Integrated Hydrocracking Hydrotreating Recycle Gas Compressor
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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 to meet ultra-low sulfur diesel specifications, and there is a need to optimize hydrogen utilization to enhance efficiency and reduce costs.
Innovation Solution
A process and apparatus that integrate hydrocracking and hydrotreating units with a common recycle gas compressor and cold separator, utilizing make-up hydrogen to increase hydrogen partial pressure in the hydrocracking reactor, and employing a warm separator to simplify diesel fractionation and reduce reheating needs, allowing for efficient production of low sulfur diesel.
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 mild hydrocracking and hydrotreating processes into an integrated system where the hydrocracking reactor effluent is directly fed to the hydrotreating reactor. This merging allows the hydrocracking unit to maximize diesel production while the integrated hydrotreating unit simultaneously removes sulfur and nitrogen contaminants, resolving the contradiction between high diesel yield and low contaminant levels.
Solution Approach 2:
The integrated system performs multiple functions: the hydrocracking reactor converts heavy hydrocarbons to diesel-range molecules, while the hydrotreating reactor simultaneously removes heteroatoms (sulfur, nitrogen) and saturates aromatic rings. This multi-functionality enables a single process configuration to achieve both high diesel yield and ultra-low sulfur specifications.
2Object-affected harmful factors
If separate hydrocracking and hydrotreating units are used, then contaminant removal is improved, but capital and operating costs increase
Solution Approach 1:
The patent merges hydrocracking and hydrotreating into an integrated process where the hydrotreating reactor serves dual purposes: it processes all hydrocracking effluent for contaminant removal and can independently process other feeds. This consolidation reduces the number of separate units required while maintaining effective sulfur removal capabilities.
Solution Approach 2:
The hydrotreating reactor is designed with multi-functionality, capable of processing both hydrocracking effluent and other hydrocarbon feeds independently. This universal capability allows a single unit to replace what would traditionally require multiple specialized units, reducing overall system complexity and cost.
3Manufacturing precision
If traditional fractionation processes are used after hydrocracking, then diesel separation is achieved, but thermal inefficiencies and reheating requirements increase operating costs
Solution Approach 1:
The hydrotreating reactor performs preliminary contaminant removal and product stabilization before fractionation. By removing sulfur, nitrogen, and unstable components in advance, the subsequent fractionation process operates on pre-treated material that requires minimal or no reheating, eliminating thermal inefficiencies while maintaining diesel separation quality.
4Productivity
If hydrogen partial pressure is increased in the hydrocracking reactor, then conversion efficiency is improved, but hydrogen consumption and compression costs increase
Solution Approach 1:
The integrated system merges hydrogen streams from both hydrocracking and hydrotreating reactors, allowing efficient utilization of hydrogen throughout the system. The common recycle gas compressor serves both units, optimizing compression efficiency and reducing redundant energy consumption while maintaining high hydrogen partial pressure in the hydrocracking reactor for improved conversion 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 integrated approach enhances diesel quality, reduces capital and operating costs, and improves hydrogen efficiency, enabling the production of low sulfur diesel that meets stringent specifications while minimizing thermal inefficiencies.
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
the diesel stream is hydrotreated in the presence of a hydrotreating hydrogen stream and hydrotreating catalyst to provide a hydrotreating effluent stream
Data Source
AI summary
A process and apparatus are 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 share the same recycle gas compressor. A make-up hydrogen stream may also be compressed in the 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.