Steam Cracking Coke Trap with Quench Bypass Emptying
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Solution Overview
Problem
Existing steam cracking processes require plant shutdown for effective coke removal, which disrupts regular operation and is inefficient.
Innovation Solution
A process and plant design incorporating a coke trap that retains coke during normal operation and is emptied using a withdrawal stream bypassing the quench heat exchanger, allowing continuous coke removal without interrupting the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coke trap is used to remove coke during normal operation, then coke removal effectiveness is improved, but device complexity increases
Solution Approach 1:
A coke trap is introduced as an intermediary device between the cracking furnace and quench heat exchanger. This trap accumulates coke particles during normal operation and can be emptied periodically using a withdrawal stream, effectively removing coke without requiring plant shutdown while maintaining a relatively simple structural addition to the existing process flow
Solution Approach 2:
The coke trap performs preliminary coke accumulation during normal operation before a planned emptying cycle. By collecting coke gradually and emptying it periodically using withdrawal stream, the system prepares for maintenance in advance rather than responding to critical coke buildup, enabling continuous operation with minimal interruption
2Reliability
If the plant is shut down for coke removal, then coke removal effectiveness is improved, but productivity deteriorates
Solution Approach 1:
The system enables continuous operation by integrating coke removal into the normal process flow. The coke trap accumulates coke during productive operation and is emptied using withdrawal stream that bypasses the quench heat exchanger, allowing coke removal to occur without interrupting the main cracking process and maintaining continuous productivity
Solution Approach 2:
The harmful coke is extracted from the main process flow and isolated in a separate coke trap. This extracted coke can then be removed using a dedicated withdrawal stream without affecting the continuous operation of the cracking furnace and product formation, separating the maintenance function from the production function
3Productivity
If coke is not removed regularly, then productivity is maintained, but harmful factors increase
Solution Approach 1:
The system incorporates a feedback mechanism where the coke trap monitors coke accumulation and triggers periodic emptying operations. When coke reaches a certain level in the trap, the system activates withdrawal stream to remove it, preventing harmful accumulation while maintaining continuous productivity through automatic cycle management
Solution Approach 2:
The harmful coke that would otherwise require plant shutdown for removal is converted into a manageable byproduct. By using withdrawal stream to periodically empty the coke trap, the system transforms the harmful accumulation problem into a controlled, periodic discharge process that maintains continuous operation and even recovers some energy through the withdrawal stream heating
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
Enables continuous coke removal, reducing maintenance time, enhancing plant safety, and improving product stream purity while minimizing environmental impact and operational costs.
Implementation Method 1
a coke trap and adapted to retain the coke
Implementation Method 2
the inlet being located downstream of the cracking furnace and upstream of the quench heat exchanger
Implementation Method 3
the cracked gas withdrawn from a cracking furnace, which is initially present at a temperature of typically 750 to 875° C., must be cooled as rapidly as possible
Implementation Method 4
the coke trap is emptied in a second mode of operation using a withdrawal stream withdrawn from a cracking furnace used for said steam cracking, bypassing the quench heat exchanger
Data Source
AI summary
A process is disclosed for the production of hydrocarbons with removal of coke from a product stream. In a first mode, hydrocarbons and steam are subjected to steam cracking to obtain a cracked gas. The removal of coke from the steam is performed using a coke trap thus obtaining a coke-depleted cracking gas which is subjected to quench heat exchange in the first mode downstream of the coke trap, effecting cooling. Product stream is formed in the first operating mode using the cracked gas cooled in the quench heat exchange. The coke trap is emptied in a second mode using a stream extracted from a cracking furnace, bypassing the quench heat exchange, to obtain a coke stream. The coke stream in the second mode is passed to a coke collector.