Industrial steam boiler optimization
Presenter: Steve Connor
September 22, 2015 in Brookfield
September 23, 2015 in Appleton
SeventhwaveG175
Industrial steam boiler optimizationIND203
Steve Connor9/22/2015 and 9/23/2015
Credit(s) earned on completion of this course will be reported to AIA CES for AIA members. Certificates of Completion for both AIA members and non-AIA members are available upon request.
This course is registered with AIA CESfor continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner ofhandling, using, distributing, or dealing in any material or product._______________________________________
Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.
Review thermodynamics and the chemistry of combustion including optimization, heat generation
control and pollutant mitigation. Then various types of high pressure steam boilers will be explored
along with their suitable applications. We’ll get you up to speed on current burner designs and
burner management and combustion control systems. Various accessories and systems that support
boilers and their connected components including water treatment and heat recovery options will be
scrutinized. We’llexplain where parasitic losses can be found, contained or eliminated, as well as
good maintenance practices such as checking essential boiler safeties.
CourseDescription
LearningObjectives
DISCUSS various types of boilers and how to achieve safe, low emitting and efficient operations.
EXPLAIN the latest in burner design including the burner management system and corresponding combustion control systems.
IDENTIFY parasitic losses along with water treatment and heat recovery options.
DESCRIBE best practices for boiler maintenance for achieving improved efficiency, sustainability, reliability and safety.
At the end of the this course, participants will be able to:
GBCI cannot guarantee that course sessions will be
delivered to you as submitted to GBCI. However, any
course found to be in violation of the standards of the
program, or otherwise contrary to the mission of GBCI,
shall be removed. Your course evaluations will help us
uphold these standards..
Approval date:
Course ID: '0920004019
Industrial steam boiler optimization
by Seventhwave
06/17/2015
Approved for:
6General CE hours
Industrial steam boiler optimization
Presented by: Steve Connor
September 22 | Brookfield, WI
September 23 | Appleton, WI
Water inletTo drain
To drain
Total Boiler Room
What is the cost of steam?
NOTE:• 45% of fuel burned by Mfr’s = Steam• $18 billion/yr spent• 20% saved = $4 billion
100 %
of fuel
cost
Boiler
Radiation losses
Stack
2 %
20.0%
Boiler
Room
Radiation, condensate tank
Heating of combustion air
Condensate not returned
Heating of make up water
Boiler blowdown1.3 %
0.2 %
0.3 %
1.2 %
0.2 %
Plant
Steam leaks,
Bad steam traps
Radiation, valves, piping0.5 To 4.0 %
Up To 10 %
Useful BTU’s60.8 To 73.3 %
What Affects Plant Efficiency?
Biggest loss area
Thermodynamics, 1st & 2nd Laws
The First Law of Thermodynamics…Heat can be convertedto mechanical power.
Motive force
Boiler Evolution
Steam Locomotive Cut-A-Way
Furnace
Convection tubes
Steam dome
Tube sheet
Stack
Water line
NOTE:
These boilers were an integral part in leading the way in the industrial
revolution starting in the 1860’s.
• 100 Tons
• 100 MPH
Boiler Evolution
Titanic Titanic Boiler Room
NOTE:
The Titanic was powered by 29 firetube boilers that contained 159furnaces which were fired with 825 tons of coal per day.
• 4/14/12
• 3400 passengers
• 1517 lost
Titanic’s Steam Engines
• Discovered 13,000 feet deep
• 2.5 miles down…
4 Cylinder Steam Engines, 215# Saturated
The Second law of Thermodynamics
Heat Transfer
Thermodynamic Principles
What is Thermal Energy and Heat?
• Potential• Kinetic
Two States of Heat
• Sensible heat is potential energy in the form of thermal energy.
– When the heat is applied (work) the state stays the same until….
Second State of Heat
Latent heat comprises the Btu’s involved in phase change. It’s the usable energy.
Motive force & Usable heat
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
Steam - Basic Concepts
1 lb water
at 338O F
1 lb
steam at 338O F
1 lb water
at 200O F
Saturated Steam Table
Pressure
(psig)0 10 80 100
Saturation
Temp212 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
0.017
Start @ 32 deg. F
Three Types of Efficiency
• Combustion
• Thermal
• FTSE
21
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.
933.2
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 & Pressure
Every 10 degree drop = 1% Efficiency loss
Methods of Heat Transfer
Radiation
Conduction
Convection
Water tube boiler
Air &
Fuel
The Radiant Area in the Furnace
Watertube boiler
The Radiant Area in the Furnace
Firetube boiler
Radiant & Convective Heat Transfer
26
Radiant Furnace Convection heat transfer
Furnace Emissivity & Heat Release
Radiant
BTU/Ft3
Stefan’s Law:• Emitted power /unit area in watts/square meter (M)
• Thermodynamic temp. in Kelvin value (T)
M = T 4
Greater temperature difference by the power of 4!
27
Emissivity
Engineering Analysis
Plain Furnace Corrugated Furnace
No difference in efficiency, durability or life expectancy
28
Mean metal temperature exceeding linear thermal limits is a factor
Heating Surface
Radiant
Convective• Reynolds number: . Relation of viscous to inertia forces. Velocity = square root of temperature. <2000 = laminar or viscous. >4000 = turbulent
• Heat Transfer Coefficient:. Proportionality between heat flow & Delta T
29
Firetube Shell & Tubesheets
• Horizontal and longitudinal• Stay braces• Tube sheets• Varying diameters• Furnace & tubes
Firetube Shell and Tubesheets
• Manway• Connections
Conduction
Conduction
Convection
Convection
• Turbulence• Laminar flow• Velocity
Combustion
• Mixer• Turbulator• Igniter
Combustion
Fuels react with oxygen in the air to produce heat.
– Hydrocarbons; Carbon and hydrogen.
• Forms Carbon dioxide (CO2) and Water (H2O) from the reactants.
Natural Gas:
CH4 + 2O2 => CO2 + 2H2O
Reactants => Products + Heat
Heating Value of Common Gas Fuels
• Natural Gas = 1,030 Btu/cu ft or 100,000 Btu/Therm
• Propane = 2,500 Btu/cu ft or 92,500 Btu/gal
• Methane = 1,000 Btu/cu ft
• Landfill gas = 500 Btu/cu ft
• Butane = 3,200 Btu/cu ft or 130,000 Btu/gal
• Methanol = 57,000 Btu/gal
• Ethanol = 76,000 Btu/gal
37
Combustion Gas Constituents
Typical Combustion Graph
37
Combustion
- Mixing
Turbulence
- Temperature
- Contact
Time
Heat
CO2
H2O
CO
NO NO2 SO2
Emission
Gases (sometimes)
S
N2Some
Fuels
C
H2
O2
N2
38
Combustion
• Carbon Monoxide (CO) can be fatal.
39
Combustion
Combustion requires…
• Time
• Temperature
• Turbulance
The Radiant Area in the Furnace
Combustion
Combustion settings will change as weather and ambient conditions vary.
Combustion
• Message?
• Don’t wait for the smoke to appear before you correct combustion problems.
What do I do first when I see this?
Manual gas shutoff valve
Manual Gas shutoff Valve
Emissions
- Mixing
Turbulence
- Temperature
- Contact
Time
Heat
CO2
H2O
CO
NO NO2 SO2
Emission
Gases (sometimes)
S
N2Some
Fuels
C
H2
O2
N2
46
47
NOx Reduction
WHY SHOULD WE CONTROL NOx?
EPA targets specific pollutants for strict regulation– Particulate matter
– Mercury (Hg)
– Carbon monoxide
– Sulfur dioxide
– Lead
– Nitrogen oxides
• Boilers contribute…
What is NOX and how is it created?
Air
– 78 % molecular nitrogen (N2),
– 21 % molecular oxygen (O2)
– 1 % of other gases
NOX
– During combustion process NO and NO2
– NOX is a precursor to ground level ozone (O3)
– Prompt, Thermal & Fuel bound
O3 from 75 ppb to 65-70 ppb proposed
Total NOX
Result is Total NOX
• Natural Gas: Approximately 120 PPM
• #2 Oil: Approximately 180 PPM (FBN .015%)
• #6 Oil: Approximately 425 PPM (FBN 0.3%)
50
Troposphere
51
• Lowest portion of atmosphere
• 80% of atmosphere’s mass and 99% of its water vapor & aerosols
• Approx 10 miles deep
• Where photochemical smog is formed
Los Angeles Smog
WHY SHOULD WE CONTROL NOx?
NO2 Reactants:
– Sunlight (UV) to form ozone (O3) and nitric oxide (NO).
– Other VOC’s combining
– Cycle repeats
– Creating more smog
Short Term Health Concerns
• Ozone attacks lung tissue (sunburn)
• Many areas in the U.S. have enough ground-level ozone to cause immediate health problems
– Shortness of breath
– Chest pain when inhaling deeply
– Wheezing and coughing
– Increased susceptibility to respiratory infections
– Inflammation of the lungs and airways
– Increased risk of asthma attacks
June 2009 “Non attainment” or “Maintenance Areas”
Acid Rain
56
Nitric Acid, HNO3
Defoliant
H2SO4
Sulfuric Acid
250 KPPH BOILER @ 9 PPM
SWIRL AIR VIEW
Prompt NOx
. Forms at lower temperatures (2200 – 2500 Deg. F)
. Reacts with radicals such as Carbon (C) or Methylene (CH2)
Thermal NOx: 2900 Deg.F...Nitrogen
Oxides forming (NO & NO2).
. Temperature and residence time.
What’s happening with burner technology today?
Common NOX Limiting Methods
Advancing Burner Technology
• High Turndown (20:1)
• Low Excess Air
• High combustion efficiency
• Low NOx
• On-line Adjustability
• No refractory throat
The watertube furnace
Providing the motive force for combustion air
Controlling the discharge…
Rotary Gun
Blade
Rotary
IntegralMulti Vane
CFD Burner Design
Looking for Efficiency, Stability, Turndown, Mixing, Staging & Shaping
Center Core
Axial/Tangential, Shaping
Swirl
Three distinct air streams
Directing and turbulating the combustion air…
67
Air
Oil
Mechanical vs Air
Atomizing….
Burner Baffle
High Efficiency & Low NOx, Single Point
Note the linkage controlling the fuel, air and FGR
FGR
Fuel
Air
Burner and Furnace Matching
69
70
L/D = 1.5 L/D = 3
L/D = 5.5
Length to Diameter Ratio
Fuel Injection
Zones
Combustion Air
Zones
·· REDUCES PRODUCTION
Steam Injection
Flame Temperature Profiling
• Staging and shaping of flame
• Matching furnace configuration
• Note cooler temps in early stages to mitigate high heat zone
Flame Contour (Side View)
CFD & FEA Modeling
Stack
4th pass
flue gas
Combustion Air
Inlet
Combustion Air
Fan
Flue Gas &
Combustion Air
Premix
Burner
FGR
79
79
N
O
O
N
O
O
N O
N O
N O
N
O
O
NH
HH N O
NH
HH
O
HH
O
HH
O
HH
N N
N N
Ammonia metering and
dilution skid (anhydrous
shown)
AIG (ammonia
injection grid)
Catalyst
Bed
SCR SYSTEM COMPONENTS
. Anhydrous
. Aqueous
. Urea
Stack gas analysis
Combustion Analysis Basics
The Flue Gas Analyzer
Combustion Analysis Basics
The constituents commonly measured are:
– Oxygen (O2)– Carbon Monoxide (CO)– Carbon Dioxide (CO2)– Exhaust gas temperature– Supplied combustion air temperature– Draft pressure– Nitric Oxide (NO)– Nitrogen Dioxide (NO2)– Sulfur Dioxide (SO2)
It all comes together; A matching…
Boiler Burner
Firetube Boiler & Integral burner
• Integral burner• 4 pass design• Rear door• Davits• Stack outlet position• Velocity
Industrial watertube boiler with matching burner
• Radiant/convection• Drums• Pressure/density
Commercial/ Industrial; matching integral and gun burners
Boiler Controls
• BMS
• CCS
The Burner Management System (BMS)
88
Primary safety controls
HM
O
Primary safety controls
Low Water cutoff
Auxiliary low water cutoff
Flame safeguard - Programmers
Tube type Electro-mechanical
Flame safeguard - Programmers
Solid state
Flame safeguard - Programmers
• Micro-processor• Alpha numeric
OL5
AGOS
28
40
(X2) BMS
GOR(A)(B)
APR APV
OL(X2)
ACMS
B
2
3
40
AR(A)(B)
AAPSGOR
30
CAPS BMSI(2) (3)30
LOPR
3251
GOR
(4) (7)(9) (3)
(9) (6)
6 152 51 7
LOPS (A)(B)44
ACMF
ACMS
Main
PowerSupply
BMF
BMS
Fusible Disc. *
LL1LL2
LL3
GR OHF
OHR
OH
35 36
4CCF-2 BM ACM
LOPR4
L2
CCF-1
CCT
OPM
DISC *
OPMS
(MAN)
POWER SUPPLY
55
374
ALWCO
FFL
LWL
AB
HGPSGOS
R
LDLW
R
AR(3)(9)
AR(6)(9)
17
16
55
17
3
3149
1313
BS
23
23 24OLC HLC
MR
(3) (4)
(2) (1)
66
(4)
(5) (6)
48LWCO
CONN’S FOR
FEED WATERSYSTEM
1111 9 9
MR
LGPS
MR
33
ALOTS
53
1212
ODS
34
HOTS
APR
24
(A)(B)
6
16
5657
5
ALWCO
5
(Note 1)
4
F
G
BRN
WHFD
27 278
21
IT
GOR(1) (7)
GPV
439
2038
OV-2ASMGV-2AS
5050(C) (NC)(NC)(C)5
38
149
1515
B
FVL
W
MGV-1
MGVV
MGV-2
OV-2
OV-1
10
OHROHT
SHV
LOPROHS
77
(CAP)
(CAP)
SHT
46
(9) (6)ON
OFF4554
13
12
14
151919
1818
22
22
43
(B) (B)
(R)
(W) (W)
MFC MC
MAN
AUTO
MAS
41
42
(R)
(T2)
(R)
(T1)
(R/B) (B/B)HFS
LFS(R) (B)
(Y)
(B)
(W)
19
18
2
25
29
21
20
26
Ladder diagramTop
Bottom
Flame Safeguard System Sequence
“The Gate Way” (CB 100E)
• C.C. Power and Modulating motor energized..L1, L2, 10
• Limit line & Low Fire Switch……………………...13,D
• Pre-ignition interlock………………………………….3
• Blower motor & Damper open proof………….....M,X&8
• High fire 30 second timing…………………………..X
• Running interlock circuit (CAPS)………………….P
• Proof of low fire position….…………………………D&12
• Trial for pilot……………………………………………..5
• Flame proving……………………………………………S1,S2
• Main valve energized………….………………………7
• Flame proven…………………………………………….S1,S2
• Pilot and ignition de-energized
• Release to modulation………………………………..11
• Alarms……………………………………………………….A
Complimenting the Flame Safeguard
98
Sensing & Sending Devices
99
RTD
Transducer
Transmitter
Thermistors Thermocouple
Sensing & Sending Devices
100
Water flow meter Steam flow meter
Flow meters measure forces produced by a flowing stream as it overcomes a known constriction to indirectly calculate
flow
The Receivers
Used for enhanced control such as incorporating parallel positioning, O2 Trim, Stack damper modulation, VFD, etc.
Independent Loop Controllers
The Receivers
Integrated with the Flame Safety Control (BMS).
PLC Based Integrated Boiler Controls
103
Loop Controllers vs PLC Platform
Loop Controllers PLC Platform
104
Firing
Rate
Control
Fuel-Air
Ratio
Control
O2
TrimDraft
Control
Economizer
ControlVSD
Control
Requires:
• Multiple Individual devices
• Separate control panel
• Interface wiring for BMS
• Relays and timers
• Extra wiring
• Expert tuning
Multiple Control loops
Lead/Lag
Control
Single Platform for All, Factory Assembled
105
PLC based system
PLC Based Integrated Boiler Controls example
Operator interface
PLC Based Integrated Boiler Controls
108
108
Plant Master
109
• Automatic sequencing
• Automatic boiler
rotation Lead/Lag or
Unison firing
• Better Overall system
efficiency and control
Common Header
Transmitter
Lead – Lag Controller
Common Header
Multi Boiler Lead-Lag Control
PLC Based Integrated Boiler Controls Example
O2 Trim
VFDMod. Stack damper
Fuel/Air Control
Gas Oil Air
Communication And Logging Systems
111
Regional
Local
Natural Gas
OL102679
Auto
Run
155 PSIG
82 %
260
30
Boiler 1
2500
35
28
13” WC
350 F
450 F
280 F
85 F
4 % O2150 PSIG
60 %
EconoIn
180 F
3
338
192 168 1 10
Remote Monitoring On Local Computer
PLC Based Integrated Boiler Controls
• Disadvantage: initial cost
• Advantages:– Expandable and flexible– Ease of use– Connectivity– User/operator features
• HMI interface• Alarm and data reporting with history• Trending and totalizing• Preprogrammed at factory• Open platform architecture
Controlling the Fuel & Air and more…
Air
Fuel
115
• Traditional Jack Shaft • Parallel Positioning• O2 Trim • Variable Speed: Comb. Fan • Draft Control• Feedwater control• Full Metered Control
Fuel Air
Combustion Control And Sub-Systems
Combustion Control System
Next focus areas…
Mod Motor
Firing Rate Signal From Boiler Controls
Fuel Valve
Mechanical Adjustable Cam
Common Shaft and Linkage Connections and Control
FGR valve(If Used)
Combustion Air
116
Single Jack Shaft Control
Approximating the Curve with Step linearization
• Linkage problems• Modulation issue
118
Parallel Positioning: Fuel Air Ratio Control
Fully Metered, Cross Limited Control
Steam Pressure, FRD
• F(x) = Characterizer
• Air characterizes based on fuel flow
• Driven by FRD
119
Characterizer F(x)
Typical Control Scheme2 & 3 Element Control
120
121
Ambient Air
Temp
FUEL
O2
Boiler
Exhaust
Gases
Air
O2 Trim Control
Other variables?
Oxygen Trim
O2 trim is an optimization of the combustion controls.
– Minimizes the amount of air used for combustion.
– Trims fuel or air
– Can be tied into a PLC platform
Necessary all the time?
Efficiency Variance Relative to Excess O2
For every 2% increase in O2, 1% Eff. Loss!
124
Stack DraftTransmitter
Stack Draft Damper
Draft Control
Why is this helpful?
125
Fuel Air Ratio Control w/ VFD
Combustion Fan Variable Speed Control
• Soft start
• Ramp based on frequency manipulation of output (pulse width modulation)Motors last longer.
• Excellent control of air when paired with the combustion air damper in a O2 trim strategy.Damper alone will allow high excess air at low fire.
• HP varies as cube of speed
• Torque varies as a square of speed.
True energy savings when
running below full load and
based on 15 minute utility
averages.
Questions?
• Thermodynamics
• Combustion
• Emissions
• Heat Transfer
• Burners
• BMS
• CCS
Typical Boiler applications…
Typical Industries
• Food
• Dairy
• Beverage
• Pharmaceutical
• Petro Chemical
• Textile
• Pulp & Paper
• Medical
• Automotive
• Computer Technology
• Government
• Schools
• Universities
129
What boiler type do I use?
• Low pressure steam to 15# & up to 160# HW <250 DF
Section IV
• 150# and over & 250 DF & higher
Section I
ASME Code
Firetube Watertube
Firetube, multi-pass
Firetube, 2 pass
Vertical Firetube
Small O type
Flextube
IWT
Steam generator
Vertical, tubeless
Commercial/Industrial Watertubes
• 500 MBH to 16,736 MBH input
– 12 to 500 Hp
• Low pressure steam
– 15 psi
• High Pressure
– Up to 700 psi
• Summer boiler?
• Point of Use boiler?
• Field erected (FLX)
Flex
Small O
Smaller Capacity Firetubes
Horizontal
Vertical
Specifics:
• Packages to 15- 2500 HP
• Design pressures to 350#
• Hot water
• Low pressure steam
• High pressure steam
Firetube boiler
Gun burner
Integral
Advantages:
• Cost effective
• High efficiencies
• Small surge loads
• Holds pressure
• Multiple fuel firing
• Low emission capable
• Excellent access
• More with integral
Firetube boiler, Dryback, Integral burner
• All same Advantages, but…
• No easy front entry to 2nd
pass
Firetube boiler, Dryback, Gun type
Three (3)Tubesheets
Water Leg
12
3
Firetube Boiler, Wetback
138
• Difficult access, 2nd
pass
Rear access plug
Disadvantages
• Horsepower limit (2500)
• DP limit to 350#
• Require large area for maintenance
• Cannot accommodate integrated super heat
• Problem with large swing loads
• Burner turndown normally limited to 10:1
• Lower steam quality (1.5%)
Firetube boiler in general
Dryback
Wetback
Advancing Firetube Designs
Convective & Conductive Heat Transfer
141
Extended Surface TubesPlain Tubes
Convective Heat Transfer
Typical Boiler Tube
142
Boundary layer
Extended Tube Surface
143
No Boundary layer
INCREASED
INERTIA FORCES
=
INCREASED HEAT
TRANSFER
Spiral tubes
Radiant & Convective Heat Transfer
144
Radiant Furnace Convection heat transfer
Heat Transfer
Radiant
Convective & Conductive
• Reynolds number: . Relation of viscous to inertia forces. Velocity = square root of temperature
• Heat Transfer Coefficient:. Proportionality between heat flow & Delta T
145
• Stefan’s Law
Reducing Weight and Footprint
146
• 30% less weight
• 15% less floor space
• Reduced fan motor horsepower
• Same or better efficiency, durability and life
Optimum furnaceImprove convection heat transfer
2 pass
NOTE:
These are attractive features to
architects designing new boiler
rooms when faced with
budget restraints.
Typical:
What about the Watertube boiler?
Industrial Watertube Boilers
Three basic types…
D
OA
“Delta” Design
150
Watertube Boiler, Delta 170,000#/HR Package
275,000 lb/hr unit
“A“ Type
“O” Design
100,000#/HR, 2900 BHP
Flue Gas Sealing
Membrane Construction
Welded or Tangent Tube Design Also Available
Upper Drum
Drum internals
Steam Quality
155
High quality steam, <1/2% moisture
Drum internals
Saturated Steam
150 Psi, 3660 F.
1 ppm dry steam
Superheated Steam
150 Psi, 4660 F.
100 degrees of SH
<1 ppm dry steam
Convection
Section
Furnace
Section
Convection Superheater “D” Style
Why superheat?
Watertube Advantages and Disadvantages
Advantages
• Very large capacities; 650,000#/Hr as a package
• Very high design pressures to 1500#
• HTHW
• Multiple fuel firing
• Low emission capable
• More sophisticated combustion control
• Higher turndown of the burner
• Quick response to load changes
• Excellent for swing loads
• Higher quality steam
• Smaller footprint per HP
• Smaller Space for maintenance
• Lower fan HP
• Integral super heat possible
Disadvantages
• Cost
• Height
• Efficiency w/o Economizer
• No low pressure
Questions?
• Boiler applications
• Steam Boiler types
• Firetube Boiler types & features
• IWT types & features
• FT advantages/disadvantages
• IWT advantages/disadvantages
The Power of Steam!
Motive force
Saturated Steam Table
Pressure
(psig)0 10 80 100
Saturation
Temp212 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
0.017
Do you know the power of steam?
• One (1) pound of water = .017 Ft3• Converted to vapor = 27.0 Ft3 • That’s an expansion of 1600 times!• 100 gallons of water @ 100# = 7,000,000 HP!• Steam catapult for jet launching• Jet = 60,000#• Zero to 165 MPH in 2 seconds!!• A 500 HP Firetube boiler contains 2300 gallons &
weighs 60,000 pounds….
LWCO = 1/4”
Section IV, Heating Boilers, 15 psi - Low
water cutoff point is 0” - 1/4” above top row
of tubes
At 0”= 2”
Section I, High pressure boilers is
first visible point in GG = 2” above
tubes…
• Blowdown water columns
• Blowdown water gauge glass
Top water line
Extra Safety Margin
Furnace
Expansion 1600 times!!
American Society of Power Engineers
173
American Society of Power Engineers
174
American Society of Power Engineers
175
June 18, 2007
Paris, TN
Weighs 6000 pounds!
Most important safety device on a steam boiler…
Requires ultimate attention!
The Low Water Cutoffs are Critical!
176
What do I do first when no water in gauge glass?
Secure the Feedwater Connection!
Questions?
• The power of steam
Water Treatment:
Softeners, Dealkalyzers, RO, Deaerators & Chemical Feed
Water inletTo drain
To drain
Total Boiler Room
Water, A critical problem with all boilers
183
CO2
CO2
CarbonatesIron
CO2
CalciumSulfates
SilicaSodium
Magnesium
Aluminum ChloridesManganese
Fluorides
Na2SO4CaSO4 MgSO4 MgCl2
O2O2
O2
O2
Makeup Water Impurities, Limits and Treatment methods
<150 ppm BSilica
Make-up Water Test Typical Impurities Typical Limits Treatment Method
Blowdown
Deaeration / Chemical
Softener
Blowdown
Chemical
Blowdown / Dealkalizer
Blowdown
<.007 ppm A
<1.0 ppm A
0.15 ppm A
7.0 - 10.5 A
<700 ppm B
<7000 µmho/cm B
10 ppm
6 ppm
86 ppm
O.1 ppm
6.87
100 ppm
500 µmho/cm
Oxygen
Hardness
Suspended Matter
pH
Alkalinity
Dissolved Solids
Water Treatment
A. Limits for feedwater
B. Limits of boiler
Water Hardness Example
• Water hardness varies geographically and locally
– Hardness (calcium & magnesium) causes scale formation
– Measured in ppm as calcium carbonate (caco3) or grains per gallon
– Softeners are sized relative to grains
– For example: 137 ppm of hardness = 8 grains per gallon
• 137 ppm / 17.1 (a conversion constant) = 8 grains of hardness per gallon
Softener Types
• Manual
• Automatic operation
• Time clock
• Water meter
• Single
• Twin or parallel tank construction
Ion Exchange Process Notes
• Pass hard water through a bed of ion exchanger (resin beads)
• Sodium cycle operation is the most common method used
• Softening cycle does not reduce TDS - (Total Dissolved Solids)
Cation Resin Bead Composition
• Chemically engineered polystyrene beads with an affinity or attraction for positive ions.
• Will exchange weaker positive ions for stronger positive ions
– Sodium (Na+) for Calcium (Ca++) and Magnesium (Mg++)
Water Softener Cycles
1. Service
2. Regeneration
A. Backwash
B. Brining
C. Slow Rinse
D. Fast Rinse / Brine Fill
3. Service
Hard Water Soft Water
Cation Exchange Process
• Service cycle– Na+ ions are exchanged for
Ca++ and Mg++ ions
Ca++ & Mg++ Na+
Cation Exchange Process
• Exhausted condition
– Cation beads can be used in the service cycle until they are saturated with Ca++ and Mg++
– Requires regeneration
Ca++ or Mg++
Cation Exchange Process
• Regeneration or Brining
– Sodium Chloride (NaCl) solution (brine) is passed through the resin to drive off the Ca++ and Mg++ ions to be rinsed away with the Cl- ions
• Resin bead will be Ca++ and Mg++ replenished with Na+
Hard Water Soft Water
Cation Exchange Process
• Service cycle
– Na+ ions are exchanged for Ca++ and Mg++ ions
Ca++ & Mg++ Na+
Boiler Room Steam System
Water inlet
Dealkalizer
Filter
90 %Bicarbonate Alkalinity HCO3 No Change
Dissolved Constituent Softener Chloride Cycle Dealkalizer Filters Deaerators
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
To .005 cc/liter of O2
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
Must have soft water
Must have soft water
Must have soft water
No Change
No Change
90 - 95%
Increases
20%
Must have filter
Down to 10
Micron
See Filter
Section
Must be removed
Free CO2 Only
No Change
98 - 100%
98 - 100%
98 - 100%
Increases
No Change
No Change
No Change
No Change
100%
Must be removed
No Change
Calcium Ca
Magnesium Mg
Hardness
Sodium
Total Dissolved Solids
Sulfate SO4
Chloride CI
Silica SiO2
Soluble Iron Fe
Dissolved Gasses
Suspended Solids
Water Treatment
Impurity removal and equipment employed
A. Specifically limited by ASME guidelines on boiler feedwater guidelines.
B. The sum of calcium and magnesium equal the hardness. Hardness has been listed as a separate item for those analysis showing
hardness only
Dealkalizers
Looks the same as a softener!
Dealkalizers
Similar principle as the water softener (Anion Resin +)
Chloride (-) cycle process
Strong anion resin removes negatively charged ions
Replaces bicarbonate, carbonate, sulfate, and (some) silica with chloride ions
Dealkalizer Cycles
1. Service
2. Regeneration
A. Backwash
B. Brining
C. Slow Rinse
D. Fast Rinse / Brine Fill
3. Service
Alkaline Water Dealkalized Water
Anion Exchange Process
• Service cycle
– Chloride (Cl-) ions are exchanged for Carbonates of Alkalinity (-)
Alkalinity Cl -
Anion Exchange Process
• Exhausted condition
– Anion beads (+) can be used in the service cycle until they are saturated with Alkalinity (-)
– Requires regeneration with Chlorides, also (-)
Alkalinity
Anion Exchange Process
• Regeneration or Brining
– Chloride ions are passed through the resin to drive off the Carbonates of Alkalinity to be washed away during the rinsing process.
• Resin bead will be replenished with Cl-
Alkalinity Cl-
Alkaline Water Dealkaline Water
Anion Exchange Process
• Service cycle
– Carbonates of alkalinity are exchanged for chloride ions (Cl-)
Alkaline Cl-
Chlorides an issue?
Why is a Dealkalizer used?
What are cycles of concentration?
And…
Dealkalizer
800 horsepower boiler…….27,790# of water
Dissolved salts Actual Limits **Cycles %
alkalinity 60 600 10 10
silica 4 150 38 2.6
Fires @ 75% or 600hp = 20,700#/hr
20,700 x *152 (212-60) Btu/hr = 3,146,400
3,146,400 x 10% BD = 314,640 Btu/.80 = 393,300 Btu input
393,300/100,000 Btu = 3.9 therms x .55 = $2.16/hr lost
$2.16 x 4000 hrs = $8653 per year lost! * NOTE: Conditions are 60 deg. feedwater and zero gauge pressure, 212 Deg. F
** Always solve for the lowest number of cycles.
DealkalizerNEXT LOWEST DISSOLVED SALT….
Silica = 38 cycles or 2.6% blowdown req’d (4/150)
3,146,400 x .026 = 81,806/.80 = 102,258/100,000/therm =
1 therm x .55 = $.55/hr x 4000 hrs = $2200/yr lost.
Cost: Without Dealkalizer = $8653
With Dealkalizer = $2200
$ Difference = $6453/YR
Does it Pay?
206
Dealkalizer & RO Systems
Removes:
. Sodium
. Alkalinity
. Sulfate
. Silica
. Nitrate
. Iron
. Chlorides
What’s the difference?
Deaeration
The process of removing air and gases
from boiler feedwater prior to its
introduction to a boiler.
Handbook of Power, Utility and Boiler Terms and Phrases, Sixth Edition, Edited by the American Boiler Manufacturers
Association, ©1992
90 %Bicarbonate Alkalinity HCO3 No Change
Dissolved Constituent Softener Chloride Cycle Dealkalizer Filters Deaerators
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
To .005 cc/liter of O2
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
Must have soft water
Must have soft water
Must have soft water
No Change
No Change
90 - 95%
Increases
20%
Must have soft water
Down to 10
Micron
See Filter
Section
Must be removed
Free CO2 not converted
to bicarbonate by the pH
No Change
98 - 100%
98 - 100%
98 - 100%
Increases
No Change
No Change
No Change
No Change
100%
Must be removed
No Change
Calcium Ca
Magnesium Mg
Hardness
Sodium
Total Dissolved Solids
Sulfate SO4
Chloride CI
Silica SiO2
Soluble Iron Fe
Dissolved Gasses
Suspended Solids
Water Treatment
Impurity removal and equipment employed
A. Specifically limited by ASME guidelines on boiler feedwater guidelines.
B. The sum of calcium and magnesium equal the hardness. Hardness has been listed as a separate item for those analysis showing
hardness only
The Steam System
Courtesy:http://www.energysolutionscenter.org/boilerburner/Eff_Improve/Images/STEAMLOOP.JPG
Courtesy:www.agen.ufl.edu/.../lect/lect_20/lect_20.htm
•Steam system generates,
distributes, consumes and
returns
•Just like the body, the
boiler is the heart, but
needs nonaggressive water
just like the body needs
oxygenated blood.
Heart of the Steam System
Courtesy:http://www.agen.ufl.edu/~chyn/age2062/lect/lect_20/30_03.GIF
Filter of the Steam System
Liver
Its about the Water…
H2O
213
CO2
CarbonatesIron
CalciumSulfates
SilicaSodium
Magnesium
Aluminum ChloridesManganese
Fluorides
Na2SO4CaSO4 MgSO4 MgCl2
O2
O2
O2
O2
CO2
CO2
O2 CO2
Oxygen – Friend or Foe?
O2
215
Dissolved Gasses
What are the bubbles?
216
Dissolved Gasses
Dissolved Gasses
Deaeration is:
. Heating
. Agitating
. Liberating
Oxygen Corrosion
Fe + 2H2O = Fe(OH)
2+ 2H
+
Iron + Water = Ferrous Hydroxide + Hydrogen
• Iron begins to dissolve when in contact with water (Rust)
• No more water, reaction stops
Oxygen Corrosion
4Fe(OH)2
+O2
+H2O= 4Fe(OH)
3
Ferrous Hydroxide + Oxygen + Water = Ferric Hydroxide
(Corrosion & Pitting)
• Now add in Dissolved O2
• Process continues until 1 of 2 things occurs
1. No more Dissolved O2
2. No more Iron Fe
Dissolved Oxygen Content in Water
Feed Water Typical Range (ppb)
50 F 12,000 - 20,000
125 F 3,000 - 5,000
180 F 2,000 - 3,000 (3 PPM)
200 F 1,000 - 2,000
212 F 1,000
.03 Deaerator 44 ppb (.03 cc/liter)
.005 Deaerator 7 ppb (.005 cc/liter)
Modern deaerators reduce dissolved Oxygen content by nearly 3000 times.
Solubility of Oxygen
10
0
2
4
6
8
21019017015013011090705030
Ox
yg
en
Co
nte
nt,
pp
m
Temperature, Degree F.
Managing Oxygen
Raise the Temperature,
Agitate, Liberate!
O2
Oxygen 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
Carbon Dioxide – Friend or Foe?
CO2
Corrosion – Carbon Dioxide
Dissolves in Cooler Condensate-Combines with Water to Create Carbonic Acid
CO2
+ H2O = H
2CO
3
Creation of CO2 from
Carbonates
Courtesy:http://www.spiraxsarco.com/resources/steam-engineering-tutorials/the-boiler-house/water-treatment-storage-and-blowdown-for-steam-
boilers.asp
Carbon Dioxide & Oxygen
CO2
Carbon Dioxide together with Dissolved
Oxygen is 40 percent more corrosive than if
the two were acting alone.
O2
Managing Carbon Dioxide
What Else do we need to be aware
of with our condensate?
CO2
Manage pH
CO2
Neutralizing the carbonic acid
Carbon Dioxide & Oxygen
How do I get rid of the corrosive gasses?
. Chemically
. Mechanically
Carbon Dioxide & Oxygen
DA versus Condensate Tank
Compare the Choices...
• Deaerator Pressurized = 5 psig
ASME code vessel
More expensive initial purchase
Less chemical use
Oxygen Concentration– 7 ppb
Higher feed water temperatures
Designed to manage flash
Longest Boiler Life
Vessel Life equals Boiler
• Boiler Feed System Vented = 0 psig
Non-code vessel
Less expensive initial purchase
More chemicals
Oxygen Concentration– 1000 - 3000 ppb
Limited to 212 F feedwater temperature
Results in flash steam loss
Shortest Boiler Life
Likely Tank Replacement
What About Pumping?
• On-Off?
• Modulating?
Selecting a Feed Water Control
• Modulating Feed Slightly more complex More expensive due to more
components Maintains nearly constant water
level in boiler Lessens possibility of thermal
shock Feeds water to boiler on
continuous basis in linear demand method
Permits flexibility with pump selection in multiple boiler installation
• Intermittent (On-Off) Simple
Less expensive initial purchase
Boiler water level will rise and fall
Sends slugs of feedwater intermittently to the boiler
Can contribute to thermal shock
Generally one pump per boiler
Causes unstable and cyclic load on DA
Primary Functions of a DA
1. Remove Dissolved Gases
2. Pre-heat Boiler feed water
3. Store Heated Feedwater & Recover Condensate
When to Consider DA’s…
• Boiler Plants operating over 50 psig
• Boiler Plants with Limited Standby Capacity
• Boiler Plants where Production Relies on Continuous Boiler Operation
• Boiler Plants with over 25% Makeup
Why Capture the Condensate?
The Condensate System
Courtesy:http://www.energysolutionscenter.org/boilerburner/Eff_Improve/Images/STEAMLOOP.JPG
Courtesy:www.agen.ufl.edu/.../lect/lect_20/lect_20.htm
Saturated Steam Table
Pressure
(psig)0 10 80 100
Saturation
Temp212 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
What is the cost of steam?
Returning Condensate
Energy Calculation (Example)– Average steam flow – ( (~1300 HP)
– Cost per MBTU at the plant
– Operation (24 hours /7 day per week)
– Operating steam pressure:
• 150 psig
• Steam total energy (hg) 1195.1
• Makeup water temperature 55ºF (13ºC)
• Makeup water BTU content hm) Btu (Based on 32 degree water)
– Condensate return temperature 212ºF (100ºC)
• BTU content of the condensate being returned (hc) Btu
Condensate returning to the boiler plant
8760 hours per year of operation
39,600 Lbs of steam 157.33 BTU/lb 6,230,268 BTUs $15.00 per MBTU $93.45 per hour cost
$93.45 per hour cost $818,622 per year
hc Energy Loss per lbhm 157.33 BTU per lb23
44,000 lbs of steam 44,000 lbs of condensate (90% return) 39,600 lbs
44,000 lbs of steam
$15.00 per MBTU = 1000#/HR.
8760 hours per year of operation
23
180.33
180.3
Packed Column Deaerator
Spray Deaerator
Heat Exchange Machine
• Components sized for a set of system parameters
• Components each have a specific function
• Parameters must be within limits to maintain heat exchange
244
MUWV and Steam Control Valve (PRV)
• Sized based on system conditions• Water and steam at balanced flows• Operate independently
245
Load Increases demand
MUWV opens
Water sprayed into collector cone
246
Steam Control Valve Reaction
Steam PRV opens to maintain set pressure
Steam atomizing valve sprays steam into lower baffles
247
Tray Deaerator
steam
Water
Single Tank Deaerator; Spray
251
Duo End-to-End
Common Skid
Duo Combo
Space and Cost considerations
Duo Piggy Back
Duo Vertical Surge
Space and NPSH
Controls - Electronic
Controls - Electronic
Summary – DA Benefits
1. Improve Equipment Life
2. Reduce replacement costs for corroded piping and tanks.
3. Lower Maintenance costs
4. Lower Total Cost of Operation
5. Improve boiler efficiency
Water inletTo drain
To drain
Total Boiler Room
Chemical Feed Tank
259
• Phosphonates
• Polymers
• Sulfite
• Non-sulfite scavengers
• Chelant
• Amines (neutralizing & filming)
Mixing and Dispensing
Questions?
• Water softeners
• Dealkalizers
• RO
• Deaerators
• Chemical feed
Capturing Parasitic Losses
Efficiency is a MAJOR Driver…
100 %
of fuel
cost
Boiler
Radiation losses
Stack
2 %
20.0%
Boiler
Room
Radiation, condensate tank
Heating of combustion air
Condensate not returned
Heating of make up water
Boiler blowdown1.3 %
0.2 %
0.3 %
1.2 %
0.2 %
Plant
Steam leaks,
Bad steam traps
Radiation, valves, piping0.5 To 4.0 %
Up To 10 %
Useful BTU’s60.8 To 73.3 %
What Affects Plant Efficiency?
Biggest loss area
Water inletTo drain
To drain
Total Boiler Room
Parasitic Losses
Where is the low hanging fruit causing us fuel dollar waste?
They’re here…
• Radiant Heat (vessel)
• Reduced Heat Transfer Ability
• Stack Losses
• Blowdown Losses
• Steam & condensate losses
• Electrical energy losses
• Poor combustion control
How Do We Capture Them?
• Vessel and Piping Insulation
• Plug steam leaks
• Fix bad traps
• Proper Combustion Settings
• BD heat recovery
• Return condensate
• Flash Steam Recovery
• Draft Control
• Stack Economizers
• Proper Water Treatment
• VFD – Variable Speed Drives
• Parallel Positioning
Vessel and Piping Insulation
– Boiler: Done at the mfg. facility.
– Replace or repair
– NOT doors.
Piping & Equipment Insulation
Bad
Good Good
Bad
268
Energy Lost Through Uninsulated Pipe
• 6” Steam Pipe @ 100 psig (338 Deg. F)
• Radiates approx. 1650 Btu/HR/Foot
• Figure 500 feet of uninsulated pipe
• Equals 826,000 Btu/HR (25 BHP)
• Production hours per year = 4000 HR’s
• At $0.65per therm for natural gas = $21,476 WASTED!
• Annual fuel bill is $500,000/YR = 5%
269
Steam Leaks
270
I don’t have
the time.
Been going on
forever!
Dollars/Year at 100 Psig
Equivalent
Orifice
Diameter
1/16”
1/8”
1/4”
1/2”
Lbs./Yr.
Steam
Loss
115,630
462,545
1,848,389
7,393,432
Steam Cost Per 1000 Lbs.
$5.00 $7.50 $10.00
$578 $867 $1,156
$2,313 $3,469 $4,625
$9,242 $13,863 $18,484
$36,967 $55,451 $73,934
Cost Multipliers For Other Steam Pressures:
16 Psig -. 26 50 Psig - .56 150 Psig - 1.43
200 Psig - 1.87 300 Psig - 2.74 600 Psig - 5.35
271
Cost of Steam Leaks
Proper Combustion Settings
• Regular flue gas analysis will verifythat the boiler is running as it was setup.
– If you do not have your own fluegas analyzer, bring in a technicianto do the job.
Ambient air temperature, humidity and barometric pressure will all
effect combustion.
Have it reset at least 2 x/yr.
Proper Combustion Settings
What to look for:
– CO or Carbon Monoxide
• Should be less than 200 ppm
– O2 or Excess Air Levels
• Will differ based on burner type and firing rate
– NOx or Nitrogen Oxides
• Lower NOx number will mean higher O2 numbers
– Well tuned: 50 – 100 deg. F above saturation temperature
– Soot and scale will cause temperature to rise
Draft Control
When draft remains constant, combustion is more complete and fuelefficient.
– Barometric pressure, temperature and wind velocity can cause changes in draft pressure.
Draft Control
A packaged boiler designed for pressurized firing requires no assistance from a stack for the combustion process.
– However, variance in stack pressures can cause significant problems with combustion.
Economizers
• Standard (non condensing)
• Condensing
277
Economizers
Standard (non condensing) economizers
– Capture sensible heat
• Typically 100oF = 2.5% efficiency gain
• Preheat boiler feed water
Economizers
Condensing economizers
Capture sensible heat
Typically 100oF = 2.5% efficiency gain
Preheat boiler feed water
Capture latent heat
970 BTU/lb of water
Condensing begins at ~ 130oF (nat. gas)
Require cold liquid stream to condense
Adds ~ 2.5-7.5% efficiency gain
Total efficiency gain ~ 5 – 10%
Economizers
Condensing economizers
– How it works
Cold Liquid
400oF
<130o
F
Economizer
Upper Coils
Economizer
Lower Coils
300oF
Boiler
Deaerator
To CIP tank
Economizers
Condensing economizer applications:
– Preheating boiler feed water
– Preheating other liquids
• Process water
• Wash water (CIP)
• Domestic Hot Water
Rule of Thumb:
>25% Make-Up Water
Good Condensing
Application
Blowdown Heat Recovery
Continuous Blowdown System
– Heats boiler water make-up
– Reduces temperature of blowdown
– Increases boiler efficiency
Hot BD from boiler(s)
281
Cold make-up water
Fuel $avings
Continuous Blowdown– Every 10 degrees save 1%
– Fuel bill $500,000/yr
– A 10 degree pickup is $5000/yr
– A 20 degree pickup is $10,000/yr
282
Effluent down the drain…
• Make-up Water (10 deg. F increase = 1% loss)
• Fuel / Energy (sensible)
• Chemicals
T
T
T
T
T
H P Condensate Return
Cond. Pump
D A TankD A Tank
Feed PumpBoiler
Strainer
Trap Trap
Trap TrapTT
TT
TT
TT
TTT
HP SteamPRV
15 psig
250 F
LP Steam175 psig366 F
TrapMotive
Force
Feed Tank
Condensate Recovery
Condensate Transfer Tanks
• Standard models 200°F or less
• Available (Low NPSH pump(s)
• 212°F elevated units available
Steam Powered Pump Trap
Open Check
Valve
Steam/Air In - Closed Steam/Air Out - Open
Closed Check
Valve
High Pressure vs Vented Condensate Receiver
• Condensate directly from the user.
• No need to deaerate.
• Pump directly into boiler from HPR
• Feed the HPR from the DA
Vented tank
HPCR
DA VR
Boiler
17.8%
flash
loss thru
vent
8220 pph
recovered
then
1463#
lost!
raw water
50oF
180
psig
380oF
353 Btu
6 psig
230oF
0
psig
212oF
180
Btu
180 psig
212oFBoiler
%Flash: [(SH-SL) / LHL X 100](353 – 180 = 173/970 = 17.8%)
Return to Pressurized Receiver
HPCR DABoiler
8220 pph
recoveredraw water
50oF
6 psig
230oF
180 psig
180 psig
380oF
100 psig
338oF
Save 1463#/HR @ $15.00/1000# X 8760 = $192,238 $/YR!
T
T
T
T
T
H P Condensate Return
Cond. Pump
D A TankD A Tank
Feed PumpBoiler
Strainer
Trap Trap
Trap TrapTT
TT
TT
TT
TTT
HP SteamPRV
15 psig
250 F
LP Steam150 psig366 F
TrapMotive
Force
Flash Tank
Feed Tank or
DA
Flash Steam
Flash Steam Recovery
Must be continuous!
(%Flash: [(SH-SL) / LHL X 100])
291
Flash tank only Flash tank w/ HR
Wasted Steam Energy
Flash Tank Economizer
• Recover blowdown energy(latent and sensible heat)
• Flash steam (18% in previous example)
• Low Pressure use
• Condensate is returned or if TDS control, cooled before discharge (per code)
• Used for single or multiple boilers
• Needs to be constant, not modulating…
VFD – Variable Speed Drives
VFD’s reduce excess air during combustion, saving energy, both fueland electrical.
Example :. Speed reduced by 20%
51% HP Red.
64% Torque Red.
NOTE:
HP is cube function of speed
Torque is a square function
Parallel Positioning
Greatly improves air to fuel ratios…
Single point
Parallel positioning
296
Excess Air Increases As The Firing Rate Decreases
“Sweet Spot”
As Excess Air Increases, Efficiency Decreases
297
Lose 1% in EfficiencyFor every 2% increase in
O2!
What’s the Difference between Steam QUALITY and PURITY?
298
Steam Nozzle Sizing & Velocity
299
Steam nozzle
Steam header valve
Water Surface
• Surface velocity: 10’/sec.
• Nozzle: 5000’/min.
T
T
T
T
T
H P Condensate Return
Cond. Pump
D A TankD A Tank
Feed PumpBoiler
Strainer
Trap Trap
Trap TrapTT
TT
DA
Tank
TT
TT
TTT
HP SteamPRV
15 psig
250 F
LP Steam
150 psig
366 F
TrapMotive
Force
Velocity in Piping
Steam & Condensate Velocity
Typical Velocities in steam systems:
Process Piping 6000 – 8000 fpm (68 – 91 MPH)
(70 – 90 MPH)
LP Heating Systems 4000 – 6000 fpm (45 – 68 MPH)
Typical Velocities in Condensate return systems
Liquid 180 – 420 fpm
Bi-phase Approx. 3000 fpm
302
High Steam Velocities cause:
– High Pressure Drop
– Erosion
– Noise
– Enhance water hammer
Steam Velocity/Pressure Drop
303
Calculation of Steam Velocities
V (fpm) =2.4 x W(lb /hr) x v(cu ft/lb)
A (sq in)
Velocity =2.4 x Flow x Specific Volume
Cross Sectional Area
304
Pipe Size
Sch 40 ID
Velocity
fpm
Velocity
mph
Press Drop
psi / 100 ft
3/4”
1”
1-1/4”
1-1/2”
2”
17,580
10,830
6,250
4,600
2,780
190
120
70
50
30
87.0
25.0
6.0
2.7
0.7
1000 lb/hr Steam Flow at 100 psig
Remember the Velocity and Delta P relationship!
Cause & Effect of Water Hammer
Three Types of Water Hammer:
Hydraulic
Thermal
Differential
Water Hammer in Steam or Condensate Lines
– Hydraulic shock• Quick closing valves
– Thermal shock• In bi-phase condensate line, steam condensing; vacuum forms.
– Branch or tracer lines– Pumped condensate lines– Lack of proper drainage ahead of a steam control valve
– Differential shock• The piston effect• Differential pressure• Steam is 10 times the velocity
Differential Water Hammer
The steam piping is subject to water hammer.
Steam velocity @90 MPH
Condensate lying in the bottom of steam lines is the cause…..
– Point A is plugging beginning.
– Point B is the Delta P; accelerating flow.
– Bowling ball scenario: 20” slug in 8” pipe, @ 86 psig, 90 MPH
Differential Water Hammer
Whack!
Cause & Effect of Water Hammer
BANG!
Effects of Water Hammer
“We thought it was another 9/11 terrorist attack!”
New York City
Midtown Manhattan
July 18, 2007
Concentric
Reducer
Eccentric
Reducer
Steam Traps; Drip pocket
Drip Legs MUST BE Adequately Sized;Diameter and Length
312
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”
313
In-line Steam Separator
314
Drain Separator Cut AwayCyclonic
315
Steam
Condensate
Dirt
Drain for
condensate &
entrained water
and dirt
Dry Steam
Outlet
Drain Separator Operation
Drip Legs Allow a Space for Condensate and Dirt to Collect, and Direct the Condensate to the Steam Trap
Drip Leg
Steam Trap
6-10”
BD and Venting
Locations:• Low Spots
• End of Main Ahead of Expansion Joints
• Ahead of Valves, Bends, Regulators
Other Steam System Problems
• Air
• Water logging
• Corrosive gasses
Effects of air on steam temperature:
– Consumes volume
– Temp. falls
Chamber containing air and steam delivers
only the partial pressure heat of the steam,
not the total pressure.
Steam chamber 100% steam
Steam pressure 100 psig
Steam temperature 338O F
Steam chamber 90% steam and 10%
air
Total pressure 100 psig
Steam pressure 90 psig
Steam temperature 320O F
Temperature reduction caused by air
Effects of air on heat transfer– 1/2 of 1% by volume = 50%. loss
– 100% Air bound = No transfer
Steam condensing in a heat transfer unit pulls air
to the heat transfer area where it collects or
“plates out” to form effective insulation.
Condensate Steam
The need to drain the heat transfer unit
n Water bound
n Condensate in the heat transfer unit reduces capacity
n Removing it quickly keeps the unit full of steam.
12 psig
“Stall” or Water logging
12 psig
Oxygen
Corrosion– Oxygen enters
– Oxidation, pitting iron and steel surfaces.
Oxygen in the system speeds corrosion
(oxidation) of pipes, causing pitting.
Carbon Dioxide
Corrosion– Carbon dioxide (CO2)
– Enters as carbonates
– Vaporized, condensed = Carbonic acid.
CO2 gas combines with condensate allowed to
cool below steam temperature to form carbonic
acid which corrodes pipes and heat transfer
units. Note grove eaten away in the pipe.
Proper Water Treatment
Minimize scale and sludge deposits on boiler heat exchange surfaces.
Heat Transfer
1/16
1/8
1/4
3/8
1/2
15%
20%
39%
55%
70%
Thickness
of Scale
(Inches)
Increase in
Fuel
Consumption
Based on pure calcium & magnesium scale
NOTE:
40 deg. F
increase
= 1%
loss!
Benchmark:
• Oper. Press.• Amb. temp.• Firing rate
Questions?
• Parasitic losses:• Stack
• Piping
• Velocity (erosion, noise & water hammer)
• Air
• Water logging
• Corrosive gasses
• Scaling
• Blowdown loss
• Condensate loss
Condensate controlSteam Traps
What Traps Do
Trap Steam
Remove Condensate
Remove Air
What Goes into Selecting a Trap?
L Load (#/hr of steam
A Application (Dictates the type of trap used)
M Mod\Constant Pressure
B Back Pressure
S Supply Pressure
Why Steam Traps Fail
331
1. Dirt
2. Pressure increases & drops
3. Air binding
4. Wear
5. Misapplication
6. Water hammer
7. Oversizing
Warning Signs
332
1. Vertical steam plume
2. Condensate tank failure
3. PRV’s not holding required pressure
4. DA or Surge overpressure/temperature
5. Production slow down
6. Piping wear and leaks
7. Heat exchanger failure (H2CO3)
What’s this cost?
Dollars/Year at 100 Psig
Equivalent
Orifice
Diameter
1/16”
1/8”
1/4”
1/2”
Lbs./Yr.
Steam
Loss
115,630
462,545
1,848,389
7,393,432
Steam Cost Per 1000 Lbs.
$5.00 $7.50 $10.00
$578 $867 $1,156
$2,313 $3,469 $4,625
$9,242 $13,863 $18,484
$36,967 $55,451 $73,934
Cost Multipliers For Other Steam Pressures:
16 Psig -. 26 50 Psig - .56 150 Psig - 1.43
200 Psig - 1.87 300 Psig - 2.74 600 Psig - 5.35
333
Cost of Steam Trap Leaks
Trap Categories
• Thermodynamic– Steam (flash) -flow operates valve
• Mechanical– Use difference in density between
steam and condensate to operate valve, or a float operates the valve.
• Thermostatic– Sense temperature change to
operate valve
Balanced pressure
F&T IB
Disc
Thermodynamic Disc
Has (2) Concentric Seating Rings:
. Inner: Separates the inlet from
the outlet (P1 from P3)
. Outer: Controls leakage of steam
Disk Trap Flashing Steam
P1
P2
P3
Operation
1. Flow of condensate opens disc2. “Bernoulli concept:” As flow increases, pressure drops3. Flash occurs4. Disc shuts
Disk Trap Closed
• Trapping Steam
Thermodynamic Traps
• Modulation – Fair - Good• Back pressure – Poor
• Dirt – Poor
• Wear – Poor• Water Hammer – Good
• Corrosion - Good• Air Removal - Fair - Good
• Outdoor – Fair to poor
• Maintenance - Good
Mechanical Types
LinkageFixed
Pivot
Air Vent Valve or thermostatic
valve
Valve Ball
Seat
Float & Thermostatic Inverted Bucket
Mechanical Types
LinkageFixed
Pivot
Air Vent or thermostatic
valve
Valve Ball
Seat
Float & Thermostatic
F&T Traps
LinkageFixed
Pivot
Air Vent or
thermostatic
valve
Valve Ball
Seat
• Modulation – Very Good• Back pressure – Good
• Dirt – Poor
• Wear – Good• Water Hammer – Poor
• Corrosion - Poor• Air Removal – Excellent
• Outside – Poor
• Maintenance – Fair - Good
IB Opening
Valve wide
open
Valve body
• Purging condensate and air
Air vent orifice
IB Filling
Condensate
Valve tightly
closed
Steam
• Trapping Steam
Inverted Bucket
• Modulation – Fair – Good*• Back pressure – Good
• Dirt – Poor
• Wear – Good• Water Hammer – Good
• Corrosion – Good• Air Removal – Fair to Poor
• Outside – Poor
• *Requires a prime for sealing• Maintenance – Fair to poor
Thermostatic Trap, Balanced Pressure
Thermostatic element
Expansion closes
valve.
Balanced Pressure
• Modulation – Good• Back pressure – Good
• Dirt – Good
• Wear – Good• Water Hammer – Poor
• Corrosion - Poor• Air Removal – Excellent
• Outside – Good
• Maintenance – Good
Questions?
• Parasitic losses
• Piping Velocities and Pressure drops
• Condensate & air problems
• Corrosion
• Water hammer
• Steam Traps and condensate transport
348
Understanding and Checking Safeties
349
Safeties Checked During Ignition Sequence
• Gas valve proof of closure
• Oil Gun Switch
• Operating controls (OHM)
• Combustion Air Proving Switch
• Low Gas Pressure Switch
• High Gas Pressure Switch
• Low Oil Pressure Switch
• Atomizing Air Pressure Switch
• Scanner
Proof of Closure
Burner Gun Switch
349
Operating Pressure Controls
OperatingHigh limit
Modulating
350
351
Operating Limit Control
• Turns burner on & off based on desired pressure/temperature setting
• Adjustable (subtractive) differential
351
352
Operating Limit Control
• Operating set point is 100# = burner off• Differential is 5#, burner on @ 95#
The burner should
start when the boiler
pressure drops to
the setpoint value
minus this
differential
The burner
should shut off
when the boiler
pressure rises to
this setpoint value
352
353
High Limit Control
• Over pressure limit safety
• Set above the operating control
• Has Fixed differential
353
354
High Limit Control
Testing the Switch:1. Make note of the current setting
2. Adjust below the Operating Limit Control
3. Watch for trip
4. This is a MR control!
The burner should
shut off when the
boiler pressure rises
to the adjusted
setpoint value
354
Combustion Air Proving Switch
355
Assures adequate air for safe combustion
356
Combustion Air Proving Switch
356
Dial up to test
357
Low Gas Pressure Switch
• Normally closed switch
• Opens on pressure drop
• Breaks power to gas valve(s)
• Powers vent valve open
Low Gas
Pressure
Sensor
Vent
Valve
Manual Gas
Cock
357
358
Testing the Switch:
1. Close Manual Gas Cock.
2. Initiate the ignition sequence.
3. Return Manual Gas Cock to the open position.
Manual gas cock
Low Gas Pressure Switch
358
359
High Gas Pressure Switch
HGPSLGPS
359
HGPS
Why is it needed?
360
High Gas Pressure Switch
360
Testing the Switch:1. Note pressure while unit running2. Dial pressure back for trip3. Return to original setting
Low Oil Pressure Switch
361
LOPS
362
Low Oil Pressure Switch
Mercury Bulb Type
Adjustable
Differential362
Testing Switch:1. Burner off2. Has adjustable differential (10# normally)3. Dial back4. Restart, wait for trip
High Oil Pressure switch
363
HOPS
364
High Oil Pressure Switch
364
Testing Switch:1. Burner off2. Note set pressure3. Dial back4. Restart burner, wait for trip
Atomizing Air Proving Switch
365
AAPS
366
Atomizing Air Proving Switch
Adjustment
Set Screw
366
Testing Switch:1. Programmer (BMS) in “Run/Test”2. Note setting3. Dial back slightly, wait for trip
367
Low Water Cut-Offs
Main, Float Type Auxiliary, Probe Type
Low Water Cut-Off
– Check the head switches and
wiring
– Gauge glass & alignment
– Clean cross connecting piping
– Should not be heavy accumulation
368
Mercury Switch Type
Mechanical Switch Type
368
LWCO and Pump Control With Scale
369
Blowdown & Evaporation Test
370
Testing switch:1. Secure feedwater2. Allow boiler to run3. Watch GG for trip @LWCO point
371
Auxiliary Low Water Cut-Off
Testing the Switch:
• Jumper LWCO
• Allow evaporation to continue
• Remove jumper
Flame Scanner
Inspect & Test:
– Scanner lens & cable
– Remove
– 1-3 seconds burner off
372
Steam Boiler Room Log
Note: record water analysis and treatment on separate log
Date
Time
Boiler #
Operator
Water visible in gauge glass
Combustion check (visual)
Steam pressure
Feedwater pressure
Feedwater temperature
Flue gas temperature
Burner
Gas pressure
Gas meter reading
Oil pressure (regulated)
Oil temperature
Oil meter reading
Atomizing air pressure
Ambient air temperature
Make-up water
Blowdown water columns
Blowdown boiler
Comments/Observations
Chemical analysis
373
Summary
374
1. Boiler is the source of greatest energy loss and possible savings
2. Fuel/air ratio control is critical (Parallel positioning and O2 trim)
3. A 40 deg. F increase in stack temperature over base = 1% loss
4. Economizers recoup these losses in the stack putting Btu’s into the FW
5. Take stack analysis on a routine basis, and have burner tuned at least twice per year.
6. A 10 deg. F loss in FW temperature = 1% loss
7. NOx is reduced with Low NOx burners, FGR and SCR/NSCR
8. Boiler control consists of Burner Management Syst. & and Combustion Control Syst.
9. VFD saves electrical energy by reducing current draw and torque
10. Boiler heat is transferred through radiation, convection and conduction; surfaces need to
be clean on fireside & waterside.
11. The boiler and burner need to be matched to achieve maximum heat transfer coefficients
and Reynolds numbers
12. During phase change water expands 1600 times
13. Deaerators remove corrosive oxygen and free carbon dioxide, saving chemical and
blowdown losses.
14. Condensate is GOLD. Return as much and at as high a temperature as you can
15. Capturing flash steam is a real energy saver. Must be continuous.
16. Continuous blowdown losses can be captured. Never bottom blowdown!
17. Piping leaks and uninsulated piping needs to be addressed, now!
18. Traps are varied in design and vary in their applications and potential problems.
19. Traps operate on a differential which must remain within a given tolerance.
20. Checking safeties is essential with the LWCO being the single most important one.
Low Water Cutoff Caution!
McD&M Series 42 and 150 – 159 LWCO’s
Manufactured between Jan. – April 2015
may allow water level to increase over
time.
Call local representative or qualified
service rep. for details and recommended
action.
376
The Boiler Room Guide & Boiler Care Handbook
Final Questions
?
Thanks and…