Continuous preparation method and device of sulfamic acid

Abstract

The invention discloses a green continuous preparation method and device for sulfamic acid, and the preparation method comprises the following steps: dissolving urea in concentrated sulfuric acid, andsimultaneously loading the urea and sulfur trioxide gas with the temperature of 35-45 DEG C and the volume fraction of 2-15% into an upper falling film reactor and a lower falling film reactor with different inner diameters through a gas-liquid distributor; after the falling film reaction is finished, performing gas-liquid separation, gas is emptied after passing through a demister, slurry obtained after gas-liquid separation enters a solid-liquid separator, concentrated sulfuric acid containing a small amount of urea obtained through solid-liquid separation goes to a raw material cycle, andan obtained solid product sulfamic acid goes to a packaging line. Continuous production is realized, fuming sulfuric acid and liquid sulfur trioxide which are extremely easy to solidify are not required to be transported, stored and metered, manual operation entering an operation area is reduced, and the safety performance is greatly improved; the reaction process is close to zero emission, the atom economy is extremely high, and the method has very important application value and practical significance.

Description

technical field [0001] The invention relates to a green continuous preparation method and device for sulfamic acid, belonging to the technical field of sulfamic acid synthesis. Background technique [0002] Sulfamic acid, also known as sulfamic acid, sulfamic acid, CAS registration number is 5329-14-6; as a very important fine chemical, it is widely used in metal cleaning, food, printing and dyeing, electroplating, papermaking and other fields. [0003] At present, the synthesis process routes of sulfamic acid at home and abroad mainly include: 1) solid-liquid phase reaction of urea and oleum; 2) urea dissolved in organic solvent, adding fuming sulfuric acid for liquid-liquid reaction; 3) sulfur trioxide and oleum Ammonia gas is reacted with gas to produce intermediates, and then hydrolyzed with water. Chinese patent CN 101391759A discloses a solid-liquid reaction between 23% oleum and urea, and then adding a large amount of dilute sulfuric acid to separate sulfamic acid. T...

AI Technical Summary

Problems solved by technology

Chinese patent CN 101391759A discloses a solid-liquid reaction between 23% oleum and urea, and then adding a large amount of dilute sulfuric acid to separate sulfamic acid. This invention will produce a large amount of dilute sulfuric acid, which will cause great pressure on environmental protection , while the process is a batch reaction, the quality of each batch is not the same

Chinese patent CN105524006A discloses a process for the gas phase reaction of sulfur trioxide and ammonia to synthesize sulfamic acid. This invention will produce a large amount of ammonium sulfate by-products. At the same time, the requirements for the water content in the reaction system are extremely strict, and the equipment is severely corroded.

Chinese patent CN1597500A discloses a small amount of fuming sulfuric acid and urea to perform solid-liquid reaction first, and then supplement liquid sulfur trioxide for further reaction. Although this process slows down the intensity of the reaction to a certain extent, liquid sulfur trioxide has Extremely strong oxidizing properties, the mass transfer effect in the reactor is poor, a large number of carbides will be generated locally and the temperature will rise sharply, triggering the second step reaction, a large amount of carbon dioxide escapes in the system, causing the boiler to leak, which is extremely dangerous

In addition, the fuming sulfuric acid and sulfur trioxide used in the production are extremely unstable and highly corrosive dangerous chemicals. They are usually solid in cold conditions, difficult to store, and high in transportation costs.

Therefore, regardless of economic cost or environmental protection pressure, the use of current fuming sulfuric acid and liquid sulfur trioxide can no longer meet the requirements of large-scale production.

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