SigmaFire Installation Manual, rev. F - Clayton Industries

Section IIIDrainCondensateReturns&Sparger TubePressureRegulatingValveSafety ReliefValveBack PressureRegulationValveTable 3-4: Deaerator ConnectionsA drain valve must be provided in the drain line. As indicated above, the drain line can betied into the overflow line as long as the line size downstream of the merge remains atleast the size of the overflow connection on the tank.NOTEThe deaerator drain and overflow lines (run independently or tied together) typicallycontain water at >230 o F and must be routed to a blowdown tank dischargepiping at a point prior to the temperature valve sensor.Most deaerators have a high and low pressure condensate return connection. The highpressure condensate return connection is where all system condensate return andseparator trap discharge is introduced. Low pressure returns are typically pumped from acondensate collection tank to the low pressure return connection. The high pressurecondensate return connection(s) is located below the water line with a sparger tubeinstalled internally. Introducing the steam and hot condensate below the water line inconjunction with using the sparger tube reduces the velocity and turbulence created at theinjection point, while minimizing flash steam losses and noise. In all cases, a check valvemust be installed, as close to the DA as possible, in the steam heat and condensate returnlines to prevent back-feeding. When installing a sparger tube(s) it must be installed sothat the holes are in a horizontal position.Steam is injected into the high pressure side of the tank to maintain the desired operatingpressure. A Pressure Regulating Valve (PRV) is used for pressure regulation.Each deaerator is equipped with a safety relief valve to prevent overpressurizing of thetank. This valve is typically rated at 50 psi. The safety relief valve must discharge toatmosphere and in a direction that will not cause harm to personnel or equipment. Thedischarge piping must not contain any valves or other obstructions that could hinder therelease of steam.A back pressure regulator is used to help maintain a steady operating pressure in the DA.This valve is set below the safety valves and will vent during minor periods of overpressurization.NOTEBPR sensing line must be plumbed directly to DA pressure sensing port at thegauge connection on top of the DA tank.3.6 SEMI-CLOSED RECEIVER (SCR)Semi-Closed Receiver (SCR) systems are used only in applications that return a largeamount (typically > 50%) of high pressure, high temperature, condensate. The SCR is a pressurizedvessel that is maintained at a pressure that will minimize venting (wasting) of the excess systemheat contained in the hot condensate returns. Feedwater outlet line sizing is critical. SeeSection 2.11.Each SCR system is unique and requires individual attention to ensure proper application,installation and operation.04/22/2015 3-7 Sect03_FeedwtrSys_SF_f.fm