2. Working principle
Electric or hydraulic cartridge valves are usually used with metal sealing butterfly valves. Take the blocked hydraulic gate valve as an example. The opening and closing of the valve consists of two parts: the valve seat propulsion mechanism (hydraulic cylinder) and the valve plate traveling mechanism (hydraulic motor). The valve plate is respectively provided with a through hole seat and a blind hole seat. The switching between the through hole seat and the blind hole seat of the valve plate is completed by pushing (releasing the valve plate) → moving the valve plate laterally → clamping (sealing the sealing pair of the valve plate), thus realizing the opening and closing of the valve. Both the valve seat propulsion mechanism and the valve plate traveling mechanism of the electric cartridge valve are driven by electric devices.
3. Fault analysis
The lateral movement of the valve plate is realized by the sprocket of the valve plate traveling mechanism driving the transmission pin shaft at the lower part of the valve plate. When the electric cartridge valve is debugged in the factory, after the valve plate moves in place, adjust the travel limit switch of the electric device to ensure that the electric device stops running and the limit device realizes the limit of the valve plate. When the hydraulic cartridge valve is debugged in the factory, after the valve plate moves in place, the valve plate travel switch is adjusted to stop the driving of the hydraulic motor, and the limit device realizes the limit of the valve plate. However, in the process of valve use, the travel switch sometimes lags behind or fails.
Through on-site analysis, it is confirmed that the signal from the travel switch is delayed or invalid due to the wrong adjustment of the electric device counter and the inertial collision of the moving parts, which leads to the overload of the electric device or hydraulic motor, damage to the transmission shaft or coupling of the valve plate traveling mechanism, and the operation accident of blast furnace gas and its system.
4. Improvement measures
Pin-and-rack safety device is to realize its safety function by using the gear to engage with the transmission pin shaft in place, and then the transmission pin shaft is separated from the gear in time, so that the gear idles and does not drive the rack to walk. This safety device will not hinder the reverse operation of the gear. Pin-and-rack safety devices usually adopt chute type and flow pin type structures. Pin-rack safety devices are arranged at the two limit positions of the lateral movement of the valve plate, and the safety of all transmission parts of the valve plate traveling mechanism is ensured by the idling of the cogwheel disengaged from the pin-rack. Chute safety device is simple in structure and is often used to open gate valves. The invention is suitable for closed gate valves. In the design, the pin hole diameter of the flow pin is appropriately increased, and the auxiliary return spring of the flow pin is equipped to ensure the normal lateral movement of the valve plate.