Parallel Valve Ammonia Injection for Combustion Plants
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Solution Overview
Problem
Existing methods for reducing NOx emissions in combustion plants face challenges such as nozzle blocking, difficulty in controlling ammonia flow, and ammonia slip, especially under varying combustion conditions or fuel types, which complicates efficient NOx reduction.
Innovation Solution
A system with multiple valve members connected in parallel, controlled by a unit to maintain a continuous flow of either ammonia-containing fluid or dilution fluid, ensuring a constant concentration of ammonia injection into the exhaust gas passage, reducing the risk of blocking and allowing precise control of ammonia dosage based on combustion conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ammonia is injected into the exhaust gas passage to reduce NOx emissions, then NOx reduction efficiency is improved, but nozzle blocking and flow control difficulty occur
Solution Approach 1:
The system divides the ammonia injection function into multiple parallel valve members (first, second, third valve members) instead of using a single valve. Each valve member can be independently controlled to manage ammonia flow, preventing blocking issues and improving flow control precision under varying combustion conditions.
Solution Approach 2:
The control unit dynamically adjusts the opening degrees of different valve members based on real-time combustion conditions, load variations, and fuel types. This dynamic control enables precise ammonia dosage adjustment to maintain optimal NOx reduction while preventing ammonia slip and blocking.
2Reliability
If ammonia flow is increased to reduce NOx emissions, then NOx reduction efficiency is improved, but ammonia slip occurs
Solution Approach 1:
The control unit receives feedback signals from sensors monitoring exhaust gas composition, temperature, and flow conditions. Based on this feedback, the control unit continuously adjusts the ammonia injection rate by modulating valve member openings to achieve precise dosage control, ensuring complete NOx reduction without excess ammonia slip.
Solution Approach 2:
The system dynamically adapts ammonia injection rates to varying combustion conditions, load levels, and fuel types. The control unit optimizes the opening degrees of parallel valve members in real-time to maintain the precise ammonia dosage needed for effective NOx reduction while preventing ammonia slip under all operating conditions.
3Device complexity
If a single valve controls ammonia flow, then device complexity is reduced, but blocking risk and control precision deteriorate
Solution Approach 1:
Instead of using a single valve, the system employs multiple parallel valve members (at least three) that can be independently controlled. This segmentation distributes the ammonia flow control function across multiple components, reducing the blocking risk in each individual valve while maintaining overall system reliability and improving control precision.
Solution Approach 2:
Each valve member in the parallel configuration can be optimized for specific local conditions and controlled independently based on its performance characteristics. This allows the system to maintain precise flow control and reduce blocking risk by distributing the workload and enabling localized adjustments without affecting the entire system.
Data Source
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AI summary
Method of and an arrangement (10, 100) for feeding ammonia containing fluid into an exhaust gas passage (22) of a combustion plant comprising a first fluid line (40) connectable in flow connection with a source of an ammonia containing fluid (14), a second fluid line (42) in flow connection with a source of a dilution fluid (12) and a control unit (38, 380) for controlling multiple valve members of a valve unit (30), each of the valve members having a first inlet (34, 340) in flow connection with the first fluid line, a second inlet (32, 320) in flow connection with the second fluid line and an outlet (36, 360) in flow connection with an outlet channel (48, 480) connected to the exhaust gas passage (22), wherein the valve members are connected in parallel so that the outlet of each of the valve members is in flow connection with a common outlet channel (48, 480), wherein the control unit is adapted for controlling each of the valve members to maintain open flow path from either the first inlet (34, 340) or the second inlet (32, 320) to the outlet (36, 360) so as to feed a flow of either the ammonia containing fluid or the dilution fluid via the valve member to the outlet channel (48, 480).