Online cleaning method for tubular reactors

Abstract

The invention discloses an online cleaning method for tubular reactors. The method comprises the following operating steps of: releasing the interlocking between liquid ammonia and phosphoric acid of tubular reactors A and B; stopping feeding of the tubular reactors A and B, switching off phosphoric acid and liquid ammonia pipeline control valves, respectively switching on medium-pressure steam valves on acid pipes and ammonia pipes of the tubular reactors A and B so as to continuously purge the steam towards the interior of a rotor drum granulator, mixing phosphoric acid and steam together and carrying out acid pickling and purging on mixing heads A and B, and the tubular reactors A and B 5 for 8-15 minutes, observing the state of materials at an outlet of the granulator in real time through video monitoring, and keeping the tubular reactors A and B to run stably, wherein the purging frequency of the tubular reactors A and B is one time per three to five hours. The cleaning process is simple to operate, and the dirt on the tubular reactors can be effectively removed.

Description

technical field [0001] The invention relates to an online cleaning method for a tubular reactor of an ammonium phosphate device. technical background [0002] The tubular reactor is a continuous operation plug flow reactor with a tubular shape and a relatively large length and diameter. It is the main reaction device in chemical production. Because of its simple process and remarkable energy saving, the tubular reactor, as an efficient production process, has been widely used in the field of chemical production, and is playing an increasingly important role in the production of phosphate compound fertilizers, such as monoammonium phosphate, Diammonium phosphate production equipment usually adopts the drum ammoniation granulation production method. The tubular reactor is generally installed in the drum granulator, which can make full use of the rapid reaction characteristics of phosphoric acid and liquid ammonia. The reaction is violently exothermic and the production is high...

AI Technical Summary

Problems solved by technology

[0004] Among the raw material fertilizer-grade concentrated phosphoric acid, especially with the shortage of phosphate rock resources, most phosphorus chemical enterprises develop and utilize low-grade phosphate rock, and use wet-process phosphoric acid to produce ammonium phosphate. Phosphoric acid contains a large amount of impurity ions, such as F - , SO 4 2- , Fe 3+ , Mg 2+ 、Al 3+ , Ca 2+ etc. These ions are easy to scale on the pipeline and filter related parts during the transportation process. With the accumulation of scale in the pipeline, the pipeline transportation space tends to decrease, and even block the pipeline, which affects the continuous operation of the pipeline reactor.

[0005] In addition, during the reaction process with phosphoric acid and liquid ammonia, the impurity ions in phosphoric acid react quickly to form a variety of insoluble or water-insoluble complexes, such as: MgNH 4 PO 4 、FePO 4 , AlNH 4 HPO 4 F, Ca10(PO 4 ) 6 (OH) 2 , (Fe,Al)MgNH 4 (HP0) 2 f 2 etc., the pipe wall, blind plate and nozzle of the slurry distribution pipe of the tubular reactor will gradually stick and accumulate and grow and expand, which will easily cause the mixing head, slurry distribution pipe and nozzle of the tubular reactor to be blocked, while the tubular reactor When the slurry pressure is between 0.2 and 0.4Mpa, there will be no partial flashing of the slurry, and the operating state is the most stable. However, with the intensification of fouling and blockage of the tubular reactor, the operating pressure of the tubular reactor rises sharply, and the phosphoric acid The transportation and feeding of liquid ammonia fluctuate, the reaction becomes more uneven, the amount of spraying slurry continues to decline, and even the feeding pressure cannot be higher than the pressure provided by the pipe reverse pump, resulting in delivery of spraying slurry, and even damage to the pump and its motor

Only stop for cleaning, which seriously interferes with the stable production continuity of the chemical industry

In addition, the slurry pipe of the tubular reactor is installed in the granulator, and the working space is narrow, which is extremely inconvenient for its cleaning and maintenance. During the cleaning process, not only enters the granulator, but the operating space is narrow and the working environment is harsh

[0006] In the prior art, there is currently no method for on-line cleaning of the tubular reactor for the ammonium phosphate production unit

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