Vapor-liquid activity coefficients for methanol and ethanol from heat of solution data: application to steam-methane reforming.
This paper presents equations and curves to calculate vapor-liquid phase equilibria for methanol and ethanol in dilute aqueous solution as a function of temperature, using activity coefficients at infinite dilution. These thermodynamic functions were originally derived to assess the distribution of by-product contaminants in the process condensate and the steam-system deaerator of a hydrogen plant [Paper ENV-00-171 presented at the NPRA 2000 Environmental Conference, San Antonio, TX, 10-12 September 2000], but have general applicability to other systems as well. The functions and calculation method described here are a necessary piece of an overall prediction technique to estimate atmospheric emissions from the deaerator-vent when the process condensate is recycled as boiler feed water (BFW) make-up. Having such an estimation technique is of particular significance at this time because deaerator-vent emissions are already coming under regulatory scrutiny in California [Emissions from Hydrogen Plant Process Vents, Adopted 21 January 2000] followed closely elsewhere in the US, and eventually worldwide. The overall technique will enable a permit applicant to estimate environmental emissions to comply with upcoming regulations, and a regulatory agency to evaluate those estimates. It may also be useful to process engineers as a tool to estimate contaminant concentrations and flow rates in internal process streams such as the steam-generating system. Metallurgists and corrosion engineers might be able to use the results for materials selection.
Kunz
R G
RG
Air Products and Chemicals, Inc., Allentown, PA 18195-1501, USA. kunzrg@aol.com
Baade
W F
WF
D000393:Air Pollutants / Q000737:chemistry; D004738:Engineering; D000431:Ethanol / Q000737:chemistry*; D000432:Methanol / Q000737:chemistry*; D008962:Models, Theoretical; D011210:Power Plants; D012997:Solvents / Q000737:chemistry*; D013696:Temperature; D014835:Volatilization
D000393:Air Pollutants; D012997:Solvents; D000431:Ethanol; D000432:Methanol