Internal Loop Reactor Draft Tube Curvature for Pressure-Loss Reduction
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Solution Overview
Problem
Existing internal loop reactors face challenges in achieving high circulation ratios due to flow separation at the draft tube outlets, leading to increased pressure loss and reduced mixing efficiency.
Innovation Solution
The design of the draft tube features a convex curvature on both the inner and outer surfaces, with a constriction closer to the inlet end and a circumferential protuberance closer to the outlet end, minimizing flow separation and optimizing fluid flow through the reactor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a draft tube is used to enhance mixing, then circulation ratio is improved, but flow separation occurs at the draft tube outlet leading to increased pressure loss
Solution Approach 1:
The draft tube features a convex curvature on its inner surface that extends over at least 70% of the tube length, creating a streamlined flow path that reduces flow separation at the outlet. The rounded edges of the draft tube further minimize turbulence and pressure loss while maintaining high circulation ratios.
Solution Approach 2:
The draft tube design incorporates a constriction of the cross-section located closer to the tube inlet end, creating localized flow acceleration and enhanced mixing in specific zones. This local modification optimizes the flow pattern without compromising overall circulation efficiency.
2Productivity
If the draft tube outlet is designed to maximize flow, then circulation ratio increases, but flow separation increases pressure loss
Solution Approach 1:
The convex curvature of the draft tube inner surface and rounded edges eliminate sharp corners that cause flow separation. This streamlined geometry allows fluid to follow the tube contour smoothly, reducing turbulent eddies and pressure losses while maintaining high circulation ratios.
3Ease of manufacture
If the draft tube geometry is simplified, then manufacturing is easier, but mixing efficiency decreases
Solution Approach 1:
The convex curvature can be implemented using standard piping bends or formed during extrusion processes, making the design manufacturable with conventional techniques. The rounded edges can be achieved through standard machining or forming operations, balancing manufacturing simplicity with enhanced mixing 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 design results in a higher circulation ratio, reducing pressure drop and enhancing mixing efficiency, allowing for improved reactant mixing and reaction selectivity.
Implementation Method 1
Flow separations may occur, e.g., at the draft tube outlet, which increases the pressure loss and leads to a reduced circulation ratio
Implementation Method 2
The invention allows control of the boundary layer flowing over the edge of the draft tube
Implementation Method 3
The flow pattern generated by the draft tube is a recirculating flow, which may be characterized by the circulation ratio
Implementation Method 4
the first conduit(s) exhibit(s) an annular constriction of the cross-section between the tube inlet end and the tube outlet end
Data Source
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AI summary
An internal loop reactor comprises: a vertically disposed cylindrical vessel comprising a sidewall and reactor fluid outlet means; and at least one draft tube arranged vertically within the vessel. The draft tube(s) have/s an inner surface and an outer surface, wherein the draft tube(s) provide(s) (a) first conduit(s) within the draft tube(s) having a tube inlet end and a tube outlet end, and a second conduit outside of the draft tube(s) and within the sidewall, the first conduit(s) being in fluid communication with the second conduit. The reactor comprises at least one nozzle arranged concentrically to the draft tube(s)for injecting a fluid into the first conduit(s) from the tube inlet end. The inner surface of the draft tube(s) convexly curves so that the first conduit(s) exhibit(s) an annular constriction of the cross-section between the tube inlet end and the tube outlet end; wherein the constriction is located closer to the tube inlet end. Further, the outer surface of the draft tube(s) convexly curves, so that the draft tube(s) exhibit(s) a circumferential protuberance between the tube inlet end and the tube outlet end. The invention further relates to a process for performing a continuous high-pressure reaction, wherein a fluid is introduced into the internal loop reactor, and a reacted fluid is removed via the fluid outlet of the loop reactor. The curved shape of the inner surfaces of the draft tube wall(s) guides the fluid through the draft tube(s) in an optimized manner.