Multiphase Hydrogenation Reactor Layout for Better Hydrogen Utilization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current petroleum refining processes face issues such as poor chemical reaction efficiency, undesirable reaction conditions, low hydrogen gas utilization, and poor selectivity in fixed-bed hydrogenation reactors, leading to challenges in producing multiple products like gasoline, diesel, ethylene raw material, and aviation kerosene, with problems like flooding, catalyst poisoning, and high hydrogen consumption.
Innovation Solution
A multi-phase combination reaction system with a fixed bed hydrogenation reactor divided into three areas: a first hydrogenation reaction area, a gas-liquid separation area, and a second and third hydrogenation reaction area, allowing for simultaneous production of multiple products by optimizing hydrogen partial pressure, reducing flooding, and enhancing mass transfer efficiency through countercurrent reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed-bed hydrogenation reactor is used for hydrorefining and hydrocracking, then the reaction can be carried out with catalyst, but the hydrogen gas must penetrate through the raw material liquid membrane on the catalyst surface which is limited by mass transfer resistance
Solution Approach 1:
The reactor is divided into multiple reaction zones with different catalyst types and functions. The upper zone uses hydrorefining catalyst for desulfurization and denitrogenation, while the lower zone uses hydrocracking catalyst for breaking down heavy hydrocarbons. This segmentation allows each zone to optimize its specific function and reduces mass transfer limitations by creating distinct reaction environments.
Solution Approach 2:
Different catalysts with specific properties are placed in different zones of the reactor. The upper zone contains catalysts optimized for removing sulfur and nitrogen, while the lower zone contains catalysts optimized for cracking heavy molecules. This local differentiation of catalyst quality matches the specific chemical needs of each reaction zone, improving overall efficiency.
2Productivity
If the raw material gradually flows downward along the catalyst bed, then the reaction can proceed, but the hydrogen partial pressure in the lower part of the reactor is significantly reduced due to accumulation of H2S, NH3 and small molecular hydrocarbons
Solution Approach 1:
The reactor is segmented into upper and lower zones with different functional catalysts. The upper zone handles the removal of H2S and NH3 through hydrorefining reactions, while the lower zone maintains higher hydrogen partial pressure for hydrocracking reactions. This segmentation prevents the accumulation of inhibitory gases in the lower zone, maintaining favorable reaction conditions.
Solution Approach 2:
The harmful accumulation of H2S, NH3 and small molecular hydrocarbons is extracted and removed in the upper zone before the raw material reaches the lower zone. By taking out these inhibitory substances in the upper reaction zone, the lower zone maintains higher hydrogen partial pressure and more favorable reaction conditions.
3Reliability
If the fixed-bed hydrogenation reactor is used for hydrogenation reaction, then the reaction can be carried out, but the selectivity of the hydrogenation reaction is poor and essentially saturates all molecules capable of performing the hydrogenation reaction
Solution Approach 1:
The reactor is divided into two functional zones: the upper zone for hydrorefining (desulfurization and denitrogenation) and the lower zone for hydrocracking. This segmentation ensures that different types of molecules are processed in appropriate zones, improving selectivity and preventing unnecessary hydrogen consumption on molecules that don't require hydrogenation.
Solution Approach 2:
Different catalysts with specific selectivities are placed in different zones. The upper zone uses catalysts selective for removing sulfur and nitrogen, while the lower zone uses catalysts selective for cracking heavy hydrocarbons. This local quality differentiation improves overall reaction selectivity and reduces hydrogen waste.
4Reliability
If the reaction environment has high hydrogen partial pressure and low concentration of impurities at the top of the reactor, then the hydrogenation reaction can proceed efficiently, but the temperature is low due to the small amount of heat release
Solution Approach 1:
The reactor is segmented into upper and lower zones with different reaction characteristics. The upper zone maintains lower temperature favorable for selective hydrorefining, while the lower zone achieves higher temperature through exothermic hydrocracking reactions. This segmentation allows each zone to operate at optimal temperatures for its specific function.
Solution Approach 2:
The reactor maintains continuous flow of raw material through both zones, with the upper zone preparing the material and the lower zone completing the transformation. The continuous action ensures that the exothermic heat from the lower zone can be utilized to maintain favorable temperatures throughout the reactor, improving overall efficiency.
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
The system improves reaction efficiency, reduces hydrogen consumption, prevents flooding, and extends catalyst life by optimizing hydrogen partial pressure and mass transfer, enabling the production of multiple products in a single reactor with reduced costs and increased throughput.
Implementation Method 1
the gas-liquid separation area is used for separating the raw oil into a gas phase A and a liquid phase A
Implementation Method 2
the first hydrogenation reaction area is used for carrying out a first hydrogenation reaction between the gas phase A and hydrogen gas
Implementation Method 3
a first hydrogenation catalyst bed is arranged in the first hydrogenation reaction area
Implementation Method 4
the second hydrogenation reaction area is used for performing a gas-liquid countercurrent reaction between the liquid phase A and the hydrogen gas
Implementation Method 5
the second hydrogenation reaction area is used for performing a gas-liquid countercurrent reaction between the liquid phase A and the hydrogen gas from the hydrogen inlet
Implementation Method 6
the third hydrogenation reaction area is used for carrying out a third hydrogenation reaction of the hydrogen-dissolved material B
Implementation Method 7
a third hydrogenation catalyst bed is arranged in the third hydrogenation reaction area
Data Source
AI summary
A multi-phase combination reaction system has at least one fixed bed hydrogenation reactor. The fixed bed hydrogenation reactor has, arranged from top to bottom, a first hydrogenation reaction area, a gas-liquid separation area, a second hydrogenation reaction area and a third hydrogenation reaction area. The gas-liquid separation area is provided with a raw oil inlet. A hydrogen inlet is provided between the second hydrogenation reaction area and the third hydrogenation reaction area. The system is capable of simultaneously obtaining two fractions in one hydrogenation reactor.