PRODUCTION & PROCESSING
BLUE-SKY THINKING
Ali Zandieh Shirazi details how an engineering fi rm’s customers inspired a game-changing valve design for major refi neries
C
racking is essential for converting long alkanes into shorter, more useful hydrocarbons. Thermal
processes were originally used for this work, though nowadays, virtually all cracking is done using catalysts. The latter process is preferred because it generates greater volumes of high- octane-rating gasoline and other valuable by-products. However, fl uid catalytic cracking (FCC) is also hazardous without due care, especially during turnarounds when the risk of fl ash fi re and injury is particularly high. In recent months, engineering
expert IMI has examined this area closely with customers, developing a breakthrough engineering solution that minimises turnaround risk and drastically reduces the time it takes to bring a refi nery back online.
WHY ISOLATION IS NON-NEGOTIABLE It’s critical to isolate a refi nery’s reactor and main column during a shutdown procedure. If this is not done correctly, fl ammable hydrocarbons will fl ow into the air side of the FCC unit, creating highly volatile conditions. But this is not the only concern.
IMI’s customers inspired a gamechanging new valve design for refi neries
Until recently, isolation of the reactor
and main column meant removing a large ring – typically between 40 and 85in in diameter – and installing a plated blind. This blinding location can be found at the reactor overhead vapour inlet to the main column. When this is parted, personnel are exposed to a rich stream of hydrocarbons at 300°F. Site staff work in high-temperature proximity suits and under fresh air for protection. It’s diff icult and dangerous work,
but also essential for keeping an FCC unit working optimally. Planned turnarounds are necessary for routine maintenance and upgrades across all heavy industries. Without these periods, plants would fall into disrepair and run a much higher risk of downtime, not to mention create much lower-quality yields. Reactors must also be isolated from the main column to deliver suff icient heat to controllably raise the reactor/regen temperature. Isolation failure caused a major explosion at the Torrance refi nery
in California, USA in February 2018. Maintenance preparations inadvertently caused a pressure deviation, allowing hydrocarbons to backfl ow and ignite in the site’s electrostatic precipitator. The result was an explosion so large it registered a magnitude 1.7 tremor.
RETHINKING THE DISCONNECT Through ongoing consultation with site managers across the world, it became clear that a new approach with easier actuation would off er considerable advantages. During the design phase, IMI’s principal concern was safety. First, it eliminated conditions that could lead to an incident similar to the one seen at the Torrance site. Second, it minimised engineers’ contact with streams of high-temperature hydrocarbons.
www.engineerlive.com
27
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56
