R016600x

Steam Generator & Fluid Heater Installation Manual

1.1.5 Vent The receiver must have a vent to discharge non-condensible gases from the feedwater. The Clayton vent most often provided is a 3/4 inch orifice union with a 1/8 inch orifice. This will con- tinuously vent a small amount of steam with the gases. 1.1.6 Level Control A liquid level controller is mounted on the receiver to control the make-up water pump. This control starts and stops the make-up pump as required. The differential between the high and low levels is a narrow band (2 to 3 inches). The water level should be maintained approximately one quarter from the top of the tank, and at the proper height for the required NPSH of the gener- ator feedwater pump. 1.1.7 Steam Relief Valve The SCR must have a steam safety relief valve with a setting not greater than the design pressure of the tank. This valve must comply with all safety codes and must be capable of reliev- ing at least 25 percent of the connected generator steaming capacity at the SCR operating pres- sure. The discharge from this valve must be piped to atmosphere and in a direction that will not cause harm to equipment or personnel. 1.1.8 Sparger Tube The high pressure condensate returns must be injected into the SCR through a sparger tube. The sparger tube inlet must be 8–12 inches below the lowest water level so the heat will be transferred from the condensate to the liquid in the SCR with the least possible noise and vibra- tion. The trap returns from the Clayton separator should also be piped into the sparger tube. 1.1.9 Back Pressure Regulator A Back Pressure Regulator (BPR) must be installed on the receiver to help control the tank pressure during large load swings, or in the event of system traps malfunction. The BPR should be set at 3–5 psi above the normal operating pressure. 1.1.10 Pressure Reducing Valve A Pressure Regulating Valve (PRV) must be installed on the SCR to maintain a preset pressure. The PRV senses the SCR pressure and injects steam (above the water level) from the header in the event of a reduction in the tank pressure. The PRV should be set at 1–2 psi below the normal operating pressure. The PRV design flow must be equal to 25 percent of the maximum steam production rate. If low pressure steam is to be drawn from the receiver for other uses, this capacity must be considered when sizing the PRV. A check-valve must be installed between the PRV and the receiver to prevent backflow in the event of a flooded condition in the receiver.

NOTE The PRV and BPR are not options. They must be installed to ensure the effective and efficient operation of the Clayton Semi-closed Re- ceiver System.

SI-2

Supplmt01_SCR_c.fm

07/10/2015