logo


Three cost effective ways to strengthen trays against uplift

Several common operating conditions cause tray damage, including high liquid levels, free water flashing at the bottom of the column, and excessive pressure drop. The result can be an expensive shutdown causing lost production and profit. Increasing tray thickness can be a first approach for strengthening the tray, but this can increase the material cost of the trays by 50% or more. Sulzer commonly uses three simple cost effective alternatives to increase tray strength in new designs.

Alternative #1: Increase the Integral Truss Height and Width
Integral tray trusses, are formed from the tray panel and serve to support the tray decks by acting as minor beams. Maximizing the truss height and width significantly increases the strength of the tray decks while only slightly increasing the material cost of the trays. The tray trusses can interfere with the flow of the vapor/liquid mixture in the vapor space below the truss limiting capacity, so it’s important to properly orient deep trusses parallel to the froth flow to prevent this interference.

Alternative #2: Statically Fix the Truss Ends
As a standard design, integral trusses are typically unsupported at the truss ends. Fixing the ends of the trusses to a clip at the vessel shell or to another tray part will increase the mechanical load that the truss can handle. Sulzer typically utilizes a shear clip which bolts to the truss that is fixed to the vessel shell by welding. If welding to the shell is not allowed, there are alternate options such as welding to the underside of the support ring, as shown in the picture below.

Alternative #3: Strengthen Panel Connections
Although frictional connectors are used in many standard duty tray designs, upgrades in strength can be attained by using either Lip-SlotTM connections or through-bolted design. Lip-Slot tray connections use a mechanically integrated design to increase strength between panels and are used for light to heavy duty applications because of their strength and ease of installation. Through-bolted trusses with short (less than 6”) bolt spacings are extremely strong and reliable and are typically used for heavy and ultra-heavy duty designs.

Mechanical Integrity is Critical to Proper Tray Design
There are a variety of ways to safely and effectively strengthen trays to improve reliability in demanding applications. The key is to use the proper design to match the column operating requirements.

DOWNLOAD LITERATURE

Sponsor:

Categories:

View More

  • 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 ...

  • 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 ...

  • Maximizing light cycle oil recovery in the FCC main fractionator

    Refiners operating FCCU's have adjusted their operating strategies to maximize light cycle oil production to meet the increased demand for automotive diesel. Catalyst formulations and reactor conditions can alter yields, but the refinery cannot take full advantage of the increased LCO recovery without ...