Aromatics

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Aromatics

Koch-Glitsch can meet your aromatics mass transfer needs whether it is a new tower or a revamp. Our current and developing technologies allow designs that provide a total solution. Our sales, specialists and designers can work with you to meet geometry, utility, product quality and schedule needs. Please contact us to discuss how our high capacity trays and packings can enhance your operations

Equipment | References | Case Studies | Technical Papers | FAQ

Koch-Glitsch Equipment
Koch-Glitsch SUPERFRAC^Ž trays can increase the capacity of your aromatics towers as much as 25%. We have recently deployed these trays in benzene fractionators and ethylbenzene columns. Benzene fractionation capacity is often a bottleneck in a modern ethylbenzene plant, and our SUPERFRAC^Ž trays have added 10-20% additional capacity for several producers.

We can also provide structured packing in aromatics columns to achieve additional capacity or efficiency. With the successful introduction of our FLEXIPAC^Ž HC^Ž packing the customer can achieve additional capacity while maintaining efficiency, achieve additional efficiency at the existing capacity or we can also optimize a solution to include both capacity and efficiency enhancements. For example, an ethylbenzene/styrene splitter can achieve additional stages and potentially 25% more capacity. Also, ethylbenzene and back-end columns are also good candidates for packing. The HC^Ž packing provides the opportunity to deploy different packings in the various column beds to utilize existing column diameters or optimize the size of a new tower.

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References




Name:	Benzene/Toluene column
Service:	Separates benzene and toluene from ethylbenzene in styrene
unitExperience:	Six columns packed with FLEXIPACŽ and/or FLEXIPACŽ HC^Ž packing
Other Statistics:	Column diameter ranges from 3.3 feet (1.0 meters) to 9 feet (2.7 meters)



Name:	EB/styrene splitter, EB recycle column
Service:	Separates ethylbenzene from styrene and heavier compounds in styrene
unitExperience:	More than 25 columns packed with GEMPAK^Ž, FLEXIPACŽ and/or FLEXIPACŽ HC^Ž packing
Other Statistics:	Column diameter ranges from 7.5 feet (2.3 meters) to over 29 feet (~9 meters)



Name:	Styrene finishing
Service:	Separates styrene from heavier compounds in styrene
unitExperience:	Six columns packed with GEMPAK^Ž, FLEXIPACŽ and/or FLEXIPACŽ HC^Ž packing
Other Statistics:	Column diameter ranges from 7 feet (2.1 meters) to 17.5 feet (~5.3 meters)



Name:	Benzene and EB fractionation
Service:	Separate benzene from EB; separate EB from heavier
unitExperience:	More than 9 columns in recent years with SUPERFRACŽ high capacity trays
Other Statistics:	Column diameter ranges from 7 feet (8 meters) to 19 feet (~5.8 meters)

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Case Studies
Revamp of a Heavy Aromatics Fractionator - Project Report 275

Increased Capacity and Greater Efficiency in Benzene and Toulene Towers - Project Report 111

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Technical Papers
FLEXIPAC^Ž HC^Ž a Structured Packing with Enhanced Capacity, Washington Group Technical Conference 2000
Request This Technical Article

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FAQ
Q: In aromatics service, when should I consider trays instead of packing?
A: There are a couple of scenarios that point to trays instead of packing. The first is how similar the liquid and vapor properties are. For example, when the vapor density is approaching the liquid density packing is not a good choice.
A second scenario to consider is when the relative volatility between the key separation components is high. With a large relative volatility, even slight maldistribution in the packing can become magnified quickly in a packed tower. In other words, in a horizontal cross section of the packing the composition can have significant variation. In a trayed tower the fluids get more frequent remixing such that variations get corrected on the subsequent tray.

Q: How do I find the flood point in my benzene fractionator?
A: There can be several ways to obtain this; each may depend on the exact separation and your existing hardware. The classic means of finding the flood point is to ramp the reflux rate up until the pressure drop begins to increase dramatically. This is usually a quick and easy method if the field instrumentation exists. A plot of the data can be very informative. This is usually better than increasing the feed rate because it may reduce the risk of generating too much product that does not meet specifications.

However, there are plenty of cases where the column may reach a limit before it is evident from the column pressure drop. To evaluate this situation one should monitor the overhead and bottom composition as the reflux rate is increased. This works great if you have an online analyzer. If analyzers are not available, one may be able to use a tray temperature similar to how tray temperature indications are used for inferred compositional control.

Q: Where is structured packing utilized in an ethylbenzene/styrene complex?
A: It is state of the art to use structured packing in the ethylbenzene/styrene splitter (EB recycle). Structured packing has also been deployed in benzene/toluene towers and finishing columns. Packing has been utilized in service very similar to ethylbenzene product and diethylbenzene/flux oil columns.

Q: How much incremental capacity can my EB recycle column (EB styrene splitter) achieve by replacing conventional structured packing with the Koch-Glitsch, LP FLEXIPAC^Ž HC^Ž High Capacity packing?
A: The range of capacity achieved by replacing conventional packing with FLEXIPAC^Ž HC^Ž packing can range from 10-40%. The actual number is dependent on your existing column configuration and process conditions. As with any revamp the reboiler and condenser duty should be evaluated. Also, a careful review of the capacity of existing distributors and inlet nozzles should be performed. With HC^Ž packing the size and efficiency can be optimized for each bed.

Q: I am trying to evaluate the efficiency of individual beds in my packed column, what are some tips on how to do that?
A: The best way to do this is by collecting interbed samples. This can be accomplished by drawing vapor samples between the beds or drawing a liquid sample from the collector. For large diameter towers, we recommend collection of samples from several locations throughout the column cross section. The sample point should protrude at least one-third of the diameter into the tower (one may also want to assess the composition near the wall). For vacuum columns, the samples should be chilled and remain chilled until analyzed to avoid loss of lighter components. Once the samples are correctly analyzed the user conducts material, component and energy balance then utilizes a simulation tool to determine which stage count matches the tested composition.

If interbed sampling is not feasible, the next option is to use the column temperature profile. This requires the user to close the material, component and energy balances then match the current column performance with a simulation. From there the simulation temperature profile can be matched with the measured temperature to approximate the location. This assumes several temperature indications are available on the column.
The last and least reliable technique is to use the pressure profile to match simulated stages to actual. Back to Top

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