hydraulic actuator - for control- and close function of

Hydraulic Actuator — for Control- and Close function of Process Valves

Technical Information

RE 08122, Edition: 2020-12, Bosch Rexroth AG

Content

Introduction 2Product Description 2Product Features - Advantages and Customer Benefit 2Functionality 3Schematic System Overview 4Key Technical Data 5Closing Direction of the Hydraulic Actuators 5Types of Hydraulic Actuators 6Maintenance Services from Bosch Rexroth 7 Further Information and Contact 8

RE 08122Edition: 2020-12Replaces: 2013-02

2/8 Technical Information | Hydraulic Actuator - for Control- and Close function of Process Valves

Bosch Rexroth AG, RE 08122, Edition: 2020-12

In turbines and industrial process applications, Globe Valves are installed to control and safeguard the engineering processes. These valves are operated via linear hydraulic axes. In Steam Turbines, for example, the steam is metered into the turbine and adjusted with the load. In Gas Turbines, on the other hand, the fuel supply is regulated. The nominal dimensions of the valves, the medium pressures and the temperatures vary between these two turbine types. This results in a varying power requirement for actuating the valves,

which in turn results in a different dimensioning of the hydraulic actuators. The hydraulic actuators from Bosch Rexroth AG can be individually configured according to a modular principle and are offered in a power range from 25 to 1600 MW in various designs, including also explo-sion-proof, depending on customer requirements. On request, they meet the requirements of IEC 61508/61511 „Functional safety“ and can be used in SIL 3 structures.

The entire drive design is modular and can be created from a selection of hydraulic cylinders, spring assem-blies, measuring systems and hydraulic valves. Also, the required drives can be built according to custo-mer specifications. All the necessary control functions are housed in the cylinder housing, which is designed in the form of an integrated control block. Due to the displacement behavior of the same surface area in both cylinder chambers of the cylinder, the hydraulic fluid can be routed directly to the opposite side of the hydraulic cylinder during the rapid switching process (actuating time 120 to 300 ms). Because of this, the connection lines of the hydraulic cylinder can be

designed for normal control operation and thus for low volume flows. The reliability of the actuator closing is achieved mechanically by the spring assembly. The actuator is hydraulically preloaded in the normal operating state of the valve and opens or closes the process valve depending on the requirements and design of the actuating unit. With the exception of the servo valve, all hydraulic valves used can be designed using seat valve technology. This ensures the shutdown safety of the system at a high level. At the same time, the leakage oil volume of the overall system is drasti-cally reduced.

Product Features - Advantages and Customer Benefit

Prdoduct Description

Introduction

• Electro-hydraulic connection interface

• Piston rod positioning by means of electrohydraulic position control

• Superimposed quick closing through spring-related closing

• Integrated end position cushi-oning of the piston rod

• SIL-3-capable version• ATEX-compatible design

Product Features

• Maximum availability and service life

• Economic engineering based on a modular design

• Customer and application-specific system solutions

• Worldwide service options from Bosch Rexroth

• Proven operation — Established and long-term proven system

• Modular structure for individual solutions

• Bosch Rexroth core compo-nents in the system network

• Rexroth-certified service centers

Advantages Customer Benefit

Hydraulic Actuator - for Control- and Close function of Process Valves | Technical Information 3/8


Functionality

In order to simplify the explanation of the system, only the essential components are shown.

Actuator in Closed Position

Actuator in Control Position

The Actuator shown here is currently in the control position. This means that operating pressure is applied to port P and the solenoid of the logic pilot valve (1) is energized. The logic valve (2) is thus piloted closed. The hydraulic cylinder forms a position control loop with the servo directional valve (3), the position measuring system (4) and the electronic assembly (not shown) and is held in a defined opening position in accordance with a specified load setpoint. The volumetric flow is then regulated in a throttled manner.

If necessary it is intended, as shown schematically in this figure, to prevent the medium from escaping from the opening. The solenoid of the logic pilot valve (1) is no longer energized, there-fore the logic valve (2) opens and the piston rod moves to the safe position with the aid of spring force. This closes the opening of the outflowing medium. The hydraulic fluid is conveyed here from one side of the hydraulic cylinder to the other without coming into contact with the tank.

1

2

3

4

1

2

4

3



Schematic System Overview

Ste

am P

roce

ss T

reat

men

t

Condensor

1.1

1.2

2.1

2.2

3

4

1

2

3

4

Main Steam Control Valve Combination

Intercept Valve Combination

Bypass Valve Combination (High Pressure)

Bypass Valve Combination (Medium Pressure)

Sample configurations are shown below. The delivered version may differ from the illustrations.

Generator

Steam Turbine

Gas Turbine

5

6

6

6 5 Actuator with Fast Closing Function

6 Actuator with Control and Fast Closing Function



Key Technical Data

Hydraulic Cylinders Measuring Unit

• Stroke from 25 to 350 mm (1 in to 13.78 in)

• Typical Fast Closing times 120 to 300 ms

• Nominal Pressure to 165 bar

• End Closing speed ≤ 0,3 m/s

• Multiple installation positions

• SIL 3-capable version option

• Explosion proof-capable version option

• Equipment of the hydraulic actuators with a measuring unit

Forces

• Hydraulic actuating forces to 2090 kN (469,850 lbf)

• Relaxed spring force to 216 kN (48,560 lbf)

• Compressed spring force to 908 kN (204,126 lbf)

Depending on the closing direction of the valve on which the hydraulic actuator is installed, there are two diffe-rent versions of the hydraulic actuator. In one of these versions, the spring ensures that the piston rod of the

Closing Direction of the Hydraulic Actuators

hydraulic actuator retracts (left figure) and the other extracts it (right figure). Hydraulic actuators that retract due to the spring force are referred to as CXE actuators and those that extract as CGE actuators.

CXE CGE



Types of Hydraulic Actuators

CGE1 / CXE1

CGE2

The hydraulic actuator CGE1 / CXE1 is primarily used to regulate the steam supply to turbines. Compared to gas and industrial turbines, the process fluid operating conditions, steam in this case, are higher and the nominal dimensions of the steam valves are larger. Therefore, the CGE1 / CXE1 is designed for higher forces and can thus be used for higher requirements.

The hydraulic actuator CGE2 is designed primarily for use in gas turbines. When compared with the actuators used in steam turbines, lower forces and loads are required here, which means that the hydraulic actuator CGE2 can usually be dimensioned smaller than the hydraulic actuator CGE1 mentioned above. When required for use in a potentially explosive environment, a version of the hydraulic actuator that is certified in accordance with explosion proof protection directives is possible.

On request, the hydraulic actuators can be designed to meet the requirements of IEC 61508/61511 „Functional Safety“ and can then be utilized in SIL 3 installations.



Maintenance Services from Bosch Rexroth

Our services for hydraulic actuators enable safe and almost uninterrupted continuous operation. A regular condition analysis by our field service helps to uncover unusual damage and sources of error and to initiate

Your Advantage — Bosch Rexroth Service

Bosch Rexroth Certification System

direct countermeasures or to plan them in good time. Necessary inspections and maintenance can be carried out during the planned downtime of the system and thus increase the system availability.

In order to offer you a fast and safe service of the highest quality, Bosch Rexroth has multiple locations throughout the world that can assist with your service needs.

• Safety for man and machine by avoiding improper operating conditions

• Maximum availability and service life

• Perform all safety relevant tests according to the original specification

• Execution of functional tests in accordance with OEM specifications

• Painting according to project specification

• Test with the original hydraulic medium according to the project specification

• The Bosch Rexroth Maintenance Plan is designed to maximize the life of the product while helping to avoid premature failures

• Depending on the operating status and installation position, we offer our system expertise for on-site services. I.e. checking the spring assembly, functio-nal check of the servo valve, et al.

Bosch Rexroth service centers are authorized to upgrade and fully overhaul these products to the original OEM Specification.



Bosch Rexroth AGIndustrial HydraulicsZum Eisengießer 197816 Lohr am Main, Germany Telefon +49 (0) 93 52 / 40 30 20 www.boschrexroth.de

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Further Information and Contact

Further information regarding our actuators can be found at www.boschrexroth.com or you can contact us at the following E-Mail: [email protected]

We will send you the requested documents and would be happy to contact you personally.

hydraulic actuator - for control- and close function of

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