Condensers and reboilers for the space age

Compabloc®

2 Compabloc

The Compabloc® from Alfa Laval can trulybe called a “magic box”. It is probably themost compact and efficient heavy-dutyheat exchanger in the world. Its remark-able design adds a completely newdimension to the condenser and reboilerchoices available – a dimension muchsmaller than you would previously havebelieved possible.

A unique concept How is such wizardry possible? Like mostmagic, it seems easy when you knowhow. The Compabloc design is based onbreakthrough technology that conjures upa whole range of significant advantages– all at the same time and in one compactunit. It operates with an extremely highthermal efficiency. Withstands aggressivemedia. Works at high pressures andtemperatures. Features a welded platepack. Can be tailored to suit your specificoperating conditions. And requires aminimum of space.

In other words, it is the perfect choice for use in chemical and petrochemicalapplications, which are often charac-terised by stringent demands. You caninstall this small unit virtually anywhere –as a condenser or reboiler for distillationand stripping columns, as a condenseron top of reactors and in a wide range ofother heat exchanger applications.

Designed for the space age Compared with conventional shell-and-tube heat exchangers, the Compablocworks magic on your wallet. It not onlyrequires a smaller volume and floor area,thus saving expensive space. It alsosubstantially reduces investment costsand minimizes maintenance – with nosacrifices in reliability or safety.

Small wonder, then, that more than 2,500 Compabloc condensers and reboilers have been installed at chemicalprocess plants all over the world since the design was first launched more thanten years ago.

The Compabloc has really worked its magic.

The Compabloc “magic box”

4 Compabloc

When you decide to install a condenseror reboiler, it is virtually standard practiceto include a shell-and-tube unit in thespecifications – it is the solution traditionally used by the chemicalprocess industry.

However, in order to fully appreciate the advantages of the Compablocdesign, you need to ignore traditionalthinking and consider some new engineering ideas.

Bulky & heavy …Shell-and-tube condensers are extremelybulky, heavy items of equipment. Thismeans there is only rarely any chance of mounting them anywhere else than at ground level – even though the placethey are often needed is at the top of a distillation column. Shell-and-tubecondensers take up a lot of the oftenlimited floor space available becausethey are usually installed horizontally.They also require complicated, expen-

sive piping that must reach from the topof the column down to the condenserand back. However, if you choose the option of installing a shell-and-tubecondenser high up, you then have theproblem of needing extremely costlyfoundations and structural work tosupport it.

Similarly, the best location for a reboileris on the ground, close to the bottom ofthe column. But shell-and-tube basedreboilers placed in this optimal locationtake up large amounts of the space thatis often at a premium.

… or compact & lightBy choosing a Compabloc design insteadof a shell-and-tube unit, you can reducethe size of your condenser or reboiler byas much as 80%, automatically makingthe entire installation much lighter.

In condenser applications, this meansyou can install the Compabloc where it

is most efficient, right at the top of thedistillation column – or as close asspace allows. No special constructionwork is needed, and the piping systemsrequired will be minimal. If you prefer toplace the Compabloc at ground level,you only require an absolute minimumof floor space to do so.

You also save considerable floor spaceif you choose a Compabloc unit as areboiler – as well as adding a newdimension to the choices open to you.Suddenly it might even become pos-sible to install a reboiler where such aninstallation was previously consideredcompletely impractical.

Breaking with traditionThe choice between installations thatare bulky and heavy and the compact,light and more modern alternative is avery simple one. You just need to forgetabout tradition and add a new, smallerdimension to your thinking.

Adding a new dimension tocondensers and reboilers

The three Compabloc condenserson the right require considerablyless space compared with the threeconventional shell-and-tubes onthe left

Compabloc 5

The small size and large capacity of theCompabloc almost seem like magic,combining two criteria that are totallyincompatible in shell-and-tube units.

The heat transfer coefficient of theCompabloc is two to four times that of atraditional shell-and-tube heat exchanger.Yet the Compabloc is also far morecompact and the liquid hold-up volumeis far smaller. Put these together, andyou can reduce the size of your con-denser or reboiler installation by a factorof five (or more) when you decide on aCompabloc unit instead of a traditionalshell-and-tube solution.

Dramatic comparisonsIn a volume of just 3 m3, the Compablocprovides you with a heat transfer areaequivalent to 1000 m2 of a traditionalshell-and-tube design. The tubular unitoccupies a volume of at least 15 m3 andneeds considerable additional free spaceso that the tube bundle can be pulled outfor cleaning. This results in a staggeringdifference in the footprint taken up bythe two different technologies.

How much can you save?Theory is one thing, practice another.What are the exact, quantitative benefitsin your particular application? This is afair question and we have a very prac-tical answer.

If you are planning to install a newdistillation column or to replace an existing condenser or reboiler, we simplysuggest that you contact us with thekey facts about your installation. We willthen provide you with a no-obligationinstallation draft and a cost estimate soyou can compare and judge for yourselfwhat the Compabloc can do for you.

The Compabloc is so compactthat you can even mount itdirectly on top of the column

Squeezing1000 m2 into 3 m3

This service will cost you nothing, but itcan ultimately save you a lot of money.An installation based on the Compablocdesign will both take up a minimum ofspace and keep the cost to a minimum.

6 Compabloc

The Compabloc is based on an innova-tive concept completely different fromtraditional condensers and reboilers. Ifyou are only familiar with the shell-and-tube design, you’ll be surprised howold-fashioned it really is and what aquantum leap the Compabloc repre-sents, both technically and in terms ofcost benefits.

The heart of the matterThe Compabloc heat exchanger is builtaround a pack of corrugated heat-transfer plates. These plates are weldedalternately to form channels. The com-plete plate pack slides inside a four-column carbon steel frame bolted topressure-retaining heads at the top andbottom. Four removable side panelscontain the fluid inlet and outlet connec-tions, and baffles direct the fluid mediaback and forth through the channels.

The corrugated plate pattern in theCompabloc creates a maximum ofturbulence, which in turn results inoutstanding heat transfer efficiency. The overall heat transfer coefficient istwo to four times greater than in acorresponding shell-and-tube unit. In other words, a Compabloc requiresonly 25–50% of the heat transfer areaof an equivalent tubular unit. That, inessence, is the advantage of theCompabloc.

Perfect as a condenser …When the Compabloc is used as a condenser, the vapour enters from thetop of the unit and condenses on thecold plates while passing through the plate pack. The condensate exits at the bottom. The cooling media isforced through several passes with aseries of baffles. This, together with theplate corrugations, maximizes heattransfer efficiency and minimizes fouling.

If the vapour contains non-condensablegases, a two-pass arrangement on thecondensing side permits gas/liquidseparation inside the Compabloc, elim-inating any need for a special separatorunit to do this. The main condensationtakes place in the first pass. The sub-cooling of the non-condensable gasesis achieved in the second pass, and this also serves as a mist eliminator.

… and as a reboilerWith its short flow path and large cross-section, the Compabloc is a perfectthermosiphon reboiler.

The feed enters at the bottom of theunit. When the liquid passes betweenthe heated plates, it is brought to boilingpoint and a mixture of vapour and liquid leaves the unit through the outletat the top.

The inner secret

The Compabloc condenserWhen used as a condenser, thevapour enters the Compablocfrom above and condenses on the cold plates. The condensate is extracted from the bottom of the unit

Condensate

Steam

Vapour/liquid mixture

Condensate

Liquid

Coolingmedia

The Compabloc reboilerIn reboiler applications, the liquidenters from the bottom of theCompabloc. The vapour/liquidmixture is extracted from thetop of the unit

The Compabloc condenser

Vapour

Coolingmedia

8 Compabloc

Corrosion and its effects have alwaysbeen a significant threat to condensersand reboilers used in the chemicalprocess industries. With shell-and-tubeunits, the traditional approach to dealingwith corrosion has simply been to expect that it will arise, to keep an eyeon the problem in the course of regularinspections, and then take the neces-sary measures when needed.

This is a risky approach, however.Corrosion developing faster thanexpected may cause product contamin-ation or a dangerous mixing of fluids.Inspection, maintenance and repairwork involve significant recurring down-time, with the worst-case scenariobeing an unexpected heat exchangerbreakdown that results in a long stand-still in production.

Aren’t exotic materials the answer?The obvious way to avoid corrosionproblems is to upgrade your condenseror reboiler by using a material that isresistant to any corrosion that mightoccur. However, the basic design of ashell-and-tube heat exchanger involvesthe use of very extensive metal surfaces,which means that replacing carbonsteel with corrosion-resistant materialssuch as Hastelloy™ or titanium is anextremely expensive step.

Manufacturing shell-and-tubes in exoticmaterial is therefore in most cases nota viable option because of the cost.This is why many plants decide to takea calculated risk and simply accept allthe production disruption and expenseassociated with operating a condenseror reboiler that continuously suffersfrom corrosion.

Play it safe with CompablocIt doesn’t have to be that way, however.With a Compabloc condenser or reboileryou can completely forget about corrosion. Due to the compactness ofthe design, the amount of heat transfermaterial used is significantly less than in a shell-and-tube unit. A Compabloccondenser or reboiler can therefore beconstructed from virtually any metal thatcan be pressed and welded, and yet stillbe available at an economical price.

This means you can afford to choosethe material that provides your particularinstallation with the best possible protection against corrosion – and thenforget about the problem once and for all.

Corrosion is no longer an issue

The Compabloc design allowsan extremely varied selection of materials, making it possibleto eliminate corrosion risks

Think along new linesWith the Compabloc, you can begin byassessing the corrosiveness of themedia in your production flow. You canthen specify the exact material that willprovide the best possible performancein your heat exchanger, confident thatyour choice will be economically feasible.

In oil refineries, for example, chloridesoften come off with the top fraction,making titanium the obvious choice forthe condenser. Where a titanium shell-and-tube condenser would be prohibi-tively expensive, a titanium Compablocis both practical and economical. Yourdistillation column could then operatecontinuously and reliably at peak levelwith no unnecessary interruptions forservicing or repair.

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Tailored to yourspecific needs

The Compabloc is based on a modularconcept that makes it easy to tailor anyunit to suit your particular processconditions. This gives you the best ofboth worlds – it is both economical and iseasy to customize to your specific needs.

What space is available?The basic advantage is the small spacetaken up by a Compabloc unit. Thanksto its high heat transfer coefficient, youcan reduce the volume taken up by your condenser or reboiler by a factor of five. If you don’t have the floor spaceavailable for a shell-and-tube heatexchanger, the Compabloc is thereforethe obvious choice.

But what if there’s not even sufficientfloor space to install a Compabloc?Well, that’s no problem either.

Creative installationIf there is insufficient floor space avail-able, a Compabloc condenser can bemounted directly on top of the distilla-tion column. And apart from savingexpensive floor space, you save a lot on piping by placing the Compablocclose to the column outlet.

Thanks to the low weight of the Compabloc, another option is to mountthe unit suspended from the roof structure. Compabloc units can be

mounted horizontally, vertically orinclined, or whatever is easiest for thespecific installation. The possibilities areendless.

Any medium, any metalThe heat exchanger plates for a Compabloc unit are available in a widerange of resistant materials and,because of their light weight, they are

relatively inexpensive. You can alwaysafford the investment to avoid corrosion.The welded construction also eliminatesany problems caused by media attack-ing gasket materials.

The way the inlets, outlets and bafflesare arranged is tailored to your specificapplication. Two-pass and multi-passflow configurations are easy to provide.

The Compabloc gives you complete freedom of choice as regards mounting – vertical,horizontal or suspended …

You can tailor an installation solution to match your requirements perfectly

10 Compabloc

Even though a shell-and-tube condenser or reboiler may rarely needroutine servicing, it is crucial that it isinstalled so that any problems can bedealt with rapidly. You need to get yourprocess restarted as soon as possible.

In a shell-and-tube installation, the tubebundle always has to be pulled outaxially. This means that considerableextra space is needed – space thatshould be kept free of all other equipment. In practice, this is rarely thecase. Everyone who has undertakensuch service work will testify that it is anawkward and unpleasant task involvinga lot of time, effort and manpower, aswell as causing significant disruption inany production environment.

The easy wayIn contrast, the unique design of theCompabloc means that service is simple.The side panels are easy to remove andvisual inspection rapidly reveals exactlywhere the problem is.

The turbulence created when a liquid orvapour flows through a Compabloc unitensures that fouling problems seldomoccur, because of the high shear ratealong the heat transfer wall. If cleaningis needed, the high turbulence and lowhold-up volume of the Compabloc alsomake chemical cleaning-in-place (CIP)procedures both effective and economical.Appropriate cleaning solutions canquickly be circulated through the unit.

An alternative solution is simply toremove the panels and hydroblast theplates with a high-pressure water jet.

A matter of hours, rather than a weekIn many condenser and reboiler applica-tions, legislation compels operators toundertake annual inspections. With theuse of exotic materials, these inspectionscan be avoided or carried out at muchlonger intervals. The installation of aCompabloc will also cut the operatingdowntime that results from an inspec-tion by almost a week compared with atraditional shell-and-tube unit, providinga significant boost to profit margins.

Easy maintenance

The compact design andremovable panels of theCompabloc ensure thatservicing is convenientand fast

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By now we hope you are sufficientlyconvinced to contact us at Alfa Laval todiscuss what Compabloc condensersand reboilers can do for you.

Should you need any further persuasion,here is a quick summary of the mainbenefits of the Compabloc. They allpoint in the same direction, because aCompabloc “magic box” works magicon your wallet.

Economy of scaleThe heat transfer coefficient of theCompabloc is two to four times that of a traditional shell-and-tube heat exchanger. Combined with the sheercompactness of the Compabloc design,this means that you can scale down thesize of your condenser or reboiler by afactor of five or more.

Economy of installationCompared with a traditional shell-and-tube heat exchanger, the Compabloctakes up much less floor space. Its lowweight means that you can also mountthe Compabloc directly on the distilla-tion column or suspend it from the roofstructure, or virtually any other suitablefixture.

Economy of configurationThe Compabloc is based on a modularconcept and can be tailored to fit yourexact process requirements, with inletsand outlets positioned to best advantage.Choosing the exact plate material bestsuited to the medium you are using isalso an economically viable proposition.

Working magic on your wallet

Economy of serviceThe Compabloc is easy to servicethanks to the simple design of the unit.Should fouling occur or service becomenecessary, the Compabloc can becleaned or repaired without moving itfrom the site. There are no unnecessaryproduction standstills.

Challenge usPresent us with your requirements andchallenge us to come up with a solutionthat is better than the traditional one.

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Alfa Laval in brief

Alfa Laval is a leading global providerof specialized products and engineer-ing solutions.

Our equipment, systems and servicesare dedicated to helping customers to optimize the performance of theirprocesses. Time and time again.

We help our customers to heat, cool,separate and transport products suchas oil, water, chemicals, beverages,foodstuff, starch and pharmaceuticals.

Our worldwide organization worksclosely with customers in almost 100countries to help them stay ahead.

How to contact Alfa Laval

Contact details for all countries are continually updated on our web site.Please visit www.alfalaval.com formore information.