Hydrogen Compression Segmentation for Multi-Pressure Hydrocracking
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Solution Overview
Problem
Current hydroprocessing methods face challenges in producing diesel fuel that meets stringent sulfur and nitrogen contaminant limits, particularly when hydrocracking units operate at different pressures, requiring improved methods for hydrogen supply and integration between hydrocracking and hydrotreating units to enhance diesel production and meet regulatory standards.
Innovation Solution
A process involving the compression of hydrogen streams to provide multiple compressed hydrogen streams for use in hydrocracking and hydrotreating units, allowing for efficient hydrocracking and hydrotreating of hydrocarbon streams, followed by fractionation to produce high-quality diesel fuel, with the option to recycle hydrogen streams to optimize pressure utilization and reduce capital and operating costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a hydrocracking unit operates at a higher pressure than a hydrotreating unit, then hydrocracking efficiency is improved, but hydrogen supply complexity increases due to different pressure requirements
Solution Approach 1:
The hydrogen supply system is segmented into multiple compression stages. A first compressor compresses make-up hydrogen to an intermediate pressure, and a second compressor further compresses a portion of this hydrogen to the higher pressure required by the hydrocracking unit. This segmentation allows each compressor to operate within optimal pressure ranges while meeting the different pressure requirements of both units.
Solution Approach 2:
The first compressed make-up hydrogen stream serves multiple functions: it provides hydrogen for the hydrotreating unit at the intermediate pressure, and serves as the feed for the second compressor that supplies the hydrocracking unit. This multi-functionality reduces the need for separate compression systems for each unit.
2Reliability
If separate compressors are used for each hydroprocessing unit, then each unit receives optimized hydrogen pressure, but capital and operating costs increase
Solution Approach 1:
The system merges the hydrogen supply functions by using the first compressor to provide a shared first compressed make-up hydrogen stream that serves both units. Only a portion requires further compression by the second compressor, reducing the total compression capacity needed compared to fully independent systems.
Solution Approach 2:
The system recycles hydrogen effluent from the hydrocracking unit back through the compression system. The recycled hydrogen is recompressed and reused, reducing the make-up hydrogen requirement and lowering both capital costs (smaller compressors needed) and operating costs (less hydrogen purchase).
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 process effectively increases diesel production while ensuring it meets stringent sulfur and nitrogen standards, optimizing hydrogen use across units, and integrating hydrocracking and hydrotreating operations to reduce costs and improve efficiency.
Implementation Method 1
compressing a make-up hydrogen stream in a first compressor to provide a first compressed make-up hydrogen stream
Implementation Method 2
A hydrocarbon stream is hydrocracked in the presence of the second compressed make-up hydrogen stream and hydrocracking catalyst
Implementation Method 3
A diesel stream is hydrotreated in the presence of the second hydroprocessing hydrogen stream and hydrotreating catalyst
Implementation Method 4
at least a portion of the first hydroprocessing effluent stream is fractionated to provide the diesel stream
Data Source
AI summary
A process is disclosed for hydroprocessing two hydrocarbon streams at two different pressures. A hydrogen stream is compressed and split. A first split compressed stream is further compressed to feed a first hydroprocessing unit that requires higher pressure for operation. A second split compressed stream is fed to a second hydroprocessing unit that requires lower pressure. Recycle hydrogen from the second hydroprocessing unit is recycled back to the compression section.