Electric Heating Block Segmentation for Carbon Deposit Removal
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Solution Overview
Problem
In direct reduction plants using electric heaters, carbon deposition on heating elements occurs due to the high carburizing potential of recycled reduction gases, leading to overheating and potential damage to the heaters. This requires intermittent shutdowns for carbon burnout, disrupting production.
Innovation Solution
A method and system where make-up hydrogen or hydrogen with added steam is introduced to specific blocks of the electric heating system to remove carbon deposits, allowing continuous production of DRI containing carbon by alternating between hydrogen and recycled gas in different blocks of the heating system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If recycled reduction gas with high carburizing potential is used to heat the electric heater, then CO2 emissions are minimized, but carbon deposits on the heating elements causing overheating and damage
Solution Approach 1:
The electric heater is divided into multiple heating blocks that can be independently controlled. This allows selective operation where some blocks process recycled reduction gas while others are dedicated to carbon removal, enabling continuous operation without shutdowns.
Solution Approach 2:
A steam injection system is introduced as an intermediary mechanism to facilitate carbon removal. Steam is injected into specific heating blocks to promote carbon burnout and deposit removal, enabling the system to handle the carbon deposition issue without stopping production.
2Reliability
If carbon burnout is conducted with oxidized gas to remove carbon deposits, then heating element damage is prevented, but production must be stopped and plant must be idle
Solution Approach 1:
The heating system is segmented into multiple independent blocks, allowing carbon removal operations to be performed on individual blocks while other blocks continue heating recycled reduction gas, thus maintaining continuous production.
Solution Approach 2:
The system enables continuous carbon removal and continuous production simultaneously by distributing different functions across multiple heating blocks, eliminating the need for production shutdowns that were required in single-block systems.
3Manufacturing precision
If carbonaceous gas or material is introduced into the shaft furnace to produce DRI containing carbon, then product quality for downstream melting is improved, but carbon deposition on electric heater increases
Solution Approach 1:
The heating system is divided into carbon-removal-dedicated blocks and normal heating blocks, allowing the system to tolerate higher carbon deposition rates in normal operation while having dedicated capacity for carbon removal without affecting production.
Solution Approach 2:
The system converts the harmful carbon deposition into a manageable process by using dedicated heating blocks with steam injection to actively remove carbon, transforming the previously problematic side effect into a controlled operational parameter.
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 approach enables the continuous removal of carbon deposits from electric heating elements without interrupting DRI production, maintaining productivity and product quality while minimizing CO2 emissions.
Implementation Method 1
the introduction of the make-up hydrogen or the make-up hydrogen with the added steam to a partial block of the electric heating system to remove the carbon deposition
Implementation Method 2
the introduction of the make-up hydrogen with the added steam to a partial block of the electric heating system to remove the carbon deposition
Implementation Method 3
thereafter the recycled hydrogen rich reduction gas is heated with an electric gas heating system
Implementation Method 4
a direct reduction shaft furnace adapted to reduce iron oxide to metallic iron with hydrogen rich reduction gas
Data Source
AI summary
A direct reduction method and system including an electric heater system adapted to heat a reduction gas and a shaft furnace adapted to receive and utilize the heated reduction gas and one or more of a carbonaceous gas and/or material to produce the direct reduced iron containing carbon, including: providing the reduction gas to an electric heating elements of the electric heater system to heat the reduction gas; stopping the providing the reduction gas; and providing a hydrogen gas or a hydrogen gas with added steam to remove carbon deposition from the electric heating elements of the electric heater system while continuing to heat the reduction gas such that the direct reduced iron production including carbon is not interrupted.