Regarding the methanol discharge from the methanol washing system, the replacement plan
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It is necessary to inspect all the towers that are used for methanol washing, and to grind inside them. Has anyone experienced this before? Is it required to wash them with water during the replacement process, or can nitrogen be used instead? Thank you all for your advice
For the inspection of all towers that are washed with methanol, grinding is carried out inside them, which constitutes an activity involving open flames. It is definitely not sufficient to simply displace the air with nitrogen; it is necessary to first displace the air with nitrogen and then rinse the area with water in order to completely remove the methanol from inside. Grinding operations can only be carried out after a combustible gas fire analysis shows satisfactory results. Of course, if time permits, drying with nitrogen after rinsing with water can prevent corrosion, which is even better.
Thank you for the guidance. That’s right; we plan to maintain a nitrogen environment while carrying out the grinding work, and the workers will wear long-tube respirators. Also, I would like to ask why you said that nitrogen should be used for purging first and then followed by rinsing with water? Thank you very much
This post was last edited by 654262293 on 2016-3-23 at 16:57. First, nitrogen is used to displace the gas inside; then water is used for washing in order to remove methanol, preventing it from evaporating and causing explosions during grinding.
Have the moderators experienced something similar? Could we ask the testing agency to use sandpaper for grinding? That way, the risk would be much lower. This inspection involves checking all the towers that use methanol for cleaning; there’s no place where the methanol can be discharged
Is it a pressure vessel inspection? We’re worried about this too. The device has been in use for just over 2 years, and there is no experience with it. Personally, I think it’s enough to open the manhole and take a quick look to see if everything such as the trays is in order. If one really has to go in to polish and measure the thickness, it’s hard to know to what extent replacement and rinsing should be carried out.
It is not very safe to work in a nitrogen environment inside the tower; it is safer to wash the tower water and then grind it.
Yes, that’s it. It seems that measuring the wall thickness at the moment isn’t very practical, but it’s required to be done this way. When will you carry out the regular inspection over there? I need to do it during the next major repair here
For treatment in the methanol tower, the process starts with discharging the material, followed by 2 to 3 washes with water. After that, steam is used for purging, the system is isolated, and it is cooled either naturally or with industrial air. Testing is then conducted; once the flammability levels and oxygen content are within acceptable limits, work can proceed. Personnel inside must carry portable detectors, and an ongoing supply of industrial air must be ensured. It is a bit troublesome, but safety must be ensured
Well, there are two difficulties at the moment: one is not knowing how much liquid is retained on the tray and how much is stored in the pipes, which relates to whether the methanol that exits can be accommodated there； Second, where is the water stored after it has been rinsed?