El retorno de condensado de un sistema de Vapor es muy importante, ya reduce los costos de aditivo , agua y combustible.

1. Boiler Condensate Return Basics
Presented by Steve Connor
February 24, 2016

2. What We Are Covering Today?
• Brief review of the total steam system
• Why a proper condensate return system is so important
• Condensate return and affect on the property’s operation
• What compromises the optimum condensate return system
• The corrective actions
• Delivering condensate back to the boiler room
• The choices for holding and treating this condensate.
• Summary
• Q/A
2

3. 3
T
T
T
T
T
Steam
Condensate
H P Cond Return
Vent
D A TankD A Tank
Feed PumpBoiler
Strainer
Trap Trap
Trap Trap
TT
TT
DA
Tank
TT
TT
TTT
HP Steam
PRV
15 psig
250 F
LP Steam
150 psig
366 F
Trap
LP Condensate Return
Cond Recovery
& Pump
Motive
Force
Supply and Return System(s)
3
Legend

4. Water inlet
To drain
To drain
Total Boiler Room
4
Chemical feed
Water softener
Feed system

5. 5
T
T
T
T
T
Steam
Condensate
H P Cond Return
Vent
D A TankD A Tank
Feed PumpBoiler
Strainer
Trap Trap
Trap Trap
TT
TT
DA
Tank
TT
TT
TTT
HP Steam
PRV
15 psig
250 F
LP Steam
150 psig
366 F
Trap
LP Condensate Return
Cond Recovery
& Pump
Motive
Force
Supply and Return System(s)
5
Legend

6. Reasons why condensate system is important
• Operating cost reduction
• Reliability
• Safety

7. Let’s first look at Efficiency & Cost of Operation
OK…

8. What is the cost of steam?
2011 Steam Rate
($15.00/1,000 lb)

9. Steam - Basic Concepts
2120 F.
2000 F.
1000 F.
320 F.
00 F.
138 880
Latent Heat
of Vaporization
(or Latent Heat
of Condensation)
Latent
Heat of
Fusion
Btu per pound of water
Sensible
Heat
Sensible
Heat
3380 F.
Boiler operating at 100 psig and 200 OF feed water
1 lb
water at
338O F
1 lb
steam at
338O F
1 lb
water at
200O F
9

10. Saturated Steam Table
Pressure
(psig)
0 10 80 100
Saturation
Temp
212 239.5 323.9 337.9
Volume (ft3/lb) 26.4 16.46 4.66 3.89
Sensible Heat
(btu/lb)
180 207.9 294.4 308.9
Latent Heat
(btu/lb)
970 952.5 891.9 880.7
Total Heat
(btu/lb)
1150 1160.4 1186.3 1189.4
Start @ 32 deg. F
10

11. FWT
30
Gauge Pressure - psig
40
70
80
60
140
100
150
110
50
130
90
160
170
180
120
190
200
212
220
227
230
29.0
29.3
30.1
30.4
29.8
32.1
30.9
32.4
31.2
29.6
31.8
30.6
32.7
33.0
33.4
31.5
33.8
34.1
34.5
34.8
35.0
35.2
29.0
29.2
30.0
30.3
29.8
32.0
30.8
32.4
31.2
29.5
31.7
30.6
32.7
33.0
33.3
31.4
33.7
34.0
34.4
34.7
34.9
35.0
28.8
29.1
29.9
30.1
29.6
31.8
30.6
32.1
30.9
29.3
31.5
30.4
32.4
32.7
33.0
31.2
33.4
33.7
34.2
34.4
34.7
34.8
28.7
29.0
29.8
30.0
29.5
31.7
30.6
32.0
30.8
29.2
31.4
30.3
32.4
32.6
33.0
32.2
33.3
33.6
34.1
34.3
34.5
34.7
28.6
29.4
29.7
29.1
31.4
30.2
31.6
30.5
28.9
31.1
30.0
31.9
32.3
32.6
30.8
32.9
33.2
33.5
33.0
34.2
34.4
34.5
28.4
29.2
29.5
28.9
31.1
30.0
31.4
30.3
28.7
30.8
29.8
31.7
32.0
32.3
30.6
32.6
32.9
33.2
33.6
33.9
34.1
34.2
28.3
29.1
29.4
28.8
31.0
29.9
31.3
30.2
28.6
30.7
29.6
31.6
31.9
32.2
30.4
32.5
32.8
33.1
33.5
33.8
34.0
34.1
28.2
29.0
29.3
28.8
30.9
29.8
31.2
30.1
28.5
30.6
29.6
31.5
31.8
32.1
30.3
32.4
32.7
33.0
33.4
33.7
33.9
34.0
28.2
28.9
29.2
28.7
30.8
29.7
31.1
30.0
28.4
30.5
29.5
31.4
31.7
32.0
30.2
32.3
32.6
32.9
33.3
33.5
33.8
33.9
28.1
28.8
29.1
28.6
30.7
29.6
31.0
29.8
28.3
30.4
29.3
31.2
31.5
31.8
30.0
32.2
32.5
32.8
33.2
33.4
33.7
33.8
28.0
28.8
29.0
28.5
30.6
29.5
30.9
29.8
28.2
30.3
29.2
31.2
31.4
31.7
30.0
32.1
32.4
32.7
33.1
33.3
33.6
33.7
28.0
28.7
29.0
28.5
30.6
29.5
30.8
29.8
28.2
30.3
29.2
31.2
31.4
31.7
30.0
32.0
32.4
32.6
33.0
33.3
33.5
33.6
27.9
28.7
28.9
28.4
30.5
29.4
30.8
29.7
28.2
30.2
29.2
31.1
31.4
31.7
30.0
32.0
32.3
32.6
33.0
33.2
33.5
33.6
27.9
28.6
28.9
28.4
30.5
29.4
30.8
29.7
28.2
30.2
29.2
31.1
31.4
31.6
30.0
32.0
32.3
32.6
33.0
33.2
33.4
33.5
27.9
28.6
28.9
28.4
30.4
29.4
30.8
29.7
28.2
30.2
29.1
31.0
31.3
31.6
29.9
31.9
32.2
32.6
32.9
33.1
33.4
33.5
27.9
28.6
28.8
28.3
30.4
29.3
30.7
29.6
28.1
30.1
29.1
31.0
31.3
31.6
29.9
31.9
32.2
32.5
32.9
33.1
33.3
33.4
27.9
28.6
28.8
28.3
30.4
29.3
30.7
29.6
28.1
30.1
29.1
30.9
31.2
31.5
29.8
31.8
32.1
32.4
32.8
33.1
33.3
33.4
0 2 10 15 20 40 50 60 80 100 120 140 150 160 180 200 220
27.8
28.5
28.8
28.3
30.4
29.3
30.6
29.6
28.1
30.1
29.0
30.9
31.2
31.5
29.8
31.8
32.1
32.4
32.8
33.0
33.3
33.4
240
Capacity At Operating Pressures vs. FWT
.

12. Energy Dollars at Risk
$
DOWN
THE
DRAIN
12
Every 10 degree drop in feed water
temperature equals a 1% drop in efficiency!

13. 13
Blowdown Heat Recovery Types
Blowdown Heat Recovery Unit
• Proportional blowdown heat recovery system
• Atmospheric feed or deaerator
• Automatically controls TDS
• Single or Multiple Boilers
• Blowdown is cooled before discharge (Code compliance)

14. Condensate Recovery
Savings Derived from:
• Fuel savings
• Chemicals
• Water
• Sewer costs
Bringing back condensate at
higher pressures will result in
even greater savings!

15. Reliability Issues

16. Shell & Tube
Plate & FramePressure Regulating Valve
16
Jacketed Kettle
Split System

17. Condensate Back-up or “Stall”
17

18. Constant Orifice Purge

19. Steam Pump Trap
Steam power
pump

20. Vacuum breaker
Water leg
Vacuum breaker
Trap
NOTE: 2.3 feet of static head = 1 pound pressure

21. Air vent

22. Non Condensable Gas Corrosion
Courtesy:http://www.engineeringtoolbox.com/oxygen-steel-pipe-...
50 F
86 F
122 F
• Almost 2 times more
corrosive at 122o F
than at 86o F
• Dissolved oxygen is
10 times more
corrosive than CO2
CO2O2

23. 23
Air and Corrosion
The Piping is Subject to Corrosion
Subcooled Condensate + CO2
Forms Carbonic Acid
( CO2 + H2O H2CO3 )
40% more corrosive when combined with dissolved O2!!
23

24. Carbonic Acid Corrosion
Cause and Effect
CO2 + H2O = H2CO3
• Created where
condensate is not
fully drained.
• Attacks pipe and
coil material.

25. 25
Carbonic Acid attack
Cause and Effect
CO2 + H2O = H2CO3
25

26. Mechanical Chemical
26
Most Economical Long-Term Approach

27. 27
Steam/Water Separator
Separation Mechanism
Cyclonic Type
• Cyclonic (centrifugal force)
• Baffle (directional flow change)
• Coalescence (trapping media) pad)

28. Secondary Steam Branch Line
In-line
separator
28To condensate return line

29. Drip pockets & Steam Trap Set
Isolation valves
Check valve
strainer
trap

30. Drip Pockets
Steam Trap
Drip Leg
6-10”
BD and Venting
Locations:
• Low Spots
• End of Main Ahead of
Expansion Joints
• Ahead of Valves,
Bends & Regulators
30
Locate every 150 – 300 feet in a linear length of steam pipe

31. 31
Steam Main Size Drip Leg Diameter Drip leg Length
4” 4” 12”
6” 4” 12”
8” 4” 12”
10” 6” 18”
12” 6” 18”
14” 8” 24”
16” 8” 24”
18” 10” 30”
20” 10” 30”
24” 12” 36”
Suggested Sizing
31

32. Moving condensate from source to boiler room
Motive force of steam pressure differential

33. Condensate Transfer Tanks
• Standard models 200°F
or less
• 210°F floor mounted
units w/ low NPSH
pumps
• 212°F elevated units
available, thereby
increasing NPSH

34. Steam & Condensate Velocity
Typical Velocities in steam systems:
Process Piping 6000 – 8000 fpm
(70 – 90 MPH)
LP Heating
Systems
4000 – 6000 fpm
(45 – 70 MPH)
Typical Velocities in Condensate return
systems
Liquid 180 – 420 fpm
Bi-phase Approx. 3000-
7000 fpm
• Boiler operating pressure
• Pounds of condensate
• Pressure at trap inlet
• Pressure in line
• Condensate pipe diameter
• Allowable pressure drop
Note: Pressure drop should not exceed 20% of boiler’s maximum operating pressure

35. 35
T
T
T
T
T
Steam
Condensate
Common Condensate Return
D A TankD A Tank
Feed PumpBoiler
Strainer
Trap Trap
Trap TrapTT
TT
DA
Tank
TT
TT
TTT
HP Steam LP Steam
150 psig
366 F
Motive
Force
Supply and Return System(s)
35
Legend
Trap

36. Saturated Steam Table
Pressure
(psig)
0 10 80 100
Saturation
Temp
212 239.5 323.9 337.9
Volume (ft3/lb) 26.4 16.46 4.66 3.89
Sensible Heat
(btu/lb)
180 207.9 294.4 308.9
Latent Heat
(btu/lb)
970 952.5 891.9 880.7
Total Heat
(btu/lb)
1150 1160.4 1186.3 1189.4
Start @ 32 deg. F
36
.017

37. Steam & Condensate Velocity
Typical Velocities in steam systems:
Process Piping 6000 – 8000 fpm
(70 – 90 MPH)
LP Heating Systems 4000 – 6000 fpm
(45 – 70 MPH)
Preferred Velocities in Condensate return systems
Liquid 180 – 420 fpm
Bi-phase Approx. 3000 - 7000 fpm

38. Condensate Pipe sizing
• Boiler operating pressure
• Pounds of condensate
• Pressure at trap inlet
• Pressure in line
• Condensate pipe diameter
• Allowable pressure drop
Condensate pipe sizing criteria
Example:
• 2000#/HR
• 7000 ft/min
• ¼# drop
• 150# inlet
• Zero & 15# outlet

39. And what’s the Safety Issue with condensate?
Efficiency
Reliability
Capture
Transportation

40. Cause & Effect of Water Hammer
Three Types of Water Hammer:
Hydraulic
Thermal
Differential

41. Thermal water hammer
The steam condensing void is rapidly filled with water
Thermal

42. Thermal Imaging & diffusion of condensate lines
Diffuser

43. 43
Flash Tank
Flash Tank
• Higher temperature drip traps
• Vent to atmosphere
• Use flash steam for LP use (non-modulating)
• Preheat boiler feed water
Drip trap location
Steam User

44. 44
Calculating Flash Steam %
Formula: (hf1 – hf2 )/hfg2 = % Flash
HF1: Sensible Btu’s in
HF2: Sensible Btu’s out
HFG2: Latent Btu’s out
Example: User operating at 150 psig with discharge @
15 psig…..
338 – 218 = 120/946 = 13% Flash Captured!
. Btu’s SAVED!
. Water & Sewer charges SAVED!
. Chemicals SAVED!

45. T
T
T
T
T
H P Condensate Return
Cond. Pump
D A TankD A Tank
Feed PumpBoiler
Strainer
Trap Trap
Trap Trap
TT
TT
TT
TT
TTT
HP Steam
PRV
15 psig
250 F
LP Steam
175 psig
366 F
Trap
Motive
Force
Feed Tank or
DA
HP Condensate Recovery

46. High Pressure Condensate Receiver
• Takes high pressure
condensate directly
from the user.
• No need to deaerate.
• Pump directly into
boiler
• Feed the HPR from
the DA

47. Holding the boiler’s feed water and protecting
the system

48. HOT Condensate returned
Deaerator
Boiler Feed System
A vented receiver, wastes energy.
48
Pressurized receiver, saves energy.
Steam diffusing tube

49. Chemical Feed Tank
49
• Phosphonates
• Chelant (de-scaler)
• Polymers
• Sulfite
• Non-sulfite scavengers
• Amines (neutralizing or filming)
Mixing and Dispensing

50. Final Summary
50
• The boiler is part of a total system including its piping supply and return
network, and all the associated accessories supporting the total whole.
• Proper condensate line engineering impacts energy efficiency,
production reliability, and safety
• Every 10 degree pickup in feedwater temperature = 1% fuel savings
• Condensate is sensible energy which increases with increasing
operating pressures
• Reliability is affected by system backup (Stall) and system corrosion
• Condensate line water hammer is normally Thermal type
• Flash recovery systems can mitigate problem and save energy
• Recommended velocities in bi-phase condensate lines is 3000 – 7000
ft/min
• As line pressure in bi-phase condensate increases the volume
decreases, reducing line size for same velocity.
• Condensate line sizing involves knowing boiler pressure, trap inlet
pressure, pounds of condensate, common line pressure, desired
velocity, and desired pressure drop

51. Steve Connor
Training & Technical Consultant
• sconnor@cleaverbrooks.com
• www.cleaverbrooks.com
51