Pump-Around Loop Decharring in Plastic Pyrolysis Steam Crackers
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Solution Overview
Problem
The presence of char and coke deposits on the internal surfaces of steam cracking furnaces and plastic pyrolysis vessels reduces heat transfer, alters equipment composition, and restricts material flow, necessitating improved removal processes.
Innovation Solution
A process involving fluid isolation of a pump-around loop section, followed by introduction of an aqueous fluid and oxidant to combust char, and subsequent heating to produce a mixture that is introduced into the steam cracking furnace, effectively removing char and coke deposits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional operation continues without interruption, then production output is maintained, but deposits accumulate on internal surfaces reducing heat transfer efficiency and causing equipment deterioration
Solution Approach 1:
The patent implements continuous online decharring by circulating aqueous fluid and oxidant through the pump-around loop during normal operation, eliminating the need for shutdowns while maintaining heat transfer efficiency and removing deposits continuously
Solution Approach 2:
The system uses the existing pump-around loop infrastructure to deliver decharring agents (aqueous fluid and oxidant) through the furnace tubes, allowing the equipment to service itself by removing deposits using its own circulation system
2Reliability
If the process is shut down for maintenance to remove deposits, then heat transfer efficiency is restored, but production output is lost during the shutdown period
Solution Approach 1:
The decharring process operates continuously during normal production, eliminating shutdowns entirely by maintaining constant circulation of decharring agents through the pump-around loop
Solution Approach 2:
Deposits are removed preventively through continuous circulation of aqueous fluid and oxidant before they can significantly impair heat transfer, rather than waiting for shutdown maintenance
3Reliability
If aqueous fluid and oxidant are introduced into the pump-around loop, then deposits are combusted and removed, but system complexity increases due to fluid isolation requirements
Solution Approach 1:
The pump-around loop serves dual functions: normal process heat transfer during operation and deposit removal during decharring, eliminating the need for separate isolation systems by using the existing loop infrastructure for both purposes
Solution Approach 2:
Aqueous fluid acts as an intermediary carrier that delivers oxidant to the deposits and facilitates combustion reactions, enabling effective deposit removal through a chemical mediation process
4Duration of action of stationary object
If char and coke deposits are present on internal surfaces, then equipment operates continuously, but material flow becomes restricted and plugging occurs
Solution Approach 1:
Continuous circulation of aqueous fluid and oxidant through the pump-around loop maintains constant deposit removal, preventing flow restrictions and plugging while enabling uninterrupted operation
Solution Approach 2:
The system preemptively counteracts deposit accumulation by continuously introducing decharring agents that combust deposits before they can restrict material flow or cause plugging
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
Enhances heat transfer and prevents plugging by efficiently removing char and coke, maintaining furnace efficiency and operation.
Implementation Method 1
An aqueous fluid and oxidant from the aqueous fluid and oxidant source can be introduced into the first end of the isolated section of the pump-around loop. The aqueous fluid and oxidant can be heated by flowing the aqueous fluid and oxidant through the fluidly isolated section of the pump-around loop to produce a first heated mixture that can include steam and at least one of char, any unreacted oxidant, and a combustion product produced by combusting at least a portion of the char.
Implementation Method 2
The aqueous fluid and oxidant can be heated by flowing the aqueous fluid and oxidant through the fluidly isolated section of the pump-around loop to produce a first heated mixture that can include steam
Implementation Method 3
The first heated mixture can flow through the second conduit to produce a second heated mixture. The second heated mixture can be introduced into a radiant section of the steam cracking furnace.
Data Source
AI summary
Processes for removing deposits from a pump-around loop or simply loop. The process can include isolating a first and a second end of the loop in fluid communication with a vessel to provide an isolated section. The isolated section can include a first conduit disposed within a convection section of a steam cracking furnace or a heat exchanger that is external to the steam cracking furnace that can include char therein. The first end can be connected to an aqueous fluid/oxidant source. The second end can be connected to a second conduit disposed within the convection section. An aqueous fluid/oxidant mixture can be introduced into the first end that can be heated by flowing through the isolated section. The heated mixture can flow through the second conduit to produce a second heated mixture that can be introduced into a radiant section of the steam cracking furnace.