Pneumatic DRI Transport for Steelmaking Plants
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Solution Overview
Problem
Existing mini-mill steelmaking plants face challenges in efficiently coordinating the continuous production of hot direct reduced iron (DRI) with the batch operation of electric arc furnaces, leading to high operational and investment costs, and limitations in DRI transport distance and structural support requirements.
Innovation Solution
A steelmaking plant design featuring a direct reduction reactor, a DRI melting furnace, a disengagement buffer bin, a dosing depressurizing bin, and a pneumatic transport system that allows continuous and flexible conveyance of hot DRI using a carrier gas, with a series bin arrangement that minimizes interruptions and structural height, enabling efficient matching of DRI production with melting furnace operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a pneumatic transport system is used to convey hot DRI, then flexibility and transport distance are improved, but device complexity increases
Solution Approach 1:
The patent employs a pneumatic transport system where hot DRI is conveyed through a gas stream from the reduction reactor to the EAF. This allows flexible transport over distances and around obstacles without requiring complex mechanical conveyors, though the system does require gas handling infrastructure.
Solution Approach 2:
A buffer bin is introduced as an intermediary between the reduction reactor and the EAF. This buffer bin receives hot DRI from the pneumatic transport system and feeds it to the EAF, decoupling the continuous production from the batch operation and simplifying the overall system coordination.
2Productivity
If hot DRI is transported to the EAF, then productivity is improved, but loss of substance occurs due to re-oxidation
Solution Approach 1:
The pneumatic transport system uses an inert or reducing gas atmosphere to convey hot DRI from the reduction reactor to the EAF. This protects the hot DRI from re-oxidation by atmospheric oxygen during transport, maintaining the metallization content while enabling continuous production.
3Ease of manufacture
If the height of the reduction reactor supporting structure is minimized, then investment cost is reduced, but gravity-aided transport capability is limited
Solution Approach 1:
The patent replaces gravity-aided mechanical transport with a pneumatic transport system. This eliminates the need for tall supporting structures to enable gravity flow, as the gas stream provides the driving force for transporting hot DRI over the required distance horizontally or with minimal elevation change.
4Ease of operation
If a series bin arrangement is used to coordinate continuous production with batch operation, then ease of operation is improved, but device complexity increases
Solution Approach 1:
The system is divided into functional segments: a reduction reactor for continuous DRI production, a buffer bin for holding and decoupling, and an EAF for batch melting. The series bin arrangement segments the transport and storage functions, allowing each component to operate independently at its optimal pace while coordinating overall production and melting operations.
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
The solution reduces operational and investment costs, enhances flexibility in DRI transport, and minimizes structural support heights, improving the overall efficiency and cost-effectiveness of mini-mill steelmaking plants by ensuring continuous and uninterrupted DRI flow to the melting furnace.
Implementation Method 1
a pneumatic transport apparatus for conducting said hot DRI with a carrier gas from said reactor discharge to feed selectively, at a level above the level of said reactor discharge, either said furnace via said series of bins or said cooler
Implementation Method 2
said disengagement buffer bin having in addition to a space in the upper portion thereof sufficient to disengage DRI from the carrier gas
Implementation Method 3
a dosing depressurizing bin located in series between said disengagement buffer bin and said melting furnace and having a capacity to hold a charge of DRI of at least one heat size for said furnace
Implementation Method 4
This patent also does not teach or suggest any solution for the practical match of the continuous hot DRI production and the batch operation of the hot DRI melting furnace... where there is the need of minimizing the operational and investment costs of the mini-mill plant
Data Source
AI summary
A steelmaking plant including a pressurized direct reduction reactor for continuous production of hot direct reduced iron with a batch-melting furnace and a standby cooler, all three being capable of being situated side-by-side, with such DRI being able to be alternatively fed to the furnace or to the cooler. The furnace is selectively charged through a diverter valve by a pneumatic transport system with the hot DRI being entrained in a carrier gas fed into a receiving bin (having an upper DRI/gas disengagement space and a lower DRI buffer portion). A pressurized charge of the DRI accumulated in such disengaging/buffer bin is periodically fed down into a dosing/depressurization bin which in turn depressurizes the DRI and feeds a batch of DRI down into the furnace. Upon sensing that the buffer portion is full, the DRI is then pneumatically diverted to the cooler, such as during furnace maintenance shut down.