Fluidic pig launcher and method of its use
A pig launcher/receiver includes a fluid distribution grid arranged above a floor of the pig launcher/receiver's barrel to define a fluid chamber between the floor and the fluid distribution grid. The distribution grid has a plurality of ports arranged to form jets that discharge at least a portion of the fluid which enters the fluid chamber. A predetermined number of the ports are inclined relative to vertical and in a direction opposite a closure door of the barrel. The fluid distribution grid, which is preferably semi-circular shaped, can be a permanent weldment, bolted on, or removable. When used in launching a pig, the ports provide a differential pressure that lifts the pig and overcomes friction as the pig moves forward. Because a number of the ports are blocked by the sealing elements (cup or disc) of the pipeline pig, the number of pigs residing in the launcher/receiver can be determined.
1. A method of launching a pipeline pig, the method comprising:
positioning a pipeline pig in a launch position over a fluid distribution grid located between the pipeline pig and a barrel floor of a first launcher/receiver, the pipeline pig including at least two sealing elements; the fluid distribution grid configured as a perforated matrix containing a plurality of ports arranged to form jets that discharge fluid toward an opposing surface area of said sealing elements resting on and blocking ports of the plurality when in the launch position;
filling a fluid chamber located between the barrel floor and the fluid distribution grid;
lifting the pipeline pig from the fluid distribution rid when in the launch position by discharging through the plurality of ports at least a portion of a fluid which enters the fluid chamber, the fluid acting on the opposing surface area of said sealing elements; and
launching the pipeline pig, when lifted, in a direction opposite that of a closure door of the first launcher/receiver.
2. A method according to claim 1 further comprising calculating a number of blocked ports and area of the fluid distribution grid covering a range of the blocked ports.
3. A method according to claim 2 further comprising:
equating the area to a number of sealing elements in the launcher/receiver; and
inferring from the number of sealing elements the number of pigs remaining in the launcher/receiver.
4. A method according to claim 1 wherein the fluid distribution grid is divided into at least two separate zones, the method further comprising preventing the fluid from entering one of the zones.
5. A method according to claim 4 further comprising allowing fluid to enter the zone where the fluid was prevented from entering.
6. A method according to claim 1 wherein a predetermined number of ports of the plurality of ports are inclined relative to vertical in a direction opposite the closure door.
7. A method according to claim 1 , the pipeline pig including a diagnostic tool.
8. A method according to claim 6 , wherein fluid exiting the inclined ports move the pig in the direction opposite the closure door.
9. A method according to claim 1 , the fluid distribution grid being shaped complementary to an opposing portion of the barrel floor.