Experimental Study On Coal Partial Gasification And Sulfur Transformation In Fluidized Bed

As a clean coal technology,coal partial gasification and residual char combustion hasbeen widely applied to the research and development of advanced power systems. And italso has broad application prospects in other industrial technology development such asUltra-high temperature fume. Therefore, a detailed study about coal partial gasificationcharacteristics was carried out in a small fluidized bed. ASPEN PLUS was also used tosimulate a process, developed by SKLCC, aiming at providing ultra-high temperature fume,in order to provide strong support for feasibility of the process.Firstly, the experiments were carried out in a small-scale fluidized bed equipment toinvestigate the coal partial gasification characteristics and sulfur migration. In this section,partial gasification experiments were conducted under air and air-steam gasifying agentrespectively, and several key working conditions were studied on the influence of coalpartial gasification and sulfur transformation. The results showed that, the temperature is akey parameter affecting the gasification characteristics. With the temperature increasing,the yield of H₂and CO significantly increased and the yield of CO₂decreased. The coalpartial gasification characteristics have significant differences under different gasificationagent.Under air-steam gasification, the decomposition reaction of the carbon with steamwas enhanced.Therefore, the yield of H₂was significantly increased. The carbonconversion efficiency and cold gas efficiency were also improved. During gasification,mostof the sulfur has been released retaining less than half in the coke. The content ofmethylmercaptan was very high, which may has a great relationship with the coal used.Adding steam in the gasifying agent promoted the release of sulfur.Then, based on the partial gasification expeiment data, experiments were carried out inthe same reactor to research on the desulfuration characteristics during partial gasification.The char combustion characteristics were studied in TGA and the sulfur releasecharacteristics during char combustion were aslo studied in a fixed bed reactor. The resultsshowed that, calcium-based sorbent has limited catalysis on coal air-steamgasification.After desulfurization,the solid products had a relatively low sulfur content ofless than50%proving that the desulfurization effect was relatively poor. This may becaused by the sintering of sorbent after calcination. Very little sulfur released in the combustion process of the gasification solid product.Finally, ASPEN PLUS was used to simulate ultra-high temperature fume technologicalprocess and the influence of key working conditions on the technology were studied for thepurpose of supporting feasibility of the process. The simulation found that when inatmospheric pressure,the gasification temperature between800⁹00℃,carbon conversionrates between0.4⁰.6,ER between0.2⁰.25,steam to coal ratio under0.5g/g,the effect ofthe gasification sufficiently meet the demand of ultra-high temperature flue gas process. Byadjusting the gasification temperature and the amount of steam,a large range of adjustmentof the temperature of the ultra-high-temperature flue could be achieved.