choice for the development of urea downstream products, but melamine tail gas treatment has become the primary issue for the development of melamine plants

The return of melamine tail gas to the urea production system increases the load of the urea medium and low pressure system, the economic benefit of the production of ammonium bicarbonate is not good, and the production of soda ash and ammonium chloride requires high supporting conditions

The foreign technology is basically to send the phosphate fertilizer or potash fertilizer to the ammonium nitrate phosphorus molten liquid tank on the top of the granulation tower with the air conveying equipment, after stirring and melting, enter the granulation tower for granulation, and form granular compound fertilizer products, but the foreign technology The cost of introduction is relatively high

The production process of the partial slurry method in China is simple, but it occupies a large area, the process is long, there are many rotating equipment, the power consumption is large, the ammonia escape rate is high, and the operating environment is poor; Between 35% and 60%, it is not suitable to produce high-nitrogen compound fertilizers, generally (N) is not more than 18%, the process has a high return rate, and the return rate is about 2.5 times that of the product; high tower granulation process It has been widely used in the production of ammonium nitrate, ammonium nitrate, and phosphate nitrate fertilizers, and it has just begun to be involved in the production of nitro compound fertilizers.

[0004] Usually, melamine tail gas is used for urea production. When melamine tail gas is used to produce urea, it is easy to cause the pressure instability of the urea production process, thus affecting the production of urea.

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