Inverted Frustoconical Fluidised Bed Reactor for Gasification
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Solution Overview
Problem
Fluidised bed gasification reactors with cylindrical geometry face challenges in achieving complete degradation of organic solids due to insufficient retention time, leading to high unburned combustion residues and reduced carbon conversion to gas, as the flow pattern predominantly causes upward entrainment of solids before complete degradation.
Innovation Solution
The reactor design incorporates an inverted frustoconical section with a distributor grid and tuyere-type diffusers, modifying the flow pattern to promote a downward path for organic solids upon entry, increasing retention time within the bed through enhanced circulation, thereby distributing the time spent from entry to the bottom, top coverage, and degradation before being entrained as ash or gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a cylindrical reactor geometry is used with upward gas flow, then the reactor structure is simple and gas flow is easy to distribute, but the retention time of organic solids is insufficient leading to incomplete degradation
Solution Approach 1:
The patent applies asymmetry by replacing the conventional cylindrical reactor geometry with a conical reactor geometry. The conical shape creates asymmetric flow patterns that force organic solids to follow a downward path along the reactor walls before being entrained upward, significantly increasing retention time and degradation completeness while maintaining relatively simple reactor construction.
Solution Approach 2:
The patent inverts the conventional flow pattern by using a conical geometry that promotes downward movement of solids against the typical upward gas flow direction. This inversion allows solids to spend more time in the reactor by traveling down the conical walls before being carried upward, resolving the retention time issue without complex internal structures.
2Productivity
If the gas flow rate is increased to enhance carbon conversion, then the productivity improves, but the unburned combustion residues increase due to insufficient retention time
Solution Approach 1:
The conical geometry creates asymmetric flow patterns that extend the residence time of organic solids through the reactor. This allows higher gas flow rates to be used for improved productivity while the extended retention time ensures complete degradation, preventing increase in unburned residues.
3Productivity
If a fluidised bed reactor is used to improve mixing and heat transfer, then the process efficiency increases, but the particle size requirements and fluidisation losses occur
Solution Approach 1:
The patent applies local quality by creating different flow regimes in different regions of the conical reactor. The downward flow along the walls provides gentle mixing suitable for larger particles, while the upward entrainment zone provides intense mixing for complete degradation. This local differentiation allows the reactor to handle a broader range of particle sizes while maintaining high process efficiency.
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 configuration increases the retention time of organic solids, resulting in a higher carbon conversion rate to gas, reduced unburned residues, and a more homogeneous mixture of inert and catalyst materials, as evidenced by increased CO2 concentration and reduced char and tar production.
Implementation Method 1
by means of a gas flow that entrains the solid particles
Implementation Method 2
distributing the fluidising agent through the lower base of the inverted frustoconical section, wherein there is a distributor grid provided with a plurality of outlet holes
Data Source
Figure 1
Figure 2~3
AI summary
The present invention relates to a process for gasification of organic solid materials in a fluidised bed reactor (1) with a cylindrical body and bottom (2) having an inverted frustoconical section, by means of a gas flow that entrains the solid particles and which comprises the steps of a.-) supplying fuel through an inlet (3) for feeding organic solid, b.-) supplying a catalytic agent and inert material through an inlet (7), c.-) introducing a fluidising agent through an inlet (6) located in the air box or plenum (12), d.-) distributing the fluidising agent through the lower base (2') of the inverted frustoconical section, in which there is a distributor grid (10) provided with a plurality of tuyere-type diffusers (11), and e.-) producing the outflow of the product stream through the top of the reactor (1).