Fluidized Catalytic Reactor Startup Using Coked Catalyst Combustion
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Solution Overview
Problem
The existing methods for starting up fluidized catalytic reaction apparatus for producing lower olefins from methanol or dimethyl ether are inefficient, consuming large amounts of diesel oil, producing carbon black pollution, and risking catalyst deactivation due to incomplete combustion and local superheating, especially when using SAPO-34 molecular sieve catalysts.
Innovation Solution
A process where methanol or dimethyl ether is fed to a reactor at elevated temperatures, causing a reaction that heats the reactor and subsequently coking the catalyst, which is then burned in a regenerator to rapidly increase the temperature to 540°C or above, eliminating the need for diesel oil spraying and minimizing catalyst deactivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If diesel oil is sprayed into the regenerator catalyst bed to increase temperature during startup, then the temperature can be increased rapidly, but a large amount of diesel oil is consumed and carbon black pollution is produced
Solution Approach 1:
The patent converts the harmful effect of coked catalyst (which needs to be burned off) into a beneficial heat source for regenerator startup. By deliberately coking the catalyst in the reactor using methanol or dimethyl ether, and then burning the coked catalyst in the regenerator, the system generates the necessary heat for startup without requiring external diesel oil spraying, thus eliminating diesel oil consumption and carbon black pollution.
2Temperature
If diesel oil is sprayed into the regenerator catalyst bed to increase temperature during startup, then the temperature can be increased rapidly, but carbon black pollution is produced and catalyst deactivation occurs due to incomplete combustion and local superheating
Solution Approach 1:
The patent converts the potentially harmful incomplete combustion of diesel oil into a controlled process by using pre-coked catalyst as the fuel source. The coked catalyst provides a uniform, predictable fuel source that burns completely and controllably, eliminating local superheating and incomplete combustion issues while generating necessary heat for regenerator startup.
Solution Approach 2:
The patent performs preliminary coking of the catalyst in the reactor before regenerator startup. This preliminary action creates a uniform distribution of combustible carbon on the catalyst particles, ensuring complete and uniform combustion during regenerator startup, thereby preventing local superheating and catalyst deactivation.
3Temperature
If external auxiliary heat-supplying equipments are used to increase bed temperatures during startup, then the temperatures can be increased, but very large amount of heat is needed and it is very difficult to increase the temperature when above 400°C
Solution Approach 1:
The patent converts the coked catalyst, which would normally be considered waste requiring regeneration, into a valuable internal fuel source. By burning the coked catalyst in the regenerator, the system generates its own heat for startup and temperature maintenance, eliminating the need for external auxiliary heat-supplying equipments and the associated large energy requirements.
Solution Approach 2:
The system becomes self-sufficient for heating during startup by using its own coked catalyst as fuel. The regenerator burns the coked catalyst to generate heat, which then heats the reactor catalyst, creating a self-sustaining thermal cycle that eliminates dependence on external auxiliary heating 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 process reduces startup costs, ensures long-term catalyst stability, shortens startup time, and enhances economic benefits by avoiding diesel oil consumption and catalyst damage, while maintaining efficient operation.
Implementation Method 1
a process technology for producing lower olefins by taking ZSM-5 zeolite as catalyst and methanol as raw material
Implementation Method 2
the heat released by the reaction of the raw material makes the temperature of the reactor increase quickly
Implementation Method 3
burning the coked catalyst to release heat so as to increase the temperature of the regenerator to 540°C or above rapidly
Implementation Method 4
a circulating fluidized apparatus including a reactor and a regenerator
Data Source
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AI summary
Disclosed is a process for starting up fluidized reaction apparatus which are used for producing lower olefins from methanol or/and dimethyl ether. Said process includes after heating the catalyst bed of circulating fluidized catalytic reaction apparatus to above 200 °C or 300°C by using a starting-up auxiliary heat source, feeding methanol or dimethyl ether raw materials to a reactor, whereby heat released by the reaction makes the temperature of the reaction system apparatus increase quickly to a designed temperature, consequently making the system reach the normal operation state rapidly. Said process is suitable for starting up an exothermic fluidized catalytic reaction apparatus and can simplify the apparatus and operation, accordingly lowering the cost.