Method of producing urea with high stability

Abstract

The invention provides a method of producing urea with high stability. The method disclosed by the invention specially comprises the following steps of: leading urine of which the mass concentration is 95-96% to a raw material dissolving tank, adding the mixture of a urease inhibitor, a nitrification inhibitor, an ammonia stabilizing agent, a water absorbent and a coloring agent, of which the mass accounts for 10-40% of that of the urine, stirring and dissolving all the materials under the circumstances of constant pressure and the temperature of 120-125 DEG C, wherein the stirring time is 15-30 minutes, preparing melted urine in which additives are dissolved, sending the melted urine into a melted pump, and conveying system urine into a pipeline of a urea prilling tower, so that the melted urine and the system urine are thoroughly mixed; pelleting and cooling mixed finished urine so as to form particulate urea. Through the adoption of the method disclosed by the invention, the residence time of raw materials in a urea production system is shortened, and the decomposition of the inhibitor and the stabilizing agent at a high temperature is reduced; under the circumstance that the additive amount is definite, the product quality is improved, and the production cycle is shortened; corrosion to system equipment is avoided, and the cost is reduced.

Description

Technical field [0001] The invention relates to the field of urea production, in particular to a process method for adding a urease inhibitor, a nitrification inhibitor, an ammonia stabilizer and a coloring agent in a stable urea production process. Background technique [0002] The existing stable urea production methods mostly add urease inhibitors, nitrification inhibitors, ammonia stabilizers and food-grade colorants to the urea production system in batches between the evaporation process or the second stage of evaporation and the melting pump. Since most of these raw materials are organic substances with poor thermal stability, they are easy to decompose or change the structure and properties of the material when the temperature is higher than 100°C, and the decomposition or structural change is accelerated when the temperature is higher than 120°C. [0003] The existing production method is to dissolve urease inhibitors, nitrification inhibitors, ammonia stabilizers and color...

AI Technical Summary

Problems solved by technology

[0003] The existing production method is to dissolve urease inhibitors, nitrification inhibitors, ammonia stabilizers and coloring agents in the urine between the first and second stages and then add them to the system between the first and second stages or after the second stage, so that the additives can be better used. Mixing with urine can also reduce the moisture in the product, but it will cause the additive to stay in the system above 120°C for a long time, which will cause the decomposition of these raw materials, and the quality of the product will decline under the condition of a certain amount of addition.

[0004] In addition, in the existing stable urea production method, in the process of dissolving urease inhibitor, nitrification inhibitor and ammonia stabilizer, some raw materials will decompose and produce air bubbles, and there are also some tiny solid particles that cannot be dissolved. These air bubbles and solid particles add After entering the system, it will cause corrosion to the system, especially when it passes through the urine melting pump, it will cause cavitation and stress corrosion, which will greatly reduce the service life of the equipment and increase the cost

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