Two-Stage Hydrotreating Process for Bio-Oil Integration
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Solution Overview
Problem
Current methods for hydrotreating mixtures of vegetable or animal oils and petroleum cuts face challenges such as high hydrogen consumption, catalyst deactivation, and poor cold properties of the products, which limit their use as gas oil fuel bases due to unsuitable operating conditions and the formation of inhibiting by-products like CO, CO2, and water.
Innovation Solution
A two-stage hydrotreating process using deep hydrodesulfurization (HDS1) followed by mild hydroconversion (HDT2) with intermediate stripping, where vegetable or animal oils are introduced in admixture with the effluent from HDS1, allowing for reduced hydrogen consumption and improved catalyst stability by avoiding deactivation agents, and adjusting operating conditions to enhance cold properties and meet gas oil specifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vegetable or animal oils are hydrotreated in conventional single-stage processes, then hydrogen consumption is high and catalyst deactivation occurs, but the products have poor cold properties and fail to meet gas oil specifications
Solution Approach 1:
The hydrotreating process is divided into two distinct stages: a first stage for deep hydrodesulfurization of petroleum cuts, and a second stage for mild hydroconversion of vegetable/animal oils. This segmentation allows each stage to be optimized independently, preventing catalyst deactivation by avoiding the introduction of deactivation agents (CO, CO2, water) into the first stage, while reducing overall hydrogen consumption through the two-stage approach.
Solution Approach 2:
An intermediate stripping section is introduced between the two catalyst beds to remove deactivation agents (CO, CO2, water) produced in the first stage before the effluent enters the second stage. This intermediary removal step protects the second catalyst bed from deactivation and allows for more efficient hydrogen utilization.
2Manufacturing precision
If vegetable oils are treated to meet gas oil specifications, then sulfur content is reduced, but cold resistance properties deteriorate
Solution Approach 1:
The second catalyst bed is specifically designed with catalysts optimized for hydroconversion reactions that improve cold resistance properties (such as isomerization and saturation reactions) while maintaining low sulfur content. The local optimization of catalyst properties in the second stage allows simultaneous achievement of sulfur reduction and cold resistance improvement.
3Ease of manufacture
If conventional hydrotreating is used to convert vegetable oils, then treatment costs are high, but the process requires strict vegetable oil limitations and careful feed selection
Solution Approach 1:
The two-stage process is designed to handle a wide range of vegetable and animal oils with different compositions and properties. The first stage processes petroleum cuts while the second stage is specifically optimized for converting various vegetable/animal oils into gas oil fuel bases, making the system universally applicable to different feedstocks without requiring strict limitations on oil type.
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 reduces treatment costs, extends catalyst life, and improves the range of usable oils while meeting sulfur and cold resistance specifications, minimizing hydrogen use and preventing thermal degradation, thus enhancing the operational stability and efficiency of the refining process.
Implementation Method 1
a stage of deep hydrodesulfurization (HDS1) of a petroleum cut
Implementation Method 2
mild hydroconversion (HDT2) with intermediate stripping, where vegetable or animal oils are introduced in admixture with the effluent from HDS1
Implementation Method 3
the triglycerides are converted to mainly paraffinic and saturated derivatives
Implementation Method 4
two-stage hydrotreating process using deep hydrodesulfurization (HDS1) followed by mild hydroconversion (HDT2) with intermediate stripping
Data Source
AI summary
A hydrotreating method uses two catalyst beds with the introduction, on the last catalyst bed, of oils of animal or vegetable origin for co-treating a mixture made up of oils of vegetable or animal origin and of petroleum cuts (gas oil cuts (GO) and middle distillates) in order to produce gas oil effluents meeting specifications with an improved cetane number. The first catalyst bed is dedicated to only the deep desulfurization reactions (HDS1) of a petroleum type feed. The effluents of the first catalyst bed having an effluent sulfur content below or equal to 50 mg/kg are separated into two streams. The first stream, which is predominant, is sent to the gas oil pool. The second stream is mixed with oils of vegetable or animal origin. The resultant oil-petroleum cut mixture is then subjected to a milder hydrotreatment (HDT2). The effluents obtained at the outlet of the second catalyst bed can optionally be mixed with the predominant stream from the first bed. The process economy, the tolerance to the specifications relative to oils of animal or vegetable origin and the quality of the products obtained are thus greatly improved.