This paper quantifies the first-principles production and heat-recovery potential of redistributing process air in a medium-pressure AK-72M weak-nitric-acid unit. The assessed concept replaces part of the T-5–K-47 heating/bleaching branch with an external air stream and redirects an equal amount of already-compressed M-10A air to the R-12/1,2 contact reactors. A stoichiometric oxygen balance, an effective overall yield factor and a reaction-heat model were evaluated for 2,500–10,000 Nm³ h⁻¹. At the documented effective oxygen basis of 19 vol.% and ηtot = 0.955–0.965, the 10,000 Nm³ h⁻¹ scenario gives 2.552–2.578 t h⁻¹ of additional 100% HNO3 equivalent, 4.477–4.523 t h⁻¹ of 57 wt.% solution and 20.21–20.42 kt y⁻¹ of HNO3 equivalent at 7,920 h y⁻¹. Using 20.95 vol.% as a dry-air boundary increases the calculated production range to 2.814–2.843 t h⁻¹, demonstrating that oxygen basis and humidity must be measured rather than assumed. Gross additional steam potential is 2.55–2.87 t h⁻¹ for the 19% basis and 80–90% heat recovery, but this is not a net utility benefit because the reduced T-5 duty may increase T-202 steam demand. The study defines the measurements and equipment constraints required to convert the model-based potential into a validated industrial result.
Coupled Mass–Energy Assessment of Process-Air Redistribution in A Medium-Pressure Nitric Acid Plant
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Abstract
References
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