Accumulator ensures safety and precision in active heave compensator

For precise load handling in maritime applications, Seaqualize in the Netherlands develops custom-fit solutions. The company is currently working on the Delta600 prototype — an accessory to turn standard heavy lift cranes into Active Heave Compensated (AHC) machines for use on the world’s oceans. This is the world’s first inline AHC tool for in-air lifting of heavy loads, and can compensate all heave motions to up to 97% using minimal, battery supplied power. For the development project, Seaqualize is relying on the expertise of Roth Hydraulics in Biedenkopf. The hydraulic accumulator specialist developed an ocean-going piston accumulator system for Delta600.

Delta600 is a flexible accessory for any type of loading crane used to move heavy loads in wave action in harbors, on ships or offshore and which requires lift compensation. The hydraulic unit, with Roth Hydraulics’ accumulator technology inside, is placed in the crane hook and enables high-precision lifting, moving and lowering of loads weighing up to 600 tons. In the process, Delta600 compensates for swell and wave motions and controls the load throughout the entire lift. For picking up heavy loads from a heaving ship, the tool’s hydraulics allow gradual build up of the load into the crane wire and automatic lowering at a safe moment.

The gentle movement controlled by the hydraulic spring prevents heavy loads from breaking away, bouncing or hitting the ground. The hydraulic unit ensures very slow and precise setting-down speeds, especially for the setting-down process.

The Roth Hydraulics piston accumulator system is around 6 m tall and has an empty weight of around 20 tons. It consists of several piston accumulators, pressure vessels and control blocks that have been specially optimised for the application. Daniel Lauber, the responsible design engineer at Roth Hydraulics, explained, “Particular challenges in the project were the specified installation space and the effect of the dynamic loads on the components of the hydraulic accumulator system. We are pleased to have worked closely with Seaqualize to develop a solution that was very precisely tailored to the Delta600 application.”

Acceptance tests for the accumulator system at Seaqualize have already been completed with great success. Edouard Schinkel, founder and the technical lead at Seaqualize, praised the constructive cooperation, “In Roth Hydraulics, we have found a medium-sized partner that sets high quality standards and has the necessary expertise in implementing special projects. Constant exchange of information within the framework of Delta600 has laid the foundation for a business relationship with Roth Hydraulics based on partnership.”

Delta600 from Seaqualize is the world’s first inline Active Heave Compensator for standard heavy lift cranes, to actively compensate up to ~97% of all heave motions during lifts and installations. | Courtesy of Seaqualize

Roth piston accumulators for machinery and equipment are available in sizes from 0.1 to 1,500 liters. Standard units are available with 350 bar maximum operating pressure and special versions up to 1,200 bar, with variable preload pressure. They are used when high withdrawal volumes and withdrawal rates are required. Depending on the application, significant increases in capacity are possible with downstream gas tanks. Even compact, ready-to-connect large-scale systems with a total volume of well over 100 m3 can be realised — by coupling piston accumulators and downstream gas containers in any number. The storage systems are suitable for temperatures from –10 to 80° C, and are optionally available for extreme temperatures from –60 and up to 200° C.

Roth designs fluid connections and sealing systems of the piston accumulators individually according to customer requirements. Abrupt gas loss to the fluid side is not possible. Friction-minimised sealing systems ensure high efficiency and highly efficient operation. Additional options, such as a built-in stroke limiter or a wide range of measuring and monitoring devices, provide information on the operating status as well as the energy content. The piston accumulators can be installed in any position.

Source: Fluid Power Journal

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