Ensuring Precise Flow Control: Optimized Multiturn-Actuation for Low-Power Applications

Abstract The subsea production and processing industry is driving towards electrification of subsea installations. Therefore, it is essential to minimize electric power consumption to enable increased step out distances and affordable installations. At the same time, accurate and responsive actuation of multiturn control valves often leads to high electric power consumption. This paper shows how all-electric control actuators with optimized energy utilization and efficiency were developed and can be used in installations where only low electric power is available. During the development of a portfolio of all electric actuators (OTC-35116-MS), it became clear that the low power operation of multiturn control valves is a major building block for upcoming industries, such as CCS and offshore green hydrogen production. With a focus on the attractiveness to the market, electro-mechanical actuators were identified, as being considered the most promising technology to perform continuous proportional control. Focusing on high efficiency, a modular electro-mechanical approach was selected and designed, allowing for scalable multiturn solutions, using proven and industrialized actuation modules and following industry standards. Valuable insights were gathered and compiled during the validation. The paper shows the results of the engineering and qualification of a low-power electro-mechanical multiturn actuator for operation of ROV Class 4 interfaces with torques up to 2,700Nm. Intensive effort was put into the electrical and mechanical challenges, such as the mechanical energy stored inside a high-ratio transmission and the challenge of accurate output motion control. Together with an industrial partner, a highly efficient subsea multiturn actuation with a low power mode has been successfully designed and qualified. The solution, consisting of a high accuracy mechanical transmission unit and servo electric controls shows high efficiency, even when providing full output torque of 2,700Nm at an electric power consumption of 96W. This enables low-power applications, such as CCS and green hydrogen production, where proportional control actuators are crucial for accurate flow control in long step-out scenarios. Benefits of integrated digital models were evaluated, resulting in increased monitoring capabilities. Decision making algorithms allow predictive maintenance and increased availability of equipment. As an outlook, such systems can also be used in brownfields, where the initial control system needs permanent override with enhanced condition monitoring. The paper demonstrates the importance of a high-quality interplay of electrical and mechanical modules in novel multiturn control actuators, combining a highly efficient and responsive control with low power consumption. Future subsea installations will have strict requirements on energy consumption, to reduce overall cost and complexity. The findings presented in this paper will help the industry to deploy all-electric control systems more efficiently and will contribute to the success of future low-power subsea installations.