概述 Brief Introduction
As a most important part of DEH (Steam Turbine Digital Electro-hydraulic Control System), EH system is composed of oil supply system, actuator and emergency trip system. The oil supply system is a center to store and deal with EH oil and it can actuate servo system by supplying the stable high pressure oil to EH system. Actuator can adjust the opening size of each steam valve by responding to the electro-instruction sent from DEH. Emergency trip system is controlled by the trip parameter of steam turbine. When these parameters exceed the limit value, the trip system will shut off all of the entrance steam valves or only the adjust steam valve in order to ensure the secure running of the steam turbine.
EH供油装置 EH Oil Supply Unit
The main function of the Oil Supply Unit is to offer the hydraulic oil and pressure to actuator and to ensure the physical-chemical characteristics & running characteristics of the pressure oil. Oil Supply Unit consists of oil box, pump, control block, oil filter, magnetism percolator, overflow valve, accumulator, condenser, EH box, some standard equipment which can alarm, display and control the pressure, temperature and capacity of the oil as well as a set of self-cycle filtering system and self-cycle cooling system.
EH系统油动机 EH system oil servomotor
EH system oil servomotor is the most important part of EH control system. There are electric hydraulic servo valve, throttle check valve, quick discharge valve and regressive check valve installed in the control block; therefore, it can compose two basic types of actuator, namely on-off type and servo control type, by connecting hydraulic pressure cylinder with a control block and other additional components.
EH系统危急遮断系统 EH Emergency Trip System
To prevent steam turbine from serious accident caused by malfunctions of some equipment, an emergency trip system is installed to EH unit. The emergency trip system mainly consists of electro-magnetic valve unit, hydraulic trip valve, air pilot valve, EH oil pressure test device, bearing oil pressure test device, condenser test device and combined test device. The emergency trip system also keeps watch on some working parameters of the steam turbine. As these parameters exceed its restriction, the system will send a trip message to shut off all of the steam-intake valves.
Monitored parameters mainly include:
Steam turbine over speed, thrust bearing abrasion, bearing oil pressure over-low, condenser vacuum over-low and fire-resistant oil pressure over-low.
EH系统再生装置 EH system regenerator
Regeneration unit for fire-resistant oil can make the oil keep neutralized and remove the moisture so as to refresh the fire-resistant oil. It is mainly composed of diatomite filter and fine filter (i.e. corrugated fiber filter).
EH油管路系统 EH Oil Pipe System
Oil Pipe system is mainly composed of a suit of pipe and accessories (for example connector, tee joint, elbow, etc.), as well as high pressure accumulator and low pressure accumulator. Its function is to connect the oil supply system and the emergency trip system with actuator, and form into a circuit.