Exergy destruction in ammonia scrubbers

Filippos K. Zisopoulos, Atze Jan van der Goot, Remko M. Boom

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

A theoretical ammonia scrubbing process by sulfuric acid solution is assessed with the concept of exergy. The exergy destruction of chemical neutralization is mainly (75–94%) due to changes in the chemical exergy of streams and thermal effects from the reaction while mixing effects have a limited contribution (6–25%). The minimum exergy consumption to remove one mole of ammonia chemically from an airstream could be two to eight times larger than the latent heat of evaporation of one mole of water depending on whether a concentrated (98% w/w) or a dilute (1% w/w) sulfuric acid solution is used. The exergy destruction per mole of ammonia scrubbed could be reduced by up to 75% when both the sulfuric acid solution and the ammonia at the inlet airstream are highly concentrated. The use of sulfuric acid concentration in the range of 10–50% w/w could lead to a very low exergy efficiency (<50%). The exergy efficiency could be improved up to ∼87% by introducing an ammonia pre-concentration step right before the scrubbing process. The extension of system boundaries shows that the cumulative exergy loss rate for neutralizing a heavily loaded ammonia airstream with a flowrate of 1 kg s−1 ranges between 0.3–1.5 MW depending on the way sulfuric acid is produced. Consequently, an exergy-efficient scrubber design should balance between the minimization of the consumption of exergy-intensive resources, the minimization of the exergy destruction occurring in the separation process, and the maximization of output stream utilization.
LanguageEnglish
Pages153-165
JournalResources, Conservation and Recycling
Volume136
DOIs
Publication statusPublished - Sep 2018

Fingerprint

exergy
ammonia
sulfuric acid
Exergy
Ammonia
neutralization
temperature effect
evaporation

Keywords

  • Chemical separation
  • Food industry
  • Irreversibility
  • Resource use efficiency

Cite this

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title = "Exergy destruction in ammonia scrubbers",
abstract = "A theoretical ammonia scrubbing process by sulfuric acid solution is assessed with the concept of exergy. The exergy destruction of chemical neutralization is mainly (75–94{\%}) due to changes in the chemical exergy of streams and thermal effects from the reaction while mixing effects have a limited contribution (6–25{\%}). The minimum exergy consumption to remove one mole of ammonia chemically from an airstream could be two to eight times larger than the latent heat of evaporation of one mole of water depending on whether a concentrated (98{\%} w/w) or a dilute (1{\%} w/w) sulfuric acid solution is used. The exergy destruction per mole of ammonia scrubbed could be reduced by up to 75{\%} when both the sulfuric acid solution and the ammonia at the inlet airstream are highly concentrated. The use of sulfuric acid concentration in the range of 10–50{\%} w/w could lead to a very low exergy efficiency (<50{\%}). The exergy efficiency could be improved up to ∼87{\%} by introducing an ammonia pre-concentration step right before the scrubbing process. The extension of system boundaries shows that the cumulative exergy loss rate for neutralizing a heavily loaded ammonia airstream with a flowrate of 1 kg s−1 ranges between 0.3–1.5 MW depending on the way sulfuric acid is produced. Consequently, an exergy-efficient scrubber design should balance between the minimization of the consumption of exergy-intensive resources, the minimization of the exergy destruction occurring in the separation process, and the maximization of output stream utilization.",
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Exergy destruction in ammonia scrubbers. / Zisopoulos, Filippos K.; van der Goot, Atze Jan; Boom, Remko M.

In: Resources, Conservation and Recycling, Vol. 136, 09.2018, p. 153-165.

Research output: Contribution to journalArticleAcademicpeer-review

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AU - Zisopoulos, Filippos K.

AU - van der Goot, Atze Jan

AU - Boom, Remko M.

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AB - A theoretical ammonia scrubbing process by sulfuric acid solution is assessed with the concept of exergy. The exergy destruction of chemical neutralization is mainly (75–94%) due to changes in the chemical exergy of streams and thermal effects from the reaction while mixing effects have a limited contribution (6–25%). The minimum exergy consumption to remove one mole of ammonia chemically from an airstream could be two to eight times larger than the latent heat of evaporation of one mole of water depending on whether a concentrated (98% w/w) or a dilute (1% w/w) sulfuric acid solution is used. The exergy destruction per mole of ammonia scrubbed could be reduced by up to 75% when both the sulfuric acid solution and the ammonia at the inlet airstream are highly concentrated. The use of sulfuric acid concentration in the range of 10–50% w/w could lead to a very low exergy efficiency (<50%). The exergy efficiency could be improved up to ∼87% by introducing an ammonia pre-concentration step right before the scrubbing process. The extension of system boundaries shows that the cumulative exergy loss rate for neutralizing a heavily loaded ammonia airstream with a flowrate of 1 kg s−1 ranges between 0.3–1.5 MW depending on the way sulfuric acid is produced. Consequently, an exergy-efficient scrubber design should balance between the minimization of the consumption of exergy-intensive resources, the minimization of the exergy destruction occurring in the separation process, and the maximization of output stream utilization.

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