Multiphase Heating Tubes for High-Temperature Gas Heating

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Solution Overview

Problem

Conventional methods for electrically heating gases, such as reducing gases for direct iron ore reduction, face high costs and limited lifetime due to the use of expensive resistance wires and high-current transformers, leading to high total cost of ownership and reduced operational efficiency at elevated temperatures.

Innovation Solution

An apparatus and method utilizing heating tubes connected to a transformer's multiphase outlet voltage, eliminating the need for high-current transformers by using heating tubes as electrical resistors, with specific electrical resistance configurations to achieve efficient heating without further transformation, and incorporating modular designs for improved durability and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If conventional resistance wires and high-current transformers are used for electrically heating gases, then heating capability is achieved, but total cost of ownership increases and lifetime decreases

Engineering Contradiction:

Improvegas heating temperatureVSAvoidheating element lifetime

Core Design Contradiction:

TemperatureVSDuration of action of moving object

Solution Approach 1:

The patent replaces conventional resistance wires with heating tubes that have integrated electrical resistance properties. The heating tubes function as both structural conduits for gas flow and electrical resistors, eliminating the need for separate fragile resistance wires and high-current transformers. This substitution of the heating mechanism extends lifetime to approximately ten years while maintaining effective gas heating capability at elevated temperatures.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Temperature

If conventional resistance wires are used for heating, then heating function is provided, but investment cost and operational cost increase significantly

Engineering Contradiction:

Improvegas heating temperatureVSAvoidtotal cost of ownership

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The heating tubes serve multiple functions simultaneously: they act as gas flow conduits, electrical resistors for heating, and structural support elements. This multi-functionality eliminates the need for separate resistance wires and high-current transformers, significantly reducing both investment cost and operational cost while maintaining effective heating capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Temperature

If fired heaters are used for heating reducing gas, then heating capability is achieved, but carbon dioxide emissions are generated

Engineering Contradiction:

Improvereducing gas temperatureVSAvoidcarbon dioxide emissions

Core Design Contradiction:

TemperatureVSObject-generated harmful factors

Solution Approach 1:

The patent replaces fired heaters that combust fossil fuels with an electrical resistance heating system using heating tubes. This substitution eliminates carbon dioxide emissions from fuel combustion while maintaining the necessary heating capability for reducing gas temperatures in iron ore reduction processes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 extends the lifetime of heating elements to approximately ten years at elevated temperatures, reduces operational costs, and eliminates carbon dioxide emissions, providing a cost-effective and efficient heating solution for gases used in direct iron ore reduction and other applications.

Implementation Method 1

tube sections which are configured to be electrically connected, at a first end thereof, to phases of a transformed multiphase outlet voltage of said transformer, and which are electrically interconnected at a second end thereof in order to resistance heat said tube sections by passing an electric current through said tube sections

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP4692378A1Apparatus and method for electrically heating a gas and process for the direct reduction of iron ore

Publication Date: 2026.02.11 SELAS LINDE

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AI summary

An apparatus for electrically heating a gas (3) is proposed, said apparatus comprising heating tubes (220) provided in one or more heating arrangements (200, 300) and a transformer (420), wherein said heating tubes (220) comprise tube sections (221, 222, 223) which are configured to be electrically connected, at a first end thereof, to phases (L1, L2, L3) of a transformed multiphase outlet voltage of said transformer (420), and which are electrically interconnected, at a second end thereof, in order to resistance heat said tube sections (221, 222, 223), wherein said transformer (420) is configured to be connected to an electrical supply voltage provided as an inlet voltage to the transformer (420) and is configured to transform the inlet voltage to said multiphase outlet voltage, and wherein said apparatus is configured to supply said multiphase outlet voltage to the, or each of the, heating arrangements (200, 300) and the heating tubes (220) therein without further transformation. A corresponding method in which the apparatus is used, and a process for the direct reduction of iron ore is also proposed.