Integrated Hydrocracking Hydrotreating Diesel Unit
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Solution Overview
Problem
Mild hydrocracking processes produce diesel that does not meet stringent sulfur and nitrogen contaminant limits, requiring additional processing steps and increased operational costs due to inefficiencies in hydrogen separation and catalyst deactivation.
Innovation Solution
Integrating a hydrotreating unit with the hydrocracking unit, using a common recycle gas compressor and a warm separator to optimize hydrogen utilization, and adding make-up gas to the hydrocracking unit to enhance hydrogen partial pressure, thereby improving diesel quality and reducing processing inefficiencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mild hydrocracking is used to produce diesel, then diesel yield is improved, but sulfur and nitrogen contaminant levels increase making the product non-compliant with specifications
Solution Approach 1:
The patent combines the hydrocracking unit and hydrotreating unit into an integrated system where the hydrocracking reactor and hydrotreating reactor operate in sequence with shared hydrogen recycle infrastructure. This merging allows the diesel produced from hydrocracking to be immediately treated for sulfur and nitrogen removal in the integrated hydrotreating section, resolving the contradiction between maintaining high diesel yield and achieving low contaminant levels.
Solution Approach 2:
The integrated design ensures continuous hydrogen recycling from the hydrotreating unit back to the hydrocracking unit through the shared recycle gas compressor. This continuous action maintains high hydrogen partial pressure throughout the process, enabling both efficient hydrocracking for diesel production and effective hydrotreating for contaminant removal without interruption.
2Manufacturing precision
If additional processing steps are added to remove sulfur and nitrogen, then product quality is improved, but capital and operating costs increase
Solution Approach 1:
By merging the hydrocracking and hydrotreating units into a single integrated apparatus with shared reactors, separators, and recycle gas compressors, the patent reduces the number of separate processing trains required. This integration achieves thorough sulfur and nitrogen removal while avoiding the need for multiple independent processing sequences, thereby controlling capital and operating costs.
Solution Approach 2:
The integrated system uses multi-functional components that serve multiple purposes: the recycle gas compressor provides hydrogen to both hydrocracking and hydrotreating reactions, the separators handle both hydrocracking and hydrotreating effluents, and the reactors are designed to accommodate both cracking and treating functions. This universality reduces overall device complexity while maintaining high diesel quality.
3Productivity
If hydrogen separation efficiency is improved, then hydrogen utilization is optimized, but equipment complexity and costs increase
Solution Approach 1:
The patent merges the hydrogen separation and recycling functions into a unified system where the recycle gas compressors handle hydrogen separation for both hydrocracking and hydrotreating units simultaneously. This integrated approach optimizes hydrogen utilization across the entire process while avoiding the need for separate, complex separation equipment for each unit.
Solution Approach 2:
The recycle gas compressors are designed as multi-functional units that perform hydrogen separation, compression, and distribution to multiple reactors. This universal equipment achieves high hydrogen utilization efficiency without requiring specialized separation equipment for each function, thereby controlling device complexity.
4Reliability
If catalyst activity is maintained through frequent replacement, then reaction efficiency is improved, but operating costs and downtime increase
Solution Approach 1:
The integrated hydrotreating unit performs preliminary cleaning of the hydrocracking effluent by removing sulfur and nitrogen contaminants before the diesel is finalized. This preliminary action protects the downstream catalysts from deactivation by heteroatoms, extending their operational life and reducing the frequency of catalyst replacements and associated downtime.
Solution Approach 2:
The continuous operation of the integrated system maintains steady-state conditions that optimize catalyst performance. The seamless flow from hydrocracking to hydrotreating ensures consistent contaminant removal, preventing catalyst deactivation events that would require shutdowns for catalyst replacement, thereby maintaining continuous reaction efficiency.
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 approach allows for the production of low sulfur diesel with reduced capital and operating costs by simplifying fractionation and extending catalyst life, while meeting stringent fuel specifications.
Implementation Method 1
hydrocracking refers to a process in which hydrocarbons crack in the presence of hydrogen and catalyst to lower molecular weight hydrocarbons
Implementation Method 2
hydrotreating a diesel stream to produce low sulfur diesel
Data Source
AI summary
An apparatus is disclosed for hydrocracking hydrocarbon feed in a hydrocracking unit and hydrotreating a diesel product from the hydrocracking unit in a hydrotreating unit. The hydrocracking unit and the hydrotreating unit shares the same recycle gas compressor. A warm separator separates recycle gas and hydrocarbons from diesel in the hydrotreating effluent, so fraction of the diesel is relatively simple. The warm separator also keeps the diesel product separate from the more sulfurous diesel in the hydrocracking effluent, and still retains heat needed for fractionation of lighter components from the low sulfur diesel product.