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Bosch Rexroth Actuators

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  RE 08122, Edition: 2013-02, Bosch Rexroth AG   Hydraulic Actuator For Control and Switch Functions in Gas and Steam Turbines Contents Introduction 2System Structure 2Features 2Function Types 2Advantages 2Applications 2Application Example 2Schematic 3Function 3Cylinder Kid 4 RE 08122 Edition: 2013-02 Technical Information  2/4 Technical Information | Hydraulic Actuator for Control and Switch Functions in Gas and Steam Turbines Bosch Rexroth AG , RE 08122, Edition: 2013-02 Secure, proven and recognized – Hydraulic Actuators for Gas and Steam TurbinesIntroduction Gas and steam turbines utilize valves with control and safety devices integrated into the actuator portion. These control actuators are designed to meet stringent specifications and to ensure all technical processes.In contrast to the gas turbine, all thermal power of a steam turbine is regulated by safety and control devices, whereas the inlet fuel supply is controlled in a gas turbine only.In general, the nominal diameters of the steam valves as well as the vapor pressures and temperatures have larger values compared to the gas turbine. The result of the higher values is higher power consumption during the operation of the valves, which in turn requires greater dimensioning of the armatures.The actuators are available in a power range from 25 to 1600 MW for steam turbines and 25 to 340 MW for gas turbines in various designs, including explosion-proof specified versions, depending on customer requirements. The actuators meet the requirements of IEC 61508/61511 “Functional safety” and are used in SIL 3 structures. System Structure The entire power cylinder design is modular and customiz-able. Depending on requirements, specific actuators can be created using a selection of hydraulic cylinders, spring assemblies, hydraulic valves and position measurement devices. The assembly can be based on customer specifi-cations to create the desired cylinder drives.All necessary control functions are accommodated in the cylinder housing which is designed as an integral control block. The starting point of the assembly is a standard, double rod cylinder. On the basis of equal area displace-ment in the two cylinder chambers, the hydraulic oil can flow, during trip function, directly to the other side of the cylinder. Normal trip times are set between 120 and 300 ms. The base tube-connecting lines of the cylinder are designed for normal control operation, and thus results in very low flow rates.A control block and spring housing with an integrated spring package form a unit. The safety of the drive actua-tor is mechanically achieved by the spring assembly, being biased in the normal operating state of the hydraulic valve and, depending on the application, the valve opens or closes.All hydraulic valves used, with the exception of a propor-tional control valve, are based on seat valve technology. On one hand, the switching certainty ensures a high level; on the other hand, the leakage of the overall system is drastically reduced. Features   ▶ Electro-hydraulic connection interface  ▶ Rod positioning using electro-hydraulic position con-trol  ▶ Built-in fast closing by means of spring-assisted clos-ing function ▶ Limiting of the maximum closing speed during fast closing  ▶ Integrated end position damping of the piston rod  ▶ SIL3-capable version Function Types   ▶ Safety valve with internal or external triggering of fast switching  ▶ Safety valve with internal or external triggering of fast switching and override control Advantages   ▶ Longtime established system  ▶ Customizable  ▶ Use of proven components  ▶ Seat valve technology Applications   ▶ Valve-actuating devices in gas and steam turbines  ▶ Damper actuators with fail-safe position  ▶ Valves with quick close and quick open function Application Example The steam supply to a turbine must be controlled and stopped in case of an emergency. This function utilizes a hydraulic cylinder actuator, mounted on a valve armature.    PT   PT  Hydraulic Actuator for Control and Switch Functions in Gas and Steam Turbines   | Technical Information  3/4 RE 08122, Edition: 2013-02, Bosch Rexroth AG   Schematic Actuator in Control Position Function The schematic representation above refers to a valve actuator working in position control, i.e. at the connec-tion P is the operating pressure. The logic pilot valves are energized, causing the logics to lock.The cylinder is mated with a proportional directional valve, position sensor(s) and an electronic control unit (not shown). These components are used in a position control loop which is held in accordance with a set value in a certain open position so that liquid, gas or vapor can travel through a throttled orifice.In case of an emergency shutdown or “tripped state” (as shown in the bottom schematic illustration), the process valve is closed, preventing the fluid from flowing through the opening. This occurs when the magnetic power of the pilot valves is switched off, opening both logic valves, the piston rod then moves, being spring-supported in the saved locking position, and causes the flowing out medium to seal. The displaced oil is transported from one cylinder side to the other without coming in contact with the tank. Actuator in Tripped or Closed Position  Bosch Rexroth AG , RE 08122, Edition: 2013-02 4/4 Technical Information | Hydraulic Actuator for Control and Switch Functions in Gas and Steam Turbines Bosch Rexroth AG HydraulicsZum Eisengießer 197816 Lohr am Main, Germany Phone +49 (0) 93 52 / 18-0 documentation@boschrexroth.de www.boschrexroth.de © This document, as well as the data, specications and other information set forth in it, are the exclusive property of Bosch Rexroth AG. It may not be reproduced or given to third parties without its consent. The data specied above only serve to describe the product. No statements concerning a certain condition or suitability for a certain application can be derived from our information. The information given does not release the user from the obligation of own judgment and verication. It must be remembered that our products are subject to a natural process of wear and aging. Cylinder Kid Measuring SystemsStroke ranges:50 to 350 mmOutputs:4 to 20 mA-10 to +10 VCylinderPiston diameter:110 to 330 mmRod diameter:60 to 125 mmStroke:50 to 350 mmSystem pressure:160 barForces at design pressure 115 bar:77 to 842 kNValvesDirectional valves:NS 6 and NS 10Proportional valves:NS 6 to NS 32Logic valves:NS 16 to NS 63Fast-acting SpringsCase:3 sizesSpring packages:4 groupsRelaxed: 5,5 to 108 kNCompressed: 18 to 450 kN
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