Degassing Of An LNG-Powered Freight Vessel

Degassing Of An LNG-Powered Freight Vessel

Portfolio Categories: Case Studies and Marine Vapor Recovery.



A customer tasked Envent to create a temporary system allowing for the degassing of an LNG-powered freight vessel while it was docked at port in order to perform critical maintenance on the vessel. The solution would allow the customer to continue standard operations without delay, remove Natural Gas Vapors from within the fuel tanks, and maintain compliance with Environmental Protection Agency (EPA) clean air standards as well as the US Coast Guard. Envent has USCG certifications to operate on the marine water ways and docks.


Envent supplied the customer with an EMECS 70, the industry leading mobile thermal oxidizer unit. The freighter has two 900 m3 LNG tanks each containing trace amounts of liquid LNG and pressurized vapors. Vapors are vacuumed out of the vessel using state of the art blower units and then routed to the thermal oxidizer at a control pressure and incinerated to greater than 99.9% efficiency at a rate of 60,000 CFH. This process continued until both LNG vessels were completely de-pressured. The vapor control, vessel degassing and purging of the vessels is completed within hours. Mobilization and demobilization of the marine vapor control systems is seamless.


Envent’s solution allowed for the customer to successfully continue operations without having to delay any standard procedures. In addition, the customer was able to start maintenance work on both LNG tanks immediately after this process was completed. Both of these achievements allowed the customer to save a valuable amount of time and money.

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