DUAL FLUIDIZED-BED REACTOR SYSTEM

The dual fluidized bed (DFB) system has two interconnected circulating fluidized bed reactors that transfer bed particles between oxidizing and reducing environments. The combustor/air reactor can be fluidized with air, air+oxygen or CO2+oxygen for oxidation of fuels or bed particles. The other reactor (gasifier/fuel reactor) is fluidized with steam and optionally oxygen or CO2, and has a water-cooled auger to feed solid fuel into the bottom of the reactor. Preheating of the fluidizing gases is achieved with two 65 kW high-temperature gas heaters, but the system can also operate autothermally if the process being researched is overall exothermic. The DFB is designed for 50-100 lb/hr feed, or about 220 kW thermal input depending on feedstock properties.

The system has been used for chemical looping combustion of natural gas, biomass and coal and for dual-bed gasification of biomass including in sorption-enhanced gasification mode to maximize production of hydrogen.

Specifications

Combustor/air reactor
  • Max. temperature: 2200°F (1200°C)
  • Fluidizing gas: air, air+O2, or CO2+O2
  • Fluidizing gas preheater:  65 kW, max 2000°F (1100°C)
  • Design:  Steel shells lined with two layers of castable refractory
  • Overall dimensions: Ø 24 in (0.61 m) x 7.0 m (23.0 ft) tall
  • Reactor inner dimensions: Ø 10 in (0.26 m) x 6.2 m (20.4 ft) tall
  • Cyclone inner dimensions: Ø 20 in (0.51 m) x 40 in (1.02 m) barrel x 40 in (1.02 m) cone
Gasifier/fuel reactor
  • Feedstock: coal, biomass, waste, natural gas, liquid fuels
  • Feed rate 50-100 lb/hr (23-45 kg/hr)
  • Max. thermal input: 750,000 Btu/hr (220 kW)
  • Max. temperature: 2000°F (1100°C)
  • Fluidizing gas: steam, steam+O2, or steam+CO2+O2
  • Fluidizing gas preheater:  65 kW, max 1830°F (1000°C)
  • Feed system:  Gravimetric metering coupled to rotary valve and water-cooled auger feeder
  • Design:  Steel shells lined with two layers of castable refractory
  • Overall dimensions: Ø 24 in (0.61 m) x 6.4 m (21.0 ft) tall
  • Reactor inner dimensions: Ø 10 in (0.26 m) x 5.6 m (18.4 ft) tall
  • Cyclone inner dimensions: Ø 20 in (0.51 m) x 40 in (1.02 m) barrel x 40 in (1.02 m) cone

Capabilities

  • Dual fluidized bed gasification
  • Sorption-enhanced gasification for high-hydrogen syngas
  • Sorption-enhanced gasification/oxy-fuel combustion for carbon-negative hydrogen production
  • Chemical looping combustion of natural gas with in-situ carbon capture
  • Chemical looping with oxygen uncoupling of solid fuels

Research

  • Measurement  of system performance (syngas, fuel conversion, temperatures, circulation rates)
  • Evaluation of bed materials for gasification, tar cracking, chemical looping (performance, attrition)
  • Comparative studies of feedstocks and feedstock blends
  • Acquisition of data for system scale-up
  • Simulation model validation