API PUBL 4679:1999

This document describes a software simulation package called Amine Unit Air Emissions Model (AMINECalc Version 1.0). This package is designed to estimate hydrocarbon emissions from amine based sour gas and natural gas liquid (NGL) sweetening units. The output generated by the software package is suitable for regulatory reporting, which will be performed by the unit operators according to the schedule derived from the Clean Air Act Amendments (CAAA) of 1990. The development of AMINECalc was funded by the American Petroleum Institute (API). The major objective of this project is to develop a comprehensive software simulator which, with its verifiable predictions, will gain acceptance of the U.S. Environmental Protection Agency (EPA). At the same time, the simulator, with its easy-to-use interface, will be accepted by amine unit operators. The calculation algorithm of this package is based on commercial software developed originally by DB Robinson Research Ltd. Equipped with a rigorous non-equilibrium stage model and the Peng-Robinson equation of state, the commercial software was designed for providing accurate and reliable solutions to sour gas and liquefied petroleum gas processes. Traditionally, the emphasis of the commercial software was on acid gas (H2S and CO2) removal, and its predictions have been constantly checked against real plant data. In this study, the commercial software has been re-engineered and enhanced to accommodate three types of calculations (mass balance calculation, gas process simulation, and NGL process simulation) required by the AMINECalc project. Emphasis has been on hazardous air pollutants (HAPs) including benzene, toluene, ethylbenzene and xylenes (BTEX), and volatile organic compounds (VOCs) from amine unit emissions.