112
Main fractionator top temperature Ammonium chloride
FCC riser
110
108
sublimation temperature
106
PPO from tanker
104
VGO
102
PPO
100
Before PPO trial
During PPO trial
PPO storage vessel
Lift steam
Flow meter
The catalytic cracking experiments were carried out at 540ºC and a catalyst-to-oil ratio of seven. In laboratory experiments, it was observed that co-processing of PPO increases LPG, dry gas, and coke, and reduces cracked naphtha, LCO, and resid yield. Product yields obtained from laboratory experiments with the 0.5% and 5% PPO processing are given in Figure 2 . Operational scheme for PPO processing in FCC unit Since PPO is not a typical feedstock for the FCC unit in a refinery, a dedicated PPO skid was installed near the FCC unit to facilitate its injection into the riser. The skid includes a storage tank, an inlet hose for receiving PPO from a tanker, an outlet hose, a pump, and a flow meter. PPO, along with lift steam, was injected into the riser, with no heating provisions provided for the storage tank and feeding line. The process flow scheme of the PPO skid is illustrated in Figure 3 . Demonstration of PPO co-processing in the FCC unit A trial of co-processing PPO was carried out in the resid FCC unit at the Mumbai refinery, which has a feed capacity of 1.27 MMPTA. In this trial, 0.5% of PPO was processed with FCC catalyst feed. No gum formation or atomisation issues were observed when injecting PPO. Based on the chloride and nitrogen content of PPO, the ammonium chloride sublimation temperature was estimated (around 104ºC) and, accordingly, the main fractionator top temperature was kept higher than the sublimation temperature Figure 4 Main fractionator top temperature and respective ammonium sublimation temperature before and during the PPO trial
PPO pump
Figure 3 Process flow scheme of PPO skid
process parameters to mitigate corrosion issues in the main fractionator and gas concentration section, and injection into the FCC riser. Various qualities of PPO are evaluated to identify those with minimal chlorine, sulphur, nitrogen, oxygenates, and diene content, ensuring reduced negative effects on FCC product yields. This selection process helps in mitigating operational challenges, such as corrosion and gum formation. Catalytic cracking experiments using the optimised PPO were conducted at Hindustan Petroleum Green R&D Centre (HPGRDC) to assess its performance and feasibility in FCC applications. Catalytic cracking experiments The catalytic cracking experiments for the co-processing of plastic pyrolysis with FCC feed were carried out in a fixed-fluid-bed micro- reactor unit. Product gas was analysed in Micro- GC, and liquid product was analysed in low- temperature simulated distillation equipment. The liquid product cuts considered were cracked naphtha (C 5 at 221°C), light cycle oil (LCO) (221°C-343°C), and resid (343°C and higher). Conversion was obtained by the sum of the yields of dry gas, LPG, cracked naphtha (CRN), and coke. Mumbai refinery resid FCC unit catalyst feed, along with 0.5% and 5% of PPO, was used as feedstock. The properties of the catalyst feed and PPO are given in Table 1 . Mumbai refinery resid FCC equilibrium catalyst (E-cat) was used for catalytic cracking experiments, and the properties of E-cat are given in Table 2 .
Refining India
13
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