Methanol unloading
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During the unloading process of methanol tank trucks, can the vent valve on the roof meet the requirements during unloading, and is it necessary to open the manhole lid? What is the maximum unloading flow rate for methanol? What are the requirements? The unloading manufacturer doesn’t have any oil and gas recovery systems, nor are there any gas connection lines to storage tanks; moreover, they won’t allow access to the manholes. I don’t know what to do. Will a vent valve be sufficient? I’m too hesitant to try it. Please give me some advice Thanks.
Before oil and gas recovery systems were available, when unloading liquids, we would open the upper manhole and cover it with a fireproof blanket to prevent the evaporation of oil and gas during the unloading process. Later, oil and gas recovery facilities were added, connecting directly to the gas phase in the vehicle; the pressure inside and outside the balance tank of the oil and gas recovery system was used to facilitate unloading.
For LPG, to prevent static electricity, the flow rate should not exceed 3 m/s. If the tank truck is equipped with a valve on top, open it; do not open the manhole. Generally, at the top, in addition to the manhole, there are DN65 or 80 valves used for venting or pressure balancing.
Is oil and gas recovery still required for methanol unloading? Shouldn’t external air enter the tank truck during unloading?