Biomass catalytic pyrolysis: process design and economic analysis

The estimation of catalytic pyrolysis oil (CPO) production cost in a biomass catalytic pyrolysis (BCP) process is the objective of this study. Experiments carried out with a woody biomass (Beechwood) and a commercially available ZSM-5 catalyst in a circulating fluid bed (CFB) reactor are the basis for the design of a commercial unit. In the CFB unit, the catalytic pyrolysis step takes place at 482 degrees C and at a catalyst to biomass ratio of 15-20. Following this step, the vapor temperature exiting the reactor is cooled from 482 to 340 degrees C by recovering energy for steam production. The vapors are condensed in two quench towers with recirculated oil and water. Following water separation, the CPO flows to storage. A commercial scale process was designed for a capacity of 180,000 metric tons (MT) per year (8wt% moisture, 0.54wt% ash) or 500 MT/day of moisture ash free (MAF) biomass (90% operating factor). The projected costs are valid only for an nth plant and they underestimate the cost for a first of its kind plant. Following procedures used for estimating investment and operating costs for a fluid catalytic cracking unit (FCCU), it is found that for BCP the estimated cost of producing CPO with 18wt% oxygen is 615US$/MT or 22US$/GJ. A sensitivity analysis showed that the price of CPO could vary from 615 to 841 US$/MT (22-31 US$/GJ). On a crude oil energy equivalent basis, the bio-oil cost lies in the range of 36-49 US$/GJ. (C) 2016 The Authors. WIREs Energy and Environment published by John Wiley & Sons, Ltd.