Today, one of the challenging issues all over the world is the global warming which can be attributed to the emission of greenhouse gases into the environment as well as burning of gases in flare gas stream of industrial units. The latter can not only cause environmental problems but also is accompanied by wasting a great deal of energy. To deal with the aforementioned issue, the flare gas stream can be recycled after separating some species. In this investigation, the objective is to separate CO 2 and H 2 from the flare gas in addition to methanol production. In this regard, a separation with sorbent/solvent method is used which is divided into two stages: (1) H 2 separation by sorbent, (2) CO 2 separation by monoethanolamine solvent. From the obtained results in this study, in the first stage, H 2 and CO 2 can be purified up to 75% and 99.83%, respectively. Beside, methanol synthesis is compared in three different cases: (1) industrial unit, (2) CO 2 is fed into the reactor instead of CO, and (3) CO 2 and H 2 are fed to the reactor with stoichiometric coefficients. The obtained methanol production of the case (1) is approximately close to that of the case (3) and it is reduced 4% in case (3).

Generally, the common adsorption processes of air separation are divided into two categories: The first category is consists of processes which make use of zeolites as nitrogen adsorbent under the equilibrium conditions and oxygen is a process product. The second one contains processes which utilize Carbon Molecular Sieves (CMSs) as oxygen adsorbent. Zeolite 13X is the most commonly adsorbent used in the air separation for oxygen production. In this work, nitrogen adsorption behavior on zeolite 13X bed is simulated. Desorption and adsorption dynamics of zeolite 13X was investigated in order to study the behavior of this zeolite. The simulation results showed that the high Roll-up Phenomena occurs for oxygen than nitrogen. There is a large mass transfer zone (MTZ) for zeolite 13X. Therefore, the adsorption rate of zeolite 13X is high. The main drop of nitrogen concentration in the outlet of zeolite 13X occurs at the time of about 125 seconds. Nitrogen concentration in the outlet of zeolite 13X approaches zero after about 180 seconds. Keywords:

A two-bed pressure swing adsorption system on a commercial type of zeolite 13X adsorbent has been studied numerically over a wide range of operating conditions to helium separation from gaseous mixture. The model includes energy, mass and momentum balances. The coupled partial differential equations are solved using fully implicit forth order Rung-Kutta scheme in the simulation. The effects of adsorption step pressure, adsorption step time and feed flow rate on the helium purity and recovery were investigated. Results shown that as the adsorption step pressure increases the helium purity will be increased. In addition, the helium recovery increases, and the helium purity decreases when the feed flow rate increases. Finally, the simulation results indicated a very good agreement with some current literature experimental work.

A two-bed pressure swing adsorption system on a commercial type of zeolite 13X adsorbent has been studied numerically over a wide range of operating conditions to helium separation from gaseous mixture. The model includes energy, mass and momentum balances. The coupled partial differential equations are solved using fully implicit forth order Rung-Kutta scheme in the simulation. The effects of adsorption step pressure, adsorption step time and feed flow rate on the helium purity and recovery were investigated. Results shown that as the adsorption step pressure increases the helium purity will be increased. In addition, the helium recovery increases, and the helium purity decreases when the feed flow rate increases. Finally, the simulation results indicated a very good agreement with some current literature experimentally work.