Direct Reduction Shaft Gas Inlets With Compact Electric Preheating
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Solution Overview
Problem
Existing systems for direct reduction of iron ore to sponge iron suffer from large preheating arrangements that occupy significant space and result in heat losses due to excessive inactive gas volume, necessitating a redesign that maintains the integrity of the shaft components and reaction chamber volume.
Innovation Solution
The system employs individual inlets through the outer wall with compact electric heater devices positioned closely around the outer periphery, eliminating the need for a ring-shaped body and reducing the inactive gas volume by using vertically extended electric resistance elements in the gas lines, allowing for efficient heating and distribution of reduction gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a ring-shaped body with a ring-shaped gas line is used to distribute reduction gas around the inner wall, then the reduction gas can be distributed around the process chamber, but the outer wall must have an excessively large inner diameter in the region of the ring-shaped body, leaving a substantial gas-filled space between the outer wall and the inner wall
Solution Approach 1:
The patent divides the single ring-shaped gas line into multiple separate gas lines, each extending through its own inlet in the outer wall. This segmentation eliminates the need for a large ring-shaped body, allowing the outer wall to maintain a consistent, smaller inner diameter while still achieving comprehensive gas distribution through multiple distributed inlets.
2Temperature
If a preheating arrangement with a main gas line is used to heat reduction gas before it enters the process chamber, then the reduction gas reaches the required temperature, but the preheating arrangement occupies a substantial area and hot gas has to be transported considerable distance
Solution Approach 1:
The patent segments the preheating function into multiple compact electric heater devices distributed around the outer periphery of the outer wall, each associated with a specific gas line inlet. This eliminates the need for a single large preheating arrangement located at a distance, allowing gas to be heated in-situ right before entering the process chamber.
Solution Approach 2:
The patent replaces the mechanical fossil fuel burner arrangement with electric heater devices. This substitution enables compact, distributed heating elements that can be positioned close to the inlets, eliminating the need for large-distance gas transport and reducing the footprint of the heating system.
3Ease of operation
If a ring-shaped body is arranged on the outer periphery of the inner wall to house the gas line, then the gas line can be positioned around the process chamber, but the ring-shaped body locally adds considerable thickness to the heat resistant inner wall
Solution Approach 1:
The patent segments the gas line positioning function into multiple discrete inlets distributed around the outer wall, eliminating the need for a continuous ring-shaped body. This allows the heat resistant inner wall to maintain a uniform, minimal thickness while gas lines are positioned individually through separate inlets in the outer wall.
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 minimizes heat losses and space occupation while maintaining the structural integrity of the shaft components, enabling a more compact and efficient direct reduction process.
Implementation Method 1
each respective heater device comprises an electric heater device... each heater device comprises one or more electric resistance elements arranged in a channel which forms part of the respective gas line
Data Source
Figure 1
Figure 2
AI summary
A system for direct reduction of iron ore to sponge iron, comprising a direct reduction shaft (1) comprising an outer wall (2) configured to withstand a pressure generated in the reduction shaft (1) during operation thereof, and a heat resistant inner wall (3) configured to protect the outer wall (2) from heat and from direct contact with the iron ore that is reduced in the reduction shaft (1), the inner wall (3) being arranged inside the outer wall (2) and defining a process chamber (4) in which the reduction of the iron ore takes place. An arrangement (5) for introducing reduction gas into the process chamber (4) comprises a plurality of reduction gas inlets (6) extending through the outer wall (2) and through the inner wall (3), wherein at each inlet (6) there is provided a respective gas line (7) for conducting reduction gas to the respective inlet (6), and wherein each gas line (7) is provided with a respective heater device (8) arranged outside the outer wall (2) and configured to heat the reduction gas in the respective gas line (7) before the reduction gas enters the process chamber (4) through the respective inlet (6).