logo

Back

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 overhead is characterized by a tendency for further cracking, as well as the presence of fine coke particles carried from the drums. The hottest zones of the column (bottom quench, wash, and heavy gas oil sections) are particularly susceptible to accumulation of coke, ultimately forcing frequent shutdowns for maintenance. Internals specifically designed to resist fouling and increase run length can positively affect unit profitability.

Anti-Fouling Design Strategy
Sulzer VG AFTM trays can be particularly useful in fouling services like the heavy coker gas oil section, above the wash zone. While the wash sprays are designed to knock down coke particulate and quench the unstable feed, coke still often ends up in the HCGO trays. While an anti-fouling tray cannot prevent coking, its unique features can substantially delay the onset of coke-related problems. Specifically, push valves ensure as strong, uniform liquid flow across the tray deck that moves the froth and associated coke particles forward, minimizing stagnant zones that could allow fouling to accumulate. Fixed, large open area V-GridTM valves are also used for fouling resistance. SVGTM or LVGTM valves force the vapor laterally across the deck in a sweeping motion to prevent fouling.

VG AF trays typically use sloped or stepped outlet weirs in HCGO service to allow particulates to be swept into the downcomer from the active zone. Highly sloped downcomers can also be used to minimize residence time in the downcomer, thus reducing the risk of further cracking.

These advanced fouling-resistant technologies have been successfully applied in a variety of commercial applications. The net result is a significant increase of unit on-stream time and a reduction in operating and maintenance expenses.

DOWNLOAD LITERATURE

Sponsor:

Categories:

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 Worldwide refinery processing review
  • Responsive image Reinventing reliability
  • Responsive image ProTreat® mass transfer rate based simulation
  • Responsive image Corrosion control
  • Responsive image The sulphur processing expert
  • Responsive image Galexia™ hydroprocessing platform
  • Responsive image Processing heavy canadian crude
  • Responsive image PROVALVE® Fixed Valve
  • Responsive image Extensive tray portfolio
  • Responsive image Shut-off valves
  • Responsive image OpX® Digital