*2.2.2.8 Hydrogenation of C3 cut*

The top product of the depropanizer is mixed with recycles and fed to the hydrogenation section in order to convert methyl acetylene and propadiene. The feed is mixed with hydrogen and enters the first reactor. **Figure 10** shows the reactor in which hydrogen is compounded with the feed stream as well as C3 stripper. For hydrogenation, three reactors have been installed, two in service and one in standby mode. The output of the reactors enters T-403 (**Figure 11**) to separate the light components where the bottom product of this tower enters the C3 splitter (T-404), with 200 trays, at tray 55 or 68. The tower condenser (E-410) is cooled by cooling water. The produced propane is directed to E-412 for cooling and then to battery limits. A by-product (propane) is taken from tray 4 or 8 and

**Figure 10.** *C3 reactor and stripper to add hydrogen to the feed stream.*

**Figure 12.** *Different technologies of interest for the production of light olefins from methane and light alkanes [27].*

*A Look at the Industrial Production of Olefins Based on Naphtha Feed: A Process Study… DOI: http://dx.doi.org/10.5772/intechopen.100017*

recycled to the furnaces. The tower re-boiler (E-412) works with quench water. The bottom product which contains C4 and heavier compounds is recycled to the depropanizer (T-401). **Figure 12** illustrates C3 splitter configuration in olefin plant.

### **3. New trends in olefin production**

In this section, some of the most promising alternatives are compared with the conventional steam cracking process. **Figure 12** depicts novel technologies for the production of light olefins from methane and light alkanes. These technologies emerge especially from the abundance of cheap propane, ethane, and methane from shale gas and stranded gas. Continuing search for alternative and preferably also more sustainable processes and feeds will eventually be required in order to fulfill the future demand for commodity chemicals. The following technologies are of interest: the catalytic dehydrogenation of light alkanes, the oxidative coupling of methane (OCM), and syngas-based routes such as the Fischer-Tropsch synthesis (FTS) and methanol synthesis followed by methanol to olefins (MTO) [27–31].

Biomass is also considered a promising alternative feed that can be converted into the valuable olefins, among other chemicals and fuels (**Figure 13**). Through processes such as fermentation, gasification, cracking and deoxygenation, biomass derivatives can be effectively converted into C2–C4 olefins. In this respect, biomass and waste streams are believed to be important for the production of chemicals in the future. In recent years, bio-ethanol has been extensively studied as an alternative feed for C2H4 production (**Figure 14**). Other bio-derived compounds such as

**Figure 13.** *Biomass to olefins primary routes [32].*

**Figure 14.** *Schematic chart of C2H4 production methods [32].*

methanol and dimethyl-ether, can be also be used as a feed for C2H4, via methanol to olefins (MTO) and dimethyl-ether to olefins (DMTO) processes. Bio-ethylene can also be produced via bio-synthesis from various enzymes or micro-organisms [32–36] (**Figure 14**). Similarly for production of C3H6 and C4H6 bio materials have been proven promising using different processes rather than steam cracking.
