Condenser Unit for NOx Reduction System
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Solution Overview
Problem
Current methods for reducing NOx emissions in vehicles and locomotives are either expensive, require toxic chemicals, or are inefficient, particularly when using diesel fuel as a direct reductant, and face challenges with coking on SCR catalysts and space constraints for NOx traps.
Innovation Solution
A system and method utilizing a condenser unit with a built-in heat exchanger to separate and condense heavy hydrocarbons from light hydrocarbons, converting diesel fuel into a mixture of hydrocarbons in the C2-C12 range, plus H2 and CO, which are then injected into the engine exhaust stream to reduce NOx emissions using a selective catalytic reduction unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diesel fuel is directly injected into the exhaust stream as NOx reductant, then NOx reduction is achieved, but coking occurs on the SCR catalyst and the system becomes inefficient
Solution Approach 1:
The patent segments the hydrocarbon mixture by separating heavy hydrocarbons (C13+) from light hydrocarbons (C2-C12) using a condenser unit. The heavy hydrocarbons are condensed and removed, while the lighter hydrocarbons are fed to the SCR catalyst. This segmentation prevents coking by eliminating the heavy hydrocarbon component that causes it.
Solution Approach 2:
The patent extracts and removes the harmful heavy hydrocarbon component (C13+) from the diesel fuel mixture through condensation. By taking out this specific component, the system prevents coking on the SCR catalyst while maintaining the NOx reduction functionality of the remaining light hydrocarbons.
2Reliability
If a lean NOx trap system is used, then NOx emissions are reduced, but the system becomes expensive and requires considerable space
Solution Approach 1:
The patent changes the physical state parameter of the hydrocarbons by cooling the exhaust stream to condense heavy hydrocarbons. This parameter change enables separation without requiring complex chemical processes or large volumes, making the system more compact and cost-effective compared to traditional lean NOx trap systems.
Solution Approach 2:
The patent utilizes phase transition (condensation) to separate heavy hydrocarbons from light hydrocarbons. By cooling the gas stream, heavy hydrocarbons transition from gas to liquid phase and are removed, while light hydrocarbons remain in the gas phase and are fed to the SCR catalyst. This simple phase-based separation reduces system complexity and space requirements.
3Reliability
If ammonia or urea is used in SCR systems, then NOx emissions are reduced, but toxic chemicals must be carried and maintained on vehicles
Solution Approach 1:
The system uses the vehicle's own exhaust stream and fuel (diesel) as the reductant source. By converting a portion of the diesel fuel into light hydrocarbons through catalytic cracking and then using these hydrocarbons to reduce NOx in the exhaust, the system makes the exhaust stream serve its own purification purpose without requiring external toxic chemicals.
Solution Approach 2:
The patent changes the chemical composition parameter of the reductant from ammonia/urea-based to hydrocarbon-based. By altering the chemical nature of the reductant to match the fuel type (diesel), the system eliminates the need to carry and manage toxic chemicals while maintaining NOx reduction effectiveness.
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 approach effectively reduces NOx emissions without the need for toxic chemicals, increases fuel efficiency, and avoids the development of expensive infrastructure, achieving a significant reduction in NOx emissions while maintaining system robustness and efficiency.
Implementation Method 1
a heat exchanger disposed within the cavity along the cylindrical wall dividing the cavity into a lower cavity and an upper cavity, wherein the heat exchanger is configured to contact a gas entering the gas inlet and separate heavy hydrocarbons from light hydrocarbons
Implementation Method 2
separate heavy hydrocarbons, from condensation driven by dew point, from light hydrocarbons
Implementation Method 3
a selective catalytic reduction unit, the selective catalytic reduction unit in fluid communication with the condenser unit
Data Source
AI summary
A system and method for the reduction of NOx emissions from combustion sources are provided. The system includes a fuel tank, fuel converter unit, condensor unit, selective catalytic reduction (SCR) unit and an engine. The condenser unit includes a generally cylindrical inner wall defining a cavity having a first lower end and a second upper end, the first lower end is configured to include a gas inlet for receiving a gas mixture from the fuel converter and the second upper end is configured to include a gas outlet in fluid communication with the SCR unit. A heat exchanger is disposed within the cavity of the condensor unit to contact the gas mixture and separate heavy hydrocarbons from light hydrocarbons, wherein the light hydrocarbons are fed to the SCR unit and the heavy hydrocarbons are condensed and either send back to the fuel tank or directly to the engine for combustion.