Storage terminal vapor emission control system

A combination bulk liquid chemical tank storage complex and vapour emission control system comprising:

• a plurality of vapour collection ducts;
• at least one tank connected to one of said vapour collection ducts;
• a flow diverter in said one of said vapour ducts to allow air to enter the duct but prevent vapour reflux;
• a header duct communicating with said collection ducts to receive vapour therefrom;
• fan means communicating with each collection duct to draw vapour into the collection duct from a vapour source, for delivery into said header duct;
• an air plenum connected to said header duct to receive the vapour therefrom, said plenum including heating and cooling coils to heat and cool the vapour passing through said plenum, said plenum having a plenum outlet duct;
• low explosion level monitoring means to sense vapour concentration at several locations within the complex;
• air delivery means to deliver air into said complex to selectively lower the vapour concentration within the complex in response to said low explosion level monitoring means detecting a high vapour concentration;
• a vapour emission control system to receive vapour from said complex, said system including collection duct means to collect vapour from said plenum outlet duct, and an activated carbon adsorption plant communicating with said duct means to receive the vapours therefrom, said plant including:
• a pair of adsorber vessels each having an inlet and an outlet and an activated carbon bed positioned between the inlet and outlet so that vapours passing through each adsorber vessel pass through the activated carbon bed thereof;
• a common delivery duct to deliver vapours to each adsorber vessel, a first branch duct extending from said common delivery duct to a first one of said vessels, a second branch duct extending from said common delivery duct to the other vessel, a first valve means to selectively close said first and second branch ducts;
• an outlet duct means extending from said vessels, a first outlet branch duct extending from the outlet of said one vessel to said outlet duct means, a second outlet branch duct extending from the outlet of said other vessel to said outlet duct means, second valve means to selectively close each of said outlet branch ducts;
• desorption piping to deliver to each vessel steam to be passed through each carbon bed to regenerate the carbon bed and convey released vapours and steam from the vessels;
• wherein said complex further includes:
• a first transfer duct means connecting the outlet of the first said vessel to the inlet of the second said vessel, a second transfer duct means connecting the outlet of the second said vessel to the inlet of the first said vessel, a third valve means to selectively close said first and second transfer duct means;
• and wherein said first and second valve means are operable to connect said vessels in series or parallel.