One-step method used for production of melamine by circulating ammonia gas as carrying gas
A technology of melamine and its production method, which is applied in the direction of organic chemistry, can solve problems such as clogged pipelines and equipment, easy precipitation of ammonium carbamate crystals, etc., and achieve the effects of improving work efficiency, reducing production costs, and reducing power consumption in compression
Inactive Publication Date: 2014-02-26
李东田
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Problems solved by technology
[0005] The following problems exist in the production: First, the carrier gas is a mixture of ammonia and carbon dioxide, and ammonium carbamate crystals are easily precipitated at low temperatures, which can block pipelines and equipment
However, this method also belongs to the reaction tail gas as carrier gas and must be pressurized by a centrifugal compressor to provide gas cycle power, and the separation of tail gas per ton of product consumes more than 6 tons of steam
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[0021] Such as figure 2 As shown, the molten urea is pumped to the urea inlet of the reactor, atomized and entered into the reactor under the action of atomizing gas—ammonia, the heat required for the reaction is provided by the molten salt system, and the fluidized bed carries The ammonia gas is the ammonia gas obtained by purification and separation of the tail gas. The ammonia gas enters the compressor with an inlet temperature of 30°C. The heater is heated by molten salt to 360-410°C and then enters the bottom inlet of the reactor. The reacted gas enters the heat exchange system to cool down. The hot gas filter removes solid impurities in the gas flow. The dust-free gas from the hot gas filter enters the crystallizer from the top, and the reaction gas continues to cool down in the crystallizer until melamine desublimes and precipitates, and the melamine enters the triamine with the reaction gas. In the trap, the melamine product is obtained after being recovered by the c...
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The invention discloses a one-step method used for production of melamine by circulating ammonia gas as a carrying gas. According to the one-step method, traditional melamine production technology is improved; a reaction gas after separation of melamine is subjected to carbon dioxide removal; ammonia gas accounts for 99.8% of the purified gas; the removed carbon dioxide is used for producing a small amount of ammonium bicarbonate, or is not used for production of ammonium bicarbonate; no steam is consumed in the whole process; purified ammonia gas can be used as a circulating carrier gas of a reactor, a atomization gas of molten urea, and a blowback gas of a hot gas filter. The one-step method possesses advantages such as low production cost, and simple and convenient equipment maintenance.
Description
technical field [0001] The invention belongs to the technical field of chemical production, in particular to a production method of melamine. Background technique [0002] At present, there are two main one-step (dry) production processes of melamine: one is the gas phase quenching process, the reaction tail gas is used as a circulating carrier gas, and the exhaust tail gas is used to produce urea, ammonium bicarbonate, ammonium nitrate, combined alkali and other products; The other is to use the reaction tail gas as a circulating carrier gas, and the exhaust tail gas is used to separate ammonia and carbon dioxide. The separated ammonia is sold as a by-product, commonly known as "ammonia and carbon separation". [0003] The gas phase quenching process is as follows: the molten urea is pumped to the urea adding port of the reactor through the urine, atomized under the action of the atomizing gas and enters the reactor, and reacts to form melamine under a certain pressure and ...
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IPC IPC(8): C07D251/60C07D251/62
CPCC07D251/60C07D251/62
Inventor 李东田
Owner 李东田