Two-Stage Hydrocracking with Divided Wall Column

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Solution Overview

Problem

Traditional hydrocracking processes are limited in producing multiple grades of lube oil base feedstock due to their fixed configuration, which increases complexity and capital expenditures, making it challenging to meet the demand for diverse lube oil base feedstock qualities.

Innovation Solution

A two-stage hydrocracking process is implemented, including a hydrotreating zone, multiple separation and fractionation zones, and a divided wall fractionation column, allowing for adjustable conversions and separate recovery of lube oil base feedstocks, reducing overall capital expenditures by enabling the production of multiple grades within a single hydrocracking unit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a traditional single-stage hydrocracking process is used, then the process configuration is simple, but it can only produce a single grade of lube oil base feedstock with fixed viscosity index

Engineering Contradiction:

Improveability to produce multiple grades of lube oil base feedstockVSAvoidcomplexity of plant design and fractionation system

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The hydrocracking process is divided into two distinct stages: a first hydrocracking stage and a second hydrocracking stage. Each stage operates with adjustable conversion parameters, enabling the production of different quality unconverted oil streams that can be blended or separated to achieve multiple grades of lube oil base feedstock with different viscosity indices

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The divided wall column is designed to perform multiple functions simultaneously: it acts as a fractionation column for separating hydrocracking products, a dewaxing unit for producing lube oil base feedstock, and a blending zone for creating multiple grades. This multi-functionality eliminates the need for separate independent fractionation systems for each product grade

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If a two-stage hydrocracking configuration is implemented to produce multiple grades of lube oil base feedstock, then product flexibility is improved, but capital and operating expenditures increase due to independent fractionation systems

Engineering Contradiction:

Improveflexibility to achieve different unconverted oil qualitiesVSAvoidcapital and operating expenditures

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The divided wall column merges the fractionation and dewaxing operations into a single integrated unit. The column simultaneously performs product separation and lube oil base feedstock production, eliminating the need for multiple independent fractionation systems. This integration significantly reduces both capital expenditures and operating costs while maintaining the ability to produce multiple grades

Inventive Principle:

Principle #5Merging (Combining)

3Ease of operation

If once-through flow schemes are used, then the process operation is simplified, but the product lube oil base feedstock is limited to a single grade with fixed viscosity index

Engineering Contradiction:

Improveoperational simplicityVSAvoidproduct grade variety

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The two-stage hydrocracking process employs dynamic control of conversion parameters at each stage. By adjusting the conversion levels in the first and second stages independently, the process can dynamically produce unconverted oil of different qualities, enabling flexible production of multiple lube oil base feedstock grades while maintaining relatively simple once-through operation

Inventive Principle:

Principle #15Dynamics

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 efficient production of multiple grades of lube oil base feedstocks, optimizing the quantity and quality of separate streams, reducing capital expenditures by 10% or more, and enhancing operational flexibility.

Implementation Method 1

The feed enters a stripper and the resulting bottom stream enters one cell of a dual cell fractionator charge heater and is flashed in the distillation zone of a divided wall fractionation column

Methodology Applied

Scientific EffectDistillation: Distillation

Implementation Method 2

The effluent of this second zone is sent to a separator and flashed in a hot low-pressure flash drum

Methodology Applied

Scientific EffectFlash evaporation: Flash Evaporation

Data Source

PatentUS9388347B2Two stage hydrocracking process and apparatus for multiple grade lube oil base feedstock production

Publication Date: 2016.07.12 SAUDI ARABIAN OIL CO

AI summary

Multiple grades of lube oil base feedstock are produced within a two-stage hydrocracking unit. Effluent from a first hydrocracking zone is sent to a separation zone, which includes multiple separation vessels, and a heavy liquid stream enters one cell of a dual cell fractionator charge heater and is flashed in the distillation zone of a divided wall fractionation column. A portion of the bottom stream from one side of the divided wall column is sent to the second hydrocracking zone. Feed to a second cell of the dual cell fractionation column is derived from the effluent of this second hydrocracking zone. A different lube oil base feedstocks is derived from each of the cells of the dual cell fractionation column.