Straw Black Liquor Steam Reforming in a Fluidized Bed Reactor. Effect of Temperature and Bed Substitution at Pilot Scale

Abstract

Gasification via the steam reforming of straw black liquor (BL) was performed in a pilot-plant fluidized bed reactor. The effects of bed material replacement (from an initial bed of calcium carbonate to a bed composed of BL char) and bed temperature (575−640 °C) on the dry gas composition, the dry gas lower heating value (LHV), gas yield, fraction of carbon to gas, and cold gas efficiency have been investigated. Although bed defluidization problems were experienced under the operating conditions tested, a medium heating value gas (with a dry gas LHV of ∼8200 kJ/m3 STP) (where STP indicates standard temperature and pressure) was obtained, composed mainly of H2 (65 vol %) and CO2 (30 vol %). Because of the high ratio of steam to biomass used, little influence of the reaction temperature on the gas composition was observed at >550 °C. At 600 °C, which is a temperature lower than that usually utilized in biomass gasification, ∼2.2 m3 STP/kg daf of gas production, 75% carbon conversion to gas, and a cold gas efficiency of 90% were achieved, showing that the low-temperature steam reforming of BL could be a suitable process if bed defluidization can be overcome.

Characteristics of gas and char generation study from reed black liquor particles (RBLP) pyrolysis in fluidized bed

“…At 530°C, the concentrations of CO and CO 2 were 34.97% and 32.14% by volume respectively. These results were approximate to the pyrolysis of black liquor solids in a fixed-bed reactor [23,45]. In addition, pyrolysis temperature had a great impact on the gaseous product concentration.…”

“…Large hydrocarbon could decompose into non-condensable gases (CO 2 , CO, H 2 and CH 4 ). At lower temperature, the carboxyl bonds were the weakest and were ruptured easily, and the oxygen in the carboxyl groups could be easily released as CO 2 [23]. Moreover, it was difficult to reduce the produced CO 2 to CO over char at low temperature [46], which can explain that CO 2 concentration was more at low temperatures than higher temperatures.…”

“…Therefore, a lot of researches have been done to study the pyrolysis of wood BL [10][11][12][13][14][15][16][17]. Nevertheless only a few studies have been found on straw BL [18][19][20][21][22][23]. What is more, not much information is available on the BL solids pyrolysis.…”

Synthesis of Transportation Fuels from Biomass: Chemistry, Catalysts, and Engineering

“…Black liquor, the major waste biomass-containing stream from chemical pulp and paper production, also can be converted into syn-gas by steam reforming. 237 Steam reforming of fossil fuels is a well-established technology, 51 and steam reforming of bio-oils is an extension of this technology. Steam reforming reactions occur at high temperature (600-800°C) and high space velocities usually with a Ni-based catalyst.…”

Reed Black Liquor Combustion in Fluidized Bed for Direct Causticization with Limestone as Bed Material

“…Nowadays, the wood BL can be burned in a Tomlinson recovery boiler for energy generation and chemical recovery. However, it is very difficult to apply the Tomlinson recovery technology to the straw BL because it has higher contents of silica and chlorine, higher viscosity, and a lower heat value compared with wood BL. − Therefore, some alternative recovery technologies that are safer, easier, and more efficient have been developed over the past 20 years. − Among them, the fluidized bed alkali recovery technology is a well-established and widely used method for BL treatment. In this system, the BL is burned in a fluidized bed to recover the energy and chemicals.…”