Band 21, Heft 5

For a smelting reduction furnace, the main role of the post-combustion operation in the upper space is to supply the energy required by the endothermic reduction reaction of iron oxide occurring in the melt bath, and thus the post-combustion behavior is important in the respect of reducing the coal consumption. In this paper, based on a developed 3D model composed of the Realizable k – ε model and DO radiation model, the post-combustion characteristics in a smelting reduction furnace was studied by numerical simulation, and the effects of top lance height, top-blown hot air flowrate and nozzle inclination angle of top lance on the flow and temperature fields, CO content distribution in the upper space were investigated. The results show that with the increase of top lance height, the length and temperature of combustion flame in the upper space increase, which is beneficial to expanding the post-combustion zone and improving the post-combustion of CO gas. And as the top-blown hot air flowrate increases, the position of the maximum temperature in the upper space gradually moves down and the CO content in gas mixtures decreases, which is conducive to the heat transport back to the melt bath. In addition, a proper velocity and temperature distribution in the upper space and distribution of CO content is obtained under the nozzle inclination angle range from 10° to 15°, but a larger nozzle inclination angle reduces the velocity and temperature in the central zone.

A denitrification mathematical model was used to describe the nitrates and organic carbons use by the denitrify biomass in the Moving Bed Biofilm Reactor (MBBR). The model integrates the diffusive mass transfer mechanism as well as double substrates Monod kinetics. Preliminary experiments were realized in order to assess the operating conditions for growth of attached biomass, the determination of the optimal (COD/NO 3 -N) ratio, moreover the results of the previous study of the residence time distribution in this MBBR established the optimal hydrodynamic operating conditions with a dead volume of 22%. In this reactor, seeded with a mixed liquor from a purification station, kaldnesk1 were used as carriers. A total of 6 kinetic and stoichiometric constants under anoxic conditions were determined by batch-test pulsed respirometry; some parametric have been determined experimentally, such as Y HD, Y NO , μ ˆ HD ${\widehat{\mu }}_{\text{HD}}$ and K S , and with their values 0.4 mgCOD (mgCOD) −1 , 0.6 mg COD (mgCOD) −1 ,0.864 d −1 and 12.48 mg COD L −1 , respectively. The other constants were determined using the model fitting (using MATLAB), such as K NO3 and b HD with its values, 0.25 mg NO 3 -N. L −1 and 0.061 d −1 , respectively. The model was used to simulated different operating condition and the results included the concentration profiles of NO 3 -N, COD and X BH , which showed good agreement with the experimental ones, mainly by using the effective volume determined experimentally in the hydrodynamic study (RTD test) and which can reach 62% of the total volume under some operating. Additionally, these findings demonstrate that moving bed reactor characterization may be accomplished using in situ pulsed respirometry (MBBR).

To address the problem of late ignition and poor burnout of Foster-Wheeler down-fired boilers, this study proposed a new combustion technology, which combines adding on arch secondary air and alternately arranging the fuel-lean coal/airflow (FLCA) and fuel-rich coal/airflow (FRCA). The coal particle trajectories of FLCA and FRCA and overall aerodynamic characteristics in the furnace were studied at FRCA and FLCA ratio ( R RL ) of 5:5, 7:3, and 9:1. The results showed that even at a low FRCA ratio, the new combustion technology could still effectively ensure the penetration depth of pulverised coal/airflow. At different R RL values, the main airflow from the arch appeared in the near-wall area and could penetrate downwards into the cold ash hopper area. With an increase in the value of R RL , the deflection degree of FLCA towards the furnace wall increased, while that of FRCA decreased. At R RL of 7:3, both the penetration depth and deflection degree of FRCA and FLCA were at a high level, which was conductive to promoting the burnout and recommended in practical applications.

Mesoporous Ni/La 2 O 3 /γ-Al 2 O 3 catalysts with different La contents (0, 0.5, 1.5, 2.5, 3.5, and 4.5 wt.%) were prepared by the step-by-step impregnation method. The physicochemical properties of the prepared Ni/La 2 O 3 /γ-Al 2 O 3 catalysts were characterized by H 2 -TPR, XRD, BET, O 2 -TPO, and TG. The effect of La dosage on the catalytic performance of Ni/γ-Al 2 O 3 catalyst for dry reforming of methane was further investigated. The results show that the La content has a significant effect on the reducibility of high-valence Ni species, specific surface area, pore size, and pore volume as well as the catalytic performances. The high-valence Ni species in the NL3.5A catalyst precursor has high reducibility. And the specific surface area, pore size and pore volume of the NL3.5A catalyst are 145.9 m 2  g −1 , 11.7 nm, and 0.47 cm 3  g −1 , respectively. The catalytic activity of the series of prepared mesoporous Ni/La 2 O 3 /γ-Al 2 O 3 catalysts follows the order: NL3.5A > NL2.5A > NL4.5A > NL1.5A > NL0.5A > NL0A. Namely, the NL3.5A catalyst possesses the best catalytic activity. The CH 4 and CO 2 conversions of NL3.5A catalyst are 61.6 and 39.1% at 600 °C, respectively. Additionally, it maintains a superior recycle capability for dry reforming of methane reaction because of the high coke resistance compared with the Ni/γ-Al 2 O 3 catalyst.

In this study, an organic metal framework adsorbent was used to remove paratoluic acid from aqueous solutions. The effect of various parameters such as pH, initial concentration of paravoluic acid, contact time, and amount of adsorbent was investigated by experimental design method. Central composite design (CCD) was used to optimize paratoluic acid uptake. Initially, MIL-53 (Al) was synthesized, and characterized by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), spectroscopy, and thermogravimetry (TGA). The results of central composite design showed that pH is the most essential factor in the removal of paratoluic acid with MIL-53 (Al). The maximum removal efficiency of paratoluic acid by MIL-53 (Al) adsorbent is 93.67%, the optimal amount of adsorbent is 0.396 g, the optimal time is 35.67 min, the initial concentration is 11.12 mg L −1 . The pH is 6.6 with the desired amount 1 is. Isothermal, and kinetic models have also examined. The maximum adsorption capacity was 132.05 (mg g −1 ), and the adsorption data of MIL-53 (Al) were well consistent with the quasi-second order, and Langmuir isotherm models.

The main task of the impurity removal process is to control the oxidation reduction potential (ORP) within the range of the optimized set value. The impurity removal process is essentially an oxidation-reduction process. Oxidation reduction potential (ORP) is an external reflection of reaction state inside the impurity removal reactor. However, actual industry is time-varying, nonlinear and multimode. It is difficult to determine the appropriate dosage of impurity remover in practice. This will lead to large fluctuations in the operation mode, affecting the safety and stability of the process and the final product quality. To solve these problems, an intelligent dynamic setting control framework (IDSCF) for the multimode impurity removal process is proposed in this paper. It includes a preset module of the dosage of impurity remover based on impurity remover utilization (IRU) estimation, an operation mode detection module based on autoencoder, a normal mode adjustment module based on fuzzy logic, and an unsteady mode adjustment module based on case-based reasoning (CBR). The framework can determine the reasonable preset dosage of impurity remover and adjust the dosage according to the current operation mode of the impurity removal process. Because the operation mode is related to the residual dosage of impurity remover added over a period of time, that is, the accumulative effect of the large-scale metallurgical reactor. When calculating the preset dosage of impurity remover, the reactant accumulation ratio (RAR) is calculated, which makes the calculation of the preset value more reasonable. In addition, it can detect the unsteady modes causing large fluctuations in the process and adjust them in time. Experiments are carried out in accordance with the data of an actual cobalt removal process. The results show that this method can effectively improve the stability of the impurity removal process, control the ORP within the set range and cope with complex mode changes.

Ammonium polyphosphate (APP) is rich in nitrogen (N) and phosphorus (P), which is a raw material for the high-efficiency water-soluble fertilizer production. In this work, the water-soluble APP was directly synthesized using commercial grade-urea phosphate and urea in a microwave reactor. The effects of the molar ratio of urea to phosphate urea (UP), microwave power and reaction time on the quality of APP were also studied. Single-factor experiments indicate that with the optimal conditions: the molar ratio of 0.4, the microwave power of 720 W, and the reaction time of 9 min, the average polymerization degree of APP was 18.91, and the solubility was 6.31 g/100 g H 2 O. Orthogonal experiment indicates that the order of significant factors for APP production is molar ratio > reaction time > microwave power. Based on the results of the range analysis and analysis of variance, the optimized conditions were found at the molar ratio of 0.6, the microwave power of 720 W, and the reaction time of 9 min, the average polymerization degree of the APP was 21.7 and the solubility was 6.03 g/100 g H 2 O at 25 °C. The TGA analysis showed that the synthesized APP had a good thermal stability. Its XRD spectrum was the same as the crystalline form I.

In this paper, a heterogeneous catalytic system consisting of Co/Mn/Br/activated carbon is used to catalyze 2-nitro-4-methylsulfonyl benzoic acid (NMSBA) production from the oxidation of 2-nitro-4-methylsulfonyltoluene (NMST) by oxygen. The activated carbon (AC) is made from coconut shell with acetic acid as an activator. The experiments indicate that the best AC is made by immersing coconut shell in 12 mol L −1 HAc solution at 50 °C for 32 h with a liquid/solid ratio (mL/g) of 5:1 and then being heated in nitrogen at 800 °C for 6 h. Compared with the Co/Mn/Br/H 3 PMo 12 O 40 @CAC (CAC, commercial activated carbon originated from coconut shell) catalytic system, the Co/Mn/Br/AC catalytic system is able to gain much higher NMSBA selectivity. In spite of holding smaller surface and less acidic groups, the AC owns much more carboxyl than CAC, which is the main reason for its better performance in the preparation of NMSBA.

Based on Ansteel’s new No. 5 blast furnace (BF), the distribution rule of hot blast on the circumference of blast furnace hearth under different blast volume was studied. The results show that, the blast volume distribution rule is similar under different blast volumes, that is, there are four regions with large blast volumes at the 0°, 90°, 180° and 270° positions of the bustle pipe. Under different blast volumes, the difference of blast volume near 90° and 270° is close to 0, which has a minor effect on the uneven distribution of gas flow and circumferential asymmetry of packed bed in BF. However, the blast volume of the tuyere near the 180° is always larger than that of the tuyere near 0°, and with the increase of blast volume from 4600 to 5000 nm 3 /min, this difference keeps increasing, 0.69 to 0.95 nm 3 /min. This phenomenon will lead to an increase in the coke consumption on the 180° side, and cause a higher descending velocity of coke than that on the 0° side, this difference increases from 0.39 to 0.54 m, which could further result in the unevenness of blast volume distribution and the circumferential asymmetry of packed bed in BF. Comparing with the actual production in Ansteel, the results obtained in this work are in good agreement with the phenomenon in practical production.