Preheating of air

P is the partial pressure of the gases at the reformer exit. Tr is usually less than 10-15°C throughout the catalyst lifetime. The thermal efficiency of a tubular steam reformer with waste heat recovery system approaches 95% of which 50-60% is transferred to the process. " The remaining heat is recovered by production of steam, preheating of air, feedstock, etc. 

Figure 10-14. Plasma (electric) energy cost of syngas production during plasma conversion of kerosene as function of specific energy input in the system (1) partial oxidation (2) steam-oxygen conversion with preheating of air (3) steam-oxygen conversion with excess water, (4) steam-conversion in low-temperature regime (5) steam conversion in high temperature regime.

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