Riser-Bed Coke Control Reactor for DMTO Catalyst Utilization
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Solution Overview
Problem
Existing DMTO industrial devices struggle to fully utilize the advantages of new generation DMTO catalysts with high methanol processing capacity and low-carbon olefin selectivity, necessitating a device and method that can effectively manage coke species to enhance catalyst performance.
Innovation Solution
A coke control reactor system comprising a riser reactor and bed reactor, which converts inactive large-molecule coke species into small-molecule coke species like polymethylbenzene and polymethylnaphthalene, improving ethylene selectivity, and a methanol conversion reactor with gas-solid separation units to optimize catalyst activity and separation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If new generation DMTO catalyst with high methanol processing capacity is used, then productivity is improved, but existing devices cannot fully utilize the catalyst advantages due to poor coke control
Solution Approach 1:
The device is divided into two independent reactors: a regenerator that separates coke from the catalyst, and a reaction reactor where methanol conversion occurs. This segmentation allows the catalyst to be regenerated in situ, maintaining high activity and enabling full utilization of the new generation catalyst's high processing capacity without being limited by coke accumulation.
Solution Approach 2:
The regenerator performs preliminary coke removal from the catalyst before it enters the reaction reactor. By pre-regenerating the catalyst in the regenerator, the system ensures that highly active catalyst is always available for methanol conversion, maximizing the utilization of the new generation catalyst's capabilities from the start of each reaction cycle.
2Device complexity
If catalyst is continuously used without regeneration, then device complexity is reduced, but coke accumulation decreases ethylene selectivity
Solution Approach 1:
The regenerator and reaction reactor are merged into a single integrated device, sharing common structures such as the reactor shell, distributor, and gas-solid separator. This merging allows coke control functionality to be added without significantly increasing overall device complexity, while still achieving high ethylene selectivity through continuous catalyst regeneration.
3Device complexity
If coke species are not controlled, then process simplicity is maintained, but product gas selectivity remains at 80 wt%
Solution Approach 1:
The system changes the operational parameters by introducing a separate regeneration phase with controlled atmosphere (air for oxidation, then nitrogen for cooling and transport). This parameter change enables the conversion of coke into removable species and restores catalyst activity, achieving product gas selectivity of 92-96 wt% ethylene without requiring complex additional processing units.
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 achieves a coke controlled catalyst with high selectivity for low-carbon olefins, increasing product gas selectivity from 80 wt% to 92-96 wt% and reducing unit consumption of methanol by 10-15%, while maintaining a narrow coke content distribution.
Implementation Method 1
a regenerator configured to deliver the spent catalyst to a coke control reactor
Implementation Method 2
a gas-solid separator configured to separate the fluid stream into a gas phase stream and a solid phase stream
Data Source
AI summary
A coke control reactor, a device for preparing low-carbon olefins from an oxygen-containing compound, and a use thereof are provided. The coke control reactor includes a riser reactor and a bed reactor; the bed reactor includes a bed reactor shell, and the bed reactor shell encloses a reaction zone I, a transition zone, and a gas-solid separation zone I from bottom to top; a bed reactor distributor is arranged in the reaction zone I; a coke controlled catalyst delivery pipe is arranged outside the reaction zone I; an upper section of the riser reactor penetrates through a bottom of the bed reactor and is axially inserted in the bed reactor; and an outlet end of the riser reactor is located in the transition zone. The coke control reactor can control the conversion and generation of coke species in a catalyst.