18 Questions
What is the purpose of the coil heater in the Tervahl T process?
To heat the feedstock to the desired temperature
What is the primary role of the soaking drum in both the Tervahl T and Tervahl H processes?
To hold the heated feedstock for a specified residence time
What happens to the gas and oil mixture from the soaking drum effluent in the Tervahl H process?
Mixed with recycle hydrogen and separated in a hot separator
In the Tervahl H process, what happens to the liquids from the hot and cold separator?
Sent to the stabilizer section for separation of purge gas and synthetic crude
What is done to the gas produced from the Tervahl T process?
Used as fuel
What temperature range characterizes vapor-phase cracking?
>500ºC to <50 psi
What is the purpose of the distillate heater in the thermal distillate cracking process?
To achieve cracking under high temperature and pressure conditions
Where is the heavy gas oil fraction taken from the combi tower typically routed to?
Surge drum
What happens to the vacuum-flashed residuum from the vacuum flasher in the thermal distillate cracking process?
Used as refinery fuel
What does routing heavy gas oil from both the vacuum flasher and combi tower to the distillate heater achieve in the thermal distillate cracking process?
Complete conversion of heavy gas oil
What is a possible alternative use for light gas oil from the combi tower in the thermal distillate cracking process?
Used as a cutter stock
How does the flexibility of feedstock and product requirements impact the thermal distillate cracking process?
By allowing optimization of conversion through adjustments of heavy gas oil recycling
What is the main purpose of selective cracking in the context of thermal distillate cracking?
To prevent fouling caused by stable low-boiling materials
What role does heavy gas oil play in the Shell thermal distillate cracking process?
It is converted to light gas oil mostly
Why does selective process selectively convert stable low-boiling materials?
To prevent fouling and reduce undesired byproducts
What is the primary benefit of converting heavy gas oil to light gas oil in thermal distillate cracking?
Minimization of coke formation
How does stable low-boiling material affect efficiency in a thermal distillate cracking system?
Reduces efficiency by leading to fouling and undesired byproducts
What distinguishes Shell thermal distillate cracking from other processes?
Converting high-boiling feedstocks to lower-boiling products
Learn about the Tervahl T process and its components such as feedstock heating, stabilization, residence time, and quenching. Understand the steps involved in this thermal cracking process.
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