Fluidized Bed Catalyst for NOx and CO Removal
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Solution Overview
Problem
Existing catalytic gas purification systems using fixed bed catalysts suffer from high pressure drop and reduced performance, limiting their application in large fuel combustion objects due to the limited surface availability of catalytic elements for pollutant conversion.
Innovation Solution
A fluidized bed system created by a high voltage electric field is used with moving granular catalysts, allowing for enhanced contact between catalytic grains and gas flow, utilizing lightweight substrates like expanded clay aggregate and volcanic stone with active metal oxide coatings to achieve efficient NOx and CO removal with low aerodynamic resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed bed catalysts are used for gas purification, then catalytic conversion of pollutants occurs, but pressure drop increases significantly reducing system performance
Solution Approach 1:
The patent transforms the static fixed bed catalyst into a dynamic fluidized bed catalyst system. By introducing fluidizing gas through distributors at the bottom of the catalytic chamber, the catalyst particles are suspended and fluidized, creating dynamic contact between gas and catalyst surfaces. This dynamic state reduces pressure drop while maintaining high purification efficiency through enhanced mass transfer and catalyst-gas interaction.
Solution Approach 2:
The patent changes the physical state and flow parameters of the catalyst from stationary to fluidized by controlling gas velocity and flow distribution. By adjusting the fluidizing gas velocity to achieve minimum fluidization conditions, the system transitions from high-pressure-drop fixed bed mode to low-pressure-drop fluidized bed mode, resolving the contradiction between purification efficiency and pressure drop.
2Quantity of substance
If fixed bed catalyst elements are packed closely, then catalyst loading volume is maximized, but surface area available for pollutant conversion is reduced
Solution Approach 1:
In the fluidized bed system, catalyst particles are suspended in the gas stream, creating continuous movement and expansion of the catalyst bed. This dynamic state increases the effective surface area exposed to pollutants compared to packed fixed bed configuration, as particles are constantly repositioned and their external surfaces are fully accessible. The system maintains high catalyst loading while maximizing active surface area through fluidization.
Solution Approach 2:
The patent utilizes porous catalyst particles with high internal surface area. The fluidized bed configuration ensures that both external and internal porous surfaces are accessible to pollutants. The combination of porous catalyst structure and fluidized bed hydrodynamics maximizes the effective surface area for catalytic conversion while maintaining reasonable catalyst loading volume.
3Reliability
If porous catalysts are used to increase mass transfer coefficient, then purification efficiency improves, but aerodynamic resistance increases limiting widespread application
Solution Approach 1:
The fluidized bed system dynamically suspends porous catalyst particles in the gas stream, creating intense turbulence and mixing. This dynamic configuration maximizes the mass transfer benefits of porous catalysts by ensuring continuous renewal of the gas-catalyst interface and eliminating boundary layer effects. Simultaneously, the fluidized state reduces overall aerodynamic resistance compared to densely packed porous catalyst beds, resolving the contradiction between mass transfer efficiency and ease of operation.
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 fluidized bed system achieves high purification efficiency with reduced pressure drop, ensuring effective conversion of NOx and CO while maintaining system performance, and the use of lightweight substrates simplifies the process and reduces costs.
Implementation Method 1
A fluidized bed system created by a high voltage electric field is used with moving granular catalysts
Implementation Method 2
A fluidized bed system created by a high voltage electric field
Implementation Method 3
catalytic grains and gas flow, utilizing lightweight substrates like expanded clay aggregate and volcanic stone with active metal oxide coatings to achieve efficient NOx and CO removal
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~4
AI summary
The invention relates to apparatus and methods for catalytic purification of gas emissions, in particular to the purification of gas emissions from nitrogen oxides NOx and carbon monoxide CO. The apparatus for the purification of gas emissions comprises two sequentially located CO oxidation and NOx reduction catalysts with the load of catalytic grains (6) which are located between the small-meshed grids (5) and plates (13, 14) and which during the purification of gas emissions operate as a fluidized bed (10) created by the influence of the high voltage electric field on the catalytic load. The catalytic grains consist of the substrate material, such as lightweight expanded clay aggregate or the volcanic stone, coated with an active layer of transition metal oxides, such as bimetallic or polymetallic oxide coating. The fluidized bed created under the influence of the electric field ensures good contact between the catalytic grains and the gas flow components CO and NOx thus providing an effective conversion of the latter to carbon dioxide CO2 and molecular nitrogen N2.