Is the outlet of the storage tank’s breather valve connected to an environmental protection gas collection hood or directly via a flange?
Thread Content
The breather valve of atmospheric pressure storage tanks has functions of venting, drawing in air, and fire suppression； So the question is, how is the normal exhaust gas from the storage tank connected to environmental protection facilities (such as flaring systems or catalytic combustion systems)? (1) For exporting flanged breather valves for direct connection of pipes to environmental protection facilities ； Here’s the question: if the storage tank absorbs air, it might experience restrictions, and the air drawn in could be high-temperature gas from a flare or catalytic combustion system? It’s not allowed for safety reasons. (2) The breather valve vents directly to the atmosphere; an inverted conical environmental protection air intake cover is then installed at the outlet of the breather valve ； So the question is: the exhaust fans used in environmental protection facilities need to remain on continuously, that is, they keep collecting exhaust gases regardless of whether there is any gas being expelled by the vent valves; is it air that fills those fans most of the time? In real-world scenarios, which form do companies generally use for collection? I would be grateful if anyone who knows something about this could offer some guidance.
The answer can be found in the document titled \"Implementation Plan for the Oil-Gas Connection Process and Guidelines on Safety Measures for VOCs Control Projects in Petrochemical Storage and Transportation Tank Areas.\" Those with similar issues can search on the forum, where this document is available for download. :)
Unreif opinion: According to the measures outlined in the \"Guidelines for the Implementation of Oil and Gas Connection Processes and Safety Measures for VOCs Control Projects in Petrochemical Storage and Transportation Areas\", the collected exhaust gases still constitute high-concentration waste gases at a larger flow rate, which in turn increases the difficulty of further treatment； At the same time, high requirements are placed on instruments and vent valves; the exhaust hood + flame arrester approach is simpler and more reliable, and it’s sufficient to simply extract air regularly
If there is a mixed hazard, it should be evaluated.
Environmental protection gas collection hoods generally use a suspended connection method; this takes into account the natural escape of gas from the storage tank, rather than active absorption. It also needs to account for the supply of air to the absorption system. Finally, direct flange connections may cause the storage tank to collapse, leading to accidents
The breather valve is selected to have functions of exhaust, flame arrestment, and check valve operation, allowing only exhaust and no intake. The storage tank is purged with an inert gas, such as nitrogen. Normal use should involve continuous nitrogen supply and continuous exhaust.