FCC Riser Sulfur Reduction via Carbon Monoxide Reducing Agent
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Solution Overview
Problem
Current FCC processes struggle to effectively reduce sulfur levels in gasoline and diesel products without additional treatment steps, as existing methods either incur high capital costs or result in loss of valuable product octane.
Innovation Solution
Incorporating carbon monoxide (CO) as a reducing agent in the fluidized catalytic cracking process, where CO is added to the riser reactor with the hydrocarbon feedstock before cracking, facilitating simultaneous reduction of sulfur content in liquid products through intimate mixing and atomization using a specialized feed nozzle assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If hydrotreating is used to remove sulfur from FCC feed before cracking, then sulfur removal effectiveness is improved, but capital cost and hydrogen consumption increase significantly
Solution Approach 1:
The patent combines sulfur removal with the cracking process by introducing carbon monoxide into the riser reactor where both cracking and sulfur reduction occur simultaneously. This merges two previously separate operations (hydrotreating before cracking and cracking) into a single integrated process, eliminating the need for separate sulfur removal equipment and reducing capital costs.
Solution Approach 2:
Carbon monoxide serves as an intermediary reducing agent that facilitates sulfur removal during cracking. Instead of using hydrogen from hydrotreating, CO acts as a mediator that donates electrons to sulfur compounds, converting them to hydrogen sulfide which is then removed in the regenerator. This intermediary approach enables sulfur removal without requiring the expensive hydrotreating equipment.
2Object-affected harmful factors
If hydrotreating is used to remove sulfur from cracked products, then sulfur removal effectiveness is improved, but valuable product octane is lost due to saturation of high octane olefins
Solution Approach 1:
The patent performs sulfur removal preliminary action during the cracking process itself rather than after cracking is complete. By introducing CO into the riser reactor before the cracking reaction, sulfur reduction occurs simultaneously with cracking, so that the high octane olefin products are formed and sulfur is removed in the same step, preventing the need for subsequent hydrotreating that would saturate and reduce octane.
Solution Approach 2:
The useful action of sulfur removal continues throughout the cracking process rather than being a separate subsequent step. CO is introduced continuously into the riser reactor where it actively reduces sulfur compounds during the entire cracking reaction time, ensuring that sulfur removal and product formation occur continuously without interruption, thereby preserving product quality.
3Device complexity
If conventional catalytic cracking is used without additional sulfur removal agents, then process simplicity is maintained, but sulfur content in liquid products remains high
Solution Approach 1:
The patent changes the chemical parameter of the cracking environment by introducing carbon monoxide gas into the riser reactor. This parameter change (adding CO) fundamentally alters the chemical reactions occurring during cracking, enabling simultaneous sulfur reduction without requiring complex equipment changes or multiple process units. The simplicity of adding a gas stream contrasts with the complexity of hydrotreating equipment.
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 achieves a significant reduction of sulfur in liquid products, exceeding 50%, with increased gasoline yield and minimal impact on other product yields, making the process commercially viable and environmentally compliant.
Implementation Method 1
carbon monoxide (CO) is used for removing sulfur in this invention. The reducing nature of CO and its oxidation to COS leads to a reduction of sulfur in the liquid products
Implementation Method 2
an intimate atomised mixture of the hydrocarbon feedstock with carbon monoxide reducing agent is separately made and the mixture is then transported to the riser reactor
Implementation Method 3
Catalytic cracking is a petroleum refining process, which is applied commercially on a very large scale. In the process, heavy hydrocarbon feed stock is converted into lighter products by reactions taking place at elevated temperature in the presence of catalyst
Implementation Method 4
regeneration is done by burning off the coke to restore the catalytic activity
Data Source
AI summary
Disclosed herein is an improved fluidized catalytic cracking process for converting normally liquid hydrocarbon feedstock with simultaneous reduction of sulfur content in the liquid products obtained therefrom which comprises carrying out the cracking process in the presence of carbon monoxide gas as a reducing agent. The process optionally includes a step of premixing the hydrocarbon feedstock with carbon monoxide gas causing major sulfur reduction before effecting the cracking. The premixing is done in a specified nozzle assembly linked to the FCC unit.