Analysis of reasons for temperature spikes
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A friend asked: During the heating and reduction process in the methanol tower, the pressure was 1.5 MP and the temperature was 30°C; the power was not turned on, nor was the circulation pump activated. The operator failed to monitor the temperature. From 8 p.m. to 5 a.m. the next day, the temperature rose to 150°C, after which the pressure was reduced; the highest temperature at the hot spots reached 300°C. What caused it?
Insufficient conditions; it’s difficult to determine. Is steam leaking along with hydrogen? During pressure release, the hydrogen that leaks in at the front comes into extensive contact with the catalyst, resulting in a higher reaction temperature. Is there oxidation? Is it a pre-reduced catalyst? If so, then it hasn’t been fully displaced.
Have you ever been involved in the production of urea alcohol? In medium-pressure and high-pressure urea alcohol plants, companies use synthetic ammonia feed gas (70% hydrogen, commonly referred to as high-hydrogen) for pressure testing, and it is very easy for the temperature to rise excessively.
To avoid overheating, low-hydrogen reduction is required when heating and reducing the catalyst.
"\"Pressure 1.5MP\" should be \"Pressure 1.5MPa\".
You haven’t completely removed the catalyst from the internal components, and air has been allowed to enter; as a result, the temperature of the old catalyst rises. When a new catalyst is installed, its temperature also goes up. If there is still hydrogen present inside, a reaction will occur, which naturally leads to an increase in temperature.
At 1.5 MPa with 70% hydrogen-containing gas, that’s when a reaction starts! !
This is something that often happens in plants that produce methanol as a by-product of ammonia synthesis. The catalyst unloading is not completed smoothly, and after loading, the absence of an air separation unit to provide pure nitrogen for purging the system results in a high oxygen content within it. If hydrogen or process gas leaks into the system, this can lead to excessive temperature rise. Moreover, in the production of glycol, shift process gas is generally used for reduction, rather than pure H