Steam
Driving Toward Energy Efficiency
Emerson Process Management
Novaspect. Inc.
June 22 / 23, 2010
Steam – Take a System Approach
Flash
Recovery /
Cascade
Systems
Air Venting
Steam Traps Distribution Drain Traps
High Pressure
Process Use
Pressure
Let Down
Med. Pressure
Process Use
Med. Pressure
Tracing
Insulation
Separation
-Steam
Quality
-Efficiency
Low Pressure
Tracing
Low Pressure
Process Use
Atmospheric Flash
Tank for Condensate
Recovery
Local Atmospheric Flash Tank
for Condensate Recovery w/
Condensate Pumping
Steam
Generation
Condensate Pumping
Make Up
Water
Topics
Flash
Recovery /
Cascade
Systems
Insulation
Pressure Reduction
Air Venting
Steam Traps Distribution Drain Traps
High Pressure
Process Use
Pressure
Let Down
Med. Pressure
Process Use
Med. Pressure
Tracing
Insulation
Separation
-Steam
Quality
-Efficiency
Low Pressure
Tracing
Flash Recovery / Cascade Systems
Atmospheric Flash
Tank for Condensate
Recovery
Local Atmospheric Flash Tank
for Condensate Recovery w/
Condensate Pumping
Steam
Generation
Steam Trapping & Steam Trap Management
Steam Leak Detection & Repair
Air Venting
Steam Using Process Equipment
Steam Tracing
Atmospheric Flash Tanks / Flash Condensing
Condensate Return
Low Pressure
Process Use
Condensate Pumping
Make Up
Water
Note
•Today’s presentation is efficiency
centric.
Flash
Recovery /
Cascade
Systems
Air Venting
Steam Traps Distribution Drain Traps
High Pressure
Process Use
Pressure
Let Down
Med. Pressure
Process Use
Med. Pressure
Tracing
Insulation
Separation
-Steam
Quality
-Efficiency
•Historically, projects have not been
driven solely on energy savings.
Low Pressure
Tracing
Atmospheric Flash
Tank for Condensate
Recovery
Local Atmospheric Flash Tank
for Condensate Recovery w/
Condensate Pumping
Steam
Generation
•Other drivers include:
-Safety
-Throughput
-Reliability / Maintenance
Low Pressure
Process Use
Condensate Pumping
Make Up
Water
What Do You Want to Know & Why
(Monitoring Points / Value)
•You can’t manage or control what you
don’t measure
Flash
Recovery /
Cascade
Systems
Air Venting
Steam Traps Distribution Drain Traps
High Pressure
Process Use
Pressure
Let Down
Med. Pressure
Process Use
Med. Pressure
Tracing
Insulation
Separation
-Steam
Quality
-Efficiency
-Typically steam systems are under measured
Low Pressure
Tracing
Low Pressure
Process Use
•Typical measurement points serve to
determine where the steam goes, how
much is being used, determine where losses are occurring and
to help troubleshoot system issues.
Atmospheric Flash
Tank for Condensate
Recovery
Local Atmospheric Flash Tank
for Condensate Recovery w/
Condensate Pumping
Steam
Generation
Condensate Pumping
Make Up
Water
-In steam using process equipment, temperature and ΔP measurements
lead to informed process and efficiency improvement decisions.
-In the distribution / condensate return system the ΔP is the condensate
driver; flow and temperature measurement let you monitor and put a
value to the energy being returned back to the boiler.
Assumptions / Clarifications
•Cost of Steam
100 PSIG Steam Cost / Per 1K LB
Inlet Temperature / °F
Fuel / Nat. Gas
Water
Chemical Treatment
Sewer
Facilities / Infrastructure / Personnel
H2O
H2O
H2O $
H2O Sewage $
H2O $
H2O Sewage $
H2O $
H2O Sewage $
Nat. Gas $
Chemical Trtmt $
8.35
7.34
0.03926
0.0236
0.005348774
0.00315508
0.000640572
0.000377854
0.00000408
0.00005
8.89
40.00
4.82
0.64
0.05
0.38
3.00
LB/GAL
GAL/FT3
FT3
FT3
GAL
GAL
LB
LB
BTU
LB/STM
•Definitions
-Sensible Heat: Btu’s contained in liquid
-Latent Heat: Btu’s gained at vaporization and given up at condensation
-Superheat: Btu’s over and above those gained at the at vaporization –
generally measured as temperature above that of saturated steam
Cost Savings through Steam Efficiency
Gallons Wash-down Water / Day
Pounds Wash-down Water / Day
Wash-down Water Inlet Temperature / °F
Wash-down Water Outlet Temperature / °F
Properties of 100 PSIG Steam
100 PSIG Steam Load Requirement at 100% Efficiency / LB
Cost to Heat 1,000,000 Gallons of Wash-down Water / Day
Cost to Heat Wash-down Water / Year
1,000,000.00
8,350,000.00
40.00
150.00
Latent Heat of Steam / BTU per LB
Cost Per 1K LB
880.70
8.89
$
$
1,042,915.67
9,271.39
3,384,057.65
Low Quality / % Entrained Water or Air
Low Quality / Latent Heat of Steam / BTU per LB
100 PSIG Steam Load Requirement at Reduced Efficiency / LB
Cost to Heat 1,000,000 Gallons of Wash-down Water / Day
Cost to Heat Wash-down Water / Year
$
$
5%
836.67
1,097,805.97
9,759.36
3,562,165.95
Cost for 5% Efficiency Loss
$
178,108.30
Insulation
Prevention of radiant heat loss (condensing of steam)
100 PSIG Steam, 100’ 8”, Schedule 40 Pipe, 10 MPH
Wind Speed, 40°F
•Uninsulated Pipe
-415 PPH Condensate / 365,700.9 Btu/HR
-$32,337 Annual Cost
•Insulated Pipe (2” Calcium Silicate)
-19.1 PPH Condensate / 17,097.4 Btu/HR
-$1,512 Annual Cost / $30,825 Annual Savings
-Approximate Payback = 36 days based an installed
insulation cost of $3,000; 71 days based an
installed insulation cost of $6,000
Insulation
Prevention of radiant heat loss (condensing of steam)
100 PSIG Steam, 100’ 8”, Schedule 40 Pipe, 0 MPH
Wind Speed, 70°F
•Uninsulated Pipe
-206 PPH Condensate / 181,654 Btu/HR
-$16,063 Annual Cost
•Insulated Pipe (2” Calcium Silicate)
-19.8 PPH Condensate / 17,426 BTU
-$1,541 Annual Cost / $14,522 Annual Savings
-Approximate Payback = 75 days based an installed
insulation cost of $3,000; 151 days based an
installed insulation cost of $6,000
Pressure Reduction
Ideally, you would produce steam at the pressure
you need at the location it’s required in the quantity
needed…
•Higher pressure generation
-Smaller Pipe Diameter
-Superheated Steam
-Need for pressure reduction
•Do work during the reduction process
-Generate electricity, compress air
•Elimination of superheat (process fouling)
-Latent heat transfer
Flash Recovery / Cascade Systems
•Condensate from higher pressure system
sent to steam trap(s).
•Traps discharge into a vessel that is regulated
at a pressure slightly above the lower pressure
steam system.
•The portion of the condensate that “flashes”
into steam is recovered into the lower pressure
system.
•Lower pressure system requirements not met
by the flash recovery / cascade system are
supplied through supplemental let down and /
or lower pressure steam production.
•This allows for multiple uses of each pound of
generated steam
Flash Recovery / Cascade Systems
Load /
Load
PPH /
PPH
100,000
100,000
100,000
100,000
100,000
100,000
100,000
Primary
Primary
Pressure
Pressure
100
100
50
50
20
20
600
600
150
150
Value
Secondary % of Flash PPH Flash Steam
Secondary
of Flash PPH
Flash Steam
Pressure %Steam
Steam
Cost
Pressure
50 Steam
4.58% Steam
4577.4 $Cost
8.89
50
4.58%
4577.4 $ 8.89
20
4.24%
4239.5
20
4.24%
4239.5 $ 8.89
0
4.88%
4883.4
0
4.88%
4883.4 $ 8.89
150
15.89%
15885.9 $ 8.89
150
15.89%
15885.9 $ 8.89
15
16.33%
16329.9
15
16.33%
16329.9 $ 8.89
Hourly
Hourly
Savings
$Savings
40.69
40.69
$ 37.69
37.69
$ 43.41
$ 43.41
$ 141.23
141.23
$ 145.17
$ 145.17
Annual Savings
Annual
Savings
$ 356,471.43
356,471.43
$ 330,157.00
330,157.00
$ 380,301.61
$ 380,301.61
$ 1,237,136.70
1,237,136.70
$ 1,271,713.82
$ 1,271,713.82
Steam Trapping
Where:
-Every 100-150’, before rise, after fall, before control valve, at
end of line, at steam using process equipment as appropriate.
Why:
-Condensate removal / maximum Btu latent heat per pound of
steam
-Reliability (hydraulic shock, cutting valves / components)
-System Start Up
Steam Trapping – Trap Efficiency
Steam
Use/HR
$/1K
Annual $ Population
Total $
Difference
0.30
$ 23.36
$
23,363
1.72
$ 133.95
$
133,947
$
110,584
2.53
$ 197.03
$
197,027
$
173,664
2.60
$ 202.48
$
202,479
$
179,116
$ 263.22
$
263,222
$
239,859
3.52
$ 274.12
$
274,125
$
250,762
4.14
$ 322.41
$
322,408
$
299,045
4.77
$ 371.47
$
371,470
$
348,108
3.38
$8.89
1000
-
Steam Trap Management
Total Trap Population
Good
Blocked
Low Temperature
Blowing
Leaking
Not in Service
Other
100.0%
59.8%
4.7%
4.9%
2.4% $
11.1% $
16.7%
0.4%
1,835.19
495.52
-
Steam Leak Detection & Repair
100 PSIG Steam / 100 PSID
Hole Diameter x
.7 Disch Coeff
1
7/8
3/4
5/8
1/2
3/8
1/4
1/8
1/16
1/32
PPH Steam
Loss
4411.1
3377.3
2481.3
1723.1
1102.8
620.3
275.7
68.9
17.2
4.3
$/1K LBS
$
8.89
$
8.89
$
8.89
$
8.89
$
8.89
$
8.89
$
8.89
$
8.89
$
8.89
$
8.89
Annual Loss
$ 343,520.59
$ 263,011.97
$ 193,234.71
$ 134,188.82
$ 85,882.09
$ 48,306.73
$ 21,470.52
$ 5,365.68
$ 1,339.47
$
334.87
Air Venting
Removal of entrained air or inert gasses.
- Insulator / inefficient heat transfer medium
- % by volume leads to reduced BTU availability
Tell-tale
-Temperature reduction
Secondary Benefits
-Reduction of probability of hydraulic shock
-Reduction of temperature stratification (process)
Steam Using Process Equipment
High Pressure Process
Use
Med. Pressure Process
Use
Separation
-Steam Quality
-Efficiency
Low Pressure Process
Use
•Use the lowest pressure that will meet the process needs.
Pressure
0
15
50
100
150
300
600
900
1500
2100
Saturation
Temperature
212
250
298
338
366
422
489
534
598
644
Sensible
Heat
180
218
267
309
339
399
475
529
614
685
Latent Heat
970
946
912
880
857
805
728
667
556
444
Total Heat
1150
1164
1179
1189
1196
1204
1203
1196
1170
1129
Steam Using Process Equipment
High Pressure Process
Use
Med. Pressure Process
Use
Separation
-Steam Quality
-Efficiency
Low Pressure Process
Use
•Use of saturated steam for process heat exchange.
Properties of 100 PSIG Steam
Saturated Steam Temperature / °F
Latent Heat of Steam / Btu per LB
Specific Enthalpy of Saturated Steam / Btu per LB
Specific Enthalpy of Saturated Water / Btu per LB
337.9
880.704
1189.728
309.024
Superheated Steam Temperature / °F (+50°F)
Latent Heat of Steam / Btu per LB
Specific Enthalpy of Superheated Steam / Btu per LB
Specific Enthalpy of Saturated Water / Btu per LB
387.9
880.704
1218.616
309.024
•50°F of superheat results in an additional 29 Btu per LB, or .58 Btu
per degree of temperature.
•The process has to shed temperature (at .58 Btu per degree) before it
gets to the point of latent heat transfer by condensing at saturation
temperature.
Steam Using Process Equipment
High Pressure Process
Use
Med. Pressure Process
Use
Separation
-Steam Quality
-Efficiency
Low Pressure Process
Use
•Complete condensate drainage of heat exchange
equipment
-Steam Trap
-Other condensate drainage method
Steam Tracing
Med. Pressure Tracing
Low Pressure Tracing
•Seasonal isolation of manifolds.
-Automated drainage scheme
•Installation best practices to ensure maximum heat
transfer.
-Insulated, heat transfer cement, no air gaps
•Pay attention to ΔP across traps.
-Follow maximum tracing run guidelines
•Sensible heat for low demand / non-critical tracing.
-Instrument & instrument enclosures
•Segment Tracing Application Specifications Based on
Criticality.
Atmospheric Flash Tanks / Flash Condensing
•Every Btu counts
-“Waste Heat” vs. pre-heat of BFW, freeze protection
-Reduced flash venting
-More warm condensate returned for reuse
•Wrapped tubing, pipe in pipe heat exchanger, plate &
frame HX
Condensate Recovery
Rule of Thumb Best Practice:
• Minimum 7 turns of BFW, 13% Make-up
• Recovery of water, treatment costs, sensible heat value
coupled with cost avoidance (sewage / treatment).
How
• ΔP as motive
• Local vented receiver with electric or secondary motive
pressure pumps
Condensate Recovery - Value
PPH Steam Produced
Pressure
Temperature
Btu/LB Sensible
Btu/LB Latent
Inlet H2O Temperature
H2O Btu/LB Sensible
500,000.00
100.00
337.90
309.02
880.70
40.00
8.00
500,000.00
100.00
337.90
309.02
880.70
100.00
68.00
500,000.00
100.00
337.90
309.02
880.70
190.00
158.00
Additional Sensible Required, Btu/LB
Additional Required x PPH
Cost / MM Btu
Additional Costs (H2O, Treatment,…)
Cost
301.02
241.02
151.02
150,512,000.00 120,512,000.00 75,512,000.00
4.82
4.82
4.82
1.07
1.07
1.07
$
886.52 $
709.82 $
444.77
Savings / HR
Savings / Year
$
$
-
$
176.70
$ 1,547,892.00
$
441.75
$ 3,869,730.00
Condensate Recovery - Value
Steam Value / Per 1K LB
Condensate Value / Per 1K LB
8.89
BTU Value (172 Btu/LB)
Water
Chemical Treatment (Initial x .5)
Sewer
Total (without F / I / P)
0.83
0.64
0.03
0.38
1.87
21%
Next Steps
Flash
Recovery /
Cascade
Systems
Take Action on Previously Identified Opportunities
Air Venting
Steam Traps Distribution Drain Traps
High Pressure
Process Use
Pressure
Let Down
Steam System Audit
Med. Pressure
Process Use
Med. Pressure
Tracing
Insulation
Separation
-Steam
Quality
-Efficiency
-Leak Survey
Low Pressure
Tracing
-Insulation Survey
Atmospheric Flash
Tank for Condensate
Recovery
Local Atmospheric Flash Tank
for Condensate Recovery w/
Condensate Pumping
Steam
Generation
-Information “White Space”
Process Audit
Steam Trap Survey
Identify Low Hanging Fruit
Identify Costs / Losses / ROI
Prioritize
Act
Low Pressure
Process Use
Condensate Pumping
Make Up
Water
Questions
Flash
Recovery /
Cascade
Systems
Air Venting
Steam Traps Distribution Drain Traps
High Pressure
Process Use
Pressure
Let Down
Med. Pressure
Process Use
Med. Pressure
Tracing
Insulation
Separation
-Steam
Quality
-Efficiency
Low Pressure
Tracing
Low Pressure
Process Use
Atmospheric Flash
Tank for Condensate
Recovery
Local Atmospheric Flash Tank
for Condensate Recovery w/
Condensate Pumping
Steam
Generation
Condensate Pumping
Make Up
Water