Heat Recovery Eng 060829

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    DMESTON

    The EdmestonHeat Recovery SystemCarbon Black - Glass - Steel

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    Edmeston provides you with the most efficientHeat Recovery Systems for optimum fuel savings

    Source: China Carbon Black Institute 2001

    Edmeston is an engineering company established in1984 and belonging to the Sandvik Group.

    Edmeston designs and sells advanced equipment andsystems for the manufacture of sulphuric acid, sodiumhydroxide etc, as well as heat recovery systems for theglass, carbon black and steel industries.

    EDMESTONs major business lines:

    Edmeston Heat Recovery Systems for

    - Carbon Black

    - Glass, INKA

    - Iron and Steel

    Edmeston SX Systems for Sulphuric AcidIndustry

    Our business is based on:

    - A unique know-how in developing and manufacturingvarious steel grades, possessed by our parentcompany Sandvik

    - Our own strong process and material technologyknow-how

    - Our capabilities in design, manufacturing andmarketing

    Our business is focused on:

    - Development and delivery of advanced, customizedequipment and systems

    - Supporting our customers in construction andcommissioning

    - Providing cost effective and technically optimizedsolutions

    For further information please visit the Edmestonhomepage atwww.edmeston.com

    ENERGY SAVING -MORE IMPORTANT THAN EVER

    With increasing oil prices and higher environmental taxesmany industrial processes can make substantial costsavings by installing a heat recovery system. During thelast 15 years, oil prices have increased 60-70%. Theincentive to recover energy is and will become more andmore evident.

    Heat recovery also means lower exhaust gas volumesand lower emissions to the atmosphere. Heat recoverygives direct savings in terms of lower fuel consumptionas well as indirect savings in lower environmental impact.

    Last, but not least, it facilitates smaller and moreeconomic furnaces.

    Thus, heat recovery is a key factor to stay competitive inan even harsher economic environment.

    The example below illustrates the substantial annualsavings achieved by preheating the combustion air in acarbon black plant.

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    OIL PRICE 1988-2003USD / barrel

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    Annual Saving at different oil pricesCarbon Black 100 tubes Air Preheater (kUSD/year)

    1 kUSD = 1000 USD

    0

    100

    200

    300

    400

    500

    600

    700

    400 650 800 900

    Preheating temperature (C)

    AnnualSaving(kUSD

    /year)

    47 USD / barrel

    34 USD / barrel

    20 USD / barrel

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    A carbon black 800C Air preheater for lower fuel consumption

    and energy saving

    OUR SOLUTIONS

    A heat recovery system from fluid gases often consistsof a recuperator, i e a heat exchanger absorbing andtransferring heat into another fluid.

    If the heat is directly returned into the primary process,typically by preheating the combustion air, energy saving

    is achieved.Preheating the combustion air in the carbon blackprocess or in a glass furnace results in considerablesavings.

    Depending on current oil prices, a typical pay back timeof the investment is 1 - 2 years.

    Heat recovery systems from Edmeston cover a widerange of industrial applications and technical solutionsfor different temperature ranges. Our solutions are basedon Sandviks high temperature materials with proven

    reliability and long lifetime.

    In some applications it is possible to achieve a lifetimeof 10 years or more.

    CARBON BLACK AIR PREHEATERS

    The technology gives a possibility to preheat cold air to800-900 C by taking the heat from the exhaust gasfrom the carbon black reactor. The preheated air is thenused as combustion air in the burner.

    Our scope of supply is shown below:

    Edmeston provides two types of air preheaters:double and single shell design.

    The figure illustrates the basic principles of the two typesof airpreheaters:

    The double shell type is of a non-fouling design. Itconsists of one inner and one outer shell. The air ispreheated in the annular air gap, minimizing the thermalgradient in the upper part. This reduces the foulingtendency.

    This type is widely recognized for its low maintenancecosts and few production stops.

    The number of cleanings due to fouling is minimized.

    Both the single and the double designs are equipped withan air cooled double bottom tube sheet. This design hasproved itself to secure maximum lifetime for the bot-

    tom part.

    The air is flowing in counterflow to the carbon blackgas inside the fire tubes and passing through bafflesplaced all the way downstream.

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    Air inletAir outlet

    Filter

    Air Preheater

    Quench water

    Reactor

    Our scope of supply

    Additives

    Natural gas

    Carbon Black

    ApplicationType of

    recuperatorHeat transfer

    by

    Flue gas inlet

    temp oC

    Preheat tempoC

    Carbon Black Tube BundleRadiation +Convection

    900 - 1030 650 - 900

    GlassTube bundle orDouble Shell

    Radiat ion 1250 - 1400 400 - 800

    Mineral Wool Tube Bundle Radiation 1100 - 1400 550 - 650

    Iron and steel Tube BundleRadiation +Convection

    700 - 1100 400 - 650

    CB gas in

    Air in

    Air out

    CB gas out

    Coolingair out

    Coolingair in

    CB gas in.

    Air in Air out

    CB gas out

    Coolingair in

    Coolingair in

    DOUBLE SHELL SINGLE SHELL

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    One unit ready for delivery

    Top and bottom view of a carbon black airpreheater during assembling

    Edmeston has supplied air preheaters to the carbon blackindustry since 1992. So far around 20 units have beeninstalled worldwide.

    The sizes range from 76 to 144 tubes. The nominal airflow 10 000 28 000 Nm3/hr and the air preheattemperature 740 800C .

    Edmeston also has a design concept for a 900

    C air pre-heat temperature unit.

    Our material selection is based on Sandviks hightemperature material technology. High temperatureresistant materials such as 253 MA etc are used in tubesand shells. Ferrules in fire tubes are made of GRX -a special and unique material with exellent hot corrosionresistance in reducing high carbon content atmospheres.

    GLASS RECUPERATORS - INKA

    Edmeston INKA glass recuperators have beendeveloped during more than 50 years of serviceexperience of the glass industry. More than 400recuperator systems have been installed over the yearsand the applications cover most glass types, such as con-tainer glass, C glass, E glass, technical glass, TV glass and

    crystal glass.

    Out of the 400 systems supplied, 40 % are of thecombined tube bundle and double shell types, 30 % aretube bundles and 30 % are double shell systems.

    The heat recovery is recuperative (not regenerative ). Itis used for air preheating up to 800C, and for furnacesizes of 10-400 ton/day.

    The recovery process is based on preheating air bytransferring heat from the exhaust gases to the cold air.

    The preheated air is then transported back to the burnersin the glass furnace.

    The exhaust gas flows inside the tube bundle and the airflows inside the tubes. Normally, parallel flow is usedbetween exhaust gas and air.

    Edmeston glass recuperators can be designed as a tubebundle, as a double shell or as a combination of thesetwo types, as shown in the table below:

    The energy saving potential is illustrated in the diagrambelow. For a typical flue gas temperature of 1350C andair preheat temperature of 800C, the energy saving is

    about 45%.

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    Tube Bundle andDouble Shell Tube Bundle Double Shell

    Air preheat temp oC 800 750 550

    Flue gas temp oC < 1450 < 1450 < 1200

    Furnace size (ton/day) 50 - 400 50 - 400 10 - 70

    Investment level, KUSD 125 - 1200 90 - 800 30 - 70

    SAVINGS IN FUEL CONCUMPTION AT DIFFERENT FLUE GAS INLET ANDAIR PREHEAT TEMPERATURES

    Calculation according to "The Handbook of Glass Manufacture"

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    25

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    45

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    1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500

    Flue gas temperature (C) before air preheat

    Fuelsaving(%)

    600 C

    700 C

    800 C

    900 C

    A unit ready for delivery

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    Cold Air

    275oC Air

    Flue gas

    Hot air 800oC to

    the burners

    Soda Lime Glass Furnace Recuperator 230 ton/day

    The picture shows a tube bundle and double shell air preheating system for a container glass furnace with the productioncapacity of 230 ton/day and a preheating temperature of 800C.

    GLASS CASE HISTORY:

    The following example is taken from a big container glass furnace showing the short pay back time for the investment:

    Furnace production 230 ton glass/day or 84 000 ton glass/year

    Energy consumption 2600 kcal/kg glass (no airpreheating)

    Oil consumption 0,27 kg oil/kg glass 22 750 ton oil/year

    Exhaust temperature 1350C

    Air preheat temp 800C

    Fuel saving 45% or 10 235 ton oil /year

    Oil price 200 USD/ton

    Saving: 2,05 MUSD/year

    Investment 1,3 MUSD

    Lifetime 10 years (one campaign)

    Pay back time 8 months!

    Waste gas outlet temperature 800C

    Air flow 17 400 Nm3/hr

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    Double shell recuperator assembly

    A tube bundle system under construction

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    A steel air preheater prior to installation

    OTHER APPLICATIONS - IRON ANDSTEEL

    Edmestons long experience of radiant heat recoverysystems in the glass and carbon black industries is alsoused in applications for the iron and steel industries.

    The figure illustrates the basic principle of the

    recuperators:

    The furnaces often work at combustion airtemperatures as low as 400C. Raising the airtemperature with 100C results in about 6% fuel savings.This substantially reduces the operating costs of thefurnace.

    Several references are available.

    Recuperators for billet reheating furnaces

    25 MW input power and a furnace temperature of1000C. The furnace is heated by natural gas and opengas burners. The flow is cross-parallel.

    Air preheat temperature 400-450C

    Waste gas inlet temperature 810-975C

    Waste gas outlet temperature 522-655

    CAir flow 26000-38 000 Nm3/hr

    Waste gas flow 27000-40000 Nm3/hr

    The recuperator was installed 1992 and is still inoperation.

    DRI (direct reduction of iron)

    Air inlet temperature 190C

    Air outlet temperature 650C

    Waste gas inlet temperature 1070C

    Waste gas outlet temperature 800C

    Air flow 74 000 Nm3/hr

    Watse gas flow 94 000 Nm3/hr

    The recuperator saving gives a pay-off time less thanone year of the investment.

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    Flue gas in

    Hot air out

    Flue gas out

    Cold air in

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    EDMESTON

    www edmeston com

    EDMESTON AB (Head Office)Olof Asklunds gata 8S-421 30 VSTRA FRLUNDA, SwedenTel: +46-31 335 63 50Fax: +46-31 335 63 65E-mail: [email protected]

    EDMESTON USc/o Sandvik Process Systems LLCTotowa, NJ 07512USAE-mail: [email protected]

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