Qingbo Yu

The Effects of Slag Compositions on the Coal Gasification Reaction in Molten Blast Furnace Slag

The char-CO2 gasification reactions in molten blast furnace slag were studied kinetically by the isothermal thermogravimetry using STA409PC thermal analyzer. The effects of slag compositions (SiO2, MgO, CaO, and Al2O3) on gasification reaction were investigated. The results showed that CaO has certain catalytic effects on gasification reaction; however, when the gasification reaction temperature reached a certain value, the catalytic effect of CaO on gasification could be neglected. MgO also played a catalytic role in the gasification reaction. In this experiment, the gasification reaction rate increased with increasing the MgO content from 8 to 10 mass%, whereas it decreased with increasing the MgO content from 10 to 12 mass%. SiO2 had no catalytic effect on gasification reaction.

Bio-oil production by fast pyrolysis from agriculture residue in northeastern China

In this paper, three typical agriculture residues (corn cob (CC), peanut shell (PS), and pine cone (PC)) from northeastern China were investigated for fast pyrolysis to produce bio-oil. The influences of carrier gas velocity, temperature, and particle size of biomass on bio-oil yield were studied. With the increase of carrier gas velocity, the bio-oil yield increased, but the increase rate of bio-oil yield first increased and then decreased. As temperature increased, the bio-oil yield first increased and then decreased. The variation trends of bio-oil yield with particle size for the three biomasses were different. For CC, the bio-oil yield increased with the reduction of the granularity; but it was completely opposite for PS and PC. The main components of the exhaust gas were CO2, CO, H2, and small quantities of CHx. The compounds of bio-oil were mostly with oxygen functional groups, resulting in the higher content of oxygen element, then leading to low calorific value.

Study on pyrolysis characteristics and kinetics of biomass and its components

With thermogravimetric analyzer, the pyrolysis characteristics of two kinds of biomass (pine cone (PC) and corn cob (CC)) and their main mix components (neutral detergent fiber, acid detergent fiber, and strong acid detergent fiber (SADF)) extracted by Van Soest analysis were studied under three heating rates (10, 20, and 40 K/min). Similar pyrolysis trends were obtained for the two original samples (OSs) and the same mix components, but the differences of the start, end, and reaction rate peak points, the residue ratios, and even the peak numbers of the pyrolysis reaction exist. Besides, to some extent the three components (hemi-cellulose, cellulose, and lignin) have the synergistic effect. On the basis of thermogravimetric analysis, the kinetic analysis of the original samples and the SADF (seen as lignin) was performed. The novel two-step method of model sifting was applied to select the most reasonable mechanism model. Different samples have different models, but the mechanism model of the same sample...

Pyrolysis characteristics and kinetics of lignin derived from three agricultural wastes

With thermogravimetric analyzer, the pyrolysis characteristics of three kinds of lignin from agricultural wastes were studied under three heating rates (10, 20, and 40 K/min). The increase of heating rate could advance the final pyrolysis degree and the pyrolysis reaction rate. In the main pyrolysis region, the lignin samples of corn cob (CC) and peanut shell (PS) showed two peaks of reaction rate curves, yet three peaks for the pine cone (PC) lignin. With the model-free Starink methods, it was found in the previous sections of all the lignin samples, the E values changed widely, and yet in the last sections, the E values were fairly stable. With the model-fitting methods, the kinetic parameters of CC and PS showed a good consistency: both of the lignin pyrolysis processes fitted F1 model for Coats-Redfern method and F1.5 model for Horowitz-Metzger method, and the E values of the two lignin pyrolysis were fairly close; yet, the parameters of the pyrolysis process of the PC lignin obtained were different f...

Thermogravimetric analysis of the biomass pyrolysis with copper slag as heat carrier

Thermo gravimetric analysis experiments were carried out on pyrolysis of three kinds of biomasses by temperature programming method. Employed by thermogravimetric analyzer, the effects of the type of biomass and the ratio of copper slag addition on pyrolysis were studied. Biomass pyrolysis process can be divided into four stages, dehydration, pre-pyrolysis, pyrolysis and carbonization. The experimental yields in this paper were modeled by CH4, C2H6, C3H8, C2H4 and C3H6, considering first-order primary reaction and reactions of alkanes and alkenes. Copper slag is beneficial for biomass pyrolysis. With Coats–Redfern method, nonlinear regression of biomass catalytic pyrolysis showed that reaction mechanism of pyrolysis process confirms well with shrinking core model (A3). The kinetic parameters and equations were also calculated. Copper slag promotes both the primary reactions of biomass pyrolysis and the Cracking reactions of alkanes and alkenes, but it cannot decrease the activation energy effectively.

The Reduction Kinetic of the Combined Cu-Based Oxygen Carrier Used for Chemical Looping Gasification Technology

The oxygen uncoupling property of the oxygen carrier is essential for the chemical looping gasification process. In this paper, the combined Cu-based oxygen carrier were prepared by mechanical mixing method. XRD and SEM were used to characterize the oxygen carrier prepared. TG experiments were performed in a thermal analyzer to investigate the oxygen uncoupling property. The XRD pattern of the fresh oxygen carriers showed that the phases of the oxygen carriers were stable. The active phase of oxygen carrier was CuxMn3-xO4. With the increasing of heating rate, the starting and ending temperatures of the reduction reaction increased. However, the reaction time decreased and the reduction rate increased. With the increasing of oxygen concentration, the starting temperatures of the reduction reaction shifted to high level. Temperature had great effect on the reduction rate and the reduction rate increased with increasing of the reduction temperatures.

Syngas production through biomass/CO2 gasification using granulated blast furnace slag as heat carrier

The emerging technology of biomass/CO2 gasification to recover waste heat from granulated blast furnace (BF) slag for solving the energy crisis and relieving the greenhouse effect was proposed. The gasification performances of biomass/CO2 in granulated BF slag under different reaction temperatures and mole ratios of CO2 to fixed carbon in the biomass (CO2/C) were investigated, and the effects of granulated BF slag on the biomass/CO2 gasification reaction were illuminated. The results showed that with higher gas content, gas yield, and lower heating value (LHV) were obtained with higher reaction temperature. When CO2/C was up to 1, the maximum concentrations of CO and H2 were obtained, and the LHV was near maximum value. Granulated BF slag could promote biomass/CO2 gasification reactions to some degree and also could act as a catalyst in the reaction. Under the optimum conditions, a reaction temperature reaching 1000 °C, CO2/C of 1 and using granulated BF slag as a heat carrier, the maximum syngas concentr...

Particles Flow Behavior Around Tubes in Moving Bed

Moving bed has been widely used in the field of heat and mass transfer and reaction between solid particles and gas. In order to enhance the heat exchange coefficient, there will be tube banks inserted in the moving bed. In the process of drying ammoniates particles or heat recovery from high-temperature particles with moving bed, the particles flow behavior around the tube banks is significant. In this paper, the particles flow behavior around the tube banks is investigated, and all the results can provide guidance for the design and operation of a moving bed.

Direct Reduction of Copper Slag Composite Pellets Within Lignite Using Biomass as Binder

The resource utilization of copper slag is an attractive option of iron resource. Thermal energy recovery and direct reduction (TER-DR) system was proposed in this study. By theoretical analysis, the exergy efficiency of this system can reach to 57.3%. To investigate the feasibility of TER-DR system, copper slag composite pellets within lignite were prepared. As a new binder, pine sawdust was added into the pellets. The diameter of pellets was 20 mm in experiments and the compressive strength of them was up to 831 N when the addition ratio of biomass was 29%. The results showed that the overall iron recovery reached to 90% and the separated iron concentrate was up to 93.5% when the temperature is at 1423 K for 90 min with CaO addition ratio of 0.3. The process reduces the secondary environmental pollution of copper slag and will be applied well in the future.

Flow Characteristic of Two-Phase Bubble Reactor for Slag Waste Heat Recovery

In order to recover the waste heat of molten blast furnace slag, a reactor with top-submerged lance was established. The numerical simulation and experiment study of the flow characteristic in the reactor were conducted. The mathematical model of reactor was established and the Euler-Euler model was employed to simulate the gas-liquid flow in molten slag bath. Meanwhile, the experiment results were obtained and compared with the simulation to testify the accuracy of the established model. According to the bubble behavior in bath, there were four stages: initial expansion stage, bubble detachment stage, freedom lift up stage and bubble broken stage. When the flow field in bath fully developed, the gas fraction decreased with the increasing of bath depth. During injection process, the area near the nozzle and lower the bath would first generate two symmetric heliciform flow regime, and then the flow regime in whole bath would become irregular because of bubble lifting up and rupturing. The gas fraction in bath, the average velocity and turbulence energy of slag would decrease before it increased to maximum and then it would keep fluctuate in a range.