Biomass Fast Pyrolysis Using a Novel Microparticle Microreactor Approach: Effect of Particles Size, Biomass Type, and Temperature

Abstract

Biomass fast pyrolysis is emerging as a front-running approach for the generation of renewable chemical and fuel resources. The pyrolysis temperature, solid-and gas-phase residence times, and biomass particle size and type have a substantial impact on char, oil, and gas yields. A laboratory-scale fast pyrolysis technique was demonstrated using manufactured biomass microspheres. A unique single-particle (∼10 μg) microreactor technology coupled to a millisecond response flame ionization detector was used to investigate the effects of relevant particle and process parameters and to capture the dynamics of real-time microscale single-particle pyrolysis for the first time. The manufactured biomass microspheres were produced by spray-drying finely milled microcrystalline cellulose, switchgrass (Panicum virgatum), and tall fescue straw (Festuca arundinacea) flour.

Biomass Fast Pyrolysis Using a Novel Microsphere Microreactor Approach: Model-Based Interpretations

“…Pyrolysis vapors were swept away from the particle and transported to a fast flame ionization detector (fast-FID), and the rate of production was gathered in real time. A more detailed description of the MSMR is provided elsewhere …”

“…The two main forces on the particle are the hydrodynamic drag force and the gravitational force. Since the entrance lock of the reactor is horizontal, the gravitational force is zero initially and until it reaches the vertical section of the tube . The sum of the forces on the particle is given as follows: subject to initial conditions where = drag force ((kg·m)/s 2 ), = gravity force ((kg·m)/s 2 ), ⟨ V g ⟩ = average gas velocity, V ̂ p = average particle velocity, C d = drag coefficient, A p = projected area of the particle (m 2 ), A t = area of tube (m 2 ), m p = mass of particle (kg), ρ = density of biomass (kg/m 3 ), ρ f = density of carrier gas (kg/m 3 ), and μ­( T ) = fluid (gas) viscosity (kg/(s·m)).…”

“…A series of lasers were used to track the velocity of the individual particle . The average velocity was estimated between successive laser pairs.…”

“…Recently, however, the pulse-heated analysis of solid reactions (PHASR) , approach was introduced in an effort to minimize transients and capture short-time-duration (1 ms) events that are effectively isothermal. The pros and cons of MSMR and PHASR reactors are described elsewhere …”

Current status of co-pyrolysis of oil shale and biomass

“…These parameters also af- fect heat transfer, the temperature gradients between particles and between the particles' surface and core, and the residence time, among other factors. The effects of pyrolysis temperature [98][99][100][101][102][103], particle size [104][105][106] and heating rate [107][108][109][110] on the fast, intermediate and slow pyrolysis of BM have been widely studied in different types of reactors and for different BM species.…”