Steady-state multiplicity analysis of two-stage-riser catalytic pyrolysis processes

Stability Analysis of Gas–Solid Distribution through Nonidentical Parallel Paths

“…TA TB (6) For gas−solid flow through two nonidentical parallel paths, there are four unknowns: two values of γ i , the total solid circulation rate (C T ), and the index of nonidentity (δ) for four unknowns. On the other hand, there are two constraints: one constraint equation (eq 3) for fraction γ i and one independent pressure drop equality equation (eq 6).…”

“…Typically, parallel reactors can achieve following advantages: (i) low cost from sharing common units, such as a prereaction or/and postreaction section; (ii) an opportunity to establish different reaction conditions in each path to obtain flexible product distribution; and (iii) restricted pressure drop (energy consumption) . One example is fluid catalytic cracking (FCC) in dual risers with one common regenerator. − The common regenerator can reduce the cost, and the product distribution, from high liquid yield to high selectivity of LPG, can be adjusted via changing the independent operational conditions (reaction temperature, catalyst-to-oil ratio, and residence time) through each riser, respectively. Since reactants and operational conditions through each path are always different, the nonidentity of the parallel system is unavoidable.…”