Design And Operation Of The Pilot -scale Circulating Fluidized Bed Gasification System For The Production Of Hydrogen

Hydrogen is a clean and efficient energy carrier and is expected to play an important role in future energy share. The technology for hydrogen production at this stage mainly includes: electrolysis of water, conversion of mineral fuels, conversion of biomass, transformation of other hydrogen-containing materials, and recovery of by-product hydrogen released by chemical-processing industries. Biomass is a renewable and carbon-neutral resource, and also abundant and cheap in the world particularly in China, therefore using biomass to produce hydrogen is foreseen as a very promising way.The thesis summarizes all technical solutions for the production of hydrogen and afterwards illustrates the comparison of those technical solutions in terms of operation, cost, maturity of technology, and process control. The focus is on thermo-chemical conversion of biomass into hydrogen, specializing in concepts of different technical options, use of different catalysts, and technical advantages/disadvantages of those options. In addition, the factors which have the impact on hydrogen yields and concentrations are discussed. This part of work leads to a conclusion that the fast pyrolysis of biomass using fluidised bed reactor to produce intermediates (bio-oils) followed by the catalytic steam reforming process is recommended as a promising way in terms of technical, economic and environmental acceptance.The theoretical calculation of fluidized bed gasifier based on cotton stalk was completed, and based on it the design of a pilot plant which includes a circulating fluidized bed gasifier, a catalytic steam reforming rector, steam and air supply system, 2 stage feeding system, tar sampling and analysis system, gas condensation, gas sampling and analysis, data collection and acquisition, as well as computer-based automatic control system.Using such pilot plant, a series of experiments were carried out inclusive cold test and hot test. During those tests, the critical fluidization velocity, bed pressure profile and pressure drop were obtained referring to different sizes of bed materials and its static height. The temperature profile and preliminary testing results such as gas composition, gas yield were also obtained from hot tests. construction flow ,datum collecting and control strategy of the compositionThe above-mentioned tests indicate that the designed pilot plant can be operated well and is under the expectation for further study in the field of gasification/pyrolysis of biomass to produce hydrogen or other products.