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David Cronin-Ohio Valley Area Manager Heat Transfer, Controls & Instrumentation, Metering. David Cronin-Ohio Valley Area Manager Heat Transfer, Controls & Instrumentation, Metering.
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NOH HeatTransfer

Jan 30, 2016

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  • David Cronin-Ohio Valley Area Manager

    Heat Transfer, Controls & Instrumentation, Metering.

    David Cronin-Ohio Valley Area Manager

    Heat Transfer, Controls & Instrumentation, Metering.

  • Heat Exchangers

  • Selection IssuesSelection Issues

    Maximum design Capacity

    Steam Supply pressure

    Materials of construction

    Space and access

    Controls/Communication

    Steam Quality

    Load TURNDOWN

    Condensate quality & system Issues

    Maintenance of ALL components

    Maximum Pressure Drop allowed

    Water Quality-TDS, hardness, chlorides

  • Selection IssuesSelection Issues

    Maximum design Capacity

    Steam Supply pressure

    Materials of construction

    Space and access

    Controls/Communication

    Steam Quality

    Load TURNDOWN

    Condensate quality & system Issues

    Maintenance of ALL components

  • Metal Wall

    Scale Film

    Steam

    Air Film Stagnant Water

    Condensate Film

    Heat Transfer Q = U x A x DT

    Water

    Being

    Heated

    Heat Transfer

  • Steam Supply QualitySteam Supply Quality

    LP steam carries more Btus, increases efficiencies.

    LP steam is normally better quality, increasing efficiencies.

    LP steam REDUCES scaling (The lower the better).

    LP steam typically requires PRVs to generate from HP.

    PRVs require space and give more to maintain.

    LP steam requires large pipes.

    LP condensate is difficult to drain from HX.

    HP steam requires no PRVs and smaller pipe.

    HP steam makes HX, conditioning, & control equipment smaller.

    Installation less expensive with HP steam.

    We can combine the benefits from both systems !

  • Methods of ControlMethods of Control

    Constant Pressure with float & thermostatic steam trap- Wild loop

    Constant Pressure with float & thermostatic steam trap in

    conjunction with mixing valve

    Constant Pressure with control of the heating surface

    Control Mass flow of steam with discharge temperature of the

    Secondary Side

  • Typical HX ???-Open SystemTypical HX ???-Open System

  • Steam and Condensate QualitySteam and Condensate Quality

    Vacuum breakers introduce air !!!!

    Reverses Heat Transfer !!!!

    Wastes steam !!!!

    Increases duty cycles of heat transfer equipment !!!!

    Increases duty cycles of Control equipment !!!!

    Barriers heat transfer, reduces heating efficiency !!!!

    Reduces equipment capability to handle load changes !!!!

    Corrodes (oxygen pitting) Heat Transfer Equipment !!!!

    Generates Carbonic Acid !!!!

    Erodes Heat Transfer Equipment !!!!

    Corrodes/erodes Condensate System !!!!

    Increases Chemical requirements !!!!

  • STALL IssuesSTALL Issues

    Poor Control !!!!

    Slow response to load changes !!!!

    Noise !!!!

    Waterhammer !!!!

    Leaking Gaskets !!!!

    Damaged / Failed Equipment !!!!

    Increased Maintenance !!!!

    Premature failure due to thermal

    Cycling

    Definition: The point at which the necessary pressure differential across the

    trap is below the point at which condensate can be removed from the heat

    exchanger.

  • Loss of Positive Differential PressureLoss of Positive Differential Pressure

    www.SpiraxSarco.comwww.SpiraxSarco.com

    APT rangeStall due to elevated return line

    15 metres

    1.5 bar g

    1.0

    bar g

    Air Heater

    Battery

    A steam trap is

    being used to drain

    the system

    www.SpiraxSarco.comwww.SpiraxSarco.com

    APT rangeStall due to elevated return line

    15 metres

    1.5 bar g

    1.0

    bar g

    Air Heater

    Battery

    A steam trap is

    being used to drain

    the system

  • Condensate backing up into

    heat exchanger-loss of A

    Condensate backing up into

    heat exchanger-loss of A

    www.SpiraxSarco.comwww.SpiraxSarco.com

    APT range

    Heat Exchanger

    P2

    P1

    Product Temperature Input

    Stall conditions

    www.SpiraxSarco.comwww.SpiraxSarco.com

    APT range

    Heat Exchanger

    P2

    P1

    Product Temperature Input

    Stall conditions

  • Temperature Control Valve Opens and

    positive differential pressure is increased.Temperature Control Valve Opens and

    positive differential pressure is increased.

    www.SpiraxSarco.comwww.SpiraxSarco.com

    APT range

    Heat Exchanger

    Stall conditions

    P2

    P1

    Product Temperature Input

    www.SpiraxSarco.comwww.SpiraxSarco.com

    APT range

    Heat Exchanger

    Stall conditions

    P2

    P1

    Product Temperature Input

  • Stall ChartStall Chart

    www.SpiraxSarco.comwww.SpiraxSarco.com

    APT range

    Total back pressure

    - 0.4 bar

    Steam pressure (temp)

    - 2 bar

    Initial Temperature Product

    - 30 oC

    % Flow (% control valve opening)

    Final Temperature product

    - 80 oC

    T

    e

    m

    p

    e

    r

    a

    t

    u

    r

    e

    C

    Product Temperature

    200

    20

    40

    60

    80

    100

    120

    140

    160

    180

    0

    100 90 80 70 60 50 40 30 20 10 0

    14.5

    11.6

    0

    0.7

    0.5

    0.05

    2.6

    0.3

    0.2

    0.1

    9.0

    7.0

    5.2

    3.8

    1.7

    1.0

    0.4

    T1

    P1

    T2

    P2

    1

    3

    Air Heater

    Application

    P

    r

    e

    s

    s

    u

    r

    e

    b

    a

    r

    g

    2

    Variable inlet temperature stall chart

    www.SpiraxSarco.comwww.SpiraxSarco.com

    APT range

    Total back pressure

    - 0.4 bar

    Steam pressure (temp)

    - 2 bar

    Initial Temperature Product

    - 30 oC

    % Flow (% control valve opening)

    Final Temperature product

    - 80 oC

    T

    e

    m

    p

    e

    r

    a

    t

    u

    r

    e

    C

    Product Temperature

    200

    20

    40

    60

    80

    100

    120

    140

    160

    180

    0

    100 90 80 70 60 50 40 30 20 10 0

    14.5

    11.6

    0

    0.7

    0.5

    0.05

    2.6

    0.3

    0.2

    0.1

    9.0

    7.0

    5.2

    3.8

    1.7

    1.0

    0.4

    T1

    P1

    T2

    P2

    1

    3

    Air Heater

    Application

    P

    r

    e

    s

    s

    u

    r

    e

    b

    a

    r

    g

    2

    Variable inlet temperature stall chart

  • Waterhammer.Waterhammer.

  • Typical Heat Exchanger Types UsedTypical Heat Exchanger Types Used

    Shell and Tube-most common

    Plate and Frame

    Plate and Shell

  • Shell & Tube Heat ExchangerShell & Tube Heat Exchanger

    Horizontal or Vertical Installations

    Lowest U value of the 3 types

    Withdrawal distance equal to length of heat exchanger

    Lowest Cost in low to medium flowrates

    Simple Design

    Steam should be installed in the shell side

    Lowest Pressure Drop on Product Side

  • Plate & Frame Heat ExchangerPlate & Frame Heat Exchanger

    Very High U Value

    Ability to increase/decrease area with process changes

    Stainless steel is standard in gasketed models

    Small Footprint and floor space

    No Withdrawal distances required

    Install new plate pack WITHOUT pipe disruptions

    Long history of use in the process industries

    History of failure in steam systems due to Stall

    Perception that they do not work in steam systems

  • Plate & ShellPlate & Shell

    Very High U Values

    Typically used for high flowrates

    Not susceptible to thermal cycling

    Long History in the OPC Market

    Repairable Units relatively expensive

    Sealed units can be cost effective in high flow conditions

    Higher Pressure drop on process side

  • Closed Loop DrainageClosed Loop Drainage

  • Steam Supply QualitySteam Supply Quality

    LP steam carries more Btus, increases efficiencies.

    LP steam is normally better quality, increasing efficiencies.

    LP steam REDUCES scaling (The lower the better).

    LP steam typically requires PRVs to generate from HP.

    PRVs require space and give more to maintain.

    LP steam requires large pipes.

    LP condensate is difficult to drain from HX.

    HP steam requires no PRVs and smaller pipe.

    HP steam makes HX, conditioning, & control equipment smaller.

    Installation less expensive with HP steam.

    We can combine the benefits from both systems !

  • Closed Loop Drainage +Closed Loop Drainage +

    HP Steam

    LP Heat Transfer

  • Closed Loop Drainage +Closed Loop Drainage +

    HP Steam

    LP Heat Transfer

    HX Size ???

  • Plate & Frame HXPlate & Frame HX

    Smaller Footprint

    Large Surface Areas for LP Transfer.

    NO Tube Withdrawal space reqd

    Easier to maintain

    Some Flexibility with capacity

    Stainless wetted parts as standard

    Higher efficiency

    Better control Accuracy

    More responsive

  • Drain

    Gutter !!!

    Pipe size!

    Trap

    New

    Condensate

    Old

    Condensate

    New

    HP SteamOld

    LP Steam

  • EASI-HEAT UNITSEASI-HEAT UNITS

  • EASIHEAT UNITSEASIHEAT UNITS

    EASIHEATMaximizes Efficiency

    Minimizes Install Cost

    Maximizes ROI

  • Natural Gas Technologies Centre ReportNatural Gas Technologies Centre Report

    The thermal efficiency of a Plate &

    Frame averages 93.8% while that of

    the shell-and-tube with automatic

    pump trap (APT) averages 87.4%, a

    6.4% efficiency advantage for the

    Plate & Frame heat exchanger

  • Summary Heat Transfer

    HP SupplyMinimizes Installation issues

    LP Heat TransferMax efficiency

    Min maintenance

    Closed LoopCorrect condensate removal

    Max Efficiency / Min MaintenanceAPT

  • Heat Exchangers

  • Hot Water Heat ExchangersHot Water Heat Exchangers

    Instantaneous variable load capability

    Eliminates hot water storage and Legionella

    bacteria risk

    Accurate temperature control

    P&F construction designed for steam use

  • THANK YOU !!!

  • Questions

    ?????

    Questions

    ?????

    EASIHEATMaximizes Efficiency

    Minimizes Install Cost

    Maximizes ROI

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