Presentation on theme: "En l an 2000 100 ans d expérience sur la vapeur Armstrong International 100 years of experience in Steam applications."— Presentation transcript:
en l an ans d expérience sur la vapeur Armstrong International 100 years of experience in Steam applications
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
E nergy 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.) sortie entrée Inlet Outlet Valve and seat Bucket Lever Inlet Tube Start up mode
Steam + Air Condensate Presence of steam = Steam trap closing
Condensation phase and incoming condensate
Steam trap opening – elimination of condensate
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 CO 2 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 Float Water seal valve Thermostatic air vent levier 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. Cant be used in superheated steam because of thermostatic element limitations. Fail close position.
Condensate Flash Steam Steam Inlet Outlet At start-up, the condensate removes the disc from the seat
Steam Condensate Flash Steam The steam penetrates inside the steam trap
The steam occupies the chamber capacity – Steam trap closing
Condensation of steam in the steam trap chamber
The steam trap air binds in presence of non-condensable Air
This problem appears frequently at start-up.
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 its size. Its 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 principal of thermostatic bellow steam strap Condensate cooling Steam
Operation principal of thermostatic wafer steam trap Diaphragm Distilled water + alcohol
Wafer steam trap opening curve Delta T Pressure (psig) temperatue Steam Water Saturation curve Open Steam trap Close Steam trap
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
Opening curve of a Bimetallic Steam Trap Delta T pressure temperature steam water Saturated curved Close steam trap Open steam trap
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.tempsr 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