Control of hydrolysis efficiency

Possible reasons: 1. The urea content in the desorption raw material is too high; you can determine this through analysis, with a typical level being 3-5%. 2. Insufficient consumption of medium-pressure steam, resulting in no hydrolysis of urea.

The urea content in the ammonium carbonate solution fed into the hydrolytic desorption unit is generally around 1%; if it is 3–5%, then it is too high, indicating a problem with the system, and the cause should be identified promptly.

Your hydrolysis tower is a horizontal type, so it must be using Snam’s advanced hydrolysis process. A sudden increase in the Ur content in the wastewater can be attributed to two main reasons: First, process-related factors – an significant increase in the Ur content of the feed material, accompanied by a rapid rise in hydrolysis pressure and a sharp drop in temperature. We need to find the cause at its source. 2 Insufficient steam: poor quality ； Sudden drop in traffic ； Valve failures, etc. 3 Low hydrolysis pressure: false indication ； Accidental operations, etc. II. Equipment-related reasons: If the process parameters are normal, it is almost certain that there is a problem with the equipment. 1. Leakage in the hydrolysis feed heat exchanger. 2 The baffles in the hydrolysis tower are damaged, causing the waste liquid to take a shortcut within the tower and resulting in an insufficient residence time. 3 Leaks in the partition between the upper and lower sections of the desorption tower cause not only an increase in Ur, but also a sharp rise in NH3 in the waste liquid. 4 The plate heat exchanger for desorption and hydrolysis feed leaks, but the NH3 level also rises sharply. III. Handling: 1 If it is due to process-related reasons, follow the guidelines and search step by step. 2. If all the process parameters are normal, sample in segments and analyze Ur step by step to identify the cause. The above are just my personal opinions; I hope they can be useful to you, and I also hope that other experts will add their comments.

It could also be a problem with the desorption tower; for example, a high ammonia content in the output from the first desorption tower can also cause abnormal operation of the hydrolyzer, affecting the hydrolysis of urea.

A sudden increase in urea content is likely due to a problem with the hydrolyzer; if the ammonia level rises suddenly, it’s probably an issue with the desorption process. Problems with hydrolysis: 1. Equipment issues – the baffle is damaged, causing the waste liquid to take a shortcut within the tower; as a result, there isn’t enough time for urea to decompose, and the reaction is incomplete ； 2. Process issues: the conditions for the urea hydrolysis reaction are not met, as indicated by insufficient temperature or pressure; this should be checked by examining the amount of steam used and the pressure control valves. This post was last edited by Boating on the Five Lakes on 2009-3-10 21:37.]

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First, the first desorption tower performs poorly; the high NH3 concentration at the inlet of the hydrolysis tower inhibits the progress of the hydrolysis reaction. Second, it is necessary to ensure that the temperature in the hydrolysis tower is sufficient – superheated steam is preferred. Third, please calculate the residence time

If the ammonia content in the carbon-ammonia mixture increases, it causes abnormal operation of the first desorption tower (fluidization), resulting in a high ammonia level in the output from this tower and affecting the hydrolysis efficiency. Currently, the trays in desorption towers are generally sieve trays or floating valves. The characteristic of sieve plates is their limited operational flexibility; therefore, when the ammonia content increases, that is, when the volume of gas rises, flooding easily occurs.