Hydrotreating and Hydrocracking Zones for ULSD Production
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Solution Overview
Problem
The petroleum industry faces challenges in producing high-quality ultra low sulfur diesel (ULSD) and fluid catalytic cracker (FCC) feedstock while balancing economic considerations, as existing methods often result in overtreatment of FCC feedstocks, leading to inefficient and costly operations due to high hydrogen pressures and lower conversion rates.
Innovation Solution
A process that decouples reactor severity requirements by using a hydrotreating zone to produce a hydrocarbon stream suitable for FCC and a hydrocracking zone to produce ULSD, operating at lower pressures and conversion rates, with specific temperature, pressure, and catalyst conditions to achieve high cetane quality and low sulfur levels without overtreating the FCC feedstock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If higher pressure and conversion conditions are used to produce high quality ULSD, then sulfur removal efficiency is improved, but capital investment and operational costs increase due to extensive equipment requirements
Solution Approach 1:
The processing unit is divided into two separate zones: a hydrotreating zone for FCC feedstock production and a hydrocracking zone for ULSD production. Each zone operates at optimized pressure conditions independently, allowing the ULSD zone to achieve high sulfur removal without subjecting the entire system to high pressure requirements, thereby reducing overall equipment complexity and capital investment.
2Manufacturing precision
If higher hydrogen pressure is applied to remove sufficient sulfur for ULSD, then product quality is improved, but FCC feedstock becomes overtreated with excessive hydrogen
Solution Approach 1:
The process separates FCC feedstock production and ULSD production into distinct operational zones. The hydrotreating zone operates at lower pressure suitable for FCC feedstock, while the hydrocracking zone operates at higher pressure for ULSD sulfur removal. This segmentation prevents excessive hydrogen treatment of FCC feedstock while achieving necessary sulfur removal for ULSD.
Solution Approach 2:
The hydrocracking zone acts as an intermediary stage that receives hydrotreated FCC feedstock and selectively processes a portion of it for ULSD production. This intermediary zone controls the hydrogen treatment level, allowing FCC feedstock to be adequately treated without over-treatment, while enabling high-sulfur-removal conditions for ULSD in a controlled manner.
3Ease of manufacture
If mild hydrocracking conditions are used to produce FCC quality feedstock, then capital costs are reduced, but diesel product quality is insufficient to meet ULSD requirements
Solution Approach 1:
The processing unit segments the production function into two zones: the hydrotreating zone produces FCC quality feedstock at mild conditions (lower capital cost), while the hydrocracking zone takes a portion of this feedstock and processes it under higher conversion conditions to produce high-quality ULSD. This segmentation allows each zone to be optimized for its specific function.
Solution Approach 2:
The hydrotreating zone serves dual purposes: it produces FCC quality feedstock for the FCC unit and simultaneously prepares feedstock for the hydrocracking zone to produce ULSD. This multi-functionality allows mild conditions to suffice for FCC feedstock while enabling higher quality ULSD production from the same feedstock stream.
4Manufacturing precision
If higher conversion rates are employed to achieve ULSD quality, then sulfur levels are reduced, but operational costs increase due to higher pressure requirements
Solution Approach 1:
The process segments sulfur removal operations into two zones with different pressure requirements. The hydrotreating zone operates at lower pressure for FCC feedstock, while the hydrocracking zone operates at higher pressure specifically for ULSD sulfur removal. This segmentation concentrates the high-energy consumption only where necessary for ULSD production, reducing overall operational costs compared to treating the entire stream at high pressure.
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 produces high-quality ULSD with less than 10 ppm sulfur and FCC feedstock with improved cetane numbers, achieving efficient and cost-effective production by optimizing operating conditions and catalyst selection, thereby reducing capital expenditures and operational costs.
Implementation Method 1
contacting a hydrocarbonaceous feedstock with a hydrotreating catalyst under hydrotreating conditions to produce a hydrocarbonaceous stream suitable for an FCC unit
Implementation Method 2
contacting the combined stream with a hydrocracking catalyst under hydrocracking conditions to form a hydrocracking zone effluent including a high quality, low sulfur diesel
Data Source
AI summary
A process is provided to produce high cetane quality and low or preferably ultra low sulfur diesel and a fluid catalytic cracker (FCC) quality feedstock from a processing unit including at least a hydrotreating zone and a hydrocracking zone. In one aspect, the processing unit includes reactor severity requirements in both the hydrotreating zone and the hydrocracking zone effective to produce the FCC feed quality and the diesel sulfur quality to permit a high quality hydrocracked product to be formed at lower pressures and conversion rates without overtreating the FCC quality feedstock stream. In another aspect, a portion of the hydrotreated effluent is selected for conversion in the hydrocracking and the remaining portion of the hydrotreated effluent is directed to subsequent processing, such as fluid catalytic cracking.