Steam Cracked Tar Upgrading via Deasphalting and Hydrocracking
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Solution Overview
Problem
Current technologies are inefficient in utilizing and disposing of steam cracker tar (SCT), a low-value byproduct of pyrolysis, due to its incompatibility with other refinery products and increasing sulfur levels, which limits its use and requires costly disposal methods.
Innovation Solution
A method involving deasphalting and hydrotreating of tar to produce valuable products like low sulfur diesel fuel, mogas, and hydrocrackate, which can be blended with Bunker Fuel, utilizing a system integrating a pyrolysis furnace, deasphalter, and hydrocracker to enhance product yield and compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steam cracking is used to produce light olefins, then valuable products such as ethylene and propylene are obtained, but steam cracked tar is produced as an unwanted byproduct that is difficult to dispose of
Solution Approach 1:
The patent converts the harmful byproduct steam cracked tar into valuable fuel products through a two-step process: first deasphalting to remove asphaltenes, then hydrocracking to produce diesel fuel and other useful hydrocarbons. This transforms the waste disposal problem into a value-added production process.
Solution Approach 2:
The patent changes the chemical parameters of steam cracked tar through deasphalting (removing asphaltenes) and hydrocracking (breaking down heavy molecules under high pressure and temperature with hydrogen). These parameter changes transform the tar from an incompatible, high-molecular-weight material into compatible, lower-molecular-weight fuel products.
2Ease of operation
If steam cracked tar is blended with refinery fuel oil pools, then disposal is simplified, but incompatibility due to asphaltenes causes precipitation and operational problems
Solution Approach 1:
The patent extracts asphaltenes from steam cracked tar through deasphalting using solvents or fractional distillation. By removing the asphaltenes that cause incompatibility and precipitation, the remaining tar becomes stable and compatible with refinery fuel oil pools, eliminating the blending problems.
3Loss of substance
If conventional disposal methods are used for high sulfur tar, then tar can be burned, but emission regulations increasingly limit the amount that can be burned
Solution Approach 1:
The patent applies hydrocracking with hydrogen under high pressure and temperature to chemically transform the high sulfur tar molecules. This process removes sulfur through hydrodesulfurization reactions, producing low sulfur diesel fuel that meets emission standards, thereby converting a regulated waste stream into a compliant fuel product.
4Productivity
If deasphalting and hydrocracking are applied to upgrade tar, then valuable fuel products are produced, but process complexity increases
Solution Approach 1:
The patent segments the tar upgrading process into two distinct stages: deasphalting (removing asphaltenes) followed by hydrocracking (producing fuels). This segmentation allows each unit operation to be optimized independently and integrated with existing refinery infrastructure, making the complex overall process more manageable and implementable.
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 effectively upgrades tar into high-value products, improving yield and compatibility with fuel oils, thereby addressing the disposal and utilization challenges of SCT, and reducing environmental impact by utilizing tar in more valuable end-products.
Implementation Method 1
GB 2 014 605 treats pyrolysis fuel oil produced during the production of olefins by thermal cracking by first subjecting it to solvent extraction to remove 'polymeric compounds'.
Implementation Method 2
Steam cracking, also referred to as pyrolysis, has long been used to crack various hydrocarbon feedstocks into olefins. Conventional steam cracking utilizes a pyrolysis furnace wherein the feedstock, typically comprising crude or a fraction thereof optionally desalted, is heated sufficiently to cause thermal decomposition of the larger molecules.
Implementation Method 3
GB 2 104 544 discloses treating pyrolysis tar obtained from the production of ethylene from naphtha feeds via steam cracking by first heating the feedstock with hydrogen to saturate polynuclear aromatic compounds, then hydrocracking the hydrogenated compounds in a cracking zone
Data Source
AI summary
In the invention, tar is upgraded by deasphalting and then hydrocracking to produce valuable products such as low sulfur diesel fuel and mogas. The invention is also directed to a system integrating a pyrolysis furnace operation with refinery operations.