Scrubber Return Channel for Symmetrical Particle Distribution
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Solution Overview
Problem
Existing dry CFB scrubbers face challenges in optimizing the distribution and entrainment of recycled particles, leading to inefficient pollutant removal and potential bed instability due to non-symmetrical particle release and low gas velocity zones, which increases system height and complexity.
Innovation Solution
A scrubber design with a centrally arranged venturi nozzle and an annularly arranged return channel ensures even distribution of recycled particles by releasing them adjacent to the venturi nozzle, where they can be entrained by a high-velocity gas stream, separating coarse fractions and optimizing particle distribution to the reaction chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If recycled particles are introduced from a bottom hopper through a sloping recycling channel and feeding nozzle to a side of an expanding downstream portion of the vertical constriction section, then the scrubber system can maintain particle circulation, but the total height of the scrubber system becomes relatively large
Solution Approach 1:
The return channel is configured to introduce recycled particles horizontally into the inlet chamber rather than vertically from above. This dimensional change in particle introduction direction allows the system to maintain particle circulation while reducing the overall vertical height of the scrubber structure.
Solution Approach 2:
Instead of introducing recycled particles from the top or upper portion of the constriction section as in conventional designs, the invention introduces particles from the inlet chamber at the bottom portion of the constriction section. This inverted approach reduces system height while maintaining circulation effectiveness.
2Length of stationary object
If recycled particles are introduced to the inlet chamber where gas velocity is relatively low, then system height is reduced, but a too large portion of recycled particles tends to sink to the bottom of the inlet chamber
Solution Approach 1:
The return channel is positioned to introduce recycled particles at a specific location in the inlet chamber where local gas flow conditions are optimized for entrainment. This localized introduction point ensures that particles are picked up by the upward gas stream rather than sinking to the bottom, maintaining high entrainment efficiency.
Solution Approach 2:
The inlet chamber acts as an intermediary zone where recycled particles are introduced and immediately mixed with the upward-moving gas stream. This intermediary region facilitates smooth transition and entrainment of particles into the reaction chamber, preventing particle settling while maintaining compact system height.
3Ease of operation
If the feeding nozzle is arranged at a relatively high vertical level in the scrubber, then particle distribution can be achieved, but the total height of the scrubber system becomes relatively large
Solution Approach 1:
The invention changes the vertical dimension of particle introduction by using a horizontal return channel that feeds particles into the inlet chamber from the side. This dimensional reconfiguration achieves effective particle distribution throughout the reaction chamber while maintaining a compact vertical profile.
Solution Approach 2:
The particle introduction function is segmented into separate components: the return channel for horizontal particle transport and the inlet chamber for vertical gas-particle mixing. This segmentation allows particle distribution to be achieved without requiring high vertical placement of the feeding mechanism.
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 design enhances pollutant removal efficiency by ensuring even and symmetrical particle distribution, preventing bed instability, and reducing the risk of agglomeration, while maintaining a compact system configuration.
Implementation Method 1
a constriction section having a vertical axis of symmetry and comprising a centrally arranged venturi nozzle, the constriction section being above and in flow connection with an upper end of the inlet chamber for accelerating the vertical gas stream
Implementation Method 2
distributing the recycled particles evenly through a vertical end section of the return channel arranged annularly around the centrally arranged venturi nozzle to a zone adjacent the lower end of the centrally arranged venturi nozzle to entrain a fine fraction of the recycled particles with the vertical gas stream
Implementation Method 3
a particle separator for separating particles including the reaction products from the gas
Data Source
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AI summary
A method of and a scrubber (18) for removing pollutant compounds from a gas stream, comprising at least one gas channel (14, 106) for introducing the gas stream to a lower portion of the scrubber;an inlet chamber (20, 64) for directing the gas stream upwards to form a vertical gas stream;a constriction section (24, 4) having a vertical axis of symmetry (68) and comprising a centrally arranged venturi nozzle (52, 88), the constriction section being above and in flow connection with an upper end of the inlet chamber (20, 64);a reaction chamber (28, 78) arranged above and in flow connection with the constriction section; means for introducing at least one reagent (30, 30', 30'') to the reaction chamber for converting pollutant compounds in the gas stream to reaction products;a discharge channel (34) in flow connection with the reaction chamber for discharging gas and particles including the reaction products from the reaction chamber;a particle separator (36) in flow connection with the discharge channel; and a return channel (46) for continuously recycling a portion of separated particles from the particle separator to the reaction chamber;wherein the return channel comprises a vertical end section (50) arranged annularly around the centrally arranged venturi nozzle (52, 88), a lower end (56) of the vertical end section being in flow connection with the inlet chamber (64) so as to distribute recycled particles evenly to a zone adjacent the lower end of the centrally arranged venturi nozzle (92) to entrain a fine fraction (102) of the recycled particles with the vertical gas stream and to separate a coarse fraction (104) of the recycled particles to a lower portion (82) of the inlet chamber (64).