Expansion Joint Inner Sleeve Assembly for Bellows Heat and Coking Control
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Solution Overview
Problem
Expansion joints in propylene production plants from propane gas face challenges in protecting the expansion bellows from high temperatures and preventing coking due to thermal expansion and hydrocarbon stagnation, leading to potential damage and yield reduction.
Innovation Solution
An expansion joint design featuring an expanded wall with an axial gap, a sealed chamber filled with gas, and an inner sleeve assembly that includes pressurized sealed chambers to prevent hydrocarbon ingress and maintain high temperatures away from the bellows, using stainless steel components and a hyperbaric pressure chamber to prevent coking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the expansion bellows is exposed to high-temperature process fluid, then the expansion joint can handle high-temperature applications, but the bellows is damaged due to overheating
Solution Approach 1:
The expansion joint is divided into distinct functional zones: a hot zone containing the process fluid and bellows, and a cold zone containing the insulated chamber. This segmentation allows the bellows to operate in high temperature while the insulation protects critical components from thermal damage.
Solution Approach 2:
An insulation material is introduced as an intermediary substance between the hot process fluid and the bellows/expanded wall assembly. This intermediary layer blocks heat transfer, protecting the bellows from thermal damage while allowing the system to handle high-temperature processes.
2Temperature
If the chamber is separated into two smaller chambers with insulation material, then thermal protection is improved, but openings are created allowing process fluid to escape and cause coking
Solution Approach 1:
The pressure parameter of the inert gas in the insulated chamber is increased to create a hyperbaric condition. This pressure differential prevents process fluid from leaking into the insulated chamber, eliminating the coking problem while maintaining thermal protection.
Solution Approach 2:
An inert gas atmosphere is introduced into the insulated chamber to replace the previous configuration. This inert environment prevents coking by eliminating hydrocarbon stagnation, and when pressurized, it also prevents process fluid leakage into the chamber.
3Object-affected harmful factors
If flushing with fresh propane gas is used to prevent coking, then coking is avoided, but the temperature of the process fluid decreases and yield is reduced
Solution Approach 1:
Instead of using fresh propane gas flushing, an inert gas atmosphere is created in the insulated chamber. This eliminates the need for temperature differential-driven flushing, preventing both coking and the associated temperature drop and yield reduction.
Solution Approach 2:
A pressurized inert gas system is used to create a hyperbaric environment that prevents process fluid leakage. This pneumatic approach replaces the need for continuous gas flushing, maintaining process temperature and productivity.
4Adaptability or versatility
If the expanded wall and inner sleeve are designed with axial gaps, then thermal expansion is accommodated, but dead zones are created where hydrocarbon material stagnates and cokes
Solution Approach 1:
The insulated chamber is filled with inert gas at a pressure higher than the process pressure. This creates a pressure barrier that prevents process fluid from entering dead zones through axial gaps, eliminating hydrocarbon stagnation and coking while preserving the gaps for thermal expansion accommodation.
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
The solution effectively protects the expansion bellows from high temperatures, prevents coking, and maintains the integrity of the expansion joint under high-temperature and pressure conditions, ensuring reliable operation and propylene yield in propylene production plants.
Implementation Method 1
The at least one sealed chamber is filled with an inert gas which absorbs thermal energy from a process fluid flowing across a flow channel within the expansion joint, thereby protecting an expansion bellows of the expansion joint from high temperatures
Implementation Method 2
The at least one sealed chamber is filled with an inert gas which absorbs thermal energy from a process fluid flowing across a flow channel within the expansion joint, thereby protecting an expansion bellows of the expansion joint from high temperatures and which prevents a leakage of process fluid into the at least one sealed chamber, thereby eliminating conditions for a coking
Data Source
AI summary
The invention relates to an expansion joint (1) for joining two adjacent parts of a pipe. The expansion joint (1) comprises an expansion bellows (5), an expanded wall (2) and an inner sleeve assembly (8). The expanded wall (2) comprises a first wall part (3) and a second wall part (4), wherein the first wall part (3) and the second wall part (4) are spaced apart from each other axially by an axial gap. The expansion bellows (5) is connected to the first wall part (3) and to the second wall part (4) such that the axial gap between the first wall part (3) and the second wall part (4) is closed and such that the first wall part (3) and the second wall part (4) are connected flexibly. The expanded wall (2) and the inner sleeve assembly (8) limit at least one sealed chamber (9, 10) between each other, and the at least one sealed chamber (9, 10) is filled by a first gas.