The entrained-flow gasifier for fine slag can be applied for large-scale industrial use of gasification fine slag. The gas-solid two-phase flow characteristics of a 10000 Nm3/h fine slag entrained-flow gasifier were studied using a cold flow experiment system and a PDA (Phase Doppler Anemometry) measurement system to improve the gasifier's gasification performance. The flow field in the gasifier was compared in detail with various burner bias angles. The results reveal that when the burner is arranged biased in the same direction, there is an obvious central tangent circle in the velocity field of the horizontal section where the burner is positioned. When the burner's bias angle is 2°, the tangential area is the smallest, the upward movement of particles is the greatest, the particle updraft rate is up to 0.47, and the turbulence intensity is more than when the bias angle is 4° or 6°. When the bias angle is 2° in the vertical section of the upper gasifier, the downward-moving particle velocity is the largest, the downward-moving particle concentration is the greatest, the airflow swirl intensity is the smallest, and the swirl is the weakest, which is not conducive to the formation of slag layer on the membrane wall. When the bias angle is 6° in the vertical section of the lower gasifier, the tangential velocity of the airflow is the greatest, the swirl intensity is the highest, and the axial velocity is greater than the axial velocity of 4° and 2°. The particles' residence time in the gasifier gets shorter, which hinders the complete reaction of the fine slag.
与煤共气化是实现煤直接液化残渣萃余物(ER)资源化利用,提升煤直接液化工程整体经济性的重要途径.气化过程灰渣的流动性是影响气化操作条件的重要参数,利用灰熔点仪、高温旋转黏度计、XRD及SEM等测试手段考察了 ER与煤共气化的灰渣熔融特性、黏温特性及晶体特性,并结合壳牌气化装置入炉煤配比和操作条件,从灰化学角度确定ER的最佳掺混比例及气化操作窗口.结果表明:ER属于高灰、高铁、高钙、高硫物质,且其灰成分偏碱性,随煤中ER添加量增大,掺混后的灰分、铁含量和硅铝比逐渐增大.当萃余物质量分数超8％,全液相温度T1iq降低,但萃余物添加量超20％时,熔渣类型从玻璃渣转变为结晶渣.XRD与SEM分析结果表明钙长石的析出造成熔渣类型改变,钙长石的析出主要是因为萃余物的添加使熔渣黏度降低,熔渣中团簇的扩散能力增强,有利于结晶行为.结合Shell气化炉的操作条件及对煤灰中铁含量的要求,当萃余物添加量为10％时,共气化熔渣适合气化炉排渣,对应的排渣窗口为1 335～1 557℃.该研究结果为ER与煤共气化提供指导,提高煤直接液化流程的经济性.
The preparation method of large-area molten carbonate fuel cell matrix and electrode was developed, and the assembly and test operation method of 10 kW level molten carbonate fuel cell stack was proposed in view of the difficulties in the preparation and matching characteristics of the key materials during the development of large-area molten carbonate fuel cell and its large power stack. A 10 kW class MCFC stack with 120 cells and an effective area of 0.2 m~2 for each cell was assembled and operated. During the constant voltage discharge test, the maximum output power reaches 16.51 kW and the current density is above 95 mA/cm~2. Through multiple experimental studies and analysis, an effective online evaluation method for the baking effect of MCFC electrolyte matrix is obtained, which makes the matrix, electrode and molten salt electrolyte in the molten carbonate fuel cell body matched well, and has important guiding significance for improving the success rate and the long cycle operation life of MCFC stack assembly. Meanwhile, the study of MCFC stack body and performance test methods will provide effective theoretical and experimental guidance for the subsequent development of larger power molten carbonate fuel cell power generation system, and have important significance in the commercial demonstration and promotion of MCFC.
To master the pollutant emission characteristics of a 350 MW supercritical CFB boiler under mixed combustion of multi-element low-calorific value coal including coal slime and coal gangue, taking a 350 MW supercritical CFB boiler of a power plant as the research object, and based on the measured data of on-site operation, the formation and emission characteristics of SO 2 , NO x and dust in flue gas were studied against the boiler load rate between 30% and 99%. Additionally, the key operated parameters including boiler operating load, average bed temperature, excess air coefficient and fluidizing air rate on its generation and emission level were investigated. The test results reveal that the flue gas pollutant emissions of the CFB unit can meet the emission standards within the load range of 30%-99% at total discharge outlet. The emission concentration of SO 2 , NO x basically decreases first and then increases rapidly with the decrease of boiler load. The concentration of dust emission decreases with the decrease of boiler load, and the dust emission concentration decreases with the reduction of boiler load. Among the key operating parameters studied, the boiler bed temperature plays a leading role in the emission level of SO 2 , NO x . The emission concentration of SO 2 and NO x is higher with the lower average bed temperature and the larger excess air coefficient, and the emission concentration is basically positively correlated with the excess air coefficient and fluidization air rate. Considering comprehensively, it is recommended that the average bed temperature of the boiler should be properly controlled above 800 ℃, and the excess air coefficient should be stabilized less than 1.3. The way of flue gas recirculation can be used to reduce the oxygen concentration of the flue gas under low load on the basis of the maintaining the normal fluidization of the material.
Aiming at the high temperature corrosion problem of the water wall of a 350 MW low nitrogen boiler in a power plant, the simulation study was carried out to adjust the air distribution and increasing near-wall air. The relationship between the concentration of reducing gases CO, H 2 S and NO x in the furnace was simulated when the burn-out air rate was 38%, 33% and 27% respectively, and the effect of increasing the wall air on the concentration of reducing gases near the water wall was simulated. The results show that the burn-out air rate is reduced from 38% to 33%, which can reduce the concentration of reducing gases CO and H 2 S in the furnace by 20% without significantly increasing the amount of NO x , and slow down the high-temperature corrosion of the water wall. Reducing the burn-out air rate from 38% to 27% can increase the oxygen concentration in the main combustion zone, reduce the production of CO and H 2 S, and slow down the high-temperature corrosion of the water wall, but the NO x concentration will increase significantly. The high-temperature corrosion area in the furnace is mainly located between the UAP nozzle of the compact burnout air and the SOFA3 nozzle of the intermediate burnout air. The near-wall air can be added on both sides of the UAP nozzle of the compact burnout air. The simulation results show that the concentration of CO and H 2 S near the water wall can be reduced by increasing the near-wall wind with the same rotation direction as the main flow, and there is the small effect on the flow field. Due to the high concentration of CO near the water wall, the flow of near-wall air on both sides is larger, which has better effect on reducing CO near the water wall. The coverage area of near-wall air on both sides is larger for high-temperature corrosion area, while the concentration of H 2 S near the water wall is lower. There is no obvious difference between the single-side near-wall air and the double-side near-wall air in reducing the H 2 S of the water wall, but the double-side near-wall air will disturb the distribution of the flow field, which is not conducive to pulverized coal combustion.
