Hydrocracking Distillate Yield via Segmented Hydrotreatment
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Solution Overview
Problem
Current hydrocracking processes for producing distillate products face challenges in maximizing yield while minimizing conversion to naphtha or lower boiling range products, often resulting in reduced lubricant base oil production and requiring severe processing conditions.
Innovation Solution
A multi-stage process involving hydrotreating, separation or fractionation of the effluent to remove contaminant gases, and subsequent hydrocracking with a large pore molecular sieve catalyst, which allows for milder reaction conditions and increased distillate yield by minimizing exposure of distillate boiling range products to additional hydroprocessing stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If severe processing conditions are used to maximize distillate yield, then distillate production increases, but conversion to naphtha and lighter products increases excessively
Solution Approach 1:
The hydroprocessing is divided into two distinct stages: a first hydroprocessing stage followed by a second hydroprocessing stage. This segmentation allows each stage to be optimized for different functions - the first stage handles initial conversion while the second stage completes the process, preventing excessive conversion to light products while maximizing distillate yield.
Solution Approach 2:
The first hydroprocessing stage performs preliminary conversion of the feedstock before the second stage. By conducting initial hydroprocessing separately, the process prepares the feed for the second stage while preventing premature over-conversion that would lead to excessive naphtha and lighter product formation.
2Device complexity
If single-stage hydrocracking is used to produce distillate, then process complexity is reduced, but distillate yield is decreased and lubricant base oil production is reduced
Solution Approach 1:
The process is segmented into two hydroprocessing stages with distinct functions. The first stage performs initial conversion and the second stage completes the hydroprocessing, allowing each stage to be optimized for its specific role. This segmentation increases distillate yield and lubricant base oil production compared to single-stage processes.
3Quantity of substance
If extended hydroprocessing exposure is used to increase conversion, then feed conversion increases, but distillate yield decreases due to over-cracking
Solution Approach 1:
The hydroprocessing is segmented into two stages where the first stage performs initial conversion and the second stage completes the process. This prevents extended exposure to hydroprocessing conditions that would cause over-cracking, thereby maintaining high distillate yield while achieving the desired level of feed conversion.
Solution Approach 2:
The first hydroprocessing stage performs preliminary conversion before the second stage. This preliminary action prepares the feedstock for the second stage while controlling the extent of conversion to prevent over-cracking and maintain optimal distillate yield.
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 significantly enhances distillate product yield while maintaining a desired level of feed conversion, reducing the need for recycle and improving overall process efficiency, allowing for increased production of distillate boiling range products such as kerosene and diesel without excessive conversion to naphtha or lighter products.
Implementation Method 1
contacting a feedstock having a T5 boiling point of at least about 473°F (245°C) with a first hydrotreating catalyst under first effective hydrotreating conditions
Implementation Method 2
contacting a feedstock having a T5 boiling point of at least about 473°F (245°C) with a first hydrotreating catalyst under first effective hydrotreating conditions
Implementation Method 3
performing a separation on the first hydrotreated effluent to form at least a first separated effluent portion and a first remaining effluent portion
Implementation Method 4
fractionating the second hydrotreated effluent to form at least a hydrotreated distillate boiling range product and a second remaining effluent portion
Implementation Method 5
contacting the second remaining effluent portion with a hydrocracking catalyst under effective hydrocracking conditions to produce a hydrocracked effluent
Data Source
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AI summary
Methods are provided for improving the yield of distillate products from hydroprocessing of gas oil feedstocks, such as vacuum gas oils. It has been unexpectedly found that stripping of gases or fractionation to separate out a distillate fraction during initial hydrotreatment of a feed can provide a substantial increase in distillate yield at a desired amount of feedstock conversion. The improvement in yield of distillate products can allow a desired level of conversion to be performed on a feedstock for generating lubricating base oil products while reducing or minimizing the amount of naphtha (or lower) boiling range products. Alternatively, the improvement in yield of distillate products can correspond to an improved yield during a single pass through a reaction system, so that distillate yield is increased even though a lubricant boiling range product is not generated.