4 simple ways to convert turnarounds into profitable tower upgrade opportunities

With planned outages commonly occurring at intervals of 2-5 years, a refinery turnaround is a prime opportunity to replace column and separator internals with the newest available technology. Planning for an outage with a “replacement-in-kind” strategy will address lost performance from refinery equipment due to normal wear and tear. However, most column internals can be upgraded for higher capacity, more flexibility, or greater efficiency at close to the same cost as an in-kind equipment replacement.

#1 – Upgrade Performance of Existing Packing or Trays
Adding column capacity to debottleneck existing operations or to create “room” for future capacity creep can often be accomplished with a simple modification to the existing design. High performance tray decks, like Sulzer MVGTM trays, can achieve up to a 15% capacity increase in entrainment-limited applications. MVG trays can fit within existing column weld-ins and ring supports for a similar cost to replacement-in-kind moveable valve trays. If increased liquid handling is required, the use of Z-bars can adapt the existing weld-ins for larger downcomers without the need for costly welding to the vessel wall. Similarly, standard structured packing can easily be replaced with high performance packings such as MellapakPlusTM and MellagridTM, providing capacity increases of up to 40% at a cost that is comparable to the existing equipment without requiring other column modifications.

#2 – Optimize Stripping Tray Open Area
Column bottom, side column, or Hydrotreater Product stripping trays are often of a single design in order to simplify equipment layout and production. In operation, however, the bottom tray has a far lower vapor rate than the top tray due to the stripping effect. Since the design will have to accommodate the highest loads, the bottom trays’ performance will likely suffer due to weeping. Because of this, stripping trays can often have an efficiency of 25% or less. By making a simple change to the design – reducing the open area on the lower trays appropriate to the predicted vapor rate, the refiner can see a large impact on stripping efficiency or can take advantage of the improved stripping by reducing energy / steam usage.

#3 – Upgrade Separator Internals
Separators, accumulators, receivers, and knockouts are often the forgotten vessels that can consume downstream capacity when operating with poor performance. Since entrainment generation is typically exponential, a small shortfall in separator capacity can result in a very large increase in liquid losses. Upgrading an existing standard mesh or demister pad with a higher capacity Sulzer KnitMesh™ Mist Eliminator or Mellachevron™ can reduce carryover of liquid or free water to downstream processes from existing separators that are forced to operate with a higher superficial velocity.

#4 – Improve Tray Fouling Resistance
Adding anti-fouling features to a replacement tray can be a simple fix to increase run length between cleanings or turnarounds in heavy fouling services. Adjusting downcomer design and incorporating push valves on the active decks can improve the washing effect of the tray liquid traffic to prevent fouling buildup. These features can typically be incorporated into the trays without the need to weld on the column wall.

Other Considerations
Making tower and vessel upgrades rather than in-kind replacements takes some extra planning and strategy but the payout is often extremely high. You have to start early so you have time to evaluate, not only the tower internals in question, but also the feeds, draws, nozzles, and auxiliary equipment as well. Sulzer’s process applications team can help evaluate all your possible options.


View More

  • Safeguard packed column efficiency with proper liquid distribution

    Initial liquid distribution directly affects the efficiency of structured and random packing beds. As such, some form of flow test should be conducted to validate distributor performance prior to column startup. Steady state water flow testing is the most common method of testing distributors. It can ...

  • Separator technology reduces refinery operating costs and downtime

    A US refining company contacted us to discuss a separation problem in the feed to an alkylation process. Caustic entrainment from their selective hydrogenation unit was poisoning the hydrofluoric acid catalyst in the alkylation unit. The continuous phase feed to the alkylation unit consisted of ~180m3/hr ...

  • Tray designs for extreme fouling applications

    Today refiners experience a lot of problems with processing of opportunity or heavy crudes. Such crudes have very high sulfur content and require the addition of amine scavengers before desalting. These amines decompose in the heater and create ammonium chlorides in the presence of water in the top of ...

  • Anti-fouling trays maximize coker main fractionator profitability

    The Coker Main Fractionator is systematically subjected to harsh operating conditions that can lead to deteriorating efficiency and performance due to coking and fouling. Poor reliability results in loss of profitable coking margins for the refinery. The main fractionator vapor feed from the coke drum ...

  • Improve separation in your column by increasing the number of trays

    Refiners often face revamp challenges when trying to improve separation within an existing column. Improving diesel recovery from gas oil, splitting benzene precursors from naphtha reformer charge, or simply minimizing product overlaps after capacity creep can all be difficult when limited by a fi xed ...

  • Gain 5-10% efficiency with this simple 4-pass tray revamp

    The design of 4-pass trays can be complex. It not only requires a close evaluation of the mechanical design but also the process response to that design at various flow rates. The balancing of the fluid flows across the tray can have a substantial effect on the tray performance, namely efficiency. Many ...

  • Proper design of mass transfer internals in the FCC flue gas scrubber can help reduce PM emissions

    The EPA’s New Source Performance Standards (40 C.F.R. §60.100-1-0, subpart Ja) regulates refinery particulate emissions, including the discharge of catalyst fines from the FCCU flue gas scrubber stack. Because refiners have traditionally correlated particulate matter (PM) emissions with FCCU ...

  • Improve fouling resistance in your wastewater benzene stripper

    Benzene stripper columns, built so that refineries can meet the National Emissions Standards for Hazardous Air Pollutants (NESHAP), operate with several unique conditions – low vapor rates, high liquid loads, and a high tendency toward fouling make designing well-balanced, effective internals difficult. The ...

  • Important tray design features that improve column operating reliability

    How often does Maintenance personnel open a column during a shutdown and find tray panels fallen without any obvious damage? How about tray valves stuck in the bottoms pump suction? While the initial reaction may be to blame faulty installation where the hardware was not properly tightened, the answer ...

  • Green design practices: focus on efficiency

    Green design is more than recycling scrap materials or calculating carbon footprints. It minimizes negative environmental impact through skillful design and operating practices to produce efficient, better-functioning processes. Because green practices reduce resource requirements, in many cases, they ...

  • Responsive image Shut-off valves
  • Responsive image Swagelok® Valves
  • Responsive image Extensive tray portfolio
  • Responsive image Catalysts for optimal performance
  • Responsive image Valves and Pumps for the Energy Industry
  • Responsive image Oil and gas water treatment applications
  • Responsive image The eco-friendly sulphur recovery solution
  • Responsive image Atlas Copco Expander Compressors