Two-Stage Hydrocracking HPNA Removal via Upstream Hydrogenation
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Solution Overview
Problem
Two-step hydrocracking processes face challenges in eliminating heavy polycyclic aromatic compounds (HPNAs), leading to catalyst deactivation and reduced yield of upgradable products due to their accumulation in the recycle loop, resulting in economic losses.
Innovation Solution
A two-step hydrocracking process with a hydrogenation step upstream of the second hydrocracking step, using a specific hydrogenation catalyst and operating conditions, to minimize HPNA formation and maximize upgradable product yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a purge is installed to remove HPNAs from the recycle loop, then HPNA accumulation and catalyst deactivation are reduced, but upgradable products are lost with the purge stream
Solution Approach 1:
The patent extracts and removes HPNAs from the recycle loop through a dedicated purge stream. By installing a purge at the bottom of the fractionation column, HPNAs are selectively removed from the system preventing their accumulation and the associated catalyst deactivation, while minimizing the loss of valuable upgradable products through optimized purge rate control.
Solution Approach 2:
The patent optimizes the purge rate as a controllable parameter to balance two opposing effects: removing enough HPNAs to prevent catalyst deactivation while minimizing the loss of upgradable products. The purge rate is adjusted to achieve the optimal trade-off between maintaining catalyst performance and maximizing product yield.
2Duration of action of stationary object
If the purge rate is increased to remove more HPNAs, then catalyst deactivation is reduced, but the yield of upgradable products decreases
Solution Approach 1:
The patent treats the purge rate as an optimized parameter that balances catalyst longevity with product yield. By carefully controlling the purge rate within specific ranges, the system achieves extended catalyst cycle times while minimizing the loss of upgradable products, preventing both premature catalyst deactivation and excessive product loss.
Solution Approach 2:
The system uses feedback control where the purge rate is adjusted based on monitoring of HPNA accumulation and catalyst performance. This allows dynamic optimization of the purge rate to maintain catalyst activity while maximizing product yield, adapting to changing process conditions and catalyst aging.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces HPNA accumulation, prolongs catalyst cycle time, and maximizes the yield of middle distillates by minimizing the need for purging, thereby reducing economic losses.
Implementation Method 1
a step of hydrogenating at least one portion of the unconverted heavy liquid fraction resulting from step d) and optionally purged, said step f) taking place, in the presence of hydrogen and a hydrogenation catalyst
Implementation Method 2
a step of hydrocracking at least one portion of the effluent resulting from step a), the hydrocracking step b) taking place, in the presence of hydrogen and at least one hydrocracking catalyst
Data Source
AI summary
The present invention is based on the use of a two-step hydrocracking process comprising a step of hydrogenation placed upstream of the second hydrocracking step, the hydrogenation step treating the unconverted liquid fraction separated in the distillation step in the presence of a specific hydrogenation catalyst. Furthermore, the hydrogenation step and second hydrocracking step are carried out under specific operating conditions and in particular under very specific temperature conditions.