The invention discloses a supercritical high-temperature and high-pressure
gate valve, belongs to the technical field of gate valves, and solves the problems that a gate plate is possibly subjected to heat collision, so that the gate plate and a
valve seat are locked or clamped, and the gate plate is damaged when being separated from the
valve seat. Comprising a valve body, a multi-stage air cylinder located above the valve body, a
valve seat fixedly connected into the valve body, a connecting gate plate capable of vertically moving in the valve body and end gate plates located on the two sides of the connecting gate plate, and the multi-stage air cylinder comprises a
piston pipe capable of vertically moving and a
piston rod capable of moving in the
piston pipe; the lower end of the piston
pipe is fixedly connected with an inverted-U-shaped connecting frame. When the device is applied to the supercritical boiler, supercritical water transportation is controlled through the
gate valve. The multi-stage air cylinder controls the gate plate to be opened and closed, and locking or clamping caused by
thermal expansion is avoided. After detection of the locking
monitoring system, locking of the connecting flashboard is removed preferentially, then the end flashboard is removed, and damage and sealing performance reduction are prevented.