NO20161987A1 - Horizontal wireline compensator - Google Patents

Abstract

A horizontal wirelinecompensator (100)for reduction of dynamic loads and motion in offshore lifting operations comprising: an actuator (10), comprising of minimum two horizontally mounted actuator cylinders (11), consisting of an actuator rod (13) Connected to an actuator piston( 12) and extending o utwardly therefrom throughone end of the actuator cylinder (11), adapted for reciprocation with respect thereto, actuator sheaves (14) mounted at the end of the actuator rods (13) adaptedforapplying force to rope means (19), suchas wire rope, fibre rope, chain, belt or similar, where the rope means (19) is connected to a payload (101) via Connection means (17), such as a padeye, and minimum one secondary sheave (15), where the actuator sheave (14) mounting direction may be horizontal orvertical, and the number of ropemeans (19) is minimum one with no upper limit, framework (16) fixing the actuator cylinders (11) position in relation to each other, the framework (16) also supports all other components, such as secondary sheaves (15), tanks (T1, T2,..., TN), etc., further the framework (16) may be used as anchoring points for connection means(17), like padeyes, to Connect the horizontal wireline compensator (100) to a crane, or similar machine, a first actuator volume(V+), located between the actuator piston (12) and piston side of the actuator cylinder (11), filled with oil for compression ba sed designs and filled with gas (at any pressure, including vacuum) on tension ba sed designs, a second actuator volume (V-), located between the actuator piston (12) and rod side of the actuator cylinder (11), filled with oil on tension based designs and filled with gas (at a ny pressure, including vacuum) on compression based designs, a position measurement means (22), suchas a laser position sensor, a linear position sensor or an ultrasonic position sensor, to register the position of the actuator piston (12), at least one double acting gas accumulator (30), comprising of a first cylinder (31), a ring shaped piston (32) mounted concentrically within the first cylinder (31) and adaptedfor reciprocation with respect thereto, where the lower end of the ring shaped piston (32) is on the same side as the lower end of the first cylinder (31) when the ring shaped piston (32) is at zero stroke, a first inner cylinder (33) mounted concentrically with and fixed to the upper end of the ring shaped piston (32), a second inner cylinder (34) mounted concentrically within the first cylinder (31) and fixed to the lower end of the first cylinder (31) with a leak tight connection against the lower end of the first cylinder (31) as well as a leaktight seal against the ring shaped piston (32), an inner piston (38 mounted concentrically within the first inner cylinder (34) with a leaktight seal against the first inner cylinder (34) where the lower end of the inner piston (38) is at the same level asthe lower end of the ring piston (38),a third inner cylinder (35) mounted concentrically within the first cylinder (31) and fixed to the upper end of the inner piston (38) and to a cylinder connector (36) thatjoinsthe third inner cylinder(35) with the first inner cylinder (33) in a stiff connection, a stuffing box (37) is mounted on top of the second inner cylinder (34) to form a leak tight connection with the first innercylinder (33), Cont. onpage2