Desuperheater apparatus and method

Abstract

The present invention inserts and retrieves a desuperheating assembly from within a pressurized steam header through an existing conduit that joins the steam header to the surrounding environment. A gate valve is disposed within the connecting conduit obstructing access to the steam header when closed. The spray nozzle of the desuperheating assembly is attached to a fluid supply pipe and is placed within the conduit on the side of the gate valve that is exposed to the ambient environment. A gas impervious seal is produced between the conduit and the fluid supply pipe so as to isolate the spray nozzle between the gate valve and the gas impervious seal. The gate valve is opened exposing the spray nozzle to the steam header. The supply pipe is advanced past the gas impervious seal, which in turn, drives the spray nozzle into the steam header. Water or steam atomized water can be supplied to the spray nozzle from an external source through the supply pipe that extends from the spray nozzle within the steam header, past the gas impervious seal, to a point external of the vessel. When retrieving the spray nozzle from within the steam header, the supply pipe is retracted past the gas impervious seal within the connecting conduit. As such, the spray nozzle is retracted into the connecting conduit past the gate valve. The gate valve is closed and the spray nozzle is isolated from the steam header. The pressure surrounding the spray nozzle is vented to ambient and the spray nozzle can then be removed without adversely effecting the flow of steam within the steam header. The spray nozzle can then be repaired or replaced and returned into the steam header as described.