The impulse safety device is the main safety valve, with auxil-iary valve support contained. This device has characteristics as large discharge ability, convenient adjustment, dual mechanical and electric protection and few workload in installation and maint-enance.
This device is used for inlet and outlet pipe of reheater to avoid mediun pressure exceeding the allowable value to ensure the reheater shall run safely.
1.The impulse safety device is as shown in the figure, mainly consisted of impulse safety valve, the main safety valve, stop valve and throttle valve. Impulse safety valve is a kind of spring safety valve. It is mainly consisted of body , bonnet, disc and other parts.The impulse safety valve can be adjusted by using the spring to regulate the pressure.
The impulse safety valve contains an electromagnet to open and another to close the valve. The actions of the mechanism and the electric appliance are separate and will not affect each other .
2.The main safety valve is as shown in the figure. With astructure of single exhaust and both ends of flange connection, it is mainly consisted of body, bonnet, piston chamber, disc, stem and other parts.
3.Both the sealed surfaces of disc and seat of the impulse safety valve are made of hard alloy of cobalt by overlaying welding Both the seat and the disc of the main safety valve are made of hard alloy of cobalt by plasma spray welding.
4.The upper part of the impulse safety valve contains an elec-tromagnet to open and another to close off. At ordinary times, the close-off electromagnet may not be electrified, but when the sealed surface of the valve leaks or when the mechanical addition adjusting reseating pressure is excessively low, it can be electrified by closing electromagnet to make valve sealed or help the valve clack return and procure a higher seat reseating pressure.
5.The impulse safety valve only leaves the factory after it has passed the seal and sensitivity tests, proved to be qualified.
When the medium pressure inside the reheater exceeding the allowable value, the impulse safety valve opens firstly; the steam enters into the piston chamber of the main safety valve, forcing the main safety valve to open; the reheater bengins discharging steam;after the excess pressure has been released, the impulse safety valve closes, stopping the steam entering into the piston chamber of the main safety valve; the main safety valve automatically colses at the reactions of the spring and medium.