Watson McDaniel Steam Design Guide

Steam & Condensate Introduction

Steam Traps

Operation of a Steam System

How does condensate flow through steam traps? Steam Pressure pushes the condensate through the trap .

Every steam trap has an Inlet Pressure (Steam Supply Pressure) and an Outlet Pressure . The difference between inlet & outlet pressure is referred to as the Differential Pressure . When the Inlet Steam Pressure is higher than the Outlet Pressure (Positive Differential Pressure), the steam will “PUSH” the condensate through the steam trap.

Outlet Pressure

Inlet Pressure 50

Differential Pressure is an important factor for sizing steam traps as well as other components, such as regulators and control valves. The higher the Inlet Pressure in relation to the Outlet Pressure, the more condensate the trap can remove from the steam system. The trap capacity is therefore a function of the differential pressure across the trap.

0

Inlet Pressure (Steam)

Differential Pressure

Outlet Pressure (Condensate)

=

Steam pressure pushes condensate through the trap

50 psig

– 0.0 psig

= 50 psi

50 psig Inlet Pressure

Roof

Air Vent Open Discharges air during start-up

0 psig

Outlet Pressure

Process #2

Process #1

Vat Process

Steam Jacketed Kettle

Drip Trap TD600S

Drip Trap TD600S

0 psig

0 psig

Process Trap

Process Trap

Steam

Drip Trap TD600

Drip Trap TD600

Vented Receiver

Condensate Return Line Condensate flows by gravity into the flash vessel .

Boiler

Pump

Condensate Return Pump A mechanical or electric Pump is used to return the condensate.

Vented Receiver A Vented Receiver maintains a pressure of 0 psig inside the condensate return lines by venting the flash steam generated by

the hot condensate to the atmosphere.

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