Urea melting apparatus

Abstract

The invention relates to a solid urea melting device, aiming at solving the technical problems of low melting efficiency, easy generation of biuret, difficult clearing and maintaining, as well as high operating cost in the existing similar devices. The device comprises a melting tank, a stirring mechanism and a heating coil arranged in the melting tank, wherein, a stirring shaft and stirring paddles of the stirring mechanism are arranged in the melting tank; the device is characterized in that: the bottom surface of the melting tank is a curved surface, and a purging port is arranged at the bottom of the curved surface; an overflow port communicated with a guniting pipe is arranged at the upper part of the side wall of the melting tank; at least two upper and lower layers of stirring paddles are laid out on the stirring shaft; and a guide flow cylinder is arranged at the lower area of the inside of the heating coil, and the lower layer of stirring paddles is matched with and arranged in the guide flow cylinder. The device can be widely applied in the field of compound fertilizer production for the fast melting of solid urea.

Description

Technical field [0001] The invention relates to a compound fertilizer production equipment, in particular to a solid urea melting device. technical background [0002] With the development and production needs of urine slurry urea-based compound fertilizer technology, sulfur-based compound fertilizer spraying nitrogen supplement technology, and large particle urea technology, high-concentration urine (≥99.5%) is used in the above-mentioned various technology Plays an increasingly important role. Except for the urea factory that can directly provide high-concentration urine (≥99.5%), other high-concentration urine is mainly derived from the direct melting of solid granular urea, but due to the particularity of urea itself, solid urea will be hydrolyzed during melting And isomerization condensation, and biuret formation. The compound fertilizer or large granular urea processed from the urine with higher biuret is not good for the growth of crops, especially it will cause serious ...

AI Technical Summary

Problems solved by technology

[0004] 1. The stirring strength of the stirring paddle in the urea melting tank is small, and it is difficult to form an up and down circulation flow. The solid urea is easily suspended on the surface of the urine, and it is not heated uniformly, so it cannot be melted quickly. It can only be melted when water (3-5%) is added.

Since the urea solution has a relatively long residence time (≥20min) or contains 3-5% moisture in the melting tank, the urea in the urea solution will soon be at high temperature (>100°C) and a long residence time (≥20min) Under certain conditions, a large amount of biuret is rapidly formed; at the same time, urea is rapidly hydrolyzed under the action of water [CO(NH 2 ) 2 +H 2 O=CO 2 +2NH 3 ], overflowing a large amount of ammonia, resulting in the loss of nitrogen on the one hand, on the other hand the hydrolysis causes the vapor pressure of ammonia in the urine to drop, leading to the further generation of biuret in the urine; in addition, adding water to the urine will cause the moisture content of the finished product High, the particles are flat and not round

[0005] 2. The stirring intensity of this type of device is low, the fluidity of the urine in the melting tank is poor, the heat of the heating coil cannot fully exchange heat with the urine in the tank, resulting in the enrichment of heat near the coil, the temperature rises, and the urine occurs Condensation reaction produces biuret (according to the measurement, the content of biuret in the urine prepared by the urea melter with the above structure is usually 5-8 times that of the solid urea itself), and a large amount of ammonia Gas overflow produces bubbling phenomenon, which causes nutrient loss, pollutes the environment, and easily leads to bubbling

[0006] 3. The molten urine is poured into the granulator through the submerged pump in the auxiliary tank. The steam insulation pipe cannot be installed at the pump outlet, and the urine is easy to solidify and block here; most of the valves in the urine pipeline are insulation valves. High maintenance costs

[0007] 4. The vertical submerged pump cannot completely drain the urine in the melting tank, and it is difficult to drain the urine and clean the tank, and it is easy to cause waste

[0008] 5. This type of equipment has a large investment and high maintenance and operation costs. If it is necessary to be equipped with a computer metering system to control the flow of urine

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