Apparatus and method for venting and depressurization of an odorant injection system

Abstract

The apparatus and method for venting and depressurization of an odorant injection system may be used on special LNG tankers that have onboard gasification equipment, on land or elsewhere. Odorant injection systems may operate at high pressures on an intermittent basis. On some occasions, the odorant is drained from a pressurized system and disposed of in inappropriate ways. The present invention depressurizes an odorant injection system and transfers the unwanted liquid odorant back into an odorant tank where it can be reused when the odorant injection system is restarted.

1 . An odorant depressurization system for depressurizing at least a portion of an odorant injection system in an environmentally friendly manner, the odorant injection system having at least one odorant injection pump, at least one odorant container and at least one odorant injection conduit in fluid communication with the at least one odorant injection pump and at least one natural gas conduit, the odorant depressurization system comprising:
 at least one bypass conduit in fluid communication with the odorant injection conduit and the at least one odorant container;   at least one vapor filter in fluid communication with the at least one odorant container and atmosphere;   a plurality of valves to open the bypass conduit to fluid communication from the odorant injection conduit to the at least one odorant container and to close the bypass injection conduit to fluid communication with other portions of the odorant injection system; and   a plurality of valves to open the at least at least one vapor filter to fluid communication from the at least one odorant container and to open the at least one vapor filter to atmosphere to vent purified vapor from the at least one odorant container.   
   
   
       2 . A system for venting vapors from an odorant injection system to atmosphere, said vapors having a reduced concentration of odorant, the venting system comprising:
 means for transporting odorant from an odorant injection conduit into an odorant container, the transporting means including valving to selectively direct the flow of odorant from the injection conduit into the odorant container; and   means for filtering vapor from the odorant tank to reduce the concentration of odorant in said vapor before it is vented to atmosphere, the filter means including valving to selectively direct the flow of vapors from the odorant container, through the filter means and thereafter into the atmosphere.   
   
   
       3 . A method for venting vapors and depressurization of an odorant injection line comprising the following steps:
 depressurizing the odorant injection line and allowing the odorant in the odorant injection line to flow back into an odorant container; and   venting the odorant container and filtering the vapors that are vented to reduce the concentration of odorant in the vapors before said vapors are vented to atmosphere.   
   
   
       4 . In combination, an odorant injection system with integrated depressurization system for use on an LNG tanker with onboard gasification systems, the odorant injection system with integrated depressurization system including:
 an odorant injection system having;
 at least one odorant storage tank to contain a supply of liquid odorant; 
 at least one odorant injection conduit; 
 at least one odorant injection pump to pump liquid odorant from the at least one odorant storage tank to the at least one odorant injection conduit; and 
 conduits providing a fluid flow path between the at least one odorant storage tank, the at least one odorant injection pump and the at least one odorant injection conduit; 
 an odorant depressurization and venting system having; 
 a bypass line to drain liquid odorant from the at least one odorant injection conduit into the at least one odorant storage tank; 
 a vapor filter to purify vapors from the at least one odorant storage tank, before the vapors are vented to atmosphere; 
   means for controlling the odorant injection system and odorant depressurization system including valves to direct the liquid odorant flow path into the at least one odorant injection conduit when the system is injecting odorant and to direct the liquid odorant from the at least one odorant injection conduit to the at least one odorant storage tank when the system is being depressurized.