Refractory Lining for Delayed Coker Drum Thermal Fatigue
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Delayed coking coke drums experience thermal fatigue and pressure boundary cracking due to transient thermal stresses during the quench and heat-up phases of the coking process, leading to potential drum bulging and mechanical stress issues.
Innovation Solution
A thermal buffering system using a monolithic, thermal shock-resistant, and erosion-resistant refractory lining is applied to the internal surface of the coke drum, particularly at areas prone to pressure boundary stress, with a suitable anchoring system to dissipate thermal stresses across the lining rather than the drum's pressure boundary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a steel drum is used for delayed coking, then the drum can withstand high pressure and temperature, but the drum experiences thermal fatigue and pressure boundary cracking due to transient thermal stresses
Solution Approach 1:
The patent applies a composite structure consisting of an inner refractory lining layer and an outer steel pressure boundary layer. The refractory lining (made of materials like alumina, silica, or magnesia) provides thermal shock resistance and protects the steel shell from transient thermal stresses, while the steel layer provides mechanical strength and pressure containment. This composite material approach resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
The refractory lining acts as an intermediary layer between the hot coke/steam environment and the steel pressure boundary. It mediates the thermal stresses by absorbing and dissipating thermal energy, preventing direct thermal shock to the steel drum. The lining serves as a buffer that protects the structural integrity of the steel shell during thermal cycling.
2Productivity
If the drum is subjected to rapid quenching to reduce cycle time, then productivity increases, but thermal stress and drum bulging increase
Solution Approach 1:
The refractory lining is installed beforehand as a protective cushion against thermal shock. During rapid quenching operations, the lining absorbs the thermal stress impact that would otherwise directly affect the steel drum, enabling faster cycle times without proportionally increasing thermal stress on the pressure boundary. The lining is pre-positioned to cushion against anticipated thermal shocks.
Solution Approach 2:
The patent changes the thermal parameters of the drum system by introducing a lining with different thermal properties (lower thermal conductivity, higher thermal shock resistance) compared to bare steel. This parameter change allows the drum to withstand more aggressive quenching conditions, thereby increasing productivity without linearly increasing thermal stress on the steel structure.
3Reliability
If internal cladding is applied to protect against sulfur corrosion, then corrosion resistance improves, but the complexity of manufacturing and installation increases
Solution Approach 1:
The refractory lining serves multiple functions simultaneously: it provides thermal shock resistance, protects against sulfur corrosion, and reduces thermal stress on the steel shell. By consolidating these protection functions into a single multi-functional lining system, the patent reduces overall system complexity compared to applying separate specialized claddings for each protection need.
Solution Approach 2:
The refractory lining combines protective properties against both thermal shock and chemical corrosion in a single material system. Materials like alumina-silica compositions provide both thermal stability and resistance to sulfur-containing environments, eliminating the need for separate corrosion protection layers and simplifying the overall drum construction.
4Reliability
If the drum shell thickness is increased to reduce thermal stress, then thermal fatigue resistance improves, but the drum weight and capital cost increase
Solution Approach 1:
Instead of increasing steel shell thickness to improve thermal fatigue resistance, the patent uses a composite structure with a relatively thin steel shell supported by a thick refractory lining. The refractory material (which is lighter than equivalent steel thickness) provides the thermal protection, while the steel shell maintains adequate structural strength. This composite approach reduces overall weight compared to a thick steel shell design.
Solution Approach 2:
The refractory lining acts as an intermediary that bears the thermal fatigue load, allowing the steel shell to remain thinner. The lining absorbs the thermal cycling stresses, so the steel pressure boundary doesn't need to be oversized for thermal protection. This mediator approach enables weight reduction while maintaining thermal fatigue resistance.
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 solution significantly reduces thermal fatigue in the coke drum shell and minimizes skirt-to-shell cracking, allowing for shorter quench phases and reduced cycle times, potentially eliminating the need for internal cladding and reducing erosion from high-pressure cutting water, while maintaining refractory integrity through coke impregnation.
Implementation Method 1
A thermal buffering system using a monolithic, thermal shock-resistant, and erosion-resistant refractory lining is applied to the internal surface of the coke drum... to dissipate thermal stresses across the lining rather than the drum's pressure boundary
Implementation Method 2
A thermal buffering system using a monolithic, thermal shock-resistant, and erosion-resistant refractory lining is applied to the internal surface of the coke drum
Implementation Method 3
maintaining refractory integrity through coke impregnation
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A delayed coking unit has a thermal shock-resistant, erosion-resistant internal lining to reduce thermally-induced mechanical stresses in the pressure boundary of the coke drum. The lining is effective to reduce or mitigate the transient thermal stress that occurs in the pressure boundary of the coke drum and to reduce or minimize the high thermal stress resulting from temperature differentials at the skirt-to-shell junction.