Steam Trap
Steam that comes out of boiler will form into condensate or “drain” when heat is lost in pipes or in other process
Steam trap is a device that discharges condensate appropriately
■Discharge condensate
■Minimize leakage of steam
■Discharge air and others promptly
Steam trap is a device that discharges condensate appropriately
Mission
■Discharge condensate
■Minimize leakage of steam
■Discharge air and others promptly
Types of Steam Trap
1.Intermittent (Mechanical)
Bucket type
Disc type
Bi-metal type
Free Float type
※Partially involves “Consecutive” type nature
2.Consecutive
Orifice and Nozzle types
ST Nozzle Type Steam Trap
Mechanical Trap
Benefit and Issues of Mechanical Type
Benefit
Adjust to changes in condensate amount and in pressure, if such changes are within a defined range
Issues
Some steam leakage are structurally inevitable
It discharges all condensate to avoid water hammer caused by open/close pressure changes. Steam leakage is unavoidable
Moving parts cannot lubricated (e.g. grease, bearing) due to high-heat and pressure. Drain sensor and valve are located nearby. This would result in setting some clearance or gap in design, which in return causes aging deterioration, shorter life and steam leakage
Stuck foreign particle and accumulation causes steam leakage. Moving parts may not synchronize with the high- speed discharge flow, which also causes steam leakage
A Consideration on Mechanical Trap
For example, a 25A steam regulator is priced around 150,000 yen, while a steam trap from the same manufacturer and with the similar parts count is priced around 30-40,000 yen
This was achieved by compounding replacement period, aged deterioration, manufacturing precision (man hour) and admitted leakage
(clearance margin)
Some Misunderstanding about Mechanical
Risk in Mechanical
Intermittent, as compared with consecutive, may have more leakage when the system is in trouble. There is no risk that the process stops due to jammed
⇒Maybe so from probability standpoint. Not necessarily so, however
Issue in Free Float
Free float has best of both worlds (intermittent and consecutive), and has no such a problem
⇒It would have less leakage, however, inherits the problems of both at the same time. The issues have not been resolved
Orifice and Nozzle Tap
Benefit and Issues of Orifice and Nozzle Types
Benefit
No leakage caused by the issues of Intermittent
Issues
Orifice has a smaller cross-section area and does not adjust to changes in drain amount or to pressure
Clogging happens, which could cause a system halt
Flash steam (and corrosion) may widen the hole and increase the discharge as it ages
Orifice plate change is not easy, nor allow granular settings. Some leakage is not avoidable
Some Misunderstanding about Orifice and Nozzle
“There is no water hammer in Consecutive, as there is no pressure change in the charging side. And therefore it allows discharging only condensate efficiently by accumulating condensate at pre-Trap stage”
Subject to adjustment to changes in drain amount, the ideal situation is to accumulate all condensate at pre-orifice stage
However, Non-ST orifice and nozzle traps tend not to be designed to accumulate condensate in the charging side (as is the case with Intermittent). There should be unavoidable steam leakage
