Safety issues regarding methanol crude alcohol storage tanks
Thread Content
My branch company’s methanol plant has two large storage tanks: a crude alcohol storage tank and a refined alcohol storage tank. Due to their different physical properties, the former is protected using low-pressure nitrogen, and it is equipped with a vent valve at the top. (Note: Both of these storage tanks were converted from original heavy oil tanks; they are atmospheric pressure tanks and cannot withstand any pressure.) ) However, during the major maintenance period, the nitrogen compressor is shut down, and only the nitrogen storage tank can supply low-pressure nitrogen; see the attached diagram for details. Calculations show that it is not feasible to add another nitrogen storage tank or build a water reservoir due to cost considerations. Therefore, I’m starting a thread here to ask the experts: how does your factory protect the methanol crude alcohol storage tanks in the absence of low-pressure nitrogen? PS: Since the images I created are small, they might not be clear to everyone. If I send attachments, downloading them would cost money; therefore, the images are posted in layered form. Not clear enough? Just right-click and select “Save As”; there is no cost involved. This post was last edited by Nine Heavens is me on 2009-2-18 15:13.]
With nitrogen protection in place, why can’t the owner turn on the nitrogen generation unit? Additionally, proper measures against static electricity, lightning, and fire must be implemented. If possible, the liquid level in the storage tank can be lowered (by increasing sales). We have been running the nitrogen generation unit.
The liquid level in the crude alcohol tank can be reduced to its lowest level, and then it can be stopped – no special protection is required!
Our branch currently has 3 air separation units: two with a capacity of 6,000 and one with a capacity of 18,000. During major maintenance, everything has to be shut down for repairs. The main focus of the maintenance is on the air compressor units; if the air separation unit stops operating, no nitrogen will be produced, and thus there will be no nitrogen available. This is therefore a challenging aspect.
Generally, no special protection is required for the methanol storage tank during routine maintenance, unless there are any maintenance tasks related to the pipelines connected to it! In the absence of nitrogen protection, be careful not to start the pump in order to prevent methanol in the tank from being pumped out, thus avoiding deformation of the storage tank due to negative pressure! Also, check the lightning protection facilities to ensure they are in good condition ； If it is a hot season, activate the spraying system to cool the tank.
I think the air compressor units can be maintained in rotation. It’s not necessary to stop all at once. Don’t we usually have spares?