This interactive application explores the feasibility of utilizing Solvent Deasphalted (SDA) pitch as a valuable feedstock for asphalt production. The primary goal is to assess how this strategy could increase coker capacity by diverting surplus vacuum residue. This section provides a high-level summary of the key findings related to both the valorization of SDA pitch and the critical engineering considerations for designing and operating large-scale heated storage tanks required for this purpose.
The core challenge lies in SDA pitch's inherent properties (hard and brittle), making it unsuitable for direct asphalt use. However, through controlled blending with specific flux oils, it can be transformed into marketable asphalt. This requires meticulous formulation to meet stringent quality standards (ASTM, AASHTO, EN).
Storing this pitch at high temperatures (150-200°C) to maintain fluidity presents significant engineering hurdles. The design of large storage tanks (>600 m³) must adhere to codes like API 650 (Appendix M for high temps), involving careful material selection, robust heating and insulation, and comprehensive safety systems.
Explore the sections below to delve into the specifics of asphalt standards, pitch properties, blending techniques, and the detailed engineering aspects of the required storage solutions.
This section delves into the transformation of SDA pitch into a marketable asphalt product. It covers the essential international standards that asphalt must meet, the typical properties of SDA pitch compared to paving asphalt, and the crucial blending processes required to modify the pitch. Understanding these aspects is key to determining the viability of selling SDA pitch-derived asphalt.
Successfully marketing asphalt requires adherence to globally recognized quality standards. These define the physical and performance characteristics for paving and other applications. Key international bodies include ASTM International, AASHTO (USA), and CEN (Europe for EN standards).
| Standard | Issuing Body | Asphalt Type | Details |
|---|
Click on a row for more details on key parameters and regions of use.
UOP SDA pitch is the heaviest stream from the SDA unit, concentrating asphaltenes, CCR, and metals. Its properties differ significantly from conventional asphalt binders, making it too hard and brittle for direct use in paving.
The chart visually compares key properties of typical SDA Pitch against a standard 60/70 penetration grade asphalt. This highlights the significant modifications needed for SDA pitch to meet paving specifications, particularly in terms of softening the pitch and improving its flexibility (ductility).
Since neat SDA pitch is unsuitable, blending with softer bituminous components or flux oils is essential. This section explores the types of flux oils, methods for assessing compatibility, and determining blend ratios.
Direct Sale of Unmodified SDA Pitch? Generally Not Feasible.
Why? Unmodified pitch is too hard, brittle, has low ductility, and high viscosity, leading to poor pavement performance and application difficulties.
Blending SDA Pitch with Other Components? Yes, Feasible & Predominant Strategy.
How? By physically mixing with flux oils (e.g., VGO, LCO, Aromatic Extracts) or softer bitumen grades to adjust properties to meet asphalt specifications. This aligns with producing "specification asphalts" without necessarily involving further chemical processing.
Various refinery streams can be used as flux oils. Their effectiveness depends on properties like aromaticity and viscosity. Highly aromatic flux oils are generally preferred for compatibility with asphaltene-rich pitch.
| Flux Oil Type | Source | Details |
|---|
Click on a row for more details on typical properties and advantages/disadvantages.
Blending incompatible streams can lead to asphaltene precipitation and sludge. Rigorous compatibility testing is crucial. Methods range from simple spot tests to more quantitative analyses like P-value or SBN/IN determination.
| Test Method | Principle | Details |
|---|
Click on a row for key outputs and relevance to SDA pitch blending.
Storing large volumes of SDA pitch at elevated temperatures (150-200°C) is a complex engineering challenge. This section outlines the critical design and construction aspects, including applicable codes, material selection for high-temperature and potentially corrosive service, heating and insulation strategies, foundation design considering thermal effects, mixing systems for homogeneity, and essential safety features. Proper engineering is vital for operational reliability and long-term asset integrity.
A comprehensive suite of industry standards governs the design of large, heated pitch storage tanks. API 650, especially Appendix M for elevated temperatures, is paramount.
| Standard | Aspect Covered | Details |
|---|
Click on a row for its key relevance to hot pitch storage.
Choosing materials involves considering temperature derating (API 650 App. M) and corrosion from high-sulfur pitch. Carbon steels like ASTM A516 Gr. 60/70 are common, with appropriate corrosion allowances.
| ASTM Grade | Min. Yield (Ambient) | Min. Tensile (Ambient) | Details |
|---|
Click on a row for key considerations. Note: Allowable stresses at operating temperature must be per API 650 App. M.
Maintaining pitch fluidity (150-200°C) requires efficient heating (hot oil systems often preferred) and robust insulation (e.g., mineral wool, calcium silicate) to minimize heat loss and manage CUI (Corrosion Under Insulation).
| Feature | Hot Oil | Steam | Electrical | Details |
|---|
Click row for more details on suitability for pitch.
| Material | Max Service Temp (°C) | k-value @ 175°C mean (W/mK)* | Details |
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Click row for pros & cons. *k-values are indicative; consult manufacturer data.
CUI is a major risk for hot (150-200°C) insulated tanks. Key strategies include:
Foundations (typically concrete ringwall) must support heavy loads and resist thermal effects from hot pitch. API 650 App. B guides geotechnical investigation.
| Investigation Aspect | API 650 App. B Recommendation | Details |
|---|
Click row for relevance to large hot pitch tanks.
Sustained heat (150-200°C) can:
Effective mixing is vital for homogeneity, sludge prevention, and temperature uniformity in viscous pitch. Side-entry mechanical mixers are generally preferred over jet mixers for high viscosity.
| Mixer Type | Suitability for Viscous Pitch | Details |
|---|
Click row for pros & cons.
Comprehensive systems are crucial: overfill protection (API 2350), tank venting (API 2000), and fire protection (NFPA 11, NFPA 30).
| System | Relevant Standard(s) | Details |
|---|
Click row for key design considerations for hot pitch service.
This final section summarizes the primary recommendations stemming from the feasibility study. It emphasizes a phased approach, starting with thorough market and product viability assessments, followed by detailed engineering for the storage facility, and culminating in a comprehensive techno-economic evaluation. The successful valorization of SDA pitch into asphalt hinges on meticulous planning and execution across all these domains.
Valorizing UOP SDA pitch as asphalt is technically feasible but complex. It requires significant modification (blending) to meet market standards. The design of a large (>600 m³) heated (150-200°C) storage tank is a major engineering project demanding adherence to API 650 App. M, careful material selection, robust heating, insulation, CUI prevention, specialized mixing, and comprehensive safety systems.
A holistic techno-economic evaluation and a systematic, phased approach are key to realizing the benefits of this strategic shift.