Combustive Properties of Hydrogen

Table 4.12 shows a comparison of safety-relevant thermo-physical and combustion properties of hydrogen with those of methane, propane and gasoline [26]. The flammability limits are affected by temperature, as shown in Figures 4.9 and 4.10, so that a preheated mixture has considerably wider limits for coherent flames [27]. An increase in pressures up to lOkPa has only a small effect. Water vapor has a strongly inhibiting influence on the oxyhydrogen reaction. 

Several of the combustion-related properties of hydrogen in air, such as its wide flammability limits (4-75 vol%), wide detonation range (20-65 vol%), very low spark ignition energy (0.02 mJ), high heat of combustion (121 kJ/g) and high flame temperature (2050°C) combine to emphasise the high fire-related hazards of the... 

The product of sorbing hydrogen on to hot zirconium powder bums with incandescence when heated in air [1,2], Ignition and combustion properties of pyrophoric zirconium and zirconium hydride powder (< 10 p), and safety measures are discussed [3], Ignition energies for zirconium hydrides, ZrUx x = 0 — 2, in air have been studied in Japan [4],... 

The Germans used hydrogen peroxide of 80-85% concentration, alone or in mixtures with combustibles, as a fuel for the big V2 rockets during World War II. The utilization of hydrogen peroxide for rocket propulsion and the explosive properties of hydrogen peroxide and its mixtures will be discussed in later sections (pp. 299, 307). 

The properties of hydrogen are detailed in Section 1. The properties that contribute to its use as a combustible fuel are its ... 

Table 4.12 Combustion and explosion properties of hydrogen, methane, propane and gasoline...

The specific thermal properties of hydrogen as a fuel and the aforementioned combustion characteristics demand that any external conditions that affect HAM/ HOM explosions be taken into account. 

Properties. A high volatile western Kentucky bituminous coal, the tar yield of which by Fischer assay was ca 16%, gave a tar yield of ca 26% at a pyrolysis temperature of 537°C (146—148). Tar yield peaked at ca 35% at 577°C and dropped off to 22% at 617°C. The char heating value is essentially equal to that of the starting coal, and the tar has a lower hydrogen content than other pyrolysis tars. The product char is not suitable for direct combustion because of its 2.6% sulfur content. 

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