Simulation optimization and control of syngas production process in regasified liquefied natural gas based ammonia plant

Abstract

Ammonia production process depends on the synthesis of its nitrogen and hydrogen newlinecomponents in about 1:3 ratio, by a process called the quotHaber-Bosch processquot. The newlineFertilizers and Chemicals Travancore Limited (FACT), Udyogamandal, Kochi, has an newlineammonia plant with an installed capacity of 900 MTPD of ammonia production and newlinewas originally designed for naphtha feedstock for getting the required hydrogen. newlineAmong different feed choices for ammonia production, regasified liquefied natural gas newline(R-LNG) has shown to be a favourable option because of its lower carbon to hydrogen newlineratio (CHR) which results in the reduction of CO2 emission. Also, due to the lower newlinesulphur content in the R-LNG, the pre-desulphurization (PDS) section where primary newlinesulphur removal takes place can be eliminated from the operation. Thus, this scheme newlineresults in a reduction of thermal energy requirement for the feed treatment. To newline newlineincorporate these benefits the FACT has revamped their existing ammonia plant with R- newlineLNG as the feedstock. newline newlineThis research was carried out to simulate the syngas production unit using Aspen newlineHYSYS process simulator with the aim of investigating R-LNG as an alternative raw newlinematerial for getting required hydrogen for syngas production. This is then directed to newlineammonia synthesis loop for the ammonia production. The simulation is based on actual newlineparameters (mass flow rates, temperature and pressure readings) obtained from the newlineAmmonia plant of the FACT. The simulation results showed that the resulting syngas newlinecomposition indicated 0.2661, 0.7331, 0.0005 and 0.0003 mole fractions of N2, H2, CH4 newlineand H2O respectively. The feed changeover from naphtha to R-LNG results in the newlinereduction of steam/carbon ratio from 3.3 to 2.8 and also reduces CO2 emission. Besides, newlinethe Aspen HYSYS simulation provides an option to estimate the energy requirement for newlineeach unit operation. newline