Electric process gas heater for preheating of hydrogen and natural gas mixtures in DRI or BF plants

The Electric Process Gas Heater (E-PGH) is used to replace combustion heating using fossil fuels to preheat gases for DRI or BF operations. The E-PGH technology is being developed to both heat hydrogen for novel upcoming applications, pure hydrogen based DRI-process but also for existing natural gas based DRI technology. In the latter case, E-PGH can be deployed to replace combustion heating either partially or entirely.
This technology is being jointly developed by Kanthal and Danieli.

TECHNICAL DESCRIPTION
The core of this technology is a direct electric gas heater, for heating process gases including pure hydrogen or hydrogen/natural gas mixtures at temperatures up to 1100°C. Initially, this technology was developed by Kanthal in the context of the Hybrit DRI project and has been validated for heating hydrogen both at the Hybrit’s pilot plant and at Kanthal’s Research and Development facility.
The heating technology is based on Kanthal®APM resistance heating alloy, where the gas to be heated flows inside resistance heated tubes that are located inside a pressure vessel. Kanthal®APM is an advanced powder-metallurgical, dispersion-strengthened, ferritic iron-chromium-aluminium alloy (FeCrAl alloy) for use at temperatures up to 1425°C . Kanthal® APM exhibits excellent resistance to high-temperature corrosion in most relevant gas atmospheres compared to other common high-temperature alloys with very low gross mass gain due to oxidation at 1 200°C in the air (See Figure 1 / Supplementary information).

In this development, Kanthal is responsible for the development and supply of the electric heating modules that will be inserted into insulated pressure vessels designed by Danieli, which has strong expertise in refractory insulation, pressure vessels design, power electronics and control cabinets. Each heating module has a power capacity of 1 – 3 MW. They are built from the assembly of cold pilgered APM tubes with spaces and accessories such as electrical feedthroughs. After integration into pressure vessels, the E-PGH can be installed in an ENERGIRON direct reduction plant for preheating of process gases (See supplementary information).

An E-PGH generates heat by passing electricity through an element of resistive wire instead of generating heat by burning natural gas in a fired process gas heater. As the current flows through the wire, it generates heat that is transferred to the process gas being heated. By avoiding combustion, the E-PGH operates at a higher efficiency, up to 95% in comparison with normal ranges of 89-91% for fuel-based process gas heaters. For instance, thermal efficiencies of 95% were achieved in the heating of hydrogen to 950°C, within the pilot trial campaigns carried out at the Hybrit’s pilot plant. The direct E-PGH technology developed provides a high-energy density making a compact solution, thereby lowering the overall footprint. The heating technology is modular enabling scale-up to large scale (100’s of MW).
Key advantages of the electric heater are summarised below:
 Compact design
 Pre-assembled (Modular design)
 Almost zero footprint in layout
 Lower temperature of the heaters (compared to in-direct heating technology)
 Lower thermal Losses, stable performance and low pressure drop
 Possibility to retrofit natural gas fired heating to electrical heating for existing ENERGIRON DRI plants.

For this type of application, indirect electrical heating (i.e. the electric heating elements are not in direct contact with the process gases) was also considered however it is thought that the thermal efficiency would be lower in this case and the maximum gas outlet temperature will be lower due to heat transfer and higher differential in temperatures, between the heater and the process gas. Indirect heating technology is also expected to lead to a much larger footprint which could overall increase CAPEX.


DEGREE OF MATURITY
The E-PGH technology being developed for DRI and blast furnace applications has been validated on smaller scale (1 MW) for heating hydrogen (within the development with Hybrit). Accelerated tests have also been made on component level and for single heating modules in air on R&D-scale. Based on validation and tests done and the technology roadmap ahead, the TRL for the technology is estimated to be 6-7.

One important step in the development and scale-up of this technology is the deployment of a pilot electric heater with 140 kW power capacity in the framework of the EU-funded project Hydra , in which a 30-m DRI pilot plant has been commissioned in 2025 to test and achieve consistent productivity and quality with various methane/hydrogen mixtures. Commissioning and start-up of the delivered electric heater is planned for the 1st quarter of 2026.
Besides, another important milestone in the industrialisation of this technology is the supply of a 1.3 MW demonstration heater to a DRI-production facility at Emirates Steel (ES) in Abu Dhabi. The E-PGH will be supplied and installed by Kanthal and Danieli jointly in May 2026.

Basic information about the technique

Participant Companies