Help: Scaling on the impeller of the methanol circulation pump
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After the methanol circulation pump’s impeller developed scaling, which caused high vibration and led to an automatic shutdown, the impeller was cleaned and balanced; yet within less than two months of restarting the pump, the vibration level rose again to 68 um. What can be done to address the problem of scaling on the impeller?
This is an inevitable problem with gas compressors; it’s not very effective to try to solve it by modifying the compressor itself. What we usually do is spray water to address the issue of coal ash. To truly resolve the problem, we need to focus on dust removal in the upstream system. This may require a larger investment, but it yields the best results. Otherwise, there can be a shortage of airflow, and even surge conditions may occur, causing further damage to the compressor
Is the water spray effect good? Where should the water be sprayed?
Look at the unit structure: generally, water spray dust removal is installed at the first stage of the unit, and a separation tank is used after the first cooler to separate water from the sediment. It’s not actually known whether it has been used or not; it is said to be used very rarely. After all, there is still a considerable risk
A new catalyst has been installed; I’m not sure if scaling will still occur on the impeller.
The shaft vibration is rising again:(
It might be better to install a filter at the process gas inlet
It is recommended to install a separator at the compressor inlet; a combination of cyclone separation and a wire mesh demister for mechanical separation should yield much better results. Additionally, water washing can be considered to remove scaling substances, but care must be taken to ensure that water does not enter the compressor; a wire mesh demister should be installed downstream
Shenmu’s compressors are equipped with such a water injection device in front of the first-stage impeller, but its actual effectiveness has not been verified; if the ash content in the gas is too high, measures need to be taken in the purification stage
The composition of the bleed gas is similar to that of the circulating gas. Our plant recovers this bleed gas; severe scaling is present at the outlet valve of the reciprocating compressor used for recovery, while the inlet valve is clean and free of scaling, with water present. Inlet bleed air at 30 degrees, outlet at 60 degrees.
The gas entering the compressor passes through a methanol synthesis separator; there is an ultrafiltration unit at the top of the separator, and a filter screen is installed at the compressor inlet. Upon inspection, both the ultrafiltration unit and the filter screen were found to be clean.