Numerical Simulation And Parameter Optimization Of KW-Scale Bituminous Coal Chemical Looping Gasification Pilot Plant

The chemical looping gasification(CLG)technology uses oxygen carriers as the circulation medium between the fuel reactor and the air reactor to carry oxygen and heat,which can produce clean gas with high efficiency and low consumption.In this paper,we modeled the kW CLG pilot plant based on the computational particle fluid dynamics(CPFD)method,determined the cold operation interval for obtaining the particle flow pattern in the bubble bed,and optimized the superficial gas velocity,coal particle size,and initial bed height parameters.(1)The oxygen release characteristics and CLG reaction performance of four ores were evaluated on a thermogravimetric analyzer and an intermittent fluidized bed.The thermogravimetric experiments showed that the actual oxygen loading rate of ilmenite was slightly lower than that of Hebei manganese ore and much higher than that of hematite and Guangxi manganese ore,which was about 12.4%.The ilmenite showed the highest reactivity in the fluidized bed experiments,with a carbon conversion rate higher than 65%within 5 min in 10 cycles,and the most stable syngas fraction was obtained in each cycle.SEM analysis of the ore before and after the cycling experiments showed that ilmenite showed slight surface sintering and small changes in surface morphology in 10 cycles,which was suitable as an oxygen carrier for the study of the kW CLG plant.(2)The cold flow model of the kW CLG pilot plant was established using the CPFD method to investigate the influence of the initial parameters in the oxygenate-carrier-gasifier system on the gas-solid flow characteristics of the fuel reactor,respectively.The simulation results show that the process of regulating the gas-solid phase in a bubbling bed particle flow pattern requires a dynamic balance between the gas-phase dynamics and the solid-phase resistance.The cold conditions of 0.106～0.125 mm particle size,0.36～0.48 m/s superficial gas velocity,and 130～140 kPa gas inlet pressure were determined to obtain a stable bubble rise rate.(3)The thermal flow reaction model of the fuel reactor of the kW CLG pilot plant was established.Firstly,the coal handling capacity under the standard operating condition of the plant was determined to be 0.5 g/s,and the power of the plant at this time was about 15 kW.The simulation results showed that the synthesis gas uniformly released in the bed by the CLG-related reaction formed an additional traction effect on the particles in the bed so that the distribution of coal particles in the bed under the hot condition was lower than that under the cold condition.After optimization,when the operating conditions are 0.36-0.48 m/s superficial gas velocity,0.3-0.4 mm coal particle size,and 0.6-0.8 m initial bed height,sufficient contact is obtained between coal particles,oxygen carrier bed particles,and gas phase to obtain carbon conversion rate and cold gas efficiency.