1 Detail of a Shell ConSeptray offering extremely highcapacity at high vapor and highliquid loads.

All the new products havebeen integrated into one con-

sistent product portfolio with thealready well-introduced structuredpacking and the tray technology ofMetawa Tray, a company whichwas acquired by Sulzer Chemtechin 1987. The portfolio is the resultof the combination of the best of all these innovative technologies –

the classical Sulzer Chemtech,Metawa, Nutter and Shell GlobalSolutions products (Fig. 1 ) com-plement each other into a fullrange mass transfer portfolio withminimal overlap.

CONVENTIONAL TRAYSA conventional tray has one ormore downcomers for liquid trans-port to the tray below and an activearea where vapor and liquid comeinto contact. This active area canbe equipped with a wide choice ofbubbling devices. In today’s indus-try, the devices used are predomi-nantly simple sieve holes, movingand fixed valves, depending on therequired operating range.

After an evaluation involving in-dustrial acceptance, technical per-formance, references and price,Sulzer Chemtech chose the rectan-gular Nutter BDH Float Valve™(Fig. 2 ) as its standard movingand Nutter V-Grid™ as its stan-dard fixed valve. The valve portfo-lio is completed with the MetawaSnap-in™ valve, predominantlyused for Shell trays, a robust cagedround valve as well as a standardround valve, mainly used forreplacement services for non-Sulzer Chemtech trays. Further-more, the Metawa Lip-Slot™ con-nection (Fig. 3) was chosen as thestandard connection between thehorizontal tray panels.

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With the acquisition of Nutter Engineering (1998) and the strategic alliancewith Shell Global Solutions (2000), Sulzer Chemtech completed its productportfolio of mass transfer components. Nutter Engineering has brought in itsrange of random packing as well as its tray technology with a competitive setof bubbling devices for fractionation trays. The Shell mass transfertechnology package contains a complete line of high-performance trays.

Alliance of Technologies:

The Right Tray for any Application

MARIO ROZADALE NUTTER

SULZER CHEMTECH

2 A Float Valve with lateral vaporrelease and streamlined liquid flow;

the absence of valve rotation andwide legs reduce wear.

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HIGH-PERFORMANCE TRAYSModifications to the standardbubbling devices can give highervapor side tray capacity. An exam-ple of such a device is the Mini V-Grid MVG™ (Fig. 4 ). The SulzerChemtech VortexTray™, MVGT™and the Shell Calming Section™and HiFi™ trays (Fig. 5 ) createhigher capacity by eliminating thedowncomer sealing area. Addition-al to the optimized downcomer con-figuration it is possible to installde-entrainment devices above theactive area. These devices capturethe liquid entrained in the vaporphase at high vapor velocities andtransport it to the downcomers.The Shell ConSep™ tray is anexample of such a tray.

A CONSISTENT PORTFOLIOOne difficulty of Chemtech’s widevariety of mass transfer productsis to give them all a consistentapplication range. In this range,they should be most attractivefrom the commercial and technicalpoint of view. Sulzer Chemtech haschosen to position them in anapplication matrix arranged byoperating pressure and specific liq-uid load (Fig. 6). In this matrix, alltray types, and also structuredpacking, can be positioned. For low pressure applications,mainly random and structuredpacking are applied. The choice ofinternals (trays, random or struc-

tured packing) strongly dependson the application-related processrequirements and is not subject ofthis article.

ATMOSPHERIC TOINTERMEDIATE PRESSURE

Most towers operating under pres-sures below 6 bar are limited bytheir vapor-side capacity. In order

to increase the capacity of a valvetray here, Sulzer Chemtech canequip the active area with NutterMVG fixed valves. The reducedentrainment of liquid to the trayabove these bubbling devices gives10–15% capacity increase. Oncethe maximum capacity with thesedevices and conventional down-comers has been reached, the

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SHELL GLOBAL SOLUTIONS

Shell Global Solutions is an international technology business thatdelivers integrated services that add to their customers’ bottomlines. Working primarily in the oil, gas and process industries, theygive a competitive edge by helping to optimize plant and processperformance, formulate and develop products, and manage opera-tional safety and environmental challenges more effectively. The alliance with Sulzer Chemtech covers technologies for high-performance trays, associated internals and phase separationequipment.

3 The MetawaLip-Slot allowsfast and easyinstallation.

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4 MVG Mini V-Grid fixed valve (right)compared with sieve holes. MVG has a

streamlined liquid flow and lateral vaporrelease. It gives the highest proven tray

efficiency/capacity profile while havinglow pressure drop and good turn-down

capability.

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NUTTER ENGINEERING

Since Earl Nutter developed the first modern valve tray in 1945, Nut-ter Engineering continuously developed new cost-effective traydesigns and introduced them to industry with commercial-scale inde-pendent tests. Developed in the 70s, self-retained Float Valve™ andV-Grid™ fixed-valve trays set industry performance and mainte-nance standards. Independent testing in 1998 proved the superiorperformance of the optimized Nutter Mini V-Grid MVG fixed-valvetray.Sulzer acquired the innovative Nutter tray and Nutter Ring™ ran-dom packing technology that same year to complete their mass trans-fer component products portfolio.

downcomer configuration has to beoptimized. In a first step, down-comers are truncated as on theNutter MVGT. The area under thedowncomers can be used as activearea, giving this tray 5–10% capac-ity increase. Sulzer Chemtech VortexTray, ShellCalming Section™ trays and ShellCalming Section Plus trays havean optimized number of smalltruncated downcomers, giving afurther 10–15% capacity increasecompared to the MVGT tray. Thehighest capacity can be reachedwith the Shell ConSep trays.

HIGH-PRESSURE SOLUTIONSMost high-pressure applicationscan also be associated with a highspecific liquid load in the column.They are in most cases limited bytheir liquid-side capacity. Thismeans that trays used for thesetowers have to be optimized withrespect to their downcomers whichtransport the liquid to the traybelow. Due to the high vapor den-sities and low liquid densities forhigh-pressure operating condi-tions, special attention must alsobe given to the vapor disengage-ment in downcomers. This be-

comes more difficult with increas-ing ratio between vapor and liquiddensity.Traditionally sieve and valve traysare used for these operating condi-tions; the MVG fixed valves cangive a 5–10% capacity increase.Additional 5–10% can be reachedwith special downcomer configura-tions; in a first step with the Sulz-er Chemtech VortexTray with itsspecial downcomer baffle, promot-ing vapor disengagement. TheShell HiFi and HiFi Plus trayswith their slotted downcomertroughs can further increase towercapacity by 10–15%.

THE GLYCOL EXCEPTIONAn exception to the rule of highpressure and high liquid load areglycol contactors. They are used toreduce the water content of natur-al and fuel gas streams. They usu-ally run at pressures between 50and 100 bar. The liquid load inthese towers is very low. Until theend of the seventies, bubble capand floating valve trays were usedfor these applications. Since then,many towers have been revampedwith Mellapak™ structured pack-ing, which is particularly suited for

these conditions – capacity in-creases of 80–100% could bereached in many cases.MellapakPlus™ structured pack-ing lead to a further increase by20–30%. In order to reach thesecapacity levels, MellapakPlus andits distributor have been combinedwith a Shell Mistmat and Swirl-deck™ combination to prevent theloss of glycol over the top of the col-umn. Ultimate capacity is reachedwith Shell Swirl Tube™ trays.These trays, which have a co-cur-rent contacting space for vapor andliquid, give a further 30–40% ca-pacity increase.

PERFORMANCE WITHEXPERIENCE

The alliance of Shell Global Solu-tions’ technology and the technolo-gy from the companies that havebeen integrated into Sulzer Chem-tech provides a complete range ofsolutions with recognized benefitsfor the customers. These highlydependable mass transfer prod-ucts are the result of profoundoperational and design experience– and will be the basis for furtherinnovations. Ω

F O R M O R E D E T A I L SSulzer Chemtech AGMario RozaPostfach 65CH-8404 WinterthurSwitzerlandTelephone +41 (0)52-262 60 08 Fax +41 (0)52-262 00 67E-mail mario.roza@sulzer.com

5 Shell HiFi trays are designed to handle large liquid loads. Their designmaximizes downcomer capacity while maintaining a high active area for vapor.

6 The Application matrix; arranged by application range going downwards in the table leads to a product with, if the design is optimized, a higher capacityfor a given tower diameter.

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Increasingcapacity

Atmospheric to intermediate pressure,low and intermediateliquid load

Conventional tray

MVG tray

MVGT tray

Calming Section tray, VortexTray

Calming Section Plus tray

ConSep tray

High liquid load,high pressure

Conventional tray

MVG (T) tray

Calming Section tray, VortexTray

HiFi tray

HiFi Plus tray

ConSep tray

Glycol(low liquid load,high pressure)

Conventional tray

Mellapak + Mistmat

MellapakPlus + Mistmat + Swirldeck

Swirl Tube tray

Low to atmosphericpressure, low and intermediateliquid load

Conventional trays, Nutter Ring

Mellapak

MellapakPlus

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