FCC Regenerator NOx Reduction via Catalyst Bed
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Solution Overview
Problem
Fluid catalytic cracking units emit significant amounts of nitrogen oxides (NOx) into the atmosphere, and existing methods for reducing NOx emissions are not sufficient, necessitating further improvements.
Innovation Solution
A process involving the addition of supported transition or lanthanide metal catalysts to NOx-containing flue gas, combined with ammonia or its precursors, to reduce NOx levels through catalytic reaction in a collecting means, forming a catalyst bed within an electrostatic precipitator or similar collecting device, at temperatures ranging from 200° C to 800° C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If ammonia is added to reduce NOx emissions, then NOx reduction efficiency is improved, but device complexity increases due to additional injection systems and catalyst handling
Solution Approach 1:
The FCC catalyst serves dual purposes: its primary function in cracking hydrocarbons and a secondary function as a NOx reduction catalyst in the regenerator. The catalyst naturally accumulates in the regenerator and forms a bed that provides NOx reduction capability without requiring separate catalyst injection systems or additional catalyst handling infrastructure.
Solution Approach 2:
The FCC catalyst is made multi-functional by enabling it to perform both cracking catalysis and NOx reduction catalysis. The same catalyst material that cracks heavy hydrocarbons also reduces NOx to N2 in the presence of ammonia, eliminating the need for separate catalyst systems for each function.
2Object-generated harmful factors
If a catalyst bed is formed in the collecting means, then NOx reduction efficiency is improved, but loss of catalyst material increases due to potential entrainment in flue gas
Solution Approach 1:
The collecting means, which already exists to capture catalyst particles from the regenerator, serves an additional function of containing the NOx reduction catalyst bed. The catalyst particles are naturally retained by the collecting means structure, preventing their loss in the flue gas while maintaining their catalytic function.
Solution Approach 2:
The function of the collecting means is merged to simultaneously perform catalyst particle recovery and NOx reduction catalysis. The same collecting means that captures catalyst fines also houses the catalyst bed that reduces NOx, combining two functions into one device.
3Productivity
If operating temperature is increased to improve reaction rate, then NOx reduction speed is improved, but energy consumption increases
Solution Approach 1:
The catalyst changes the reaction parameters by providing an alternative reaction pathway with lower activation energy. This allows the NOx reduction reaction to proceed efficiently at the existing flue gas temperatures (200-800°C) without requiring additional heating energy, as the catalyst enables the reaction to occur at these moderate temperatures.
Solution Approach 2:
The flue gas itself provides the thermal energy required for the NOx reduction reaction. The high temperature flue gas from the regenerator naturally heats the catalyst bed to the required reaction temperature, eliminating the need for external heating systems or additional energy input.
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 effectively reduces NOx emissions by up to 60% or more, producing a flue gas with lower nitrogen oxide concentrations, which can be discharged safely, and can be applied to any combustion process.
Implementation Method 1
NOx in the flue gas is reacted with the ammonia or ammonia precursor at a temperature ranging from 200° C. to 800° C. in the presence of the catalyst bed to reduce the amount of NOx in the flue gas
Data Source
AI summary
The invention includes a process for reducing the amount of NOx discharged to atmosphere from a FCC unit, having a regenerator and a means for collecting and supporting catalyst particles. The process comprises adding a catalyst to the regenerator flue gas prior to entering the collecting means and precipitating the catalyst in the collecting means to form a catalyst bed. Ammonia or ammonia precursor is added to the flue gas prior to and/or within the collecting means. The flue gas NOx is reacted with the ammonia or ammonia precursor at 200° C. to 800° C. in the presence of the catalyst bed to reduce the NOx amount, and the flue gas containing a reduced amount of NOx is discharged to atmosphere. The catalyst is one or more supported transition or lanthanide metal catalysts. The process can also be utilized in any combustion process.