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The purpose of a condensate steam trap. To obtain a maximum efficiency and productivity from an installations, a steam trap should not only provide the separation of water and steam. A number of criteria, grouped in four categories must be satisfied. Operation and output Energy conservation Maintenance and life span Installation/investment

Operating criteria Instant condensate evacuation Adapt to flow variations Adapt to upstream pressure variations Functioning in presence of back pressure Venting of non-condensables on start-up Venting of non-condensables at steam temperature Insensitive to climatic changes Pressure/flow operating range Follow the saturation curve. Check valve fonction

Energy conservation criteria Tight shut off valve and seat arrangement No leaks at body joints Tight shut-off at closure or no delay at closure Efficient at low flow Possibility of trap insulation Sub-cooling energy conservation

Maintenance and life span criteria Ability to handle dirt Resistance to wear Internal and external corrosion resistance Resistance to superheat Water hammer resistance Resistance to damage from freezing Easy maintenance Easy and fast trap testing diagnostic

Assembly and investment Criteria Capacity / size ratio Price Ease of installation Application versatility Spare parts prices

Steam straps various technology Type Method of operation Family Mechanical Density differencial I.B. F.&.T Temperature Temperature differencial B.M Capsule Thermodynamics Speed differencial T.D Venturi Pressure loss Orifice

Inverted bucket steam trap. Principal of operation (I.B.) Inlet sortie Valve and seat Lever Inlet Tube Bucket entrée Start up mode Outlet

Steam + Air Condensate Presence of steam = Steam trap closing

Condensation phase and incoming condensate

Steam trap opening – elimination of condensate

Operational Forces

IB Steam trap Avantages No loss of live steam : the steam trap water seal prevent the loss of steam. Continuous condensate discharge Long life expectancy Water hammer resistance Remove air and CO2 at saturated steam temperature

IB Steam trap Advantages Adapt to upstream pressure variations Instant response to condensate load variations Not affected by dirt because of its discharge orifice at the top of the trap and the syphon effect when the orifice is completely open Fail open steam trap

Important details of conception The mechanism is free-floating Valve continues to seat itself deeper with wear, preserving a tight seal.

IB Steam trap inconveniencies For all the models , except the models with connector, the IB should be installed only on horizontal or vertical lines. Some model have a tendency to pass live steam on superheated steam application, if proper piping installation is not done .

Operation principals of Float & Thermostatic steam trap Thermostatic air vent levier Float Water seal valve Start up mode

Presence of steam - Thermostatic air vent closing

F & T steam trap advantages Can vent a large quantity of non-condensables because the air vent mechanism is distinct from the steam trap condensate mechanism. Continuous condensate discharge without retaining water upstream of the steam trap The discharge orifice is surrounded by a water seal, preventing live steam loss. Capable of handling large capacity of condensate

F & T steam trap inconveniences Because the orifice is at the bottom of the trap and the continuous discharge principle this steam trap is sensitive to dirt. When steam is shut off, water stays in the steam trap body becoming sensitive to frost damage. Water hammer can damage the float by implosion and destroy the thermostatic element. Can’t be used in superheated steam because of thermostatic element limitations. Fail close position.

Operation principals of thermodynamics steam traps Pressure chamber Disc Seat Discharge orifice

Condensate Flash Steam Steam Inlet Outlet At start-up, the condensate removes the disc from the seat

The steam penetrates inside the steam trap Flash Steam Condensate The steam penetrates inside the steam trap

The steam occupies the chamber capacity – Steam trap closing

Condensation of steam in the steam trap chamber

Air The steam trap air binds in presence of non-condensable

This problem appears frequently at start-up.

Operational Forces

Features of a thermodynamic steam trap Small, light weight, easy to install. One size orifice for all pressure ranges, Stock reduction. Large capacity in proportion to it’s size. It’s one mobile part make it resistant to ‘’water hammer’’. Competitive pricing

Inconveniences of the thermodynamic steam trap The disc opening cycle depends on the pressure over the disc. The climatic conditions therefore influence the operation of each cycle, by cooling the body of the trap, where a rapid condensation of the steam and a pressure drop occur over the disc. Operation cycle, fast at low loads, cause a premature wear and tear. The operation cycle speeds up when seat wear appears, this accelerates the wearing process and reduces the service life of the steam trap.

Inconveniences of the thermodynamic steam trap Does not close if back pressure reaches 50 % of upstream pressure. A steam trap leak could drive other steam traps that are connected to the same line system to leak. Does not close if a pressure drops under 5 psi. The requirements specified for the surface conditions, makes it very sensitive to dirt. No instant reaction to condensate loads variations. Retains the condensate between cycles.

2 main reasons why the TD steam trap wear and tear rapidly Snap closure of the disc against the seat at each cycle. High velocity outlet = premature erosion of disc and lost, of seat tightness.

Operation principals of thermostatic bellow steam strap Alcohol Valve Seat

Operation principal of thermostatic bellow steam strap Condensate cooling Steam

Operation principal of thermostatic wafer steam trap Distilled water + alcohol Diaphragm

Wafer steam trap opening curve Saturation curve Steam Close Steam trap temperatue Delta T Open Steam trap Water Pressure (psig)

Operational Forces

Advantages of Wafer Steam trap and Bellow Steam strap In general sizes are small and light Reduces the amount of flash steam Allows sensible heat recuperation Will adapt to pressure and discharge variations At start-up, it will remove the non-condensables

Inconveniences of bellow steam trap Sensitive to dirt Upstream condensate retention (sub cooling) causes a reduction in Ph which develops corrosion and premature wear Sensitive to water hammer Not adapted for superheated steam Can fail close

Bimetallic Steam Trap Adjusting screw Bimetallic strips Valve stem Inverted valve

Air at Start-Up

Condensate at start-up

Condensate Flash Steam Steam

Steam + air

Operational Forces

Opening curve of a Bimetallic Steam Trap Saturated curved steam temperature Delta T Close steam trap water Open steam trap pressure

Bimetallic Steam Trap Advantages Ability to handle start-up air loads Recuperation of sensible heat Reduces the amount of flash steam Resistance to water hammer

Bimetallic Steam Trap inconveniences Sensitive to dirt Sensitive to back pressure Sensible to upstream pressure variation Improper continuous air venting Not adapted for process applications Valid capacity curves for a given temperature

Selection methodology for condensate steam trap Steam Main Boiler Header Unit Heather Exchanger Tracing Drum dryer Q=L.M.Cs.t.60 Q=V..Cs.t Q=<1 kg/h.m r.temps r Q= Cap. Boiler Q=V..Cs.t Q=L.Ø..35 kg/h.m² 0,1 r Qx1,5 QX2 QX2 QX2 Aucun Q x3 à 5 QX3 QX3 Application Calculation of flow in kg/h Safety margin