industrial steam boiler optimization - seventhwave course_3up... · industrial steam boiler...

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


by Seventhwave

06/17/2015

Approved for:

6General CE hours


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

http://commons.wikimedia.org/wiki/File:Newcomen_atmospheric_engine_animation.gif


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


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


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


Solid state


• 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


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


• 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!

http://www.weatherinstruments.com/hygrometers/analog-hygrometers/chaney12inchthermometerwithhygrometer.cfm

http://www.weatherinstruments.com/hygrometers/analog-hygrometers/chaney12inchthermometerwithhygrometer.cfm

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


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


174


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+


• Exhausted condition

– Cation beads can be used in the service cycle until they are saturated with Ca++ and Mg++

– Requires regeneration

Ca++ or Mg++


• 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


• 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



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 -


• Exhausted condition

– Anion beads (+) can be used in the service cycle until they are saturated with Alkalinity (-)

– Requires regeneration with Chlorides, also (-)

Alkalinity


• 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


• 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




No Change

No Change

90 - 95%

Increases

20%


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

http://en.wikipedia.org/wiki/Image:Dioxygen-montage.png


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

http://www.engineeringtoolbox.com/oxygen-steel-pipe-corrosion-d_1170.html

http://www.tennoji-h.oku.ed.jp/tennoji/oka/2004/carbon dioxide.gif


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






How do I get rid of the corrosive gasses?

. Chemically

. Mechanically


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


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


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!

http://images.google.com/url?source=imgres&ct=tbn&q=http://www.heatandpowerproducts.com/images/steam/controls.jpg&usg=AFQjCNFYeuQaDcYNItUclv3YiGATmPsEyQ

http://images.google.com/url?source=imgres&ct=tbn&q=http://www.heatandpowerproducts.com/images/steam/controls.jpg&usg=AFQjCNFYeuQaDcYNItUclv3YiGATmPsEyQ

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


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…

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