Decarbonisation Technology - August 2023 Issue

Risk

Potential mitigations

Burner capability at high H 2 content

Review original data sheet and testing, work with vendors to select and adjust burners to improve flame stabilisation Review and upgrade flame detectors that can handle hydrogen firing Shorter flames with higher radiant and less convective heat transfer. Review firebox design and heat flux More thermal but lower prompt NOx emissions. Review with burner manufacturers Review gas supply line pressure, gas control valve sizing, and maximum burner pressure allowance. Review combustion air controls Address with stated codes and standards for metallurgy choices

Flame detection

Flame height

Increased NOx

Control systems

Materials

Table 1 Hydrogen firing risks and potential mitigations

a mechanism to help meet decarbonisation targets, especially as the operating entity was concerned about firing >90% hydrogen streams. Within the review, Becht assessed the fuel gas supply system, operational challenges, potential modifications, and anticipated shifts in heater performances. Table 1 identifies some of the risks and mitigations for hydrogen firing. In this example, sufficient supporting analysis was provided to help the client determine that pre- combustion is technically viable and should be part of their decarbonisation investment plans. Another case study considered the use of hydrogen as a fuel source within gas turbines. From a conservation of energy standpoint, the principle of taking green power (such as wind, solar, hydro, or geothermal), converting it to hydrogen, and then combusting the hydrogen to

make power is particularly inefficient compared to the direct use of green power within the grid. However, a large base of installed gas turbine generation could be retrofitted to use hydrogen. Additionally, hydrogen can serve as a replacement for natural gas or coal for load management of power supply vs power demand and as an energy storage mechanism. As such, hydrogen can reduce our dependency on fossil energy sources and be complementary to green power. For instance, during high solar or wind power generation and meager demand periods, the excess power could be used to generate hydrogen via electrolysis and then stored for combustion in a ‘peaking’ gas turbine during low solar or wind power generation periods. This approach helps more fully leverage the

Becht was selected by a rening client to evaluate and qualify combustion hardware capability of firing a blend of up to 40%hydrogen refinery o - gas in a gas turbine located at the adjacent cogeneration plant.

Becht s ubject m atter e xperts collaborated with client, hardware supplier , and cogeneration plant personnel to examine turbine retrofit feasibility, impacts , and operability.

This retrofit will allow the client to eliminate flaring during turnarounds and perform additional process optimisations and reduce their carbon footprint

Cogeneration plant will realise improved gas turbine performance (output and heat rate), carbon footprint reduction (combusting high H fuel gas blend) , and extended operating time between combustor and hot gas path maintenance outages

Figure 2 Hydrogen firing gas turbine case study