On methods to reduce energy consumption in FCC units and the utilization of low-temperature heat, as well as the issue of eliminating steam heating in absorption stabilization systems
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As the title suggests: In FCC units, especially those for heavy oil, there is an overall excess of heat – this is not only evident in the regeneration and distillation systems; there is also an excess of heat in these FCC units. The energy consumption of FCC units depends not only on minimizing pressure drops and reducing energy use in large-scale units, but also on making use of the low-temperature heat generated by the absorption and stabilization systems. 1. The issue of eliminating steam heating in the absorption and stabilization systems (how do people address the heat supply needs of the desorption tower and stabilization tower?).
1. If incomplete regeneration technology is used, the recovery and utilization of CO definitely play a crucial role. It’s a pity that domestic development and related equipment in this area are not very advanced! 2. In the catalytic cracking designs of the 1990s, it was common to use the intermediate section as a heat source that provided stable heat; however, later designs gradually switched to using steam as the heat source (in my opinion, steam seems to be a more stable heat source!) In some cases where an issue occurs in the middle section, it needs to be removed. ), this involves the issue of heat exchange network equilibrium! Our facility originally had equipment for generating power from low-temperature waste heat, but that project was abandoned later on! 3. Current designs mostly focus on the individual units, with little consideration given to the heat exchange balance across the entire plant. Regarding this issue, many design institutes in China have already started working on it: the excess heat from catalytic cracking is used as a heat source for gas separation, and part of it is utilized for heating indoor spaces throughout the plant during winter! 4. Personally, I believe that from the design stage, energy-saving measures should be taken into account for a system; adding elements later on will disrupt the existing balance, and sometimes it seems to yield half the results with twice the effort!
2. Heat supply temperature: The heat supply temperature for the FCC feed (normal slag) is around 150°C. Has this target been achieved by everyone?
This used to be the rule here, and that’s what we did as well!
Low-temperature heat is recovered using low-temperature hot water.
We cannot reach this temperature; it’s around 140 degrees
How is low-temperature heat recovered using hot water? Which heat exchangers are involved in this process?
Top circulation oil, diesel, external slurry oil
The desorption tower can use light diesel or gasoline from the stabilizer bottom as a heat source, with an additional source used as well.