Modular SCR Exhaust Gas Aftertreatment with Atomizing Nozzles
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Solution Overview
Problem
Existing SCR exhaust gas aftertreatment devices are costly and inefficient for internal combustion engines with large exhaust gas volumes and divided exhaust gas trains, as they struggle with ammonia distribution and urea injection, leading to suboptimal NOx reduction and potential damage from freezing temperatures.
Innovation Solution
The implementation of a modular SCR exhaust gas aftertreatment device with multiple metering units equipped with atomizing nozzles and pressure sensors, which enable precise urea injection and distribution, along with a diaphragm pump and proportional valve for efficient atomization and protection against freezing, ensuring high NOx reduction with low urea consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single-point urea injection system is used, then the device complexity is low, but the ammonia distribution in large exhaust gas volumes is insufficient
Solution Approach 1:
The exhaust gas train is divided into multiple sections with separate metering units and atomizing nozzles distributed throughout the system. Each metering unit independently injects urea solution into its designated exhaust gas stream, ensuring uniform ammonia distribution across large exhaust volumes while maintaining manageable system complexity through modular design
2Quantity of substance
If conventional injection methods are used, then the device complexity is low, but the reactive surface area of urea is insufficient
Solution Approach 1:
A diaphragm pump delivers urea solution under pressure through common lines to multiple metering units. The pressurized injection system creates fine atomization of the urea solution, dramatically increasing the reactive surface area available for NOx reduction reactions without requiring complex mechanical injection mechanisms
Solution Approach 2:
The system changes the physical state of urea from liquid solution to fine aerosol droplets through pressurized atomizing nozzles. This parameter change from bulk liquid to dispersed droplets increases the reactive surface area by several orders of magnitude, enhancing reaction efficiency
3Object-affected harmful factors
If the exhaust gas aftertreatment device operates in open circuits with aqueous urea solution, then the system is simple, but freezing temperatures can cause damage
Solution Approach 1:
The system takes preliminary anti-action against freezing by maintaining the aqueous urea solution in a liquid state through continuous circulation and pressure maintenance. The diaphragm pump keeps the solution under pressure in the common lines and metering units, lowering the freezing point and preventing ice crystal formation that would cause damage to the open circuit components
4Measurement precision
If multiple metering units with pressure sensors are used, then the metering precision is high, but the device complexity increases
Solution Approach 1:
Each metering unit is designed as a universal module that can be replicated multiple times throughout the exhaust gas train. The metering units use standardized components including pressure sensors, atomizing nozzles, and control valves that perform multiple functions: measuring pressure, regulating flow, and injecting urea. This modular universal design achieves high metering precision through consistent calibration while managing complexity through standardization
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 solution provides improved NOx reduction efficiency, reduced urea consumption, and protection against freezing, making it suitable for large engines like ship diesel engines and V/W engines, with a cost-effective modular design that simplifies maintenance and part replacement.
Implementation Method 1
a supply unit which has a diaphragm pump and a pressure filter
Implementation Method 2
a plurality of metering units, which have a metering valve and an atomizing nozzle, so that the AUS can be nozzle-injected at a plurality of points
Implementation Method 3
Present in accordance with the invention is a pressure sensor, which, in comparison to a purely mechanical—that is, spring-controlled—pressure regulation, enables a precise regulation of the pressure
Implementation Method 4
a proportional valve, which regulates the through-flow from the metering unit to the AUS tank
Implementation Method 5
Each of these metering valves feeds the ammonia into the partial train of an exhaust gas manifold, which is assigned to a combustion compartment of an internal combustion engine. In this way, nitrogen oxides (NOx) will be reduced in the exhaust gas
Data Source
AI summary
The invention relates to an SCR exhaust gas aftertreatment device, particularly for diesel motor internal combustion engines having a very large exhaust gas volume and/or divided exhaust gas trains. In order to be able to manufacture this SCR exhaust gas aftertreatment device in a cost-efficient manner, also for a high mixing degree of exhaust gas and AUS, it is proposed that a plurality of metering units (D1, D2, Dn) is provided, each of which has an atomizing nozzle, which nozzle-injects the aqueous urea solution into the exhaust gas train. In this case, the pressure existing in a common line for all metering units (D1, D2, Dn) can be determined by means of a pressure sensor.