AF Flue Gas Ex Changers

In Finland:Taniplan KyKylätie 18 B 2000320 HelsinkiTel. 09-4583 120Fax 09-4583 119Email [email protected] http://www.taniplan.fi

Air FröhlichFlue Gas Heat Exchangers

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Air Fröhlich Flue Gas Heat Exchangers

1. Reheating of Clean Gases behindScrubbers

Clean gases discharged from wet absorbers (scrubbers) arewater vapour saturated and still contain droplets and residualparticulate matter. These gases must be dried by reheatingbefore admission into subsequent components or into thedischarge stack. For this purpose, AIR FRÖHLlCH suppliesstatic heat exchangers as a proven and economical solution.

Application Areas with Flue Gases

* Oil and coal-fired power plants and co-generation plants* Industrial combustion plants* Refuse and special waste incineration plants

Heat displacement with a raw gas cooler and clean gasheater

Direct heat exchange by StagavoR

Steam reheating by means of steam/gas preheater

Clean gas drying by admixture of hot air from StagavoR

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2 Utilization of the Heat of CleanGases from Denox-Reactors

lf the SCR facility is mounted behind the scrubber,the raw gases must be reheated to the reactiontemperature of approx. 300 °C. AIR FRÖHLICHstatic heat exchangers with high thermal efficiencydispense in large measure with the need to useexternal energy sources. The main heating iseffected via the multistage steel tube heatexchanger or the counterflow plate-type heatexchanger. To prevent corrosion in the cold inletzone, the raw gases must be preheated by meansof an acid-resistant heat exchanger. This may berealized through:

a) A steam/gas preheater (also suitable forcold start-up)b) ReheatIng behind the scrubber by meansof a StagavoR

c) Use of an acid-resistant first stage of theheat exchanger operating with the pre-cooledclean gases behind the Denox facility

3 Energy Saving by Utilization ofFlue Gas Heat

The energy content of the flue gas can be used atvarious points in the flue gas line for energy savingpurposes or to increase plant efficiency. For thispurpose, the heat exchanger must satisfy thenecessary requirements in respect of temperature,corrosion resistance and cleaning capacity on theraw gas side.

AIR FRÖHLlCHbuilds heat exchangers for use:* as air preheaters* as economizers* for heat extraction

CombinationsFurther application areas and combinations ormodifications of the three examples of usedescribed here are of course feasible and havealready been implemented in a great many plants.

Raw gas heating in front of Denox-reactor using a counterflow plate-type heat exchanger; preheating by means of a steam/gas preheater

Raw gas heating in front of Denox-reactor using a multi-stage steeltube heat exchanger; preheating by means of a steam/gas preheater oran acid-resistant first stage

Air preheater

Economizer

Heat extraction

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Stagavo® and Static Air Preheaters

Acid-resistant Flue Gas HeatExchangers by AIR FRÖHLICH

The heat exchanger with fully synthetic tubeshas been developed to meet the need for aheat exchanger with unlimited corrosionresistance in the acid dew point range of fluegases. The temperature ranges of raw gasesin coal- and refuse firing systems are suchthat only fluorinated synthetics, such as PTFE,PFA and PVDF are suitable for this app-lication. The exchanger surfaces consist oftubes which are sealed on both sides in tube-end plates which are also corrosion resistant;the tubes, depending on their length, are fixedwith a variable number of spacers.

StagavoR in Block- andRing~type Designs

Depending on the flue gas flow rate to beprocessed, block- or ring-type designs will bechosen. For flue gas volumes of up to about1 million Nm3/h, a more economical solutionfor the design of ducts and hoods is gene-rally adopted with the BlockStagavoR. Forlarger flue gas volumes, a ring-type StagavoR

layout will be chosen to save space andhandle the flow requirements.

Gas flows through StagavoR

Heat exchangers with fully synthetic tubes willpreferably be built with vertical tubeconfiguration. The raw gases flow downwardsthrough the tubes while the clean gas(generally arriving from theSOx-absorber) is conducted horizontallyaround the tubes.

Design for Higher Raw GasTemperatures

The heat exchanger with fully synthetic tubescan be used at temperatures of up to 250 °C.For higher temperatures, AIR FRÖHLICHbuilds a special model with a metallic rawgas inlet seal. Provided that minimum tem-peratures are respected for the raw gas andmaximum temperatures for the clean gas, thisversion is suitable for raw gas inlettemperatures of up to 320 °C.

Special Steel Tube Version, lined with SyntheticMaterial

Provided that the gases which flow through the tubes do not condenseand contain no harmful substances (e.g. air or dry clean gases) alower cost version with steel tubes, lined with synthetic material, canbe chosen. These tubular heat exchangers only offer corrosionresistance in the area of gas circulation around the tubes.

Glass Tube Heat Exchangers - a Low CostSolution

Glass tubes can also be used to a limited extent as heat exchanger surfacefor air preheaters in contact with flue gases, provided that no condensingfluorides occur.

Design Type Designation Notes

Glass tube airpreheaters

GRS-S, GES, FGRS,GHS, GFS ja GTS

Casing design andtube seals deoendingon application area

IAir preheaters withlined steel tubes

FRS Flue gases aroundthe tubes

Air preheaters withfully synthetic tubes

FHS, FES Flue gases aroundthe tubes

Block-typeStagavosR

FFS, FTS, EFS Both gas sides influorinated syntheticdesign

Ring-type StagavosR

1)FFR, EFR Both gas sides in

fluorinated syntheticdesign for largevolumes in powerplants

StagavosR is a registered trade name of AIR FRÖHLICH1) Ring-type StagavosR are supplied in co-operation withAppratebau Rothemüle

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Model of ring-type StagavoR for powerplant applications1)

StagavoR unit module

StagavosR with fullysynthetic tubes requirecompensation for lengthvariation caused bytemperature differences,the lower tube-end platetherefore is designed asa membrane

Metallic tube sealing forStagavosR in thetemperature range up to320 °C

Air preheater in glasstube design: the casinghas an acid-resistantlining

StagavoR and Static Air Preheaters

Block-type StagavoR for reheating clean gases byutilization of raw gas heat

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Steam/Gas Preheaters and Gas/Water Heat Exchangers

AIR FRÖHLlCH gas/water heat exchangers in plaintubular design, using stainless steel tubes or PFA-lined compound tubes, are proven appliances foruse as flue gas heaters and flue gas coolers tosatisfy exacting standards.

Acid-resistant Designs

The heat exchangers with full corrosion protectionon the gas side are made of stainless steel tubeslined with fluorinated synthetics. The tube-endplates are also lined on the gas side with plates offluorinated synthetics. This design combinespressure resistance of the steel tubes on the wateror steam sides with excellent corrosion resistanceof the synthetic material on the gas side. Theproverbial anti-adhesion properties of fluorinatedsynthetics limit the susceptibility to fouling andensure easy cleaning on the gas side.

These heat exchangers are built to comply withthe relevant regulatory provisions on steamvessels, in particular when they are designed assteam preheaters. official acceptance certificatesare supplied.

Stainless Steel and Glass TubeHeat Exchangers

Stainless steel plain tube heat exchangers areused as gas preheaters and coolers for gases witha low corrosive effect. The AIR FRÖHLICH glasstube heat exchanger is suitable for special applications, in particular at relatively low waterpressures.

Design TypeDesignation Notes

Steam/gas preheater FDG-D/-P Synthetic material lining ongas side

Raw gas coolerClean gas heater FWG-B/-P/-D

For heat displacementsystems in power plantsand refuse incinerationplants

Economizer SWG, FWG,FGWG, GWG

Feed water, heatextraction for districtheating or process water

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Stainless steel tubeeconomizer for high gastemperatures

Acid-resistant gas cooler forwaste incineration plant

Steel tubes lined withfluorinated synthetics, waterheaders outside of gas flow

Special welding of tubes intotube-end plate

Steam/gas preheater for cleangas application

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The Denox-Gas preheater

Gas/Gas Heat Exchangers byAIR FRÖHLICH with HighThermal Efficiency

AIR FRÖHLICH builds low-cost tubular andplate-type heat exchangers in carbon steelfor flue gases in the temperature rangeabove the acid dew point.

The steel tube production plant of theArbonia-Forster-Group is directly adjacentto the AIR FRÖHLICH heat exchangerassembly shop. This brings AIR FRÖHLICHlogistic benefits for the procurement of steelprofiles and round tubes.

Tubular Heat Exchanger(SRX) (multiple counter-crossflow)

The AIR FRÖHLICH tubular Denoxgaspreheater offers maximum operationaldependability:* Possible sulphate deposits around thetubes can be washed off easily* Single tubes in horizontal tubearrangement or modules can be replaced* Fluorinated synthetics can be used toprotect the first (cold) stage against SO3-condensation on the clean gas side

Plate-Type Heat Exchanger(SPG) (counterflow)

The AIR FRÖHLICH plate-type heatexchanger is built with rectangular profiletubes. It combines a compact design withhigh thermal efficiency (low temperaturedifference). It will generally be preceded bya steam/gas preheater or StavagoR, withcorrosion protection to preheat the raw(cold) gases.

Counterflow plate-type heat exchanger

Thermal efficiency (low temperature difference)

- - - - - Plate-type heat exchanger (counterflow)_____ Tubular heat exchanger (counter-crossflow)

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AIR FRÖHLICH Denox-gas preheaters arebased on steel tubingmanufactured by theArbonia-Forster-Group.Both, round tubes andprofile tubes, aremanufactured inhouse.

Structure of the plate-type heat exchangerwith profile tubes

Steel plate Denox-gaspreheater designed toensure high thermalefficiency (lowtemperature difference)

Steel tube heatexchanger in counter-crossflow design

Tubular heat exchanger (vertical tube configuration)

Tubular heat exchanger (horizontal tube configuration)

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Corrision-resistant Linings

Acid-resistant heat exchangers are notcoated but lined with fluorinatedsynthetics, using a fixing system whichhas been specially developed by AIRFRÖHLICH.

AIR FRÖHLICH specialists are able tofit this lining even on complex ductsections in all sizes.

Total protection againstcorrosive attack on the gas-carrying ducts is guaranteed:

* Temperature resistance to 250 °C* Leakproof* Repairable* Independent of duct material andsurface finish* Long life expectancy (no abrasion)

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Cleaning Facilities

Depending on the particular application, a cleaning facilitymust be provided for the heat exchanger on the raw gasside, and in some cases also on the clean gas side. Wateris generally used for cleaning.

Cleaning Systems:* Revolving spray pipe cleaning* Movable spray pipe cleaning* Manual cleaning by water injection during regular plantshutdown

Our Reference Plants

AIR FRÖHLICH has acquired many years experience in theconstruction of heat exchangers for flue gases.

Large numbers of AIR FRÖHLICH heat exchangers havebeen in successful worldwide use since 1978 as airpreheaters and economizers or for heat extraction.

Steam/gas preheaters, StagavosR (static gas preheaters)and heat displacement systems made by AIR FRÖHLICHgive excellent results in reheating applications behindscrubbers. Between 1987 and 1992 alone, some 100 unitsof this kind were incorporated into waste incineration plants.

Many Denox-gas preheaters have been delivered or alreadyordered since 1992.

The experience acquired by AIR FRÖHLICH guarantees thedependability of its products.’

Stagavo® with integral movable spray pipe cleaningsystem

Revolving spray pipe cleaning system with washing inprogress

Revolving spray pipe cleaning device

Reheating unit in waste incineration plant

Assembly of a large Denox-gas preheater,built as a 4-stage tubular heat exchanger

Block-type StagavoR in a coal-firedindustrial power plant

Stagavo® installed in Japan

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AIR FRÖHLICH - TheSpecialists for StaticHeat Exchangers

Our head quarters in Oberaach, Switzerland, are responsible fordevelopment, design, fabrication and marketing.

Established 1972 as Air Fröhlich, AG for energy recovery;since March 1, 2000 name changed to Air Fröhlich Engineering AG.

Air Fröhlich Engineering AGWeidweisenCH-8587 Oberaach

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AF Flue Gas Ex Changers