The challenges of the HyInHeat project

HyInHeat is a project that aims to explore the possibilities and challenges of using hydrogen (H₂) as a fuel for industrial heating applications. The project faces numerous challenges in implementing this technology, ranging from technical issues to regulatory and commercial challenges. In this blog we discuss the technical, regulatory, and commercial challenges that HyInHeat is facing.

From natural gas to hydrogen

One of the main technical challenges faced by the HyInHeat project is the fuel switch from natural gas (NG) to hydrogen. The fuel supply system needs to be redesigned and equipped with H₂-compatible instrumentation due to the 3.33 times higher fuel volume flow at constant burner capacity and the lower heating value of H₂ compared to NG. In addition, the change in water vapor content in the off-gas due to the use of H₂ can affect the gas-solid or gas-liquid interaction between the furnace atmosphere and the product in direct heating applications, impacting the quantity and quality of metal oxide formation (scale and dross) and the refractory structure due to higher and accelerated corrosion rates/kinetics. Different concentrations in radiating gas species in the combustion gases (H₂O and CO₂) also change the emissivity of the flame and furnace atmosphere, affecting the heat transfer and temperature homogeneity. For combustion control, a challenge arises from the absence of CO, as typical control algorithms and measurement devices focus on combined CO/O₂-measurement in the off-gas.

Burner design and materials

Another significant technical challenge is related to burner design and material. H₂ has a high reactivity/flammability, which can lead to shorter flame lengths and higher temperatures, which can affect the material lifetime of burners. Therefore, burner construction might need to be modified to reduce the risk of flashbacks and implement H₂-compatible materials, such as fuel supply lines and sealing. One of the main safety functions in burner operation is flame detection/monitoring, and stable operation of UV-cells and ionization must be guaranteed to ensure safe combustion systems.

Commercial and regulatory challenges

Apart from the technical challenges, the HyInHeat project also faces commercial and regulatory challenges. The commercial availability of burners for pure H₂ is limited, and the current Technology Readiness Level (TRL) for large capacity burners for industrial furnaces is in the range of 3-6 depending on the furnace/process. The implementation of H₂ heating requires modifying existing burner infrastructure, ensuring safe and reliable operation, and meeting regulatory and certification requirements. Continuous Emission Measurement (CEM) for NO_x emissions is essential to obtain an operating permit from authorities. However, modern in-situ measurement technology is certified for fossil-fired processes, but the applicability has not been proved for H₂/O₂ combustion processes. The implementation of predictive emission monitoring (PEM) technology is also a challenge, as a suitable prediction model needs to be built for specific plants or types of plants.

Measurement technology

In addition, the implementation of H₂ heating requires accurate combustion control for energy efficiency and fuel savings. The measurement of wobbe index, which is critical for feed-forward combustion control, is not currently possible with state-of-the-art wobbe meters for industrial H₂ heating. The application of optical emission spectroscopy (OES) and in-situ gas analysis to achieve optimum combustion efficiency also needs further development. The huge amount of water in the gas treatment system for H₂/O₂ combustion processes causes problems with condensation in cold extractive gas analysis systems, and the development of in-situ emission measurement systems is needed to enable accurate measurement of emissions.

In conclusion, the implementation of H₂ heating in industrial processes requires significant technical, regulatory, and commercial challenges to be overcome. The development of suitable measurement technology, burner design and material, safety functions, and the availability of commercial H₂ burners are critical to the success of the HyInHeat project. The project aims to demonstrate the feasibility and benefits of H₂ heating, and its success can pave the way for widespread adoption of this technology in the industry.

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