Alkylation Reactor with Segmented Mixing Zones
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Solution Overview
Problem
Conventional alkylation reactors face challenges in achieving high conversion and selectivity due to back-mixing and inefficient mixing of reactants, leading to suboptimal reaction rates and product quality in isoalkane and alkene reactions.
Innovation Solution
A combined reactor with multiple reaction zones of varying diameters and internal flow disturbance components, allowing for controlled mixing intensities and residence times to enhance dispersion and hydrogen transfer reactions, thereby improving reaction conversion and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a horizontal stirred tank reactor is used with sufficient dispersing and mixing of the two phases, then the complete conversion of the alkene can be achieved quickly, but the reaction time becomes too long causing trimethylpentane to isomerize to dimethylhexane with low octane number
Solution Approach 1:
The reactor is divided into multiple reaction zones with different mixing intensities and residence times. The first reaction zone provides intensive mixing for rapid alkene conversion, while the second reaction zone provides a quiescent environment to prevent TMP isomerization, thus resolving the contradiction between conversion rate and product selectivity.
Solution Approach 2:
Different regions of the reactor are designed with different flow characteristics and mixing intensities. The inlet region has high mixing intensity for rapid reaction, while the outlet region has low mixing intensity to preserve product quality, allowing simultaneous achievement of high conversion and high selectivity.
2Productivity
If the reaction time is extended to achieve high conversion, then more alkene is converted, but trimethylpentane continues to contact the strongly acidic catalyst causing isomerization to dimethylhexane
Solution Approach 1:
The reaction process is segmented into two distinct zones: the first zone enables rapid conversion of alkene to TMP through intensive mixing, while the second zone maintains a quiescent environment that prevents further isomerization of TMP to DMH, thus achieving high conversion without product degradation.
Solution Approach 2:
The first reaction zone is designed to rapidly complete the alkylation reaction in a short time, rushing through the conversion step before isomerization can occur. This allows the system to achieve high conversion while minimizing the time products are exposed to the acidic catalyst.
3Ease of operation
If a fixed motor is used to drive the stirring paddle for mechanical agitation, then mixing is achieved, but leakage is easy to generate due to poor sealing
Solution Approach 1:
The mechanical stirring system with fixed motor and seals is replaced with a circulating pump system that uses fluid circulation to achieve mixing. This substitution eliminates the sealing problems associated with mechanical shafts while maintaining effective mixing capability through controlled circulation of the reaction mixture.
4Area of stationary object
If a single large reactor is used for macroscopic mixing, then the mixing space is sufficient, but the back-mixing is large which is not conducive to increasing the selectivity of the reaction
Solution Approach 1:
The large reactor volume is segmented into multiple reaction zones with different flow characteristics. The first zone provides intensive mixing for rapid reaction, while the second zone provides a quiescent environment with minimal back-mixing to preserve product selectivity, thus maintaining the benefits of large volume while avoiding the drawbacks of back-mixing.
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 solution accelerates the alkylation reaction rate, reduces energy consumption, and produces high-octane products while minimizing side reactions, making it suitable for plant-scale processes.
Implementation Method 1
a feed liquid circulating pump... the mixed feed liquid is conveyed to the rotary packed bed by the circulating pump for cyclic reaction
Implementation Method 2
a rotary packed bed consisting of a rotor and a packing layer... enhance the mixing between the reactants and the acid hydrocarbon emulsion
Implementation Method 3
the alkylation reaction of isobutane and butene is a typical double liquid phase reaction, and the interphase mass transfer rate determines the macroscopic reaction rate
Data Source
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AI summary
The present invention provides an alkylation reaction apparatus, which is characterized by comprising n reactors, in said n reactors, there are m reactors including the first reactor that are those having three reaction zones as defined below; according to the flow direction order of alkylation reaction streams, said three reaction zones are an x reaction zone, a y reaction zone and a z reaction zone respectively; based on the mixing intensity, the mixing intensity of the y reaction zone>the mixing intensity of the x reaction zone>the mixing intensity of the z reaction zone, wherein n≥1 and n≥m. The present invention also provides an alkylation reaction system comprising the aforementioned alkylation reaction apparatus, and a liquid acid catalyzed alkylation reaction process by using the aforementioned alkylation reaction apparatus or the aforementioned alkylation reaction system.